| abstract |
A negative working photoresist is disclosed responsive to imaging radiation of a visible wavelength shorter longer than 550 nm comprised of an organic film forming component containing ethylenic unsaturation and capable of selective immobilization by addition at the site of ethylenic unsaturation and activator and photosensitizer coinitiators for ethylenic addition. The activator is an azinium salt activator, and the photosensitizer is a dye having its principal absorption peak at a wavelength shorter than 550 nm and having a reduction potential which in relation to that of said azinium salt activator is at most 0.1 volt more positive. When the dye is a keto dye, it exhibits when excited by imaging radiation an intersystem crossing efficiency to a triplet state of less than 10 percent. |