Semiconductor device and method for producing semiconductor device
Hydrogen atoms and crystal defects are introduced into an n− semiconductor substrate by proton implantation. The crystal defects are generated in the n− semiconductor substrate by electron beam irradiation before or after the proton implantation. Then, a heat treatment for generating donors is performed. The amount of crystal defects is appropriately controlled during the heat treatment for generating donors to increase a donor generation rate. In addition, when the heat treatment for generating donors ends, the crystal defects formed by the electron beam irradiation and the proton implantation are recovered and controlled to an appropriate amount of crystal defects. Therefore, for example, it is possible to improve a breakdown voltage and reduce a leakage current.
1. A method for producing a semiconductor device that forms a donor layer in a semiconductor substrate using proton implantation, comprising:
a crystal defect forming step of generating crystal defects in the semiconductor substrate before or after a proton implantation, wherein the crystal defects are formed with either electron beam irradiation or helium irradiation; and
a donor layer forming step of forming the donor layer in the semiconductor substrate using the proton implantation and a first heat treatment, wherein the crystal defects are formed before the first heat treatment and contribute to the generation of donors during the first heat treatment, and wherein the crystal defects are not completely recovered during the first heat treatment so that some of the crystal defects remain in the donor layer.
2. The method for producing a semiconductor device according to claim 1 , wherein the crystal defect forming step generates the crystal defects such that a predetermined amount of crystal defects remain in the semiconductor substrate during the first heat treatment.
3. The method for producing a semiconductor device according to claim 1 , wherein the crystal defect forming step generates the crystal defects using electron beam irradiation.
4. The method for producing a semiconductor device according to claim 1 , wherein the crystal defects which remain in the semiconductor substrate during the first heat treatment contribute to the formation of the donor layer.
5. The method for producing a semiconductor device according to claim 1 , wherein the crystal defect forming step performs a second heat treatment to adjust an amount of crystal defects in the semiconductor substrate after the crystal defects are formed.
6. The method for producing a semiconductor device according to claim 1 , wherein the first heat treatment is performed under conditions of a temperature of 350° C. to 550° C. and a processing time of 1 to 10 hours.
7. The method for producing a semiconductor device according to claim 1 , further comprising a step of grinding one main surface of the semiconductor substrate before the proton implantation.
8. The method for producing a semiconductor device according to claim 7 , wherein the proton implantation is performed from a rear surface of the semiconductor substrate.
9. The method for producing a semiconductor device according to claim 1 , wherein the proton implantation is performed one or more times and the range of the proton implantation which is performed at least once is equal to or more than 15 μm from the rear surface of the semiconductor substrate.
10. The method for producing a semiconductor device according to claim 1 , wherein the donor layer is an n-type field stop layer of a diode or an insulated gate bipolar transistor.
11. The method for producing a semiconductor device according to claim 1 , wherein a processing temperature of the donor layer forming step performed after the first heat treatment is lower than the temperature of the first heat treatment.
12. The method according to claim 1 , wherein the lifetime of minority carriers in the donor layer is equal to or less than 10 μs.
13. The method according to claim 1 , wherein the lifetime of the carriers in the donor layer is in the range of 0.1 μs to 1 μs.
14. A semiconductor device that forms a donor layer in a semiconductor substrate using proton implantation and is produced by
a crystal defect forming step of generating crystal defects before or after a proton implantation, wherein the crystal defects are formed in the semiconductor substrate with either electron beam irradiation or helium irradiation and
a donor layer forming step of forming the donor layer in the semiconductor substrate using the proton implantation and a first heat treatment, wherein the crystal defects are formed before the first heat treatment and contribute to the generation of donors during the first heat treatment, and wherein the crystal defects are not completely recovered during the first heat treatment so that some of the crystal defects remain in the donor layer.