Insulated gate bipolar transistor having first and second field stop zone portions and manufacturing method
An embodiment relates to a method of manufacturing an insulated gate bipolar transistor in a semiconductor body. A first field stop zone portion of a first conductivity type is formed on a semiconductor substrate. A second field stop zone portion of the first conductivity type is formed on the first field stop zone portion. A drift zone of the first conductivity type is formed on the second field stop zone portion. A doping concentration in the drift zone is smaller than 10 13 cm −3 along a vertical extension of more than 30% of a thickness of the semiconductor body upon completion of the insulated gate bipolar transistor.
1. A method of manufacturing an insulated gate bipolar transistor in a semiconductor body, the method comprising:
forming a first field stop zone portion of a first conductivity type on a semiconductor substrate;
forming a second field stop zone portion of the first conductivity type on the first field stop zone portion; and
forming a drift zone of the first conductivity type on the second field stop zone portion, wherein a doping concentration in the drift zone is smaller than 10 13 cm −3 along a vertical extension of more than 30% of a thickness of the semiconductor body upon completion of the insulated gate bipolar transistor,
wherein the doping concentration in the drift zone is set by a background doping of an epitaxial growth equipment having all doping gas inlets turned off during formation of the drift zone.
2. The method of claim 1 , wherein the second field stop zone portion and the drift zone are formed in the same epitaxial growth equipment, and wherein the epitaxial growth equipment is purged with H 2 gas between formation of the second field stop zone portion and the drift zone.
3. The method of claim 1 , wherein a ratio of a maximum doping concentration in the second field stop zone portion to a minimum doping concentration in the drift zone is set in a range of 50:1 to 1000:1.
4. The method of claim 1 , wherein a maximum doping concentration in the second field stop zone portion is set by in-situ doping.
5. The method of claim 1 , wherein a maximum doping concentration in the second field stop zone portion is set by a doping peak caused by implantation of dopant ions and activation or by in-situ doping.
6. The method of claim 5 , wherein setting the doping concentration in the second field stop zone portion comprises setting a constant doping profile along a vertical extension of the second field stop zone portion in a thickness range of 4 to 55 μm.
7. The method of claim 6 , wherein a ratio between a doping concentration of the constant doping profile and a minimum doping concentration of the drift zone ranges between 20:1 and 1000:1.
8. The method of claim 1 , further comprising setting a doping concentration in a top portion of the drift zone more than twice as large as a minimum doping concentration of the drift zone.
9. The method of claim 1 , wherein a gradient of a doping concentration profile in a transition region between the first field stop zone portion and the second field stop zone portion is set smaller than 10 20 cm −4 .
10. The method of claim 1 , wherein q 1 equals an integral of an ionized dopant charge along a vertical extension of the first field stop zone portion and q 2 equals an integral of an ionized dopant charge along a vertical extension of the second field stop zone portion, and wherein a doping concentration profile of the first and second first field stop zone portions is adjusted to set a ratio of q 2 to q 1 in a range from 1 to 8.
11. The method of claim 10 , wherein a sum of q 1 and q 2 is set smaller than a breakdown charge of the semiconductor body.
12. The method of claim 10 , wherein q 1 is set smaller than 60% of a breakdown charge of the semiconductor body.
13. The method of claim 1 , further comprising thinning the semiconductor body by removing material of the semiconductor substrate from a second surface of the semiconductor body opposite to the first surface.
14. The method of claim 1 , wherein forming the first field stop zone portion comprises an epitaxial growth process.
15. The method of claim 1 , wherein forming the second field stop zone portion comprises an epitaxial growth process.
16. The method of claim 1 , wherein forming the drift zone comprises an epitaxial growth process.
17. A method of manufacturing an insulated gate bipolar transistor in a semiconductor body, the method comprising:
forming a first field stop zone portion of a first conductivity type on a semiconductor substrate;
forming a second field stop zone portion of the first conductivity type on the first field stop zone portion; and
forming a drift zone of the first conductivity type on the second field stop zone portion, wherein a doping concentration in the drift zone is smaller than 10 13 cm −3 along a vertical extension of more than 30% of a thickness of the semiconductor body upon completion of the insulated gate bipolar transistor,
wherein a maximum doping concentration in the second field stop zone portion is set by in-situ doping.
18. The method of claim 17 , wherein setting the doping concentration in the drift zone comprises counter-doping.
19. The method of claim 17 , further comprising setting a doping concentration in a top portion of the drift zone more than twice as large as a minimum doping concentration of the drift zone.
20. The method of claim 17 , wherein the second field stop zone portion and the drift zone are formed in the same epitaxial growth equipment, and wherein the epitaxial growth equipment is purged with H 2 gas between formation of the second field stop zone portion and the drift zone.
21. The method of claim 17 , wherein q 1 equals an integral of an ionized dopant charge along a vertical extension of the first field stop zone portion and q 2 equals an integral of an ionized dopant charge along a vertical extension of the second field stop zone portion, and wherein a doping concentration profile of the first and second first field stop zone portions is adjusted to set a ratio of q 2 to q 1 in a range from 1 to 8.
22. A method of manufacturing an insulated gate bipolar transistor in a semiconductor body, the method comprising:
forming a first field stop zone portion of a first conductivity type on a semiconductor substrate;
forming a second field stop zone portion of the first conductivity type on the first field stop zone portion;
forming a drift zone of the first conductivity type on the second field stop zone portion, wherein a doping concentration in the drift zone is smaller than 10 13 cm −3 along a vertical extension of more than 30% of a thickness of the semiconductor body upon completion of the insulated gate bipolar transistor; and
setting a doping concentration in a top portion of the drift zone more than twice as large as a minimum doping concentration of the drift zone.
23. The method of claim 22 , wherein setting the doping concentration in the drift zone comprises counter-doping.
24. The method of claim 22 , wherein the second field stop zone portion and the drift zone are formed in the same epitaxial growth equipment, and wherein the epitaxial growth equipment is purged with H 2 gas between formation of the second field stop zone portion and the drift zone.
25. The method of claim 22 , wherein ql equals an integral of an ionized dopant charge along a vertical extension of the first field stop zone portion and q 2 equals an integral of an ionized dopant charge along a vertical extension of the second field stop zone portion, and wherein a doping concentration profile of the first and second first field stop zone portions is adjusted to set a ratio of q 2 to q 1 in a range from 1 to 8.