Numerical prediction of etched profile in pyrolytic laser etching

T. S. Wee, Y. F. Lu, W. K. Chim

Research output: Contribution to journalConference articlepeer-review


A quasi-static two-dimensional 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.

Original languageEnglish (US)
Pages (from-to)211-220
Number of pages10
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 1997
Externally publishedYes
EventMicroelectronic Packaging and Laser Processing - Singapore, Singapore
Duration: Jun 25 1997Jun 25 1997


  • Carbon tetrachloride
  • Diffused reflection
  • Finite element method
  • Heat conduction analysis
  • Laser etched profile
  • Laser induced temperature profile
  • Numerical laser etching model
  • Pyrolytic laser etching
  • Silicon

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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