JPH0749561A - Production of aligner device and element using reflection type mask - Google Patents

Abstract

PURPOSE:To miniaturize the aligner and to enhance the accuracy of exposure and transfer by exposing a wafer by using a reflection type mask formed by using a reflection layer having a multilayered film structure alternately laminated with plural materials varying in optical constants as a reflection part. CONSTITUTION:Layers 2, 4 of a first material and layers 3, 5 of a second material are alternately laminated on a substrate 1 having a plane surface, by which the reflection mirror part is formed thereon. Absorbers A for soft X-rays and vacuum UV rays patterned to desired shapes are disposed on the uppermost layer thereof. The soft X-rays which are generated from a divergent X-ray source and are made incident by specular reflection on the reflection type mask M0 constituted by forming the exposure patterns by the reflection layer having the multilayered film structure alternately laminated with the layers 2, 4 of the first material and the layers 3, 5 of the second material varying in the optical constants and the absorbers A on the substrate 1 are admitted via the reflection part of the mask M0 into a projecting optical system and are reflected by a concave face mirror M1, a convex face mirror M2 and a concave face mirror M3 in this order, by which the images of the mask M0 are formed on the exposed substrate (wafer). The element patterns are thus transferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an exposure apparatus and an element using a reflective mask, which is suitable for lithography using soft X-rays or vacuum ultraviolet rays.

[0002]

2. Description of the Related Art Conventionally, as an X-ray reflecting portion of a reflection type mask used for manufacturing an exposure apparatus and an element using X-ray,
A single crystal plate was used (Japanese Patent Application No. 52-54126).
issue). However, since this reflection type mask for X-ray exposure utilizes Bragg diffraction of a single crystal, X-ray incidence must be oblique incidence, and energy loss due to the mask was large. As a result, the mask area becomes very large,
Since it is large, it is difficult to make it flat and uniform, and there are problems such as low utilization efficiency of radiated light.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and it is an object of the present invention to achieve a drastic downsizing of an exposure apparatus and a high accuracy of exposure transfer.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-described problems, and the gist thereof is different in optical constants.
An optical system for irradiating exposure radiation to a reflective mask having a reflective layer having a multilayer film structure in which layers of various types are alternately laminated and an exposure pattern by an absorber are formed on a substrate,
An exposure apparatus comprising: an optical system for projecting radiation reflected by the reflective mask onto a wafer to transfer an exposure pattern to the wafer; and a multilayer film in which two types of layers having different optical constants are alternately laminated. A step of irradiating a reflective mask having a reflective layer having a structure and an element pattern of an absorber formed on a substrate with exposure radiation, and projecting the radiation reflected by the reflective mask onto a wafer. And a step of transferring an element pattern onto a wafer.

The present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an example of a multilayer film reflection type mask for soft X-ray / vacuum ultraviolet exposure used in an exposure apparatus and a method for manufacturing an element of the present invention.

In this multilayer reflective mask, as shown in the figure, a first material layer 2, 4, ...
.. are alternately laminated to form a reflecting mirror portion, and an absorber A for soft X-ray / vacuum ultraviolet light, which is patterned into a desired shape, is arranged on the uppermost layer thereof. There is.

The film thicknesses d ₁ , d _2, ... Of the respective layers are 10 A or more, and the film thicknesses are alternately equal (d ₁ = d ₃ = ...,
d ₂ = d ₄ = ...) is acceptable even if all film thicknesses are changed, but the amplitude is reduced by absorption of soft X-rays and vacuum ultraviolet rays in each layer, and the reflected light at the interface of each layer is reduced. In consideration of both the strengthening of reflected light due to the overlapping of phases, it is preferable that the thickness of the reflecting mirror as a whole be such that the highest reflectance is obtained. The thickness of each layer is 10Å
If it is smaller, it is not preferable because a high reflectance cannot be obtained as a reflecting mirror due to the effect of diffusion of two substances at the interface. The reflectance increases as the number of layers increases, but on the other hand, manufacturing difficulties arise. Therefore, the number of laminated layers is preferably 200 or less.

The absorber absorbs soft X-rays and vacuum ultraviolet rays,
Any material may be used as long as it has high thermal conductivity and low thermal expansion, but specifically, it has a linear expansion coefficient of 5 × 10 ⁻⁵ / deg or less and a thermal conductivity of 0.1 J / cm · s · deg or more. What is good is. If the coefficient of linear expansion and the thermal conductivity are larger than the above values, the problem that the absorber and the reflecting mirror having the multilayer structure are displaced or separated easily occurs. As a substance forming such an absorber, for example, metals such as gold, tantalum, and tungsten, semiconductors such as silicon, and insulators such as silicon nitride, silicon carbide, and tantalum nitride are preferably used.

FIG. 3 is an optical path diagram of the projection optical system of the exposure apparatus using the reflective mask of the present invention.

According to the present invention, a reflective layer having a multilayer film structure in which first material layers 2 and 4 having different optical constants and second material layers 3 and 5 having different optical constants are alternately laminated, and an exposure pattern by an absorber A are provided. Is generated from the divergent X-ray source to the reflection-type mask M ₀ formed on the substrate 1 and the soft X-rays which are normally incident are incident on the mask M _0.
The element pattern is transferred to the projection optical system through the reflection part of the concave mirror, the concave mirror M ₁ , the convex mirror M ₂ , and the concave mirror M ₃ are sequentially reflected to form the image of the mask M _{0 on} the exposure substrate (wafer). It is a method of manufacturing an exposure apparatus and an element that can be performed.

[0012]

EXAMPLES The present invention will be described in more detail with reference to Examples of the present invention. Example 1 As shown in FIG. 2 (a), a substrate 1 is made of a silicon single crystal plate polished to have a surface roughness of 10 Å or less as an rms value, and a material forming the first layers 2, 4 ... As ruthenium (Ru) and silicon carbide (SiC) as the material forming the second layers 3, 5, ... After reaching an ultra high vacuum of 1 × 10 ⁻⁶ Pa or less, the argon pressure is 5 × 10 ⁻¹ Pa. And the film thickness was 29.8Å and 33.9Å respectively by the sputter deposition method.
41 layers (Ru layer 21 layers, SiC: 20 layers) were laminated as above, and further 10 l of carbon (C) was laminated thereon as a protective film B to obtain a multilayer laminated plate. In this case, the first layer has a small real part of the refractive index and the second layer has a large real part of the refractive index.

Next, as shown in FIG. 2B, a PMMA layer as a resist is formed to a thickness of 0.5 μm on this multilayer laminated plate, and 1.75 μm lines and spaces are patterned by EB drawing. Gold (a linear expansion coefficient of 1.42 × 10 ⁻⁵ / deg, a thermal conductivity of 3.16 J / cm 2) which is a soft X-ray absorber is formed on the patterned resist C made of PMMA.
.S.deg) was formed by EB vapor deposition to a thickness of 0.1 .mu.m. Next, the PMMA is peeled off, and the gold pattern A is formed on the multilayer film.
Was obtained (FIG. 2 (c)).

Next, soft X-ray exposure was performed using the multilayer reflective mask thus prepared.

FIG. 3 is an optical path diagram of the projection optical system.
The line reflection mirrors M ₁ , M ₂ and M ₃ are a concave mirror, a convex mirror and a concave mirror, respectively, and W is an exposure substrate. M ₀ is the multilayer reflective mask. The position is shown in the figure. Generated from a divergent X-ray source and 1.7 ° with respect to the mask M ₀
The soft X-rays incident at an angle of (normal incidence) enter the projection optical system via the reflecting portion of the mask M ₀ , and are concave mirror M ₁ and convex mirror M ₁ .
₂ , the concave mirror M ₃ is reflected in this order, and the image of the mask M ₀ is formed on the exposure substrate W. This projection optical system has a projection magnification of 1 /
5, effective F number 13, image plane size 28x14m
m ² , the image height is 20 to 37 mm, and the resolution is 0.35 μm.

A soft X-ray of 124 Å was used as a light source, and PMMA 1 μm was applied to the exposed substrate W. When a soft X-ray is generated and the PMMA resist on the exposure substrate W is exposed and developed by a projection exposure system, 0.35 μm line &
Space resolved. Example 2 On a silicon single crystal plate 1 polished in the same manner as in Example 1, tantalum nitride (Ta) was used as a material for the first layers 2, 4 ...
N) and silicon (S) as a material forming the second layers 3, 5 ...
i), after reaching an ultra high vacuum of 1 × 10 ⁻⁶ Pa or less,
Keeping the argon pressure at 5 × 10 ⁻¹ Pa and setting the film thickness to 20.3Å and 40.6Å respectively by the sputter deposition method,
41 layers (TaN: 21 layers, Si: 20 layers) were laminated, and further 10 A of carbon (C) was laminated thereon as a protective film B.
In this case, the first layer has a small real part of the refractive index and
The real part of the refractive index of the layer is large.

Next, PMMA0.
5 μm was formed and patterned by EB drawing.
On this PMMA pattern, tantalum (Ta) (linear expansion coefficient 6.3 × 10 ⁻⁶ / deg, thermal conductivity 0.575 J / cm · s · deg), which is a soft X-ray absorber, was formed by EB vapor deposition to a thickness of 0.1 μm. After thickly forming, PMMA was peeled off to obtain a tantalum pattern A on the multilayer film.

Using the mask produced here, Example 1
The PMMA on the exposure substrate W was exposed by the reduction optical system shown by. As a result, 0.35 μm line and space was resolved. Example 3 On a silicon single crystal plate polished in the same manner as in Example 1, the first
(Pd) is used as a material for forming the layers 2, 4 ... and Silicon (Si) is used as a material for forming the second layers 3, 5 ..., and EB vapor deposition is performed in an ultrahigh vacuum of 1 × 10 ⁻⁶ Pa or less. Thus, 41 layers (Pd: 21 layers, Si: 20 layers) were laminated with film thicknesses of 21.1Å and 40.3Å, respectively, and further 10Å of carbon (C) was laminated thereon as a protective film.
In this case, the first layer has a small real part of the refractive index and
The real part of the refractive index of the layer is large.

Next, PMMA0.
5 μm was formed and patterned by EB drawing.
On this PMMA pattern, silicon (Si) as a soft X-ray absorber (coefficient of linear expansion of 2.6 × 10 ⁻⁶ / deg, thermal conductivity of 1.49 J / cm · s · deg) was formed by EB vapor deposition.
After forming a film having a thickness of 1 μm, PMMA was peeled off to obtain a silicon pattern A on the multilayer film.

Using the mask produced here, Example 1
The PMMA on the exposure substrate W was exposed by the reduction optical system shown by. As a result, 0.35 μm line and space was resolved.

In the embodiment of the present invention, the ⅕ reduction optical system (0.35 μm resolution) having the configuration shown in FIG. 3 is assumed, but it goes without saying that an exposure optical system having other specifications and configurations may be used. May be used.

In the examples, the EB vapor deposition method and the sputtering method were used for forming the multilayer film, but the present invention is not limited to this, and other resistance heating, CVD,
Various thin film forming methods such as reactive sputtering can be used. Although a Si single crystal plate was used as the substrate, the substrate is not limited to this, and any substrate such as glass, fused silica, silicon carbide, etc., whose surface is sufficiently smooth compared to the wavelength used, can be used. Good.

[0023]

According to the present invention, a wafer is exposed by using a reflective mask having a reflective layer having a multilayer structure in which two substances having different optical constants are alternately laminated as a reflective portion. Unlike the reflecting mirror using Bragg diffraction of the single crystal, it is not necessary to obliquely enter the radiation from the horizontal direction, the radiation can be directly incident on the mask, and the utilization efficiency of the emitted light is high. As a result, it is possible to significantly reduce the size of the exposure apparatus and improve the accuracy of exposure transfer.

[Brief description of drawings]

FIG. 1 is a basic sectional view of a multilayer film reflective mask for soft X-ray / vacuum ultraviolet exposure used in the present invention.

2A, 2B, and 2C are manufacturing process diagrams of a multilayer film reflection mask used in the present invention.

FIG. 3 is an optical path diagram of a projection optical system of the exposure apparatus of the present invention.

[Explanation of symbols]

1 Si substrate 2,4 First substance layer 3,5 Second substance layer A Soft X-ray / vacuum ultraviolet absorber B Protective film C Resist (PMMA) M ₀ Soft X-ray / vacuum ultraviolet exposure multilayer film Reflective mask M ₁ concave X-ray mirror M ₂ convex X-ray mirror M ₃ concave X-ray mirror W exposure substrate d _{1 to} d ₄ thickness of each layer

Claims (4)

[Claims] 1. A reflective mask having a reflective layer having a multilayer film structure in which two types of layers having different optical constants are alternately laminated and an exposure pattern of an absorber are formed on a substrate,
An exposure apparatus comprising: an optical system for irradiating exposure radiation; and an optical system for projecting the radiation reflected by the reflective mask onto a wafer to transfer an exposure pattern onto the wafer. 2. A reflection type mask in which a reflection layer having a multilayer film structure in which two types of layers having different optical constants are alternately laminated and an element pattern made of an absorber are formed on a substrate,
A method for manufacturing an element, comprising: a step of irradiating exposure radiation; and a step of projecting the radiation reflected by the reflective mask onto a wafer to transfer an element pattern to the wafer. 3. The exposure apparatus according to claim 1, or the element manufacturing method according to claim 2, wherein the projection is reduction projection. 4. The exposure apparatus according to claim 1, or the element manufacturing method according to claim 2, wherein the radiation is soft X-rays or vacuum ultraviolet rays.