Patent ID: 8492079

Claim:
A method of forming a patterned structure comprising: forming a stack of, from bottom to top, an underlying layer, a second photoresist layer in contact with said underlying layer, and a first photoresist layer on a substrate; lithographically exposing said first photoresist layer by a first illumination at a first exposure wavelength through a first mask, wherein at least one lithographically exposed first photoresist portion of said first photoresist layer becomes optically transparent at a second exposure wavelength and is formed within areas of a first pattern in said first photoresist layer; lithographically exposing said second photoresist layer by a second illumination at said second exposure wavelength through a second mask, said second illumination impinging on an area of a second pattern including a first area within said areas of said first pattern and a second area outside said areas of said first pattern, wherein a portion of said second photoresist layer in said first area becomes a lithographically exposed second photoresist portion and a portion of said second photoresist layer in said second area is not lithographically exposed, wherein a composite pattern is formed by at least one lithographically exposed second photoresist portion of said second photoresist layer that includes said lithographically exposed second photoresist portion, wherein said second composite pattern is the same as said second pattern that is limited only within said first pattern; and transferring said composite pattern into said underlying layer.