Zone heating system with feedback control

摘要

A structure and method are disclosed which allow for a tighter control of the temperature across a wafer substrate. In accordance with the present invention, a wafer (16) to be processed is heated to a constant and uniform temperature by an RF induction coil (18,20) including a plurality of heating zones each of which being shunted by an associated capacitor tuned to a specific frequency. By adjusting the time during which current of a particular frequency is provided to the induction coil, current flow within, and thus the heat generated in, each of the zones may be independently controlled. Since the heat generated in the susceptor quickly changes in response to changes in current flow therein, both deviations of the wafer temperature from the processing temperature and temperature gradients across the surface of the wafer may be quickly corrected. This superior thermal response results in the present invention maintaining a wafer at a uniform temperature during heating and cooling with increased accuracy and precision.