NOVEL DEVELOPMENT OF THE WEIGHING METHOD FOR AUTOMATIC CZOCHRALSKI CRYSTAL-GROWTH OF SEMICONDUCTORS

It is demonstrated both experimentally and theoretically that, by modu lating the heater power supplied to the melt and by cross correlating that modulated signal with the output of a crystal weight sensor, a ro bust signal can be obtained which increases strongly as grow-out of a semiconductor crystal from a seed proceeds. This signal could be used as an improved sensor in automatic diameter control systems for semico nductor growth and overcomes the problem of using the differentiated w eight signal directly which, in some situations, fails to detect rapid grow-out soon enough to avoid ''flash-out'' of the crystal.