Optimizing an optical parametric model for structural analysis using optical critical dimension (OCD) metrology

A method of optimizing optical parametric models for three-dimensional structural analysis using optical critical dimension (OCD) metrology with an optical metrology system, the optical metrology system including a processor coupled with a memory and an optical metrology tool, the method performed by the optical metrology system comprising:

• measuring values of far field diffraction signals for a three-dimensional structure, the measurement being performed by the optical metrology tool of the optical metrology system;
• determining a first optical model fit for a parameter of the three-dimensional structure, the first optical model fit based on a domain of wavelengths for a first model of the three-dimensional structure;
• determining a first near optical field response for a first wavelength of the domain of wavelengths at a plurality of azimuth angles;
• determining a second near optical field response for a second, different wavelength of the domain of wavelengths at one of the plurality of azimuth angles,
• wherein determining the first and second near optical field responses comprises:
• identifying a region of low correlation of the first optical model fit with measured values for the structure, and
• selecting the first and second wavelengths from the region of low correlation of the first optical model fit;
• comparing the first and second near optical field responses to locate a common region of high near optical field intensity for the parameter of the three-dimensional structure;
• modifying the first model of the three-dimensional structure based at least in part on the common region of high near optical field intensity to provide a second, different model of the three-dimensional structure;
• and determining a second, different optical model fit for the parameter of the three-dimensional structure based on the second model of the three-dimensional structure.

A non-transitory machine-accessible storage medium having instructions stored thereon which cause a data processing system to perform a method of optimizing optical parametric models for structural analysis using optical critical dimension (OCD) metrology with an optical metrology system, the optical metrology system including a processor coupled with a memory and an optical metrology tool, the method comprising:

• measuring values of far field diffraction signals for a structure with the optical metrology tool of the optical metrology system;
• determining a first optical model fit for a parameter of the structure, the first optical model fit based on a domain of quantities for a first model of the structure;
• determining a first near optical field response for a first quantity of the domain of quantities and a second near optical field response for a second, different quantity of the domain of quantities, wherein the domain of quantities is the first quantity being a first wavelength and the second quantity being a second wavelength, and wherein determining the first and second near optical field responses comprises:
• identifying a region of low correlation of the first optical model fit with measured values for the structure, and
• selecting the first and second wavelengths from the region of low correlation of the first optical model fit;
• comparing the first and second near optical field responses to locate a common region of high near optical field intensity for the parameter of the structure;
• modifying the first model of the structure based at least in part on the common region of high near optical field intensity to provide a second, different model of the structure;
• and determining a second, different optical model fit for the parameter of the structure based on the second model of the structure.

A non-transitory machine-accessible storage medium having instructions stored thereon which cause a data processing system to perform a method of optimizing optical parametric models for three-dimensional structural analysis using optical critical dimension (OCD) metrology with an optical metrology system, the method comprising:

• measuring values of far field diffraction signals for a three-dimensional structure with an optical metrology tool of the optical metrology system;
• determining a first optical model fit for a parameter of the three-dimensional structure, the first optical model fit based on a domain of wavelengths for a first model of the three-dimensional structure;
• determining a first near optical field response for a first wavelength of the domain of wavelengths at a plurality of azimuth angles;
• determining a second near optical field response for a second, different wavelength of the domain of wavelengths at one of the plurality of azimuth angles,
• wherein determining the first and second near optical field responses comprises:
• identifying a region of low correlation of the first optical model fit with measured values for the three-dimensional structure, and
• selecting the first and second wavelengths from the region of low correlation of the first optical model fit;
• comparing the first and second near optical field responses to locate a common region of high near optical field intensity for the parameter of the three-dimensional structure;
• modifying the first model of the three-dimensional structure based at least in part on the common region of high near optical field intensity to provide a second, different model of the three-dimensional structure;
• and determining a second, different optical model fit for the parameter of the three-dimensional structure based on the second model of the three-dimensional structure.