Method for producing a semiconductor device using laser annealing for selectively activating implanted dopants
View Patent ↗A method for producing a semiconductor device such as a RC-IGBT or a BIGT having a patterned surface wherein partial regions doped with dopants of a first conductivity type and regions doped with dopants of a second conductivity type are on a same side of a semiconductor substrate is proposed. An exemplary method includes: (a) implanting dopants of the first conductivity type and implanting dopants of the second conductivity type into the surface to be patterned; (b) locally activating dopants of the first conductivity type by locally heating the partial region of the surface to be patterned to a first temperature (e.g., between 900 and 1000° C.) using a laser beam similar to those used in laser annealing; and (c) activating the dopants of the second conductivity type by heating the substrate to a second temperature lower than the first temperature (e.g., to a temperature below 600° C.). Boron is an exemplary dopant of the first conductivity type, and phosphorous is an exemplary dopant of the second conductivity type. Boron can be activated in the regions irradiated only with the laser beam, whereas phosphorus may be activated in a low temperature sintering step on the entire surface.
1. A method for producing a semiconductor device with a patterned surface having at least one partial region doped with a dopant of a first conductivity type and at least one region doped with a dopant of a second conductivity type on a same side of a semiconductor substrate, the method comprising:
implanting the dopant of the first conductivity type and implanting the dopant of the second conductivity type into the surface to be patterned;
locally activating the dopant of the first conductivity type by locally heating the at least one partial region of the surface to be patterned to a first temperature using a laser beam; and
activating the dopant of the second conductivity type by heating the semiconductor substrate to a second temperature lower than the first temperature, wherein the dopant of the first conductivity type is implanted and activated in the partial region to a higher doping concentration than the dopant of the second conductivity type thereby locally overcompensating the dopant of the second conductivity type.
2. The method of claim 1 , wherein the dopant of the first conductivity type is at least one of boron and aluminum for forming p-type doping.
3. The method of claim 1 , wherein the dopant of the second conductivity type is at least one of phosphorous and arsenic for forming n-type doping.
4. The method of claim 1 , wherein the first temperature is above 850° C.
5. The method of claim 1 , wherein the second temperature is below 650° C.
6. The method of claim 1 , wherein the dopant of the first conductivity type is implanted with at least one of a dose ranging from 1e13/cm 2 to 1e16/cm 2 and an energy ranging from 5 keV to 200 keV.
7. The method of claim 1 , wherein the dopant of the second conductivity type is implanted with at least one of a dose ranging from 1e12/cm 2 to 1e16/cm 2 and an energy ranging from 50 keV to 600 keV.
8. The method of claim 1 , wherein the dopant of the first conductivity type is implanted to a lower depth than the dopant of the second conductivity type.
9. The method of claim 1 , wherein areas into which the dopant of the first conductivity type is implanted and areas into which the dopant of the second conductivity type is implanted at least partially overlap.
10. The method of claim 1 , wherein locally activating the dopant of the first conductivity type comprises:
scanning a laser beam of a laser annealing apparatus along the partial region to be locally activated.
11. The method of claim 10 , wherein a laser energy and a scanning speed are adapted such that a superficial layer of the substrate is temporarily heated to the first temperature, the superficial portion having a depth of less than 1 μm.
12. The method of claim 1 , wherein heating the substrate to the second temperature comprises:
sintering subsequent to the locally heating of the partial region of the surface to be patterned to the first temperature using the laser beam.
13. The method of claim 12 , comprising:
generating front side structures, wherein the implanting and activating are performed after the generating of front side structures.
14. The method of claim 1 , wherein the semiconductor device is one of a reverse conducting insulated gate bipolar transistor (RC-IGBT) and a bimode insulated gate bipolar transistor (BIGT), and wherein the side having the patterned surface is a rear side of the semiconductor device.
15. The method of claim 1 , wherein the semiconductor device is a diode.
16. The method of claim 2 , wherein the dopant of the second conductivity type is at least one of phosphorous and arsenic for forming n-type doping.
17. The method of claim 2 , wherein the first temperature is above 850° C.
18. The method of claim 3 , wherein the second temperature is below 650° C.
19. The method of claim 16 , wherein the dopant of the first conductivity type is implanted to a lower depth than the dopant of the second conductivity type.
20. The method of claim 16 , wherein areas into which the dopant of the first conductivity type is implanted and areas into which the dopant of the second conductivity type is implanted at least partially overlap.
21. The method of claim 2 , wherein the dopant of the first conductivity type is implanted with at least one of a dose ranging from 1e13/cm 2 to 1e16/cm 2 and an energy ranging from 5 keV to 200 keV.
22. The method of claim 17 , wherein the dopant of the first conductivity type is implanted with at least one of a dose ranging from 1e13/cm 2 to 1e16/cm 2 and an energy ranging from 5 keV to 200 keV.
23. The method of claim 3 , wherein the dopant of the second conductivity type is implanted with at least one of a dose ranging from 1e12/cm 2 to 1e16/cm 2 and an energy ranging from 50 keV to 600 keV.
24. The method of claim 18 , wherein the dopant of the second conductivity type is implanted with at least one of a dose ranging from 1e12/cm 2 to 1e16/cm 2 and an energy ranging from 50 keV to 600 keV.
25. The method of claim 2 , wherein locally activating the dopant of the first conductivity type comprises:
scanning a laser beam of a laser annealing apparatus along the partial region to be locally activated.
26. The method of claim 3 , wherein heating the substrate to the second temperature comprises:
sintering subsequent to the locally heating of the partial region of the surface to be patterned to the first temperature using the laser beam.