Electrostatic chuck, support platform, and plasma processing apparatus

An electrostatic chuck for supporting a substrate and an edge ring including a first portion and a second portion, the electrostatic chuck comprising:

• a first region including a first top surface, the first region being configured to hold the substrate that is placed on the first top surface;
• a second region extending in a circumferential direction of the first region so as to surround the first region, the second region including a second top surface, and being configured to support the edge ring that is placed on the second top surface, the second region and first region being made of the same dielectric material, and the second portion of the edge ring being on the second top surface;
• an electrode provided in the second region;
• and
• an elastic sheet;
• wherein the first top surface and the second top surface extend along a single flat plane;
• a groove is provided between the first region and the second region;
• the first portion of the edge ring is accommodated in the groove so that the top surface of the first portion is below the lower surface of the second portion, the two portions being connected by an annular vertical wall;
• and
• the elastic sheet is disposed between the first portion of the edge ring and the electrostatic chuck.