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Depositing Rhodium Patterns

IP.com Disclosure Number: IPCOM000078850D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Newcomb, DA: AUTHOR

Abstract

Deposited patterns of rhodium film are desirable where considerations of both wear and conductivity exist. The deposition of patterns of rhodium film can be difficult. Etching rhodium is not desirable as etchants for rhodium are very difficult to work with, and as they also attack other metals which may be present. Depositing rhodium in a pattern by electroplating through a photoresist mask is not feasible, because the rhodium plating bath causes the photoresist to break down and contaminate the plating solution. Vacuum deposition of rhodium through a mask directly on a substrate, results in deposited films which have high-internal stress.

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Depositing Rhodium Patterns

Deposited patterns of rhodium film are desirable where considerations of both wear and conductivity exist. The deposition of patterns of rhodium film can be difficult. Etching rhodium is not desirable as etchants for rhodium are very difficult to work with, and as they also attack other metals which may be present. Depositing rhodium in a pattern by electroplating through a photoresist mask is not feasible, because the rhodium plating bath causes the photoresist to break down and contaminate the plating solution. Vacuum deposition of rhodium through a mask directly on a substrate, results in deposited films which have high-internal stress.

A series of steps for depositing rhodium patterns, which avoids these problems, is shown. The nonconductive substrate is cleaned and then vacuum coated, in succession, with titanium, copper and chromium. The titanium provides adhesion, the copper provides a conductive layer, and the chromium serves as a masking layer. Subsequently, the chromium layer is coated with photoresist, exposed to pattern, and portions of the photoresist corresponding to the pattern removed to expose corresponding portions of the chromium layer. Chromium etchants are then applied through the photoresist, removing unprotected portions of chromium and exposing the subjacent copper layer. Following this etching operation, the balance of the photoresist is removed from the surface of the remaining chromium. Then, using the remaining chromium layer as a plating mask, rhodium is electrodeposited onto the exposed copper surfaces. Rhodium does not tend to deposit on the chromium due to its high- electrical resistance. Subsequently, chromium, copper and titanium, not protec...