US Patent 9947517 Adjustable extended electrode for edge uniformity control

Embodiments described herein generally related to a substrate processing apparatus. In one embodiment, a process kit for a substrate processing chamber disclosed herein. The process kit includes a first ring having a top surface and a bottom surface, an adjustable tuning ring having a top surface and a bottom surface, and an actuating mechanism. The bottom surface is supported by a substrate support member. The bottom surface at least partially extends beneath a substrate supported by the substrate support member. The adjustable tuning ring is positioned beneath the first ring. The top surface of the adjustable tuning ring and the first ring define an adjustable gap. The actuating mechanism is interfaced with the bottom surface of the adjustable tuning ring. The actuating mechanism is configured to alter the adjustable gap defined between the bottom surface of the first ring and the top surface of the adjustable tuning ring.