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Growing Large Area Silicon Carbide and Aluminum Nitride Crystals

IP.com Disclosure Number: IPCOM000082919D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+2]

Abstract

SiC, although it is the oldest known synthesized semiconductor compound, has not been widely utilized for electronic and electroluminescent semiconductor devices, because there is no known process for economically making large area, reproducible single-crystal wafers such as have been developed for silicon, germanium and gallium arsenide, for instance.

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Growing Large Area Silicon Carbide and Aluminum Nitride Crystals

SiC, although it is the oldest known synthesized semiconductor compound, has not been widely utilized for electronic and electroluminescent semiconductor devices, because there is no known process for economically making large area, reproducible single-crystal wafers such as have been developed for silicon, germanium and gallium arsenide, for instance.

Described is a method for producing large area silicon carbide single-crystal layers. Briefly, it involves starting with a sapphire single-crystal wafer and chemically vapor growing a tungsten overlay 1 on the sapphire wafer (which can be of 1" diameter and larger) to a thickness of a few thousands of an inch, in the manner described in IBM Technical Disclosure Bulletin, Vol.15, No.2, July 1972, page 564, in an article entitled, "Preparation of Large Area Single Crystal Strain Free Tungsten Surfaces" by J. J. Cuomo. This tungsten overlay is removed from the sapphire and the side next to the sapphire is found to be as smooth as the polished face of the sapphire itself (of whose surface it is a negative replica), and is also clean and highly ordered or nearly single crystalline at the surface. On this tungsten surface, a layer on the order of a micron thick of AlN 2 is reactively sputtered at about 1000 Degrees C and this, too, is highly ordered or single crystalline.

The A1N coated tungsten wafer is then placed A1N side down on a smooth SiC source 3, which is either a single or polycrystalline wafer or a pressed or sintered wafer of powdered SiC, as shown in the figure. This assembly is then placed in a carbon crucible 4 which is placed in a furnace 5, capable of generating temperatures of the order of 2000 Degrees C and providing temperature gradients 7 up to a few 100 Degrees C/mil. Crucible 4 is placed in an inert gas such as argon mixed with a small percentage of hydrogen for cleaning and vapor growth promotion, and the crucible is heated by a tungsten or carbon heater 6 or other suitable means until the silicon carbide is approximately 1800 Degrees C. The geometry and thermal gradients are adjusted so that the tungsten is approximately 100 Degrees C cooler.

Even though the A1N tends to decompose at this temperature, it has been found that SiC growth will initiate itself as the temperature of the system is gradually raised, so that erosion of the AlN occurs only at the...