JPH02197115A - Manufacture of x-ray exposure mask - Google Patents

Abstract

PURPOSE:To enhance the accuracy of formed mask pattern, and to prevent X-ray absorbed material from remaining in the pattern by a method wherein the polycrystalline or single crystal thin SIC film and BNC film or BN film, and a polycrystalline or single crystal SIC film are grown successively. CONSTITUTION:A first SIC film 2 of prescribed thickness is grown on an Si substrate 1 using a high temperature CVD method at the prescribed temperature, the surface of said substrate 1 is formed into the mirror face having no recesses and projections, and an SIC film is formed on the region 1A located on the rear of the substrate 1 when the film 2 is formed. Then, a BNC film 3 of prescribed thickness is formed on the film 2 using a plasma CVD method, and a second SIC film 4 of the prescribed thickness is formed on the film 3 using the same method used in the process 1. Moreover, a Ta film 5, which is an X-ray absorbing material film in the prescribed thickness, is formed on the film 4 using a sputtering method. Besides, the region 1A on the rear of the substrate 1 is selectively etched using an RIE method, a ceramic ring 6 is adhered, the film 2 is exposed to the rear of the substrate 1, and the high preciseness of a mask pattern is achieved.

Description

[Detailed Description of the Invention] [Summary]) A method for manufacturing an X-ray exposure mask using a combination of SiC film and BNC film or BNllil as a patterned supporting film, ie, membrane, made of an absorbing material. Regarding this, the purpose is to obtain a highly accurate pattern made of an X-ray absorbing material and to avoid the presence of any residue of the X-ray absorbing material within the pattern. A first SiC film consisting of a BNC membrane and a first SiC film consisting of
A step of sequentially growing a second SiC film made of polycrystal or single crystal to become a film and a membrane, then a step of bonding a ring serving as a membrane support frame to the back surface of the silicon substrate, and then a step of bonding a ring serving as a membrane support frame to the back surface of the silicon substrate a step of exposing the first SiC film by etching from the back side;
After that, the method includes a step of forming a mask pattern made of an X-ray absorbing material on the surface of the second SiC film, or the BNC film is replaced with a BN film.

[Industrial application field]

The present invention provides a support film for a pattern made of an X-ray absorbing material, that is, a SiC film and a BNC film or a BN film as a membrane.
The present invention relates to a method of manufacturing an X-ray exposure mask using a film in combination.

Generally, membranes in XvA exposure masks are required to have high X-ray transparency, high optical transparency, high Young's modulus, high tensile stress, high radiation resistance, smooth surface, etc.

Therefore, in order to manufacture semiconductor devices with fine patterns, there is an urgent need to realize a good X-ray exposure mask having a membrane that satisfies the above requirements.

[Conventional technology]

Conventionally, BN, BNC, SiN, 5iSiC, etc. are known as constituent materials for membranes in X-ray exposure masks, but BN or BNC has good XI, % transmittance, and optical transmittance. It is known that SiC also has a high Young's modulus (e.g. 3~4X IQ" (d y n7c
m”) or higher), high radiation resistance (e.g. 100 (M
It is excellent in that it has physical properties such as J /amff) or more.

Incidentally, the SiC film is normally heated at a temperature of 700 ('C) to 1
Chemical vapor deposition carried out under high temperature of 380 ('c)
chemical vapor d.

Polycrystalline or single-crystalline materials grown using CVD (Posftion: CVD) method are best;
CVD method and ECR (e I e c t r ).

nic cyclotron resonance
) Although amorphous materials grown by the CVD method have a mirror-like surface, they have problems such as low radiation resistance.

[Problem to be solved by the invention]

When an X-ray exposure mask is manufactured using the membrane made of BN or BNC described above, H2O and 02
There are unstable elements such as reacting with other substances and changing into boric acid.

Furthermore, when an X-ray exposure mask is manufactured using a membrane made of StC, there is a drawback that unevenness is generated on the surface. That is, a SiC film is usually formed by depositing, for example, polycrystalline Si on a single-crystal Si substrate by applying a high-temperature CVD method.
The C film must be grown as thick as, for example, 2 [μm] to 3 [μm]. However, due to the misfit and thermal expansion difference between St and SiC, it is not possible to form a SiC film that is completely defect-free and has a mirror surface to the thickness described above, and is approximately 0°l [μm]. From 0. 2 [μm]
This results in some degree of unevenness. In general, S
A film of an X-ray absorbing material such as Ta, W, or Au is formed on the iC film, and is patterned to form a mask pattern. Generally, a pattern in a semiconductor device formed using an X-ray exposure mask has a line width of about 0.1
The goal is to have a diameter of about 0.2 [μm] to 0.2 [μm]. Therefore, when trying to obtain a mask pattern to form a mask pattern, if there are irregularities of the same size on the membrane that forms the mask pattern, the mask pattern cannot be formed with high precision. There's no way it could be done, and the edges would be jagged. Furthermore, in addition to such problems, experiments have revealed that a major problem of unknown cause has occurred. That is, on the SiC film where the unevenness exists, for example, Ta
When an X-ray absorbing material film is formed and patterned, Ta remains on the top surface of the uneven surface. Usually, a film is formed on an uneven base,
When the film is removed, it is possible that some of the film remains on the concave parts, but in the case of membranes made of SiC, the opposite is true, with more residue on the convex parts than on the concave parts. exist. Therefore, when buttering an X-ray absorbing material film made of Ta, it is visible that it remains in spots in areas where it should not exist, and this causes
%i cannot be used as a photomask.

The present invention provides a highly accurate pattern of X-ray absorbing material and eliminates the presence of residues of X-ray absorbing material within the pattern.

[Means to solve the problem]

The present invention has found that when a very thin SiC film is grown, the SiC film can maintain a mirror surface.

It is the basis.

For this reason, in the method for manufacturing an X-ray exposure mask according to the present invention, a first SiC film made of polycrystal or single crystal to form a membrane on the surface of an Al silicon substrate and a B N film to form a membrane are provided. A step of sequentially growing CI! and a second SiC film made of polycrystal or single crystal to become a membrane, then a step of bonding a ring serving as a membrane support frame to the back surface of the silicon substrate, and then or (b) the step of exposing the first SiC film by etching from the back surface of the 5iCIQ film, and then forming a mask pattern made of an X-ray absorbing material on the surface of the second 5iCIQ. One of the methods is to replace the BNC film with a BN film.

[Effect]

By adopting the above method, a membrane having a structure in which a BNC film or a BN film is sandwiched between thin polycrystalline or single crystal SiC films can be obtained. Therefore, the base on which the mask pattern made of the XvA absorbing material is to be formed has a mirror surface. Therefore, the accuracy of the formed mask pattern is very high, and there is no residue of X-ray absorbing material in the pattern. In addition, since the membrane is mainly composed of a BNC film or a BN film, its X-ray transparency and optical transparency are extremely good, and since these films are covered with a SiC film, It has sufficiently high resistance to radiation, and is also stable against 02 and B20 in the atmosphere.

(Example) Part 1 Figures 1 to 8 are cross-sectional side views of essential parts of an X-ray exposure mask at key points in the process for explaining one embodiment of the present invention.
The explanation will be given below with reference to these figures.

Refer to Figure 1. (1) By applying a high temperature CVD method at a temperature of 700 ('C) to 1000 (''C), a thickness of about 1000 to 2000 [people], for example, is deposited on the St substrate 1. Grow the first 5iC92.

In this case, supply gas: S i HCl 3 or 5iH2C1z
10C3H or C2H2 diluent gas: B2, and the growth apparatus may be either a cold wall type (induction heating) or a hot wall type (lamp heating).

The average grain size of the first SiC film 2 thus obtained is 0.05 (μm) or less, and therefore,
The surface is rough, that is, it has a mirror surface with almost no unevenness. Incidentally, the coating designated by the symbol IA is the first S
This is the SiC film formed on the back surface of the Si substrate 1 when the iC film 2 was formed.

(2) By applying the plasma CVD method, B is deposited on the first SiC film 2 to a thickness of, for example, about 2 [μm].
NCNSO2 is formed.

In this case, supply gas: B2H6 + NH3 + CH4 Temperature: 450 [''C] (3) In the same manner as in step (1) above, a second SiC film 4 having a thickness of about 1000C to 2000C is formed on BNCNSO2. The surface of the second SiC film 4 formed here is rough, that is, the unevenness is 0.02C.
It has a mirror surface of less than [μm].

Refer to Figure 2 (4) By applying the sputtering method, a layer with a thickness of, for example, 1 [μm] is formed on the second SiC film 4 having a mirror surface.
A Ta film 5, which is an X-ray absorbing material film, is formed. still,
This Ta film 5 can be replaced with a W film or an Au film.

(5) 5iCJI! was formed on the back surface of the Si substrate 1 by applying the resist process in normal photolithography technology and the RIE method using CF and +02 etching gases. Perform selective etching of JIA.

Refer to FIG. 3 (a ring 6 made of ceramic or heat-resistant high silicate glass (for example, Pyrex: trade name) is adhered to the back surface of the 61Si substrate 1 using, for example, a photocurable adhesive.

Refer to FIG. 4 (etching is performed from the back surface of the 71 Si substrate 1 to the back surface of the first SiC film 2.

For etching in this case, HF/HN O3/
A wet etching method using CH3COOH as an etchant may be applied.

By going through this step, only the peripheral portion of the Si substrate 1 remains in a ring shape, and the rest is removed. In the figure, this is represented by symbol 1
It is indicated by '.

Refer to FIG. 5 (8) For example, by applying a spin coating method, an ordinary electron beam resist such as polymethyl methacrylate (po 17methy1methacrylate) is coated on the Ta film 5.
Resist film 7 made of hacrylate (PMMA)
form.

See FIG. 6 (9) The electron beam resist II*7 is patterned by applying electron beam lithography technology.

Refer to Figure 7 0ω Etching gas, for example C7!2 / CCl
4, the Ta film 5 is patterned using the electron beam resist film 7 as a mask to form a mask pattern 5'.

See Figure 8 01) Complete by removing the electron beam resist film 7.

In this way, a pattern with a line width of about 0.2 [μm] can have sufficiently high precision, and no Ta residue is present. It goes without saying that Ta can be replaced by W or Au.

Part 2 A BN film is used instead of the BNC film in the above embodiment.

Even in this case, exactly the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

In the method for manufacturing an XG exposure mask according to the present invention, a thin polycrystalline or single-crystalline SiC film, a BNC film or BN film, and a thin polycrystalline or single-crystalline SiC film are sequentially grown on the surface of a silicon substrate. ing.

By adopting the above structure, a membrane having a structure in which an ENC film or BN film is sandwiched between thin polycrystalline or single crystal SiC films can be obtained, and therefore a mask made of an X-ray absorbing material can be used.
The base on which the pattern is to be formed is flat like a mirror.
Therefore, the accuracy of the formed mask pattern is very high, and there is no residue of X-ray absorbing material in the pattern. In addition, since the membrane is mainly composed of a BNC film or a BN film, its X-ray transparency and optical transparency are extremely good, and since these films are covered with a SiC film, It has sufficiently high resistance to radiation, and is also stable against 02 and H20 in the atmosphere.

[Brief explanation of the drawing]

1 to 8 are cross-sectional side views of essential parts of an X-ray exposure mask at key points in the process for explaining one embodiment of the present invention. In the figure, 1 is a Si substrate, IA is a SiC film, 2 is a first SiC film, 3 is a BNC film, 4 is a second SiC film, 5 is a Ta film, 6 is a ring, and 7 is a photoresist. The membranes and 5' indicate mask patterns, respectively. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Akio Aitani Representative Patent Attorney Hiroshi Watanabe - Cut-away side view of essential parts of X-ray exposure mask Figure 1 Cut-away side view of essential parts of X-ray exposure mask Essentials of X-ray exposure mask Partial cutaway side view Figure 5. Main part cutaway side view of X-ray exposure mask Figure 6. Main part cutaway side view of X-ray exposure mask Figure 3. Main part cutaway side view of X-ray exposure mask Figure 7. Figure 8: Cutaway side view of essential parts of

Claims (2)

[Claims] (1) Steps of sequentially growing a first SiC film made of polycrystal or single crystal to become a membrane, a BNC film to become a membrane, and a second SiC film made of polycrystal or single crystal to become a membrane on the surface of a silicon substrate; Next, a step of bonding a ring serving as a membrane support frame to the back surface of the silicon substrate, a step of etching from the back surface of the silicon substrate to expose the first SiC film, and a step of exposing the first SiC film. A method for manufacturing an X-ray exposure mask, comprising the step of forming a mask pattern made of an X-ray absorbing material on the surface of the film. (2) The method for manufacturing an X-ray exposure mask according to claim 1, wherein the BNC film is a BN film.