Patent ID: 6940047

Claim:
A heat treatment apparatus for successively heat treating a series of planar substrates one by one in a plurality of heat treatment cycles, the apparatus comprising: a furnace body having a boundary surface oriented to face one of the series of substrates upon positioning of the substrate in the heat treatment apparatus for heat treatment; a controllable heater configured to heat the furnace body at a power level set by a power setting; a heat treatment temperature sensor configured to measure a treatment temperature experienced by the substrate during heat treatment; and a temperature regulator for controlling the treatment temperature, the temperature regulator configured to receive a heat treatment temperature reading from the treatment temperature sensor, to receive a desired temperature input for a desired treatment temperature and to generate and to output the power setting for the heater, wherein the temperature regulator further comprises: a first computational component configured to generate one or more trigger signals resonant with a frequency of the heat treatment cycles; and a second computational component configured to calculate a control set-point, the control set-point at least partially determining the power setting for the heater, the second computational component further configured to receive the trigger signals and to calculate, upon receiving the trigger signals, a new control set-point using the treatment temperature readings and to hold the new control set-point until the calculation is triggered again by a next trigger signal.