JPH0451821B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] This invention relates to a developer for positive photoresists. [Conventional technology] In recent years, the integration density of integrated circuits has accelerated, and now so-called super LSIs with an integration density of 1 million or more
We are moving into an era of
Furthermore, it has entered the submicron region of 0.8 μm or less, and the requirements for this photolithography technology are becoming more severe year by year. 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 carboxylic acid groups are generated when irradiated with light. Becomes alkali soluble. For this reason, developing solutions for such positive photoresists are mainly based on quaternary ammonium bases that do not contain metal ions, such as tetramethylammonium hydroxide and trimethylhydroxyethylammonium hydroxide (choline). An organic quaternary ammonium hydroxide aqueous solution 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 ratio of dissolution rate between exposed and non-exposed areas of a positive photoresist. When it comes to fine patterns of 1 μm or less, the effect of the decrease in the resist film thickness of the resist pattern obtained after development becomes relatively large, resulting in an extreme decrease in resist profile and dimensional control accuracy, and small gaps between the resist patterns. Problems such as development defects (scum, resist residue) and hem cuts at the edges of resist patterns are also coming into focus. Therefore, in the past, a method of adding a quaternary ammonium type proton ionic surfactant for the purpose of improving the selectivity of dissolution rate (for example, JP-A-58
-9143), methods of adding non-ionic surfactants or certain organic solvents to remove resist residues, edge cuts, or improve wettability to photoresist films (for example, JP-A No. 58-57128). No., JP-A-59-182444, JP-A-61-167948, JP-A-62
-32453, Japanese Unexamined Patent Publication No. 62-67535, etc.) have been proposed. However, in a developer containing only a quaternary ammonium type cationic surfactant,
Although the dissolution selectivity for the exposed and non-exposed areas is good, a serious problem arises in that the 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. So-called stepper exposure has become mainstream, but as the degree of integration increases, the shapes that need to be drawn become more and more complex, and the number of exposures tends to increase. Decreased sensitivity requires longer exposure times, leading to a reduction in the throughput of the exposure process, which uses expensive machinery such as reduction projection exposure machines, and is a major hindrance to VLSI manufacturing. 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 resist residue and edge breakage, including wettability, are improved, but the difference between exposed and unexposed areas is improved. There is a disadvantage that the selectivity of dissolution rate is reduced. For this reason, the remaining film rate of the resist film decreases and the resist profile worsens, but this effect becomes relatively larger as the pattern size becomes finer, so it becomes a big problem when the pattern size becomes submicron. It becomes a point. Therefore, in order to compensate for these shortcomings and obtain practical improvements, methods of using cationic and nonionic surfactants in combination (for example, JP-A-61
-18944, Japanese Unexamined Patent Publication No. 61-151537, etc.) have been proposed. And in this method,
Basically, all of them have the following structural formula R(-CH ₂ -CH ₂ -O-) _l CH ₂ -CH ₂ -OH [wherein, R is an alkyl group having 10 to 20 carbon atoms or

A nonionic surfactant of the formula (R' is an alkyl group having 6 to 25 carbon atoms, l is an integer of 4 to 100) is employed. These are ether-based polyoxyethylene and special nonionic ether-based surfactants, which are commonly used as nonionic surfactants. It is true that developers using these nonionic surfactants have improved development characteristics such as resist residue and edge breakage, including wettability, but they have large foaming properties 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 inevitable. . 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 on development characteristics such as resist residue and edge cut-off can be improved. It almost never appears. Therefore, as a nonionic surfactant to be combined with a cationic surfactant, it has low foaming properties.
What is desired is a material that has great effects on resist residue, edge breakage, and wettability to photoresist films, and that does not reduce the selectivity between exposed and unexposed areas 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 between exposed and unexposed areas without reducing resist sensitivity. It is an object of the present invention to provide a low-foaming positive photoresist developer that has improved speed selectivity, poor development, and edge breakage. [Means for Solving the Problems] That is, the present invention provides an HLB which contains an organic quaternary ammonium hydroxide aqueous solution as a main component and has ethylene oxide added to polypropylene glycol represented by the following general formulas () and (). Pluronic type and/or Tetronic type nonionic surfactants having a value of 6 to 14 and represented by the following general formula (), hydrocarbon-based cationic surfactants represented by the following general formula (), and the following: A positive type characterized by containing a fluorine-based cationic surfactant represented by the general formula () or a quaternary ammonium compound represented by the following general formula () that does not substantially contain a halogen atom. Developer for photoresist. General formula (), () HO−A _l −B _n −A _o −H () HO−C _x −A _y −C _z −H () (In the formula, A is −CH ₂ −CH ₂ −O−, B is -CH
( _CH3 ) _-CH2 -O-, C is _-CH2 -CH( _CH3 )-
O-, l+n=15~100, m=20~70, x+z=
15-100, y=15-60) General formula () (In the formula, A is -CH ₂ -CH ₂ -O-, D is -CH
( _CH3 ) _-CH2 -O- or _-CH2 -CH( _CH3 )-O
−, p=10 to 50, q=5 to 30) General formula () (In the formula, R ₁ is a methyl group, R ₂ is a methyl group,

[Formula] or (-CH ₂ -CH ₂ -O-) _r H. (r=1-15) R ₃ is a methyl group or (-CH ₂ -CH ₂ -
O-) _s H (s = 1 to 15), R ₄ is an alkyl group having 6 to 18 carbon atoms, and X is an acid group] (In the formula, R ₅ is a perfluoroalkyl group having 6 to 12 carbon atoms, E is -SO ₂ - or -CO-, R ₆ is an alkylene group having 1 to 4 carbon atoms, and R ₇ to _{R 9} are the same or different hydrogen, lower alkyl group or hydroxy-substituted lower alkyl group, Y is OH or acid radical) General formula () (In the formula, R ₁₀ to _{R 12} are the same or different alkyl groups having 1 to 4 carbon atoms, R ₁₃ is an alkyl group having 8 to 18 carbon atoms, and Z is OH or HCO ₃ ) In the present invention, as the main component The organic quaternary ammonium hydroxide aqueous solution used has the following general formula: (However, in the formula, R ₁₄ to _{R 17} are the same or different alkyl groups having 1 to 3 carbon atoms or hydroxy-substituted alkyl groups.)
% by weight, preferably 1 to 5.5% by weight aqueous solution,
Specifically, tetramethylammonium hydroxide (TMAH), trimethylhydroxyethylammonium hydroxide (choline),
Examples include methyltrihydroxyethylammonium hydroxide, dimethyldihydroxyethylammonium hydroxide, tetraethylammonium hydroxide, trimethylethylammonium hydroxide, etc., but TMAH and choline are preferable from the viewpoint of pH, production, economics, etc. It is an aqueous solution. The nonionic surfactant used in the present invention is a high molecular weight Pluronic type nonionic surfactant represented by the general formula () or (), and has an HLB value in the range of 6 to 14, Preferably it is in the range of 10-14. If the HLB value is 6 or less, the water solubility is poor, and even in a small amount, it hardly dissolves in the developer or is difficult to dissolve, so it is not very practical. If the HLB value exceeds 14, the solubility in the developer will be very high, but the foaming property will increase, and the resolution of fine patterns of 1 μm or less and development characteristics such as resist residue and edge breakage will decrease. This is lower than those with HLB values in the range of 10 to 14. Further, the nonionic surfactant used in the present invention is a Tetronic type nonionic surfactant represented by the above general formula (). These Pluronik-type and Tetronik-type nonionic surfactants may be used alone or in combination of two or more, and the amount added depends on the type or type of resist. It varies, but usually 0.001
It ranges from ~0.5% by weight, preferably from 0.004 to 0.08% by weight. Furthermore, in the present invention, in order to complement the action of the Pluronic type and/or Tetronic type nonionic surfactant and improve the selectivity of dissolution rate between the exposed area and the unexposed area, A hydrocarbon-based quaternary ammonium-type cationic surfactant represented by the general formula () or a fluorine-based quaternary ammonium-type cationic surfactant represented by the general formula (), or a fluorine-based quaternary ammonium-type cationic surfactant represented by the general formula ( ) can be added. Both of these quaternary ammonium surfactants and quaternary ammonium compounds have the function of improving the selectivity ratio of dissolution rate between exposed and unexposed areas, but their effectiveness and properties are delicate. There are many differences, and these choices depend on the specific lithography process conditions, sensitivity (productivity), resist profile, resolution limit, or ultra-high purity of the developer (e.g., halogen-free). ), which items and parts to focus on, and compatibility with individual resists.Optimization is once determined to satisfy a large number of parameters. The amount of the quaternary ammonium type cationic surfactant or quaternary ammonium compound added is usually in the range of 0.0005 to 0.1% by weight, preferably 0.001 to 0.05% by weight. To prepare the positive photoresist developer of the present invention, a Pluronic type nonionic surfactant and a quaternary ammonium type cationic surfactant or a quaternary ammonium compound are added to the organic quaternary ammonium hydroxide aqueous solution. may be added in a predetermined amount and uniformly dissolved. [Examples] The present invention will be specifically described below based on Examples and Comparative Examples. Example 1 2.38wt%-TMAH aqueous solution with OPG-average molecular weight
2050 and ethylene oxide weight percentage 40% and
Adding 0.05% by weight of a Pluronic type nonionic surfactant of the general formula () with an HLB value of 10.1 and 0.006% by weight of trimethyllauryl ammonium chloride,
A developer solution according to Example 1 was prepared. Positive photoresist on silicon wafer
Spin coat OFPR-800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) and pre-bake on a hot plate for 90 seconds at 110°C.
A film thickness of 1.5 μm was obtained. This resist film is
Exposure was performed using a test pattern reticle at 436 nm and a stepper (reduction projection type exposure device manufactured by Nikon Corporation) with an NA value of 0.35. Next, using the developer of Example 1 above, development was performed for 30 seconds at a developer temperature of 25°C, and after 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 photographed at 20,000x using a scanning electron microscope, and the roundness of the pattern shape,
Resist residue, edge breakage, resolution, etc. between the lines (spaces) of the resist profile were observed. In addition, at this time, the mask size is 1.0μ
The appropriate exposure time at which the line and space ratio in L/S of m was 1:1 was defined as the resist sensitivity (the exposure time at which the resist pattern reproduced the design dimensions was defined as the sensitivity). Further, the remaining film rate was measured using a Talystep film thickness meter. Furthermore, based on Comparative Example 1 described below, which was developed using a developer consisting only of a 2.38wt%-TMAH aqueous solution, the resist residue, edge breakage, resist profile, etc. were comprehensively judged, and the development was performed. ◎ if the performance is particularly good,
The evaluation was rated as ◯ if it was good, △ if it was the same, and × if it was worse. In addition, for each developer, the degree of foaming (the height of the foam immediately after) and the stability of foam (5
The foam height after 1 minute was measured. When compared with Comparative Example 1 using only the 2.38wt%-TMAH aqueous 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, the additives shown in Table 2 were added to a 2.38wt%-TMAH aqueous solution to prepare the developers of Examples 2 to 8, and the developer solutions were prepared in the same manner as in Example 1 above. 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: OPG - Pluronic type nonionic surfactant of general formula () with average molecular weight 1750, ethylene oxide weight proportion 40wt% and HLB value 10.1 ...0.01wt% Same cationic interface as Example 1 activator
...0.002wt% Example 3: Same Pluronic type nonionic surfactant as Example 2 ...0.02wt% Dimethyllaurylbenzylammonium chloride ...0.001wt% Example 4: Same Pluronic type nonionic interface as Example 2 Activator: 0.05wt% Methyl lauryl dihydroxyethylammonium chloride: 0.001wt% Example 5: Same Pluronic type nonionic surfactant as in Example 1: 0.05wt% (a + b = 15) ...0.001wt% Example 6: OPG - Pluronic type nonionic surfactant of general formula () with average molecular weight 1200, ethylene oxide weight proportion 40wt% and HLB value 11.5 ...0.02wt% trimethylcetyl Ammonium chloride...0.002wt% Example 7: Same Pluronic type nonionic surfactant as Example 1...0.05wt% [C ₈ F ₁₇ SO ₂ NHC ₃ H ₆ N(CH ₃ ) ₃ ] ^{+ -}
...0.005wt% Example 8: Same Pluronic type nonionic surfactant as in Example 1 ...0.05wt% Trimethyllauryl ammonium hydride ...0.002wt% Examples 9 to 12 4.6wt% - Table 3 in choline aqueous solution Developing solutions of Examples 9 to 12 were prepared by adding the additives shown below, and the resist sensitivity and residual film rate were measured in the same manner as in Example 1, 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% Same cationic surfactant as Example 1
...0.004wt% Example 10: Pluronic type nonionic surfactant as in Example 2 ...0.02wt% Same cationic surfactant as in Example 4
...0.001wt% Example 11: Pluronic type nonionic surfactant as in Example 1 ...0.04wt% Same cationic surfactant as in Example 7
...0.004wt% Example 12: Same Pluronic type nonionic surfactant as Example 2 ...0.01wt% Same quaternary ammonium compound as Example 8 ...0.004wt% Examples 13-14 Example 1 and Similarly, developers of Examples 13 to 14 were prepared by adding the additives shown in Table 4 to a 2.38 wt% TMAH aqueous solution, and various measurements and evaluations were also performed.
The results are shown in Table 1. Table 4 Example 13: OPG - Tetronic type nonionic surfactant with average molecular weight 3000 and ethylene oxide weight percentage 40wt%...0.01wt% Same cationic surfactant as Example 1
...0.001wt% Example 14: Same Tetronic type nonionic surfactant as Example 13 ...0.04wt% Same cationic surfactant as Example 8
…0.004wt% Comparative Example 1 Only 2.38wt% aqueous solution of tetramethylammonium hydroxide without additives (2.38wt%
%-TMAH aqueous solution) in Comparative Example 1.
It was evaluated in the same manner as in Example 1. The results are shown in Table 1. Comparative Example 2 Trimethylhydroxyethylammonium hydroxide 4.6 wt% aqueous solution only (4.6 wt% -
Evaluation was made in the same manner as in Example 1, except that a developer consisting of a choline aqueous solution was used as the developer in Comparative Example 2, and the developer temperature was 30°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. Number of moles of ethylene oxide added≒20 HLB value: 16.0 Comparative Example 4 Evaluation was performed in the same manner as in Example 4, except that the following nonionic surfactant was used in place of the Pluronic type nonionic surfactant used in Example 4. did. The results are shown in Table 1. C ₁₂ H ₂₅ O(-C ₂ H ₄ -O-) _o H Number of moles of ethylene oxide added≒20 HLB value: 16.0 Comparative Example 5 The following nonionic surfactant was used in place of the Pluronic type nonionic surfactant used in Example 7. Evaluation was conducted in the same manner as in Example 7 except that an ionic surfactant was used. The results are shown in Table 1. C ₁₂ H ₂₅ O(-C ₂ H ₄ -O-) _o H Number of moles of ethylene oxide added≒20 HLB value: 16.0 Comparative Example 6 The following nonionic surfactant was used in place of the Pluronic type nonionic surfactant used in Example 9. Evaluation was conducted in the same manner as in Example 9 except that an ionic surfactant was used. The results are shown in Table 1. Number of moles of ethylene oxide added≒20 HLB value: 16.0 Comparative Example 7 In place of the Pluronic type nonionic surfactant used in Example 1, OPG-average molecular weight 3250, ethylene oxide weight percentage 80wt%, and general formula (14.1) with HLB value: ) Pluronic type nonionic surfactant was added at a ratio of 0.01% by weight, and the same cationic surfactant as in Example 1 was added in an amount of 0.001% by weight, but the measurement was carried out in the same manner as in Example 1. I conducted an evaluation. The results are shown in Table 1. Comparative Example 8 Measurements and evaluations were carried out in the same manner as in Comparative Example 7, except that the amount of Pluronic nonionic surfactant added in Comparative Example 7 was 0.01% by weight, and the amount of cationic surfactant added was 0.004% by weight. I went. The results are shown in Table 1. Reference Examples 1-2 For reference, 2.38wt%-TMAM aqueous solution,
A developing solution containing only the Pluronic type nonionic surfactant of Example 1 (Reference Example 1) and a developing solution containing only the Tetronic type nonionic surfactant of Example 13 (Reference Example 2) were prepared, These developing solutions were measured and evaluated in the same manner as in Example 1. The results are shown in Table 1.

【table】

[Table] Examples 15 to 18 and Comparative Examples 9 to 12 2.38wt%-TMAH aqueous solution containing the types shown in Table 5,
A developing solution was prepared by adding a Pluronic type nonionic surfactant according to the HLB value and proportion, and the foaming property was measured in the same manner as in Example 1. In addition, a substrate on which a positive photoresist film was formed on a silicon wafer was prepared in the same manner as in Example 1, and each developer was dropped onto this substrate. The contact angle was measured.
Furthermore, each developer was heated to a temperature above the cloud point to make it cloudy, and then gradually cooled, and the temperature at which the solution became transparent was determined as the cloud point. These results are shown in Table 5.

[Table] From the results in Table 5, those with HLB values within the range of 6 to 14 (Examples 15 to 18) have a lower incidence than those with HLB values over 14 (Comparative Examples 11 and 12). It is foamy (low foaming and easy to remove bubbles) and has a small contact angle, so the developer spreads quickly and uniformly on the substrate, making it easy to use, and there is no risk of developing defects due to the effects of bubbles. It is also recognized that this method is effective in improving the wettability of the developer to the resist film. In addition, the foaming properties of the developing solutions of Comparative Examples 11 and 12 were only slightly reduced in the height of the foam immediately after and after 5 minutes, indicating that the generated foam was difficult to disappear. There is. In addition, those with HLB values in the range of 6 to 14 have cloud points of 40°C or higher, whereas those with HLB values lower than 6 (Comparative Examples 9 and 10) both have cloud points of 29°C. , showing a low value. This cloud point is a temperature specific to nonionic surfactants (it varies somewhat depending on the concentration and external conditions), and below this cloud point, the surfactant is water (here, developer: 2.38 wt%). It is a guideline that it dissolves well in TMAH aqueous solution), but becomes poorly soluble above the cloud point. Further, although the developer is generally used at room temperature, in consideration of transportation and storage of the developer in the summer, it is desired that the cloud point be 40° C. or higher. Therefore, those with an HLB value lower than 6 (Comparative Example 9,
10) has a low clouding point, which means that the solution becomes cloudy when the liquid temperature exceeds 30°C.In this regard, if the HLB value is within the range of 6 to 14, the solution becomes cloudy during the development stage. There are no such problems. [Effects of the Invention] The positive photoresist developer of the present invention has excellent wettability of the developer to the resist surface,
It is possible to improve the dissolution rate selectivity between exposed and unexposed areas, poor development, and edge breakage without reducing resist sensitivity, and it also has low foaming properties and is easy to use (e.g., The developer can be supplied stably without any problems caused by the generation of bubbles during supply circulation, and there is no risk of poor development caused by bubbles present in the developer.

Claims (1)

[Scope of Claims] 1 Pluronic type and/or polypropylene glycol having an HLB value of 6 to 14 and/or containing an organic quaternary ammonium hydroxide aqueous solution as a main component and adding ethylene oxide to polypropylene glycol represented by the following general formulas () and (). Or Tetronic type nonionic surfactant represented by the following general formula (), hydrocarbon-based cationic surfactant represented by the following general formula (), fluorine represented by the following general formula () 1. A positive photoresist developer characterized by containing a cationic surfactant or a quaternary ammonium compound represented by the following general formula () and substantially free of halogen atoms. General formula (), () HO−A _l −B _n −A _o −H () HO−C _x −A _y −C _z −H () (In the formula, A is −CH ₂ −CH ₂ −O−, B is -CH
( _CH3 ) _-CH2 -O-, C is _-CH2 -CH( _CH3 )-
O-, l+n=15~100, m=20~70, x+z=
15-100, y=15-60) General formula () (In the formula, A is -CH ₂ -CH ₂ -O-, D is -CH
( _CH3 ) _-CH2 -O- or _-CH2 -CH( _CH3 )-O
−, p=10 to 50, q=5 to 30) General formula () (In the formula, R ₁ is a methyl group, R ₂ is a methyl group,
[Formula] or (-CH ₂ -CH ₂ -O) - _r H. (r=1-15) R ₃ is a methyl group or (-CH ₂ -CH ₂ -
O) _-s H (s=1 to 15), _R4 is an alkyl group having 6 to 18 carbon atoms, and X is an acid radical] General formula () (In the formula, R ₅ is a perfluoroalkyl group having 6 to 12 carbon atoms, E is -SO ₂ - or -CO-, R ₆ is an alkylene group having 1 to 4 carbon atoms, and R ₇ to _{R 9} are the same or different hydrogen, lower alkyl group or hydroxy-substituted lower alkyl group, Y is OH or acid radical) General formula () (In the formula, R ₁₀ to _{R 12} are the same or different alkyl groups having 1 to 4 carbon atoms, R ₁₃ is an alkyl group having 8 to 18 carbon atoms, and Z is OH or HCO ₃ ) 2 Nonionic surfactant The amount added is 0.001 to 0.5
The developer for a positive photoresist according to claim 1, which is within the range of % by weight. 3 The amount of quaternary ammonium type cationic surfactant and/or quaternary ammonium compound added is
The positive photoresist developer according to claim 1, wherein the amount is in the range of 0.0005 to 0.1% by weight.