JP4581662B2 - Projection optical system, exposure apparatus, and device manufacturing method - Google Patents

Description

The present invention relates to a projection optical system having an aperture device that is mounted on an exposure apparatus and can adjust the size of an aperture. Furthermore, the present invention relates to an exposure apparatus that exposes an image of a pattern formed on a mask onto a substrate. In addition, the present invention relates to a device manufacturing method including a lithography process.

  Conventionally, in a lithography process for manufacturing a device such as a semiconductor element or a liquid crystal display element, a pattern formed on a mask such as a photomask or a reticle is applied with a photosensitive material such as a resist via a projection optical system. An exposure apparatus for transferring onto a substrate such as a wafer or glass plate is used. As this type of exposure apparatus, a static exposure type exposure apparatus such as a so-called stepper and a scanning exposure type exposure apparatus such as a so-called scanning stepper are mainly used.

  In recent years, in devices, particularly semiconductor elements, circuit patterns have been remarkably miniaturized, and the demand for higher resolution for exposure apparatuses has been greatly increased. In order to meet such demands, the exposure apparatus is being developed in a direction that uses exposure light having a shorter wavelength and increases the numerical aperture of the projection optical system. The numerical aperture of the projection optical system can be changed to an arbitrary size by a variable aperture device arranged in the vicinity of the pupil plane in the projection optical system.

  In addition, it is difficult to manufacture the projection optical system as designed completely, and various aberrations remain in the actually manufactured projection optical system due to various factors. For this reason, the optical characteristics of the actually produced projection optical system are different from the designed optical characteristics, and the pupil plane of the projection optical system may be curved. In a projection optical system having such a curved pupil surface, when the variable aperture device is fixed at a specific position in the optical axis direction, even if it matches the ideal aperture position at a certain numerical aperture, May deviate from the ideal aperture position.

In order to cope with such a problem, an optical system that can adjust the position of the variable aperture device in the optical axis direction has been developed.
In this variable aperture device that can adjust the position in the optical axis direction, an annular ring gear that is rotated by a motor mounted on the mount is disposed inside the mount. And the inner ring and grooved ring which hold | maintain the iris diaphragm for changing the magnitude | size of an opening part are hold | maintained inside the ring gear.

  The ring gear is formed with a step portion protruding toward the optical axis so as to cover the lower surface of the inner ring, and the inner ring is connected via a driving lug disposed at the tip of the step portion. The rotation of the ring gear is transmitted to the inner ring via the drive lug, and the size of the opening of the iris diaphragm is adjusted.

The ring gear is provided with a guide lug that engages with a guide groove formed on the outer peripheral surface of the grooved ring. When the ring gear is rotated, the guide lug is displaced in the guide groove, and the positions of the grooved ring and the inner ring in the optical axis direction are adjusted. (See Patent Document 1)
JP 2001-154235 A (page 5-6, FIG. 2)

  However, in the conventional configuration, since the stepped portion for holding the drive lug in the ring gear protrudes greatly in the optical axis direction so as to cover the lower surface of the inner ring, an increase in size of the aperture device is inevitable. .

  In the ring gear, a drive lug for rotating the inner ring is provided along the optical axis direction, whereas a guide lug for displacing the inner ring and the grooved ring in the optical axis direction is light. It is provided along the direction intersecting the axis. In other words, it is necessary to project two shafts that are directed in directions orthogonal to each other from one ring gear, and in order to avoid interference between the shafts and the surrounding configuration, the enlargement of the diaphragm device and the complexity of the configuration are avoided. I can't.

  In addition, in order to realize a higher resolution of the projection optical system, when trying to provide a plurality of variable aperture devices in the vicinity of the pupil plane of the projection optical system, if the conventional configuration is to be adopted, There has been a problem that further increase in complexity and size of the configuration is unavoidable, leading to an increase in size of the projection optical system and further of the exposure apparatus.

The present invention has been made paying attention to such problems existing in the prior art. As the purpose is to provide a projection optical system resolution is enhanced while suppressing the large-reduction. Another object is to provide an exposure apparatus capable of improving exposure accuracy. In addition, another object is to provide a device manufacturing method capable of manufacturing a highly integrated device with a high yield.

To achieve the above object, a first aspect of the present invention, a projection optical system for projecting an image of a predetermined pattern formed on the mask onto a substrate, a plurality of adjustable size of apertures aperture blade A first plate member that holds each of the roots so as to be movable, and a second plate that supports the first plate member so as to be relatively movable , and is capable of moving the first plate member in the optical axis direction of the projection optical system. A first engaging member engaged with a side surface of the first plate member, and an engaging member engaged with a side surface of the second plate member; and connected to the engaging member; And a driving mechanism for driving the second plate member while driving the one plate member.

According to the first aspect of the present invention, the imaging characteristics of the projection optical system can be adjusted with high accuracy, and the exposure accuracy can be improved. In addition, an engagement member that engages with the side surface of the first plate and the side surface of the second plate is provided, and the first plate and the second plate are driven by the drive mechanism via the engagement member. ing. The plurality of aperture blades are moved by driving the first plate member, and the size of the opening can be adjusted. Further, the first plate member can be moved in the optical axis direction of the projection optical system by driving the second plate member.

As described above, the mechanism for adjusting the size of the opening and the mechanism for adjusting the position of the projection optical system in the optical axis direction can be provided without providing a member that largely protrudes toward the optical axis. The engagement member that engages with the side surface of the second plate and the side surface of the second plate can be provided. For this reason, the simplification of the configuration can be achieved and an increase in size can be suppressed.

According to a second aspect of the present invention, in the first aspect of the invention, the first plate member moves the plurality of diaphragm blades as the second plate member moves in the optical axis direction. Thus, the size of the opening is adjusted.

In the invention according to the second aspect, in addition to the action of the invention according to the first aspect, in the case where the pupil plane of the projection optical system is curved, the diaphragm is arranged along the curved pupil plane. It can arrange | position in a more preferable position, setting to a desired numerical aperture.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the first plate member is centered on the optical axis as the second plate member moves in the optical axis direction. And rotating with respect to the second plate member .

  In the third aspect of the invention, in addition to the function of the first or second aspect of the invention, the size of the opening formed in the plurality of diaphragm blades is linked to the position of the diaphragm blades in the optical axis direction. Can be adjusted.

  According to a fourth aspect of the present invention, there is provided a frame member to which a driving source of the driving mechanism is attached in the first aspect of the present invention. And is arranged inside the frame member and rotates with respect to the frame member around the optical axis.

In the invention according to the fourth aspect, in addition to the action of the invention according to any one of the first to third aspects, the engaging member is rotated about the optical axis of the projection optical system, so that a plurality of the engaging members are rotated. The aperture size can be adjusted by the aperture blades and the positions of the plurality of aperture blades in the optical axis direction can be adjusted, and the configuration can be simplified. Further, the frame member and the engaging member can be efficiently arranged concentrically with the optical axis of the projection optical system as the center, and the enlargement of the diaphragm device can be suppressed.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the engaging member includes at least a part of a first cam mechanism for adjusting a size of the opening, and the second. And at least a part of a second cam mechanism for moving the plate member in the optical axis direction.

  According to the fifth aspect of the invention, in addition to the operation of the fourth aspect of the invention, the opening size and the position of the second plate member in the optical axis direction are adjusted with a simple configuration. Therefore, the configuration of the diaphragm device can be simplified and the enlargement can be suppressed.

  According to a sixth aspect of the invention, in the fifth aspect of the invention, the first cam mechanism has a first cam groove, and the second cam mechanism has a second cam groove. It is characterized by this.

  According to the sixth aspect of the invention, the first and second cam grooves are provided in the engaging member, whereby the action of the fifth aspect of the invention can be realized, and the structure of the further throttling device is simplified. And suppression of size increase.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein a plurality of the first plate members are arranged at a predetermined interval in the optical axis direction. The engaging members are respectively engaged with side surfaces of the plurality of first plate members.

In the invention as set forth in claim 7, by providing a plurality of the variable throttle in the projection optical system, the imaging characteristics of the projection optical system, can be adjusted more finely than in the case of providing the single variable throttle For example, an abnormal line width on the image plane of the projection optical system can be corrected more suitably. Thereby, the resolving power of the projection optical system can be further improved.

  The invention described in claim 8 is characterized in that, in the invention described in claim 7, the plurality of first plate members adjust the sizes of the openings to different sizes. .

In the invention as set forth in claim 8, in addition to the functions of the invention as set forth in claim 7, the imaging characteristics of the projection optical system can be adjusted more finely, is possible to further improve the resolution of the projection optical system it can.

Further, an invention according to claim 9, in an exposure apparatus including a projection optical system for projecting an image of a predetermined pattern formed on the mask onto a substrate, as the projection optical system, one of claims 1-8 one The projection optical system described in the item is used.

According to the ninth aspect of the present invention, the imaging characteristics of the projection optical system can be adjusted with high accuracy, and the exposure accuracy can be improved.
According to a tenth aspect of the present invention, in the ninth aspect of the invention, the plurality of diaphragm blades move along a pupil plane of the projection optical system.

  In the invention according to claim 10, in addition to the action of the invention according to claim 9, the state of the plurality of diaphragm blades can be adjusted along the pupil plane, and the imaging characteristics of the optical system can be accurately adjusted. It can be corrected.

The invention according to claim 11 is the invention according to claim 10, wherein the pupil plane is a curved pupil plane, and the plurality of diaphragm blades are arranged along the curved pupil plane with the opening. while adjusting the size, it is characterized in that to move in the optical axis direction of the projection optical system.

In the invention according to claim 11, the action of the invention according to claim 10 can be exerted even when the pupil surface is curved .

Also, the invention of claim 12 is a method of manufacturing a device comprising a lithography step, the lithographic process, which comprises using the exposure apparatus according to any one of claims 9 to 11 It is.

In the invention according to claim 12 , a highly integrated device can be manufactured with a high yield.
Next, the technical ideas further included in the invention described in the above claims will be described below together with their actions.

(1) The projection optical system according to claim 7 or 8, wherein the plurality of first plate members are provided so as to engage with a single engaging member.
Therefore, according to the invention described in (1), in addition to the operation of the invention according to claim 7 or 8, which achieves the effect that it is possible to miniaturize further.

(2) The projection optical system according to claim 7 or 8, further comprising a position adjusting mechanism that adjusts a relative position of the plurality of first plate members in the optical axis direction.
Therefore, according to the invention described in (2), in addition to the operation of the invention described in claim 7 or 8, the relative positions of the plurality of variable stops are finely adjusted according to the residual aberration of the projection optical system. As a result, the image forming characteristic of the projection optical system can be corrected with higher accuracy.

(3) When the curved pupil plane interferes with an optical element constituting a part of the projection optical system, the plurality of diaphragm blades are portions where the curved pupil plane and the optical element interfere with each other. The exposure apparatus according to claim 10, further comprising an interference avoidance mechanism that avoids interference between the optical element and the optical element.

Therefore, according to the invention described in (3), in the portion where the curved pupil plane and the optical element interfere with each other, only the size of the aperture is adjusted while avoiding interference between the plurality of diaphragm blades and the optical element. can do. In a portion where the curved pupil plane and the optical element do not interfere with each other, the position of the plurality of aperture blades in the optical axis direction of the projection optical system can be adjusted along the pupil plane while adjusting the size of the aperture. The effect | action is played.

As described above in detail, according to the present invention, it is possible to provide a projection optical system resolution is enhanced while suppressing the large-reduction. Furthermore, according to the present invention, an exposure apparatus capable of improving exposure accuracy can be provided. In addition, according to the present invention, it is possible to provide a device manufacturing method capable of manufacturing a highly integrated device with a high yield.

(First embodiment)
Below, the exposure apparatus, optical system, and diaphragm apparatus of the present invention are embodied in an exposure apparatus used in a lithography process when manufacturing a semiconductor element, its projection optical system, and a diaphragm apparatus provided in the projection optical system. 1st Embodiment is described based on FIGS.

  FIG. 1 is a schematic block diagram showing an exposure apparatus 21 of the present invention. As shown in FIG. 1, this exposure apparatus 21 synchronizes a reticle R as a mask and a wafer W as a substrate in a one-dimensional direction (here, the Y-axis direction which is the horizontal direction in FIG. 1). While moving, the circuit pattern formed on the reticle R is transferred to each shot area on the wafer W via the projection optical system PL. That is, the exposure apparatus 21 is a step-and-scan type scanning exposure apparatus, that is, a so-called scanning stepper.

  The exposure apparatus 21 includes a light source 22, an illumination optical system 23, a reticle stage RST, a projection optical system PL as an optical system, and a wafer stage WST. The illumination optical system 23 illuminates the reticle R with the exposure light EL from the light source 22. Reticle stage RST holds reticle R. Projection optical system PL projects exposure light EL emitted from reticle R onto wafer W. Wafer stage WST holds wafer W.

  As the light source 22, an ArF excimer laser light source that outputs exposure light composed of pulsed ultraviolet light is used. The light source 22 is connected to the illumination optical system 23 via a beam matching unit (not shown).

  The illumination optical system 23 includes an ND filter (not shown), a beam shaping optical system, a vibrating mirror, a fly-eye lens as an optical integrator, a relay lens system, a diaphragm mechanism, a reticle blind, and a condenser lens. The exposure light EL emitted from the light source 22 is converted into parallel light that illuminates the pattern surface of the reticle R with uniform illuminance by passing through the illumination optical system 23.

  Here, as the projection optical system PL, a refracting optical system having a 1/4, 1/5, or 1/6 reduction magnification composed of only a refractive optical element (lens element) made of quartz or meteorite as an optical glass material is used. ing. The projection optical system PL is a catadioptric optical system (catadioptric optical system) that combines a refractive optical element (lens element) and a reflective optical element (mirror), or a reflective optical system that includes only a reflective optical element. May be. The lens barrel 24 of the projection optical system PL has an airtight structure. Then, a low-absorbing gas (for example, clean dry nitrogen gas or helium gas having a concentration of air (oxygen) of less than 1 ppm) or the like is supplied into the lens barrel 24, and the oxygen concentration and moisture content in the lens barrel. Is kept below a predetermined value.

  The projection optical system PL includes a first optical system LS1 composed of a plurality of lens elements, a second optical system LS2 composed of a plurality of lens elements, and a first optical system LS1 and a second optical system LS2. And an aperture stop 25 as an aperture device disposed between them. The aperture stop 25 has a variable numerical aperture, and is provided so as to be movable along the pupil plane IS of the projection optical system PL.

Next, the configuration of the aperture stop 25 will be described with reference to FIGS.
FIG. 2 is a perspective view showing the aperture stop 25 in a state where the numerical aperture is maximum, and FIG. 3 is a perspective view showing the aperture stop 25 in a state where the numerical aperture is minimum. As shown in FIG. 2, the aperture stop 25 includes a fixed frame 31 as a frame member, a movable frame 32 as an engagement member, an arrow wheel 33 as a first plate member, and a base plate as a second plate member. 34.

  The fixed frame 31 has a cylindrical shape and constitutes a part of the lens barrel 24 of the projection optical system PL. A motor 37 as a drive source of the drive mechanism is provided on the outer surface of the lens barrel 24 via a motor fixing block 38. Attached.

  FIG. 4 is a partial cross-sectional view showing the main part of the aperture stop 25. As shown in FIG. 4, a gear 40 that meshes with the drive shaft 39 of the motor 37 is rotatably fixed to the motor fixing block 38. A part of the gear 40 is exposed to the inside of the fixed frame 31 through a rectangular opening 41. Here, an O-ring 42 is sandwiched between the outer surface of the fixed frame 31 and the motor fixing block 38 so as to surround the opening 41, and the flow of gas inside and outside the fixed frame 31 is restricted. The airtightness in the lens barrel 24 is maintained.

  As shown in FIG. 2, the movable frame body 32 is formed in a cylindrical frame shape and is accommodated in the fixed frame body 31. As shown in FIG. 4, the movable frame 32 is held on a convex portion 43 that is formed to protrude from the inner wall surface of the bottom of the fixed frame 31 via a bearing (not shown).

  A spur gear 46 that meshes with the gear 40 exposed inside the fixed frame 31 is fixed to the movable frame 32. Thus, when the motor 37 is driven, the driving force from the drive shaft 39 is transmitted to the spur gear 46 via the gear 40, and the movable frame 32 is fixed to the fixed frame with the optical axis of the projection optical system PL as the center. It rotates with respect to 31. Further, the position of the movable frame 32 is always detected by a position sensor 47 attached to the fixed frame 31.

  As shown in FIG. 2, the movable frame 32 has a rotation angle control groove 48 as a first cam groove constituting a part of one first cam mechanism, and one of the three second cam mechanisms. An oblique groove 49 as a second cam groove constituting the portion and three long holes 50 are formed. In the figure, for the sake of drawing, only a part of the skew groove 49 and the long hole 50 are shown.

  The rotation angle control groove 48 is formed to extend in a direction parallel to the optical axis of the projection optical system PL. The oblique groove 49 is formed in an oblique shape having a downward gradient in the rotation direction of the movable frame 32 from the maximum numerical aperture side to the minimum numerical aperture side. The long hole 50 is formed in an oblique shape having an upward slope in the rotation direction of the movable frame 32 and in a wide opening, like the oblique groove 49. Here, the oblique grooves 49 and the long holes 50 are formed so that the center angles about the optical axis are 120 ° apart from each other at a predetermined interval.

  The base plate 34 shown in FIG. 4 has an annular shape and is accommodated in the movable frame 32. A support groove 55 for supporting the side end portion 54 of the arrow wheel 33 via a bearing (not shown) is formed at the upper end of the side wall portion 53 formed on the outer peripheral edge of the base plate 34.

  On the side surface of the side wall portion 53, skew bearings 56 that constitute a part of three second cam mechanisms that engage with the skew groove 49 of the movable frame body 32 are provided. As shown in FIG. 2, three sliders 57 are attached at positions corresponding to the long holes 50 of the movable frame 32 on the side surface of the side wall portion 53. The slider 57 is fixed on the inner peripheral surface of the fixed frame 31 through the long hole 50 so as to extend in a direction parallel to the optical axis at a position where the central angles about the optical axis are spaced by 120 °. The rotation restricting rail 58 is engaged.

  Thereby, when the movable frame 32 is rotated by the driving force from the motor 37, the rotation of the base plate 34 around the optical axis of the projection optical system PL is restricted by the engagement of the slider 57 and the rotation restricting rail 58. Therefore, the skew bearing 56 moves in the skew groove 49 in the optical axis direction of the projection optical system PL. As described above, the base plate 34 is restricted from rotating around the optical axis of the projection optical system PL, and is allowed to move only in the optical axis direction.

The arrow wheel 33 shown in FIG. 4 has an annular shape, and is accommodated in the movable frame 32 in a state of being overlapped with the base plate 34 so as to be relatively movable with a predetermined gap.
FIG. 5 is a plan view of the arrow wheel 33 and shows the movement of one of the plurality of aperture blades 61. As shown in FIGS. 3 and 5, a plurality of aperture blades 61 are attached to the lower surface of the arrow wheel 33 so as to be movable radially in a plane perpendicular to the optical axis as viewed from the optical axis.

  The aperture blade 61 has, for example, an arcuate contour on the inner side, and the curvature of the inner arc is the same as the aperture diameter corresponding to the maximum numerical aperture required for the projection optical system PL. When the aperture diameter is small, it is close to a polygon having the same number of corners as the number of aperture blades 61, but can be approximated as an aperture aperture 25 having a desired small aperture diameter. If it is increased to 3 or more, preferably 5 or more, and more desirably 8 or more, there is no problem.

  The diaphragm blade 61 is fixed to the arrow wheel 33 so as to be rotatable by a rotary shaft 62 at one end portion of the outer arc. A guide pin 63 protrudes from the diaphragm blade 61 at a position spaced apart from the rotary shaft 62 by a predetermined distance on the outer arc. The guide pin 63 is engaged with one of the oblique guide grooves 64 provided in the arrow wheel 33 as many as the number of the aperture blades 61. Here, the guide groove 64 is formed in an oblique shape having a downward gradient in the rotation direction of the arrow wheel 33 from the maximum numerical aperture side toward the minimum numerical aperture side.

  As shown in FIG. 2, a rotation transmission bearing 65 that engages with a rotation angle control groove 48 of the movable frame body 32 and forms a part of the first cam mechanism at a side end portion 54 that forms the side surface of the arrow wheel 33. Is provided.

  Accordingly, when the movable frame body 32 is rotated by the driving force from the motor 37, the arrow wheel 33 is rotated in synchronization with the movable frame body 32 due to the engagement between the rotation transmission bearing 65 and the rotation angle control groove 48. . When the arrow wheel 33 is rotated in the direction of the arrow R1 in FIG. 5, for example, the guide pin 63 of the diaphragm blade 61 is relatively moved in the direction of the arrow R2 with respect to the arrow wheel 33 in the guide groove 64, so that the diaphragm blade 61 is rotated. It is rotated to the minimum opening diameter side around 62.

  With the rotation of the movable frame 32, the base plate 34 moves in the optical axis direction of the projection optical system PL, so that the arrow wheel 33 also moves in the optical axis direction. At this time, the rotation transmission bearing 65 moves in the rotation angle control groove 48 in the optical axis direction of the projection optical system PL.

  Here, as shown in FIG. 1, when the pupil plane IS of the projection optical system PL is curved, the rotational angle control groove 48 and the skew groove 49 of the movable frame 32 have a plurality of shapes. The periphery of the opening formed by the diaphragm blades 61 is formed so as to move along the curved pupil plane IS. Specifically, for example, at least one of the rotation angle control groove 48 and the skew groove 49 is not linear, but is formed to have a loose arc shape according to the curved state of the pupil plane IS.

Therefore, according to the present embodiment, the following effects can be obtained.
(A) The aperture stop 25 includes an arrow wheel 33 that can move each of the plurality of diaphragm blades 61, and a base plate 34 that supports the arrow wheel 33 and that can move the arrow wheel 33 in the optical axis direction of the projection optical system PL. It has. The aperture stop 25 engages with a rotation transmission bearing 65 provided at the side end portion 54 of the arrow wheel 33 and also engages with a skew bearing 56 provided at the side wall portion 53 of the base plate 34. 32. The arrow wheel 33 and the base plate 34 are driven via the movable frame 32 by a motor 37 connected to the movable frame 32.

  For this reason, a mechanism for adjusting the size of the aperture in the aperture stop 25 and a mechanism for adjusting the position of the projection optical system PL in the optical axis direction are provided with a member that protrudes greatly toward the optical axis. Instead, it can be provided on the movable frame 32 that engages the side surfaces of the arrow wheel 33 and the base plate 34. For this reason, it is possible to simplify the configuration of the aperture stop 25 and to suppress an increase in size.

(A) In the aperture stop 25, the plurality of aperture blades 61 of the arrow wheel 33 adjust the size of the opening as the base plate 34 moves in the optical axis direction.
For this reason, even when the pupil plane IS of the projection optical system PL is curved, the aperture stop 25 is set at a more preferable position along the curved pupil plane IS while setting a desired numerical aperture. Can do.

(C) In the aperture stop 25, the arrow wheel 33 rotates about the optical axis as the base plate 34 moves in the optical axis direction.
For this reason, the size of the opening formed by the plurality of diaphragm blades 61 can be adjusted in conjunction with the position of the diaphragm blades 61 in the optical axis direction.

  (D) The aperture stop 25 has a fixed frame 31 to which the motor 37 is attached. In addition, a movable frame 32 for driving the arrow wheel 33 and the base plate 34 is formed in a frame shape similar to the fixed frame 31, is disposed inside the fixed frame 31, and is centered on the optical axis of the projection optical system PL. As shown in FIG.

  For this reason, by rotating the movable frame 32 around the optical axis of the projection optical system PL, the size of the openings by the plurality of aperture blades 61 and the position of the plurality of aperture blades 61 in the optical axis direction are adjusted. Adjustment can be performed, and the configuration can be simplified. In addition, the fixed frame body 31 and the movable frame body 32 can be efficiently arranged concentrically around the optical axis of the projection optical system PL, and an increase in the size of the aperture stop 25 can be suppressed.

  (E) In the aperture stop 25, the movable frame 32 is provided with a rotation angle control groove 48 for adjusting the size of the opening and a skew groove 49 for moving the base plate 34 in the optical axis direction. ing.

  For this reason, it is possible to adjust the size of the opening and the position of the base plate 34 in the optical axis direction with cam grooves having simple configurations such as the rotation angle control groove 48 and the skew groove 49. Simplification of the configuration and suppression of enlargement can be realized.

(F) In the projection optical system PL, the aperture stop 25 having the effects described in (A) to (E) is used as a stop device that makes the size of the aperture variable.
For this reason, it is possible to improve the resolving power of the projection optical system PL while suppressing an increase in the size of the projection optical system PL.

(G) In the projection optical system PL, the plurality of aperture blades 61 of the aperture stop 25 are moved along the pupil plane IS of the projection optical system PL.
For this reason, when setting the aperture stop 25 to a desired numerical aperture, while adjusting the apertures of the plurality of aperture blades 61 to a predetermined size, the plurality of aperture blades 61 are arranged along the pupil plane IS with a suitable optical axis. It can be adjusted to the position of the direction. Therefore, the imaging characteristics of the projection optical system PL can be adjusted with high accuracy. By mounting this projection optical system PL on the exposure apparatus 21, the exposure accuracy of the exposure apparatus 21 can be improved.

(Second Embodiment)
Next, a second embodiment of the diaphragm device according to the present invention will be described with reference to FIGS. 6 and 7 with a focus on the differences from the first embodiment.

  FIG. 6 is a partial development view showing a part of the outer peripheral surface of the movable frame 32 in the aperture stop 25 of the second embodiment. In the aperture stop 25 of the second embodiment, as shown in FIG. 6, an oblique groove 71 as a second cam groove that constitutes a part of the second cam mechanism formed in the movable frame body 32. The shape is different from the skew groove 49 of the first embodiment. In the oblique groove 49, a transverse portion 72 as an interference avoiding mechanism extending in the circumferential direction of a circle centering on the optical axis of the projection optical system PL is formed on the maximum numerical aperture side portion.

  FIG. 7 shows a lens element in which the pupil plane IS ′ of the projection optical system PL is curved, and the maximum numerical aperture side portion of the pupil plane IS ′ forms part of the second optical system LS2 in the projection optical system PL. 73 shows a state of interference. Due to restrictions on the size of the projection optical system PL and the optical design, such interference between the pupil plane IS ′ and the lens element 73 may be unavoidable. In such a case, the plurality of aperture blades 61 of the aperture stop 25 cannot simply be moved along the pupil plane IS '.

  On the other hand, in the aperture stop 25 having the skew groove 71 having the transverse portion 72 as shown in FIG. 6, the size of the openings by the plurality of stop blades 61 and the projection optical system PL of the plurality of stop blades 61 The position in the optical axis direction changes as follows.

  That is, first, when the aperture stop 25 is set to the maximum numerical aperture, the skew bearing 56 provided on the base plate 34 is disposed at the end portion 72 a of the transverse portion 72 in the skew groove 71. In this state, when the movable frame body 32 is rotated by driving the motor 37 in order to reduce the numerical aperture of the aperture stop 25, the skew bearing 56 moves the inside of the transverse portion 72 toward the oblique portion 74 side. It will move relative to the body 32.

  Here, in the transverse section 72, the displacement of the projection optical system PL in the optical axis direction of the oblique bearing 56 does not occur, and the position of the base plate 34 in the optical axis direction does not change. On the other hand, since the arrow wheel 33 is rotated by the engagement between the rotation angle control groove 48 and the rotation transmission bearing 65, the plurality of aperture blades 61 are rotated toward the small opening diameter side. Accordingly, as indicated by a two-dot chain line in FIG. 7, the aperture stop 25 is positioned in the optical axis direction in a state where the skew bearing 56 is moved relative to the movable frame body 32 in the transverse portion 72. Without changing, only the size of the aperture changes toward the pupil plane IS ′.

  Eventually, when the contour of the opening formed by the plurality of aperture blades 61 reaches the pupil plane IS ′ in the vicinity of the lens element 73 and does not interfere with the lens element 73, the skew in the skew groove 71 is performed. The bearing 56 moves from the transverse portion 72 to the oblique portion 74. In a state where the skew bearing 56 moves relative to the movable frame body 32 in the skew portion 74, the base plate 34 is moved in the optical axis direction of the projection optical system PL. In the aperture stop 25, the aperture is reduced in diameter along the pupil plane IS 'by the rotation of the arrow wheel 33, and the positions of the plurality of aperture blades 61 in the optical axis direction are changed.

Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects described in (a) to (g) in the first embodiment.
(H) In this aperture stop 25, in order to avoid interference between the plurality of aperture blades 61 and the lens element 73 at a portion where the curved pupil plane IS ′ and the lens element 73 interfere, A transverse portion 72 is provided in the row groove 71.

  For this reason, at the portion where the curved pupil plane IS ′ and the lens element 73 interfere with each other, only the size of the aperture of the aperture stop 25 is adjusted while avoiding interference between the plurality of aperture blades 61 and the lens element 73. Can do. In a portion where the curved pupil plane IS ′ and the lens element 73 do not interfere with each other, the optical axis of the optical system of the plurality of aperture blades 61 is adjusted along the pupil plane IS ′ while adjusting the size of the aperture stop 25. The position in the direction can be adjusted.

(Third embodiment)
Next, a third embodiment of the diaphragm device according to the present invention will be described with reference to FIGS. 8 and 9, focusing on portions different from the first embodiment.

  FIG. 8A and FIG. 8B are partial cross-sectional views showing the main part of an aperture stop 81 as the stop device of the third embodiment. In the aperture stop 81 of the third embodiment, as shown in FIGS. 8A and 8B, a plurality of sets (two sets in the present embodiment) of the base plate 34 and the arrow wheel 33 are provided. This is different from the aperture stop 25 of the first embodiment.

  That is, in the aperture stop 81, the object plane side stop 82 disposed on the object plane side of the projection optical system PL and the image plane side stop 83 disposed on the image plane side are in the optical axis direction of the projection optical system PL. Are arranged at predetermined intervals. The base plate 34 o of the object plane side diaphragm 82 and 34 i of the image plane side diaphragm 83 are engaged with a single movable frame 32.

  In the aperture stop 81, the configurations of the object plane side stop 82 disposed on the object plane side of the projection optical system PL and the image plane side stop 83 disposed on the image plane side are both the first embodiment. Therefore, detailed description thereof is omitted here.

  FIG. 9 is a partial development view showing a part of the outer peripheral surface of the movable frame 32 in the aperture stop 81 of the third embodiment. As shown in FIGS. 8A and 9, the movable frame 32 includes an object plane side rotation angle control groove 48o for controlling the rotation angle of the arrow wheel 33o of the object plane side stop 82, and an image plane side. One image plane side rotation angle control groove 48i for controlling the rotation angle of the arrow wheel 33i of the diaphragm 83 is provided so as to be substantially along the optical axis direction of the projection optical system PL. In the present embodiment, the object plane side rotation angle control groove 48o is formed to be slightly curved, and the image plane side rotation angle control groove 48i is formed in an oblique straight line having a slight gradient.

  Further, the movable frame 32 includes an object plane side oblique groove 49o for adjusting the position of the base plate 34o of the object plane side diaphragm 82 in the optical axis direction in the projection optical system PL, and a base plate 34i of the image plane side diaphragm 83. Three image plane side oblique grooves 49i for adjusting the position of the projection optical system PL in the optical axis direction are formed. Here, the object plane side oblique groove 49o and the image plane side oblique groove 49i are both substantially S-shaped and are formed so that one by one approaches each other. Further, the object plane side oblique groove 49o and the image plane side oblique groove 49i are formed such that the interval thereof changes in accordance with the rotation angle of the movable frame 32.

  Here, in FIG. 8A, the skew bearings 56 of the object plane side diaphragm 82 and the image plane side diaphragm 83 are arranged on the maximum numerical aperture side in the object plane side skew groove 49o and the image plane side skew groove 49i, respectively. The state of the aperture stop 81 in the state arrange | positioned at the terminal part 49a is shown. In this state, both the object plane side diaphragm 82 and the image plane side diaphragm 83 are set to the maximum numerical aperture, and the aperture diameter φ1 of the object plane side diaphragm 82 is slightly smaller than the aperture diameter φ2 of the image plane side diaphragm 83. It is set to be.

  FIG. 8B shows that the skew bearings 56 of the object plane side diaphragm 82 and the image plane side diaphragm 83 are respectively connected to the maximum numerical aperture side and the minimum numerical aperture in the object plane side oblique groove 49o and the image plane side oblique groove 49i. The state of the aperture stop 81 in the state arrange | positioned in the intermediate part 49b with the side is shown.

  In this state, the diaphragm blades 61o and 61i of the object plane side diaphragm 82 and the image plane side diaphragm 83 protrude to the optical axis side of the projection optical system PL and are set to a numerical aperture smaller than the maximum numerical aperture. . Further, the difference between the aperture diameter φ1 of the object plane side diaphragm 82 and the aperture diameter φ2 of the image plane side diaphragm 83 is larger than the difference between the numerical apertures φ1 and φ2 in the state where the maximum numerical aperture is set. Yes. The difference between the aperture diameter φ1 and the aperture diameter φ2 is based on the difference in shape between the object plane side rotation angle control groove 48o and the image plane side rotation angle control groove 48i. It is set by causing a difference between the rotation angle of the arrow wheel 33 i of the surface side diaphragm 83.

  The distance L2 between the plurality of diaphragm blades 61o of the object plane side diaphragm 82 and the plurality of diaphragm blades 61i of the image plane side diaphragm 83 is set to be larger than the distance L1 between the two diaphragm blades 61o and 61i in a state where the maximum numerical aperture is set. It is getting smaller. As described above, in the aperture stop 81, as the object plane side stop 82 and the image plane side stop 83 are moved in the optical axis direction of the projection optical system PL, a plurality of stop blades of the object plane side stop 82 are provided. The distance between 61o and the plurality of aperture blades 61i of the image plane side aperture 83 is also adjusted. The adjustment of the distance between the diaphragm blades 61o and 61i is adjusted by the distance between the object plane side oblique groove 49o and the image plane side oblique groove 49i at each rotational position of the movable frame 32.

Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects described in (a) to (g) in the first embodiment.
(K) In this aperture stop 81, a plurality of arrow wheels 33o, 33i having a plurality of diaphragm blades 61o, 61i are arranged at a predetermined interval in the optical axis direction of the projection optical system PL, and the movable frame 32 is a plurality of arrow wheels 33o. , 33i are respectively engaged with the side surfaces.

  For this reason, an object plane side diaphragm 82 and an image plane side diaphragm 83 whose aperture diameter can be changed are provided in the projection optical system PL, and the imaging characteristic of the projection optical system PL is provided with one variable diaphragm. It can be adjusted more finely than the case. Thereby, for example, an abnormal line width on the image plane of the projection optical system PL can be corrected more suitably. Accordingly, the resolution of the projection optical system PL can be further improved.

  The aperture stop 81 has a simple configuration despite the fact that it has a plurality of variable stops, an object plane side stop 82, and an image plane side stop 83. This is because the number of variable stops is increased. There is almost no increase in the size of the aperture stop 81. In addition, in the aperture stop 81, when the number of variable stops is to be further increased, the number of the arrow wheel 33 and the base plate 34 is increased, and the movable frame body 32 corresponds to the number of the arrow wheel 33 and the base plate 34. It is only necessary to form the rotation angle control groove 48 and the skew groove 49. Therefore, the aperture stop 81 is particularly suitable when it is necessary to provide a plurality of variable stops in the projection optical system PL.

  In addition, by providing the aperture stop 81 in the projection optical system PL of the exposure apparatus 21, the exposure accuracy of the exposure apparatus 21 is improved while suppressing an increase in the size of the projection optical system PL and, consequently, an increase in the size of the exposure apparatus 21. be able to.

  (E) In the aperture stop 81, the plurality of arrow wheels 33o and 33i adjust the sizes of the openings formed by the plurality of aperture blades 61o and 61i to different sizes.

For this reason, the imaging characteristics of the projection optical system PL can be adjusted more finely, and the resolving power of the projection optical system PL can be further improved.
(S) In this aperture stop 81, a plurality of arrow wheels 33o, 33i are provided so as to engage with a single movable frame 32. Therefore, the aperture stop 81 having a plurality of variable stops, that is, the object plane side stop 82 and the image plane side stop 83 can be further reduced in size. Further, the object plane side stop 82 and the image plane side stop 83 can be handled as one unit, which is convenient when the projection optical system PL is manufactured.

  (F) With this aperture stop 81, the relative position in the optical axis direction between the plurality of stop blades 61o in the object plane side stop 82 and the plurality of stop blades 61i in the image plane side stop 83 can be adjusted on the movable frame 32. Thus, an object plane side skew groove 49o and an image plane side skew groove 49i are formed. Therefore, the projection optical system can be adjusted by finely adjusting the relative positions of the plurality of diaphragm blades 61o in the object plane side diaphragm 82 and the plurality of diaphragm blades 61i in the image plane side diaphragm 83 according to the residual aberration of the projection optical system PL. The imaging characteristics of the system PL can be corrected with higher accuracy.

(Modification)
The embodiment of the present invention may be modified as follows.
In the first and second embodiments, one rotation angle control groove 48 is provided in the movable frame 32. However, two or more rotation angle control grooves 48 may be provided.

  In the first and second embodiments, three movable grooves 49 and 71 are provided in the movable frame 32. However, one, two, or four or more inclined grooves 49 and 71 are provided. It is good.

  In the third embodiment, two sets of variable apertures are provided in the movable frame 32, that is, the object plane side aperture 82 and the image plane side aperture 83 are provided. A variable aperture may be provided. In this case, it is necessary to adjust the number of rotation angle control grooves 48 and skew grooves 49 formed in the movable frame 32 in accordance with the number of variable diaphragm sets.

In each of the above embodiments, a fixed diaphragm may be provided in the aperture diaphragms 25 and 81.
The shapes of the rotation angle control grooves 48, 48 o, 48 i and the skew grooves 49, 49 o, 49 i, 71 are not limited to those described in the above embodiments, but the pupil plane IS of the projection optical system PL, The shape may be appropriately changed according to the shape of IS ′ and the interference state between the pupil planes IS and IS ′ of the projection optical system PL and the optical elements of the projection optical system PL.

  In each of the above-described embodiments, the aperture stops 25 and 81 of the present invention are arranged in the projection optical system PL of the exposure apparatus 21. For example, another optical system of the exposure apparatus 21, such as the illumination optical system 23, is used. It may be arranged inside a relay optical system or the like in the BMU. In addition, the aperture stops 25 and 81 of the present invention are not limited to the optical system of the exposure device 21, but include, for example, a camera, a video camera, a telescope, a microscope, an optical sensor, a length measuring device, various light source devices, a laser interferometer, a projector, and a projector. It can be mounted on the optical system of other optical machines.

As the light source 22 of the exposure apparatus 21, in addition to the ArF excimer laser (193 nm) described in the above embodiment, for example, a KrF excimer laser (248 nm), an F ₂ laser (157 nm), a Kr ₂ laser (146 nm), Ar _Two lasers (126 nm) or the like may be used. Infrared or visible single wavelength laser light oscillated from a DFB semiconductor laser or fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear optical crystal is obtained. It is also possible to use harmonics that have been converted into ultraviolet light.

  In each of the above embodiments, the present invention is embodied in a scanning exposure type exposure apparatus for manufacturing a semiconductor element, but may be embodied in an exposure apparatus that performs batch exposure by, for example, a step-and-repeat method.

  Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a silicon wafer or the like.

  Of course, the present invention is applied not only to an exposure apparatus used for manufacturing a semiconductor element but also to an exposure apparatus used for manufacturing a display including a liquid crystal display element (LCD) to transfer a device pattern onto a glass plate. be able to. The present invention can also be applied to an exposure apparatus used for manufacturing a thin film magnetic head or the like and transferring a device pattern onto a ceramic wafer or the like, and an exposure apparatus used for manufacturing an image pickup device such as a CCD.

As an exposure apparatus, the present invention can also be applied to an immersion type exposure apparatus in which a liquid (for example, pure water) is filled between the projection optical system PL and the wafer W.
The exposure apparatus 21 of the present invention can be manufactured by the following method, for example. That is, the illumination optical system 23 and the projection optical system PL that are constituted by a plurality of optical elements such as lenses and mirrors are incorporated in the exposure apparatus body and optically adjusted. In addition, a reticle stage RST and wafer stage WST made up of a large number of mechanical parts are attached to the exposure apparatus main body, wiring and piping are connected, and overall adjustment (electrical adjustment, operation check, etc.) is performed. Further, it is desirable that the exposure apparatus 21 be manufactured in a clean room in which the temperature, cleanliness, etc. are controlled.

  As the glass material of each lens element of the illumination optical system 23 and each lens element of the projection optical system PL in the above embodiment, in addition to fluorite, quartz, etc., lithium fluoride, magnesium fluoride, strontium fluoride, lithium-calcium-aluminum -Crystals such as fluoride, lithium-strontium-aluminum-fluoride, fluoride glass composed of zirconium-barium-lanthanum-aluminum, quartz glass doped with fluorine, quartz glass doped with hydrogen in addition to fluorine, OH Modified quartz such as quartz glass containing a group, quartz glass containing OH group in addition to fluorine can be used.

Next, an embodiment of a manufacturing method of a micro device (hereinafter simply referred to as “device”) using the exposure apparatus 21 described above in a lithography process will be described.
FIG. 10 is a flowchart showing a manufacturing example of a device (a semiconductor element such as an IC or LSI, a liquid crystal display element, an image pickup element (CCD or the like), a thin film magnetic head, a micromachine, or the like). As shown in FIG. 10, first, in step S201 (design step), device function / performance design (for example, circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Subsequently, in step S202 (mask manufacturing step), a mask (such as a reticle R) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S203 (substrate manufacturing step), a substrate (or a wafer W when a silicon material is used) is manufactured using a material such as silicon or a glass plate.

  Next, in step S204 (substrate processing step), using the mask and substrate prepared in steps S201 to S203, an actual circuit or the like is formed on the substrate by lithography or the like, as will be described later. Next, in step S205 (device assembly step), device assembly is performed using the substrate processed in step S204. This step S205 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation or the like) as necessary.

  Finally, in step S206 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S205 are performed. After these steps, the device is completed and shipped.

  FIG. 11 is a diagram showing an example of a detailed flow of step S204 of FIG. 10 in the case of a semiconductor device. In FIG. 11, in step S211 (oxidation step), the surface of the wafer W is oxidized. In step S212 (CVD step), an insulating film is formed on the wafer W surface. In step S213 (electrode formation step), an electrode is formed on the wafer W by vapor deposition. In step S214 (ion implantation step), ions are implanted into the wafer W. Each of the above steps S211 to S214 constitutes a pretreatment process at each stage of the wafer processing, and is selected and executed according to a necessary process at each stage.

  At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing process, first, a photosensitive agent is applied to the wafer W in step S215 (resist formation step). Subsequently, in step S216 (exposure step), the circuit pattern of the mask (reticle R) is transferred onto the wafer W by the lithography system (exposure apparatus) described above. Next, in step S217 (development step), the exposed wafer W is developed, and in step S218 (etching step), the exposed member other than the portion where the resist remains is removed by etching. In step S219 (resist removal step), the resist that has become unnecessary after the etching is removed.

Multiple circuit patterns are formed on the wafer W by repeatedly performing these pre-processing and post-processing steps.
If the device manufacturing method of the present embodiment described above is used, the exposure apparatus described above is used in the exposure step (step S216), the resolution can be improved by exposure light in the vacuum ultraviolet region, and the exposure amount control can be performed with high accuracy. Can be done. Therefore, as a result, a highly integrated device having a minimum line width of about 0.1 μm can be produced with a high yield.

1 is a schematic block diagram showing an exposure apparatus of the present invention. The perspective view which shows the aperture stop of 1st Embodiment in a state with the largest numerical aperture. The perspective view which shows the aperture stop of FIG. 2 in a state with a minimum numerical aperture. FIG. 3 is a partial cross-sectional view showing a main part of the aperture stop of FIG. 2. FIG. 3 is a plan view showing movement of one of the arrow wheel and the plurality of aperture blades in FIG. 2. The partial expanded view which shows a part of outer peripheral surface of the movable frame of the aperture stop of 2nd Embodiment. Explanatory drawing which shows the state in which the maximum numerical aperture side part of the pupil surface of a projection optical system is interfering with the optical element of a projection optical system. In the aperture stop of the third embodiment, (a) shows a state arranged on the maximum numerical aperture side, and (b) shows a state arranged on the intermediate position between the maximum numerical aperture side and the minimum numerical aperture side. FIG. The partial expanded view which shows a part of outer peripheral surface of the movable frame of FIG. The flowchart of the manufacture example of a microdevice. 11 is a detailed flowchart regarding the substrate processing of FIG. 10 in the case of a semiconductor element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 21 ... Exposure apparatus, 25, 81 ... Aperture stop as diaphragm apparatus, 31 ... Fixed frame body as frame member, 32 ... Movable frame body as engagement member, 33, 33i, 33o ... Arrow wheel as first plate member , 34, 34i, 34o ... base plate as second plate member, 37 ... motor as drive source of drive mechanism, 48 ... rotation angle control groove as first cam groove constituting part of first cam mechanism 48i: Image surface side rotation angle control groove as a first cam groove constituting a part of the first cam mechanism, 48o: Object as a first cam groove constituting a part of the first cam mechanism Surface-side rotation angle control groove 49... Skew groove as a second cam groove constituting a part of the second cam mechanism, 49 i... A second cam groove constituting a part of the second cam mechanism Image surface side oblique groove, 49o... Part of the second cam mechanism Object-surface-side oblique grooves as second cam grooves, 56... Oblique bearings constituting a part of the second cam mechanism, 61, 61 i, 61 o. Rotational transmission bearings constituting the part, IS, IS ′: pupil plane, PL: projection optical system as an optical system, R: reticle as a mask, W: wafer as a substrate.

Claims (12)

In a projection optical system that projects an image of a predetermined pattern formed on a mask onto a substrate,
A first plate member for movably holding the respective adjustable multiple aperture blade roots the size of the apertures,
A second plate member that supports the first plate member so as to be relatively movable , and is capable of moving the first plate member in an optical axis direction of the projection optical system;
An engaging member that engages with a side surface of the first plate member and engages with a side surface of the second plate member;
A projection optical system comprising: a drive mechanism coupled to the engagement member and driving the first plate member and driving the second plate member via the engagement member. The said 1st plate member adjusts the magnitude | size of the said opening by moving these several aperture blades with the movement to the said optical axis direction of the said 2nd plate member. Projection optical system . Said first plate member, along with the movement of the second plate to the optical axis of the member, to claim 1 or 2, characterized in that rotate relative to the second plate member about said optical axis The projection optical system described. A frame member to which a drive source of the drive mechanism is attached; and the engagement member is formed in a frame shape and is disposed on the inner side of the frame member with respect to the frame member around the optical axis. The projection optical system according to any one of claims 1 to 3, wherein the projection optical system rotates. The engaging member includes at least a part of a first cam mechanism for adjusting the size of the opening and at least one of a second cam mechanism for moving the second plate member in the optical axis direction. The projection optical system according to claim 4, further comprising: 6. The projection optical system according to claim 5, wherein the first cam mechanism has a first cam groove, and the second cam mechanism has a second cam groove. The plurality of first plate members are arranged at predetermined intervals in the optical axis direction, and the engaging members engage with side surfaces of the plurality of first plate members, respectively. The projection optical system according to claim 6 . The projection optical system according to claim 7, wherein the plurality of first plate members adjust the sizes of the openings to different sizes. In an exposure apparatus including a projection optical system that projects an image of a predetermined pattern formed on a mask onto a substrate ,
It said projection as the optical system, an exposure apparatus characterized by a projection optical system according to any one of claims 1-8 is used. The exposure apparatus according to claim 9, wherein the plurality of aperture blades move along a pupil plane of the projection optical system. The pupil plane is a pupil surface curved, the plurality of diaphragm blades, along the pupil plane in which the curved, while adjusting the size of the opening, to move in the optical axis direction of the projection optical system The exposure apparatus according to claim 10. In a device manufacturing method including a lithography process,
12. The device manufacturing method using the exposure apparatus according to claim 9 in the lithography process.

Images