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Photochemical Etching of Metals With Chloro-brominated Methane Gases

IP.com Disclosure Number: IPCOM000061417D
Original Publication Date: 1986-Jun-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chuang, TJ: AUTHOR [+2]

Abstract

Interest in laser-induced etching of metals has intensified recently. We have performed such photochemical etching by photolyzing CCl3Br at copper and chromium surfaces to yield bromine atoms and CCl3 radicals, and found very high metal etch rates.

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Photochemical Etching of Metals With Chloro-brominated Methane Gases

Interest in laser-induced etching of metals has intensified recently. We have performed such photochemical etching by photolyzing CCl3Br at copper and chromium surfaces to yield bromine atoms and CCl3 radicals, and found very high metal etch rates.

Bromotrichloromethane is inert towards copper surfaces, in contrast to halogen gases. It is known to produce Br and CCl3 upon uv photolysis. Examination of the uv spectrum of commercially available liquid reveals that the optimal wavelength for the photolysis is 278 nm. We have succeeded in etching copper with the partially focused output of both a xenon chloride excimer laser (308 nm) and a krypton fluoride excimer laser (248 nm). Our observed etch rate at 308 nm is approximately 20 angstroms per pulse at a fluence of 0.25 J/cm2, whereas at 248 nm we have observed etching completely through five micrometers of copper in 500 pulses (100 angstroms/pulse). These rates are quite high for a surface photochemical process (chlorine etching, which features reactive diffusion of the etchant into the bulk metal, can proceed at up to 200 angstroms/pulse). A copper substrate was etched through a molybdenum mask at 308 nm to a depth of about 4.5 mm. A similar sample was etched completely through (5 mm) in 25s at 25 Hz using 248 nm light. The fluence in both cases was 250-300 mJ/cm2 . In contrast to halogen gases such as chlorine and bromine, photochemical etching...