Patent Application
20080316446
1. Field of the Invention
The present invention relates to a stage apparatus that comprises a plurality of stages, as well as to an exposure apparatus.
2. Description of Related Art
In a lithographic process, which is one of the processes used to fabricate a device such as a semiconductor device, a liquid crystal display device, an imaging device (for example, a charge coupled device, i.e., a CCD), or a thin film magnetic head, an exposure apparatus is used to transfer a pattern of a reticle, which serves as a mask, onto a wafer (or a glass plate and the like), which serves as a substrate and is coated with a photoresist, through a projection optical system. A full-field exposure type (stationary exposure type) projection exposure apparatus, such as a stepper, or a scanning exposure type projection exposure apparatus (scanning type exposure apparatus), such as a scanning stepper, can be used as the exposure apparatus.
In recent years, a liquid immersion type exposure apparatus has been realized wherein a space between the projection optical system and the wafer is filled with a liquid that has a refractive index that is higher than that of gas, thereby increasing the numerical aperture of the projection optical system and improving resolution. Japanese Patent Application, Publication No. 2005-19864 A discloses a technology that uses this type of exposure apparatus, wherein a plane parallel plate, which is set at a height position that is the same as that of the wafer, is provided, liquid is temporarily transferred between the projection optical system and the wafer onto the plane parallel plate when exchanging the wafer by moving the plane parallel plate to a position that is directly below the projection optical system while retracting the wafer from its position directly therebelow, and then, after the exchange is complete, a new wafer is disposed at the position that is directly below the projection optical system while retracting the plane parallel plate that is positioned directly therebelow, and thereby the space between the projection optical system and the new wafer is filled with a liquid.
Incidentally, when liquid is transferred between two members, i.e., when liquid that is between the projection optical system and the wafer is transferred to the plane parallel plate temporarily, as disclosed in the abovementioned Patent Document 1, or when liquid that was transferred to the plane parallel plate is transferred back to the wafer, if a gap that is of a prescribed width or greater arises between those members, then there is a risk that the liquid will leak. In addition, if a step of a prescribed height or greater is created between those members, then there is a risk that the liquid will not be transferred completely and that some of it will remain. If liquid leaks, then it is conceivable that it will infiltrate the interior of the stage where it will cause rust or the like, which would degrade the performance of the substrate stage. In addition, there is also a risk that the heat of vaporization of the liquid will cause the temperature of the stage to fluctuate, which will lead to a decrease in exposure accuracy (for example, resolution, transfer fidelity, superpositional accuracy, and line width error).
A purpose of some aspects of the present invention is to provide a stage apparatus and an exposure apparatus that can transfer a liquid without any of that liquid leaking or remaining behind.
A first aspect of the invention provides a stage apparatus that comprises: first and second stages that move along a base surface; a first measurement apparatus that measures a first gap between the first and second stages along a first direction that intersects the base surface; and a first adjustment apparatus that adjusts the first gap based on a measurement result of the first measurement apparatus.
According to this stage apparatus, the first measurement apparatus measures the relative position between the first stage and the second stage in the intersecting direction and, based on the measurement result, the first adjustment apparatus adjusts the relative position between the first stage and the second stage.
A second aspect of the invention provides a stage apparatus that comprises: first and second stages that move along a base surface; a measuring apparatus that measures the positions of the first and second stages along the base surface; a detection apparatus that detects an edge of an upper surface of the first stage and an edge of an upper surface of the second stage; and an adjustment apparatus that adjusts the position of at least one stage of the first and second stages along the base surface based on a measurement result of the measuring apparatus and a detection result of the detection apparatus.
According to this stage apparatus, the detecting apparatus detects the positions of the first stage and the second stage in the first direction, the detection apparatus detects the edge part of the upper surface of the first stage and the edge part of the upper surface of the second stage, and, based on these detection results, the adjustment apparatus adjusts the position of at least one of the first stage and the second stage in the first direction.
A third aspect of the present invention provides an exposure apparatus, which exposes a substrate through a liquid, that comprises: a stage apparatus according to the first aspect, wherein the first measurement apparatus measures the first gap without transiting through the liquid.
A fourth aspect of the present invention provides an exposure apparatus, which exposes a substrate through a liquid, that comprises: a stage apparatus according to the second aspect, wherein the detection apparatus detects an edge of an upper surface of the first stage and detects an edge of the upper surface of the second stage without transiting through the liquid.
A fifth aspect of the present invention provides a device fabricating method that comprises an exposure process wherein the abovementioned exposure apparatus is used.
A sixth aspect of the present invention provides a method of moving an immersion area between a first member and a second member, which are capable of relative movement, to perform immersion exposure that comprises: a first step that moves a liquid between the first member and the second member; and a second step that, prior to the first step, measures the positional relationship between the first member and the second member.
A seventh aspect of the present invention provides an exposing method that exposes a substrate, which is held by a first member, through a liquid, comprising: a first step that moves a liquid between the first member and a second member, which is capable of moving relative to the first member; and a second step that, prior to the first step, measures the positional relationship between the first member and the second member.
An eighth aspect of the present invention provides a device fabricating method that comprises an exposure process, wherein the abovementioned exposing method is used.
A ninth aspect of the present invention provides an exposing method that is a method of fabricating an exposure apparatus that exposes a substrate through a liquid, comprising: a step that supplies the abovementioned stage apparatus; and a step that measures the positional relationship between the first stage and the second stage without transiting through the liquid.
Some aspects of the present invention measure the relative position between a first stage and a second stage and, based thereon, adjusts the relative position between the stages; thereby, it is possible to transfer a liquid between the first stage and the second stage without the liquid leaking or remaining behind.
The following explains the details of a stage apparatus and an exposure apparatus according to one embodiment of the present invention, referencing the drawings.
Furthermore, in the explanation below, an XYZ orthogonal coordinate system is defined in the figures and the positional relationships of members are described referencing this system as needed. The XYZ orthogonal coordinate system as shown in
As shown in
The reticle R, wherein a pattern is formed on its pattern surface (on the −Z side in
The position of the reticle stage RST within its plane of movement (including the rotation about the Z axis) is continuously detected by a laser interferometer (hereinafter, referred to as a reticle interferometer) 12 that has a resolving power of, for example, approximately 0.5-1 nm, via a movable mirror 13 (actually, a Y movable mirror that has a reflecting surface that is orthogonal to the Y axis and an X movable mirror that has a reflecting surface that is orthogonal to the X axis are provided). Measurement values of the reticle interferometer 12 are output to the main control apparatus 20 (not shown in
Two reticle alignment detection systems 14a, 14b, each of which uses light of a wavelength that is the same as the exposure wavelength and comprises a through the reticle (TTR) alignment system, are provided above the reticle stage RST so that they are spaced apart by a prescribed distance in the X directions. The reticle alignment detection systems 14a, 14b simultaneously observe a pair of reticle alignment marks on the reticle R and conjugate images of a corresponding pair of fiducial marks on the measurement stage MST through the projection optical system PL. A system that is configured similarly to the one disclosed in, for example, Japanese Patent Application, Publication No. H7-176468 A (corresponding U.S. Pat. No. 5,646,413) is used for both of the reticle alignment detection systems 14a, 14b.
The projection unit PU includes the projection optical system PL, which comprises a lens barrel 15 and multiple optical elements that are held therein with prescribed positional relationships. A dioptric system that comprises multiple lenses (lens elements), each of which has a common optical axis AX in the Z directions or the like, is used as the projection optical system PL. In addition, although not shown, an imaging characteristics correction controller 16 (refer to
In addition, in order to perform an exposure wherein the exposure apparatus EX of the present embodiment adopts a liquid immersion method, a liquid supply nozzle 18a and a liquid recovery nozzle 18b of a liquid immersion apparatus 17 are provided in the vicinity of a lens (hereinbelow, also called a front lens) GL, which is the optical element that is closest to the image plane (the wafer W side) of the projection optical system PL. One end of a supply pipe (not shown) is connected to a liquid supply apparatus 19a (not shown in
Here, ultrapure water (unless otherwise required, hereinafter simply referred to as “water”), which transmits ArF excimer laser light (light of a 193 nm wavelength), is used as the abovementioned liquid. Ultrapure water is advantageous in that it can be obtained easily in large quantities at semiconductor fabrication plants and the like and does not adversely affect the optical lenses and the photoresist on, for example, the wafer W. Here, the refractive index n of water is substantially 1.44 and the wavelength of the illumination light IL in water is shortened to approximately 134 nm (193 nm×1/n). In addition, an immersion area may be formed by supplying liquid of a temperature that is substantially the same as that of the wafer W. Thereby, it is possible to prevent, for example, thermal deformation of the wafer W that is caused by a temperature differential between the liquid and the wafer W.
In accordance with an instruction from the main control apparatus 20, the liquid supply apparatus 19a opens a valve that is connected to the supply pipe by a prescribed opening degree and supplies water through the liquid supply nozzle 18a to the space between the front lens GL and the wafer W. In addition, in accordance with an instruction from the main control apparatus 20, the liquid recovery apparatus 19b opens a valve that is connected to the recovery pipe by a prescribed opening degree and recovers the water from the space between the front lens GL and the wafer W through the liquid recovery nozzle 18b and stores it in the liquid recovery apparatus 19b (a tank of liquid). At this time, the main control apparatus 20 issues commands to the liquid supply apparatus 19a and the liquid recovery apparatus 19b so that the amount of water that is supplied through the liquid supply nozzle 18a and the amount of water that is recovered through the liquid recovery nozzle 18b to and from, respectively, the space between the front lens GL and the wafer W are always equal. Accordingly, a fixed amount of water Lq (refer to
As explained above, the liquid immersion apparatus 17 of the exposure apparatus EX according to the present embodiment is a local liquid immersion apparatus that comprises the liquid supply apparatus 19a, the liquid recovery apparatus 19b, the supply pipe, the recovery pipe, the liquid supply nozzle 18a, and the liquid recovery nozzle 18b.
The stage apparatus ST comprises: a frame caster FC, which is disposed, for example, on a floor surface FL of a semiconductor fab; a base plate 21, which is provided on the frame caster FC; the wafer stage WST and the measurement stage MST, which are disposed above the base plate 21 and move along an upper surface 21a (a moving surface) thereof; an interferometer system 24 (refer to
The following explains the details of the configuration of the stage apparatus ST.
As shown in
In addition, the wafer stage WST comprises: a first drive system 27, which drives the wafer stage main body 26 with a long stroke in the X directions and also finely drives the wafer stage main body 26 in the Y, the Z, the θx (rotation around the X axis), the θy (rotation around the Y axis), and the θz (rotation around the Z axis) directions; and second drive systems 28a, 28b that drive the wafer stage main body 26 and the first drive system 27 with a long stroke in the Y directions. Furthermore, the wafer stage WST comprises a tube carrier 29, which moves in the X directions with uniform motion, and a pipe (not shown) that has six degrees of freedom and transmits the force of, for example, a vacuum or air, from the tube carrier 29 to the wafer stage main body 26. Here, the uniform motion of the tube carrier 29 in the X directions is for the purpose of reducing the impact of the reaction force that is generated by the drive thereof on the wafer stage main body 26.
Three openings are formed in the side surfaces of the wafer stage main body 26 on both the +X side and the −X side. A Y axis stator 33, which comprises a plurality of coils, is provided so that it passes through the wafer stage main body 26 through the substantially center opening of the three openings in each side surface. In addition, two X axis stators 34a, 34b are provided so that they pass through the wafer stage main body 26 through the two of the three openings, which are formed in each side surface, that sandwich, in the Y directions, the opening through which the Y axis stator 33 passes. Furthermore, a permanent magnet is provided to each of the three openings discussed above.
The abovementioned Y axis stator 33 cooperates with the permanent magnet that is provided to the opening through which the Y axis stator 33 passes and finely drives the wafer stage main body 26 in the Y directions. In addition, the abovementioned two X axis stators 34a, 34b cooperate with the permanent magnets, which are provided to the openings through which the X axis stators 34a, 34b pass, and drive the wafer stage main body 26 with a long stroke in the X directions. Here, it is possible to rotate the wafer stage main body 26 in the θz directions by creating a difference in the drive amounts of the X axis stators 34a, 34b.
Namely, the first drive system 27 comprises: a moving magnet type linear motor, which comprises the X axis stators 34a, 34b and permanent magnets; and a moving magnet type linear motor, which comprises the Y axis stator 33 and permanent magnets. Furthermore, the above explained an exemplary case wherein moving magnet type linear motors are provided, but moving coil type linear motors may be provided. In addition, as described above, the wafer stage WST is a guideless stage that does not have a guide member that guides its movement in the X directions.
In addition, two Z axis stators (not shown), which extend in the X directions, and corresponding permanent magnets (not shown) are provided below the wafer stage main body 26. It is possible to drive the wafer stage main body 26 in the Z, the θx, and the θy directions by separately controlling the drive amount of each of the Z axis stators. In addition, a stator 37, which extends in the X directions, is provided in order to drive the tube carrier 29 in the X directions. Furthermore, both ends of the abovementioned Y axis stator 33, the X axis stator 34a, 34b, the Z axis stators, and the stator 37 are fixed to sliders 39a, 39b, which constitute the second drive systems 28a, 28b.
Y axis stators 38a, 38b, which extend in the Y directions and constitute the second drive systems 28a, 28b, are provided and disposed above the protruding parts FCa, FCb, respectively, of the frame castor FC. Aerostatic bearings (not shown), e.g., air bearings, that are provided to the lower surfaces of the Y axis stators 38a, 38b levitationally support these Y axis stators 38a, 38b above the protruding parts FCa, FCb, respectively, with a prescribed clearance. The reaction force that is generated by the movement of the wafer stage WST or the measurement stage MST in the Y directions moves the stators 38a, 38b, which serve as Y countermasses in the Y directions, in the reverse direction and is thereby offset by the law of conservation of momentum.
The wafer stage main body 26, which was discussed above, and the like are disposed between these stators 38a, 38b, and the sliders 39a, 39b, to which both ends of the Y axis stator 33, the X axis stator 34a, 34b, the Z axis stators, and the stator 37 are fixed, are inserted in the stators 38a, 38b, respectively, from their inner sides. That is, the slider 39a is inserted from the medial side of the stator 38a, and the slider 39b is inserted from the medial side of the stator 38b. The stators 38a, 38b comprise permanent magnets, which are arrayed in the Y directions, and the sliders 39a, 39b comprise coils, which are arrayed in the Y directions. Namely, the second drive systems 28a, 28b comprise moving coil type linear motors that drive the wafer stage WST in the Y directions. Furthermore, the above explained an exemplary case wherein moving coil type linear motors are provided, but moving magnet type linear motors may be provided.
With the exception of the electromagnetic coupling between the stator 38a and the slider 39a and between the stator 38b and the slider 39b, the wafer stage WST is a guideless stage that does not have a guide member that guides its movement in the Y directions. Furthermore, the reaction force that is generated when the wafer stage WST moves in the X directions is transmitted to X countermasses (not shown) through the electromagnetic coupling between the stator 38a and the slider 39a and between the stator 38b and the slider 39b, which are provided to the second drive systems 28a, 28b. These X countermasses are provided between the stator 38a and the protruding part FCa of the frame castor FC and between the stator 38b and the protruding part FCb of the frame castor FC, and are configured so that they hold the stators 38a, 38b, which are used as countermasses in the Y directions, and are movable in the X directions. The X countermasses move in a direction that is the reverse of that of the X directional movement of the wafer stage WST and/or the measurement stage MST, and thereby offsets the reaction force that is generated when the wafer stage WST is driven in the X directions. Furthermore, with the stage apparatus ST of the present embodiment, the X countermasses and the Y countermasses are shared by the wafer stage WST and the measurement stage MST, but just the X countermasses or just the Y countermasses may be shared by the wafer stage WST and the measurement stage MST.
A wafer holder 40, which holds the wafer W, is provided on the wafer table WTB. The wafer holder 40 comprises a plate shaped main body part and a liquid repellent (water repellent) auxiliary plate, wherein a circular aperture (the diameter of which is larger than that of the wafer W) is formed at its center, that is fixed to the upper surface of the main body part. Numerous (a plurality of) pins are disposed in an area of the main body part inside the circular opening of the auxiliary plate. The numerous pins vacuum chuck the wafer W in a supported state. In this state, wherein the wafer W is vacuum chucked, the height of the front surface of the wafer W and that of the front surface of the auxiliary plate are substantially the same. Furthermore, liquid repellency may be imparted to the front surface of the wafer table WTB without providing the auxiliary plate.
In addition, as shown in
The X axis interferometer 42 and the Y axis interferometer 23 receive the light reflected from the reflecting surfaces 41X; 41Y, respectively, and thereby detect the displacements of the reflecting surfaces 41X, 41Y in the measurement directions from reference positions (generally, fixed mirrors are disposed on the side surfaces of the projection unit PU and/or the side surfaces of an off-axis type alignment system 45, which is disposed on the +Y direction side of the projection optical system PL—refer to
The X axis interferometer 42 has a length measuring axis that passes through the center of projection of the projection optical system PL (the optical axis AX; refer to
In other words, the X axis interferometer 42 is capable of measuring the position of the wafer table WTB or the measurement table MTB in the X directions at the projection center position and the alignment center position in the Y directions. Furthermore, the baseline quantity is a quantity that indicates the positional relationship of the wafer stage WST with respect to the projected image of the pattern that is projected by the projection optical system PL; specifically, it is the distance between the center of projection of the projection optical system PL and the center of the measurement field of the alignment system 45. The Y axis interferometer 23 has a length measuring axis that is parallel to the Y axis and that connects the center of projection of the projection optical system PL (the optical axis AX; refer to
With the exceptions of the tube carrier 29 and the pipe (not shown) that has six degrees of freedom, the measurement stage MST has a configuration that is substantially similar to that of the wafer stage WST. Namely, as shown in
Similar to the first drive system 27 that is provided to the wafer stage WST, the first drive system 47 comprises: pairs of permanent magnets, which are disposed in each of the three openings provided to the end surfaces of the measurement stage main body 46 in the +X and −X directions, and one Y axis stator and two X axis stators, which each comprise a plurality of coils so that they pass through the measurement stage main body 46 in the X directions through each of the openings. The permanent magnets along with the X axis stators and the Y axis stator drive the measurement stage main body 46 with a long stroke in the X directions, finely drive it in the Y directions, and rotate it in the θz directions. In addition, the first drive system 47 comprises permanent magnets, which are provided to the lower surface of the measurement stage main body 46, and Z axis stators, which cooperate with the permanent magnets and generate thrust. These permanent magnets and Z axis stators can drive the measurement stage main body 46 in the Z directions, the θx, and the θy directions. Furthermore, the above explained an exemplary case wherein the first drive system 47 comprises moving magnet type linear motors, but it may comprise moving coil type linear motors.
The second drive systems 48a, 48b comprise the stators 38a, 38b and sliders 49a, 49b that are fixed to both ends of the X axis stators that pass through the measurement stage main body 46 in the X directions, the Y axis stators, and Z axis stators that are disposed below (in the −Z direction of) the measurement stage main body 46; in addition, the sliders 49a, 49b are inserted in the stators 38a, 38b from their inner sides. That is, the slider 49a is inserted from the medial side of the stator 38a, and the slider 49b is inserted form the medial side of the stator 38b. The sliders 49a, 49b comprise coils, which are arrayed in the Y directions, and cooperate with the stators 38a, 38b, which comprise the permanent magnets that are arrayed in the Y directions, to generate thrust in the Y directions. Namely, the second drive systems 48a, 48b comprise moving coil type linear motors that drive the measurement stage MST in the Y directions. Thus, in the present embodiment, the stators 38a, 38b are configured so that the linear motors (the actuator parts) that drive the wafer stage WST in the Y directions and the linear motors (the actuator parts) that drive the measurement stage MST in the Y directions are shared. Furthermore, the above explained an exemplary case wherein moving coil type linear motors are provided, but moving magnet type linear motors may be provided.
At least part of the stage drive part 25 shown in
The measurement table MTB is formed from, for example, a low thermal expansion material, such as Zerodur® made by Schott Nippon K.K., and its upper surface is liquid repellent (water repellent). The measurement table MTB is held on the measurement stage main body 46 by, for example, vacuum chucking, and is configured so that it is exchangeable. The height of the front surface of the measurement table MTB is set so that it is substantially identical to that of the front surface of the wafer holder 40, which is provided on the wafer table WTB. A reflecting surface 51X that is orthogonal to the X directions (i.e., extends in the Y directions) is formed by mirror polishing at one end (the +X side end) of the measurement table MTB in the X directions. Likewise, a reflecting surface 51Y, which is orthogonal to the Y directions (i.e., extends in the X directions) is formed by mirror polishing at one end (the −Y side end) of the measurement table MTB in the Y directions.
Interferometer beams (beams) from the X axis interferometer 42 and the Y axis interferometer 22, which constitute the interferometer system 24 (refer to
Furthermore, instead of the configuration wherein the reflecting surfaces 51x, 51Y are formed on the end surfaces of the measurement table MTB, a configuration is also acceptable wherein a Y movable mirror that has a reflecting surface (51Y) that extends in the X directions and an X movable mirror that has a reflecting surface (51X) that extends in the Y directions are provided to the upper surface of the measurement table MTB. Similar to the Y axis interferometer 23, the abovementioned Y axis interferometer 22 has a length measuring axis that is parallel to the Y axis and that connects the center of projection (the optical axis AX; refer to
In addition, the measurement stage MST further comprises a measuring instrument group for performing various measurements related to the exposure. Examples of measuring instruments in the measuring instrument group include an aerial image measuring apparatus, a wavefront aberration measuring apparatus, and an exposure detection apparatus. The aerial image measuring apparatus measures an aerial image that is projected onto the measurement table MTB through the projection optical system PL and the water Lq. In addition, the wavefront aberration measuring apparatus disclosed in, for example, PCT International Publication WO 99/60361 (corresponding European Patent No. 1,079,223) can be used as the abovementioned wavefront aberration measuring apparatus.
In addition, the exposure detection apparatus is a detection apparatus that acquires information (for example, the amount of light, the luminous flux intensity, and the luminous flux intensity nonuniformity) that is related to the exposure energy of the exposure light that is irradiated onto the measurement table MTB through the projection optical system PL, and it is possible to use a luminous flux intensity nonuniformity measuring instrument as disclosed in, for example, Japanese Patent Application, Publication No. S57-117238 A (corresponding U.S. Pat. No. 4,465,368) or a luminous flux intensity monitor as disclosed in, for example, Japanese Patent Application, Publication No. H11-16816 A (corresponding U.S. Patent Application, Publication No. 2002/0061469) as the exposure detection apparatus. Furthermore, in
A fiducial plate 53, which serves as a measurement pattern part wherein various marks are formed that are used by the measuring instrument group or the alignment system 45 (refer to
Returning to
Furthermore, returning to
The operation of the exposure apparatus EX as configured above will now be explained. In the exposure apparatus EX of the present embodiment, the wafer W is exposed in a state wherein the main control apparatus 20 controls the switching of the valves of both the liquid supply apparatus 19a and the liquid recovery apparatus 19b of the liquid immersion apparatus 17 so as to fill the space directly below the front lens GL of the projection optical system PL with the water Lq. When the exposure of the wafer W that is held on the wafer stage WST is complete, the wafer stage WST moves to the loading position in order to exchange the wafer W, and the measurement stage MST moves to a position below (in the −Z direction of) the projection optical system PL in order to perform various measurements.
At this time, the measurement stage MST approaches the wafer stage WST and both stages move integrally, and thereby the water Lq that is directly below the front lens GL of the projection optical system PL is transferred to the measurement stage MST. When the transfer of the water Lq is complete, the wafer stage WST moves to the loading position and exchanges the wafer W, and the measurement stage MST remains below the projection optical system PL and performs various measurements.
When the exchange and the measurement of the wafer W are complete, the measurement stage MST moves to a prescribed retraction position, and the wafer stage WST moves to a position that is below (in the −Z direction of) the projection optical system PL. At this time, the wafer stage WST approaches the measurement stage MST, and both stages move integrally once again; thereby, the water Lq that is directly below the front lens GL of the projection optical system PL is transferred from the measurement stage MST to the wafer stage WST.
In addition, if a step (a gap G2) is created between the upper surface of the wafer stage WST (the front surface of the wafer holder 40) and the upper surface of the measurement stage MST (the front surface of the measurement table MTB) when the water Lq is transferred, then there is a risk that the water Lq will not be completely transferred and will remain on the original stage. Consequently, the gap G2 between the upper surfaces of both stages is controlled so that the water Lq does not remain. The gap G2 is set to, for example, less or equal to 0.1 mm.
The main control apparatus 20 controls the wafer stage WST and the measurement stage MST so that the gap G1 is, for example, less or equal to 0.5 mm, and the gap G2 is, for example, less or equal to 0.1 mm during the transfer of the water Lq. Nevertheless, a case is conceivable wherein, because of, for example, the accumulation of positional errors of each of the stages, the gap G1 cannot be maintained at less or equal to 0.5 mm or the gap G2 cannot be maintained at less or equal to 0.1 mm. In addition, if the wafer stage WST or the measurement stage MST rotate around the Z axis during the transfer of the water Lq, then it is conceivable that the gap G1 between the wafer stage WST and the measurement stage MST will change positionally.
Consequently, in the present embodiment, the alignment system 45 and the focus leveling detection system 64 are used to measure the relative position between the wafer stage WST and the measurement stage MST when the exposure apparatus EX starts up, during periodic maintenance, or when a reset is performed that sets the apparatus state of the exposure apparatus EX to its initial state in the event of a power outage or an error. Furthermore, during the measurement of the relative position, the valves of both the liquid supply apparatus 19a and the liquid recovery apparatus 19b are in a closed state, and therefore the water Lq is not supplied to the space directly below the front lens GL of the projection optical system PL.
At this time, the measurement stage MST is moved so that an edge part e1 of the measurement table MTB on the +Y direction side enters a measurement field of the alignment system 45. Next, the main control apparatus 20 drives the first drive system 47, which is provided to the measurement stage MST, so as to move the measurement stage MST in the +X direction, and, as shown in
Subsequently, the main control apparatus 20 drives the first drive system 47, which is provided to the measurement stage MST, so as to move the measurement stage MST in the −X direction, and, as shown in
Next, the main control apparatus 20 monitors the detection values of the Y axis interferometers 22, 23 shown in
When the movement is complete, the main control apparatus 20 drives the first drive system 27, which is provided to the wafer stage WST, so as to move the wafer stage WST in the +X direction, and, as shown in
Subsequently, the main control apparatus 20 drives the first drive system 27, which is provided to the wafer stage WST, so as to move the wafer stage WST in the −X direction, and, as shown in
The main control apparatus 20 derives position information about the measurement points P21, P22 in the measurement field by image processing each of the imaging signals of the measurement points P21, P22 that were obtained by the above process, and, based on this position information and the result of the detection by the Y axis interferometer 23 that was obtained at the point in time when the imaging signals were acquired, derives position information about the measurement points P21, P22 in the Y directions.
The relative positional relationship between the edge part e1 and the edge part e2 in the Y directions, i.e., the relative position between the wafer stage WST and the measurement stage MST in the Y directions, is derived based on position information about the measurement points P11, P12 and position information about the measurement points P21, P22 obtained from the above process. Because the edge part e1 is measured at the plurality of measurement points P11, P12 and the edge part e2 is measured at the plurality of measurement points P21, P22, it is also possible to derive the amount of deviation from parallelism of the edge part e1 and the edge part e2 that is caused by the rotation of the wafer stage WST or the measurement stage MST around the Z axis. Furthermore, information that indicates the relative position between the wafer stage WST and the measurement stage MST in the Y directions that was obtained by the above process is stored in the memory 65 (refer to
At this time, as shown in
Subsequently, the main control apparatus 20 drives the first drive system 27, which is provided to the wafer stage WST, so as to move the wafer stage WST in the −X direction, and disposes the wafer stage WST so that the detection area of the focus leveling detection system 64 is set so that it is on the wafer holder 40 in the vicinity of an end part of the edge part e2 in the +X direction (hereinbelow, called a measurement surface P32). In this state, the measurement surface P32 is detected using the focus leveling detection system 64. The detection result is supplied to the main control apparatus 20.
Next, the main control apparatus 20 monitors the detection values of the Y axis interferometers 22, 23 shown in
When the disposing of the stages WST, MST in the Y directions is complete, the main control apparatus 20 drives the first drive system 47, which is provided to the measurement stage MST, so as to move the measurement stage MST in the +X direction, and disposes the measurement stage MST so that the detection area of the focus leveling detection system 64 is set on the measurement table MTB in the vicinity of an end part of the edge part e1 in the −X direction (hereinbelow, called a measurement surface P41). In this state, the measurement surface P41 is detected using the focus leveling detection system 64. The detection result is supplied to the main control apparatus 20.
Subsequently, the main control apparatus 20 drives the first drive system 47, which is provided to the measurement stage MST, so as to move the measurement stage MST in the −X direction, and disposes the measurement stage MST so that the detection area of the focus leveling detection system 64 is set so that it is on the measurement table MTB in the vicinity of an end part of the edge part e1 in the +X direction (hereinbelow, called a measurement surface P42). In this state, the measurement surface P42 is detected using the focus leveling detection system 64. The detection result is supplied to the main control apparatus 20.
The relative positional relationship between the wafer holder 40 and the measurement table MTB in the Z directions, i.e., the relative position between the wafer stage WST and the measurement stage MST in the Z directions, is derived based on the results of the detection of the measurement surfaces P31, P32 and of the measurement surfaces P41, P42 obtained from the above process. Furthermore, information obtained from the above process that indicates the relative position between the wafer stage WST and the measurement stage MST in the Z directions is stored in the memory 65 (refer to
When the exposure apparatus EX starts up, when periodic maintenance is performed, or when a reset is performed, the process of exposing the wafer W is started after the measurement process explained above is complete. Next, the details of the exposure process will be explained. When a wafer W is exposed, the measurement stage MST is disposed at the prescribed retraction position, and the wafer stage WST, which holds the wafer W to be exposed, is disposed below (in the −Z direction of) the projection optical system PL.
Furthermore, in a state wherein there is no water Lq on the wafer W before the water Lq is supplied from the liquid supply apparatus 19a, a process of measuring an alignment mark that is formed on the wafer W is performed. Furthermore, it is assumed herein that the pattern of at least one layer is formed on the wafer W; however, if no layer pattern is formed on the wafer W at all, then the process of measuring an alignment mark is omitted.
In the measurement process, the main control apparatus 20 monitors the detection results of the X axis interferometer 42 and of the Y axis interferometer 23, and, while doing so, drives the first drive system 27 and the second drive systems 28a, 28b, which are provided to the wafer stage WST, so as to move the wafer stage WST along a prescribed pathway. Along the way of this movement, the alignment system 45 is used to measure a plurality of alignment marks formed on the wafer W without transiting through the water Lq. Furthermore, when the alignment mark is measured by the alignment system 45, the wafer stage WST is in a stopped state.
Thereby, the position of each alignment mark is measured within a coordinate system that is defined by the X axis interferometer 42 and the Y axis interferometer 23. Furthermore, when the alignment system 45 measures the alignment marks on the wafer W, it may measure all of the alignment marks, or only a portion thereof. In addition, if the alignment system 45 can measure the alignment mark on the wafer W while the wafer W is moved, then the wafer stage WST does not need to be set to the stopped state.
In addition, during the abovementioned movement of the wafer stage WST, front surface information about the wafer W is detected by the focus leveling detection system 64 without transiting through the water Lq. The focus leveling detection system 64 detects surface information for each shot region (not shown) that is set on the wafer W, and stores the detection results in the main control apparatus 20 associated with the position on the wafer W in the scanning directions (the Y axial directions). Furthermore, the focus leveling detection system 64 may detect the surface information of just a portion of the shot regions. In addition, either the operation of measuring position information of the plurality of alignment marks using the alignment system 45 or the operation of detecting surface information about the wafer W using the focus leveling detection system 64 may be completed before the other, and subsequently the other operation may be performed.
When the abovementioned measurements are complete, the main control apparatus 20 performs enhanced global alignment (EGA) calculation using the abovementioned alignment mark measurement results, derives the layout of all shot regions on the wafer W, and stores that layout information in the memory 65. In addition, the abovementioned detection results obtained using the focus leveling detection system 64 are stored in the memory 65. Furthermore, switching control of each valve of the liquid supply apparatus 19a and the liquid recovery apparatus 19b of the liquid immersion apparatus 17 is performed and the water Lq is supplied to the space between the front lens GL of the projection optical system PL and the wafer W (the wafer holder 40).
Next, the main control apparatus 20 reads out layout information of all shot regions from the memory 65, uses the previously obtained baseline quantity measurement results to correct the layout information, and then moves the wafer stage WST so that the shot region on the wafer W that is to be exposed first is disposed at the scanning start position. Furthermore, the main control apparatus 20 monitors the detection values of the X axis interferometer 42, the Y axis interferometer 23, and the reticle interferometer 12, and, while doing so, controls the drive of the reticle stage drive part 11 along with the first drive system 27 and the second drive systems 28a, 28b so as to scan the reticle R (the reticle stage RST) and the wafer W (the wafer stage WST) relative to the Y directions.
While the stages RST, WST are moved uniformly during scanning (after acceleration ends and immediately prior to the start of deceleration), the pattern of the reticle R is transferred to the first shot region that is to be exposed on the wafer W by causing the reticle R (the reticle stage RST) and the wafer W (the wafer stage. WST) to move in the Y directions with uniform and synchronous movement with respect to the illumination area of the illumination light IL. During the scanning of the reticle R and the wafer W, the front surface information, which was detected using the focus leveling detection system 64 prior to supplying the liquid Lq, is read out from the memory 65 and used to adjust the front surface position of the wafer W in the Z directions as well as its attitude. The abovementioned scanning is performed repetitively for all shot regions that are set on the wafer W.
When the exposure of the wafer W, which is held on the wafer stage WST, is complete, the main control apparatus 20 controls the drive of the first drive system 47 and the second drive systems 48a, 48b, which are provided to the measurement stage MST, based on the detection value of the Y axis interferometer 22 so as to bring the measurement stage MST proximate to the wafer stage WST. At this time, the main control apparatus 20 reads out the information that indicates the relative position between the wafer stage WST and the measurement stage MST (the information that is obtained by the measurements described in
Furthermore, the main control apparatus 20 transfers the water Lq on the wafer stage WST onto the measurement stage MST by moving both of the stages WST, MST in the +Y direction in a state wherein the abovementioned positional relationship is maintained. At this time, the abovementioned control ensures that the gap G1 between the wafer stage WST and the measurement stage MST is, for example, less or equal to 0.5 mm, which makes it possible to prevent the water Lq from leaking out of the space between the wafer stage WST (the wafer holder 40) and the measurement stage MST (the measurement table MTB). In addition, the abovementioned control ensures that the gap G2 between the wafer stage WST and the measurement stage MST is, for example, less or equal to 0.1 mm, which makes it possible to prevent the water Lq from remaining on the wafer stage WST.
Subsequently, the main control apparatus 20 controls the position of the wafer stage WST based on the detection values of the X axis interferometer 42 and the Y axis interferometer 23, and, while doing so, controls the drives of the first drive system 27 and the second drive systems 28a, 28b, which are provided to the wafer stage WST, so as to move the wafer stage WST to the prescribed loading position, and then exchanges the wafer W. Parallel therewith, prescribed measurements that use the measurement stage MST are performed as needed. These measurements include, for example, the measurement of the baseline quantity of the alignment system 45 after the reticle on the reticle stage RST has been exchanged.
When the abovementioned exchange of the wafer W on the wafer stage WST and the measurement using the measurement stage MST are complete, the main control apparatus 20 brings the wafer stage WST proximate to the measurement stage MST and once again performs the control discussed above so as to move both of the stages WST, MST in the −Y direction in a state wherein the positional relationship between the wafer stage WST and the reticle stage RST is maintained. Thereby, the water Lq on the measurement stage MST is transferred onto the wafer stage WST. At this time, the gap G1 shown in
When the transfer of the water Lq is complete, the main control apparatus 20 moves the measurement stage MST to the prescribed retraction position and returns the wafer stage WST to a position that is directly below the projection unit PU. Furthermore, on the wafer stage WST side, wafer alignment is performed on the wafer W after the exchange, i.e., the alignment system 45 detects an alignment mark on the exchanged wafer W and performs EGA calculations in order to derive the positional coordinates of the multiple shot regions on the wafer W. Subsequently, the main control apparatus 20 performs a step-and-scan system exposure operation on the new wafer W, similar to that described above, and successively transfers the reticle pattern to the multiple shot regions on the wafer.
Furthermore, in the previously discussed measurement wherein the alignment system 45 is used to measure the relative position between the wafer stage WST and the measurement stage MST in the Y directions, the alignment system 45 sequentially measures two locations (the measurement points P11, P12) of the edge part e1 of the measurement stage MST (the measurement table MTB) and two locations (the measurement points P21, P22) of the edge part e2 of the wafer stage WST (the wafer holder 40) as was explained using
In addition, in the embodiment explained above, the alignment system 45 measures the relative position between the wafer stage WST and the measurement stage MST in the Y directions, and the focus leveling detection system 64 measures the relative position between the wafer stage WST and the measurement stage MST in the Z directions. Alternatively, it is possible not only to measure the position information of the marks in the XY plane, but also to use an alignment system than can detect the focus state to measure the relative position between the wafer stage WST and the measurement stage MST in the Y directions and the Z directions simultaneously.
Namely, the focus state detection system 70 detects the amount of deviation between the imaging plane position of the imaging device 74 and the imaging position of the reflected light image from the front surface of the wafer W in the focus directions as a change in the spacing between the images that are imaged at different positions in the imaging plane of the imaging device 74 (the images resulting from the division by the pupil dividing mirror 72). Here, as shown in part (a) of
As shown in part (b) of
In addition, as shown in
With the configurations shown in
The above explained the embodiments of the present invention, but the specific constitution is not limited to these embodiments, and it is understood that variations and modifications may be effected without departing from the spirit and scope of the invention. For example, in the embodiment discussed above, the alignment system 45, which is provided in order to measure the alignment marks on the wafer W, and the focus leveling detection system 64, which is provided in order to detect the front surface position of the wafer W in the Z directions and its attitude, are used to measure the relative position between the wafer stage WST and the measurement stage MST. Alternatively, specialized measuring apparatuses for measuring these relative positions may be provided and used in these measurements.
For example, the relative position in the Y directions may be measured by providing a measuring apparatus to either the wafer stage WST or the measurement stage MST, and then measuring the distance to the other stage. When performing such a measurement, a configuration is preferable wherein the distance between the edge parts e1, e2 (refer to
In addition, the abovementioned embodiment explained an exemplary case wherein ArF excimer laser light is used, but it is also possible to use, for example, g line light (436 nm wavelength), i line light (365 nm wavelength), KrF excimer laser light (248 nm wavelength), F2 laser light (157 nm wavelength), Kr2 laser light (146 nm wavelength), YAG laser light, or the high frequency light of a semiconductor laser. Furthermore, higher harmonics may also be used by using, for example, an erbium (or erbium-ytterbium) doped fiber amplifier to amplify single wavelength laser light in the infrared region or the visible region that is oscillated from a DFB semiconductor laser or a fiber laser, and then using a nonlinear optical crystal to perform wavelength conversion so as to convert the output laser light to ultraviolet light. For example, if the oscillating wavelength of the single wavelength laser is in the range of 1.51 to 1.59 μm, then the eighth harmonic, wherein the generating wavelength is in the range of 189 to 199 nm, or the tenth harmonic, wherein the generating wavelength is in the range of 151 to 159 nm, is output.
Furthermore, in each of the abovementioned embodiments, the position information of the reticle stage RST and the wafer stage WST is measured using the interferometer system (24), but the present invention is not limited thereto and, for example, an encoder system may be used that detects a scale (diffraction grating) that is provided to each stage. In this case, the system is configured as a hybrid system that is provided with both an interferometer system and an encoder system, and it is preferable to use the measurement results of the interferometer system to calibrate the measurement results of the encoder system. In addition, the positions of the stages may be controlled by switching between the interferometer system and the encoder system, or by using both.
In addition, the present invention can also be adapted to a twin stage type exposure apparatus, which is provided with a plurality of wafer stages. The structure and exposure operation of a twin stage type exposure apparatus is disclosed in, for example, Japanese Patent Application, Publication No. H10-163099 A, Japanese Patent Application, Publication No. H10-214783 A (corresponding U.S. Pat. Nos. 6,341,007, 6,400,441, 6,549,269 and 6,590,634), Published Japanese Translation No. 2000-505958 of the PCT International Publication (corresponding U.S. Pat. No. 5,969,441), or U.S. Pat. No. 6,208,407. In this case, the gaps G1, G2 between multiple wafer stages may be controlled instead of between the wafer stage WST and the measurement stage MST, and the water Lq may be transferred between the multiple wafer stages. Furthermore, the gaps G1, G2 between the wafer stage WST and a stage that does not have a measuring function may be controlled, and the water Lq transferred therebetween. Furthermore, the present invention may be adapted to the wafer stage disclosed in Japanese Patent Application No. 2004-168481 (corresponding PCT International Publication No. WO 2005/122242), which was previously filed by the present applicant.
In addition, the projection optical system PL may be telecentric on both the object plane (the reticle R) side and the image plane (the wafer W) side, or it may be telecentric on just one side. Furthermore, a unity magnification image of the pattern image of a reticle R may be projected in addition to a reduced image thereof that is projected by a reduction system. Furthermore, a catoptric system, which comprises only catoptric elements, or a catadioptric system, which comprises catoptric elements and dioptric elements, may be used as the projection optical system PL. Furthermore, in accordance with the wavelength of the illumination light IL, quartz, fluorite, or the like may be used as the glass material of the multiple lens elements that constitute the projection optical system PL.
Furthermore, the substrate held by the movable stage in each of the abovementioned embodiments is not limited to a semiconductor wafer for fabricating semiconductor devices, but can also be adapted to, for example, a glass substrate for a display device, a ceramic wafer for a thin film magnetic head, or the original plate (synthetic quartz or a silicon wafer) of a mask or a reticle that is used in an exposure apparatus. The exposure apparatus EX can also be adapted to a scanning type exposure apparatus that does not use the liquid immersion method, as well as to a step-and-repeat type projection exposure apparatus (stepper) that exposes the full field of the pattern of the reticle R with the reticle R and the wafer W in a stationary state, and sequentially steps the wafer W. In addition, the present invention can also be adapted to a step-and-stitch system exposure apparatus that partially and superimposingly transfers at least two patterns onto the wafer W. The type of exposure apparatus EX is not limited to a semiconductor device fabrication exposure apparatus that exposes the pattern of a semiconductor device on the wafer W, but can also be widely adapted to an exposure apparatus that is used for fabricating, for example, liquid crystal devices or displays, and an exposure apparatus that is used for fabricating thin film magnetic heads, imaging devices (CCDs), micromachines, MEMS, DNA chips, or reticles and masks.
In addition, each of the abovementioned embodiments was explained by taking as an example an exposure apparatus that is provided with the projection optical system PL, but the present invention can be adapted to an exposure apparatus and an exposure method that do not use the projection optical system PL. Even if a projection optical system is not used, exposure light is radiated onto the substrate through optical members, such as a mask or a lens, and an immersion region is formed in a prescribed space between the substrate and such optical members.
Furthermore, in the embodiments discussed above, a light transmitting type mask is used wherein a prescribed shielding pattern (or a phase pattern or a dimming pattern) is formed on a light transmitting substrate; however, instead of such a mask, it is also possible to use an electronic mask wherein a transmittance pattern, a reflected pattern, or a light emitting pattern is formed based on electronic data of the pattern to be exposed, as disclosed in, for example, U.S. Pat. No. 6,778,257; here, electronic masks, which are also called variable forming masks, include, for example, a digital micromirror device (DMD), which is one type of a non light emitting image display device (spatial light modulator).
Furthermore, the present invention can also be adapted to an exposure apparatus that combines, through a projection optical system, the patterns of two masks on a substrate, and double exposes, substantially simultaneously, a single shot region on the substrate with a single scanning exposure, as disclosed in, for example, Published Japanese Translation No. 2004-519850 of the PCT International Publication (corresponding U.S. Pat. No. 6,611,316).
If a linear motor is used in the wafer stage WST or the reticle stage RST (refer to U.S. Pat. No. 5,623,853 and U.S. Pat. No. 5,528,118), then either an air levitation type that uses an air bearing, or a magnetic levitation type that uses Lorentz's force or reactance force may be used. In addition, each of the stages WST, RST may be a type that moves along a guide or may be a guideless type. A planar motor may be used for the drive mechanism of each of the stages WST, RST; in each stage, the planar motor causes a magnet unit, wherein magnets are disposed two dimensionally, and an armature unit, wherein coils are disposed two dimensionally, to oppose one another, and drives each the stage using electromagnetic force. In this case, for each of the stages WST, RST, either the magnet unit or the armature unit should be connected to the stage, and the other unit should be provided on the moving surface side of the stage.
The reaction force generated by the movement of the wafer stage WST may be mechanically discharged to the floor (ground) by using a frame member so that it is not transmitted to the projection optical system PL, as recited in Japanese Patent Application, Publication No. H08-166475 A (U.S. Pat. No. 5,528,118). The reaction force generated by the movement of the reticle stage RST may be mechanically discharged to the floor (ground) by using a frame member so that it is not transmitted to the projection optical system, as recited in Japanese Patent Application, Publication No. H08-330224 (corresponding U.S. Pat. No. 5,874,820).
As far as is permitted, the disclosures in all of the Publications and U.S. patents related to exposure apparatuses and the like cited in the above respective embodiments and modified examples, are incorporated herein by reference.
As described above, the exposure apparatus EX of the embodiments in the present application is manufactured by assembling various subsystems, including each constituent element, so that prescribed mechanical, electrical, and optical accuracies are maintained. To ensure these various accuracies, adjustments are performed before and after this assembly, including an adjustment to achieve optical accuracy for the various optical systems, an adjustment to achieve mechanical accuracy for the various mechanical systems, and an adjustment to achieve electrical accuracy for the various electrical systems. The process of assembling the exposure apparatus EX from the various subsystems includes interconnecting the various subsystems, e.g., interconnecting mechanical components, electrical circuits, and atmospheric pressure circuit pipes. Naturally, the processes of assembling each individual subsystem are performed before the process of assembling the exposure apparatus EX from these various subsystems is performed. When the process of assembling the exposure apparatus EX from the various subsystems is complete, a comprehensive adjustment is performed to ensure the various accuracies of the exposure apparatus EX as a whole. Furthermore, it is preferable to manufacture the exposure apparatus in a clean room, wherein the temperature, the cleanliness level, and the like are controlled.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2005-227666 | Aug 2005 | JP | national |
This is a Continuation Application of International Application No. PCT/JP2006/315422, filed Aug. 3, 2006, which claims priority to Japanese Patent Application No. 2005-227666, filed Aug. 5, 2005. The contents of the aforementioned application are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2006/315422 | Aug 2006 | US |
| Child | 12068199 | US |
