| 摘要 |
PURPOSE:To control the diameter of a material other than silicon in high accuracy, by monitoring a grown crystal by a television camera in Czochralski method, extracting a given signal from luminance signals on a fixed sensing line, calculating the crystal diameter. CONSTITUTION:Luminance signals on the sensing line 41 of the raw material melt 43 and the crystal ingot 42 to be pulled up are monitored by a television camera, and luminance q0-q479 at 480 points on the sensing line 41 are collected by a 8 bit AD convertor. The diameter is calculated according to the flow chart. As mentioned above, the measurement of the crystal diameter is repeated in a fixed period. When the value of change becomes >= a given value, the pulling speed or temperature is subjected to feedback control, to pull up a crystal with a constant diameter. |
