Ceramic foam for helium light-up suppression

A method of assembling an electrostatic chuck (ESC), comprising:

• providing a dielectric block having an upper surface for interfacing with a substrate support surface and a lower surface for interfacing with a baseplate, the dielectric block including a plurality of plug channels extending from the lower surface of the dielectric block to the upper surface of the dielectric block, each plug channel having a plug region;
• inserting a ceramic foam plug into the plug region of each plug channel, the ceramic foam plug having a body and a pre-formed pore matrix that is integrally distributed throughout the body;
• mating the lower surface of the dielectric block with an upper surface of the baseplate while the plurality of plug channels of the dielectric block is aligned with a respective plurality of gas distribution channels of the baseplate such that when gas flows out of the plurality of gas distribution channels, the gas flows into the respective ceramic foam plugs as inserted into the plurality of plug channels;
• applying, prior to said inserting, a bonding material between an inner wall of the plug region of the plug channel and an outer surface of the ceramic foam plug for securing the ceramic foam plug to the plug region of the plug channel.

An electrostatic chuck (ESC), comprising:

• a substrate support surface with a plurality of minimum contact area (MCA) pads for supporting a substrate;
• a dielectric block having an upper surface that interfaces with the substrate support surface and a lower surface for interfacing with a baseplate, the dielectric block includes a plurality of plug channels extending from the lower surface of the dielectric block to the upper surface of the dielectric block and through holes in the substrate support surface, wherein the plurality of plug channels is configured to introduce thermal conductance gas through the dielectric block to a temperature conduction region between the substrate support surface and a lower surface of the substrate when present;
• a plurality of ceramic foam plugs inserted into respective plug regions of the plurality of plug channels, each ceramic foam plug having a body and a pre-formed pore matrix that is integrally distributed throughout the body;
• and
• the baseplate including a plurality of gas distribution channels for supplying thermal conductance gas into the plurality of ceramic foam plugs, an upper surface of the baseplate interfacing with the lower surface of the dielectric block such that the plurality of gas distribution channels are aligned respectively with the plurality of ceramic foam plugs;
• wherein the ceramic foam plugs enable suppression of light-up of the thermal conductance gas when the thermal conductance gas flows through the dielectric block into the temperature conduction region when the ESC is subject to an electric field during a plasma processing procedure, the pre-formed pore matrix causing a reduction of a mean free path of the thermal conductance gas for said suppression of light-up when the thermal conductance gas is made to flow through the plurality of ceramic foam plugs.