Controlling melt-solid interface shape of a growing silicon crystal using a variable magnetic field
AssigneeMEMC Electronic Materials, Inc.
InventorZheng Lu
Life of this patent
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Abstract
System for controlling crystal growth in a Czochralski crystal growing apparatus. A magnetic field is applied within the crystal growing apparatus and varied to control a shape of the melt-solid interface where the ingot is being pulled from the melt. The shape of the melt-solid interface is formed to a desired shape in response to the varied magnetic field as a function of a length of the ingot.
Claims20
A system for controlling crystal growth in a crystal growing apparatus, said crystal growing apparatus having a heated crucible including a semiconductor melt from which a monocrystalline ingot is grown according to a Czochralski process, said ingot being grown on a seed crystal pulled from the melt, said melt and said ingot forming a melt-solid interface therebetween, said system comprising:
- first and second coils positioned near the crucible for applying a cusped magnetic field to the melt;
- a variable power supply for energizing the coils to produce the magnetic field applied to the melt;
- and
- a controller for varying the power supply while the ingot is being pulled from the melt, said variable power supply being responsive to the controller for varying the magnetic field to control cusp position of the magnetic field relative to the melt-solid interface between the melt and the ingot to control a shape of the melt-solid interface, said controlled shape of the melt-solid interface being a function of length of the ingot.
A system for controlling crystal growth in a crystal growing apparatus, said crystal growing apparatus having a heated crucible including a semiconductor melt from which a monocrystalline ingot is grown according to a Czochralski process, said ingot being grown on a seed crystal pulled from the melt, said system comprising:
- first and second coils positioned near the crucible for applying a cusped magnetic field to the melt, said magnetic field being based on power distributed to said first and second coils;
- a first power supply for supplying the first coil with power according to a first power distribution;
- a second power supply for supplying the second coil with power according to a second power distribution;
- and
- a controller for controlling the first and second power supplies while the ingot is being pulled from the melt to produce the magnetic field applied to the melt, said controller controlling the first and second power supplies according to the first and second power distributions, respectively, for varying the magnetic field to control a shape of the melt-interface as a function of length of the ingot.
A system for producing a monocrystalline semiconductor ingot by a Czochralski process, said system comprising:
- a crystal growing apparatus having a heated crucible, said crucible containing a semiconductor melt from which the ingot is grown on a seed crystal pulled from the melt, said melt and said ingot forming a melt-solid interface therebetween;
- first and second coils positioned near the crucible for applying a cusped magnetic field to the melt;
- a variable power supply for energizing the coils to produce the magnetic field applied to the melt;
- and
- a controller for varying the power supply while the ingot is being pulled from the melt, said variable power supply being responsive to the controller for varying the magnetic field to control cusp position of the magnetic field relative to the melt-solid interface between the melt and the ingot for controlling a shape of the melt-solid interface, said controlled shape of the melt-solid interface being a function of length of the ingot.
Dependencies are inferred from the claim text.