Fabrication of strained heterojunction structures

A method of forming a strained crystalline silicon layer on which devices may be formed comprising:

• (a) growing a layer of silicon-germanium alloy on a side of a silicon template layer of a silicon-on-insulator substrate to form a multilayer structure, the silicon-on-insulator substrate including the silicon template layer supported on its other side on a sacrificial layer of silicon dioxide formed over a silicon handle layer, such that the silicon-germanium alloy layer is in compressive strain as it is grown;
• (b) patterning and etching material adjacent to a side of the sacrificial layer to expose areas of the sacrificial layer;
• and
• (c) preferentially etching the silicon dioxide sacrificial layer to release the multilayer structure such that strain in the silicon-germanium layer is relaxed and the silicon template layer is strained as the silicon-germanium layer relaxes.

A strained multilayer semiconductor structure comprising:

• (a) a bottom layer of tensilely strained crystalline silicon;
• (b) a layer of partially compressive-strain relaxed silicon-germanium alloy on the bottom silicon layer;
• and
• (c) a top layer of tensilely strained crystalline silicon on the silicon-germanium layer.

A strained multilayer semiconductor structure comprising:

• (a) a bottom layer of tensilely strained crystalline silicon;
• (b) a first layer of partially compressive strain relaxed silicon-germanium alloy on the bottom silicon layer;
• (c) a second layer of tensilely strained crystalline silicon on the first silicon-germanium layer;
• (d) a second layer of partially compressive strain relaxed silicon-germanium alloy on the second layer of tensilely strained silicon, wherein the Ge content in the second silicon-germanium alloy layer is the same as or higher than that in the first silicon-germanium alloy layer;
• and
• (e) a layer of tensilely strained crystalline silicon on the second silicon-germanium alloy layer.

A method of forming a strained crystalline layer on which devices may be formed comprising:

• (a) growing a first layer of material epitaxially on a side of a crystalline template layer to a thickness below an effective critical thickness at which the grown layer will start to relax plastically and generate dislocations, the template layer supported on its other side by a sacrificial layer of a substrate having a handle layer, the first grown layer and the template layer having a lattice mismatch so that the grown layer is compressively strained as it is grown;
• (b) growing a top layer of material epitaxially over the first grown layer to a thickness below an effective thickness at which the top layer will start to relax plastically and generate dislocations, the first and top layers forming a multilayer structure with the template layer;
• (c) patterning and etching material adjacent to a side of the sacrificial layer to expose areas of the sacrificial layer;
• and
• (d) preferentially etching the sacrificial layer at the exposed areas of the sacrificial layer to release the multilayer structure such that the strain in the first grown layer is relaxed and the crystalline template layer and top layer are strained as the first grown layer relaxes.