Patent ID: 7534362
Filing Date: 2009-05-19
Classification: H01J

Abstract:
1. A method for improving process uniformity in a etching or substrate cleaning reactor utilizing an rf discharge between substantially parallel plates, one of which is a showerhead with a primary internal gas reservoir, greater in area and corresponding in shape to the substrate and connected to the plasma region adjacent the substrate by small holes, for processing large non-circular substrates, comprising the steps of: providing a rate adjustment gas or gas mixture, through openings in a manifold or manifolds disposed within the edge and/or corner regions of the reservoir, for improving the spatial uniformity of the process, introduced by separate controllable means into the edge and/or corner regions of the showerhead reservoir in addition to a main process gas or mixture introduced into that same reservoir so that the rate adjustment gas or gas mixture combines and mixes with the main process gas or gas mixture within the reservoir in the showerhead, having higher concentration in the edge and corner regions therein, and the combined gases flow into the plasma discharge between showerhead and substrate: the rate adjustment gas or gas mixture fed into the plasma causing an increase or decrease of the processing rate on the substrate roughly proportional to the local concentration of said adjustment gas or gas mixture coming into the plasma; and preferentially increasing the processing rate in the regions of the substrate corresponding to those locations within the showerhead where the adjustment gas or mixture is preferentially introduced.