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High Resolution Molybdenum Masks by Laser Etching

IP.com Disclosure Number: IPCOM000062022D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Koren, G: AUTHOR [+2]

Abstract

Thin Molybdenum (Mo) masks are used as templates through which metal paste is screened onto ceramic green sheets to form conducting lines after lamination and sintering. In forming t masks, the conventional wet lithographic processes can only make lines as small as 3 mils wide. The process described here is a simple dry process which can easily produce slots 1 mil wide in 2 mil Mo sheet. These slots can be separated by as little as 3 mils. The physical effect used in forming these masks is the laser burning of Mo metal in air. This article describes the application of that physical effect to the problem of Mo mask manufacture and repair.

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High Resolution Molybdenum Masks by Laser Etching

Thin Molybdenum (Mo) masks are used as templates through which metal paste is screened onto ceramic green sheets to form conducting lines after lamination and sintering. In forming t masks, the conventional wet lithographic processes can only make lines as small as 3 mils wide. The process described here is a simple dry process which can easily produce slots 1 mil wide in 2 mil Mo sheet. These slots can be separated by as little as 3 mils. The physical effect used in forming these masks is the laser burning of Mo metal in air. This article describes the application of that physical effect to the problem of Mo mask manufacture and repair.

The process is as follows: The Mo foil (2 mils thick) is held on a computer driven x - y stage in air in the focal plane of a focussed Ar ion laser operated on all lasing lines or another suitable laser (e.g., Nd:YAG). Local laser heating with about 5 - 10W power induces the oxidation of Mo to MoO3 which is volatile at the elevated sample temperatures. The MoO3 vaporizes and can be collected on a cold surface away from the sample by a moving gas stream. In this process, the Mo metal is not melted and very smooth edge profiles are formed. The mechanism is really laser assisted chemical oxidation of Mo and thermal evaporation of the reaction product. Features as small as 10 microns can be etched through 2 mil Mo sheets and typical results for 1 - 2 mil wide slots can be etched with...