Additives to negative photoresists which increase the sensitivity thereof

The use of a scanning electron beam to generate a pattern in a negative photoresist is known. Electron beam equipment can be made which is capable of scanning very quickly, but standard negative photoresists require such a large flux of electrons for proper exposure that the scanning equipment must be operated at speeds substantially slower than the capability of the equipment. By adding certain compounds which dissociate readily into free radicals to the photoresist, the sensitivity or speed of the photoresist is effectively increased. As a result, the electron beam can scan at a higher rate. Compounds which are most effective are benzophenone, benzil and 1,4-diphenyl-1,3-butadiene.