Abstract: Provided are optimized scatterometry techniques for evaluating a diffracting structure. In one embodiment, a method includes computing a finite-difference derivative of a field matrix with respect to first parameters (including a geometric parameter of the diffracting structure), computing an analytic derivative of the Jones matrix with respect to the field matrix, computing a derivative of the Jones matrix with respect to the first parameters, and computing a finite-difference derivative of the Jones matrix with respect to second parameters (including a non-geometric parameter). In one embodiment, a method includes generating a transfer matrix having Taylor Series approximations for elements, and decomposing the field matrix into two or more smaller matrices based on symmetry between the incident light and the diffracting structure.

Abstract: Ellipsometry systems and ellipsometry data collection methods with improved stabilities are disclosed. In accordance with the present disclosure, multiple predetermined, discrete analyzer angles are utilized to collect ellipsometry data for a single measurement, and data regression is performed based on the ellipsometry data collected at these predetermined, discrete analyzer angles. Utilizing multiple discrete analyzer angles for a single measurement improves the stability of the ellipsometry system.

Abstract: The present invention includes generating a three-dimensional design of experiment (DOE) for a plurality of semiconductor wafers, a first dimension of the DOE being a relative amount of a first component of the thin film, a second dimension of the DOE being a relative amount of a second component of the thin film, a third dimension of the DOE being a thickness of the thin film, acquiring a spectrum for each of the wafers, generating a set of optical dispersion data by extracting a real component (n) and an imaginary component (k) of the complex index of refraction for each of the acquired spectrum, identifying one or more systematic features of the set of optical dispersion data; and generating a multi-component Bruggeman effective medium approximation (BEMA) model utilizing the identified one or more systematic features of the set of optical dispersion data.

Abstract: A method to calibrate a polarizer in polarized optical system at any angle of incidence, by decoupling the calibration from a polarization effect of the system, by providing a calibration apparatus that includes a substrate having a polarizer disposed on a surface thereof, with an indicator on the substrate for indicating a polarization orientation of the polarizer, loading the calibration apparatus in the polarized optical system with the indicator in a desired position, determining an initial angle between the polarization orientation and a reference of the polarized optical system, acquiring spectra using the polarized optical system at a plurality of known angles between the polarization orientation and the reference of the polarized optical system, using the spectra to plot a curve indicating an angle of the polarizer in the polarized optical system, and when the angle of the polarizer is outside of a desired range, adjusting the angle of the polarizer, and repeating the steps of acquiring the spectra, a

Abstract: Approaches for accurate neural network training for library-based critical dimension (CD) metrology are described. Approaches for fast neural network training for library-based CD metrology are also described.

Abstract: Methods of determining asymmetric properties of structures are described. A method includes measuring, for a grating structure, a first signal and a second, different, signal obtained by optical scatterometry. A difference between the first signal and the second signal is then determined. An asymmetric structural parameter of the grating structure is determined based on a calculation using the first signal, the second signal, and the difference.

Abstract: Line edge roughness or line width roughness of a feature on a sample may be determined from incident radiation scattered from the feature. An amount of ordered scattered radiation characterized by a discrete diffraction order is determined and a diffuse scattered radiation signal is measured. A ratio between an intensity of the ordered scattered incident radiation and an intensity of the diffuse scattered radiation signal is determined. The line edge roughness or line width roughness is determined from the ratio.

Abstract: A global node optimization (GNO) technique can generate a model for a planar multiple layer film stack structure, e.g. a binary grating structure. In this technique, after obtaining spectra and target thicknesses from one or more wafers, a continuous film approximation (CFA) and a grating factor (GF) set are identified. A model using the CFA and the GF set is optimized by simultaneously fitting a plurality of the spectra while minimizing error compared to the target thicknesses. After simultaneously fitting all of the spectra, a GNO stack is created. A GNO recipe is then created using the GNO stack. Notably, a tool implementing the GNO technique uses minimal modeling capabilities and computational resources.

Abstract: The above and other needs are met by a method of determining actual properties of a film stack by directing an incident beam of light towards the film stack, such that the incident beam of light is reflected from the film stack as a reflected beam of light. The actual properties of the reflected beam of light are measured, and properties of the film stack are estimated. A mathematical model of the film stack is solved with the estimated properties of the film stack, to yield theoretical properties of the reflected beam of light. The mathematical model is solved in part using a fast Z-matrix algorithm. The theoretical properties of the reflected beam of light are compared to the actual properties of the reflected beam of light, to yield a cost function. The estimated properties of the film stack are iteratively adjusted, and the mathematical model is iteratively solved, until the cost function is within a desired tolerance.

Abstract: Metrology may be implemented during semiconductor device fabrication by a) modeling a first measurement on a first test cell formed in a layer of a partially fabricated device; b) performing a second measurement on a second test cell in the layer; c) feeding information from the second measurement into the modeling of the first measurement; and after a lithography pattern has been formed on the layer including the first and second test cells, d) modeling a third and a fourth measurement on the first and second test cells respectively using information from a) and b) respectively.

Abstract: A method of determining actual properties of layered media. An incident beam of light is directed towards the layered media, such that the incident beam of light is reflected from the layered media as a reflected beam of light. The actual properties of the reflected beam of light are measured, and properties of the layered media are estimated. A mathematical model of the layered media based on a modal function expansion is solved with the estimated properties of the layered media to yield theoretical properties of the reflected beam of light. The eigenvalues of the modal functions are computed recursively by recasting the eigenvalue equation in the following form: ?ni+1=F(?ni) where ?ni=the eigenvalue of the ith recursion and F is a function such that ?n=F(?n) is mathematically identical to the eigenvalue equation.

Abstract: A method of determining actual properties of layered media. An incident beam of light is directed towards the layered media, such that the incident beam of light is reflected from the layered media as a reflected beam of light. The actual properties of the reflected beam of light are measured, and properties of the layered media are estimated. A mathematical model of the layered media is solved with the estimated properties of the layered media to yield theoretical properties of the reflected beam of light. The mathematical model is solved using a diagonal T matrix algorithm. The theoretical properties of the reflected beam of light are compared to the actual properties of the reflected beam of light to yield a cost function. The estimated properties of the layered media are iteratively adjusted and the mathematical model is iteratively solved until the cost function is within a desired tolerance. The estimated properties of the layered media are reported as the actual properties of the layered media.

Abstract: A method of determining actual properties of layered media. An incident beam of light is directed towards the layered media, such that the incident beam of light is reflected from the layered media as a reflected beam of light. The actual properties of the reflected beam of light are measured, and properties of the layered media are estimated. A mathematical model of the layered media is solved with the estimated properties of the layered media to yield theoretical properties of the reflected beam of light. The mathematical model is solved using at least one of a modified T matrix algorithm and a Z matrix algorithm. The theoretical properties of the reflected beam of light are compared to the actual properties of the reflected beam of light to yield a cost function. The estimated properties of the layered media are iteratively adjusted and the mathematical model is iteratively solved until the cost function is within a desired tolerance.

Abstract: An optical metrology system includes model approximation logic for generating an optical model based on experimental data. By eliminating theoretical model generation, in which the fundamental equations of a test sample must be solved, the model approximation logic significantly reduces the computational requirements of the metrology system when measuring films formed on patterned base layers. The experimental model can be created by selecting an expected mathematical form for the final model, gathering experimental data, and compiling a lookup model. The lookup model can include the actual measurement data sorted by output (attribute) value, or can include “grating factors” that represent compensation factors that, when applied to standard monolithic model equations, compensate for the optical effects of grating layers.

Abstract: A method of determining the actual properties of a film stack. An incident beam of light is directed towards the film stack, such that the incident beam of light is reflected from the film stack as a reflected beam of light. The actual properties of the reflected beam of light are measured, and properties of the film stack are estimated. A mathematical model of the film stack is solved with the estimated properties of the film stack to yield theoretical properties of the reflected beam of light. The theoretical properties of the reflected beam of light are compared to the actual properties of the reflected beam of light to yield a cost function. The estimated properties of the film stack are iteratively adjusted and the mathematical model is iteratively solved until the cost function is within a desired tolerance. The estimated properties of the film stack are reported as the actual properties of the film stack.

Abstract: A method and apparatus for performing in situ measurement of etch uniformity within a semiconductor wafer processing system. Specifically, the apparatus and concomitant method analyzes optical emission spectroscopy (OES) data produced by an OES system. The analysis computes the first derivative of the OES data as the data is acquired. When the data meets a particular trigger criterion, the value of the first derivative is correlated with a particular uniformity value. As such, the system produces a uniformity value for a semiconductor wafer using an in situ measurement technique.

Abstract: A substrate processing system having a bi-directional interface and concomitant communication protocol to allow a controller to communicate with an external endpoint system is disclosed. More specifically, the substrate processing system comprises a controller and an endpoint detection system that are coupled together via a RS-232 interface. A SECS compliant communication protocol is employed to effect communication between the controller and endpoint detection system to increase wafer processing information exchange and data exchange.