Semiconductor device and method for manufacturing semiconductor device
AssigneeMitsubishi Electric Corporation
InventorHiroshi WATANABE
Life of this patent
Estimating the term…
Abstract
The present techniques relate to a semiconductor device having resistance which has a positive temperature coefficient and a suitable value, and to a method for manufacturing a semiconductor device having resistance which has a positive temperature coefficient and a suitable value. The semiconductor device related to the present techniques is a bipolar device in which a current flows through a pn junction. The semiconductor device includes an n-type silicon carbide drift layer, a p-type first silicon carbide layer formed on the silicon carbide drift layer, and a p-type second silicon carbide layer formed on the first silicon carbide layer. Then, the second silicon carbide layer has a positive temperature coefficient of resistance.
Claims7
1-11. (canceled)
A semiconductor device which is a bipolar device in which a current flows through a pn junction, comprising:
- a silicon carbide drift layer of a first conductivity type;
- a first silicon carbide layer of a second conductivity type which is formed on said silicon carbide drift layer;
- a second silicon carbide layer of the second conductivity type which is formed on said first silicon carbide layer;
- and
- a third silicon carbide layer of the second conductivity type which is formed on said second silicon carbide layer, wherein
- said second silicon carbide layer has a positive temperature coefficient of resistance,
- said second silicon carbide layer has an impurity concentration which is lower than that of said first silicon carbide layer,
- said third silicon carbide layer has an impurity concentration which is higher than that of said second silicon carbide layer, and
- in said second silicon carbide layer, an impurity concentration of a region located on a side closer to said first silicon carbide layer is lower than that of a region located on a side closer to said third silicon carbide layer.
A method for manufacturing a semiconductor device which is a bipolar device in which a current flows through a pn junction, comprising the steps of:
- forming a silicon carbide drift layer of a first conductivity type;
- forming a silicon carbide layer of a second conductivity type on said silicon carbide drift layer;
- and
- implanting an ion of the first conductivity type into a part of said silicon carbide layer, to form a layer in a portion of said silicon carbide layer which is located on a side closer to said silicon carbide drift layer, and a layer in a portion of said silicon carbide layer which is located on a side opposite to said silicon carbide drift layer, as a first silicon carbide layer and a second silicon carbide layer, respectively, wherein
- said second silicon carbide layer has a positive temperature coefficient of resistance.
Dependencies are inferred from the claim text.