Photosensitive polymer, resist composition, and associated methods

A method of patterning a material, the method comprising:

• forming a resist layer on the material;
• forming a resist pattern from the resist layer using a lithographic process;
• and
• patterning the material through the resist pattern, wherein:
• the resist layer includes a photosensitive polymer, the photosensitive polymer including repeating units represented by Formulae 1 to 3:
• and, in Formulae 1 to 3:
• R1 and R3 are independently hydrogen or methyl,
• R2 is a C4 to C20 acid-labile group,
• R4 is a lactone-derived group,
• AR is a substituted or unsubstituted phenyl ring, or a substituted or unsubstituted aryl having from two to three fused aromatic rings,
• carbon CAR is bonded directly to an aromatic ring of AR,
• l, m, and n are positive integers,
• 1/(l+m+n) is about 0.1 to about 0.5,
• m/(l+m+n) is about 0.3 to about 0.5, and
• n/(l+m+n) is about 0.1 to 0.4.