Patent ID: 8624355

Claim:
A semiconductor device comprising: a substrate; an n-type buried layer provided on the substrate; an n-type base layer provided on the buried layer and having an n-type impurity concentration lower than an n-type impurity concentration of the buried layer; a p-type emitter layer provided in a surface of the base layer; a p-type collector layer provided in the surface of the base layer and spaced from the emitter layer; an n-type first guard ring layer provided between the emitter layer and the collector layer on a surface side of the base layer, spaced from the emitter layer and the collector layer, and having an n-type impurity concentration higher than an n-type impurity concentration of the base layer; and an n-type second guard ring layer provided between the first guard ring layer and the buried layer, connected to the first guard ring layer and the buried layer, and having an n-type impurity concentration higher than the n-type impurity concentration of the base layer, the first guard ring layer having an n-type impurity concentration profile decreasing toward the second guard ring layer side, and the second guard ring layer having an impurity concentration profile decreasing toward the first guard ring layer side.