Deep STI trench and SOI undercut enabling STI oxide stressor

A method for imparting stress to the channel region of an SOI transistor, comprising:

• providing a semiconductor stack containing a buried oxide layer, an SOI layer, and a hard mask;
• creating a first trench which extends through the hard mask and the SOI layer and which exposes a portion of the oxide layer;
• removing a portion of the oxide layer with an etch that undercuts the SOI layer, thereby forming a second trench;
• and
• backfilling the second trench with a stressor material, thereby forming a trench isolation structure.

A semiconductor device, comprising:

• a semiconductor layer having an insulating layer disposed underneath it;
• a channel region defined in said semiconductor layer;
• and
• a trench isolation structure which is adjacent to said channel region and which extends through said first semiconductor layer and into said insulating layer;
• wherein said trench isolation structure imparts stress to said channel region wherein said trench isolation structure undercuts the semiconductor layer.

A method for imparting stress to the channel region of a semiconductor device, comprising:

• providing a semiconductor layer disposed on an insulating layer;
• creating a trench which extends through the semiconductor layer and into the insulating layer, wherein the trench is formed by (a) using a first etch to create an opening which extends through the semiconductor layer and which exposes a portion of the insulating layer, and (b) using a second etch to remove a portion of the insulating layer;
• backfilling the trench with a stressor material;
• and
• creating a channel region adjacent to the backfilled trench.

A method for imparting stress to the channel region of a semiconductor device, comprising:

• providing a semiconductor layer disposed on an insulating layer;
• creating a trench which extends through the semiconductor layer and into the insulating layer;
• backfilling the trench with a tensile stressor material;
• and
• creating a channel region adjacent to the backfilled trench.

A method for imparting stress to the channel region of a semiconductor device, comprising:

• providing a semiconductor layer disposed on an insulating layer;
• creating a trench which extends through the semiconductor layer and into the insulating layer;
• backfilling the trench with a stressor material;
• and
• creating a channel region adjacent to the backfilled trench;
• wherein the semiconductor layer has a hard mask disposed thereon, wherein the trench extends through the hard mask, and wherein the hard mask comprises a layer of pad oxide having a layer of silicon nitride disposed thereon.