Western Electric Company, Inc.

At&t Technologies, Inc.

At&t Bell Laboratories

Duane E Bacon

Spencer S Hecox

J David Gattermeir

Paul A Kohl

Jeffrey R Bessette

Bonnie J Hrivnak

John J Robb

Photoelectrochemical processing of semiconductors is highly desirable because of its versatility and simplicity. The invention is a photoelectrochemical etching procedure for n-type silicon in which an alcohol based solution of hydrofluoric acid is used as the electrolyte. This procedure is useful for the fabrication of a variety of silicon devices.

Photoelectrochemical etching of n-type silicon

An article, such as a semiconductor wafer (31), is selectively electrolytically plated to form metal deposits, such as contacts (26), adjacent to anodes of diode regions within such wafer by mounting the wafer in a plating chamber (36) opposite first and second electrodes (61 and 62), filling the chamber (36) with a metal plating electrolyte (49) and applying alternatingly plating pulses between the wafer (31) and the first electrode (61) and deplating pulses between the wafer (31) and the second electrode (62). The plating pulses are current controlled yielding a predetermined total plating current. The deplating pulses are voltage controlled yielding a deplating current which tends to subside in the course of the plating operation. The electrolyte in the chamber is agitated by streams of electrolyte pumped at a comparatively high rate toward the wafer (31) to break down surface layers of electrolyte adjacent to the wafer.

Methods of and apparatus for electroplating preselected surface regions

An edge surface (18) of an article (16) is treated in a fluid (52) with a minimum effect on other adjacent side surfaces of the article by contacting the edge surface to the surface of the fluid such that the fluid wets the side surfaces and forms a meniscus adjacent to each of the side surfaces. In the meniscus the fluid stagnates and quickly becomes an inactive barrier which shields the side surfaces of the article, while the edge surface of the article remains exposed for the duration of the treatment to the active bulk of the fluid.

Selectively treating an article

A cylindrical surface of an article is electrolytically treated with a controlled, cross-sectional distribution of the electrolytic action. The distribution is achieved by placing the surface at a predetermined distance from a formed electrode to control the influence of the electrode on each portion of the surface along a cross section thereof. The influence on each such portion with respect to other portions of the surface is determined by the magnitude of an influence number associated with such portion in relation to the magnitude of similar influence numbers associated with the other surface portions along the cross section.

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Lee's Summit, MO, United States of America

Duane E Bacon