JP4792666B2 - Stencil mask, manufacturing method thereof and exposure method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stencil mask used for exposure of charged particle beams such as an electron beam and an ion beam, a manufacturing method thereof, and an exposure method.
[0002]
[Prior art]
In recent years, miniaturization of semiconductor elements has been progressing rapidly. Various exposure techniques have been developed as a technique for manufacturing an element having such a fine pattern. For example, there are exposure methods using electron beams such as partial exposure of electron beams and electron stepper exposure, exposure methods using ions, exposure methods using light in the vacuum ultraviolet region, exposure methods using light in the extreme ultraviolet region, etc. .
[0003]
Among these, as an exposure method using an electron beam, a method of performing equal magnification exposure using an electron beam is proposed in Japanese Patent No. 2951947. This method has a feature that the acceleration voltage of an electron beam is 1/20 as compared with a conventional exposure method using an electron beam.
[0004]
In the stencil mask used for the same magnification exposure, the processing accuracy of the mask pattern is important. In particular, the aspect ratio, which is the ratio between the mask film thickness and the mask pattern line width (electron beam transmission hole diameter), is a problem. The mask pattern is processed by dry etching, but the aspect ratio is usually about 10. Therefore, for example, in order to form a pattern with a line width of 100 nm, the thickness of the mask is limited to about 1 μm.
[0005]
Therefore, the above-mentioned Japanese Patent No. 2951947 discloses that a stencil mask made of single crystal silicon has a thickness of 0.2 μm to 1.0 μm. However, this patent publication does not describe any method for manufacturing such a stencil mask made of single crystal silicon.
[0006]
Usually, when single crystal silicon is used as the material of the thin film constituting the stencil mask, a substrate is required to support the thin film and maintain the flatness of the mask. As this substrate, single crystal silicon is used from the viewpoint of processability and availability. Then, in order to perform microfabrication of the thin film by etching, an SOI (Silicon On Insulator) substrate having a structure in which a silicon oxide film is sandwiched between two single crystal silicon substrates is used, and the mask pattern is obtained by polishing one single crystal silicon substrate. Thus, the film thickness is made to a predetermined thickness and then patterned. At this time, the silicon oxide film that is an intermediate layer of the SOI substrate functions as an etching stopper when the mask pattern is processed.
[0007]
However, with such a method, it is extremely difficult to polish the single crystal silicon substrate to the above-mentioned thin film of 0.2 μm to 1.0 μm. Further, with such a film thickness, there is a problem that a thin single crystal silicon substrate is cracked by the stress of the silicon oxide film in the manufacturing process of the stencil mask.
[0008]
For this reason, a stress adjustment process is required for the single crystal silicon thin film formed on the silicon oxide film. In such a case, however, the manufacturing process is increased, resulting in a problem that the tact time is increased.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide a stencil mask which is made under such circumstances, can be easily formed into a thin film, can perform stress control, and has excellent electron beam irradiation characteristics.
[0010]
It is another object of the present invention to provide a method for manufacturing such a stencil mask.
[0011]
Still another object of the present invention is to provide a charged particle beam exposure method using such a stencil mask.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention comprises a base having an opening, and a mask base whose peripheral part is supported by the base and a part other than the peripheral part is exposed from the opening. , the charged particle beam Ri is Do a single layer of silicon oxide thin film having a transmission hole pattern of transmission, the silicon oxide thin film, 0.1 [mu] m or more, has a thickness of less than 5 [mu] m, silicon and atoms of oxygen of the silicon oxide A stencil mask characterized in that the ratio is 2: 1 or more and 1: 2 or less is provided.
[0013]
According to such a stencil mask of the present invention, since the mask base is composed of a silicon oxide thin film, the silicon oxide thin film is controlled by controlling the atomic ratio of silicon to oxygen to 2: 1 or more and 1: 2 or less. It is possible to design and control the stress applied to the film, and to reduce the resistance.
[0014]
In addition, a silicon oxide thin film can be easily formed by a reactive vapor deposition method, CVD, etc., has excellent workability, and can form a pattern with a desired aspect ratio with high accuracy. Control is easy and it is possible to obtain a stencil mask with excellent charged particle beam irradiation characteristics.
[0015]
In the stencil mask of the present invention, the silicon oxide thin film has a thickness of 0.1 μm or more and 5 μm or less . Film thicknesses in this range were difficult to form with single crystal silicon, but can be easily obtained with good controllability by reactive vapor deposition or CVD.
[0016]
The silicon oxide thin film has an atomic ratio of silicon to oxygen of 2: 1 or more and 1: 2 or less . Such a silicon oxide thin film is a film having an atomic ratio range in which stress control is possible, and has conductivity, so that charge-up can be prevented.
[0017]
The present invention also provides a silicon oxide thin film having a thickness of 0.1 μm or more and 5 μm or less and a silicon / oxygen atomic ratio of 2: 1 or more and 1: 2 or less on a substrate by reactive vapor deposition. Forming a single layer, patterning the silicon oxide thin film, and selectively etching the opposite side of the substrate from the silicon oxide thin film to form an opening and exposing the silicon oxide thin film The manufacturing method of the stencil mask which comprises the process to perform is provided.
[0018]
Furthermore, the present invention has a thickness of 0.1 μm or more and 5 μm or less on a substrate by a plasma CVD method using an organic source gas , and an atomic ratio of silicon to oxygen is 2: 1 or more and 1: 2 or less. step of forming a single-layer silicon oxide film is, step for patterning the silicon oxide film, and the substrate, the silicon oxide film by selectively etching the opposite side, to form an opening, wherein A method for manufacturing a stencil mask comprising a step of exposing a silicon oxide thin film is provided.
[0020]
According to these manufacturing methods, it is possible to easily obtain a stencil mask excellent in charged particle beam irradiation characteristics with high workability and high accuracy without causing cracks and peeling due to stress.
[0021]
Furthermore, the present invention provides a charged particle beam exposure method comprising a step of irradiating the above stencil mask with a charged particle beam and shaping the charged particle beam into the shape of a transfer pattern.
According to such an exposure method, it is possible to perform pattern exposure with high accuracy on the resist formed on the sample substrate. As a result, it is possible to manufacture a pattern of a semiconductor or the like with a high yield.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a stencil mask according to one embodiment of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a cross-sectional view illustrating a stencil mask according to one embodiment of the present invention. In FIG. 1, a stencil mask 1 forms a mask base 3 having a predetermined transmission hole pattern and made of a silicon compound thin film containing oxygen and / or nitrogen on a single crystal silicon wafer 2 in which openings are formed. It is constituted by.
[0024]
For the supporting substrate, a semiconductor material such as gallium-arsenic or indium-phosphorus can be used in addition to single crystal silicon.
[0025]
Examples of the silicon compound thin film constituting the mask base 3 include a silicon oxide film, a silicon nitride film, and a silicon oxynitride film.
[0026]
The film thickness of the silicon compound thin film is desirably 0.1 μm or more and 5 μm or less. If the film thickness is too thin, the silicon compound thin film may be dissolved if the current value is increased in order to increase the throughput. If it is too thick, the mask pattern processing accuracy cannot be increased.
[0027]
In the stencil mask according to the present embodiment configured as described above, since a silicon compound thin film containing oxygen and / or nitrogen is used as the mask base instead of the conventionally used single crystal silicon thin film, an electron beam is used. Since a thin film having a thin film thickness can be formed with excellent irradiation resistance and electron beam irradiation such as conductivity, a pattern with a desired aspect ratio can be formed with high accuracy.
[0028]
Next, the manufacturing process of the stencil mask described above will be described with reference to FIGS.
[0029]
First, as shown in FIG. 2, a silicon compound thin film 12 containing oxygen and / or nitrogen is formed on a single crystal silicon substrate 11 by reactive vapor deposition or plasma CVD.
[0030]
Next, as shown in FIG. 3, the silicon compound thin film 12 is patterned to form a mask base 13 having a predetermined transmission hole pattern. This through hole pattern formation process is performed through a resist pattern forming step on the silicon compound thin film 12, a step of dry etching the silicon compound thin film 12 using the resist pattern as a mask, and a resist pattern peeling step. Is called.
[0031]
As the exposure for forming the resist pattern, electron beam direct drawing using an electron beam resist, stepper exposure using a photoresist, or the like can be suitably used.
[0032]
Further, when the silicon compound thin film 12 is dry-etched, if the resist has insufficient etching resistance, a metal such as chromium, tungsten, tantalum, titanium, nickel, or aluminum, an alloy containing these metals, or these metals Alternatively, a metal compound of an alloy and oxygen, nitrogen, carbon, or the like can be used as an etching mask. These etching masks can be formed by various thin film forming methods. For example, there are forming methods such as sputtering, CVD, and vapor deposition.
[0033]
For dry etching, the dry etching method and etching conditions are not particularly limited. Examples of the gas used for etching include a mixed gas mainly containing a fluorine-based gas such as SF ₆ gas and CF ₄ gas, a mixed gas mainly containing a chlorine-based gas such as Cl ₂ gas and SiCl ₄ gas, and a bromine such as HBr gas. Examples thereof include a mixed gas mainly composed of a system gas. Examples of the dry etching apparatus include a dry etching apparatus using a discharge method such as RIE, magnetron RIE, ECR, ICP, microwave, helicon wave, and NLD.
[0034]
Then, as shown in FIG. 4, the opening part 14 is formed in the single crystal silicon substrate 11, and a stencil mask is completed.
[0035]
In this step, dry etching, wet etching, ultrasonic processing, sandblasting, or the like can be suitably used. Note that either the patterning step of the silicon compound thin film 12 or the step of forming the opening in the single crystal silicon substrate 11 may be performed first.
[0036]
【Example】
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
[0037]
Example 1
With reference to FIGS. 2-4, the manufacturing process of the stencil mask which concerns on one Example of this invention is demonstrated.
A silicon oxide film 12 was formed on a single crystal silicon substrate 11 having a thickness of 525 μm by reactive vapor deposition using a vacuum vapor deposition apparatus.
[0038]
The conditions for reactive vapor deposition are as follows.
Raw material: SiO
Reaction gas: O ₂ (+ 5% ozone)
Reaction pressure: 10 ⁻⁸ to 10 ⁻⁴ Torr
Deposition rate: 1-2 angstrom / second Film thickness: 500 nm.
[0039]
On the silicon oxide film 12 formed as described above, an electron beam resist (not shown) is applied to a thickness of 0.5 μm, and this is drawn using an electron beam drawing machine with an acceleration voltage of 20 kV. Development was performed using an alkaline developer, to form a resist pattern (not shown).
[0040]
Next, the silicon oxide film 12 was dry etched using a resist pattern as a mask, using a plasma etching apparatus and using SF ₆ as an etchant, to form a pattern 13 as shown in FIG.
[0041]
Next, the resist pattern is peeled off, a protective film (not shown) made of a silicon nitride film is formed on the entire surface using a plasma CVD (Chemical Vapor Deposition) apparatus, and then the opening of the single crystal silicon substrate 11 is formed by dry etching. The protective film on the part formation region was removed.
[0042]
Next, it was accommodated in an etching solution of KOH aqueous solution heated to about 90 ° C., and the single crystal silicon substrate 11 was subjected to anisotropic etching along the plane direction using the protective film as a mask to form an opening. Next, the protective film was removed by etching with hot phosphoric acid at about 170 ° C. to complete a stencil mask as shown in FIG.
[0043]
In the stencil mask manufactured as described above, the silicon oxide film 12 has a very thin film thickness of 500 nm and has a low stress. Therefore, no peeling or cracking occurs, and the resistance is low. There is no need to provide it. Moreover, since the silicon oxide film 12 has good processability, the obtained stencil mask had high pattern accuracy and excellent charged particle beam irradiation characteristics.
[0044]
Example 2
A stencil mask was manufactured in the same manner as in Example 1 except that the silicon oxide film 12 was formed by plasma CVD under the following conditions using a parallel plate type plasma CVD apparatus.
[0045]
Source gas: TEOS + O2 (0-20%
Reaction pressure: 5 Pa
High frequency power: 100W
Film thickness: 500 nm.
[0046]
Also in this example, the same effect as in Example 1 was obtained.
[0047]
Example 3
A stencil mask was manufactured in the same manner as in Example 1 except that a silicon nitride film was formed by LPCVD using the LPCVD apparatus under the following conditions.
[0048]
Source gas: SiH ₂ CI ₂ + NH ₃ (10-50%)
Reaction pressure: 30-60 Pa
Film thickness: 500nm
Also in this example, the same effect as in Example 1 was obtained.
[0049]
【The invention's effect】
As described above in detail, according to the present invention, since the mask base is composed of a silicon compound thin film, it can be easily formed by reactive vapor deposition, CVD, etc. It is easy, has excellent workability, and can form a pattern with a desired aspect ratio with high accuracy. As a result, a stencil mask with excellent charged particle beam irradiation characteristics can be obtained.
[0050]
Moreover, according to the manufacturing method of the present invention, it is possible to easily obtain a stencil mask having excellent charged particle beam irradiation characteristics with high accuracy without causing cracks and peeling due to stress.
[0051]
Furthermore, according to the exposure method of the present invention, it is possible to perform pattern exposure with high accuracy on the resist formed on the sample substrate. As a result, it is possible to manufacture a pattern of a semiconductor or the like with a high yield.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a stencil mask according to one embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a manufacturing process of a stencil mask according to one embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a manufacturing process of a stencil mask according to one embodiment of the present invention.
FIG. 4 is a cross-sectional view illustrating a manufacturing process of a stencil mask according to one embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stencil mask 2, 11 ... Single crystal silicon substrate 3, 13 ... Mask mother body 12 ... Silicon compound thin film 14 ... Opening

Claims (4)

A base having an opening, and a mask base that is supported by the base and has a peripheral portion that is exposed from the opening, and the mask base has a transmission hole pattern through which a charged particle beam passes. Ri Do of a single layer of silicon oxide thin film having the silicon oxide thin film, 0.1 [mu] m or more, has a thickness of less than 5 [mu] m, the atomic ratio of silicon and oxygen of the silicon oxide 2: 1 or more, 1: 2 or less stencil mask, characterized in that it. A single layer of a silicon oxide thin film having a thickness of 0.1 μm or more and 5 μm or less and an atomic ratio of silicon to oxygen of 2: 1 or more and 1: 2 or less is formed on the substrate by reactive vapor deposition. The process of
Manufacturing a stencil mask comprising: patterning the silicon oxide thin film; and selectively etching the opposite side of the substrate from the silicon oxide thin film to form an opening and exposing the silicon oxide thin film Method. A silicon oxide thin film having a thickness of 0.1 μm or more and 5 μm or less and an atomic ratio of silicon to oxygen of 2: 1 or more and 1: 2 or less by a plasma CVD method using an organic source gas on a substrate. Forming a single layer;
Manufacturing a stencil mask comprising: patterning the silicon oxide thin film; and selectively etching the opposite side of the substrate from the silicon oxide thin film to form an opening and exposing the silicon oxide thin film Method. A charged particle exposure method comprising a step of irradiating the stencil mask according to any one of claims 1 to 3 with a charged particle beam and shaping the charged particle beam into a shape of a transfer pattern.

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