Integrated Circuit Having Back Gating, Improved Isolation And Reduced Well Resistance And Method To Fabricate Same
A structure includes a silicon substrate; at least two wells in the silicon substrate; and a deep trench isolation (DTI) separating the two wells. The DTI has a top portion and a bottom portion having a width that is larger than a width of the top portion. The structure further includes at least two semiconductor devices disposed over one of the wells, where the at least two semiconductor devices are separated by a shallow trench isolation (STI). In the structure sidewalls of the top portion of the DTI and sidewalls of the STI are comprised of doped, re-crystallized silicon. The doped, re-crystallized silicon can be formed by an angled ion implant that uses, for example, one of Xe, In, BF 2 , B 18 H 22 , C 16 H 10 , Si, Ge or As as an implant species to amorphize the silicon, and by annealing the amorphized silicon to re-crystallize the amorphized silicon.
1 . A structure comprising:
a silicon substrate;
at least two wells in the silicon substrate;
a deep trench isolation (DTI) separating said two wells, the DTI having a top portion and a bottom portion having a width that is larger than a width of the top portion; and
at least two semiconductor devices disposed over one of the wells, the at least two semiconductor devices being separated by a shallow trench isolation (STI);
where sidewalls of the top portion of the DTI and sidewalls of the STI are comprised of doped, re-crystallized silicon.
2 . The structure of claim 1 , where the silicon substrate is disposed beneath a buried oxide layer that in turn is disposed beneath a semiconductor layer.
3 . The structure of claim 1 , where the silicon substrate is a bulk silicon substrate.
4 . The structure of claim 1 , where one of the wells is an N-type well and one of the wells is a P-type well.
5 . The structure of claim 1 , where the doped, re-crystallized silicon is formed by an angled ion implant that uses one of Xe, In, BF 2 , B 18 H 22 , C 16 H 10 , Si, Ge or As as an implant species to amorphize the silicon, and by annealing the amorphized silicon to re-crystallize the amorphized silicon.
6 . The structure of claim 5 , where the angled ion implant uses Xe as an implant species and is performed with about a 10 KeV implant energy and about a 3×10 14 atoms/cm 2 dose.
7 . The structure of claim 1 , where the bottom portion of the DTI contains a void within insulator material that fills the bottom portion.