JPS59142538A - Photosensitive composition - Google Patents

Abstract

PURPOSE:To obtain a photoresist film high in photosensitivity by using an azo compd. type light absorbing agent. CONSTITUTION:The azo compd. type light absorbing agent to be mixed with a photoresist is represented by general formula ( I )-(III) in which phenyl and naphthyl groups may be substd. by the prescribed group and when needed, moreover, lower alkyl or alkoxy, halogen, hydroxy, and/or the like group; R<1> is H or OH; R<2> is H, NO2, or di(lower alkyl)amino; one of R<3> and R<4> is OH and the other is H; and R<5> is formula (IV), (V), or (VI).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive composition containing a novel light absorbing agent, and particularly to a photosensitive composition suitable for microfabrication of semiconductor devices and the like.

Semiconductor elements such as transistors, ICs, and LSIs have so far been manufactured using microfabrication technology using photoetching. This photoetching method involves forming a photoresist layer on a silicon wafer, overlaying a mask with a predetermined pattern on it, exposing it to light, developing it to form an image, and then etching it to form the desired pattern. This is a method of performing selective diffusion using this. After selective diffusion is performed by repeating these steps several times, aluminum electrodes and wiring are processed to produce a semiconductor electronic component.

In manufacturing such a semiconductor device, if selective diffusion is performed several times, a step difference of 1 μm or more is usually generated, and if passivation is applied to this step, the step difference becomes even larger. When applying aluminum wiring to such a surface, it is necessary to deposit aluminum on the surface of the silicon wafer and then etch it using a photoetching method.
When exposed to light, halation due to the aluminum surface is generally large, and when negative or positive type autoresist or deep UV resist is used, halation may occur on the substrate surface not only on the flat parts of the surface but also on the stepped parts. There is a drawback that vertically incident light rays cause diffuse reflection on the sloped surface of the stepped portion, making it difficult to accurately reproduce a pattern with a thin line width of several μm.

In order to prevent this halation and accurately reproduce fine images, various researches have been conducted on photoresists, and a technology has been developed to add light-absorbing materials to them (Japanese Patent Publication No. 37562/1983). .

Conventionally, as light absorbers for photoresist, oil yellow (trade name), which is a type of organic dye, and l-alkoxy-
4-(4'-N,N-dialkylaminophenylazo)
Benzene derivatives etc. have been adopted (Japanese Patent Application Laid-open No. 55-3
6838). However, oil yellow is usually 8
It has the disadvantage that it easily sublimes and volatilizes from the photoresist film during prebaking performed at a temperature of 0 to 100°C, significantly impairing the antihalation effect during exposure, and is greatly affected by the prebaking processing conditions. There was a drawback that this occurred. On the other hand, the latter has no problem with sublimation and volatility during pre-baking, but has the disadvantage that, when incorporated into a positive photoresist consisting of, for example, a phenol novolac resin and an O-quinone diazide compound, the sensitivity is significantly reduced.

The present inventors (1) have conducted extensive research into light absorbing agents that can overcome the drawbacks of conventional photosensitive resin compositions and act effectively in any photoresist, and as a result, have developed a certain type of azosol. The inventors have discovered that a compound-based light absorber is effective in achieving this objective, and have completed the present invention based on this knowledge.

That is, the present invention provides a photoresist with the general formula [wherein R1 is a hydrogen atom or a hydroxyl group, R2 is a hydrogen atom,
is a nitro group or a di(lower alkyl)amino group] 3 (in the formula, one of R3 and R4 is a hydroxyl group and the other is a hydrogen atom) or (in the formula, R5 is O) At least one selected from compounds
The present invention provides a photosensitive composition characterized in that it contains a certain type of light absorbing agent.

The phenyl group and naphthyl group in the above general formulas (1), (II), in addition to the predetermined substituents, may further include a lower alkyl group, a lower alkoxyl group, a halogen atom, and a hydroxyl group as desired. It may have at least one type of substituent selected from among these azo compounds. Examples of particularly suitable azo compounds are shown below.

, i/-dimethylaminoazobenzene 2,4-dihydroxy-47-ethylaminoazobenzene H 2,4-dihydroxyazobenzene 2,4-dihydroxy-4'-nitroazobenzene 4-
(3-methoxy-4-hydroxybenzilitine)aminoazobenzene-1n 2-hydroxynaphthalene-1-azobenzene8-hydroxynaphthalene-1-azo-(2'-methylbenzene) 8-hydroxynaphthalene-1-azo(2/ .

4'-dimethylbeshizene) 1-'[4'-(2-methyl-1-phenylazo)-
2'-Methylphenylazo)-2-hydroxybenzene M("1 l-(4'-phenylazo-1'-phenylazo)-2
-Hydroxynaphthalene These azo compounds are usually used alone, but if desired, two or more types can be used in combination.

Next, the photoresist used as a base material of the composition of the present invention includes, for example, a negative photoresist mainly composed of a polymer compound and a bisazide compound, a phenol, a novolac resin, a cresol novolak resin, or both, and at least one Positive photoresist containing 0-quinonediazide compound or polymethyl methacrylate (PM
MA), polymethyl isopropenyl ketone (PMIPK
) or boglycidyl methacrylate) (PGMA), and other deep UV resists mainly composed of polymers.

An example of the negative photoresist is 0NNR-20.
, 0NNR-22 (trade name, Tokyo Ohka Kogyo ■1), and examples of positive photoresists include 0FPR-2.
, 0FPR-77, 0FPR-800 [trade name, manufactured by Tokyo Ohka Kogyo ■], AZ-1350, AZ-1400 [trade name, manufactured by Silaplay Co., Ltd.].

Also, an example of deep UV resist is 0DUR-10.
Examples include 0,0DUR-1000,0DUR-1013 [trade name, manufactured by Tokyo Fuka Kogyo ■], and the like.

The amount of the photoabsorbent to be contained in the photosensitive composition of the present invention is:
Based on the weight of the above photoresist, 0.1 to 20% by weight
It is preferable to add it in a range of , particularly in a range of o, i to 15% by weight. If the amount added is less than this, the antihalation effect will not be exhibited, and if it is more than this, crystals of the light absorbing agent will tend to precipitate in the photoresist film and form a heterogeneous phase, which is not preferable.

The light-absorbing agent used in the present invention has excellent compatibility with all film-forming components of negative photoresists, positive photoresists, and deep UV resists, including monoethyl ether acetate and ethylene glycol. It is easily soluble in many organic solvents such as monoethyl ether and cyclohexanone, so it can be easily and uniformly added by adding it directly to the resist film forming solution, or by dissolving it in a small amount of an organic solvent that dissolves in nucleic acid. It is possible to obtain a composition that is Furthermore, the light absorbing agent used in the present invention does not show sublimation even at high temperatures and remains stably in the photoresist film at a high residual rate even after pellet baking, so it has an extremely large antihalation effect during exposure. The pattern forming ability of various photoresists can be improved. In particular, when a positive photoresist made of a phenol novolac resin and an O-quinonediazide compound, which is conventionally said to have a large sensitivity decrease due to prebaking, contains a light absorbing agent of the general formulas (1) to (III), the sensitivity This provides a practical positive-working photosensitive composition with extremely low deterioration and satisfactory properties.

As described above, when the photosensitive composition of the present invention pre-bakes the coating film at a temperature of, for example, 80 to 100°C to evaporate the solvent, the light absorbing agent remains in the resist film without volatilization or change. Because it exists stably in .

Therefore, when using the composition of the present invention, it is possible to easily form a photoresist film firmly adhered to a substrate without causing wrinkles on the surface due to residual solvent. In addition, even if left for a long time after prebaking, crystals will not precipitate in the photoresist film and form a heterogeneous phase, so it can be stored as a film, which reduces the allowable range of photoetching operations. becomes wider,
Handling becomes easier. Furthermore, since products of stable quality can be mass-produced and there is no decrease in sensitivity due to the addition of a light absorbing agent, a projection type mask aligner can also be used, making it possible to use it in the field of ultra-fine processing.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these Examples.

Example 1 Positive photoresist l-0FP containing phenolic novolac resin and at least one O-quinonediazide compound
R-soo (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd., solid content 27% by weight) was added with 4-hydroxy-4'-dimethylamineazobenzene, a light absorbing agent, at a solid content of 3% to make it photosensitive. A composition was prepared.

This composition was applied to a silicon wafer with a 1 μm thick step structure on which a 0.5 μm thick aluminum layer was deposited.
．． Spin code to a thickness of 3 μm, pre-baking at 90°C for 20 minutes using a hot air circulation dryer,
A film was formed. Canon mask aligner - PLA-500, which has a 200W ultra-high pressure mercury lamp connected to it through the mask.
(manufactured by Canon ■) for 4.5 seconds, and the developer solution NMD.
-a (trade name, manufactured by Tokyo Ohka Kogyo ■) for 1 minute at a liquid temperature of 25° C., and developed by the immersion method. The formed resist pattern had no dashed lines due to the effect of halation or jaggedness due to the effect of standing waves, and was resolved to a line width of 0.5 μm.

Comparative Example 1 and Control Example In Example 1, instead of the light absorbing agent 4-hydroxy-47-diethylaminoazobenzene, the same amount of the conventionally used 4-ethoxy-4'-diethylaminoazobenzene was added as a light absorbing agent. The resist pattern forming ability was examined by operating in exactly the same manner (Comparative Example 1).

In addition, a positive photoresist 0F that does not use any light absorbing agent.
Resist pattern forming ability was similarly investigated using PR-800 as a photosensitive composition (control example).

As a result, the exposure time (exposure amount) necessary for proper image formation was 3.6 seconds for the resist without adding a light absorber, and there was no problem in terms of sensitivity, but the resist image at the bottom of the step was There were many moth-eaten spots due to the effects of halation from the sides, and there were disconnections in the fine pattern areas.

Also, the pattern may become jagged due to the influence of standing waves.
Only line widths up to 1 μm could be resolved.

On the other hand, with the composition of Comparative Example 1, no effects of halation or standing waves were observed, resolution was achieved down to a line width of 0.5 μm, and the exposure amount required 9.5 seconds, resulting in a decrease in throughput. It is the cause.

Example 2 2,4-dihydroxy-4' instead of the light absorbing agent of Example 1
The procedure was carried out in exactly the same manner as in Example 1, except that -nitroazobenzene was used. As a result, the resist exposure time was 4.5
seconds, and no effects of halation or standing waves were observed yet.

Examples 3-6. Comparative Example 2 Four types of photosensitive compositions were prepared in which four types of light absorbers of the present invention shown in Table 1 were used instead of the light absorbent of Example 1, and for comparison, Oil Yellow 5S (4-diethylaminoazobenzene) was used. ) was prepared in the same manner as in Example 1, and the same operations were carried out to examine the pattern of turn formation in each resist.

The results are summarized in the table below, and the data of Examples 1 and 2 and Comparative Example 1 are also listed for reference. From the data in the table, it can be seen that the light absorbent according to the present invention is excellent for use in BON type photoresists.

Still, the light absorbent 4-hydroxy-4'-dimethylamine azobenzene (referred to as light absorbent A) according to the present invention used in Example 1 and the conventional light absorber 4 used in Comparative Example 1
-Ethoxy-4'-diethylaminoazobenzene (referred to as light-absorbing agent B) was used to determine the residual rate in the photoresist film over time during pre-baking as follows.

Using positive-type OFP, R-800 as a photoresist, a sample was prepared by applying a composition containing light absorber A to the substrate, and another sample was prepared in exactly the same manner using the same amount of light absorber B. Created. Both samples were then prebaked at a temperature of 80° C., and the amount of each light absorber in each photoresist film was quantified over time.

The attached drawing is a graph showing the relationship between the prebaking time (minutes) for each sample and the residual rate of the contained light absorbent in the photoresist film, with light absorbent A shown as a solid line and light absorbent B shown as a dotted line. There is.

As is clear from this figure, the light absorbent A according to the present invention shows a high residual rate, but the longer the prebaking time is, the longer the prebaking time is, the more the light absorbent A according to the present invention shows a high residual rate. rate decreases, and the effect of preventing no-ration declines. However, it can also be understood that the higher the pre-baking temperature, the lower the survival rate.

Example 7 A light absorbing agent O was added to a negative photoresist 0NNR-20 (trade name, manufactured by Tokyo Ohka Kogyo ■, solid content 12%) consisting of a polymer compound and a bisazide compound in an amount of 3% by weight of its resin content. A photosensitive composition was prepared.

This composition was applied to a silicon wafer with a step structure of 1 μm thick on which an aluminum layer of 0.5 μm thick was deposited.
The film was spin-coded to a film thickness of 1°0 μm, and prebaked at 100° C. for 30 minutes using a hot air circulation dryer to form a film. This film was exposed through a mask to Canon Mass Qualiner PI, A-500 (manufactured by Canon ■) for 8 seconds, and then a developer for 0NNR (
Product name: manufactured by Tokyo Ohka Kogyo ■) and rinsing liquid for 0NNR (
Patterning was performed by immersing each sample in a solution (trade name, manufactured by Tokyo Ohka Kogyo ■) for 1 minute each. The formed pattern was free from the effects of no-rations and standing waves, and was resolved to lines and spaces of 3 μm.

Comparative Example 3 Patterning was performed in exactly the same manner as in Example 7, except that no light absorbing agent was added and the exposure amount was set to 5 seconds. The observation result of this pattern is 4μm
Only lines and spaces could be resolved, and there were many jagged edges.

Example 8 Deep UV photo lettuce made by adding a sensitizer to polymethyl isopropenyl ketone polymer) A photosensitive composition was prepared by adding a light absorbing agent.

This composition was applied to a film thickness of 1.0 μm on an aluminum substrate with steps similar to those in Examples 1 to 7, and prebaked in a hot air dryer at 120° C. for 30 minutes. This film was exposed to light for 6 seconds through a mask using a tape UV fluoroscopic device Canon PLA-520 (manufactured by Canon ■) equipped with a cold mirror 290. Develop with 0DUR developer (trade name, manufactured by Tokyo Ohka Kogyo ■) at 23°C for 2 minutes using the immersion method 1. Rinse with ODU'R rinse solution (trade name, manufactured by Tokyo Ohka Kogyo ■) at 23°C for 1 minute. I did it. There are no chips (insect bites) or disconnections due to no-rations in the formed resist pattern or uneven tapering, and there are no jaggies or burrs due to the influence of standing waves, and the line width is resolved down to 0.5 μm. Ta.

Comparative Example 4 In Example 8, a photoresist pattern was formed in exactly the same manner as in Example 8 except that no light absorbing agent was added. However, many small jags were generated at line widths i and 0 μm, and the resolution was decreased. It is recognized that there is one.

[Brief explanation of the drawing]

The drawing is a graph showing the baking time and residual rate in the film during pre-baking of the photosensitive compositions of the present invention and comparative examples. Patent Applicant Tokyo Ohka Kogyo Co., Ltd. Agent Same Shape Clear Fiber Baking Color Shama (Min)

Claims (1)

[Claims] 1. A photoresist having a general formula [wherein R1 is a hydrogen atom or a hydroxyl group, R2 is a hydrogen atom,
is a nitro group or a di(lower alkyl)amine group] (in the formula, one of R3 and R4 is a hydroxyl group and the other is a hydrogen atom) or (in the formula, R5 is O) at least one selected from
A photosensitive composition characterized in that it contains a light absorbing agent of various types. 2. Claim 1, wherein the photoresist is a negative photoresist whose main components are a polymer compound and a bisazide compound, a positive photoresist whose main components are a novolak resin and at least one 0-quinone azide compound, or a deep UV resist. A photosensitive composition of the same name. 3. The photosensitive composition according to claim 1, characterized in that the light absorbing agent is present in an amount of 0.1 to 20% by weight based on the weight of the photoresist.