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Process for Noble Metal Pattern Generation

IP.com Disclosure Number: IPCOM000080389D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Park, KC: AUTHOR [+2]

Abstract

A method has been provided for generating a noble metal pattern without employing specific etchants having the high-chemical reactivity needed to etch away the noble metal, yet not affect normal photoresists.

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Process for Noble Metal Pattern Generation

A method has been provided for generating a noble metal pattern without employing specific etchants having the high-chemical reactivity needed to etch away the noble metal, yet not affect normal photoresists.

The process involves the utilization of a thick anodized aluminum oxide film and the generation of a negative pattern on the oxide using a photoresist step, followed by deposition of the desired metal or alloy over the entire surface, wherein the last step comprises the etching of the aluminum oxide. The steps are numbered pictorially. Step (1) is the deposition of aluminum on a suitable substrate, followed by step (2) which consists of producing an aluminum oxide layer of several microns thick. The aluminum is anodized in an oxalic acid electrolyte consisting of 8 parts acid and 100 parts water, using a current density of 3.5mA/cm/2/.

A photoresist pattern is put on over the Al(2)O(3) at step 3 and an aluminum oxide etch, using a 20% NaOH solution, is used to leave a pattern of Al(2)O(3) (step 4). The photoresist may be removed with the etched Al(2)O(3) or left on through step 5. The desired metal or alloy is deposited over the pattern in step 5 and the final step of removing the Al(2)O(3) (step 6) takes place, using an Al(2)O(3) etch consisting of 34cc of 85% phosphoric acid and 30g of chromic acid per liter of H(2)0 at 85 degrees C. An equivalent Al(2)O(3) etch is a concentrated solution of NaOH. The desired meta...