SILICON CARBIDE SEMICONDUCTOR DEVICE AND METHOD FOR PRODUCING THE SAME

摘要

An SiC semiconductor device has a p type region including a low concentration region and a high concentration region filled in a trench formed in a cell region. A p type column is provided by the low concentration region, and a p+ type deep layer is provided by the high concentration region. Thus, since a SJ structure can be made by the p type column and the n type column provided by the n type drift layer, an on-state resistance can be reduced. As a drain potential can be blocked by the p+ type deep layer, at turnoff, an electric field applied to the gate insulation film can be alleviated and thus breakage of the gate insulation film can be restricted. Therefore, the SiC semiconductor device can realize the reduction of the on-state resistance and the restriction of breakage of the gate insulation film.

主权项

1. A silicon carbide semiconductor device comprising:
a first or second conductivity type substrate made of silicon carbide; a drift layer disposed on the substrate, the drift layer made of a first conductivity type silicon carbide having an impurity concentration lower than that of the substrate; a base region disposed on the drift layer, the base region made of a second conductivity type silicon carbide; a source region disposed in an upper layer portion of the base region, the source region made of a first conductivity type silicon carbide having an impurity concentration higher than that of the drift layer; a trench gate structure disposed in a first trench that extends from a surface of the source region to a position deeper than the base region, the trench gate structure including a gate insulation film disposed on an inner wall surface of the first trench and a gate electrode disposed on the gate insulation film; a second conductivity type region disposed in a second trench that extends from the surface of the source region to the drift layer while passing through the base region and is deeper than the first trench, the second conductivity type region including a second conductivity type first low concentration region and a second conductivity type first high concentration region, the first low concentration region having a second conductivity type impurity concentration being set relatively low, the first high concentration region being disposed on a surface of the first low concentration region and having a second conductivity type impurity concentration being set higher than that of the first low concentration region, the first high concentration region being deeper than the first trench to provide a deep layer; a source electrode electrically connected to the base region through the source region and the second conductivity type region; and a drain electrode disposed on a rear surface of the substrate, wherein the silicon carbide semiconductor device is provided with a semiconductor switching element with an inversion type trench gate structure in which an inversion type channel region is formed on a surface portion of the base region located on a side surface of the first trench by controlling an application voltage to the gate electrode to cause an electric current between the source electrode and the drain electrode through the source region and the drift layer, and a super junction structure is provided by alternately arranged P and N columns that are provided by the first low concentration region and a portion of the drift layer opposing to the first low concentration region.