Plasma processing apparatus and plasma processing method

A plasma processing method for performing a plasma process on a substrate in a plasma processing apparatus which includes a mounting table for mounting thereon the substrate and a focus ring provided on the mounting table so as to surround the substrate,

• wherein the focus ring includes a dielectric ring provided so as to surround a substrate mounting portion of the mounting table and a conductive ring provided on the dielectric ring,
• the conductive ring includes an outer ring and an inner ring as separate bodies, the outer ring being provided so as to surround a peripheral portion of the substrate and having a top surface higher than the substrate mounted on the substrate mounting portion, and the inner ring being spaced apart inwardly from the outer ring so as to be positioned under the peripheral portion of the substrate and having a top surface lower than the substrate, and
• the outer ring and the inner ring are connected with a DC power supply for the outer ring and a DC power supply for the inner ring, respectively, and the outer ring is connected with a voltage sensor for detecting a floating voltage thereof,
• further wherein the plasma processing method comprises:
• obtaining an optimum application voltage value to be applied to the outer ring based on a floating voltage of the outer ring detected by the voltage sensor and an optimum application voltage value to be applied to the inner ring, and storing the obtained optimum application voltage values in a storage;
• when a plasma process is performed, detecting a floating voltage of the outer ring by the voltage sensor for each plasma process, obtaining a variation in the floating voltage, and adjusting the optimum application voltage value of the outer ring stored in the storage based on the variation in the floating voltage;
• and
• performing the plasma process on the substrate by applying a voltage corresponding to the adjusted optimum application voltage value of the outer ring to the outer ring from the DC power supply for the outer ring and by applying a voltage corresponding to the optimum application voltage value of the inner ring stored in the storage to the inner ring from the DC power supply for the inner ring.

A plasma processing apparatus for performing a plasma process on a substrate mounted on a mounting table, the apparatus comprising:

• a focus ring which includes a dielectric ring provided so as to surround a substrate mounting portion of the mounting table and a conductive ring provided on the dielectric ring and having an outer ring and an inner ring as one body;
• a voltage sensor configured to detect a floating voltage of the conductive ring;
• a DC power supply configured to apply a DC voltage to the conductive ring;
• a storage configured to store therein an optimum application voltage value to be applied to the conductive ring, the optimum application voltage value being obtained based on the floating voltage of the conductive ring detected by the voltage sensor;
• and
• a controller configured to detect a floating voltage of the conductive ring by the voltage sensor for each plasma process when a plasma process is performed, to obtain a variation in the floating voltage, to adjust the optimum application voltage value stored in the storage based on the variation in the floating voltage, and to perform the plasma process on the substrate by applying a voltage corresponding to the adjusted optimum application voltage value to the conductive ring from the DC power supply,
• wherein the outer ring is provided so as to surround a peripheral portion of the substrate and has a top surface higher than the substrate mounted on the substrate mounting portion, and
• the inner ring is extended inwardly from the outer ring so as to be positioned under the peripheral portion of the substrate and has a top surface lower than the substrate.