Patent ID: 6479876
Filing Date: 2002-11-12
Classification: H01L

Abstract:
Vertical power MOSFET having a semiconductor body with an inner zone (1) of the first conduction type and a predetermined doping concentration in which in operation is formed a space charge zone, at least one base zone (3), adjoining the inner zone (1) and a first surface of the semiconductor body, of the second conduction type and into which in each case at least one source zone (4) is embedded, at least one drain zone (7), adjoining one of the surfaces of the semiconductor body, and with at least one additional zone (11) of the second conduction type arranged in the inner zone (1) essentially inside the space charge zone which spreads out when there is a reverse voltage, and at least one additional zone (12) of the first conduction type, which is laterally surrounded by said at least one additional zone of the second conduction type, is more highly doped than the inner zone (1), and has a doping level for the additional zones (11, 12) and distances between the additional zones of the second conduction type such that their charge carriers are substantially depleted when a reverse voltage is applied, characterized in that the charge carrier lifetime in the at least one additional zone (12) of the first conduction type has been reduced by at least one of a lifetime reducing impurity or irradiation and the thickness dimensions and doping of the additional zones (11, 12) are such that the space charge zone that spreads out when any operating reverse voltage less than that necessary to cause avalanche breakdown is applied, does not reach the drain zone (7) but leaves the majority of the inner zone (1) located between the bottom of the additional zones (11, 12) and the drain zone (7) free of the space charge zone.