| CPC H01L 21/0274 (2013.01) [H01L 21/0337 (2013.01); H01L 21/3086 (2013.01); H01L 21/31105 (2013.01); H01L 21/31127 (2013.01); H01L 21/31144 (2013.01); H01L 21/76804 (2013.01); H01L 21/76807 (2013.01); H01L 21/76816 (2013.01)] | 13 Claims |

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1. A method of patterning an underlying structure, comprising:
providing the underlying structure;
forming a first photoresist material on the underlying structure;
patterning the first photoresist material using a first photomask as a mask to form a first patterned photoresist layer;
performing a first patterning process on the underlying structure to form a first patterned underlying structure comprising a first opening, wherein the first patterning process comprises:
etching the underlying structure using the first patterned photoresist layer as a mask;
forming a second photoresist material on the first patterned underlying structure, wherein the second photoresist material fills the first opening;
patterning the second photoresist material using the first photomask as a mask to form a second patterned photoresist layer, wherein the second patterned photoresist layer fills the first opening;
forming a third photoresist material on the first patterned underlying structure and the second patterned photoresist layer;
patterning the third photoresist material using a second photomask as a mask to form a third patterned photoresist layer; and
performing a second patterning process on the first patterned underlying structure to form a second patterned underlying structure comprising the first opening and a second opening, wherein the second patterning process comprises:
etching the first patterned underlying structure using the third patterned photoresist layer as a mask.
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