Patent ID: 8530147

Claim:
A method for patterning a material layer consisting of: forming an unpatterned first mask layer on the material layer; exposing and developing for patterning the unpatterned first mask layer to form a patterned first mask layer, wherein the patterned first mask layer has a plurality of patterns therein and a plurality of gaps within the patterns and the gaps expose a portion of the material layer directly followed by forming a second mask layer over the material layer, wherein the second mask layer fills the gaps; after the second mask layer is formed, performing a treatment to the second mask layer so as to form an interface layer between and directly contacting the patterned first mask layer and the second mask layer; removing a portion of the second mask layer until the top surface of the interface layer is exposed to remain a rest of the second mask layer; removing the interface layer to expose a portion of the material layer while the rest of the second mask layer and the patterned first mask layer remain; and patterning the material layer by using the patterned first mask layer and the rest of the second mask layer as a mask.