JPH061375B2 - Positive photoresist composition - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a positive photoresist composition. More specifically, the present invention relates to a positive photoresist composition having high resistance to oxygen plasma, which is suitable for manufacturing semiconductor devices and electronic parts.

2. Description of the Related Art In recent years, in the semiconductor industry, industrial computers,
Demand for office automation, personal computers, etc. has expanded dramatically, and the technology has continued to develop rapidly, and along with this, semiconductor integrated circuit devices have also rapidly increased in density and integration, Many proposals and ideas have been made regarding the manufacturing process. For example, in the manufacture of semiconductor integrated circuit devices, pattern formation on the order of submicrons is required. Therefore, photoresists used in the lithography process are also required.
In place of the negative photoresist, which was the mainstream until now,
High-resolution positive photoresists are becoming mainstream. Further, also in the pattern forming method using this positive type photoresist, a multi-layer resist method with high dimensional accuracy is often used. In particular, in a substrate in which circuits are multilayered by performing a plurality of lithography steps in order to obtain a high degree of integration, the surface has unevenness, and the multilayer resist is applied to a substrate having such an uneven surface. The method is an essential pattern forming method.

This multilayer resist method is a method of forming a positive photoresist layer on the uppermost layer, patterning this, and then sequentially transferring the pattern to a lower layer by a dry etching method to form a pattern with high dimensional accuracy on a substrate. By using the reactive ion etching method having a high anisotropy also in the dry etching, it is possible to obtain the one with higher dimensional accuracy.

Regarding such a multilayer resist method, a two-layer resist structure and a three-layer resist structure are known.
Generally, the former consists of a positive photoresist layer (upper layer) and an organic film layer (lower layer), and the latter has a metal thin film layer (intermediate layer) between the upper and lower layers of a two-layer resist structure. In this multi-layer resist method, whichever of two-layer resist structure or three-layer resist structure,
Although it has the same effect in that a pattern with high dimensional accuracy can be formed, a two-layer resist structure is naturally preferable in consideration of the working process.

However, in this two-layer resist structure, the organic film layer formed on the substrate for the purpose of flattening the surface of the substrate that normally has the uneven surface and the positive photoresist directly provided thereon are altered in their contact surfaces. In particular, the positive photoresist as the upper layer is required to have oxygen plasma resistance. As described above, the positive photoresist is required to have oxygen plasma resistance because the pattern formed by the positive photoresist is used as a mask when the lower organic film layer is etched by the dry etching method using oxygen gas. This is because it must have a function.

However, conventional positive photoresists generally do not have sufficient resistance to oxygen plasma, and when the lower organic film layer is dry-etched, the resist film to be used as a mask is also thinned, especially in the submicron order. The pattern formation has a drawback that the resist as a mask disappears before the etching of the organic film layer is completed.

Therefore, in order to cope with the recent tendency of pattern miniaturization, it is necessary to provide a metal thin film layer as an intermediate layer and use a three-layer resist structure having a complicated working process using the metal thin film layer as a mask. is the current situation.

On the other hand, the two-layer resist structure is effective as a pattern forming method with high dimensional accuracy, and the work process is easier than that of the three-layer resist structure. Therefore, if a positive photoresist having high oxygen plasma resistance is developed, the above problem can be solved. Therefore, in the semiconductor industry, development of a positive photoresist having high oxygen plasma resistance that can be used for this two-layer resist structure is developed. Is an important issue.

Furthermore, in the production of semiconductor elements and electronic parts, imide-based resins have advantages such as heat resistance and chemical stability.
It is often used as a protective film or an interlayer insulating film. There has been a long-felt need for a positive photoresist having a high oxygen plasma resistance as a mask material when patterning this imide resin film.

As a positive photoresist that meets such a demand, a photoresist based on a polymer having a trimethylsilyl group introduced in its molecule has been reported [eg, "1984 Inte
rnational symposium on Electron, Ion and Photon Bea
ns, Tarrytown, NY 1984 "," J. Electrochem.Soc ", Vol. 132, p. 909 (1985)].

However, such polymers are extremely difficult to produce and have drawbacks such as poor storage stability, and have not been industrially used.

Problems to be Solved by the Invention Under such circumstances, the object of the present invention is to positive type, which is suitable for manufacturing semiconductor elements and electronic parts, has high resistance to oxygen plasma, and is industrially applicable. It is to provide a photoresist composition.

Means for Solving the Problems As a result of intensive studies by the present inventors, a composition containing a mixture of a specific silicon-containing phenol and a novolac resin and a quinonediazide group-containing compound was found to meet the above-mentioned object. Based on this finding, the present invention has been completed.

That is, the present invention is the general formula (A) [Wherein R ₁ is a trialkylsilyl group, a dialkylvinylsilyl group, an alkyldivinylsilyl group, a dialkylarylsilyl group, an alkyldiarylsilyl group, a triarylsilyl group, a dialkylhydroxyarylsilyl group or a trialkylsiloxy group, R ₂ Is a hydrogen atom, a hydroxyl group, an alkyl group, an alkoxy group or a trialkylsilyl group, A is a formula Or (However, m is an integer of 1 to 6),
n is 0 or 1] and a mixture of a silicon-containing phenol and a novolak resin, and (B) a quinonediazide compound are contained in the positive photoresist composition.

In the composition of the present invention, the general formula (I) as the component (A)
It is necessary to use a mixture of the silicon-containing phenols represented by and a novolac resin.

Examples of the silicon-containing phenols represented by the general formula (I) include trimethylsilylphenol, tri (trimethylsiloxy) silylphenol, dimethyldi (4-
Hydroxyphenyl) silane, trimethylsilylpropylphenol, trimethylsilylmethoxyphenol,
Trimethylsilyl propoxyphenol, 2-methyl-
Examples thereof include 3- (trimethylsilylmethoxy) phenol and trimethylsiloxydimethylsilylphenol.

These silicon-containing phenols such as p-trimethylsilylphenol are protected by reacting the hydroxyl group of p-chlorophenol with a trimethylsilylating agent, and then hydrolyzing the product obtained by reacting trimethylchlorosilane with a Grignard reagent. It can be obtained by distillation and purification.

On the other hand, the novolak resin mixed with the above-mentioned silicon-containing phenols is formed by condensing phenol, lower alkylphenol, dihydroxybenzene or a mixture thereof with formaldehyde, and as such, for example, phenol novolac resin, Examples thereof include cresol novolac resin and novolac resin obtained by condensing a mixture of tert-butylphenol and phenol with formaldehyde.

In the composition of the present invention, the mixing ratio of the silicon-containing phenols and the novolac resin is preferably 1: 1 to 1:10, and more preferably 1: 2 to 1: 7 by weight.

In the composition of the present invention, as the quinonediazide group-containing compound used as the component (B), for example, orthobenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide, a compound having a sulfonic acid of a quinonediazide and a phenolic hydroxyl group or an amino group Partial or complete esterification, or partial or complete sulfonamide formation.

Examples of the compound having a phenolic hydroxyl group or an amino group include 2,3,4-trihydroxybenzophenone and 2,
Polyhydroxybenzophenone such as 2 ′, 4,4′-tetrahydroxybenzophenone, alkyl gallate, aryl gallate, phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A, naphthol, pyrocatechol, Pyrogallol, Pyrogallol monomethyl ether, Pyrogallol
1,3-dimethyl ether, gallic acid, esterified or etherified gallic acid leaving some hydroxyl groups, aniline, p
-Aminodiphenylamine and the like.

The mixing ratio of the mixture of the silicon-containing phenols of the component (A) and the novolac resin and the quinonediazide group-containing compound of the component (B) is 100 parts by weight of the component (A) with respect to 10 parts by weight of the component (B). It is selected in the range such that it is not more than 55 parts by weight, preferably not more than 55 parts by weight. When the component (A) exceeds 100 parts by weight,
The fidelity of the mask pattern of the obtained image is inferior and the transferability is reduced.

The composition of the present invention is advantageously used in the form of a solution by dissolving the silicon-containing phenols, the novolac resin and the quinonediazide group-containing compound in a suitable solvent.

Examples of such a solvent include acetone, methyl ethyl ketone, cyclohexanone, isoamyl ketone and other ketones: ethylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or Mention may be made of polyhydric alcohols such as monophenyl ether and its derivatives: cyclic ethers such as dioxane: and esters such as methyl acetate, ethyl acetate and butyl acetate. These may be used alone or in combination of two or more.

The positive photoresist composition of the present invention may further contain compatible additives such as a sensitizer, an additional resin, a plasticizer, a stabilizer or a coloring agent for making the developed image more visible. A commonly used one may be added and contained.

The material to be etched that is etched by performing the dry etching treatment using the composition of the present invention as a mask is not particularly limited as long as it can be dry-etched by oxygen plasma, and almost any organic material can be used. Specific examples include organic photoresists, polymethyl methacrylate, copolymers of methyl methacrylate and methacrylic acid, and imide resins used as the lower layer of a two-layer resist structure.

One example of a suitable method of using the composition of the present invention is:
First, a solution of the composition is applied onto an object to be etched by a spinner or the like, and after drying, a quinonediazide supply-containing compound is exposed to light, and active light suitable for solubilization, for example, a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, Actinic rays using an arc lamp, a xenon lamp, or the like as a light source are selectively irradiated through a desired mask, or are irradiated while scanning an electron beam. Then, the portion solubilized by exposure is dissolved and removed with a developing solution, for example, an alkaline aqueous solution such as a 1-2 wt% sodium hydroxide aqueous solution, a tetramethylammonium hydroxide aqueous solution, and a trimethyl (2-hydroxyethyl) ammonium hydroxide aqueous solution. Thus, a resist pattern is formed on the object to be etched. Next, the exposed object to be etched is dry-etched by oxygen gas, for example, by a plasma etching method, a reactive ion etching method, or the like, whereby a pattern faithful to the mask pattern can be obtained.

EFFECT OF THE INVENTION The positive photoresist composition of the present invention has a higher resistance to oxygen plasma than conventional ones by using a silicon-containing phenol, and thus is extremely useful as a mask for dry etching using oxygen gas. It is useful, and by using it as an upper layer of a multi-layer resist method having a two-layer resist structure which is particularly effective for obtaining a pattern with high dimensional accuracy, it is easy to form a submicron-order fine pattern, and further, an imide resin. It can be used as a masking material for almost all organic films such as films.

EXAMPLES Next, the present invention will be described in more detail by way of examples.

Example 1 25 parts by weight of p-trimethylsilylphenol, 75 parts by weight of phenol novolac resin, and 25 parts by weight of an ester condensate of 1.6 mol of naphthoquinonediazide-5-sulfonic acid and 1 mol of 2,3,4-trihydroxybenzophenone,
Ethylene glycol monoethyl ether acetate 300
After being dissolved in parts by weight, it was filtered using a membrane filter having 0.2 μm pores to prepare a coating solution of a positive photoresist composition.

Then, this coating solution was applied onto a 3-inch silicon wafer by a TR-4000 type resist coater (manufactured by Tatsumo Co., Ltd.) at 1.3.
It was evenly applied to a film thickness of μm and dried on a hot plate at 110 ° C. for 90 seconds. Next, reduction projection exposure system 1505G3
2.38% by weight after UV exposure through a test chart using A type wafer stepper (manufactured by Nihon Kogaku)
With an aqueous solution of tetramethylammonium hydroxide,
It was developed at 23 ° C. for 30 seconds. Then, the obtained resist pattern film is used as an OA which is a parallel plate type plasma etching device.
Using PM-400 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), pressure is 10 mTor
When reactive on etching was performed under the conditions of r, oxygen gas flow rate of 10 cc / min, RF output of 50 W, and processing temperature of 25 ° C., the amount of resist film reduction was 22 nm per minute.

Examples 2 to 7 and Comparative Examples 1 to 3 A positive photoresist having a composition as shown in the table in the same manner as in Example 1 using silicon-containing phenols, novolac resins and quinonediazide group-containing compounds as shown in the attached table. A coating solution of the composition was prepared, and the amount of resist film reduction due to dry etching treatment using oxygen gas was determined per minute.

In addition, a coating solution of a positive photoresist composition using a conventional novolac resin was prepared, and the film thickness reduction of the resist was determined in the same manner (Comparative Examples 1 to 3).

The results are shown in the table.

From this table, it can be seen that the positive photoresist composition of the present invention has approximately 10 times the oxygen plasma resistance as compared with the conventional one.

Example 8 A cresol novolak resin and naphthoquinone diazide-5-sulfonic acid were added to a 2,3-, 4-, 4-, silicon wafer on which aluminum having a step of 1.0 μm was vapor-deposited using a TR-4000 type resist coater (manufactured by Tatsumo Co., Ltd.). For the solid component of OFPR-800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), which is a positive photoresist containing an ester condensate with 4-trihydroxybenzophenone, pN, N-dimethylamino-p '
After applying 5% by weight of ethoxyazobenzene as an absorber to a thickness of 2.0 μm, it is dried at 110 ° C. for 90 seconds and then 5 kW with a strength of 185 mW / cm ^{2 at} 365 nm.
The whole surface was irradiated with ultraviolet rays for 2 minutes by the ultra-high pressure mercury lamp. Then, a coating solution of the positive photoresist used in Example 1 was applied thereon to a film thickness of 1.3 μm by the resist coater and developed in the same manner as in Example 1, and then the exposed lower layer resist was used in Example. When dry etching was performed under the same conditions as in No. 1, the etching was completed in 20 minutes, and a pattern having a line width of 0.7 μm and having good linearity perpendicular to the substrate was obtained.
In that case, the amount of film loss of the upper layer resist is 23 nm per minute.
Met.

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-60-43651 (JP, A) JP-A-59-68795 (JP, A)

Claims (1)

[Claims] 1. A general formula (A) [Wherein R ₁ is a trialkylsilyl group, a dialkylvinylsilyl group, an alkyldivinylsilyl group, a dialkylarylsilyl group, an alkyldiarylsilyl group, a triarylsilyl group, a dialkylhydroxyarylsilyl group or a trialkylsiloxy group, R ₂ Is a hydrogen atom, a hydroxyl group, an alkyl group, an alkoxy group or a trialkylsilyl group, A is a formula Or (Wherein m is an integer of 1 to 6), n is 0 or 1], and a mixture of a silicon-containing phenol and a novolac resin, and (B) a quinonediazide compound. A positive photoresist composition comprising