Proton Beam Writing Device Based on Electrostatic Accelerator for 3D Micro- and Nano-Structure Fabrication

Abstract

Surface micro-and nanostructures have been being used in various physical applications such as Х-ray optics, photonics, microelectromechanical systems, metamaterials, etc. Problem Statement. The existing methods for fabricating such structures either are expensive or do not meet certain requirements (the aspect ratio and the quality of side wall surface). Purpose. To create a device for proton beam writing, which enables fabricating surface micro-and nanostructures with required parameters. Materials and Methods. One of alternative methods for fabricating the mentioned surface structures is proton beam writing. Silicon substrates coated with a positive resistive polymethyl methacrylate layer are used as samples for fabricating the surface structures. Results. A proton-beam lithography device based on an electrostatic accelerator has been developed, the configuration and specifications have been presented. The main parameters (demagnifications, proton beam current, and minimum probe dimensions) have been specified. Advantages of using quadrupole optics in fabricating micro-diffraction gratings have been shown. The first experiments on fabrication of source grating in X-ray phase-contrast tomographs with a characteristic line width of about 20 μm have been carried out. Conclusions. A new probe-forming system based on a separated magnetic quadrupole lense pentuplet has been used in the proposed device. The use of an electrostatic scanning system ensures a high accuracy of positioning the focused beam in a closed scanning cycle. The scanning process is controlled using a multifunctional reconfigurable input-output module with programmable logic. K e y w o r d s : proton beam writing, electrostatic accelerator, and magnetic quadrupole lens.