Patent Document ID: 20090310645
Application ID: 12194019
Patent Flag: 0

Claim One:
1. A sample temperature control method for controlling the temperature of a sample placed on a sample stage that is disposed in a plasma processing chamber for placing the sample and has 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 method comprising the steps of: measuring in advance, with no plasma processing being performed, the variations-with-time of supply electric power to the heater, temperature of the sample, and temperature of the temperature sensor; approximating the relation among the measured values using a simultaneous linear differential equation; estimating a sample temperature from the variation-with-time of sensor temperature, heater electric power, and plasma heat input by means of the Luenberger's states observer based on the simultaneous linear differential equation used for the approximation; and performing a feedback control of sample temperature using the estimated sample temperature.