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Electrolytic Etching of Tungsten

IP.com Disclosure Number: IPCOM000060079D
Original Publication Date: 1986-Feb-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Boatwright, B: AUTHOR [+2]

Abstract

This describes an electrolytic process to etch tungsten at very high yields. The high rate of dissolution minimizes the time that the tungsten comes in contact with the electrolytes. This results in minimum undercutting (under the photoresist).

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Electrolytic Etching of Tungsten

This describes an electrolytic process to etch tungsten at very high yields. The high rate of dissolution minimizes the time that the tungsten comes in contact with the electrolytes. This results in minimum undercutting (under the photoresist).

Etching tungsten consists of the following: - Laminate a solvent base photoresist of the Riston (E.I. du Pont de Nemours & Co.) or KBR (Eastman Kodak) type to a tungsten foil. - Expose and develop the area needed to form the tungsten electrodes. - Place the developed foil in an electrolytic cell consisting of the following: Sodium Hydroxide 3 Moles/Liter Sodium Nitrate 2 Moles/Liter Temperature 100-120 degrees F Current Density 50-100 Amps/Ft.2 Voltage 2-5 Volts Time 3-10 Minutes - Use a DC power supply or a rectifier to supply the current density. Attach the positive terminal to the tungsten foil and the negative terminal to an inert cathode, i.e., titanium or stainless steel. The power supply is then turned on and the above current density is passed until all the exposed tungsten is removed. - Remove the undeveloped photoresist using a suitable solvent recommended by the photoresist manufacturer.

Disclosed anonymously.

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