Patent ID: 6555275
Filing Date: 2003-04-29
Classification: B82Y,G03F,H01J,Y10S

Abstract:
A method of manufacturing a photomask, comprising:forming at least one of a phase shift film and an opaque layer on a transparent substrate; coating said at least one of the phase shift film and the opaque layer with an electron beam resist; exposing the electron beam resist to a first electron beam having an accelerating voltage so low and of such a dosage that the electron beam resist absorbs an amount of energy less than the threshold energy of the resist, the threshold energy being that necessary to cause the electron beam resist to develop when subjected to a developing process designated for use in developing the resist; exposing the electron beam resist to a second electron beam having an accelerating voltage greater than that of the first electron beam and of a dosage sufficient to cause the resist to absorb an amount of energy which, when added to the energy absorbed by the resist as the result of its exposure to the first electron beam, exceeds the threshold energy of the resist required for the resist to develop when subjected to said developing process; wherein at least one of the steps of exposing the electron beam resist to an electron beam comprises irradiating the resist in a pattern; subsequently developing the electron beam resist using said developing process, whereby selected portions of the resist corresponding to the pattern are removed, to thereby form an electron beam resist pattern; and subsequently etching said at least one of the phase shift film and the opaque layer, using the electron beam resist pattern as an etching mask.