Synthesis and characterization of statistical copolymers of styrene and 4‐(1‐hydroxyalkyl)styrene

Abstract

A family of new polymers based on poly(4-(1-hydroxyalkyl)styrene), and its copolymers with styrene were synthesized and thoroughly characterized by 1 H-NMR, 13 C-NMR, FTIR, and UV spectroscopies. The chemical modification reactions of polystyrene (PS) was used as a novel method of performing the synthesis of poly(4-(1-hydroxyethyl-co-styrene)), poly(4-(1-hydroxypropyl-co-styrene)), poly(4-(1-hydroxybutyl-co-styrene)), and poly(4-(1-hydroxyphenylmethyl-co-styrene)). The novelty of this method lies in the incorporation of the desired mol % of the functional groups in polystyrene chain, to obtain random copolymers of desired composition. In preliminary testing/evaluation studies the utility and versatility of the new copolymers, which have the potential to be negative-tone photoresist materials, were studied. Thus a few photoresist formulations based on poly-(styrene-co-4-(1-hydroxyalkylstyrene)) were developed with 5 wt % of a photoacid generator. These studies suggested that the new copolymers synthesized by a simple and alternate method could have the same potential as a photoresist material when compared with the polymers synthesized by the polymerization of the corresponding functional monomer.

Poly(4-(1-hydroxyalkyl)styrene based photoresist materials: design, synthesis, and their lithographic performance

“…The detailed characterizations of the copolymers are reported elsewhere. 4 FTIR of the four copolymers synthesized are presented in the Fig. 3.…”

“…4,9 Acetylated copolymers of desired extent of acetylation were obtained by varying the amount of acetylating reagent. Similar procedure was adopted for the synthesis of PrPS-co-PS, BuPS-co-PS and BPS-co-PS at desired extent of acylation by varying the amount of different acylating agents were obtained as given in the Scheme 1.…”

“…Significant advances have been made by Dhamodharan et al in functionalizing PS at the para position without side reactions as well as crosslinking. [2][3][4][5][6][7][8][9][10] Almost all chemically amplified resists optimized for DUV lithography utilize homo-and co-polymers derived from 4-hydroxystyrene (4-HS) as the materials of choice. [11][12][13][14] Some attempts have also been made for synthesizing non-PHS based polymers for DUV such as poly(4-(1-hydroxy-1-phenylethyl)styrene).…”

Characterization of acrylic copolymers applied in negative‐type photoresist via a ternary composition diagram

“…value is the amount of KOH in milligrams needed to reach the equivalent point for one gram of the prepared binder (mg/g). 6. Viscosity of the as-synthesized binder solution was measured using a viscometer (RVDV-II1CP, Brookfield, Middleboro, MA), and the spindle LV2 was used.…”

“…Photoresists are widely used for the manufacture of microelectronics, silk screen printings, printed circuit boards, optical disks, color filter resists, and so on. [5][6][7] Typically, a negative-type photoresist consists of polymer binder, photosensitive polyfunctional monomer, photoinitiator, solvents and additives. 8,9 Acrylic monomers used to synthesize the binder contain the desired functional groups, such as benzyl, hydroxyl, carboxyl groups, etc.…”