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Proceedings Paper

Numerical prediction of etched profile in pyrolytic laser etching
Author(s): Teng Soon Wee; Yongfeng Lu; Wai Kin Chim
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Paper Abstract

A quasi-static 2D heat conduction analysis is used to deduce the geometrical profile of a cavity pyrolytically etched on an isotropic silicon substrate by a stationary CW Ar+ laser with a Gaussian intensity profile. Starting with a substrate having a flat surface, the analysis progressively removes regions of the substrate to model the actual etching action. The finite element method is used to solve the non- linear problem iteratively. Multiple reflections of the laser beam in the etched cavity are also modeled assuming that the substrate surface is perfectly diffused. Laser etching experiments performed on a silicon substrate in a CCl4 gas ambient are used to verify the numerical routine. Comparison with the numerical results indicates that the desorption of SiCl2 radicals is probably responsible for the final etched profile obtained. Deposition of the residue from the chemical etching was also observed in the etched cavity. The re-deposition was found to proceed in different manners for stationary and scanning beams. These differing actions of re-deposition are explained in the context of the different temperature distributions induced in the two cases.

Paper Details

Date Published: 18 August 1997
PDF: 10 pages
Proc. SPIE 3184, Microelectronic Packaging and Laser Processing, (18 August 1997); doi: 10.1117/12.280576
Show Author Affiliations
Teng Soon Wee, National Univ. of Singapore (Singapore)
Yongfeng Lu, National Univ. of Singapore (Singapore)
Wai Kin Chim, National Univ. of Singapore (Singapore)

Published in SPIE Proceedings Vol. 3184:
Microelectronic Packaging and Laser Processing
Yong Khim Swee; HongYu Zheng; Ray T. Chen, Editor(s)

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