The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 25, 2001
Filed:
Feb. 22, 1993
Donald Thomas James Hurle, Malvern, GB;
Gordon Charles Joyce, Malvern, GB;
Kathryn Elizabeth McKell, Stockport, GB;
The National Research Development Corporation, London, GB;
Abstract
A method and apparatus for growing single crystal of GaAs, etc uses the Czochralski techniques. Control of crystal (,) diameter is by a closed loop (,) control of melt (,) temperature in response to crystal weight signals (,) W or dW/dt. The invention injects a test signal St (,) into the control loop and performs a signal processing (,), e.g. cross correlation, on St and crystal weight signal. Peak amplitude of correlation values is related to the growing crystal shape. This is used by comparison with reference values (,) to control the growing-out phase from seed diameter (,) to full diameter of the crystal (,).