Patent ID: 7862986

Claim:
A method for patterning a material layer comprising: forming a mask layer on the material layer; forming a first photoresist layer on the mask layer; performing a first exposure process on the first photoresist layer; performing a first develop process to remove the exposed first photoresist layer together with a portion of the mask layer exposed by the exposed first photoresist layer to form a first pattern of a first pitch; removing the first photoresist layer; forming a second photoresist layer; performing a second exposure process on the second photoresist layer; performing a second develop process to remove the exposed second photoresist layer together with a portion of the mask layer exposed by the second photoresist layer to form in the mask layer a second pattern of a second pitch that exposes a portion of the material layer, wherein the second pitch is less than the first pitch; removing the second photoresist layer; hardening the mask layer after the second photoresist layer is removed; forming a third photoresist layer with a third pattern on the portion of the material layer exposed by the second pattern, wherein the third photoresist layer and the second pattern together form a fourth pattern; and patterning the material layer by using the fourth pattern as an etching mask.