Powder metallurgy tungsten crucible for aluminum nitride crystal growth
AssigneeCrystal IS, Inc.
InventorsLeo J. Schowalter, Glen A. Slack
Life of this patent
Estimating the term…
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. The crucible includes a plurality of tungsten grains and a wall thickness of at least about 1.5 times the average tungsten grain size. In particular embodiments, the crucible includes first and second layers of tungsten 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 machined from a bar, plate, or billet of powder metallurgy tungsten.
Claims21
A sealable tungsten crucible for growing aluminum-nitride semiconductor crystal, said crucible comprising:
- an elongated wall structure extending in a longitudinal direction;
- said wall structure defining an interior crystal growth cavity;
- said wall structure including a plurality of tungsten grains;
- said grains being configured to swell due to aluminum absorption;
- said grains forming at least first and second layers, said first layer including grains forming an inside surface of said crucible and said second layer being superimposed with said first layer;
- said layers including diffusion pathways defined by boundaries between adjacent grains;
- and
- wherein diffusion pathways of said first layer are substantially obstructed by swollen grains of said second layer.
A sealable tungsten crucible for growing a III-nitride semiconductor crystal, said crucible comprising:
- an elongated wall structure extending in a longitudinal direction;
- said wall structure defining an interior crystal growth cavity;
- said wall structure including a plurality of tungsten grains;
- and
- said wall structure having a thickness dimension extending in a direction substantially perpendicular to said longitudinal direction, said thickness dimension being at least about 1.5 times the average tungsten grain size.
A sealable tungsten crucible for growing a III-nitride semiconductor crystal, said crucible comprising:
- an elongated wall structure extending in a longitudinal direction;
- said wall structure defining an interior crystal growth cavity;
- said wall structure including a plurality of tungsten grains;
- and
- said grains forming at least first and second layers, said first layer including grains forming an inside surface of said crucible and said second layer being superposed with said first layer.
A method for fabricating a tungsten crucible for use in growing aluminum nitride single crystals, said method comprising:
- machining an elongated wall structure from a bar of powder metallurgy tungsten, said wall structure extending in a longitudinal direction;
- the wall structure defining an interior crystal growth cavity and including a plurality of tungsten grains;
- wherein said grains form at least first and second layers, the first layer including grains forming an inside surface of the crucible and the second layer being superposed with the first layer.
A method for fabricating an aluminum nitride crystal, said method comprising:
- depositing aluminum nitride in a crystal growth cavity of a tungsten crucible having an elongated wall structure extending in a longitudinal direction, the wall structure defining an interior crystal growth cavity and including a plurality of tungsten grains, the grains forming at least first and second layers, the first layer including grains forming an inside surface of the crucible and the second layer being superposed with the first layer;
- sealing the crucible;
- heating at least a portion of the crucible to a temperature in excess of about 2000 degrees C.
Dependencies are inferred from the claim text.