JP2005079363A - Aligner, optical member, and exposing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner capable of accurately adjusting a relative position between a mask and a photosensitive substrate even a both side telecentricity of a projection optical system is in an unsatisfactory state. <P>SOLUTION: The aligner projects an image of a transfer pattern formed on a mask R arranged on a first face on a photosensitive substrate W arranged on a second face. The aligner comprises a projection optical system PL for forming the image of the transfer pattern on the mask to the second face; an alignment optical system RAL for supplying an alignment beam to a first mark RM positioning on the first face and a second mark WFM positioning on the second face, and detecting the relative positional relationship of the first mark and the second mark on the basis of the beam from the first mark and the second mark; first optical members 18, 19 arranged between the first face and the projection optical system in an insertion and a pulling-out capable manner and polarizing the alignment beam from the alignment optical system; and a second optical member 18 for correcting a change in optical path length of the alignment beam from the alignment optical system caused by the insertion and pulling-out of the first optical member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus used in a manufacturing process of a semiconductor element, a liquid crystal display element, and other microdevices, an optical member used in the exposure apparatus, and an exposure method using the exposure apparatus.

  In the manufacturing process of semiconductor elements, liquid crystal display elements, and other micro devices, an exposure apparatus that projects and exposes a pattern, which is an original image formed on a mask, onto a photosensitive substrate coated with a photosensitive agent such as a photoresist (for example, Step-and-repeat type exposure apparatus) is used. Here, in order to perform overlay exposure, it is necessary to perform alignment (alignment) between the mask and the photosensitive substrate, and the exposure apparatus includes an alignment optical that detects the relative position between the mask and the photosensitive substrate. A system is provided. The accuracy of alignment is required to be high with the miniaturization of the pattern, and the relative position detection between the mask and the photosensitive substrate by the alignment optical system must also have high accuracy.

  Here, as the alignment optical system, a mask mark is provided on the mask and a wafer mark is provided on the photosensitive substrate, and the mask mark is formed by the epi-illuminated mask mark and the mark image formed based on the reflected light from the wafer mark. There is an epi-illumination type alignment optical system that detects the relative position between the substrate and the photosensitive substrate (see, for example, Patent Document 1).

JP-A-8-162400

  By the way, the projection optical system of the exposure apparatus is designed and manufactured so as to be a mask (object) side telecentric and a photosensitive substrate (image) side telecentric, that is, both sides telecentric at the maximum image height at the exposure field end. Has been. However, it is difficult to design and manufacture a projection optical system that is telecentric on both sides in the entire exposure field.

  Here, in order to perform optimum alignment by the epi-illumination type alignment optical system, it is necessary to arrange a mask mark at or near the maximum image height position where the telecentricity of the projection optical system is ensured. However, in order to prevent the exposure light from being blocked by the epi-illumination alignment optical system, the mask mark may not be placed at the maximum image height position where the telecentricity of the projection optical system is ensured. Accordingly, when the mask mark cannot be arranged at the maximum image height position, the both-side telecentricity of the projection optical system at the mask mark position is unsatisfactory. Further, even when the mask mark can be arranged at or near the maximum image height position where the telecentricity of the projection optical system is ensured, the two-side telephoto of the projection optical system at the mask mark position is caused by the manufacturing error of the exposure apparatus. Centricity may be unsatisfactory.

  In this way, when the telecentricity on both sides of the projection optical system at the mask mark position becomes unsatisfactory, the relative position relationship between the mask mark and the wafer fiducial mark is accurately detected by the epi-illumination reticle alignment system. Difficult to do. FIG. 8 is a diagram showing an optical path of alignment light emitted from an episcopic reticle alignment system (not shown). As shown in FIG. 8, in the episcopic reticle alignment system, a reflected image based on the reflected light reflected by the reticle mark 102 located on the reticle 100 and a projection optical system 104 are used on a wafer stage (not shown). The relative positional relationship between the reticle mark 102 and the wafer fiducial mark 106 is detected on the basis of a reflected image based on the reflected light reflected by the wafer fiducial mark 106 positioned at the position.

  Here, when the telecentricity of the projection optical system 104 is unsatisfactory at the image height where the reticle mark 102 is located, the alignment light reflected by the reticle mark 102 is indicated by the arrow 108 as shown in FIG. Proceed in the direction. On the other hand, the alignment light reflected by the wafer fiducial mark 106 via the projection optical system 104 travels in the direction of the arrow 110. Accordingly, when the reticle 100 is moved in the direction of the arrow 112 shown in FIG. 9, the reflected image light intensity distribution from the reticle mark 102 changes from A in FIG. 10A to the state in FIG. The reflected image light intensity distribution from the wafer fiducial mark 106 changes from B in FIG. 10A to the state in FIG. 10B (B ′) (moves to the right in the figure). ) That is, the reflected image from the reticle mark 102 is laterally shifted in the opposite direction to the reflected image from the wafer fiducial mark 106.

  In the exposure apparatus, after the reticle is placed on the reticle stage, focus adjustment is performed in order to cope with variations in the thickness of the reticle. The focus focusing accuracy has a certain error because there is a limit to the tracking accuracy and signal processing accuracy of the autofocus lens. Therefore, when focus adjustment is performed with the telecentricity on both sides of the projection optical system being unsatisfactory, the reticle mark imaging position and the wafer fiducial mark imaging position are in opposite directions due to the accuracy error of the focus adjustment. Therefore, it is difficult to accurately detect the relative positional relationship between the reticle mark and the wafer fiducial mark.

  An object of the present invention is to provide an exposure apparatus capable of accurately adjusting the relative position between a mask and a photosensitive substrate even when the both-side telecentricity of the projection optical system is unsatisfactory, and to deflect light and deflect light. And an exposure method using the exposure apparatus.

  The exposure apparatus according to claim 1, wherein an image of a transfer pattern formed on a mask disposed on a first surface is projected onto a photosensitive substrate disposed on a second surface. Alignment light is applied to the projection optical system that forms an image of the transfer pattern on the second surface, the first mark located on the first surface, and the second mark located on the second surface. Supplying an alignment optical system for detecting a relative positional relationship between the first mark and the second mark based on light from the first mark and the second mark; the first surface; A first optical member that is detachably disposed between the projection optical system and deflects alignment light from the alignment optical system, and alignment from the alignment optical system that is caused by insertion / removal of the first optical member. Light path length change Characterized in that it comprises a second optical member for correcting.

  According to the exposure apparatus of the first aspect, since the first optical member for deflecting the alignment light from the alignment optical system is provided, both-side telecentricity of the projection optical system of the exposure apparatus is in an unsatisfactory state. However, the telecentricity at the first mark position can be ensured. In addition, since the second optical member for correcting the optical path length change of the alignment light generated by inserting the first optical member is provided, the imaging position before the first optical member is inserted is provided. Can be corrected. Therefore, even when there is an error in the focusing accuracy of the exposure apparatus, it is possible to eliminate the lateral shift of the imaging positions of the first mark and the second mark, and the relative relationship between the first mark and the second mark. The positional relationship can be detected accurately.

  The exposure apparatus according to claim 2 is characterized in that the first optical member includes a declination prism having a wedge angle. According to the exposure apparatus of the second aspect, since the first optical member includes the declination prism having the wedge angle, the alignment light from the alignment optical system can be deflected, and the projection optics of the exposure apparatus Even if the telecentricity on both sides of the system is unsatisfactory, the telecentricity at the first mark position can be ensured. Therefore, even when there is an error in the focusing accuracy of the exposure apparatus, it is possible to eliminate the lateral shift of the imaging positions of the first mark and the second mark, and the relative relationship between the first mark and the second mark. The positional relationship can be detected accurately.

  According to a third aspect of the present invention, in the exposure apparatus, the declination prism is composed of a declination optical member having at least two wedge angles, and each declination optical member rotates around the optical axis of the alignment optical system. It is configured to be possible.

  According to the third aspect of the present invention, the alignment light from the alignment optical system can be deflected by rotating the declination optical member having at least two wedge angles around the optical axis of the alignment optical system. Therefore, even if the both-side telecentricity of the projection optical system of the exposure apparatus is unsatisfactory, the telecentricity at the first mark position can be ensured. Therefore, even when there is an error in the focusing accuracy of the exposure apparatus, it is possible to eliminate the lateral shift of the imaging positions of the first mark and the second mark, and the relative relationship between the first mark and the second mark. The positional relationship can be detected accurately.

  The exposure apparatus according to claim 4 is characterized in that the second optical member has a positive refractive power. According to the exposure apparatus of the fourth aspect, it is possible to correct the optical path length change of the alignment light caused by inserting the first optical member by the positive refractive power of the second optical member. The imaging position can be corrected to the imaging position before the first optical member is inserted. Accordingly, since the amount of change in focus can be minimized even when a thick optical member is inserted, the relative positional relationship between the first mark and the second mark can be accurately detected.

  The exposure apparatus according to claim 5 is characterized in that the first optical member and the second optical member are integrally formed. According to the exposure apparatus of the fifth aspect, since the first optical member and the second optical member are integrally formed, the configuration of the optical member can be simplified, and the optical member can be inserted and removed. Can be performed more easily.

  The exposure apparatus according to claim 6, wherein the first optical member and the second optical member detect a relative positional relationship between the first mark and the second mark by the alignment optical system. And is retracted after detecting the relative positional relationship between the first mark and the second mark by the alignment optical system.

  According to the exposure apparatus of the sixth aspect, the first optical member and the second optical member are configured to be detachable, and the relative relationship between the first mark and the second mark by the alignment optical system. Inserted only when the positional relationship is detected. Therefore, even when the first mark located on the first surface is arranged in or near the exposure area of the exposure apparatus, the first optical member and the second optical member emit the exposure light passing through the exposure area. Optimal exposure can be performed without blocking.

  According to a seventh aspect of the present invention, there is provided an optical member comprising: an adjustment unit that adjusts a light deflection angle; and a correction unit that corrects a change in the optical path length of the light generated by the adjustment unit. According to the optical member of the seventh aspect, since the adjusting means for adjusting the deflection angle of the light and the correcting means for correcting the change in the optical path length of the light are provided, by using this optical member, it is possible to remove from the optical system. Adjustment of the deflection angle of light and correction of change in the optical path length of light from the optical system can be easily performed.

  The optical member according to claim 8 is characterized in that the adjusting means includes a declination prism having a wedge angle. Since the optical member according to the eighth aspect includes the declination prism having the wedge angle, the deflection angle of the light from the optical system can be easily adjusted by using this optical member.

  The optical member according to claim 9 is constituted by at least two declination optical members having a wedge angle in which the declination prisms are opposed to each other, and each of the declination optical members is opposed to each other. The rotation position can be changed.

  According to the optical member of the ninth aspect, the rotational position of the surface of the declination prism constituted by the two declination optical members can be changed. Therefore, the deflection angle of the light from the optical system can be easily adjusted by rotating using the declination prism.

  The optical member according to claim 10 is characterized in that the correction means has positive refractive power. Since the optical member according to the tenth aspect has positive refracting power, the optical path length change of the light of the optical system can be easily corrected by using this optical member.

  The optical member according to claim 11 is characterized in that the adjusting means and the correcting means are integrally formed. According to the optical member of the eleventh aspect, since the adjusting means and the correcting means are integrally formed, the configuration of the optical member can be simplified, and the optical member can be easily inserted and removed. Can do.

  An exposure method according to claim 12 is an exposure method using the exposure apparatus according to any one of claims 1 to 6, wherein an illumination step of illuminating the mask using an illumination optical system; A transfer step of transferring the mask pattern onto the photosensitive substrate.

  According to this exposure method, the relative positional relationship between the first mark and the second mark is accurately detected, and the relative position between the mask and the photosensitive substrate is accurately adjusted. Since exposure is performed using an apparatus, a fine pattern can be exposed satisfactorily.

  According to the exposure apparatus of the present invention, since the first optical member that deflects the alignment light from the alignment optical system is provided, even if the both-side telecentricity of the projection optical system of the exposure apparatus is unsatisfactory, Telecentricity can be ensured at the first mark position. In addition, since the second optical member for correcting the optical path length change of the alignment light generated by inserting the first optical member is provided, the imaging position before the first optical member is inserted is provided. Can be corrected. Therefore, even when there is an error in the focus focusing accuracy of the exposure apparatus, the relative position relationship between the first mark and the second mark without the lateral shift of the imaging positions of the first mark and the second mark. Can be accurately detected.

  Further, according to the optical member of the present invention, since the adjusting means for adjusting the deflection angle of the light and the correcting means for correcting the optical path length change of the light are provided, the light from the optical system can be obtained by using this optical member. It is possible to easily adjust the deflection angle and correct the change in the optical path length of the light from the optical system.

  According to the exposure method of the present invention, the relative positional relationship between the first mark and the second mark is accurately detected, and the relative position between the mask and the photosensitive substrate is accurately adjusted. Therefore, a fine pattern can be exposed satisfactorily.

  An exposure apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing the schematic arrangement of the entire exposure apparatus according to an embodiment of the present invention. In this embodiment, as shown in FIG. 1, a wafer (photosensitive substrate) on which an image of a transfer pattern formed on a reticle (mask) R is coated with a photosensitive material (resist) via a projection optical system PL. A step-and-scan type exposure apparatus that performs projection exposure on W will be described as an example.

  In the following description, the XYZ orthogonal coordinate system shown in FIG. 1 is set, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the wafer W, and the Z axis is set in a direction orthogonal to the wafer W. In the XYZ coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z-axis is set vertically upward.

  The exposure apparatus according to this embodiment includes an illumination optical system IL that includes a light source and guides a light beam emitted from the light source to the reticle R. The light beam emitted from the light source passes through the illumination optical system IL, illuminates the reticle R arranged on the first surface substantially uniformly, enters the projection optical system PL, and forms a pattern image of the reticle R on the second surface. Projection exposure is performed on the wafer W to be arranged. Reticle R is placed on reticle stage RST, and wafer W is placed on wafer stage WST. Wafer stage WST is position-measured and controlled by laser interferometer 2 using movable mirror 1 positioned on wafer stage WST.

  Further, this exposure apparatus detects a relative positional relationship between a reticle mark (first mark) RM located on reticle R and a wafer fiducial mark (second mark) WFM located on wafer stage WST. An episcopic reticle alignment system (alignment optical system) RAL is provided. The epi-illumination type reticle alignment system RAL is used when initializing the position of the reticle R in the manufacturing stage of the exposure apparatus.

  The exposure apparatus also includes a wafer alignment system WAL that detects a relative positional relationship between a wafer mark (not shown) located on the wafer W and a wafer fiducial mark WFM. Further, the detection position of wafer fiducial mark WFM is measured and controlled by laser interferometer 2 using moving mirror 1 positioned on wafer stage WST.

  In addition, the control device 3 provided in the exposure apparatus receives a detection signal indicating a relative positional relationship between the reticle mark RM and the wafer fiducial mark WFM detected by the incident-light reticle alignment system RAL. In addition, the control device 3 receives a detection signal indicating a relative positional relationship between the wafer mark detected by the wafer alignment system WAL and the wafer fiducial mark WFM. Further, the control device 3 receives a measurement signal of the position of the wafer W by the laser interferometer 2. On the other hand, the control device 3 drives the wafer stage WST based on the detection signal from the episcopic reticle alignment system RAL, the detection signal from the wafer alignment system WAL, and the measurement signal from the laser interferometer 2, and the reticle R, the wafer W, Adjust the relative position of.

  FIG. 2 is a diagram showing a configuration of the epi-illumination type reticle alignment system RAL. A part of the light beam from the light source of the exposure apparatus is incident on the incident end of the fiber 4 that supplies illumination light (alignment light) to the incident-light reticle alignment system RAL. Therefore, the illumination light having the same wavelength as the exposure light is supplied from the fiber 4 to the incident-light reticle alignment system RAL.

  As shown in FIG. 2, the light emitted from the exit end of the fiber 4 enters the condenser lens 5. The alignment light passing through the condenser lens 5 is collected and then incident on the relay lens 6. The alignment light that has become parallel light through the relay lens 6 is reflected by the mirror 8 in the downward direction in FIG. 2 and enters the half mirror 10. The alignment light transmitted through the half mirror 10 enters the first objective lens 12. The alignment light collected by the first objective lens 12 is sequentially reflected by the epi-illumination mirrors 14 and 16 configured to be detachable. Here, the epi-illumination mirrors 14 and 16 can be retracted by moving the epi-illumination mirrors 14 and 16 together in the right direction in FIG. In this embodiment, two epi-illumination mirrors 14 and 16 are used, but the epi-illumination mirror may be composed of one or three or more.

  The light sequentially reflected by the incident mirrors 14 and 16 illuminates the reticle mark (first mark) RM located on the reticle R. The light transmitted through the transmission part of the reticle mark RM is transmitted through a declination prism (first optical member) 20 constituted by declination optical members 18 and 19 having a wedge angle. Here, as shown in FIG. 3, the declination prism 20 is configured to be inserted into and removed from the optical path of the alignment light, and the relative alignment between the reticle mark RM and the wafer fiducial mark WFM by the reticle alignment optical system RAL. When detecting the positional relationship, it is inserted into the optical path of the alignment light by moving it in the left direction of the arrow in FIG. Further, as shown in FIG. 3, the declination prism 20 detects the relative positional relationship between the reticle mark RM and the wafer fiducial mark WFM by the incident-light reticle alignment system RAL (that is, before exposure), and then FIG. 3. Is moved away from the optical path of the alignment light. At this time, the incident mirrors 14 and 16 in FIG. 2 are also retracted from the optical path of the alignment light in the same direction as the retracting direction of the deflection prism 20.

  The alignment light that has passed through the deflection optical members 18 and 19 illuminates the wafer fiducial mark (second mark) WFM located on the wafer stage WST via the projection optical system PL. The reflected light reflected by the wafer fiducial mark WFM passes through the declination prism 20 again through the projection optical system PL.

  Reflected light from the wafer fiducial mark WFM and the reticle mark RM with respect to the alignment light is incident on the half mirror 10 via the epi-illumination mirrors 16 and 14 and the first objective lens 12. The light reflected by the half mirror 10 enters the second objective lens 22 and enters the parallel plane plate 24 disposed in the vicinity of the condensing point where the light is collected by the second objective lens 22. Here, the plane parallel plate 24 is used as an optical member for adjusting the visual field position and the like. The light that has passed through the plane-parallel plate 24 enters the half mirror 30 via the focus adjustment component 26 having a lens action and the third objective lens 28. The light transmitted through the half mirror 30 enters a sensor (imaging device) 34 via the fourth objective lens 32. On the other hand, the light reflected by the half mirror 30 enters the half mirror 36. The light reflected by the half mirror 36 enters the sensor (imaging device) 40 via the fourth objective lens 38. On the other hand, the light transmitted through the half mirror 36 is reflected by the mirror 42 and enters the sensor (imaging device) 46 via the fourth objective lens 44.

  Here, each sensor 34, 40, 46 is set to optical conditions (magnification, numerical aperture, etc.) for optimal alignment, and is stored in a housing 48. Further, in order to remove the heat generated by the operation of each sensor 34, 40, 46, the heat is removed using the exhaust in the housing 48 or a cooling plate. By this heat removal, the temperature rise of the housing 48 or the optical member disposed around the housing 48 can be suppressed, and the deterioration of the alignment accuracy due to the thermal expansion of the optical member or the change of the refractive index can be prevented. it can. Further, since each sensor 34, 40, 46 is arranged at one place in the housing 48, heat removal can be performed efficiently.

  The sensor 34 detects the positions of the reticle mark RM and the wafer fiducial mark WFM formed on the imaging surface of the sensor 34 in the X-axis direction. The sensor 40 detects the positions of the reticle mark RM and wafer fiducial mark WFM formed on the imaging surface of the sensor 40 in the Y-axis direction. The sensor 46 detects images of the reticle mark RM and the wafer fiducial mark WFM formed on the imaging surface of the sensor 46. Each sensor 34, 40, 46 outputs each detection result to the control device 3.

  FIG. 4 is an enlarged view for explaining the configuration and operation of the deflection optical members 18 and 19. As shown in FIG. 4A, the declination optical members 18 and 19 are configured to be rotatable around the optical axis AX of the reticle alignment optical system RAL. That is, as shown in FIG. 4B, the alignment light can be deflected by independently rotating the deflection optical members 18 and 19 around the optical axis AX of the reticle alignment optical system RAL. The declination optical members 18 and 19 are arranged with an interval that prevents the declination optical member 18 and the declination optical member 19 from interfering when the declination optical members 18 and 19 are rotated.

  In addition, as shown in FIG. 4, the declination optical member 18 is configured by a convex lens having an entrance surface 18a having a positive refractive power in order to correct a change in the optical path length of the alignment light. That is, by inserting the declination optical members 18 and 19 into the optical path of the alignment light, the optical path length of the alignment light is changed from the length indicated by the solid line in FIG. 5A to the length indicated by the broken line in FIG. To change. Here, by making the incident surface 18a of the declination optical member 18 a convex lens surface having positive refractive power, the declination optical members 18 and 19 insert the optical path length of the alignment light as shown in FIG. 5B. The optical path length of the alignment light before being corrected can be corrected.

  The declination optical members 18 and 19 are for detecting the relative positional relationship between the reticle mark RM and the wafer fiducial mark WFM using the epi-illumination type reticle alignment system RAL, and the principal ray of the alignment light is the wafer. When it is perpendicular to the wafer fiducial mark WFM on the W side and the principal ray is not perpendicular to the reticle mark RM on the reticle R side but has a predetermined inclination, it is inserted between the reticle R and the projection optical system PL. . The rotation amounts of the declination optical members 18 and 19 are calculated based on a predetermined inclination value between the principal ray and the reticle mark RM so that the projection optical system PL is telecentric at the position of the reticle mark RM on the reticle R side. Is done. The declination optical members 18 and 19 are rotated based on the calculated rotation amounts to deflect the alignment light so that the projection optical system PL becomes telecentric at the position of the reticle mark RM on the reticle R side. Make adjustments. The telecentricity at the position of the reticle mark RM on the reticle R side of the projection optical system PL is secured by the declination optical members 18 and 19. Further, the optical path length change of the alignment light caused by inserting the declination optical members 18 and 19 is corrected by the convex lens action of the incident surface 18 a of the declination optical member 18.

  As shown in FIG. 2, alignment light having the same wavelength as the exposure light emitted from the exit end of the fiber 4 passes through the condenser lens 5 and the relay lens 6 and is reflected by the mirror 8. A reticle mark (first mark) RM that passes through the objective lens 12 and is sequentially reflected by the incident mirrors 14 and 16 and located on the reticle R is illuminated. The light that has passed through the transmission part of the reticle mark RM passes through a declination prism (first optical member) 20 that is arranged to be telecentric at the position of the reticle mark RM. The alignment light that has passed through the declination prism 20 illuminates a wafer fiducial mark (second mark) WFM located on wafer stage WST via projection optical system PL. The reflected light reflected by the wafer fiducial mark WFM passes through the declination prism 20 again through the projection optical system PL.

  Reflected light from the wafer fiducial mark WFM and the reticle mark RM with respect to the alignment light is reflected by the reflecting mirrors 16 and 14, the first objective lens 12, the half mirror 10, the second objective lens 22, the third objective lens 28, and the half mirror 30. Then, the light enters the sensor 34 via the fourth objective lens 32. The light reflected by the half mirror 30 is reflected by the half mirror 36 and enters the sensor 40 via the fourth objective lens 38. The light transmitted through the half mirror 36 enters the sensor 46 through the mirror 42 and the fourth objective lens 44.

  Each sensor 34, 40, 46 outputs each detection result to the control device 3. The control device 3 is based on the detection signal output from the episcopic reticle alignment system RAL (each sensor 34, 40, 46), the detection signal output from the wafer alignment system WAL, and the detection signal output from the laser interferometer 2. Thus, the relative positions of the reticle R and the wafer W are adjusted. After the adjustment of the relative positions of the reticle R and the wafer W is completed, the deflection optical members 18 and 19 are retracted.

  In the above-described embodiment, the declination optical members 18 and 19 are relatively rotated based on the rotation amounts of the declination optical members 18 and 19 calculated in advance. Telecentricity adjustment at the position of the reticle mark RM on the reticle R side of the projection optical system PL can be performed while rotating the members 18 and 19. That is, in this case, the principal ray of the alignment light is perpendicular to the wafer fiducial mark WFM on the wafer W side, and the principal ray is not perpendicular to the reticle mark RM on the reticle R side but has a predetermined inclination. The two declination optical members 18 and 19 are inserted between the reticle R and the projection optical system PL, and the two declination optical members 18 and 19 are gradually rotated so that the projection optical system PL is on the reticle R side. A rotational position that is telecentric at the position of the reticle mark RM is obtained, and adjustment is performed so that the projection optical system PL is telecentric at the position of the reticle mark RM on the reticle R side.

  According to the exposure apparatus of this embodiment, since the declination optical member capable of deflecting the alignment light is provided, the reticle mark on the reticle side is provided even when the both-side telecentricity of the projection optical system is unsatisfactory. Telecentricity at the position of can be secured. In addition, since the incident surface of the declination optical member is formed of a convex lens surface, it is possible to correct a change in the optical path length of the alignment light caused by inserting the declination optical member. Therefore, even when there is an error in the focus focusing accuracy of the exposure apparatus, it is possible to eliminate the lateral shift of the imaging position of the reticle mark and the wafer fiducial mark, and the relative position between the reticle mark and the wafer fiducial mark. Adjustment can be made accurately.

  Further, according to the exposure apparatus of this embodiment, the declination prism provided between the reticle and the projection optical system is configured to be detachable, so that only when alignment is performed by the episcopic reticle alignment system. A declination prism can be inserted. Therefore, even when the reticle mark is arranged in or near the exposure area of the exposure apparatus, optimum exposure can be performed without blocking the exposure light passing through the exposure area by the declination prism.

  In the exposure apparatus according to this embodiment, the deflection light of the alignment light from the incident-light reticle alignment system RAL and the correction of the optical path length change are performed using the two declination optical members 18 and 19. It may be configured to include a single deflection optical member. In this case, the size and rotation amount of the wedge angle of the declination optical member are calculated based on a predetermined inclination value between the principal ray and the reticle mark so that the projection optical system is telecentric at the reticle mark position. Is done. The declination optical member is formed based on the calculated wedge angle, the rotation position is determined based on the calculated rotation amount, and is inserted between the reticle and the projection optical system. Further, the exposure apparatus according to this embodiment may be configured to include three or more declination optical members.

  When telecentricity adjustment at the reticle mark position is performed by the declination optical member, a rotation drive system may be provided in the exposure apparatus, and the declination optical member may be rotated by the rotation drive system. The declination optical member may be rotated by temporarily retracting the member, manually adjusting the member, and reinserting the member.

  In the exposure apparatus according to this embodiment, the incident surface 18a of the declination optical member 18 is configured to have a convex lens surface (positive refractive power). In other words, an example is shown in which an optical member that deflects alignment light from an episcopic reticle alignment system and an optical member that corrects a change in the optical path length of the alignment light are integrally formed. It may be formed. That is, a declination optical member that deflects alignment light and an optical member having a separate convex lens surface (positive refractive power) may be provided.

  In the exposure apparatus according to the above-described embodiment, the reticle (mask) is illuminated by the illumination optical system (illumination process), and the transfer pattern formed on the mask is exposed to the photosensitive substrate using the projection optical system ( By the exposure step, a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. FIG. 6 is a flowchart of an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a plate or the like as a photosensitive substrate using the exposure apparatus according to the above-described embodiment. Will be described with reference to FIG.

  First, in step 301 of FIG. 6, a metal film is deposited on one lot of plates. In the next step 302, a photoresist is applied on the metal film on the one lot of plates. Thereafter, in step 303, using the exposure apparatus according to the above-described embodiment, the pattern image on the mask is sequentially exposed and transferred to each shot area on the plate of the one lot via the projection optical system. . Thereafter, in step 304, the photoresist on the one lot of plates is developed, and in step 305, the resist pattern is etched on the one lot of plates to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each plate.

  Thereafter, a device pattern such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, the relative positional relationship between the reticle mark and the wafer fiducial mark is accurately detected by the incident-light reticle alignment system, and the relative position between the mask and the photosensitive substrate is accurately adjusted. Since exposure is performed using the exposure apparatus, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput. In steps 301 to 305, a metal is vapor-deposited on the plate, a resist is applied on the metal film, and exposure, development, and etching processes are performed. Prior to these processes, the process is performed on the plate. It is needless to say that after forming a silicon oxide film, a resist may be applied on the silicon oxide film, and steps such as exposure, development, and etching may be performed.

  In the exposure apparatus according to the above-described embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 7, in a pattern forming process 401, a so-called photolithography process is performed in which a mask pattern is transferred and exposed to a photosensitive substrate (such as a glass substrate coated with a resist) using the exposure apparatus of the present embodiment. By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes steps such as a developing step, an etching step, and a resist stripping step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step 402.

  Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three of R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembling step 403 is executed. In the cell assembling step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern forming step 401, the color filter obtained in the color filter forming step 402, and the like. In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402, and a liquid crystal panel (liquid crystal cell) is obtained. ).

  Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, the relative position relationship between the reticle mark and the wafer fiducial mark is accurately detected by the incident-light reticle alignment system, and the relative position between the mask and the photosensitive substrate is accurately adjusted. Since the exposure is performed using the exposure apparatus performed in the above, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

It is a figure which shows schematic structure of the exposure apparatus concerning embodiment of this invention. It is a figure which shows the structure of the epi-illumination type reticle alignment system concerning embodiment of this invention. It is a figure for demonstrating the insertion / removal method of the declination prism which comprises the exposure apparatus concerning embodiment of this invention. It is a figure for demonstrating the rotation method of the declination optical member which comprises the exposure apparatus concerning embodiment of this invention. It is a figure for demonstrating the convex lens effect | action of the declination optical member which comprises the exposure apparatus concerning embodiment of this invention. It is a flowchart of the method of manufacturing the semiconductor device as a micro device concerning an embodiment. It is a flowchart of the method of manufacturing the liquid crystal display element as a microdevice concerning embodiment. It is a figure which shows the optical path of alignment light when the alignment light from an epi-illumination type reticle alignment system is not parallel to exposure light. It is a figure for demonstrating the optical path of the alignment light by an epi-illumination type reticle alignment system. It is a figure which shows the image light intensity | strength of a reticle mark and a wafer fiducial mark detected by an epi-illumination type reticle alignment system.

Explanation of symbols

IL: Illumination optical system, PL: Projection optical system, R: Reticle, RST: Reticle stage, RM: Reticle mark, RAL ... Episcopic reticle alignment system, W: Wafer, WST: Wafer stage, WFM ... Wafer fiducial mark , WAL ... wafer alignment system, 1 ... moving mirror, 2 ... laser interferometer, 3 ... control device, 4 ... fiber, 5 ... condenser lens, 6 ... relay lens, 8,42 ... mirror, 10, 30, 36 ... half Mirror 12, first objective lens 14, 16, epi-illumination mirror 18, 19, declination optical member, 20, declination prism, 22, second objective lens, 24, parallel plane plate, 26, focus adjustment lens 28 ... third objective lens, 34, 40, 46 ... sensor, 48 ... casing.

Claims (12)

In an exposure apparatus for projecting an image of a transfer pattern formed on a mask disposed on a first surface onto a photosensitive substrate disposed on a second surface,
A projection optical system for forming an image of the transfer pattern on the mask on the second surface;
Alignment light is supplied to the first mark located on the first surface and the second mark located on the second surface, and light from the first mark and the second mark is supplied to the first mark and the second mark located on the second surface. An alignment optical system that detects a relative positional relationship between the first mark and the second mark,
A first optical member that is detachably disposed between the first surface and the projection optical system, and that deflects alignment light from the alignment optical system;
A second optical member that corrects an optical path length change of alignment light from the alignment optical system caused by insertion / removal of the first optical member;
An exposure apparatus comprising:   The exposure apparatus according to claim 1, wherein the first optical member includes a declination prism having a wedge angle.   The declination prism is composed of declination optical members having at least two wedge angles, and each declination optical member is configured to be rotatable around the optical axis of the alignment optical system. The exposure apparatus according to claim 1 or 2.   The exposure apparatus according to claim 1, wherein the second optical member has a positive refractive power.   The exposure apparatus according to any one of claims 1 to 4, wherein the first optical member and the second optical member are integrally formed.   The first optical member and the second optical member are inserted when detecting a relative positional relationship between the first mark and the second mark by the alignment optical system, and the alignment optical system The exposure apparatus according to claim 1, wherein the exposure apparatus is retracted after detecting a relative positional relationship between the first mark and the second mark. Adjusting means for adjusting the deflection angle of the light;
Correction means for correcting a change in the optical path length of the light generated by the adjustment means;
An optical member comprising:   The optical member according to claim 7, wherein the adjusting unit includes a declination prism having a wedge angle.   The declination prism is composed of at least two declination optical members having wedge angles that are arranged to face each other, and each declination optical member is configured to be able to change the rotational position of the opposed surface. The optical member according to claim 8.   The optical member according to claim 7, wherein the correction unit has a positive refractive power.   The optical member according to claim 7, wherein the adjustment unit and the correction unit are integrally formed. In the exposure method using the exposure apparatus according to any one of claims 1 to 6,
An illumination process for illuminating the mask using an illumination optical system;
A transfer step of transferring the pattern of the mask onto the photosensitive substrate;
An exposure method comprising:

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