JPH01293337A - Negative type photoresist composition - Google Patents

Abstract

PURPOSE:To improve definition and sensitivity by forming the above compsn. of a polymer consisting of a specific repeating unit, or a copolymer contg. said repeating unit, a compd. contg. an azide group, and a solvent. CONSTITUTION:This compsn. consists of the polymer consisting of the repeating unit expressed by the formula I, the copolymer contg. said repeating unit, the compd. contg. the azide group, and the solvent. The alkaline soluble polymer is a polymer contg. a hexafluoro-2-hydroxyl propyl group or is more specifically a p-(hexafluoro-2-hydroxyl propyl)styrene (HFS) polymer or a copolymer (HFS copolymer) of the HFS and other vinyl monomer. The compd. contg. the azide group is preferably a arom. azide compd. contg. at least >=1 azide groups in one molecule. The definition and sensitivity are thereby improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a resist material suitable for forming fine patterns applied to the manufacture of semiconductor integrated circuits, magnetic bubble memory elements, etc. A deep ultraviolet and excimer laser consisting of a crosslinking agent containing azide.
The present invention relates to a negative photoresist composition that has high sensitivity, high resolution, and high dry etch resistance and is suitable for lithography.

[Prior art and problems to be solved by the invention] Conventionally,
Negative photoresist compositions based on cyclized rubber and containing bisazide compounds are well known and are still widely used in the manufacture of semiconductor integrated circuits and the like. As the cyclized rubber, cyclized polyisoprene or cyclized polybutadiene, which is obtained by partially cyclizing polyisoprene or polybutadiene under an acidic catalyst, is used, and as a bisazide compound, 2
．． 6-bis(4'-azidobenzal)-4-methylcyclohexanone and the like are used. In these compositions,
The azide group is decomposed by light irradiation and active nitrene is generated. This nitrene reacts with the double bonds remaining in the cyclized rubber, crosslinks the cyclized rubber, and turns it into a polymer. After exposure, unexposed areas are removed by developing with an organic solvent to form a negative pattern.

In addition, halogenated polystyrene-based negative photoresist compositions are also well known, and many compositions have been published. For example, iodinated polystyrene, chloromethylated polystyrene, chlorinated polyvinyltoluene, etc. are known. These polystyrene resists are polymerized by the generation of halogen radicals by light irradiation and the resulting crosslinking of the polymer by the carbon radicals in the polymer chains. After exposure, unexposed areas are removed by developing with an organic solvent to form a negative pattern.

However, these resists have several problems when attempting to form a pattern of 1 micron or less, and their use is limited. These problems include insufficient pattern resolution, low heat resistance, and low sensitivity. In particular, the lack of resolution is significant, and there is a large difference from the resolution required for current resists. The reason for this is that the exposed area swells in the organic solvent developer.

Additionally, organic solvent developers are environmentally and health-hazardous;
It is also unfavorable in terms of flammability.

Therefore, an object of the present invention is to provide a negative resist composition that has high resolution and high sensitivity and is developable in an alkaline solution.

[Means for Solving the Problems] In view of the above circumstances, the inventors of the present invention have made extensive studies and found that a composition comprising an alkali-soluble polymer and an azide compound is a negative solution that achieves the above object. The present inventors have discovered that the present invention can be used as a type photoresist composition, and have completed the present invention.

That is, the present invention relates to a negative photoresist composition comprising a polymer comprising repeating unit [1] or a copolymer containing repeating unit [1], a compound containing an azide group, and a solvent.

H The negative photoresist composition of the present invention will be described in detail below.

The alkali-soluble polymer used in the present invention is a polymer containing a hexafluoro-2-hydroxylpropyl group, more specifically a p-(hexafluoro-2-hydroxylpropyl) styrene (hereinafter referred to as HFS) polymer or HFS. It is a copolymer with other vinyl monomers (hereinafter referred to as HFS copolymer).

The hydroxyl hydrogen atom in the hexafluoro-2-hydroxylpropyl group has a greater dissociative ability than a normal hydroxyl group due to the electron-withdrawing properties of the two trifluoromethyl groups bonded to adjacent carbon atoms. Ori,
Its bond-dissociation constant is comparable to that of phenol. Therefore, a polymer containing a hexafluoro-2-hydroxylpropyl group has an alkali solubility comparable to that of polyvinylphenol.

p-(hexafluoro-2-hydroxylpropyl)styrene used in the present invention can be produced from p-chlorostyrene and hexafluoroacetone using a Grignxrd reaction.

Other vinyl monomers for the HFS copolymer used in the present invention can be used as long as they are copolymerizable with HFS. Specifically, styrene monomers such as styrene, chlorostyrene, chloromethylstyrene, vinyltoluene, α-methylstyrene, and vinylphenol, acrylic acid,
Acrylic acid monomers such as acrylic acid, methyl, methacrylic acid, methyl methacrylate, phenyl methacrylate,
Further, vinyl acetate monomers such as vinyl acetate and vinyl benzoate can be mentioned. HF in HFS copolymer
The ratio of S to the above monomer is preferably HFS of 50% or more. If the proportion of HFS is less than 50%, it will have an adverse effect on developability.

These HFS polymers and HFS copolymers can have a weight average molecular weight of 1.000 to 50.000, but
Preferably it is 2.000 to 20.000. If it deviates from the above range, resolution, developability, and coating properties will be adversely affected.

The compound containing an azide group used in the present invention is preferably an aromatic azide compound containing at least one azide group in one molecule, and specifically, 4-azidobenzalacetophenone, 4-azidobenza Zaruacetone, 2.6-
Bis(4'-azidobenzal)cyclohexanone, 4.
Examples include, but are not limited to, 4'-diazidiphenylmethane, 4,4'-diazidiphenylmeether, and 3,3'-diazidiphenyl sulfone. In addition, these compounds can be used alone,
Alternatively, two or more types can be used in combination.

The proportion of the compound containing an azide group in the composition of the present invention is preferably 1 to 10 parts by weight based on 100 parts by weight of the HFS polymer and HFS copolymer.

If the amount of the compound containing an azide group is less than 1 part by weight, the sensitivity will be insufficient, while if it is more than 10 parts by weight, there will be no further effect and it will be uneconomical.

The negative photoresist composition according to the present invention is soluble in organic solvents, and when used in the production of integrated circuits, it is usually put to practical use in the form of a solution (resist solution). In this case, the composition is generally prepared by dissolving it in an organic solvent in a proportion of 1 to 50% by weight, preferably 5 to 30% by weight.

In this case, the solvent to be used is one that uniformly dissolves each constituent component of the negative photoresist composition of the present invention, coats it on the surface of a substrate such as silicon or aluminum, and then evaporates the organic solvent to form a uniform and smooth surface. Those from which a coating film can be obtained are preferred. Specifically, ketone solvents such as methyl ethyl ketone, cyclopentanone, and cyclohexanone, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether,
Examples include, but are not limited to, ester solvents such as ethylene glycol monoethyl ester and ethylene glycol monomethyl acetate.

The above organic solvents may be used alone or in combination of two or more.

In addition to the above-mentioned components, a sensitizer, a dye, an adhesion improver, etc. can be added to the negative photoresist composition of the present invention, if necessary. With the negative photoresist composition of the present invention, a relief pattern can be formed by conventional photoresist techniques by adjusting the resist solution as described above. The method for forming this relief pattern will be explained below.

(1) The resist solution prepared as described above is applied to a substrate to form a resist film with a thickness of 1 to 1.5 μm. This application to the substrate can be performed using, for example, a spinner.

(2) The temperature of the substrate is 60 to 120°C, preferably 80 to 9°C.
Dry at 0°C for 20 to 60 minutes. (Pre-bake) (3) This coating film is irradiated with deep ultraviolet rays or excimer laser through a photomask chart.

(4) A relief pattern is obtained by washing out the unexposed areas with a developer. As a developer, sodium hydroxide,
For example, a weak alkaline aqueous solution of potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide, etc. having a concentration of 10% by weight or less can be used.

(5) Develop the phosphor base at a temperature of 80 to 130°C, preferably 9°C.
Dry at 0-120°C for 20-60 minutes. (Bost bake) The relief pattern thus formed has a resolution of 1 μm or less and has good sensitivity.

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

(Production Example 1) After adding 7 g of magnesium to a 2001 Sanro flask and replacing the inside of the reactor with nitrogen, 5 g of p-chlorostyrene and 2 ml of ethyl bromide were dissolved in tetrahydrofuran (THF).
Added 20ml. Next, without stirring, a solution of 25 g of p-chlorostyrene dissolved in 100 m, 1 of THF was slowly added dropwise while maintaining the reaction temperature at 35°C.

After the dropwise addition was completed, the mixture was refluxed for 1 hour.

Thereafter, hexafluoroacetone was introduced into the reaction solution over a period of 4 hours. After the reaction was completed, the reaction mixture was poured into 1000ml of ice water to obtain a precipitate. This precipitate was washed with a 5% aqueous hydrochloric acid solution, a 10% aqueous sodium hydroxide solution, and a 5% aqueous hydrochloric acid solution in this order, dried, and then distilled under reduced pressure to obtain p-(hexafluoro-2-hydroxylpropyl)styrene.

5 g of the obtained p-(hexafluoro-2-hydroxylpropyl)styrene was added to benzene Ihl, and 0.0 g of azobisisobutyronitrile (A I BN) was added thereto. Olg
was added, and then reacted at 50°C for 40 hours.

After the reaction was completed, the reaction mixture was poured into 1001 methanol to obtain a polymer. The obtained polymer was mixed with benzene.
Precipitation purification was performed twice using a methanol system, and a recovery rate of 70% was obtained. The weight average molecular weight of the polymer was determined to be 7300 by gel permeation chromatography (GPC).

(Production Example 2) 5 g of p-(hexafluoro-2-hydroxylpropyl) styrene obtained in Production Example 1 and 2 g of styrene were added to 10 ml of benzene, and azobisisobutyronitrile (AIBN) Q, After adding Olg, the mixture was reacted at 50°C for 40 hours. After the reaction was completed, purification was performed in the same manner as in Production Example 1. The weight average molecular weight of the polymer was gsoo. The proportion of HFS in the polymer was determined to be 70 mol% by elemental analysis.

(Example 1) 3 g of the HFS polymer obtained in Production Example 1 and 0.15 g of 3.3'-diazidodiphenylsulfone were dissolved in 15 ml of ethyl cellosolve acetate to prepare a resist solution.

This resist solution was mixed with hexamethylene disilazane (HMD).
S) Using a spin coater on a silicon wafer spin-coded with 1.0011 at 2000 rpm/60 seconds,
Spin code was 00Q+9111/60 seconds. This wafer was prebaked in an oven at 80°C for 30 minutes to obtain a coating film of 1 μm.Then, the coating film was passed through a patterned chrome mask and CM was applied using a contact aligner PLA-521F manufactured by C Cannon. -25
Deep ultraviolet light exposure was performed using a zero mirror. After exposure, development was performed for 1 minute with a 1.5% aqueous solution of tetramethylammonium hydroxide to dissolve the unexposed areas and obtain a pattern. Further, a characteristic curve of irradiation amount and residual film rate was obtained by performing a post bake at 100° C. for 30 minutes and measuring the film thickness, and a sensitivity of 36 m j /cut (254 am) was obtained. Further, as a result of observing the formed pattern with an electron microscope, it was found that a rectangular fine pattern of 0.75 μm was well resolved.

(Example 2) The same procedure as in Example 1 was carried out except that the HFS copolymer obtained in Production Example 2 was used instead of the HFS polymer.

A sensitivity of 59 m j /ad (254 nm) was obtained, and a fine pattern of 1.75 μm could be resolved.

(Effects of the Invention) As explained above, the negative photoresist composition of the present invention has high sensitivity in the exposure range of deep ultraviolet rays and wavelengths associated with excimer laser sources. Moreover, since it can be developed with an alkaline aqueous solution, there is no risk of swelling.
It is possible to form fine photoresist patterns with high precision. Therefore, these compositions are suitable for IC and L
It can be used as a resist for manufacturing integrated circuits such as SI.

Claims (1)

[Scope of Claims] 1. A negative photoresist composition comprising a polymer consisting of repeating unit [1] or a copolymer containing repeating unit [1], a compound containing an azide group, and a solvent. thing. ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ [1]