WO2001093319A1

WO2001093319A1 - Gas supply system, exposure device, and method of producing device

Info

Publication number: WO2001093319A1
Application number: PCT/JP2001/004597
Authority: WO
Inventors: Motokatsu Imai; Tomonari Nakamura
Original assignee: Nikon Corporation
Priority date: 2000-05-31
Filing date: 2001-05-31
Publication date: 2001-12-06
Also published as: JPWO2001093319A1; AU2001262678A1

Abstract

A gas supply system and an exposure device, wherein exposure light is prevented from being attenuated by a light absorbing substance and is thereby allowed to reach a substrate in a stabilized manner without the optical characteristics of the exposure device being greatly affected. The gas supply system comprises a feed pipe (30) for feeding a predetermined gas to a space (PA), a refiner (33) having a plurality of gas refining units (40, 41) for refining the predetermined gas from a gas to be refined, the feed pipe (30) being connected to the plurality of gas refining units (40, 41).

Description

Description Gas supply system, exposure apparatus and device manufacturing method

The present invention relates to an exposure apparatus for manufacturing an electronic device such as a semiconductor device, a liquid crystal display device, an imaging device (such as a CCD), and a thin-film magnetic head, and more particularly to supplying a predetermined gas to a space in the exposure device. Gas supply system.

This application is based on a patent application to Japan (Japanese Patent Application No. 2000-163614), the contents of which are incorporated herein. Background art

When manufacturing semiconductor devices (integrated circuits, etc.) and devices such as liquid crystal display panels (electronic devices) in the photolithographic process, a mask or reticle (hereinafter collectively referred to as a reticle) is used by exposure light (exposure light) for exposure from a light source. An exposure apparatus is used which illuminates a reticle and transfers a reticle pattern (circuit pattern) to a substrate (a wafer coated with a photosensitive agent, a glass plate, etc.) via a projection optical system. The circuit of the electronic device is transferred by exposing a circuit pattern on the substrate by the projection exposure apparatus, and is formed by post-processing. For example, an integrated circuit is formed by repeatedly laminating about 20 layers of the circuit wiring thus formed.

In recent years, high-density integration of integrated circuits, that is, miniaturization of circuit patterns has been promoted, and accordingly, the wavelength of exposure light in an exposure apparatus tends to be shortened. In other words, a KrF excimer laser (wavelength: 248 nm) has been used as the exposure light instead of the emission line of a mercury lamp that has been dominant until now, and a shorter wavelength ArF excimer laser (193 nm) has been used. ) Is also entering the final stage. In addition, research on F2 laser (157 nm) and Ar 2 laser (126 nm) is being pursued for further high-density integration.

Light (energy beam) having a wavelength of about 120 nm to 200 nm belongs to the vacuum ultraviolet region, and these lights (hereinafter referred to as vacuum ultraviolet light) do not pass through air. this is, This is because the energy of light is absorbed by molecules of oxygen, water, carbon dioxide, organic substances, halides, etc. (hereinafter referred to as “absorbing substances”) contained in the air.

Therefore, when vacuum ultraviolet light is used as the exposure light, the concentration of the light-absorbing substance in the optical path space in the exposure apparatus (that is, the space from the light source to the substrate) is sufficient to obtain a desired illuminance (light amount) on the substrate. It is necessary to increase the exposure light transmittance. Therefore, it is necessary to fill the exposure space with a high-purity purge gas containing almost no light-absorbing substance. Also, a plurality of optical elements (reflective optical elements, lenses, etc.) are arranged in the space in the optical path, and when the environment such as temperature and pressure between these optical elements changes, the optical characteristics of the exposure apparatus change. In order to stably reach the exposure light to the substrate, it is necessary to appropriately control the state of the purge gas.

The present invention has been made in view of the above circumstances, and prevents exposure light from being attenuated by a light-absorbing substance without significantly affecting optical characteristics of an exposure apparatus, and allows exposure light to reach a substrate stably. It is an object to provide a gas supply system and an exposure apparatus which can perform the above. Disclosure of the invention

In order to solve the above-described problems, the present invention provides a gas supply system for supplying a predetermined gas to a space (PA) in an exposure apparatus via a supply pipe (30). A plurality of gas purifiers (40, 41) for purifying from the gas to be purified are provided, and the supply pipe (30) is connected to the plurality of gas purifiers (40, 41), respectively. It is characterized by that.

In this gas supply system, a predetermined gas is purified from a gas to be purified by a gas purifier, and the purified predetermined gas is supplied to a space in the exposure apparatus via a supply pipe. This makes it possible to fill the space in the exposure apparatus with a high-purity gas with reduced light-absorbing substances. Further, since the supply pipe is connected to a plurality of gas purifiers, it becomes possible to more stably supply a high-purity predetermined gas to the space in the exposure apparatus as compared with the case where one gas purifier is used. .

Here, “space” means a three-dimensional area surrounded by an object, for example, an internal space of a housing, and is either airtight or non-airtight. Shall be included. The “non-hermetic space” is, for example, an airspace where the air pressure inside the housing is set higher than the outside air pressure and no external air flows into the housing. Also,

The “space in the exposure apparatus” is a space formed between the light source and the substrate. For example, an illumination system housing that houses an illumination optical system that illuminates the reticle, and an image of a pattern formed on the reticle is printed on the substrate. A reticle chamber for accommodating a reticle, and a wafer chamber for accommodating a substrate. In addition, the space between the illumination system housing and the plurality of optical elements arranged in the lens barrel (particularly, the space where the optical elements face) also corresponds.

In this case, as in another embodiment of the present invention, the gas to be purified is supplied from a gas supply source to be purified, and the gas supply source to be purified is a gas cylinder containing the gas to be purified. 36) or the space (PA). Refined gas When the supply source is a gas cylinder, even if the refined gas contained in the gas cylinder is a specific gas with a certain degree of purity, the gas purifier purifies the specific gas to higher purity. . Further, even if the gas to be purified contained in the gas cylinder is a high-purity predetermined gas, impurities are mixed into the high-purity predetermined gas on the way between the gas cylinder and the gas purifier, and Even if the purity is reduced, the gas purifier purifies the predetermined gas into a high-purity gas. Furthermore, when the source of the gas to be purified is a space inside the exposure apparatus, the gas consumption is reduced by purifying and reusing the gas from the space.

In still another embodiment, the gas supply system selectively selects any one of the plurality of gas purifiers (40, 41) for the space (PA). A switching device (44) for connection may be provided. Also. The gas supply system has a first measuring device (42) for measuring the concentration of impurities contained in the purified gas purified by the gas purifier or the concentration of the predetermined gas, and the switching device (44) ) May be connected to any one of the gas purifiers based on the measurement result by the first measuring device (42). In this case, one of the gas purifiers is selectively connected to the space in the exposure apparatus based on the concentration of the impurity measured by the first measurement apparatus or the concentration of the predetermined gas, so that the performance is improved. By discontinuing the use of greatly reduced gas purifiers or giving priority to high-performance gas purifiers, It becomes possible to stably supply a high-purity predetermined gas to the space in the exposure apparatus. In still another embodiment, the gas supply system further comprises: a second measuring device (52) for measuring the concentration of the impurity contained in the gas to be purified or the concentration of the predetermined gas upstream of the gas purifier; A gas discharging device (55) for discharging the gas to be purified from upstream of the gas purifier (53, 54) to the outside based on the measurement result by the second measuring device (52). I'm sorry. In this case, the gas is discharged from the upstream of the gas purifier to the outside based on the concentration of the impurity measured by the second measuring device or the concentration of the predetermined gas. Inflow is prevented, and a significant decrease in the performance of the gas purifier can be prevented.

In still another embodiment, the gas supply system includes a gas filling device (51) for replenishing a predetermined gas, and the gas replenishing device (51) is provided with the gas purifier (53,5). 4) may be connected upstream. In this case, since the gas from the gas replenishing device is purified by the gas purifier, contamination of impurities into the space in the exposure device due to gas replenishment is suppressed.

In still another embodiment, the gas supply system for supplying the predetermined gas to the space (PA) in the exposure apparatus includes: supplying the predetermined gas to the space (PA) via a gas supply pipe (61). (PA) and a pulsation suppressor (62) for suppressing pressure fluctuation of the predetermined gas flowing in the gas supply pipe (61).

In this gas supply system, the fluctuation of the pressure of the gas supplied to the space inside the exposure apparatus is suppressed by the pulsation suppressor, so that the pressure change in the space inside the exposure apparatus due to the gas supply is reduced.

In this case, the pulsation suppression device (62) is disposed immediately before the exposure device, so that the pressure fluctuation of the gas caused by the gas supply system is effectively suppressed.

In still another embodiment, the pulsation suppressor (62) of the gas supply system is configured to suppress a pressure fluctuation of the gas flowing in the gas supply pipe (61) to 3 mmHg or less. Is also good. In this case, the influence of the gas pressure fluctuation on the optical characteristics of the exposure apparatus is reliably prevented. Further, the present invention provides an exposure apparatus having a plurality of spaces formed in an optical path of an energy beam, wherein the gas supply system is provided to supply a predetermined gas to at least one of the plurality of spaces. It is characterized by.

According to the present invention, there is provided a method for manufacturing a device including a lithographic process, wherein a devise is manufactured using the exposure apparatus in the lithography step. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram showing a first embodiment of an exposure apparatus including a gas supply system according to the present invention.

FIG. 2 is an overall configuration diagram showing a first embodiment of the exposure apparatus according to the present invention.

FIG. 3 is a configuration diagram showing a gas supply system in a second embodiment of the exposure apparatus according to the present invention.

FIG. 4 is a configuration diagram showing an example of the gas discharge device 55 shown in FIG.

FIG. 5 is a configuration diagram showing a gas supply system in a third embodiment of the exposure apparatus according to the present invention.

FIG. 6 is a flowchart showing an example of a device manufacturing process. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a first embodiment of an exposure apparatus including a gas supply system according to 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 type exposure apparatus using vacuum ultraviolet light as an energy beam for exposure.

FIG. 2 is a partially cutaway configuration view showing a schematic configuration of the exposure apparatus of the present example. In FIG. 2, the mechanism of the exposure apparatus of the present example includes an illumination optical system unit 5 and a reticle operation unit 6. , The projection optical system PL and the wafer operation unit 7.The illumination optical system unit 5, the reticle control unit 6, the projection optical system PL, and the wafer operation unit 7 are respectively a box-shaped illumination system 1 and reticle. The chamber 2, the lens barrel 3, and the wafer chamber 4 are housed in a substantially sealed state, being isolated from outside air (here, gas in a chamber described later). You. The “closed state” refers to the flow of gas between the internal space and the external space.

There is no outflow or inflow of gas between the internal space and the external space, but the pressure in the internal space is higher than the external space so that gas flows out from the internal space to the external space. Indicates a state in which the flow of gas from the external space to the internal space is suppressed when set.

In addition, the space inside the exposure apparatus, that is, the internal space of the illumination system chamber 1, the reticle chamber 2, the lens barrel 3, and the wafer chamber 4 (particularly, the space facing the optical element) is provided by a gas supply system 8 described later. Temperature controlled gas (purge gas) is supplied. Further, the exposure apparatus of the present embodiment is housed in one large chamber (not shown) in which the temperature of the gas inside is controlled within a predetermined target range.

In the illumination optical system unit 5, F ₂ laser light source for generating a pulsed laser beam having a wavelength of 1 5 7 eta m in the vacuum ultraviolet region as the exposure light source 1 1 is used, the exit end of the exposure light source 1 1 is an illumination system Installed at the bottom of chamber 1. Exposure light IL (energy beam) emitted from the exposure light source 11 into the illumination system chamber 1 at the time of exposure is reflected upward by the mirror 112, and is used to adjust the cross-sectional shape of the illumination system and control the amount of light. The light enters the fly-eye lens (or rod lens) 14 as an optical integrake (homogenizer) via the shaped optical system 13. An aperture stop (not shown) is arranged on the exit surface of the fly-eye lens 14. Exposure light IL emitted from the fly-eye lens 14 and passing through the aperture stop is reflected by the mirror 15 in a substantially horizontal direction. The field stop (reticle blind) 17 is reached via the relay lens 16.

The arrangement surface of the field stop 17 is almost conjugate with the pattern surface of the reticle R to be exposed.The field stop 17 has a fixed blind that defines the shape of the elongated rectangular illumination area on the pattern surface, It has a movable blind that closes its illumination area to prevent exposure of unnecessary parts at the start and end. Exposure light IL that has passed through the field stop 17 passes through a relay lens 18, a mirror 19, and a condenser lens system 20 fixed to the tip of the illumination system chamber 1, and a rectangular shape on the reticle R pattern surface ( Illuminate the illumination area (on the slit) with a uniform illuminance distribution. Exposure light source 1 1 to condenser lens system 20 constitute illumination optics section 5, illumination optics section 5 The optical path of the exposure light IL, that is, the optical path from the exposure light source 11 to the condenser lens system 20 is sealed by the illumination system champer 1. In addition, between the illumination optical system unit 5 and the exposure light source 11, a beam matching unit (for adjusting the optical axis of the illumination optical system unit 5 and the optical axis of the exposure light IL emitted from the exposure light source) is used. (Not shown) is provided. Further, the beam matching unit may be provided with an automatic tracking mechanism (not shown) for correcting an optical axis shift due to vibration or the like.

Under the exposure light IL from the illumination optical system section 5, an image of the pattern in the illumination area of the reticle R passes through the projection optical system PL to a predetermined projection magnification β (β is, for example, 1/4,

1-5), and projected onto the wafer W coated with photosensitive material (photoresist). The wafer W is a disk-shaped substrate such as a semiconductor (silicon or the like) or SOI (silicon on insulator).

Here, the exposure light IL as in this example in the case of the F ₂ laser beam is good good optical glass material of the transmittance was doped fluorite. (Crystal C a F _2), fluorine or hydrogen, etc. Since it is limited to quartz glass, magnesium fluoride (MgF ₂ ), etc., it is difficult to obtain the desired imaging characteristics (chromatic aberration characteristics, etc.) by configuring the projection optical system PL with only refractive optical members. There may be. Therefore, a catadioptric system combining a refractive optical member and a reflecting mirror may be employed as the projection optical system PL. In the following description, the X axis is taken in a direction intersecting the optical axis AX of the shadow optical system PL, and the Y axis is taken perpendicular to the plane of FIG. The illumination area on the reticle R in this example is a rectangle elongated in the X direction, and the scanning direction of the reticle R and the wafer W during exposure is in the Y direction.

In the reticle operating section 6, a reticle R is held on a reticle stage 21. The reticle stage 21 continuously moves the reticle R in the Y direction on a reticle base (not shown), and minutely drives the reticle R so as to reduce synchronization errors in the X, Y, and rotation directions. The position and the rotation angle of the reticle stage 21 are measured with high precision by a laser interferometer (not shown), and the measured values and control information from a main control system 25 composed of a computer that controls the overall operation of the apparatus. The reticle stage 21 is driven on the basis of. The reticle operation unit 6 is composed of a reticle stage 21 and a reticle base / reticle loader (not shown), and is projected from the optical path of the exposure light IL in the reticle operation unit 6, that is, from the condenser lens system 20. The optical path to the optical member on the reticle side of the optical system PL is sealed by the reticle chamber 2.

In the projection optical system PL, a plurality of optical members (optical elements) (not shown) are housed in a lens barrel 3, and an optical path from the optical member on the reticle side of the projection optical system PL to the optical member on the wafer side is formed. It is sealed in the lens barrel 3. Note that a gas (purge gas) from a gas supply system 8 described later is supplied to each closed space facing the optical member in the projection optical system PL.

In this example, fluorite (C a F ₂ crystal) is used for all refractive optical members (optical elements) constituting the projection optical system PL. The oscillation center wavelength of the _two laser light as an energy beam is 157.6 nm, and the wavelength width is 157.6 nm.

Chromatic aberration has been corrected for the 10-pm light, and various aberrations such as spherical aberration, astigmatism, and distortion have been well corrected.

In the wafer operating section 7, the wafer W is suction-held on the mounting surface formed of the concave portion on the wafer holder 22, the wafer holder 22 is fixed to the concave portion on the wafer stage 23, and the surface 23a of the wafer stage 23 is formed. Are arranged on substantially the same plane as the surface of the wafer W and the surface of the wafer holder 22. This allows the gas to flow smoothly over the surface of the wafer W. Wafer stage 2 3 is wafer base

24. The wafer W is continuously moved in the Y direction on step 4, and the wafer W is step-moved in the X and Y directions. In addition, the wafer stage 23 projects the surface of the wafer W by an autofocus method based on information on a position (focus position) in the optical axis AX direction of the surface of the wafer W measured by an auto force sensor (not shown). Optical system

Focus on the image plane of PL. Position of wafer stage 23 in X and Y directions, rotation angle around X axis (pitching amount), rotation angle around Y axis (rolling amount), rotation angle around Z axis (jowing amount) Is measured by a laser interferometer (not shown) with high accuracy. Based on the measured values and control information from the main control system 25, the wafer stage

23 is driven.

The wafer operation unit 7 is configured by the wafer holder 22, the wafer stage 23, and the wafer base 24, and a wafer loader or the like (not shown) as a transfer system is arranged in the X direction of the wafer operation unit 7. . Furthermore, the exposure light in the wafer operation unit 7 The optical path of the IL, that is, the optical path from the optical member on the wafer side of the projection optical system PL to the wafer base is sealed by the wafer chamber 4. Note that an opening / closing door may be attached to one side surface of the wafer chamber 4, and the door may be opened when the wafer W is replaced. Here, the gas supply system 8 will be described with reference to FIG.

The gas supply system 8 according to the present embodiment is configured such that a predetermined gas serving as a purge gas is supplied in a highly pure state with the illumination system chamber: chamber 1, reticle chamber 2, lens barrel 3, and wafer chamber 4 in each internal space.

(Hereinafter, each space is collectively referred to as a purge space PA :). In this example, the recovered gas recovered from each purge space PA is purified as a gas to be purified and reused. As the purge gas, an inert gas having a high transmittance with respect to the exposure light IL, that is, a gas containing substantially no light absorbing substance (a “transmitted gas” described later) is used.

Since the exposure light IL of this embodiment is the wavelength 1 5 7 nm vacuum ultraviolet light, as the light absorbing material relative to the exposure light IL, oxygen (0 _2), water (water vapor: H ₂ 0), carbon dioxide (CO : Co ₂ ), organic substances, and halides. On the other hand, the exposure light I

Gases through which L permeates (substances that hardly absorb energy) include nitrogen (N 2), helium (He), neon (Ne :), argon (Ar), and talliptone ( There is a rare gas consisting of Kr), xenon (Xe), and radon (Rn). Hereinafter, this nitrogen gas and rare gas will be collectively referred to as “permeated gas”.

Here, nitrogen gas acts as a light-absorbing substance for light having a wavelength of 150 nm 1 or less, and helium gas can be used as a transmissive gas up to a wavelength of about 100 nm. In addition, helium gas has a thermal conductivity of about 6 times that of nitrogen gas, and the amount of change in the refractive index with respect to pressure change is about 1 Z8 of nitrogen gas. Excellent in stability and cooling.

In this example, helium gas is used as the purge gas through which the exposure light IL passes, from the viewpoint of the stability of the imaging characteristics and the cooling property. Since helium gas is high value, the case is 1 5 0 nm or more as long the exposure beam is an F ₂ laser, the use of nitrogen gas as a purge gas in order to reduce the operating costs Good.

The gas supply system 8 has a supply line connected to the purge space PA. A circulation path 32 having a pipe 30 and a collection pipe 31; a purification apparatus 33 having one end connected to the supply pipe 30 and the other end connected to the collection pipe 31; A supply device 34 for supplying the purge gas purified in step 3 to the purge space PA via a supply pipe 30, a temperature controller 35 for controlling the temperature of the purge gas, and a helium gas as the purge gas. It is configured to include a gas cylinder 36 to be housed and the main control system 25 for integrally controlling each device. The supply pipe 30 and the recovery pipe 31 are branched into a plurality according to each purge space PA, and the supply pipe 30 is provided with valves 37 A to 37 D that can adjust the flow rate. Connected to each purge space PA via .

The purifying device 33 purifies high-purity purge gas (helium gas) by removing impurities, that is, the above-mentioned light-absorbing substance, from the purge gas collected from each purge space PA. (Here, two) gas purifiers 40 and 41 are provided. The plurality of gas purifiers 40 and 41 have a downstream end connected to a supply pipe 30 and an upstream end connected to a recovery pipe 31, respectively. It is arranged parallel to 32 and detachably.

Further, downstream of the gas purifiers 40 and 41, a measuring device 42 for measuring the concentration of the light-absorbing substance contained in the gas purified by the gas purifiers 40 and 41 is connected. The measured value of the device 42 is supplied to the main control system 25. As the measuring device 42, for example, an oxygen concentration meter, a dew point meter as a water vapor concentration meter, a concentration meter such as a carbon dioxide sensor, or a composite sensor combining these sensors is used. As a measuring device, the concentration of the light-absorbing substance contained in the gas is indirectly measured by applying a current to the inside of the gas purifiers 40 and 41 and measuring the current value. The same effect can be obtained with a sensor for measurement. Also, in each purge space PA, measuring devices 43A to 43D similar to the measuring device 42 may be individually provided independently. In addition, one measuring device is prepared, and each purge space PA and one measuring device are connected by piping, and each purge space PA and one measuring device are selectively connected, so that impurities in the purge space are removed. The concentration or the concentration of helium gas may be measured.

On the other hand, upstream of the gas purifiers 40 and 41, based on the measurement results by the measuring device 42, In addition, a switching device 44 for selectively connecting any one of the gas purifiers 40 and 41 to the collection pipe 31 is provided. As the switching device 44, for example, a control valve having a driving device is used. Here, the switching device 44 operates when the concentration of a predetermined light absorbing substance (oxygen, water vapor, and carbon dioxide in this example) measured by the measuring device 42 exceeds a preset allowable concentration. Based on the instruction of the control system 25, one of the gas purifiers 40 and 41 is switched to and connected to the collection pipe 31. The state where the concentration of the predetermined light-absorbing substance measured by the measuring device 42 becomes high may be a case where the gas purifier deteriorates due to long-time use and the gas purifying ability of the gas purifier decreases. As described above, when the purification capacity of the gas purifier is reduced, the light-absorbing substance that cannot be removed by the gas purifier flows out downstream. Therefore, the measuring device 42 can determine the refining ability of the gas purifier by measuring the concentration of the light-absorbing substance that cannot be removed by the gas purifier.

Helium gas as a purge gas is compressed or liquefied in a high-purity state and stored in the gas cylinder 36. Helium gas is replenished into the supply pipe 30 by opening the valve 36A. It is supposed to be.

Subsequently, a gas supply method by the gas supply system 8 will be described.

In this gas supply system 8, the interior space of the illumination system chamber 1, the reticle chamber 2, the lens barrel 3, and the wafer chamber 4, that is, the purge space PA, is filled with a purge gas (helium gas) as a high-purity permeation gas. The supply device 34 is driven to recover the gas and the light-absorbing substance in the purge space PA via the recovery pipe 31, and the purifying device 33 purifies a high-purity purge gas from the recovered gas. Then, after the temperature of the purified purge gas is controlled by the temperature controller 35, the purge gas is supplied into the purge space PA of the exposure apparatus via the supply pipe 30. When the supply of the purge gas is started, if the helium gas (permeable gas) is small in the purge space PA, the gas in the purge space PA is once discharged by a vacuum pump or the like (not shown). Helium gas is supplied into the purge space PA by opening the valve 36 A of the gas cylinder 36, or helium gas is supplied to each purge space PA while the gas in the purge space PA is exhausted by the vacuum pump. Then, Was However, when the purge gas is supplied, it is desirable that the gas in the purge space Ρ is not supplied to the gas purifier 33 but exhausted outside. With this configuration, it is possible to prevent the performance of the gas purifier 33 from being significantly deteriorated.

At this time, in the gas supply system 8, the gas purifier to be used is divided into a plurality of gas purifiers (in this embodiment, gas purifiers 40, 41) based on the concentration of the light absorbing substance measured by the measuring device 42. ) Select one from. Here, one gas purifier (for example, gas purifier 40) is continuously used until the concentration of the light-absorbing substance to be measured reaches a predetermined allowable concentration (for example, 10 ppm by volume). When the concentration is exceeded, switch to another gas purifier (for example, gas purifier 41) and use it. That is, when the concentration of the light-absorbing substance exceeds the predetermined allowable concentration, the switching device 44 is driven based on the instruction of the main control system 25 to collect another gas purifier different from the one before. Connect to piping 31. As a result, a new gas purifier is opened with respect to the circulation path '32, and the purge gas purified by the gas purifier is supplied to the purge space PA. On the other hand, the original gas purifier used up to the point is cut off from the recovery pipe 31 by the switching device 44, so that the gas purifier is closed with respect to the circulation path 3.2. While the gas purification process is being performed, a refresh process is performed to restore the purification capacity.

In other words, although the purifying capacity of the gas purifiers 40 and 41 gradually decreases with the gas purifying process, other gas purifiers arranged in parallel while using one gas purifier are used. High-purity purge gas is continuously supplied to the purge space PA without delay by controlling the concentration of light-absorbing substances contained in the purified purge gas to below the permissible concentration. Can be supplied.

At this time, the main control system 25 monitors the concentration of the light-absorbing substance in each purge space PA based on the measurement results of the measuring devices 43A to 43D arranged in each purge space PA, The supply amount of the purge gas to the purge space PA is controlled by the supply device 34 or the valves 37A to 37D. Then, when it is confirmed that the concentration of the light-absorbing substance has become equal to or lower than the predetermined allowable concentration and each purge space PA has been filled with a high-purity purge gas, the next exposure processing operation is executed.

As the exposure processing operation, in the exposure apparatus having the above configuration, the reticle R shown in FIG. C) The so-called step-and-scan scanning exposure, in which the pattern formed on the reticle R is transferred to each shot area of the wafer W via the projection optical system PL while synchronizing the movement of W with the one-dimensional direction. I do. As a result, a reduced image of the pattern of the reticle R is sequentially transferred to each shot area on the wafer W.

At this time, in the exposure apparatus of the present embodiment, as described above, the gas supply system 8 allows the purge space PA (the illumination system chamber 1, the reticule chamber 2, the lens barrel 3, and the like) to be disposed in the optical path of the exposure light IL. Fill each internal space of the wafer chamber 4 with helium gas as a high-purity permeation gas to reduce the concentration of light-absorbing substances. Therefore, even when vacuum ultraviolet light is used as the exposure light IL as in this example, the attenuation of the exposure light IL due to the light absorbing substance is prevented, and the exposure light IL is stably provided with sufficient illuminance and sufficient illuminance uniformity. It reaches wafer W.

Furthermore, the gas supply system 8 monitors the concentration of the light-absorbing substance contained in the purge gas supplied to the purge space PA, and controls the concentration so as to be lower than a predetermined allowable concentration (for example, 10 ppm by volume). In the purge space PA, a high transmittance state is stably maintained. Moreover, since the gas in the purge space PA is purified and reused, the gas consumption is small.

In the exposure apparatus of the present embodiment, the gas supply system 8 selectively uses one of the plurality of gas purifiers 40 and 41 to continuously supply high-purity purge gas to the purge space PA. Supply. Therefore, the space in the optical path is always filled with the high-purity helium gas as a permeated gas, and the continuous exposure processing operation is stably performed.

Next, a second embodiment of the present invention will be described with reference to FIGS.

The main difference between the second embodiment and the first embodiment is that the gas supply system 8 of the first embodiment has a configuration in which all the recovered gas from the purge space PA flows to the purification device 33. On the other hand, the gas supply system 50 of the second embodiment is configured to discharge the recovery gas from the purge space PA to the outside according to predetermined conditions. As in the first embodiment, the purge space PA in the exposure apparatus corresponds to, for example, a wafer chamber, a reticle chamber, and a space in an optical path (particularly, a space facing an optical element). That is, the gas supply system 50 of the present embodiment is provided with a recovery gas as a gas to be purified. Measuring device 52 that measures the concentration of light-absorbing substances (impurities) contained in the gas, and discharges the collected gas to the outside from the upstream of the gas purifiers 53 and 54 based on the measurement results of the measuring device 52 A gas discharge device 55 is provided. The gas discharge device 55 also has a function as the switching device 44 shown in the first embodiment. For example, as shown in FIG. 4, a plurality of control valves 55 A to 55 It has a configuration combining 55 C (for example, a configuration including a three-way valve 55 A and stop valves 55 B, 55 C). The measurement result of the measuring device 52 is sent to the main control system 25, and the concentration of the predetermined light absorbing substance (oxygen, water vapor, and carbon dioxide) measured by the measuring device 52 exceeds the predetermined allowable concentration. In some cases, the control valve 55 A is switched based on an instruction from the main control system 25 to discharge a predetermined gas to the outside through a discharge pipe 56. As the measuring device 52, the same device as the measuring device 42 described in the first embodiment is used.

In the exposure apparatus of this embodiment including such a gas supply system 50, when the concentration of the light absorbing substance contained in the collected gas is lower than a predetermined allowable concentration (for example, 100 ppm by volume ratio), the gas discharge device 55 When the concentration of the light-absorbing substance exceeds a predetermined allowable concentration (for example, 100 ppm in volume ratio) while the collected gas is passed through the gas purifiers 53 and 54 by the Then, the direction of the flow of the recovered gas is switched by the gas discharge device 55, and the recovered gas is discharged to the outside via the discharge pipe 56. For this reason, when the purge space PA is excessively contaminated, for example, when starting up the apparatus or performing maintenance, it is possible to prevent the contaminated recovered gas from flowing into the gas purifiers 53, 54, The performance of the gas purifier can be stably maintained. When the gas is discharged to the outside by the gas discharge device 55, it is preferable to open the valve 51A of the gas cylinder 51 and supply the purge gas to the purge space PA. Further, in the present embodiment, unlike the first embodiment, a gas cylinder 51 for replenishing a predetermined gas is connected to the upstream side of the gas purifiers 53, 54. Therefore, even if the gas contained in the gas cylinder 51 has a certain degree of purity (including a few ppm of light-absorbing substance), the gas must be subjected to gas purification. Mixing of the light absorbing substance into the purge space PA due to the replenishment of the gas is more reliably suppressed. That is, despite the fact that a predetermined gas of high purity is stored in the gas cylinder 51, Even if impurities are mixed into the predetermined gas on the way from the gas cylinder 51 to the purifier 33, the purity of the predetermined gas is reduced, the gas purifiers 53, 54 convert the predetermined gas into high-purity gas. Purified. In addition, high purity gas is generally expensive. Therefore, for the purpose of cost reduction, a gas cylinder containing a gas with a purity that is several percent lower than that of a high-purity gas is purchased, and the gas is purified by gas purifiers 53 and 54. Purity gas can also be supplied to the purge space PA.

Next, a third embodiment of the present invention will be described with reference to FIG.

The gas supply system 60 of the third embodiment is different from each of the above-described embodiments, and includes a pulsation suppressor 62 for suppressing pressure fluctuation of the purge gas flowing in the supply pipe 61.

The pulsation suppressor 61 suppresses pressure fluctuation of gas flowing in the pipe, particularly pulsation of the pipe する generated in a short cycle, by diffusing the energy of the fluid or absorbing the energy into other objects. Here, a pulsation prevention tank formed with a predetermined volume so as to widen the flow path of the supply pipe 61 is used. It is needless to say that the pulsation suppressing device 61 is not limited to the tank-shaped form, but various forms can be applied.

In the exposure apparatus of the present embodiment including such a gas supply system 60, since the fluctuation of the pressure of the purge gas supplied to the purge space PA is suppressed by the pulsation suppressor, the pressure in each purge space PA due to the supply of the purge gas is reduced. The change is small. In an exposure apparatus, in general, when the atmospheric pressure changes in the space in the optical path, the refractive index of light changes, which may affect the optical characteristics. Therefore, by controlling the pressure change and keeping the environment of the purge space PA constant, the exposure light can reach the substrate more stably. In addition, the exposure apparatus may be equipped with a correction device for keeping the atmospheric pressure in a predetermined space constant.However, it is difficult to cope with a short-period pressure fluctuation, so it is effective to provide such a pulsation suppression device. It is. Here, by suppressing the pressure fluctuation of the gas flowing in the supply pipe 61 to 3 mmHg or less, it is possible to reliably prevent the influence of the gas pressure fluctuation on the optical characteristics of the exposure apparatus. .

The cause of the pressure fluctuation is mainly due to the supply of purge gas to the purge space PA. In many cases, the supply device 63 (for example, a pump) is used, and the pulsation suppressing device 62 needs to be arranged at least downstream of the supply device 63. In the present embodiment shown in FIG. 5, in order to suppress pressure fluctuations caused by devices other than the supply device 63 (for example, the purification device 64), a pulsation suppressing device 6 is provided downstream of the purification device 64. Two are arranged. Thus, by disposing the pulsation suppressor 62 immediately before the purge space PA of the exposure apparatus, it is possible to effectively suppress the gas pressure fluctuation caused by the gas supply system 60. In FIG. 5, the pulsation suppressor 62 is arranged upstream of the temperature controller 65 in order to improve the temperature control accuracy. In this case, a pulsation suppressor 62 may be disposed downstream of the temperature controller 65.

The various shapes, combinations, procedures, and the like of the constituent members shown in each of the above-described embodiments are merely examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention. is there. The present invention includes, for example, the following changes.

In each of the above embodiments, the force S at which two gas purifiers are provided for the purifier is not limited to this, and may be 3 or more, which is appropriately determined according to the refining capacity. Further, in each of the above embodiments, since a plurality of gas purifiers are arranged in parallel with respect to the circulation path, the advantage that one gas purifier can recover the refining ability of another gas purifier during use. have. However, the present invention is not limited to this, and a plurality of gas purifiers may be arranged in series with respect to the circulation path. In this case, the concentration of the light absorbing substance contained in the purge gas can be further reduced. In addition, by arranging gas purifiers with different purification capacities in series from the upstream in ascending order of their capacity, it is possible to prevent contamination of the gas purifiers with high purification capacities and the flow of collected gas. Becomes If the purge space PA is excessively contaminated, for example, during equipment startup or during maintenance, it is necessary to prevent the contaminated recovered gas from flowing into the gas purifiers 53, 54. It is possible.

In the above embodiments, when the concentration of the light-absorbing substance measured by the measuring device exceeds a predetermined allowable concentration, control is performed so that the gas purifier to be used is changed. Instead, the gas purifier to be used may be changed every predetermined time that is input in advance. Furthermore, based on the concentration of the light absorbing substance measured by the measuring device, May be preferentially used. Further, a measuring device for measuring the transmittance or the reflectance of the optical member may be provided, and the gas purification to be used may be changed based on the measurement result of the measuring device.

In each of the above embodiments, a plurality of gas purifiers are attached to the gas supply system, but only one gas purifier is actually connected to the collection pipe. Therefore, when switching between a gas purifier whose performance has deteriorated and an unused gas purifier with a switching device, and refreshing or maintaining the gas purifier whose performance has deteriorated, the target gas purifier is identified. An identification mechanism may be provided. That is, for example, the identification mechanism reads the identification number given to the gas purifier in advance, sends a signal corresponding to the identification number to the main controller, and based on the signal, the main control system performs predetermined monitoring. Alternatively, the identification number may be displayed on the display to notify the maintenance worker of the target gas purifier. '

In the above embodiment, a plurality of gas purifiers are attached to the gas supply system before operating the exposure apparatus, and the gas used is determined based on the concentration of the light absorbing substance measured by the measuring apparatus. The case where one of the purifiers is selected has been described. However, the present invention is not limited to the above-described embodiment, but includes various modifications such as, for example, the form described below. That is, for example, before moving the exposure apparatus, one gas purifier is attached to the gas supply system for a predetermined period of time (in this case, the period during which the purifying ability of the gas purifier decreases). The gas recovered from the purge space is purified by this gas purifier until the gas elapses, and after a predetermined time, the refreshed gas purifier or a new (unused) gas purifier is supplied to the gas supply system. After installation, the switching device is driven to switch from the gas purifier that was initially installed to the newly installed gas purifier and connect it to the collection pipe. You may. .

Further, a purge pipe may be provided by providing a supply gas supply pipe and an exhaust pipe for each space of the optical elements constituting the illumination optical system and the projection optical system.

In addition, for example, in the space of the illumination system champer 1, the reticle chamber 2, the lens barrel 3, and the wafer chamber 4 in FIG. Further, the refining apparatus in the present embodiment is configured such that one refining apparatus is used for one refining apparatus. Although the configuration includes an apparatus, one refining apparatus may be provided for a plurality of exposure apparatuses. In this case, it is possible to reduce the cost of the refining device in improving semiconductor production, and to reduce the set area of the refining device.

Furthermore, in the present embodiment, the configuration in which the same purge gas (helium) is supplied to each space of the illumination system chamber 1, the reticle chamber 2, the lens barrel 3, and the wafer chamber 4 has been described. Is also good. For example, helium may be supplied to the space of the lens barrel 3 and nitrogen may be supplied to another space. In this case, the gas supply system of the present embodiment may be provided for the lens barrel that supplies helium. As described above, when the type of gas is changed for each space, the gas supply system of the present embodiment is provided for a space to which an expensive gas is supplied in consideration of the cost of the supplied gas. Good. That is, depending on the type of gas, it may not be necessary to provide the gas supply system of the present embodiment.

Further, the concentration of the light absorbing substance may be controlled for each space of the optical element constituting the illumination optical system or the projection optical system.

In each of the above embodiments, helium (He) is assumed as the permeated gas. However, any inert gas such as nitrogen (N ₂ ) or a rare gas (argon (Ar), etc.) is evacuated. The absorption of light in the ultraviolet region is small, especially the absorption of F ₂ laser light is so small that it can be ignored. Therefore, in the above embodiment, any inert gas may be used.

Further, in the above embodiment, since the surface 23 a of the wafer stage 23 is substantially flush with the surface of the wafer W, the gas flow is uniformly close to the laminar flow, and the wafer is efficiently processed. Degassing from W can be eliminated. However, it goes without saying that the present invention is effective even when there is a step between the upper surface of the wafer stage and the surface of the wafer.

Further, in order to exclude the light absorbing substance from the optical path, it is preferable to perform a treatment for reducing the amount of outgas from the surface of the structural material in advance. For example, (1) the surface area of the structural material is reduced, (2) the surface of the structural material is polished by mechanical polishing, electrolytic polishing, no polishing, chemical polishing, or GBB (Glass Beads Blasting). Reduce roughness, (3) Blow fluid such as ultrasonic cleaning and clean dry air Clean the surface of structural materials by techniques such as baking, vacuum heating degassing (baking), etc. (4) Electric wire coating materials containing hydrocarbons and halides ゃ Seal members (O-rings, etc.), adhesives Are not installed in the optical path space as much as possible. Also, in FIG. 1, the casing (a cylindrical body or the like) constituting the illumination system chamber 1 and the wafer chamber 4 and the piping for supplying helium gas and the like are made of a material with a small amount of impurity gas (degas), for example, stainless steel. It is desirable to use various polymers such as steel, tetrafluoroethylene, tetrafluoroethylene-terfluoro (alkyl biel ether), or tetrafluoroethylene-hexafluoropropene copolymer.

Similarly, it is desirable that the cables for supplying electric power to the drive mechanisms (reticle blinds, stages, etc.) in each housing are also covered with the above-mentioned material with a small amount of impurity gas (degas). )

As the gas purifier of the present embodiment, the oxygen that has been mixed in the inert gas (0 _2), carbon monoxide (CO), carbon dioxide (C0 _2), hydrogen (H ₂₎ and water ( It is possible to use one that removes impurities such as H ₂₀ ) by chemical adsorption and physical adsorption with a catalyst and an adsorbent, and purifies an inert gas to ultra-high purity. For example, the inert gas purifier UIP-E of Vionitas Japan can be used.

It is apparent that the present invention can be applied not only to a scanning exposure type exposure apparatus but also to a batch exposure type (stepper type) exposure apparatus. The projection optical system provided in these may be not only a catadioptric system as in the above embodiment, but also a dioptric system or a catoptric system. Furthermore, the magnification of the projection optical system may be not only a reduction magnification but also an equal magnification or an enlargement. - Further, as the present invention is an energy beam, and when using the A r F excimer laser beam (wavelength 193 nm), Kr ₂ laser beam (wavelength 146 nm), Ar ₂ laser beam

(Wavelength 126 nm), especially when using vacuum ultraviolet light with a wavelength of about 200 nm to 100 nm, such as a harmonic of a YAG laser or a harmonic of a semiconductor laser, that is, a light in a wavelength range where absorption to oxygen is large. It is valid.

Also excimer laser or F. DFB (Distributed feed back) instead of laser, etc. Infrared region oscillated from semiconductor laser or fiber laser, Alternatively, a single-wavelength laser in the visible region is amplified by a fiber amplifier doped with, for example, erbium (Er) (or both erbium and ytterbium (Yb)), and wavelength-converted to ultraviolet light using a nonlinear optical crystal. Higher harmonics may be used.

For example, if the oscillation wavelength of a single-wavelength laser is in the range of 1.544 to 1.553 m, the 8th harmonic in the range of 193 to 194 nm, that is, almost the same wavelength as the ArF excimer laser Assuming that the oscillation wavelength is in the range of 1.57 to 1.58 μπι, the 10th harmonic in the range of 157 to 158 nm, that is, the ultraviolet light having substantially the same wavelength as the F ₂ laser, can get.

Furthermore, if the oscillation wavelength is in the range of 1.03 to 1.12 πι, a 7th harmonic whose output wavelength is in the range of 147 to 160 nm is output.

If the wavelength is in the range of 9 to 1.106 μπι, an ultraviolet light having a seventh harmonic whose generation wavelength is in the range of 157 to 158 nm, that is, almost the same wavelength as the F ₂ laser can be obtained. As the single-wavelength oscillation laser in this case, for example, a ytterbium-doped fiber laser can be used.

In addition, the use of the exposure apparatus is not limited to an exposure apparatus for manufacturing semiconductors. For example, an exposure apparatus for liquid crystal, which exposes a liquid crystal display element pattern on a square glass plate, and a thin film magnetic head are manufactured. It can be widely applied to an exposure apparatus for performing the above.

When a linear motor is used for the wafer stage and reticle stage, either an air levitation type using an eye bearing or a magnetic levitation type using Lorentz force or reactance force may be used. The stage may be a type that moves along a guide or a guideless type that does not have a guide.

When a planar motor is used as the stage driving device, one of the magnet unit (permanent magnet) and the armature unit is connected to the stage, and the other of the magnet unit and the armature unit is connected to the stage moving surface (base). ).

Also, the reaction force generated by the movement of the wafer stage may be mechanically released to the floor (ground) using a frame member, as described in JP-A-8-166475. The present invention is also applicable to an exposure apparatus having such a structure.

Also, the reaction force generated by the movement of the reticle stage is disclosed in Japanese Patent Application Laid-Open No. 8-33022. As described in Japanese Unexamined Patent Publication No. 4 (Kokai) No. 4, the material may be mechanically released to the floor (ground), using a frame member. The present invention is also applicable to an exposure apparatus having such a structure.

As described above, the exposure apparatus according to the embodiment of the present invention performs various subsystems including each component listed in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. It is manufactured by assembling. Before and after this assembly, adjustments to achieve optical accuracy for various optical systems, adjustments to achieve mechanical accuracy for various mechanical systems, and various electrical The system will be adjusted to achieve electrical accuracy. The process of assembling the exposure apparatus from various sub-systems includes mechanical connection, wiring connection of electric circuits, and piping connection of pneumatic circuits between the various subsystems. It goes without saying that there is an individual assembly process for each subsystem before the assembly process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are ensured. It is desirable to manufacture the exposure equipment in a clean room where the temperature and cleanliness are controlled.

FIG. 6 shows a flowchart of a manufacturing example of a device (semiconductor element, liquid crystal display element, imaging element (CCD, etc.), thin S magnetic head, etc.). As shown in Fig. 6, the device has a step 201 for designing the function and performance of the device, a step 202 for manufacturing a mask (reticle) based on this design step, and a wafer manufactured from a silicon material. Step 203, wafer processing step 204 for exposing a reticle pattern to a wafer by the exposure apparatus of the above-described embodiment, device assembly step (including dicing step, bonding step, and package step) 205, inspection製造 Manufactured through steps 206 and so on.

As described above, according to each of the above-described inventions, high-purity gas is purified by a purifying apparatus having a plurality of gas purifiers, and the purified gas is filled in the space inside the exposure apparatus, thereby generating vacuum ultraviolet light. Even when used as exposure light, it is possible to prevent the exposure light from being attenuated by the light-absorbing substance, and to allow the exposure light to reach the substrate stably with sufficient illuminance and sufficient illuminance uniformity. Further, according to the exposure apparatus of the present invention, exposure accuracy can be improved. Further, according to the method for producing a depiice of the present invention, it is possible to provide a depiice having improved accuracy of a formed pattern.

Claims

The scope of the claims

1. A gas supply system for supplying a predetermined gas to a space in an exposure apparatus through a supply pipe,

A plurality of gas purifiers for purifying the predetermined gas from the gas to be purified,

The supply pipe is connected to each of the plurality of gas purifiers.

2. The gas supply system according to claim 1, wherein

The refined gas is supplied from a refined gas supply source,

The purified gas supply source is a gas cylinder containing the predetermined gas or the space.

3. The gas supply system according to claim 1, wherein

A switching device is provided for selectively connecting any one of the gas purifiers to the space.

4. The gas supply system according to claim 3, wherein

A first measuring device for measuring the concentration of impurities contained in the purified gas purified by the gas purifier or the concentration of the predetermined gas,

The switching device connects the two gas purifiers based on the measurement result by the first measuring device.

5. The gas supply system according to claim 1, wherein

A second measuring device for measuring the concentration of impurities contained in the gas to be purified or the concentration of the predetermined gas upstream of the gas purifier;

A gas discharging device for discharging the gas to be purified from the upstream of the gas purifier based on the measurement result by the second measuring device.

6. The gas supply system according to claim 1, wherein Place Equipped with a gas replenishing device for replenishing gas,

The gas charging device is connected upstream of the gas purifier.

7. A gas supply system for supplying a predetermined gas to a space in the exposure apparatus, wherein the supply device supplies the predetermined gas to the space via a gas supply pipe.

A pulsation suppressor for suppressing pressure fluctuation of the predetermined gas flowing in the gas supply pipe.

8. The gas supply system according to claim 7, wherein the pulsation suppression device is disposed immediately before the exposure device. ''

9. The gas supply system according to claim 7, wherein

The pulsation suppressor suppresses a pressure fluctuation of a gas flowing in the gas supply pipe to 3 mmHg or less.

10. In an exposure apparatus having a plurality of spaces formed in the optical path of the energy beam,

The gas supply system according to claim 1, which supplies a predetermined gas to at least one of the plurality of spaces.

1 1. A method for manufacturing a device including a lithographic process,

A method for manufacturing a device, characterized in that in the lithographic process, a device is manufactured using the exposure apparatus according to claim 10.