Single-crystal – oriented-crystal – and epitaxy growth processes; – Apparatus – With means for measuring – testing – or sensing
Patent
1995-06-09
1997-01-14
Nguyen, Nam
Single-crystal, oriented-crystal, and epitaxy growth processes;
Apparatus
With means for measuring, testing, or sensing
117 18, 117208, C30B 3500
Patent
active
055934986
ABSTRACT:
Apparatus and methods for pulling a semiconductor crystal according to a Czochralski method are disclosed. The apparatus includes a crucible containing a melt, a crystal pulling mechanism which pulls the semiconductor crystal from the melt, a motor coupled to the crucible, and a control circuit for energizing the motor to rotate the crucible at a variable speed. The control circuit may energize the motor to rotate the crucible at a continuously varying acceleration and continuously varying rotational speed while the crystal pulling mechanism is pulling at least a portion of the semiconductor crystal from the melt in the crucible. The control circuit may also energize the motor to rotate the crucible at a rotational speed which monotonically increases and decreases. A method for pulling a semiconductor crystal is also disclosed which includes the steps of performing a Fourier analysis on a periodic signal for variably rotating a crucible; generating a sine wave which corresponds to a fundamental Fourier frequency of the periodic signal; and energizing the crucible motor to rotate the crucible at a rotational speed which increases and decreases as a function of the generated sine wave. Other apparatus and methods for pulling crystals with the CZ method to achieve a desired oxygen concentration and gradient are also disclosed.
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Hall Cynthia F.
Kimbel Steven L.
Korb Harold W.
Garrett Felisa
MEMC Electronic Materials , Inc.
Nguyen Nam
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