AVS 49th International Symposium
    Manufacturing Science and Technology Monday Sessions
       Session MS+SE-MoM

Paper MS+SE-MoM9
Real Time Process Control by Spectroellipsometry

Monday, November 4, 2002, 11:00 am, Room C-109

Session: In-Situ Monitoring and Metrology for Coating Growth and Manufacturing
Presenter: D. Daineka, CNRS, Ecole Polytechnique, France
Authors: D. Daineka, CNRS, Ecole Polytechnique, France
P. Bulkin, CNRS, Ecole Polytechnique, France
T. Novikova, CNRS, Ecole Polytechnique, France
B. Drévillon, CNRS, Ecole Polytechnique, France
Correspondent: Click to Email
In situ ellipsometry is well known to be the most sensitive, non-invasive tool for monitoring and control of thin film growth. In the fabrication of optical coatings and thin films in general the refractive index of the material is usually assumed to remain constant within a single layer. With such assumption only optical thickness of the layer can be controlled. For modern complex structures, however, even insignificant variation in the refractive index can be very detrimental to the final performance of the coating. Simultaneous real-time determination of refractive index and growth rate is required in order to comply with strict specifications. If the index departs from the pre-calculated target value, one has to adjust process parameters. In PECVD such control variables are gas flows of the precursors. We report on the closed-loop control of the silicon oxynitrides deposition by in situ phase modulated kinetic spectroellipsometry using a direct numerical inversion algorithm for the real-time reconstruction of refractive index and layer thickness. This technique is tested on constant index layers as well as on graded refractive index profiles and shown to be efficient and reliable.