base

Abstract

This invention provides a base for stably holding a wafer. The base includes a plate-shaped ceramic plate having a first main surface and a second main surface. A first support wall extending circumferentially along the first main surface is provided on the ceramic plate. The wafer is placed on the first support wall. An electrostatic chuck electrode for attracting the wafer by electrostatic force is provided within the ceramic plate. The electrostatic chuck electrode has a positive electrode for applying a positive voltage and a negative electrode for applying a negative voltage. The positive electrode includes a first positive electrode portion, which, when viewed from a direction perpendicular to the first main surface, coincides with a portion of the annular region on the first main surface where the first support wall is provided. The negative electrode includes a first negative electrode portion, which, when viewed from a direction perpendicular to the first main surface, coincides with a portion of the annular region. A plurality of first positive electrode portions and a plurality of first negative electrode portions are alternately arranged along the circumferential direction of the ceramic plate.

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