JPH045178B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photosensitive composition for microfabrication, including the semiconductor industry, and more specifically, the present invention relates to a photosensitive composition for microfabrication, including the semiconductor industry, and more specifically, it is made by adding a specific aromatic azide compound to a polymerized polymer to impart photosensitivity, and then plasma-developed it to form a micropattern. The present invention relates to a photosensitive composition suitable for forming a photosensitive composition. Photolithography is part of the manufacturing process for semiconductor devices. This involves forming a photoresist film that becomes a resistive film during etching on a silicon wafer with a silicon oxide film thickness of several hundred nanometers, selectively irradiating it with ultraviolet rays through a desired mask, then developing and exposing it. Etch the silicon oxide film. Thereafter, the photoresist film is peeled off, the wafer is thoroughly cleaned, and impurities are diffused and implanted from the exposed silicon area. Semiconductor elements are manufactured by repeating these operations and further creating electrodes and wiring. Currently, the resists used in microfabrication, including the semiconductor industry, are negative resists such as OMR (manufactured by Tokyo Ohka Kogyo Co., Ltd.), ONNR (manufactured by Tokyo Ohka Kogyo Co., Ltd.),
There are KMR (manufactured by Kodatsu), and positive resists such as OFPR (manufactured by Tokyo Ohka Kogyo), ONPR (manufactured by Tokyo Ohka Kogyo), KMPR (manufactured by Kodatsu), and AZ (manufactured by Shippray). All of these resists are developed using a developer in the semiconductor manufacturing process, and the resulting resist film is used as a mask to etch the silicon oxide film using hydrofluoric acid etching, and then the resist film is removed using a stripping agent. do. In this way, these products use a solvent as a developer in the development process, so the solvent seeps into the resist film.
The resist film pattern swells, making it impractical to form fine patterns, and since a large amount of solvent is used, there are problems such as deterioration of the working environment. In recent years, it has been proposed to form a pattern on a resist film using a dry developing method that has improved the problems caused by these wet developing methods. After selectively irradiating the resist film with active rays, a process (such as heat treatment) that creates a difference in plasma resistance between the irradiated area and the non-irradiated area is applied, and this difference is used to generate plasma gas. In this method, a resist film pattern is formed by performing a development process. This dry development method is particularly advantageous for forming fine patterns because it does not use any solvent at all, and has many other advantages such as being free from pollution, so it is an extremely effective method for the semiconductor industry. As photosensitive compositions for dry development, those comprising an acrylic and/or vinyl ketone polymer and a sublimable azide photocuring agent are known (Japanese Unexamined Patent Publication No. 137347/1983). .
However, these resist films have low sensitivity to active radiation and low plasma resistance, so the residual thickness of the pattern is low, and the underlying silicon oxide film, etc., is etched using the pattern as a protective film. In some cases, it may no longer function as a protective film. Furthermore, conventional photosensitive compositions have disadvantages such as poor storage stability and cannot be stored for long periods of time, making them impractical. Therefore, the present inventors aimed to provide a highly practical photosensitive composition for dry development, and as a result of various studies, it was found that a photosensitive composition consisting of a polymer and a specific aromatic azide compound can achieve the objective. This discovery led to the completion of the present invention. That is, the present invention is a photosensitive composition for dry development comprising a polymer and an aromatic azide compound described below. The present invention will be explained in detail below. The polymer that is a component of the composition of the present invention must be easily ashed and removed in plasma gas. Examples of such things include:
Polymethyl methacrylate, polymethyl isopropenyl ketone, polyglycidyl acrylate, polyglycidyl methacrylate, copolymer of glycidyl methacrylate and methyl methacrylate, copolymer of glycidyl acrylate and methyl methacrylate, polyvinyl chloride, polyvinyl acetate,
Copolymer of vinyl chloride and vinyl acetate, copolymer of vinyl chloride and acrylic acid, polyisopropyl pinyl ketone, polybutyl methacrylate, poly(2,3-dichloro-1-propyl acrylate), poly(1, 3-dichloro-1-propyl acrylate), poly(2-chloroethyl acrylate), and the like. The other component, the aromatic azide compound, is represented by the following general formula () or (). [In the formula, X ₁ is −CH=CR ₁ −CO−CR′ ₁ =CH−, −CH=CH−CH=CR ₃ −CO−CR ₃ =CH−CH=
CH- (where R ₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, a phenyl group, a phenoxy group,
R′ ₁ is an alkyl group having 1 to 3 carbon atoms, cyano group, phenyl group, phenoxy group, R ₂ is an alkyl group having 2 to 3 carbon atoms, cyano group, phenyl group, phenoxy group, R ₃ is each independently Hydrogen atom, carbon number 1
~3 alkyl group, cyano group, phenyl group, phenoxy group)] () N ₃ -A-X ₂ -A'-N ₃ [In the formula, X ₂ is -CH=CH-CO-, -CH= _CR4 −CO− _CR4 =CH−, −CH=CH−CH=CR ₄ −CO−CR ₄ =CH−CH=
CH- (where A is

【formula】

【formula】

[Formula] A′ is

【formula】

[Formula] R ₄ is each independently a hydrogen atom, carbon number 1-
3 represents an alkyl group, a cyano group, a phenyl group, or a phenoxy group)] Specifically, 4,4'-diazidodibenzylidene methylacetone, 4,4'-diazidodibenzylidene, 4,4'-diazidodibenzylidene, azidodibenzylidene monophenoxyacetone, 2,6-di-(4-azidobenzylidene)-4-isopropylcyclohexanone,
2,6-di-(4-azidobenzylidene)-4-cyanocyclohexanone, 2,6-di-(4-azidobenzylidene)-4-phenoxycyclohexanone, 2,6-di-(4-azido cinnamylidene)-cyclohexanone, 2,6-di-(4-azidocinnamylidene)-4-methylcyclohexanone, 2,6-di-(4-azidocinnamylidene)-
4-cyanocyclohexanone, 4,4'-diazidodicinnamylidene acetone, 4,4'-diazidodicinnamylidene monocyanoacetone, 4,4'-diazidodicinnamylidene dicyanoacetone, 4,
4'-Diazidodicinnamylidene monomethylacetone, 4,4'-Diazidodicinnamylidene dimethylacetone, 4,4'-Diazidodicinnamylidene monophenoxyacetone, 4,4'-Diazidodicinnamylidene monomethylacetone Enoxyacetone, 4,4'-diazidocinnamylidene monophenylacetone, 4,
4'-Diazidodicinnamylidene diphenylacetone, etc., or one or two of the 1,4-phenylene groups bonded to the azide group of these aromatic azide compounds to a 1,4-naphthylene group or 9,10-
Those converted to anthrylene groups, specifically 2-
(4-azidobenzylidene)-4-phenoxy-6
-(4-azidobenzobenzylidene)-cyclohexanone, 2,6-di-(4-azidobenzobenzylidene)-4-cyanocyclohexanone, 4-
Azidobenzocinnamylidene-10-Azidobenzocinnamylidene diphenoxyacetone, di(10
- diazidobenzocinnamylidene) diphenylacetone, etc. In order to form a fine pattern using the photosensitive composition of the present invention comprising the above polymer and an aromatic azide compound, a coating solution is first prepared. For this purpose, the polymer and aromatic azide compound are dissolved in a single solvent or a mixture of solvents such as cyclohexanone, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, toluene, chlorobenzene, and tetrahydrofuran. This coating solution is applied onto a substrate such as a silicon wafer using a spinner set at an appropriate rotation speed to form a desired film thickness. Further, the substrate is placed in a hot air dryer to evaporate the used solvent, a resist film is obtained on the substrate, and active rays are irradiated through a predetermined patterning mask. The active ray in this case is a particle beam or an electromagnetic wave, and the particle beam can be an electron beam or an ion beam, and the electromagnetic wave can be an ultraviolet ray, a deep ultraviolet ray, or an X-ray. Next, the resist film is subjected to some kind of treatment, such as heating, reduced pressure, or a combination of both, to create a difference in plasma resistance between the active ray irradiated area and the non-irradiated area. After this treatment, a resist film pattern can be formed on the substrate by placing it in a gas plasma device and performing dry development treatment using plasma gas. Suitable introduction gases for the development process include O ₂ , fluorocarbon, fluorocarbon-O ₂ series, O ₂ -Ar series, and the like. In the photosensitive composition for dry development of the present invention, when the resist film is selectively irradiated with actinic radiation, the aromatic azide compound is activated and acts on the polymer in the resist film to crosslink it. The cross-linked aromatic azide compound and polymer are then rearranged through subsequent processing.
It has a structure that deactivates the excitation energy caused by plasma gas, and the resistance to plasma gas is significantly improved. Therefore, the ashing rate of the irradiated area in the plasma gas becomes extremely low. On the other hand, the unchanged aromatic azide compound in the non-irradiated area is inactivated by the treatment, resulting in a difference in plasma resistance between the irradiated area and the non-irradiated area, and the non-irradiated area is inactivated in the plasma gas. is easily ashed and selectively removed, and the irradiated area remains on the substrate in a pattern with less film loss. The photosensitive composition of the present invention creates a large difference in plasma resistance between the active ray irradiated area and the non-irradiated area compared to conventional ones, so it is possible to easily form a pattern with a high residual film thickness. Since the aromatic azide compound of the invention has high solubility, it provides a composition with high sensitivity and resolution, and has good storage stability with little change over time, making it extremely practical. Next, the present invention will be specifically explained with reference to Examples. Example Polymethyl isopropenyl ketone with a molecular weight of 200,000
Various coating solutions prepared by dissolving 10 g of various aromatic azide compounds shown in Table 1 in about 90 g of cyclohexanone were spin-coated onto silicon wafers at 3000 rpm for 30 seconds. Next, it was dried for 20 minutes in a hot air dryer kept at 85°C to evaporate the remaining solvent in the coating film to obtain a resist film. Next, a PLA-520F ultraviolet exposure device with a CM-290 molded mirror installed.
(manufactured by Canon Inc.) was used to perform hard contact exposure to far ultraviolet rays through a resolution test mask with a minimum pattern of 0.5 μm. Next, after heat treatment in a temperature atmosphere of 140°C for 30 minutes, the silicon wafer was placed in the processing chamber of a plasma processing equipment OAPM-300 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) at a frequency of 13.56MHz, an RF output of 100W, and a table temperature of 100°C. Table 1 summarizes the results of investigating the sensitivity, solubility, and stability of various resists by developing with oxygen plasma gas under conditions of , pressure of 1.0 Torr, and oxygen gas flow rate of 100 c.c./min.

【table】

[Table] From Table 1, it can be seen that the composition of the present invention is superior in sensitivity, solubility, and stability compared to conventional compositions.

Claims (1)

[Claims] 1. Polymethyl methacrylate, polymethyl isopropenyl ketone, polyglycidyl acrylate, polyglycidyl methacrylate, copolymer of glycidyl methacrylate and methyl methacrylate, copolymer of glycidyl acrylate and methyl methacrylate, polyvinyl chloride , polyvinyl acetate, copolymer of vinyl chloride and vinyl acetate,
Copolymer of vinyl chloride and acrylic acid, polyisopropenyl ketone, polybutyl methacrylate,
At least one polymer selected from poly(2,3-dichloro-1-propyl acrylate), poly(1,3-dichloro-1-propyl acrylate) and poly(2-chloroethyl acrylate) and the following general formula ( ) or an aromatic azide compound represented by (). [In the formula, X ₁ is −CH=CR ₁ −CO−CR′ ₁ =CH−, −CH=CH−CH=CR ₃ −CO−CR ₃ =CH−CH=
CH- (where R ₁ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, a phenyl group, a phenoxy group,
R ₁ is an alkyl group with 1 to 3 carbon atoms, cyano group, phenyl group, phenoxy group, R ₂ is an alkyl group with 2 to 3 carbon atoms, cyano group, phenyl group, phenoxy group, R ₃ is each independently hydrogen Atom, carbon number 1
~3 alkyl group, cyano group, phenyl group, phenoxy group)] () N ₃ -A-X ₂ -A'-N ₃ [In the formula, X ₂ is -CH=CH-CO-, -CH= _CR4 −CO− _CR4 =CH−, −CH=CH−CH=CR ₄ −CO−CR ₄ =CH−CH=
CH- (where A is [Formula] [Formula] [Formula] A′ is [Formula] [Formula] R ₄ is each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyano group, a phenyl group, (represents a phenoxy group)]