Method of improving mechanically prepared substrate surfaces of

Details Method of improving mechanically prepared substrate surfaces of Method of improving mechanically prepared substrate surfaces of

1990-10-03

1993-04-06

Wilczewski, Mary

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

437100, 437 93, 437946, 156613, 156DIG64, 156DIG68, 148DIG148, C30B 2502, C30B 2936

Patent

active

052000222

DESCRIPTION:

BRIEF SUMMARY
epared (0001) surface of alpha silicon carbide is used as a substrate for epitaxial deposition of beta silicon carbide thereon, the resulting layer is often an unsatisfactory mixture of alpha and beta polytypes. In turn, the resulting thin film often lacks utility for those electronic applications for which substantially pure polytype beta silicon carbide is desired.
Therefore, most successful growth of beta silicon carbide thin films on 6H alpha silicon carbide substrates has to date been limited to growth upon naturally occurring (0001) surfaces. As stated earlier, however, because of the recent success in growing relatively large bulk crystals of 6H alpha silicon carbide, it would be most desirable if such large crystals could be sliced into large wafers upon which beta silicon carbide thin films could be successfully grown, so that larger wafers, larger devices, and larger numbers of devices can be appropriately and successfully formed.


OBJECT AND SUMMARY OF THE INVENTION

Therefore, it is an object of the invention to provide a method for the growth of epitaxial layers of beta silicon carbide of extremely pure polytype composition on substrates of alpha silicon carbide, particularly where the substrates are mechanically prepared.
The invention meets this object by providing a method of improving a mechanically prepared surface of alpha silicon carbide by decreasing the frequency and energy of exposed higher energy lattice positions along a mechanically prepared {0001} surface of an alpha silicon carbide substrate.
In another embodiment, the invention comprises a method of growing epitaxial layers of beta silicon carbide on mechanically prepared surfaces of silicon carbide.
In an additional embodiment, the invention comprises a surface of silicon carbide that encourages the growth of beta silicon carbide thereon under growth conditions for which beta silicon carbide is favored.
In yet another embodiment, the invention comprises a device precursor for devices formed in beta silicon carbide.
The foregoing and other objects, advantages and features of the invention, and the manner in which the same are accomplished, will become more apparent upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings, which illustrate preferred and exemplary embodiments, and wherein:


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing of a silicon carbide crystal lattice for which the present invention has not been incorporated;
FIG. 2 is partial perspective schematic diagram similar to that of FIG. 1;
FIG. 3 is a 100.times. optical micrograph of an unetched, undoped 3C-SiC film grown on a 6H-SiC wafer, but without incorporating the present invention;
FIG. 4 is a 400.times. optical micrograph of the wafer of FIG. 3 following an etching step;
FIG. 5 is a 100.times. optical micrograph of the surface morphology of a beta-SiC film grown on a (0001) Si face of a 6H-SiC substrate using the present invention;
FIG. 6 is a 200.times. optical micrograph of the surface shown in FIG. 5 after chemical etching;
FIG. 7 is a 100.times. optical micrograph of a (0001) Si face of a 6H-SiC substrate following treatment according to the present invention;
FIG. 8 is another 100.times. optical micrograph of the surface morphology of a beta-SiC film grown on the (0001) Si face of a 6H-SiC substrate using the present invention;
FIG. 9 is a 400.times. optical micrograph of the surface of FIG. 8 following chemical etching;
FIG. 10 is a 100.times. optical micrograph of the surface morphology of a beta-SiC thin grown on a (0001) Si face of a 6H-SiC substrate incorporating the method of the present invention; and
FIG. 11 is a 400.times. optical micrograph of the surface of FIG. 10 following chemical etching.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In its most fundamental embodiment, the present invention is a method of improving a mechanically prepared surface of alpha silicon carbide for increasing the polytype purity of an epitaxial layer of beta silicon

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This invention was made with Government support under Department of the Navy Contract No. N00014-90-C-0038. The Government was certain rights in this invention.

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