In the reverse-conducting IGBT according to the present invention, an n-type buffer layer surrounds a p-type collector layer. A p-type separation layer surrounds an n-type cathode layer. The n-type buffer layer separates the p-type collector layer and the p-type separation layer from each other. The p-type separation layer separates the n-type cathode layer and the n-type buffer layer from each other. Therefore, the present invention makes it possible to reduce snapback.

A p-type anode layer (2) is provided on an upper surface of an n-type drift layer (1). An n-type cathode layer (3) is provided on a lower surface of the n.sup.-type drift layer (1). An n-type buffer layer (4) is provided between the n.sup.-type drift layer (1) and the n-type cathode layer (3). A peak impurity concentration in the n-type buffer layer (4) is higher than that in the n.sup.-type drift layer (1) and lower than that in the n-type cathode layer (3). A gradient of carrier concentration at a connection between the n.sup.-type drift layer (1) and the n-type buffer layer (4) is 20 to 2000 cm.sup.4.

A semiconductor device includes MOSFET cells having a drift region of a first conductivity type. A first and second active area trench are in the drift region. A split gate uses the active trenches as field plates or includes planar gates between the active trenches including a MOS gate electrode (MOS gate) and a diode gate electrode (diode gate). A body region of the second conductivity type in the drift region abutts the active trenches. A source of the first conductivity type in the body region includes a first source portion proximate to the MOS gate and a second source portion proximate to the diode gate. A vertical drift region uses the drift region below the body region to provide a drain. A connector shorts the diode gate to the second source portion to provide an integrated channel diode. The MOS gate is electrically isolated from the first source portion.

A silicon carbide semiconductor device includes an electric field relaxation layer disposed in a drift layer. The electric field relaxation layer includes a first region having a second conductivity type and disposed at a position deeper than trenches, and a second region having the second conductivity type and disposed between the adjacent trenches to be away from a side surface of each of the adjacent trenches. Each of the first region and the second region is made of an ion implantation layer. The electric field relaxation layer further includes a double implantation region in which the first region and the second region overlap with each other, and the electric field relaxation layer has a peak of a second conductivity type impurity concentration in the double implantation region.

A semiconductor device includes a semiconductor substrate with: a drift layer; a base layer; and a collector layer and a cathode layer. In the semiconductor substrate, when a region operating as an IGBT device is an IGBT region and a region operating as a diode device is a diode region, the IGBT and diode regions are arranged alternately in a repetitive manner; a damaged region is arranged on a surface portion of the diode region in the semiconductor substrate. The IGBT and diode regions are demarcated by a boundary between the collector and cathode layers; and a surface portion of the IGBT region includes: a portion having the damaged region at a boundary side with the diode region; and another portion without the damaged region arranged closer to an inner periphery side relative to the boundary side.

A device includes a semiconductor substrate, a doped isolation barrier disposed in the semiconductor substrate and defining a core device area within the doped isolation barrier, an isolation contact region disposed in the semiconductor substrate outside of the core device area and to which a voltage is applied during operation, and a depleted well region disposed in the semiconductor substrate outside of the core device area. The depleted well region electrically couples the isolation contact region and the doped isolation barrier such that the doped isolation barrier is biased at a voltage level lower than the voltage applied to the isolation contact region.

A semiconductor device includes a substrate having a first conductivity type, a high-voltage well having a second conductivity type and disposed in the substrate, a high-voltage doped region having the first conductivity type and disposed in the high-voltage well, a drain region disposed in the high-voltage well and spaced apart from the high-voltage doped region, a source region disposed in the high-voltage doped region, a first gate structure disposed above a first side portion of the high-voltage doped region between the source region and the drain region, and a second gate structure disposed above a second and opposite side portion of the high-voltage doped region.

A semiconductor device including a semiconductor substrate; a trench formed in a front surface of the semiconductor substrate; a gate conducting portion formed within the gate trench; and a first region formed adjacent to the trench in the front surface of the semiconductor substrate and having a higher impurity concentration than the semiconductor substrate. A shoulder portion is provided on a side wall of the gate trench between the top end of the gate conducting portion and the front surface of the semiconductor substrate and has an average slope, relative to a depth direction of the semiconductor substrate, that is greater than a slope of the side wall of the gate trench at a position opposite the top end of the gate conducting portion, and a portion of the first region that contacts the gate trench is formed as a deepest portion thereof.

Embodiments of a device are provided, including a semiconductor substrate including an active device area; a body region disposed in the semiconductor substrate within the active device area, wherein a channel is formed within the body region during operation; a doped isolation layer disposed in the semiconductor substrate underneath the active device area, the doped isolation layer including an opening positioned under the active device area; and a lightly-doped isolation layer disposed in the semiconductor substrate underneath the active device area, the lightly-doped isolation layer positioned at least within the opening and in electrical contact with the doped isolation layer, wherein the doped isolation layer and the lightly-doped isolation layer form a doped isolation barrier that extends across an entire lateral extent of the active device area.

A semiconductor device includes a semiconductor layer having a first surface and a second surface, a first electrode on the first surface, a second electrode on the second surface, a first semiconductor region of a first conductivity type in the semiconductor layer, a second semiconductor region of a second conductivity type in an element region of the semiconductor layer between the first semiconductor region and the first electrode, a third semiconductor region of the second conductivity type between the second semiconductor region and the first electrode, and a fourth semiconductor region of the second conductivity type in a termination region of the semiconductor layer inwardly of the first surface. A distance between the fourth semiconductor region and the second surface is greater than a distance between the second semiconductor region and the second surface.