DIFFUSER PLATE WITH SLIT VALVE COMPENSATION

摘要

A diffusion plate having a slit valve compensation tool is provided to control a shape and/or size of a hollow cathode cavity so as to be most adjacent to a slit value, thereby improving uniformity of a thickness of a film formed on a substrate and uniformity of plasma distribution over the whole processing chamber. A gas distribution plate assembly comprises a diffusing plate device(200) and a plurality of gas passages(208a-208c). The diffusing plate device comprises an upstream side, a downstream side, a first edge arranged to be adjacent to a slit valve, a central part and a second edge. The gas passage passes through between the upstream side and downstream side. The plural gas passes comprise the followings. A first gas passage(208a) has a first hollow cathode cavity(214a) adjacently arranged in the first edge of the diffusing plate device. A second gas passage(208b) has a second hollow cathode cavity(214b) adjacently arranged in the central part of the diffusing plate device. A third gas passage(208c) has a third hollow cathode cavity(214c) adjacently arranged in the second edge. The first hollow cathode cavity, the second hollow cathode cavity and the third hollow cathode cavity has different volumes.