Disclosure of Invention
The invention aims to provide a photoresist stripping method, which improves photoresist stripping uniformity by setting parameters in a gas homogenizing disc, a softening process and a dry photoresist stripping process. In order to achieve the above purpose, the invention adopts the following technical scheme:
A photoresist stripping method adopts a wafer with photoresist and comprises the following steps:
step 01, placing the wafer in an etching cavity, wherein a gas homogenizing disc with a plurality of through holes is arranged in the etching cavity, and the wafer is placed between the gas homogenizing disc and a microwave source;
step 02, oxygen and water are sequentially introduced into the etching cavity from the upper side of the wafer so as to soften the surface layer part of the photoresist;
step 03, discharging the oxygen and the water which are introduced in the step 02;
Step 04, introducing 0.2-0.5 g of water into the etching cavity from above the wafer, and simultaneously starting the microwave source, wherein the water forms water vapor in the descending process, the microwave source ionizes the water vapor into an ionic state, and the water vapor in the ionic state descends to the wafer through a gas homogenizing disc so as to absorb chloride ions attached to the wafer;
step 05, performing dry photoresist stripping according to preset dry photoresist stripping parameters to strip the surface layer part of the photoresist and the photoresist, wherein the preset dry photoresist stripping parameters comprise the flow of oxygen and the flow of nitrogen, and the oxygen and the nitrogen are introduced into the etching cavity from the upper part of the wafer;
and simultaneously, continuously introducing 0.2-0.5 g of water into the etching cavity from the upper part of the wafer so as to absorb chloride ions attached to the wafer.
Preferably, in step 04, the radio frequency power of the microwave source is 1000-1400W, and the reaction pressure of the etching cavity is 2000-8000Torr.
Preferably, in step 05, the preset dry photoresist removing parameter further includes a radio frequency power and a reaction pressure of the etching cavity, the radio frequency power of the microwave source is 1000-1400W, and the reaction pressure of the etching cavity is 2000-8000torr.
Preferably, in step 05, the oxygen flow is 2000-4000 sccm, and the nitrogen flow is 200-800 sccm.
Preferably, in step 02, the total flow of oxygen gas is 3500sccm, the time of introduction is 30s, the total amount of water introduced is 0.6g, and the time of introduction is 30s.
Preferably, in step 01, the gas distribution plate is made of quartz material.
Preferably, in step 01, the gas homogenizing disc comprises N circles of through hole units, wherein N is more than or equal to 1, each through hole unit comprises a plurality of through holes distributed along the circumference, and the radiuses of the through hole units are different.
Preferably, after step 05, it returns to step 04.
Preferably, in step 01, the method specifically includes:
S1, conveying a wafer in the wafer loading cavity to the position right above a heat table in an etching cavity through a mechanical arm device;
and S2, lifting the ceramic thimble mechanism positioned below the hot table and sequentially passing through the hot table and the hollow area of the mechanical arm device so as to jack up the wafer on the hollow area, wherein the distance between the wafer and the hot table is 9mm.
Compared with the prior art, the invention has the advantages that:
(1) Firstly, introducing oxygen and water in the softening process to physically soften the surface layer parts of the photoresist and the photoresist so that the photoresist and the surface layer part of the photoresist are both water-containing, then discharging the softened oxygen and water out of an etching cavity, then dissolving chloride ions on a wafer by utilizing water in an ionic state to remove the chloride ions, and finally stripping the surface layer part of the photoresist and the photoresist by setting a dry photoresist stripping parameter. Therefore, the photoresist removing uniformity can be improved through the above steps.
(2) In the softening process and the dry photoresist removing process, oxygen, nitrogen and water are introduced from above the wafer into the etching cavity, the oxygen, the nitrogen and the water are ionized into ion states by a microwave source, and then uniformly sprayed to the wafer under the action of a gas homogenizing disc so as to react with photoresist and the surface layer part of the photoresist, thereby finally removing the photoresist and uniformly removing the photoresist.
Detailed Description
The present invention will be described in more detail below with reference to the drawings, in which preferred embodiments of the invention are shown, it being understood that one skilled in the art can modify the invention described herein while still achieving the advantageous effects of the invention. Accordingly, the following description is to be construed as broadly known to those skilled in the art and not as limiting the invention.
As shown in FIG. 1, a photoresist stripping method, which uses a wafer with photoresist, comprises the following steps 01-06.
And 01, placing the wafer in an etching cavity, arranging a gas homogenizing disc with a plurality of through holes in the etching cavity, and placing the wafer between the gas homogenizing disc and a microwave source.
The gas homogenizing disc is made of quartz materials and comprises N circles of through hole units, wherein N is a positive integer and is more than or equal to 1, each through hole unit comprises a plurality of through holes distributed along the circumference, and the radiuses of the through hole units are different.
The function of the gas homogenizing disc is to homogenize the oxygen and water introduced into the etching cavity. In step 02, the gas homogenizing disc is used for uniformly contacting oxygen and water with the photoresist and the surface layer part of the photoresist to improve the softening effect, in step 04, the gas homogenizing disc is used for uniformly contacting water vapor formed by ionization of a microwave source with the photoresist and the surface layer part of the photoresist to uniformly absorb chlorine ions attached to a wafer, and in step 05, the gas homogenizing disc is used for uniformly contacting oxygen ions, nitrogen ions and water vapor ions formed by ionization of the microwave source to uniformly contact the oxygen ions, nitrogen ions and water vapor ions with the photoresist and the surface layer part of the photoresist to improve the photoresist removing uniformity.
The wafer loading cavity is characterized in that a wafer is placed in an etching cavity body, the wafer in the wafer loading cavity is firstly sent to the position right above a hot table in the etching cavity body through a mechanical arm device, then a ceramic thimble mechanism positioned below the hot table is lifted and sequentially passes through the hot table and a hollow area of the mechanical arm device, so that the wafer on the hollow area is jacked, and the distance between the wafer and the hot table is 9mm. As will be appreciated by those skilled in the art, methods of operation as to how a wafer is placed in an etch chamber are well known in the art. In addition, because the temperature of the heat table is higher, in order to prevent photoresist on the wafer from bonding, the wafer is not contacted with the heat table, and the difficulty coefficient of photoresist removal is reduced.
And 02, introducing oxygen and water into the etching cavity from the upper part of the wafer in sequence to soften the surface layer part of the photoresist.
Specifically, oxygen and water are introduced through the wafer, and as the introduced amount increases, the oxygen gradually covers the photoresist on the wafer and the surface layer part of the photoresist or the water vapor gradually completely floods the photoresist on the wafer and the surface layer part of the photoresist. The oxygen is used for softening the photoresist and the surface layer part of the photoresist, avoiding baking the photoresist and the surface layer part of the photoresist in the subsequent photoresist removing time process, and the water is used for physically softening the photoresist and the surface layer part of the photoresist, so that the photoresist and the surface layer part of the photoresist both contain water, and avoiding baking the photoresist and the surface layer part of the photoresist at the high temperature of 250 ℃.
Wherein the total flow of the introduced oxygen is 3500sccm, the introduction time is 30s, the total amount of the introduced water is 0.6g, and the introduction time is 30s.
And 03, completely discharging the oxygen and the water which are introduced in the step 02.
Specifically, an exhaust pipe communicated with the etching cavity and a drain pipe communicated with the etching cavity can be arranged at the bottom of the etching cavity. When the softening time reaches a preset value, valves on the exhaust pipe and the drain pipe are opened, and oxygen and water are respectively discharged out of the etching cavity. The function of step 3 is to avoid oxygen or water residues. If oxygen or water remains, the proportion of the process gas and water in the steps 4 and 5 is unbalanced, and the photoresist removing uniformity is affected.
And 04, introducing 0.2-0.5 g of water into the etching cavity from above the wafer, starting a microwave source at the same time, forming water vapor in the descending process, ionizing the water vapor into an ionic state by the microwave source, and descending the water vapor in the ionic state to the wafer through a vapor homogenizing disc so as to absorb chloride ions attached to the wafer, wherein the step can also play a role in photoresist stripping. Wherein, in the previous step of photoresist stripping, chlorine is needed for dry etching aluminum. Therefore, the residual chloride ions are generated in the photoresist removing process, and the chloride ions have a corrosive effect, so that the chloride ions need to be removed in advance.
Wherein the radio frequency power of the microwave source is 1000-1400W, and the reaction pressure of the etching cavity is 2000-800torr.
And 05, performing dry photoresist stripping according to preset dry photoresist stripping parameters to strip the surface layer part of the photoresist and the photoresist, wherein the preset dry photoresist stripping parameters comprise the flow of oxygen and the flow of nitrogen, the oxygen and the nitrogen are introduced into an etching cavity from the upper part of the wafer, and the oxygen and the nitrogen are used as reaction gases and react with the photoresist and the surface layer part of the photoresist after ionization so as to remove the photoresist and the surface layer part of the photoresist.
And (3) continuously introducing 0.2-0.5 g of water into the etching cavity from the upper part of the wafer while removing the photoresist by the dry method so as to further absorb chloride ions attached to the wafer.
Wherein the oxygen flow is 2000-4000 sccm and the nitrogen flow is 200-800 sccm.
The preset dry photoresist removing parameters further comprise radio frequency power and reaction pressure of the etching cavity, the radio frequency power of the microwave source is 1000-1400W, and the reaction pressure of the etching cavity is 2000-8000torr.
Step 06, after step 05, returning to step 04. Steps 04 and 05 are repeated a plurality of times to completely remove the photoresist, the surface layer portion of the photoresist.
Example 1
The parameters in the step 04 are set up, the size of the holes of the gas homogenizing disc is 6-10mm, the number of layers is 5 from inside to outside, the number of layers is 2mm from inside to outside, the radio frequency power is 1000-1400W, the pressure of the etching cavity is 2000-8000mtorr, and the water flow is 0.2-0.5g. Experimental results show that the photoresist stripping uniformity is 10.5%, and the photoresist stripping rate is 49190A/min.
The parameters in the step 05 are set up, wherein the size of the holes of the gas homogenizing disc is 6-10mm, the number of layers is 5 from inside to outside, the number of layers is 2mm from inside to outside, the increasing or unchanged, the upper radio frequency power is 1000-1400W, the etching cavity pressure is 2000-8000mtorr, the water flow is 0.2-0.5g, the oxygen flow is 2000-4000sccm, and the nitrogen flow is 200-800sccm. The experimental result shows that the photoresist stripping uniformity is 14.8 percent, and the photoresist stripping rate is 31470A/min.
Example 2
The parameters in the step 04 are set up, the size of the holes of the gas homogenizing disc is 6-10mm, the number of layers is 4 from inside to outside, the number of layers is 2mm from inside to outside, the increasing or unchanged, the upper radio frequency power is 1000-1400W, the pressure of the etching cavity is 2000-8000mtorr, and the water flow is 0.2-0.5g. The experimental result shows that the photoresist stripping uniformity is 14.2 percent, and the photoresist stripping rate is 55230A/min.
The parameters in the step 05 are set up, wherein the size of the holes of the gas homogenizing disc is 6-10mm, the number of layers is 4 from inside to outside, the number of layers is 2mm from inside to outside, the radio frequency power is 1000-1400W, the cavity pressure is 2000-8000mtorr, the water flow is 0.2-0.5g, the oxygen flow is 2000-4000sccm, and the nitrogen flow is 200-800sccm. Experimental results show that the photoresist stripping uniformity is 14.4%, and the photoresist stripping rate is 30600A/min.
Example 3
Case three:
The parameters in the step 04 are set up, the size of the holes of the air homogenizing disc is 6-10mm, the number of layers is 4 from inside to outside, the number of layers is 2mm from inside to outside, the radio frequency power is 800-1000W, the cavity pressure is 2000-8000mtorr, and the water flow is 0.2-0.5g. Experimental results show that the photoresist stripping uniformity is 12.2%, and the photoresist stripping rate is 29190A/min.
The parameters in the step 05 are set up, wherein the size of the holes of the gas homogenizing disc is 6-10mm, the number of layers is 4 from inside to outside, the number of layers is 2mm from inside to outside, the radio frequency power is 800-1000W, the cavity pressure is 2000-8000mtorr, the water flow is 0.2-0.5g, the oxygen flow is 2000-4000sccm, and the nitrogen flow is 200-800sccm. Experimental results show that the photoresist stripping uniformity is 11% and the photoresist stripping rate is 41190A/min.
The dry photoresist removal uniformity and photoresist removal rate of examples 1 and 2 can be seen that the uniformity can be controlled within 15% and the etching rate can be controlled above 25000A/min by adjusting the structure (number of turns and pore size) of the gas homogenizing disc.
The dry photoresist stripping uniformity and photoresist stripping rate of example 2 and example 3 can be seen that the uniformity can be stably controlled within 15% and the etching rate can be controlled above 25000A/min by adjusting the process parameters based on the optimized structure (number of turns and aperture size) of the gas-homogenizing disc.
In addition, as shown in tables 1-2, the invention also verifies the dry photoresist removal etching rate and photoresist removal uniformity for the size of the through hole. In Table 2, the photoresist uniformity calculations have been calculated using the industry-wide range method. In this embodiment, "uniformity" refers to "photoresist removal uniformity".
Table 1 data of sizes of 10 groups of vias
Table 2 output parameters of the 10 sets of experiments corresponding to table 1 (uniformity < 15)
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art will make any equivalent substitution or modification to the technical solution and technical content disclosed in the invention without departing from the scope of the technical solution of the invention, and the technical solution of the invention is not departing from the scope of the invention.