Grumman Aerospace Corporation

Janine E Dubois

John Frederick Klein

Victor Curreri

David J Larson, Sr

The present invention monitors thermocouple data from a semiconductor furnace. The data is checked against a first set of profiles which mimic an intended operational temperature profile for the furnace. If the temperature measured in any zone of the furnace falls outside a first set of maximum and minimum limits fixed by the mimicking profiles, a warning is generated thereby giving operational personnel an opportunity to correct the condition. If the condition remains unchecked and further deviation occurs, a second condition is reached as defined by a corresponding second set of mimicking maximum and minimum profiles. This condition is established as a serious condition which will cause a microprocessor to terminate power supply to the furnace. Otherwise, the quality of the grown crystal would be jeopardized; or sufficiently excessive power would be delivered to the furnace so as to cause its damage or destruction.

Alarm system for a crystal growing furnace

A heating system has a substantially cylindrical hollow muffle formed of a alumina ceramic with a plurality of heat-generating windings therearound. A light-actuated power control is operatively connected to the windings. A computer is operatively connected to a temperature monitor associated with an article being heated in the muffle. The computer is also operatively connected to a light-signal generator and provides commands to the generator in the form of a train of equidistantly spaced electrical pulses in response to temperature measurements provided by the monitor such that an article can be heated to an elevated steady state temperature and controlled at that steady state temperature within precise predetermined limits. The precise temperature control makes the system particularly valuable in the fabrication of crystals with uniform properties or having special growth requirements.

Computerized multi-zone crystal growth furnace

A computerized method of digitally controlling the temperature profile of a heated article in which the temperature profile is defined by a plurality of temperature zones spaced about the article. The temperature profile of the article is monitored and a heating cycle requirement of the temperature zones of the profile is computed. A train of minute increments of power is supplied to heat each respective zone in accordance with the computed heating cycle requirements to achieve a precision approximately between .+-.0.1.degree. and .+-.0.5.degree. C. in a temperature range of approximately 400.degree. C. to 1,350.degree. C.

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Shirley, NY, United States of America

Janine E Dubois