Apparatus for automatically controlling crystal growth

Details Apparatus for automatically controlling crystal growth Apparatus for automatically controlling crystal growth

1975-03-31

1977-06-28

Bascomb, Jr., Wilbur L.

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

23273SP, 219 1077, B01J 1718, H05B 506

Patent

active

040323897

ABSTRACT:
Automatic control of the growth from the melt of a crystal in the Czochralski technique by weighing the crystal, comparing the weight with its expected value in a comparator and using the difference in a servo-loop as a servo-control signal is known. The servo-control signal modulates the melt heater power which adjusts the temperature isotherms of the melt in order to maintain the crystal cross-sectional area constant. It has been found that a thermal delay which occurs when heat is conducted from the melt crucible to the crystal/melt interface can cause the crystal cross-sectional area to depart from its uniform expected value. The effect of the thermal delay is compensated for by a phase advance circuit which is connected to the output of the servo-loop comparator.

REFERENCES:
patent: 2908004 (1959-10-01), Levinson
patent: 3136876 (1964-06-01), Crosthwait
patent: 3284172 (1966-11-01), Binder
patent: 3621213 (1971-11-01), Jen et al.
patent: 3692499 (1972-09-01), Andrychuk
patent: 3934983 (1976-01-01), Bardsley et al.
Automated Crystal Puller, Kyle et al., Mat. Res. Bull., vol. 8, No. 4, (April, 1973), pp. 443-450, Pergamon Press, Inc.

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