Method of producing a thin silicon-on-insulator layer

A method of forming a thin semiconductor layer substantially free of defects upon which semiconductor structures can be subsequently formed, comprising the steps of:

• a) forming a silicon diffusion layer upon a first wafer, the first wafer comprising a silicon substrate of a first conductivity type and the diffusion layer being of a second conductivity type and characterized by a first etch characteristic;
• b) forming a first thin epitaxial layer upon said diffusion layer, said first thin epitaxial layer being of the second conductivity type and characterized by a second etch characteristic different from the first etch characteristic of said diffusion layer;
• c) doping said first thin epitaxial layer in predetermined regions to form diffusion regions therein, said diffusion regions being of the second conductivity type and characterized by the first etch characteristic;
• d) forming a second thin epitaxial layer upon said first thin epitaxial layer, said second thin epitaxial layer being of the second conductivity type and characterized by the second etch characteristic;
• e) forming a thin oxide layer upon said second thin epitaxial layer;
• f) providing a second wafer comprising a silicon substrate having a thin oxide layer formed on a surface thereof;
• g) wafer bonding said first wafer to said second wafer;
• h) removing the silicon substrate of said first wafer in a controlled mechanical manner;
• and
• i) removing said diffusion layer and said diffusion regions of said first wafer using a selective low energy dry plasma process to expose areas of the underlying first and second thin epitaxial layers in contact with said diffusion layer and said diffusion regions, respectively, the selective dry plasma process providing an etch ratio of the first etch characteristic to the second etch characteristic such that said diffusion layer and diffusion regions are removed with minimal formation of any shallow plasma radiation damage to the exposed areas of the underlying first and second thin epitaxial layers, respectively.

A method of forming a thin semiconductor layer substantially free of defects upon which semiconductor structures can be subsequently formed, comprising the steps of:

• a) forming a silicon diffusion layer upon a first wafer, the first wafer comprising a silicon substrate of a first conductivity type and the diffusion layer being of a second conductivity type and characterized by a first etch characteristic;
• b) forming an epitaxial layer upon said diffusion layer, said epitaxial layer being of the second conductivity type and characterized by a second etch characteristic different from the first etch characteristic of said diffusion layer;
• c) forming trenches in said epitaxial layer at predetermined regions therein;
• d) filling said trenches with a trench fill;
• e) planarizing a top surface of said epitaxial layer and said filled trenches;
• f) forming a thin oxide layer upon said planarized epitaxial layer and filled trenches;
• g) providing a second wafer comprising a silicon substrate having a thin oxide layer formed on a surface thereof;
• h) wafer bonding said first wafer to said second wafer;
• i) removing the silicon substrate of said first wafer in a controlled mechanical manner;
• and
• j) removing said diffusion layer of said first wafer using a selective dry low energy plasma process to expose the underlying epitaxial layer, the selective dry plasma process providing an etch ratio of the first etch characteristic to the second etch characteristic such that said diffusion layer is removed with minimal formation of any shallow plasma radiation damage to the exposed underlying epitaxial layer.