Adjustable electrode plasma processing chamber

Abstract

A plasma processing chamber incorporating parallel plate electrodes whose separation may be mechanically adjusted from the outside thereof. The chamber includes a sealable assembly including an electrode housing and a reaction chamber body. The body includes an aperture to receive a planar surfaced terminal end of the housing. The aperture is constructed to permit the housing to be easily translated with respect to the body. One electrode surface of the chamber is established on the end of the housing thus received. The other electrode is provided by a corresponding surface within the body. Entry of atmospheric gases into the space between the electrode's surfaces is barred by a sliding, dual, differentially pumped seal between the housing's surface and the aperture's surface. Also incorporated into the processing chamber are four jackscrews aligned parallel to the axis of the housing. These jackscrews, arranged to form a square about the housing, are interposed between the body and a flange projecting radially outward from the housing's terminal end furthest from the body. Synchronous rotation of these jackscrews, provided by a continuous, closed chain passing around sprockets secured to each of the jackscrews, moves the housing with respect to the body thereby altering the electrode's separation. A potentiometer, also driven in synchronism with the jackscrews, permits remote, electronic sensing of electrode spacing.