JPH01275654A - Positive photoresist composition - Google Patents

Abstract

PURPOSE:To obtain a positive photoresist composition improved in resolution, sensitivity, heat resistance, developability, shape of resist, etc., by mixing a specified alkali-soluble novolac resin with a 1,2-quinonediazide compound. CONSTITUTION:A cresol/phenol mixture (i) is reacted with 0.6-1.0mol, per mol of component (i), of an aldehyde (ii) (e.g., formaldehyde) at 70-200 deg.C in the presence of 1X10<-4>-1X10<-3>mol, per mol of component (i), of an acidic catalyst to obtain an alkali-soluble novolac resin (A) having a weight-average MW (in terms of the MW of PS as determined by gel permeation chromatography) of 2,000-30,000 and giving a <13>C-NMR spectrum in which M is within the range of formula I (wherein a is the peak area of 111.5-113.8ppm, b is the peak area of 113.8-115.8ppm, and c is the peak area of 115.8-118.4ppm) and N is within the range of formula II [wherein d is the peak area of a methyl carbon atom (15-21ppm), e is the peak area of an aromatic carbon adjacent to a hydroxyl group (149-156ppm)]. 100pts.wt. component A is mixed with 5-100pts.wt. 1,2-quinonediazide compound (B) as a photosensitive material.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a positive photoresist that is sensitive to radiation, and more particularly, it relates to a positive photoresist that is sensitive to radiation, and more particularly, it is composed of a specific alkali-soluble Tumerac resin and 1. The present invention relates to a positive photoresist composition containing a coquinone diazide compound, which is excellent in resolution, sensitivity, heat resistance, developability, and resist shape. The positive photoresist according to the present invention is coated onto a semiconductor wafer or a substrate made of glass, ceramics, metal, etc. to a thickness of 0.1 to 3 μm by spin coating or roller coating. Thereafter, it is heated and dried, and a circuit pattern etc. is printed by UV irradiation through a glazing mask and developed to obtain a positive image.

Furthermore, by etching this positive image as a mask, it is possible to process the substrate into a pattern. Typical application fields are the manufacturing process of conductors such as ICs, the manufacturing of circuit boards such as liquid crystals and thermal heads, and other photosensitive application processes.

<Prior Art> As a positive photoresist composition, a composition containing an alkali-soluble resin and a naphthoquinone diazide compound as a photosensitive material is generally used. For example, USP-J44J Hiro 73, 08F-≠// as "Tumelac-type phenolic resin/naphthoquinone diazide substituted compound"
! No. 1 and USP-111734A70, etc., the most common composition is ``novolak resin composed of cresol-formaldehyde/trihydroxybenzophenone-7,l-naphthoquinonediazide sulfonic acid ester'' by Thompson. “Introduction to Microring Graphie” (L, F, Thomps
on “Introduction t.

Microlithography J) (AC8 Publishing, Muco No. 12, pi/co~/2/).

Novolac resins as binders are particularly suitable for this application because they can be dissolved in alkaline aqueous solutions without swelling and also provide high resistance to plasma etching, especially when the generated image is used as an etching mask. Useful. In addition, the 7-toquinone diazide compound used in photosensitive materials itself acts as a dissolution inhibitor that reduces the alkali solubility of the novolac resin, but when it decomposes when exposed to light, it produces alkali-soluble substances and rather It is unique in that it functions to increase solubility, and because of its large property change in response to light, it is particularly useful as a photosensitive material for positive photoresists.

From this point of view, many positive photoresists containing novolac resins and naphthoquinonediazide-based photoresists have been developed and put into practical use.

! Sufficient results have been achieved in line width processing of μm-λμm up to 1 MA degree.

<Problems to be solved by the present invention> However, the degree of integration of integrated circuits is increasing and
In the manufacture of semiconductor substrates such as SI, it has become necessary to process ultra-fine patterns having line widths of 1 μm or less. In such applications, a photoresist is required that has particularly high resolution, high sensitivity for accurately copying the shape of the exposure mask, R-turn shape reproduction accuracy, and high sensitivity from the viewpoint of high productivity. The reality is that photoresist cannot handle this problem.

Therefore, the objects of the present invention are to provide (1) a positive photoresist composition with high resolution, and (2) accurate mask dimensions over a wide range of photomask line widths, particularly in the production of semiconductor devices. (3) A positive photoresist composition capable of producing a cross-sectional resist pattern with a high aspect ratio in a pattern with a line width of 1 μm or less; (4) Pattern cross section (5) A positive photoresist composition that can produce a pattern with nearly vertical sidewalls; (5) A positive photoresist composition that has a wide development latitude; (6) A positive M7 photoresist whose resulting resist has excellent heat resistance. (7) A positive photoresist composition that does not produce resist residue or scum in exposed areas.

The goal is to provide the following.

Means for Solving the Problems The inventors of the present invention have taken into account the above-mentioned characteristics and, as a result of intensive study, have found that the novolac resin has cresol and phenol as its constituent components, and the peak area of its C-NMR spectrum is The inventors have discovered that the above objects can be achieved by using a device that is limited to a certain specific range, and based on this knowledge, the present invention has been accomplished.

That is, the object of the present invention is to provide an alkali-soluble novolak resin and/or
In a positive photoresist composition comprising a l,z-quinonediazide compound, the alkali-soluble novolac resin condenses cresol and phenol using an aldehyde, and in its 13C-NMR spectrum,
This was achieved using a positive photoresist composition characterized in that M and N are in the ranges of formulas (1) and (2), respectively.

The present invention will be explained in detail below.

The alkali-soluble novolac resin used in the present invention can be obtained by condensing a predetermined monomer with an aldehyde in the presence of an acidic catalyst. The predetermined monomer is m-
A mixture of cresol, p-cresol and phenol is used.

Examples of aldehydes include formaldehyde, non-formaldehyde, furfural, acetaldehyde,
Examples include benzaldehyde, but formaldehyde is preferably used.

As the acidic catalyst, hydrochloric acid, sulfuric acid, formic acid, oxalic acid, acetic acid, etc. can be used.

The amount of the above aldehyde used is 0.0000000000000000000000000000000000000000000,000,000,000,000,000,000,000,000,000, based on 1 mole of the specified monomer. t~/, 0 mol, the amount of the acidic catalyst used is:
/X10' to /X1 for 1 mole of a given monomer
A range of 0 mol is preferable.The reaction temperature is usually 7 mol.
00C to λooOc. It is preferable that the weight factor of the novolac resin obtained in this way be within the range.

Here, the weight average molecular weight is defined using a polystyrene equivalent value using gel normation chromatography.

When the weight average molecular weight is less than 2000, the film loss after development in the unexposed area is large (If it exceeds JOOOO, the development speed becomes small. Furthermore, in order to impart good heat resistance, it is necessary to A range of is particularly suitable.

The C-NMR spectrum of the deuterated dimethyl sulfoxide solution of Norac resin obtained from m-cresol, p-cresol and phenol described above is l! ~
ko/ppm%///, j ~//r, 'ippm and l
≠2.0-/j4. A unique peak is given to Oppm, etc., but if the constituent component ratio of the resin is different, the ratio of the integral value of each peak will be different.

The resins used in the present invention have this ratio within a specific range. Specifically, resins in which M and N defined by formulas +11 and (21) are both within the following ranges are preferred.

More preferably, M and N are each O0 at the same time! ≦M≦
0.6.0. l! The resin is in the range of ≦N≦00.2J.

(MHz) f, temperature, 2j ~ 41 @C,,
The measurement was carried out under the following conditions: e las width Y, 0 μs (ri o O), waiting time po seconds, reference peak tetra, methylsilane, and measurement mode reverse gated decoupling mode.

The 1,-2-quinonediazide compounds used in the present invention include /, -1-7toquinonediazide-t-sulfonic acid, /, 2-naphthoquinonediazide-dasulfonic acid,
Alternatively, an ester of cobenzo Φ nondiazide μm sulfonic acid and a polyhydroxy aromatic compound is used.

Examples of the polyhydroxy aromatic compound include co-, 3-
．． Dartrihydroxybenzophenone, co, ≠, 4A'
-Trihydroxybenzophenone, J, 4! , 4-) lyhydroxybenzophenone, co.

3.1. 3′-tetrahydroxybenzophenone,
2', 4A, 4t'-tetoxybenzophenone, 21≠, 4. j', 44', j'-hexahydroxybenzophenone, cop's "s" tp/, zl-
Polyhydroxybenzophenones such as hexahydroxybenzophenone, 3゜hiro-trihydroxyacetophenone, 3. Polyhydroxyphenylalkyl ketones such as trihydroxyphenylhexyl ketone, bis(co,hiro-dihydroxyphenyl)methane, bis(J,J,$-trihydroxyphenyl)methane, bis(J, 4cm dihydroxyphenyl)pro /Gun-/
, etc., bis((poly)hydroxyphenyl)alkanes such as j, p, j-)propyl hydroxybenzoate, j,
$,j-) Polyhydroxybenzoic acid esters such as phenyl trihydroxybenzoate, bis(J, j,!-)lihydroxybenzoyl)methane, bis(Tips 3. Polyhydroxybenzoyl) alkanes or bis(polyhydroxybenzoyl)aryls, ethylene glycol di(J
, J-dihydroxybenzoate) and other alkylene di(polyhydroxybenzoates), J, to,! ',!
'-Biphenyltetrol, 21≠, co1.4cl-Biphenyltetrol, λ.

≠, a, j', j'-biphenylindole, co.

Hiroshi, Otsu, 2/, 4L/, 6/-polyhydroxybiphenyls such as biphenylhexol, Hiroshi, 4
L'.

J",4t"-nato2hydroxy-3. Evening, 3'.

! '-Tet2methyltriphenylmethane 44. Hiro'.

ko, 3, l-he7tahydroxy 3. j.

3/, zl-tetramethyltriphenylmethane, co, 3
．． μ, koZ3/, da/, j', 4! "-octahydroxy-!,!'-Polyhydroxytriphenylmethanes such as diacetyltriphenylmethane, J, J,!',
3'-tetramethyl-7゜l'-spirobiindane-
t, a, j/, 4/.

-Tetrol, J, J, J',! '-tetramethyl-1
．． /,'-Spirobindan-r,,4,7゜11.
61. y/-hekinall, J, j, j'.

3'-tetramethyl-/, l'-spirobiindane-
Hiroshi, r, a, ≠ 1. z1.41-hexol, j, j
, j', j'-tetramethyl-l.

l/-Spirob Indanda I'l'l"1≦', 7
Polyhydroxy spirobiindans such as '-hequinol and the like can be used.

In the present invention, the ratio of the photosensitive material and the alkali-soluble novolak resin is 100 parts by weight of the novolac resin to 100 parts by weight of the novolak resin. ~ioo parts by weight, preferably 10~! It is 0 parts by weight. If the usage ratio is less than 1 part by weight, the residual film rate will be significantly lowered, and if it exceeds 100 parts by weight, the sensitivity and solubility in solvents will be lowered.

The present invention can further contain a polyhydroxy compound to promote dissolution in a developer.

Preferred polyhydroxy compounds include phenols, resorcinol, 70glucine%'l'#≠-trihydroxybenzophenone, 2. J, France, 4t/-tetrahydroxybenzophenone, acetone-pyrogallol condensation resin phloroglucide, and the like.

Examples of solvents for dissolving the photosensitive material and alkali-soluble novolak resin of the present invention include ketones such as methyl ethyl ketone and cyclohexanone, alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, and ethers such as dioxane and ethylene glycol dimethyl ether. cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate, fatty acid esters such as butyl acetate, methyl lactate, ethyl lactate, 's'+')! J Halogenated hydrocarbons such as dichloroethylene, dimethylacetamide,
Examples include highly polar solvents such as N-methylpyrrolidone, dimethylformamide, and dimethylsulfoxide. These solvents can be used alone or in combination.

The positive photoresist composition of the present invention may contain dyes, plasticizers, adhesion aids, surfactants, and the like, if necessary. Specific examples include dyes such as methyl violet, crystal violet, and malachite green; plasticizers such as stearic acid, acetal resin, phenoxy resin, and alkyd resin; adhesive aids such as hexamethyldisilazane and chloromethylsilane; There are Ω surfactants such as nonylphenoxypoly(ethyleneoxy)ethanol and octerphenoxypoly(ethyleneoxy)ethanol.

The above-mentioned positive dispersion photoresist composition is coated onto a substrate (e.g. silicon/silicon dioxide coated) used in the manufacture of precision integrated circuit elements by an appropriate coating method such as a spinner or coater, and then coated with a predetermined mask. A good resist can be obtained by exposing and developing the resist.

Examples of the developer for the positive photoresist composition of the present invention include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, etc. i/amines, diethylamine, di-n-
Secondary amines such as butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, μ-class ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, All aqueous solutions of alkalis such as cyclic amines such as pyrrole and piperidine can be used. Furthermore, appropriate amounts of alcohols and surfactants may be added to the aqueous alkali solution.

<Effects of the Invention> The positive photoresist of the present invention has excellent resolution, sensitivity, heat resistance, developability, and cross-sectional shape of a resist image, and is suitably used as a photoresist for microfabrication.

<Examples> Examples of the present invention will be shown below, but the present invention is not limited thereto. Note that % indicates weight loss unless otherwise specified.

Example 1 (1) Synthesis of novolak resin (a) m-cresol Jtf% p-cresol ay.

Phenol/7f, 37% formalin water soluble IQi, j2
and oxalic acid 0. /f'f (Pour it into a Mitsuro flask, raise the temperature to 100'C without stirring, and react for l! hours.Then, raise the temperature to 000C and gradually increase the temperature to 100'C.
Vacuum was applied to wx Hg to remove water, unreacted monomer, formaldehyde, and oxalic acid. Then, the molten alkali-soluble (metallic) resin was returned to room temperature and recovered. The obtained novolak resin had a weight average molecular weight of ttco00 (in terms of polystyrene).

(2) Synthesis of photosensitive material, 3. μ, μ′ tetrahydroxybenzophenone f
, Jt, /, Cornaphthoquinone diazido! - Sulfonyl chlorite co-r, at and acetone core 0d were charged into a Mitsuro flask and uniformly dissolved under stirring. Then triethylamine //.

/ff: Gradually added dropwise and allowed to react at room temperature for 1 hour.

After the reaction, the contents were dropped into a 1% aqueous hydrochloric acid solution, the resulting precipitate was separated, washed with methanol, and dried to give a %-
21'1≠, an ester compound of μ'-tetrahydroxybenzophenone was obtained.

(3) Preparation and evaluation of positive photoresist composition (2)
The photoreceptor obtained in (1), JOfl and the novolak resin It obtained in (1) were treated with ethyl cellosolve acetate ire.
and filtered using a 0.2 μm microfilter to prepare a photoresist composition. This photoresist composition was coated on a silicon wafer using a spinner and dried for 130 minutes at P0°C in a convection open atmosphere under a nitrogen atmosphere to obtain a resist film with a thickness of /Jμm. After this film was exposed using a photolithographic exposure device lt-, it was developed for 1 minute with a 2.31% aqueous solution of tetramethylammonium hydroxide, washed with water for 30 seconds, and dried. The resist pattern of the nine silicon wafers thus obtained was examined using a scanning electron microscope, and the resist was evaluated. The results are shown in Cloth-7 below.

The sensitivity was defined as the reciprocal of the exposure amount for reproducing a 2.0 μm mask pattern, and was expressed as a relative value of the sensitivity of Comparative Example 1.

The resolving power represents the limit resolving power that exceeds the exposure amount that reproduces a mask pattern of 2.0 μm.

Heat resistance was determined by baking a silicon wafer on which 9 turns of resist had been formed in a convection oven for 30 minutes, and showing the temperature at which the pattern did not deform.

Developability is determined by observing the resist pattern with a scanning electron microscope and checking for resist residue and scum in exposed areas.

The shape of the resist is expressed as the angle (0) between the resist wall surface and the plane of the silicon wafer in the cross section of the resist pattern of 0 μm.

Examples 2 and 3, Comparative Examples/~Hirota-/L/(As shown, novolak resins with different molar ratios of m-cresol, p-cresol, and phenol were synthesized, and resists were prepared in the same manner as in Example 1. 9. Preparation and evaluation.

As is clear from the table, the positive photoresist of the present invention has excellent resolution, sensitivity, heat resistance, developability, and resist shape.

Claims (1)

[Scope of Claims] A positive photoresist composition comprising an alkali-soluble novolac resin and a 1,2-quinonediazide compound, wherein the alkali-soluble novolac resin condenses cresol and phenol using an aldehyde, and
A positive photoresist composition characterized in that M and N are in the ranges of formulas (1) and (2), respectively, in the ^3C-NMR spectrum. 0.4≦M=(b/a+b+c)≦1.0...
(1) However, a is the peak area of 111.5 to 113.8 ppm b is the peak area of 113.8 to 115.8 ppm c is the peak area of 115.8 to 118.4 ppm 0.1≦N=(de /d)≦0.6・・・・・・・・・
...(2) However, d is the peak area of methyl carbon (15 to 21 ppm) and e is the peak area of aromatic carbon adjacent to the hydroxyl group (149 to 156 ppm).
m) peak area