Rational approximation and continued-fraction approximation approaches for computation efficiency of diffraction signals
AssigneesTokyo Electron Limited, KLA-Tencor Corporation
InventorHanyou Chu
Life of this patent
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Abstract
Methods and apparatuses for improving computation efficiency for diffraction signals in optical metrology are described. The method includes simulating a set of diffraction orders for a structure. A set of diffraction efficiencies is determined for the set of diffraction orders. A rational approximation or a continued-fraction approximation is applied to the set of diffraction efficiencies to obtain a rationally approximated set of diffraction efficiencies or a continued-fraction approximated set of diffraction efficiencies, respectively. A simulated spectrum is then provided.
Claims30
A method for improving computation efficiency for diffraction signals in optical metrology, comprising:
- simulating a set of diffraction orders for a structure;
- determining a set of diffraction efficiencies for the set of diffraction orders;
- applying a rational approximation to the set of diffraction efficiencies to obtain a rationally approximated set of diffraction efficiencies;
- and
- providing a simulated spectrum based on the rationally approximated set of diffraction efficiencies.
A method for improving computation efficiency for diffraction signals in optical metrology, comprising:
- simulating a set of diffraction orders for a structure;
- determining a set of diffraction efficiencies for the set of diffraction orders;
- applying a continued-fraction approximation to the set of diffraction efficiencies to obtain a continued-fraction approximated set of diffraction efficiencies;
- and
- providing a simulated spectrum based on the continued-fraction approximated set of diffraction efficiencies.
A machine-accessible storage medium having instructions stored thereon which cause a data processing system to perform a method for improving computation efficiency for diffraction signals in optical metrology, the method comprising:
- simulating a set of diffraction orders for a structure;
- determining a set of diffraction efficiencies for the set of diffraction orders;
- applying a rational approximation to the set of diffraction efficiencies to obtain a rationally approximated set of diffraction efficiencies;
- and
- providing a simulated spectrum based on the rationally approximated set of diffraction efficiencies.
A machine-accessible storage medium having instructions stored thereon which cause a data processing system to perform a method for improving computation efficiency for diffraction signals in optical metrology, the method comprising:
- simulating a set of diffraction orders for a structure;
- determining a set of diffraction efficiencies for the set of diffraction orders;
- applying a continued-fraction approximation to the set of diffraction efficiencies to obtain a continued-fraction approximated set of diffraction efficiencies;
- and
- providing a simulated spectrum based on the continued-fraction approximated set of diffraction efficiencies.
A system for improving computation efficiency for diffraction signals in optical metrology, comprising:
- a processor;
- a main memory;
- a secondary memory having instructions stored thereon which cause the system to perform a method, comprising:
- simulating a set of diffraction orders for a structure;
- determining a set of diffraction efficiencies for the set of diffraction orders;
- applying a rational approximation to the set of diffraction efficiencies to obtain a rationally approximated set of diffraction efficiencies;
- and
- providing a simulated spectrum based on the rationally approximated set of diffraction efficiencies;
- and
- a bus which allows the processor, the main memory and the secondary memory to communicate with one another.
A system for improving computation efficiency for diffraction signals in optical metrology, comprising:
- a processor;
- a main memory;
- a secondary memory having instructions stored thereon which cause the system to perform a method, comprising:
- simulating a set of diffraction orders for a structure;
- determining a set of diffraction efficiencies for the set of diffraction orders;
- applying a continued-fraction approximation to the set of diffraction efficiencies to obtain a continued-fraction approximated set of diffraction efficiencies;
- and
- providing a simulated spectrum based on the continued-fraction approximated set of diffraction efficiencies;
- and
- a bus which allows the processor, the main memory and the secondary memory to communicate with one another.
Dependencies are inferred from the claim text.