Abstract: Provided is an apparatus for processing a substrate using plasma, in which an etching rate can be controlled using an insulation plate provided with an air-gap. The substrate processing apparatus includes a chamber including a processing space for processing a substrate using plasma, and a support module located in the processing space and for supporting the substrate, wherein the support module includes a support plate for receiving high frequency power and a first surface disposed under the support plate and facing the support plate, and at least one first recess is formed on the first surface.