The qualification of semiconductor surfaces is an important aspect of IC lechnology, from checking the quality of the substrate material right through to the dimensioning of the finished device. Etching the surface of the substrate reveals details concerning chemical and crystal defects. Surface roughness measurements are required before preparing epitaxial layers and device processing. The height, width and shape of component features need to be checked throughout the device processing stage. In this paper we describe a three dimensional NDT optical profiler we have developed for the nanometrology of semiconductor surfaces. The system is based on interference microscopy, using phase stepping for automatic fringe analysis. Illumination is by high intensity LED or white light and detection is by a CCD camera. A vertical resolution of mm is achieved, with the lateral resolution being better than O.5i.m. Comparison of a two dimensional profile of a chemically etched surface using PSM with that obtained by a stylus profiler are within 10% agreement. Results are shown of three dimensional profiles of chemically etched InP and an MOCVD grown epitaxial layer, surface roughness of polished InP, and profiles of a recess in a combined laser/photodiode device.

Date Published: 1 January 1991
PDF: 10 pages
Proc. SPIE 1332, Optical Testing and Metrology III: Recent Advances in Industrial Optical Inspection, (1 January 1991); doi: 10.1117/12.51100

Published in SPIE Proceedings Vol. 1332:
Optical Testing and Metrology III: Recent Advances in Industrial Optical Inspection
Chander Prakash Grover, Editor(s)