Process for making non-uniform minority carrier lifetime distribution in high performance silicon power devices
View Patent ↗An electronic power device comprising a single crystal silicon segment being characterized in that the segment comprises a non-uniform distribution of minority carrier recombination centers, the minority carrier recombination centers comprising a substitutional metal, with the concentration of the centers in a bulk layer being greater than the concentration in a surface layer. The centers have a concentration profile in which the peak density of the centers is at or near the central plane with the concentration generally decreasing from the position of peak density in the direction of the front surface of the segment and generally decreasing from the position of peak density in the direction of the back surface of the segment.
1. An electronic power device comprising:
a single crystal silicon segment having two major, generally parallel surfaces, a front surface of the segment and a back surface of the segment, a central plane between the front and back surfaces, a circumferential edge joining the front and back surfaces, a surface layer which comprises a first region of the segment below the front surface and a distance, D 1 , as measured from the front surface and toward the central plane, and a bulk layer which comprises a second region of the segment between the central plane and the first region, the electronic power device being characterized in that
the single crystal silicon segment comprises a non-uniform distribution of minority carrier recombination centers, the minority carrier recombination centers comprising a substitutional metal, with the concentration of the centers in the bulk layer being greater than the concentration in the surface layer and with the centers having a concentration profile in which the peak density of the centers is at or near the central plane with the concentration generally decreasing from the position of peak density in the direction of the front surface of the segment and with the concentration generally decreasing from the position of peak density in the direction of the back surface of the segment.
2. The electronic power device of claim 1 wherein the device is a thyristor.
3. The electronic power device of claim 1 wherein the device is a power diode.
4. The electronic power device of claim 1 wherein the segment has a carbon concentration which is less than about 1×10 16 atoms/cm 3 .
5. The electronic power device of claim 1 wherein the segment has a thickness ranging from about 500 microns to about 800 microns.
6. The electronic power device of claim 1 wherein the segment has a thickness ranging from about 800 microns to about 1200 microns.
7. The electronic power device of claim 1 wherein the concentration of minority carrier recombination centers in the segment's surface layer is less than about 1×10 11 centers/cm 3 .
8. The electronic power device of claim 1 wherein the concentration of minority carrier recombination centers in the segment's surface layer is less than about 1×10 13 centers/cm 3 .
9. The electronic power device of claim 1 wherein the distance D 1 is at least about 10 microns.
10. The electronic power device of claim 1 wherein the distance D 1 is at least about 30 microns.
11. The electronic power device of claim 1 wherein the distance D 1 is at least about 50 microns.
12. The electronic power device of claim 1 wherein the distance D 1 is at least about 100 microns.
13. An electronic power device comprising:
a single crystal silicon segment having two major, generally parallel surfaces, a front surface of the segment and a back surface of the segment, a central plane between the front and back surfaces, the electronic power device being characterized in that
single crystal silicon segment comprises a non-uniform distribution of minority carrier recombination centers, the minority carrier recombination centers comprising a substitutional metal, and with a maximum concentration of the minority carrier recombination centers being in a region which is between the front surface and the central plane and nearer to the front surface than the central plane and with a minimum concentration of the recombination centers, which is less than the concentration of the recombination centers at the central plane and which is between the front surface and the maximum concentration, the concentration of the recombination centers increasing from the minimum concentration to the maximum concentration and decreasing from the maximum concentration to the central plane.
14. The electronic power device of claim 13 wherein the device is a thyristor.
15. The electronic power device of claim 13 wherein the device is a power diode.
16. The electronic power device of claim 13 wherein the segment has a carbon concentration which is less than about 1×10 16 atoms/cm 3 .
17. The electronic power device of claim 13 wherein the segment has a thickness ranging from about 500 microns to about 800 microns.
18. The electronic power device of claim 13 wherein the segment has a thickness ranging from about 800 microns to about 1200 microns.
19. The electronic power device of claim 13 wherein the segment's maximum concentration of recombination centers is within about 5 microns from the front surface of the segment.
20. The electronic power device of claim 13 wherein the segment's maximum concentration of recombination centers is within about 10 microns from the front surface of the segment.
21. The electronic power device of claim 13 wherein the segment's maximum concentration of recombination centers is within about 20 microns from the front surface of the segment.
22. The electronic power device of claim 13 wherein the segment's maximum concentration of recombination centers is within about 60 microns from the front surface of the segment.