Patent attributes
The present invention relates generally to improved photomask blanks used in photolithography for the manufacture of integrated circuits and other semiconductor devices, and more specifically, to the detection of defects in such photomasks after processing. In particular, the present invention is directed to a photomask blank having one or more intermediate layers made from materials having a higher extinction coefficient at the inspection tool wavelength than exposure tool wavelengths. The intermediate layer(s) are made from materials that absorb a sufficient amount of light to meet the optical requirements of inspection tools while at the same time transmit a sufficient amount of light to meet the optical requirements of exposure tools. As a result, the photomask improves inspection results of a photomask without sacrificing transmission properties during the semiconductor writing process.
