JP2002277620A - Amplitude division means, illuminating optical device having the amplitude division means, projecting exposure device, and exposing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an amplitude division means adoptable to <=200 nm short wavelength and capable of reducing the energy absorption, an effect interference reducing means using the amplitude division means when a light source has with interfering property and an illuminating optical device and a projecting exposure device applying the interference reducing means. SOLUTION: A plurality of plate-like members are superposed to each other and used as the amplitude division means. The interference reducing means is formed by the amplitude division means and a plurality of mirrors and applied to the illuminating optical device and the projecting exposure device. In the optical device and the exposure device, an S wave is preferably used as a light beam made incident on the division means. The reflection factor of the plate-like member is different between the incidence of P polarized light and that of S polarized light and a higher reflection factor can be secured by the incidence of S polarized light as compared with the incidence of P polarized light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a projection exposure apparatus, and more particularly to a projection exposure apparatus suitable for use in a projection exposure step during a semiconductor integrated circuit manufacturing process, or an illumination device mounted thereon.

[0002]

2. Description of the Related Art JP-A-11-174365,
In Japanese Patent Application Laid-Open No. -312631 and JP-A-2000-223396, the present applicant has proposed effective coherence reducing means when the light source has coherence. The present invention is an improvement on these inventions.

[0003]

Recently, there has been a remarkable reduction in the wavelength of a light source used in the technical field to which the present invention belongs. The conventional mainstream is K which emits light of 248.4 nm.
Although it was an rF excimer laser, it has recently been 193.3.
nm ArF excimer laser is becoming mainstream,
Further, an F2 excimer laser of 157.6 nm is being studied as a light source of a next-generation exposure machine.

[0004] The inventions described in the prior art all assume the existence of an amplitude dividing mirror, a so-called half mirror. However, the half mirror cannot sufficiently cope with the shortening of the wavelength to 200 nm or less. Even if the wavelength is short, a film material having a high transmittance does not easily exist, so that a half mirror having a large absorption is inevitably formed. The present invention has been devised in view of this point, and has a structure of 193.3 nm.
It is an object of the present invention to propose an amplitude dividing means that has a small absorption even at an extremely short wavelength such as 157.6 nm or 157.6 nm.

[0005]

In order to solve the above-mentioned problems, the present invention proposes that a plurality of plate-like members are superimposed and used as amplitude dividing means. It is desirable that the light beam incident on the amplitude dividing means is an S wave. This is because the reflectance of the plate member is different between the incidence of P-polarized light and the incidence of S-polarized light, and the incidence of S-polarized light can ensure a higher reflectance than the incidence of P-polarized light. Generally, glass has a refractive index of only about 1.5. For this reason, even if the parallel plane plate is slanted so that the angle (incident angle) between the direction of the light beam in the optical path and the perpendicular of the reflection surface of the parallel plane plate is 45 °, even if multiple reflection is taken into consideration, 9.
Only 3% reflection can be expected. For this reason, elementary glass is not usually recognized to have a function as a half mirror. However, if the light amplitude dividing means has a structure in which six plate members are stacked, the reflectance jumps to 32%. Furthermore, if the incident light is limited to S-polarized light, its reflectance is 55
It works fine as a half mirror. Further, the principle of the present invention will be described by calculating the effect of an optical delay structure using an optical amplitude dividing means having a structure in which plate members are stacked. FIG. 1 is a diagram for explaining the principle of the present invention.
In FIG. 1, the light amplitude dividing means 50 in which three uncoated parallel flat plates each having a thickness of 19.8 mm and an internal transmittance of 99.8% / cm are coated is placed. If the incident light is limited to S-polarized light, it becomes a mirror with a reflection of 41.6% and a transmission of 58.3%. Therefore, the total amount of light that can pass through this optical delay structure is 99.8 of the incident light.
% And only a loss of 0.2% occurs. On the other hand, in the conventional half mirror 60, the reflection is 40% and the transmission is 5%.
About 5% is used. 5% is absorption by the membrane. In this case, the total amount of light that can pass through the optical delay structure is 90% of the incident light, and a light amount loss of about 10% occurs. Hereinafter, the means of the present invention and the effects thereof will be described more specifically. In the first invention of the present invention, 200n
The amplitude dividing means for light having a wavelength of not more than m has a plurality of plate-like members that transmit light having a wavelength of not more than 200 nm stacked and inclined. Preferably, the thickness of the plate member is 0.1 mm to 5 mm, and the number of the plate members is 2 to 10 sheets. With such a configuration and limitation, even when used in a wavelength region of 200 nm or less, the loss of light amount is small, the plate member is not deformed, the light beam is not largely shifted by multiple reflections, and the transmitted light is not changed. Can be realized.

According to a second aspect of the present invention, a light source means for supplying a light beam, a surface light source forming means for dividing a light beam from the light source into a wavefront to form a pseudo surface light source, and the surface light source forming means In the illumination optical device having the condenser optical system for illuminating the mask pattern with the illumination light from the pseudo surface light source formed by the method, the coherence reducing means having the amplitude dividing means according to the first invention is provided.

According to a third aspect of the present invention, there is provided a light source unit for supplying a light beam, a surface light source forming unit for forming a pseudo surface light source by dividing a light beam from the light source into a wavefront, and the surface light source forming unit. A condenser optical system that illuminates a mask pattern with illumination light from a pseudo surface light source formed by a projection optical system, and a projection optical system that projects and exposes the mask pattern to a surface to be exposed using the illumination light. The projection exposure apparatus may be arranged such that the amplitude dividing means is disposed between the light source means and the surface light source forming means, or the coherence reducing means using the amplitude dividing means is formed between the light source means and the surface light source forming means. Place between means. With such a configuration, 200
Even when used as a light source in the wavelength region of nm or less, it is possible to realize an illumination system with reduced loss of light amount and reduced coherence, or an illumination system of a projection exposure apparatus.

According to a fourth aspect of the present invention, the light beam supplied from the light source is substantially linearly polarized light and is incident on the amplitude dividing means as an S wave.
The angle of incidence of the light beam incident on the amplitude dividing means is 45
° or more. With such a configuration,
Even if it is used in a wavelength region of 200 nm or less, it is possible to realize an amplitude dividing means with a small loss of light quantity and a high reflectance per one plate member.

According to a fifth aspect of the present invention, the plate-like member of the amplitude dividing means is made of glass. Alternatively, the sixth invention of the present invention is characterized in that the material of the plate member of the amplitude dividing means is any of synthetic quartz, fluorite, magnesium fluoride, fluorine-doped quartz, and quartz.
By using such a known material having a high transmittance in a wavelength region of 200 nm or less, it is possible to realize an amplitude dividing unit with a smaller loss of light amount according to the higher transmittance.

[0010] In the seventh invention of the present invention, the thickness of 200 nm
The amplitude splitting means for light having the following wavelengths is characterized in that the amount of light absorbed by the amplitude splitting means is less than 5% of the total amount of incident light having a wavelength of 200 nm or less. With such a feature, it is possible to realize an amplitude dividing unit having less loss of light quantity than an amplitude dividing unit having a known thin film.

Further, according to an eighth aspect of the present invention, a light source means for supplying a light beam, a surface light source forming means for dividing a light beam from the light source into a wavefront to form a pseudo surface light source, and a surface light source forming means A condenser optical system that illuminates a mask pattern with illumination light from a pseudo-surface light source formed by an exposure method having a projection optical system that projects and exposes the mask pattern onto a surface to be exposed using the illumination light. An exposure method comprising the amplitude dividing means according to the first invention. With such a configuration, even when used as a light source unit in a wavelength region of 200 nm or less, it is possible to realize an exposure method in which loss of light amount is small and coherence is reduced.

[0012]

FIG. 2 shows a first embodiment of an illuminating device for an exposure apparatus using a light dividing means according to the present invention. FIG.
In describing the configuration of this embodiment from the light source side, a light source 1, a quarter-wave plate 2, a depolarizer 3, a first optical delay structure 4, a second optical delay structure 5, a fly-eye optical integrator 6.

The light source 1 is a light source that emits light of 193.3 nm.
rF excimer laser. The fly-eye optical integrator 6 is one of surface light source forming means for dividing a light beam into a wavefront and forming a pseudo surface light source. The optical amplitude dividing means 40 and 50 according to the present invention include the optical delay
1 mm as in the configuration shown in FIG.
Three thick uncoated plate-like members are arranged in an overlapping manner.
The role of the optical delay structures 4 and 5 is to amplitude-divide the light beams incident on them, and to split the two light beams by an optical path constituted by two mirrors (41a, 41b or 51a, 51b) by a distance longer than the coherence distance. By providing an optical path difference and synthesizing two light beams again by the light amplitude dividing means, the number of modes in the light beam is increased and speckle is reduced. Here, the optical amplitude dividing means 40 and 5
The incident angle of the light beam to 0 is preferably 45 °, and 45 °.
° or more is also suitable. The functions of the depolarizer 3 and the optical delay structures 4 and 5 in this embodiment and the function as an illumination device are described in Japanese Unexamined Patent Publication No.
It is basically the same as 126126. FIG. 3 shows a second embodiment of an illuminating device for an exposure apparatus using the light dividing means according to the present invention. In FIG. 3, the configuration of the present embodiment is described from the light source side. The light source 1, the shaping optical system 22, the first optical delay structure 4, the second optical delay structure 5, the fly-eye optical integrator 6, the condenser lens 27. The light source 1 is an ArF excimer laser that emits light of 193.3 nm. The fly-eye optical integrator 6 is one of surface light source forming means for dividing a light beam into a wavefront and forming a pseudo surface light source.

The light amplitude dividing means 70 and 80 according to the present invention
Are components of the optical delay structures 4 and 5. The role of the optical delay structures 7 and 8 is to divide the light beams incident on each of them into amplitudes and to split the light into four mirrors (71a, 71b, 71c, 71d).
Alternatively, an optical path composed of 81a, 81b, 81c, and 81d) gives an optical path difference equal to or longer than the coherence distance to the two split light beams, and combines the two light beams again by the light amplitude splitting means, thereby obtaining a light beam within the light beam. The purpose is to increase the number of modes and reduce speckle. By employing such an optical delay structure, it is possible to realize an illumination optical system with a small loss of light amount. The functions of the shaping optical system 22 and the optical delay structures 7 and 8 in this embodiment and the function as an illumination device are basically the same as those of Japanese Patent Application Laid-Open No. 2000-223396 by the same applicant as the present application. . FIG. 4 is a diagram schematically illustrating a configuration of an exposure apparatus including the illumination optical device according to the embodiment of the present invention. The outline of the function of the exposure apparatus in this embodiment will be described with reference to FIG. 4, the optical axis AX of the projection optical system 16 is shown.
, The X axis is set in a plane perpendicular to the optical axis AX, the X axis is set parallel to the plane of FIG. 4, and the Y axis is set perpendicular to the plane of FIG. The projection exposure apparatus in FIG. 4 includes an ArF excimer laser that supplies light having a wavelength of 193.3 nm as a light source 11 for supplying exposure light (illumination light). Light emitted from the light source 11 enters the illumination optical system 12.

The mask 13 is held on a mask stage 15 via a mask holder 14 in parallel with the XY plane. Light from the pattern formed on the mask 13 forms a (reduced) image of the mask pattern on a wafer 17 as a photosensitive substrate via the projection optical system 16.
The wafer 17 is held on a wafer stage 19 via a wafer holder 18 in parallel with the XY plane. The wafer stage 19 is two-dimensionally movable along the wafer surface (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are measured by an interferometer 20 using a movable mirror. It is configured to be controlled.

In this manner, the wafer 17 is two-dimensionally driven and controlled in the plane (XY plane) orthogonal to the optical axis AX of the projection optical system 16 using the drive system and the interferometer (20). The pattern of the mask 13 is sequentially exposed to each of the exposure regions. Alternatively, the pattern of the mask 13 is scanned and exposed on each exposure area of the wafer 17 while relatively moving the mask 13 and the wafer 17 along the scanning direction with respect to the projection optical system 16.

In the above-described embodiment, the light source 1 is a 193.3 nm ArF excimer laser, which is becoming mainstream in recent years, but a 157.6 nm F2 excimer laser which is being studied as a light source for a next-generation exposure machine. Etc. can be used. Also, other than the above laser, other,
It is also possible to use a short wavelength light source having a wavelength shorter than 200 nm. The present invention is considered to be particularly suitable for use with a light source of 200 nm or less among many light sources.

The wafer that has undergone the exposure step (photolithography step) by the exposure apparatus of the above-described embodiment undergoes a development step, and then an etching step of removing unnecessary portions of the element material, and an unnecessary resist after the etching step. After the resist removal step, the process proceeds to the next wafer processing step.

The circuit pattern is formed on the wafer by performing the wafer process steps including the steps described above usually many times. In the actual assembling process, each process such as dicing for cutting a wafer into chips for each formed circuit, bonding for providing wiring and the like to each chip, and packaging process for packaging each chip is performed. After that, a semiconductor device (such as an LSI) is finally manufactured as a device.

In the above description, a semiconductor device is manufactured by a photolithography process in a wafer process using a projection exposure apparatus. A display device, a thin-film magnetic head, and an imaging device (such as a CCD) can be manufactured. Thus, in the case of an exposure method for manufacturing a semiconductor device using the illumination optical apparatus utilizing the present invention, projection exposure is performed under favorable exposure conditions in which illumination unevenness due to interference is small and light amount loss is small. Therefore, a good semiconductor device can be manufactured.

In the above embodiment, a fly-eye lens in which a plurality of lens elements are arranged in a matrix is used as an optical integrator. However, the optical integrator of the present invention is not limited to a fly-eye lens. For example, an internal reflection type rod integrator may be applied. In this case, it is preferable that the optical delay structure in the present invention is arranged in the optical path between the light source and the rod-type integrator.

In the above-described embodiment, the uncoated parallel plane plate is used as a part of the half mirror. However, the present invention is not limited to this, and a coated parallel plane plate can be used. As the material of the parallel flat plate, it is preferable to use synthetic quartz, fluorite, magnesium fluoride, fluorine-doped quartz, quartz, or other materials having a predetermined transmittance at 200 nm or less.

[0023]

As described above, in the amplitude division means of light having a wavelength of 200 nm or less, in which a great loss of light quantity cannot be avoided, a light amplitude means without loss of light quantity has become possible. Also, JP-A-11-174365 and JP-A-11-174.
When applying the light source coherence reducing means proposed in Japanese Patent Application Laid-Open No. 312631 and JP-A-2000-223396 to an illuminating device and an exposing device using a wavelength shorter than 200 nm, it has been conventionally thought that a large light amount loss cannot be avoided. However, according to the present invention, it is possible to implement the coherence reducing means without loss of light quantity.

[Brief description of the drawings]

FIG. 1 is an optical delay structure of the present invention.

FIG. 2 is an embodiment of the present invention.

FIG. 3 shows one mode of an embodiment of the present invention.

FIG. 4 is a schematic view of an exposure apparatus equipped with an illumination system having an optical delay structure according to the present invention, and is an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 light source 2 quarter-wave plate 3 depolarizer 4 first optical delay structure 5 second optical delay structure 6 fly-eye optical integrator 7 first optical delay structure 8 second optical delay structure 11 light source DESCRIPTION OF SYMBOLS 12 Illumination optical system 13 Mask 14 Mask holder 15 Mask stage 16 Projection optical system 17 Wafer 18 Wafer holder 19 Wafer stage 20 Interferometer 22 Shaping optical system 27 Condenser lens 40 Light amplitude splitting means 41a, 41b mirror 50 of the present invention Light amplitude dividing means 51, 51a, 51b mirror 60 Conventional half mirror 70 Light amplitude dividing means 71a, 71b, 71c, 71d mirror of the present invention 80 Light amplitude dividing means 81a, 81b, 81c, 81d mirror of the present invention

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Claims (12)

[Claims] A plurality of plate members that transmit light having a wavelength of 200 nm or less are stacked and inclined.
Means for dividing the amplitude of light having the following wavelengths. 2. The method according to claim 1, wherein the thickness of the plate-like member is equal to 0.
Amplitude dividing means of 1 mm to 5 mm. 3. The amplitude dividing means according to claim 1, wherein the number of plate members to be overlapped is 2 to 10. 4. A light source means for supplying a light beam, a surface light source forming means for dividing a light beam from the light source into a wavefront to form a pseudo surface light source, and a pseudo surface formed by the surface light source forming means. An illumination optical device having a condenser optical system for illuminating a mask pattern with illumination light from a light source, wherein an interference coherence reducing means having the amplitude dividing means according to claim 1, 2, or 3 is provided. 5. A light source means for supplying a light beam, a surface light source forming means for dividing a light beam from the light source into a wavefront to form a pseudo surface light source, and a pseudo surface formed by the surface light source forming means. In a projection exposure apparatus having a condenser optical system for illuminating a mask pattern with illumination light from a light source and a projection optical system for projecting and exposing the mask pattern to a surface to be exposed using the illumination light, the light source means and the surface light source 4. A projection exposure apparatus comprising the amplitude division means according to claim 1, 2 or 3, between the projection exposure apparatus and the formation means. 6. A light source means for supplying a light beam, a surface light source forming means for dividing a light beam from the light source into a wavefront to form a pseudo surface light source, and a pseudo surface formed by the surface light source forming means. In a projection exposure apparatus having a condenser optical system for illuminating a mask pattern with illumination light from a light source and a projection optical system for projecting and exposing the mask pattern to a surface to be exposed using the illumination light, the light source means and the surface light source 4. A projection exposure apparatus comprising a decoherer using the amplitude dividing means according to claim 1, between said forming means and said forming means. 7. The illumination optical device according to claim 4, wherein the light beam supplied from said light source means is substantially linearly polarized light and is incident on said amplitude dividing means as an S wave. Projection exposure equipment. 8. An illumination optical apparatus according to claim 4, wherein the incident angle of the light beam incident on said amplitude dividing means is 45 ° or more. 9. The amplitude dividing means according to claim 1, wherein said plate-like member is glass. 10. The method according to claim 1, wherein the material of the plate-like member is
Amplitude dividing means, which is one of synthetic quartz, fluorite, magnesium fluoride, fluorine-doped quartz, and quartz. 11. An amplitude dividing means for light having a wavelength of 200 nm or less, wherein the amount of light absorbed by the amplitude dividing means is 5% of the total amount of incident light having a wavelength of 200 nm or less.
Amplitude dividing means characterized by being less. 12. A light source means for supplying a light beam, a surface light source forming means for dividing a light beam from the light source into a wavefront to form a pseudo surface light source, and a pseudo surface formed by the surface light source forming means. 4. An exposure method comprising: a condenser optical system for illuminating a mask pattern with illumination light from a light source; and a projection optical system for projecting and exposing the mask pattern to a surface to be exposed using the illumination light. An exposure method comprising an amplitude dividing means.