Dependence of the effective p+ buried layer implant dose for reducing junction leakage on well-to-buried layer spacing

We investigated the dependence of the effective p⁺ buried layer implant dose for reducing junction leakage current on well-to-buried layer spacing. P⁺-n junction leakage current characteristics as function of the projected range difference between the p⁺ buried layer and well show that minimum well-to-buried layer spacing for suppressing leakage current should be wider than 2 μm. Moreover, it is found that a wider well-to-buried layer spacing gives a lower buried layer dose available for suppressing junction leakage current. The junction leakage current characteristics with various well-to-buried layer spacings in conjunction with implanted doses of buried layer are closely related to the density of threading dislocations and their spatial extents from the buried layer. Taking these results and throughput issues due to low beam current performance at high energy range into account, the well depth should be decreased within the limit of acceptable transistor characteristics