Patent ID: 11914294
Assignee: SHIN-ETSU CHEMICAL CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A positive resist composition comprising a base polymer comprising repeat units having the formula (a):, , wherein RA is hydrogen or methyl,
X1 is each independently a single bond, phenylene, naphthylene, or a C1-C16 linking group containing an ester bond, ether bond or lactone ring, and
R is an acid labile group having the formula (a1) or (a2):, , wherein R1, R2 and R3 are each independently halogen, trifluoromethyl or a C1-C6 saturated hydrocarbyl group,
RN1 and RN2 are each independently hydrogen, a C1-C10 alkyl group, C2-C10 alkenyl group, C2-C10 alkynyl group, C2-C10 alkoxycarbonyl group or C1-C10 acyl group, the alkyl, alkenyl, alkynyl, alkoxycarbonyl and acyl groups optionally containing an ether bond or halogen,
the circle Ra is a C2-C10 alicyclic group including the nitrogen atom,
m1, m2 and m3 are each independently an integer of 0 to 5, and
the broken line designates a valence bond,
wherein the base polymer further comprises repeat units having a carboxy group substituted by an acid labile group and/or repeat units having a phenolic hydroxy substituted by an acid labile group, with the proviso that these units are exclusive of the repeat units having formula (a), and
wherein a fraction of the repeat units having a carboxy group substituted by an acid labile group and/or repeat units having a phenolic hydroxy group substituted by an acid labile group in the base polymer is 0.15 to 0.7.