Use of beam profile reflectometry to determine depth of silicon etch damage and contamination

Karen A. Reinhardt; Susan M. Kelso

doi:10.1117/12.221192

18 September 1995 Use of beam profile reflectometry to determine depth of silicon etch damage and contamination

Karen A. Reinhardt, Susan M. Kelso

Proceedings Volume 2638, Optical Characterization Techniques for High-Performance Microelectronic Device Manufacturing II; (1995) https://doi.org/10.1117/12.221192
Event: Microelectronic Manufacturing '95, 1995, Austin, TX, United States

Abstract

Silicon lattice damage and contamination caused by plasma etching have been well documented. The typical techniques for measuring the silicon damage depth are TEM (transmission electron microscopy) and RBS (Rutherford back scattering). This paper shows that by using optical tecniques; BPR (beam profile relfectometry) and BPE (beam profile ellipsometry), accurate damage thickness can be obtained. Characterization of the silicon substrate damage and surface contamination leads to an understanding of the etch process. In this case, the LDD (lightly doped drain) spacer etch process is evaluated. This etch is used to form oxide spacers on the sidewall of the polygate, exposing the silicon substrate to the plasma after the oxide clears at the end of the etch step. The silicon must have minimal polymer on the surface and minimum silicon damage to assure reliable electronic devices. The silicon damage and polymeric surface contamination cuased by LDD spacer oxide etching on a split powered diode system is quantitatively analyzed. The thickness of the polymeric film and the damage layer are obtained by BPR and BPE. Results show damage to the silicon to be intensive, approximately 70 to 140 angstrom deep for the moderately damaged layer and approximately 160 to 360 angstrom for the lightly damaged layer. Comparison of the damage thickness obtained by BPR to the damage thickness obtained by TEM is performed. The correlation indicates that the technique of BPR provides a good measure of the actual damage layer thickness. The thickness of the polymer obtained by BPE is 50 to 80 angstrom which corresponds to the values obtained by TEM.

Citation Download Citation

Karen A. Reinhardt and Susan M. Kelso "Use of beam profile reflectometry to determine depth of silicon etch damage and contamination", Proc. SPIE 2638, Optical Characterization Techniques for High-Performance Microelectronic Device Manufacturing II, (18 September 1995); https://doi.org/10.1117/12.221192

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