JPH01129250A - Developing solution for positive type photoresist - Google Patents

Abstract

PURPOSE:To improve the selection ratio in the velocity of dissolution between the exposed and unexposed parts of a resist, defective development and the sharpness at the bottom by adding a specified nonionic surfactant and a quat. ammonium type cationic surfactant or a quat. ammonium compd. to an aq. soln. of org. quat. ammonium hydroxide. CONSTITUTION:A developing soln. is produced by adding a 'Pluronic(R)' and/or 'Tetronic(R)' type nonionic surfactant having 6-15 HLB prepd. by adding ethylene oxide to polypropylene glycol and a quat. ammonium type cationic surfactant or a quat. ammonium compd. to an aq. soln. of an org. quat. ammonium hydroxide. The developing soln. well wets the surface of a resist and can improve the selection ratio in the velocity of dissolution between the exposed and unexposed parts of the resist, defective development and the sharpness at the bottom without lowering the sensitivity of the resist. The soln. foams up hardly and can easily be handled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer for positive photoresists.

[Prior art] In recent years, the integration of integrated circuits has accelerated at an accelerating pace, and we are now moving into the era of so-called ultra-LSIs with an integration density of 1 million or more. The requirements for this photolithography technology are becoming more severe year by year, entering the submicron region of 0.2 μm or less, and even 0.8 μm or less.

By the way, the mainstream of positive photoresists currently in use is one in which a base alkali-soluble novolak resin is combined with a naphthoquinone diazide compound as a photodegrading agent, and carbonic acid groups are generated by light q4. Becomes alkali soluble. Therefore, as a developing solution for such a positive photoresist, a quaternary ammonium base that does not contain metal ions, such as tetramethylan7inium hydroxide or trimethylhydroxydi[delammonium hydroxide (choline)] is recommended. An organic quaternary ammonium hydroxide aqueous solution mainly composed of is used.

However, when only such an organic quaternary ammonium hydroxide aqueous solution is used as a developer, a satisfactory value cannot be obtained for the selectivity of the dissolution rate between the exposed and non-exposed areas of the positive photoresist. When it comes to fine patterns of 1μ or less, the effect of the decrease in the resist film thickness of the resist pattern that is 1q after development becomes relatively large, and the resist profile and 1-method control accuracy are extremely reduced. Problems such as poor development (scum, resist residue) where a small amount of undeveloped material remains and the problem of cut-off of the edges of the resist pattern are attracting attention.

Therefore, in the past, methods of adding a quaternary ammonium type cationic surfactant for the purpose of improving the selectivity of the dissolution rate (for example, Japanese Patent Application Laid-open No. 58-9143), and methods of adding resist residue and undercutting have been proposed. , or a method of adding a nonionic surfactant or a certain organic solvent to improve the wettability of the photoresist film (for example, Japanese Patent Laid-Open No. 58-5
7.128, JP-A-59-182.444@, JP-A-61-167, 948, wait u11, JP-A-62-32.45
No. 3, Japanese Unexamined Patent Publications No. 62-67, 535, etc.) have been proposed.

However, in a developer containing only a quaternary ammonium type cationic surfactant, although the dissolution selectivity for exposed and non-exposed areas is good, a serious problem arises in that resist sensitivity decreases. . In other words, in the current photolithography process, in order to improve the resolution, a single wafer is divided and exposed many times by performing reduction projection using monochromatic light with low light intensity. Stepper exposure has become mainstream, but as the degree of integration increases, the shapes that need to be drawn become increasingly complex, and the number of exposures tends to increase. A decrease in sensitivity requires a longer exposure time, leading to a reduction in the throughput of the exposure process that uses an expensive machine such as a reduction projection exposure machine, which becomes a major obstacle to the production of VLSIs. Another drawback is that scum remains (resist residue) is likely to occur in exposed areas after development, making it impractical.

In addition, in the method of adding nonionic surfactants or certain organic solvents, development characteristics such as wettability, resist, residue, and edge cutting are improved, but the difference between exposed and unexposed areas is improved. The drawback is that the selectivity of dissolution rate is reduced. For this reason, the residual film rate of the resist film decreases and the resist 1~ profile worsens, but this effect becomes relatively large as the pattern size becomes finer, so when the pattern size becomes submicron, This becomes a big problem.

Therefore, in order to compensate for these drawbacks and obtain practical improvements, a method using cationic surfactants and nonionic surfactants (for example, JP-A-61-18, 94) has been proposed.
No. 4, Japanese Unexamined Patent Publication No. 61-151,537, etc.) have been proposed. In this method, the following structural formula (% formula) (wherein R is an alkyl group having 10 to 20 carbon atoms or R'+
0- (R' to J coal jma6~250)7)'vki)
1. A nonionic surfactant with tlA>1 and O is an integer from 4 to 100 is employed. These are polyoxyethylene ether type and special nonionic ether type, which are commonly used as nonionic surfactants.

It is true that developers using these nonionic surfactants improve visual properties such as resist residue and edge breakage, including wettability, but they have a large foaming property and are difficult to bond with exposed areas. It has the disadvantage that the selectivity of the dissolution rate in the unexposed area is greatly reduced. Therefore, when using these nonionic surfactants and also adding a cationic surfactant in an amount sufficient to improve the dissolution rate selectivity, a significant decrease in resist sensitivity is unavoidable. .

In addition, if the concentration of these nonionic surfactants is so small that the selectivity of dissolution rate does not decrease significantly, the effect of practical improvement of visual properties such as resist residue and edge cutting will be small. It almost disappears.

Therefore, as a nonionic surfactant to be combined with a cationic surfactant, it has low foaming properties and has a great effect on resist residue, edge breakage, and wettability to photoresist films. Furthermore, it is desired that the selectivity ratio between the exposed area and the unexposed area is not lowered as much as possible.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to improve the wettability of a developer to the resist surface and to improve the dissolution rate between exposed and unexposed areas without reducing resist sensitivity. An object of the present invention is to provide a low-foaming positive photoresist developer with improved selectivity, poor development, and edge breakage.

[Means for Solving the Problems] The present invention is based on a polypropylene polymer having an organic quaternary ammonium hydroxide aqueous solution as a main component and having a B value of 6 to 15. Pluronic type and/or tetronic type nonionic surfactants, quaternary ammonium type cationic surfactants,
Alternatively, it is a positive photoresist developer containing a quaternary ammonium compound.

The organic quaternary ammonium hydroxide aqueous solution used as the main component in the present invention has the following general formula (however, in the formula R14
~R17 represents an alkyl group having 1 to 3 carbon atoms or a hydroxy-substituted alkyl group, which are the same or different from each other. Yes, specifically tetramethylammonium hydroxide (fHAH), trimethylhuman 0
xyethylammonium hydroxide (choline)
, methyltrihydroxyethylammonium hydroxide, dimethyldihydroxyethylammonium hydroxide, tetraethylammonium hydroxide, trimethylethylammonium hydroxide, etc., but from the viewpoint of pH, production, economics, etc., diHAtl is preferable. It is an aqueous solution of choline and choline.

In addition, the nonionic surfactants used in the present invention include:
Below - Formula (I> or (I) ■0 to 8, Q-BII
, -Ao-H(I)HO-Cx-Ay-Cz-H(
ff > (formula midship L -CH12-CH12-0-1
B is -CI1. (CIl3)-Cf12-0-, C is -CIl-CIl(CH+3)-0-1j +n=
15~2501m=2Q~70. x+z=15~
150. A high molecular weight pluronic type nonionic activator represented by V=15 to 60), and furthermore, [1
It is in the range of 0-14. If the 1118 value is 6 or less, it has poor water solubility, and even in a small amount, it hardly dissolves in the imaging solution or is difficult to dissolve, so it cannot be said to be very practical. When the old-8 value is 15 or more, the solubility in the developer becomes very high, but the foaming property becomes large, and the resolution of fine patterns of 1 μm or less and resist residue and hem cut-off during development occur. v1 is 1118 value 10~
It is lower than that in the range of 14.

Furthermore, other nonionic surfactants used in the present invention include the following formula (III) (where A is -CH2-CH2-0-1D is -CH(CH
3) -CH2-0- or -CH2-CH1 (CM-CH
A tetronic type nonionic surfactant represented by 2-CH1 (C-150.Q-5-30) can be mentioned.

These pluronic type and tetronic type nonionic surfactants may be used alone or in combination of two or more types, and the amount added depends on the type, the type of resist, etc. Although it varies depending on the situation, it is usually 0.05OO1 to 0.5% by weight, preferably 0.05% by weight.
The range is from 0.004 to 0.08@% by weight.

Furthermore, in the present invention, the above-mentioned Pluronic type and/or
Alternatively, for the purpose of complementing the action of a tetronic type nonionic surfactant and improving the selectivity of the dissolution rate between the exposed area and the unexposed area, an alkyl group of the following formula % formula % () ~ 18 , X is an acid radical) (R5 is a perfurkyl group having 6 to 12 carbon atoms, E is -3O
2- or -co-1R6 is an alkylene group having 1 to 4 carbon atoms, R7 to R9 are hydrogen, lower alkyl group, or human[]oxy-substituted lower alkyl group, Y is 011
Quaternary ammonium type cationic surfactants represented by 18 alkyl groups, Z is 011 or 0COOH
It is possible to add a quaternary ammonium compound represented by

Both of these quaternary ammonium surfactants and quaternary ammonium-E nium compounds have a tendency to improve the selectivity ratio of dissolution rate between exposed and unexposed areas, but their effectiveness is limited. , there are subtle differences in characteristics, and the selection of these depends on the conditions of the individual lithography process, sensitivity (productivity), resist profile, critical resolution, or ultra-high purity of the developer. Optimization was once determined to satisfy numerous parameters, such as what items and parts to place the dried fish in (for example, halogen-free), and compatibility with each resist.

The amount of the quaternary ammonium type cationic surfactant or quaternary ammonium compound added is usually 0.0005 to 0.1% by weight, preferably 0.0% by weight.
It is within the range of 01 to 0.0511%.

To prepare the positive photoresist developer of the present invention,
Add a predetermined amount of a pluronic type nonionic surfactant and a quaternary ammonium type cationic surfactant or a quaternary ammonium compound to a quaternary ammonium hydroxide aqueous solution and dissolve uniformly. Just slack off.

[Examples] The present invention will be specifically described below based on Examples and Comparative Examples.

Example 1 Pluronic type nonionic surfactant of the general formula (I) with an average molecular weight of 2,050, an ethylene oxide weight ratio of 40% by weight, and a 11L8 value of 10.1 was added to an aqueous solution of 2.38 wt%-11. ．． The developer of Example 1 was prepared by adding 1M% of O5ff and 0.006% by weight of trimethyllauryl chloride.

Positive photoresist leaf PR-8 on silicon wafer
00 (manufactured by Tokyo Ohka Kogyo (fl)) was spin-coded and pre-baked on a hot plate at 110°C for 90 seconds to give a 1.5μ
A film thickness of m was obtained. This resist film was coated with a wavelength of 435 nm.
Exposure was carried out using a test pattern reticle on a stepper with an NA value of 0.35 (reduction projection type exposure apparatus manufactured by FL).

Next, using the developer of Example 1 above, the developer temperature was 25°C.
After developing with C for 30 seconds, rinsing with pure water and drying, 1.2 μm, 1.0 μm, and 0.8 μm on the wafer,
A cross-section of the line-and-space (hereinafter referred to as L/S) resist pattern was examined using a scanning electron microscope.
The images were taken at 0x magnification to observe the roundness of the pattern shape, resist residue and gaps between the lines (spaces) of the resist profile, resolution, etc. In addition, at this time, the appropriate exposure time at which the line and space ratio in L/S with a mask size of 1.0 μm was 1:1 was defined as the resist sensitivity (the exposure time to reproduce the resist pattern or the designed dimension was defined as the sensitivity). Further, the remaining film rate was measured using a Talystep film thickness meter. Roughly, 1. Comprehensively judge the condition of resist residue and hem breakage, resist 10 file, etc. marked F, and if the developability is particularly good, ◎, if it is good, if it is equivalent to O1, Δ, and worse than that. The case was evaluated as X. The results are shown in Table 1.

Compared to Comparative Example 1 using only the 2.38wt%-TMAIIM solution, when the developer of Example 1 was used, the resist sensitivity did not decrease much, the pattern shape was not rounded, and the residual film rate was improved. A sharp cross-sectional shape was obtained, and resist residue and hem breakage at the edges of the resist pattern were also very good.

Examples 2 to 8 In the same manner as in Example 1, developers of Examples 2 to 8 were prepared by adding the additives shown in Table 2 to 2.38 wt%-TM cold ice aqueous solution. The resist sensitivity and residual film rate were measured, and the developability was evaluated. The results are shown in Table 1.

Table 2 Example 2: 0PG-average molecular weight 1,750. Pluronic type nonionic surfactant of general formula (I) with ethylene oxide weight proportion 40 wt% and 11 [8 value 10.1... Old group...0.0
1wt% Same cationic surfactant as Example 1... Decoy... Dan... River... 0.002
wt% Example 3: Same Pluronic type nonionic surfactant as Example 2...0.02wt% Dimethyllaurylbenzylammonium chloride...0.001w1% Example 4: Same Pluronic type nonionic as Example 2 Surfactant: 0.05wt% methyl lauryl dihydroxyethylammonium chloride Group: Old:
・0.001Wtχ Example 5: Same Pluronic type nonionic surfactant as Example 1...0.05wt% (a+b
=15)・・・・・・・・・・・・・・・・・・
0.001wt% Example 5: 0PG-average molecular weight 1,2
Pluronic type nonionic surfactant of general formula (I) with 00, ethylene oxide weight proportion 4wt% and 11[B value of 11.5.
・0.02wt% trimethylcetylammonyram chloride・・・・・・・・・・・・o,
oozwt% Example 7: Same pluronic type nonionic surfactant as Example 1...0.05w1% Example 8
: Same pluronic type nonionic surfactant as Example 1...0.05wt% trimedel lauryl ammonium hydride...0.002wt
% Examples 9 to 12 Developing solutions of Examples 9 to 12 were prepared by adding the additives shown in Table 3 to a 4.6 wt % choline aqueous solution, and
The resist sensitivity and residual film rate were measured in the same manner as above, and the developability was evaluated. The results are shown in Table 1.

Table 3 Example 9: Same pluronic type nonionic surfactant as Example 1...0.04wt% Example 1
Same cationic surfactant as ・・・・・・・・・・・・・・・・・・・・・
...o, ooawt% Example 10: Same pluronic type nonionic surfactant as Example 2...0.02wt
% Same cationic surfactant as Example 4・・・・・・・・・・・・・・・・・・・・・
... o, oo 1wt% Example 11: Same pluronic type nonionic surfactant as Example 1 ... 0.04wt
% Same cationic surfactant as Example 7・・・・・・・・・・・・・・・・・・・・・
...0.004wt% Example 12: Same pluronic type nonionic surfactant as Example 2 ...0.01wt%
Quaternary ammonium compound same as Example 8・・・・・・・・・・・・0.0
04wt% Comparative Example 1 Only a 2.381M% aqueous solution of tetramethyl 7 ammonium hydroxide containing no additives (2°38wt%-
A developer consisting of aqueous solution of Group ^11) was used as the developer in Comparative Example 1, and evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 2 A developer consisting of only a 4.6 wt% aqueous solution of trimedelhydroxyethylaminium hydroxide (4.6 wt% choline aqueous solution) was used as the developer in Comparative Example 2, and the developer humidity was set to 30'. The evaluation was carried out in the same manner as in Example 1 except that it was set as C. The results are shown in Table 1.

Comparative Example 3 Evaluation was carried out in the same manner as in Example 1, except that the following nonionic surfactant was used in place of the Pluronic type nonionic surfactant used in Example 1. The results are shown in Table 1.

Compared to Example 1, there was almost no change in the residual film rate, but the resist sensitivity was significantly reduced. Furthermore, the profile near the limit resolution was also better in Example 1.

C9H19+O+C2H4-0+-T-H Number of moles of ethylene oxide added 420 11 [B value: 16.0 Comparative Example 4 The following nonionic surfactant was used in place of the Pluronitsa type nonionic surfactant used in Example 4. Except for this, evaluation was performed in the same manner as in Example 4. The results are shown in Table 1.

Cl2H250÷C2H4-0→-T-1-1 Number of moles of ethylene oxide added -20 11 [B value: 16.0 Comparative Example 5 The following non-ionic surfactant was used in place of the Pluronituta type nonionic surfactant used in Example 7. Evaluation was performed in the same manner as in Example 7 except that an ionic surfactant was used. The results are shown in Table 1.

Cl2H250+C2H4-0→-In the unlikely event that 1 ethylene oxide addition molar number crystal 20 +1 LB value: 16.0 Comparative Example 6 The following nonionic surfactant was used in place of the Pluronitsa type nonionic surfactant used in Example 9. Evaluation was carried out in the same manner as in Example 9 except that it was used. The results are shown in Table 1.

C9to119<di←0-(-C2H4-0÷-il+number of moles of ethylene oxide added -20 [1[B value: 16.0 Table 1 [Effects of the invention]] The positive photoresist developer of the present invention is , it has excellent wettability of the developer on the resist surface, and can improve the dissolution rate selectivity between exposed and unexposed areas, development defects, and edge breakage without reducing resist sensitivity. Moreover,
It has low foaming properties and is easy to use.

Claims (8)

[Claims] (1) A Pluronic type and/or Tetronic type nonionic surfactant with an HLB value of 6 to 15, which is made by adding ethylene oxide to polypropylene glycol and has an organic quaternary ammonium hydroxide aqueous solution as its main component, and quaternary ammonium A positive photoresist developer characterized by containing a type cationic surfactant or a quaternary ammonium compound. (2) The nonionic surfactant has the following general formula (I) or (
II) HO-A_l-B_m-A_n-H(I) HO-C_x-A_y-C_z-H(II) (In the formula, A is -CH_2-CH_2-O-, B is -CH(
CH_3)-CH_2-O-, C is -CH_2-CH(
CH_3)-O-, l+n=15~250, m=20~
70, x+z=15-150, y=15-60)
The developer for a positive photoresist according to claim 1, which is a high molecular weight pluronic nonionic surfactant represented by: (3) The nonionic surfactant has the following general formula (III) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) (In the formula, A is -CH_2-CH_2-O-, D is -CH (
CH_3)-CH_2-O- or -CH_2-CH(C
2. The positive photoresist developer according to claim 1, which is a Tetronic type nonionic surfactant represented by H_3)-O-, p=10 to 150, and q=5 to 30. (4) The amount of nonionic surfactant added is 0.001 to 0.
．． The positive photoresist developer according to claim 1, wherein the amount is within the range of 5% by weight. (5) The quaternary ammonium type cationic surfactant has the following general formula (IV) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (IV) (R_1 is a methyl group, R_2 is a methyl group, ▲ mathematical formula, chemical formula, There are tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (r = 1-15), R_3 is a methyl group, or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (s = 1-15), R_4
The developing solution for a positive photoresist according to claim 1, which is a cationic surfactant represented by the following formula: wherein X is an alkyl group having 6 to 18 carbon atoms, and X is an acid radical. (6) The quaternary ammonium type cationic surfactant has the following general formula (V) ▲ Numerical formula, chemical formula, table, etc. ▼ (V) (R_5 is a perfluoroalkyl group having 6 to 12 carbon atoms,
E is -SO_2- or -CO-, R_6 has 1 to 4 carbon atoms
, R_7 to R_9 are the same or different hydrogen, lower alkyl group or hydroxy-substituted lower alkyl group, and Y is OH or an acid radical. The developer for positive photoresist according to item 1. (7) The quaternary ammonium compound has the following general formula (VI) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VI) (In the formula, R_1_0 to R_1_2 are the same or different alkyl groups having 1 to 4 carbon atoms, R_1_3 has 8 or more carbon atoms
18. The positive photoresist developer according to claim 1, wherein Z is OH or OCOOH. (8) Quaternary ammonium type cationic surfactant and/or
Or the amount of quaternary ammonium compound added is 0.000
The positive photoresist developer according to claim 1, wherein the amount is in the range of 5 to 0.1% by weight.