Contribution à l'amélioration de la résolution en profondeur lors de l'analyse SIMS par des techniques de traitement du signal.

Abstract

The improvement of the depth resolution of Secondary Ions Mass Spectrometry (SIMS) analysis for the actual needs of microelectronics is necessary. In this work, we chose to improve the depth resolution by signal processing techniques, in particular the deconvolution. A deconvolution technique is proposed. It is able to produce regular solutions similar to those obtained by Van Cittert with Tikhonov-Miller regularization and hard constraints algorithm (algorithm already proved its effectiveness in SIMS) with a faster convergence. Moreover, by using the proposed algorithm the gains in depth resolution and in maximum are better than those achieved using the algorithm of Van Cittert regularized and constrained. Techniques to overcome the limits of the partial deconvolution procedure are also proposed. It was shown that the amplification of the noise can be controlled by filtering the measured profile before the application of the deconvolution or by applying the partial deconvolution procedure through Tikhonov-Miller regularization. The two problems amplification of the noise and appearance of negative values in the deconvolved profiles can be treated by using iterative methods.