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Design and Process Issues for Silicon Carbide Power DiMOSFETS

Published online by Cambridge University Press:  21 March 2011

Sei-Hyung Ryu ,
Anant K. Agarwal ,
Nelson S. Saks ,
Mrinal K. Das ,
Lori A. Lipkin ,
Ranbir Singh  and
John W. Palmour
Sei-Hyung Ryu
Affiliation:
Cree, Inc., 4600 Silicon Drive Durham, NC 27703
Anant K. Agarwal
Affiliation:
Cree, Inc., 4600 Silicon Drive Durham, NC 27703
Nelson S. Saks
Affiliation:
Navel Research Laboratory, 4555 Overlook Avenue Washington, D.C. 20375
Mrinal K. Das
Affiliation:
Cree, Inc., 4600 Silicon Drive Durham, NC 27703
Lori A. Lipkin
Affiliation:
Cree, Inc., 4600 Silicon Drive Durham, NC 27703
Ranbir Singh
Affiliation:
Cree, Inc., 4600 Silicon Drive Durham, NC 27703
John W. Palmour
Affiliation:
Cree, Inc., 4600 Silicon Drive Durham, NC 27703
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Abstract

This paper discusses the design and process issues of high voltage power DiMOSFETs (Double implanted MOSFETs) in 4H-silicon carbide (SiC). Since Critical Field (EC) in 4H-SiC is very high (10X higher than that of a Si), special care is needed to protect the gate oxide. 2D device simulation tool was used to determine the optimal JFET gap, which provides adequate gate oxide protection as well as a reasonable JFET resistance. The other issue in 4H-SiC DiMOSFETs is extremely low effective channel mobility (μeff) in the implanted p-well regions. NO anneal of the gate oxide and buried channel structure are used for increasing μeff. NO anneal, which was reported to be very effective in increasing the μeff of SiC MOSFETS in p-type epilayers, did not produce reasonable μeff of SiC MOSFETs in the implanted p-well. Buried channel (BC) structure with 2.7×1012 cm−2 charge in the channel showed high μeff utilizing bulk buried channel, but resulted in a normally-on device. However, it was shown that by controlling the charge in the BC layer, a normally off device with high μeff can be produced. A 3.3 mm × 3.3 mm DiMOSFET with BC structure showed a drain current of 10 A, which is the highest current reported in SiC power MOSFETs to date, at a forward drop of 4.4 V with a gate bias of only 2.5 V.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 640: Symposium H – Silicon Carbide-Materials, Processing, and Devices , 2000 , H4.5
Copyright
Copyright © Materials Research Society 2001

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References

REFERENCES

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