Patent ID: 9627181
Date: 2017-04-18
CPC Classifications: H01J

Claim:
1. A plasma processing apparatus, comprising: a processing chamber having a dielectric window; a substrate holding unit for holding thereon a processing target substrate within the processing chamber; a processing gas supply unit configured to supply a processing gas into the processing chamber in order to perform a plasma process on the substrate; a RF antenna provided outside the dielectric window in order to generate plasma of the processing gas within the processing chamber by inductive coupling; and a high frequency power supply unit configured to supply a high frequency power having a frequency for generating a high frequency electric discharge of the processing gas, wherein the RF antenna includes only three coils consisting of an inner coil, an intermediate coil and an outer coil with gaps therebetween in a radial direction, the inner coil includes a single inner coil segment or more than one inner coil segments connected in series and disposed in a plane, the intermediate coil includes a plurality of intermediate coil segments separated in a circumferential direction and electrically connected with each other in parallel and disposed in said plane, and the outer coil includes a multiplicity of outer coil segments separated in a circumferential direction and electrically connected with each other in parallel and disposed in said plane, and wherein a variable intermediate capacitor is electrically connected with the plurality of intermediate coil segments in series between a first node on the side of the high frequency power supply unit and a second node on a ground potential side, a variable outer capacitor is electrically connected with the multiplicity of outer coil segments in series between the first and second nodes, the numbers of the intermediate coil segments and the numbers of the outer coil segments are selected independently, and connection conductors upwardly extending from the RF antenna are connected to each other in horizontal directions while spaced apart from the dielectric window at a predetermined distance to reduce electromagnetic influence upon the inner, intermediate and outer coils, when high frequency power transmission lines are extended continuously from the first node to the second node, a winding direction of the intermediate coil on the high frequency power transmission line is opposite to winding directions of the inner coil and the outer coil on the high frequency power transmission lines in the circumferential direction, the variable intermediate capacitor has an electrostatic capacitance having a range in which a combined reactance of the plurality of intermediate coil segments and the variable intermediate capacitor has a negative value, an output side common capacitor between the second node and an earth line is electrically connected in series to the inner, intermediate and outer coil segments such that the variable intermediate capacitor, the variable outer capacitor and the output side common capacitor are directly connected to second node, and the inner coil, the intermediate coil and the outer coil are electrically connected with each other in parallel between the first and second nodes.