Simulated Annealing Algorithm Application on Inverting Optical Constants of Thin Films

In thin-film thickness wideband monitoring system,in order to eliminate error accumulation effect of layers which have been deposited on layer which will be deposited, the thin-film optical constants of layers deposited must be achieved.Utilizing transmittance spectral curve which has been measured, Simulated Annealing Algorithm is applied on inversion of optical constants n,k,d.For the purpose of increasing optimization speed and algorithm efficiency,the algorithm is improved, exponent dropping temperature rate varies with acceptance probability P ;The finding range of new value is controlled adaptively according to acceptance rate when the dropping temperature is t,then the algorithm is applied on the example that is membrane ZnS is deposited on the substrate of quartz glass , n,k,d are obtained in a shorter time by optimization and their values are satisfying.

Compensation Research of the Thin Film Absorption in Thin-Film Thickness Wideband Monitoring System

During the course of thin film deposition,the thin-film thickness wideband monitoring system is utilized,the correction of thickness monitoring depends on overlapping stage of the theoretical transmittance curve and the measured one. The absorption of thin-film material results in the measured spectrum curve deviation from the theoretical spectrum curve. A method in software brings forward, namely before the next layer will be deposited, its theoretical transmittance curve is corrected so that the absorption of layers which have been deposited has no effect on this layer, as such, the theoretical transmittance curve of the layer which will be deposited is corrected until the deposition ends.By experiment, the monitoring error of thin-film thickness is less than 10-3, the result indicates that this method can satisfy the practical requirement.