Molecular resist composition and patterning process

Patent metadata

Field	Value
Publication number	US-11940728-B2
Application number	US-202117484333-A
Country	US
Kind code	B2
Filing date	Sep 24, 2021
Priority date	Sep 28, 2020
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

A molecular resist composition and a pattern forming process. A molecular resist composition comprising a sulfonium salt having a cation of specific structure and an organic solvent has a high sensitivity and forms a resist film with improved resolution and LWR, when processed by EB or EUV lithography. The molecular resist composition does not contain a base polymer. The molecular resist composition comprising a sulfonium salt having a cation of specific partial structure has a high sensitivity and forms a resist film with improved resolution and LWR, so that the resist composition is quite useful for precise micropatterning.

First claim

The invention claimed is:

1. A molecular resist composition comprising a sulfonium salt having the formula (1) and an organic solvent, wherein the molecular resist composition does not contain a base polymer,

wherein Ar 1 , Ar 2 and Ar 3 are each independently a C 6 -C 20 aryl group in which some or all of the hydrogen atoms on its aromatic ring may be substituted by halogen or a C 1 -C 20 hydrocarbyl group which may contain a heteroatom, at least one of Ar 1 , Ar 2 and Ar 3 is substituted with a group having the formula (1a), (1b) or (1c), any two of Ar 1 , Ar 2 and Ar 3 may bond together to form a ring with the sulfur atom to which they are attached,

wherein R a1 , R a2 and R a3 are each independently hydrogen or a C 1 -C 10 hydrocarbyl group; R b1 , R b2 and R b3 are each independently a C 1 -C 10 hydrocarbyl group, R b1 and R b2 may bond together to form a ring with the carbon atom to which they are attached; R c1 and R c2 are each independently hydrogen or a C 1 -C 10 hydrocarbyl group, R c3 , R c4 and R c5 are each independently a C 1 -C 10 hydrocarbyl group, R c3 and R c4 may bond together to form a ring with the carbon atom to which they are attached; the broken line designates a valence bond, and
X − is an anion, exclusive of a halide ion, BF 4 − , PF 6 − , SbF 6 − and anions having the following formulae (ex1) to (ex4):

wherein R ex1 is halogen or a C 1 -C 40 hydrocarbyl group which may contain a heteroatom; R ex2 , R ex3 , R ex4 , R ex5 and R ex6 are each independently fluorine or a C 1 -C 40 hydrocarbyl group which may contain a heteroatom, R ex2 and R ex3 may bond together to form a ring with the carbon atoms to which they are attached and intervening atoms, R ex4 and R ex5 may bond together to form a ring with the carbon atoms to which they are attached and intervening atoms; R ex7 is halogen, hydroxy or a C 1 -C 40 hydrocarbyl group which may contain a heteroatom; R ex8 and R ex9 are each independently fluorine or trifluoromethyl.

2. The molecular resist composition of claim 1 wherein Ar 1 , Ar 2 and Ar 3 are a group having the formula (2), (3) and (4), respectively:

wherein R 1 to R 21 are each independently hydrogen, hydroxy, cyano, halogen, a C 1 -C 20 hydrocarbyl group which may contain a heteroatom, or a group having any one of formulae (1a) to (1c), at least one of R 1 to R 21 being a group having any one of formulae (1a) to (1c), p, q and r are each independently 0 or 1, the broken line designates a valence bond.

3. The molecular resist composition of claim 1 wherein X − is nitrate ion, hydrogensulfate ion, hydrogencarbonate ion, tetraphenylborate ion, or an anion having any one of the formulae (5) to (8):

wherein R 31 is a C 1 -C 40 hydrocarbyl group which may contain a heteroatom, exclusive of a hydrocarbyl group in which hydrogen on α-carbon relative to the carboxy group is substituted by fluorine or trifluoromethyl,
R 41 and R 42 are each independently a C 1 -C 40 hydrocarbyl group which may contain a heteroatom, exclusive of a hydrocarbyl group in which hydrogen on α-carbon relative to the sulfonyl group is substituted by fluorine or trifluoromethyl, R 41 and R 42 may bond together to form a ring with the sulfur atoms to which they are attached and intervening atom,
R 51 , R 52 and R 53 are each independently a C 1 -C 40 hydrocarbyl group which may contain a heteroatom, exclusive of a hydrocarbyl group in which hydrogen on α-carbon relative to the sulfonyl group is substituted by fluorine or trifluoromethyl, R 51 and R 52 may bond together to form a ring with the sulfur atoms to which they are attached and intervening atom,
R 61 is fluorine or a C 1 -C 10 fluorinated hydrocarbyl group which may contain a hydroxy moiety, ether bond or ester bond, R 62 is hydrogen or a C 1 -C 20 hydrocarbyl group which may contain a hydroxy moiety, ether bond or ester bond, R 61 and R 62 may bond together to form a ring with the atoms to which they are attached.

4. The molecular resist composition of claim 1 , further comprising a radical trapping agent.

5. The molecular resist composition of claim 1 , further comprising a surfactant.

6. A pattern forming process comprising the steps of applying the molecular 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.

7. The process of claim 6 wherein the high-energy radiation is EB or EUV.

8. A molecular resist composition comprising a sulfonium salt selected from the group consisting of the following formulae, and an organic solvent, wherein the molecular resist composition does not contain a base polymer,

Assignees

• Shinetsu Chemical Co

Inventors

• Ohashi Masaki
• Katayama Kazuhiro
• Fukushima Masahiro
• Kikuchi Shun

Classifications

• G03F7/0045 Primary

  with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors · CPC title

• C07C59/84

  containing six membered aromatic rings · CPC title

• C07C309/71

  having sulfur atoms of esterified sulfo groups bound to carbon atoms of rings other than six-membered aromatic rings · CPC title

• C07C381/12

  Sulfonium compounds · CPC title

• C07C2601/14

  The ring being saturated · CPC title