A re-examination of the physics of multiplication-induced breakdown in MOSFETs

It is shown that the physics of multiplication-induced breakdown (MIB) is essentially different from what has previously been thought. Two phases, multiplication-enhanced channel injection (MECI) and multiplication-induced bulk injection (MIBI) of the increased source injection, are distinguished. They are both shown to be impossible to treat conventionally. It is found that MECI can be accounted for in terms of a certain multiplication equivalent threshold lowering (METL). The latter, however, cannot be replaced by the body effect resulting from the external positive bulk bias equal to the internal self-biasing V/sub sub/=R/sub sub/I/sub sub/, as might seem desirable at first sight. In addition, although MIBI can be treated in terms of a parasitic bipolar transistor action, the mode of biasing of the latter, contrary to what other approaches postulate, has little to do with V/sub sub/. This is because of the substrate current I/sub sub/ which implies that the Fermi level follows the increasing (from the bulk terminal to the surface) potential. As a result, the source injection is considerably weaker than in conventional diode and can be associated with an effective junction bias which is much smaller than V/sub sub/.<>