RADIATION-SENSITIVE COMPOSITION AND PATTERN-FORMING METHOD

Abstract

A radiation-sensitive composition contains: a metal oxide having a first structural unit represented by formula (1), formula (2) or a combination thereof, and a second structural unit represented by formula (3); and a solvent. In the formulae (1) to (3), M.sup.1, M.sup.2 and M.sup.3 each independently represent germanium, tin or lead; and R.sup.1, R.sup.2 and R.sup.3 each independently represent a monovalent organic group having 1 to 40 carbon atoms which bonds to M.sup.1 or M.sup.2 via a carbon atom. A proportion of the first structural unit with respect to total structural units constituting the metal oxide is preferably no less than 50 mol %.

##STR00001##

Claims

1. A radiation-sensitive composition comprising: a metal oxide comprising a first structural unit represented by formula (1), formula (2) or a combination thereof, and a second structural unit represented by formula (3); and a solvent, ##STR00014## wherein, in the formulae (1) and (2), M.sup.1 and M.sup.2 each independently represent germanium, tin or lead; and R.sup.1, R.sup.2 and R.sup.3 each independently represent a monovalent organic group having 1 to 40 carbon atoms which bonds to M.sup.1 or M.sup.2 via a carbon atom, and
(M.sup.3O.sub.4/2) (3) in the formula (3), M.sup.3 represents germanium, tin or lead.

2. The radiation-sensitive composition according to claim 1, wherein a proportion of the first structural unit with respect to total structural units constituting the metal oxide is no less than 50 mol %.

3. The radiation-sensitive composition according to claim 1, wherein R.sup.1 in the formula (1) and R.sup.2 in the formula (2) each represent a monovalent hydrocarbon group having 1 to 20 carbon atoms, wherein at least a part of hydrogen atoms thereof is substituted with a substituent that is an unsaturated bond-containing group, an electron attractive group or a combination thereof.

4. The radiation-sensitive composition according to claim 1, further comprising a radiation-sensitive base generator.

5. The radiation-sensitive composition according to claim 1, wherein a content of the metal oxide in the radiation-sensitive composition in terms of solid content equivalent is no less than 50% by mass.

6. The radiation-sensitive composition according to claim 1, wherein the solvent is an organic solvent.

7. A pattern-forming method comprising: applying the radiation-sensitive composition according to claim 1 directly or indirectly on a substrate to provide a film; exposing the film; and developing the film exposed.

8. The pattern-forming method according to claim 7, wherein in the developing of the film, the film is developed with a developer solution comprising an organic solvent.

9. The pattern-forming method according to claim 7, wherein in the exposing of the film, the film is exposed to a radioactive ray which is an extreme ultraviolet ray or an electron beam.

Description

EXAMPLES

[0171] 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.

Synthesis of Metal Oxide

Synthesis Example 1

[0172] Into 100 g of a 0.3 M aqueous hydroxylated tetramethyl ammonium solution, 9.50 mmol of tert-butyltin trichloride (a compound represented by the following formula (X-1) (hereinafter, may be also referred to as compound (X-1))) and 0.50 mmol of tetra-tert-butoxytin (a compound represented by the following formula (X-2) (hereinafter, may be also referred to as compound (X-2))) were charged, and the mixture was vigorously stirred at room temperature for 90 min. Thus separated precipitate was filtered out, and thereafter washed twice with 50 g of water, whereby a metal oxide (hereinafter, may be also referred to as metal oxide (A-1)) represented by the following formula (A-1) was synthesized. The metal oxide (A-1) had Mw of 2,500. It is to be noted that Mw is a value determined by using gel permeation chromatography under the following conditions.

[0173] GPC columns: G2000HXL2, G3000HXL1 and G4000HXL1, available from Tosoh Corporation;

[0174] column temperature: 40 C.;

[0175] elution solvent: tetrahydrofuran;

[0176] flow rate: 1.0 mL/min;

[0177] sample concentration: 1.0% by mass;

[0178] amount of injected sample: 100 L;

[0179] detector: differential refractometer; and

[0180] standard substance: mono-dispersed polystyrene

[0181] In addition, proportions of a structural unit derived from the compound (X-1) and a structural unit derived from the compound (X-2) contained in the metal oxide (A-1) were 95 mol % and 5 mol %, respectively, as determined by .sup.119Sn-NMR measurement.

Synthesis Examples 2 to 10 and Comparative Synthesis Examples 1 to 4

[0182] Metal oxides (A-2) to (A-10) and (a-1) to (a-4) represented by the following formulae were synthesized by similar operations to Synthesis Example 1 except that the type and the charging molar ratio of the monomer used were changed as shown in Table 1. Structures of compounds (X-1) to (X-8) as monomers are represented by the following formulae (X-1) to (X-8), respectively. The total number of moles of the monomer used was 10.00 mmol. It is to be noted that the proportion of each structural unit contained in each metal oxide synthesized was determined by a similar .sup.119Sn-NMR measurement to Synthesis Example 1, and ascertained to be as each estimated from the charging molar ratio (mol %) of the compound that provides each structural unit.

Synthesis Example 11

[0183] Into 100 g of a 0.3 M aqueous hydroxylated tetramethyl ammonium solution, 9.00 mmol of isopropyl(trichloro)gelmane (compound represented by the following formula (X-9)) and 1.00 mmol of tetraethoxygelmane (compound represented by the following formula (X-10)) were charged, and the mixture was vigorously stirred at room temperature for 90 min. Thus separated precipitate was filtered out, and thereafter washed twice with 50 g of water, whereby a metal oxide (hereinafter, may be also referred to as metal oxide (A-11)) represented by the following formula (A-11) was synthesized. The metal oxide (A-11) had the Mw of 2,000.

Comparative Synthesis Example 5

[0184] Into 100 g of a 0.3 M aqueous hydroxylated tetramethyl ammonium solution, 10.00 mmol of isopropyltrichlorogelmane (compound (X-9)) was charged, and the mixture was vigorously stirred at room temperature for 90 min. Thus separated precipitate was filtered out, and thereafter washed twice with 50 g of water, whereby a metal oxide (hereinafter, may be also referred to as metal oxide (a-5)) represented by the following formula (a-5) was synthesized. The metal oxide (a-5) had the Mw of 1,900.

Comparative Synthesis Example 6

[0185] Into 100 g of a 0.3 M aqueous hydroxylated tetramethyl ammonium solution, 10.00 mmol of tetraethoxygelmane (compound (X-10)) was charged, and the mixture was vigorously stirred at room temperature for 90 min. Thus separated precipitate was filtered out, and thereafter washed twice with 50 g of water, whereby a metal oxide (hereinafter, may be also referred to as metal oxide (a-6)) represented by the following formula (a-6) was synthesized. The metal oxide (a-6) had the Mw of 2,100.

##STR00011## ##STR00012## ##STR00013##

TABLE-US-00001 TABLE 1 Monomer that Monomer that gives struc- gives struc- tural unit (I) tural unit (II) Charging Charging (A) molar molar Compo- ratio ratio nent Mw Type (mol %) Type (mol %) Synthesis A-1 2,500 X-1 95 X-2 5 Example 1 Synthesis A-2 2,400 X-3 95 X-2 5 Example 2 Synthesis A-3 2,400 X-4 95 X-2 5 Example 3 Synthesis A-4 2,500 X-5 95 X-2 5 Example 4 Synthesis A-5 2,300 X-6 95 X-2 5 Example 5 Synthesis A-6 2,400 X-1 90 X-2 10 Example 6 Synthesis A-7 2,500 X-7 50 X-2 50 Example 7 Synthesis A-8 2,400 X-8 90 X-2 10 Example 8 Synthesis A-9 2,400 X-1 80 X-2 20 Example 9 Synthesis A-10 2,400 X-1 40 X-2 60 Example 10 Synthesis A-11 2,000 X-9 90 X-10 10 Example 11 Comparative a-1 2,500 X-1 100 Synthesis Example 1 Comparative a-2 2,400 X-3 100 Synthesis Example 2 Comparative a-3 2,400 X-2 100 Synthesis Example 3 Comparative a-4 2,500 X-7 100 Synthesis Example 4 Comparative a-5 1,900 X-9 100 Synthesis Example 5 Comparative a-6 2,100 X-10 100 Synthesis Example 6

Preparation of Radiation-Sensitive Composition

[0186] Components other than the metal oxide (A) used for preparing radiation-sensitive compositions are shown below.

[0187] (B) Solvent

[0188] B-1: 4-methyl-2-pentanol

[0189] (C) Base Generator

[0190] C-1: 2-nitrobenzylcyclohexyl carbamate

[0191] (D) Surfactant

[0192] D-1: nonionic acetylene group-containing surfactant (Surfinol 465, available from Nissin Chemical Co., Ltd.)

Example 1

[0193] A radiation-sensitive composition (J-1) of Example 1 was prepared by mixing 3.0 parts by mass of the metal oxide (A-1) and 97.0 parts by mass of the solvent (B-1), and filtering a thus obtained mixture through a membrane filter having a pore size of 0.2 m.

Examples 2 to 13 and Comparative Examples 1 to 6

[0194] Radiation-sensitive compositions (J-2) to (J-13) of Examples 2 to 13 and radiation-sensitive compositions (j-1) to (j-6) of Comparative Examples 1 to 6 were prepared by a similar operation to that of Example 1 except that the type and the content of each component were as shown in Table 2 below. It is to be noted that the denotation in Table 2 below indicates that a corresponding component was not used.

Evaluations

[0195] Evaluation of sensitivity was made by using each radiation-sensitive composition of Examples and Comparative Examples through forming a pattern in accordance with the following method. In addition, evaluations of etching resistance and a coating characteristic of the radiation-sensitive composition on a substrate were made according to the following method. The results of the evaluation are shown together in Table 2 below.

[0196] Formation of Metal-Containing Film

[0197] After the radiation-sensitive composition (J-1) prepared in Example 1 described above was spin-coated on a silicon wafer in CLEAN TRACK ACT-8 available from Tokyo Electron Limited, PB was carried out under a condition of 80 C. for 60 sec to form a metal-containing film having an average thickness (averaged value of the film thickness at arbitrary nine points on the silicon wafer) of 50 nm. The radiation-sensitive compositions (J-2) to (J-13) and (j-1) to (i-6) were similarly applied to form the metal-containing film having an average thickness of 50 nm.

[0198] Pattern Formation

[0199] The metal-containing film corresponding to each radiation-sensitive composition obtained as described above was subjected to patterning by irradiating with an electron beam using a simplified electron beam writer (HL800D available from Hitachi, Ltd., power: 50 KeV, electric current density: 5.0 ampere/cm.sup.2) such that a width of a line part and a width of a space part formed between neighboring line parts has a ratio of 1:1 (line-and-space pattern (1L 1S)). After the irradiation with the electron beam, in the CLEAN TRACK ACT-8, propylene glycol monomethyl ether acetate was used to carry out a development in accordance with a puddle procedure at 23 C. for 1 min, followed by drying, whereby the pattern was formed.

[0200] Sensitivity

[0201] An exposure dose was decided, at which formation of a line-and-space pattern (1L 1S) was enabled, the line-and-space pattern including a line part having a width of 150 nm and a space part having a width of 150 nm formed between neighboring line parts, and this exposure dose was defined as an optimum exposure dose, which was employed as an indicative of the sensitivity (C/cm.sup.2).

[0202] Etching Resistance

[0203] The substrate which had been provided with the metal-containing film obtained as described above was subjected to a treatment by using a plasma etching apparatus (EXAM available from SHINKO SEIKI CO., LTD.), under conditions involving O.sub.2 of 100 sccm, at 100 W for 60 sec. An etching rate (nm/sec) was calculated from average film thicknesses of before and after the treatment, and the oxygen-etching resistance was evaluated therefrom. The etching resistance was evaluated to be: A (very favorable) in the case of the etching rate being less than 4.5 (nm/min); B (favorable) in the case of the etching rate being no less than 4.5 (nm/min) and less than 5.0 (nm/min); and C (unfavorable) in the case of the etching rate being no less than 5.0 (nm/sec).

[0204] Coating Characteristic

[0205] The radiation-sensitive resin composition prepared as described above was applied onto the surface of an 8-inch silicon wafer by using a spin coater (Tokyo Electron Limited, CLEAN TRACK ACTS), and then subjected to PB at 80 C. for 60 sec. Thereafter, cooling was carried out at 23 C. for 30 sec to form a resist film having an average thickness of 50 nm. The coating characteristic was evaluated by visually observing the presence/absence of striation (radially running streaks from the center portion toward the peripheral portion) and repellency, to be: favorable in the case where these defects were found; and unfavorable in the case where these defects were not found.

TABLE-US-00002 TABLE 2 (A) Metal (C) Base oxide (B) Solvent generator (D) Surfactant Radiation- parts parts parts parts Pattern formation Evaluation sensitive by by by by Developer Pattern Sensitivity Etching Coating composition Type mass type mass type mass Type mass solution tone (C/cm.sup.2) resistance characteristic Example 1 J-1 A-1 3.0 B-1 97.0 PGMEA negative 30 A favorable Example 2 J-2 A-2 3.0 B-1 97.0 PGMEA negative 33 A favorable Example 3 J-3 A-3 3.0 B-1 97.0 PGMEA negative 18 A favorable Example 4 J-4 A-4 3.0 B-1 97.0 PGMEA negative 18 A favorable Example 5 J-5 A-5 3.0 B-1 97.0 PGMEA negative 25 B favorable Example 6 J-6 A-6 3.0 B-1 97.0 PGMEA negative 28 A favorable Example 7 J-7 A-7 3.0 B-1 97.0 PGMEA negative 22 B favorable Example 8 J-8 A-1 2.9 B-1 97.0 C-1 0.090 PGMEA negative 27 A favorable Example 9 J-9 A-1 2.9 B-1 97.0 C-1 0.090 D-1 0.001 PGMEA negative 26 A favorable Example 10 J-10 A-8 3.0 B-1 97.0 PGMEA negative 29 A favorable Example 11 J-11 A-9 3.0 B-1 97.0 PGMEA negative 30 A favorable Example 12 J-12 A-10 3.0 B-1 97.0 PGMEA negative 33 A favorable Example 13 J-13 A-11 3.0 B-1 97.0 PGMEA negative 30 A favorable Comparative j-1 a-1 3.0 B-1 97.0 PGMEA negative 32 C favorable Example 1 Comparative j-2 a-2 3.0 B-1 97.0 PGMEA negative 35 C favorable Example 2 Comparative j-3 a-3 3.0 B-1 97.0 PGMEA negative (not A unfavorable Example 3 resolved) (striation) Comparative j-4 a-4 3.0 B-1 97.0 PGMEA negative 53 C unfavorable Example 4 (repellency) Comparative j-5 a-5 3.0 B-1 97.0 PGMEA negative 40 C favorable Example 5 Comparative j-6 a-6 3.0 B-1 97.0 PGMEA negative (not A unfavorable Example 6 resolved) (striation)

[0206] As is seen from the results shown in Table 2 above, the radiation-sensitive compositions of Examples were superior in sensitivity and enabled a pattern superior in etching resistance to be formed, as compared with the radiation-sensitive compositions of Comparative Examples.

[0207] The radiation-sensitive composition and the pattern-forming method of the embodiments of the present invention enable a pattern superior in etching resistance to be formed with superior sensitivity being achieved. Therefore, these can be suitably used in manufacture of semiconductor devices in which further progress of miniaturization is expected in the future.

[0208] 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.