Method of producing monocrystalline silicon
AssigneeGTAT Corporation
InventorsScott J. Turchetti, Ning Duanmu
Life of this patent
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Abstract
A method of producing a crystalline product comprising a high percentage by volume monocrystalline material in a crystal growth apparatus is disclosed. The method comprises the steps of providing a crucible comprising feedstock and at least one monocrystalline seed, melting the feedstock without substantially melting the monocrystalline seed under controlled conditions, and forming the crystalline product by solidification of the melt also under controlled conditions. The resulting crystalline product comprises greater than 50% by volume monocrystalline material.
Claims24
A method of producing a crystalline material comprising the steps of
- i) providing a crystal growth apparatus comprising
- a hot zone surrounded by an insulation cage,
- a crucible placed within the hot zone, wherein the crucible comprises at least one monocrystalline silicon seed arranged on a bottom of the crucible and silicon feedstock arranged on top of the monocrystalline silicon seeds,
- an upper thermocouple positioned above the crucible, and
- a heating system comprising a top heater positioned above the crucible and at least one side heater positioned around sides of the crucible, wherein the top heater and the side heaters are configured to be independently supplied with power;
- ii) melting the silicon feedstock without substantially melting the at least one monocrystalline silicon seed, comprising
- a) heating the hot zone to a target temperature above the melting point of silicon, as measured by the upper thermocouple, by supplying power independently to the top heater and the side heaters in a first top heater/side heater power ratio;
- b) opening the insulation cage beneath the crucible upon reaching the target temperature;
- and
- c) changing the power independently supplied to the top heater and the side heaters to a second top heater/side heater power ratio, wherein the second top heater/side heater power ratio is greater than the first top heater/side heater power ratio, thereby melting the silicon feedstock without substantially melting the at least one monocrystalline silicon seed;
- and
- iii) forming the crystalline material comprising
- a) removing heat from the hot zone and
- b) changing the power independently supplied to the top heater and the side heaters to a final top heater/side heater power ratio, wherein the final top heater/side heater power ratio is less than the first top heater/side heater power ratio, thereby forming the crystalline material, wherein the crystalline material comprises greater than 50% by volume monocrystalline silicon.
A crystalline silicon material comprising greater than 80% monocrystalline silicon.
Dependencies are inferred from the claim text.