SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME

摘要

A semiconductor device is disclosed in which proton implantation is performed a plurality of times to form a plurality of n-type buffer layers in an n-type drift layer at different depths from a rear surface of a substrate. The depth of the n-type buffer layer, which is provided at the deepest position from the rear surface of the substrate, from the rear surface of the substrate is more than 15 μm. The temperature of a heat treatment which is performed in order to change a proton into a donor and to recover a crystal defect after the proton implantation is equal to or higher than 400° C. In a carrier concentration distribution of the n-type buffer layer, a width from the peak position of carrier concentration to an anode is more than a width from the peak position to a cathode.

主权项

1. A semiconductor device comprising:
an n-type drift layer that is provided in an n-type semiconductor substrate; a p-type layer that is provided in a surface layer of a first main surface of the n-type semiconductor substrate so as to come into contact with the n-type drift layer; and an n-type layer that is provided in a second main surface of the n-type semiconductor substrate so as to come into contact with the n-type drift layer, wherein the n-type layer includes a plurality of n-type buffer layers which are formed by changing hydrogen introduced into the n-type semiconductor substrate into a donor and are provided at different depths from the second main surface of the n-type semiconductor substrate, the position of carrier peak concentration of the closest buffer layer which is arranged at a position closest to the p-type layer among the plurality of n-type buffer layers is deeper than 15 μm from the second main surface of the n-type semiconductor substrate, the carrier concentration of a region interposed between the n-type buffer layers which are adjacent to each other in a depth direction is less than the carrier peak concentration of the n-type buffer layer and is equal to or more than the carrier concentration of the n-type semiconductor substrate, in a carrier concentration distribution of the region interposed between the n-type buffer layers which are adjacent to each other in the depth direction, a distance between positions where the n-type buffer layers which are adjacent to each other in the depth direction have the peak carrier concentration is LAB, a region with a length aLAB in the range of the distance LAB is a region M, the value of a is in the range of 0.3 to 0.7, a value which is obtained by integrating the carrier concentration of the region M with the region M and dividing the integrated value by the distance LAB is the average carrier concentration of the region M, the region M includes a portion in which the carrier concentration is the minimum between the n-type buffer layers which are adjacent to each other in the depth direction, and a carrier concentration distribution of the region M includes a flat portion in which carrier concentration is in the range of 80% to 120% of the average carrier concentration.