US 6,747,291 B1 · Ohmic contacts on p-type silicon carbide using carbon films

Abstract

Ohmic contact formation on p-type Silicon Carbide is disclosed. The formed contact includes an initial amorphous Carbon film layer converted to graphitic sp2 Carbon during an elevated temperature annealing sequence. Decreased annealing sequence temperature, reduced Silicon Carbide doping concentration and reduced specific resistivity in the formed ohmic contact are achieved with respect to a conventional p-type Silicon Carbide ohmic contact. Addition of a Boron carbide layer covering the p-type Silicon Carbide along with the sp2 Carbon is also disclosed. Ohmic contact improvement with increased annealing temperature up to an optimum temperature near 1000° C. is included. Addition of several metals including Aluminum, the optimum metal identified, over the Carbon layer is also included; many other of the identified metals provide Schottky rather than the desired ohmic contacts, however.

Claims18

Dependent claims

The method of fabricating a graphitic sp2 Carbon-enabled ohmic contact for a p-type Silicon Carbide semiconductor device, said method comprising the steps of:

providing a cleaned surfaced wafer sample of p-type Silicon Carbide having a selected doping concentration of up to 1×1019 atoms/cm3 and selected initial resistivity characteristics;
covering said sample cleaned surface with a layer of amorphous sp2 and sp3 Carbon mixture;
supplying a layer of Carbon conversion-accelerating catalytic elemental material over said sample layer of amorphous sp2 and sp3 Carbon mixture;
converting a substantial portion of said catalytic elemental material layer-covered amorphous sp2 and sp3 Carbon mixture on said sample to elemental material-catalyzed graphitic sp2 Carbon;
said converting step including a heat treating annealing of said sample at a temperature less than 1000° C. but sufficiently high to achieve ohmic contact electrical characteristics between said converted, element material catalyzed graphitic sp2 Carbon and said sample of p-type Silicon Carbide;
and
disposing an external circuit electrically conductive element in contact with a selected portion of said converted, element material catalyzed graphitic sp2 Carbon.

4 more elements

Dependencies are inferred from the claim text.

Ohmic contacts on p-type silicon carbide using carbon films

Life of this patent

Ohmic contacts on p-type silicon carbide using carbon films

Life of this patent

Abstract

Claims18