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Electrical double layers play a key role in a variety of electrochemical systems. The mean free path of secondary electrons in aqueous solutions is on the order of a nanometer, making them suitable for probing ultrathin electrical double layers at solid–liquid electrolyte interfaces. Employing graphene as an electron-transparent electrode in a two-electrode electrochemical system, we show that the secondary electron yield of the graphene–liquid interface depends on the ionic strength and concentration of the electrolyte and the applied bias at the remote counter electrode. These observations have been related to polarization-induced changes in the potential distribution within the electrical double layer and demonstrate the feasibility of using scanning electron microscopy to examine and map electrified liquid–solid interfaces.

In-line, non-destructive process control metrology of high aspect ratio (HAR) holes and trenches has long been a known gap in metrology. Imaging the bottoms of at-node size contact holes in oxide with aspect rations beyond 10:1 has not yet been demonstrated. Nevertheless, holes and trenches of 30:1, 40:1, or even 60:1 will soon enter production, with these etches being applied to various homogeneous and multi-layer stacks of Si and SiO2. The need comes from Moore's Law and increasing functional density on microchips, on which true 3D memory devices will soon be manufactured. These can take many different forms, but a common building block will be these ultra-HAR etched features. In this work, we show experimental results and simulations from the NIST JMONSEL program to assess the feasibility of measuring such features using both conventional low voltage scanning electron microscopy (SEM) and higher beam energies and low vacuum conditions to ameliorate charging. In our measurements, higher voltage SEM did not improve upon conventional critical dimension (CD)-SEM. Simulations suggest the reason is a failure to overcome a negative oxide potential. Although a signal can in principle be detected from the bottom of contact holes in typical imaging conditions in the CD-SEM, it is likely that it will be very small and possibly below the noise floor.

In this paper, the application of instrumented indentation devices to the measurement of the elastic modulus of polymeric materials is reviewed. This review includes a summary of traditional analyses of load‐penetration data and a discussion of associated uncertainties. Also, the use of scanning probe microscopes to measure the nanoscale mechanical response of polymers is discussed, particularly with regard to the associated limitations. The application of these methods to polymers often leads to measurements of elastic modulus that are somewhat high relative to bulk measurements with potentially artificial trends in modulus as a function of penetration depth. Also, power law fits to indentation unloading curves are often a poor representation of the actual data, and the power law exponents tend to fall outside the theoretical range. These problems are likely caused by viscoelasticity, the effects of which have only been studied recently. Advancement of nanoindentation testing toward quantitative characterization of polymer properties will require material‐independent calibration procedures, polymer reference materials, advances in instrumentation, and new testing and analysis procedures that account for viscoelastic and viscoplastic polymer behavior.

Our world is three-dimensional, and so are the integrated circuits (ICs), they have always been. In the past, for a long time, we have been very fortunate, because it was enough to measure a simple critical dimension (CD), the width of the resist line, to keep IC production under acceptable control. This requirement has changed in the last few years to contour and now to three-dimensional measurements. Optical lithography is printing photoresist features that are significantly smaller than the wavelength of the light used, and therefore it is indispensable to use optical proximity correction (OPC) methods. This includes modeling and compensation for various errors in the lithography process down to sub-nanometer, essentially atomic levels. The process has to rely on sophisticated and complex simulations and on accurate and highly repeatable dimensional metrology. The necessary dimensional metrology is beyond the conventional one-dimensional line width measurements, and must include two - and three-dimensional measurements of the contours and shapes of structures. Contour metrology needs accurate and highly repeatable measurements on sets and individual OPC structures, for which the critical dimension measurement scanning electron microscope (CD-SEM) is the key metrology tool. Three-dimensional (3D) metrology is now indispensable for IC technology, but current metrology tools and methods cannot fulfill the requirements. We believe that with the implementation of new methods it is feasible to develop 3D metrology that will well serve IC production, even on structures in the few nanometer-size range.

The ability of a critical dimension scanning electron microscope (CD-SEM) to resolve differences in the widths of two lines depends on the instrument’s measurement repeatability and any sample-dependent biases. The dependence of repeatability and bias on eight different parameters is studied using the MONSEL Monte Carlo electron simulator. For each of 14,400 different combinations of values of eight parameters, three describing the sample and five describing characteristics of the instrument or measurement condition, an image is simulated, noise is added, and the edge positions are “measured” as would be done in a CD-SEM. From 100 repetitions of noise, the repeatability of such CD determinations is ascertained. Biases (i.e., average errors) are also determined. Noise amplitude, edge detection algorithm, and beam size are shown to be significant factors in measurement repeatability. The CD-SEM’s measurement repeatability may be an order of magnitude better than its spatial resolution. For standard edge detection methods, the bias depends on the sample. This means that in a manufacturing environment in which the sample shape varies, there will be a random component of error that is not measured by the industry’s usual same-sample tests of instrument precision.

The ability of a critical dimension scanning electron microscope (CD-SEM) to resolve differences in the widths of two lines depends on the instrument’s measurement repeatability and any sample-dependent biases. The dependence of repeatability and bias on eight different parameters is studied using the MONSEL Monte Carlo electron simulator. For each of 14,400 different combinations of values of eight parameters, three describing the sample and five describing characteristics of the instrument or measurement condition, an image is simulated, noise is added, and the edge positions are “measured” as would be done in a CD-SEM. From 100 repetitions of noise, the repeatability of such CD determinations is ascertained. Biases (i.e., average errors) are also determined. Noise amplitude, edge detection algorithm, and beam size are shown to be significant factors in measurement repeatability. The CD-SEM’s measurement repeatability may be an order of magnitude better than its spatial resolution. For standard edge detection methods, the bias depends on the sample. This means that in a manufacturing environment in which the sample shape varies, there will be a random component of error that is not measured by the industry’s usual same-sample tests of instrument precision.