A positive-working alkaline developable photoresist based on partially tert-Boc-protected calix[4]resorcinarene and a photoacid generator

Abstract

A positive working low- molecular- weight photoresist based on partially t- Boc protected tetra- C-methylcalix[ 4] resorcinarene (t- Boc C- 4- R) and a photoacid generator (PAG), diphenyliodonium 9,10- dimethoxyanthracene- 2- sulfonate (DIAS) has been developed. t- Boc C- 4- Rs were prepared by the reaction of C- 4- R with di- tert- butyl dicarbonate in the presence of 4- dimethylaminopyridine (DMAP). A clear film cast from a 20 wt% t- Boc C- 4- R solution in cyclohexanone showed high transparency to UV above 300 nm. The appropriate t- Boc protecting ratio was about 60 mol% in view of adhesion, deprotection temperature and dissolution rate. The photoresist consisting of 60 mol% t- Boc C- 4- R (95 wt%) and DIAS (5 wt%) showed a sensitivity of 13 mJ cm(-2) and a contrast of 12.6 when it was exposed to 365 nm light and postbaked at 105 degreesC for 90 s, followed by developing with a 2.38 wt% aqueous tetramethylammonium hydroxide (TMAH) solution at room temperature. A fine positive image featuring 1.5 mum of minimum line and space patterns was observed on the film of the photoresist exposed to 40 mJ cm(-2) of UV- light at 365 nm by the contact mode.