Soi transistors with improved source/drain structures with enhanced strain

A semiconductor device including an SOI (silicon on insulator) transistor device, said semiconductor device comprising:

• a substructure including a silicon substrate, a buried oxide layer disposed on said silicon substrate and a crystalline silicon material disposed on said buried oxide layer;
• a gate structure formed over said crystalline silicon material, said gate structure including a gate electrode and source/drain spacers along sidewalls of said gate electrode;
• source/drain structures disposed adjacent opposite sides of said gate electrode, said source/drain structures formed of a strain material filling an opening that extends through said crystalline silicon material and said buried oxide layer and into said silicon substrate, including beneath said source/drain spacers, said source/drain structures each having an upper portion disposed above an upper surface of said crystalline silicon material;
• and
• dopant impurity regions in said semiconductor substrate beneath each said source/drain structure.

A method for forming a transistor on a silicon-on-insulator (SOI) substructure, said method comprising:

• providing a semiconductor substrate;
• forming an oxide layer over said semiconductor substrate;
• forming a crystalline silicon material over said oxide layer;
• forming a gate structure over said crystalline silicon material;
• creating openings extending through said oxide layer and said crystalline silicon material and extending into said semiconductor substrate, adjacent said gate structure;
• and
• filling said openings with a strain material, said strain material including a top surface above an upper surface of said crystalline silicon material.