JPS608842A - Formation of pattern - Google Patents

Abstract

PURPOSE:To form a superior resist micropattern good in adhesive strength to a substrate without deteriorating sensitivity and resolution by using 2-layer resist films each made of a specified polymer. CONSTITUTION:A <=0.1mum thin film made of one kind of polymer selected from a group B is formed on a substrate, and on this film another 0.1-0.2mum thin film made of one kind of polymer selected from a group A is formed to obtain 2- layer thin films. As the polymer of the group A, a homopolymer of a monomer represented by formula I (R1 is methyl or Cl, and R2 is halogenated alkyl) or a copolymer of it and another vinyl monomer, preferably, a polymer represented by formula II in which R3 is -CH2CF3, -CH(CH3)CF3, -C(CH3)2CF3, CH2CF2CHF2, or -CH(OCH3)CF3. The polymers of the group B are superior in solubility in org. solvents and adhesive strength to a substrate to said polymers of the group A, and they are decomposable with radiation, and a preferable monomer of them is represented by formula III in which R4 is 3-7 C alkyl. Such 2-layer resist films can be formed into a superior micropattern good in adhesive strength to the substrate with a small amt. of radiation, and can be used for microfabrication of a semiconductor substrate, a mask substrate, etc.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention provides a method for forming a fine pattern by irradiating a polymer thin film on a substrate with radiation such as rays, X-rays, and ion particle beams. In particular, the present invention relates to a method for forming patterns using improved two-layer polymer thin films.

[Traditional techniques and the differences between them]

In recent years, with the increasing density of semiconductors in Yonago, the Y-knob 2-fee technology using radiation has been introduced. By the way, in the method of forming a resist pattern using radiation ginegraphy, a radiation-sensitive resist (74) is coated on a substrate, this resist film is irradiated with radiation in a desired pattern, and then a pattern is formed on the resist film by performing a development process. Then, using this resist pattern as a mask, wet or dry etching is performed to etch and form a desired pattern on the substrate.

Until now, halogen-containing positive resists such as polytrifluoroethyl α-chloroacrylate have been used as highly sensitive positive radiation resists. The adhesion to the core substrate is poor, and when a pattern is formed on such a semiconductor substrate, there is a drawback that pattern deformation is likely to occur due to poor adhesion to the substrate.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances.
A method of forming a microscopic resist pattern with excellent adhesion to a substrate without reducing sensitivity or resolution by using a 21i resist film of a resist with good resistance and the above-mentioned halogen-containing positive resist. This is what we are trying to provide.

[Summary of the invention]

That is, the present invention involves forming a thin Lusa made of one type of polymer selected from group CB) on a substrate with a film thickness of 01 μm or less, and then forming a thin Lusa made of one type of halogen-containing polymer selected from group A) on the substrate. A two-state resist film is formed with a thickness of 0.1 to 2.0 μm, and after pre-baking at an appropriate temperature, this two-state resist film is irradiated with radiation in a desired pattern. The irradiated portions are then selectively removed by development treatment to form a fine resist pattern with excellent adhesion to the substrate.

However, group A) (wherein R1 represents a methyl group or a chlorine atom, and R3 represents a halogenated alkyl group) [1] Consists of a homopolymer of the monomer represented by the formula or a copolymer of it and other vinyl monomers Polymer group [13] A radiolytic polymer group that has lower solubility in organic solvents and better adhesiveness to a substrate than the polymers selected from group A). 1 layer: mm resists include polypropyl methacrylate, polyisopropyl methacrylate, poly-n-butyl methacrylate, poly-isobutyl methacrylate, poly sec-butyl methacrylate, poly-1-butyl methacrylate, polypentyl methacrylate, polycyclohexyl methacrylate. , polyhexyl methacrylate, and the like. The resists used for the second layer include polytrifluoroethyl α-chloroacrylate, polytrifluoroinpropyl α-chloroacrylate, polytrifluorot-chloroacrylate, and polytrifluoroinpropyl α-chloroacrylate.
Butyl α-chloroacrylate.

Poly 1-methoxide difluoroethyl α-chloroacrylate, polytrifluoroethyl meccrylate, botatrichloroethyl methacrylate.

Examples include polyhexafluorobutyl methacrylate.

The molecular weight of the resist used for the first layer of the present invention is sufficient to have a molecular weight of several million or less so that coating properties are not inhibited,
Further, it is preferable that the resist film has a good film thickness of 0.1 μm or less, preferably about 100 to 500 μm.

Substrates used in the present invention include, for example, a single silicon substrate doped with impurities, a semiconductor substrate such as one in which a polycrystalline silicon film is provided as a matrix via a silicon oxide layer, and a compound semiconductor such as gallium arsenide. substrate,
Alternatively, a mask substrate such as a chromium film or a chromium oxide film laminated on a transparent glass plate can be provided.

〔Effect of the invention〕

However, the two-layer resist film used in the present invention is...

The lower layer is a thin polymer film with good adhesion to the substrate, and the upper layer is a highly sensitive positive stone! Since it is an electronic powder resist, the present invention makes it possible to easily obtain a fine resist pattern with good adhesion to the substrate with a small irradiation dose. The lower layer resist film is of the radial decomposition type and the upper layer resist film is 7N.
Since it is made of a polymer with higher solubility than FJ, it is possible to form a two-layer resist pattern that can be etched in one step of inspection and image processing. In addition, there is no need to form a thick resist film as the lower layer resist film, and the film thickness is 0.
．． A thin resist film of 1 μm or less, in the range of 100 to 500 people, is sufficient.

[Embodiments of the invention]

Example 1 Poly n-butyl methacrylate (molecular weight: 100,000) was formed by spin coating on a silicon substrate on which a silicon oxide film had been formed, to a thickness of 200 nm, and heated at 150°C.
After 20 minutes of veribake treatment, polytrifluoroethyl α-curulacrylate (molecular weight 600,000) was similarly spin-coated to form a film with a thickness of 1μ.
After pre-baking at 00°C for 1 hour, poly H-butyl methacrylate was applied as the lower layer, polytrifluoroethyl α
- A two-layer resist film with a chloroacrylate upper layer was formed. Further, as a comparative example, a single layer resist film of polytrifluoroethyl α-chloroacrylate (thickness: 1 μm) was formed on a silicon oxide substrate by the same method.

Next, the above-mentioned two-pronged regime) beam diameter of 0.1μ for ITR,
An electron beam with an accelerating voltage of 20I (V) is
μ space, 8μC/, d in a pattern of length 100μ
MIBK (methyl isobutyl ketone)-II? A (inpropyl alcohol) (65:
A pattern was formed using a developer consisting of a mixed solution (35 volume ratio). Observing the formed pattern 2
The layered resist pattern has no pattern flow and is 0.5μ.
A fine pattern was formed, but pattern flow was observed in some parts of the -m resist.

After that, dry etching was performed using a mixed gas of CF, -H, (70':30 partial pressure ratio) using the above two-layer resist pattern as a mask, and when the resist was removed with oxygen plasma, the resist pattern was clearly visible on the silicon oxide substrate. It was confirmed that it was transcribed.

Example 2 Poly n-butyl methacrylate (molecular weight 100,000) was spin-coated onto a silicon substrate at 200 A
After forming a resist film with a thickness of , prebaking at 150°C for 20 minutes,
- Chloracrylate (molecular weight 1,000,000) was also spin-coated; a film thickness of 1 μm was formed (2), prebaked at 180°C for 1 hour, and the poly-
A two-layer resist film was formed with n-butyl methacrylate as the lower layer and polytrifluoroisopropyl α-chloroacrylate as the upper layer. As a comparative example, polytrifluoroisopropyl α-
A resist film of one layer of chloroacrylate (thickness: 1 μm) was formed.

Next, the above two types of regimes) Beam diameter 0.1 at IF'<
μ.

0.5 μ line 1.
10μC/in a pattern of 0μ space and 100μ length.
MIBK-IPA (50:
A pattern was formed using a developer consisting of a mixed solution (volume ratio: 50% by volume). When the formed pattern was observed, it was found that the two-layer resist pattern had no pattern bleeding and a fine pattern of 0.5 μm was formed, but pattern bleeding was observed in a considerable portion of the one-layer resist pattern. Then CF
Dry etching was performed using a 40t (96:4 partial pressure ratio) mixed gas using the above two-layer resist pattern as a mask, and the resist was removed with oxygen plasma, and it was found that the resist pattern was clearly transferred onto the silicon substrate. confirmed.

As detailed above, by using a two-stroke resist film made of a specific radiation-degradable polymer, it is possible to form a fine resist film with good adhesion to the substrate with a small amount of radiation irradiation. It is possible to provide a highly practical resist pattern forming method that can be effectively used for microfabrication of mask substrates and the like.

Agent: Patent attorney Noriyuki Chika (and 1 other person) 1ri0

Claims (1)

[Scope of Claims] (1) In a method of forming a fine pattern using radiation such as electron beams, X-rays, and ion particle beams, a thin film made of one type of polymer selected from group [B] is coated with 0. r less than 1μ
A thin film made of one type of polymer selected from group A is formed on a substrate with a thickness of 0.1 to 2.0 μm, and is used in a stable manner. Characteristic pattern forming method CA) group (where 几l represents a methyl group or a chlorine atom, R2 represents a halogenated alkyl group) [1] A homopolymer of the monomer represented by the formula, or a combination of this and other vinyl monomers A radiolytic polymer group (2) which has higher solubility in organic solvents and better adhesion to a substrate than a polymer selected from group (13) group CA) consisting of a copolymer of ) Group (A) is a polymer group l represented by the general formula [2] (where l(,3 is -CH, CFs, -CH(CM,)
OF,,-C(CHs)zCOOR. (However, R represents an alkyl group having 3 to 7 carbon atoms.) Patent claim 1 characterized in that it is a polymer group.
Pattern formation method described in section