Copolymer with acid-labile group, photoresist composition, coated substrate, and method of forming an electronic device

1. A copolymer comprising repeat units derived from an acid-labile monomer having formula (I)

wherein

R 1 is an unsubstituted or substituted C 1-18 alkyl;

R 2 is an unsubstituted or substituted C 1-18 alkyl, an unsubstituted or substituted C 7-18 arylalkyl, or an unsubstituted or substituted C 6-18 aryl;

R 3 is —H, —F, —CH 3 , or —CF 3 ; and

Ar is an unsubstituted or substituted C 6-18 aryl;

provided that R 2 and Ar collectively include at least nine carbon atoms;

a lactone-substituted monomer;

a base-soluble monomer having a pK a less than or equal to 12; and

a photoacid-generating monomer comprising

2. The copolymer of claim 1 , wherein R 1 is C 1-3 alkyl.

3. The copolymer of claim 1 , wherein R 2 is C 1-3 alkyl, phenyl, or C 1-6 alkyl-substituted phenyl.

4. The copolymer of claim 1 , wherein Ar is phenyl, C 1-6 -alkyl-substituted phenyl, biphenyl, or naphthyl.

5. The copolymer of claim 1 , wherein the acid-labile monomer comprises

or a combination thereof.

6. A photoresist composition comprising the copolymer of claim 1 .

7. A coated substrate comprising:

(a) a substrate having one or more layers to be patterned on a surface thereof; and

(b) a layer of the photoresist composition of claim 6 over the one or more layers to be patterned.

8. A method of forming an electronic device, comprising:

(a) applying a layer of a photoresist composition of claim 6 on a substrate;

(b) pattern-wise exposing the photoresist composition layer to activating radiation; and

(c) developing the exposed photoresist composition layer to provide a resist relief image.

9. A copolymer comprising repeat units derived from

an acid-labile monomer having formula (I)

wherein

R 1 is an unsubstituted or substituted C 1-18 alkyl;

R 2 is an unsubstituted or substituted C 1-18 alkyl, an unsubstituted or

substituted C 7-18 arylalkyl, or an unsubstituted or substituted C 6-18 aryl;

R 3 is —H, —F, —CH 3 , or —CF 3 ; and

Ar is an unsubstituted or substituted C 6-18 aryl;

provided that R 2 and Ar collectively include at least nine carbon atoms;

a lactone-substituted monomer comprising

a base-soluble monomer comprising

 and

a photoacid-generating monomer comprising

10. The copolymer of claim 9 ,

wherein the acid-labile monomer comprises

or a combination thereof.