Spectroscopic ellipsometry has long been recognized as a powerful technique for nondestructive characterization of thin films and multilayer structures. In the case of photolithography it has been intensively used for layer thickness and optical index determinations. Nevertheless, the main drawback of this technique is that it is not direct. The data analysis must be made adjusting a prior optical models on the experimental data. For photolithographic films, it is sometimes difficult to find accurate structural model and the analysis becomes difficult when the film is absorbent in the entire wavelength range. It is why SOPRA has developed recently a new versatile instrument that integrates different experimental techniques. The base is the SOPRA GESP5 instrument which offers already the possibility to perform spectroscopic ellipsometry, spectroscopic photometry and scatterometry. We have added a grazing x-ray reflectometer option, which allows measurements on the same spot at the same time, and combine analysis of the different data. The source is a compact ceramic Cu fine focus x-ray tube. the x-ray beam is defined by Soller Slits and a parallel interchangeable slits. After reflection on the sample surface, the beam is monochromatized using a curve graphite crystal and focused on the detector. This new system is discussed in details hereafter and characterization of antireflective for microlithography is presented.

Date Published: 28 April 1999
PDF: 11 pages
Proc. SPIE 3741, Lithography for Semiconductor Manufacturing, (28 April 1999); doi: 10.1117/12.346881

Published in SPIE Proceedings Vol. 3741:
Lithography for Semiconductor Manufacturing
Chris A. Mack; Tom Stevenson, Editor(s)