USRE40963E1 - Method for plasma processing by shaping an induced electric field - Google Patents

Abstract

A method for achieving a highly uniform plasma density on a substrate by shaping an induced electric field including the steps of positioning the substrate in a processing chamber, supplying a high frequency power to a spiral antenna generating an induced electric field in the processing chamber, generating a plasma in the processing chamber, and shaping the electric field with respect to the substrate to achieve a uniform distribution of plasma on the substrate being processed.

Description

This application is a Division of application Ser. No. 08/788,636 filed on Jan. 27, 1997 now U.S. Pat. No. 5,938,883 on Aug. 17, 1999, which is a continuation of Ser. No. 08/180,281 filed Jan. 12, 1994, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plasma processing apparatus for performing a predetermined process using a plasma.

2. Description of the Related Art

In the manufacture of, for example, a semiconductor integrated circuit, plasma is utilized in the steps of ashing, etching, CVD and sputtering treatments in order to promote the ionization of a processing gas, the chemical reaction, etc. It was customary in the past to use in many cases a parallel plate type plasma apparatus using a high frequency (RF) energy as a means for generating a plasma. Recently, proposed is a high frequency induction type plasma processing apparatus using a substantially planar spiral antenna because the plasma processing apparatus of this type permits a desirable energy density distribution of the plasma, makes it possible to control highly accurately the bias potential between the plasma and the susceptor, and is effective for diminishing the contamination with the heavy metal coming from the electrode. As described in, for example, European Patent Laid-Open Specification No. 379828, the high frequency induction type plasma processing apparatus comprises a processing chamber and a wafer-supporting plate positioned within the processing chamber. In general, the upper wall portion, which is positioned to face the wafer-supporting plate, of the processing chamber is formed of an insulating material such as a silica glass. Also, a spiral antenna is fixed to the outer wall surface of the insulating region of the processing chamber. A high frequency current is allowed to flow through the antenna so as to generate a high frequency electromagnetic field. The electrons flowing within the region of the electromagnetic field are allowed to collide against neutral particles within the processing gas so as to ionize the gas and, thus, to generate a plasma.

In the high frequency induction type plasma processing apparatus, a plasma is formed within the inner space of the processing chamber right under the spiral antenna. Concerning the density distribution of the plasma thus formed relative to the intensity of the electric field, the highest plasma density is formed about midway between the center and the outermost region in the radial direction of the substantially planar spiral antenna, and the plasma density is gradually lowered toward the center and toward the outermost region of the spiral antenna. In other words, the plasma density is uneven in the radial direction of the spiral antenna. The plasma of the uneven distribution is the radial direction is diffused from the higher density region toward the lower density region, with the result that the plasma density is made considerably uniform near a semiconductor region positioned below the plasma-forming region.

In the conventional plasma processing apparatus of this type, however, the plasma diffusion in the radial direction tends to cause the plasma density in the central region of the semiconductor wafer to be higher than in the outer peripheral region of the wafer, leaving room for further improvement in the uniformity and reproducibility of the plasma processing.

SUMMARY OF THE INVENTION

The present invention which has been achieved in view of the situation described above, is intended to provide a high frequency induction type plasma processing apparatus which permits a highly uniform plasma density in the region around an object to be processed and is excellent in its uniformity and reproducibility of the plasma processing.

According to a first aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber;
  • an induction member arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction member and the processing chamber, and a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed; and
  • a paramagnetic member arranged to overlap at least partially with the induction member.

According to a second aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber; and
  • an induction member arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction member and the processing chamber, a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed, and the induction member being spiral such that a space is provided in its central region.

According to a third aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber; and
  • an induction member arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction member and the processing chamber, a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed, and the induction member being spiral and having an outer region and a central region differing from each other in its pitch.

According to a fourth aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber; and
  • at least two induction members each arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction members and the processing chamber, a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed, each of the two induction members forming a single loop, and the two induction members being arranged in a concentric configuration.

According to a fifth aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber; and
  • two induction members each arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction members and the processing chamber, a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed, and one of the two induction members forming a single loop with the other being spiral, these two induction members being arranged in a concentric configuration.

According to a sixth aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber; and
  • two induction members each arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction members and the processing chamber, a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed, and each of the two induction members being spiral, these two induction members being arranged in a concentric configuration.

Further, according to a seventh aspect of the present invention, there is provided a plasma processing apparatus, comprising:

• • a processing chamber in which an object to be processed is arranged;
  • a processing gas introducing means for introducing a processing gas into the processing chamber;
  • an induction member arranged in that region on the outer surface of the processing chamber which is positioned to correspond to the object to be processed, an insulator being interposed between the induction member and the processing chamber, and a high frequency power being supplied to the induction member so as to form an induction electric field near the object to be processed; and
  • a magnetic member arranged in the vicinity of the induction member outside the processing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an oblique view showing a plasma processing apparatus according to a first embodiment of the present invention;

FIG. 2 is a cross sectional view showing the plasma processing apparatus shown inFIG. 1;

FIG. 3 shows the distribution of a plasma density on the surface of a semiconductor wafer used as an object to be processed;

FIG. 4 schematically shows a single loop antenna as an example of an induction member used in the apparatus according to the first embodiment of the present invention;

FIG. 5 schematically shows a spiral antenna having the central portion cut away, said antenna exemplifying the induction member used in the apparatus according to the first embodiment of the present invention;

FIG. 6 schematically shows a spiral antenna having the central portion cut away, said antenna exemplifying an induction member used in the apparatus according to a second embodiment of the present invention;

FIG. 7 schematically shows a spiral antenna with the pitch of turns of the antenna conductor changed in its radial direction, said antenna exemplifying an induction member used in the apparatus according to the second embodiment of the present invention;

FIG. 8 schematically shows an antenna of a double ring structure, which exemplifies an induction member used in the apparatus according to a third embodiment of the present invention;

FIG. 9 schematically shows an antenna consisting of two spiral antenna members arranged to collectively form a large spiral structure, said antenna exemplifying an induction member used in the apparatus according to the third embodiment of the present invention;

FIG. 10 schematically shows an antenna consisting of a single loop antenna member and a spiral antenna member arranged to be concentric with the single loop antenna member, said antenna exemplifying an induction member used in the apparatus according to the third embodiment of the present invention;

FIG. 11 is a cross sectional view showing a plasma processing apparatus according to a fourth embodiment of the present invention;

FIG. 12 is a plan view showing the plasma processing apparatus shown inFIG. 11;

FIG. 13 schematically exemplifies a magnetic field forming means used in the apparatus shown inFIG. 11;

FIGS. 14 to16 show other examples of the magnetic member used in the apparatus according to the fourth embodiment of the present invention;

FIGS. 17 and 18 show other examples of the induction member used in the apparatus according to the fourth embodiment of the present invention;

FIGS. 19A,19B and19C are an oblique view, a back view and a cross sectional view, respectively, of a shower head for introducing a processing gas into the processing chamber included in the apparatus of the present invention;

FIGS. 20 and 21 schematically show modifications of the induction member used in the apparatus of the present invention;

FIG. 22 is a cross sectional view showing another plasma processing apparatus using an induction member;

FIG. 23 is an oblique view showing the plasma generating section included in the apparatus shown inFIG. 22;

FIG. 24 is a horizontal cross sectional view showing the plasma generating section included in the apparatus shown inFIG. 22;

FIGS. 25 and 26 are cross sectional views each exemplifying a gas supply mechanism from a first gas supply tube into the processing chamber, said mechanism being included in the apparatus shown inFIG. 22;

FIG. 27 is a cross sectional view showing a modification of the apparatus shown inFIG. 22; and

FIG. 28 schematically shows an antenna used in the apparatus shown in FIG.27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Let us describe some preferred embodiments of the present invention with reference to the accompanying drawings. First of all,FIG. 1 is an oblique view schematically showing a plasma processing apparatus according to a first embodiment of the present invention.FIG. 2 is a cross sectional view showing the apparatus shown in FIG.1.

As shown inFIG. 1, the plasma processing apparatus of the present invention comprises aprocessing chamber10 which is cylindrical and is hermetically sealed. Each of the bottom wall and side wall of theprocessing chamber10 is formed of a metal, e.g., aluminum. On the other hand, anupper wall12 of theprocessing chamber10 is formed of an insulator such as silica glass or a ceramic material. Where theupper wall12 is formed of a transparent silica glass, it is possible to visually observe the light-emitting state of a plasma within theprocessing chamber10. In another embodiment of the present invention, the insulator (i.e. dielectric) is a dielectric plate member positioned between the spiral antenna and the substrate.

A disc-like or columnar supporting table (i.e., susceptor)14 is arranged in the central portion of the bottom wall of theprocessing chamber10. A semiconductor wafer W, i.e., an object to be processed, is disposed on the upper surface of thesusceptor14, which is made of, for example, aluminum and having the surface subjected to an anodic oxidation treatment.

Where the plasma processing apparatus shown in the drawing is used as an etching apparatus, a highfrequency power source18 of, for example, 13.56 MHz for the etching treatment is connected to thesusceptor14 via acapacitor16 acting as a matching circuit. A cooling water for preventing an excess heating by the high frequency power is supplied from a cooling water supply source (not shown) into an inner region of thesusceptor14. A high frequency bias power is applied appropriately from the highfrequency power supply18 to thesusceptor14 depending on the kind and pressure of the processing gas used so as to accelerate the ion stream within a plasma and make the ion stream uniform.

As shown inFIG. 2, a focusingring35 made of quartz is arranged on the upper surface of thesusceptor14 within theprocessing chamber10 in a manner to surround the semiconductor wafer W acting as an object to be processed. The upper surface of the focusingring35 is positioned higher than the upper surface of the wafer W. The focusingring35 serves to collect the plasma formed above thesusceptor14 onto the upper surface of the semiconductor wafer W so as to promote the plasma processing efficiency. In the case of, for example, an etching treatment, the focusingring35 permits promoting the etching rate. The focusingring35 also serves to prevent the exposed portion, which is not covered with the wafer, of thesusceptor14 made of aluminum from being etched to generate dust.

Anelectrostatic chuck30 is provided in the wafer-holding surface of thesusceptor14. Theelectrostatic chuck30 comprises acopper foil31 acting as an electrode and an insulating film, e.g., a polyimide film, covering thecopper foil31. It follows that the wafer W is electrostatically attracted accurately to and firmly held by theelectrostatic chuck30. ADC power supply32 is connected to theelectrostatic chuck30. A DC voltage of, for example, 2 kV is applied from theDC power source32 to theelectrostatic chuck30, with the result that the wafer W is held by theelectrostatic chuck30 without fail.

A gas inlet port10a is formed in an upper part of the side wall of theprocessing chamber10, and agas supply pipe20 is connected to the gas inlet port10a. A processing gas is supplied from agas supply source37 into theprocessing chamber10 through thegas supply pipe20. In this case, the processing gas to be supplied differs depending on the kind of the treatment applied to the object. In the case of, for example, an etching treatment, an etching gas such as a CHF₃gas or a CF₄gas is supplied into theprocessing chamber10. In the embodiment shown in the drawing, the apparatus comprises a singlegas supply source37 and a singlegas supply pipe20. Needless to say, however, a plurality of gas supply sources and a plurality of gas supply pipes are connected to theprocessing chamber10 in the case where a plurality of different kinds of gases are used for the treatment.

A gas exhaust port10b is formed in a lower part of the side wall of theprocessing chamber10. Agas discharge pipe22 is connected to the gas discharge port10b. A gas discharge system including a vacuum pump, etc. is connected to thegas discharge pipe22 so as to maintain a predetermined degree of vacuum within theprocessing chamber10.

A spiralhigh frequency antenna24 acting as an induction member is mounted to the outer surface of theupper wall12 of theprocessing chamber12. Theantenna24, which is made of a conductive wire material or a conductive tubular material, is positioned to face the semiconductor wafer W mounted on thesusceptor14 arranged within thechamber10. It is desirable for theantenna24 to be made of copper which exhibits an excellent cooling property. A high frequency voltage of, for example, 13.56 MHz is applied from a highfrequency power supply28 for forming a plasma to theantenna24 through acapacitor26 acting as a matching circuit. To be more specific, the high frequency voltage noted above is applied between an inner terminal24c and anouter terminal24b of theantenna24. As a result, a high frequency current i_RFflows through theantenna24 so as to form an induced electric field in the free space right under theantenna24 within theprocessing chamber10 and, thus, to form a plasma of the processing gas, as described herein later. It should be noted that the highfrequency power supplies18 and28 are controlled by acontroller36.

In the embodiment shown inFIGS. 1 and 2, a circularthin plate30 made of a paramagnetic metal such as copper is interposed between the central portion of thehigh frequency antenna24 and thesilica glass12, and an electrical insulator (not shown) is interposed theantenna24 and theplate30. The diameter of the circularthin plate30 is determined appropriately in view of the shape and size of theantenna24, the output power of the highfrequency power supply28, the diameter of the semiconductor wafer W, the distance between theantenna24 and the semiconductor wafer W, etc. As described herein later, an alternating magnetic field B is controlled in the free space within theprocessing chamber10 by the circularthin plate30. As a result, an alternating electric field E induced in the free space noted above is controlled so as to permit diffusion of a plasma. It follows that the plasma density is rendered uniform in the surface region of the semiconductor wafer W.

Let us describe with reference toFIG. 2 how a plasma is formed and how a plasma processing is applied in the plasma processing apparatus of the construction described above.

In the first step, a semiconductor wafer W acting as an object to be processed is transferred from a load lock chamber (not shown) adjacent to theprocessing chamber10 into thechamber10 which is evacuated in advance to a vacuum of, for example, 10⁻⁶Torr. The semiconductor wafer W thus introduced into thechamber10 is held by theelectrostatic chuck30.

In the next step, a predetermined processing gas such as a CHF₃gas or a CF₄gas is introduced into theprocessing chamber10 through thegas supply pipe20. In this step, the pressure within thechamber30 is controlled to be, for example, 10⁻³Torr. Under this condition, a high frequency voltage is applied from the highfrequency power supply28 to thespiral antenna24, with the result that a high frequency current i_RFis caused to flow through thespiral antenna24. Flow of the high frequency current i_RFpermits generation of an alternating magnetic field B around the antenna conductor. A majority of the magnetic fluxes thus formed run in a vertical direction through the central portion of the antenna so as to form a closed loop. The alternating magnetic field B induces an alternating electric field E right under theantenna24. The induced alternating electric field E is substantially concentric and runs in a circumferential direction. What should be noted is that electrons are accelerated in the circumferential direction by the alternating electric field E and collide against the neutral particles within the processing gas so as to ionize the gaseous molecules and, thus, to form a plasma.

The plasma thus formed right under theantenna24 has the highest density substantially midway between the center and the outermost region in the radial direction of theantenna24, as schematically shown in FIG.2. In other words, the plasma density is gradually lowered from the highest density region noted above toward the center and toward the outermost region in the radial direction of thespiral antenna24.

In the embodiment shown in the drawing, an eddy current flows within thecopper plate30 in a manner to obstruct the passage of the magnetic fluxes B therethrough with the result that the magnetic fluxes B are unlikely to run through the central portion of theantenna24. As shown inFIG. 2, the magnetic flux lines B pass through the silica glass12 (i.e., a dielectric), which is disposed between thespiral antenna24 and the substrate W. It follows that the magnetic fluxes B run outside magnetic fluxes B′ denoted by dotted lines, i.e., the magnetic fluxes B′ in the absence of thecopper plate30. This causes a plasma forming region P right under theantenna24 to be displaced to the outside in the radial direction of a plasma forming region P′ denoted by a dotted line, i.e., the plasma forming region P′ in the absence of thecopper plate30.

As described previously, the plasma is diffused from a higher density region toward a lower density region in the absence of thecopper plate30 so as to make the plasma density uniform in the vicinity of the semiconductor wafer W. As a result, the plasma density in the central region of the wafer W is rendered higher than in the outer peripheral region of the wafer, as denoted by “Pd′” in FIG.3. It follows that a uniform treatment can be performed on the wafer surface.

On the other hand, where thecopper plate30 is disposed as shown inFIG. 2, formed is the plasma forming region P which is displaced to the outside in the radial direction of the plasma forming region P′ denoted by a dotted line, which is formed in the absence of thecopper plate30. As a result, the plasma is diffused both in the radial direction and in the vertical direction so as to make the plasma density uniform in the vicinity of the semiconductor wafer W. It follows that the plasma density is rendered substantially uniform in the vicinity of the surface of the semiconductor wafer W, as denoted by “Pd” in FIG.3. Since the plasma density is substantially uniform, the active species within the plasma such as the ions and electrons are supplied uniformly to the entire surface region of the semiconductor wafer W, making it possible to apply a predetermined plasma processing uniformly to the entire surface of the wafer.

When it comes to, for example, a plasma etching treatment, the gaseous molecules excited by the plasma into an active state are enabled to perform a chemical reaction with the substance of the workpiece. In this case, the reaction product is vaporized so as to cause the substances on the wafer surface to be taken away. In the case of a CVD treatment, the gaseous molecules excited by the plasma are allowed to react each other. In this case, the reaction product is deposited on the wafer surface so as to form a CVD film.

As exemplified above, a plasma is allowed to act with a uniform density on the entire surface of the semiconductor wafer W in the plasma processing apparatus of the present invention in any of the plasma processings, making it possible to achieve a uniform processing on the wafer surface.

When the plasma processing applied to the wafer W is finished within theprocessing chamber10, the residual gas and the residual reaction product are exhausted out of theprocessing chamber10 by theexhaust system38, followed by taking the semiconductor wafer W disposed on thesusceptor14 out of theprocessing chamber10 by using a transfer arm and subsequently putting the semiconductor wafer W in the load lock chamber.

As described above, the plasma processing apparatus shown inFIGS. 1 and 2 comprises themetal plate30 formed of a paramagnetic metal such as copper, which is arranged to overlap at least partially with thespiral antenna24 acting as an induction member, e.g., overlap with the central portion of theantenna24. What should be noted is that thecopper plate30 serves to weaken the magnetic fluxes so as to weaken the alternating electric field in that region within the free space of the processing chamber which corresponds to thecopper plate30, leading to a lower density of the plasma formed. Where thecopper plate30 is arranged in the central portion of theantenna24, the plasma forming region P right under theantenna24 is displaced outward in the radial direction, with the result that the plasma density is made uniform on the surface of the semiconductor wafer W. It follows that the apparatus of the present invention makes it possible to apply a plasma processing uniformly and with a high reproducibility to the wafer W.

In the embodiment described above, theantenna24 used as an induction member is spiral. However, it is also possible to use an antenna in the form of a single loop, i.e., a ring-like antenna, as shown in FIG.4. In the case of using such a ring-like antenna, it is also possible to form an alternating electric field as in the case of using a spiral antenna, making it possible to form a relatively uniform plasma. It is also possible to use a modified spiral antenna as shown in FIG.5. In this case, the central portion of the spiral configuration is cut away to provide the modified spiral antenna. In the case of using the modified spiral antenna as shown inFIG. 5, the diameter of the space region in the central portion is determined appropriately in view of the number of turns of thespiral antenna24, the output power of the highfrequency power supply28, the diameter of the semiconductor wafer W, the distance between theantenna24 and the wafer W, etc.

The shape of the member formed of a paramagnetic metal need not be restricted to a plate. It should also be noted that it suffices for the paramagnetic metal member to be arranged in the vicinity of the antenna acting as an induction member. For example, the paramagnetic metal member may be arranged in the central portion of the antenna as in the embodiment shown inFIGS. 1 and 2 and in other regions. Further, the paramagnetic metal member may be arranged in a plurality of portions, as required, e.g., both in the central portion and outer peripheral region of the antenna. Still further, the paramagnetic metal member may be arranged to overlap completely with the antenna.

Let us describe a second embodiment of the present invention. The basic construction of the plasma processing apparatus according to the second embodiment is substantially equal to that of the first embodiment described above. In the second embodiment, however, a paramagnetic metal is not used for controlling the plasma density. In place of using a paramagnetic metal, the state of the spiral antenna is changed so as to control the plasma density in the plasma processing apparatus of the second embodiment.

FIG. 6 shows that theantenna24 acting as an induction member is spiral and has a space region in the central portion. In thespiral antenna24 having a space region in the central portion, the number of magnetic fluxes passing in the vertical direction through the central portion of the antenna is decreased, leading to reduction in the electric field of the alternating electric field induced right under the spiral antenna. It follows that the plasma forming region P is displaced toward the outside in the radial direction of the antenna, as in the first embodiment. The displacement of the plasma forming region P permits making the plasma density uniform as in the first embodiment. In this case, it is necessary to enlarge the diameter R of the space region in the central portion of the antenna, compared with the diameter in the case ofFIG. 5, because the paramagnetic metal member Included in the first embodiment is not included in the embodiment of FIG.6. For example, it is necessary to select the diameter R equal to the diameter of the wafer W, e.g., 6 inches. Incidentally, the diameter of the free space region in the central portion of the antenna is determined appropriately in view of the number of turns of theantenna24, the output power of the highfrequency power supply28, the diameter of the semiconductor wafer W, the distance between theantenna24 and the wafer W in the case of the antenna shown inFIG. 6, too.

In thespiral antenna24 shown inFIG. 7, the pitch of turns of the antenna conductor is made uneven in the radial direction of theantenna24. As shown in the drawing, the pitch is shorter in the outer region and is made gradually longer toward the center of the antenna. According to the particular spiral structure, concentric alternating electric field induced right under the antenna is rendered relatively weaker toward the central portion, with the result that the plasma forming region is shifted toward the outer region in the radial direction of the antenna. It follows that it is possible to obtain an effect similar to that obtained in the first embodiment.

Let us describe a plasma processing apparatus according to a third embodiment of the present invention. In this embodiment, two antennas used as an induction member are concentrically arranged, and the high frequency voltages supplied to these two antennas are independently controlled.

To be more specific,FIG. 8 shows that ring-like antennas24A and24B are concentrically arranged on, preferably, the same plane. As shown in the drawing, a first highfrequency power supply28A is connected to a terminal24Aa and to a terminal24Ab, via acapacitor26A acting as a matching circuit, of theouter antenna24A. Likewise, a second highfrequency power supply28B is connected to a terminal24Ba and to another terminal24Bb, via acapacitor26B acting as a matching circuit, of theinner antenna24B.

These first and second highfrequency power supplies28A and28B serve to supply independently first and second high frequency powers of the same frequency, e.g., 13.56 MHz, and same phase to the outer and inner ring-like antennas24A and24B. Where these antennas are arranged in substantially the same positions as in the embodiment shown inFIGS. 1 and 2, the second high frequency power is selected to be smaller than the first high frequency power. As a result, a relatively large high frequency current i_ARFis allowed to flow through the outer ring-like antenna24A, with a relatively small high frequency power i_BRFbeing allowed to flow through the inner ring-like antenna24B. In this case, the plasma forming region P in the free space right under the antenna within the processing chamber is shifted toward the outside, compared with the plasma forming region P shown inFIG. 2 in the case where the same high frequency current i_RFflows through thesingle antenna24. It follows that the plasma density is rendered uniform as in the embodiment shown inFIGS. 1 and 2. In order to make the plasma density more uniform in this case, it is desirable to arrange these outer ring-like antenna24A and inner ring-like antenna24B such that the semiconductor wafer W used as an object to be processed is positioned in a region corresponding to the region between these outer andinner antennas24A and24B.

Where the antennas used as an induction member are constructed as described above, it is possible to determine independently the high frequency power supplied to each of these inner and outer antennas, making it possible to control the plasma forming region more accurately over a wider range. Incidentally, it is possible to use commonly a single high frequency power supply in place of the first and second highfrequency power supplies28A and28B by providing a power distributing circuit between the high frequency power supply and theantenna24A and between the high frequency power supply and theother antenna24B.

In the embodiment shown inFIG. 9, twospiral antennas24A and24B are concentrically arranged such that these antennas substantially form a larger spiral configuration. To be more specific, aninner spiral antenna24B is arranged inside anouter spiral antenna24A, and these inner and outerspiral antennas24B,24A are connected to highfrequency power supplies28B,28A viacapacitors26B,26A, respectively. The arrangement shown inFIG. 9 produces an effect similar to that obtained from the arrangement shown in FIG.8. It should be noted that the number of turns of each of these spiral antennas can be determined appropriately in view of the output of each of the highfrequency power supplies28B,28A, the diameter of the semiconductor wafer, the distance between the antenna and the semiconductor wafer, etc. In the embodiment shown inFIG. 8, two spiral antennas are arranged to form a larger spiral configuration. However, it is also possible to arrange three or more spiral antennas to form a larger spiral configuration.

FIG. 10 shows that a ring-like antenna24B is concentrically arranged inside aspiral antenna24A. Of course, the arrangement shown inFIG. 10 also produces a similar effect. Incidentally, a ring-like antenna is arranged inside a spiral antenna in the embodiment shown in FIG.10. Needless to say, however, it is also possible to arrange a ring-like antenna outside a spiral antenna.

It is also possible to use a paramagnetic metal member as used in the first embodiment described previously in each of the embodiments shown inFIGS. 8 to10. In this case, both the high frequency power and the paramagnetic metal member can be utilized for controlling the plasma density.

Let us describe a plasma processing apparatus according to a fourth embodiment of the present invention with reference toFIGS. 11 and 12. The basic construction of the apparatus shown in these drawings is substantially equal to that of the apparatus shown inFIGS. 1 and 2. Thus, the same reference numerals are put to the same members of the apparatus, and the description thereof is omitted in the following description of the apparatus shown inFIGS. 11 and 12.

In this embodiment, a ring-like antenna24 acting as an induction member is arranged on the outer surface of theupper wall12 of theprocessing chamber10 formed of an insulator. Theantenna24 is arranged to surround a region corresponding a semiconductor wafer W acting as an object to be processed. Also, amagnetic member40 is arranged in substantially the central portion on the outer surface of theupper wall12 such that the location of themagnetic member40 corresponds to the position of the wafer W inside the ring-like antenna24. As a result, a magnetic field is allowed to act in the plasma forming region within theprocessing chamber10. Themagnetic member10, which is formed of a ferromagnetic material, should desirably be low in its electrical conductivity. For example, it is desirable to use a soft ferrite, e.g., a Ni—Zn based material, for forming themagnetic member10. Where themagnetic member40 is formed of a material having a high electrical conductivity, an eddy current is generated by an alternating magnetic field when a high frequency current is allowed to flow through themagnetic member40, resulting in failure to form a desired magnetic field within theprocessing chamber10.

Themagnetic member10 is formed to have a relatively thicker portion and a relatively thinner portion. To be more specific, that region of themagnetic member10 which serves to form a magnetic field applied to a region in which it is desirable to relatively increase the plasma density is formed relatively thicker, with that region of themagnetic member10 which serves to form a magnetic field applied to other regions is formed relatively thinner. The plasma density can be controlled as desired by controlling the thickness of themagnetic member40 in this fashion. For example, the outer peripheral portion of themagnetic member40 is formed thicker, with the central portion being formed thinner, as shown inFIG. 11 so as to have the plasma density distributed uniformly within a plane within theprocessing chamber10. Needless to say, however, the shape of themagnetic member40 is not restricted to that exemplified in FIG.11. In other words, the shape of themagnetic member40 can be determined appropriately in view of the process conditions.

It is also important to pay attentions to the cross sectional area in the horizontal direction of themagnetic member40, i.e., the cross sectional area substantially parallel with the processing surface of the wafer W disposed within theprocessing chamber10. To be more specific, it is desirable to make the cross sectional area noted above of themagnetic member40 larger than the processing area of the wafer W. The particular construction makes it possible to allow the magnetic field generated from themagnetic member40 to act over the entire region of the processing area of the wafer W, with the result that the plasma density distribution can be controlled more accurately.

It should be noted that, where a high frequency current is allowed to flow through theantenna24 for the plasma generation, a demagnetizing field is likely to be generated within themagnetic member40 so as to adversely affect the magnetic field generated from themagnetic member40. It follows that it is desirable to determine the thickness of themagnetic member40 in a manner to make the influence given by the demagnetizing field negligible. It is also desirable to make, for example, the magnetic path longer so as to eliminate the adverse effect given by the diamagnetic field.

In the embodiment shown inFIGS. 11 and 12, a magnetic field forming means42 formed of, for example, a permanent magnet is arranged to surround theprocessing chamber10. As shown in, for example,FIG. 13, the magneticfield forming means42 consists of a plurality of permanent magnets42a to42f arranged to form a ring-like configuration. These permanent magnets42a to42f are arranged such that the adjacent permanent magnets are opposite to each other in polarities so as to form a multi-polar magnetic field having lines of magnetic force as denoted by arrows in FIG.13. The multi-polar magnetic field thus formed serves to push the plasma stream, which is likely to collide against the inner wall of theprocessing chamber10, back toward the center of thechamber10 so as to retain a plasma of a desired shape in the vicinity of the semiconductor wafer W used as an object to be processed.

Let us describe more in detail the function of themagnetic member40 included in the embodiment shown inFIGS. 11 and 12. In general, distribution of the plasma density within theprocessing chamber10 is affected by the magnetic field distribution within thechamber10. Thus, in this embodiment, themagnetic member40 formed of, for example, a soft ferrite is mounted on theupper wall12 formed of an insulator in order to control the magnetic field distribution within thechamber10. To be more specific, the shape of themagnetic member40 is changed appropriately so as to control the magnetic field distribution within theprocessing chamber10 and, thus, to control the distribution of the plasma density. To achieve the object, that region of themagnetic member40 which serves to form a magnetic field acting on a region in which it is desirable to increase relatively the plasma density is made relatively thicker, with the other region of themagnetic member40 being made relatively thinner, as described previously.

It is also necessary to control as desired the distribution of the plasma density over the entire processing surface of the semiconductor wafer W used as an object to be processed. To achieve the object, it is also important to pay attention to the cross sectional area in the horizontal direction of themagnetic member40 formed of a soft ferrite, i.e., the cross sectional area substantially parallel with the processing surface of the semiconductor wafer W. To be more specific, it is necessary to make the cross sectional area noted above of themagnetic member40 larger than the processing surface area of the wafer W. What should also be noted is that a diamagnetic field is generated within themagnetic member40, if a high frequency current is allowed to flow through theantenna24, as described previously. To overcome the difficulty, it is desirable to make the thickness of themagnetic member40 negligibly small in terms of the demagnetizing field generation.

As described above, the distribution of the plasma density within theprocessing chamber10 can be controlled as desired by controlling appropriately the shape of themagnetic member40. Suppose that themagnetic member40 is not included in the apparatus shown in FIG.11. In this case, the plasma density in the peripheral portion within theprocessing chamber10 is generally rendered lower than in the central portion, as described previously in conjunction with the first embodiment shown inFIGS. 1 and 2. In order to make the plasma density uniform over the entire region, the thickness of themagnetic member40 should be made larger in the peripheral portion than in the central region as shown in FIG.11. Alternatively, themagnetic member40 should be constructed to provide a longer magnetic path.

It should be noted that the required distribution of the plasma density depends on various factors including the kind of the object to be processed, the kind of the reactive gas used, and the gas pressure. In the present invention, however, a desired optimum distribution of the plasma density can be obtained by controlling appropriately the shape of themagnetic member40 formed of a soft ferrite.

In the embodiment shown in, for example,FIG. 14, a loopedantenna24 is completely covered with themagnetic member40. As a result, it is possible to offset the effect of the demagnetizing field which is generated when a high frequency current is allowed to flow through theantenna24. It is also possible to supply a magnetic field over the entire processing surface of the semiconductor wafer W.

In the embodiment shown inFIG. 15, a region outside themagnetic member40 is covered with themagnetic member40. In this case, it is also possible to offset the effect of the demagnetizing field noted above. Further, the central portion of themagnetic member40 is made thinner than the peripheral portion, with the result that the distribution of the plasma density within theprocessing chamber10 can be made uniform.

Further, in the embodiment shown inFIG. 16, themagnetic member40 is interposed between theantenna24 and theupper wall12. In this case, an electrostatic shielding effect can be obtained by setting themagnetic member40 at a predetermined potential, e.g., ground potential.

In the embodiment shown inFIGS. 11 and 12, theantenna24 is in a simple form of a single loop. As a matter of fact, the shape of theantenna24 is not particularly restricted as far as the antenna is enabled to form a satisfactory alternating magnetic field within theprocessing chamber10 when a high frequency current is allowed to flow through the antenna. For example, it is possible to superpose antennas in the shape of d simple loop one upon the other, as shown inFIG. 17 so as to strengthen the alternating magnetic field. It is also possible to use a spiral antenna as in the embodiments described previously so as to form an alternating magnetic field over a wide range.

Further, two ring-like antennas24A and24B can be concentrically arranged as shown in FIG.18. In this case, a single high frequency power supply which is shared by two high frequency power supplies can be controlled independently so as to control more effectively the plasma density distribution, as described previously in conjunction with the third embodiment.

In any of the embodiments described above, it is desirable to provide ashower head50 on the upper surface of theprocessing chamber10 for supplying a processing gas into the processing chamber, as shown inFIGS. 19A to19C. Specifically,FIG. 19A is an oblique view showing showing theshower head50. On the other hand,FIGS. 19B and 19C are a plan view showing the bottom state and a cross sectional view of the shower head shown inFIG. 19a, respectively. Theshower head50 is formed of an insulating material such as a fused silica, quartz and a ceramic material. As shown in the drawings, theshower head50 comprises a processinggas inlet port51, abuffer chamber52 and a large number of gas spurting holes53. Agas inlet pipe20 is connected to thegas inlet port51. The processing gas introduced through thegas inlet port51 into thebuffer chamber52 is once stored in thebuffer chamber52. Then, the processing gas is spurted under a uniform pressure and a uniform flow rate through theholes53 into the processing chamber positioned below theshower head50. It should be noted that theshower head50 is effective for supplying the processing gas into theprocessing chamber10 uniformly so as to make the plasma density uniform within thechamber10.

In the present invention, it is possible for the high frequency antenna to be shaped optionally. For example, the high frequency antenna may be plate-like, rod-like or tubular. Also, the diameter (or thickness) of the conductor forming the high frequency antenna need not be constant. For example, it is possible to use a hollow metal pipe. In this case, a cooling medium may be allowed to flow through the hollow pipe for the cooling purpose.

The plasma processing apparatus of the present invention need not be restricted to a plasma etching apparatus and a plasma CVD apparatus. In other words, the technical idea of the present invention can also be applied to, for example, a plasma sputtering apparatus and a plasma ashing apparatus. Further, the object to be processed by the apparatus of the present invention need not be restricted to a semiconductor wafer. For example, it is possible to use the apparatus of the present invention for applying a plasma processing to an LCD substrate. In the case of applying a plasma processing to an object having a square cross sectional shape such as an LCD substrate, used is a squaresingle loop antenna24 as shown inFIG. 20 or asquare spiral antenna24 as shown in FIG.21.

Let us describe another plasma processing apparatus using an induction member, said apparatus comprising a plasma generating section and a plasma processing section. In this apparatus, a plasma stream generated in the plasma generating section is introduced into the plasma processing section so as to apply a plasma processing to an object disposed within the plasma processing section. An induction member is arranged within the plasma generating section. When a high frequency current is allowed to flow through the induction member, an alternating electric field is generated via an insulating member within the plasma processing section. Also, a magnetic field forming means is arranged to surround the plasma generating section so as to form a static magnetic field in a direction perpendicular to the alternating electric field noted above. In this case, the alternating electric field and the static magnetic field noted above are controlled so as to form an electron cyclotron resonance region within the plasma processing section. The apparatus outlined above is called a plasma apparatus utilizing an electron cyclotron resonance (ECR).

In recent years, a marked progress is being made in the miniaturization of the pattern formed in an object such as a semiconductor wafer. In accordance with the progress, it is required to perform a plasma processing more accurately in the sub-micron order. When it comes to, for example, an etching treatment, it is important to satisfy various severe conditions simultaneously. Specifically, it is necessary to achieve a vertical etching. The region to be etched should not be damaged or contaminated. An adverse effect should not be given to the device characteristics. Further, it is required to achieve a high etching selectivity.

Under the circumstances, a plasma apparatus utilizing an electron cyclotron resonance (ECR) has come to attract attentions in this technical field. A typical conventional ECR plasma apparatus is disclosed in, for example, Jap. Pat. Appln. KOKOKU Publication No. 3-43774. Compared with the conventional RIE plasma apparatus, the ECR plasma apparatus disclosed in this prior art permits forming a pattern of a high anisotropy and a high selectivity with a low ion energy. Thus, vigorous researches are being made in an attempt to introduce the ECR plasma apparatus into the manufacturing process of sub-micron devices in the future.

The conventional ECR plasma apparatus is constructed to utilize a micro wave of 2.45 GHz introduced from a magnetron oscillating device into a discharge section through an appropriate waveguide and a magnetic field of 875 Gauss generated from an electromagnetic coil arranged in the vicinity of the discharge section. These micro wave and magnetic field are allowed to act in a suitable region within the discharge section so as to achieve the ECR condition and, thus, to form a plasma stream.

In the conventional ECR plasma apparatus, however, a micro wave is utilized for achieving the ECR condition as pointed out above, with the result that a special waveguide is required for transmitting the micro wave. It is also necessary to form within the discharge section such a high magnetic field as 875 Gauss, which corresponds to the micro wave of 2.45 GHz which can be commercially utilized, making it necessary to install a large and heavy magnet. The particular construction pointed out above brings about enlargement and an increased manufacturing cost of the plasma processing apparatus in accordance with increase in the diameter of the semiconductor wafer. Of course, vigorous researches are being made in an attempt to find some coutermeasures. Further, the plasma stream is considerably affected by the diffusing magnetic field of such a large magnetic field as pointed out above.

The apparatus described above, which has been achieved in view of the inconveniences noted above, permits using a lower frequency region so as to make it possible to achieve the ECR condition with a smaller magnetic field. It follows that the apparatus permits miniaturizing and reducing the manufacturing cost of the plasma processing apparatus.

Let us describe the plasma apparatus, which is applied to an ECR plasma etching apparatus, with reference to the accompanying drawings.

As schematically shown inFIG. 22, the plasma apparatus comprises a plasma generating section A and a plasma processing section B. The plasma generating section A includes acylindrical quartz tube102 having, for example, a dome-shaped top portion, anantenna103 acting as an induction member and surrounding thequartz tube102, and anelectromagnetic coil106 arranged to surround thequartz tube102 above theantenna103.

Theantenna103 is connected to a first highfrequency power supply105 via amatching box104. A high frequency power can be supplied to theantenna103 in accordance with a command given from acontroller108. Theelectromagnetic coil106 is connected to apower supply107 and can be excited in accordance with a command given from thecontroller108 so as to form a desired static magnetic field.

A firstgas inlet passageway110 is formed in the dome-shaped top portion of thequartz tube102. A first processing gas, e.g., an inert gas such as an argon gas, is introduced from afirst gas source109 into the plasma generating section A through the firstgas inlet passageway110.

As shown inFIG. 23 in detail, theantenna103 consists of an upper ring member103a, alower ring member103b, and a connecting member103c serving to join these upper andlower ring members103a and103b. A desired high frequency current is allowed to flow from the first highfrequency power supply105 into theantenna103 via thematching box104 as denoted by arrows in FIG.23. As a result, an alternating electric field is formed within thecylindrical quartz tube102. Incidentally, the shape of the antenna is not particularly restricted as far as an alternating electric field can be formed within a desired region.

As apparent fromFIGS. 23 and 24, theelectromagnetic coil106 is arranged to surround thecylindrical quartz tube102 above theantenna103. Incidentally, about a half portion of theelectromagnetic coil106 is cut away inFIG. 23 in order to facilitate the description of the construction of the apparatus. As denoted by arrows inFIG. 24, which is a plan view, theelectromagnetic coil106 is excited by thepower supply107 so as to form a static magnetic field in a direction perpendicular to the alternating electric field. In the drawing, the static magnetic field thus formed extends downward in d vertical direction, i.e., in the axial direction of the cylindrical tube.

As described herein later, the sizes and outputs of thequartz tube102, theantenna103 and theelectromagnetic coil106, which collectively form the plasma generating section, are determined to permit formation of an ECR region E about 20 to 30 cm above the reacting surface of the wafer W. To be more specific, in the apparatus shown inFIG. 22, the ECR region E is allowed to be formed in the vicinity of the junction between thequartz tube102 and theplasma processing chamber111.

Let us describe the construction of the plasma processing section B of the plasma processing apparatus utilizing ECR with reference toFIG. 22 again. As shown in the drawing, the plasma processing section B comprises aprocessing chamber111 in which an object to be processed such as a semiconductor wafer W is to be processed with a plasma stream generated from the plasma generating section A. Asusceptor112 on which the wafer W is to be supported is arranged within theprocessing chamber111. Thesusceptor112 is connected to a second highfrequency power supply114 via amatching box113. An RF bias is applied to thesusceptor112 in accordance with a command generated from thecontroller108 in applying an etching treatment to the semiconductor wafer W.

A secondgas supply passageway119 is formed in a shoulder portion of theprocessing chamber111. A second process gas is supplied from asecond gas source118 into theprocessing chamber111 through the secondgas supply passageway119. Agas exhaust passageway116 is formed in a lower portion, which is positioned opposite to the secondgas supply passageway119, of theprocessing chamber111. Thegas exhaust passageway116 is connected to agas exhaust system115 including a vacuum pump, etc. The free space within theprocessing chamber111 is evacuated into a desired degree of vacuum, as desired, by utilizing thegas exhaust system115 and thegas exhaust passageway116.

A magnetic field forming means117 is arranged to surround the side wall of theprocessing chamber111. The construction of the magnetic field forming means117 is substantially equal to that of the magnetic field forming means42 shown in FIG.11. To reiterate, the plasma stream introduced from the plasma generating section A can be retained in a desired shape in the vicinity of the processing surface of the semiconductor wafer W, i.e., an object to be processed, by the magneticfield forming means117.

Where the ECR plasma etching apparatus of the construction described above is used for applying an etching treatment to the semiconductor wafer W, the wafer W is transferred from a load lock chamber (not shown) located adjacent to theprocessing chamber111 into theprocessing chamber111 whose inner pressure is reduced in advance into, for example, 10⁻⁶Torr. The wafer W thus transferred into theprocessing chamber111 is held by a fixing means such as an electrostatic chuck (not shown) on thesusceptor112 arranged within theprocessing chamber111.

In the next step, predetermined processing gases for applying a plasma etching treatment to the semiconductor wafer W are introduced into thequartz tube102 and theprocessing chamber111 through the firstgas inlet passageway110 formed in the dome-shaped top portion of thequartz tube102 and the secondgas inlet passageway119 formed in the shoulder portion of theprocessing chamber111, respectively. In this step, the pressure within theprocessing chamber111 is controlled to be, for example, 10⁻³Torr. For example, an inert gas such as an argon gas is introduced through the firstgas supply passageway110. On the other hand, a processing gas such as a Cl₂gas or a CHF₃gas is supplied through the secondgas inlet passageway119. What should be noted is that the apparatus is constructed to permit supplying processing gases into the plasma generating section A and the plasma processing section B through the two different gas inlet passageways. It follows that the optimum mixing ratio of the processing gases adapted for the etching treatment can be achieved by separately setting the parameters for the plasma generating section A and the plasma processing section B, making it possible to achieve a plasma etching treatment with an excellent control capability.

In generating a plasma, a suitable high frequency current is supplied from the first highfrequency power supply105 to theantenna103. As a result, an alternating electric field is formed within the processing chamber. At the same time, theelectromagnetic coil106 is excited by thepower supply107 so as to form a static magnetic field having lines of magnetic force running downward in the vertical direction, i.e., running in the axial direction of the quartz tube. If the ECR condition, which is described later, is satisfied, the electrons present within the ECR region are enabled to make spiral movements in a manner to wind the lines of magnetic force of the magnetic field so as to arrive at the plasma potential. As a result, the moving electrons are accelerated in the direction of a weak magnetic field, i.e., accelerated downward in the vertical direction. It follows that formed is a plasma stream flowing in a direction perpendicular to the processing surface of the wafer W.

The condition for achieving the electron cyclotron resonance (ECR) can be obtained when the formula given below is satisfied:
B=2rmefc/e

• • where “B” Ls the magnetic flux density, “me” is the mass of electron, “fc” is the frequency, and “e” is the electric charge.

The micro wave which can be commercially utilized has such a high frequency as 2.45 GHz. Thus, in the conventional micro wave ECR plasma apparatus, it is necessary to generate such a high magnetic field as 875 Gauss in order to meet the ECR condition. Naturally, it is necessary to use a large and heavy magnet for obtaining the high magnetic field, making it unavoidable for the apparatus to be rendered bulky. Further, it is necessary to use a special waveguide for transmitting the micro wave.

As apparent from the formula given above, the ECR condition can be achieved with a lower magnetic field in the case of using a lower frequency. In the plasma apparatus described above, a high frequency current having a low frequency, e.g., 100 MHz or less, is supplied to the antenna so as to form an alternating electric field. It follows that the ECR condition can be satisfied by forming such a low magnetic field as about 35 Gauss. Naturally, in the apparatus of the present invention, it suffices to use an electromagnetic coil much smaller than in the conventional apparatus, making it possible to simplify and diminish the apparatus.

As shown inFIG. 24, the lines of magnetic force generated from the first magnetic field forming means form a diverging magnetic field. In other words, the lines of magnetic force are deflected toward the periphery of the processing chamber, as these lines extend downward in the vertical direction. As a result, the plasma stream flowing toward the semiconductor wafer w also tends to be diverged. When it comes to, particularly, the conventional micro wave ECR plasma apparatus, it is unavoidable to use such a high magnetic field as 875 Gauss as described previously. Naturally, the diverging magnetic field formed within the processing chamber is also rendered very high. Further, the diverging tendency of the plasma stream is also increased. Under the circumstances, it is very difficult to permit the plasma stream to be incident in a direction perpendicular to the processing surface of the semiconductor wafer W.

In the plasma processing apparatus described above, however, it is possible to use such a small magnetic field as, for example, 35 Gauss, making it possible to diminish the diverging magnetic field generated within theprocessing chamber11. It follows that the diverging tendency of the plasma stream introduced into theprocessing chamber11 can be suppressed to the minimum level. In particular, the effect of the diverging magnetic field can be made substantially negligible in a region about 20 to 30 cm apart from the ECR region. As a result, the plasma stream can be guided in a direction substantially perpendicular to the processing surface of the semiconductor wafer W, making it possible to achieve a satisfactory anisotropic etching having a high etching selectivity.

It should also be noted that, in the plasma apparatus shown inFIG. 22, a multi-polar magnetic field is generated around theprocessing chamber111. As a result, the plasma stream introduced from the plasma generating section A into theprocessing chamber111 can be retained in a shape so as to correspond to the processing surface of the semiconductor wafer W. Further, the multi-polar magnetic field permits decreasing the diverging tendency of the plasma stream noted above so as to allow the plasma stream to be incident in a direction perpendicular to the processing surface of the semiconductor wafer W. It follows that it is possible to ensure a high etching selectivity and a high etching uniformity.

Further, in the apparatus shown inFIG. 22, an RF bias is applied from the second highfrequency power supply114 to thesusceptor112 via thematching box113. Thus, the RF bias can be applied appropriately in accordance with the kind and the pressure of the processing gas used so as to accelerate the ions contained in the plasma stream and, at the same time, to make the ion stream uniform.

When the processing, e.g., the etching processing, is finished as described above, the residual processing gas and the reaction product within theprocessing chamber111 are sufficiently withdrawn to the outside by operating theexhaust system115, followed by taking the semiconductor wafer W supported on the susceptor into the load lock chamber by using a transfer arm.

Each ofFIGS. 25 and 26 shows another embodiment in respect of the processing gas passageway from the firstgas supply passageway110 formed in the dome-shaped top portion of thequartz tube102. To be more specific, in the embodiment shown inFIG. 22, the processing gas is introduced from the first gas supply passageway formed in the dome-shaped top portion of thequartz tube102 directly into thequartz tube102. However, it is desirable to employ the construction shown inFIG. 25 or26 in order to allow the processing gas to be dispersed uniformly and promptly into the processing chamber. In the embodiment shown inFIG. 25, the processing gas is introduced through aplate member121 having a plurality of throughholes120 formed therein so as to permit the gas to be dispersed uniformly and rapidly. On the other hand, in the embodiment shown inFIG. 26, a sponge-likeporous member122 is disposed in the vicinity of the firstgas supply passageway110. In this embodiment, the processing gas is introduced into the plasma generating section throughmicro pores123 present in the sponge-likeporous member122 so as to permit the gas to be dispersed uniformly and rapidly.

FIGS. 27 and 28 collectively show an ECR plasma etching apparatus according to still another embodiment of the present invention. Some members of the apparatus shown inFIG. 27 are equal to those shown inFIG. 22 in the function and construction. The same reference numerals are put to these particular members in FIG.27 and the description thereof is omitted in the following description.

In the apparatus shown inFIG. 27, aquartz plate130 is arranged on the upper surface of theprocessing chamber111 in place of thequartz tube102 used in the apparatus shown inFIG. 22, and a substantiallyplanar antenna131 is arranged on the outer surface of thequartz plate130. As shown inFIGS. 27 and 28, theantenna131 is a substantially planar spiral antenna having multiple curved antenna segments (e.g., two, as shown in FIG.28), each of which has an inner end positioned at the central area of the spiral of the spiral antenna. Each of the curved antenna segments is shaped such that it spirals outwardly from the inner end on a plane shared with the other segments. A high frequency current is applied from a highfrequency power supply105 to thespiral antenna131 so as to permit theantenna131 to form efficiently an alternating electric field. Incidentally, the shape of the antenna arranged on the outer surface of thequartz plate130 need not be restricted to the spiral shape as shown in FIG.28. In other words, an antenna of any optional shape can be used as far as a desired alternating electric field can be formed in a desired region.

In the apparatus shown inFIG. 27, anelectromagnetic coil106 is arranged to correspond to thespiral antenna131, as in the embodiment shown inFIG. 22, making it possible to form a static magnetic field having lines of magnetic force gradually diverging vertically downward. It follows that the apparatus of the embodiment shown inFIG. 27 also permits forming an ECR region in a desired region, e.g., aregion 20 to 30 cm above the processing surface of the object to be treated, if the outputs of theantenna131 and theelectromagnetic coil106 are controlled appropriately.

What should also be noted is that, in the apparatus shown inFIG. 27, it is unnecessary to use such a large member as thequartz tube102 which is used in the embodiment shown in FIG.22. It follows that the plasma processing apparatus can be markedly miniaturized.

Claims (18)

1. A method for processing a substrate with plasma, comprising the steps of:

positioning the substrate in a processing chamber;

supplying a high frequency power to a substantially planar spiral antenna from a central area thereof and generating an induced electric field in the processing chamber;

generating a plasma in said processing chamber; and

shaping said induced electric field with respect to said substrate so as to achieve a uniform distribution of said plasma on said substrate.

2. The method according toclaim 1, wherein:

said supplying step includes supplying the high frequency power to the spiral antenna and impedance matching an output of a high frequency power supply to an input of said spiral antenna.

3. The method according toclaim 1, further comprising a step of controlling a supply of the high frequency power by a controller.

4. The method according toclaim 1, wherein:

said supplying step comprises,

generating an alternating magnetic field having flux lines that pass through a dielectric member disposed between said spiral antenna and said substrate in said processing chamber.

5. The method according toclaim 1, wherein:

said supplying step comprises,

supplying the high frequency power to said spiral antenna which includes a plurality of curved antenna segments having inner ends which are positioned at the central area.

6. The method according toclaim 5, wherein:

said supplying step comprises,

supplying the high frequency power to said curved antenna segments, each of said curved antenna segments spiralling radially outward in a same direction, said direction being either clockwise or counterclockwise.

7. The method according toclaim 1 wherein:

said shaping step includes,

disposing a paramagnetic plate under said spiral antenna.

8. The method according toclaim 1, wherein the substantially planar spiral coil is a continuous coil.

9. The method according toclaim 1, wherein the substantially planar spiral coil comprises at least two elongated members that are separated in a radial direction.

10. A method for processing a substrate by a plasma processing apparatus including a processing chamber, a susceptor having a supporting area for supporting the substrate in the processing chamber, a spiral antenna having at least two elongated members, each of the members having an inner end and an outer end and outwardly extending from a central area of the processing chamber, and a dielectric member positioned between the supporting area of the susceptor and the spiral antenna, the method comprising:

supporting the substrate in the supporting area of the susceptor;

introducing a processing gas into the processing chamber;

supplying a high frequency power to one of the inner and the outer end of each of the elongated members to generate an induced electric field in the processing chamber; and

generating a plasma in the processing chamber;

wherein each of the at least two elongated members is a separate member separately supplied with high frequency power.

11. The method according toclaim 8, wherein said supplying comprises:

supplying the high frequency power to the inner end of each of the elongated members.

12. The method according toclaim 10, wherein said supplying comprises:

supplying the high frequency power to one of the inner end and the outer end of each of the elongated members through a matching circuit.

13. The method according toclaim 10, wherein turns of the spiral antenna are arranged so that a pitch of the turns in a central region is greater than a pitch in an outer region.

14. A method for processing a substrate by a plasma processing apparatus, comprising

positioning the substrate in a processing chamber;

applying a high frequency power to inner end portions of a plurality of elongated members of a spiral antenna, the inner end portions of the elongated members being positioned in a central area of the spiral antenna, and the elongated members be in outwardly extended from the central area in a curved shape to generate an induced electric field in the processing chamber; and

generating a plasma in the processing chamber to process the substrate;

wherein each of the plurality of elongated members is a separate member separately supplied with high frequency power.

15. The method according toclaim 14, wherein said applying the high frequency power comprises:

supplying high frequency power to the inner end of each of the elongated members through a matching circuit.

16. The method according toclaim 14, wherein turns of the spiral antenna are arranged so that a pitch of the turns in a central region is greater than a pitch in an outer region.

17. The method according toclaim 14, wherein each of the elongated members of the spiral antenna is extended along a surface of the processing chamber.

18. The method according toclaim 17, wherein each of the elongated members comprises a flat elongated surface that is in contact with the surface of the processing chamber.

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