Patent ID: 7713818

Claim:
A method of making a device, comprising: forming a first photoresist layer over an underlying layer; patterning the first photoresist layer to form a first photoresist pattern; rendering the first photoresist pattern insoluble to a solvent by forming a barrier layer over the first photoresist pattern; forming a second photoresist layer over the first photoresist pattern; patterning the second photoresist layer to form a second photoresist pattern; and etching the underlying layer using both the first and the second photoresist patterns as a mask; wherein: the barrier layer comprises a thin polymer film having a thickness of less than 10 nm which is disposed on a surface of the first photoresist pattern, such that the underlying layer is exposed in first openings in the first photoresist pattern; and the barrier layer protects the first photoresist pattern from being dissolved by a solvent used during the step of patterning the second photoresist layer.