Forming an extremely thin semiconductor-on-insulator (ETSOI) layer

1. A method comprising

providing a wafer including a plurality of semiconductor-on-insulator (SOI) layer regions separated by at least one shallow trench isolation (STI);

selectively amorphizing the plurality of SOI layer regions and the STI,

wherein the selectively amorphizing includes implanting the plurality of SOI layer regions and the STI with an implant species, the implanting of the plurality of SOI layer regions performed at a higher energy level than the implanting of the STI,

wherein the selectively amorphizing causes the plurality of SOI layer regions to have a defect concentration approximately greater than 10 percent,

wherein a depth of the defect concentration is approximately 60 percent to approximately 70 percent of a thickness of the wafer; and

removing a portion of each of the selectively amorphized SOI layer regions to form at least one recess in the amorphized SOI layer.

2. The method of claim 1 , wherein the removing includes removing a portion of each of the selectively amorphized SOI layer regions between a plurality of STIs.

3. The method of claim 1 , wherein the removing includes chemical-mechanical polishing (CMP).

4. The method of claim 1 , further comprising annealing the SOI layer regions after the removing of the selectively amorphized portion of the SOI layer region.

5. The method of claim 4 , further comprising forming an oxide cap over the at least one recess after the annealing.

6. The method of claim 1 , wherein each of the selectively amorphized portion of the SOI layer regions have a defect concentration greater than approximately 10%.

7. The method of claim 1 , wherein the implant species is Xenon, and wherein the higher energy level is approximately 20-30 KeV.

8. The method of claim 1 , wherein the higher energy level is less than approximately 60 KeV, and wherein the implant species reaches a depth of the SOI wafer of approximately 400-600 Angstroms.