An approach was presented to fabricate wafer-scale nanoring structures based on nanopillar array templates fabricated by nanoimprint lithography. This fabrication method combined UV-curing nanolithography technology, metal deposition, and an etching process, which made it possible to tune the geometric properties of nanorings: height, diameter, and linewidth for various materials, such as Au and Ni. Nanoring arrays showed potential applications in many fields, including memory storage, biosensing, and optical devices. The optical measurement of Au nanorings (d=380  nm) showed its strong transmission resonances at the wavelength of 2.1  μm. A modified version of this fabrication method by depositing Ni in a controlled angle as a sacrificial layer was also utilized to create nanocrescent arrays. This modified method could easily tune the width of crescents through the nickel deposition angles and nanopillar template heights. The large-area gold nanocrescent arrays showed strong polarization-dependent transmission bands. Plasmonic crescent structures were expected to apply in infrared metamaterial and chemical sensing.

As extreme ultraviolet lithography becomes closer to reality for high volume production, its peculiar modeling challenges related to both inter and intrafield effects have necessitated building an optical proximity correction (OPC) infrastructure that operates with field position dependency. Previous state-of-the-art approaches to modeling field dependency used piecewise constant models where static input models are assigned to specific x/y-positions within the field. OPC and simulation could assign the proper static model based on simulation-level placement. However, in the realm of 7 and 5 nm feature sizes, small discontinuities in OPC from piecewise constant model changes can cause unacceptable levels of edge placement errors. The introduction of dynamic model generation (DMG) can be shown to effectively avoid these dislocations by providing unique mask and optical models per simulation region, allowing a near continuum of models through the field. DMG allows unique models for electromagnetic field, apodization, aberrations, etc. to vary through the entire field and provides a capability to precisely and accurately model systematic field signatures.

Graphoepitaxy directed self-assembly is a potential low-cost solution for patterning via layers with pitches beyond the reach of a single optical lithographic exposure. In this process, selective control of the interfacial energy at the bottom and sidewall of the template is an important but challenging exercise. A dual brush process is implemented, in which two brushes with distinct end-groups are consecutively grafted to the prepattern to achieve fully independent modification of the bottom and sidewall surface of the template. A comprehensive study of hole pattern quality shows that using a dual brush process leads to a substantial improvement in terms of positional and dimensional variability across the process window. These findings will be useful to others who wish to manipulate polymer–surface interactions in directed self-assembly flows.

Line-edge roughness (LER) has important impacts on the quality of semiconductor device performance, and power spectrum estimates are useful tools in characterizing it. These estimates are often obtained by taking measurements of many lines and averaging a classical power spectrum estimate from each one. While this approach reduces the uncertainty of the estimates, there are disadvantages to the collection of many measurements. We propose techniques with widespread application in other fields that simultaneously reduce data requirements and the uncertainty of LER power spectrum estimates over current approaches at the price of computational complexity. Multitaper spectral analysis uses an orthogonal collection of data windowing functions or tapers to obtain a set of approximately statistically independent spectrum estimates. The Welch overlapped segment averaging is an earlier approach to reduce the uncertainty of power spectrum estimates. There are known techniques to evaluate the uncertainty of power spectrum estimates. We simulate random rough lines using the Thorsos method.

We report our findings in developing a low-power etching recipe using a newly acquired reactive-ion etching (RIE) tool (RIE-10NR, Samco, Japan), with the aim of achieving smooth and vertical sidewalls in micropatterned silicon substrate. We used a combination of CF4, SF6, and O2 gases, which at low power (30 W) and low pressure (2 Pa) allowed for vertical silicon etching (aspect ratio ∼2). We used photoresist and silicon oxide as the etching masks. As it is a continuous etching process, scalloping effects were not present, which is contrary to the process done with an inductively coupled plasma-based “Bosch” approach. We also show a successful use of these microstructures as master mold in soft-lithographic techniques for producing devices in elastomeric materials that have applications in mechanobiology. To the best of our knowledge, the recipe we present here has the lowest combination of power and pressure for etching silicon with vertical profile using a standard, parallel plates RIE tool.

The parallel plate capacitive humidity sensor based on the grid upper electrode is considered to be a promising one in some fields which require a humidity sensor with better dynamic characteristics. To strengthen the structure and balance the electric charge of the grid upper electrode, a strip is needed. However, it is the strip that keeps the dynamic characteristics of the sensor from being further improved. The numerical method is time- and cost-saving, but the numerical study on the response time of the sensor is just of bits and pieces. The numerical models presented by these studies did not consider the porosity effect of the polymer film on the dynamic characteristics. To overcome the defect of the grid upper electrode, a new structure of the upper electrode is provided by this paper first, and then a model considering the porosity effects of the polymer film on the dynamic characteristics is presented and validated. Finally, with the help of software FLUENT, parameter effects on the response time of the humidity sensor based on the microhole upper electrode are studied by the numerical method. The numerical results show that the response time of the microhole upper electrode sensor is 86% better than that of the grid upper electrode sensor, the response time of humidity sensor can be improved by reducing the hole spacing, increasing the aperture, reducing film thickness, and reasonably enlarging the porosity of the film.

We report the nanofabrication and characterization of x-ray transmission gratings with a high aspect ratio and a feature size of down to 65 nm. Two nanofabrication methods, the combination of electron beam and optical lithography and the combination of electron beam, x-ray, and optical lithography, are presented in detail. In the former approach, the proximity effect of electron beam lithography based on a thin membrane of low-z material was investigated, and the x-ray transmission gratings with a line density of up to 6666  lines/mm were demonstrated. In the latter approach, which is suitable for low volume production, we investigated the x-ray mask pattern correction during the electron beam lithography process and the diffraction effect between the mask and wafer during the x-ray lithography process, and we demonstrated the precise control ability of line width and vertical side-wall profile. A large number of x-ray transmission gratings with a line density of 5000  lines/mm and Au absorber thickness of up to 580 nm were fabricated. The optical characterization results of the fabricated x-ray transmission gratings were given, suggesting that these two reliable approaches also promote the development of x-ray diffractive optical elements.

A capacitive tactile sensor comprising two capacitors was developed to enhance detection by more than doubling the spatial resolution. This arrangement reduced the number of required capacitors from four to two and reconfigured the capacitor shape from square to rectangular, resulting in a symmetric spatial resolution in the x- and y-directions. The theoretical evaluations, simulation predictions, device fabrication, and data analysis conducted in this study yielded identical results. In addition, angle detection errors resulting from fabrication and material uncertainties were comprehensively examined for the first time. The evaluations performed regarding the capacitor configuration further indicated that the sensitivity of shear force detection in this study was optimized with the requirement of a symmetric design.

The output of one typical capacitive microelectromechanical system (MEMS) accelerometer under square wave bias voltage is discussed. Output drift of the accelerometers should be suppressed to improve the device performance. Theoretical analysis indicates that square wave bias voltage can be applied instead of the DC bias voltage to mitigate the dielectric charging-induced output drift. Theoretical models of the sensing structure under square wave bias voltage indicate that both square wave and DC bias voltage can generate the same electrostatic force among the sensing structure. Therefore, the system equilibrium can be maintained with square wave bias voltage when the same input acceleration is applied. Configuration and the frequency of the square wave bias voltage are analyzed to maintain the system equilibrium and device function. Experimental results show that although the magnitude of the output voltage is slightly decreased, output drift can be significantly suppressed when the square wave voltage is applied.