Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2007-01-16
2007-01-16
Estrada, Michelle (Department: 2823)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S285000, C438S931000, C257SE21054
Reexamination Certificate
active
10884580
ABSTRACT:
A composite Pt/Ti/WSi/Ni Ohmic contact has been fabricated by a physical deposition process which uses electron beam evaporation and dc-sputter deposition. The Ni based composite Ohmic contact on n-Sic is rapid thermally annealed (RTA) at 950° C. to 1000° C. for 30 s to provide excellent current-voltage characteristics, an abrupt, void free contact-SiC interface, retention of the as-deposited contact layer width, smooth surface morphology and an absence of residual carbon within the contact layer and/or at the Ohmic contact-SiC interface. The annealed produced Ni2Si interfacial phase is responsible for the superior electrical integrity of the Ohmic contact to n-SiC. The effects of contact delamination due to stress associated with interfacial voiding has been eliminated. Wire bonding failure, non-uniform current flow and SiC polytype alteration due to extreme surface roughness have also been abolished. The Ohmic contact also avoids electrical instability associated with carbon inclusions within the contact metallization and/or at the contact-SiC interface, that occur under prolonged high temperature and power device operations. Overall, this contact is reliable for high temperature and high power operations and the stresses inclusive of use under those conditions.
REFERENCES:
patent: 5597744 (1997-01-01), Kamiyama et al.
patent: 6468890 (2002-10-01), Bartsch et al.
Cole Melanie W.
Joshi Pooran C.
Estrada Michelle
Randolph William
The United States of America as represented by the Secretary of
Tobergte Nicholas J.
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