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We demonstrate temporally multiplexed multibeam ptychography implemented for the first time in the EUV, by using a high harmonic based light source. This allows for simultaneous imaging of different sample areas, or of the same area at different times or incidence angles. Furthermore, we show that this technique is compatible with wavelength multiplexing for multibeam spectroscopic imaging, taking full advantage of the temporal and spectral characteristics of high harmonic light sources. This technique enables increased data throughput using a simple experimental implementation and with high photon efficiency.

Recent advances in structured illumination are enabling a wide range of applications from imaging to metrology, which can benefit from advanced beam characterization techniques. Solving uniquely for the spatial distribution of polarization in a beam typically involves the use of two or more polarization optics, such as a polarizer and a waveplate, which is prohibitive for some wavelengths outside of the visible spectrum. We demonstrate a technique that circumvents the use of a waveplate by exploiting extended Gerchberg–Saxton phase retrieval to extract the phase. The technique enables high-resolution, wavefront-sensing, full-field polarimetry capable of solving for both simple and exotic polarization states, and moreover, is extensible to shorter wavelength light.

Multiple beam ptychographic imaging with an extreme ultraviolet high harmonic light source is demonstrated through simultaneous spectral and temporal multiplexing. This method is experimentally straightforward to implement and ideal for hyperspectral functional imaging of nanosystems

Coherent Fourier scatterometry (CFS) via laser beams with a Gaussian spatial profile is routinely used as an in-line inspection tool to detect defects on, for example, lithographic substrates, masks, reticles, and wafers. New metrology techniques that enable high-throughput, high-sensitivity, and in-line inspection are critically in need for next-generation high-volume manufacturing including those based on extreme ultraviolet (EUV) lithography. Here, a set of novel defect inspection techniques are proposed and investigated numerically [Wang et al., Opt. Express 29, 3342 (2021)], which are based on bright-field CFS using coherent beams that carry orbital angular momentum (OAM). One of our proposed methods, the differential OAM CFS, is particularly unique because it does not require a pre-established database for comparison in the case of regularly patterned structures with reflection symmetry such as 1D and 2D grating structures. We studied the performance of these metrology techniques on both amplitude and phase defects. We demonstrated their superior advantages, which shows up to an order of magnitude higher in signal-to-noise ratio over the conventional Gaussian beam CFS. These metrology techniques will enable higher sensitivity and robustness for in-line nanoscale defect inspection. In general, our concept could benefit EUV and x-ray scatterometry as well.

We report simulations of nonlinear post-compression in multi-pass cells in the anomalous dispersion regime. By solving the nonlinear Schrödinger equation and mapping the parameter space we uncover regimes of self-compression, temporal soliton and modulation instabilities.

Coherent Fourier scatterometry (CFS) using laser beams with a Gaussian spatial profile is routinely used as an in-line inspection tool in semiconductor industry. Here, a set of novel defect inspection techniques are proposed and investigated numerically, which are based on bright-field CFS using coherent beams that carry orbital angular momentum (OAM). Through numerical simulations, we demonstrated that it shows up to an order of magnitude higher in signal-to-noise ratio over the conventional Gaussian beam CFS.

An analysis of blind ptychography that provides predictions of error and the reconstructed field-of-view (FOV) is presented. The utility of this analysis is demonstrated with a new approach called dual-grid ptychography that maximizes the FOV.

A new imaging technique enables nondestructive, 3D characterization of nanostructures, their composition, and interfaces., Next-generation nano- and quantum devices have increasingly complex 3D structure. As the dimensions of these devices shrink to the nanoscale, their performance is often governed by interface quality or precise chemical or dopant composition. Here, we present the first phase-sensitive extreme ultraviolet imaging reflectometer. It combines the excellent phase stability of coherent high-harmonic sources, the unique chemical sensitivity of extreme ultraviolet reflectometry, and state-of-the-art ptychography imaging algorithms. This tabletop microscope can nondestructively probe surface topography, layer thicknesses, and interface quality, as well as dopant concentrations and profiles. High-fidelity imaging was achieved by implementing variable-angle ptychographic imaging, by using total variation regularization to mitigate noise and artifacts in the reconstructed image, and by using a high-brightness, high-harmonic source with excellent intensity and wavefront stability. We validate our measurements through multiscale, multimodal imaging to show that this technique has unique advantages compared with other techniques based on electron and scanning probe microscopies.

We present a versatile, ptychographic phase-sensitive imaging EUV reflectometer that can nondestructively image samples with spatial, depth and compositional resolution, with sensitivities to dopant levels and interface quality.

Coherent diffractive imaging of periodic samples is demonstrated with a tabletop, 13.5 nm high-harmonic source. With a novel image reconstruction technique, the record high spatial resolution of 12.6 nm is achieved in the extreme-ultraviolet region.

We demonstrate the first stroboscopic full-field EUV nanoscope using high harmonics. We image the propagation of thermal and surface acoustic waves in nickel with 80nm transverse, 0.5 Å axial, and 10 fs resolution.

We present a tabletop-scale complex-imaging EUV reflectometer that uses grazing- incidence ptychographic imaging to non-destructively determine depth-dependent, spatially-resolved composition with high sensitivity to chemical makeup, thin film layer thickness, interface quality and dopant profiles.

The influence of surface and interface roughness on X-ray and extreme ultraviolet (EUV) reflectometry is becoming increasingly important as layer thicknesses decrease to a few nanometers in next-generation nanodevices and multilayer optics. Here we simulate two different approaches for numerically modeling roughness, the Névot–Croce factor and the graded-interface method, in the Parratt formalism of calculating the complex reflectance of multilayer systems. The simulations were carried out at wavelengths relevant to widely used metrology techniques, including 0.154 nm for X-ray reflectometry and 13.5 nm for EUV lithography. A large discrepancy is observed between the two approaches in several situations: when the roughness is large with respect to the wavelength, for interfaces with large changes in refractive index across the boundary, as well as around reflectance peaks due to interference effects. Caution is thus required when using either approach to model roughness in these situations.

Defect inspection on lithographic substrates, masks, reticles, and wafers is an important quality assurance process in semiconductor manufacturing. Coherent Fourier scatterometry (CFS) using laser beams with a Gaussian spatial profile is the standard workhorse routinely used as an in-line inspection tool to achieve high throughput. As the semiconductor industry advances toward shrinking critical dimensions in high volume manufacturing using extreme ultraviolet lithography, new techniques that enable high-sensitivity, high-throughput, and in-line inspection are critically needed. Here we introduce a set of novel defect inspection techniques based on bright-field CFS using coherent beams that carry orbital angular momentum (OAM). One of these techniques, the differential OAM CFS, is particularly unique because it does not rely on referencing to a pre-established database in the case of regularly patterned structures with reflection symmetry. The differential OAM CFS exploits OAM beams with opposite wavefront or phase helicity to provide contrast in the presence of detects. We numerically investigated the performance of these techniques on both amplitude and phase defects and demonstrated their superior advantages—up to an order of magnitude higher in signal-to-noise ratio—over the conventional Gaussian beam CFS. These new techniques will enable increased sensitivity and robustness for in-line nanoscale defect inspection and the concept could also benefit x-ray scattering and scatterometry in general.

We demonstrate quantitative, chemically specific imaging of buried nanostructures, including oxidation and diffusion reactions at buried interfaces, using nondestructive tabletop extreme ultraviolet (EUV) coherent diffractive imaging (CDI). Copper nanostructures inlaid in SiO2 are coated with 100 nm of aluminum, which is opaque to visible light and thick enough that neither visible microscopy nor atomic force microscopy can image the buried interface. Short wavelength high harmonic beams can penetrate the aluminum layer, yielding high-contrast images of the buried structures. Quantitative analysis shows that the reflected EUV light is extremely sensitive to the formation of multiple oxide layers, as well as interdiffusion of materials occurring at the metal-metal and metal-insulator boundaries deep within the nanostructure with few nanometers precision.

We built a stroboscopic extreme UV microscope with tabletop high harmonics to make nanoscale movies of thermal and acoustic waves., Imaging charge, spin, and energy flow in materials is a current grand challenge that is relevant to a host of nanoenhanced systems, including thermoelectric, photovoltaic, electronic, and spin devices. Ultrafast coherent x-ray sources enable functional imaging on nanometer length and femtosecond timescales particularly when combined with advances in coherent imaging techniques. Here, we combine ptychographic coherent diffractive imaging with an extreme ultraviolet high harmonic light source to directly visualize the complex thermal and acoustic response of an individual nanoscale antenna after impulsive heating by a femtosecond laser. We directly image the deformations induced in both the nickel tapered nanoantenna and the silicon substrate and see the lowest-order generalized Lamb wave that is partially confined to a uniform nanoantenna. The resolution achieved—sub–100 nm transverse and 0.5-Å axial spatial resolution, combined with ≈10-fs temporal resolution—represents a significant advance in full-field dynamic imaging capabilities. The tapered nanoantenna is sufficiently complex that a full simulation of the dynamic response would require enormous computational power. We therefore use our data to benchmark approximate models and achieve excellent agreement between theory and experiment. In the future, this work will enable three-dimensional functional imaging of opaque materials and nanostructures that are sufficiently complex that their functional properties cannot be predicted.

Colloidal crystals with specific electronic, optical, magnetic, vibrational properties, can be rationally designed by controlling fundamental parameters such as chemical composition, scale, periodicity and lattice symmetry. In particular, silica nanospheres -which assemble to form colloidal crystals- are ideal for this purpose, because of the ability to infiltrate their templates with semiconductors or metals. However characterization of these crystals is often limited to techniques such as grazing incidence small-angle scattering that provide only global structural information and also often require synchrotron sources. Here we demonstrate small-angle Bragg scattering from nanostructured materials using a tabletop-scale setup based on high-harmonic generation, to reveal important information about the local order of nanosphere grains, separated by grain boundaries and discontinuities. We also apply full-field quantitative ptychographic imaging to visualize the extended structure of a silica close-packed nanosphere multilayer, with thickness information encoded in the phase. These combined techniques allow us to simultaneously characterize the silica nanospheres size, their symmetry and distribution within single colloidal crystal grains, the local arrangement of nearest-neighbor grains, as well as to quantitatively determine the number of layers within the sample. Key to this advance is the good match between the high harmonic wavelength used (13.5nm) and the high transmission, high scattering efficiency, and low sample damage of the silica colloidal crystal at this wavelength. As a result, the relevant distances in the sample - namely, the interparticle distance (≈124nm) and the colloidal grains local arrangement (≈1μm) – can be investigated with Bragg coherent EUV scatterometry and ptychographic imaging within the same experiment simply by tuning the EUV spot size at the sample plane (5μm and 15μm respectively). In addition, the high spatial coherence of high harmonics light, combined with advances in imaging techniques, makes it possible to image near-periodic structures quantitatively and nondestructively, and enables the observation of the extended order of quasi-periodic colloidal crystals, with a spatial resolution better than 20nm. In the future, by harnessing the high time-resolution of tabletop high harmonics, this technique can be extended to dynamically image the three-dimensional electronic, magnetic, and transport properties of functional nanosystems.

With increasingly 3D devices becoming the norm, there is a growing need in the semiconductor industry and in materials science for high spatial resolution, non-destructive metrology techniques capable of determining depth-dependent composition information on devices. We present a solution to this problem using ptychographic coherent diffractive imaging (CDI) implemented using a commercially available, tabletop 13 nm source. We present the design, simulations, and preliminary results from our new complex EUV imaging reflectometer, which uses coherent 13 nm light produced by tabletop high harmonic generation. This tool is capable of determining spatially-resolved composition vs. depth profiles for samples by recording ptychographic images at multiple incidence angles. By harnessing phase measurements, we can locally and nondestructively determine quantities such as device and thin film layer thicknesses, surface roughness, interface quality, and dopant concentration profiles. Using this advanced imaging reflectometer, we can quantitatively characterize materials-sciencerelevant and industry-relevant nanostructures for a wide variety of applications, spanning from defect and overlay metrology to the development and optimization of nano-enhanced thermoelectric or spintronic devices.

Using a tabletop coherent extreme ultraviolet source, we extend current nanoscale metrology capabilities with applications spanning from new models of nanoscale transport and materials, to nanoscale device fabrication. We measure the ultrafast dynamics of acoustic waves in materials; by analyzing the material’s response, we can extract elastic properties of films as thin as 11nm. We extend this capability to a spatially resolved imaging modality by using coherent diffractive imaging to image the acoustic waves in nanostructures as they propagate. This will allow for spatially resolved characterization of the elastic properties of non-isotropic materials.

We report the first stroboscopic full-field EUV microscope using high harmonics. Specifically, we demonstrate nanoscale movies of acoustic wave propagation in nanostructures with ≈0.1nm axial resolution, 90nm lateral resolution, and 10fs time resolution.

We demonstrate high-resolution and wide field-of-view imaging using tabletop 13nm HHG sources in transmission and reflection geometries. Additionally, we present preliminary simulations and results of complex 13nm imaging reflectometry allowing highly-sensitive, non-destructive 3D composition determination.

EUV lithography is promising for addressing upcoming

We demonstrate the first reflection-mode, tabletop imaging using 12.7nm illumination via ptychography. This is the first reflection-mode image using any ~13nm source of a general sample. We utilize glancing incidence-angles to obtain a large field-of-view.

We report the first dynamic (i.e. stroboscopic), full field, tabletop extreme ultraviolet microscope. This new capability allows us to image longitudinal and transverse acoustic waves in laser-excited Nickel nano-grating on Silicon substrates.

We report the first stroboscopic full-field EUV microscope using high harmonics. Specifically, we demonstrate nanoscale movies of thermal and acoustic wave propagation in nanostructures with 0.1nm axial resolution, 90nm lateral resolution, and 10fs time resolution.

We demonstrate the first general, sub-wavelength EUV diffraction imaging results using a 13.5nm high-harmonic light source. A novel modulus enforced probe technique is developed and implemented allowing quantitative imaging of nearly periodic objects.

By combining tabletop 13.5nm high-harmonic EUV beams with novel ptychography reconstruction algorithms, we demonstrate diffraction-limit high-NA and sub-wavelength resolution imaging at EUV wavelengths for the first time, representing a record resolution for full-field light-based microscopy.

The ability to record large field-of-view images without a loss in spatial resolution is of crucial importance for imaging science. For most imaging techniques however, an increase in field-of-view comes at the cost of decreased resolution. Here we present a novel extension to ptychographic coherent diffractive imaging that permits simultaneous full-field imaging of multiple locations by illuminating the sample with spatially separated, interfering probes. This technique allows for large field-of-view imaging in amplitude and phase while maintaining diffraction-limited resolution, without an increase in collected data i.e. diffraction patterns acquired.

We use EUV coherent microscopy to obtain high-resolution images of buried interfaces, with chemical specificity, in 2+1 dimensions. We perform reflection mode, ptychographic, coherent diffractive imaging with tabletop EUV light, at 29nm, produced by high harmonic generation. Our damascene-style samples consist of copper structures inlaid in SiO2, polished nearly flat with chemical mechanical polishing. We obtain images of both an unaltered damascene as well as one buried below a 100nm thick layer of evaporated aluminum. The aluminum is opaque to visible light and thick enough that neither optical microscopy, SEM, nor AFM can access the buried interface. EUV microscopy is able to image the buried structures, non-destructively, in conditions where other techniques cannot.

We present an extension to ptychography that allows simultaneous deconvolution of multiple, spatially separate, illuminating probes. This enables an increased field of view and hence, an increase in imaging throughput, without increased exposure times. This technique can be used for any non-interfering probes: demonstrated with multiple wavelengths and orthogonal polarizations. The latter of which gives us spatially resolved polarization spectroscopy from a single scan.

We demonstrate imaging of optically opaque nanostructures buried beneath a thick layer of aluminum using a tabletop extreme ultraviolet source. Our non-destructive technique uncovers interfacial diffusion and oxidation between layers, validated using destructive techniques.

We demonstrate a record near-wavelength limited 17.5nm spatial resolution for EUV imaging using ptychographic coherent diffractive imaging with illumination at 13.5nm from a high-harmonic light source.

We demonstrate a record sub-wavelength 12.6nm spatial resolution for EUV imaging using 13.5nm illumination from a high-harmonic light source. Modulus enforced probe ptychographic coherent diffractive imaging allows for large-field quantitative imaging of near-periodic objects.

We present an extension of ptychography coherent diffractive imaging that enables simultaneous imaging of several areas of an extended sample using multiple, spatially separated interfering beams. We show that this technique will increase the throughput of an imaging system by a factor that is equal to the number of beams used. This allows for the acquisition of large field of view images with near diffraction-limited resolution without an increase in data acquisition. This represents a significant step towards large field of view, high resolution imaging in the EUV and x-ray energy regimes.

We use reflection-mode ptychography CDI with HHG illumination to image copper nanostructures buried beneath 100nm of aluminum. Our technique yields absolute reflectivity images, allowing non-destructive detection of diffusion at the Al-Cu boundary, confirmed by Auger-Electron-Spectroscopy.

Lensless imaging with short-wavelength light is a promising method for achieving high-resolution, chemically sensitive images of a wide variety of samples. The use of 13 nm illumination is of particular interest for materials science and the imaging of next-generation nanofabricated devices. Prior to this work, there was an unmet need for a microscope that can image general samples with extreme ultraviolet light, which requires a reflection geometry. Here, we fulfill this need by performing lensless imaging using a 13 nm high-harmonic beam at grazing incidence, where most materials are reflective. Furthermore, we demonstrate to our knowledge the first 13 nm reflection-mode lensless microscope on a tabletop by using a compact high-harmonic generation source. Additionally, we present an analytic formalism that predicts when general lensless imaging geometries will yield Nyquist sampled data. Our grazing-incidence ptychographic approach, which we call GLIDER, provides the first route for achieving wide field-of-view, high-resolution, lensless images of general samples with extreme ultraviolet and soft x-ray light.

We image a nanostructured sample through a visibly-opaque 100nm layer of aluminum using lensless Fresnel Ptychography and a tabletop high harmonic source. The reconstructed amplitude-contrast image uncovered the presence of interfacial diffusion non-destructively.

We achieve high-contrast, 3D surface topographic imaging with a lateral resolution of 1.3λ and with 6A axial precision using ptychographic coherent diffraction imaging and a high-harmonic source at 30nm.

Spectronanoscopy of buried structures and interfaces is an important challenge for many applications including nanofabrication of multilayers and devices for data storage and nanoelectronics. Here we use ptychographic coherent diffractive imaging (CDI)in a reflection geometry with a tabletophigh harmonic generation (HHG) source to perform quantitativechemical specific imaging of buried nanostructures and interfaces.

We introduce a novel coherent diffraction imaging technique based on ptychography that enables simultaneous full-field imaging of multiple, spatially separate, sample locations. This technique only requires that diffracted light from spatially separated sample sites be mutually incoherent at the detector, which can be achieved using multiple probes that are separated either by wavelength or by orthogonal polarization states. This approach enables spatially resolved polarization spectroscopy from a single ptychography scan, as well as allowing a larger field of view to be imaged without loss in spatial resolution. Further, we compare the numerical efficiency of the multi-mode ptychography algorithm with a single mode algorithm.

We extend ptychography CDI to allow for imaging of multiple areas on a sample simultaneously using multiple identical beams. This enables high throughput imaging of large samples without increased data collection or loss in resolution.