초록 ▼

An optical inspection device generates a plurality of measured optical data from inspection of a thin film stack. A processor evolves models of theoretical data, which are compared to the measured data, and a "best fit" solution is provided as the result. Each model of theoretical data is represente

An optical inspection device generates a plurality of measured optical data from inspection of a thin film stack. A processor evolves models of theoretical data, which are compared to the measured data, and a "best fit" solution is provided as the result. Each model of theoretical data is represented by an underlying "genotype" which is an ordered list of "genes." Each gene corresponds to a selected thin film parameter of interest. Many such individual genotypes are created thereby forming a "population" of genotypes, which are evolved through the use of a genetic algorithm. Each genotype has a fitness associated therewith based on how much the theoretical data derived therefrom differs from the measured data. Individual genotypes are selected based on fitness, then a genetic operation is performed on the selected genotypes to produce new genotypes. Multiple generations of genotypes are evolved until an acceptable solution is obtained.

대표청구항 ▼

[ We claim:] [1.] A method for evaluating parameters of a stack of thin film layers on a sample comrprising:identifying a group of thin film parameters to be evaluated;defining a genotype as a collection of genes, each gene corresponding to a selected one of the group of thin film parameters to be e

[ We claim:] [1.] A method for evaluating parameters of a stack of thin film layers on a sample comrprising:identifying a group of thin film parameters to be evaluated;defining a genotype as a collection of genes, each gene corresponding to a selected one of the group of thin film parameters to be evaluated;defining a population as a collection of genotypes;initializing a current population with theoretical parameters corresponding to the actual parameters of the thin film layers to be evaluated;for each group of theoretical parameters, deriving a set of theoretical data corresponding thereto;optically inspecting the thin film stack and generating therefrom a set of measured data; andcomparing the set of measured data to the sets of derived theoretical data for each genotype to determine a level of fitness for each genotype;evolving a next population by selecting at least one genotype from the current population based on the fitness level of the genotype and performing a genetic operation on the at least one genotype, thereby creating at least one new genotype and adding the at least one new genotype to the next population; andrepeating the comparing and evolving steps so that the theoretical thin film parameters of the selected genotype become increasingly more representative of the actual thin film parameters of the sample.