Method and apparatus for plasma processing

An optimization design method for optimizing a configuration of a focus ring and a processing stage applied to a plasma processing apparatus for plasma processing an object to be processed, the plasma processing apparatus including the processing stage for placing the object to be processed, the focus ring, and a RF power supply for applying RF bias to the object to be processed and to the focus ring, with the focus ring being disposed on the processing stage and surrounding the object to be processed, the method comprising:

• acquiring a voltage and a sheath height on a surface of the object to be processed and a voltage and a sheath height on a surface of the focus ring by an equivalent circuit analysis;
• performing a two dimensional plasma analysis and a two dimensional electric field analysis, based on the result of the equivalent circuit analysis;
• and
• optimizing the configuration of the focus ring and the processing stage, based on results of the two dimensional plasma analysis and the two dimensional electric field analysis, and based on a plasma-sheath interface flattening condition for making a first voltage drop of an RF voltage from the processing stage to a plasma-sheath interface above the object to be processed equal to a second voltage drop of an RF voltage from the processing stage to a plasma-sheath interface above the focus ring, and for making a sum of a surface height of the object to be processed and a sheath height of the surface of the object to be processed equal to a sum of a surface height of the focus ring and the sheath height of the surface of the focus ring,
• wherein the first voltage drop is calculated on the basis of a voltage on a surface of the object to be processed, and
• wherein the second voltage drop is calculated on the basis of a voltage on a surface of the focus ring.