Patent ID: 6093507
Filing Date: 2000-07-25
Classification: G03F

Abstract:
A method of forming phase shifting masks, comprising:providing a mask substrate of transparent material, a layer of opaque material formed on said mask substrate, and a layer of resist formed on said layer of opaque material;exposing a first pattern in the entire thickness of said layer of resist using a first exposure dose;exposing a second pattern in a top portion of said layer of resist using a second exposure dose, wherein said second exposure dose is less than said first exposure dose;developing said layer of resist thereby forming said first pattern in said entire thickness of said layer of resist and said second pattern in said top portion of said layer of resist;etching said first pattern in said layer of opaque material using a first etching means and said first pattern formed in said entire thickness of said layer of resist as a mask;etching said first pattern a first distance into said mask substrate of transparent material using a second etching means and said first pattern formed in said entire thickness of said layer of resist as a mask;etching away part of said layer of resist using a third etching means thereby forming said second pattern in that part of said layer of resist that remains;etching said second pattern in said layer of opaque material using a fourth etching means and said second pattern formed in that part of said layer of resist that remains as a mask; andremoving the remaining said resist.