JPS61198151A - Positive type photoresist composition - Google Patents

Abstract

PURPOSE:To improve the dry etching resistance by adding a naphthoquinonediazido sensitizer and novolak resin obtd. by condensing aldehydes with a mixture of at least one between m-cresol and p-cresol with a specified organosilicic compound. CONSTITUTION:This positive type photoresist composition contains a naphthoquinonediazido sensitizer and novolak resin obtd. by condensing aldehydes with a mixture of at least one between m-cresol and p-cresol with an organosilicic compound represented by the formula (where each of R<1>-R<3> is alkyl or aryl, and each of R<4>-R<7> is H, alkyl or phenyl). The ester of 1,2- naphthoquinonediazido-5-sulfonic acid with a compound having a phenolic hydrox yl group is used as the naphthoquinonediazido sensitizer. The novolak resin has preferably 1,000-30,000 weight average mol.wt. (expressed in terms of styrene) measured by gel permeation chromatography.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positive photoresist composition sensitive to radiation, and more particularly, a composition comprising a mixture of a specific organosilicon compound and metacresol or paracresol. The present invention relates to a positive photoresist composition containing a novolac resin obtained by condensation with an aldehyde and a naphthoquinone diazide photosensitizer.

[Conventional technology]

The integration of semiconductor integrated circuits is progressing at an accelerated pace year by year, and we are currently transitioning from the so-called LEjX era to the era of ultra-LSIs. Along with this, a photolithography technique with finer patterns has been required. In response to such demands, 7-toquinonediazide-based positive photoresists have come to be frequently used in photolithography.

[Problem that the invention seeks to solve]

However, dry etching resistance is not necessarily sufficient in conventional positive type photoresists using quinone diazide yarns using cresol novolac resins, vinyl phenol polymers, etc. as binder resins.

In addition, with the miniaturization of Ringer-Raffi patterns, the resolution of the resist is required to be in the range of 1 μm to 1 μm, and even in the form of submicron patterns.

Furthermore, on extremely uneven surfaces such as the top of a super LSI
As a technique for drawing level or submicron patterns, a non-photosensitive resin is applied to flatten the surface, then a resist is further applied to the upper layer and patterned, and the lower layer is etched using oxygen reactive ion etching using this pattern as a mask. A so-called multilayer resist technique has been developed in which a non-photosensitive resin is etched to form an entire resist relief pattern, but the resist used for the upper layer must have sufficient resistance to oxygen reactive ion etching, The conventional one is a silicone-based resin that is sensitive only to electron beams or the far ultraviolet region, and is sensitive to the two emission lines of mercury (11 and 7A), which are commonly used.
The reality is that there is nothing sensitive to nanometers (nm).

[Failure to solve the problem]

In view of these points, the present inventors conducted intensive studies and found that
By combining a naphthoquinone diazide photosensitizer with a novolac resin containing a specific organosilicon compound as a condensation component, a positive photoresist composition with excellent dry etching resistance, particularly oxygen reactive ion etching resistance, and high resolution can be obtained. This led to the completion of the present invention.

That is, the gist of the present invention is as follows: (a) a 7-toquinone diazide photosensitizer; and (b)
At least one of meta-cresol and para-cresol, and the general formula (R1''+ R3 represents an alkyl group or an aryl group,
R4-R7 represent hydrogen, an alkyl group or a phenyl group.

) A positive photoresist composition characterized by containing a novolac resin obtained by condensing a mixture with an organosilicon compound represented by the following formula and an aldehyde.

Next, the present invention will be explained in detail.

As the naphthoquinonediazide-based photosensitizer, an ester of hako-naphthoquinonediazide-5-sulfo/acid and a compound having a phenolic hydroxyl group is used, and any one can be used as long as it shows appropriate development characteristics as a positive photoresist. Examples of compounds having a phenolic hydroxyl group include 3. 'I-)lyhydroxybenzophenone, co,j,4(,4(-7tophhydroxybenzophenone, quercetin, etc.) are preferably used.The hydroxyl group of the compound having a phenolic hydroxyl group is 2.J,I
In the case of I-trihydroxybenzopheno/, 5 oqb or more of the hydroxyl group, , , 7. lI, 5 in the case of danotetrahydroxybenzophenone, 7 of its hydroxyl group
0% or more, and in the case of quercetin, Aθ% of its hydroxyl group
The above is 7. A 2-naphthoquinonediazide based photosensitizer which is an ester of conabutoquinonediazide-3-sulfonic acid is preferably used. When the esterification rate of phenolic hydroxyl groups is low, the residual film rate of the resist film in the unexposed area generally decreases.

The novolac resin is a novolac resin obtained by condensing a mixture containing a specific organosilicon compound and at least one of metacresol or paracresol with formaldehyde according to a conventional method, and has suitable development characteristics as a positive photoresist. Any resin can be used as long as it exhibits the following, but preferably a novolac resin having a styrene-equivalent weight average molecular weight of /,000 to 30,000 in gel permeation chromatography.

When paratrialkyl-7lylphenol is used as an organosilicon compound as a condensation component, the trialkylsilyl group is removed by the acid catalyst during novolak resin synthesis, and all become phenol. Therefore, in the present invention, the following general formula is used: It is necessary to use an organosilicon compound represented by

HOR'(R' to R3 represent an alkyl group or an aryl group, R4
-R1 represents hydrogen, an alkyl group or a phenyl group. ) Specific examples of organosilicon compounds of the above general formula include metatrimethyl7lylphenol, metatriethylsilylphenol, dimethylphenylsilylphenol, di7lylphenol,
Examples include 1-rumethyl-7-lylphenol and metatriphenylsilylphenol.

The higher the content of the organosilicon compound in the Novo2c resin, the better the dry etching resistance. However, in consideration of sensitivity, the organosilicon compound is usually used in a 20-10 mol range, and metacresol or para-cresol is gθ~20
Selected from a range of morchis.

The ratio of the naphthoquinone diazide photosensitizer to the novolak resin is usually as follows:
About 10 to 70 parts by weight of photosensitizer, preferably 73 to 26 parts by weight
The above-mentioned novolak resin and toquinonediazide-based photosensitizer are dissolved in a solvent such as ethyl cellosolve acetate, mixed in parts by weight, and applied onto a substrate such as a silicon wafer, and exposed and developed according to a conventional method. ,sensitivity,
Furthermore, a resist with good dry etching resistance can be obtained.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Synthesis example/ Metatrimethylsilylphenol! ;　Ommol.

Metacresol! ; A mixture of Om1ml101 and 70 mmol of 37% formaldehyde aqueous solution was added with stirring.
Heat to 100°C and add A mmol of oxalic acid.
3. At 705℃. After reacting for S hours, water and unreacted monomers were distilled off under reduced pressure to obtain a novolac resin of g, J9.

Synthesis example cometatrimethylsilylphenol J Ommol, metacresol 30 mmol, paracunzole 30fnI
+101 and 3 cutiformaldehyde aqueous solution 63 mmo
1 was stirred and heated to DO℃, oxalic acid was added, and q plate 01 was added, and after reacting at 100℃ to 1O5℃ for 3.3 hours, the water and unreacted monomers were distilled off under reduced pressure. Obtained.

Example 1 Novolac resin 3.0 consisting of molar ratio of trimethylsilylphenol and metacresol obtained in Synthesis Example
11 and 3. Naphthoquinonediazide-based photosensitive 1dJO, in which 90% or more of the hydroxyl groups of dihydroxypenzophenone are esters of /,2-naphthoquinonediazide-5-sulfonic acid. ;I! f ethyl cellosolve acetate? , Jll and filtered through an Ol-μm 70 Robofilter (manufactured by Sumitomo Electric).

The obtained P solution was applied to a coin chip wafer with a thickness of 7.55 μm.
A sample was obtained by spin coating to obtain a film thickness of . After prebaking at 9g°C for 30 minutes in an open environment, it was exposed using Mikasa Mask Aligner MA-/θ and a Toppan Printing (Stock System Step Tablet), and then exposed using a tetramethylammonium hydroxide, 3F1 aqueous solution at 2SC for 7 minutes by immersion method. The remaining film rate at each step of the step tablet was measured, a sensitivity curve was obtained, and the number of seconds of lightning at which the remaining film rate reached θ was extrapolated from the sensitivity curve, and it was found to be 12 seconds.

Next, the photoresist photosensitive solution was spin-coated onto the coin chip wafer to a film thickness of 1 μm, and then placed in an oven for 9 days.
Pre-bake for 30 minutes at 0°C. PA-/lfi/ (
2. Exposure using a Canon stepper) and a resolution test mask manufactured by Curved Printing ■. ．． The film was developed by dipping in a 3'1% aqueous solution of tetramethylammonium hydroxide at 5°C for 1 minute. When the resolution was examined using a scanning electron microscope (Akashi Seisaku Shinsei S-GMA II), θ, t
Good resolution was achieved down to μm.

Further, when the film surface was etched using a plasma etching apparatus manufactured by Plasma Thermo Co., Ltd. in R-E (reactive ion etching) mode using oxygen as an etching gas, the remaining film ratio was 97 inches, and there was no substantial film loss.

Novolak resin consisting of trimethylsilylphenol, p-cresol, and meta-cresol obtained in Example co-Synthesis example co, in a molar ratio of 1 pair/pair/3. OI and a, 3.41 - 90% or more of the trihydroxybenzophenone hydroxyl groups are esters of λ-naphthoquinonediazide S-sulfo/acid, 7 toquinone diazide photosensitizers o, sy, ethyl cellosolve acetate, 9. Dissolve in 3g and 0. A sample was obtained by applying it to silicone urethane in the same manner as in Example 1, and obtaining a sensitivity curve in the same manner. When the exposure time was extrapolated, it was 75 seconds.

Next, exposure was carried out using FPA-/II/ (Canon Stepper) in the same manner as in Example 1, and the resolution was determined to be 003.
A micrometer line-and-space pattern was resolved.

In addition, the film surface was etched using a Plasmatherm plasma etching apparatus using oxygen as an etching gas in R-K (reactive ion etching mode).As a result, the remaining film rate was 100% and there was no film loss.

〔Effect of the invention〕

According to the composition of the present invention, it has excellent dry etching resistance and has sensitivity that allows extremely fine pattern formation.
In addition, since it is sensitive to 9 emission lines, it can be very suitably used as a photo-cist in the production of ultra-LEI technology.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - (1 other person)

Claims (4)

[Claims] (1) (a) Naphthoquinone diazide photosensitizer, and (b
) At least one of meta-cresol and para-cresol, and the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (R^1 to R^3 represent an alkyl group or an aryl group,
R^4 to R^7 represent hydrogen, an alkyl group, or a phenyl group. 1. A positive photoresist composition comprising a novolac resin obtained by condensing a mixture of an organosilicon compound represented by the following formula with an aldehyde. (2) The naphthoquinone diazide photosensitizer is 2,3,4-
50% or more of the hydroxyl groups in trihydroxybenzophenone are esters of 1,2-naphthoquinone azide-5-sulfonic acid, or 60% or more of the hydroxyl groups in 2,3,4,4'-tetrahydroxybenzophenone are 1,2-naphthoquinone diazide. -5-Sulfonic acid ester or a naphthoquinonediazide-based photosensitizer in which 60% or more of the hydroxyl groups of quercetin are 1,2-naphthoquinonediazide-5-sulfonic acid esters, Claim 1 The photoresist composition described in . (3) Claim 1 or 2, wherein the novolak resin is a novolak resin obtained by condensing a mixture of meta-trialkylsilylphenol, metacresol and para-cresol, and formaldehyde. The photoresist composition according to item 2. (4) The weight average molecular weight of the novolak resin is 1,000 or more
30,000.
The photoresist composition according to any one of items 1 to 3.