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US 2026/0015768 A1Published application
Magnet ramp profiles during single crystal silicon growth
AssigneeGlobalWafers Co., Ltd.
InventorsZheng Lu, Sumeet S. Bhagavat
Life of this patent
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Abstract
Control of magnet ramp profiles with predetermined ramp rates in Czochralski silicon crystal growth to mitigate the transient behavior in silicon melt flow and its impact to semiconductor silicon crystal growth and crystal quality. The magnetic field strength may be regulated in at least two stages or at least three stages of growth of the constant diameter portion of the ingot.
Claims20
A method for reducing transient melt behavior during growth of a single crystal silicon ingot, the method comprising:
- melting polycrystalline silicon in a crucible enclosed in a growth chamber to form a melt, the melt having a melt surface;
- contacting a seed crystal with the melt;
- withdrawing the seed crystal from the melt to form the silicon ingot;
- applying a horizontal magnetic field to the melt during formation of a constant diameter portion of the silicon ingot, the horizontal magnetic field being applied by a pair of magnetic coils, the pair of magnetic coils being characterized by a maximum magnetic field strength that the pair of magnetic coils is capable of applying to the melt;
- regulating a magnetic field strength during formation of the constant diameter portion of the silicon ingot in at least three stages of ingot growth, the constant diameter portion having a length, the at least three stages comprising:
- a first stage corresponding to formation of the silicon ingot from a beginning of formation of the constant diameter portion of the silicon ingot up to a first intermediate ingot length;
- a second stage corresponding to formation of the silicon ingot from at least the first intermediate ingot length to a second intermediate ingot length;
- a third stage corresponding to formation of the silicon ingot from at least the second intermediate ingot length to a third intermediate ingot length;
- wherein regulating the magnetic field strength comprises:
- ramping the magnetic field strength from an initial magnetic field strength to a first intermediate magnetic field strength during the first stage;
- maintaining the magnetic field strength at a second stage magnetic field strength during the second stage, the second stage magnetic field strength being between 75% and 125% of the first intermediate field strength;
- and
- ramping the magnetic field strength from the second stage magnetic field strength to a second intermediate magnetic field strength during the third stage.
10 more elements
A method for reducing transient melt behavior during growth of a single crystal silicon ingot, the method comprising:
- melting polycrystalline silicon in a crucible enclosed in a growth chamber to form a melt, the melt having a melt surface;
- contacting a seed crystal with the melt;
- withdrawing the seed crystal from the melt to form the silicon ingot;
- applying a horizontal magnetic field to the melt during formation of a constant diameter portion of the silicon ingot, the horizontal magnetic field being applied by a pair of magnetic coils, the pair of magnetic coils being characterized by a maximum magnetic field strength that the pair of magnetic coils is capable of applying to the melt;
- regulating a magnetic field strength during formation of the constant diameter portion of the silicon ingot in at least two stages of ingot growth, the constant diameter portion having a length, the at least two stages comprising:
- a first stage corresponding to formation of the silicon ingot from a beginning of formation of the constant diameter portion of the silicon ingot up to a first intermediate ingot length;
- and
- a second stage corresponding to formation of the silicon ingot from at least the first intermediate ingot length to a total length of the constant diameter portion of the silicon ingot;
- wherein regulating the magnetic field strength comprises:
- ramping the magnetic field strength from an initial magnetic field strength to a first intermediate magnetic field strength during the first stage, wherein the magnetic field strength is ramped from the initial magnetic field strength to the first intermediate magnetic field strength in no more than 20% of the length of the constant diameter portion;
- and
- maintaining the magnetic field strength at a second stage magnetic field strength during the second stage, the second stage magnetic field strength being between 75% and 125% of the first intermediate magnetic field strength.
9 more elements
Dependencies are inferred from the claim text.