APPARATUS AND METHOD FOR DETERMINING POWER IN PLASMA PROCESSING

Assignee

ASSOCIATED INSTITUTIONS FOR MEDICAL SCIENCES, INC.

Filed

Jun 23, 1992

Granted

Dec 28, 1993

Location

HOLLAND PA US

Abstract

An apparatus and method including a current sensor having a radiation emitter, such as an electrical resistor, and a radiation detector, such as an infrared detector, for sensing current flowing to a plasma generating electrode from a radio frequency (RF) power source. The resistor may include a high emissivity infrared coating to enhance efficiency of the current sensor. The infrared detector provides a highly accurate indication of the average or root-mean-square current delivered to the plasma generating electrode without introducing parasitic capacitance into the measurement, or sensing, circuit. A voltage sensor and a second current sensor, such as a torroidal current sensor, provide the voltage and phase angle of the current delivered to the plasma generating electrode to thereby permit calculation of the power delivered to the plasma generating electrode. A processor controls the RF source responsive to the sensed average current, sensed voltage, and sensed phase angle of the current.

Source: Google Patents