Selective Implantation into STI of ETSOI Device

A method of forming a plurality of isolation regions in a silicon-on-insulator (SOI) device, the method comprising:

• providing a device stack comprising a buried oxide (BOX) layer in a substrate;
• patterning a hardmask over the substrate;
• forming the plurality of isolation regions in the device stack, wherein the plurality of isolation regions extend through the box layer and the substrate;
• forming a well mask over the device stack, wherein an opening through the well mask exposes a first set of isolation regions of the plurality of isolation regions;
• and
• modifying a stress of a material of the first set of isolation region by implanting ions into the first isolation region of the plurality of isolation regions, wherein a second set of isolation regions of the plurality of isolation regions is not impacted by the implanted ions.

A method of forming an extra thin silicon-on-insulator (ETSOI) device, the method comprising:

• providing a device stack comprising a buried oxide (BOX) layer in a silicon substrate;
• patterning a hardmask over the silicon substrate;
• forming a plurality of isolation regions in the device stack, wherein the plurality of isolation regions extend through the box layer and the silicon substrate;
• forming a well mask over the device stack, wherein an opening through the well mask exposes a first isolation region of the plurality of isolation regions;
• and
• modifying a stress of a material of the first isolation region by implanting the first isolation region of the plurality of isolation regions.