Pre-exposure method for increased sensitivity in high contrast resist development of positive working diazo ketone photoresist

Claim 1

A process for developing a positive photoresist pattern in an ultraviolet (UV) or visible radiation sensitive diazo ketone/novalac resin photoresist, in a high contrast system, wherein the photoresist comprises a continuous coating on the surface of a supporting substrate, the process comprising: flood exposing the coating, over the area which is to receive the positive photoresist pattern, with a first predetermined amount of radiation in the UV or visible range or a combination thereof, said first predetermined amount of radiation being insufficient alone to produce more than about 5% film loss with subsequent development of the photoresist; pattern exposing the coating, over the area which is to receive the positive photoresist pattern, with a second predetermined amount of radiation in the UV or visible range or by electron beam, to form a latent image of the pattern in the photoresist, said second predetermined amount of radiation being insufficient alone to produce more than about 5% film loss with subsequent development of the photoresist, said first and second predetermined amounts of radiation being applied to the coating directly, rather than indirectly via any uncoated surface of the substrate, with the proviso that said first and second predetermined amounts of radiation cumulatively are sufficient to produce significant film loss, and thereby a positive image, in areas irradiation by both said first and second predetermined amounts of radiation; and thereafter developing the photoresist to remove areas exposed to both said first and second predetermined amounts of radiation with a high contrast aqueous alkaline developer to thereby produce a positive pattern image.