Patent ID: 8394705

Claim:
A method of manufacturing a semiconductor device, comprising: providing a semiconductor substrate having a first region where a first optical device is to be formed and a second region where a waveguide is to be formed; forming a first buried oxide layer in the semiconductor substrate in the first region so that the semiconductor substrate in the first region is divided into a lower semiconductor layer and an upper semiconductor layer, while not forming the first buried oxide layer in the semiconductor substrate in the second region; defining an active portion by forming a trench in the semiconductor substrate in the second region; forming a capping semiconductor pattern over a top surface of the active portion and over a sidewall of the active portion; exposing a lower portion of the sidewall of the active portion; oxidizing the capping semiconductor pattern and the lower portion of the sidewall of the active portion to form an oxide layer surrounding a non-oxidized portion of the active portion; and forming a first optical device disposed in the upper semiconductor layer of the first region, wherein the non-oxidized portion of the active portion is configured to be a core of the waveguide through which optical signals pass, wherein the core is coupled to the first optical device, and wherein the forming of the capping semiconductor pattern comprises: forming a sacrificing pattern filling the trench; exposing an upper portion of the sidewall of the active portion by recessing the sacrificing pattern; conformally forming a capping semiconductor layer over the semiconductor substrate; removing the capping semiconductor layer over the recessed sacrificing pattern to expose the recessed sacrificing pattern and to form the capping semiconductor pattern; and removing the exposed sacrificing pattern to expose the lower portion of the sidewall of the active portion, wherein the capping semiconductor pattern extends to cover a top surface of the upper semiconductor layer in the first region, and wherein a portion of the capping semiconductor pattern over the upper semiconductor layer is oxidized by an oxidizing process, so that the oxide layer is formed over the upper semiconductor layer.