NEGATIVE RESIST COMPOSITION AND PATTERN FORMING PROCESS

Abstract

A negative resist composition comprising a base polymer comprising repeat units derived from a triple bond-containing maleimide compound is provided. A pattern with a high resolution and reduced edge roughness is formed therefrom.

Claims

1. A negative resist composition comprising a base polymer comprising repeat units (a) derived from a triple bond-containing maleimide compound.

2. The negative resist composition of claim 1 wherein the repeat units (a) are repeat units (a1) having the formula (a1) or repeat units (a2) having the formula (a2): ##STR00134## wherein R.sup.1 and R.sup.2 are each independently hydrogen or methyl, X.sup.1A and X.sup.1B are each independently a single bond, a C.sub.1-C.sub.6 saturated hydrocarbylene group or phenylene group, X.sup.2A and X.sup.2B are each independently a single bond, ester bond or ether bond.

3. The negative resist composition of claim 1 wherein the base polymer further comprises repeat units (b) having a phenolic hydroxy group.

4. The negative resist composition of claim 3 wherein the repeat units (b) have the formula (b): ##STR00135## wherein R.sup.A is hydrogen or methyl, R.sup.11 is a C.sub.1-C.sub.4 alkyl group, C.sub.1-C.sub.4 alkoxy group, acetoxy group or halogen, Y.sup.1 is a single bond, ester bond or amide bond, a is an integer of 0 to 4, b is 1 or 2, and the sum of a+b is from 1 to 5.

5. The negative resist composition of claim 1 wherein the base polymer further comprises repeat units (c) having the formula (c): ##STR00136## wherein R.sup.A is hydrogen or methyl, R.sup.12 is a C.sub.1-C.sub.6 alkyl group or halogen, R.sup.13 and R.sup.14 are each independently hydrogen or a C.sub.1-C.sub.6 saturated hydrocarbyl group, R.sup.13 and R.sup.14 may bond together to form a ring with the carbon atom to which they are attached, Y.sup.2 is a single bond or ester bond, c is an integer of 0 to 4, d is 1 or 2, and the sum of c+d is from 1 to 5.

6. The negative resist composition of claim 1 wherein the base polymer further comprises repeat units having the formula (d1), (d2) or (d3): ##STR00137## wherein R.sup.A is hydrogen or methyl, Z.sup.1 is a single bond, a C.sub.1-C.sub.6 aliphatic hydrocarbylene group, phenylene group, naphthylene group, or C.sub.7-C.sub.18 is group obtained by combining the foregoing, or —O—Z.sup.11—, —C(═O)—O—Z.sup.11— or —C(═O)—NH—Z.sup.11—, Z.sup.11 is a C.sub.1-C.sub.6 aliphatic hydrocarbylene group, phenylene group, naphthylene group, or C.sub.7-C.sub.18 group obtained by combining the foregoing, which may contain a carbonyl moiety, ester bond, ether bond or hydroxy moiety, Z.sup.2 is a single bond or ester bond, Z.sup.3 is a single bond, —Z.sup.31—C(═O)—O—, —Z.sup.31—O— or —Z.sup.31—O—C(═O)—, Z.sup.31 is a C.sub.1-C.sub.12 aliphatic hydrocarbylene group, phenylene group, or C.sub.7-C.sub.18 group obtained by combining the foregoing, which may contain a carbonyl moiety, ester bond, ether bond, bromine or iodine, Z.sup.4 is methylene, 2,2,2-trifluoro-1,1-ethanediyl, or carbonyl, Z.sup.5 is a single bond, methylene, ethylene, phenylene, fluorinated phenylene, trifluoromethyl-substituted phenylene group, —O—Z.sup.51—, —C(═O)—O—Z.sup.51—, or —C(═O)—NH—Z.sup.51—, Z.sup.51 is a C.sub.1-C.sub.6 aliphatic hydrocarbylene group, phenylene group, fluorinated phenylene group, or trifluoromethyl-substituted phenylene group, which may contain a carbonyl moiety, ester bond, ether bond, halogen or hydroxy moiety, R.sup.21 to R.sup.28 are each independently halogen or a C.sub.1-C.sub.20 hydrocarbyl group which may contain a heteroatom, a pair of R.sub.23 an R.sup.24 or R.sub.26 and R.sup.27 may bond together to form a ring with the sulfur atom to which they are attached, and M.sup.− is a non-nucleophilic counter ion.

7. The negative resist composition of claim 1, further comprising an organic solvent.

8. The negative resist composition of claim 1, further comprising an acid generator.

9. The negative resist composition of claim 1, further comprising a quencher.

10. The negative resist composition of claim 1, further comprising a surfactant.

11. A pattern forming process comprising the steps of applying the negative resist composition of claim 1 onto a substrate to form a resist film thereon, exposing the resist film to high-energy radiation, and developing the exposed resist film in a developer.

12. The process of claim 11 wherein the substrate is a photomask blank.

13. The process of claim 11 wherein the high-energy radiation is UV radiation of wavelength 180 to 400 nm.

14. The process of claim 11 wherein the high-energy radiation is EB or EUV of wavelength 3 to 15 nm.

15. A photomask blank having the negative resist composition of claim 1 coated thereon.

Description

EXAMPLES

[0125] Examples of the invention are given below by way of illustration and not by way of limitation. The abbreviation “pbw” is parts by weight.

[1] Synthesis of Base Polymers

[0126] Monomers M-1 to M-4, AM-1 to AM-4 and PM-1 to PM-4 used in the synthesis of base polymers are identified below. The polymer was analyzed for composition by .sup.13C-NMR and .sup.1H-NMR spectroscopy, and for Mw and Mw/Mn by GPC versus polystyrene standards using THF solvent.

##STR00120## ##STR00121##

Synthesis Example 1

Synthesis of Polymer P-1

[0127] A 2-L flask was charged with 2.4 g of Monomer M-1, 4.1 g of Monomer AM-1, 7.2 g of 4-hydroxystyrene, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of azobisisobutyronitrile (AIBN) was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., yielding Polymer P-1. Polymer P-1 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00122##

Synthesis Example 2

Synthesis of Polymer P-2

[0128] A 2-L flask was charged with 2.4 g of Monomer M-1, 3.8 g of Monomer AM-2, 7.8 g of 4-hydroxystyrene, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C. yielding Polymer P-2. Polymer P-2 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00123##

Synthesis Example 3

Synthesis of Polymer P-3

[0129] A 2-L flask was charged with 2.4 g of Monomer M-2, 4.0 g of Monomer AM-3, 6.0 g of 4-hydroxystyrene, 3.6 g of 4-hydroxyphenyl methacrylate, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol, and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., yielding Polymer P-3. Polymer P-3 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00124##

Synthesis Example 4

Synthesis of Polymer P-4

[0130] A 2-L flask was charged with 2.7 g of Monomer M-3, 4.9 g of Monomer AM-1, 5.4 g of 4-hydroxystyrene, 6.8 g of Monomer PM-1, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C. yielding Polymer P-4. Polymer P-4 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00125##

Synthesis Example 5

Synthesis of Polymer P-5

[0131] A 2-L flask was charged with 5.1 g of Monomer M-4, 4.9 g of Monomer AM-1, 4.8 g of 4-hydroxystyrene, 5.9 g of Monomer PM-2, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., yielding Polymer P-5. Polymer P-5 was analyzed by .sup.13C— and .sup.1-H-NMR and GPC, with the results shown below.

##STR00126##

Synthesis Example 6

Synthesis of Polymer P-6

[0132] A 2-L flask was charged with 3.2 g of Monomer M-1, 4.9 g of Monomer AM-1, 4.8 g of 4-hydroxystyrene, 5.6 g of Monomer PM-3, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., yielding Polymer P-6. Polymer P-6 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00127##

Synthesis Example 7

Synthesis of Polymer P-7

[0133] A 2-L flask was charged with 1.6 g of Monomer M-1, 8.3 g of Monomer AM-4, 6.0 g of 3-hydroxystyrene 7.4 g of Monomer PM-4, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., yielding Polymer P-7. Polymer P-7 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00128##

Synthesis Example 8

Synthesis of Polymer P-8

[0134] A 2-L flask was charged with 3.2 g of Monomer M-1, 4.9 g of Monomer AM-1, 5.9 g of 4-hydroxy-3-methoxystyrene, 5.6 g of Monomer PM-3, and 40 g of THF solvent. The reactor was cooled at −70° C. in a nitrogen atmosphere, after which vacuum pumping and nitrogen blow were repeated three times. The reactor was warmed up to room temperature, whereupon 1.2 g of AIBN was added. The reactor was heated at 60° C., whereupon reaction ran for 15 hours. The reaction solution was concentrated to a half volume and poured into a mixture of 1 L of methanol and 0.1 L of water for precipitation. The resulting white solid was collected by filtration and dried in vacuum at 60° C., yielding Polymer P-8. Polymer P-8 was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00129##

Comparative Synthesis Example 1

Synthesis of Comparative Polymer cP-1

[0135] A comparative polymer cP-1 was synthesized by the same procedure as in Synthesis Example 1 aside from using 2.3 g of acenaphthylene instead of Monomer M-1. The polymer was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00130##

Comparative Synthesis Example 2

Synthesis of Comparative Polymer cP-2

[0136] A comparative polymer cP-2 was synthesized by the same procedure as in Synthesis Example 1 aside from using N-phenylmaleimide instead of Monomer M-1. The polymer was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00131##

Comparative Synthesis Example 3

Synthesis of Comparative Polymer cP-3

[0137] A comparative polymer cP-3 was synthesized by the same procedure as in Synthesis Example 1 aside from using N-ethylitaconimide instead of Monomer M-1. The polymer was analyzed by .sup.13C— and .sup.1H-NMR and GPC, with the results shown below.

##STR00132##

[2] Preparation and Evaluation of negative Resist Compositions

Examples 1 to 10 and Comparative Examples 1 to 3

(1) Preparation of Negative Resist Compositions

[0138] A negative resist composition was prepared by dissolving the selected components in a solvent in accordance with the recipe shown in Table 1, and filtering through a filter with a pore size of 0.2 μm. The solvent contained 50 ppm of surfactant Poly Fox PF-636 (Omnova Solutions Inc.)

[0139] The components in Table 1 are identified below.

Organic Solvent

[0140] PGMEA (propylene glycol monomethyl ether acetate)

[0141] EL (ethyl lactate)

Acid Generator: PAG-1

[0142] ##STR00133##

(2) EB Lithography Test

[0143] A silicon substrate having a diameter of 6 inches was vapor primed with hexamethyldisilazane (HMDS) at 110° C. for 60 seconds. Using a coater/developer system Clean Track Mark 5 (Tokyo Electron Ltd.), the negative resist composition shown in Table 1 was spin coated onto the substrate and pre-baked on a hotplate at 110° C. for 60 seconds to form a resist film of 80 nm thick. Using a system HL-800D (Hitachi Ltd.) at a HV voltage of 50 kV, the resist film was exposed imagewise to EB in a vacuum chamber.

[0144] Using Clean Track Mark 5, immediately after the imaging, the resist film was baked (PEB) on a hotplate at the temperature shown in Table 1 for 60 seconds and puddle developed in a 2.38 wt % TMAH aqueous solution for 30 seconds to form a negative pattern.

[0145] The resulting resist pattern was evaluated as follows. Sensitivity is the exposure dose that provides a 1:1 resolution of a 100-nm line-and-space (LS) pattern. Resolution is a minimum size at that dose. The 100-nm LS pattern was measured for line edge roughness (LER) under SEM. The results are shown in Table 1 together with the formulation of resist composition.

TABLE-US-00001 TABLE 1 Base Acid PEB polymer generator Quencher Organic solvent temp. Sensitivity Resolution LER (pbw) (pbw) (pbw) (pbw) (° C.) (μC/cm.sup.2) (nm) (nm) Example 1 P-1 PAG-1 Q-1 PGMEA (1,500) 110 39.3 70 5.2 (100) (12) (4.0) EL (1,000) 2 P-2 PAG-1 Q-1 PGMEA (1,500) 110 42.5 70 5.8 (100) (12) (4.0) EL (1,000) 3 P-3 PAG-1 Q-1 PGMEA (1,500) 120 49.6 70 5.9 (100) (12) (4.0) EL (1,000) 4 P-1 (60) PAG-1 Q-1 PGMEA (1,500) 120 45.8 70 5.7 P-3 (40) (12) (4.0) EL (1,000) 5 P-4 — Q-1 PGMEA (1,500) 80 43.6 65 4.1 (100) (4.0) EL (1,000) 6 P-5 — Q-1 PGMEA (1,500) 80 41.2 65 4.2 (100) (4.0) EL (1,000) 7 P-6 — Q-1 PGMEA (1,500) 80 42.1 65 4.2 (100) (4.0) EL (1,000) 8 P-7 (50) PAG-1 Q-1 PGMEA (1,500) 80 46.2 65 4.8 bP-1 (50)  (7) (4.0) EL (1,000) 9 P-1 (50) PAG-1 Q-1 PGMEA (1,500) 85 44.7 65 4.7 P-6 (50)  (7) (4.0) EL (1,000) 10 P-8 — Q-1 PGMEA (1,500) 80 45.6 70 4.2 (100) (4.0) EL (1,000) Comparative 1 cP-1 PAG-1 Q-1 PGMEA (1,500) 110 50.0 80 7.1 Example (100) (12) (4.0) EL (1,000) 2 cP-2 PAG-1 Q-1 PGMEA (1,500) 110 48.0 80 7.1 (100) (12) (4.0) EL (1,000) 3 cP-3 — Q-1 PGMEA (1,500) 110 44.0 75 6.1 (100) (4.0) EL (1,000)

[0146] As seen from Table 1, the negative resist composition within the scope of the invention meets satisfactory resolution and reduced LER.

[0147] Japanese Patent Application No. 2021-023472 is incorporated herein by reference.

[0148] Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.