JP2010087312A - Exposure apparatus, and method of manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure apparatus efficiently operated by preventing change of an image formation position and degradation of resolution, eliminating a recovery time from damage of a spectrum purification filter, and reducing a maintenance time. <P>SOLUTION: This exposure apparatus includes an EUV light source emitting EUV light, and an illumination optical system illuminating an original plate with the EUV light emitted from the EUV light source. The exposure apparatus further includes: an optical filter formed of a thin film transmitting the EUV light and blocking light other than the EUV light, and arranged in an optical path of the EUV light; and a deterioration detection means to detect deterioration of the optical filter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure apparatus that uses EUV light, which is extreme ultraviolet light, as a light source.

  Conventionally, reduction projection exposure using ultraviolet rays has been performed as a printing (lithography) method for manufacturing fine semiconductor elements such as semiconductor memories and logic circuits. The minimum dimension that can be transferred by reduction projection exposure is proportional to the wavelength of light used for transfer and inversely proportional to the numerical aperture of the projection optical system. For this reason, the wavelength of light used for transferring fine circuit patterns has been shortened, and ultraviolet light used for mercury lamp i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), and ArF excimer laser (wavelength 193 nm). The wavelength of light has become shorter.

However, semiconductor elements are rapidly miniaturized, and there is a limit in lithography using ultraviolet light as described above. Therefore, a reduction projection exposure apparatus using EUV light, which is extreme ultraviolet light having a wavelength of 10 nm or more and 13.5 nm or less, which is shorter than ultraviolet light, in order to efficiently burn a very fine circuit pattern of less than 0.1 μm. Has been developed.
In the EUV light region, absorption by a substance becomes very large, so it is not possible to use a lens optical system that utilizes light refraction as used in visible light or ultraviolet light. In an exposure apparatus using EUV light, reflection optics are used. A system is used. In this case, a reflective reticle in which a pattern to be transferred by an absorber is formed on a mirror is also used.

  As a reflection type optical element constituting the reflection optical system of the exposure apparatus using EUV light, there are a multilayer mirror and a grazing incidence total reflection mirror. The oblique incidence total reflection mirror is a mirror that utilizes the fact that total reflection occurs when used in oblique incidence where EUV light is incident on the surface because the real part of the refractive index is slightly smaller than 1 in the EUV region. Usually, a high reflectivity of several tens of percent or more can be obtained at an oblique incidence within several degrees as measured from the surface. However, the degree of freedom in optical design is small, and it is difficult to use a grazing incidence total reflection mirror in a projection optical system.

  On the other hand, as a mirror for EUV light used at an incident angle close to normal incidence, a multilayer mirror in which two kinds of substances having different optical constants are alternately stacked is used. Molybdenum and silicon are alternately laminated on the surface of a glass substrate polished to a precise surface shape. As for the thickness of the layer, for example, the thickness of the molybdenum layer is 0.2 nm, the thickness of the silicon layer is about 0.5 nm, and the number of stacked layers is about 20 pairs. The sum of the thicknesses of the two types of substances is called the film cycle. In the above example, the film period is 0.2 nm + 0.5 nm = 0.7 nm. When EUV light is incident on such a multilayer mirror, EUV light having a specific wavelength is reflected.

When the incident angle is θ, the wavelength of the EUV light is λ, and the film period is d, approximately Bragg's equation 2 × d × sin θ = λ
Only EUV light with a narrow bandwidth centered on λ that satisfies the above relationship is efficiently reflected. A multilayer mirror formed of molybdenum and silicon usually has a high reflectance of light having a wavelength of 13.5 nm, and the bandwidth is about 0.6 to 1 nm centering on this. The reflectivity of the reflected EUV light is about 0.7 at the maximum, and the EUV light that is not reflected is absorbed in the multilayer film or the substrate, and most of the energy becomes heat. As described above, since the multilayer mirror has a larger light loss than the visible light mirror, it is necessary to minimize the number of mirrors.

  A reduction projection exposure apparatus using EUV light is composed of an EUV light source, an illumination optical system, a reflective reticle, a projection optical system, a reticle stage, a wafer stage, an alignment optical system, a vacuum system, and the like. The light source is used. This is to irradiate a target material placed in a vacuum vessel with high-intensity pulsed laser light to generate high-temperature plasma, which becomes a light emitting point, and uses EUV light with a wavelength of about 13 nm, for example, emitted from this It is.

As the target material, a metal thin film, an inert gas, a droplet, or the like is used, and is supplied into the vacuum container by means such as a gas jet. As another type of EUV light source, a discharge plasma type light source may be used. A normal incidence multilayer mirror used as an optical element constituting an exposure apparatus using EUV light has a high reflectivity for EUV light having a wavelength of 13.5 nm. For this reason, among the light emitted from the EUV light source, EUV light having a wavelength of 13.365 nm to 13.635 nm centering on a wavelength of 13.5 nm is used as the projection exposure. The EUV light from this light emitting point is condensed at the condensing point by the condensing mirror, and after diverging from the condensing point, it is introduced into the illumination optical system. The illumination optical system includes a plurality of multilayer films or oblique incidence mirrors, an optical integrator, and the like, and uniformly illuminates the reticle.
JP 2003-229298 A JP 2006-279036 A

  However, in the above-described conventional projection exposure apparatus, the EUV light source emits light having a wavelength different from that used for exposure in the vicinity of 13.5 nm regardless of whether the EUV light source is a laser plasma system or a discharge plasma system. To do. A part of the light of 130 to 400 nm reaches the resist, which is a photosensitive member on the wafer, without being absorbed by the optical elements of the projection exposure apparatus. Remarkably lowered. Further, a part of visible light and infrared light having a wavelength of 400 nm or more is absorbed by the optical element, reticle, or wafer of the projection exposure apparatus, and this becomes a heat load and raises these temperatures. As a result, it expands and changes its shape, resulting in performance degradation such as a change in imaging position and a decrease in resolution.

  On the other hand, Patent Document 1 and Patent Document 2 propose using a spectral purification filter that is an optical filter for transmitting EUV light and blocking infrared, visible, and ultraviolet light emitted from plasma. ing. This spectral purification filter is usually formed of a thin film such as zirconium having a thickness of about 50 to 250 nm or a thin film in which a zirconium thin film and a silicon thin film are laminated. However, since it is an extremely thin film, its heat capacity is extremely small, and it is a thin film, and since it is placed in a vacuum or under a pressure of about 1 Pa, cooling due to heat conduction is extremely small, and it tends to become high temperature due to light irradiation from plasma. .

  For example, since the melting point of zirconium forming the thin film is 2125K, it is used so as not to exceed this temperature. However, even below the melting point, it gradually sublimates and thins, and the function of blocking the infrared, visible, and ultraviolet light emitted from the plasma, which is the original function, is reduced. Degradation occurs in which the rate increases. When the deteriorated spectral purification filter is used without replacement, the image forming position in the projection exposure apparatus and the resolution are lowered, and the mechanical strength such as pressure resistance is reduced and damaged. To do. Furthermore, the projection exposure apparatus cannot be operated, and it takes a long time to recover the damaged object.

  Further, even when the temperature of the spectral purification filter is suppressed as described above and does not sublime, the chamber in which the spectral purification filter is disposed is usually evacuated but contains a small amount of hydrocarbon gas. It is. By irradiating EUV light or ultraviolet light in this environment, deterioration occurs in that carbon adheres to the surface of the spectrum purification filter and the transmittance of the EUV light decreases. When the spectral purification filter having such a deterioration is used without replacement, the intensity of the EUV light that is the exposure light is reduced and the throughput of the projection exposure apparatus is reduced. When the throughput is extremely reduced, the projection exposure apparatus is temporarily stopped and maintenance is performed. However, there are several possible causes such as deterioration of the EUV light source and other optical elements, so restoration is not easy. It took a lot of time.

Therefore, the exposure apparatus of the present invention provides an exposure apparatus that prevents the change of the imaging position and the resolution, eliminates the recovery time from the damage of the spectrum purification filter, shortens the maintenance time, and operates efficiently. The purpose is to do.

  In order to achieve the above object, an exposure apparatus according to the present invention includes an EUV light source that irradiates EUV light, and an illumination optical system that illuminates the original with the EUV light irradiated from the EUV light source. An optical filter comprising a thin film that transmits EUV light and blocks light other than the EUV light, and has an optical filter provided in an optical path of the EUV light, and a deterioration detecting means for detecting deterioration of the optical filter, To do.

  According to the present invention, it is possible to prevent the change of the imaging position and the resolution, eliminate the recovery time from the damage of the spectrum purification filter, shorten the maintenance time, and operate efficiently.

Embodiment 1 of the present invention will be described below with reference to the accompanying drawings.
FIG. 6 is a schematic block diagram of an exposure apparatus according to an embodiment of the present invention.
Light emitted from the light source chamber 6 having a light source is projected onto a reticle 23 as an original through an illumination optical system chamber 7 having an illumination optical system disposed inside the vacuum chamber 26. As the light source inside the light source chamber 6, for example, EUV light which is extreme ultraviolet light having an oscillation spectrum in the range of 10 nm to 13.5 nm (soft X-ray region) is used as exposure illumination light.

The reticle 23 is held on a reticle stage 23 a, and the pattern of the reticle 23 is projected onto a wafer 25 as a substrate via a projection optical system 24. A resist is applied to the surface of the wafer 25 which is a sample to be exposed, and shots formed in the exposure process are arranged. The wafer 25 is held by a wafer stage 25a, and the inside of the vacuum chamber 26 is kept at a high degree of vacuum by a vacuum pump 27.
As the exposure apparatus of the present embodiment, for example, a step-and-scan type scanning projection exposure apparatus in which the reticle 23 and the wafer 25 are controlled so that the wafer 25 is scanned and exposed is used.

Next, a projection exposure apparatus using EUV light according to the first embodiment of the present invention will be described with reference to the sectional view of FIG.
The EUV light source 1 is provided inside the EUV light source chamber 6, is a discharge plasma type EUV light source, and is a light source that emits EUV light that is extreme ultraviolet light. The EUV light source 1 is not limited to the discharge plasma method, and may be a laser plasma method. For example, Xe gas supplied from the nozzle 1-a constituting the EUV light source 1 and a high voltage applied to the electrode 1-b cause discharge. Furthermore, a high-density plasma 1-c is generated by a pinch action by a self-magnetic field of a charged particle flow, and EUV light 1d, ultraviolet light, visible light, and infrared light are generated from the plasma plasma 1-c. The EUV light 1d generated from the plasma 1-c passes through a debris filter 2 for removing debris particles, and is reflected and collected by a condensing mirror 3 composed of a double mirror whose reflection surface is a spheroid. Condensed to point 4.

  The spectral purification filter 5 that is an optical filter is formed of a thin film that transmits the EUV light 1d and blocks light other than the EUV light, and is provided between the EUV light source chamber 6 and the illumination optical system chamber 7 in the optical path of the EUV1d light. It is done. The spectrum purification filter 5 is an optical filter made of, for example, a 150 nm-thickness zirconium thin film that transmits EUV light 1d and blocks ultraviolet light, visible light, and infrared light. The EUV light 1d has a property of being absorbed by gas, and the EUV light source 1, the debris filter 2, and the collecting mirror 3 are disposed inside the light source chamber 6 in order to prevent absorption by the gas. The light source chamber 6 is evacuated by a vacuum pump 27 shown in FIG.

  The illumination optical system provided in the illumination optical system chamber 7 is an optical system that illuminates the reticle 23 with EUV light 1d emitted from the EUV light source 1, and includes an illumination system first mirror 8, an optical integrator 9, and an optical element (not shown). Have The EUV light 1d that has reached the condensing point 4 is reflected by the illumination system first mirror 8, and then enters the optical integrator 9, and further passes through an optical element (not shown) to uniformly reach the reticle 23 shown in FIG. Illuminate.

  The illumination optical system chamber 7 is evacuated by the vacuum pump 27 shown in FIG. 6 in the same manner as the light source chamber 6 in order to prevent the EUV light 1d from being absorbed by the gas. In addition, although the inside of the light source chamber 6 is exhausted by the vacuum pump 27, there is a gas supplied from the nozzle 1-a, and a trace amount of hydrocarbon in the gas supplied from the nozzle 1-a is optical. This causes carbon to adhere to the element. Therefore, in order to prevent this gas from flowing into the illumination optical system chamber 7, the spectrum purification filter 5 as an optical filter is provided between the light source chamber 6 and the illumination optical system chamber 7 as a vacuum partition. Thereby, the light source chamber 6 in which the EUV light source is provided is separated from the illumination optical system chamber 7 in which the illumination optical system is provided. A radiation thermometer 10 which is a deterioration detecting means for detecting deterioration of the spectrum purification filter 5 is a means for measuring the temperature of the thin film of the spectrum purification filter 5 and measures the temperature of the substance from infrared rays radiated from the substance by infrared thermography. .

  When the exposure apparatus of the first embodiment using the EUV light 1d shown in FIG. 1 is operated, the temperature of the spectrum purification filter 5 is increased by the EUV light 1d irradiated from the plasma 1-c. However, when used for a long time, the thin film of the spectral purification filter 5, for example, zirconium gradually sublimates and becomes thin, the transmittance of ultraviolet light, visible light, and infrared light to be blocked increases, and the mechanical strength is increased. descend.

  At the same time, since the heat capacity of the thin film is reduced and the heat conduction is reduced, the temperature rise of the spectral purification filter 5 during operation is larger, and the ultimate temperature is higher than when the spectral purification filter 5 is first used. . In advance, it is separately examined how the transmittance, mechanical strength, and ultimate temperature of the spectral purification filter 5 with the sublimation of the thin film material are changed. Further, a reference ultimate temperature that is an ultimate temperature corresponding to a reference transmittance or a reference mechanical strength of ultraviolet light, visible light, and infrared light that can be used by the spectrum purification filter 5 is obtained.

  By using the spectrum purification filter 5 for a long time, the temperature reached by the spectrum purification filter 5 becomes high. When the reference temperature is reached, the operation of the exposure apparatus of the first embodiment is stopped, and the spectrum purification filter 5 is turned on. Replace with a new one. With such a configuration and method, in the first embodiment, the spectrum purification filter 5 that always satisfies the standard is used.

  As described above, according to the first embodiment, there is provided the deterioration detecting means by measuring the temperature of the optical filter. This prevents a change in the imaging position and a decrease in resolution of the exposure apparatus of the first embodiment, eliminates a recovery time from the damage of the spectrum purification filter 5, and operates the exposure apparatus of the first embodiment efficiently. can do.

Next, an exposure apparatus according to Embodiment 2 of the present invention will be described with reference to a sectional view of FIG.
The second embodiment has the same configuration as that of the first embodiment, but is different in that the deterioration detecting means for detecting the deterioration of the spectral purification filter 5 measures the electrical resistance of the thin film of the spectral purification filter 5. The thin film of the spectral purification filter 5 is held by a filter holder 11 made of an insulator for electrical insulation from the light source chamber 6 and the illumination optical system chamber 7. In addition, electrodes 12-a and 12-b are provided at two locations on the surface of the thin film, and conductive wires 13-a and 13-b are joined from the electrodes 12-a and 12-b, respectively. A voltage is applied between the conducting wire 13-a and the conducting wire 13-b by the voltage applying means 14, a current value is measured by the ammeter 15, and the electric resistance of the thin film of the spectrum purification filter 5 is measured.

  When the projection exposure apparatus using the EUV light according to the second embodiment is operated, the temperature of the spectrum purification filter 5 is increased by the EUV light 1d irradiated from the plasma 1-c. However, when used for a long time, the thin film of the spectral purification filter 5, for example, zirconium gradually sublimates and becomes thin, the transmittance of ultraviolet light, visible light, and infrared light to be blocked increases, and the mechanical strength is increased. At the same time, the electrical resistance of the thin film increases.

  In advance, the transmittance of ultraviolet light, visible light, and infrared light, the mechanical strength, and the electrical resistance of the thin film are examined separately in advance with the sublimation of the thin film material. Further, a reference electrical resistance that is an electrical resistance corresponding to the reference transmittance or the reference mechanical strength of ultraviolet light, visible light, and infrared light that can be used by the spectral purification filter 5 is obtained. By using the spectral purification filter 5 for a long time, the electrical resistance of the spectral purification filter 5 increases, and when the reference electrical resistance is reached, the operation of the projection exposure apparatus of the second embodiment is stopped, and the spectral purification filter 5 Replace with a new one. With this configuration and method, the spectrum purifying filter 5 that always satisfies the standard is used in the second embodiment.

As described above, according to the second embodiment, the deterioration detecting means is provided by measuring the electric resistance of the thin film of the optical filter. As a result, a change in the imaging position and a decrease in resolution of the projection exposure apparatus according to the second embodiment can be prevented, and a recovery time from the damage of the spectrum purification filter can be eliminated, so that the projection exposure apparatus can be operated efficiently. .
Although it is the timing of measuring the electrical resistance, the spectral purification filter when the emission of the EUV light source 1 is stopped by exchanging the wafer 25 shown in FIG. It is preferable that the temperature of the thin film 5 is constant.

Next, an exposure apparatus according to Embodiment 3 of the present invention will be described with reference to a sectional view of FIG.
The difference between the third embodiment and the first embodiment is that the deterioration detecting means for detecting the deterioration of the spectral purification filter 5 evaporates or sublimates a substance constituting the thin film of the spectral purification filter 5, and is near the spectral purification filter 5. It vapor-deposits on the crystal oscillator 16 which is a member provided. Thereby, a change in the physical quantity of the crystal unit 16 is detected. That is, the deterioration detecting means uses a crystal oscillator microbalance method for detecting the mechanical resonance frequency of the crystal oscillator 16.

  In the vicinity of the spectrum purification filter 5, a quartz crystal resonator 16 as a member is provided. When the thin film material of the spectrum purification filter 5 is sublimated, a part of the quartz crystal resonator 16 is evaporated. The crystal resonator 16 vibrates by application of an AC voltage having a frequency near the mechanical resonance frequency of the crystal resonator 16 from the oscillation circuit 17. However, the oscillation circuit 17 detects the resonance frequency of the crystal resonator 16 by oscillating the frequency of the applied AC voltage and measuring the current phase and current value.

  When the projection exposure apparatus using the EUV light according to the third embodiment is operated, the temperature of the spectrum purification filter 5 is increased by the EUV light 1d irradiated from the plasma 1-c. However, when used for a long time, the thin film of the spectral purification filter 5, for example, zirconium gradually sublimates and becomes thin, the transmittance of ultraviolet light, visible light, and infrared light to be blocked increases, and the mechanical strength is increased. descend.

  At the same time, the deposition of the thin film material on the crystal unit 16 occurs, the mass is loaded and the shape changes, and the mechanical resonance frequency of the crystal unit 16 changes. In advance, it is separately examined how the transmittance, mechanical strength, and mechanical resonance frequency of the quartz crystal resonator 16 of the spectrum purifying filter 5 with the sublimation of the thin film material are changed. Further, a reference mechanical resonance frequency that is a mechanical resonance frequency corresponding to a reference transmittance or a reference mechanical strength of ultraviolet light, visible light, and infrared light that can be used by the spectrum purification filter 5 is obtained.

  When the spectral purification filter 5 is used for a long time, the mechanical resonance frequency of the spectral purification filter 5 changes, and when the reference mechanical resonance frequency is reached, the operation of the projection exposure apparatus of the third embodiment is stopped, and the spectrum Replace the purification filter 5 with a new one. With such a configuration and method, the spectrum purifying filter 5 that always satisfies the standard in the third embodiment is used.

As described above, according to the third embodiment, the deterioration detecting means is provided by detecting a change in the physical quantity of the mechanical resonance frequency of the crystal resonator 16 in the vicinity of the optical filter. As a result, a change in the imaging position and a decrease in resolution of the projection exposure apparatus according to the third embodiment can be prevented, and a recovery time from the damage of the spectral purification filter can be eliminated, so that the projection exposure apparatus can be operated efficiently. .
Although the crystal unit 16 is arranged inside the illumination optical system chamber 7, it may be arranged inside the light source chamber 6. However, in the light source chamber 6, it is preferable to provide a shielding plate or the like between the crystal resonator 16 and the plasma 1-c so that debris emitted from the vicinity of the plasma 1-c does not adhere to the crystal resonator 16.

Next, an exposure apparatus according to Embodiment 4 of the present invention will be described with reference to a sectional view of FIG.
The configuration of the fourth embodiment is the same as that of the third embodiment, but the third embodiment has a crystal resonator 16 based on a crystal oscillator microbalance method as a constituent requirement. However, in the fourth embodiment, a glass plate 18 is disposed in place of the crystal resonator 16, and physical quantities such as transmittance and reflectance that change as a result of vapor deposition are detected. The substance constituting the thin film of the spectral purification filter 5 evaporates or sublimates and is deposited on the glass plate 18 which is a member provided in the vicinity of the spectral purification filter 5. The deterioration detecting means for detecting the deterioration of the spectrum purification filter 5 detects a change in the physical quantity of the glass plate 18 due to the vapor deposition. That is, the deterioration detection unit measures the optical properties of the glass plate 18.

  A glass plate 18 is provided in the vicinity of the spectral purification filter 5, and when the thin film material of the spectral purification filter 5 is sublimated, a part of the glass plate 18 is deposited. The light emitting element 19 is made of an LED or the like, and a part 19a of light from the light emitting element 19 is reflected by the surface of the glass plate 18 and enters the light receiving element 20 made of, for example, a photodiode.

  When the projection exposure apparatus using the EUV light according to the fourth embodiment is operated, the temperature of the spectrum purification filter 5 is increased by the EUV light 1d irradiated from the plasma 1-c. However, when used for a long time, the thin film of the spectral purification filter 5, for example, zirconium gradually sublimates and becomes thin, the transmittance of ultraviolet light, visible light, and infrared light to be blocked increases, and the mechanical strength is increased. Degradation occurs. At the same time, deposition of a thin film material on the glass plate 18 occurs, and the reflectance of the glass plate 18 increases, so that the output of the light receiving element 20 increases.

  It is separately examined beforehand how the transmittance, mechanical strength, and output of the light receiving element 20 of the spectrum purifying filter 5 with the sublimation of the thin film material are changed. Further, a reference output that is an output of the light receiving element 20 corresponding to a reference transmittance or a reference mechanical strength of ultraviolet light, visible light, and infrared light that can be used by the spectrum purification filter 5 is obtained. By using the spectrum purification filter 5 for a long time, the output of the light receiving element 20 increases. When the reference output is reached, the operation of the projection exposure apparatus of the fourth embodiment is stopped, and the spectrum purification filter 5 is replaced with a new one. To do. With this configuration and method, the spectrum purifying filter 5 that always satisfies the standard in the fourth embodiment is used.

  As described above, according to the fourth embodiment, there is provided a deterioration detecting means that utilizes a change in optical properties caused by vapor deposition of a member in the vicinity of the optical filter. As a result, it is possible to prevent a change in the imaging position and a decrease in resolution of the projection exposure apparatus of the fourth embodiment, eliminate the recovery time from the damage of the spectrum purification filter 5, and operate the projection exposure apparatus efficiently. it can.

In the fourth embodiment described above, a configuration using the reflectance change of the glass plate 18 accompanying the deterioration of the spectrum purification filter 5 is used. However, other optical properties may be measured. For example, the light receiving element 20 may be disposed on the opposite side of the light emitting element 19 with the glass plate 18 interposed therebetween, and a change in transmittance may be used.
Further, although the glass plate 18, the light emitting element 19 and the light receiving element 20 are configured to be disposed inside the illumination optical system chamber 7, they may be disposed inside the light source chamber 6. Inside the light source chamber 6, it is preferable to provide a shielding plate or the like between the glass plate 18 and the plasma 1-c so that debris emitted from the vicinity of the plasma 1-c does not adhere to the glass plate 18.

Next, an exposure apparatus according to Embodiment 5 of the present invention will be described with reference to a sectional view of FIG.
Although the configuration of the fifth embodiment is the same as that of the first to fourth embodiments described above, the first to fourth embodiments have increased transmittance of ultraviolet light / visible light / infrared light by sublimation of the thin film of the spectral purification filter 5 and In this configuration, deterioration such as a decrease in mechanical strength is detected. However, the fifth embodiment is configured to detect deterioration in which the transmittance of the EUV light 1d is reduced due to deposits on the spectrum purification filter 5. That is, the synchrotron radiation measuring instrument 21 which is a deterioration detecting means is a measuring instrument based on the same principle as that of the radiation thermometer 10 in the first embodiment shown in FIG. 1, but is irradiated from the surface of the spectrum purification filter 5 on the light source chamber 6 side. It is arranged on the upper part of the light source chamber 6 so as to measure and detect the emitted light.

When the projection exposure apparatus using the EUV light according to the fifth embodiment is operated and used for a long time, the light source of the spectrum purification filter 5 is irradiated with the trace amount of hydrocarbon gas contained in the light source chamber 6 and the EUV light 1d. Hydrocarbon gradually accumulates on the surface on the chamber 6 side. This deposition reduces the EUV light transmittance of the spectral purification filter 5.
The spectrum purification filter 5 emits infrared light due to an increase in temperature due to the EUV light 1d emitted from the EUV light source 1, but the emissivity of zirconium, which is a material of the thin film of the spectrum purification filter 5, is about 0.2. On the other hand, hydrocarbon is about 0.9. For this reason, when the hydrocarbon is attached, infrared light several times is emitted, and the output of the radiated light measuring instrument 21 reaches several times.

  In advance, the EUV light transmittance of the spectrum purification filter 5 and the output of the synchrotron radiation measuring device 21 will be examined separately in advance as the hydrocarbon is deposited. Further, a synchrotron radiation meter output, which is a synchrotron radiation meter output corresponding to the EUV light transmittance standard that can be used by the spectrum purification filter 5, is obtained. By using the spectrum purification filter 5 for a long time, the output of the synchrotron radiation measuring instrument 21 increases. When the output of the synchrotron radiation measuring instrument reaches the reference synchrotron radiation measuring instrument output, the operation of the projection exposure apparatus of the fifth embodiment is stopped, and the spectrum purification Replace the filter 5 with a new one. With this configuration and method, the spectrum purifying filter 5 that always satisfies the criteria in the fifth embodiment is used.

  As described above, according to the fifth embodiment, by having the deterioration detecting means by detecting the amount of radiated light, the intensity of the EUV light 1d is reduced and the throughput of the projection exposure apparatus of the fifth embodiment is increased. Prevents the decline. In addition, maintenance does not take much time when the cause of the decrease in throughput is unknown. Further, not only the attachment of the hydrocarbon, but also, for example, the difference between the physical property values of zirconium and tin in the exposure apparatus having the EUV light source 1 using tin as a plasma material may be used. Thereby, the difference in the physical property value between the deposit and the thin film material of the spectrum purification filter 5 can be utilized.

  In addition, when deterioration due to sublimation of the thin film of the spectral purification filter 5 described in the first to fourth embodiments occurs at the same time, it is possible to grasp in advance which deterioration is caused by deposits on the spectral purification filter 5 and which is earlier. Keep it. For this reason, Example 5 should be used when the deterioration due to deposits is rapid, and Examples 1 to 4 may be used otherwise.

(Example of device manufacturing method)
A device (semiconductor integrated circuit element, liquid crystal display element, etc.) is a step of exposing a substrate (wafer, glass plate, etc.) coated with a photosensitive agent using the exposure apparatus of any of the embodiments described above, and its exposure. And a step of developing the processed substrate.

It is sectional drawing of Example 1 of this invention. It is sectional drawing of Example 2 of this invention. It is sectional drawing of Example 3 of this invention. It is sectional drawing of Example 4 of this invention. It is sectional drawing of Example 5 of this invention. It is a schematic block diagram of the exposure apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 EUV light source 1-a Nozzle 1-b Electrode 1-c Plasma 1d EUV light 2 Debris filter 3 Condensing mirror 4 Condensing point 5 Spectral purification filter 6 Light source chamber 7 Illumination optical system chamber 8 Illumination system 1st mirror 9 Optical integrator DESCRIPTION OF SYMBOLS 10 Radiation thermometer 11 Filter holder 12-a Electrode 12-b Electrode 13-a Conductor 13-b Conductor 14 Voltage application means 15 Ammeter 16 Crystal oscillator 17 Oscillator circuit 18 Glass plate 19 Light emitting element 20 Light receiving element 21 Radiated light Measuring instrument

Claims (9)

An EUV light source that emits EUV light;
In an exposure apparatus having an illumination optical system that illuminates the original with the EUV light emitted from the EUV light source,
An optical filter comprising a thin film that transmits the EUV light and blocks light other than the EUV light, and is provided in an optical path of the EUV light;
A projection exposure apparatus comprising: a deterioration detecting unit that detects deterioration of the optical filter.   The exposure apparatus according to claim 1, wherein the deterioration detecting unit measures a temperature of a thin film of the optical filter.   The exposure apparatus according to claim 1, wherein the deterioration detecting unit measures an electrical resistance of a thin film of the optical filter.   The deterioration detecting means detects a change in a physical quantity of the member caused by evaporation or sublimation of a substance constituting a thin film of the optical filter and vapor deposition on a member provided in the vicinity of the optical filter. The exposure apparatus according to claim 1.   5. The exposure apparatus according to claim 4, wherein the member is a crystal resonator, and the deterioration detecting means uses a crystal oscillator microbalance method.   The exposure apparatus according to claim 4, wherein the member is a glass plate, and the deterioration detecting unit measures an optical property of the glass plate.   2. The exposure apparatus according to claim 1, wherein the deterioration detecting means detects the amount of radiation emitted from the optical filter.   8. The optical filter separates an EUV light source chamber in which the EUV light source is provided from an illumination optical system chamber in which the illumination optical system is provided. 8. Exposure device. A step of exposing the substrate using the exposure apparatus according to claim 1;
Developing the exposed substrate;
A device manufacturing method comprising:

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