JPH11233412A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection aligner wherein superposing realized at high precision with no degradation in projection precision when adjusting, etc., is performed at, for example, adjusting part of a projection aligner. SOLUTION: Related to adjusting parts 30 and 40 of a projection optical system 17, seal parts 35 and 45 are provided between two members, a lower part lens barrel 23A and an upper part lens barrel 23B, constituting a lens barrel 23 and between two members, an upper part lens barrel 23B and an upper lid 23C, constituting the lens barrel 23. The seal parts 35 and 45 comprise a groove 35 of a lower part ring 36, upper part rings 37 and 47 inserted in the groove 39, and a seal material 38 of inactive grease, etc., packed between the groove 39 and the upper part rings 37 and 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for projecting and transferring an image of a mask pattern, for example, when projecting and transferring a very fine pattern image with high precision in a semiconductor integrated circuit manufacturing process. The present invention relates to a projection exposure apparatus suitable for use.

[0002]

2. Description of the Related Art In a photolithography process occupying an important position in a manufacturing process of a device such as a semiconductor device or a liquid crystal display device, a circuit pattern of a photomask or a reticle (hereinafter simply referred to as a "reticle") is formed by a projection optical system. There is used a projection exposure apparatus that performs projection exposure and transfer onto a substrate such as a wafer or a glass plate to which a photosensitive agent has been applied via a photomask. In recent years, as the degree of integration of semiconductor integrated circuits has increased, such a projection exposure apparatus has a step-and-repeat method in which a substrate is sequentially moved and a pattern is sequentially projected and transferred onto a plurality of exposure regions on the substrate. , The so-called stepper has become mainstream.

In a projection exposure apparatus such as a stepper, a laser beam is often used as exposure light emitted from a light source. In particular, in recent years, since the circuit pattern of a semiconductor element has been steadily miniaturized, the exposure wavelength has been shortened in order to cope with this. For example, an ArF excimer laser having a wavelength of 193 nm has been used.

However, in the case of exposure light such as an ArF excimer laser, the emission spectrum line overlaps with the oxygen absorption spectrum region, so that light absorption efficiency is reduced due to oxygen absorption and inconvenience is caused by generation of ozone. In particular, ozone is not only harmful but also has a bad effect on light use efficiency (transmittance), and furthermore, causes a chemical reaction with ions and suspended matters in the air to cause white turbidity on the surface of an optical element such as a lens. Which causes a reduction in the performance of the projection exposure apparatus.

In order to avoid such a problem, a projection exposure apparatus using an exposure light such as an ArF excimer laser has conventionally been provided with an atmosphere in the optical path of the exposure light such as a nitrogen gas or a helium inert to a photochemical reaction. Technology for replacing with an inert gas such as a gas (for example, Japanese Patent Application Laid-Open No. 6-260385,
(A technique disclosed in JP-A-6-260386).

In this type of projection exposure apparatus, the pattern formed on the wafer and the projected image of the pattern of the next layer are aligned with each other, so that the overlay accuracy matching the resolution of the projection optical system is required. Is required. The overlay accuracy is generally 1/4 to 1/10 of the minimum resolution line width of the projection optical system. For example, for a projection optical system that resolves a 0.25 μm-wide pattern for use in VLSI manufacturing, Requires an overlay accuracy of about 70 nm or less for the entire projection exposure apparatus. Needless to say, it is important to improve the accuracy of each part of the projection exposure apparatus in order to achieve high-accuracy overlay accuracy.

[0007]

As described above, in a conventional projection exposure apparatus, it is important to increase the accuracy of each part. For example, in a projection optical system, a high accuracy is required due to the following factors. Has been hindered.

[0008] The projection optical system of the projection exposure apparatus has a structure in which a plurality of lenses are arranged and stored along the optical axis of exposure light inside a lens barrel. Such a projection optical system is provided with an adjustment unit configured to relatively move one lens relative to one lens in order to finely adjust the focus, magnification, and the like of the projection optical system. In this adjustment unit,
In order to prevent the inert gas supplied into the lens barrel from leaking, a rubber-based material or the like is provided between the holding member for holding the one lens and the holding member for holding the other lens. Packing or gasket is sandwiched.

However, if a packing or gasket made of an elastic material such as a rubber-based material has a certain thickness or more, when the packing and the gasket are tightened with two holding members, the packing and the gasket are not only in the thickness direction but also in the thickness direction. It may also be deformed in the direction perpendicular to the direction. Then, the positional relationship between the two lenses,
The positional relationship originally intended is shifted in a direction orthogonal to the optical axis, and as a result, the adjustment by the adjusting unit may not be performed with high accuracy.

In the adjusting section having such a sealing property, when the two lenses are relatively moved for adjustment, the volume of the space between the two lenses fluctuates, and the air pressure in this space fluctuates. I do. For example, if the two lenses are moved in a direction to approach each other, the air pressure in the space increases, and if the two lenses are moved in a direction away from each other, the air pressure in the space decreases. In this way, if the space between the two lenses, that is, the atmospheric pressure of the light path atmosphere of the exposure light fluctuates, the refractive index of the atmosphere changes, and the imaging position may fluctuate or the image may be distorted. is there.

As described above, the problems that the adjustment by the adjustment unit using the packing or the gasket cannot be performed with high accuracy, and that the image formation position fluctuates or the image is distorted due to the adjustment are all caused by the projection. This causes a reduction in projection accuracy in the exposure apparatus, and as a result, hinders the realization of high-accuracy superposition of patterns. The present invention has been made in consideration of the above points, and it is possible to realize high-accuracy superimposition without lowering the imaging accuracy even if adjustment is performed in, for example, an adjustment unit of a projection exposure apparatus. It is an object to provide a projection exposure apparatus as described above.

[0012]

The invention according to claim 1 is
A projection exposure apparatus (11) for transferring a pattern of a mask (13) onto a substrate (12), an illumination optical system (15) for irradiating the mask (13) with exposure light, and emitting the exposure light. A light transmission system (16) disposed between a light source (14) and the illumination optical system (15); and a projection optical system (20) for projecting exposure light from the mask (13) onto the substrate (12). 17), a casing (23) is provided so as to surround the optical path of the exposure light and into which an inert gas is supplied, and the casing (23) is provided with the casing (23). A seal portion (35, 45) for preventing the inactive gas from flowing out of the casing (23) is provided between the two members constituting (23), and the seal portion (35, 45) is provided. , A recess formed on one of the member sides ( 9), convex portions are formed on the other of said member side is inserted into the recess (39) in (37,4
7) and a filler (38) filled between the concave portion (39) and the convex portion (37, 47) and having a sealing property.

According to the projection exposure apparatus (11), the casing in which the inert gas is supplied to at least a part of the illumination optical system (15), the light transmission system (16), and the projection optical system (17). Since (23) is provided, the atmosphere of the exposure light in the casing (23) is replaced with an inert gas. The seal portions (35, 45) are provided with a concave portion (39) and a convex portion (37, 45) inserted into the concave portion (39).
47), the filler (38) is filled between the inner surface of the concave portion (39) and the convex portion (37) inserted into the concave portion (39). , 47)
Will be interposed between the outer surface of the first member and the second member. Accordingly, the one member and the other member are relatively displaced in a direction of approaching / separating from each other, and accordingly, the concave portion (39) and the convex portion (37,
47), the filler (38) remains in a state of being sandwiched between the inner surface of the concave portion (39) and the outer surface of the convex portion (37, 47) to maintain the sealing property. It has become. Moreover, at this time, the filler (3) interposed between the inner surface of the concave portion (39) and the outer surface of the convex portion (37, 47).
8) is less likely to be deformed in a direction orthogonal to the displacement direction.

According to a second aspect of the present invention, in the projection exposure apparatus (11) according to the first aspect, a photochemically inert grease is used as the filler (38). .

As described above, the casing (23) is constituted by using grease, which is a semi-solid or viscous viscous material, instead of an elastic material such as a conventional packing or gasket as the filler (38). Even when the two members are displaced relative to each other, the filler (38) does not exert a reaction force that shifts the two members. Moreover, since the inert grease is inert to the photochemical reaction, the casing (2)
3) The sealing property can be maintained without causing a photochemical reaction with the inert gas supplied in the inside.

The invention according to claim 3 is the invention according to claim 1 or 2
In the projection exposure apparatus (11), the projection optical system (17) has a plurality of optical elements (21) arranged along an optical axis thereof and a plurality of holding units for holding the plurality of optical elements (21). A member (22) and the plurality of holding members (22)
And a lens barrel (23) for accommodating the seal member (3).
5, 45) are provided between two holding members (22) which move relatively among the plurality of holding members (22).

Thus, the invention according to claim 1 or 2 can be applied to an adjustment unit of a projection optical system (17) having a structure in which two holding members (22) holding an optical element (21) such as a lens are relatively moved. Etc. can be applied.

The invention according to claim 4 is the invention according to claims 1 to 3
In the projection exposure apparatus (11), the gas supply mechanism (50) for supplying the inert gas into the lens barrel (23) of the projection optical system (17), and the lens barrel (2).
3) The inert gas circulated inside the lens barrel (2)
And 3) a gas discharge mechanism (52) for discharging the gas.

Thus, the atmosphere in the optical path of the exposure light of the projection optical system (17) is replaced with the inert gas.

According to a fifth aspect of the present invention, there is provided an illumination optical system (15) for irradiating the mask (13) with exposure light, and for projecting the exposure light on the substrate (12) through the mask (13). A projection exposure apparatus (1) including a projection optical system (17) in which a plurality of optical elements (21) are arranged along the optical axis.
In 1), a gas supply mechanism (50) for supplying an inert gas to a plurality of spaces (S) sandwiched by the plurality of optical elements (21), and a first optical element (50) of the projection optical system (17). 21A, 21C) and the first optical element (2
1A, 21C) and the first space (S1, S2) sandwiched between the second optical elements (21B, 21D) relatively moved.
3) into a gas chamber (S2, S2) filled with the inert gas.
And a communication means (25) for communicating with (4).

As described above, since the first space (S1, S3) and the gas chamber (S2, S4) communicate with each other, the first optical element (21A, 21C) and the second optical element (21B, 21).
D) relative to each other and the volume of the first space (S1, S3) fluctuates, the first space (S1, S3) and the gas chamber (S2, S2).
S4) is kept at the same pressure as the first space (S1, S3).
Of the inert gas is suppressed.

According to a sixth aspect of the invention, in the projection exposure apparatus (11) according to the fifth aspect, the gas chambers (S2, S
4) is the first space (S) of the plurality of spaces (S).
The second space (S2, S4) is different from (1, S3).

That is, since the first space (S1, S3) and the second space (S2, S4) of the projection optical system (17) communicate with each other, the second optical element (21B, 21D) is moved. Also the first space (S1, S3) and the second space (S2, S4)
Thus, the pressure of the inert gas does not fluctuate.

According to a seventh aspect of the present invention, in the projection exposure apparatus (11) according to the sixth aspect, the second space (S2, S2
4) is a third optical element (21C, 21E) and the second optical element (21C) arranged on the opposite side of the first optical element (21A, 21C) with respect to the second optical element (21B, 21D). 21B, 21D).

As a result, the second optical element (21B, 21B)
Even if D) is moved, the second optical element (21B, 21D)
Does not occur in the first space (S1, S3) and the second space (S2, S4) located on both sides of.

The invention according to claim 8 is the invention according to claims 5 to 7
In the projection exposure apparatus (11) according to any one of the above, the gas supply mechanism (50) may include the plurality of optical elements (2).
The inert gas is supplied to each of the plurality of spaces (S) through gas supply holes (25) provided in the plurality of holding members (22) for holding 1) and communicating with each other.

Thus, when the inert gas is supplied to one space (S), the gas supply holes (25) pass through the entire plurality of spaces (S) including the first space (S1, S3). An inert gas will be supplied.

The ninth aspect of the present invention relates to the fifth to eighth aspects.
In the projection exposure apparatus (11) according to any one of (1) to (3), a movable member (22) that holds the second optical element (21B, 21D) and a coupling part (35, 45) is characterized in that a sealing material (38) is provided.

As a result, the second optical element (21B, 21D) held by the movable member (22) is replaced with the first optical element (2).
1A, 21C), the coupling portion (3) between the movable member (22) and the main body of the projection optical system (17).
In (5, 45), the sealing property is maintained.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a projection exposure apparatus according to the present invention will be described below with reference to FIGS. FIG. 1 schematically shows a configuration of a projection exposure apparatus according to an embodiment of the present invention.
1 is a projection exposure apparatus, 12 is a wafer (substrate), 13 is a reticle (mask), 14 is a light source that emits exposure light, 15 is an illumination optical system that irradiates the reticle 13 with exposure light, 16 is a light source 14 and illumination optical A light transmission system disposed between the
Reference numeral 7 denotes a projection optical system that projects exposure light from the reticle 13 onto the wafer 12.

The projection exposure apparatus 11 uses
For example, a short wavelength laser light such as an ArF light source excimer laser is emitted from the light source 14.

The illumination optical system 15 includes an optical integrator (rod integrator or fly-eye lens), a relay lens, a condenser lens, a field stop (reticle blind), an aperture stop, and the like. The illumination optical system 15 illuminates the reticle 13 with the exposure light in order to equalize the illuminance of the light flux of the exposure light emitted from the light source 14 and sent through the light transmission system 16.

In the projection exposure apparatus 11, the optical path of exposure light from the light source 14 to the reticle 13, ie, the illumination optical system 1
5, the light transmitting system 16 and the reticle 13 are surrounded by a container 2
It is surrounded by 0. Inside this container 20,
An inert gas such as a nitrogen gas or a helium gas, which is inert to a photochemical reaction, is supplied via a supply pipe (not shown). Thereby, the illumination optical system 15 and the light transmission system 16
Has a configuration in which the optical path atmosphere of the exposure light is replaced with an inert gas.

As shown in FIG. 2, the projection optical system 17 includes a plurality of lenses (optical elements) 21, a holding member (movable member) 22 for holding each lens 21, and these holding members 2.
And a cylindrical lens barrel (casing) 23 for housing the lens barrel 2. In the projection optical system 17, the exposure light transmitted through the reticle 13 (see FIG. 1) is projected onto the wafer 12 (see FIG. 1) via a plurality of lenses 21.

Each holding member 22 is formed at its center with an opening 24 communicating with both sides of the holding member 22.
One side (lower side) of the holding member 22 is a small-diameter portion 24 a having a smaller diameter than the lens 21, and the other side (upper side) is a large-diameter portion 24 b having a larger diameter than the lens 21. The lens 21 is provided between the small diameter portion 24a and the large diameter portion 24b.
The configuration is such that a step portion 24c having substantially the same diameter as that is formed.
Thus, each holding member 22 holds the lens 21 by fitting the outer periphery of the lens 21 into the step portion 24 c of the opening 24.

Further, the holding member 22 has a plurality of communicating portions on the outer peripheral side of the small-diameter portion 24a of the opening portion 24 for communicating one surface side of the holding member 22 and the other surface side on which the large-diameter portion 24b is formed. A hole (communication means, gas supply hole) 25 is formed.

The lens barrel 23 is, for example, a lower lens barrel 23A.
, An upper lens barrel 23B, and an upper lid 23C. The inner peripheral surface 26 of each of the lower lens barrel 23A and the upper lens barrel 23B has an inner diameter substantially the same as the outer diameter of the holding member 22. Lower lens barrel 23A, upper lens barrel 23
An opening 27 having a smaller diameter than the outer diameter of the holding member 22 is formed at the lower end of B. With this opening 27, a holding portion 28 for holding the held holding member 22 is formed at the lower end of the lower lens barrel 23A and the upper lens barrel 23B.

The lower lens barrel 23A and the upper lens barrel 23B
An adjustment unit 30 for adjusting these relative positions is provided between the control unit and the control unit. The adjusting unit 30 includes a plurality of adjusting screws 33 and biasing members 34 provided between a flange 31 formed at an upper end of the lower lens barrel 23A and a flange 32 formed at a lower end of the upper lens barrel 23B. It is composed of The adjusting screw 33 is rotatably supported on the flange 32 side, and a screw portion formed at the tip thereof is screwed to the flange 31 side. The biasing member 34 is made of a spring or the like, and is interposed in a compressed state between the flange 31 and the flange 32, so that the lower lens barrel 23A and the upper lens barrel 23B are separated from each other. It is to energize.

In such an adjusting section 30, the adjusting screw 33
By turning, the relative position between the flange 31 and the flange 32, that is, the relative position between the lower lens barrel 23A and the upper lens barrel 23B is displaced. That is, when the adjusting screw 33 is tightened, the lower lens barrel 23A and the upper lens barrel 23B relatively move in the approaching direction, and when the adjustment screw 33 is loosened, the lower lens barrel 23A and the upper lens barrel 23B relatively move in the separating direction. It is supposed to. Then, the adjustment unit 30 displaces the relative position between the lower lens barrel 23A and the upper lens barrel 23B, thereby forming the uppermost lens 21D of the lower lens barrel 23A and the upper lens barrel 23A.
The positional relationship between B and the lowermost lens 21C is adjusted. (Here, for the sake of explanation, the projection optical system 1
Are referred to as lenses 21A, 21B, 21C,... From the uppermost part to the lowermost part. )

Further, the adjusting portion 30 between the lower lens barrel 23A and the upper lens barrel 23B has a sealing portion (coupling portion) 35.
Is provided. The seal part 35 includes a lower ring 36 provided on the upper surface of the holding member 22 housed in the uppermost part of the lower lens barrel 23A, and an opening 27 at the lower end of the upper lens barrel 23B.
, And a sealing material (filler) 38 interposed between the lower ring 36 and the upper ring 37. The lower ring 36 is substantially U-shaped in cross section, and has a groove (recess) 3 on its upper surface side.
9 are formed. The groove 39 has substantially the same diameter as the upper ring 37, and its width is set to be larger by a predetermined dimension than the thickness of the upper ring 37. The sealing material 38 is made of a viscous material, such as Demnum, and is made of inert grease or the like having an inert property to a photochemical reaction. The sealing material 38 is provided in a groove 39 of the lower ring 36. Is filled.

In such a sealing portion 35, the lower end of the upper ring 37 is inserted into the sealing material 38 filled in the groove 39 of the lower ring 36. As a result, the seal member 38 is interposed between the inner side surface of the groove 39 and the outer side surface of the upper ring 37, and communication between the inside and outside of the seal member 38 is cut off, and the adjusting portion 30 exhibits a sealing property. .

An adjusting section 40 having the same structure as the adjusting section 30 is also provided between the upper end of the lens barrel 23 and the upper lid 23C disposed above the upper section. Adjustment unit 40
Is a flange 41 formed at the upper end of the upper lens barrel 23B.
And an adjusting screw 33 and a biasing member 34 provided between the upper cover 23C and the outer peripheral portion of the upper cover 23C. Then, by turning the adjustment screw 33, the relative position between the upper lens barrel 23B and the upper lid 23C is displaced, and the upper lens barrel 23B and the upper lid 23C are urged by the urging member 34 in the direction away from each other. I have. In the adjustment unit 40, by displacing the relative position between the upper lens barrel 23B and the upper lid 23C, the uppermost lens 21B of the upper lens barrel 23B,
The positional relationship with the lens 21A mounted on the upper lid 23C is adjusted. In addition, this upper lid 23C
An opening 42 having a step 42a for holding the lens 21A is formed in the center, and a communication hole 43 is formed in the outer periphery thereof.
Is formed, and also has a function corresponding to the holding member 22.

Further, the adjusting portion 40 is provided with a seal portion (coupling portion) 45 similar to the seal portion 35. The seal portion 45 is provided with a lower ring 36 provided on the upper surface of the holding member 22 housed in the uppermost portion of the upper lens barrel 23B.
And an upper ring (convex portion) 47 having a substantially L-shaped cross section attached to the lower surface of the upper lid 23C, and a seal member 38 interposed between the lower ring 36 and the upper ring 47.

In the sealing portion 45, the upper ring 47 is attached to the sealing material 38 filled in the groove 39 of the lower ring 36.
Is inserted at the lower end. As a result, the seal member 38 is interposed between the inner side surface of the groove 39 and the outer side surface of the upper ring 47, and communication between the inside and the outside is interrupted, so that the adjusting portion 40 exhibits a sealing property. .

In such a projection optical system 17, the lens barrel 23
Each of the plurality of holding members 22 housed in the
5, the spaces S1 and S3 between, for example, two lenses 21A and 21B and between the two lenses 21C and 21D located above and below each other are connected to each other.

At the upper end of the projection optical system 17,
In one of the communication holes 43 formed in the upper cover 23C of the lens barrel 23, a supply pipe (gas supply mechanism) 50 for supplying an inert gas inert to a photochemical reaction such as nitrogen gas or helium gas is provided. A sealing plug 51 that is connected and closes the other communication hole 43 is mounted. On the other hand, the projection optical system 17
A discharge pipe (gas discharge mechanism) 52 is connected to one communication hole 25 to the holding member 22 of the lens 21 facing the opening 27 at a lower end portion of the lens 21, and a sealing plug 5 is connected to the other communication hole 25.
1 is attached. The supply tube 5 is provided in the lens barrel 23.
0, an inert gas is fed in, and this inert gas is supplied to each space S through the communication hole 25 of each holding member 22,
It is discharged from the discharge pipe 52. Thereby, the projection optical system 1
In 7, the atmosphere of the optical path of the exposure light in the lens barrel 23 is replaced with an inert gas, and the inert gas is circulated.

In the projection optical system 17, when adjusting the focal point and magnification of the exposure light, the adjusting screws 33 are turned in the adjusting units 30 and 40, so as to be positioned above and below the adjusting units 30 and 40. Lens 21A,
The positional relationship between 21B, 21C, and 21D is adjusted. At this time, when the adjustment screw 33 is turned, the sealing portion 35,
At 45, the lower ring 36 and the upper ring 37 or 47 are relatively displaced in the vertical direction. At this time, the lower ring 36 and the upper ring 37 or 4
Even when the sealing material 38 is relatively displaced in the vertical direction, the sealing material 38 interposed therebetween is made of inert grease or the like, so that the sealing material 38 is not elastically deformed like a packing or a gasket. Thus, the state of being interposed between the side surface of the upper ring 39 and the side surfaces of the upper rings 37 and 47 is maintained. As a result, the sealing property between the lower ring 36 and the upper ring 37 or 47, that is, the adjusting portions 30, 40 is maintained.

As shown in FIG. 1, a desired inert gas atmosphere is formed between the final lens of the projection optical system 17 and the wafer 12 by an appropriate method. . Specifically, the entire stage device 48 on which the wafer 12 is mounted is surrounded by a container (not shown) from the lower end of the projection optical system 17 and the container is filled with an inert gas. There is a method of continuously supplying an inert gas into an open space between the wafer 12 and the wafer 12 to form an inert gas atmosphere. In the present embodiment, as shown in FIG. 1, the reticle 13 (and the reticle stage (not shown)) is arranged in the container 20. However, the reticle 13 and the reticle 13 are arranged between the illumination optical system 15 and the reticle 13. At least one of the space between the projection optical system 13 and the projection optical system 17 may be configured as an open space to flow an inert gas.

In such a projection exposure apparatus 11, the light source 1
Exposure light emitted from 4 is transmitted by a light transmission system 16 and an illumination optical system 15.
The reticle 13 is irradiated with the light through the reticle 13, and the image of the circuit pattern formed on the reticle 13 is projected and transferred to a predetermined exposure area of the wafer 12 via the projection optical system 17. And
After the transfer of the pattern to the exposure area is completed, the wafer 12 is moved to a predetermined position and positioned by the stage device 48, and the pattern is projected and transferred to the next exposure area. In this manner, the projection transfer of the pattern onto the entire wafer 12 is performed by the so-called step-and-repeat method in which the movement / positioning of the wafer 12 and the projection transfer of the pattern are sequentially repeated.

As described above, in the projection exposure apparatus 11,
The surroundings of the illumination optical system 15, the light transmission system 16, and the reticle 13 are surrounded by a container 20, into which an inert gas is supplied. Further, the projection optical system 1
7 is provided with a supply pipe 50 for supplying an inert gas to the inside thereof, and a discharge pipe 52 for discharging the inert gas circulated inside the lens barrel 23 from the barrel 23. Has become. Thereby, the atmosphere of the optical path of the exposure light from the light source 14 to the wafer 12 is replaced with the inert gas,
Exposure light passes through an inert gas atmosphere. Therefore,
It is possible to prevent the generation of ozone generated when the exposure light causes a photochemical reaction with air. As a result, projection exposure can be prevented without damaging the environment or lowering the light use efficiency (transmittance) of the exposure light, and preventing the surface of the optical element such as the lens 21 and the mirror from becoming cloudy. The performance of the device 11 can be exhibited stably. Further, in the projection optical system 17, not only the atmosphere in the optical path of the exposure light can be replaced with an inert gas, but also the inert gas can be recovered from the lens barrel 23 and circulated.
The inert gas can be efficiently used without waste.
Further, for example, in a projection optical system 17 that projects an ArF excimer laser onto the wafer 12 as exposure light, the lens barrel 23 is used.
Even if the inside is replaced with an inert gas, the lens 21 is held in the holding member 2.
Adhesive (or filler) to be fixed to the lens 2 or the lens barrel 23
Foreign matter (for example, water, hydrocarbon, or a substance that diffuses exposure light other than these) generated from the inner wall of the lens adheres to the lens 21 or enters (floats) in the illumination optical path, thereby causing the projection optical system 17 to emit light. There is a problem that the transmittance fluctuates. However, by collecting the inert gas from the lens barrel 23 as described above, it is possible to minimize the fluctuation of the transmittance of the projection optical system 17.

Further, the supply pipe 50 is provided with a plurality of holding members 22.
Are supplied to the plurality of spaces S1, S2,... Through the communication holes 25 respectively formed in the plurality of spaces S1, S2,. Thus, if the inert gas is supplied to the uppermost space S1 of the projection optical system 17, the inert gas is supplied to the other spaces S2, S3, S4,... Through the communication holes 25, 25,. In the entire projection optical system 17, the atmosphere of the optical path of the exposure light can be replaced with an inert gas. In addition,
In the projection optical system 17 whose optical axis is disposed along the vertical direction (gravity direction), it is preferable to supply an inert gas from the lowermost space thereof. It is desirable that the inert gas be exhausted from the uppermost space S1.

According to the projection exposure apparatus 11 described above, the adjusting units 30 and 40 of the projection optical system 17 include the lens barrel 23
And seal members 35 and 45 are provided between the two members of the lower lens barrel 23A and the upper lens barrel 23B constituting the lens barrel and between the two members of the upper lens barrel 23B and the upper lid 23C constituting the lens barrel 23. Has become. And these seal parts 3
Reference numerals 5 and 45 denote a groove 39 of the lower ring 36, upper rings 37 and 47 inserted into the groove 39, and a sealing material 38 such as inert grease filled between the groove 39 and the upper rings 37 and 47. It consists of. Therefore, even if the adjustment is performed in the adjustment units 30 and 40, the sealing material 38 is not in contact with the side surface of the groove 39 of the lower ring 36 and the upper
7 and 47 can be maintained while maintaining a state of being interposed between them and the side surfaces thereof, and the sealing property can be maintained. In addition, since the sealing material 38 such as inert grease is a viscous material, even if the lower ring 36 and the upper rings 37 and 47 are relatively displaced, the sealing material 38 can be easily deformed following the relative displacement. A reaction force that shifts the positional relationship between the upper ring 36 and the upper rings 37 and 47 is not exerted. Therefore, the lenses 12A, 12B or 12 of the adjustment units 30, 40 are adjusted by the adjustment.
The positional relationship between C and 12D does not shift, and adjustment can be performed with high accuracy. As a result, the imaging accuracy of the projection exposure apparatus 11 is reduced, that is, the focal position and magnification of the projection optical system 17, fluctuations such as Seidel's five aberrations, and telecentricity and image contrast are not reduced. The superimposition of patterns with high accuracy can be realized.

Further, in the above-described projection exposure apparatus 11, as described above, the lens barrel 23 is provided with the supply pipe 50 for supplying the inert gas to the plurality of spaces S sandwiched by the plurality of lenses 21. It has become. And the adjusting unit 3
At 0, a space (first space) S3 sandwiched between a lens (first optical element) 21C and a lens (second optical element) 21D relatively moved with respect to the lens 21C, a lens 21D, and a lens 21D The lens (third optical element) 21 </ b> E disposed on the opposite side and a space (gas chamber, second space) S <b> 4 sandwiched by the lens (third optical element) 21 </ b> E communicate with the communication hole 25. That is, only the lens 21D is changed without changing the distance between the lenses 21C and 21E.
E moves relative to E. Similarly, the adjusting unit 40
, A space (first space) S1 between a lens (first optical element) 21A and a lens (second optical element) 21B relatively moved with respect to the lens (first optical element) 21A, and a lens 21B and a space opposite to the lens 21B. (Third optical element) 2 arranged on the side
1C and a space (gas chamber, second space) S2 sandwiched between
It is configured to be communicated by the communication hole 25. That is, only the lens 21B relatively moves with respect to the lenses 21A and 21C without changing the distance between the lenses 21A and 21C. FIG. 2 does not show a mechanism for independently driving 21B and 21D. This allows
The adjustment is performed in the adjustment units 30 and 40, and the spaces S3 and S1 are adjusted.
This space S3, S1
Communicates with the spaces S4 and S2, the spaces S3 and S1 and the spaces S4 and S2 are maintained at the same pressure, and the spaces S3 and S1
Of the inert gas is suppressed. Also in this case, it is possible to realize high-accuracy pattern superposition without causing a decrease in projection accuracy in the projection exposure apparatus 11 by performing adjustments by the adjustment units 30 and 40.

Further, in the adjusting sections 30 and 40, the sealing sections 35 and 45, which are the connecting sections of the holding member 22 for holding the lenses 21D and 21B, and the upper barrel 23B and the upper lid 23C, which are the main body of the projection optical system 17, are provided. , Each with a sealing material 3
8 is provided. As a result, the lenses 21D and 21B held by the holding member 22 and relatively moved with respect to the upper lens barrel 23B and the upper lid 23C during the adjustment,
The sealability can be maintained in the adjustment units 30 and 40 of the projection optical system 17.

In the above embodiment, the adjusting unit 3
Although the seal portions 35 and 45 are provided at 0 and 40,
Instead of the seal portions 35 and 45, for example, a configuration including a seal portion as described below may be provided. As shown in FIG. 3, the seal portion 55 provided in the adjustment portion 30 is provided on the outer peripheral surface side of the flange 31 at the upper end of the lower lens barrel 23A and the flange 32 at the lower end of the upper lens barrel 23B. Further, it is constituted by a cylindrical member 56 made of rubber, for example. Similarly, the seal portion 57 provided in the adjustment portion 40 also has a configuration in which, for example, a rubber cylindrical member 58 is provided on the outer peripheral surface side of the flange 41 at the upper end of the upper lens barrel 23B and the upper lid 23C. belongs to.

If the entire projection optical system 17 is housed in a container or the like and an inert gas is supplied thereto, the sealing section 3
5, 45, 55 and 57 may be omitted. In such a case, the inside of the container becomes a gas chamber, and the gas chamber and the inside of the lens barrel 23 are communicated via the communication hole 43. Further, in the above embodiment, the spaces S3, S
1 communicates with the spaces S4 and S2 located on the opposite side of the lens 21D and 21B via the communication hole 25, but communicates with the other space S or the projection optical system 17 via a communication pipe or the like. May be provided separately and communicate with a container filled with an inert gas. In the latter case, for example, spaces S1 and S2 or S3 and S4 are communicated with the separately provided container.

In addition, in the above embodiment, the supply tube 50 is provided in the projection optical system 17 and the inert gas is supplied from the supply tube 50.
In a case where the lens barrel 23 is integrally connected to the container 20 surrounding the periphery of the container 3, the supply pipe 50 is omitted, and
As a gas chamber, an inert gas may be sent from the container 20 to the lens barrel 23 through the communication hole 43. Also,
It is also possible to abolish the discharge pipe 52 and discharge the inert gas from the opening 27 at the lower end of the lens barrel 23.

Further, in the above embodiment, the present invention is applied to the projection optical system 17, but it is needless to say that other parts such as the illumination optical system 15 and the light transmission system 16 can be used as lenses or mirrors. The present invention can be applied in the same manner as described above as long as the two optical elements move relative to each other. For example, by moving an optical integrator (fly-eye lens) in the direction of the optical axis of the illumination optical system, in other words, by changing the distance between the optical integrator and each of the two optical elements interposed therebetween, This is effective for an illumination optical system configured to adjust the illuminance distribution of exposure light on the reticle 13.

In the projection optical system 17 shown in FIG.
When the lens 21C is moved by the adjusting unit 30, the lenses 21A, 2A,
1B will also move. However, the mechanism for driving the lens 21 of the projection optical system 17 is not limited to this configuration. For example, the members for holding the lenses 21A and 21B are not stacked on the holding member for the lens 21C. Even if the holding member of the lens 21C is driven, the lenses 21A and 21B may not move. Instead of the adjusting screw 33, the lens (or its holding member) may be supported and moved by, for example, three piezoelectric elements (piezo elements or the like). As described above, by increasing the number of lenses 21 configured to be movable, at least three of the focal position, magnification, distortion, astigmatism, field curvature, coma, and spherical aberration of the projection optical system 17 are obtained. One may be configured to be adjustable.
Further, the projection optical system 17 is provided with a tiltable parallel flat plate disposed on the wafer 12 side for correcting eccentric coma aberration. The present invention is also applied to a driving mechanism of this parallel flat plate. Can be applied. Further, in the above-described embodiment, the description has been given on the assumption that the projection optical system includes only a plurality of refractive optical elements (lenses). However, the projection optical system includes only a plurality of reflective optical elements, or the reflective optical element and the refractive optical element. The present invention can also be applied to a catadioptric optical system combining the above. Further, in an exposure apparatus using ultraviolet light having a wavelength of about 190 nm or more (such as an ArF excimer laser) as exposure light, it is preferable to use nitrogen as the above-mentioned inert gas in consideration of cost and the like,
When the projection optical system is a catadioptric optical system, it is preferable to supply nitrogen to the illumination optical system and supply helium to the projection optical system. The wavelength is 200 nm
In an exposure apparatus that uses ultraviolet light (FrF excimer laser or the like) of a degree or more as exposure light, chemically clean dry air is used instead of nitrogen or an inert gas in the illumination optical system 15.
It may be supplied to the like. Dry air is obtained by removing ammonium ions and the like from air in a clean room by a chemical filter made of activated carbon or the like, and adjusting the humidity to, for example, about 5% or less. Further, in an exposure apparatus using an ultraviolet ray (F2 laser or the like) having a wavelength of about 190 nm or less, it is practical to use helium as the above-mentioned inert gas. In addition to the above, a step-and-repeat type projection exposure apparatus has been described as an example. However, a scanning projection exposure apparatus that exposes a pattern of the reticle 3 by synchronously moving the reticle 3 and the wafer 2 may also be used. The techniques of the present invention can be applied as well. Further, the type of the projection exposure apparatus is not limited to the one for manufacturing a semiconductor, and is, for example, a projection exposure apparatus for a liquid crystal for exposing a liquid crystal display element pattern to a square glass plate, and a method for manufacturing a thin film magnetic head. The technology of the present invention can be widely applied to an exposure apparatus and the like. Further, the magnification of the projection optical system 17 may be not only a reduction system but also any one of an equal magnification and an enlargement system. The light source used as the exposure light in the projection exposure apparatus is not limited to an ArF excimer laser (193 nm), but may be a KrF excimer laser (248 nm), an F ₂ laser (157 nm), or a harmonic of a YAG laser or a metal vapor laser, for example. EUV (Extreme Ultra Violet) light having an oscillation spectrum in the range of 5 to 15 nm (soft X-ray region), or a charged particle beam such as X-ray can also be used. In such a case,
The projection optical system 17 uses quartz or fluorite as a glass material when using an excimer laser, and uses a catadioptric system when using X-rays (a reticle is also of a reflection type). Further, the exposure apparatus using EUV light has a reduction projection optical system including only a plurality of (about four) reflection optical elements (mirrors) while defining an illumination area on the reflection type mask in an arc slit shape. The pattern of the reflective mask is transferred onto the wafer by synchronously moving the reflective mask and the wafer at a speed ratio corresponding to the magnification of the reduction projection optical system. At this time, the EUV light irradiates the reflective mask with its principal ray inclined with respect to an axis orthogonal to the reflective mask.

Other than this, any configuration may be adopted as long as it does not depart from the gist of the present invention, and it is needless to say that the above-described configurations may be appropriately selectively combined. No.

[0061]

As described above, according to the projection exposure apparatus of the first aspect, the casing in which the inert gas is supplied to at least a part of the illumination optical system, the light transmission system, and the projection optical system. The casing is provided with a seal portion between two members constituting the casing, including a concave portion on one member side, a convex portion on the other member, and a filler filled therebetween. I have. By providing a casing to which an inert gas is supplied in at least a part of the illumination optical system, the light transmission system, and the projection optical system, the atmosphere of the exposure light is replaced with the inert gas in the casing, and Is prevented from occurring. Therefore, it is possible to prevent the environment and the light use efficiency from being reduced and to prevent the surface of an optical element such as a lens from becoming cloudy, and to stably exhibit the performance of the projection exposure apparatus. In addition, since the sealing portion of the casing has a structure in which a filler is filled between the concave portion and the convex portion, the filler is formed between the inner surface of the concave portion and the outer surface of the convex portion inserted into the concave portion. Between them. Therefore, for example, when adjustment is performed in the adjustment unit of the lens of the projection optical system, the filler remains in a state sandwiched between the inner surface of the concave portion and the outer surface of the convex portion, and further, with respect to the displacement direction. Since deformation in the orthogonal direction is unlikely to occur, it is possible to prevent the two members from deviating from a predetermined positional relationship. As a result, when performing adjustment in the projection exposure apparatus or the like, it is possible to achieve high-accuracy pattern superposition without lowering the projection accuracy.

According to the projection exposure apparatus of the second aspect, a photochemically inert grease is used as the filler. By using grease which is a viscous material as a filler as described above, grease does not exert a reaction force enough to shift the two members, so even when the two members constituting the casing are relatively moved. High accuracy can be maintained without shifting these relative to a predetermined positional relationship. Moreover, since the inert grease is photochemically inert, it does not undergo a photochemical reaction with the inert gas supplied into the casing, so that the sealing property can be maintained.

According to the projection exposure apparatus of the third aspect, the projection optical system has a plurality of optical elements arranged along the optical axis, a plurality of holding members, and a lens barrel. Are provided between two holding members that move relative to each other. Thus, the adjustment section of the projection optical system and the like can be provided with the seal section having the above-described effects. Therefore, when adjusting the projection optical system,
It is possible to prevent the sealing performance from being impaired and the displacement from occurring.

According to the projection exposure apparatus of the fourth aspect, a gas supply mechanism for supplying an inert gas into the lens barrel of the projection optical system, and the inert gas circulated inside the lens barrel is discharged from the lens barrel. And a gas discharge mechanism. This allows the projection optical system to not only replace the atmosphere in the optical path of the exposure light with the inert gas, but also collect and circulate the inert gas from the lens barrel, and efficiently and efficiently use the inert gas. Can be used for

According to the projection exposure apparatus of the fifth aspect, a gas supply mechanism for supplying an inert gas to a plurality of spaces sandwiched by a plurality of optical elements, a first optical element of a projection optical system, and a There is provided a communication means for communicating the first space between the second optical element which is relatively moved and a gas chamber filled with an inert gas. According to the projection exposure apparatus of the sixth aspect, the gas chamber is configured to be a second space different from the first space among a plurality of spaces. Further, according to the projection exposure apparatus of the seventh aspect, the second space is sandwiched between the third optical element and the second optical element arranged on the opposite side of the first optical element with respect to the second optical element. It is configured to be a closed space. in this way,
Since the first space and a gas chamber such as a second space adjacent to the first space with the second optical element interposed therebetween communicate with each other, the first optical element and the second optical element relatively move and the first space is moved. Even if the volume of one space fluctuates, the first space and the gas chambers such as the second space are kept at the same pressure, and the fluctuation of the pressure of the inert gas in the first space is suppressed. Thus, it is possible to realize high-accuracy pattern superimposition without lowering the projection accuracy in the projection exposure apparatus.

According to the projection exposure apparatus of the eighth aspect, the gas supply mechanism supplies the inert gas to the plurality of spaces through the gas supply holes respectively provided in the plurality of holding members. . Accordingly, if the inert gas is supplied to one space, the inert gas is supplied to the entire plurality of spaces through the gas supply holes through the gas supply holes. The light path atmosphere can be replaced with an inert gas, and generation of ozone due to a photochemical reaction with exposure light can be prevented. Therefore, it is possible to prevent the environment and the light use efficiency (transmittance) from being lowered and prevent the surface of an optical element such as a lens from becoming cloudy, thereby stably exhibiting the performance of the projection exposure apparatus. Can be.

According to the projection exposure apparatus of the ninth aspect, the movable member for holding the second optical element and the filler having a sealing property are provided at the joint between the movable member and the main body of the projection optical system. Thus, the adjustment unit and the like of the projection optical system can have the effect according to any one of the fifth to eighth aspects.

[Brief description of the drawings]

FIG. 1 shows an example of a projection exposure apparatus according to the present invention, and is a view schematically showing a configuration of the projection exposure apparatus.

FIG. 2 is a diagram showing a main part of the projection exposure apparatus,
FIG. 2 is an elevational sectional view showing a projection optical system of the projection exposure apparatus.

FIG. 3 is a view showing another example of the projection exposure apparatus according to the present invention, and is an elevational sectional view showing the projection optical system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 projection exposure apparatus 12 wafer (substrate) 13 reticle (mask) 14 light source 15 illumination optical system 16 light transmission system 17 projection optical system 21 lens (optical element) 21A, 21C lens (first optical element) 21B, 21D lens (first 2 optical element) 21C, 21E lens (third optical element) 22 holding member (movable member) 23 lens barrel (casing) 25 communication hole (communication means, gas supply hole) 35, 45 seal portion (coupling portion) 37, 47 Upper ring (convex portion) 38 Sealing material (filling material) 39 Groove (recessed portion) 50 Supply pipe (gas supply mechanism) 52 Discharge pipe (gas discharge mechanism) S space S1, S3 space (first space) S2, S4 space ( Gas chamber, second space)

Claims (9)

[Claims] 1. A projection exposure apparatus for transferring a pattern of a mask onto a substrate, comprising: an illumination optical system that irradiates the mask with exposure light; and a light source that emits the exposure light and the illumination optical system. At least a part of the light transmission system to be arranged and the projection optical system for projecting the exposure light from the mask onto the substrate are arranged so as to surround the optical path of the exposure light and have an inert gas therein. Is provided, and the casing has a seal portion between two members constituting the casing to prevent the outflow of the inert gas out of the casing. A concave portion formed on one of the member sides;
A projection exposure apparatus comprising: a convex portion formed on the other member side and inserted into the concave portion; and a filler filled between the concave portion and the convex portion and having a sealing property. . 2. The projection exposure apparatus according to claim 1, wherein
A projection exposure apparatus, wherein a photochemically inert grease is used as the filler. 3. The projection exposure apparatus according to claim 1, wherein said projection optical system includes a plurality of optical elements arranged along an optical axis thereof, and a plurality of holding members for holding said plurality of optical elements. And a lens barrel accommodating the plurality of holding members, wherein the seal portion is provided between two of the plurality of holding members that move relative to each other. 4. The projection exposure apparatus according to claim 1, wherein a gas supply mechanism that supplies the inert gas into the lens barrel of the projection optical system, and the gas supply mechanism is circulated inside the lens barrel. And a gas discharging mechanism for discharging the inert gas from the lens barrel. 5. An illumination optical system for irradiating a mask with exposure light, and a projection optical system in which a plurality of optical elements are arranged along an optical axis for projecting the exposure light onto a substrate via the mask. A projection exposure apparatus comprising: a gas supply mechanism for supplying an inert gas to a plurality of spaces sandwiched by the plurality of optical elements; a first optical element of the projection optical system; and a first optical element. A projection exposure apparatus, comprising: communication means for communicating a first space sandwiched between a second optical element which is relatively moved and a gas chamber filled with the inert gas. 6. The projection exposure apparatus according to claim 5, wherein
The projection exposure apparatus according to claim 1, wherein the gas chamber is a second space different from the first space among the plurality of spaces. 7. The projection exposure apparatus according to claim 6, wherein
The second space is a space interposed between a third optical element and the second optical element arranged on the opposite side of the first optical element with respect to the second optical element. Exposure equipment. 8. The projection exposure apparatus according to claim 5, wherein the gas supply mechanism is provided on a plurality of holding members for holding the plurality of optical elements, and the gas supply holes communicate with each other. And supplying the inert gas to each of the plurality of spaces through the projection exposure apparatus. 9. The projection exposure apparatus according to claim 5, wherein a sealing member is provided at a joint between the movable member for holding the second optical element and a main body of the projection optical system. A projection exposure apparatus comprising: