Patent ID: 8038833

Claim:
A plasma processing apparatus comprising: a processing vessel for providing a depressurized space for performing a plasma processing on a substrate to be processed; a first electrode disposed in the processing vessel; a processing gas supply unit for supplying a processing gas into the processing vessel; a high frequency power supply for generating a high frequency voltage for forming a plasma; a high frequency feeding conductor connected to the first electrode for supplying the high frequency voltage from the high frequency power supply to the first electrode; a DC potential measurement unit for non-contactly measuring an electrostatic surface potential of the high frequency feeding conductor by using electrostatic capacitance to obtain the DC potential, and a matching unit for performing an impedance matching between the high frequency power supply side and a load side, the matching unit having an input terminal electrically coupled to the high frequency power supply and an output terminal electrically coupled to the high frequency feeding conductor, wherein the matching unit is installed outside the processing vessel, and the high frequency feeding conductor between the matching unit and the processing vessel is surrounded with a cylindrical conductor connected to a ground potential, wherein the high frequency feeding conductor includes a joint piece detachably connecting the high frequency feeding conductor together via a connecting part, wherein the cylindrical conductor includes a first cylindrical conductor portion whose one end is coupled to the processing vessel, a second cylindrical conductor portion whose one end is coupled to the matching unit, and a first connecting part including a pair of semi-cylindrical connecting parts for attachably and detachably connecting the other ends of the first and the second cylindrical conductor portion with each other, and wherein a probe of the DC potential measurement unit is installed in the first connecting part in a vicinity of the joint piece.