Positive resist composition for electron beam, X-ray or EUV and pattern forming method using the same

1. A positive resist composition for electron beam, X-ray or EUV, comprising:

a compound having a proton acceptor functional group and capable of producing an acid radical upon irradiation with an actinic ray or radiation to reduce or lose the acceptor property or to change the proton acceptor functional group to be acidic,

wherein

the positive resist composition has a solid content concentration of from 2.5 to 4.5 mass %.

2. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 1 , wherein

said compound is a compound capable of generating an organic acid represented by the following formula (I) upon irradiation with an actinic ray or radiation:

HO3S-A-(X) n —B—R  (I)

wherein

A represents a divalent linking group,

X represents —SO2- or —CO—,

n represents 0 or 1,

B represents a single bond, an oxygen atom or N(Rx)—,

Rx represents a hydrogen atom or a monovalent organic group,

R represents a monovalent organic group containing a proton acceptor functional group, or a monovalent organic group containing an ammonium group, and

when B is —N(Rx)—, R and Rx may combine to form a ring.

3. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 1 , further comprising:

a resin capable of decomposing by the action of an acid to increase the solubility in an alkali developer.

4. A pattern forming method comprising:

forming a resist film from the positive resist composition claimed in claim 1 ,

exposing said resist film with an electron beam, X-ray or EUV, and

developing said resist film.

5. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 3 , wherein the resin capable of decomposing by the action of an acid to increase the solubility in an alkali developer has a hydroxystyrene repeating unit.

6. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 5 , wherein the resin capable of decomposing by the action of an acid to increase the solubility in an alkali developer has a repeating unit represented by formula (II) and a repeating unit represented by formula (III):

wherein,

each R 01 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group;

each of L 1 and L 2 , which may be the same or different, represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aralkyl group;

M represents a single bond or a divalent linking group;

Q represents an alkyl group, a cycloalkyl group or an alicyclic or aromatic ring group which may contain a heteroatom;

A represents a halogen atom, a cyano group, an acyl group, an alkyl group, an alkoxy group, an acyloxy group or an alkoxycarbonyl group;

at least two members out of Q, M and L 1 may combine to form a 5- or 6-membered ring; and

each of m and n represents an integer of 0 to 4.

7. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 5 , wherein the resin capable of decomposing by the action of an acid to increase the solubility in an alkali developer has a repeating unit represented by formula (V):

wherein,

each of Ra, Rb, and Rc independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group; and

X 1 represents a hydrogen atom or an organic group.

8. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 7 , wherein X 1 represents an acid decomposable group.

9. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 3 , wherein a weight average molecular weight of the resin capable of decomposing by the action of an acid to increase the solubility in an alkali developer is 5,000 or less.

10. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 1 , wherein the partial structure of the proton acceptor functional group is selected from the group consisting of crown ether, aza-crown ether, tertiary amine, secondary amine, primary amine, pyridine, imidazole and pyrazine structures.

11. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 2 , wherein the partial structure of the proton acceptor functional group is selected from the group consisting of crown ether, aza-crown ether, tertiary amine, secondary amine, primary amine, pyridine, imidazole and pyrazine structures.

12. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 1 , wherein the compound having a proton acceptor functional group and capable of producing an acid radical upon irradiation with an actinic ray or radiation to reduce or lose the acceptor property or to change the proton acceptor functional group to be acidic is a compound represented by formula (A3):

wherein,

each of R 1 to R 13 independently represents a hydrogen atom or a substituent, and at least one of R 1 to R 13 is a substituent containing an alcoholic hydroxyl group;

Z represents a single bond or a divalent linking group; and

X − represents an anion containing a proton acceptor functional group.

13. The positive resist composition for electron beam, X-ray or EUV as claimed in claim 1 , wherein the positive resist composition further comprises a compound capable of generating an acid upon irradiation with an actinic ray or radiation.