Abstract: Disclosed are apparatus and methods for performing small angle x-ray scattering metrology. This system includes an x-ray source for generating x-rays and illumination optics for collecting and reflecting or refracting a portion of the generated x-rays towards a particular focus point on a semiconductor sample in the form of a plurality of incident beams at a plurality of different angles of incidence (AOIs). The system further includes a sensor for collecting output x-ray beams that are scattered from the sample in response to the incident beams on the sample at the different AOIs and a controller configured for controlling operation of the x-ray source and illumination optics and receiving the output x-rays beams and generating an image from such output x-rays.

Abstract: Systems and methods are presented to enhance and isolate residual signals indicative of the speckle field based on measurements taken by optically based metrology systems. Structural irregularities such as roughness and topographical errors give rise to light scattered outside of the specularly reflected component of the diffracted light. The scattered light interferes constructively or destructively with the specular component in a high numerical aperture illumination and detection system to form a speckle field. Various methods of determining residual signals indicative of the speckle field are presented. Furthermore, various methods of determining structural irregularities based on analysis of the residual signals are presented. In various embodiments, illumination with a high degree of spatial coherence is provided over any of a wide range of angles of incidence, multiple polarization channels, and multiple wavelength channels.

Abstract: Disclosed are apparatus and methods for characterizing a plurality of structures of interest on a semiconductor wafer. A plurality of models having varying combinations of floating and fixed critical parameters and corresponding simulated spectra is generated. Each model is generated to determine one or more critical parameters for unknown structures based on spectra collected from such unknown structures. It is determined which one of the models best correlates with each critical parameter based on reference data that includes a plurality of known values for each of a plurality of critical parameters and corresponding known spectra. For spectra obtained from an unknown structure using a metrology tool, different ones of the models are selected and used to determine different ones of the critical parameters of the unknown structure based on determining which one of the models best correlates with each critical parameter based on the reference data.

Abstract: Methods and systems for performing simultaneous X-ray Fluorescence (XRF) and small angle x-ray scattering (SAXS) measurements over a desired inspection area of a specimen are presented. SAXS measurements combined with XRF measurements enables a high throughput metrology tool with increased measurement capabilities. The high energy nature of x-ray radiation penetrates optically opaque thin films, buried structures, high aspect ratio structures, and devices including many thin film layers. SAXS measurements of a particular location of a planar specimen are performed at a number of different out of plane orientations. This increases measurement sensitivity, reduces correlations among parameters, and improves measurement accuracy. In addition, specimen parameter values are resolved with greater accuracy by fitting data sets derived from both SAXS and XRF measurements based on models that share at least one material parameter. The fitting can be performed sequentially or in parallel.

Abstract: Disclosed are apparatus and methods for characterizing a plurality of structures of interest on a semiconductor wafer. A plurality of spectra signals are measured from a particular structure of interest at a plurality of azimuth angles from one or more sensors of a metrology system. A difference spectrum is determined based on the spectra signals obtained for the azimuth angles. A quality indication of the particular structure of interest is determined and reported based on analyzing the difference spectrum.

Abstract: Disclosed are apparatus and methods for determining process or structure parameters for semiconductor structures. A plurality of optical signals is acquired from one or more targets located in a plurality of fields on a semiconductor wafer. The fields are associated with different process parameters for fabricating the one or more targets, and the acquired optical signals contain information regarding a parameter of interest (POI) for a top structure and information regarding one or more underlayer parameters for one or more underlayers formed below such top structure. A feature extraction model is generated to extract a plurality of feature signals from such acquired optical signals so that the feature signals contain information for the POI and exclude information for the underlayer parameters. A POI value for each top structure of each field is determined based on the feature signals extracted by the feature extraction model.

Abstract: Structural parameters of a specimen are determined by fitting models of the response of the specimen to measurements collected by different measurement techniques in a combined analysis. X-ray measurement data of a specimen is analyzed to determine at least one specimen parameter value that is treated as a constant in a combined analysis of both optical measurements and x-ray measurements of the specimen. For example, a particular structural property or a particular material property, such as an elemental composition of the specimen, is determined based on x-ray measurement data. The parameter(s) determined from the x-ray measurement data are treated as constants in a subsequent, combined analysis of both optical measurements and x-ray measurements of the specimen. In a further aspect, the structure of the response models is altered based on the quality of the fit between the models and the corresponding measurement data.

Abstract: Methods and systems for evaluating the capability of a measurement system to track measurement parameters through a given process window are presented herein. Performance evaluations include random perturbations, systematic perturbations, or both to effectively characterize the impact of model errors, metrology system imperfections, and calibration errors, among others. In some examples, metrology target parameters are predetermined as part of a Design of Experiments (DOE). Estimated values of the metrology target parameters are compared to the known DOE parameter values to determine the tracking capability of the particular measurement. In some examples, the measurement model is parameterized by principal components to reduce the number of degrees of freedom of the measurement model. In addition, exemplary methods and systems for optimizing the measurement capability of semiconductor metrology systems for metrology applications subject to process variations are presented.

Abstract: Methods and systems for enhancing metrology sensitivity to particular parameters of interest are presented. Field enhancement elements (FEEs) are constructed as part of a specimen to enhance the measurement sensitivity of structures of interest present on the specimen. The design of the FEEs takes into account measurement goals and manufacturing design rules to make target fabrication compatible with the overall device fabrication process. Measurement of opaque materials, high-aspect ratio structures, structures with low-sensitivity, or mutually correlated parameters is enhanced by the addition of FEEs. Exemplary measurements include critical dimension, film thickness, film composition, and optical scatterometry overlay. In some examples, a target element includes different FEEs to improve the measurement of different structures of interest. In other examples, different target elements include different FEEs.

Abstract: Methods and systems for performing semiconductor metrology directly on device structures are presented. A measurement model is created based on measured training data collected from at least one device structure. The trained measurement model is used to calculate process parameter values, structure parameter values, or both, directly from measurement data collected from device structures of other wafers. In some examples, measurement data from multiple targets is collected for model building, training, and measurement. In some examples, the use of measurement data associated with multiple targets eliminates, or significantly reduces, the effect of under layers in the measurement result, and enables more accurate measurements. Measurement data collected for model building, training, and measurement may be derived from measurements performed by a combination of multiple, different measurement techniques.

Abstract: Methods and systems for performing measurements based on a measurement model integrating a metrology-based target model with a process-based target model. Systems employing integrated measurement models may be used to measure structural and material characteristics of one or more targets and may also be used to measure process parameter values. A process-based target model may be integrated with a metrology-based target model in a number of different ways. In some examples, constraints on ranges of values of metrology model parameters are determined based on the process-based target model. In some other examples, the integrated measurement model includes the metrology-based target model constrained by the process-based target model. In some other examples, one or more metrology model parameters are expressed in terms of other metrology model parameters based on the process model. In some other examples, process parameters are substituted into the metrology model.

Abstract: Methods and systems for achieving a small measurement box size specification across a set of metrology system parameters are presented. The small measurement box size specification is achieved by selectively constraining one or more of the sets of system parameters during measurement. A subset of measurement system parameters such as illumination wavelength, polarization state, polar angle of incidence, and azimuth angle of incidence is selected for measurement to maintain a smaller measurement box size than would otherwise be achievable if the full, available range of measurement system parameters were utilized in the measurement. In this manner, control of one or more factors that affect measurement box size is realized by constraining the measurement system parameter space. In addition, a subset of measurement signals may be selected to maintain a smaller measurement box size than would otherwise be achievable if all available measurement signals were utilized in the measurement.

Abstract: Structural parameters of a specimen are determined by fitting models of the response of the specimen to measurements collected by different measurement techniques in a combined analysis. Models of the response of the specimen to at least two different measurement technologies share at least one common geometric parameter. In some embodiments, a model building and analysis engine performs x-ray and optical analyses wherein at least one common parameter is coupled during the analysis. The fitting of the response models to measured data can be done sequentially, in parallel, or by a combination of sequential and parallel analyses. In a further aspect, the structure of the response models is altered based on the quality of the fit between the models and the corresponding measurement data. For example, a geometric model of the specimen is restructured based on the fit between the response models and corresponding measurement data.

Abstract: Methods and systems for performing simultaneous optical scattering and small angle x-ray scattering (SAXS) measurements over a desired inspection area of a specimen are presented. SAXS measurements combined with optical scatterometry measurements enables a high throughput metrology tool with increased measurement capabilities. The high energy nature of x-ray radiation penetrates optically opaque thin films, buried structures, high aspect ratio structures, and devices including many thin film layers. SAXS and optical scatterometry measurements of a particular location of a planar specimen are performed at a number of different out of plane orientations. This increases measurement sensitivity, reduces correlations among parameters, and improves measurement accuracy. In addition, specimen parameter values are resolved with greater accuracy by fitting data sets derived from both SAXS and optical scatterometry measurements based on models that share at least one geometric parameter.

Abstract: A compact, optically-pumped solid-state microchip laser device uses efficient nonlinear intracavity frequency conversion for obtaining low-cost green and blue laser sources. The laser includes a solid-state gain medium, such as Nd:YVO4, and a nonlinear crystal. The nonlinear crystal is formed of periodically poled lithium niobate or periodically poled lithium tantalate, and the crystal is either MgO-doped, ZnO-doped, or stoichiometric to ensure high reliability. The nonlinear crystal provides efficient frequency doubling to translate energy from an infrared pump laser beam into the visible wavelength range. The laser device is assembled in a package having an output aperture for the output beam and being integrated with an optical bench accommodating a laser assembly. The package encloses and provides heat sinking for the semiconductor diode pump laser, the microchip laser cavity assembly, the optical bench platform, and electrical leads.

Abstract: A gallery of seed profiles is constructed and the initial parameter values associated with the profiles are selected using manufacturing process knowledge of semiconductor devices. Manufacturing process knowledge may also be used to select the best seed profile and the best set of initial parameter values as the starting point of an optimization process whereby data associated with parameter values of the profile predicted by a model is compared to measured data in order to arrive at values of the parameters. Film layers over or under the periodic structure may also be taken into account. Different radiation parameters such as the reflectivities Rs, Rp and ellipsometric parameters may be used in measuring the diffracting structures and the associated films. Some of the radiation parameters may be more sensitive to a change in the parameter value of the profile or of the films then other radiation parameters.

Abstract: A gallery of seed profiles is constructed and the initial parameter values associated with the profiles are selected using manufacturing process knowledge of semiconductor devices. Manufacturing process knowledge may also be used to select the best seed profile and the best set of initial parameter values as the starting point of an optimization process whereby data associated with parameter values of the profile predicted by a model is compared to measured data in order to arrive at values of the parameters. Film layers over or under the periodic structure may also be taken into account. Different radiation parameters such as the reflectivities Rs, Rp and ellipsometric parameters may be used in measuring the diffracting structures and the associated films. Some of the radiation parameters may be more sensitive to a change in the parameter value of the profile or of the films then other radiation parameters.

Abstract: An overlay target with gratings thereon is illuminated and radiation scattered by the target is imaged onto detectors. A phase difference is then detected between the outputs of the detectors to find the mis-alignment error. In another aspect, an overlay target with gratings or box-in-box structures is illuminated and radiation scattered by the target is imaged onto detectors located away from the specular reflection direction of the illumination in a dark field detection scheme. Medium numerical aperture optics may be employed for collecting the radiation from the overlay target in a bright or dark field configuration so that the system has a larger depth of focus and so that the two structures of the target at different elevations can be measured accurately at the same time. Analytical functions are constructed for the grating type targets. By finding the phase difference between the two gratings at different elevations, misalignment errors can be detected.

Abstract: Arrays of vertical extended cavity surface emitting lasers (VECSELs) are disclosed. The functionality of two or more conventional optical components are combined into an optical unit to reduce the number of components that must be aligned during packaging. A dichroic beamsplitter selectively couples frequency doubled light out of the cavity. In one implementation the dichroic beamsplitter includes at least one prism.

Abstract: A light engine includes a multi-color laser source having a set of semiconductor lasers. A controller synchronizes the operation of the laser source to operate in a color sequential order with a spatial modulator.