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Browse Prior Art Database

Electroplating Fixture With Efficient Uniformity Control

IP.com Disclosure Number: IPCOM000044070D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Chesnutt, RB: AUTHOR [+3]

Abstract

This invention provides a more efficient method of controlling uniformity across the cathode in electroplating. When electroplating solution seeps past the parts of certain types of cathodes, metal can be deposited on the inner surfaces of the cathode, causing poor thickness uniformity. Also, the normal current distribution due to pattern geometry creates areas of high and low density across the cathode, causing further lack of uniformity. To eliminate these problems, a new cathode has been designed and used in the electrodeposition of metals and alloys. It consists of a nonconductive cathode body placed between a thin metal overly and a plexiglas back plate (see figure). To gain proper deposit uniformity, it is necessary to electrodeposit around the parts on the cathode surface.

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Electroplating Fixture With Efficient Uniformity Control

This invention provides a more efficient method of controlling uniformity across the cathode in electroplating. When electroplating solution seeps past the parts of certain types of cathodes, metal can be deposited on the inner surfaces of the cathode, causing poor thickness uniformity. Also, the normal current distribution due to pattern geometry creates areas of high and low density across the cathode, causing further lack of uniformity. To eliminate these problems, a new cathode has been designed and used in the electrodeposition of metals and alloys. It consists of a nonconductive cathode body placed between a thin metal overly and a plexiglas back plate (see figure). To gain proper deposit uniformity, it is necessary to electrodeposit around the parts on the cathode surface. Due to machining and rework processes for standard solid metal cathodes, the parts are usually located a minimum of .03 inch below the cathode surface. In this overlay design, the distance is reduced to .01 inch or less, allowing the formation of a more uniform diffusion layer. This results in better thickness and compositional uniformity as well as a reduced distance between the cathode surface and the parts. The overlay pattern can also be adjusted to influence current distribution. Cathodes based on this invention have been used to plate metal masks with a "reverse" plating thickness ramp. In other words, areas expected to be hi...