Patent ID: 7084950
Filing Date: 2006-08-01
Classification: G03F

Abstract:
1. A chromeless photomask for use in a photolithographic process of forming a desired pattern on a photoresist layer disposed on a substrate, said chromeless photomask comprising: a substrate of a material that will transmit an exposure light of the photolithographic process therethrough and having a core area and a peripheral area adjacent an outer periphery of said core area; and a main pattern portion occupying said core area, and a complementary pattern portion occupying said peripheral area, said main pattern portion being constituted by a raised portion of material that will transmit the exposure light and a recessed portion of material that will transmit the exposure light, the difference in height between the raised and recessed portions of said main pattern portion being such that rays of the exposure light passing through the raised portion will be out of phase by 180 degrees with respect to rays of the exposure light passing through the recessed portion, and the raised and recessed portions of said main pattern portion constituting a first pattern dedicated to produce interference, during the photolithographic process, that will form the desired pattern on the photoresist layer, said complementary pattern portion being constituted by a raised portion of material that will transmit the exposure light and a recessed portion of material that will transmit the exposure light, the difference in height between the raised and recessed portions of said complementary pattern portion being such that rays of the exposure light passing through the raised portion thereof will be out of phase by 180 degrees with respect to rays of the exposure light passing through the recessed portion thereof, and the raised and recessed portions of said complementary pattern portion constituting a second pattern that is different from said first pattern, and that will produce interference, during the photolithographic process, that will enhance the portion of the desired pattern formed on the photoresist layer by light passing through an outer edge of the main pattern portion.