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 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 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:
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 metrology system is disclosed. In one embodiment, the metrology system includes a controller communicatively coupled to a reference metrology tool and an optical metrology tool, the controller including one or more processors configured to: generate a geometric model for determining a profile of a test HAR structure from metrology data from a reference metrology tool; generate a material model for determining one or more material parameters of a test HAR structure from metrology data from the optical metrology tool; form a composite model from the geometric model and the material model; measure at least one additional test HAR structure with the optical metrology tool; and determine a profile of the at least one additional test HAR structure based on the composite model and metrology data from the optical metrology tool associated with the at least one HAR test structure.
Abstract:
An overlay metrology system may include a controller to generate optical tool error adjustments for a hybrid overlay target including optically-resolvable features and device-scale features by measuring a difference between an optical overlay measurement based on the optically-resolvable features and a device-scale overlay measurement based on the device-scale features, generate target-to-device adjustments for the hybrid overlay target based on positions of features within the device area, determine device-relevant overlay measurements for one or more locations in the device area based on at least one of the optical overlay measurement, the optical tool error adjustments, or the target-to-device adjustments, and provide overlay correctables for the device area to a lithography tool to modify exposure conditions for at least one subsequent exposure based on the device-relevant overlay measurements.
Abstract:
Methods and systems for characterizing dimensions and material properties of high aspect ratio, vertically manufactured devices using transmission, small-angle x-ray scattering (T-SAXS) techniques are described herein. Exemplary structures include spin transfer torque random access memory (STT-RAM), vertical NAND memory (V-NAND), dynamic random access memory (DRAM), three dimensional FLASH memory (3D-FLASH), resistive random access memory (Re-RAM), and PC-RAM. In one aspect, T-SAXS measurements are performed at a number of different orientations that are more densely concentrated near the normal incidence angle and less densely concentrated at orientations that are further from the normal incidence angle. In a further aspect, T-SAXS measurement data is used to generate an image of a measured structure based on the measured intensities of the detected diffraction orders. In another further aspect, a metrology system is configured to generate models for combined x-ray and optical measurement analysis.
Abstract:
Methods and systems for solving measurement models of complex device structures with reduced computational effort are presented. In some embodiments, a measurement signal transformation model is employed to compute transformed measurement signals from coarse measurement signals. The transformed measurement signals more closely approximate a set of measured signals than the coarse measurement signals. However, the coarse set of measured signals are computed with less computational effort than would be required to directly compute measurement signals that closely approximate the set of measured signals. In other embodiments, a measurement signal transformation model is employed to compute transformed measurement signals from actual measured signals. The transformed measurement signals more closely approximate the coarse measurement signals than the actual measured signals. Transformed measurement signals are subsequently used for regression, library generation, or other analyses typically employed as part of an effort to characterize structural, material, and process parameters in semiconductor manufacturing.
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. In other examples, measurement sensitivity is improved and parameter correlation is reduced.
Abstract:
Methods and systems for performing in-situ, selective spectral reflectometry (SSR) measurements of semiconductor structures disposed on a wafer are presented herein. Illumination light reflected from a wafer surface is spatially imaged. Signals from selected regions of the image are collected and spectrally analyzed, while other portions of the image are discarded. In some embodiments, a SSR includes a dynamic mirror array (DMA) disposed in the optical path at or near a field plane conjugate to the surface of the semiconductor wafer under measurement. The DMA selectively blocks the undesired portion of wafer image. In other embodiments, a SSR includes a hyperspectral imaging system including a plurality of spectrometers each configured to collect light from a spatially distinct area of a field image conjugate to the wafer surface. Selected spectral signals associated with desired regions of the wafer image are selected for analysis.