| CPC H10D 30/668 (2025.01) [H10D 62/393 (2025.01); H10D 62/8325 (2025.01); H10D 64/513 (2025.01)] | 3 Claims |
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1. A switching element, comprising:
a semiconductor substrate that has an upper surface on which a trench is disposed;
a gate insulating film that covers an inner surface of the trench; and
a gate electrode that is disposed inside the trench, the gate electrode being insulated from the semiconductor substrate by the gate insulating film,
wherein
the semiconductor substrate further includes:
an n-type source region in contact with the gate insulating film on a side of the trench;
a p-type body region in contact with the gate insulating film on the side below the source region;
an n-type drift region that is arranged below the body region, the n-type drift region being in contact with the gate insulating film on the side below the body region and with the gate insulating film at a bottom surface of the trench;
a p-type first electric field reduced region that is arranged inside the drift region below the trench to be spaced away from the bottom surface of the trench, the p-type first electric field reduced region extending along the bottom surface of the trench; and
a p-type connection region that protrudes downward from the body region to reach the first electric field reduced region, the p-type connection region extending in a direction intersecting the trench when viewed in a plan view,
a permittivity of the connection region is ε(F/cm), a critical electric field strength of the connection region is Ec (V/cm), an elementary charge is e (C), and an area density of p-type impurity when viewed in a plan view of the connection region located below the trench is Q (cm−2),
Q>ε*Ec/e,
a p-type impurity concentration in the connection region is higher than a p-type impurity concentration in the first electric field reduced region,
the switching element further comprises a source electrode disposed on the upper surface of the semiconductor substrate,
the body region further includes:
a contact region in ohmic contact with the source electrode; and
a main body region having lower p-type impurity concentration than the contact region, the main body region being in contact with the source region and the contact region from a lower side and in contact with the gate insulating film below the source region,
the connection region protrudes downward from the main body region, and
the connection region has higher p-type impurity concentration than the p-type impurity concentration of the main body region.
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