Method and structure of forming strained channels for CMOS device fabrication

A method for manufacturing a semiconductor device, comprising:

• growing a first strained semiconductor layer on a substrate, the first strained semiconductor layer having a first type of strain;
• wherein the substrate comprises a first crystalline orientation at a top surface of the substrate;
• forming at least one trench in the substrate, wherein exposed sidewalls of the at least one trench have a second crystalline orientation different from the first crystalline orientation;
• growing a buffer layer in the at least one trench from the exposed sidewalls of the at least one trench;
• and
• growing a second strained semiconductor layer on the buffer layer, the second strained semiconductor layer having a second type of strain;
• wherein the first type of strain is different from the second type of strain;
• wherein a surface of the buffer layer parallel to the top surface of the substrate is substantially free of strain;
• and
• wherein the surface of the buffer layer parallel to the top surface of the substrate has a strain level less than 0.3%.

A method for manufacturing a semiconductor device, comprising:

• growing a first strained semiconductor layer on a substrate, the first strained semiconductor layer having a first type of strain;
• wherein the substrate comprises a first crystalline orientation at a top surface of the substrate;
• forming at least one trench in the substrate, wherein exposed sidewalls of the at least one trench have a second crystalline orientation different from the first crystalline orientation;
• growing a buffer layer in the at least one trench from the exposed sidewalls of the at least one trench;
• growing a second strained semiconductor layer on the buffer layer, the second strained semiconductor layer having a second type of strain;
• removing, prior to forming the at least one trench, a portion of the first strained semiconductor layer from an area of the substrate corresponding to where the at least one trench is to be formed;
• and
• forming a hardmask on the first strained semiconductor layer, wherein the hardmask leaves exposed the portion of the first strained semiconductor layer corresponding to where the at least one trench is to be formed;
• wherein the first type of strain is different from the second type of strain;
• and
• wherein growing the buffer layer in the at least one trench comprises overgrowing the buffer layer to a height above a top surface of the hardmask.

A method for manufacturing a semiconductor device, comprising:

• growing a first strained semiconductor layer on a substrate, the first strained semiconductor layer having a first type of strain;
• wherein the substrate comprises a first crystalline orientation at a top surface of the substrate;
• forming at least one trench in the substrate, wherein exposed sidewalls of the at least one trench have a second crystalline orientation different from the first crystalline orientation;
• growing a buffer layer in the at least one trench from the exposed sidewalls of the at least one trench;
• growing a second strained semiconductor layer on the buffer layer, the second strained semiconductor layer having a second type of strain;
• and
• forming, prior to growing the first strained semiconductor layer, a hardmask on the substrate, wherein the hardmask leaves exposed an area of the substrate corresponding to where the at least one trench is to be formed;
• wherein the first type of strain is different from the second type of strain.