Patent ID: 7330346

Claim:
A method for measuring self-bias voltage in an etching apparatus comprising an electrostatic chuck mechanism for chucking a sample, a mechanism for filling a cooling gas to a rear surface of the sample subjected to electrostatic chuck and controlling the pressure of the cooling gas, and a means for measuring a relative force of electrostatic chuck of the sample based on a status of control of the rear surface pressure of the sample during processing, the method comprising the steps of: acquiring the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on the status of control of the rear surface pressure of the sample when high-frequency bias power is applied to the sample during processing; acquiring the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on the status of control of the rear surface pressure of the sample when high-frequency bias power is not applied to the sample during processing; and estimating the self-bias voltage applied to the sample via the high-frequency bias power using the acquired forces of electrostatic chuck and the electrostatic chuck voltages corresponding to the forces of electrostatic chuck of both of the status of control when the high-frequency bias power is applied to the sample during processing and the status of control when the high-frequency bias power is not applied to the sample during processing.