X-Ray Lithography for Nanofabrication: Is There a Future?

X-ray lithography has been first proposed almost 50 years ago, and the related LIGA process around 25 years ago. It is therefore a good time to make an analysis of the technique, with its pros and cons. In this perspective article, we describe X-ray lithography’s latest advancements. First, we report the improvement in the fabrication of the high aspect ratio and high-resolution micro/nanostructures. Then, we present the radiation-assisted synthesis and processing of novel materials for the next generation of functional devices. We finally draw our conclusion on the future prospects of the technique.

Photo: (A) Scheme of the beam scan method. The exposure stage (assembly of mask and sample) is moved with respect to the beam during exposure. (B) Scheme of the multiple mask lithography, where superimposed masks are moved while irradiating. The idea comes from Moser et al. (2012). (C) Examples of 3D structures obtained with XRL. (c1) 3D Microneedle fabricated using three aligned exposures of which two are dynamic by moving an obelisk-shaped absorber mask (shown in the inset) first in one direction, and then at 90° on the same plane. In this way, the pyramid needle is obtained. A third static exposure is performed to obtain the needle hole. Adapted from Wang et al. (2021) (c2) Oblique submicron structures of a 10-μm period at 20° obtained with a slanted mask and exposure (shown in the inset). Adapted from Kim et al. (2021). (c3) Step-like microstructures with height 250 and 150 µm obtained by changing the absorber thickness of the mask. Adapted from Nazmov et al. (2020) with permission of AIP Publishing.

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