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Gas Recirculator for Debris Removal in Laser Etching Processes

IP.com Disclosure Number: IPCOM000061842D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Ho, F: AUTHOR [+2]

Abstract

The present apparatus greatly reduces debris build-up on optical windows in laser-assisted metal etching processes by flowing a recirculating mixture of a high pressure inert buffer gas with the etching gas over the window and into a filter to trap the debris. One of the major problems of laser-assisted chemical etching of metals is the glass window contamination caused by the reaction product deposition. In the etching process, a reactive gas, such as CP2, is used, and the pressure of the reactive gas is kept low to minimize the optical absorption of the laser beam by the gas. The reacted material, which is ablated by the laser, suffers few collisions with the gas molecules and therefore quickly deposits on the glass window surface.

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Gas Recirculator for Debris Removal in Laser Etching Processes

The present apparatus greatly reduces debris build-up on optical windows in laser-assisted metal etching processes by flowing a recirculating mixture of a high pressure inert buffer gas with the etching gas over the window and into a filter to trap the debris. One of the major problems of laser-assisted chemical etching of metals is the glass window contamination caused by the reaction product deposition. In the etching process, a reactive gas, such as CP2, is used, and the pressure of the reactive gas is kept low to minimize the optical absorption of the laser beam by the gas. The reacted material, which is ablated by the laser, suffers few collisions with the gas molecules and therefore quickly deposits on the glass window surface. The deposit accumulates during the etching process and causes substantial laser energy loss due to optical absorption in the deposit. The present apparatus adapted for reducing window contamination is shown in the figure. In this arrangement, the total gas pressure in the reaction chamber 10 is increased by adding a chemically inert and laser- light-transparent buffer gas to the low pressure etch gas. This greatly reduces the deposition rate of the etch product on the glass window 12 by increasing the number of collisions between gas molecules and the ablated debris. The gas mixture is also circulated over the window 12 by a pumping device, comprising a motor 14 and a fan 16, combined with a filter 18. The debris is theref...