Abstract: An optical metrology system includes a photometric device with a source configured to generate and direct light onto a structure, and a detector configured to detect light diffracted from the structure and to convert the detected light into a measured diffraction signal. A processing module of the optical metrology system is configured to receive the measured diffraction signal from the detector to analyze the structure. The optical metrology system also includes a generic interface disposed between the generic interface and the processing module. The generic interface is configured to provide the measured diffraction signal to the processing module using a standard set of signal parameters. The standard set of signal parameters includes a reflectance parameter that characterizes the change in intensity of light when reflected on the structure and a polarization parameter that characterizes the change in polarization states of light when reflected on the structure.

Abstract: The profile of a single feature formed on a wafer can be determined by obtaining an optical signature of the single feature using a beam of light focused on the single feature. The obtained optical signature can then be compared to a set of simulated optical signatures, where each simulated optical signature corresponds to a hypothetical profile of the single feature and is modeled based on the hypothetical profile.

Abstract: A wafer structure profile is modeled by determining one or more termination criteria. A determination is made as to whether a wafer structure includes at least one layer having three or more materials alone a line within the at least one layer. An optical metrology model for the wafer structure is created, where three or more materials are incorporated in the model for the at least one layer having three or more materials. A set of diffraction signals is simulated using the optical metrology model. The set of simulated diffraction signals and a set of diffraction signals measured off of the wafer structure are used to determine if the one or more termination criteria are met. The optical metrology model is modified until the one or more termination criteria are met.

Abstract: An optical metrology system includes a photometric device with a source configured to generate and direct light onto a structure, and a detector configured to detect light diffracted from the structure and to convert the detected light into a measured diffraction signal. A processing module of the optical metrology system is configured to receive the measured diffraction signal from the detector to analyze the structure. The optical metrology system also includes a generic interface disposed between the photometric device and the processing module. The generic interface is configured to provide the measured diffraction signal to the processing module using a standard set of signal parameters. The standard set of signal parameters includes a reflectance parameter that characterizes the change in intensity of light when reflected on the structure and a polarization parameter that characterizes the change in polarization states of light when reflected on the structure.

Abstract: The present invention includes a method and system for identifying an underlying structure that achieves improved planarization characteristics of layers while minimizing introduction of random and/or systematic noise to the reflected metrology signal. One embodiment of the present invention is a method of designing underlying structures in a wafer with pads of varying sizes and varying loading factors, and selecting the design of pads that yield a reflected metrology signal closest to the calibration metrology signal and that meet preset standard planarization characteristics. Another embodiment is a method of designing underlying structures with random shapes of varying sizes and varying loading factors. Still another embodiment is the use of periodic structures of varying line-to-space ratios in one or more underlying layers of a wafer, the periodicity of the underlying periodic structure being positioned at an angle relative to the direction of periodicity of the target periodic structure of the wafer.

Abstract: The profile of a single feature formed on a wafer can be determined by obtaining an optical signature of the single feature using a beam of light focused on the single feature. The obtained optical signature can then be compared to a set of simulated optical signatures, where each simulated optical signature corresponds to a hypothetical profile of the single feature and is modeled based on the hypothetical profile.

Abstract: A library of simulated-diffraction signals and hypothetical profiles of a periodic grating can be generated by generating diffraction calculations for a plurality of blocks of hypothetical layers. A diffraction calculation for a block of hypothetical layers characterizes, in part, the behavior of a diffraction beam in the block of hypothetical layers. Each block of hypothetical layers includes two or more hypothetical layers, and each hypothetical layer characterizes a layer within a hypothetical profile. The diffraction calculations for the blocks of hypothetical layers are stored prior to generating the library. The simulated-diffraction signals to be stored in the library are then generated based on the stored diffraction calculations for the blocks of hypothetical layers.

Abstract: A simulated diffraction signal to be used in measuring shape roughness of a structure formed on a wafer using optical metrology is generated by defining an initial model of the structure. A statistical function of shape roughness is defined. A statistical perturbation is derived based on the statistical function and superimposed on the initial model of the structure to define a modified model of the structure. A simulated diffraction signal is generated based on the modified model of the structure.

Abstract: A method of generating a library of simulated-differentiation signals (simulated signals of a periodic grating includes obtaining a measured-differentiation signal (measured signal). Hypothetical parameters are associated with a hypothetical profile. The hypothetical parameters are varied within a range to generate a set of hypothetical profiles. The range to vary the hypothetical parameters is adjusted based on the measured signal. A set of simulated signals is generated from the set of hypothetical profiles.

Abstract: The present invention relates to a method and system for efficiently determining grating profiles using dynamic learning in a library generation process. The present invention also relates to a method and system for searching and matching trial grating profiles to determine shape, profile, and spectrum data information associated with an actual grating profile.

Abstract: A library of simulated-diffraction signals for an integrated circuit periodic grating is generated by generating sets of intermediate layer data. Each set of intermediate layer data corresponding to a separate one of a plurality of hypothetical layers of a hypothetical profile of the periodic grating. Each separate hypothetical layer has one of a plurality of possible combinations of hypothetical values of properties for that hypothetical layer. The generated sets of intermediate layer data are stored. Simulated-diffraction signals for each of a plurality of hypothetical profiles are generated based on the stored generated sets of intermediate layer data.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.

Abstract: A method of generating a library of simulated-diffraction signals (simulated signals) of a periodic grating includes obtaining a measured-diffraction signal (measured signal). Hypothetical parameters are associated with a hypothetical profile. The hypothetical parameters are varied within a range to generate a set of hypothetical profiles. The range to vary the hypothetical parameters is adjusted based on the measured signal. A set of simulated signals is generated from the set of hypothetical profiles.

Abstract: The present invention relates to a method and system for efficiently determining grating profiles using dynamic learning in a library generation process. The present invention also relates to a method and system for searching and matching trial grating profiles to determine shape, profile, and spectrum data information associated with an actual grating profile.

Abstract: A library of simulated-diffraction signals for an integrated circuit periodic grating is generated by generating gets of intermediate layer data. Each set of intermediate layer data corresponding to a separate one of a plurality of hypothetical layers of a hypothetical profile of the periodic grating. Each separate hypothetical layer has one of a plurality of possible combinations of hypothetical values of properties for that hypothetical layer. The generated sets of intermediate layer data are stored. Simulated-diffraction signals for each of a plurality of hypothetical profiles are generated based on the stored generated sets of intermediate layer data.

Abstract: A structure formed on a semiconductor wafer is examined by directing an incident beam at the structure at an incidence angle and a azimuth angle. The incident beam is scanned over a range of azimuth angles to obtain an azimuthal scan. The cross polarization components of diffracted beams are measured during the azimuthal scan.

Abstract: The diffraction of electromagnetic radiation from periodic grating profiles is determined using rigorous coupled-wave analysis, with intermediate calculations cached to reduce computation time. To implement the calculation, the periodic grating is divided into layers, cross-sections of the ridges of the grating are discretized into rectangular sections, and the permittivity, electric fields and magnetic fields are written as harmonic expansions along the direction of periodicity of the grating. Application of Maxwell's equations to each intermediate layer, i.e., each layer except the atmospheric layer and the substrate layer, provides a matrix wave equation with a wave-vector matrix A coupling the harmonic amplitudes of the electric field to their partial second derivatives in the direction perpendicular to the plane of the grating, where the wave-vector matrix A is a function of intra-layer parameters and incident-radiation parameters.

Abstract: Overlay measurements are obtained by forming a first grating test pattern using a first layer mask. A second grating test pattern is formed using a second layer mask. The first and second grating test patterns have the same periodicity. The first and second grating test patterns are measured using an optical metrology equipment. The alignment of the second layer mask to the first layer mask is measured based on the measurement of the first and second grating test patterns.

Abstract: Overlay measurements for a semiconductor wafer are obtained by forming a periodic grating on the wafer having a first set of ridges and a second set of ridges. The first and second sets of ridges are formed on the wafer using a first mask and a second mask, respectively. After forming the first and second sets of gratings, zero-order cross polarization measurements of a portion of the periodic grating are obtained. Any overlay error between the first and second masks used to form the first and second sets of gratings is determined based on the obtained zero-order cross polarization measurements.

Abstract: Disclosed is a method and system for measurement of periodic gratings which have deviations which result in more than two materials occurring along at least one line in the periodic direction. A periodic grating is divided into a plurality of hypothetical layers, each hypothetical layer having a normal vector orthogonal to the direction of periodicity, each hypothetical layer having a single material within any line parallel to the normal vector, and at least one of the hypothetical layers having at least three materials along a line in the direction of periodicity. A harmonic expansion of the permittivity ? or inverse permittivity 1/? is performed along the direction of periodicity for each of the layers including the layer which includes the first, second and third materials. Fourier space electromagnetic equations are then set up in each of the layers using the harmonic expansion of the permittivity E or inverse permittivity 1/?, and Fourier components of electric and magnetic fields in each layer.