High voltage implanted RESURF p-LDMOS using BiCMOS technology

The authors present a complementary RESURF p-LDMOS in which the n/sup +/ buried layer is used as an effective substrate and a field implant is introduced to modify the drift charges. The implant conditions in this case, particularly the placements, are studied. After processing, V/sub B/ are investigated with different implant placement (L/sub A/, L/sub B/) and field oxide lengths L/sub F/. It is found that although the ion implant covers part of the drift region, the device performance can still be greatly improved. Results show that a long enough implant, compatible with L/sub F/, under the field oxide can result in the maximum, V/sub B/=V/sub BP/. This is verified by simulation results, which show that the peak of the surface electric field is significantly reduced. Results also show that a full length (L/sub F/) implantation under the field oxide can result in the minimum R/sub on/ for a fixed L/sub F/.