Denso Corporation

Koichi Murakawa

Shigeki Takahashi

Masakiyo Sumitomo

In a semiconductor device in which an IGBT region having an IGBT element and an FWD region having an FWD element are formed to a semiconductor substrate, a plurality of carrier injection layers electrically connected with a second electrode and configuring a PN junction with a field stop layer is disposed in a cathode layer. When an impurity concentration of the field stop layer is defined as Nfs [cm], and a length of a shortest portion of each of the plurality of carrier injection layers along a planar direction of the semiconductor substrate is defined as L[&#x3bc;m], the plurality of carrier injection layers satisfies a relationship of L&#x3e;6.8&#xd7;10&#xd7;Nfs+20.

Semiconductor device including carrier injection layers

In a semiconductor device, a boundary area is between an IGBT region and a diode region. In other words, the boundary region is at a position adjacent to the diode region. The boundary region has a lower ratio of formation of a high-concentration P-type layer than the IGBT region. Accordingly, during recovery, hole injection from the IGBT region to the diode region can be inhibited. The reduced ratio of formation of the high-concentration P-type layer in the boundary region also reduces the amount of hole injection from the high-concentration P-type layer of the boundary region. Thus, it inhibits an increase in maximum reverse current during the recovery, and also decreases the carrier density on the cathode side to inhibit an increase in tail electrical current, so that the semiconductor device reduces switching loss and is highly resistant to recovery destruction.

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Kariya, Japan

Koichi Murakawa