JP2001013297A - Catoptric element and exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extremely lessen deformation due to thermal fluctuation even when X rays or extreme ultraviolet rays are radiated and prevent the intensity of irradiation of X rays or extreme ultraviolet rays from attenuating by providing a cooling means in a multilayer reflecting mirror that reflects X rays or extreme ultraviolet rays. SOLUTION: A catoptric element that reflects X rays or extreme ultraviolet rays is equipped with a substrate 1 where a reflection film can be formed over a larger area than a reflection region 2a, reflection films 2 which are deposited on the reflection region 2a and a domain 2b other than it on the substrate 1 and a cooling means 3 that is located on the reflection film 2 deposited on the domain 2b to cool the reflection film 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus using an X-ray reflection mirror, an X-ray reflection mask or an X-ray reflection optical system used in an X-ray reflection optical system.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductor integrated circuit elements, X-rays having shorter wavelengths have been used in place of conventional ultraviolet rays in order to improve the resolution of an optical system limited by the diffraction limit of light. Projection lithography technology has been developed. An X-ray projection exposure apparatus used in this technique mainly includes an X-ray source, an illumination optical system, a mask, an imaging optical system, a wafer stage, and the like.

By the way, in the X-ray wavelength region, there is no transparent substance and the reflectivity on the substance surface is very low, so that ordinary optical elements such as lenses and reflectors cannot be used. Therefore, the reflecting mirror used in the optical system for X-rays is configured by a multilayer reflecting mirror that obtains a high reflectance by an interference effect by matching the phases of the reflected light at each interface of the multilayer film.

However, such a multilayer reflector has an X-ray reflectivity that is not 100% and an X-ray that is not reflected.
The rays are absorbed by the X-ray reflector and become heat, which heats the reflector. Therefore, when strong X-rays are incident, the irradiation causes heating of the X-ray reflecting mirror, which causes a problem that the shape of the X-ray reflecting mirror is thermally deformed and the surface of the X-ray reflecting mirror is deteriorated by heat.

Therefore, in order to prevent heating by heat, Japanese Patent Laid-Open Publication No. 63-312638 discloses that a cooling mechanism is provided on the back side of the X-ray reflecting mirror to cool the X-ray reflecting mirror. Further, a method has been proposed in which a space provided with an X-ray reflecting mirror is replaced with hydrogen or helium gas having relatively good X-ray transmittance to cool the space. On the other hand, with an X-ray reflector,
It is required that the shape be created with extremely high precision.
For this purpose, the substrate is made of a glass material such as quartz that can be processed with high precision, but these materials generally have poor thermal conductivity.

Therefore, in the conventional cooling from the back side,
For materials with poor thermal conductivity, such as quartz, no matter how much the back surface is cooled, a large temperature gradient is formed inside the reflector, and even if the back surface is cooled, the response of the surface temperature change is poor. It has been difficult to efficiently cool the reflector. As a result, even when cooling, the heat generated by X-ray irradiation is accumulated near the surface of the X-ray reflector, causing thermal deformation and alteration of the X-ray reflector, which is a factor that degrades optical performance. I was In particular, a large temperature gradient inside the reflector has been one of the causes of distortion of the reflector.

Further, even if the reflecting surface of the X-ray reflecting mirror is cooled by hydrogen or helium gas, there is no sufficient cooling ability, and X-rays are attenuated by the propagation of hydrogen or helium gas by X-rays. It is also possible.

[0008]

As described above, attempts have been made to realize a projection lithography technique using short-wavelength X-rays or extreme ultraviolet rays. Even when a cooling mechanism is provided or when cooling with gas is performed, the cooling effect is not sufficient, so that heat generated by irradiation with X-rays or extreme ultraviolet rays causes heat deformation of the reflecting mirror shape or thermal deterioration of the reflecting mirror surface. Deterioration of optical performance has been a problem. Further, absorption by gas is also not preferable because it attenuates X-rays and extreme ultraviolet rays.

In view of the above, the present invention relates to a multilayer reflector for reflecting X-rays or extreme ultraviolet rays, which has very little deformation due to a thermal change even when irradiated with X-rays or extreme ultraviolet rays, and is provided with a cooling means. And that the irradiation intensity of extreme ultraviolet light does not decrease.

[0010]

According to a first aspect of the present invention, there is provided a reflective optical element for reflecting X-rays or extreme ultraviolet rays, wherein a reflective film is formed over an area larger than a reflective area. Substrate, a reflective film formed on the substrate in a reflective region and a region other than the reflective region, and a cooling means provided on the reflective film formed in a region other than the reflective region and cooling the reflective film. Equipped.

By providing the reflection film with the cooling means, a large temperature gradient is not formed inside the reflection mirror (especially, the substrate), and the reflection mirror itself can be efficiently cooled. Thermal deformation can be prevented. Further, since the optical path is provided in a region other than the irradiation area of the reflective optical element, vignetting does not occur in the optical path, and attenuation of X-rays or extreme ultraviolet rays does not occur when cooling by gas is used.

Still further, according to the first aspect of the present invention, a heat transfer layer made of a substance having a higher thermal conductivity than the substrate or the reflective film is provided between the substrate and the reflective film. .
Thus, by further providing the heat transfer layer, the temperature gradient can be further reduced, and the heat can be efficiently released to the area other than the irradiation area of the reflective optical element, and the heat is efficiently transmitted to the cooling means. be able to.

Further, according to the first aspect of the present invention,
In the reflective film, an opening was formed in which a reflective film having a predetermined pattern was not formed. This makes it possible to form a reflective mask that is less likely to be deformed by heat. Further, other than providing the openings, a similar reflective mask can be obtained by forming an absorber having a predetermined pattern on the reflective film and absorbing X-rays and extreme ultraviolet rays.

According to the first aspect of the present invention, there is further provided a temperature measuring means formed on a reflection film and formed on a portion other than the reflection area for measuring the temperature of the reflection optical element;
Control means for controlling the cooling means so that the temperature measured by the temperature measuring means falls within a predetermined range. By controlling the cooling capacity of the cooling means while monitoring the temperature in this way, in addition to the deformation of the reflective optical element due to the generation of heat, the deformation of the reflective optical element caused by contraction of the substrate due to overcooling is prevented. Can be.

Further, according to a second aspect of the present invention, at least one sheet has a reflecting mirror provided with a cooling means, and a pattern formed on a mask is formed on a wafer by using X-rays or extreme ultraviolet rays. In an exposure apparatus for transferring to a mirror, a reflecting mirror provided with a cooling means is formed on a substrate on which a reflective film can be formed over an area larger than the reflective region, and on the substrate, a reflective region and a region other than the reflective region. The cooling means is provided on a reflective film formed in a region other than the reflective region. Further, there are provided a temperature measuring means for measuring the temperature of the reflecting mirror, and a control means for controlling the cooling means based on information obtained by the temperature measuring means.

By controlling the cooling capacity of the cooling means while measuring the temperature in this way, it is possible to prevent the deformation of the reflecting mirror due to a heat change, and to prevent the occurrence of aberrations of the optical system caused by the heat change. . As a result, it is possible to provide an exposure apparatus in which the imaging performance does not deteriorate even when the operation time of the exposure apparatus is prolonged. Further, according to the third aspect of the present invention, an illumination optic for illuminating a mask having a pattern formed on a wafer and comprising a light source for radiating X-rays or extreme ultraviolet rays and at least one multi-layer reflecting mirror is provided. System and
An exposure apparatus comprising at least one or more multilayer film reflecting mirrors and having a projection optical system for projecting X-rays or extreme ultraviolet rays from a mask onto a wafer, wherein at least one of the multilayer film reflecting mirrors forming the projection optical system One multi-layer reflector has a substrate on which a reflective film can be formed over an area larger than the reflective region, and a reflective film formed on the substrate in the reflective region and in a region other than the reflective region. In addition, a cooling unit is provided together with a temperature measuring unit on a reflective film formed in a region other than the reflection area, and a control unit that controls the cooling unit based on information from the temperature measuring unit.

As described above, in the exposure apparatus having the illumination optical system and the projection optical system constituted by the multilayer film reflecting mirror, at least one of the multilayer film reflecting mirrors forming the projection optical system is provided with the cooling means and the temperature measurement. Means, when a mask pattern is imaged on a wafer, it is possible to prevent deformation of the multilayer film reflecting mirror of the projection optical system, which greatly affects the imaging performance, due to thermal changes, and to prevent deterioration of optical characteristics. Can be prevented.

Next, the present invention will be described by exemplifying embodiments of the present invention. However, the present invention is not limited to this.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first embodiment of the present invention, an exposure apparatus will be described. This exposure apparatus has the schematic configuration shown in FIG. The configuration of this exposure apparatus is as follows. This exposure apparatus is a projection exposure apparatus that performs an exposure operation by a step-and-scan method using light in a soft X-ray region (EUV light) as illumination light for exposure. In FIG. 1, the direction of the optical axis of a projection system for forming a reduced image of the mask 18 on the wafer 10 is defined as a Z direction, and the direction in the plane of the drawing perpendicular to the Z direction is defined as a Y direction.
The direction perpendicular to the paper plane perpendicular to the YZ directions is defined as the X direction.

This exposure apparatus uses a reflective mask 18 as a projection original, and projects a partial image of a circuit pattern drawn on the reflective mask 18 onto a wafer 10 as a substrate via a projection system 19. In addition, the mask 18 and the wafer 10 are moved one-dimensionally with respect to the projection system 19 (here, the Y-axis direction).
The entire circuit pattern of the reflective mask 18 is transferred to each of a plurality of shot areas on the wafer 10 by a step-and-scan method by performing relative scanning on the wafer.

Here, soft X-rays (hereinafter referred to as EUV light), which are illumination light for exposure, have a low transmittance to the atmosphere.
The optical path through which the UV light passes is covered by the vacuum chamber 1 and is shielded from outside air. As a light source to be used, a laser plasma X-ray source using xenon as a target is used. In this laser plasma X-ray source, components other than a laser light source 90 as an excitation light source and a condensing optical system 91 are installed in a vacuum vessel including a vacuum chamber 50b and a window 50a. In particular, in this laser plasma X-ray source, debris is generated from a nozzle that emits xenon gas, and therefore, must be disposed in a vacuum vessel different from the vacuum chamber 1.

First, the illumination system of the exposure apparatus according to the first embodiment will be described. The laser light source 90 has a function of supplying laser light having a wavelength in the infrared region to the visible region. For example, a YAG laser or an excimer laser excited by a semiconductor laser is used. This laser light is condensed by the condensing optical system 91 and condensed on the position 13. The nozzle 12 ejects xenon gas toward the position 13, and the ejected xenon gas receives a laser beam of high illuminance at the position 13. At this time, the ejected object becomes hot due to the energy of the laser light, is excited into a plasma state, and emits EUV light when transitioning to a low potential state.

An elliptical mirror 14 constituting a condensing optical system is arranged around the position 13.
Are positioned such that their first focal point substantially coincides with the position 13. A multilayer film for reflecting the EUV light is provided on the inner surface of the elliptical mirror 14, and the EUV light reflected here passes through the window 50 a of the vacuum vessel, and the second focal point of the elliptical mirror 14. After focusing once, the light goes to a parabolic mirror 15 as a collimating reflecting mirror. This parabolic mirror 15
The focal point is positioned so as to substantially coincide with the second focal point position of the elliptical mirror 14, and the inner surface thereof is provided with an alternating multilayer film for reflecting EUV light.

The EUV light emitted from the parabolic mirror 15 is
The light goes to the reflective fly-eye optical system 16 as an optical integrator in a substantially collimated state. The reflective fly-eye optical system 16 includes a first reflective element group 60a formed by integrating a plurality of reflective surfaces (a plurality of mirror elements), and a plurality of reflective surfaces corresponding to the plurality of reflective surfaces of the first reflective element group 60a. And a second reflective element group 60b having a reflective surface of These first and second reflecting element groups 60a, 60
A multilayer film for reflecting EUV light is also provided on a plurality of reflection surfaces constituting Ob.

The collimated EU from the parabolic mirror 15
The V light is wavefront divided by the first reflecting element group 60a,
EUV light from each reflecting surface is collected to form a plurality of light source images. A plurality of reflecting surfaces of the second reflecting element group 60b are provided in the vicinity of the positions where the plurality of light source images are formed, respectively.
The plurality of reflecting surfaces b substantially function as field mirrors. Thus, the reflection type fly-eye optical system 16
Forms a large number of light source images as secondary light sources based on the substantially parallel light flux from the parabolic mirror 15. Such a reflective fly-eye optical system 16 is proposed in Japanese Patent Application No. 10-47400 by the present applicant.

The EUV light from the secondary light source formed by the reflection type fly-eye optical system 16 travels to a condenser mirror 17 positioned such that a position near the position of the secondary light source is a focal position. After being reflected and condensed by the mirror 17, the light reaches the reflective mask 18 via the optical path bending mirror 17a. On the surfaces of the condenser mirror 17 and the optical path bending mirror 17a,
A multilayer film that reflects EUV light is provided. Then, the condenser mirror 17 is provided with EU light emitted from the secondary light source.
The V light is condensed, and a predetermined illumination area on the reflective mask 18 is uniformly illuminated in a superimposed manner.

In this embodiment, the reflection type mask 18 is used.
The illumination system is non-telecentric, and the projection system 19 is also a mask in order to spatially separate the optical path between the illumination light traveling toward the projection type and the EUV light reflected by the reflection type mask 18 toward the projection system 19. The optical system is non-telecentric. A reflective film made of a multilayer film that reflects EUV light is provided on the reflective mask 18, and the reflective film conforms to the shape of a pattern to be transferred onto the wafer 10 as a photosensitive substrate. It has a pattern. The EUV light reflected by the reflective mask 18 and including the pattern information of the reflective mask 18 enters the projection system 19.

The projection system 19 of the first embodiment comprises a concave first mirror 19a and a convex second mirror 19a.
b, a total of four mirrors (reflecting mirrors): a convex third mirror 19c and a concave fourth mirror 19d. Each of the mirrors 19a to 19d is formed by providing a multilayer film that reflects EUV light on a base material, and is arranged such that their optical axes are coaxial.

Here, in order not to interrupt the reciprocating optical path formed by each of the mirrors 19a to 19d, the first mirror 19
a, the second mirror 19b and the fourth mirror are provided with notches. In addition, the dotted line part shown in FIG. 1 has shown the notch. An aperture stop (not shown) is provided at the position of the third mirror 19c. The EUV light reflected by the reflective mask 18 is successively reflected by the first mirror 19a to the fourth mirror 19d, and enters a predetermined reduction magnification β (for example, | β | = 1 / 4,1 /
(5, 1/6), a reduced image of the pattern of the reflective mask 18 is formed. This projection system 19 is located on the image side (wafer 10).
Side) is configured to be telecentric.

Although not shown in FIG. 1, the reflective mask 18 is supported by a reticle stage movable at least along the Y direction.
It is supported by a wafer stage (substrate stage) movable along the Z direction. In the exposure operation, the illumination system irradiates the illumination area on the reflection mask 18 with EUV light, and the reflection mask 18 and the wafer 10 are determined with respect to the projection system 19 by the reduction magnification of the projection system. Move at a predetermined speed ratio. Thus, the pattern of the reflective mask 18 is scanned and exposed in a predetermined shot area on the wafer 10.

Incidentally, in the mirror and the reflection element used in the first embodiment, the effective area is not necessarily centered on the optical axis, but is a part of the outer shape. Also, the projection system 19
The reflection mirror used in the above has an X-ray reflection film 2 formed in a region other than the reflection region as shown in FIG. FIG. 2 is an enlarged view of the projection system 19 employed in the present exposure apparatus. In FIG. 2, the area through which the X-rays are transmitted and reflected is an inner part surrounded by a dotted line 100.

As can be seen from this figure, the mirror used in the first embodiment has a cooling means 3 described later on the X-ray reflection film 2 formed outside the reflection area. Details of the configuration of the cooling means 3 will be described later. Further, as shown in FIG. 1, a cooling means driving section 30b for supplying cooling water and energy for cooling to the cooling means 3 is provided. Then, each cooling means 3 is driven.

In contrast to the example shown in FIG. 2, when a multilayer film reflecting mirror is formed using a substrate having a sufficient area and a substrate surface which cannot secure a peripheral portion, the peripheral portion is not provided. Further, another plate material is provided around the substrate so as to enlarge the reflection film 2. At this time, a plate material is provided at a place where the optical path of the X-ray optical system is not affected. Then, a cooling means may be provided in the peripheral portion. By doing so, the optical path of the X-ray optical system can be prevented from being affected around the X-ray reflection area.

The cooling means 3 is also provided in the mirrors and the reflection elements constituting the illumination system, and supplies the cooling means 3 with energy for cooling a cooling medium such as cooling water or other cooling means. A cooling means driving unit 30a is also provided. Next, as a representative example of the mirror used in the first embodiment, based on the X-ray reflecting mirror shown in FIG. 3, a detailed configuration of the X-ray reflecting mirror will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of the X-ray reflecting mirror according to the present invention, and has a shape substantially the same as that of the condenser mirror 17 of the exposure apparatus shown in FIG. Note that FIG.
3A shows a top view of the X-ray reflecting mirror, and FIG. 3B shows a cross-sectional view.

The X-ray reflecting mirror according to the first embodiment has an X-ray reflecting area 2a, a peripheral portion 2b outside the X-ray reflecting area, and is applied to the substrate 1 and the substrate 1. ,
It comprises a reflective film 2 composed of an alternating multilayer film formed of at least two kinds of substances having different optical constants in an X-ray region, and a cooling medium circulating means as a cooling means 3. The reflection film 2 includes an X-ray reflection region 2a and a peripheral portion 2b.
In both cases, a film is continuously formed without a seam.

The X-ray reflecting mirror according to the first embodiment comprises:
It is used for a projection optical system for X-ray reduction exposure with a wavelength of 13 nm, and quartz is used as the material of the substrate 1 and its reflection surface shape is processed with high precision. The X-ray reflection film 2 uses a multilayer film of molybdenum and silicon having a higher thermal conductivity than the substrate 1 and a high reflectance of X-rays having a wavelength of 13 nm. The X-ray reflection film 2 is not limited to the multilayer film of molybdenum and silicon, but may be a multilayer film made of a combination of substances having a higher thermal conductivity than the substrate 1 and exhibiting a high reflectance according to the wavelength to be used. At a wavelength of 10 to 15 nm, ruthenium (R
u), rhodium (Rh) and silicon (S
i), a multi-layer film in combination with a substance such as beryllium (Be) carbon tetraboride (B4C) may be used.

Incidentally, the cooling medium circulating means, which is the cooling means 3 of the present embodiment, has a pipe for circulating the medium on the X-ray reflection film 2 in the peripheral portion 2b.
As shown in FIG. 3, the X-ray reflecting area 2 of the X-ray reflecting mirror
A pipe is provided in the peripheral portion 2b so as not to obstruct a. A cooling water as a cooling medium flows through the pipe.

The X-ray reflecting mirror according to the first embodiment is
At the same time as the X-rays are reflected by the X-ray reflection film 2 on the X-ray reflection area 2a, the unreflected X-rays are absorbed by the X-ray reflection film 2 and turned into heat. The generated heat is transmitted through the X-ray reflection film 2 having a high thermal conductivity, and is transferred from the X-ray reflection region 2a to the peripheral portion 2b.
And the temperature of the entire X-ray reflection film 2 is increased.
On the other hand, the temperature of the cooling means 3 provided in the peripheral portion 2b was kept constant by a temperature control mechanism 300 having a pump for sending cooling water to a cooling pipe provided in the peripheral portion 2b of the X-ray reflection film 2. Cooling water is circulating. And X
When the temperature of the X-ray reflection film 2 becomes higher than the cooling water due to the irradiation of the rays, the heat of the X-ray reflection film 2 is absorbed by the cooling water through the pipe 3a.

In the present invention, the relationship between the cooling means control units 30a and 30b and the temperature control mechanism 300 shown in FIG.
b. Incidentally, molybdenum, ruthenium, and rhodium are used as the high refractive index substance used for the X-ray reflection film 2. In these materials, the X-ray reflection film 2 has a high thermal conductivity, so that the temperature gradient between the X-ray reflection region 2a and the peripheral portion 2b is small. Further, since the amount of cooling water is circulated to such an extent that the heat generated by X-ray irradiation can be sufficiently absorbed, the entire surface of the X-ray reflecting mirror can be maintained at substantially the same temperature as the cooling water.

In the first embodiment, water is used as the cooling medium. However, a liquid such as oil or a gas such as chlorofluorocarbon may be used. Next, an exposure apparatus according to a second embodiment of the present invention will be described with reference to FIG. The exposure apparatus according to the second embodiment of the present invention differs from the exposure apparatus according to the first embodiment only in the use of an X-ray reflecting mirror. Therefore, only the X-ray reflecting mirror will be described here.

FIG. 4 is a schematic structural view of an X-ray reflecting mirror used in an exposure apparatus according to a second embodiment of the present invention. FIG. 4A is a top view of the X-ray reflecting mirror, and FIG. 4B is a cross-sectional view. In FIG. 4,
Configurations that are the same as or correspond to the configurations in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted. The X-ray reflecting mirror of the second embodiment is different from the reflecting mirror of the first embodiment in that (1) the Peltier device 3
(2) The temperature sensor 5 is installed not only in the Peltier element 3b as the cooling means 3 but also in the peripheral part 2b of the X-ray reflecting mirror.

Further, in the second embodiment, X
The line reflecting mirror includes a cooling unit control unit 310 that controls the cooling capacity of the Peltier element 3b. This control unit 31
0 is X based on the temperature information obtained from the temperature sensor 5.
The current supplied to the Peltier element 3b is controlled so that the line reflector can always maintain a constant temperature. The control unit 310 outputs a temperature sensor output unit 312 that outputs a temperature obtained from the temperature sensor 5 as a signal, a power supply unit 311 that supplies current to the Peltier element 3b, and a signal obtained from the temperature sensor output unit 312. The control unit 313 calculates a current to be supplied to the Peltier element 3b based on the control and controls the power supply unit 311.

By the way, in the second embodiment, X
Similarly to the X-ray reflecting mirror described in the first embodiment, the X-ray reflecting mirror uses an alternate multilayer film of molybdenum and silicon as the X-ray reflecting film 2. The alternate multilayer film is formed continuously and seamlessly on both the X-ray reflection region 2a and the peripheral portion 2b. The Peltier element 3b and the temperature sensor 5 are arranged in the peripheral portion 2b so as not to block the X-ray reflection area 2a of the X-ray reflection mirror. The temperature sensor 5 is arranged near the X-ray reflection area 2a. Actually, as shown in FIG. 4, a temperature sensor 5 is provided closest to the X-ray reflection area 2a, and a Peltier element 3 is further provided therearound.
b. In such an arrangement, the temperature of the X-ray irradiation area 2a is to be measured by the temperature sensor 5 without error. The temperature sensor 5 uses a thermistor in the second embodiment.

On the other hand, the Peltier element 3b is an element capable of cooling one side by passing an electric current and transferring the heat to the back side. Since there is no movable portion, dust and vibration are not generated. In the optical system of the exposure apparatus, if dust or vibration occurs, the optical performance of the optical system is degraded. Therefore, such a cooling unit that does not generate dust or vibration is a means suitable for the exposure apparatus. The Peltier element 3b is
The feature is that the amount of cooling can be controlled by the magnitude of the current flowing through the cooling device.

Therefore, the cooling means control section 310 uses the Peltier element 3 based on the information obtained from the temperature sensor 5.
The magnitude of the current flowing through the Peltier element 3b is determined to control the cooling amount of the Peltier element 3b. Thus, by controlling the cooling amount of the Peltier element 3b based on the temperature information obtained from the temperature sensor 5, the X-ray reflecting mirror can always be kept at a constant temperature. Thus, in the second embodiment, the deformation of the X-ray reflecting mirror due to heating can be prevented, and the deformation of the X-ray reflecting mirror due to supercooling can be prevented. Therefore, in the optical system using the X-ray reflecting mirror described in the second embodiment, stable optical characteristics are always obtained in any state, and it is possible to prevent changes in optical characteristics due to thermal changes. it can.

The temperature sensor 5 may be anything as long as it can measure the temperature of the X-ray reflection film 2, and may be another temperature sensor such as a thermocouple. Further, as another example of the temperature sensor 5, a material using a substance whose resistance value changes with temperature as shown in FIG. 5 may be used. FIG. 5A shows an example in which a substance whose resistance value changes according to such temperature is provided in the vicinity of the X-ray reflection region 2a of the X-ray reflection mirror. FIG. 5A shows only a part of the X-ray reflecting mirror.

As shown in FIG. 5A, the temperature sensor 5 is provided only in a part near the X-ray reflection area 2a. Further, the temperature sensor 5 shown in FIG. 5 uses a temperature sensor composed of a resistance film 51 made of a material having a large resistance temperature coefficient. Note that the cooling means 3 is provided with the temperature sensor 5
It is further provided on the outer periphery.

FIG. 5B shows a sectional view of the structure. As can be seen from FIG. 5B,
The temperature sensor 5 shown in FIG. 5 includes a resistance film 51 and an insulating film 6. The resistance film 51 is made of platinum (Pt) having a relatively stable temperature coefficient of resistance, and is electrically insulated from the X-ray multilayer film 2 by the insulating film 6. Since the electric resistance of the resistance film 51 changes according to a change in temperature, a voltage can be applied to the resistance film 51, a resistance value can be measured by a flowing current, and the temperature can be measured by converting the resistance value into a temperature. Such a temperature sensor 5 is formed by patterning a material forming the insulating film 6 and a material forming the resistive film 51 by a film forming method which is a process used for manufacturing an X-ray reflecting mirror. It has the feature that it can be built on the surface of a line reflector. Note that a film may be formed using a similar manufacturing method so that different kinds of metals such as thermocouples are joined.

Although platinum is used for the resistance film 51, other pure metals such as nickel (Ni), copper (Cu) and indium (In), platinum-rhodium, rhodium-
Alloys such as iron and platinum-cobalt may be used. Note that the X-ray reflector used by controlling the cooling amount of the cooling means 3 using the temperature sensor 5 may be replaced with the X-ray reflector used in the exposure apparatus shown in FIG. In that case, it is preferable to provide a cooling unit control unit 310 shown in FIG. 4 in each of the X-ray reflecting mirrors instead of the cooling unit driving units 30a and 30b. Also, instead of providing such a cooling unit control unit 310, a centralized CPU may be provided, and the cooling amount of each X-ray reflecting mirror may be controlled there.

In some cases, the X-ray reflecting mirror employed in the projection system 9 which has a large influence on the aberration is provided with a mechanism for controlling the cooling amount of the cooling means 3 having the temperature sensor 5. If an X-ray reflecting mirror is used, a large heat change does not occur.
An exposure apparatus in which the shape change of the line reflecting mirror is reduced and stable imaging performance is obtained can be obtained.

Next, an exposure apparatus according to a third embodiment of the present invention will be described. The exposure apparatus according to the third embodiment of the present invention differs from the exposure apparatus according to the first embodiment only in the use of a reflective mask. Therefore, only the reflection type mask will be described here. FIG. 6 shows a schematic configuration diagram of the reflective mask 18 used in the exposure apparatus shown in FIG. FIG. 6A is a top view of the reflective mask 18.
FIG. 6B shows a cross-sectional view thereof. In FIG. 6, the same or corresponding components as those in FIG. 4 are denoted by the same reference numerals, and redundant description will be omitted.

The reflective mask 18 has the reflective film 2 and the opening 9 formed corresponding to the circuit pattern to be printed on the wafer 10. Further, this reflection type mask has an X-ray reflection area 2a on the reflection mirror substrate 1.
The heat transfer layer 8 is formed regardless of the peripheral portion 2b. A Peltier element 3b is provided on the heat transfer layer 8 in the peripheral portion 2b, and a temperature sensor 5 for measuring the temperature of the reflective mask 18 is provided in the peripheral portion 2b near the X-ray reflection region 2a. Is provided.

On the other hand, the X-ray reflection film 2 is formed at a predetermined position on the heat transfer layer 8 in the X-ray reflection area 2a. In addition,
The position where the X-ray reflection film 2 is formed is determined according to a circuit pattern to be patterned on the wafer 10. With such a configuration, the heat transmitted through the heat transfer layer 8 is absorbed by the Peltier element 3b, and the reflective mask 18 that reflects X-rays is cooled. As described above, the X-ray reflection film 2 is divided into the X-ray reflection region 2 a and the peripheral portion 2 b
It is possible to cool even a reflection member that cannot form a film continuously.

In the reflective mask 18 used in the third embodiment, the heat transfer layer 8 is formed of gold.
Note that this substance called gold absorbs X-rays and has high heat transfer characteristics. Therefore, in the reflection mask 18, the X-rays are reflected by the X-ray reflection film 2 in the X-ray reflection region 2 a and the X-rays are absorbed by the opening 9 of the X-ray reflection film 2. A contrast is formed in the region, and the pattern of the reflective mask 18 can be transferred onto the wafer 10 by X-ray projection exposure.

The material for forming the heat transfer layer 8 may be a material having a high thermal conductivity such as copper or silver. In such a reflective mask 18, X-rays not reflected at the portion where the X-ray reflective film 2 is formed are absorbed, and the opening 9 is formed.
Since the heat transfer layer 8 is exposed, most X-rays are absorbed by the heat transfer layer 8. Each of the absorbed X-rays turns into heat. Since the amount of generated heat is determined by the amount of absorbed X-rays, in the reflective mask 18 as described above, the amount of generated heat per unit area is larger in the heat transfer layer 8.

The heat generated in this way propagates through the heat transfer layer 8 having a higher thermal conductivity than the X-ray reflection film 2 and
spread to b. The heat transmitted through the heat transfer layer 8 is measured by the temperature sensor 5, and the cooling amount of the Peltier element 4 is controlled based on the temperature measured by the temperature sensor 5, so that the temperature of the X-ray reflecting mirror is reduced. Can be kept constant. In addition, not only the heat generated in the heat transfer layer but also the heat generated by the X-ray reflection film 2 propagates through the heat transfer layer 8 having a high thermal conductivity. Can cool the whole well. The control unit used in this embodiment is the same as the cooling unit control unit used in the second embodiment of the present invention.

As described above, the exposure apparatus according to the third embodiment of the present invention can prevent the reflective mask 18 from being deformed even when the exposure time to the reflective mask 18 is long, thus providing accurate exposure. An exposure apparatus capable of transferring a simple pattern onto the wafer 10 is obtained. By the way, the reflection type mask according to the present invention is not limited to this, and the heat transfer layer 8 may be used.
It is not necessary to have. An example will be described with reference to FIG.
The reflective mask shown in FIG. 7 differs from the reflective mask shown in FIG. 6 in that the X-ray reflecting film 2 of the X-ray reflecting mirror is continuously formed on both the X-ray reflecting region 2a and the peripheral portion 2b. The X-ray absorber 11 having a predetermined pattern is formed on the X-ray reflection film 2. The Peltier element 3b, which is a cooling means, is in contact with the X-ray reflection film 2 formed on the peripheral portion 2b, absorbs the heat transmitted through the X-ray reflection film 2, and moves the X-ray reflection mirror. It is configured to cool. In addition, a temperature sensor 5 is disposed in a peripheral portion 2b near the X-ray reflection region 2a.

The X-ray absorber 11 of the reflective mask 18 is made of gold and has a characteristic of absorbing X-rays. Therefore, in the reflection type mask 18 shown in FIG. 7, the X-ray reflection film 2 is formed in the X-ray reflection region 2a, and reflects the X-rays at the portion where the X-ray reflection film 2 is exposed.
Since X-rays are absorbed by the X-ray absorber 11 formed above, contrast is formed in these two regions. Therefore, the pattern formed on the reflective mask can be transferred onto the wafer by X-ray projection exposure using the reflective mask 18. The X-ray absorber 11 may be made of copper, silver, or the like in addition to gold.

As described above, in the exposure apparatus according to each embodiment of the present invention, the X-ray reflecting mirror and the reflective mask are deformed by the heat generated by X-ray irradiation, and the optical characteristics of the optical system are changed. It can be prevented from changing. Furthermore, if the optical characteristics of the X-ray optical system have changed, the apparatus may be stopped to correct the change, the optical system of the apparatus may be adjusted, or exposure may be resumed after waiting for heat radiation. However, by adopting the present invention, the necessity is eliminated, and the throughput is improved.

The present invention is not limited to the reflection member used in each of the above embodiments. For example, also in the X-ray reflecting mirror, the heat transfer layer may be continuously provided on both the X-ray reflecting region 2a and the peripheral portion 2b. In this case, it is preferable to provide a heat transfer layer between the X-ray reflection film 2 and the substrate 1. In addition to the cooling by the cooling water passing through the cooling pipe and the cooling by the Peltier element 3b, the cooling means 3 also sprays a cooled or supercooled substance onto the peripheral portion 2b of the X-ray reflecting mirror, and A collection mechanism may be provided so that the substance does not enter the optical path of the X-ray reflected by the reflecting member. If the medium to be cooled does not go to the optical path of the X-rays, the intensity of the X-rays does not need to be reduced while cooling the X-ray reflecting member.

[0061]

As described above, when the X-ray reflecting mirror according to the present invention is used, the X-ray reflecting mirror provided at the peripheral portion allows the X-ray reflector to be used.
It is possible to efficiently cool the heat generated by the irradiation of the radiation. In addition, since the cooling means installed on the surface of the X-ray reflection film is installed in the peripheral part, there is no vignetting in the optical path, and the heat generated by irradiation can be efficiently cooled, and good optical performance is exhibited. A possible X-ray reflection optical element is obtained.

Further, by controlling the cooling amount, the X-ray reflecting mirror is not deformed by a temperature change caused by X-ray irradiation or a temperature change caused by the cooling amount of the cooling means being too large. An exposure apparatus that can operate while maintaining optical characteristics under any conditions can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exposure apparatus showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a projection system 19 used in the exposure apparatus according to the first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an X-ray reflecting mirror used in the exposure apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an X-ray reflecting mirror used in an exposure apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a modification of the X-ray reflecting mirror used in the exposure apparatus according to the second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a reflective mask used in an exposure apparatus according to a third embodiment of the present invention.

FIG. 7 is a view showing a modification of the reflection type mask used in the exposure apparatus according to the third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... X-ray reflection film 2a ... X-ray reflection area 2b ... Peripheral part 3 ... Cooling means 3b ... Peltier element 5 ... Temperature sensor 51 ... Resistive film DESCRIPTION OF SYMBOLS 6 ... Insulating film 8 ... Heat transfer layer 9 ... Opening 10 ... Wafer 11 ... X-ray absorber 12 ... Nozzle 14 ... Elliptical mirror 15 ... Parabolic surface Mirror 16: reflective fly-eye optical system 60a: first reflective element group 60b: second reflective element group 17: condenser mirror 18: reflective mask 19: projection system 30, 30a ··· cooling unit driving unit 300 ··· temperature control mechanism 310 ··· cooling unit control unit 311 ··· power supply unit 312 ··· temperature sensor output unit 313 ··· control unit 50b ··· Vacuum chamber 50a ・ ・ ・ Vacuum chamber window 90 ・ ・ ・ Lay Light source 91 ... focusing optical system

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G02B 17/00 G02B 7/18 Z

Claims (7)

[Claims] 1. A reflective optical element that reflects X-rays or extreme ultraviolet light, wherein: a substrate on which a reflective film can be formed over an area larger than a reflective region; and a reflective region and a region other than the reflective region on the substrate. A reflective optical element, comprising: the formed reflective film; and a cooling unit provided on the reflective film formed in a region other than the reflective region to cool the reflective film. 2. The reflective optical element according to claim 1, wherein a heat transfer layer made of a substance having a higher thermal conductivity than the substrate or the reflective film is provided between the substrate and the reflective film. A reflective optical element. 3. The reflective optical element according to claim 2, wherein the reflective film has an opening in a predetermined pattern where the reflective film is not formed. . 4. The reflection optical element according to claim 2, wherein an absorber for absorbing X-rays or extreme ultraviolet light having a predetermined pattern is formed on the reflection film. element. 5. The reflective optical element according to claim 1, further comprising: measuring a temperature of the reflective optical element.
A temperature measurement unit provided on a reflection film formed outside the reflection region; and a control unit for controlling the cooling unit so that the temperature measured by the temperature measurement unit falls within a predetermined range. A reflective optical element characterized by the following. 6. An exposure apparatus for transferring a pattern formed on a mask by a plurality of reflecting mirrors onto a wafer using X-rays or extreme ultraviolet rays, wherein the reflecting mirrors form a reflecting film over an area larger than a reflecting area. A substrate that can be formed, and the reflection film formed on the substrate over the reflection region and the region other than the reflection region, and further provided on the reflection film formed on the region other than the reflection region. A cooling unit that cools the reflection film; a temperature measurement unit that measures the temperature of the reflection mirror; and a control unit that controls the cooling unit based on information obtained by the temperature measurement unit. Exposure apparatus. 7. An illumination optical system which comprises a light source which emits X-rays or extreme ultraviolet rays and at least one or more multi-layer reflecting mirrors, which forms a pattern to be projected on a wafer and illuminates a mask, An exposure apparatus comprising the above multilayer reflector, and having a projection optical system for projecting X-rays from the mask onto a wafer, wherein at least one of the multilayer reflectors forming the projection optical system The film reflecting mirror has a substrate on which a reflective film can be formed over an area larger than the reflective region, and a reflective film formed on the substrate in a region other than the reflective region and the reflective region. A cooling unit and a temperature measurement unit provided on a reflection film formed in a region other than the reflection region; and a control unit that controls the cooling unit based on information from the temperature measurement unit. Dew Light device.