Patent ID: 6251547
Filing Date: 2001-06-26
Classification: G03F

Abstract:
A method of forming a mask, comprising the steps of:providing a mask substrate;forming a first mask layer on said substrate;forming a second mask layer on said first mask layer;forming a layer of energy sensitive resist over said second mask layer;transferring a certain first portion of a pattern to said resist by depositing energy of such an amount that the resist is exposed to its maximum depth;transferring a certain second portion of a pattern to said resist by depositing energy of a lesser amount;developing the exposed portions of the resist and removing them;removing the second mask layer that is exposed by the deeper of the two openings in the resist;removing the first mask layer that is exposed by the removal of said second mask layer;increasing the depth of the shallower openings in the resist by use of a selective, anisotropic etchant until the second mask layer is exposed;removing said second mask layer by a dry or wet etch;stripping away the remaining resist layer.