Positive tone ultra thick photoresist composition

A positive working chemically amplified photosensitive composition comprising:

• Component a) at least one random copolymer, having structure (A), wherein
• the repeat unit of structure (I) ranges from about 17 mole % to about 70 mole %,
• the repeat unit of structure (II) ranges from 0 to about 70 mole %,
• the repeat unit of structure (III) ranges from 0 to about 70 mole %,
• the sum of the repeat unit of structures (II) and (III) ranges from about 30 mole % to about 70 mole %,
• the repeat unit of structure (IV) ranges from about 0 mole % to about 35 mole %, wherein the sum of the mole % of the repeat units of structure (I), (II), (III), and (IV) either does not exceed 100 mole % or is equal to 100 mole %, if other types of repeat units are not present, Ri1, Ri2, Ri14 and Ri13 are individually selected from H or a C-1 to C-4 alkyl, Ri3, Ri4, Ri5, Ri6, R7, Ri8, Ri9, Ri10, Ri11, and Ri12, are individually selected from H, a C-1 to C-8 alkyl, a C-1 to C-4 alkoxy, a phenyl, a substituted phenyl, and mixtures thereof, Li1 is a C-2 to C-6 alkylene moiety, ni, mi, oi and pi are respectively the number of repeat units of structure (I), (II), (III) and (IV), and further wherein,
• the copolymer of structure (A) has a minimum dissolution rate of 500 Å/sec in 0.26 N tetramethylammonium hydroxide at 23° C., and does not comprise any repeat units which have acid cleavable groups:
• component b) at least one acrylic copolymer component of structure (B) comprising repeat units selected from ones having structure (1), (2), (3), (4), (5), (6), and (7):
• wherein
• R1, R2, R3, R4, R5, R6, and R7 are individually selected from either H, F, a C-1 to C-4 perfluoroalkyl, or a C-1 to C-4 alkyl,
• R8 and R9 are individually selected from H, a C-1 to C-4 alkyl, a C-1 to C-4 alkyloxy alkyl, and a halogen,
• R10 is selected from the group consisting of a C-1 to C-8 primary alkyl, a C-3 to C-8 secondary alkyl, a C-3 to C-8 cyclic secondary alkyl, and a C-7 to C-14 secondary alicyclic alkyl,
• R11 is a C-2 to C-8 (hydroxy)alkylene moiety,
• R12 is a tertiary alkyl acid cleavable group, and
• R13 is a C-3 to C-12, (alkyloxy)alkylene moiety;
• and further
• these repeat units in total constitute 100 mole % of the repeat units in said functionalized acrylic copolymer, wherein,
• the repeat unit of structure (1) ranges from about 0 mole % to about 20 mole % of the acrylic copolymer,
• the repeat unit of structure (2) ranges from about 0 mole % to about 20 mole % of the acrylic copolymer,
• wherein the repeat unit of structure (3) ranges from about 5 mole % to about 55 mole % of the acrylic copolymer,
• wherein the repeat unit of structure (4) ranges from about 0 mole % to about 30 mole % of the acrylic copolymer,
• the repeat unit of structure (5) ranges from about 15 mole % to about 55 mole % of the acrylic copolymer,
• the repeat unit of structure (6) ranges from about 18 mole % to about 40 mole % of the acrylic copolymer
• the repeat unit of structure (7) ranges from about 0 mole % to about 40 mole % of the acrylic copolymer
• component c) at least one Novolak polymer,
• component d) at least one photoacid generator (PAG),
• component e) at least one base additive,
• component f) at least one heterocyclic thiol compound,
• component g) an organic spin casting solvent.