PLASMA PROCESSING APPARATUS

摘要

A plasma processing apparatus performs a stable and accurate matching operation with high reproducibility in a power modulation process of modulating of a high frequency power to be supplied into a processing vessel in a pulse shape. In the plasma processing apparatus, an impedance sensor 96A provided in a matching device performs a dual sampling averaging process on a RF voltage measurement value and an electric current measurement value respectively obtained from a RF voltage detector 100A of a voltage sensor system and a RF electric current detector 108A of an electric current sensor system by sampling-average-value calculating circuits 104A and 112A and by moving-average-value calculating circuits 106A and 114A. Thus, an update speed of a load impedance measurement value outputted from the impedance sensor 96A can be matched well with a driving control speed of a motor in a matching controller.

主权项

1. A plasma processing apparatus of generating plasma by high frequency discharge of a processing gas between a first electrode and a second electrode which are provided to face each other within an evacuable processing vessel that accommodates therein a substrate to be processed, which is loaded into and unloaded from the processing vessel, and performing a process on the substrate held on the first electrode under the plasma, the plasma processing apparatus comprising:
a first high frequency power supply configured to output a first high frequency power having a frequency suitable for ion attraction into the substrate on the first electrode from the plasma; a first high frequency transmission line configured to transmit the first high frequency power outputted from the first high frequency power supply to the first electrode; a first matching device configured to match impedance on the side of the first high frequency power supply with load impedance on the first high frequency transmission line; a second high frequency power supply configured to output a second high frequency power having a frequency suitable for plasma generation; a second high frequency transmission line configured to transmit the second high frequency power outputted from the second high frequency power supply to any one of the first electrode and the second electrode; a second matching device configured to match impedance on the side of the second high frequency power supply with load impedance on the second high frequency transmission line; and a high frequency power modulation unit configured to control the second high frequency power supply such that a first period during which the second high frequency power is on or has a first level and a second period during which the second high frequency power is off or has a second level lower than the first level is alternately repeated at a predetermined pulse frequency, wherein the first matching device includes: a matching circuit having a variable reactance element provided on the first high frequency transmission line; a sampling-average-value calculating circuit configured to sample voltage detection signals and electric current detection signals corresponding to the first high frequency power on the first high frequency supply line with a preset sampling frequency and calculate an average value of these signals during a first monitoring time set for both of the first period and the second period in each cycle of the pulse frequency; a moving-average-value calculating circuit configured to calculate a moving average value of the voltage detection signals and the electric current detection signals based on an average value obtained from the sampling-average-value calculating circuit in each cycle; a load impedance-measurement-value calculating circuit configured to calculate a measurement value of the load impedance with respect to the first high frequency power supply based on the moving average value of the voltage detection signals and the electric current detection signals obtained from the moving-average-value calculating circuit; and a matching controller configured to vary a reactance of the variable reactance element such that the measurement value of the load impedance obtained from the load impedance-measurement-value calculating circuit is equal or approximate to a preset matching point corresponding to impedance on the side of the first high frequency power supply.