Abstract: A semiconductor device includes an n-type base substrate; a p-type first region; a p-type surface region having a plurality of second corner portions and a plurality of second side portions surrounding the first region. The p-type surface region has a dopant concentration lower than a dopant concentration of the first region. The semiconductor device further includes a field plate in a region overlapping with the surface region in a plan view by way of an insulation film. The field plate has a plurality of field plate corner portions and a plurality of field plate side portions. A relationship of L1>L2 is established at least at a portion of the surface region or a relationship of FP1>FP2 is established at least at a portion of the field plate is satisfied. A withstand voltage of the second side portion is lower than a withstand voltage of the second corner portion.

Abstract: A semiconductor device includes an n-type base substrate; a p-type first region; a p-type surface region having a plurality of second corner portions and a plurality of second side portions surrounding the first region. The p-type surface region has a dopant concentration lower than a dopant concentration of the first region. The semiconductor device further includes a field plate in a region overlapping with the surface region in a plan view by way of an insulation film. The field plate has a plurality of field plate corner portions and a plurality of field plate side portions. A relationship of L1>L2 is established at least at a portion of the surface region or a relationship of FP1>FP2 is established at least at a portion of the field plate is satisfied. A withstand voltage of the second side portion is lower than a withstand voltage of the second corner portion.

Abstract: A semiconductor device includes a semiconductor base body having an n+-type semiconductor layer and an n?-type semiconductor layer p+-type diffusion regions selectively formed on a surface of the n?-type semiconductor layer, and a barrier metal layer formed on a surface of the n?-type semiconductor layer and surfaces of p+-type diffusion regions. A Schottky junction is between the barrier metal layer and the n?-type semiconductor layer. An ohmic junction is between the barrier metal layer and the p+-type diffusion regions. Platinum is diffused into the semiconductor base body such that a concentration of platinum becomes maximum in a surface of the n?-type semiconductor layer.

Abstract: A semiconductor device includes a semiconductor base body having an n+-type semiconductor layer and an n?-type semiconductor layer p+-type diffusion regions selectively formed on a surface of the n?-type semiconductor layer, and a barrier metal layer formed on a surface of the n?-type semiconductor layer and surfaces of p+-type diffusion regions. A Schottky junction is between the barrier metal layer and the n?-type semiconductor layer. An ohmic junction is between the barrier metal layer and the p+-type diffusion regions. Platinum is diffused into the semiconductor base body such that a concentration of platinum becomes maximum in a surface of the n?-type semiconductor layer.

Abstract: A method of producing a tube which has a tube body portion constituting an outer hull of flow passages, and flow passage dividers for dividing the flow passages, comprising a roll forming process to form the tube, a cutting process to cut the tube to a predetermined length after the roll forming process, and a brazing process to braze the tube contact portions of the flow passage dividers to the inner surface of the tube body portion after the cutting process. The cutting process forms a slit in the tube, and so as to concentrate a stress on the slit, thereby to cut the tube starting from the slit. The slit is formed in only the tube body portion between the tube body portion and the flow passage dividers or formed ranging from the tube body portion to the tube contact portions of the flow passage dividers.