Reduction processes in the fast atom bombardment mass spectrometry of sulfonyl esters of diazonaphthalenones

Abstract

AbstractOrthoquinone diazides, which are widely used in microlithography, have attracted considerable attention, especially in terms of their application in the production of high‐contrast resists. Previous electron impact mass spectrometric results have confirmed that the primary fragmentation process of these compounds is the elimination of N2 to form an indenoketene ion. This is analogous to the photodecomposition pathway which makes them effective in the lithographic process. Those results also revealed the occurrence of an alternative process, which involves a two‐hydrogen reduction of the intermediate species formed prior to conversion to the ketene. The present study investigates the behaviour of the orthoquinone diazides when there is an abundance of protons available to form the reduction product. Several different types of diazonaphthalenone sulfonyl esters, ranging in complexity from the monosubstituted phenol esters to disubstituted dihydroxybenzophenones, were examined using fast atom bombardment mass spectrometry. Although reduction was the primary process in the hydrogen‐rich matrices, the extent of reduction was characteristic of the particular isomer as well as the matrix used.