| CPC H01J 9/02 (2013.01) [H01J 37/32541 (2013.01)] | 18 Claims |

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1. A method of manufacturing an electrode plate for a plasma processing apparatus for forming a plurality of gas holes having a straight portion exceeding 12 mm in length in a thickness direction of an electrode plate main body in a penetrating state and in parallel to each other, the method comprising:
a prepared hole forming step of forming a prepared hole with a diameter of 50% or more and 80% or less of a diameter of a hole forming the straight portion with a first drill from one surface of the electrode plate main body; and
a straight portion forming step of forming the straight portion to overlap the prepared hole with a second drill,
wherein the electrode plate main body consists of single crystal silicon, columnar crystal silicon, or polycrystalline silicon,
a diameter of the second drill is larger than a diameter of the first drill, and
the straight portion forming step is conducted after the prepared hole forming step.
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