Radiation-sensitive resin composition, method of forming resist pattern, and compound

Abstract

A radiation-sensitive resin composition contains: a polymer that includes a structural unit including an acid-labile group; a radiation-sensitive acid generator; and a compound represented by the following formula (1). In the following formula (1), R.sup.1 represents a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms; and X.sup.n+ represents a radiation-sensitive onium cation having a valency of n, wherein n is an integer of 1 to 3. It is preferable that R.sup.1 in the following formula (1) represents an organic group, and that the organic group has a ring structure. It is preferable that R.sup.1 in the following formula (1) represents an organic group, and that the organic group is an acid-labile group. X.sup.n+ in the following formula (1) preferably represents a sulfonium cation, an iodonium cation, or a combination thereof. ##STR00001##

Claims

1. A radiation-sensitive resin composition comprising: a polymer which comprises a structural unit comprising an acid-labile group; a radiation-sensitive acid generator; and a compound represented by formula (1): ##STR00034## wherein, in the formula (1), R.sup.1 represents a monovalent organic group having 1 to 30 carbon atoms; and X.sup.n+ represents a radiation-sensitive onium cation having a valency of n, wherein n is an integer of 1 to 3.

2. The radiation-sensitive resin composition according to claim 1, wherein R.sup.1 in the formula (1) represents an organic group, and the organic group comprises a ring structure.

3. The radiation-sensitive resin composition according to claim 1, wherein R.sup.1 in the formula (1) represents an organic group, and the organic group is an acid-labile group.

4. The radiation-sensitive resin composition according to claim 1, wherein X.sup.n+ in the formula (1) represents a sulfonium cation, an iodonium cation, or a combination thereof.

5. The radiation-sensitive resin composition according to claim 1, wherein n in the formula (1) is 1.

6. A method of forming a resist pattern, the method comprising: applying a radiation-sensitive resin composition directly or indirectly on a substrate; exposing a resist film formed by the applying; and developing the resist film exposed, wherein the radiation-sensitive resin composition comprises: a polymer which comprises a structural unit comprising an acid-labile group; a radiation-sensitive acid generator; and a compound represented by formula (1): ##STR00035## wherein, in the formula (1), R.sup.1 represents a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms; and X.sup.n+ represents a radiation-sensitive onium cation having a valency of n, wherein n is an integer of 1 to 3.

7. A compound represented by formula (1): ##STR00036## wherein, in the formula (1), R.sup.1 represents a monovalent organic group having 1 to 30 carbon atoms; and X.sup.n+ represents a cation having a valency of n, wherein n is an integer of 1 to 3.

8. The compound according to claim 7, wherein the cation represented by X.sup.n+ in the formula (1) is an onium cation.

9. The compound according to claim 8, wherein the onium cation represented by X.sup.n+ is radiation sensitive.

10. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the acid generating agent in the radiation-sensitive resin composition is from 0.1 parts by mass to 50 parts by mass with respect to 100 parts by mass of the polymer.

11. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the acid generating agent in the radiation-sensitive resin composition is from 10 parts by mass to 40 parts by mass with respect to 100 parts by mass of the polymer.

12. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the compound in the radiation-sensitive resin composition is from 1 to 50 mol % with respect to 100 mol % of the acid generating agent.

13. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the compound in the radiation-sensitive resin composition is from 10 to 30 mol % with respect to 100 mol % of the acid generating agent.

14. The method according to claim 6, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the acid generating agent in the radiation-sensitive resin composition is from 0.1 parts by mass to 50 parts by mass with respect to 100 parts by mass of the polymer.

15. The method according to claim 6, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the acid generating agent in the radiation-sensitive resin composition is from 10 parts by mass to 40 parts by mass with respect to 100 parts by mass of the polymer.

16. The method according to claim 6, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the compound in the radiation-sensitive resin composition is from 1 to 50 mol % with respect to 100 mol % of the acid generating agent.

17. The method according to claim 6, wherein the radiation-sensitive acid generator is an acid generating agent, and a content of the compound in the radiation-sensitive resin composition is from 10 to 30 mol % with respect to 100 mol % of the acid generating agent.

18. The method according to claim 6, wherein X.sup.n+ in the formula (1) represents a sulfonium cation, an iodonium cation, or a combination thereof.

19. The compound according to claim 9, wherein X.sup.n+ in the formula (1) represents a sulfonium cation, an iodonium cation, or a combination thereof.

Description

EXAMPLES

(1) Hereinafter, the present invention is explained in detail by way of Examples, but the present invention is not in any way limited to these Examples. Physical property values in the Examples were measured as described below.

(2) Weight Average Molecular Weight (Mw), Number Average Molecular Weight (Mn) and Dispersity Index (Mw/Mn)

(3) Measurements were carried out by gel permeation chromatography (GPC) using GPC columns produced by Tosoh Corporation (G2000 HXL2, G3000 HXL1, and G4000 HXL1) under an analytical conditions involving a flow rate of 1.0 mL/min, an elution solvent of tetrahydrofuran, a sample concentration of 1.0% by mass, an injected sample amount of 100 L a column temperature of 40 C., and a differential refractometer as a detector, with mono-dispersed polystyrene as a standard. Furthermore, a dispersity index (Mw/Mn) was calculated according to measurement results of the Mw and the Mn.

(4) Proportion of Each Structural Unit of Polymer

(5) The proportion of each structural unit of each polymer was determined by .sup.13C-NMR analysis using a nuclear magnetic resonance apparatus (JNM-Delta400, available from JEOL, Ltd.).

(6) Synthesis of Polymer (A)

(7) Monomers used for synthesizing the polymer (A) are shown below. It is to be noted that in the following Synthesis Examples, unless otherwise specified particularly, the term parts by mass means a value, provided that the total mass of the monomers used was 100 parts by mass, and the term mol % means a value, provided that the total mol number of the monomers used was 100 mol %.

(8) ##STR00025## ##STR00026##

Synthesis Example 1: Synthesis of Polymer (A-1)

(9) The monomer (M-3) and the monomer (M-1) were dissolved in 200 parts by mass of propylene glycol-1-monomethyl ether such that the molar ratio became 60/40. Next, a monomer solution was prepared by adding 6 mol % azobisisobutyronitrile (AIBN) as a radical polymerization initiator. Meanwhile, to an empty reaction vessel were charged 100 parts by mass of propylene glycol-1-monomethyl ether, which were then heated to 85 C. with stirring. Next, the monomer solution prepared as described above was added dropwise to the reaction vessel over 3 hrs, and then a thus resulting solution was further heated for 3 hrs at 85 C., and a polymerization reaction was allowed to proceed for 6 hrs. After completion of the polymerization reaction, the polymerization solution was cooled to room temperature.

(10) The polymerization solution thus cooled was charged into 500 parts by mass of hexane with respect to 100 parts by mass of the polymerization solution, and a thus precipitated white powder was filtered off. The white powder obtained by the filtration was washed twice with 100 parts by mass of hexane with respect to 100 parts by mass of the polymerization solution, followed by filtering off and dissolution in 300 parts by mass of propylene glycol-1-monomethyl ether. Next, 500 parts by mass of methanol, 50 parts by mass of triethylamine, and 10 parts by mass of ultra-pure water were added to a resulting solution, and a hydrolysis reaction was performed at 70 C. for 6 hrs with stirring.

(11) After completion of the reaction, the remaining solvent was distilled away and a solid thus obtained was dissolved in 100 parts by mass of acetone. A thus obtained solution was added drop wise to 500 parts by mass of water to permit coagulation of the polymer, and a solid thus obtained was filtered off. Drying at 50 C. for 12 hrs gave a white powdery polymer (A-1). The Mw of the polymer (A-1) was 5,700, and the Mw/Mn was 1.61. Furthermore, as a result of the .sup.13C-NMR analysis, the proportions of the structural units derived from (M-3) and (M-1) were, respectively, 59.1 mol % and 40.9 mol %.

Synthesis Examples 2 to 9

(12) Polymers (A-2) to (A-9) were synthesized by a similar operation to that of Synthesis Example 1 except that each monomer of the type and in the proportion shown in Table 1 below was used. It is to be noted that in Table 1, - indicates that the corresponding monomer was not used.

(13) TABLE-US-00001 TABLE 1 Monomer that gives Monomer that gives Monomer that gives other structural unit (I) structural unit (II) structural unit proportion of proportion of proportion of (A) proportion structural proportion structural proportion structural Polymer type (mol %) unit (mol %) Type (mol %) unit (mol %) type (mol %) unit (mol %) Mw Mw/Mn Synthesis A-1 M-3 60 59.1 M-1 40 40.9 5,700 1.61 Example 1 Synthesis A-2 M-4 60 57.2 M-1 40 42.8 5,800 1.64 Example 2 Synthesis A-3 M-5 60 55.8 M-1/M-2 30/10 30.2/14.0 6,100 1.65 Example 3 Synthesis A-4 M-6 60 56.1 M-1 40 43.9 6,200 1.50 Example 4 Synthesis A-5 M-7 60 59.5 M-1 40 40.5 5,500 1.54 Example 5 Synthesis A-6 M-8 60 59.7 M-1 40 40.3 5,400 1.53 Example 6 Synthesis A-7 M-9 60 55.3 M-1 40 44.7 6,000 1.67 Example 7 Synthesis A-8 M-3 60 58.9 M-1 30 32.2 M-10 10 8.9 6,900 1.70 Example 8 Synthesis A-9 M-3 60 59.2 M-1 30 31.6 M-11 10 9.2 6,800 1.65 Example 9

Synthesis of Compound (C)

Example 1: Synthesis of Compound (Z-1)

(14) Compound (Z-1) was synthesized according to the following reaction scheme.

(15) ##STR00027##

(16) Into a reaction vessel were charged 29 mmol of cyclohexanol as a compound represented by the above formula (ppz-1), 29 mmol of triethylamine (NEt.sub.3), and 100 g of dichloromethane. After stirring a resulting mixture at 0 C., 14.5 mmol of tetrafluorosuccinic anhydride was added dropwise. After stirring a resulting mixture for 12 hrs at room temperature, 100 g of water and 16 mmol of triphenylsulfonium chloride (TPS-Cl) were added to a thus generated compound represented by the above formula (pz-1), i.e., triethylammonium 2-(cyclohexylcarbonyl)-1,1,2,2-tetrafluoro-propionate. A resulting mixture was stirred for 2 hrs at room temperature, and then an organic layer was separated, and was thereafter washed with water. After drying over anhydrous sodium sulfate, the solvent was distilled off, and recrystallization gave a compound (Z-1).

Examples 2 to 9: Synthesis of Compounds (Z-2) to (Z-9)

(17) Compounds represented by the following formulae (Z-2) to (Z-9) were synthesized in a similar manner to Example 1 by appropriately selecting precursors.

(18) ##STR00028## ##STR00029## ##STR00030##
Preparation of Radiation-Sensitive Resin Composition

(19) The acid generating agent (B) and the solvent (D) used in preparing each radiation-sensitive resin composition of the one embodiment of the present invention, and the acid diffusion control agent (E) used in preparing each radiation-sensitive resin composition of the Comparative Examples are shown below.

(20) (B) Acid Generating Agent

(21) B-1 to B-6: Compounds represented by the following formulae (B-1) to (B-16)

(22) ##STR00031## ##STR00032##
(D) Solvent
D-1: propylene glycol monomethyl ether acetate
D-2: propylene glycol 1-monomethyl ether
(E) Acid Diffusion Control Agent
E-1 to E-3: Compounds represented by the following formulae (E-1) to (E-3)

(23) ##STR00033##

Example 10

(24) A radiation-sensitive resin composition (R-1) was prepared by: blending 100 parts by mass of (A-1) as the polymer (A), 20 parts by mass of (B-1) as the acid generating agent (B), 20 mol % with respect to 100% mol (B-1) of (Z-1) as the acid diffusion control agent (C), and 4,800 parts by mass of (D-1) and 2,000 parts by mass of (D-2) as the organic solvent (D), and then filtering a thus resulting mixture through a membrane filter having a pore size of 0.2 m.

Examples 11 to 31 and Comparative Examples 1 to 3

(25) Radiation-sensitive resin compositions (R-2) to (R-22) and (CR-1) to (CR-3) were prepared in a similar manner to Example 10, except that for each component, the type and content shown in Table 2 below were used.

(26) TABLE-US-00002 TABLE 2 (C) Compound or (E) Acid (B) Acid generating diffusion control agent Radition- (A) Polymer agent content (D) Solvent sensative content content (mol % with content resin (parts by (parts by respect to 100 (parts by composition type mass) type mass) type mol % of (B)) type mass) Example 10 R-1 A-1 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 11 R-2 A-1 100 B-1 20 Z-2 20 D-1/D-2 4,800/2,000 Example 12 R-3 A-1 100 B-1 20 Z-3 20 D-1/D-2 4,800/2,000 Example 13 R-4 A-1 100 B-1 20 Z-4 20 D-1/D-2 4,800/2,000 Example 14 R-5 A-1 100 B-1 20 Z-5 20 D-1/D-2 4,800/2,000 Example 15 R-6 A-1 100 B-1 20 Z-6 20 D-1/D-2 4,800/2,000 Example 16 R-7 A-1 100 B-1 20 Z-7 20 D-1/D-2 4,800/2,000 Example 17 R-8 A-1 100 B-1 20 Z-8 20 D-1/D-2 4,800/2,000 Example 18 R-9 A-1 100 B-1 20 Z-9 20 D-1/D-2 4,800/2,000 Example 19 R-10 A-1 100 B-2 20 Z-1 20 D-1/D-2 4,800/2,000 Example 20 R-11 A-1 100 B-3 20 Z-1 20 D-1/D-2 4,800/2,000 Example 21 R-12 A-1 100 B-4 20 Z-1 20 D-1/D-2 4,800/2,000 Example 22 R-13 A-1 100 B-5 20 Z-1 20 D-1/D-2 4,800/2,000 Example 23 R-14 A-1 100 B-6 20 Z-1 20 D-1/D-2 4,800/2,000 Example 24 R-15 A-2 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 25 R-16 A-3 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 26 R-17 A-4 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 27 R-18 A-5 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 28 R-19 A-6 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 29 R-20 A-7 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 30 R-21 A-8 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Example 31 R-22 A-9 100 B-1 20 Z-1 20 D-1/D-2 4,800/2,000 Comparative CR-1 A-1 100 B-1 20 E-1 20 D-1/D-2 4,800/2,000 Example 1 Comparative CR-2 A-1 100 B-1 20 E-2 20 D-1/D-2 4,800/2,000 Example 2 Comparative CR-3 A-1 100 B-1 20 E-3 20 D-1/D-2 4,800/2,000 Example 3
Resist Pattern Formation

(27) Using a spin coater (CLEAN TRACK ACT 12, available from Tokyo Electron Limited), the radiation-sensitive resin compositions prepared as described above were each applied on a surface of a 12-inch silicon wafer with an underlayer film (AL412, available from Brewer Science, Inc.) having an average thickness of 20 nm being formed thereon, and PB was conducted at 130 C. for 60 sec. Thereafter, by cooling at 23 C. for 30 sec, a resist film having an average thickness of 50 nm was formed. Next, the resist film was irradiated with EUV using an EUV scanner (NXE3300, available from ASML Co., with NA of 0.33 under an illumination condition of Conventional s=0.89, and with a mask of imecDEFECT32FFR02). After the irradiation, PEB was carried out on the resist film at 130 C. for 60 sec. Thereafter, the resist film was developed at 23 C. for 30 sec by using a 2.38% by mass aqueous TMAH solution to form a positive-tone 32 nm line-and-space pattern.

(28) Evaluations

(29) With regard to the resist patterns formed as described above, each radiation-sensitive resin composition was evaluated on the sensitivity and the process window thereof in accordance with the following methods. It is to be noted that a scanning electron microscope (CG-4100, available from Hitachi High-Technologies Corporation) was used for line-width measurement of the resist patterns. The results of the evaluations are shown in Table 3 below.

(30) Sensitivity

(31) An exposure dose at which a 32-nm line-and-space pattern was formed in the aforementioned resist pattern formation was defined as an optimum exposure dose, and this optimum exposure dose was adopted as sensitivity (mJ/cm.sup.2). The sensitivity was evaluated to be: favorable in a case of being no greater than 30 mJ/cm.sup.2; and unfavorable in a case of being greater than 30 mJ/cm.sup.2.

(32) Process Window

(33) Using a mask for forming a 32-nm line-and-space pattern (1L/1S), patterns were formed with exposure doses ranging from low to high exposure doses. In general, defects in connections between patterns and the like can be found on the low exposure dose side, and defects such as pattern collapses can be found on the high exposure dose side. The difference between the upper limit value and the lower limit value of resist dimensions at which no such defects were found was considered to be the CD (Critical Dimension) margin. It is considered that the CD margin (nm) being larger indicates that the process window is broader. The CD margin was evaluated to be: favorable in a case of being no less than 30 nm; and unfavorable in a case of being less than 30 nm.

(34) TABLE-US-00003 TABLE 3 Radiation-sensitive Sensitivity CD margin resin composition (mJ/cm.sup.2) (nm) Example 10 R-1 27 40 Example 11 R-2 26 38 Example 12 R-3 25 39 Example 13 R-4 25 41 Example 14 R-5 25 43 Example 15 R-6 24 45 Example 16 R-7 25 44 Example 17 R-8 28 36 Example 18 R-9 27 37 Example 19 R-10 25 41 Example 20 R-11 24 43 Example 21 R-12 25 42 Example 22 R-13 28 44 Example 23 R-14 26 47 Example 24 R-15 28 43 Example 25 R-16 28 42 Example 26 R-17 29 44 Example 27 R-18 27 41 Example 28 R-19 28 42 Example 29 R-20 29 39 Example 30 R-21 26 42 Example 31 R-22 25 44 Comparative CR-1 42 20 Example 1 Comparative CR-2 33 35 Example 2 Comparative CR-3 24 17 Example 3

(35) As is clear from the results shown in Table 3, when compared to the Comparative Examples, all of the radiation-sensitive resin compositions of the Examples were favorable in terms of the sensitivity and the CD margin.

(36) The radiation-sensitive resin composition and the method of forming a resist pattern of the embodiments of the present invention enable forming a resist pattern, with superior sensitivity and the broad process window. The compound of the still another embodiment of the present invention can be suitably used as a component of the radiation-sensitive resin composition. Therefore, these can be suitably used in manufacturing processes of semiconductor devices, in which further progress of miniaturization is expected in the future.

(37) Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.