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US 7,247,247 B2Granted
Selective etching method
AssigneeWalsin Lihwa Corporation
InventorsJerwei Hsieh, Huai-Yuan Chu, Julius Ming-Lin Tsai, Weileun Fang
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Abstract
A selective etching method with lateral protection function is provided. The steps includes: (a) providing a substrate; (b) forming a plurality of tunnels; (c) forming a lateral strengthening structure at a peripheral wall of the tunnels; (d) removing a bottom portion of the lateral strengthening structure, and a part of the substrate by an etching process so as to form a lower structure and expose an unstrengthened structure; and (f) etching the unstrengthened structure laterally so as to form an upper structure.
Claims18
A selective etching method, comprising steps of:
- (a) providing a substrate;
- (b) forming a first mask layer having plural openings on said substrate;
- (c) forming a second mask layer on said first mask layer and forming said second mask layer in at least one of said openings for covering at least one part of said substrate;
- (d) forming a photoresist layer on said second mask layer and said part of said substrate so as to form plural etching windows directly on said substrate;
- (e) etching downwards said substrate through said plural etching windows by a first etching process so as to extend said plural etching windows downwards into said substrate;
- (f) removing said photoresist layer and etching said substrate through said plural openings by a second etching process so as to form plural tunnels with different depths;
- (g) forming a lateral strengthening structure at a peripheral wall of said plural tunnels with different depths;
- (h) removing said second mask layer, a portion of said lateral strengthening structure below said second mask layer, and a part of said substrate by a third etching process so as to form a lower structure and expose an unstrengthened structure;
- (i) etching said unstrengthened structure laterally so as to form an upper structure.
6 more elements
Dependencies are inferred from the claim text.