Method and apparatus for multidomain data analysis
First Claim
1. A multidomain method for evaluating parameters of a semiconductor wafer or wafer set comprising:
- identifying a group of semiconductor wafer parameters to be evaluated;
mapping the semiconductor wafer parameters into at least one genotype, said genotype comprising a collection of genes, each gene corresponding to a selected one of the group of semiconductor wafer parameters to be evaluated;
defining more than one domain as a collection of genotypes, each domain with its own population of genotypes;
deriving a set of theoretical data for each genotype;
inspecting the semiconductor wafer or wafer set using a beam of radiation and generating therefrom sets of measured data;
comparing a set of measured data to a corresponding set of derived theoretical data for each genotype in each domain in order to determine a level of fitness for each genotype;
migrating genotypes among the domains by selecting at least one genotype from a current domain population and adding it to the population of a different domain;
evolving a next population for each domain 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; and
repeating the comparing, migrating, and evolving steps so that for each domain the fittest genotype becomes increasingly more fit.
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Abstract
An optical measuring device generates a plurality of measured optical data from inspection of a thin film stack. The measured optical data group naturally into several domains. In turn the thin film parameters associated with the data fall into two categories: local and global. Local “genes” represent parameters that are associated with only one domain, while global genes represent parameters that are associated with multiple domains. A processor evolves models for the data associated with each domain, which models 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 set of the genes. For each domain a “population” of genotypes is evolved through the use of a genetic algorithm. The global genes are allowed to “migrate” among multiple domains during the evolution process. Each genotype has a fitness associated therewith based on how much the theoretical data predicted by the genotype differs from the measured data. During the evolution process, 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 or other termination criterion is satisfied.
89 Citations
37 Claims
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1. A multidomain method for evaluating parameters of a semiconductor wafer or wafer set comprising:
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identifying a group of semiconductor wafer parameters to be evaluated;
mapping the semiconductor wafer parameters into at least one genotype, said genotype comprising a collection of genes, each gene corresponding to a selected one of the group of semiconductor wafer parameters to be evaluated;
defining more than one domain as a collection of genotypes, each domain with its own population of genotypes;
deriving a set of theoretical data for each genotype;
inspecting the semiconductor wafer or wafer set using a beam of radiation and generating therefrom sets of measured data;
comparing a set of measured data to a corresponding set of derived theoretical data for each genotype in each domain in order to determine a level of fitness for each genotype;
migrating genotypes among the domains by selecting at least one genotype from a current domain population and adding it to the population of a different domain;
evolving a next population for each domain 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; and
repeating the comparing, migrating, and evolving steps so that for each domain the fittest genotype becomes increasingly more fit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 33)
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12. A multidomain method for evaluating parameters of a semiconductor wafer or wafer set, comprising:
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identifying a group of semiconductor wafer parameters to be evaluated;
mapping the semiconductor wafer parameters into at least one genotype, said genotype comprising a collection of genes, each gene corresponding to a selected one of the group of semiconductor wafer parameters to be evaluated;
defining more than one domain as a collection of genotypes, each domain with its own population of genotypes;
deriving a set of theoretical data for each genotype;
inspecting the semiconductor wafer or wafer set using a beam of radiation and generating therefrom sets of measured data;
comparing a set of measured data to a corresponding set of derived theoretical data for each genotype in each domain in order to determine a level of fitness for each genotype;
migrating genotypes among the domains by selecting at least one genotype from a current domain population and adding it to the population of a different domain;
evolving a new population of genotypes for each domain by selecting at least one genotype from the current domain population based on the fitness of the genotype and performing a genetic operation on the at least one genotype to form at least one new genotype, said genetic operation being selected from one of the following;
reproducing an identical copy of the at least one genotype;
selecting a gene from the at least one genotype and mutating the gene;
or selecting corresponding genes in a pair of genotypes and exchanging the genes, and adding the at least one new genotype to a next population; and
repeating the comparing, migrating, and evolving steps so that for each domain the fittest genotype becomes increasingly more fit. - View Dependent Claims (13, 14, 15, 16)
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17. A multidomain method for evaluating parameters of a semiconductor wafer or wafer set comprising:
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identifying a group of semiconductor wafer parameters to be evaluated;
mapping the semiconductor wafer parameters into at least one genotype, said genotype comprising a collection of genes, each gene corresponding to a selected one of the group of semiconductor wafer parameters to be evaluated;
dividing the genes into at least two different gene classes, at least one of said gene classes being subject to a migration operation;
defining more than one domain as a collection of genotypes, each domain with its own population of genotypes;
deriving a set of theoretical data for each genotype;
inspecting the semiconductor wafer or wafer set using a beam of radiation and generating therefrom sets of measured data;
comparing a set of measured data to a corresponding set of derived theoretical data for each genotype in each domain in order to determine a level of fitness for each genotype;
applying a migration operation to at least one genotype from a current domain population, said migration operation including a mechanism for moving genes in at least one of said gene classes to the genotype population of a different domain;
evolving a next population for each domain 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; and
repeating the comparing, migration operation, and evolving steps so that for each domain the fittest genotype becomes increasingly more fit. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A multidomain method for evaluating parameters of a semiconductor wafer or wafer set, comprising:
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identifying a group of semiconductor wafer parameters to be evaluated;
mapping the semiconductor wafer parameters into at least one genotype, said genotype comprising a collection of genes, each gene corresponding to a selected one of the group of semiconductor wafer parameters to be evaluated;
dividing the genes into at least two different gene classes, at least one of said gene classes being subject to a migration operation;
defining more than one domain as a collection of genotypes, each domain with its own population of genotypes;
deriving a set of theoretical data for each genotype;
inspecting the semiconductor wafer or wafer set using a beam of radiation and generating therefrom sets of measured data;
comparing a set of measured data to a corresponding set of derived theoretical data for each genotype in each domain in order to determine a level of fitness for each genotype;
applying a migration operation to at least one genotype from a current domain population, said migration operation including a mechanism for moving genes in at least one of said gene classes to the genotype population of a different domain;
evolving a new population of genotypes for each domain by selecting at least one genotype from the current domain population based on the fitness of the genotype and performing a genetic operation on the at least one genotype to form at least one new genotype, said genetic operation being selected from one of the following;
reproducing an identical copy of the at least one genotype;
selecting a gene from the at least one genotype and mutating the gene;
or selecting corresponding genes in a pair of genotypes and exchanging the genes, and adding the at least one new genotype to a next population; and
repeating the comparing, migration operation, and evolving steps so that for each domain the fittest genotype becomes increasingly more fit. - View Dependent Claims (28, 29, 30, 31, 32)
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34. A multidomain process for evaluating parameters of a semiconductor wafer or wafer set comprising:
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identifying a group of semiconductor wafer parameters to be evaluated;
inspecting the semiconductor wafer or wafer set using a beam of radiation and generating therefrom sets of measured data, each set of measured data corresponding to a different measurement;
defining more than one search domain, each search domain corresponding to a set of measured data;
applying an iterative search method to each search domain in order to generate a group of optimized parameter values for each search domain, said iterative search method including the steps of;
generating a set of theoretical parameter values associated with each search domain;
deriving a set of theoretical data for each set of theoretical parameter values;
comparing the sets of theoretical data associated with the set of parameter values associated with each search domain to the set of measured data corresponding to each search domain;
generating a new set of theoretical parameter values of each search domain based on the comparing step in a manner so as to identify increasingly more optimal theoretical parameter values for each search domain; and
wherein said iterative search method further includes the step of migrating a set of theoretical parameter values from one search domain to another search domain. - View Dependent Claims (35, 36, 37)
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Specification