WO2002037545A1

WO2002037545A1 - Exposure method and system

Info

Publication number: WO2002037545A1
Application number: PCT/JP2001/009521
Authority: WO
Inventors: Masato Hatasawa
Original assignee: Nikon Corporation
Priority date: 2000-10-31
Filing date: 2001-10-30
Publication date: 2002-05-10
Also published as: AU2002210978A1; JPWO2002037545A1

Abstract

An exposure method and system capable of a high-precision exposure without compromise in image forming characteristics of a projection optical system even when the atmospheric pressures of airtight chambers in the projection optical system and locations in front and rear thereof vary. A space between the top-most lens (L1) and the lower-most lens component (L8) in the projection optical system (4) is made high in air-tightness, and part of an illuminating optical system, a reticle stage system and a wafer stage system are respectively housed in highly airtight sub-chambers. A pressure gauge (S3) is installed in the projection optical system (4) to measure an atmospheric pressure inside the projection optical system (4). Pressure gauges are installed respectively in respective sub-chambers to measure internal atmospheric pressures in respective sub-chambers. Lenses (L2-L5) are finely moved via drive elements (63A-63D) according to measurement results of pressures in the projection optical system (4) and sub-chambers to thereby adjust the image forming characteristics of the projection optical system (4).

Description

Description Exposure method and apparatus

The present invention relates to a lithography method for manufacturing a device such as a semiconductor device, an imaging device (such as a CCD), a liquid crystal display device, a plasma display device, or a thin-film magnetic head. TECHNICAL FIELD The present invention relates to an exposure method, an exposure apparatus, and a device manufacturing method for transferring an image onto a substrate via a substrate. Background art

A projection exposure apparatus is used to transfer a reticle pattern as a mask via a projection optical system onto a wafer (or a glass plate or the like) coated with a photosensitive material as a substrate. In recent years, with the miniaturization and high density of the projection optical system, further improvement in the resolution of the projection optical system has been demanded, and the exposure beam used in the projection exposure system has been shortened year by year. Have been doing.

In a projection exposure apparatus, it is also required to improve the throughput by increasing the illuminance of an exposure beam. However, when the wavelength of the exposure beam is in the vacuum ultraviolet region of a wavelength of about 200 nm or less, substances such as oxygen, water vapor, and carbon dioxide contained in the atmosphere of the optical path of the exposure beam (hereinafter, referred to as “absorbing substances”). ) Increases the absorption of the exposure beam. In addition, a trace amount of organic substance in the optical path may cause a photochemical reaction by vacuum ultraviolet light to form a cloudy substance, and if the cloudy substance adheres to the optical member, the illuminance of the exposure beam decreases. Are getting bigger and bigger.

Therefore, when vacuum ultraviolet light (especially light with a wavelength of about 180 nm or less) is used as the exposure beam, it is necessary to reach the wafer surface with sufficient illuminance and perform exposure at a practical throughput. is there. To this end, most of the atmosphere on the optical path of the exposure beam is replaced with a gas that allows the exposure beam to pass, that is, a gas (purge gas) such as helium or nitrogen that has a higher transmittance for the exposure beam than the above-mentioned light-absorbing substances. It is desirable to do so. When light having a wavelength of about 200 nm or less is used as an exposure beam in a projection exposure apparatus, the atmosphere of the optical path of the exposure beam is controlled by an exposure beam in order to suppress a decrease in the amount of the exposure beam due to a light absorbing substance on the optical path. Assuming that the gas is replaced by a gas that passes through, for example, inside the projection optical system, it is necessary to reduce the fluctuation amount of the atmospheric pressure in order to stabilize the imaging characteristics. Therefore, the space inside the projection optical system and the airtight room where the reticle is placed in one of the front and rear and the airtight room where the reticle is housed in the other space before and after the reticle are stored. It is desirable to perform the gas replacement independently of each other. However, if gas is replaced independently in the space inside the projection optical system and the space before and after it, a pressure difference occurs between the space inside the projection optical system and the space before and after it. It will be easier. As a result, the imaging characteristics such as distortion of the projection optical system may change due to the pressure difference. In addition, if the pressure difference fluctuates, the imaging characteristics also fluctuate. Therefore, it is difficult to maintain the imaging characteristics in a good state and perform high-precision exposure. In view of the above, the present invention improves the optical characteristics of an optical system disposed on an optical path of an exposure beam, for example, the imaging characteristics of a projection optical system when supplying a gas that transmits the exposure beam to the optical path of the exposure beam. The primary purpose is to be able to maintain a stable state.

Further, the present invention provides an optical system on the optical path of the exposure beam, for example, a space inside the projection optical system, and a space before and after the gas, which supplies the gas that transmits the exposure beam substantially independently of each other. A second object is to be able to maintain good imaging characteristics of the optical system. Disclosure of the invention

The exposure method according to the present invention is directed to an exposure method for exposing an object (W) with an exposure beam via a projection system (4), wherein a plurality of airtight chambers (3, 8, A gas that transmits the exposure beam is supplied to each of the airtight chambers, and the pressure inside at least one of the airtight chambers is measured, and the object is measured based on the measurement result. This is to adjust at least one of the image forming state of the image of the pattern to be exposed to the air and the gas supply condition to at least one of the plurality of hermetic chambers. According to the present invention, for example, as at least one of the plurality of hermetic chambers, for example, measuring the air pressure of the hermetic chamber adjacent to the hermetic chamber that houses a projection system that projects a pattern image onto an object I do. Then, the relationship between the amount of change in the air pressure of the hermetic chamber and the amount of change in the imaging characteristics of the projection system is determined in advance by simulation or experimentally, and based on the measurement result of the air pressure in the adjacent hermetic chamber, Obtain the variation of the imaging characteristics of the projection optical system. As an example, by adjusting the air pressure of the adjacent airtight chamber so as to offset the fluctuation amount of the imaging characteristics of the projection system, the imaging characteristics of the projection system can be maintained in a good state, and the resolution and overlay accuracy can be maintained. Etc. can be kept high.

Further, according to the present invention, as another method, among a plurality of hermetic chambers, as two hermetic chambers adjacent to each other, for example, a projection system having an airtight interior and an hermetic chamber adjacent to the projection system It is also possible to measure the air pressure in each of these two hermetic chambers. レ At this time, the air pressure in the projection system and the air pressure in the adjacent hermetic chamber are determined in advance by simulation or experimentally. The relationship between the atmospheric pressure difference and the amount of variation in the imaging characteristics of the projection system is determined, and the amount of variation in the imaging characteristics is determined based on the measured value of the atmospheric pressure difference and the relationship. Then, for example, by adjusting the imaging characteristics so as to cancel out the fluctuation amount, the imaging characteristics can be maintained in a good state, and the resolution and the overlay accuracy can be maintained at a high level.

Instead of adjusting the imaging characteristics as described above, for example, the gas supply conditions may be adjusted so that the pressure difference is within a predetermined target range. This also allows the imaging characteristics to be maintained in a good state. Furthermore, by combining the adjustment of the imaging characteristics and the adjustment of the supply condition of the gas, the imaging characteristics can be maintained in a better state.

In this case, it is desirable to displace a predetermined optical member inside the projection system in order to adjust the imaging characteristics (optical characteristics). When the optical member is displaced in this manner, control is easy because the pressure inside the projection system hardly changes. Similarly, the imaging characteristics can be easily controlled by changing the wavelength of the exposure beam. Further, as another adjustment method, the posture (position or inclination) of the object may be adjusted with respect to the imaging plane of the projection system.

Also, the exposure beam is used as the object through the mask (R) and the projection system. When the substrate is exposed, the plurality of hermetic chambers are, for example, a first chamber (3) that covers at least a part of the illumination system of the exposure beam, and a second chamber (8) that houses the mask. A third chamber for covering at least a part of the optical members of the projection system; and a fourth chamber for accommodating the substrate. At this time, even if a gas that transmits the exposure beam is supplied from the first chamber to the fourth chamber substantially independently of each other, by adjusting the imaging characteristics according to the present invention, the imaging characteristics can be reduced. It can be maintained in good condition.

Further, information relating to at least one atmospheric pressure of the third room and at least one of the second room (8) or the fourth room (6) adjacent to the third room is detected, and according to the detected information, At least one of the optical characteristics of the optical system and the gas supply conditions may be adjusted. In this case, as an example, the second chamber is set to at least one of a pair of spaces sandwiching the optical system. At this time, the optical characteristics of the projection system can be adjusted based on the measurement result of the atmospheric pressure in the second chamber.

The optical system is, for example, an imaging system (4) for projecting a pattern on the first surface onto the second surface, and the second chamber includes at least one of the first surface and the second surface. It is included. When the optical system is a projection system, the imaging characteristics can be maintained in a good state, so that the resolution and the overlay accuracy are improved.

Next, an exposure apparatus according to the present invention is an exposure apparatus that exposes an object (W) with an exposure beam via an optical system (4), wherein the plurality of hermetic chambers (3, 3) provided along the optical path of the exposure beam. 8, 4, 6), a gas supply mechanism (13) for supplying a gas that transmits the exposure beam into the plurality of hermetic chambers, and an air pressure inside at least one of the plurality of hermetic chambers. Barometer (S1 to S4) that measures the air pressure, based on the measurement results of the barometer, the imaging characteristics of the projection system, and the gas for at least one of the multiple hermetic chambers. And a control mechanism (13, 63A to 63D, 64, 65) for controlling at least one of the supply conditions. According to the present invention, the exposure method of the present invention can be performed, and the imaging characteristics of the projection system can be maintained in a good state.

In this case, the optical system includes, for example, a projection optical system that projects an image of a pattern formed on a mask onto the object. The optical system is another example. And an illumination optical system for illuminating the mask on which the pattern is formed. In addition, a film-shaped coating member (or coating member) having flexibility so as to cover a space communicating with a space between at least two adjacent airtight chambers (8, 4) among the plurality of airtight chambers (8, 4). It is desirable to provide 50). This coating member (or coating member) can prevent outside air from entering from the boundary between adjacent airtight chambers, and maintain high illuminance of the exposure beam.

When the optical system has an illumination optical system for illuminating the mask on which the pattern is formed with the exposure beam and a projection optical system for projecting an image of the pattern onto the object, a plurality of airtight chambers are provided. As an example, a first chamber (3) that covers at least a part of the illumination optical system, a second chamber (8) that houses the mask, and at least a part of the optical members of the projection optical system It has a third chamber (4) for covering and a fourth chamber (6) for accommodating the substrate.

Further, it relates to a pressure difference between a third chamber in which at least a part of the projection optical system is arranged among the plurality of hermetic chambers and at least one of the second chamber and the fourth chamber adjacent to the third chamber. A detection device (S1 to S4) for detecting information, and the control mechanism determines the imaging characteristics of the projection optical system and the gas supply conditions based on the information detected by the detection device. It is desirable to adjust at least one.

Further, the device manufacturing method according to the present invention includes a step of transferring a device pattern (R) onto a workpiece (W) using the exposure method or the exposure apparatus of the present invention. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic configuration diagram with a part cut away showing a projection exposure apparatus according to an example of an embodiment of the present invention. FIG. 2 is a sectional view showing the projection optical system 4 of FIG. 1 and a mechanism around the projection optical system. FIG. 3 is a diagram showing another example of the projection optical system. FIG. 4 is an explanatory diagram of an example of a manufacturing process when a semiconductor device is manufactured using the projection exposure apparatus according to the embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the present invention is applied to a step-and-scan projection exposure apparatus using vacuum ultraviolet light as an exposure beam.

FIG. 1 is a schematic configuration diagram showing the projection exposure apparatus of this embodiment. In FIG. 1, the projection exposure apparatus of this embodiment uses an F ₂ laser light source (wavelength: 157 nm) as an exposure light source. Vacuum ultraviolet light such as Ar F excimer laser light source (wavelength 193 nm), Kr ₂ laser light source (wavelength 146 nm), harmonic generator of YAG laser, harmonic generator of semiconductor laser, etc. In this case, a light source that emits light with a wavelength of 20 Onm or less can be used. However, even when a KrF excimer laser light source (wavelength: 248 nm) or a mercury lamp (i-ray, etc.) is used as the exposure light source, the present invention can be applied when it is desired to particularly increase the transmittance of the exposure beam. .

When vacuum ultraviolet light is used as the exposure beam as in this example, the vacuum ultraviolet light is generated from oxygen, water vapor, hydrocarbon-based gas (carbon dioxide, etc.), organic substances, and octogen that are present in the normal atmosphere. In order to prevent the exposure beam from attenuating, it is desirable that the concentration of these light absorbing substances (impurities) be suppressed to, for example, about 10 to 100 ppm or less. Further, the allowable value (upper limit value) of the impurity concentration may be made different in at least one of a plurality of hermetic chambers (corresponding to the projection optical system 4 and sub-chambers 3, 6, and 8 described later). Therefore, in this example, the gas on the optical path of the exposure beam is converted into a gas through which the exposure beam passes, that is, nitrogen (N ₂ ) gas or helium (He), neon (Ne), argon (A r), krypton (Kr ), Xenon (Xe) or radon (Rn), a gas that is chemically stable with a high transmittance to exposure beams and a highly light-absorbing substance (hereinafter referred to as “purge gas”). ").

Nitrogen gas is a gas through which the exposure beam is transmitted even for light with a wavelength of up to about 150 nm even in the vacuum ultraviolet region, that is, for light with a wavelength of about 150 nm or less that can be used as a purge gas. It almost acts as a light absorbing substance. Therefore, it is desirable to use a rare gas as the purge gas for the exposure beam whose wavelength is about 150 nm or less. Among rare gases, helium gas is desirable from the viewpoint of stability of refractive index and high thermal conductivity, but helium is expensive. Therefore, when importance is attached to the operation cost and the like, another rare gas may be used. Further, for example, in the case of using A r F excimer laser as an exposure beam (wavelength 1 9 3 nm), the absorption by oxygen is not too much as compared with the case of using F _2, single The exposure apparatus Helium gas or nitrogen is supplied to the interior space of the projection optical system in order to reduce the operating cost of the projector. For example, nitrogen gas or dry air (dry air (dry air) from which organic substances are highly removed is supplied to the interior space of the illumination optical system. ) May be supplied. Incidentally, as the exposure beam, in the case of using the F ₂ laser, the optical path space for the exposure bi one beam extending from the light source to the substrate needs to be replaced with a purge gas. In that case, helium gas may be supplied to the internal space of the projection optical system, and nitrogen may be supplied to the other space, that is, the internal space of the illumination optical system. Further, as the purge gas, not only a single kind of gas may be supplied, but also a mixed gas in which nitrogen and helium are mixed at a predetermined ratio may be supplied.

In this embodiment, helium gas is used as a purge gas for the stability of the refractive index (stability of the imaging characteristics) and high thermal conductivity (high cooling effect). Therefore, for example, in the machine room below the floor where the projection exposure apparatus of this example is installed, high-purity purge gas is supplied to the projection exposure apparatus and a plurality of hermetic chambers in the equipment attached to the projection exposure apparatus. A supply / exhaust mechanism 13 is installed to collect and reuse the gas flowing through the airtight chamber. The supply / exhaust mechanism 13 may be configured so that the gas exhausted from each hermetic chamber is collected, but the collected gas is not reused. Further, a configuration may be adopted in which gas disposed from each airtight chamber is exhausted via factory piping.

Hereinafter, the configuration of the projection exposure apparatus of this example will be described in detail. The main body of the projection exposure apparatus of this example is mounted on a base member 2C, and has a substantially gate-shaped first frame 2A including four or three legs (columns) on the base member 2C. Is installed. The illumination optical system of the present example is composed of an exposure light source and optical members such as an optical integrator (uniformizer or homogenizer). Most of the optical members except for the exposure light source are housed in a highly airtight box-shaped first sub-chamber 3, and the first sub-chamber 3 is installed on the upper part of the first frame 2 </ b> A. Exposure consisting of pulsed laser light with a wavelength of 157 nm emitted from an exposure light source (not shown) of the illumination optical system The light (exposure beam) illuminates the pattern area on the pattern surface (lower surface) of reticle R as a mask. The exposure beam transmitted through the reticle R passes the projection of the reticle R onto the wafer (wafer) W as the substrate via the projection optical system 4 as the projection system. (Z4, 1Z5, etc.). The wafer W is, for example, a semiconductor such as silicon or a disk-shaped substrate such as SOI (silicon on insulator), on which a photoresist is applied. The wafer W in this example corresponds to the object to be exposed according to the present invention.

As shown in FIG. 2, a straight-tube type catadioptric system is used as the projection optical system 4 (details will be described later). A system or the like can be used. When exposure light having a wavelength of 157 nm is used as in this example, a material that can obtain a high transmittance as a material of the refraction member in the illumination optical system and the projection optical system 4 is fluorite (C) a F ₂ ), synthetic quartz doped with predetermined impurities, and magnesium fluoride (MgF ₂ ). In the following, the Z axis is taken parallel to the optical axis of the projection optical system 4, the X axis is taken parallel to the plane of Fig. 1 in a plane perpendicular to the Z axis, and the Y axis is taken perpendicular to the plane of Fig. 1. I do. In this case, the illuminated area on the reticle: the slit shape is elongated in the X direction, and the reticle R and the wafer W are exposed in the Y direction during exposure.

First, reticle R is held on reticle stage 7b via reticle holder 7a. Then, the reticle stage 7b continuously moves in the Y direction (scanning direction) on the reticle base 7c in a linear mode overnight, and finely adjusts the position of the reticle R in the XY plane. When the reticle stage 7b moves in the Y direction, the reticle base 7c moves on the base member 21 in the direction opposite to the direction of movement of the reticle stage 7b so as to satisfy the law of conservation of momentum. The generation of vibration when the stage 7b moves is suppressed. In addition, the base member 21 is mounted on four (or three, etc.) support plates (only two positions are shown in FIG. 1) in the middle of the first frame 2A. Supported via A, 23B. The anti-vibration members 23A and 23B are active type anti-vibration devices that combine an air damper (or a hydraulic damper or the like) with an electromagnetic actuator such as a voice coil motor. Reticle stage system RS from reticle holder 7a, reticle stage 7b, reticle base 7c, etc. The reticle stage system RST is housed in a highly airtight box-shaped second subchannel 8 (reticle chamber).

Inside the first column 2A on the upper surface of the base member 2C, there are four (or even three) vibration damping members 24A and 24B (only two in Fig. 1). A substantially gate-shaped second frame 2E is installed through the, and the projection optical system 4 is placed in a U-shaped opening in the center of the upper plate of the second frame 2E. I have. The anti-vibration members 24A and 24B are active type anti-vibration devices similar to the anti-vibration members 23A and 23B. Then, an interferometer support member 28 is installed on the upper plate of the second frame 2E, and the upper end of the interferometer support member 28 passes through an opening provided in the base member 21 through the second sub-chamber 8. The laser interferometer (reticle interferometer) is installed at the upper end. The gap between the opening of the base member 21 and the interferometer support member 28 is, for example, a bullet that has been chemically cleaned (such as coating a surface with a fluorine-based resin). Sealed with a resin having properties.

The position of the reticle stage 7b (reticle R) in the X and Y directions by the reticle interferometer and the movable mirror 19 installed on the reticle stage 7b, and, if necessary, the X-axis and Y-axis. The rotation angle around the Z axis is measured, and the position and the moving speed of the reticle stage 7b are controlled by a stage control system (not shown) based on these measured values. A reticle alignment support frame 12 is installed on the base member 21, and a reticle alignment microscope (not shown) is installed above the reticle stage 7 b of the support frame 12. Have been.

On the other hand, the wafer W is held on the sample table 5a via a wafer holder (not shown). The sample stage 5a is fixed on the XY stage 5b. The XY stage 5b continuously moves the sample stage 5a (wafer W) on the wafer base 22 in the Y direction, and moves the sample stage 5a in the X direction and the Y direction as needed. The sample stage 5a controls the focus position (position in the Z direction) of the wafer W, and the tilt angle around the X axis and the Y axis. The XY stage 5b is driven by a drive unit (not shown) of, for example, a linear motor type so as to satisfy a movement amount conservation rule, and the generation of vibration when driving the XY stage 5b is suppressed. In addition, the wafer base 22 is connected via four (or three, etc.) anti-vibration members 25 A, 25 B (only two locations appear in FIG. 1). The vibration isolating members 25A and 25B are mounted on the base member 2C, and are active vibration isolating devices similar to the vibration isolating members 23A and 23B. A wafer stage system WST is composed of the sample stage 5a, the XY stage 5b, and the like, and the wafer stage system WST is housed in a highly airtight box-shaped third sub-chamber 6 (wafer chamber).

Also, the lower end of the interferometer support member 28 fixed to the second frame 2E is inserted into the third sub-chamber 6, and the lower end of the interferometer support member 28 is fixed to a wafer interferometer composed of a laser interferometer. The side of the platform 5a is machined into a movable mirror. Then, the position of the sample stage 5a (wafer W) in the X and Y directions and the rotation angles around the X, Y, and Z axes are measured by the wafer interferometer and the moving mirror of the sample stage 5a. The operation of the XY stage 5b is controlled by a stage control system (not shown) based on these measured values. Also, for example, an oblique incidence type multi-point optical autofocus sensor (AF sensor) 10 is fixed to the bottom surface of the upper plate of the second frame 2E. Based on the information on the focus positions at a plurality of measurement points on the wafer W measured by the method, the sample stage 5a is focused on the wafer W by the auto focus method and the auto repeller method, and the X axis and the Y axis. Controls the angle of inclination around. Thus, the surface of the wafer W is continuously focused on the image plane of the projection optical system 4 during the exposure.

In addition, a wafer alignment system 14 of an off-axis imaging system for performing the alignment of the wafer W is also fixed to the second frame 2E. Further, in the lateral direction of the first frame 2A, a reticle opening system RLD for transferring a reticle R to and from the reticle stage system RST, and a wafer W to and from the wafer stage system WST. The wafer loader system WLD is housed in the column • Column 17 is installed. The transfer port for transferring the reticle and the transfer port for transferring the wafer in this interface column 17 are gates to minimize the opening of the reticle stage system RST and wafer stage system WST to the outside air. Valves 15 and 16 are provided, respectively.

Then, at the time of scanning exposure, when the exposure of one shot area on the wafer W is completed, the next shot area is moved to the scanning start position by the step movement of the XY stage 5b. After that, the reticle stage 7 b and the XY stage 5 b on the wafer side Synchronous scanning in the Y direction is performed using the projection magnification j3 of the projection optical system 4 as the speed ratio, that is, scanning the reticle R and the corresponding shot area on the wafer W while maintaining the imaging relationship. Repeated in an AND-scan manner. Thus, the pattern image of the reticle R is sequentially transferred to each shot area on the wafer W. The projection exposure apparatus of this embodiment is provided with a supply / exhaust mechanism 13 for replacing (purging) gas in the space including the optical path of the exposure light with gas (purge gas) through which the exposure light passes. . A part of the illumination optical system, the reticle stage system RST, and the wafer stage system WST are housed in highly airtight sub-chambers 3, 8, and 6 as airtight chambers, respectively. The space between this optical member and the lowermost optical member is a highly airtight space (this also corresponds to an “airtight room”). A high-purity purge gas is supplied into the sub-chambers 3, 8, and 6 by a supply / exhaust mechanism 13, and a high-purity purge gas is also supplied to a highly airtight space in the projection optical system 4. (Details below). Further, inside the sub-chambers 3 and 8, the projection optical system 4 and the sub-champer 6, pressure gauges S1 to S4 for measuring the pressure of the gas inside are respectively installed. The air pressure measured in steps S4 to S4 is supplied to the environmental information measurement system 47 in FIG. The pressure gauge S3 may be arranged in a space between the film cover 50 and the projection optical system 4.

Further, in FIG. 1, the boundary between the first sub-chamber 3 and the upper portion of the second sub-chamber 8 and the boundary between the bottom surface of the base member 21 and the upper surface of the second frame 2E (that is, the second sub-chamber 2) And the boundary between the bottom surface of the upper plate of the second frame 2E and the upper surface of the third sub-chamber 6 isolate the internal space from the outside. As a result, cylindrical film-like covers 1A, 50, and 1D are provided as flexible film-like covering members (or covering members). That is, the film cover 50 functions as a covering member that covers a part of the projection optical system 4. Also, between the sub-chambers 8 and 6 and the gate valves 15 and 16 of the interface column 17, flexible cylindrical film covers 18 A and 18 B are provided, respectively. I have. Flanges made of metal such as aluminum or ceramics are provided at both ends of the film-shaped force pars 1A, 1D, 50, 18A and 18B, respectively. Of each frame It is screwed to the installation surface, for example, via an o-ring so that no outside air is mixed. In FIG. 1, the interferometer support member 28 is disposed outside the film cover 50.However, in order to prevent outside air from entering through a gap around the interferometer support member 28, the interferometer support member 28 is provided. It is desirable to arrange the member 28 inside the film-like cover 50.

The film-like covers 1A, 1D, 50, 18A, and 18B can be referred to as a flexible shielding member having high flexibility or a bellows having extremely low rigidity. Since these film-shaped covers 1A, 1D, 50, 18A, and 18B substantially seal their boundaries, the optical path of the exposure light is almost completely sealed. For this reason, there is almost no mixing of the gas containing the light absorbing substance from the outside onto the optical path of the exposure light, and the attenuation of the exposure light can be extremely suppressed.

Here, the film-shaped cover 50 of this example will be representatively described.

The film-like cover 50 is made of a polyethylene (one (CH ₂ CH ₂ ) n one) protective film with good elasticity on the outer surface of a film material made of ethylene vinyl alcoholic resin (EVOH resin) via an adhesive. The film is formed by coating a stabilizing film made of aluminum (A1) on the inner surface of the film material by vapor deposition or the like. Ethylene vinyl alcohol resin (EVOH resin) is extremely excellent in gas barrier properties (gas barrier properties). As EVOH resin, for example, Kuraray Co., Ltd. “EVAL” (Kuraray trademark or registered trademark) "Etc. can be used. Further, it is desirable that the stabilizing film is formed of a substance which does not generate degassing or which has extremely low degassing.

That is, the film-like cover 50 is basically formed by laminating (multilayer processing) a protective film having good elasticity and a film material having good gas barrier properties, and has a stabilized film with very little degassing on its inner surface. The overall thickness of the film-shaped cover 50 is about 0.1 mm. Further, in order to completely seal the film-shaped cover 50 in a closed state in a cylindrical shape, the same material as the protective film is applied via an adhesive so as to cover the joint from the outside.

In this case, the protective film has good stretchability, but has poor gas barrier properties, is easily degassed, and has a drawback that metal and the like are not easily adhered to the inner surface. Therefore, In this example, a film material which has excellent gas barrier properties, can prevent inflow of outside air and outflow of purge gas, and is easily adhered to metal or the like is formed on the inner surface of the protective film, and a stabilizing film is formed on the inner surface. Is formed. Due to this stabilizing film, degassing generated from the adhesive, protective film, heat seal, and the like used when forming the film cover 50 is generated inside the film cover 50, that is, on the optical path of the exposure light. To prevent intrusion. In addition, by coating the inner surface with a stabilizing film, the barrier property against gas is further improved.

As described above, the film-shaped cover 50 of this example has a large flexibility such as a film material, that is, is formed of a material having extremely low rigidity and excellent gas barrier properties. In addition to obtaining the same gas barrier properties as compared to the case of using a compression mechanism, almost no vibration is transmitted between the base member 21 and the second frame 2E in Fig. 1. Has become. The other film-shaped covers 1A, ID, 18A, and 18B are also formed in the same manner as the film-shaped cover 50, so that vibration is not easily transmitted between adjacent airtight chambers. I have.

The material of the film material used to form the film cover 50 is not limited to the ethylene-vinyl-alcohol resin of this example, but may be polyamide (polya mide), polyimide (polyimide), or polyester (polyester). Any material may be used as long as it has good barrier properties against the air and has flexibility such as). Further, the material coated as a protective film on the inner surface of the film-shaped cover 50 is not limited to aluminum of this example, but may be an exposure light such as vacuum ultraviolet light such as other metals or inorganic materials such as ceramics. Any material may be used as long as it has a low reactivity with respect to and a small amount of degassing. Further, as the protective film, then _c may be used and polypropylene in addition to polyethylene, supply and exhaust mechanism 1 3 of the present example, storage section for storing recovery unit for recovering the purge gas, high purity par purge gas , And an air supply unit that supplies the purge gas to the outside with its temperature adjusted.The high-purity purge gas is supplied into the sub-chambers 3, 8, 6 and the projection optical system 4 via the air supply pipe 26, respectively. The gas is supplied at a pressure slightly higher than the pressure (positive pressure), and the purge gas containing impurities flowing through the sub-chambers 3, 8, 6 and the projection optical system 4 is supplied to the exhaust pipe 2 with the valve V. Collected via 7 respectively. At this time, the air supply pipe 26 and the inside of the projection optical system 4 are connected by a branched air supply pipe 48. The inside of the projection optical system 4 and the exhaust pipe 27 are connected by a branched exhaust pipe 49. In this example, the space inside the film-shaped cover 50 is also filled with a part of the purge gas supplied into the sub-chamber.

Further, the supply / exhaust mechanism 13 separates the purge gas from the collected gas and squeezes the separated purge gas to a high pressure or liquefies and temporarily accumulates the purge gas. As an example, impurity sensors for measuring the concentration of, for example, oxygen as a light-absorbing substance are installed inside the subchambers 3, 8, 6 and the projection optical system 4, and the light-absorbing substance detected by these impurity sensors is detected. If the concentration exceeds a specified tolerance, the recovery of gas via exhaust pipe 27 and the replenishment of high-purity purge gas via supply pipe 26 will result in an almost constant pressure (slightly positive pressure). ) Is performed by a gas flow control method in which a gas is supplied. For this reason, the same pressure is always applied to the film covers 1 A to 18 B, 50 even if the extremely flexible film covers 1 A to 18 B, 50 are used. Thus, no excessive force acts on these film covers 1A to 18B, 50.

When supplying the purge gas, the supply / exhaust mechanism 13 adjusts the temperature, humidity, pressure, etc. of the supplied purge gas, and also removes dust from the dust filter such as a HEPA filter (high efficiency particulate air-Π Iter). The above-mentioned light-absorbing substances and the like are removed from the purge gas by a filter such as a chemical filter for removing the above-mentioned light-absorbing substances including a trace amount of organic substances. The substances to be removed here are substances that adhere to the optical elements used in the projection exposure apparatus and cause fogging, or are suspended in the optical path of the exposure light and used for the illumination optical system and the projection optical system. Substances that change the transmittance (illuminance) or the illuminance distribution of the wafer, or substances that adhere to the surface of the wafer W (photoresist) and deform the pattern image after the development process.

As described above, by replacing the atmosphere on the optical path of the exposure light with the high-purity purge gas, the transmittance for the exposure light is maintained high, and the illuminance of the exposure light incident on the wafer W is increased. Exposure time for each shot area can be reduced, and throughput can be improved. Also, in this example, the optical path of the measurement beam of the optical measurement device such as the reticle interferometer, the wafer interferometer, and the autofocus sensor 10 provided on the interferometer support member 28 is set in the atmosphere of the purge gas. I have. By this, The occurrence of measurement errors due to the fluctuation of gas on the optical path of the measurement beam of these optical measuring instruments can be suppressed.

Next, the projection optical system 4 of the present example will be described in detail with reference to FIG.

FIG. 2 is a sectional view showing the projection optical system 4 of FIG. 1 and a mechanism around the projection optical system. In FIG. 2, the projection optical system 4 of the present embodiment forms a primary image (intermediate image) of the pattern of the reticle R. First imaging optical system for forming a second image for forming a secondary image of a reticle pattern on a wafer W as a photosensitive substrate at a predetermined reduction magnification based on light from the primary image. And an optical system. The first imaging optical system is configured by arranging, in order from the reticle side, a first lens group having a positive refractive power, an aperture stop AS, and a second lens group having a positive refractive power. The first lens group includes, in order from the reticle side, a positive meniscus lens L1 having an aspheric convex surface facing the reticle side, and a positive meniscus lens L2 having an aspheric convex surface facing the reticle side. And a positive meniscus lens L3 having an aspheric concave surface facing the e-side. A circular light-blocking member PF for blocking the zero-order light is disposed near the arrangement surface of the aperture stop AS.

The second lens group includes, in order from the reticle side, a biconcave lens L having a reticle-side surface formed into an aspherical shape and a biconvex lens having a reticle-side surface formed into an aspherical shape. L5, a positive meniscus lens L6 with the aspherical convex surface facing the wafer side, and a positive meniscus lens L7 with the aspherical concave surface facing the wafer side. .

On the other hand, the second imaging optical system includes, in order from the reticle side, a primary mirror Ml having a surface reflecting surface with a concave surface facing the wafer side and having an opening at the center, a lens component L8, and a lens component L8. A secondary mirror M2 provided on the wafer-side surface of the component L8 and having a reflective surface having an opening in the center. In this case, all optical elements (refractive member, reflective member) constituting the projection optical system 4 are arranged along a single optical axis AX. Thus, in this example, the exposure light IL from the reticle R pattern forms a primary image (intermediate image) of the reticle pattern via the first imaging optical system, and the light from the primary image passes through the primary mirror M The light is reflected by the secondary mirror M2 through the central opening of 1 and the lens component L8. Then, the light reflected by the secondary mirror M2 passes through the lens component L8 and is reflected by the primary mirror Ml. The reflected light forms a secondary image of the reticle pattern at a reduced magnification on the surface of the wafer W through the lens component L8 and the central opening of the secondary mirror M2. In the example of FIG. 2, the imaging magnification i31 of the first imaging optical system is approximately 0.62, and the imaging magnification ^ 2 of the second imaging optical system is approximately 0.4. The projection magnification / 3 is 0.25 (1Z4 times).

In this example, fluorite (a crystal of G a F ₂ ) is used for all refractive optical members (lens components) constituting the projection optical system 4. The oscillation center wavelength of F ₂ laser light as the exposure light IL is 157. 6 nm, with the wavelength width chromatic aberration for light of 157. 6 nm ± 10 pm is corrected, spherical aberration, astigmatism Various aberrations such as aberration and distortion are also corrected well. The detailed lens data of the projection optical system 4 in FIG. 2 is disclosed in, for example, International Publication (W0) 00/39623. Further, as the catadioptric system, another optical system disclosed in WO 00/39623 can also be used. As the projection optical system 4, for example, a catadioptric optical system whose optical axis is bent in a V-shape may be used.

The lens barrel of the projection optical system 4 of the present embodiment is configured by stacking four divided lens barrels 57 to 60 in close contact with each other along the optical axis AX. That is, the lenses L6 and L7, the primary mirror Ml, and the secondary mirror M2 (lens component L8) are held inside the first split lens barrel 57 via the lens frames, respectively. It is placed via a flange in the U-shaped opening of 2E and fixed with Porto. A second split barrel 58 is placed on the split barrel 57. The split barrels 57 and 58 fasten, for example, three locations of a pair of opposed flange portions F with a port 61 in the optical axis direction. As a result, they are connected in close contact with each other. The same applies to the connection of other split lens barrels. Note that the cross-sectional view of the projection optical system 4 in FIG. 2 is a vertical cross-sectional view at an opening angle of 120 ° about the optical axis AX. The lenses L5 and L4 are held in the split lens barrel 58 via three driving elements 63A and 63B that can expand and contract in the optical axis direction.

Further, a third divided lens barrel 59 is mounted on and coupled to the divided lens barrel 58, and is provided in the divided lens barrel 59 via three drive elements 63C and 63D which can expand and contract in the optical axis direction.

3 and L 2 are held. And the fourth split on split lens barrel 59 The lens barrel 60 is mounted and connected, and a lens L1 is held at the upper end in the split lens barrel 60 via a lens frame. As the driving elements 63A to 63D, an electric micro-mechanical element, a piezoelectric element (such as a piezo element), or a magnetostrictive element can be used. The expansion and contraction of the driving elements 63A and 63B are controlled by a driver 64 fixed to the outer surface of the divided lens barrel 58, and the expansion and contraction of the driving elements 63C and 63D The operation of the dryinos 64 and 65 is controlled by an imaging characteristic control system 46 equipped with a combination. At this time, each of the driving elements 63A to 63D has a built-in sensor for detecting the amount of expansion and contraction, such as a one-way encoder, a capacitive or optical gap sensor, and the like. , 65 control the driving amounts of the corresponding driving elements 63 A to 63 D while feeding back the detection results of those sensors. The drive elements 63 A to 63 D and the drynos 64 and 65 correspond to a control mechanism for controlling the imaging characteristics of the present invention, and a film is formed so as to cover the control mechanism and the projection optical system 4. 50 covers are installed. In this example, by driving the driving elements 63A to 63D, the four lenses L2 to L5 can be finely moved in the optical axis AX direction, and the lenses L2 to L5 can be moved. Each is configured to be tiltable around two axes orthogonal to each other in a plane perpendicular to the optical axis AX. By driving the four lenses L2 to L5 in this manner, the optical characteristics of the projection optical system 4, for example, the imaging characteristics such as projection magnification, distortion, spherical aberration, and coma aberration can be controlled within a predetermined range. Can be controlled. In FIG. 2, a signal cable for transmitting control information from the imaging characteristic control system 46 is connected to a connector 66 B on the outer surface of the convex portion 2Ea on the upper surface of the second frame 2E. It is connected to the drivers 64 and 65 via the signal cable part 67 inside the part 2Ea and the connector 66A on the inner surface of the convex part 2Ea. In this case, the connectors 66A and 66B have a highly airtight structure (a so-called vacuum joint) so that gas does not flow, and the outside air is projected through the signal cable section 67 to the projection optical system. It is configured so that it does not enter around 4.

In the projection optical system 4 of this example, the lens frame of the uppermost lens L1 and the lens frame of the lowermost lens component L8 (secondary mirror M2) have a closed structure, and other lenses and The lens frame of the primary mirror M 1 has a large number of A small opening is formed. The air supply pipe 48 for the purge gas is inserted into the side of the uppermost split lens barrel 60 (the bottom side of the lens L 1), and the exhaust pipe 49 is connected to the lowermost split lens barrel 57. The purge gas, which is inserted into the side surface (the upper surface side of the lens component L8) and supplied from the air supply pipe 48 to the inside of the projection optical system 4, flows around the lenses L1 to L7 and the primary mirror Ml. It is exhausted from the exhaust pipe 49. As a result, the purity of the purge gas inside the projection optical system 4 is kept high.

Furthermore, for example, the inner surfaces of the split lens barrels 57 to 60 of the projection optical system 4 are coated with, for example, a fluorine-based resin, or a hard film (such as a ceramic film or a stainless steel film) that is less degassed by plasma spraying. ) Or electrolytic polishing to perform chemical clean treatment. In addition, as a material of the lens barrel itself, a chemical-clean material such as stainless steel or Teflon may be used.

By the way, the imaging characteristic control system 46 of the projection optical system 4 of the present example includes the pressure gauges S 1 to S 4 ( An environment information measurement system 47 that samples measurement data from a thermometer and a hygrometer (not shown) around the projection optical system 4 and the projection optical system 4 is connected and supplied to the environment information measurement system 47. The measured values of the pressure gauges S1 to S4 and the measured values of temperature and humidity are supplied to the imaging characteristic control system 46. Further, the pressure of the gas outside the film cover 150 on the side surface of the projection optical system 4 (which can be regarded as almost atmospheric pressure) is measured by the barometer S5, and the measured value (atmospheric pressure) Is also supplied to the imaging characteristic control system 46 via the environmental information measurement system 47. Further, information on the integrated energy of the exposure light IL that has passed through the projection optical system 4 is also supplied to the imaging characteristic control system 46. As an example, the integrated energy information is obtained by detecting the luminous flux branched from the exposure light with an integral sensor as a photoelectric detector in the illumination optical system in the sub-chamber 3 in FIG. 1 and integrating the detection signal. Can be obtained by:

In this case, it is conventionally known that the imaging characteristics of the projection optical system 4 fluctuate due to the fluctuation of the atmospheric pressure and the integrated energy passing through the projection optical system 4. The relationship between the value of the atmospheric pressure and the accumulated energy and the amount of change in the imaging characteristics (hereinafter referred to as the “first relationship”), which is obtained experimentally in advance, is stored in the storage unit of the function or the te. —Remembered as Bull. Based on the first relationship and the measured values of the atmospheric pressure and the integrated energy, the imaging characteristic control system 46 predicts the fluctuation amount of the imaging characteristic. Then, based on the predicted fluctuation amount, the imaging characteristic control system 46 drives the corresponding lenses L2 to L5 via the drivers 64 and 65, and the fluctuation amounts described above are canceled. Adjust the imaging characteristics of the projection optical system so that

Further, according to the inventor of the present application, the fluctuation amount of the imaging characteristics is represented by the pressure as the pressure inside the projection optical system 4 (measured value of the pressure gauge S3) and the pressure in the airtight chamber before and after the projection optical system 4. It was confirmed that the pressure also changed depending on the pressure inside the subchambers 3, 8, and 6 (measured values of the pressure gauges S1, S2, and S4). This is thought to be because the refractive index of the gas in each hermetic chamber changes slightly due to the change in the atmospheric pressure inside each hermetic chamber, and the optical path of the exposure light IL also slightly changes. Therefore, there is a certain degree of reproducibility between the values of the atmospheric pressure and the amount of change in the imaging characteristics. Therefore, in this example, the relationship between the measured values of the pressure gauges S1 to S4 and the amount of change in the imaging characteristics (hereinafter referred to as “second relationship”) is obtained in advance by experiment or simulation, and a predetermined function Alternatively, it is stored in the storage unit in the imaging characteristic control system 46 as a table.

Then, when the imaging characteristic control system 46 predicts the variation of the imaging characteristic based on the first relationship, the measurement values of the pressure gauges S1 to S4 and the second relationship are obtained. To correct the variation of the imaging characteristics. Also, even when there is no change in the atmospheric pressure, if the measured values of the pressure gauges S1 to S4 change, the imaging characteristic control system 46 will determine the imaging characteristics based on the second relationship. Is calculated. Then, the imaging characteristic control system 46 drives the corresponding lenses L2 to L5 via the drivers 64 and 65 so as to cancel the finally obtained fluctuation amount of the imaging characteristic, and Adjust the imaging characteristics of the optical system 4. That is, in this embodiment, the value of the atmospheric pressure inside the projection optical system 4 and the sub-chambers 3, 8, and 6 is added as an offset to the relationship between the value of the atmospheric pressure, the accumulated energy, and the amount of change in the imaging characteristics. This is a configuration for calculating the amount of change in the imaging characteristics of the projection optical system. As a result, even if, for example, the balance of the flow rate of the purge gas changes slightly during exposure, and the pressure inside the projection optical system 4 and the airtight chamber before and after it changes, the imaging of the projection optical system 4 can be performed. High-precision exposure can be performed while maintaining the characteristics in a desired state. That is, the pattern image of reticle R can be transferred onto wafer W with high resolution and line width control accuracy. In addition, high overlay accuracy can be obtained with overlay exposure.

Note that it is not always necessary to measure the pressure in all of the sub-chambers 3, 8, and 6. For example, only the pressure in at least one of the sub-chamber 8 (reticle chamber) or the sub-chamber 6 (wafer chamber) is typically measured. May be. In this case, the relationship between at least one of the measurement value of the pressure gauge S2 or the measurement value of the pressure gauge S4 and the variation amount of the imaging characteristic of the projection optical system is stored in the storage unit as a second relationship. It is good. Then, the imaging characteristic control system 46 predicts at least one of the measured value of the pressure gauge S2 or the measured value of the pressure gauge S4 when predicting the variation amount of the imaging characteristic based on the first relationship, What is necessary is just to correct the fluctuation amount of the imaging characteristic using the second relation. Further, an average value of the air pressures of the reticle chamber and the wafer chamber may be used as the air pressure of the airtight chambers before and after the projection optical system 4, and the imaging characteristics of the projection optical system 4 may be adjusted using the average value. .

Further, in the above embodiment, the imaging characteristic of the projection optical system 4 is adjusted. In addition, or in addition, at least a part of an illumination optical system (illumination system) that illuminates the reticle R with exposure light, for example. The optical characteristics (telecentricity, uneven illuminance, etc.) may be adjusted. At this time, since the illumination optical system includes an aperture stop, a density filter for adjusting the illuminance distribution, a relay lens system, a field stop, and a condenser lens system, at least one of these optical systems is used. By displacing an element (eg, a lens element or a density filter), its optical properties can be adjusted. Also in this case, instead of displacing the optical element, the optical characteristics may be adjusted by changing the wavelength of the exposure light.

The method of adjusting the imaging characteristics of the projection optical system 4 is not limited to the method of driving the lenses L2 to L5 in the present example.For example, the method of adjusting the projection optical system 4 or the By adjusting the supply conditions (for example, flow rate, pressure, etc.) of the purge gas supplied to the sub-chambers 3, 8, and 6, the pressure inside the projection optical system 4 and the sub-chambers 3, 8, and 6 is adjusted, and the projection is performed. The imaging characteristics of the optical system 4 may be adjusted. At this time, for example, a difference occurs between the air pressure in the sub-chamber 8 and the air pressure in the projection optical system 4, and the imaging characteristics of the projection optical system 4 are changed. When there is a possibility that the pressure may fluctuate, for example, the air pressure in the sub-chamber 8 and the air pressure in the projection optical system 4 may be returned to a predetermined common target value by the air supply / exhaust mechanism 13. This eliminated the pressure difference Therefore, its imaging characteristics are maintained in a good state.

Furthermore, by changing the wavelength of the exposure light (exposure beam), the imaging characteristics of the projection optical system 4 or the optical characteristics of the illumination optical system (such as telecentricity) are adjusted (or corrected). Good. In this case, in order to increase the adjustment amount, a method for driving the above lens and a method for changing the wavelength of the exposure beam may be combined. In addition, a method of adjusting the supply condition of the purge gas and a method of changing the wavelength of the exposure beam may be combined.

Further, if the pressure of the purge gas fluctuates during the exposure, for example, the wafer W may be defocused due to a change in the optical path length. As an example, when the allowable range of the variation of the deformation force is about 10 nm, the fluctuation of the purge gas pressure is about 25 mmHg in the sub-chamber 8 (reticle chamber) containing the reticle stage system RST. Hereinafter, it is desirable to keep the projection optical system 4 to about 2 mmHg or less, and to keep the wafer stage system WST in the sub-chamber 6 (wafer chamber) to about 22 mmHg or less. Therefore, an air supply pipe and an exhaust pipe are connected to the sub-chamber 8, the projection optical system 4, and the sub-chamber 6 independently from the air supply / exhaust mechanism 13, and the sub-chamber 8, the projection optical system 4, and the sub-chamber 6 are put into the sub-chamber 8, the projection optical system 4, and the sub-chamber 6. The supply and exhaust of the purge gas may be controlled independently of each other. In this case, the distortion can be effectively corrected by adjusting the air pressure of the sub-chamber 8 (reticle chamber).

In addition, as the projection optical system 4 shown in the present embodiment, for example, a projection optical system as shown in FIG. 3 may be used.

In FIG. 3, the projection optical system includes a first imaging optical system having a refractive optical axis AX1 for forming a first intermediate image of a pattern of a reticle R as a projection master arranged on a first surface. With system G1. A first optical path bending mirror Ml is arranged near the position where the first intermediate image formed by the first imaging optical system G1 is formed. The first optical path bending mirror Ml deflects the light beam toward the first intermediate image or the light beam from the first intermediate image toward the second imaging optical system G2. The second imaging optical system G2 having the optical axis AX2 has a concave reflecting mirror CM and at least one negative lens NL, and is substantially equal to the first intermediate image based on the light flux from the first intermediate image. 1st intermediate image (1st intermediate image) Is formed in the vicinity of the formation position of the first intermediate image. A second optical path bending mirror M2 is arranged near the position where the second intermediate image formed by the second imaging optical system G2 is formed. The second optical path bending mirror M2 deflects the light beam toward the second intermediate image or the light beam from the second intermediate image toward the third imaging optical system G3 having the refractive optical axis AX3. Here, the reflecting surface of the first optical path bending mirror Ml and the reflecting surface of the second optical path bending mirror M2 are spatially separated. In addition, the first optical path bending mirror Ml and the second optical path bending mirror M2 integrally form a reflection block FM. The third imaging optical system G3 converts a reduced image of the pattern of the reticle R (an image of the second intermediate image and the final image of the catadioptric optical system) into a second image based on the light beam from the second intermediate image. It is formed on wafer W as a photosensitive substrate arranged on the surface.

In the configuration described above, the chromatic aberration and the Pebbal sum of positive values generated in the first imaging optical system G1 and the third imaging optical system G3, which are refractive optical systems including a plurality of lenses, are converted into the second imaging light. Compensated by concave mirror CM and negative lens NL of G2. Further, with the configuration in which the second imaging optical system G2 has an imaging magnification of approximately the same magnification, it is possible to form the second intermediate image near the first intermediate image. In this projection optical system, by performing optical path separation near these two intermediate images, the distance from the optical axis of the exposure region (ie, the effective exposure region), that is, the off-axis amount can be set small. As described above, the second imaging optical system G2 bears all the compensation for the color difference and the positive Petzval sum generated in the first imaging optical system G1 and the third imaging optical system G3. . For this reason, it is necessary to set both the concave reflecting mirror CM and the negative lens NL constituting the second imaging optical system G2 to have a large power. Therefore, if the symmetry of the second imaging optical system G2 is broken, asymmetric chromatic aberration such as chromatic aberration of magnification and chromatic coma will increase, and it will be impossible to obtain a sufficient resolving power. Therefore, in this projection optical system, by adopting a configuration in which the imaging magnification of the second imaging optical system G2 is set to approximately the same magnification and the concave reflecting mirror CM can be arranged near the pupil position. However, good symmetry can be ensured, and the above-described asymmetric chromatic aberration can be prevented from occurring.

In the above embodiment, the present invention is applied to a step-and-scan type projection exposure apparatus. However, the present invention can also be applied to a batch exposure type projection exposure apparatus such as a stepper. it is obvious. As an exposure beam, for example, a single wavelength laser in the infrared or visible range oscillated from a DFB semiconductor laser or a fiber laser, for example, erbium (E r)

The present invention is also applied to a case where a harmonic is amplified by a single-fiber amplifier doped with (or both erbium and ytterbium (Y b)) and wavelength-converted to ultraviolet light using a nonlinear optical crystal. .

Further, the illumination optical system and the projection optical system according to the above-described embodiment are assembled by arranging the respective optical members in a predetermined positional relationship, performing adjustment, and then installing the optical members on the corresponding frames and the like. Along with this assembly adjustment, assembling and adjusting the reticle stage system RST, the wafer stage system WST, and the air supply / exhaust mechanism 13 are performed, and the above components are electrically, mechanically, or optically connected to each other. The projection exposure apparatus according to the embodiment is assembled. In this case, it is desirable to perform the work in a clean room where the temperature is controlled.

Next, an example of a semiconductor device manufacturing process using the projection exposure apparatus of the above embodiment will be described with reference to FIG.

FIG. 4 shows an example of a semiconductor device manufacturing process. In FIG. 4, first, a wafer W is manufactured from a silicon semiconductor or the like. Thereafter, a photoresist is applied on the wafer W (step S10), and the wafer W is loaded on, for example, a sample table 5a of the projection exposure apparatus of FIG. In the next step S12, reticle R1 is loaded on reticle holder 7a in FIG. 1, and this reticle R1 is moved below the illumination area, and the pattern of reticle R1 is entirely transferred onto wafer W. Scans and exposes the shot area SE. The wafer W is, for example, a wafer having a diameter of 30 O mm (12-inch wafer). The size of the shot area SE is, for example, 25 mm in the non-scanning direction and 33 mm in the scanning direction. It is a rectangular area of mm. Next, in step S14, a predetermined pattern is formed in each shot region SE of the wafer W by performing development, etching, ion implantation, and the like. Next, in step S16, a photoresist is applied on the wafer W, and then in step S18, another reticle R2 is loaded on the reticle holder 7a in FIG. 1, and this reticle R2 is illuminated. Moving below the area, the pattern of the reticle R2 is scanned and exposed on each shot area SE on the wafer W. Then, in step S20, the development and etching of the wafer W By performing ion implantation or the like, a predetermined pattern is formed in each shot region of the wafer W. The above exposure process to pattern formation process (Step S16 to Step S

20) is repeated as many times as necessary to produce the desired semiconductor device. Then, through a dicing process (step S22) for separating each chip CP on the wafer W one by one, a bonding process, a packaging process, and the like (step S224), a semiconductor as a product is obtained. Device SP is manufactured.

The application of the exposure apparatus of the present invention is not limited to an exposure apparatus for manufacturing a semiconductor device. For example, a liquid crystal display element formed on a square glass plate, or a display apparatus such as a plasma display. It can be widely applied to exposure equipment for manufacturing various devices such as exposure equipment, imaging devices (such as CCD), micro machines, thin film magnetic heads, and DNA chips. Further, the present invention can be applied to an exposure step (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which a mask pattern of various devices is formed using a photolithographic process. .

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention. In addition, the specification, claims, drawings, and abstract, including the description, the Japanese patent application filed on October 31, 2000, 2000-

The entire disclosure of 3 3 3 9 9 6 is hereby incorporated by reference in its entirety. Industrial applicability

ADVANTAGE OF THE INVENTION According to this invention, when supplying the gas which an exposure beam permeates to the optical path of an exposure beam, the optical characteristic of the optical system in the optical path of an exposure beam, for example, the imaging characteristic of a projection system, becomes a favorable state. There are advantages that can be maintained. Accordingly, when the optical system is an illumination system, telecentricity and the like can be improved, and when the optical system is a projection system, high resolution and high overlay accuracy can be obtained.

When adjusting the imaging characteristics based on the pressure inside the projection system and the pressure inside the space before and after the projection system, the space inside the projection system and the space before and after the projection system are substantially independent of each other. When a gas that transmits the exposure beam is supplied to the Properties can be maintained in a good state.

Claims

The scope of the claims

1. In an exposure method for exposing an object with an exposure beam,

Supplying gas that transmits the exposure beam to a plurality of hermetic chambers provided along the optical path of the exposure beam;

Among the plurality of hermetic chambers, the air pressure inside at least one hermetic chamber is measured, and based on the measurement result, an image forming state of an image of a pattern exposed on the object, and An exposure method, wherein at least one of the gas supply conditions to at least one hermetic chamber is adjusted.

2. The exposure method according to claim 1, wherein an image formation state of the image of the pattern is adjusted by adjusting an optical characteristic of an optical system arranged in an optical path of the exposure beam.

3. The optical system is disposed between a mask on which the pattern is formed and the object, and includes a projection optical system that projects an image of the pattern onto the object.

3. The exposure method according to claim 2, wherein an image forming state of the image of the pattern is adjusted by displacing a predetermined optical member inside the projection optical system.

4. The exposure method according to claim 3, wherein the optical system includes an illumination optical system that illuminates a mask on which the pattern is formed.

5. The exposure method according to claim 2, wherein the imaging state of the image of the pattern is adjusted by changing a wavelength of the exposure beam.

6. The optical system includes: an illumination optical system that illuminates the mask on which the pattern is formed with the exposure beam; and a projection optical system that projects an image of the pattern onto the object. A first chamber that covers at least a part of the illumination optical system, a second chamber that houses the mask, a third chamber that covers at least a part of optical members of the projection optical system, and the substrate. 3. The exposure method according to claim 2, further comprising a fourth chamber in which is stored.

7. The exposure method according to claim 6, wherein the third chamber is disposed between the second chamber and the fourth chamber.

8. Detecting information related to at least one pressure difference between the third chamber and the second chamber or the fourth chamber adjacent to the third chamber,

7. The exposure method according to claim 6, wherein at least one of an optical characteristic of the optical system and a supply condition of the gas is adjusted according to the detected information.

9. The method according to claim 1, wherein the air pressure of each of the plurality of airtight chambers is measured, and the supply conditions of the gas to be supplied to the plurality of airtight chambers are adjusted based on the measurement result. Exposure method according to the above.

10. In an exposure apparatus that exposes an object with an exposure beam via an optical system,

A plurality of airtight chambers provided along the optical path of the exposure beam,

A gas supply mechanism for supplying a gas that transmits the exposure beam into the plurality of airtight chambers;

A barometer that measures the air pressure in at least one of the plurality of hermetic chambers;

Based on a measurement result of the barometer, at least one of an imaging state of an image of a pattern exposed on the object and a gas supply condition to at least one of the plurality of hermetic chambers is controlled. Exposure apparatus characterized by having a control mechanism

11. The exposure apparatus according to claim 10, wherein the optical system includes a projection optical system that projects an image of a pattern formed on a mask onto the object.

12. The exposure apparatus according to claim 11, wherein the control mechanism includes a driving unit that displaces a predetermined optical member of the projection optical system.

13. The exposure apparatus according to claim 11, wherein the optical system includes an illumination optical system that illuminates a mask on which the pattern is formed.

14. A flexible film member is provided so as to cover a space that communicates with a space between at least two adjacent airtight chambers among the plurality of airtight chambers. The exposure apparatus according to any one of ranges 10 to 13.

15. The optical system includes: an illumination optical system that illuminates a mask on which the pattern is formed with the exposure beam; and a projection optical system that projects an image of the pattern onto the object. A first chamber for covering at least a part of the illumination optical system, a second chamber for containing the mask, and a cover for at least a part of the optical members of the projection optical system. The exposure apparatus according to claim 10, further comprising a third chamber, and a fourth chamber in which the substrate is stored.

16. The exposure apparatus according to claim 15, wherein the third chamber is disposed between the second chamber and the fourth chamber.

17. A detection device for detecting information relating to a pressure difference between the third chamber and the second chamber or the fourth chamber adjacent to the third chamber,

The control mechanism according to claim 16, wherein the control mechanism adjusts at least one of an imaging characteristic of the projection optical system and a supply condition of the gas in accordance with information detected by the detection device. Exposure equipment.

18. The barometer is provided in each of the plurality of airtight chambers,

The gas supply mechanism according to claim 11, wherein the gas supply mechanism adjusts a supply condition of the gas based on a detection result of the barometer provided in the plurality of airtight chambers.

1 9. Device device using the exposure method according to any one of claims 1 to 9.

- A device manufacturing method characterized in that it comprises a step of transferring the down on the workpiece _c