Patent Document ID: 8093529
Application ID: 12194019
Patent Flag: 1

Claim One:
1. A control method for controlling the temperature of a sample placed on a sample stage disposed in a plasma processing chamber, the sample stage including a refrigerant flow path to cool the sample stage, a heater to heat the sample stage, and a temperature sensor to measure a temperature of the sample stage, the control method comprising the steps of: measuring, in advance of plasma processing being performed, variations-with-time of: heater electric power, temperature of the sample, and temperature of the temperature sensor; approximating a relationship between the measured values by using a simultaneous linear differential equation; estimating a temperature of the sample from the variation-with-time of: sensor temperature, heater electric power, and plasma heat input, by means of Luenberger states observer equations based on at least one value produced by the simultaneous linear differential equation used for the approximation; and performing a feedback control of temperature of the sample, by using the estimated temperature of the sample to perform a PI control.