Patent ID: 9543160
Date: 2017-01-10
CPC Classifications: H01L

Claim:
1. A method comprising: forming a mask layer over an underlying layer; forming a first patterned photo resist over the mask layer; performing a first etching step on the mask layer using the first patterned photo resist as an etching mask, thereby forming a first etched mask layer; removing the first patterned photo resist; forming a particle-fixing layer contacting the first etched mask layer, wherein the particle-fixing layer fills a lower portion of a gap between two neighboring remaining portions of the first etched mask layer, wherein an upper portion of the gap is unfilled by the particle-fixing layer; forming a second patterned photo resist over the particle-fixing layer and the first etched mask layer; performing a second etching step on the particle-fixing layer and the mask layer using the second patterned photo resist as an etching mask, thereby forming a second etched mask layer; patterning the underlying layer using the second etched mask layer as a mask; and removing the second etched mask layer.