JPS628777B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pattern forming method. In particular, the present invention relates to a method for forming fine patterns of photosensitive compositions in the production of semiconductors and integrated circuits.

In recent years, with the increasing integration and density of solid-state devices, there has been a demand for efficient formation of fine patterns. For example, 1μ using an electron beam sensitive composition.
It is possible to form a pattern with a width of about m. However, in order to irradiate an electron beam, the electron beam must be narrowed down and sequentially irradiated from end to end of the irradiated surface, and it takes a long time to irradiate one sample. For example, the time required to irradiate a 10×10 cm surface is usually about 0 to 50 minutes, depending on the sensitivity of the composition used and the contents of the pattern. Moreover, the irradiation must be carried out in a vacuum, and considering the time and effort required to keep the sample in a vacuum, it is not preferable to irradiate products manufactured industrially in large quantities with an electron beam.

On the other hand, if a photosensitive composition is used and exposed to light through a mask, it can be carried out in a short time. However, ordinary photosensitive compositions have a wavelength of about 320 to 500 nm.
Sensitive to light of m. When light of this wavelength is irradiated through a mask, it is difficult to form a pattern with a width of 1 to 2 μm due to diffraction and interference phenomena based on its inherent properties.

One method for forming such fine patterns is 200 to 320 nm, preferably 200 to 320 nm.
A method using short wavelength ultraviolet light of 300 nm has been proposed. In this case, since the effects of diffraction, interference, etc. are reduced, a precise pattern can be formed. However, polymethyl methacrylate and polymethyl isopropenyl ketone are known as materials that are sensitive to short wavelength ultraviolet light, but both of these have extremely low sensitivity to short wavelength ultraviolet light and are of little practical use. It became clear.

The present invention aims to form fine patterns with high sensitivity in a short time.

The pattern forming method of the present invention is based on the general formula (However, A represents an element or substituent such as O, S, CH ₂ , CH ₂ CH ₂ , SO ₂ or S ₂ , and X represents H or
Represents the element _N3 or a substituent, Z represents the element where X is H
When X is N3, the substituent is _N3 , and when X is _N3 , it is an element H or Cl), and a polymer compound that is crosslinked by a photoreaction product of the bisazide compound. forming a coating film of a photosensitive composition on a substrate;
It is characterized by comprising a step of irradiating the coating film with short wavelength ultraviolet light having a predetermined pattern, and a step of removing unexposed portions of the coating film by development.

The above bisazide compounds include 4,4'-diazide diphenyl ether, 4,4'-diazide diphenyl sulfide, 4,4'-diazide diphenyl sulfone, and 3,3'-diazide diphenyl. sulfone, 4.4'-diazide diphenylmethane, 3.
3'-dichloro-4,4'-diazide diphenylmethane, 4,4'-diazide diphenyl disulfide,
Examples include 4,4'-diazidobibenzyl. Two or more of these compounds can be used in combination.

These bisazide compounds can be synthesized by reacting the corresponding diamine compound with hydrochloric acid and sodium nitrite in an aqueous solution to diazotize it, and adding sodium azide to the resulting diazonium salt solution to form an azide.

For example, 4,4'-diaminodiphenyl ether is reacted as described above to form 4,4'-diazide diphenyl ether (77°C; hereinafter the numbers in parentheses indicate the melting point).

Synthesized from the corresponding diamine in a similar manner,
Preferred compounds used in the present invention are 4,4'-
Diazidophenyl sulfide (90℃), 4・4'-
Diazido diphenyl sulfone (163℃), 3・3'-
Diazido diphenyl sulfone (116℃), 4・4'-
Diazidiphenylmethane (44°C), 3,3'-dichloro-4,4'-diazidodiphenylmethane (128°C), 4,4'-diazide diphenyl disulfide (37°C), 4・4′-Diazidobibenzyl (80
℃) etc.

On the other hand, examples of polymer compounds crosslinked by the photoreaction product of the bisazide compound include natural rubber,
Modified rubber such as cyclized natural rubber, polybutadiene,
Synthetic rubbers such as polyisoprene, cyclized polybutadiene, cyclized polyisoprene, polychloroprene, styrene-butadiene rubber, and nitrile rubber, and organic solvents such as synthetic polymer compounds such as polystyrene, nylon, novolak resin, polyvinylphenol, and polyvinyl butyral. A soluble polymer compound is used. Of course, two or more types of polymer compounds can also be used in combination. Among the above-mentioned polymer compounds, rubber-based compounds are preferable because they are excellent as a coating film.

To form a coating film of the photosensitive composition, various known methods are used, for example, a solution of the photosensitive composition is coated by a spin coating method, a spray coating method, etc.
Do this after drying.

As described above, the exposure is preferably carried out using short wavelength ultraviolet light of 200 to 320 nm, preferably 200 to 300 nm, through a mask having a predetermined pattern.

Development is carried out in a conventional manner using a solvent that dissolves the unexposed photosensitive composition but does not dissolve the portion of the coating cured by exposure. A mixture of two or more solvents may be used.

One of the effects of the pattern forming method of the present invention is that it does not show oxygen desensitization when certain of the above-mentioned bisazide compounds are used. Generally, photosensitive compositions using a bisazide compound as a crosslinking agent exhibit oxygen desensitization. In other words, when exposed in an air containing oxygen gas, the reaction is inhibited, preventing the surface of the film from curing, or forming a film in areas where the exposure intensity is low, resulting in the formation of a desired pattern in the film. becomes difficult to do. Therefore, methods such as exposure in an inert gas such as nitrogen gas are used.

However, a photosensitive composition using a bisazide compound in which A is SO ₂ in the general formula as a crosslinking agent does not exhibit oxygen desensitization. Therefore, the use of such a photosensitive composition is extremely advantageous industrially since the same results can be obtained even when exposure is carried out in air as when exposure is carried out in nitrogen gas.

Among the above-mentioned compounds, such bisazide compounds include 4,4'-diazide diphenyl sulfone,
Examples include 3,3'-diazide diphenyl sulfone.

The present invention will be explained in more detail with reference to Examples below.

Example 1 A photosensitive solution was prepared by dissolving 10 g of cyclized polyisoprene rubber and 0.1 g of 4,4'-diazide diphenyl sulfide in 90 g of xylene. This photosensitive solution was spin-coated onto a silicon wafer on which an oxide film was formed, and dried to form a photosensitive film with a thickness of about 0.9 μm. Subsequently, this substrate was exposed for 2 seconds under a nitrogen gas atmosphere using a 500 W xenon-mercury lamp through a chrome mask on the quartz substrate. At that time, 300n
A cold mirror that transmits light with a wavelength longer than m,
It was placed between the light source and the mask. Thus, the wavelength
When the substrate exposed to deep ultraviolet light of 200 to 300 nm was developed with a developer consisting of n-heptane and xylene and the unexposed areas of the photoresist film were dissolved and removed, 2.
A pattern with a width of 1 μm was formed at μm intervals.

On the other hand, when the same experiment was carried out using polymethyl methacrylate and polymethyl isopropenyl ketone, which are known as deep ultraviolet photoresists, the exposure time to obtain a good pattern was 400 seconds for the former and 80 seconds for the latter. It cost. That is, the photosensitive composition according to the present invention is 200 times more sensitive than polymethyl methacrylate, and
It was 40 times more sensitive than polymethyl isopropenyl ketone.

Examples 2 to 7 Similar experiments were conducted using the following bisazide compounds in place of 4,4'-diazidophenyl sulfide in Example 1. Good fine patterns were obtained using the following exposure times.

3,3'-Diazido diphenyl sulfone (12
sec), 4,4′-diazide diphenyl ether (4
sec), 4,4′-diazide diphenyl sulfone (6
3,3'-dichloro-4,4'diazide diphenylmethane (6 seconds), 4,4'-diazide diphenyl disulfide (10
4,4'-Diazidiphenylmethane (6 seconds), 4,4'-Diazidobibenzyl (4 seconds).

Examples 8 and 9 Photosensitive compositions used in Examples 2 and 4,
That is, using a composition consisting of 3,3'-diazide diphenyl sulfone and cyclized polyisoprene rubber and a composition consisting of 4,4'-diazide diphenyl sulfone and cyclized polyisoprene rubber, Examples 2 and 4 except that exposure was performed.
processed in the same way. In this case, results similar to those obtained by exposure in nitrogen gas were obtained.

For comparison, when a composition consisting of 4,4'-diazidiphenylmethane and cyclized polyisoprene rubber was exposed in air in the same manner as above, the surface of the film did not harden and the film thickness was sufficient. It wasn't.

Example 10 3 g of polyvinyl butyral, 0.2 g of 4,4'-diazide diphenyl ether and 97 g of cyclohexanone
The same treatment as in Example 1 was carried out using this solution. A good pattern was obtained with an exposure time of 4 seconds.

Claims (1)

[Claims] 1. General formula (However, A represents an element or substituent such as O, S, CH ₂ , CH ₂ CH ₂ , SO ₂ or S ₂ , and X represents H or
Represents the element _N3 or a substituent, Z represents the element where X is H
When X is N3, the substituent is _N3 , and when X is _N3 , it is an element H or Cl), and a polymer compound that is crosslinked by a photoreaction product of the bisazide compound. forming a coating film of a photosensitive composition on a substrate;
A pattern forming method comprising the steps of irradiating the coating film with short wavelength ultraviolet light having a predetermined pattern, and removing unexposed portions of the coating film by development. 2 The bisazide compound is 4,4'-diazide diphenyl ether, 4,4'-diazide diphenyl sulfide, 4,4'-diazide diphenyl sulfone,
3,3'-diazide diphenyl sulfone, 4,4'-
Diazidodiphenylmethane, 3,3'-dichloro-
The claim is at least one bisazide compound selected from the group consisting of 4,4'-diazidodiphenylmethane, 4,4'-diazidodiphenyl disulfide, and 4,4'-diazidobibenzyl. The pattern forming method according to item 1. 3. The pattern forming method according to claim 2, wherein the bisazide compound is 4,4'-diazide diphenyl sulfide. 4 The polymer compound is natural rubber, cyclic natural rubber,
Polybutadiene, polyisoprene, cyclized polybutadiene, cyclized polyisoprene, polychloroprene, styrene-butadiene rubber, nitrile rubber,
The pattern forming method according to any one of claims 1 to 3, wherein the pattern forming method is at least one polymeric compound selected from the group consisting of polystyrene, nylon, novolak resin, polyvinylphenol, and polyvinyl butyral. 5 The polymer compound is natural rubber, cyclized natural rubber,
The pattern formation according to claim 4, which is at least one polymeric compound selected from the group consisting of polybutadiene, polyisoprene, cyclized polybutadiene, cyclized polyisoprene, polychloroprene, styrene-butadiene rubber, and nitrile rubber. Method. 6. The pattern forming method according to any one of claims 1 to 5, wherein the irradiation with short wavelength ultraviolet light is performed while keeping the coating film in an atmosphere of inert gas. 7 The bisazide compound is at least one compound selected from the group consisting of 4,4'-diazide diphenyl sulfone and 3,3'-diazide diphenyl sulfone, and irradiation with short wavelength ultraviolet light causes the coating film to 6. The pattern forming method according to claim 1, wherein the pattern forming method is carried out in an atmosphere containing oxygen gas.