JPS61278846A - Positive type photoresist composition - Google Patents

Abstract

PURPOSE:To improve a pattern profile by incorporating a photosensitive component contg. a quinonediazide group, and as a resin component a specified novolak resin and/or a specified vinylphenol polymer. CONSTITUTION:The positive type photoresist composition consists of the photosensitive component A contg. the quinonediazide group and the resin component B of the novolak resin obtained by additionally condensing formaldehyde with one of phenols substd. by 0.5-1.5 average C per one phenol ring represented by formula I, R1 being H or 1-4 C alkyl, and/or the vinylphenol polymer having repeating units each represented by formula II, R2 being H or methyl, mixed in an A/B weight ratio of (1:5)-(1:7). This photoresist composition is characterized by having a light absorptivity of 0.15-0.27 at 400nm wavelength, when it is dissoved in dioxane to prepare a dioxane solution contg. the solid matter freed of solvent volatile matter in an amount of 10<-4>g/ml and that solution is measured by placing it into quartz cell of 1 cm light path length.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to positive photoresist compositions with improved pattern profiles.

Since positive-type photoresists have significantly better resolution than negative-type photoresists, they have recently been used as an etching protective film ( It is used as a resist film).

Proposals regarding these are also published in Japanese Patent Publication No. 88-12088, Japanese Patent Publication No. 41-16259, and Japanese Unexamined Patent Publication No. 58-171.
Various efforts have been made, such as in Publication No. 12.

Of these, @ product circuits are now 64KDRAM → 2
In 66 → IM (mega) and miniaturization due to high integration progressed,
Nowadays, pattern forming with a width of 1 μm is required. In order to form such fine patterns with high precision, it is important not only to change from a contact exposure method to a reduction projection exposure method, to improve exposure equipment, and to improve an etching method, but also to improve the performance of the photoresist used therein.

That is, it has been found that when seeking high resolution, the pattern profile, which is one of the characteristics of the resist, becomes a problem.

The pattern profile referred to here means that the resist is connected to the substrate i.
This refers to the cross-sectional shape of the resist pattern after coating, exposure, and development.

Nine typical examples are shown in FIGS. 1 to 8. In the figure, 1 indicates a substrate, and 2 indicates a resist. Figure 1 (J) This is a so-called "overhang shape" and is an advantageous shape when forming a desired pattern using a method called lift-off method. The pattern shown in Figure 3 is a trapezoidal pattern with a taper.

The pattern shown is this. The degree of taper varies depending on the process conditions such as the resist used, exposure method, development method, and conditions.

When forming a very thin pattern of 1 .mu.m width by etching, the shape shown in FIG. 8 is the most problematic. The problems can be broadly classified into the following two points.

■Resist pattern width is the top surface of the pattern (top side of trapezoid)
and the lower surface (base of the trapezoid), so the closer the pattern spacing, the more difficult it is to control the dimensions.

Q) Recently, as the demand for miniaturization has progressed, conventional hydrofluoric acid,
Hot etching using an etching solution such as nitric acid has been replaced by dry etching, and in particular, reactive ion etching (RIE), a method of etching using directional ions or plasma. In this case, in the case of a trapezoidal pattern, the resist film thickness is particularly thin at the base of the pattern, so it cannot withstand etching species (ions, plasma, etc.), and the dimensional values after etching vary or do not match the designed values.

From these facts, it can be said that as long as a pattern is formed by etching, it is desirable that the cross-sectional shape of the pattern be as close to the rectangular shape shown in FIG. 2 as possible. In order to obtain such patterns, improvements are usually made to the process, such as pre-baking conditions, developing methods, and on-site conditions. However, it is extremely difficult to control the pattern shape using these methods, and even if it were possible, it would be difficult to implement, as a nearly rectangular pattern could only be obtained under certain limited conditions. Or, it must be said that it is a method with extremely poor reproducibility.

In view of this situation, the inventors of the present invention conducted intensive studies on the relationship between resist composition and pattern profile, and as a result, the ratio of the photosensitizer component to the resin component in the resist and the measurement of the resist solid component at a specific wavelength were determined. The present inventors have discovered that the absorbances affected affect the pattern profile of the resist, and that when these absorbances take values within a specific range, the pattern profile is greatly improved.

That is, the present invention provides (A) a photosensitizer component containing a quinonediazide group, and (B) a mixture of one or more compounds represented by H (an alkyl group having a prime number of 1 to 4) as a resin component, which contains phenol. A novolak resin obtained by addition-condensation reaction of a phenol having an average number of substituted carbon atoms per skeleton of 035 to 1.5 with formaldehyde, and/or a vinyl having a repeating unit represented by a methyl group) In a positive photoresist composition containing a phenolic polymer, the above (A
): The component ratio (weight 11) of (B) is 1:5 to 1;7
and the solid content of the resist composition excluding the solvent volatile content is IO? When a dioxane solution adjusted to /- is measured using a quartz cell with an optical path length of 11, Part 4
Provided is a positive photoresist composition characterized in that the absorbance at 0.00 nm is in the range of 0.915 to 0.27.

According to the present invention, the pattern profile obtained using the resist composition of the present invention exhibits excellent rectangularity as shown in FIG.

The present invention will be described in more detail below. The photosensitive agent containing a quinonediazide group in (M) is a compound containing a naphthoquinonediazide group or a benzoquinonediazide group. It can be obtained by condensation in the presence of. Examples of compounds having hydroxyl groups are /”% idoquinone, resorcinol, phloroglucin, 2.4-dihydroxybenzophenone, 2.8
．． Examples include 4-trihydroxybenzophenone, gallic acid alkyl ester, and 2.2',4.4'-tetrahydroxybenzophenone.

Next, the resin component (B) will be described. The resin component that can be used in the present invention may be a novolak resin, a vinyl phenol polymer, or a mixture thereof. Phenols, which are the raw materials for the novolak resin referred to herein, are used alone or as a mixture of two or more kinds of compounds. In the above general formula, R1 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and R1 is o-1m, p-
It may be bonded at any position. Examples of such compounds include isomers of phenol, O-cresol, m-cresol, p-cresol, 〇-ethylphenol, m-ethylphenol, p-ethylphenol, propylphenol, and isomers of butylphenol. It will be done. One or a mixture of two or more of these compounds is used, and in that case, the average number of substituent carbon atoms per phenol skeleton needs to be 0.5 to 165. Average number of substituent carbon atoms per phenol skeleton is 0
．． If the number of substituents is less than 5, the novolac resin dissolves too quickly in the developer (alkaline aqueous solution), resulting in a decrease in the remaining film rate of the unexposed areas that should remain, and conversely, if the average number of substituent carbon atoms is 1.
If it exceeds 5 m, the speed at which the novolak resin dissolves in the developer becomes slow, causing a problem that it takes time to develop the exposed area. Therefore, this average substituent carbon number is 0.
Choose between 5 and 1.5 pieces.

For example, when a mixture of m-cresol and p-cresol is used, the average number of substituent carbon atoms per phenol skeleton is 1, so the above conditions are satisfied.

When a mixture of phenol and m-ethylphenol is used, it may be used within the range of 1/8≦phenol/m-ethylphenol≦8 (molar ratio) according to the above conditions.

In the mixture, 5 Q mole % or more of phenols having a substituent at the m-position in m-1p-10- is preferable because the sensitivity of the resist is increased.

Specific examples of phenols have been described above, but various other combinations and combinations of 8 or more can be considered, and in that case, 1ζ can also be used by selecting the mixing pressure from the above conditions.

Next, formaldehyde 1 to be subjected to addition condensation reaction with 1ζ phenols will be explained.

As formaldehyde, formaldehyde aqueous solution (
Formalin] and formaldehyde, which is an oligomer of formaldehyde, can be used. Especially 87%
Formalin is conveniently produced in large quantities industrially.

A novolac resin is obtained by addition condensation of these phenols and formaldehyde using a commonly used acid or an organic acid salt of a divalent metal as a catalyst. The acid used as a catalyst may be either an inorganic acid or an organic acid.

Specific examples include hydrochloric acid, sulfuric acid, phosphoric acid, P-)-luenesulfonic acid, oxalic acid, and trichloroacetic acid.

! Examples include organic acid salts of divalent metals and acetates, formates, lactates, and benzoates of metals such as magnesium, manganese, zinc, cadmium, cobalt, and lead, respectively. Alternatively, it may be a combination of the above-mentioned acids and an organic acid salt of a divalent metal.

Regarding the molecular weight of novolak resin, the optimum range varies depending on the type of phenol, the type of catalyst, and the reaction conditions, but it is generally determined by GPC (Gelber Meation Chromatography).
ooo~80,000, preferably 5,000~20
,000 is appropriate. The Mf shown here is a value calculated using a calibration curve obtained using monodisperse polystyrene from GPO Chromatogram L, and the GPC chromatogram was measured using a LO-08 preparative liquid chromatograph manufactured by Nippon Analytical Kogyo. Using the apparatus, 1 column of JAIGEL%L 8255 and JAIGEL, 2H manufactured by Japan Analytical Industry Co., Ltd. was used.
A series of books was also used at a flow rate of 2.5 ynt7 using tetrahydrofuran as the carrier solvent.

Next, a vinylphenol polymer that can be used as the resin component (B) will be described. The vinyl phenol polymer mentioned here is a polymer of the general formula (in the formula, 2 is hydrogen or a methyl group).

Specific examples include polymers of p-vinylphenol, 111-vinylphenol, P-isopropenylphenol, and m-isopropenylphenol. Further, the polymer may be a copolymer containing one unit of another monomer within the range that does not impair the present invention. Examples of copolymer materials include styrene derivatives, acrylic acid derivatives, and methacrylic acid derivatives. The vinylphenol content in the copolymer is generally preferably 50% or more. Suitable molecular weights for these polymers are 2.000 to 50,000 in terms of 5-average molecular weight measured by the method of Aki.

These polymers are disclosed in, for example, Japanese Patent Publication No. 48-16061, Special Publication No. 52-50898, and West German Patent No. 1.00.
It can be produced by the method described in the specification of No. 4.168 and Japanese Patent Application No. 1986-1962.

The composition ratio of the components (A) and (B) described above has a great influence on the pattern profile.

In order to obtain the above-mentioned ideal pattern with good rectangularity or something close to it, it is necessary to simultaneously satisfy the following two requirements.

■The component ratio (weight ratio) of (A): (B) is 1:5 to 1
■The solid content of the resist composition after removing the volatile content of the solvent must be within the range of io
When a dioxane solution adjusted to give y,,'INt is measured in a quartz cell with an optical path length of 1, the
Absorption summer at 1 m is in the range of 0.15 to 0.27.

As for (2), the most rectangular pattern can be obtained more preferably when the ratio is in the range of 1:5 to 1:6. 1:
If it is out of the range of 5 to 1, a pattern profile such as a trapezoid that is not desirable for an etching-resistant mask may result, or a resist pattern may not be formed at all, or the sensitivity of the resist itself may become low (desired Large exposure energy, specifically long exposure time, is required to obtain a resist pattern, resulting in a decrease in throughput and a very poor residual film ratio, which is undesirable.

Further, if the value is outside the range of (■), the same phenomenon will occur, which is not preferable.

The resist solution is prepared by dissolving and mixing each of the components in a suitable solvent. The solvent used here is preferably one that provides a uniform and smooth coating after the solvent evaporates at an appropriate drying rate. As such,
Examples include ethyl cellosolve acetate, methyl cellosolve acetate, ethyl cellosolve, methyl cellosolve, butyl acetate, methyl isobutyl ketone, and xylene.

The positive photoresist composition described above may further contain small amounts of additional resins, plasticizers, dyes, etc. as additional additives.

The photoresist composition of the present invention as described above has a particularly excellent pattern profile and exhibits an ideal pattern shape required as an etching mask. Utilizing this fact, it is possible to form fine patterns on the 1 μm level with high resolution, thereby achieving a significant improvement in throughput and yield (rate of non-defective products) in large-scale integrated circuit manufacturing.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but of course the present invention is not limited to these Examples.

Example 1 ■ Photosensitizer (naphthoquinone-(1,2)-diazide-(2
) - 1.2:1 (molar ratio) condensation reaction product of 5-sulfonic acid chloride and 2°8.4-trihydroxybenzophenone
My (weight average molecular weight) obtained by synthesis using oxalic acid as a catalyst at a charging ratio of cresol 26/4 = 10,50
0] 17F■ Dye (Sumiplas Treadm S, manufactured by Sumitomo Chemical Industries)
0.2) The above composition was filtered through a 0.2 μm filter, and the resist solution was filtered. Separately, a solution was prepared by diluting the resist composition with dioxane so that the solid content excluding the solvent component was 10-'Fd. This was measured using a spectrophotometer UV-865 at Takasugi Seisakusho, with an optical path length of 1.
When absorbance was measured at 400 nm using a proprietary cell, it was found to be 0.
．． It showed an absorbance of 21.

On the other hand, the resist solution was coated on a silicon wafer that had been cleaned using a conventional method using a spin coating machine (4000 r).
It was applied at pm. This was placed in a clean oven at 90°C and dried for 20 minutes. The thickness of the resulting coating film was 1.80
It was.

Then, using a contact mask aligner using a 260 W ultra-high pressure mercury lamp as a light source, exposure was performed for 8 seconds through a mask having a minimum line width of 1.5 μm. Add this to 80PD developer.
(manufactured by Sumitomo Chemical Co., Ltd., tetramethylammonium hydroxide aqueous solution) for 70 seconds. After development, the thickness was 1.6 μm.
A portion of the wafer onto which the pattern had been transferred was cut out, and its cross-sectional shape was observed with a scanning electron microscope. As a result, a 1.5 μm pattern with a cross-sectional shape as shown in FIG. 2 was clearly formed.

Example 2 (1) Photosensitizer (condensation reaction product of naphthoquinone-(1,2)-(2)-5sulfonic acid chloride and 2,8°4-trihydroxybenzophenone in a molar ratio of 1.1:1) 8. 8y-■
Novolak resin (MY-6000 made by reacting m-cresol with formalin using zinc acetate as a catalyst) 17? ■Dye (Sumiplas Tread A8゜Specially manufactured by Sumitomo Chemical) 0.2P After passing the above composition through a 0.2 μm filter to prepare a resist solution, it was applied to a silicon wafer through E-filtering as in Example 1. , dried in a clean oven. The obtained film thickness was 1.28 μm. This is DSW-4800 type 1
After exposure for 13QQmsec using a 0:1 reduction projection exposure machine using reticles with various dimensions, development was performed at 80PD for 70 seconds. Thereafter, a portion having a pattern size of 1°0 μm was cut out and observed under a scanning electron microscope, and a pattern with good rectangularity as shown in FIG. 2 was formed.

In addition, 4 Q Q nm measured in the same manner as in Example 1
The absorbance at was 0.24.

Example 8 While flowing well-dried nitrogen into a well-dried container, 50% of isopropenylphenyl acetate and 150% of 1,2-dichloroethane were charged, cooled to -41°C, and stirred.

After carefully adding 10 WIt of antimony pentachloride 1,2-dichloroethane solution (0.02 mol/l) so that the system temperature did not exceed 185°C, the internal temperature was returned to -41°C.
Stirring was continued for 6 hours. After 10 dk of methanol was added to stop the polymerization, the viscous polymerization mixture was poured into 81 g of methanol, and the precipitated isopropenylphenyl acetate polymer was dried door to door. This polymer and 'rE[Fl 00
d. 50 ml of methanol was charged into a reaction vessel, and the polymer was dissolved under stirring and reflux. 60 ml of 2N hydrochloric acid was added over 80 minutes, and stirring and refluxing was continued for 4 hours.

Further, the pressure of the system was reduced, the solvent was distilled off, and the precipitated isopropenylphenol polymer (40?, 98%) was recovered. GPC measurement after drying, MW=6400, [w/M
n=L. 20 physical properties were obtained.

A resist pattern was obtained in the same manner as in Example 1 except that the novolak resin of Example 1 (the above resin was used instead).The obtained pattern profile had good rectangularity as in Example 1. The absorbance measured in the same manner as in Example 1 was 0.24.

Comparative Example 1 ■Photosensitizer used in Example 1 6.8
? ■ 〃ri novolac resin 1
7y-■ ke Dye
0.2) The above composition was treated in the same manner as in Example 1,
It was applied onto a wafer and dried to obtain a coating film of 1.80 μm.

After exposure for 8 seconds using the contact mask aligner used in Example 1, development was performed for 70 seconds at 80PD, and when a portion corresponding to 1.6 μm was observed using a scanning electron microscope, a trapezoidal tapered pattern was obtained. Ta. Also 400nm
The absorbance of was 0.52. Further, patterns were similarly observed while varying the development time, but a pattern with good rectangularity as obtained in Example 1.2 could not be obtained.

Comparative Example 2 ■Photosensitizer used in Example 2 1.51■
〃 1 month Novolac resin 17? ■〃〃
〃 Dye 0.2? ■ 〃 2
Solvent 41' The above composition was treated in the same manner as in Example 1 to obtain a coating film of 1.81 μm. This was exposed for 8 seconds using the contact mask aligner used in Example 1 and then developed, but the sensitivity as a resist was low and a good pattern could not be obtained.

Further, the exposure time was changed to 1 second, 5 seconds, and 10 seconds, but the results were similar.

Furthermore, an attempt was made to form a pattern by changing the exposure time using the reduction projection exposure machine used in Example 2, but no pattern could be obtained.

Further, the absorbance of this product at 400 nm was 0612.

Super Examples 4 to 7, Comparative Examples 3 to 9 After preparing resist solutions using various photosensitive agents and resins as shown in Table 1, they were coated on wafers in the same manner as in Example 1, dried, exposed, and developed. , the pattern profile was observed.

The results are shown in the same table.

l) The solvent used was a mixture ratio of ethyl cellosolve/n-butyl acetate/xylene-8/1/1, and the amount of solvent was 1.8 when the resist composition was applied at 4000 rpffl.
It was adjusted to 0 μm.

2) Mutnaphthoquinone-(1,2)-diazide-(2
)-5-sulfonic acid chloride and 2.8.4-trihydroxybenzophenone in a 1.2:1 (molar ratio) condensation reaction product 3) Condensation reaction product 4 with the same components as BIA and a 1.1:1 molar ratio )C; naphthoquinone-(1,2)-diazide-(2)
- Condensation reaction product of 1.2:1 (molar ratio) of 5-sulfonic acid chloride and 2,4-dihydroxybenzophenone 5) Condensation reaction product with the same components as DHO and a molar ratio of O, S:t 5) EIO and Condensation reaction product with the same components and a molar ratio of 8=1 7) Novolac resin with My = 18000 obtained by reacting with formalin using oxalic acid as a catalyst at a charging ratio of FHm-cresol/p-cresol-8/2 8) G: Novolac resin with MW=9500 obtained by reacting with formalin using hydrochloric acid as a catalyst at a charging ratio of m-cresol/p-cresol 10-cresol=7/2/1 9) Sumiplast Tread A8. Sumitomo Chemical Specialty 10
) Exposure a Using a contact mask aligner b Using a reduction projection exposure machine 1 Absorbance at 400 nm of a solution prepared by diluting the solid content of the resist with dioxane to 10 P/- (optical path length of the cell 1 n) 12) Pattern profile ■ Rectangle Pattern profile with good properties (similar to Examples 1 and 2) ■Tapered pattern profile (similar to Comparative Example 1) ■Sensitivity as a resist is low and good patterns cannot be obtained ■Good patterns cannot be obtained No. (The developer 2ζ does not dissolve in the lI light area and the non-exposed area.)

[Brief explanation of the drawing]

Figures xi-8 show cross-sectional views of the pattern profile of the resist. l...Resist 2...Substrate board
1 Figure 112IXJ 3 Country

Claims (1)

[Scope of Claims] (A) A photosensitizer component containing a quinonediazide group, and (B) a resin component, including (i) general formula ▲ numerical formula, chemical formula, table, etc. ▼ (R_1 is hydrogen or a carbon number of 1 to 4 Addition condensation of phenols, which are one or a mixture of two or more compounds represented by (alkyl group) and have an average number of substituted carbon atoms per phenol skeleton of 0.5 to 1.5, and formaldehyde. Novolak resin obtained by reaction, and/or (ii) general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R
In a positive photoresist composition containing a vinylphenol polymer having a repeating unit represented by (_2 is hydrogen or methyl group), the above (A
):(B) component ratio (weight) is in the range of 1:5 to 1:7, and the solid content after removing the solvent volatile content from the resist composition is adjusted to be 10^-^4g/ml. When the dioxane solution was measured using a quartz cell with an optical path length of 1 cm,
A positive photoresist composition characterized in that its absorbance at 400 nm is in the range of 0.15 to 0.27.