Patent ID: 9385022
Filing Date: 2016-07-05
CPC Classification: G02B,H01L

Claim Text:
1. A method comprising: forming an optical waveguide in a bulk silicon layer, the optical waveguide including a set of shallow trench isolation (STI) regions overlying a silicon substrate region; ion implanting the silicon substrate to amorphize a portion of the silicon substrate; forming a set of trenches through the STI regions and into the underlying silicon substrate region, wherein the forming of the set of STI regions includes forming a waveguide structure including the STI regions, the waveguide structure having a first portion extending to a first depth in the bulk silicon layer, and a second portion extending to a second depth in the bulk silicon layer, the second depth being greater than the first depth; undercut etching the silicon substrate region under the STI regions through the set of trenches to form a set of cavities, wherein the amorphized portion of the silicon substrate etches at a rate less than an etch rate of the silicon substrate, wherein the amorphized portion underlies the waveguide structure; and sealing the set of cavities.