JPH02264260A - Three-layered resist - Google Patents

Abstract

PURPOSE:To allow fine working with a high resolution by disposing a dry etching-resistant inorg. material and dry etching-resistant org. high-polymer material between an LB (Langmuir-Blodgette) film and a substrate. CONSTITUTION:The dry etching-resistant inorg. material and the org. high- polymer material to serve as a mask at the time of flattening the steps of the substrate and dry etching the substrate are disposed between the LB film and the substrate. Silicon oxide, silicon nitride, etc., are used as the dry etching- resistant inorg. material and acrylic resins, such as polymethyl methacrylate and polyacrylate, and styrene resins, such as polystyrene and polymethyl styrene, are used as the dry etching-resistant org. high-polymer material to be used for a lower layer. The fine working with the high resolution is enabled in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-layer resist used for microfabrication, and more specifically, the present invention relates to a three-layer resist used for microfabrication, and more specifically, it relates to a three-layer resist used for microfabrication. , relates to a three-layer resist characterized by disposing a dry-etchable inorganic material and a dry-etch-resistant organic polymer material.

As the integration of Saramai Lijutsu semiconductors progressed, 4M chips advanced to the mass production stage.
Research has begun on a 64M prototype of the 16M chip. For such integration, 0.7 μm and 0.5 μm are required, respectively.
Processing with a minimum line width of 0.3 μm is required.

In view of these problems, we have developed a single-layer LB film for resists with high resolution and dry etching resistance by patent application No. 63-226,934 and No. 62-215,930.
proposed.

However, as the semiconductor processing process progresses, large irregularities occur on the substrate.
- When a film was formed, there was a problem in that the LB film was very thin and the degree of occurrence of defects was high.

Another problem is that it is difficult to obtain a pattern with good resolution due to reflected and scattered light from the substrate surface.

A three-layer resist consisting of three layers of an image-forming resist, silicon oxide, and a dry etching-resistant organic material has already been proposed, but in order to achieve a resolution of about 0.3 μm, it is necessary to shorten the wavelength of the light source used and to image the image. It is important to reduce the thickness of the forming resist film.

However, in the case of the commonly used phenol-novolak positive resist, it is difficult to obtain a good pattern due to its strong absorption in the far ultraviolet region, and spin coating is difficult to coat thinly and uniformly without defects. The problem was that it was difficult.

. In a resist using an LB film, the present invention uses a dry etching-resistant inorganic material between the LB film and the substrate, and a mask for flattening the steps on the substrate and dry etching the substrate. It has become clear that high-resolution microfabrication can be achieved by arranging organic polymer materials.

The LB film used in the present invention may be a conventional LB film that can be patterned using ultraviolet light, electron beams, , chemical resistance has been improved, and ultraviolet rays
It was designed so that patterns could be formed using electron beams, X-rays, etc., and was patented in Japanese patent applications No. 63-226,934 and No. 62-215.
, 930 is preferably used.

Next, the LB method, which is a method for manufacturing the LB film used in the present invention, will be explained.

The LB method is a method in which a film-forming substance is spread on the water surface, the material spread on the water surface is compressed with a constant surface pressure to form a monomolecular film, and the film is transferred onto a substrate. In addition to the vertical immersion method, methods such as the horizontal attachment method and rotating cylinder method (New Experimental Chemistry Course, Volume 18, Interfaces and Colloids, 49B-508
), and any commonly used method can be used without particular limitation.

The LB method is an excellent method for forming thin films of 1000 Å or less and hundreds of holes or tens of holes in an oriented manner and the thickness can be controlled in units of tens of holes, and the LB film used in the present invention also has this feature. have. However, films with a thickness of 10, 00, or more can also be formed by this method.

Patent application No. 63-226.934, Patent application No. 62-215.9
Although the polymer compounds proposed in No. 30 can be used alone to form films by the LB method, the film forming performance is improved by mixing these polymer compounds with known LB film compounds, and such mixed films are also preferred in the present invention. This is an embodiment. In particular, when a small number of hydrocarbon-containing groups having 10 to 30 carbon atoms, which may include substituents, are introduced per repeating unit, it is preferable to form a film by mixing with a known LB film compound.

The known LB film compound is a compound that is also described in the literature cited above and is known in the art.

In particular, compounds of the following formula consisting of a hydrocarbon group having about 16 to 22 carbon atoms and a hydrophilic group are preferred.

CHz (CHz) - - + Z CHz = CH (C1b) - -z ZCH: + (CH
z) IC3CC3C (CHz) m Z where n=1
6-22. j+m=n 5. Z=OH, Nl2
, C0OH, CONH2, C0OR'(R' is a lower aliphatic hydrocarbon group).

To improve film formability, CI+3 (CH2) , -
Those expressed by the IZO formula are superior in terms of performance and cost, but those containing unsaturated bonds have the characteristic that they can be polymerized by irradiation with ultraviolet rays, electron beams, etc.

There is no particular limitation on the mixing ratio of at least one compound selected from these and the polymer compound. The polymer compound may also be a mixture of two or more selected from the polymer compounds of the present invention.

When the components that form a film by the LB method are spread on the water surface,
For -i, benzene, chloroform, etc., which are insoluble in water and evaporate into the gas phase at °C, are used as solvents.
In the case of the polymer compound of the present invention, it is desirable to use an organic polar solvent in combination to increase solubility. Preferred organic polar solvents are N,N dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, dimethylsulfoxide, N-methyl 2-pyrrolidone. , pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylenesulfone,
Dimethyltetramethylene sulfone, etc.

Therefore, when developing a polymer compound and a known LB film compound, it is desirable to use a mixed solvent of a solvent such as benzene or chloroform and an organic polar solvent.

When benzene, chloroform, etc. are used together with an organic polar solvent, it is thought that the benzene, chloroform, etc. will evaporate into the gas phase when the membrane is developed, and the organic polar solvent will dissolve in a large amount of water.

Next, the inorganic material of the present invention will be explained. This inorganic material is used as an intermediate layer of a three-layer resist, the pattern of the upper LB film is transferred to this intermediate layer, and oxygen RI E (ReactνeIon) is applied using the intermediate layer pattern as a mask.
A pattern of the lower layer organic polymer material is obtained by etching). Silicon oxide, silicon nitride, silicon, germanium, spin-on glass, etc. are preferably used.

These inorganic material films are formed by vacuum deposition or CVD.

Silicon oxide film forming materials used in semiconductor silicon wafer processing can also be preferably employed. The composition of the coating liquid for formation is based on the chemical formula of the organosilicon compound [Rn5
i(Oil)4-n] as a main component, to which a vitreous forming material, an organic binder, etc. are added, and the mixture is dissolved in an organic solvent containing alcohol as a main component. The desired film can be easily obtained using various coating methods such as spin coating.

The dry-etch resistant organic polymer material used for the lower layer is selected from organic polymer materials that can flatten steps on the substrate and serve as a mask when dry etching the substrate.

Polymethyl methacrylate, polyacrylate.

Acrylic resins such as polymethyl isopropenyl ketone and polyglycidyl methacrylate, polystyrene, polymethylstyrene, styrene-maleic anhydride copolymers, styrenic resins such as polyhydroxystyrene, novolacs such as phenol-formaldehyde novolac resins and talesol-formaldehyde novolac resins. and polyimide resins are used.

From the viewpoint of dry etching resistance, hard-baked novolac resins and polyimide resins are preferably used.

Particularly preferred are general-purpose novolak positive photoresists and hard-baked polyimide resins for semiconductors.

The above polymer materials can be applied by a spin coating method or the like used in ordinary semiconductor manufacturing processes by selecting an appropriate solvent, and are preferred for planarization.

The microfabrication method will be explained.

The above-mentioned organic polymeric material is applied to the substrate.

If the substrate has irregularities, the coating is applied to a sufficient thickness so that the irregularities can be flattened and the substrate can be processed by dry etching through the pattern of the organic polymer material. 1~
A thickness of about 2 μm is used.

After coating by spin coating or the like, it is desirable to remove the solvent contained in the coated film and to sufficiently bake it to ensure heat resistance and dry etching resistance.

A film of an inorganic material as an intermediate layer is formed on the formed lower organic polymer film. Oxygen RI is applied to the lower organic molecular film.
The inorganic material and film thickness are selected to be sufficient to provide E. 0.1~0
．． A thickness of about 3 μm is used. A three-layer resist is formed by accumulating an LB film thereon. Next, if necessary, UV rays, electron beams, X-rays, etc. are irradiated through a mask. In particular, ultraviolet light is preferable, and it is further preferable to use excimer laser light such as KrP because a high-resolution pattern can be obtained and the exposure time can be shortened.

For example, a positive pattern of the LB film can be obtained by exposing the LB film to ultraviolet light through a mask and then dissolving and removing the exposed portion with a developer.

It is not necessarily clear why the LB film pattern can be formed, but it seems to be due to the main chain bond being cut in the positive type, and the polymer compound of the present invention has an absorption maximum at λma = approximately 200, 250 nm. This seems to be related to having .

For two, J, Kosar rLight 5ens
itive Systems (John Wiley,
& 5ons, Inc., New York+ 1
It may be preferable to use the sensitizers described in p. 965), p. 143-146, p. 160-188. For example, Mihiraketone, benzoyl ether, 2-t-
Butyl-9,10-anthraquinone, 1,2-benzo-
Examples include 9,10-anthraquinone and 4,4°-bis(diethylamino)benzophenone.

As the developer, a mixed solvent system of dimethylacetamide, dimethylformamide, dimethylsulfoxide, hexamethylphosphoramide, N-methylpyrrolidone, etc., and methanol, ethanol, etc. is used. In addition to organic solvents such as methanol and ethanol, aqueous ammonia, aqueous inorganic alkaline solutions, and organic alkaline solutions such as tetramethylammonium hydroxide are preferably used.

In a negative LB film, it is thought that a pattern can be formed by polymerization or secondary formation, which changes the solubility in a solvent.

It is also preferable to use the following sensitizers and their long-chain hydrocarbon substitutes. Preferred sensitizers include sensitizers known in the art, such as anthraquinone, benzoquinone, naphthoquinone, benzanthraquinone, benzophenone, etc., including long-chain hydrocarbon substitutes modified to be preferred for LB films.

In the case of negative-tone photosensitive, the developer may be a solvent for the negative-tone photosensitive compound, but N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, hexamethylphosphorol can be used. A mixed solvent of amide, N-methyl-2-pyrrolidone, etc., and benzene, ether, chloroform, acetone, etc. is preferable.

Although the LB film of the present invention contains aromatic rings, it can be made very thin, so absorption, which is a problem with phenol novolak resists, does not become a problem, and it is possible to obtain a good pattern of about an automicron size. I can do it.

Furthermore, since it has excellent dry etching resistance, the pattern of the LB film can be transferred to the inorganic material film of the intermediate layer by anisotropic dry etching. As a pattern mask for this intermediate layer, a pattern of the underlying organic polymer material is obtained by oxygen RIE.

Using the pattern of this organic polymer material as a mask, anisotropic dry etching was performed using CCl4.
CCl4 + He, C121CHFII CCl4
By using +021BCh, SF6, etc., Si, polySi.

Many materials such as AI and Mo can be microfabricated.

The method of the present invention will be explained in more detail with reference to Examples.

Example I 1. Tokyo Ohka 0FPR5000 was deposited on a silicon wafer.
It was formed to a thickness of 5 μm, beta-heated at 130°C, and a spin-on glass was formed on Tokyo Ohka OCD 0.2 μm.
Bake at 130°C.

After that, it has a fire structure (white space below). Using a mixed solution of polyamic acid distearyl ester and stearyl alcohol in a 1:1 (molar ratio) (chloroform: dimethylacetamide + 8 = 2), 31 layers (810 people) were formed by the LB method. ) accumulated. A positive pattern of the LB film was formed by irradiating light having a main wavelength of 250 nm through a mask and developing with an alkaline aqueous solution.

The spin-on glass was anisotropically etched using CF4/Hz using the positive pattern of the LB film as a mask, and the novolac resist was anisotropically etched using 02RIE using the spin-on glass mask, resulting in a good positive pattern of the LB film. N confirmed that it would be transcribed.

Claims (1)

[Claims] A three-layer resist using an LB film, characterized in that a dry etch-resistant inorganic material and a dry etch-resistant organic polymer material are disposed between the LB film and the substrate.