Two styrene derivatives ((Z)-2

2

2-trifluoro-1-(4'-vinyl-[1

1'-biphenyl]-4-yl)ethan-1-one O-(3-methylbenzoyl) oxime

OXE-P and (Z)-2

2

2-trifluoro-1-(4'-vinyl-[1

1'-biphenyl]-4-yl)ethan-1-one O-thiophene-2-carbonyl oxime

OXE-S) modified by photosensitive oxime ester group were synthesized. They were characterized by hydrogen nuclear magnetic resonance (1H NMR) spectroscopy and high-resolution mass spectrometry (HRMS). New polymers (POXE-P and POXE-S) were prepared by the reversible addition-fragmentation transfer (RAFT) polymerization

and were further measured by gel permeation chromatography (GPC)

giving molecular weights (Mw) of 8.3 and 7.2 kDa

and polydispersity indexes (PDI) of 1.1. Both polymers exhibit good solubility

thermal stability and film-forming ability

which meet the requirements of resist materials. The polymers were dissolved separately in the propylene glycol methyl ether acetate (PGMEA) to form nonchemically-amplified resists (n-CARs). The lithographic performance of the POXE-P resist was examined by e-beam lithography

giving a 50 nm HP (half-pitch) lithographic pattern. The mechanism of POXE-P resist during exposure was investigated by Fourier Transform Infrared Spectrometer (FTIR) and in situ outgassing analysis. It showed that the oxime ester group decomposed during exposure to form carbonyl compounds

CO2

and other small molecules. The cleavage of side chains and the possible crosslinking led to the solubility switch of the polymer

resulting in negative lithographic patterns.