Abstract: The present disclosure provides systems for controlling movement of a table supporting an object. The system may include: a first control sub-system configured to generate a first control instruction; a second control sub-system configured to generate a second control instruction; a table control sub-system operably coupled to the table; and a master controller configured to receive the first control instruction from the first control sub-system, or the second control instruction from the second control sub-system, generate a third control instruction based on the first control instruction or the second control instruction, and transmit the third control instruction to the table control sub-system. The table control sub-system may be configured to generate a control signal based on the third control instruction, and cause the table to move based on the control signal.

Abstract: A method for measuring critical dimension of semiconductor, includes: acquiring a plurality of measured spectra for signals scattered from a wafer to be measured; determining an average measured spectrum of the plurality of measured spectra; determining a plurality of mean square error (MSE) values each between a corresponding one of the plurality of measured spectra and the average measured spectrum, and defining the one of the plurality of measured spectra corresponding to a maximum one of the plurality of MSE values as a farthest measured spectrum; determining a spectrum matching range including a plurality of library spectra in a spectral library, based on the average measured spectrum and the farthest measured spectrum; and matching the plurality of measured spectra with the library spectra in the spectrum matching range, to determine one or more values of one or more parameters, respectively, for a structure on the wafer.

Abstract: One embodiment relates to a method of model-based optical metrology. An area of a geometrical structure of dispersive materials on a substrate is illuminated with polarized incident electromagnetic radiation using an illuminator of a scatterometer apparatus. Spectral components of the incident electromagnetic radiation reflected from the area are measured using a detector of the scatterometer apparatus. Using a computer for the scatterometer apparatus, parameter values are determined that minimize an objective function which represents a difference between the measured spectral components and computed spectral components based on a parameterized model of the geometrical structure. Steps for determining the parameter values that minimize the objective function include: computing a solution to state equations driven by a function representing the incident electromagnetic radiation, and computing a solution to an adjoint to the state equations. Other embodiments and features are also disclosed.