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Resist sidewall slopes frequently need to be adjusted in micro- and nanofabrication. In this paper, the authors present a straightforward approach to adjust sidewall slopes by using electron beam lithography and applying a background dose in addition to the feature dose. The underlying effect is attributed to an inhomogeneous energy deposition along the resist depth, for which a three-dimensional point spread function is necessary to correctly describe the energy deposition in the resist even for large acceleration voltages and thin resist films. This enables adjacent features with different positive or different negative slopes within a single lithographic step. Corresponding experimental results obtained with the two positive tone resists poly(methyl methacrylate) and ZEP520A are shown, and their opposed sidewall behavior is explained. Moreover, a customized contrast curve is discussed that can, in theory, be used to achieve resist profiles with positive and negative slopes for the same resist. Therefore, a full range tuning on the same substrate becomes feasible. [ABSTRACT FROM AUTHOR]

We report the fabrication and field emission properties of high-density nano-emitter arrays with on-chip electron extraction gate electrodes and up to 106 metallic nanotips that have an apex curvature radius of a few nanometers and a the tip density exceeding 108 cm−2. The gate electrode was fabricated on top of the nano-emitter arrays using a self-aligned polymer mask method. By applying a hot-press step for the polymer planarization, gate–nanotip alignment precision below 10 nm was achieved. Fabricated devices exhibited stable field electron emission with a current density of 0.1 A cm−2, indicating that these are promising for applications that require a miniature high-brightness electron source. [ABSTRACT FROM AUTHOR]

Abstract: We present the fabrication of large nanodot arrays with very small single dot sizes made of different metals and on different substrates using e-beam lithography and lift-off techniques. Nanodot arrays have a high potential for bioanalytical applications aiming towards single molecule detection. In addition, they can be used as well defined models of heterogeneous catalysts. For this purpose an independent control of the dot size and the distance between the dots is necessary. This is a limitation for many fabrication techniques, which can be overcome by e-beam lithography. However, aiming for the dot size of few tens of nanometers, we observed a strong influence of the beam focusing and astigmatism on the quality of the fabricated nanodot arrays. A significant improvement, i.e. reduction of defect density as well as better control of the dot size, was achieved by modification of the fine focus and stigmation system of the used e-beam writer. Using lift-off technique, we successfully fabricated platinum dot arrays on glassy carbon with target dot diameter ranging from 25 to 35nm. By applying additional annealing step, we could fabricate nanodot arrays made of gold on SiO2 with very small dot sizes down to 6nm and pitch of 100nm. Furthermore, the generation of large area arrays of nanosized pillars was demonstrated using the same exposure strategy in a negative tone HSQ resist. [Copyright &y& Elsevier]

Abstract High quality gratings are among the key elements for successful imaging with X-ray grating interferometry. Grating fabrication, specifically of absorption gratings, with high aspect ratio and large area, is a great challenge from a microfabrication point of view. In this paper the fabrication of absorption gratings by seedless electroplating of gold in high aspect ratio silicon moulds that are fabricated by deep reactive ion etching (Bosch process) is presented. We report on our latest results and discuss the possibility of reducing the grating period down to 1.3 μ m. In addition, the quality of the gratings is assessed by performing visibility measurements and imaging various samples on a compact in house X-ray grating interferometer. [ABSTRACT FROM AUTHOR]