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Micro-Ellipsometric Measurements of Strained Layer Structures

Published online by Cambridge University Press:  25 February 2011

Yi-Ming Xiong  and
Paul G. Snyder
Yi-Ming Xiong
Affiliation:
University of Nebraska, Center for Microelectronic and Optical Materials Research, and Dept. of Electrical Engineering, Lincoln, NE 68588-0511
Paul G. Snyder
Affiliation:
University of Nebraska, Center for Microelectronic and Optical Materials Research, and Dept. of Electrical Engineering, Lincoln, NE 68588-0511
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Abstract

Ellipsometric measurements are extremely sensitive (on the monolayer scale) to layer thicknesses and surface or interfacial roughness. However, lateral resolution is poor, because of the need for a highly collimated ( ≤0.05° ) and therefore large diameter (typically 1 mm) optical beam. Many materials are inhomogeneous on a smaller lateral scale, in which case conventional ellipsometry simply measures some average value. Focusing the beam leads, for an incoherent light source, to an uncollimated beam and a consequential spread in the angle of incidence, which in turn degrades the sensitivity. We describe here a technique for focusing a coherent, Gaussian laser beam to a minimum spot size of about 30μm × 130μm, while maintaining a negligible effective spread in angle of incidence. The technique was used to measure semi-insulating (S.I.) GaAs, laser annealed ion implanted GaAs, and InI Ga1−xAs strained layer structures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 216: Symposium T – Long-Wavelength Semiconductor Devices, Materials and Processes , 1990 , 483
Copyright
Copyright © Materials Research Society 1991

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References

REFERENCES

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