JP2675263B2 - Exposure apparatus and exposure method using reflective mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention uses soft X-rays and vacuum ultraviolet rays.
A reflective mask suitable for the used lithography was used.
Exposure equipmentExposure methodIt is about. [0002] 2. Description of the Related Art Conventionally, an exposure apparatus using X-rays andExposure method
LawThe X-ray reflection part of the reflective mask used for
A crystal plate was used (Japanese Patent Application No. 52-54126).
issue). However, this reflective mask for X-ray exposure is a single crystal
In order to utilize the Bragg diffraction of
Must be done, and the energy loss due to the mask is also large
Was. As a result, the mask area becomes very large,
Because it is large, it is difficult to make it flat and uniform.
,EnteringProblems such as low utilization efficiency of the emitted light have occurred. [0003] The present invention is based on the above-mentioned conventional example.
In view of the problems of
The purpose of this is to achieve high precision of. [0004] The present invention solves the above problems.
The purpose of the decision is 2
A reflective layer having a multilayer film structure in which different types of layers are alternately laminated;
A reflective mask with a pattern formed by an absorber on the substrate.
Against the skSoft X-ray or vacuum ultraviolet rayToEnteringShootmeans
And was reflected by the reflective maskSoft X-ray or vacuum ultraviolet ray
ToExposed substrateToEnteringShootExposed substrateToThePatternImagingDo
projectionAn exposure apparatus having an optical system, and
A multilayer film structure in which two types of layers having different optical constants are alternately laminated
A reflective layer having a structure and a pattern formed by an absorber on the substrate
For the formed reflective mask,Soft X-ray or vacuum ultraviolet
lineToEnteringAnd the step of irradiating and reflected by the reflective maskSoft X
Line or vacuum ultravioletToExposed substrateToEnteringShootExposed substrateToThePa
TurnImagingAnd a step ofexposure
On the way. The present invention will be described below with reference to the drawings. FIG. 1 is for soft X-ray or vacuum UV exposureofmultilayer
Film reflective maskStructuralIt is a model type sectional view of an example. This multilayer reflective mask is shown in the figure.
And the second layer of the first material 2 on the planar substrate 1
The layers of material 3, 5 ... Are alternately laminated to form the reflector portion.
Formed and patterned on top of it to the desired shape
Absorber A for soft X-rays and vacuum ultraviolet rays is arranged.
You. Film thickness d of each layer₁ , D_Two ... is 10A or more
And the film thicknesses are alternately equal and (d₁ = D_Three =…,
d_Two = D_Four ＝…), all the film thickness can be changed
However, soft X-rays and vacuum ultraviolet rays in each layer
Amplitude reduction due to absorption and at the interface of each layer
Both of the strengthening of the reflected light due to the overlapping of the phases of the reflected light
In consideration of the above, the highest reflectance is obtained for the entire reflector.
Such a thickness is preferable. The thickness of each layer is 10Å
If smaller, the effect of diffusion of two substances at the interface
Therefore, it is not preferable because a high reflectance cannot be obtained as a reflecting mirror.
No. The reflectance increases as the number of layers increases.
However, on the other hand, manufacturing difficulties will occur. That
Therefore, the number of laminated layers is preferably 200 or less. The absorber absorbs soft X-rays and vacuum ultraviolet rays,
Any material with high thermal conductivity and low thermal expansion
However, specifically, the coefficient of linear expansion is 5 × 10.^-FiveBelow / deg
The thermal conductivity is 0.1 J / cm · s · deg or more.
Things are good. Greater linear expansion coefficient and thermal conductivity
In this case, the absorber and the multi-layer reflecting mirror may be misaligned or separated.
It is easy to cause problems. Form such an absorber
Examples of substances include gold, tantalum, and tungsten.
Any metal, semiconductor such as silicon, silicon nitride, silicon carbide
Insulators such as elemental and tantalum nitride are preferably used. FIG. 3 showsthe aboveExposure system using reflective mask
3 is an optical path diagram of the projection optical system of FIG. Layers 2 and 4 of the first substance having different optical constants
A multilayer film structure in which layers 3 and 5 of the second substance are alternately laminated
The reflective layer and the exposure pattern formed by the absorber A have the substrate 1
Reflective mask M formed on top₀ Against a divergent X-ray source
The soft X-rays generated from₀ Reflective part of
Enter the projection optical system via the₁ , Convex mirror M_Two,
Concave mirror M_Three Mask in the order of₀ Image on the exposed substrate
To form an imageexposureTo be able to transfer the pattern
Exposure equipment andexposureIs the way. [0012] EXAMPLES The present invention will be further described below with reference to Examples of the present invention.
This will be described in detail. Example 1 As shown in FIG. 2A, the surface roughness of the substrate 1 is rms value.
A silicon single crystal plate polished to 10 Å or less by
Ruthenium is used as a material for the first layers 2, 4 ...
(Ru), silicon carbide as a material forming the second layers 3, 5 ...
1x10 using elemental (SiC)^-6Ultra high vacuum of Pa or less
After reaching, set the argon pressure to 5 × 10^-1Keep at Pa
The film thickness is 29.8Å and 33.9Å respectively by the vapor deposition method.
41 layers (Ru layer 21 layers, SiC: 20 layers) as a stack
On top of that, as a protective film B, 10 l of carbon (C) is stacked.
Layered to obtain a multilayer laminate. In this case, the first layer is
The real part is small and the second layer is the real part of the refractive index is large
is there. Next, as shown in FIG. 2B, this multilayer product is
PMMA layer as a resist is 0.5μm thick on the layer plate
Formed on EB and 1.75μm line & space by EB drawing
Patterning of the PMMA pattern
Gold as a soft X-ray absorber (coefficient of linear expansion
1.42 x 10^-Five/ Deg, thermal conductivity 3.16 J / cm
・ S ・ deg) is formed by EB evaporation to a thickness of 0.1 μm
Was. Next, the PMMA is peeled off, and the gold pattern A is formed on the multilayer film.
Was obtained (FIG. 2 (c)). Next, using the multilayer reflective mask created
Soft X-ray exposure was performed. FIG. 3 is an optical path diagram of the projection optical system.
Line reflection mirror M₁ , M_Two , M_Three Are concave mirror and convex surface, respectively
A mirror and a concave mirror, and W indicates an exposure substrate. M₀ Is
The above-mentioned multilayer reflective mask. The position is shown in the figure
You. Mask M generated from divergent X-ray source₀ To 1.7 °
X-rays incident at an angle of (normal incidence) are masks M₀ Reflection of
Enters the projection optical system through the section, and the concave mirror M₁ , Convex mirror M
_Two , Concave mirror M_Three In the order of, mask M₀ The image of the exposure base
An image is formed on the plate W. This projection optical system has a projection magnification of 1 /
5, effective F number 13, image plane size 28x14m
m^Two , Image height is 20 ~ 37mm, resolution is 0.35μm
is there. As the light source, a soft X-ray of 124 Å was used, and the exposure substrate
The plate W was coated with 1 μm of PMMA. Generates soft X-rays
The projection exposure system allows the PMMA resist on the exposed substrate W to be
When exposed to light and developed, 0.35 μm line &
Space resolved. Example 2 On a silicon single crystal plate 1 polished in the same manner as in Example 1,
As the material forming the layers 1, 2, ..., Tantalum nitride (Ta
N) and silicon (S) as a material forming the second layers 3, 5 ...
1) using i)^-6After reaching an ultra-high vacuum of Pa or less,
Argon pressure is 5 × 10^-1Keeping at Pa, sputter deposition method
By setting the film thickness to 20.3Å and 40.6Å respectively,
41 layers (TaN: 21 layers, Si: 20 layers) are laminated, and further
On top of this, carbon (C) 10 is formed as a protective film B.ÅLaminated.
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.
Tantalum which is a soft X-ray absorber on this PMMA pattern
(Ta) (coefficient of linear expansion 6.3 × 10^-6/ Deg, thermal conductivity
0.575 J / cm · s · deg) by EB evaporation
After forming 0.1 μm thick, peel off PMMA and
A tantalum pattern A was obtained on the top. Using the mask produced here, Example 1
The PMMA on the exposed substrate W is exposed by the reduction optical system shown in.
Glowed. 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) as the material forming the layers 2, 4 ...
Silicon (Si) is used as a material for the layers 2, 5 ...
Yes, 1 × 10^-6EB vapor deposition in ultra-high vacuum of Pa or less
By the method, the film thickness is set to 21.1Å and 40.3Å
41 layers (Pd: 21 layers, Si: 20 layers), and then
Then, 10 Å 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.
Silicon as a soft X-ray absorber on this PMMA pattern
(Si) (coefficient of linear expansion 2.6 × 10^-6/ Deg, thermal conductivity
1.49 J / cm.s.deg.
After forming 1 μm thick, peel off the PMMA and put it on the multilayer film.
A silicon pattern A was obtained. Using the mask produced here, Example 1
The PMMA on the exposed substrate W is exposed by the reduction optical system shown in.
Glowed. As a result, 0.35 μm line and space
Was resolved. The embodiment of the present invention is shown in FIG.
1/5 reduction optical system (0.35 μm resolution)
However, of course, the exposure optical system with other specifications and configurations can be used.
May be used. Further, in the embodiment, in forming a multilayer film,
I used the EB evaporation method and the sputtering method.
However, the resistance heating, CVD,
For forming various thin films such as reactive sputtering
Method can be used. Also, as a substrate, a Si single crystal plate
However, it is not limited to glass, fused silica, and silicon carbide.
It is a substrate such as a substrate, and its surface is sufficient compared to the wavelength used.
Anything that has been polished to be smooth may be used. [0023] According to the present invention, two optical elements having different optical constants are used.
The reflective layer with a multilayer structure in which the
Using the reflective mask used as the projectionExposed substrateExposure to
Bragg diffraction of a conventional single crystal was used to perform
Like a reflectorSoft X-ray or vacuum UVFrom the horizontal
It is not necessary to make it obliquely incident, but it is made incident normally on the mask
Is possibleOf soft X-rays or vacuum ultraviolet raysUsage efficiency
high. As a result, the size of the exposure system has been drastically reduced and the exposure transfer
It is possible to achieve high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a basic cross-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 Codes] 1 Si substrate 2, 4 First material layer 3, 5 Second material layer A Soft X-ray / vacuum UV absorber B Protective film C Resist (PMMA) M ₀ Soft X-ray / vacuum Multilayer film reflective mask for UV exposure 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 (1)

(57) [Claims] Soft X-ray or vacuum is applied to a reflective mask in which a reflective layer having a multilayer film structure in which two types of layers having different optical constants are alternately laminated and a pattern of an absorber are formed on a substrate.
Means for morphism enter the UV, reflected by the reflection type mask
The input shines with exposed substrate soft X-ray or vacuum ultraviolet ray exposure substrate
And a projection optical system for forming an image of the pattern. 2. Soft X-ray or vacuum is applied to a reflective mask in which a reflective layer having a multilayer film structure in which two types of layers having different optical constants are alternately laminated and a pattern of an absorber are formed on a substrate.
A step of morphism enter the UV, reflected by the reflection type mask
The input shines with exposed substrate soft X-ray or vacuum ultraviolet ray exposure substrate
Characterized by a step of imaging the pattern
Exposure method. 3. The projection optical system is a reduced projection light provided with a reflection mirror.
The exposure apparatus according to claim 1, which is an academic system . 4. From the reflective mask to the exposed substrate, the projection optical system
Along the optical path of, the concave mirror, convex mirror, concave mirror
The exposure apparatus according to claim 3, further comprising a reflecting mirror .