Field effect transistor for reducing hot carrier damage and methods for forming the same

A method of forming a device structure comprising:

• forming doped wells including a source-side doped well and a drift-region well within a semiconductor material layer;
• forming shallow trenches within the semiconductor material layer overlying portions of the drift-region well;
• forming a distal doped layer stack within the drift-region well underneath one of the shallow trenches by sequentially implanting dopants of a second conductivity type at different implantation depths thereby creating a set of distal doped semiconductor layers having different average atomic concentrations of the dopants of the second conductivity type;
• depositing a dielectric material within the shallow trenches thereby forming a shallow trench isolation structure;
• forming a proximal doped layer stack within the drift-region well adjacent to the shallow trench isolation structure by implanting additional dopants of the second conductivity type;
• forming a gate dielectric layer and a gate electrode over a channel region within the drift-region well;
• and
• forming a source region and a drain region within the respective doped wells, thereby inducing a graded dopant transition beneath the shallow trench isolation structure through the distal doped layer stack that laterally offsets current paths from structural interfaces in a resultant field effect transistor configuration.

A method of forming a device structure comprising:

• providing a semiconductor-on-insulator substrate comprising a semiconductor material layer located over a buried insulating layer;
• forming a drift-region well and a source-side doped well within the semiconductor material layer;
• forming a shallow trench isolation structure within the semiconductor material layer overlying the drift-region well;
• forming a proximal doped layer stack and a distal doped layer stack within the drift-region well by implanting dopants of a second conductivity type to create variable atomic concentration profiles;
• forming a gate dielectric layer extending over a channel region and contacting the proximal doped layer stack;
• forming a gate electrode overlying the gate dielectric layer;
• and
• forming a source region and a drain region embedded within the respective doped wells, thereby inducing graded dopant transitions through the proximal doped layer stack and the distal doped layer stack on the buried insulating layer that laterally offset and downward deflect current paths from interfaces of the shallow trench isolation structure in a resultant field effect transistor configuration.