JPH0446344A - Negative photosensitive composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates generally to negative-tone photosensitive compositions that are sensitive to radiation, and more particularly to negative-tone photoresists for making semiconductor integrated circuits. It is.

[Conventional technology]

It is generally said that the integration of semiconductor integrated circuits is increasing at a rate of four times every three years.For example, if we take dynamic random access memory as an example, it is now
A device with a storage capacity of M bits is in full-scale production.

Requirements for photolithography technology, which is essential for the production of integrated circuits, are becoming stricter year by year.

For example, 0.8 μm level lithography technology is required to produce 4M bit DRAM, and 0.5 μm and 0.3 μm level lithography technology is required for 16M and 64M DRAMs, which have become even more highly integrated. It is expected that Therefore, there has been a strong desire to develop a resist that can be used in half-micron lithography.

As a resist used in photolithography, a negative resist using cyclized rubber and bisazide as a crosslinking agent is well known. However, since this system requires an organic solvent for development, swelling occurs during development, and the image resolution is limited to about 3 μm, making it unsuitable for manufacturing highly integrated devices. Furthermore, organic solvents used for development have many problems in terms of environment, health, and flammability.

Furthermore, positive resists made of naphthoquinonediazide and alkali-soluble novolac resins are also well known. However, this system has a drawback that there is large absorption at wavelengths below 300 nm, and the pattern profile deteriorates significantly when short wavelength exposure is performed. Therefore, exposure has to be carried out at a wavelength of about 350 nm or more, which limits the resolution and makes it impossible to support half-micron lithography.

On the other hand, X-ray lithography and electron beam lithography are candidates for high-resolution carisogelaphy, but the former is lagging behind in terms of hardware and resist, while the latter is not compatible with mass production in terms of throughput. Can not.

Therefore, at present, in order to obtain higher resolution, it is necessary to expose using light in the deep UV g range using a light source such as a low-pressure mercury lamp or excimer laser, and also to have a pattern profile that is suitable for half-micron lithography. The development of resists is strongly desired.

[Problem to be solved by the invention]

As mentioned above, a resist that does not swell during development and has low absorption in the deep UV region is essential for half-micron resists, and conventional cyclized rubber resists and naphthoquinonediazide-novolac resists are None of them satisfy these two conditions.

An object of the present invention is to solve the problems of the prior art and to develop a resist that can be exposed using light in the deep UV 95 range and has a good pattern profile that can be used in half-micron lithography.

[Means to solve the problem]

As a result of various studies to achieve the above object, the present inventors developed a resist composition containing a combination of an alkali-soluble resin, a specific photoacid generator, and a crosslinking agent with alkaline water after exposure. It was found that this is a high-performance negative photoresist composition that can obtain a non-swelling, high-resolution pattern profile.

The present invention was completed based on this knowledge, and the gist thereof is to provide a negative photosensitive composition containing an alkali-soluble resin, a photoacid generator, and a crosslinking agent for the alkali-soluble resin that acts under acidic conditions. , the photoacid generator has the formula [
A negative photosensitive composition characterized by being an oxadiazole derivative represented by I].

[In the formula, X represents an alkyl group, an alkenyl group, or an aromatic group which may have a substituent.] This example will be described in detail below.

The alkali-soluble resin used in the present invention is not particularly limited, but preferably has a phenolic hydroxyl group, and particularly has an exposure wavelength in the range of 150 to 300 nm at which the transmittance at a film thickness of 1 micron is 20% or more. Examples of such resins, which are preferably
Examples include novolak resin, polyvinylphenol, N-(p-hydroxyphenyl)maleimide polymer, and the like.

The crosslinking agent is not particularly limited as long as it is a compound that undergoes a crosslinking reaction with an alkali-soluble resin in the presence of an acid, but preferably JP-A-59-113435 and JP-A-60-26 are used.
Compounds cited in No. 3143 and JP-A-62-164045, A, knop, L, A, Pilat
Examples include compounds described in Phenolic Reins, written by John O. Particularly preferably, specifically, RIOC
H.

NHCONHCH,OR"(R' and R" each independently represent a hydrogen atom or an alkyl group) or 01 to 01 to ethyl group, linear or branched propyl group, butyl group, pentyl group, hexyl group, etc. Examples of C1 alkyl groups and alkenyl groups include compounds represented by C3 to C1 alkenyl groups such as vinyl, allyl, and crotyl groups, and R4 each independently represents a hydrogen atom or an alkyl group.

In addition, the carbon number of the alkyl group represented by R1 and R4 is 1 to
It is about 4.

The present invention is particularly characterized in that a trichloromethyl group-containing oxadiazole derivative represented by the following formula [I] is used as a photoacid generator.

These groups may be substituted with a nitro group, a cyano group, a halogen atom, a lower alkyl group, a lower alkoxy group, a phenyl group, or the like.

Specific examples of the substituent represented by X include (wherein, X is an alkyl group, an alkenyl group, which may have a substituent,
It is an aromatic group. ) As the alkyl group represented by χ, methyl group, CHx-CJs, CJt, CaH*
, CHz-CH-The ratio of the alkali-soluble resin, acid generator, and crosslinking agent in the photoresist composition of the present invention is 0.05 to 20 parts by weight, preferably 0 parts by weight, of the acid generator per 100 parts by weight of the alkali-soluble resin. The crosslinking agent is used in an amount of 1 to 50 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight of the alkali-soluble resin.

The composition of the present invention is usually used after being dissolved in a solvent, but the solvent is not particularly limited as long as it has sufficient solubility for the resin and photosensitizer and provides good coating properties.
For example, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ester solvents such as butyl acetate, amyl acetate, methyl lactate, and ethyl lactate, and highly polar solvents such as dimethylformamide and N-methylpyrrolidone. Examples include solvents, mixed solvents thereof, and mixed solvents to which aromatic hydrocarbons are added. The proportion of the solvent used is in the range of 1 to 20 times the total amount of solid content as a weight ratio.

The negative photosensitive composition of the present invention is used as a photoresist after passing through the steps of coating, exposure, post-exposure baking (FEB), and development as described below.

A spin coater is usually used for coating, and the appropriate film thickness is about 0.5 microns to 2 microns.

For exposure, light in the deep UV Ql region, for example, 254 nm light from a low-pressure mercury lamp as a light source, or 157 nm, 193 nm, 222 nm light from an excimer laser or the like as a light source is used.
nm, 249 nm light is preferably used. The light during exposure may be broad rather than monochromatic.

The post-exposure heating (FEB) is preferably performed using a hot plate at 90 to 140° C. for about 1 minute to 10 minutes. A convection covered oven may be used instead of a hot plate, which typically requires a longer time than using a hot plate.

The developing solution includes inorganic alkalis such as potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, primary amines such as ethylamine and n-propylamine, diethylamine, di-n-
Secondary amines such as propylamine, triethylamine,
An alkaline developer comprising an aqueous solution of a tertiary amine such as trimethylamine or a quaternary ammonium salt such as tetramethylammonium hydroxide or trimethylhydroxyethylammonium hydroxide is preferably used.

Alcohol, surfactant, etc. may be added to the developer as necessary.

Note that the photoresist solution and developer are used after being filtered to remove insoluble components.

The negative photosensitive composition of the present invention can be used as a photoresist for producing VLSI wiring, a solder resist, image formation such as relief images or image duplication, photocuring ink, paint, etc.
Can be used for adhesives, etc.

〔Example〕

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

Example 1 A mixture of 142.5 g (1,32 mol) of m-cresol, 190.0 g (1,76 mol) of p-cresol, and 161.0 g (1,29 mol) of 2,5-xylenol was prepared at 37% by weight. 276.3 g of formalin solution (3.4 mol as formaldehyde) and 10.0 g of oxalic acid (0,0
79 mol) as a catalyst at 91 to 94°C to obtain 414 g of novolak resin (Mw = 6700, transmittance at exposure wavelength 248 nm: 35%) On the other hand, a compound represented by the following formula (n) was It was synthesized according to the method of

6.8 g (0,051 of) acetophenone and 20 g of 80% hydrophobic hydrazine were heated at 100° C. for 2 hours, cooled, diluted with water, and mixed to obtain a compound represented by the following formula.

Mix 1.52 g (0,011 sol) of the compound and 3.09 g (0,01 mol) of trichloroacetic anhydride, 3
After stirring for an hour POCj! 7.5 g of S was added and refluxed for 3 hours. After cooling, drop into ice water, pour through mouth, ethanol,
The compound represented by the above formula (n) was obtained by recrystallization from a mixed solution of water and water.

30 g of the above novolak resin, 6 g of the compound represented by the following formula [■], and 0.4 g of the compound represented by the above formula (II)
g was dissolved in ethyl lactate OOg and microfiltered using a 0.2 micron Teflon filter paper to prepare a photoresist composition. This photoresist composition was coated onto a 4-inch diameter silicon wafer to a thickness of 1.0 microns using a spin coating device (Mikasa 1H-2D), and dried in an oven at 90°C for 30 minutes. . This was placed in close contact with a photomask (manufactured by Toppan Printing), exposed for 60 seconds using a 6W low-pressure mercury lamp (manufactured by Ushio Inc.), and then heated in an oven at 90"C for 130 minutes (FEB).
Then, a negative image was formed by developing with a 2.38% tetrahydroxyammonium hydride solution for 60 seconds. When the obtained resist pattern was observed with a scanning electron microscope (manufactured by Akashi Seisakusho), lines and spaces of 0.5 microns were resolved.

Example 2 A photoresist composition was prepared and evaluated in the same manner as in Example 1, except that 4 g of dimethylol urea was used in place of the compound represented by formula (III) as the crosslinking agent in Example 1. 0.5 micron lines and spaces were resolved.

Comparative Example 1 17.2 g (70 mmol) of 2.3.4.4'-tetrahydroxybenzophenone and 56.4 g (210 mmol) of 1,2-naphthoquinonediazide-5-sulfonyl chloride
mmol) in a mixed solvent of dioxane/N-methylpyrrolidone in the presence of triethylamine to synthesize a photosensitizer. 0.063 g of this photosensitizer and 1.00 g of the novolac resin used in Example 1 were mixed with 4.0 g of ethyl lactate.
and N-methylpyrrolidone 0.5g in a mixed solvent,
Microfiltration using 0.2 micron Teflon filter paper,
A photoresist composition was prepared. This photoresist composition was coated on a silicon wafer with a diameter of 4 inches using a spin coating device (Mikasa IH-2D).1.
Coated to a thickness of 0 microns and placed in an oven at 90℃ for 30 minutes.
Dry for a minute. This was placed in close contact with a photomask (manufactured by Toppan Printing), and using a 6W low-pressure mercury lamp (manufactured by Ushio Inc.),
Exposure was carried out for 600 seconds.

A positive image was formed by developing with the 12.38% tetrahydroxyammonium hydride solution for 60 seconds. The obtained resist pattern was examined using a scanning electron microscope (
When observed with Akashi Seisakusho), there is a 0°8 micron line &
Only space was resolved.

Comparative Example 2 A photoresist composition was prepared in the same manner as in Example 1, except that 0.4 g of a compound represented by the following formula (IV) was used as a photoacid generator in place of the compound represented by formula (n). When prepared and evaluated, a good image was not formed due to insufficient exposure. In the case of sufficient exposure, lines and spaces of 0.5 microns were resolved, but in that case, exposure for 3 minutes or more was required, that is, only a resist with low sensitivity was obtained.

〔Effect of the invention〕

The negative photosensitive composition of the present invention is a highly sensitive resist composition, and by exposing it to light with a wavelength in the deep UV g range, high resolution lithography is possible in an extremely short exposure time. This is extremely useful.

(Voluntary) Procedural Dispute Report Month 6, 1991 1 Display of incident 1990 Patent Application No. 155649 2 Name of the invention Negative photosensitive composition 3 Person making the amendment

Claims (1)

[Claims] (1) In a negative photosensitive composition containing an alkali-soluble resin, a photoacid generator, and a crosslinking agent for the alkali-soluble resin that acts under acidic conditions, the photoacid generator has the formula [I]
A negative photosensitive composition characterized by being an oxadiazole derivative represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼... [I] [In the formula, X represents an alkyl group, an alkenyl group, or an aromatic group that may have a substituent. ]