Abstract: A photomask is formed by depositing an opaque layer on a transparent substrate. A resist is formed on the opaque layer and selectively patterned to expose the portions of the opaque layer that are to be etched out. During the dry etching step, the photomask is exposed to an etchant gas mixture which exhibits a selectivity equal to or higher than 1.2:1 between the opaque layer and the resist layer. Due to the selectivity of the gas mixture, a thinner resist film can be used, thereby increasing resolution and accuracy of the opaque layer pattern. Also, due to reduced susceptibility to both a macro-loading effect and a pattern density effect, overetching of the resist and underetching of the opaque layer are significantly reduced, thereby achieving improved etching uniformity and consequently improved CD uniformity.

Abstract: An exposure method includes the steps of transferring, by exposure, a pattern formed on an original to different shot regions on a substrate sequentially, and performing, during exposure of a certain shot, at least one of (i) adjusting a relative positional relation between the original and the substrate, with respect to a direction effective to correct translation of a transfer region of the substrate due to thermal distortion thereof, and (ii) adjusting a transfer magnification of the pattern of the original to the substrate so as to correct enlargement of the transfer region due to thermal distortion of the substrate. In one preferred form, the adjustment is made in accordance with a correction table related to thermal expansion of the substrate during exposure and being prepared on the basis of one of a calculation and a preparatory exposure experiment.