USRE40043E1 - Positioning device having two object holders - Google Patents

Abstract

A positioning device has first and second object holders that are guided over a guiding surface extending parallel to an X-direction and parallel to a Y-direction perpendicular to the X-direction and which are displaceable over the guiding surface from a first position into a second position by means of a displacement system. The displacement system includes a first displacement unit and a second displacement unit to which the object holders can be alternately coupled. The first displacement unit is suitable for carrying out a first series of positioning steps of the first object holder in the first position and for displacing the first object holder from the first position into an intermediate position between the first and second positions. The second displacement unit is suitable for carrying out a second series of positioning steps of the second object holder in the second position, simultaneously with and independently of the first displacement unit, and for displacing the second object holder from the second position into the intermediate position. In the intermediate position, the object holders are exchanged, after which the first series of positioning steps can be carried out by the first displacement unit with the second object holder in the first position and the second series of positioning steps can be carried out by the second displacement unit with the first object holder in the second position. The positioning device is suitable for use in a lithographic device to carry out an exposure process with a first semiconductor substrate in an exposure position and, simultaneously therewith and independently thereof, a characterization process with a second semiconductor substrate in a characterization position.

Description

BACKGROUND OF THE INVENTION

The invention relates to a positioning device having a guiding surface extending parallel to an X-direction and parallel to a Y-direction, a first object holder and a second object holder which are each guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position, and a displacement system for displacing the first object holder and the second object holder over the guiding surface.

The invention further relates to a lithographic device provided with a radiation source, a mask holder, a focusing unit having a main axis, a characterization unit, and a positioning device, said positioning device comprising a guiding surface extending parallel to an X-direction, which is perpendicular to the main axis, and parallel to a Y-direction, which is perpendicular to the X-direction and the main axis, a first substrate holder and a second substrate holder which are each guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position which is present near the focusing unit, and a displacement system for displacing the first substrate holder and the second substrate holder over the guiding surface.

A positioning device and a lithographic device of the kinds mentioned in the opening paragraphs are known from EP-A-0 687 957. The known lithographic device is used for the exposure of semiconductor substrates in the manufacturing process of integrated semiconductor circuits and operates according to the so-called step-and-repeat process. The known positioning device is used in the known lithographic device for displacing semiconductor substrates relative to the focusing unit and relative to the characterization unit. The first position of the known positioning device is a load and unload position in which a semiconductor substrate can be loaded on or unloaded from the first or the second object holder. The second position of the positioning device is an exposure position in which a semiconductor substrate present on the first or the second object holder can be exposed via the focusing unit. The first and the second object holder are displaceable from the first position to the second position and vice versa by the displacement system of the positioning device which is not described in detail in EP-A-0 687 957. When the first object holder is in the second position and the semiconductor substrate present thereon is being exposed, the second object holder is in the first position and a next semiconductor substrate is loaded thereon at first. Then the second object holder is displaced from the first position to a characterization position in which the semiconductor substrate present on the second object holder is characterized by the characterization unit. When the second object holder is in the characterization position, the first object holder and the second object holder are displaced lockstep-wise. In this manner the exposure of the semiconductor substrate present on the first object holder and the characterization of the semiconductor substrate present on the second object holder are carried out simultaneously, so that a high throughput of the step-and-repeat apparatus is obtained.

A disadvantage of the known positioning device and the known lithographic device is that the characterization of the semiconductor substrate present on the second object holder and the exposure of the semiconductor substrate present on the first object holder cannot be carried out independently from each other as a result of said lockstep-wise displacements of the first and the second object holder. As a result, the exposure of the semiconductor substrate present on the first object holder cannot be started until the second object holder has reached the characterization position.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a positioning device of the kind mentioned in the opening paragraph in which a first process involving a first series of positioning steps of the first object holder can be carried out simultaneously with and independently from a second process involving a second series of positioning steps of the second object holder, and in which also the first process can be carried out with the second object holder and, simultaneously and independently, the second process can be carried out with the first object holder.

It is a further object of the present invention to provide a lithographic device of the kind mentioned in the second paragraph in which a characterization process involving a first series of positioning steps of the first substrate holder can be carried out simultaneously with and independently from an exposure process involving a second series of positioning steps of the second substrate holder, and in which also the characterization process can be carried out with the second substrate holder and, simultaneously and independently, the exposure process can be carried out with the first substrate holder.

The positioning device according to the invention is for this purpose characterized in that the displacement system comprises a first displacement unit and a second displacement unit to which the first object holder and the second object holder can be coupled alternately, the first displacement unit being suitable for displacing the object holders from the first position into an intermediate position between the first position and the second position, and the second displacement unit being suitable for displacing the object holders from the intermediate position into the second position. As a result of the use of said first and second displacement units, a first process involving a first series of positioning steps of the first object holder can be carried out in the first position by means of the first displacement unit, and a second process involving a second series of positioning steps of the second object holder can be carried out in the second position by means of the second displacement unit simultaneously with and independently from the first process. When the first process and the second process have been completed, the first object holder is displaced by the first displacement unit from the first position into the intermediate position and the second object holder is displaced by the second displacement unit from the second position into the intermediate position. In the intermediate position, the first object holder is uncoupled from the first displacement unit and is coupled to the second displacement unit, while the second object holder is uncoupled from the second displacement unit and is coupled to the first displacement unit. Subsequently, the first object holder is displaced by the second displacement unit from the intermediate position to the second position and the second object holder is displaced by the first displacement unit from the intermediate position to the first position. Then the first process can be carried out with the second object holder in the first position and, simultaneously and independently, the second process can be carried out with the first object holder in the second position. Furthermore, as a result of the use of said two displacement units, a distance over which each individual displacement unit has to displace the object holders is reduced, so that the required dimensions of the displacement units are reduced. It is in addition prevented that the displaceable parts of the first displacement unit and the displaceable parts of the second displacement unit must be constructed so as to be capable of passing one another, which allows a comparatively simple construction of the displacement units.

The lithographic device according to the invention is for this purpose characterized in that the positioning device of the lithographic device is a positioning device according to the invention, wherein each of the object holders of the positioning device is a substrate holder of the lithographic device, and wherein the first position of the object holders is a characterization position which is present near the characterization unit. As a result of the use of the positioning device according to the invention in the lithographic device according to the invention, a characterization process involving a first series of positioning steps of the first substrate holder can be carried out in the first position by means of the first displacement unit of the positioning device, and an exposure process involving a second series of positioning steps of the second substrate holder can be carried out in the second position by means of the second displacement unit of the positioning device simultaneously with and independently from the first process. The first process can also be carried out with the second substrate holder in the first position and, simultaneously and independently, the second process can be carried out with the first object holder in the second position.

A particular embodiment of a positioning device according to the invention is characterized in that the displacement units each comprise an X-motor having a first part extending parallel to the X-direction and a second part which is displaceable along the first part of the X-motor and can be coupled alternately to the first object holder and to the second object holder, and two Y-motors each having a first part extending parallel to the Y-direction and a second part which is displaceable along the first part of the relevant Y-motor, the first part of the X-motor of each displacement unit being connected to the second parts of the two Y-motors of the relevant displacement unit. Since the first part of the X-motor of each displacement unit is connected to the second parts of the two Y-motors of the relevant displacement unit, a comparatively stiff and stable support of the X-motor by the two Y-motors is obtained, which benefits the positioning accuracy of the displacement unit. Since the first displacement unit has a limited displacing range from the first position to the intermediate position and the second displacement unit has a limited displacing range from the intermediate position to the second position, the four Y-motors of the two displacement units can be arranged in two lines, which leads to a compact and simple construction of the positioning device.

A further embodiment of a positioning device according to the invention is characterized in that the first parts of the Y-motors of the two displacement units are connected to a common balancing unit which is guided relative to a base of the positioning device so as to be displaceable parallel to the X-direction and parallel to the Y-direction and to be rotatable about an axis of rotation extending perpendicularly to the X-direction and the Y-direction. Since the first parts of the Y-motors of the displacement units are connected to said common balancing unit, reaction forces of the X-motors and the Y-motors of the displacement units are transmitted via the first parts of the Y-motors to the balancing unit and are converted into displacements of the balancing unit parallel to the X-direction and parallel to the Y-direction and rotations of the balancing unit about said axis of rotation relative to the base. In this manner, a transmission of the reaction forces to the base, the guiding surface, and the object holders is prevented as much as possible, so that the positioning accuracy of the positioning device is further improved.

A yet further embodiment of a positioning device according to the invention is characterized in that the object holders each comprise a basic part which is guided over the guiding surface and can be coupled to the displacement units, and an object table which is displaceable relative to the basic part by means of an actuator unit of the relevant object holder. In this yet further embodiment of the positioning device, the object tables of the object holders are displaceable by the displacement units over comparatively large distances and with comparatively low accuracies, while the object tables are displaceable by said actuator units over comparatively small distances and with comparatively high accuracies. In this manner, the displacement units can be of a relatively simple, conventional type, while the dimensions of the accurate actuator units can be limited as much as possible.

A particular embodiment of a positioning device according to the invention is characterized in that the object table of each of the object holders is displaceable relative to the basic part parallel to the X-direction, parallel to the Y-direction, and parallel to a Z-direction extending perpendicularly to the X-direction and the Y-direction, and is pivotable relative to the basic part about a first pivot axis extending parallel to the X-direction, a second pivot axis extending parallel to the Y-direction, and a third pivot axis extending parallel to the Z-direction. In this manner, a high degree of adjustability of the object tables relative to the basic parts is obtained.

BRIEF DESCRIPTION OF THE DRAWING

The invention will be explained in more detail below with reference to the drawing, in which

FIG. 1 diagrammatically shows a lithographic device according to the invention,

FIG. 2 is a diagrammatic plan view of a first embodiment of a positioning device according to the invention suitable for use in the lithographic device ofFIG. 1,

FIG. 3 shows the positioning device ofFIG. 2, two substrate holders of the positioning device being in an intermediate position, and

FIG. 4 is a diagrammatic plan view of a second embodiment of a positioning device according to the invention suitable for use in the lithographic device of FIG.1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The lithographic device according to the invention shown diagrammatically inFIG. 1 is used for the exposure of semiconductor substrates in the manufacturing process of integrated semiconductor circuits and comprises a frame1 which supports in that order, as seen parallel to a vertical Z-direction, apositioning device3 according to the invention, a focusingunit5, amask holder7, and aradiation source9. The lithographic device is an optical lithographic device whoseradiation source9 comprises a light source11. Themask holder7 comprises asupport surface13 which extends perpendicularly to the Z-direction and on which amask15 can be placed comprising a pattern or a sub-pattern of an integrated semiconductor circuit. The focusingunit5 is an imaging or projection system and comprises anoptical lens system17 having a mainoptical axis19 extending parallel to the Z-direction and an optical reduction factor of, for example,4 or5. Thepositioning device3 comprises afirst substrate holder21 and asecond substrate holder23 which is identical to thefirst substrate holder21. Thesubstrate holders21,23 each comprise asupport surface25,27 which extends perpendicularly to the Z-direction. In the situation shown inFIG. 1, afirst semiconductor substrate29 is present on thesupport surface25 of thefirst substrate holder21 and asecond semiconductor substrate31 is present on thesupport surface27 of thesecond substrate holder23. Thepositioning device3 further comprises a guidingsurface33 extending parallel to a horizontal X-direction which is perpendicular to the Z-direction and parallel to a horizontal Y-direction which is perpendicular to the X-direction and the Z-direction. Thesubstrate holders21,23 are each guided over the guidingsurface33 and are each displaceable over the guidingsurface33 parallel to the X-direction and parallel to the Y-direction by means of a displacement system35 of thepositioning device3.

In the situation shown inFIG. 1, thefirst substrate holder21 with thefirst semiconductor substrate29 is in a second position of thepositioning device3 which corresponds to an exposure position of the lithographic device which is present near the focusingunit5. In this position, a light beam originating from the light source11 is guided through themask15 and is focused on thefirst semiconductor substrate29 by means of the focusingunit5, so that the pattern present on themask15 is imaged on a reduced scale on thefirst semiconductor substrate29. Thefirst semiconductor substrate29 comprises a large number of individual fields on which identical semiconductor circuits are to be imaged. The fields of thefirst semiconductor substrate29 are consecutively exposed through themask15 for this purpose. The exposure process used in the lithographic device ofFIG. 1 is a so called step-and-repeat exposure process according to which thefirst semiconductor substrate29 and themask15 are in fixed positions relative to the focusingunit5 during the exposure of an individual field of thefirst semiconductor substrate29, and according to which a next field of thefirst semiconductor substrate29 is brought into position relative to the focusingunit5 after the exposure of a previously exposed field in that thefirst substrate holder21 is displaced parallel to the X-direction and/or parallel to the Y-direction by the displacement system35 of thepositioning device3. This process is repeated a number of times, with a different mask each time, so that complicated integrated semiconductor circuits with a layered structure can be manufactured.

In the situation shown inFIG. 1, thesecond substrate holder23 with thesecond semiconductor substrate31 is in a first position of thepositioning device3 which corresponds to a characterization position of the lithographic device. In the situation shown, a previous semiconductor substrate, which was fully exposed in the exposure position via themask15, was unloaded from thesecond substrate holder23 and was transported to a stack of semiconductor substrates under manufacture not shown in the figure. Thesecond semiconductor substrate31 shown inFIG. 1 is a next semiconductor substrate which has just been taken from said stack of semiconductor substrates and loaded on thesecond substrate holder23 and which has to be exposed via themask15 after thefirst semiconductor substrate29. In the characterization position, thesecond semiconductor substrate31 is characterized by acharacterization unit37 of the lithographic device which is also supported by the frame1. When thesecond semiconductor substrate31 has been fully characterized and thefirst semiconductor substrate29 has been fully exposed, thesecond substrate holder23 with thesecond semiconductor substrate31 is displaced by the displacement system35 from the characterization position into the exposure position and thefirst substrate holder21 with thefirst semiconductor substrate29 is displaced by the displacement system35 from the exposure position into the characterization position. Thecharacterization unit37 comprises, for example, a measuring system which is used for measuring the positions of the individual fields of thesecond semiconductor substrate31 relative to thesecond substrate holder23. Since these positions are already measured in the characterization position, the individual fields of thesecond semiconductor substrate31 can subsequently be positioned relative to the focusingunit5 in the exposure position by measuring the position of thesecond substrate holder23 relative to the focusingunit5. In this manner, the time required to position the individual fields of the successive semiconductor substrates relative to the focusingunit5 in the exposure position is limited considerably, so that the throughput of the lithographic device is considerably improved. Since the position of each individual field of thesecond semiconductor substrate31 has to be measured in the characterization position, a step wise displacement of thesecond substrate holder23 with thesecond semiconductor substrate31 is carried out by the displacement system35 of thepositioning device3 in the characterization position. As a result of the use of the two separateidentical substrate holders21 and23, the exposure process of a semiconductor substrate in the exposure position can be carried out simultaneously with the unload process of a previous semiconductor substrate and the load and characterization processes of a next semiconductor substrate in the characterization position, so that the throughput of the lithographic device is further improved.

As shown inFIG. 2, the displacement system35 of thepositioning device3 comprises a first displacement unit39 and a second displacement unit41. Thesubstrate holders21,23 each comprise an aerostatically supportedfoot43,45 provided with a static gas bearing by means of which therelevant substrate holder21,23 is guided over the guidingsurface33. The guidingsurface33 constitutes an upper surface of agranite block47 which is fastened to the frame1 of the lithographic device. Furthermore, thesubstrate holders21,23 each comprise afirst coupling member49,51 and asecond coupling member53,55 by means of which thesubstrate holders21,23 can be coupled alternately to acoupling member57 of the first displacement unit39 and to acoupling member59 of the second displacement unit41, respectively. In the situation shown inFIG. 2, thefirst substrate holder21 is coupled to thecoupling member59 of the second displacement unit41 and thesecond substrate holder23 is coupled to thecoupling member57 of the first displacement unit39. Alternatively, thefirst substrate holder21 can be coupled to thecoupling member57 of the first displacement unit39 and thesecond substrate holder23 can be coupled to thecoupling member59 of the second displacement unit41. Thecoupling members49,51,53,55,57,59 may be of a type which is known and usual per se, such as, for example, a mechanical or an electromechanical coupling member.

AsFIG. 2 shows, the first displacement unit39 and the second displacement unit41 each comprise a linear X-motor61,63 and two linear Y-motors65,67,69,71 of a conventional type which is known and usual per se. The X-motors61,63 each comprise afirst part73,75 extending parallel to the X-direction and asecond part77,79 which is displaceable along thefirst part73,75 of the relevant X-motor61,63 and comprises thecoupling member57,59 of the relevant X-motor61,63. The Y-motors65,67,69,71 each comprise afirst part81,83,85,87 extending parallel to the Y-direction and asecond part89,91,93,95 which is displaceable along thefirst part81,83,85,87 of the relevant Y-motor65,67,69,71. The X-motor61 and the two Y-motors65,67 of the first displacement unit39 are mutually arranged in a H-configuration, afirst end97 and asecond end99 of thefirst part73 of the X-motor61 being coupled to thesecond part89 of the Y-motor65 and to thesecond part91 of the Y-motor67, respectively. Likewise, the X-motor63 and the two Y-motors69,71 of the second displacement unit41 are mutually arranged in a H-configuration, afirst end101 and asecond end103 of thefirst part75 of the X-motor63 being coupled to thesecond part93 of the Y-motor69 and to thesecond part95 of the Y-motor71, respectively.

In the situation shown inFIG. 2, thesecond substrate holder23 is in the first position or characterization position and a characterization process involving a first series of positioning steps of thesecond substrate holder23 is carried out by means of the first displacement unit39. Simultaneously, thefirst substrate holder21 is in the second position or exposure position and an exposure process involving a second series of positioning steps of thefirst substrate holder21 is carried out by means of the second displacement unit41. Thus, as a result of the use of the first displacement unit39 and the second displacement unit41, the characterization process can be carried out not only simultaneously with but also independently from the exposure process. When the exposure process with thefirst substrate holder21 and the characterization process with thesecond substrate holder23 have been completed, thefirst substrate holder21 is displaced by means of the second displacement unit41 from the exposure position into an intermediate position M′ between the exposure position and the characterization position as shown inFIG. 3, and thesecond substrate holder23 is displaced by means of the first displacement unit39 from the characterization position into an intermediate position M″ between the exposure position and the characterization position. In said intermediate positions M′ and M″, thesecond coupling member53 of thefirst substrate holder21 is uncoupled from thecoupling member59 of the second displacement unit41 and thefirst coupling member51 of thesecond substrate holder23 is uncoupled from thecoupling member57 of the first displacement unit39. Subsequently, thecoupling member57 of the first displacement unit39 is coupled to thefirst coupling member49 of thefirst substrate holder21 and thecoupling member59 of the second displacement unit41 is coupled to thesecond coupling member55 of thesecond substrate holder23, as shown in FIG.3. Then, thefirst substrate holder21 is displaced by the first displacement unit39 from the intermediate position M′ into the characterization position where the substrate present on thefirst substrate holder21 is unloaded and a next substrate is loaded and characterized. Simultaneously therewith and independently therefrom, thesecond substrate holder23 is displaced by the second displacement unit41 from the intermediate position M″ into the exposure position where the substrate present on thesecond substrate holder23 is exposed. Since the first displacement unit39 is suitable for displacing bothsubstrate holders21 and23 from the first position or characterization position into the intermediate positions M′ and M″ and the second displacement unit41 is suitable for displacing bothsubstrate holders21 and23 from the intermediate positions M′ and M″ into the exposure position, a distance over which each displacement unit39,41 must be able to displace thesubstrate holders21 and23 is reduced, so that the required dimensions of the displacement units39,41 are reduced. AsFIG. 2 shows, particularly the dimensions of the Y-motors65,67,69,71 of the displacement units39,41 are considerably reduced as seen parallel to the Y-direction. Furthermore, the use of the two displacement units39,41 prevents that the displaceable parts of the displacement system35, in particular the X-motors61 and63, must be constructed so as to be capable of passing one another, as a result of which a comparatively simple construction of the displacement system35 is achieved. The arrangement of the two X-motors61,63 and the four Y-motors65,67,69,71 in two H-configurations leads to a comparatively stiff and stable support of X-motors61,63 by the relevant Y-motors65,67,69,71, which benefits the positioning accuracy of the displacement units39,41. The limited displacing range of the displacement units39,41 as seen parallel to the Y-direction enables the mutual arrangement of the four Y-motors65,67,69,71 in two lines of two Y-motors65,69 and67,71 each, which leads to a compact and simple construction of thepositioning device3.

FIG. 4 shows a second embodiment of apositioning device105 according to the invention suitable for use in the lithographic device according to the invention. Corresponding parts of the first embodiment of thepositioning device3 and the second embodiment of thepositioning device105 are indicated by means of corresponding reference numerals inFIGS. 2,3, and4. Hereafter, only the main differences between thepositioning devices3 and105 will be discussed.

Thesubstrate holders21 and23 of thepositioning device105 each comprise a basic part107,109 which comprises the aerostatically supportedfoot43,45, thefirst coupling member49,51, and thesecond coupling member53,55 of therelevant substrate holder21,23. Furthermore, thesubstrate holders21,23 of thepositioning device105 each comprise a substrate table111,113 which comprises thesupport surface25,27 of therelevant substrate holder21,23. Thesubstrate holders21,23 each comprise ahactuator unit115,117 which is indicated diagrammatically only in FIG.4 and by means of which the substrate table111,113 of therelevant substrate holder21,23 is displaceable relative to the basic part107,109 of therelevant substrate holder21,23. In the second embodiment of thepositioning device105 according to the invention, theactuator units115,117 each comprise a system of contactless Lorentz-force motors which are known and usual per se and by means of which the substrate table111,113 of therelevant substrate holder21,23 is displaceable relative to the basic part107,109 of therelevant substrate holder21,23 with comparatively high accuracies and over comparatively small distances in directions parallel to the X-direction, parallel to the Y-direction, and parallel to the Z-direction, and by means of which the substrate table111,113 of therelevant substrate holder21,23 is pivotable relative to the basic part107,109 of therelevant substrate holder21,23 with comparatively high accuracies and over comparatively small angles about a first pivot axis extending parallel to the X-direction, a second pivot axis extending parallel to the Y-direction, and a third pivot axis extending parallel to the Z-direction. In this manner, the displacement units39,41 each constitute a so called coarse-fine displacement unit wherein thesubstrate holders21,23 with the substrate tables111,113 are displaceable over comparatively large distances and with comparatively low accuracies by means of the X-motors61,63 and the Y-motors65,67,69,71 of the displacement units39,41, and wherein the substrate tables111,113 are displaceable and pivotable with comparatively high accuracies and over comparatively low distances and small angles relative to the basic parts107,109 of thesubstrate holders21,23 by means of theactuator units115,117 of the displacement units39,41. In this manner, the X-motors61,63 and the Y-motors65,67,69,71 can be of a relatively simple, conventional, and low-cost type, while the required dimensions and therefore the costs of the accurate andadvanced actuator units115,117 can be limited as much as possible. The use of theactuator units115,117 as described further provides a high degree of adjustability of the substrate tables111,113 relative to the focusingunit5 and relative to thecharacterization unit37 of the lithographic device.

AsFIG. 4 further shows, thefirst parts81,83,85,87 of the Y-motors65,67,69,71 of the displacement units39,41 of thepositioning device105 are fastened to abalancing unit119 which is common for the two displacement units39,41. Thebalancing unit119 comprises a first beam121 which extends substantially parallel to the Y-direction and to which thefirst part81 of the Y-motor65 of the first displacement unit39 and thefirst part85 of the Y-motor69 of the second displacement unit41 are fastened, and a second beam123 which also extends substantially parallel to the Y-direction and to which thefirst part83 of the Y-motor67 of the first displacement unit39 and thefirst part87 of the Y-motor71 of the second displacement unit41 are fastened. The first beam121 and the second beam123 are interconnected by means of afirst cross-beam125 and asecond cross-beam127, the beams121 and123 and thecross-beams125 and127 being arranged in a rectangular configuration which surrounds thegranite block47 carrying the guidingsurface33. AsFIG. 4 diagrammatically shows, the first beam121 of thebalancing unit119 is guided by means ofstatic gas bearings129 over a further guiding surface131 which is provided on a base133 of thepositioning device105 and extends parallel to the X-direction and parallel to the Y-direction, and the second beam123 of thebalancing unit119 is guided by means ofstatic gas bearings135 over said further guiding surface131. Thus, thebalancing unit119 is displaceable in direction parallel to the X-direction and parallel to the Y-direction and is rotatable about an axis of rotation extending parallel to the Z-direction. In operation, reaction forces of theactuator units115,117 of the displacement units39,41 directed parallel to the X-direction and/or parallel to the Y-direction are transmitted via the X-motors61,63 and the Y-motors65,67,69,71 to thebalancing unit119, reaction forces of the X-motors61,63 of the displacement units39,41 directed parallel to the X-direction and/or parallel to the Y-direction are transmitted via the Y-motors65,67,69,71 to thebalancing unit119, and reaction forces of the Y-motors65,67,69,71 of the displacement units39,41 directed parallel to the X-direction and/or parallel to the Y-direction are directly transmitted to thebalancing unit119. Since thebalancing unit119 is guided over the further guiding surface131 by means of thestatic gas bearings129,135, said reaction forces are substantially completely converted into relatively small displacements of thebalancing unit119 in directions parallel to the X-direction and/or parallel to the Y-direction and into relatively small rotations of thebalancing unit119 about said axis of rotation extending parallel to the Z-direction. In this manner, mechanical vibrations, which may be caused by said reaction forces in the base133 and which may be transmitted to thegranite block47 and thesubstrate holders21,23 of thelithographic device105 and to the frame1 of the lithographic device, are prevented as much as possible, so that the positioning accuracy of the displacement system35 of thepositioning device105 is further improved.

It is noted that another type of displacement unit may be used in the positioning device according to the invention instead of the displacement units39,41 used in thepositioning devices3,105 described before. For example, the displacement units of the positioning device may each alternatively comprise a single linear X-motor and a single linear Y-motor for large-distance displacements of the relevant object holder and an actuator unit solely comprising an X-Lorentz-force motor and a Y-Lorentz-force motor for small-distance displacements of the relevant object table.

It is further noted that the invention also relates to lithographic devices in which an exposure process following the step-and-scan principle is applied. Such a lithographic device is provided with a further positioning device by means of which the mask holder is displaceable in a scan direction which is parallel to, for example, the X-direction. According to the stepand-scan process, the mask and the semiconductor substrate are not in fixed positions relative to the focusing unit during the exposure process but are displaced simultaneously in the scan direction, so that the pattern present on the mask is scanned.

It is finally noted, that a positioning device according to the invention may be used not only in a lithographic device but also in other devices where two object tables have to perform a series of positioning steps simultaneously and independently from each other. Examples are finishing machines, machine tools, and other machines or devices in which an object to be machined or processed is first characterized relative to an object holder in a characterization position and is subsequently machined or processed in an operational position.

Claims (15)

1. A positioning device for a lithographic apparatus, comprising:

a guiding surface extending parallel to an X-direction and parallel to a Y-direction;

a first object holder and a second object holder which are each adapted to be guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position; and

a displacement system constructed and arranged to displace the first object holder and the second object holder over the guiding surface,

wherein the displacement system comprises a first displacement unit and a second displacement unit to which the first object holder, and the second object holder can be coupled alternately, the first displacement unit being suitable for displacing the object holders from the first position into an intermediate position between the first position and the second position, and the second displacement unit being suitable for displacing the object holders from the intermediate position into the second position.

2. A positioning device as claimed inclaim 1, wherein the first and second displacement units each comprise an X-motor having a first part extending parallel to the X-direction and a second part which is displaceable along the first part of the X-motor and can be coupled alternately to the first object holder and to the second object holder, and two Y-motors each having a first part extending parallel to the Y-direction and a second part which is displaceable along the first part of the relevant Y-motor, the first part of the X-motor of each displacement unit being connected to the second parts of the two Y-motors of the relevant displacement unit.

3. A positioning device as claimed inclaim 2, wherein the first parts of the Y-motors of the two displacement units are connected to a common balancing unit which is guided relative to a base of the positioning device so as to be displaceable parallel to the X-direction and parallel to the Y-direction and to be rotatable about an axis of rotation extending perpendicularly to the X-direction and the Y-direction.

4. A positioning device as claimed inclaim 1, wherein the object holder each comprise a basic part which is guided over the guiding surface and adapted to be coupled to the displacement units, and an object table which is displaceable relative to the basic part by an actuator unit of the relevant object holder.

5. A positioning device as claimed inclaim 4, wherein the object table of each of the object holders is displaceable relative to the basic part parallel to the X-direction, parallel to the Y-direction, and parallel to a Z-direction extending perpendicularly to the X-direction and the Y-direction, and is pivotable relative to the basic part about a first pivot axis extending parallel to the X-direction, a second pivot axis extending parallel to the Y-direction, and a third pivot axis extending parallel to the Z-direction.

6. A positioned device as claimed inclaim 1, wherein said first and second object holders are first and second substrate holders, respectively.

7. A lithographic device comprising:

a radiation source;

a mask bolder holder;

a focusing unit having a main axis;

a characterization unit; and

a positioning device comprising:

a guiding surface extending parallel to an X-direction, which is perpendicular to the main axis, and parallel to a Y-direction, which is perpendicular to the X-direction and this main axis,

a first substrate holder and a second substrate holder which are each guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position which is near the focusing unit, and

a displacement system constructed and arranged to displace the first substrate bolder holder and the second substrate holder over the guiding surface,

wherein the displacement system comprises a first displacement unit and a second displacement unit to which the first substrate holder and second substrate holder can be coupled alternately, the first displacement unit being suitable for displacing the substrate holders from the first position into an intermediate position between the first position and the second position, and the second displacement unit being suitable for displacing the substrate holders from the intermediate position into the second position, and

wherein the first position of the substrate holders is a characterization position which is present near the characterization unit.

8. A lithographic device as claimed inclaim 7, wherein the first and second displacement units each comprise an X-motor having a first part extending parallel to the X-direction and a second part which is displaceable along the first part of the X-motor and can be coupled alternately to the first substrate holder and to the second substrate holder, and two Y-motors each having a first part extending parallel to the Y-direction and a second part which is displaceable along the first part of the relevant Y-motor, the first part of the X-motor of each displacement unit being connected to the second parts of the two Y-motors of the relevant displacement unit.

9. A lithographic device as claimed inclaim 8, wherein the first parts of the Y-motors of the two displacement units are connected to a common balancing unit which is guided relative to a base of the positioning device so as to be displaceable parallel to the X-direction and parallel to the Y-direction and to be rotatable about an axis of rotation extending perpendicularly to the X-direction and the Y-direction.

10. A lithographic device as claimed inclaim 7, wherein the substrate holders each comprise a basic part which is guided over the guiding surface and can be coupled to the displacement units, and a substrate table which is displaceable relative to the basic part by means of an actuator unit of the relevant substrate holder.

11. A lithographic device as claimed inclaim 10, wherein the substrate table of each of the substrate holders is displaceable relative to the basic part parallel to the X-direction, parallel to the Y-direction, and parallel to the Z-direction extending perpendicularly to the X-direction and the Y-direction, and is pivotable relative to the basic part about a first pivot axis extending parallel to the X-direction, a second pivot axis extending parallel to the Y-direction, and a third pivot axis extending parallel to the Z-direction.

12. A positioning device for a lithographic apparatus, comprising:

a guiding surface extending parallel to an X-direction and parallel to a Y-direction;

a first object holder and a second object holder which are each adapted to be guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position;

a displacement system constructed and arranged to displace the first object holder and the second object holder over the guiding surface;

wherein the displacement system comprises a first displacement unit and a second displacement unit to which the first object holder and the second object holder can be coupled alternately so that the first object holder and the second object holder switch positions;

wherein the first and second displacement units each comprise an X-motor having a first part extending parallel to the X-direction and a second part which is displaceable along the first part of the X-motor and can be coupled alternately to the first object holder and to the second object holder, and two Y-motors each having a first part extending parallel to the Y-direction and a second part which is displaceable along the first part of the relevant Y-motor, the first part of the X-motor of each displacement unit being connected to the second parts of the two Y-motors of the relevant displacement unit; and

wherein the first parts of the Y-motors of the two displacement units are connected to a common balancing unit which is guided relative to a base of the positioning device so as to be displaceable parallel to the X-direction and parallel to the Y-direction and to be rotatable about an axis of rotation extending perpendicularly to the X-direction and the Y-direction.

13. A positioning device for a lithographic apparatus, comprising:

a guiding surface extending parallel to an X-direction and parallel to a Y-direction;

a first object holder and a second object holder which are each adapted to be guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position;

a displacement system constructed and arranged to displace the first object holder and the second object holder over the guiding surface;

wherein the displacement system comprises a first displacement unit and a second displacement unit to which the first object holder and the second object holder can be coupled alternately so that the first object holder and the second object holder switch positions;

wherein the object holders each comprise a basic part which is guided over the guiding surface and adapted to be coupled to the displacement units, and an object table which is displaceable relative to the basic part by an actuator unit of the relevant object holder; and

wherein the object table of each of the object holders is displaceable relative to the basic part parallel to the X-direction, parallel to the Y-direction, and parallel to a Z-direction extending perpendicularly to the X-direction and the Y-direction, and is pivotable relative to the basic part about a first pivot axis extending parallel to the X-direction, a second pivot axis extending parallel to the Y-direction, and a third pivot axis extending parallel to the Z-direction.

14. A positioning device for a lithographic apparatus, comprising:

a guiding surface extending parallel to an X-direction and parallel to a Y-direction;

a first object holder and a second object holder which are each adapted to be guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position;

a displacement system constructed and arranged to displace the first object holder and the second object holder over the guiding surface;

wherein the displacement system comprises a first displacement unit and a second displacement unit to which the first object holder and the second object holder can be coupled alternately so that the first object holder and the second object holder switch positions; and

wherein said first and second object holders are first and second substrate holders, respectively.

15. A positioning method for performing operations on substrates in a lithographic device, comprising:

moving first and second substrate holders over a two-dimensional plane between a first position into a second position with first and second displacement units;

loading and characterizing a substrate in the first position;

exposing and unloading the substrate in the second position;

the first and second displacement units moving the first substrate holder and the second substrate holder over the guiding surface between the first and second positions using connections that can be coupled and uncoupled so that the substrate holders switch positions.

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