JP2935306B2 - Acid-decomposable compound and positive-type radiation-sensitive resist composition containing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation-sensitive resist composition which is sensitive to radiation such as ultraviolet rays, far ultraviolet rays, electron beams, and X-rays.
The present invention relates to an alkali-developable positive-type radiation-sensitive resist composition for fine processing used in the production of semiconductor integrated circuits and masks such as I.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of semiconductor integrated circuits and the like, a resist is applied to a substrate such as a silicon wafer, which is irradiated with radiation through a mask and developed to form a fine pattern, and then the pattern is formed. Processing of a substrate portion is performed using the same. At present, g-rays (436 nm) and i-rays (365 nm) are used in the exposure apparatus. In recent years, with the increase in integration of integrated circuit elements, far ultraviolet rays such as excimer lasers with higher resolution, electron beams, The use of X-rays and the like is being studied, and the demand for resist materials sensitive to these radiations is increasing. As the resist currently used, a positive resist and a negative resist are known.

As a negative resist composition which is sensitive to radiation such as far ultraviolet rays, electron beams and X-rays, a chloromethylated polystyrene or a resin composition containing chlorinated polymethylstyrene using polystyrene as a main polymer is known. In general, development with an aqueous alkali solution is advantageous in order to increase the resolution.However, these compositions have the advantages of high sensitivity and excellent dry etching resistance. It has the disadvantage that the transfer pattern is distorted by the influence of swelling and the resolution is inferior due to peeling of the film.

As the positive resist composition, polymethyl methacrylate and polyolefin sulfone are known, but the former is excellent in resolution but has very low sensitivity, and the latter has high sensitivity but cannot be dry-etched. have. Attempts have also been made to use oxydiazo compounds such as Meldrum's acid and dimedone as disclosed in U.S. Pat. No. 4,339,522 and Chemische Berichte 92, 130 (19959) as positive resist compositions. These compositions have good resolution and good dry etching resistance in an alkali developing type, but are unstable to thermal load, and a considerable amount is lost due to sublimation of the oxyazo compound during prebaking. There is a disadvantage that.

On the other hand, a compound in which a hydroxy group of a polyvinyl phenol resin is partially substituted with a tertiary butoxycarbonyl group (hereinafter referred to as a tBOC group) as an alkali-soluble resin and a compound which generates an acid upon irradiation (hereinafter referred to as an acid generator) And a positive resist composition comprising a polyvinyl tert-butyl benzoate resin and an acid generator (Procee)
dings SPIE, 1086, 11 (1989)). In the former composition, it is known that the tBOC group is efficiently eliminated by the generated acid, but there is a drawback that the difference in dissolution rate with respect to the alkali developing solution between the irradiated part and the unirradiated part is hardly obtained, and the resolution is inferior. doing. Further, in the latter composition, polyvinyl tert-butyl benzoate is decomposed by the generated acid to produce polyvinyl benzoic acid, but the decomposition rate is generally slow, and as a result, there is a disadvantage that it is difficult to increase the sensitivity.

On the other hand, a positive resist composition comprising a novolak resin as an alkali-soluble resin and a tertiary butoxycarbonylated bisphenol A as an acid-decomposable compound and an acid generator is known (Proceedings SPIE, 920, 6).
0 (1988)). Tertiary butoxycarbonylated bisphenol A is decomposed by the generated acid to increase the alkali solubility of the novolak resin. However, since the effect of suppressing the dissolution of tertiary butoxycarbonylated bisphenol A is low, the alkali developing solution in the irradiated and unirradiated portions is low. However, there is a disadvantage that the difference in dissolution rate is difficult to obtain and the resolution is inferior.

[0007]

Alkali development for fine processing which is sensitive to radiation such as far ultraviolet rays, electron beams and X-rays, has excellent sensitivity, residual film ratio, good heat resistance and good dry etching resistance. There is a need for the development of a possible positive radiation sensitive resist composition.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and have arrived at the present invention. That is, the present invention provides:

[0009]

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[0010] (Wherein R in the formula (1) represents hydrogen or a methyl group). (2) An alkali-soluble resin, a compound capable of generating an acid in response to radiation and a compound represented by the formula (1) described in the above (1). A positive-working radiation-sensitive resist composition comprising

The present invention will be described in detail. The compound represented by the formula (1) of the present invention exhibits acid-decomposability, and has a remarkably large effect of suppressing the solubility of an alkali-soluble resin in an alkali developing solution as compared with the above-mentioned tert-butoxycarbonylated bisphenol A. It can be made sufficiently insoluble in an alkali developing solution. (See FIG. 1) The compound represented by the formula (1) is easily decomposed (acid-decomposable) by an acid generated from an acid generator upon irradiation with radiation, and is converted into a phenol derivative. As a result, the solubility in the alkali developing solution is increased, and the difference in the dissolving rate in the alkali developing solution between the irradiated portion and the non-irradiated portion is increased, so that a transfer pattern with high contrast can be obtained.

The compound represented by the formula (1) of the present invention is represented by the formula (2)

[0013]

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(Wherein R in the formula (2) represents hydrogen or a methyl group) and di-t-dicarbonate
It can be obtained by a condensation reaction with butyl. That is, 1 equivalent of the compound represented by the formula (2) and 2 to 4 equivalents of di-t-butyl dicarbonate are dissolved in an organic solvent such as tetrahydrofuran, diethyl ether, acetone, methyl ethyl ketone, dioxane, benzene, and toluene. To the mixture are added 1 to 10 equivalents of a base such as triethylamine, pyridine, dimethylaniline, diethylaniline, diazabicycloundecene, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate and the like.
The mixture is heated and condensed at a temperature of 0 ° C. for 1 to 40 hours. Then, the solvent of the reaction solution is distilled off, a water-soluble solvent such as acetone, methanol, ethanol or the like is added, the solution is poured into water, and the precipitated product is filtered, washed with water and dried to obtain the desired product. . When a water-soluble solvent is used for the reaction solution, the desired product can be obtained by pouring the reaction solution into water, filtering the precipitated product, washing with water and drying.

Specific examples of the compound represented by the formula (1) include tris (4-tert-butoxycarbonyloxyphenyl) methane and bis (4-tert-butoxycarbonyloxy-3-methylphenyl) -4-tert-butyl. Butoxycarbonyloxyphenylmethane. These acid-decomposable compounds can be used alone or in combination.

The alkali-soluble resin used in the positive radiation-sensitive resist composition of the present invention includes phenol novolak resin, cresol novolak resin, polyvinyl phenol, methyl (meth) acrylate- (meth) acrylate.
Acrylic acid copolymer, styrene-maleic acid copolymer and the like can be mentioned, and all those which are soluble in alkali and compatible with the acid-decomposable compound represented by the formula (1) can be used.

The acid generator which forms or releases an acid upon irradiation with radiation used in the positive radiation-sensitive resist composition of the present invention includes a large number of compounds and mixtures thereof. These include diazonium salts, iodonium salts, sulfonium salts, phosphonium salts, selenonium salts, arsonium salts, metallocene complexes, halogen compounds and sulfonic acid esters. Specific examples of these compounds include Journal of Photopolymer Science and
Technology, 2 (2), (1989), pages 283 to 284, described as photoacid generators, but are not limited to compounds that generate an acid upon irradiation. be able to.

In the present invention, the content ratio of each component, when the total solid content is 100 parts by weight, the alkali-soluble resin is 60 to 90 parts by weight, preferably 65 to 85 parts by weight or represented by the formula (1). 5 to 40 parts by weight of the compound,
It is preferable that the acid generator is contained in an amount of 0.1 to 15 parts by weight, preferably 0.5 to 10 parts by weight, more preferably 10 to 30 parts by weight. Outside the above range, the sensitivity, pattern shape, resolution, alkali solubility and dry etching resistance are adversely affected, which is not preferable.

The positive-working radiation-sensitive resist composition of the present invention is usually used by dissolving it in an organic solvent in the form of a photosensitive solution. As the organic solvent used at this time, ethyl cellosolve acetate, methyl cellosolve acetate, propylene glycol methyl ether acetate, (ethoxypropyl) acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, methyl cellosolve, ethyl cellosolve, butyl acetate, amyl acetate, Examples thereof include methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl lactate, ethyl lactate, and butyl lactate. These may be used alone or as a mixture of two or more.

The positive-working radiation-sensitive resist composition of the present invention further comprises additives such as a spectral sensitizer, a plasticizer, a photochromic agent, a dye, an adhesion improver, and a surfactant, depending on the application. be able to.

Next, a method for forming a fine pattern using the composition thus obtained will be described. The composition of the present invention is dissolved in the above-mentioned solvent so that the solid content concentration is 5 to 60%, preferably 10 to 40%, and if necessary, the above-mentioned additives are added. The insoluble matter is removed to obtain a photosensitive solution. This photosensitive solution is first applied onto a substrate such as a silicon wafer or a chromium vapor-deposited plate with a spinner or the like to obtain a uniform film.
After drying the coating film by baking at a temperature of 0 to 130 ° C., preferably 80 to 120 ° C., it is irradiated with radiation such as ultraviolet rays, electron beams, and X-rays if necessary using a mask. 120 ° C, preferably 80 to 1
A fine pattern can be transferred onto the substrate by heating at a temperature of 10 ° C., performing a sensitization reaction treatment, and then developing with an aqueous alkali solution having a suitable concentration.

The heat treatment after irradiation is a treatment for sensitizing the sensitivity of the positive-working radiation-sensitive resist composition.
It is preferable to carry out this in order to achieve the object of the present invention. If the processing temperature is lower than 70 ° C., practical sensitivity cannot be obtained. If the processing temperature exceeds 120 ° C., there is a possibility that the transfer pattern becomes thin and a good pattern cannot be obtained.

In the positive radiation-sensitive resist composition of the present invention, an aqueous solution of an organic alkali such as tetramethylammonium hydroxide, triethylamine and triethanolamine, sodium hydroxide,
Although an aqueous solution of an inorganic alkali such as potassium hydroxide, sodium carbonate, or potassium carbonate can be used, it is preferable to use an aqueous solution of an organic alkali in the integrated circuit manufacturing process. Substrates subjected to heat treatment after irradiation are treated with these developing solutions at 10 ° C. to 35 ° C., preferably 15 ° C.
A resist pattern can be obtained by developing at a temperature of 1 to 30 ° C. for 1 to 30 minutes, preferably 0.5 to 10 minutes.

The positive-working radiation-sensitive resist composition of the present invention has high sensitivity to radiation, and the transferred pattern has no swelling, is extremely excellent in resolution, and is also extremely excellent in dry etching resistance and heat resistance.

[0025]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 Tris (4-tert-butoxycarbonyloxyphenyl)
Synthesis of methane Tris (4-hydroxyphenyl) methane 5.0 g
(17.1 mmol) and di-t-butyl dicarbonate 1
1.5 g (52.7 mmol) in tetrahydrofuran
Dissolved in 30 ml. Next, 5.3 g (52.4 mmol) of triethylamine was added to this solution, and the mixture was heated under reflux for 8 hours. The reaction solution was cooled to room temperature and poured into water, whereby white crystals precipitated. This was collected by filtration, washed with water, and dried in vacuo to obtain 8.6 g of the desired product.

Next, the analysis data of this is shown. (B) Melting point 100-102 ° C (b) Mass * 1 (M + 1) / e = 593 (c) 1 H NMR * 2 δ 1.56 ppm (s, 27H), 5.52
(s, 1H), 7.08 (s, 12H) (d) UV * 3 λmax 273,265nm

* 1 Mass is an abbreviation for mass spectrum.
Measured by chemical ionization method and detected (M + 1) ion.
The same applies to the following embodiments. * 2 1 H NMR is an abbreviation for proton nuclear magnetic resonance spectrum. CDCl ₃ solvent. Tetramethylsilane standard. The same applies to the following embodiments. * 3 UV is an abbreviation of electronic spectrum. Ethanol solvent.
The same applies to the following embodiments.

Example 2 Synthesis of bis (4-tert-butoxycarbonyloxy-3-methylphenyl) -4-tert-butoxycarbonyloxyphenylmethane bis (4-hydroxy-3-methylphenyl) -4-hydroxyphenylmethane 3.0 g (9.36 mmo
l) and di-t-butyl dicarbonate 6.4 g (29.3 mm)
ol) was dissolved in 30 ml of tetrahydrofuran.
Then 4.4 g of diazabicycloundecene was added to this solution.
(28.9 mmol) was added, and the mixture was heated and refluxed for 3 hours. After the solvent was distilled off, 50 ml of methanol was added, and the mixture was poured into water to precipitate a white solid. This was collected by filtration, washed with water, and dried under vacuum to obtain 4.4 g of the desired product.

Next, the analysis data of this is shown. (B) Glass transition point 52 ° C (b) Decomposition point 174 ° C (c) Mass (M + 1) / e = 621 (d) 1 H NMR δ 1.55 ppm (s, 27H), 2.16
(s, 6H), 5.43 (s, 1H), 6.88 (dd, J = 8.3,2.2Hz, 2H), 6.96 (d, J
= 2.2Hz, 2H), 6.98 (d, J = 8.3Hz, 2H), 7.08 (s, 4H) (e) UV λmax 274,267nm

Example 3 80 parts by weight of m, p-cresol novolak resin having a weight average molecular weight of 10,000, 3 parts by weight of triphenylsulfonium trifluoromethanesulfonate as an acid generator, and the above tris as an acid-decomposable compound of the present invention 17 parts by weight of (4-tert-butoxycarbonyloxyphenyl) methane are dissolved in ethyl lactate so that the concentration of the total solid content thereof is 24%, and the obtained solution is 0.2 μm in pore size.
A photosensitive solution was obtained by pressure filtration using a membrane filter of No.

Next, the photosensitive solution thus obtained was applied to a chromium-deposited substrate, which had been subjected to a surface treatment by a known method, onto a chromium-deposited substrate.
Spin coating was performed with a spin coater at 00 rpm for 30 seconds and dried on a hot plate having a surface temperature of 100 ° C. for 90 seconds to obtain a resist layer having a thickness of 1.0 μm. Then, ELS-3 manufactured by Elionix, Inc. was added to the resist layer.
1. Using a 300 electron beam lithography system at an acceleration voltage of 20 kV.
After irradiating with an electron beam having an energy of ³ μC / cm ^2, a heating sensitization reaction was performed for 300 seconds on a hot plate having a surface temperature of 90 ° C., and an aqueous solution of 2.38 wt% tetramethylammonium hydroxide was added at 120 ° C. The pattern was obtained by dissolving and removing the electron beam irradiated portion by immersing for 2 seconds. This transfer pattern had a residual film of 95% or more and had a rectangular cross section. The minimum line width is 0.3
It was confirmed that it had a resolution of μm.

Example 4 65.0 parts by weight of a styrene-maleic acid monomethyl ester copolymer having a weight average molecular weight of 20,000, 1.0 part by weight of diphenyliodonium-trifluoromethanesulfonate as an acid generator and an acid of the present invention As a decomposable compound, 30 parts by weight of bis (4-tert-butoxycarbonyloxy-3-methylphenyl) -4-tert-butoxycarbonyloxyphenylmethane has a total solid concentration of 20%.
Was dissolved in ethyl cellosolve acetate so as to obtain a photosensitive solution by subjecting the resulting solution to pressure filtration using a membrane filter having a pore size of 0.2 μm.

Next, the photosensitive solution thus obtained was applied to a silicon substrate which had been subjected to a surface treatment by a known method, for 4,000 hours.
Spin coating was performed with a spin coater at 0 rpm for 30 seconds, and dried on a hot plate having a surface temperature of 80 ° C. for 60 seconds to obtain a resist layer having a thickness of 1.0 μm. Next, the resist layer was irradiated with ultraviolet light having a wavelength of 254 nm through a mask on which a pattern was drawn, and then subjected to a heat sensitization reaction on a hot plate having a surface temperature of 80 ° C. for 300 seconds to obtain a 2.38 wt. By immersing in a methylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, the ultraviolet irradiation part was dissolved and removed to obtain a pattern. This transfer pattern had a residual film of 90% or more and had a rectangular cross section. It was also confirmed that the minimum line width had a resolution of 0.35 μm.

Example 5 Polyvinylphenol 8 having a weight average molecular weight of 25,000
5 parts by weight, 9,10-diethoxyanthracene-2-sulfonic acid-p-nitrobenzyl ester as an acid generator and tris (4) as an acid-decomposable compound of the present invention.
-Tert-butoxycarbonyloxyphenyl) methane 10
A weight part was dissolved in diethylene glycol dimethyl ether so that the solid content concentration became 20%, and the obtained solution was subjected to pressure filtration using a membrane filter having a pore diameter of 0.2 μm to obtain a photosensitive solution.

Next, the photosensitive solution thus obtained was applied to a silicon substrate which had been subjected to a surface treatment by a known method, to 4,000.
The resist was spin-coated with a spin coater at 30 rpm for 30 seconds and dried on a hot plate having a surface temperature of 110 ° C. for 60 seconds to obtain a resist layer having a thickness of 1.0 μm. Next, this resist layer was irradiated with ultraviolet light having a wavelength of 365 nm through a mask on which a pattern was drawn, and then subjected to a heat sensitization reaction on a hot plate having a surface temperature of 80 ° C. for 600 seconds to obtain a 1.0 wt. By immersing in a methylammonium hydroxide aqueous solution at 23 ° C. for 60 seconds, the ultraviolet irradiation part was dissolved and removed to obtain a pattern. This transfer pattern had a residual film of 90% or more and had a rectangular cross section. It was also confirmed that the minimum line width had a resolution of 0.40 μm.

[0037]

The acid-decomposable compound of the present invention is easily decomposed by an acid generated by irradiation with radiation, and a positive-type radiation-sensitive resist composition using the compound has high sensitivity to radiation and a pattern transferred to a substrate. Is extremely useful in the production of semiconductor integrated circuits because it has no swelling, has extremely excellent resolution, and has extremely excellent dry etching resistance and heat resistance.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between inhibitor / solid content and dissolution rate. In FIG. 1, the horizontal axis is the inhibitor / solid content (%).
And the vertical axis indicates the dissolution rate (μm / min).

────────────────────────────────────────────────── (5) Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 21/027 H01L 21/30 502R (56) References JP-A-4-211256 (JP, A) JP-A-63-27829 ( JP, A) JP-A-5-173333 (JP, A) JP-A-5-142774 (JP, A) JP-A-5-158242 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) G03F 7/004 501 C07C 69/96 C08K 5/10 C08L 101/00 G03F 7/039 601

Claims (2)

(57) [Claims] (1) Formula (1) (In the formula (1), R represents hydrogen or a methyl group.) 2. A positive radiation-sensitive resist composition comprising an alkali-soluble resin, a compound capable of generating an acid in response to radiation and a compound represented by the formula (1) according to claim 1.