Powder metallurgy crucible for aluminum nitride crystal growth
AssigneeCrystal IS, Inc.
InventorsLeo J. Schowalter, Glen A. Slack
Life of this patent
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Abstract
A crucible for growing III-nitride (e.g., aluminum nitride) single crystals is provided. The crucible includes an elongated wall structure defining an interior crystal growth cavity. Embodiments include a plurality of grains and a wall thickness of at least about 1.5 times the average grain size. In particular embodiments, the crucible includes first and second layers of grains the first layer including grains forming an inside surface thereof and the second layer being superposed with the first layer. The crucible may be fabricated from tungsten-rhenium (W—Re) alloys; rhenium (Re); tantalum monocarbide (TaC); tantalum nitride (Ta2N); hafnium nitride (HfN); a mixture of tungsten and tantalum (W—Ta); tungsten (W); and combinations thereof.
Claims32
A sealable crucible for growing a III-nitride semiconductor crystal, said crucible comprising an elongated wall structure extending in a longitudinal direction, said wall structure comprising a plurality of grains and defining an interior crystal growth cavity, said wall structure having a thickness dimension (i) extending in a direction substantially perpendicular to said longitudinal direction and (ii) being at least about 1.5 times the average grain size.
A method for fabricating a crucible for use in growing aluminum nitride single crystals, said method comprising fabricating a wall structure from a granular material, the wall structure defining an interior crystal growth cavity and comprising a plurality of grains, said grains forming at least first and second layers, the first layer including a portion of the plurality of grains forming an inside surface of the wall structure and the second layer being superimposed on the first layer.
A method for fabricating an aluminum nitride crystal, said method comprising:
- (i). depositing aluminum nitride in a crystal growth cavity of a crucible comprising an elongated wall structure defining the crystal growth cavity, the elongated wall structure comprising a plurality of grains, the grains forming at least first and second layers, the first layer including grains forming an inside surface of the wall structure and the second layer being superimposed on the first layer;
- (ii). sealing the crucible;
- and
- (iii). heating at least a portion of the crucible to a temperature in excess of about 2000° C.
- wherein during step (iii), in at least the portion of the crucible, grains of at least the second layer swell to substantially obstruct diffusion of aluminum along diffusion pathways defined by boundaries between grains of at least the first layer.
A crucible for use in the single-crystal growth of aluminum nitride, said crucible comprising a wall structure defining an interior crystal growth cavity and comprising a plurality of grains defining a plurality of diffusion pathways within said structure, said grains swelling upon absorption of at least one of aluminum and nitrogen, thereby substantially obstructing at least some of the diffusion pathways.
An aluminum nitride single-crystal boule tapered to a diameter greater than about 20 mm.
Dependencies are inferred from the claim text.