Abstract: The system includes a modulatable illumination source configured to illuminate a surface of a sample disposed on a sample stage, a detector configured to detect illumination emanating from a surface of the sample, illumination optics configured to direct illumination from the modulatable illumination source to the surface of the sample, collection optics configured to direct illumination from the surface of the sample to the detector, and a modulation control system communicatively coupled to the modulatable illumination source, wherein the modulation control system is configured to modulate a drive current of the modulatable illumination source at a selected modulation frequency suitable for generating illumination having a selected coherence feature length. In addition, the present invention includes the time-sequential interleaving of outputs of multiple light sources to generate periodic pulse trains for use in multi-wavelength time-sequential optical metrology.

Abstract: Methods and systems for optimizing measurement system parameter settings of an x-ray based metrology system are presented. X-ray based metrology systems employing an optimized set of measurement system parameters are used to measure structural, material, and process characteristics associated with different semiconductor fabrication processes with greater precision and accuracy. In one aspect, a set of values of one or more machine parameters that specify a measurement scenario is refined based at least in part on a sensitivity of measurement data to a previous set of values of the one or more machine parameters. The refinement of the values of the machine parameters is performed to maximize precision, maximize accuracy, minimize correlation between parameters of interest, or any combination thereof. Refinement of the machine parameter values that specify a measurement scenario can be used to optimize the measurement recipe to reduce measurement time and increase measurement precision and accuracy.

Abstract: The system includes a modulatable illumination source configured to illuminate a surface of a sample disposed on a sample stage, a detector configured to detect illumination emanating from a surface of the sample, illumination optics configured to direct illumination from the modulatable illumination source to the surface of the sample, collection optics configured to direct illumination from the surface of the sample to the detector, and a modulation control system communicatively coupled to the modulatable illumination source, wherein the modulation control system is configured to modulate a drive current of the modulatable illumination source at a selected modulation frequency suitable for generating illumination having a selected coherence feature length. In addition, the present invention includes the time-sequential interleaving of outputs of multiple light sources to generate periodic pulse trains for use in multi-wavelength time-sequential optical metrology.

Abstract: A system for providing illumination to a measurement head for optical metrology is configured to combine illumination beams from a plurality of illumination sources to deliver illumination at one or more selected wavelengths to the measurement head. The intensity and/or spatial coherence of illumination delivered to the measurement head is controlled. Illumination at one or more selected wavelengths is delivered from a broadband illumination source configured for providing illumination at a continuous range of wavelengths.

Abstract: An overlay metrology system includes an overlay metrology tool configurable to generate overlay signals with a plurality of recipes and further directs an illumination beam to an overlay target and collects radiation emanating from the overlay target in response to the at least a portion of the illumination beam to generate the overlay signal with the particular recipe. The overlay metrology system further acquires two or more overlay signals for a first overlay target using two or more unique recipes, subsequently acquires two or more overlay signals for a second overlay target using the two or more unique recipes, determines candidate overlays for the first and second overlay targets based on the two or more overlay signals for each target, and determines output overlays for the first and second overlay targets based on the two or more candidate overlays for each target.

Abstract: A spectroscopic metrology system includes a spectroscopic metrology tool and a controller. The controller generates a model of a multilayer grating including two or more layers, the model including geometric parameters indicative of a geometry of a test layer of the multilayer grating and dispersion parameters indicative of a dispersion of the test layer. The controller further receives a spectroscopic signal of a fabricated multilayer grating corresponding to the modeled multilayer grating from the spectroscopic metrology tool. The controller further determines values of the one or more parameters of the modeled multilayer grating providing a simulated spectroscopic signal corresponding to the measured spectroscopic signal within a selected tolerance. The controller further predicts a bandgap of the test layer of the fabricated multilayer grating based on the determined values of the one or more parameters of the test layer of the fabricated structure.

Abstract: Methods and systems for performing measurements of semiconductor structures based on high-brightness, polychromatic, reflective small angle x-ray scatterometry (RSAXS) metrology are presented herein. RSAXS measurements are performed over a range of wavelengths, angles of incidence, and azimuth angles with small illumination beam spot size, simultaneously or sequentially. In some embodiments, RSAXS measurements are performed with x-ray radiation in the soft x-ray (SXR) region at grazing angles of incidence in the range of 5-20 degrees. In some embodiments, the x-ray illumination source size is 10 micrometers or less, and focusing optics project the source area onto a wafer with a demagnification factor of 0.2 or less, enabling an incident x-ray illumination spot size of less than two micrometers.

Abstract: A system, method and computer program product are provided for combining raw data from multiple metrology tools. Reference values are obtained for at least one parameter of a training component. Signals are collected for the at least one parameter of the training component, utilizing a first metrology tool and a different second metrology tool. Further, at least a portion the signals are transformed into a set of signals, and for each of the at least one parameter of the training component, a corresponding relationship between the set of signals and the reference values is determined and a corresponding training model is created therefrom. Signals from a target component are collected utilizing at least the first metrology tool and the second metrology tool, and each created training model is applied to the signals collected from the target component to measure parametric values for the target component.

Abstract: Methods and systems for estimating values of parameters of interest of actual device structures based on optical measurements of nearby metrology targets are presented herein. High throughput, inline metrology techniques are employed to measure metrology targets located near actual device structures. Measurement data collected from the metrology targets is provided to a trained signal response metrology (SRM) model. The trained SRM model estimates the value of one or more parameters of interest of the actual device structure based on the measurements of the metrology target. The SRM model is trained to establish a functional relationship between actual device parameters measured by a reference metrology system and corresponding optical measurements of at least one nearby metrology target. In a further aspect, the trained SRM is employed to determine corrections of process parameters to bring measured device parameter values within specification.

Abstract: Methods and systems for measuring metrology targets smaller than the illumination spot size employed to perform the measurement are described herein. Collected measurement signals contaminated with information from structures surrounding the target area are reconstructed to eliminate the contamination. In some examples, measurement signals associated one or more small targets and one or more large targets located in close proximity to one another are used to train a signal reconstruction model. The model is subsequently used to reconstruct measurement signals from other small targets. In some other examples, multiple measurements of a small target at different locations within the target are de-convolved to estimate target area intensity. Reconstructed measurement signals are determined by a convolution of the illumination spot profile and the target area intensity. In a further aspect, the reconstructed signals are used to estimate values of parameters of interest associated with the measured structures.

Abstract: In one embodiment, apparatus and methods for determining a parameter of a target are disclosed. A target having an imaging structure and a scatterometry structure is provided. An image of the imaging structure is obtained with an imaging channel of a metrology tool. A scatterometry signal is also obtained from the scatterometry structure with a scatterometry channel of the metrology tool. At least one parameter, such as overlay error, of the target is determined based on both the image and the scatterometry signal.

Abstract: Methods and systems for characterizing dimensions and material properties of semiconductor devices by transmission small angle x-ray scatterometry (TSAXS) systems having relatively small tool footprint are described herein. The methods and systems described herein enable Q space resolution adequate for metrology of semiconductor structures with reduced optical path length. In general, the x-ray beam is focused closer to the wafer surface for relatively small targets and closer to the detector for relatively large targets. In some embodiments, a high resolution detector with small point spread function (PSF) is employed to mitigate detector PSF limits on achievable Q resolution. In some embodiments, the detector locates an incident photon with sub-pixel accuracy by determining the centroid of a cloud of electrons stimulated by the photon conversion event. In some embodiments, the detector resolves one or more x-ray photon energies in addition to location of incidence.

Abstract: Methods and systems for robust overlay error measurement based on a trained measurement model are described herein. The measurement model is trained from raw scatterometry data collected from Design of Experiments (DOE) wafers by a scatterometry based overlay metrology system. Each measurement site includes one or more metrology targets fabricated with programmed overlay variations and known process variations. Each measurement site is measured with known metrology system variations. In this manner, the measurement model is trained to separate actual overlay from process variations and metrology system variations which affect the overlay measurement. As a result, an estimate of actual overlay by the trained measurement model is robust to process variations and metrology system variations. The measurement model is trained based on scatterometry data collected from the same metrology system used to perform measurements. Thus, the measurement model is not sensitive to systematic errors, aysmmetries, etc.

Abstract: Disclosed are apparatus and methods for determining a structure or process parameter value of a target of interest on a semiconductor wafer. A plurality of collection patterns are defined for a spatial light beam controller positioned at a pupil image plane of a metrology tool. For each collection pattern, a signal is collected from a sensor of the metrology tool, and each collected signal represents a combination of a plurality of signals that the spatial light beam controller samples, using each collection pattern, from a pupil image of the target of interest. The collection patterns are selected so that the pupil image is reconstructable based on the collection patterns and their corresponding collection signals. The collected signal for each of the collection patterns is analyzed to determine a structure or process parameter value for the target of interest.

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 are presented to reduce the illumination spot size projected onto a measurement target and associated spillover onto area surrounding a measurement target. In one aspect, a spatial light modulator (SLM) is located in the illumination path between the illumination light source and the measurement sample. The SLM is configured to modulate amplitude, phase, or both, across the path of the illumination light to reduce wavefront errors. In some embodiments, the desired state of the SLM is based on wavefront measurements performed in an optical path of the metrology system. In another aspect, an illumination aperture having an image plane tilted at an oblique angle with respect to a beam of illumination light is employed to overcome defocusing effects in metrology systems that employ oblique illumination of the measurement sample. In some embodiments, the illumination aperture, objective lens, and specimen are aligned to satisfy the Scheimpflug condition.

Abstract: Methods and systems are described herein for producing high radiance illumination light for use in semiconductor metrology based on a confined, sustained plasma. One or more plasma confining circuits introduce an electric field, a magnetic field, or a combination thereof to spatially confine a sustained plasma. The confinement of the sustained plasma decreases the size of the induced plasma resulting in increased radiance. In addition, plasma confinement may be utilized to shape the plasma to improve light collection and imaging onto the specimen. The induced fields may be static or dynamic. In some embodiments, additional energy is coupled into the confined, sustained plasma to further increase radiance. In some embodiments, the pump energy source employed to sustained the plasma is modulated in combination with the plasma confining circuit to reduce plasma emission noise.

Abstract: Methods and systems for evaluating the geometric characteristics of patterned structures are presented. More specifically, geometric structures generated by one or multiple patterning processes are measured by two or more metrology systems in accordance with a hybrid metrology methodology. A measurement result from one metrology system is communicated to at least one other metrology systems to increase the measurement performance of the receiving system. Similarly, a measurement result from the receiving metrology system is communicated back to the sending metrology system to increase the measurement performance of the sending system. In this manner, measurement results obtained from each metrology system are improved based on measurement results received from other cooperating metrology systems. In some examples, metrology capability is expanded to measure parameters of interest that were previously unmeasurable by each metrology system operating independently.

Abstract: Methods and systems for estimating values of parameters of interest based on repeated measurements of a wafer during a process interval are presented herein. In one aspect, one or more optical metrology subsystems are integrated with a process tool, such as an etch tool or a deposition tool. Values of one or more parameters of interest measured while the wafer is being processed are used to control the process itself. The measurements are performed quickly and with sufficient accuracy to enable yield improvement of a semiconductor fabrication process flow. In one aspect, values of one or more parameters of interest are estimated based on spectral measurements of wafers under process using a trained signal response metrology (SRM) measurement model. In another aspect, a trained signal decontamination model is employed to generate decontaminated optical spectra from measured optical spectra while the wafer is being processed.

Abstract: Methods and systems are presented to reduce the illumination spot size projected onto a measurement target and associated spillover onto area surrounding a measurement target. In one aspect, a spatial light modulator (SLM) is located in the illumination path between the illumination light source and the measurement sample. The SLM is configured to modulate amplitude, phase, or both, across the path of the illumination light to reduce wavefront errors. In some embodiments, the desired state of the SLM is based on wavefront measurements performed in an optical path of the metrology system. In another aspect, an illumination aperture having an image plane tilted at an oblique angle with respect to a beam of illumination light is employed to overcome defocusing effects in metrology systems that employ oblique illumination of the measurement sample. In some embodiments, the illumination aperture, objective lens, and specimen are aligned to satisfy the Scheimpflug condition.