WO2004021418A1

WO2004021418A1 - Temperature control method and device, and exposure method and apparatus

Info

Publication number: WO2004021418A1
Application number: PCT/JP2003/010757
Authority: WO
Inventors: Dai Arai; Tomoyuki Yoshida
Original assignee: Nikon Corporation
Priority date: 2002-08-29
Filing date: 2003-08-26
Publication date: 2004-03-11
Also published as: AU2003257538A1; TWI310210B; JPWO2004021418A1; TW200407967A; JP4273421B2

Abstract

A technique of controlling temperature with high precision even if a device thermally variable by the state of a temperature-controlled fluid is used, and an exposure technique are disclosed. The gas collected from a reticle chamber (32) the temperature of which is controlled and a high-purity purging gas from a gas supply source (35) are mixed in a mixing unit (45). The mixed gas is cooled by a refrigerating machine (47), and the humidity is measured by a humidity sensor (49). After the measurement, the gas is supplied to the reticle chamber (32) through a heater (52), a chemical filter (53) absorbing/generating heat depending on humidity, and a dust-removal filter (54). The amount of heat added to the gas by the heater (52) is controlled according to information on temperature given by a temperature sensor (39B) in the reticle chamber (32) and information on humidity given by the humidity sensor (49).

Description

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1 Description Temperature control method and apparatus, and exposure method and apparatus

The present invention relates to a temperature control technique for controlling a temperature in a predetermined space, and relates to various devices such as a semiconductor device, an imaging device (such as a CCD), a liquid crystal display device, a plasma display device, and a thin film magnetic head. It is suitable for use in controlling the temperature in an airtight chamber (chamber or the like) in which an exposure apparatus used in a lithography process for manufacturing or a part of the mechanism is housed. Further, the present invention relates to an exposure technique and a device manufacturing technique using the temperature control technique. Background art

For example, when manufacturing a semiconductor device, an exposure apparatus is used to transfer a pattern formed on a reticle as a mask onto a wafer (or a glass plate or the like) coated with a photosensitive material as a substrate. I have. In an exposure apparatus, the temperature of the environment (atmosphere) in which the exposure apparatus is installed is set so as to transfer the pattern to each layer on the wafer with high accuracy and to maintain high overlay accuracy between different layers. It is necessary to perform exposure in a state where is set within the allowable range with respect to the target temperature. For this reason, the exposure apparatus has conventionally been installed in an environment chamber in which a dust and impurities are removed and a gas whose temperature is precisely controlled is circulated.

Conventionally, in order to control the temperature inside the environmental chamber, the temperature of a gas that is a mixture of gas collected by circulating through the environmental chamber and gas taken in from the outside is controlled by a temperature control unit, and the temperature is controlled by the temperature control unit. Controlled gas was supplied into the environmental chamber through a dust filter. At this time, the temperature of the gas supplied into the environmental chamber was set to the target temperature by feeding back the measured value of the temperature sensor installed in the environmental chamber to the temperature control unit.

As described above, in the conventional exposure apparatus, regardless of the state of the gas (pressure, humidity, etc.) circulated through the environment chamber and the gas recovered by circulating through the environment chamber, the exposure chamber remains in the environment chamber. Only the measured value from the installed temperature sensor was fed back to the temperature control unit to control the air temperature.

Recently, it has been required to further improve the dust resistance in the environmental chamber. Accordingly, not only filters (HEPA filters, etc.) for physically removing fine particles as dust-proof filters, but also organic-based filters have been developed. Chemical filters for chemically removing gases and the like are also being used. However, if a chemical filter is installed in the gas flow path by simply feeding back only the measured value of the temperature in the environmental chamber to the temperature control unit as in the past, the temperature of the gas in the environmental chamber tends to fluctuate. This has the disadvantage of lowering the temperature control accuracy.

The inventors of the present invention have confirmed that one of the factors that lowers the temperature control accuracy is that the chemical filter slightly generates or absorbs heat depending on the level of humidity of the gas passing therethrough. In the future, as the degree of integration and fineness of semiconductor elements further increases, it is necessary to increase the control accuracy of the temperature inside the environmental chamber. In such a case, the required control accuracy may not be achieved. · In addition to chemical fill, when devices that affect the temperature of the gas that comes into contact with the condition of the gas, such as humidity and pressure, are used in various sensors, the necessary temperature control accuracy is similarly reduced. There is a risk that it will not be available.

In this regard, recently, in order to further increase the resolution, the wavelength of the exposure light has been shifted from a KrF excimer laser (wavelength: 248 nm) to an ArF excimer laser (wavelength: 193 nm), which is almost in the vacuum ultraviolet region. Attempts are being made to use shorter wavelength F ₂ lasers (wavelength 157 nm). When the wavelength of the exposure light is shortened in this way, the absorption by impurities such as oxygen in the air and organic gas contained in the air increases, so that the impurity in the light path of the exposure light is increased in order to increase the transmittance for the exposure light. Supply gases such as nitrogen gas and rare gases (helium, neon, argon, krypton, xenon, radon) that are highly removed and have low absorption for short wavelength light (hereinafter referred to as “purge gas”). It is desirable to do. When the purge gas is supplied to the optical path of the exposure light as described above, the optical path of the exposure light is, for example, surrounded by a sub-chamber of the illumination optical system, a reticle chamber surrounding the reticle stage system, a space in the projection optical system, and a wafer stage system. It is also being studied to use a system that divides the gas into a plurality of hermetic chambers such as a wafer chamber and supplies a purge gas from which the impurities are highly removed by independently controlling the temperature in the plurality of hermetic chambers. Even in such a purge gas supply system, when a device such as a chemical filter that causes thermal fluctuations depending on the gas state is used, higher accuracy than a system that simply feeds back the temperature in an airtight chamber is used. Therefore, a method that can perform temperature control is required. Disclosure of the invention

In view of the above, the present invention has as its first object to provide a temperature control technique and an exposure technique that can enhance the temperature control accuracy when performing temperature control of a predetermined space using a temperature-controlled gas. Aim.

Further, the present invention provides a temperature control technology and an exposure technology that can obtain high temperature control accuracy even when a device that causes thermal fluctuation depending on the gas state is used when using a temperature-controlled gas. Is the second purpose.

The temperature control method according to the present invention provides a temperature control method for controlling the temperature in a predetermined space (32) using a gas which is temperature-controlled and which has passed through a chemical filter (53). The temperature of the gas is controlled based on the temperature information of the gas and the information of at least one or more physical quantities that cause a change in the temperature of the gas, and the gas is supplied to the space. It contains information on heat absorption or heat generation in the chemical filter due to the humidity of the gas supplied to the chemical filter.

According to the present invention, it is possible to predict the amount of heat radiation and the amount of heat absorbed in the path (chemical fill) on the way where the gas is supplied to the space by using the above information on the physical quantity. By using the information of the predicted heat release and heat absorption together with the temperature information in the space, the optimal heating of the gas to maintain the temperature in the space within the allowable range for the target temperature, for example, is performed. The amount or endotherm can be set sequentially. As a result, the temperature control accuracy in the space is improved.

In the present invention, at least one of the pressure and the flow rate of the gas can be used as the information of the physical quantity. Further, it is desirable that the information on heat absorption or heat generation in the chemical filter include the humidity of the gas supplied to the chemical filter. For example, if the chemical filter absorbs heat when the humidity of the gas passing through it is high, by raising the temperature of the gas in advance when the humidity is high, the temperature control accuracy in the space is improved.

In addition, in order to control the temperature of the gas supplied to the space, it is desirable to feed-forward the information of the physical quantity to the temperature control unit. By adjusting the temperature of the gas in advance according to the information of the physical quantity, the amount of temperature fluctuation in the space is reduced.

In addition, in order to control the temperature of the gas supplied to the space, it is desirable to feed back temperature information in the space to the temperature control unit. Thereby, the temperature in the space is set to the target value.

The exposure method according to the present invention is an exposure method using the temperature control method according to the present invention, wherein the first object (13) is illuminated with an exposure beam, and the second object is irradiated with the exposure beam through the first object. The temperature of the space (31 to 33, 18) including at least a part of the optical path of the exposure beam of the exposure apparatus for exposing the object (19) or the space communicating with the space is determined by the temperature control method. Control. According to the present invention, it is possible to improve the temperature control accuracy of the first object or the second object.

Next, a temperature control device according to the present invention is a temperature control device that controls the temperature in a predetermined space (32) using a gas that is temperature-controlled and that has passed through a chemical filter (53). A gas supply unit (35, 45, 75A) that supplies gas for temperature control to the space, a temperature sensor (39B) that detects temperature information in the space, and a temperature of the gas A physical quantity sensor (49) for detecting information of at least one physical quantity that causes a change, and a temperature controller (52) for controlling the temperature of the gas based on the temperature sensor and the detection result of the physical quantity sensor And the information on the physical quantity includes information on heat absorption or heat generation in the chemical filter caused by the humidity of the gas supplied to the chemical filter.

According to the present invention, the accuracy of temperature control in the space is improved by using the detection result of the physical quantity sensor together with the detection result of the temperature sensor. For example By feeding back the detection result of the temperature sensor to the temperature control unit and feeding forward the detection result of the physical quantity sensor to the temperature control unit, the temperature in the space can be maintained at the target value with high accuracy.

In the present invention, at least one of the pressure and the flow rate of the gas can be used as the information of the physical quantity.

Further, it is desirable that the physical quantity sensor (49) detects humidity information of the gas supplied to the chemical fill. The temperature control accuracy is improved by using the humidity information.

Next, an exposure apparatus according to the present invention illuminates a first object (13) with an exposure beam, and exposes a second object (19) via the first object with the exposure beam. The temperature control device of the present invention, and the temperature of the space (31 to 33, 18) including at least a part of the optical path of the exposure beam, or the temperature of the space communicating with the space is provided to the temperature control device. Control.

According to the exposure apparatus of the present invention, it is possible to improve the temperature control accuracy of the first object or the second object, or a driving mechanism of the first object or the second object. Therefore, the positioning accuracy and the overlay accuracy of the first object or the second object can be improved.

The device manufacturing method according to the present invention includes a step of transferring and exposing a device pattern formed on a mask as a first object onto a substrate as a second object using the exposure apparatus of the present invention. . The use of the exposure apparatus of the present invention improves overlay accuracy and the like, so that various devices can be mass-produced with high accuracy. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic configuration diagram showing a projection exposure apparatus according to an example of an embodiment of the present invention. FIG. 2 is a diagram showing the purge gas supply mechanism in FIG. FIG. 3 is a diagram showing an example of a temperature control operation in the purge gas supply mechanism of FIG. FIG. 4 is a diagram illustrating an example of a device manufacturing process 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. The present invention provides a method for controlling the temperature in a clean room in which a lithography system is housed, a method for controlling the temperature in an environment chamber in which an exposure apparatus is housed as a whole, The present invention can be widely applied to a case where a gas is divided into closed rooms and a gas having a high transmittance and a temperature is controlled is supplied to each of the closed rooms. In the following embodiments, a case will be described in which the present invention is applied to a step-and-scan type projection exposure apparatus having an airtight chamber to which a temperature-controlled gas is supplied. FIG. 1 is a schematic configuration diagram showing a projection exposure apparatus of this example. In FIG. 1, the projection exposure apparatus of this example uses an Ar F excimer laser having an oscillation wavelength of 193 nm as an exposure light source 1. Light that can be regarded as almost vacuum ultraviolet light is absorbed by impurities such as oxygen, water vapor, hydrocarbon-based gas (carbon dioxide, etc.), organic substances, and halides that are present in the normal atmosphere. In order to prevent the exposure beam from attenuating, it is desirable to keep the concentration of these impurity gases low. The gas in the optical path of the exposure beam is nitrogen (N ₂ ) gas, which is a gas through which the exposure beam passes, or helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon ( It is desirable to replace the gas with a gas that is chemically stable such as Xe) or a rare gas made of radon (Rn) and has a low impurity concentration (hereinafter referred to as “purge gas”). In this example, nitrogen gas is used as an example of the purge gas.

As the exposure beam, for example, the F ₂ laser beam (wavelength 1 57 nm), Kr ₂ laser beam (wavelength 147 nm), or A r ₂ laser beam may be used (wavelength 1 26 nm) or the like. Further, the present invention can be applied to a case where KrF excimer laser light (wavelength: 248 nm) is used as an exposure beam. As the exposure light source, a light source that generates harmonics of a solid-state laser such as a YAG laser, or a single-wavelength laser in the infrared or visible range oscillated by a DFB semiconductor laser or fiber laser, for example, erbium A device that amplifies (Er) (or both erbium and ytterbium (Yb)) with a doped fiber amplifier and converts the wavelength to ultraviolet light using a nonlinear optical crystal can also be used.

Nitrogen gas can be used as a gas through which the exposure beam passes (purge gas) up to a wavelength of about 150 nm even in the vacuum ultraviolet region, but it has a wavelength of 150 nm. The light substantially acts as an impurity with respect to light having a light intensity of less than about. Therefore, it is desirable to use a rare gas as a purge gas for an exposure beam having a wavelength of about 150 nm or less. Among rare gases, helium gas is desirable from the viewpoints of stability of refractive index and high thermal conductivity.However, helium is expensive. May be used. Further, as the purge gas, not only a single kind of gas may be supplied, but also a mixed gas such as a gas obtained by mixing nitrogen and helium at a predetermined ratio may be supplied.

On the other hand, when the exposure beam is a KrF excimer laser (wavelength: 248 nm), air having a low concentration of impurities such as water vapor, organic substances, and halides (so-called dry air) is used as the purge gas. May be supplied.

Hereinafter, the configuration of the projection exposure apparatus of this example will be described in detail. First, exposure light (illumination light for exposure) IL composed of laser light having a wavelength of 193 nm as an exposure beam emitted from the exposure light source 1 is emitted by the shaping optical system 2 in the first sub-chamber 31. The cross-sectional shape is shaped and the light enters the fly-eye lens 3 as an optical integrator (uniformizer or homogenizer) for uniformizing the illuminance distribution. The pupil plane IP (optical Fourier transform plane with respect to the reticle pattern surface), which is the exit side surface of the fly-eye lens 3, has the numerical aperture and the aperture shape of the exposure light for normal illumination, annular illumination, and deformation. A variable aperture stop 4 for switching to illumination or the like is arranged in a rotating manner by a driving motor 43.

Exposure light I L emitted from fly-eye lens 3 passes through variable aperture stop 4, first relay lens 5, mirror 6 for bending optical path 6, second relay lens 7, and field stop.

(Reticle blind) Up to 8, the illumination field of view is defined as a narrow rectangular area. The exposure light IL that has passed through the field stop 8 passes through the first condenser lens 9, the second condenser lens 10, the mirror 11 for bending the optical path, and the third condenser lens 12, and passes through the reticle 13 as a mask. The pattern area of the pattern surface (lower surface) is illuminated. Illumination optics from exposure light source 1, shaping optics 2, fly-eye lens 3, variable aperture stop 4, relay lenses 5, 7, mirror 6, 11, field stop 8, and condenser lenses 9, 10, 10, 12, etc. A shaping optical system 2 to a condenser lens 12 are housed in a sub-chamber 31 as a highly airtight box-shaped airtight chamber. In FIG. 1, the exposure light IL transmitted through the reticle 13 passes through a projection optical system 18 onto a wafer 19 as a substrate to project a pattern of the reticle 13 onto a projection magnification 0 (3 is 1/4, 1/1). 5) to form a reduced image. The wafer 19 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 reticle 13 and the wafer 19 of the present example correspond to the first object and the second object (substrate to be exposed) of the present invention, respectively. In the following, the Z axis is taken parallel to the optical axis PAX of the projection optical system 18, the X axis is taken parallel to the plane of Figure 1 in a plane perpendicular to the Z axis, and the Y axis is taken perpendicular to the plane of Figure 1 explain. In this case, the illumination area on the reticle 13 has a slit shape elongated in the Y direction, and the scanning direction of the reticle 13 and the wafer 19 at the time of exposure is the X direction.

In this example, reticle 13 is held on reticle stage 14, and reticle stage 14 continuously moves reticle 13 in the X direction on reticle base 15, and slightly moves in the X, Y, and rotation directions. To correct the synchronization error of reticle 13. The position and rotation angle of the reticle stage 14 are measured by a moving mirror 16 fixed to the end of the reticle stage 14 and a laser interferometer in the reticle stage drive system 17. Based on the measured values, the reticle The stage drive system 17 controls the operation of the reticle stage 14. A reticle stage system is composed of a reticle stage 14, a reticle base 15 and the like, and this reticle stage system is housed in a reticle room 32, which is a highly airtight box-shaped airtight room.

On the other hand, the wafer 19 is held on a wafer stage 20 via a wafer holder (not shown), and the wafer stage 20 continuously moves the wafer 19 in the X direction on the wafer base 21 and, if necessary, The wafer 19 is step-moved in the X and Y directions. The position and rotation angle of the wafer stage 20 are measured by a moving mirror 22 fixed to the end of the wafer stage 20 and a laser interferometer in the wafer stage drive system 23, and based on the measured values, the wafer stage The drive system 23 controls the operation of the wafer stage 20. Further, based on information on the focus positions (positions in the optical axis AX direction) at a plurality of measurement points on the wafer 19 measured by an auto focus sensor (not shown), the wafer stage 20 is configured to use an auto focus method. By controlling the focus position and tilt angle of 19, the surface of wafer 19 is continuously exposed during exposure. Adjust to the image plane of the shadow optical system 18. A wafer stage system is composed of the wafer stage 20 and the wafer base 21 and the like, and this wafer stage system is housed in a wafer chamber 33 which is a box-shaped airtight chamber with high airtightness.

At the time of exposure, under the control of the main control system 24 (see FIG. 2) which controls the operation of each part of the exposure apparatus, when exposure to one shot area on the wafer 19 is completed, the wafer stage 20 After the next shot area is moved to the scanning start position by the step movement, the reticle stage 14 and the wafer stage 20 are synchronously scanned in the X direction using the projection magnification ratio of the projection optical system 18 as the speed ratio, that is, The operation of scanning the reticle 13 and the shot area on the wafer 19 while maintaining the imaging relationship with the shot area is repeated by the step-and-scan method. Thus, the pattern images on the reticle 13 are sequentially transferred to the respective shot areas on the wafer 19.

As described above, the projection exposure apparatus of this embodiment is provided with a purge gas supply mechanism for replacing gas in the space including the optical path of the exposure light IL with a gas (purge gas) through which the exposure light IL passes. I have. That is, a part of the illumination optical system, the reticle stage system, and the wafer stage system are housed in a sub-chamber 31, a reticle chamber 32, and a wafer chamber 33, respectively, as airtight chambers. The space between the optical members 8 is also a lens chamber as an airtight chamber. A high-purity purge gas is supplied into the sub-chamber 31, the reticle chamber 32, and the wafer chamber 33, and the high-purity purge gas is also supplied to each lens chamber in the projection optical system 18. Supplied. Further, the boundary between the sub-chamber 31 and the upper part of the reticle chamber 32, the lower part of the reticle chamber 32 and the upper part of the projection optical system 18, and the lower part of the projection optical system 18 and the wafer chamber 33 Covers 40, 41, and 42, which are flexible and have excellent gas barrier properties, are provided at the boundary with the upper part of the. Since these boundaries are substantially sealed by the covers 40 to 42, and the optical path of the exposure light is almost completely sealed, the cover includes external impurities on the optical path of the exposure light. There is almost no gas contamination, and the amount of exposure light attenuation is extremely low.

The purge gas supply mechanism of this example includes a gas supply source 35 such as a gas cylinder that accumulates a high-purity purge gas, a purge gas collected from each hermetic chamber by a suction pump, and a high-purity gas supplied from the gas supply source 35. Recovery mixing device for mixing with purge gas 36, The system is composed of an air supply device 38 that controls the temperature of the purge gas and supplies it to each hermetic chamber, and a control unit 34 (see Fig. 2) composed of a computer that supervises and controls the operation of these devices. In this example, since nitrogen gas is used as the purge gas, the gas supply source 35 may be, for example, a device that liquefies and stores high-purity nitrogen and supplies it after vaporization as necessary.

The recovery mixing device 36 converts the gas in the sub-chamber 31, the reticle chamber 32 and the wafer chamber 33 through an exhaust pipe with valves VII, V9, and V10 and an exhaust pipe 75A, respectively, to a substantially steady pressure near the atmospheric pressure. The gas in the plurality of lens chambers of the projection optical system 18 is collected by the gas flow control via the plurality of branched exhaust pipes 71A, the exhaust pipe 75B, and the valve V3. . In the case of gas flow control, a purge gas having a flow rate substantially equal to the flow rate of the gas exhausted from each airtight chamber is supplied to each airtight chamber.

On the other hand, the air supply device 38 is composed of a dust filter for removing fine particles such as a HEPA filter (high efficiency particulate air-filter) or ULPA filter (ultra low penetration air-filter), and a chemical filter such as ammonia or organic gas. 68A and 68B containing chemical filters for removing chemical impurities, and a purge gas (detailed later) whose temperature is controlled passes through the filters 68A and 68B. As a result, the impurities including the fine particles are removed. Then, the purge gas passing through the filter section 68A is supplied to the sub-chamber 31, the reticle chamber 32, via the air supply pipe 69A with the valve V1, and the branched air supply pipes with the valves V7, V5 and V6 respectively. The purge gas supplied into the wafer chamber 33 and passed through the filter section 68B is supplied to the projection optical system 18 through an air supply pipe 69B having a valve V8 and an air supply pipe 70A having a plurality of branch pipes. It is supplied to a plurality of lens chambers. In this case, the valves V1 to V11 are valves that can be opened and closed electromagnetically, and their opening and closing operations are controlled by the control unit 34 (see FIG. 2) independently of each other. The control unit 34 can control not only the opening and closing of the valve but also the size of the valve diameter (amount of throttle of the valve). By controlling the size of the valve diameter, only the supply of the purge gas is shut off. In addition, the supply amount (flow rate per hour) of the purge gas can be controlled. Then, the gas collection operation by the collection and mixing device 36, the purge gas supply operation from the air supply device 38, the opening and closing operations of the valves V1, V5 to V8, and the size of the valve diameter, A gas having a desired flow rate is supplied to the gas chamber at a desired flow rate in any of the hermetic chambers of the sub-chamber 31, the reticle chamber 32, the wafer chamber 33, and the plurality of lens chambers in the projection optical system 18. It is configured so that air can be supplied by a flow control method. The gas in the plurality of lens chambers of the projection optical system 18 may be evacuated in a stepwise manner by a suction method involving decompression to a certain degree of vacuum.

Further, inside the sub-chamber 31, the reticle chamber 32, the projection optical system 18, and the wafer chamber 33, temperature sensors 39A to 39D for detecting the temperature of the purge gas in the respective chambers are provided. Is installed, and temperature information in each airtight room is continuously measured at a predetermined sampling rate by the temperature sensors 39A to 39D. These measurement data are supplied to the control unit 34 in FIG. In this example, the temperature of the purge gas in each hermetic chamber measured by the temperature sensors 39A to 39D is within a predetermined allowable range (for example, ± 0.01) with respect to a predetermined target temperature (for example, 23 ° C.). Purge gas is supplied into each hermetic chamber so that it falls within 00.

Hereinafter, a detailed configuration relating to the temperature control of the purge gas supply mechanism of the present embodiment will be described with reference to FIG. 2, but in FIG. 2, only the reticle chamber 32 of the plurality of airtight chambers is illustrated and the reticle chamber is illustrated. Pipes not communicating with 32, and valves and branched pipes are not shown for convenience of explanation.

In FIG. 2, a control unit 34 controls the operation of each unit under the control of a main control system 24 that controls the overall operation of the exposure apparatus. In the collection / mixing device 36, the gas collected by suction and the high-purity purge gas supplied from the gas supply source 35 through the pipe 72 are mixed in the mixing section 45 (provided with a suction pump). ), And the mixed gas is supplied to a refrigerator 47 via a pipe 46A, where the temperature is once lowered. The mixing section 45 includes a suction pump that sucks gas from an exhaust pipe 75A, and a blower fan that blows the mixed gas through a pipe 46A. Gas supply source

35, the exhaust pipe 75A for gas recovery, and the mixing section 45 correspond to the "gas supply section" of the present invention. However, the present invention can also be applied to a system that does not reuse gas (fluid) circulated in an airtight chamber (predetermined space). Assuming that the target temperature in the reticle chamber 32 as an airtight chamber to be temperature-controlled is 23 ° C, the temperature of the mixed gas in the refrigerator 47 can be lowered to, for example, 2 Ot: several degrees lower than that. . The gas that has passed through the refrigerator 47 receives information on physical quantities (in this example, flow rate, temperature, humidity, and pressure) that may cause a temperature change of the purge gas in the reticle chamber 32 via the pipe 46B. It is supplied to the measuring unit for measuring.

The measuring section includes a flow meter 48 for measuring the flow rate of the gas in the pipe 46 B, a pipe 73 installed between the flow meter 48 and the air supply device 38, and a pipe 73. It comprises a humidity sensor 49, a temperature sensor 50, and a sensor unit including a pressure sensor 51 installed inside. Information on the flow rate measured by the flow meter 48, and the humidity, temperature, and pressure (barometric pressure) of the gas flowing through the pipe 73 measured by the humidity sensor 49, temperature sensor 50, and pressure sensor 51 Information is supplied to the control unit 34 at a predetermined sampling rate.

The gas whose physical quantity information has been measured is supplied to an air supply device 38 via a pipe 73. In the air supply device 38, the gas supplied via the pipe 73 is heated to a predetermined temperature by a heater 52 including a heater, and the heated gas is supplied to a pipe 46C via an ammonia organic system. The gas is supplied to the intake pipe 69A as a high-purity and temperature-controlled purge gas through a chemical filter 53 for removing chemical impurities such as gas and a dust-proof filter 54. The chemical filter 53 and the dust filter 54 correspond to the filter section 68 A in FIG. The purge gas supplied to the air supply pipe 69 A is supplied into the reticle chamber 32. Temperature information measured by a temperature sensor 39 B in the reticle chamber 32 is also supplied to the control unit 34.

The heater 52 corresponds to the “temperature controller” of the present invention. In this example, since the temperature of the gas is once lowered by the refrigerator 47, and then the gas is heated to the target temperature by the heater 52, a relatively simple control of only controlling the heating amount is performed. Response speed and high temperature control accuracy can be obtained. Note that the refrigerator 47 may be omitted, and a temperature controller capable of performing both heating and heat absorption may be provided instead of the heater 52. In this configuration, the temperature control becomes complicated, but the mechanism can be simplified.

The substances that are removed in Chemical Filler 53 are used in projection exposure equipment. A substance that adheres to an optical element and causes fogging, a substance that floats in an optical path of an exposure beam and changes transmittance (illuminance) or illuminance distribution of an illumination optical system or a projection optical system, and a wafer surface ( (Photoresist) and the like, which deforms the pattern image after development processing. As the chemical filter 53, an activated carbon filter (for example, Gigasoap (trade name) manufactured by NITTA CORPORATION) can be used, and an ion exchange membrane type filter (for example, Ebara Corporation) EP IX filter (trade name) can be used), or zeolite filter, or a filter combining these. These chemical filters also remove silicon-based organic substances such as siloxane (a substance whose axis is a Si-O chain) or silazane (a substance whose axis is a Si-N chain).

In this example, information on the temperature T of the purge gas measured by the temperature sensor 39 B in the reticle chamber 32 and the flow meter 48, the humidity sensor 49, the temperature sensor 50, and the pressure sensor 51 in the collection and mixing device 36. Based on the information of the measured gas flow rate F, humidity H, temperature U, and pressure P, the control unit 34 allows the temperature in the reticle chamber 32 to be within the allowable range with respect to the above target temperature (= TC). The heating amount S of the gas in the heater 52 per unit time is controlled so as to fall within the range. In this case, since the reticle chamber 32 is disposed downstream of the gas with respect to the heater 52, information on the temperature T measured by the temperature sensor 39B in the reticle chamber 32 is fed back to the heater 52. ing. On the other hand, since the recovery mixing device 36 (physical quantity measurement unit) is located upstream of the gas with respect to the heater 52, the flow meter 48, humidity sensor 49, temperature sensor 50, and pressure sensor 51 of the measurement unit are provided. The information of the gas flow rate F, the humidity H, the temperature U, and the pressure P, which are measured at, are fed forward to the heater 52.

That is, in order to feed back the temperature T of the temperature sensor 39B, as an example, the difference between the target temperature TC in the reticle chamber 32 and the temperature T is defined as ΔΤ (= T-TC), and this difference itself is a predetermined value of the difference. Integration at the integration time Δt (actually the sum of digital data, the same applies below) t ATd t and its differential (actually the digital data difference, the same applies hereinafter) dATZd t to heater KT1, kT2, k are the coefficients for calculating the amount of change in the heating amount S per unit time in 52, respectively. T3. These coefficients are experimentally determined in advance in accordance with the level of an allowable range for a target temperature in the reticle chamber 32 and stored in the main control system 24. Before the exposure process starts, the main control system 24 controls the control unit 34. Is set to The controller 34 obtains a change AS1 of the heating amount S in the heater 52 due to the temperature Β of the temperature sensor 39 Β from the following equation.

△ S l = kT l-AT + kT2Δt + kT3dΔΤ / dt

… (1)

Next, in order to feed forward the flow rate F, humidity H, temperature U, and pressure P of the gas measured by the flow meter 48, the humidity sensor 49, the temperature sensor 50, and the pressure sensor 51, for example, The reference values of the physical quantities (for example, the average value of the measured values in a certain exposure step) are set as FC, HC, UC, and PC, respectively. For simplicity, the differences between these reference values and the measured values are (= F-FC), Δ (= H—HC), AU (= U—UC), and ΔΡ (= Ρ—PC). Coefficients for obtaining the amount of change in the amount of heating S in the heater 52 from these differences are denoted by kF1, kH1, kU1, and kPl, respectively. These coefficients are also set in the control unit 34 from the main control system 24 in advance. These coefficients are experimentally determined in advance in accordance with the level of an allowable range for a target temperature in the reticle chamber 32 and stored in the main control system 24, and are controlled by the main control system 24 before the exposure process starts. Set to 34. The controller 34 obtains a change ΔS 2 of the heating amount S in the heater 52 due to the gas flow rate F, humidity H, temperature U, and pressure P from the following equation.

Δ S 2 = k F 1-Δ F + kH 1-ΔΗ + kU 1-AU + k P 1

… (2)

In this example, as shown in FIG. 2, a chemical filler 53 is disposed between the heater 52 (temperature control unit) and the reticle chamber 32 (airtight chamber), and the chemical filler 53 passes through the inside. When the humidity of the gas rises, heat is absorbed and the temperature of the discharged gas tends to decrease. In addition, the chemical filter 53 tends to generate heat when the humidity of the gas passing therethrough decreases, and the temperature of the discharged gas tends to increase. This is because the chemical filter 53 acts to keep the humidity inside the filter at a certain level. Therefore, in this example, the humidity Η measured by the humidity sensor 49 is When the difference Δ 1 (= H-HC) from the reference value HC becomes +, the change amount AS 2 of the heating amount is set to +, and when the difference ΔΗ becomes −, the change amount AS 2 is set to −. Is set to a predetermined positive value. In this case, for example, the humidity when heat absorption or heat generation occurs in the chemical filter 53 may be experimentally measured in advance, and this humidity may be used as the reference value HC.

Note that this reference value HC is determined individually according to the type of chemical filter 53 used (the composition of the chemical filter, material, etc.), and is used depending on the type of filler used. Further, in the case where the heat absorption and heat generation capability of the chemical filter to be used fluctuates with time, it is preferable that the above-mentioned reference value H C is also fluctuated according to the fluctuation of the capability.

In order to obtain the change の S 2 of the heating amount S more precisely, the change AS 2 may be obtained in the form of a linear function or a higher-order function with respect to the difference ΔΗ. . Further, the variation △ S2 may be obtained in consideration of the integration ίAHdt of the difference ΔΗ at a predetermined integration time Δt and the differentiation dΔΤΖοΙt of the difference. In order to further improve the control accuracy of other flow rates F, temperature U, and pressure P, the amount of change in the heating amount S should be calculated taking into account not only the difference value but also the integral value and the derivative value. You may.

Further, when the flow rate F increases, the temperature decreases with the same heating amount, so the heating amount S may be increased in advance. Therefore, the value of the coefficient kF1 for obtaining the change amount of the heating amount S with respect to the flow rate F may be set to a predetermined (eg, experimentally determined) positive value. On the other hand, when the temperature U is high, the heating amount S may be small, and thus the coefficient kUl may be set to a predetermined negative value.

As described above, in this example, the flow rate F, humidity H, temperature U, and pressure P of the gas are measured, and from these state quantities, the energy state quantity of the gas, ie, entropy-(enthalpy) (Unit is energy (J or cal)). At this time, the amount of change in the amount of heating S in the heater 52 is corrected so that the amount of heat generated by the steam in the path from the humidity sensor 49 to the reticle chamber 32 is measured in advance. AS 2 may be set.

The temperature control unit 34 in FIG. 2 calculates the change ΔS 1 of the heating amount S in equations (1) and (2), The change AS of the heating amount S in the heater 52 is calculated by adding ΔS2 as in the following equation.

Δ S = A S 1 + △ S 2… (3)

Then, the temperature controller 34 sends a control signal to the heater 52 so as to change the heating amount S by the change AS. The calculations of equations (1) to (3) and the supply of the control signal for the change in the heating amount S to the heater 52 are continuously performed at a predetermined sampling rate (for example, about several tens Hz to several kHz) during the exposure process. Done in

Accordingly, the temperature of the purge gas in the reticle chamber 32 is kept within an allowable range with respect to the target temperature, and exposure can be performed with high accuracy.

Specifically, FIGS. 3 (A), 3 (B), and 3 (C) show the temperature T (measured value of the temperature sensor 39B) in the reticle chamber 32 and the heating amount S in the heater 52 in FIG. , And an example of a change in the humidity S measured by the humidity sensor 49.

The horizontal axis of (C) is the elapsed time! ; For example, as shown by the solid line 55 A in FIG. 3A, when the temperature T in the reticle chamber 32 shifts from the target value TC at the time point t1, by feeding back the temperature T, the solid line in FIG. As shown by 56 A, the heating amount S of the heater 52 shifts from the reference value SC from the time point t2 immediately after that, and the temperature T returns to the target value TC.

Also, as shown by the solid line 57 in FIG. 3 (C), when the humidity H measured by the humidity sensor 49 fluctuates from the reference value HC from the time t3, the fluctuation cancels out heat absorption and heat generation in the chemical fill 53. Then, the heating amount S of the heater 52 changes as shown in FIG. 3 (B). Thereby, the temperature T in the reticle chamber 32 is maintained at the target value TC. On the other hand, when there is no feedforward of the humidity H, as shown by the dotted line 55B in FIG. 3A, the temperature T in the reticle chamber 32 fluctuates due to heat absorption and heat generation in the chemical filter 53. . This fluctuation is gradually reduced by the feedback of the temperature T, but the accuracy of the temperature control deteriorates.

Thus, in this example, based on the humidity H of the gas measured in front of the heater 52, the heat absorption and heat generation in the chemical filter 53 installed next to the caro heater 52 are cancelled. Since the heating amount S is controlled, even if the chemical filter 53 is used, the amount of temperature fluctuation in the reticle chamber 32 can be suppressed, and high temperature control accuracy can be obtained. Can be. Furthermore, since the heating amount S in the heater 52 is controlled by using the gas flow rate F, the temperature U, and the pressure P measured in front of the heater 52, higher temperature control accuracy is obtained. Can be

Further, in this example, the measured humidity H is fed forward to the heater 52, so that the influence of the chemical filter 53 can be canceled before the temperature fluctuation occurs in the reticle chamber 32. Therefore, higher temperature control accuracy can be obtained.

In the example of FIG. 2, the humidity H of the gas is measured in the collection and mixing device 36 before the heater 52, but the humidity H may be measured in the chemical filter 53. . In this case, the measured value of the humidity H is fed back to the heater 52, but the heating amount of the heater 52 can be controlled based on the measured value before the reticle chamber 32 even in this case. In addition, the temperature control accuracy in the reticle chamber 32 is improved as compared with the case where the value of the humidity H is not taken into consideration.

In the example of FIG. 2, if the gas flow rate F and the pressure P measured in the collection and mixing device 36 can be considered to be almost constant, or the reticle chamber caused by the gas flow rate F and the pressure P If the amount of heat fluctuation within 32 is within an allowable range, the values of the gas flow rate F and the pressure P may not necessarily be used to control the heater 52.

In FIG. 1, the supply of purge gas to the three hermetic chambers including the sub-chamber 31, the reticle chamber 32, and the wafer chamber 33 and the supply of the purge gas to the projection optical system 18 is shown in FIG. 2 while controlling the valves. Although such a purge gas supply mechanism is commonly used, a purge gas supply mechanism as shown in FIG. 2 may be provided independently for each of the projection optical system and each hermetic chamber. If a purge gas supply mechanism is provided for each supply destination, the temperature of the supplied purge gas can be controlled independently for each supply destination, and its temperature control accuracy (for example, if the control accuracy is ± 0.1 ° or ± The force at 0.01 ° can also be set independently for each supply destination.

In the purge gas supply mechanism of the present example, the concentration of the oxygen gas in the impurities inside each of the sub-chamber 31, the reticle chamber 32, the projection optical system 18, and the wafer chamber 33 is set. An oxygen concentration sensor (not shown) for detection is installed, and information on the concentration of oxygen as an impurity in each hermetic chamber is continuously obtained at a predetermined sampling rate. It is being measured. These measurement data are also supplied to the control unit 34 in FIG. In this example, in parallel with the above-described temperature control, if any one of the oxygen concentration sensors detects oxygen gas having a concentration equal to or higher than a predetermined allowable concentration, the oxygen gas concentration is controlled by a command from the control unit 34 in FIG. The proportion of the high-purity purge gas from the gas supply source 35 in the gas mixture supplied to the hermetic chamber where the oxygen gas was detected is increased until the oxygen gas concentration falls below the allowable concentration. As the oxygen concentration sensor, for example, a polarographic oxygen concentration meter, a zirconia oxygen concentration meter, a yellow phosphorus emission type oxygen sensor, or the like can be used. As the sensor for detecting the impurities, used for other oxygen concentration sensor, ozone (0 _3), water vapor, and a sensor for detecting carbon dioxide (C_〇 ₂₎ hydrocarbon molecules such as May be.

When the present invention is applied to, for example, temperature control of a clean room (airtight room) in which a lithography system is installed, gas supplied to the clean room is taken in from, for example, outside air through a dustproof filter or the like and dried. It becomes air (dry air-). Similarly, when the present invention is applied to, for example, temperature control of an environmental chamber (airtight chamber) in which an exposure apparatus is housed as a whole, the gas supplied to the environmental chamber is supplied to a dustproof filter or the like in a clean room. It becomes the air taken in through the air (dry air).

Further, in each of the above embodiments, the present invention is applied to a step-and-scan type projection exposure apparatus, but the present invention is also applicable to a batch exposure type projection exposure apparatus such as a stepper. Can be. The magnification of the projection optical system provided in these projection exposure apparatuses is not limited to reduction, but may be equal magnification or enlargement. Further, the present invention can be applied to, for example, an immersion type exposure apparatus disclosed in International Publication No. WO 99/49504. Further, the present invention relates to an exposure operation and an alignment operation (mark detection operation), as disclosed in, for example, International Publication No. 98/241115 pamphlet and No. 988Z40971 pamphlet. The present invention can also be applied to an exposure apparatus having two wafer stages capable of performing the steps substantially in parallel. Further, it is apparent that the present invention can be applied to a proximity type exposure apparatus or the like that does not use a projection optical system.

In the illumination optical system and the projection optical system according to the above-described embodiment, each optical member is After adjustment is performed by arranging the support member in the lens barrel in a positional relationship, the support member and the lens barrel are set on a column (not shown) to assemble. Along with this assembly adjustment, the stage system, laser interferometer, and a purge gas supply mechanism for purging the inside of the apparatus are assembled and adjusted, and each component is electrically, mechanically, or optically adjusted. By linking, the projection exposure apparatus of the above embodiment is assembled. In this case, it is desirable to perform the work in a clean room where temperature control has been performed. 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, a wafer W is first manufactured from a silicon semiconductor or the like. Thereafter, a photoresist is applied on the wafer W (step S10), and in the next step S12, the reticle (tentatively, R) is placed on the reticle stage of the projection exposure apparatus of the above embodiment (FIG. 1). 1), and the pattern (represented by the symbol A) of the reticle R 1 is transferred (exposed) to all the shot areas SE on the wafer W by the scanning exposure method. At this time, double exposure is performed as necessary. The wafer W is, for example, a wafer having a diameter of 300 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. This is a rectangular area. Next, in step S14, a predetermined pattern is formed in each shot area SE of the wafer W by performing development, etching, ion implantation, and the like.

Next, in step S16, a photoresist is applied onto the wafer W, and then in step S18, a reticle (assuming that a reticle (provisionally R) is placed on the reticle stage of the projection exposure apparatus of the above embodiment (FIG. 1). 2) and transfer (exposure) the pattern of the reticle R 2 (represented by the symbol B) to each shot area SE on the wafer W by the scanning exposure method. Then, in step S 20, a predetermined pattern is formed in each shot area of the wafer W by performing development, etching ion implantation, and the like on the wafer W.

The above-described exposure step to pattern formation step (step S16 to step S20) are repeated as many times as necessary to manufacture a desired semiconductor device. Then, a dicing process (step S22) for separating each chip CP on wafer W one by one, The semiconductor device SP as a product is manufactured through the bonding step, the packaging step, and the like (step S24).

According to the device manufacturing method of this example, since the temperature control accuracy of the reticle and the wafer of the projection exposure apparatus can be increased, the overlay accuracy and the like can be increased, and a more highly integrated and high-performance semiconductor device (integrated circuit) the still _c can be prepared in high yield, without being restricted to an exposure apparatus for manufacturing semiconductor devices use of the exposure apparatus of the present invention, for example, a liquid crystal display is formed on a square glass plate The present invention can be widely applied to an exposure apparatus for manufacturing various devices such as an element or an exposure apparatus for a display apparatus such as a plasma display, an imaging element (such as a CCD), a micro machine, a thin film magnetic head, and a DNA chip. 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. .

Note that the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention. In addition, all disclosures of Japanese Patent Application No. 2002-2509, filed on August 29, 2002, including the specification, claims, drawings, and abstract. The contents are incorporated in the present application by reference as they are. Industrial potential

According to the present invention, since the temperature of the fluid for temperature control is controlled based on information of at least one or more physical quantities that cause a temperature change of the fluid for temperature control, the space is supplied with the fluid. For example, it is possible to improve the temperature control accuracy inside a chamber or the like accommodating the exposure apparatus. Therefore, when the present invention is applied to the exposure method and apparatus, the temperature control accuracy of the first object (mask) and the second object (substrate) at the time of exposure can be improved. Can be manufactured.

Further, according to the present invention, when a device that causes heat fluctuation due to the humidity of the gas as a fluid, such as a chemical fill, is used, the temperature is measured using the measurement information of the humidity. By performing the control, high temperature control accuracy can be obtained. In addition, the temperature information in the space to be controlled is fed back, and the information on the physical quantity is fed forward to control the amount of heat absorbed and generated by the temperature control unit, so that the temperature in the space can be increased to the target value at a high speed. Can be set with high control accuracy.

Claims

The scope of the claims

1. A temperature control method for controlling the temperature in a predetermined space by using a gas that is temperature-controlled and that has passed through a chemical filter.

Controlling the temperature of the gas based on temperature information in the space and information of at least one physical quantity causing a change in the temperature of the gas, and supplying the gas to the space;

The temperature control method, wherein the information on the physical quantity includes information on heat absorption or heat generation in the chemical filter caused by humidity of gas supplied to the chemical filter.

2. The temperature control method according to claim 1, wherein the information on the physical quantity further includes at least one of a pressure and a flow rate of the gas.

3. The temperature control method according to claim 1, wherein the information on heat absorption or heat generation in the chemical fill includes humidity of the gas.

4. The temperature control method according to claim 1, wherein information on the physical quantity is fed forward to control the temperature of the gas supplied to the space.

5. The temperature control method according to any one of claims 1 to 4, wherein the temperature information in the space is fed back to control the temperature of the gas supplied to the space.

6. An exposure method using the temperature control method according to any one of claims 1 to 5,

A space including at least a part of an optical path of the exposure beam of an exposure apparatus that illuminates a first object with an exposure beam and exposes a second object via the first object with the exposure beam, or a space communicating with the space An exposure method, wherein the temperature of the substrate is controlled by the temperature control method.

7. A temperature control device that controls the temperature in a predetermined space using a gas that is temperature-controlled and that has passed through a chemical filter.

A gas supply unit that supplies a gas for temperature control to the space, A temperature sensor for detecting temperature information in the space,

A physical quantity sensor that detects information of at least one or more physical quantities that cause a change in the temperature of the gas;

A temperature controller that controls the temperature of the gas based on the detection results of the temperature sensor and the physical quantity sensor,

The temperature control device, wherein the information on the physical quantity includes information on heat absorption or heat generation in the chemical fill that occurs due to the humidity of the gas supplied to the chemical fill.

8. The temperature control device according to claim 7, wherein the information on the physical quantity further includes at least one of a pressure and a flow rate of the gas.

9. The temperature control device according to claim 7, wherein the physical quantity sensor detects the humidity of the gas.

10. The information of the physical quantity from the physical quantity sensor is fed forward to the temperature control section, and the temperature information in the space from the temperature sensor is fed back to the temperature control section. The temperature control device according to 7, 8, or 9.

1 1. An exposure apparatus that illuminates a first object with an exposure beam, and exposes a second object through the first object with the exposure beam,

Having a temperature control device according to any one of claims 7 to 10,

An exposure apparatus, wherein a temperature of a space including at least a part of an optical path of the exposure beam or a space communicating with the space is controlled by the temperature control device.

12. A step of transferring and exposing a device pattern formed on a mask as the first object onto a substrate as the second object, using the exposure apparatus according to claim 11. Device manufacturing method.