Silica glass crucible
AssigneeHeraeus Shin-Etsu America, Inc.
InventorsKatsuhiko Kemmochi, Robert O. Mosier, Paul G. Spencer
Life of this patent
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Abstract
A silica glass crucible is manufactured by introducing into a rotating crucible mold bulk silica grain to form a bulky wall including a bottom wall and a side wall. After heating the interior of the mold to begin to fuse the bulk silica grains, an inner silica grain, doped with aluminum, is introduced. The heat at least partially melts the inner silica grain, allowing it to fuse to the wall to form an inner layer. The crucible is cooled, the fused silica grains forming nuclei of crystalline silica within the inner layer.
Claims31
A crucible comprising:
- a crucible wall including a bottom wall and side wall;
- an aluminum-doped inner layer formed on an inner portion of said crucible wall, said inner layer having a thickness in the range of 0.2 mm to less than 0.5 mm;
- and
- an aluminum-doped outer layer formed on an outer portion of said crucible wall.
A silica glass crucible, comprising:
- a crucible wall including a bottom wall and a side wall;
- an interior cavity defined by said crucible wall;
- and
- an inner layer formed on the innermost portion of said crucible wall;
- wherein said inner layer has a depth in the range of from 0.2 mm to less than 0.5 mm and is homogeneously doped with aluminum in the range of about 50-500 ppm.
A silica glass crucible comprising:
- a crucible wall including a bottom wall and a side wall;
- and
- an inner layer non-homogeneously doped with aluminum,
- said inner layer is disposed on an inner portion of said said crucible wall and having a thickness of at least 0.2 mm, said inner layer doped with aluminum in a non-uniform distribution of silica, and
- wherein said inner layer has an average aluminum doping of 30-100 ppm.
A crucible, comprising:
- a crucible wall including a bottom wall and side wall;
- an aluminum-doped inner layer on an inner portion of said crucible wall;
- and
- an aluminum-doped outer layer on an outer portion of said crucible wall;
- wherein the inner layer is in the range of 0.2 mm to less than 0.5 mm deep and doped with aluminum in the range of about 50-500 ppm.
A method for preparing a silicon melt for pulling a single crystal by the Czochralski method, comprising:
- loading silicon charge into a crucible including:
- a crucible wall including a bottom wall and a side wall,
- an interior cavity defined by said crucible wall, and
- an inner layer formed on the innermost portion of said crucible wall, wherein said inner layer has a depth in the range of 0.2mm to less than 0.5mm and is homogeneously doped with aluminum in the range of about 50-500ppm;
- and melting the polycrystalline silicon within the crucible to substantially devitrify a portion of inner layer which is in contact with the molten silicon.
A method for preparing a molten silicon mass for pulling a single crystal by the Czochralski method, comprising:
- heating a silicon charge in a crucible to form the molten silicon mass, the crucible including:
- a crucible wall including a bottom wall and side wall,
- an aluminum-doped inner layer formed on an inner portion of said crucible wall, and
- an aluminum-doped outer layer formed on an outer portion of said crucible wall,
- wherein the inner layer is in the range of 0.2mm to less than 0.5mm deep and doped with aluminum in the range of about 50-500ppm.
- forming a devitrified shell of β-cristobalite on the inner and outer layers of the side wall of the crucible when the charge of polysilicon is heated to form the molten silicon mass.
A method for preparing a silicon melt for pulling a single crystal by the Czochralski method, comprising:
- loading silicon charge into a crucible including:
- a crucible wall including a bottom wall and a side wall,
- an inner layer non-homogeneously doped with aluminum,
- said inner layer disposed on an inner portion of said crucible wall and having a thickness of at least 0.2mm, and
- said inner layer doped with aluminum in a non-uniform distribution,
- wherein said inner layer has an average aluminum doping of 30-100 ppm;
- and
- melting the polycrystalline silicon within the crucible and substantially converting at least a portion of inner layer which is in contact with the molten silicon from an amorphous glass structure to a β- cristobalite crystalline structure.
Dependencies are inferred from the claim text.