Patent ID: 11948976
Assignee: FUJI ELECTRIC CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A vertical metal oxide semiconductor field effect transistor (MOSFET) containing silicon carbide and having a pn junction interface through which a current passes in a forward direction, the vertical MOSFET comprising:
a starting substrate of a first conductivity type, having a first surface and a second surface opposite to each other;
a first first-conductivity-type epitaxial layer containing silicon carbide;
a second first-conductivity-type epitaxial layer containing silicon carbide, provided on the first surface of the starting substrate via the first first-conductivity-type epitaxial layer, the second first-conductivity-type epitaxial layer containing silicon carbide having an impurity concentration lower than an impurity concentration of the starting substrate and an impurity concentration of the first first-conductivity-type epitaxial layer, the second first-conductivity-type epitaxial layer further containing, as an impurity thereof, a first element that is a dopant of the first conductivity type;
a first semiconductor region of the first conductivity type, provided as a portion of the second first-conductivity-type epitaxial layer, in contact with the first first-conductivity-type epitaxial layer, the first semiconductor region having, as an impurity thereof, the first element and a second element, the second element forming recombination centers;
a second-conductivity-type epitaxial layer containing silicon carbide, the second-conductivity-type epitaxial layer forming the pn junction interface with the second first-conductivity-type epitaxial layer and supplying a minority carrier to the second first-conductivity-type epitaxial layer that includes the first semiconductor region;
a plurality of second semiconductor regions of the first conductivity type, selectively provided in the second-conductivity-type epitaxial layer;
a plurality of trenches that penetrate through the plurality of second semiconductor regions, respectively, and through the second-conductivity-type epitaxial layer, and reach the second first-conductivity-type epitaxial layer;
a plurality of gate electrodes that are provided in the plurality of trenches via a plurality of gate insulating films, respectively;
a first electrode electrically connected to the second semiconductor regions and the second-conductivity-type epitaxial layer; and
a second electrode electrically connected to the second surface of the starting substrate, wherein
a lifetime of the minority carrier of the first semiconductor region is shorter than a lifetime of the minority carrier of another portion of the second first-conductivity-type epitaxial layer excluding the first semiconductor region,
a concentration of the second element in the first semiconductor region is at most 1/10 of a concentration of the first element in the second first-conductivity-type epitaxial layer,
the first element is nitrogen,
the second element is vanadium, and
the concentration of the second element in the first semiconductor region is in a range from 5×1013/cm3 to 1×1015/cm3.