International Business Machines Corporation

Thomas A Gunther

Brian H Desilets

John H Keller

Charles J Hendricks

William C Heybruck, Deceased

An improved plasma reactor for uniformly etching a large number of semiconductor wafers at a reduced plasma potential includes, in one embodiment, a grounded plate mounted intermediate the cathode and the top plate of a reactor chamber, the top plate and the chamber walls forming the reactor anode. The grounded plate is spaced apart from the chamber top plate a distance sufficient to allow a plasma to be established between the grounded plate and the top plate, and the distance between the grounded plate and the cathode is large enough not to disturb the field in the proximity of the wafers being etched. The plate can be apertured to facilitate etchant gas flow. According to another embodiment of the invention at least two grounded plates are employed, spaced apart from each other and from the upper surface of the reactor plasma chamber.

Plasma etching reactor with reduced plasma potential

A reactive ion etching chamber structure is designed to provide operation with uniformity in electric field and generated plasma so as to produce uniform, contaminant-free etching over large batches of silicon wafers. The anode chamber structure is cylindrical and physically symmetrical with respect to a round cathode plate with the internal surfaces of the chamber being free of any apertures, holes, recesses, or the like, having an opening dimension larger than one tenth the thickness of plasma 'dark space'. Under normal reactive ion etching conditions, such opening dimension is 1.5 mm or less and the distance between cathode and anode internal surface is 3.0 mm, or less.

Reactive ion etching chamber

As etching progresses from one layer of material to another in reactive ion etching systems, the partial pressures of the reaction chamber gas components change. In constant pressure reactive ion etching systems, changes in chamber pressure are corrected by changes in the etchant species flow rate into the reaction chamber. By monitoring flow rate, information is obtained which may be used to identify the points where partial pressures change, and latter may, in turn, be used to derive etching points in the material being etched.

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Hopewell Junction, NY, United States of America

Thomas A Gunther