Analysis of Electromechanical Deformation of a MEMS Element of a Reflection-Type Dynamic Mask Based on a Torsional Micromirror

At present, the concept of X-ray nanolithography seems to be particularly attractive for creating nanostructures with a lateral size down to 13 nm and below. To dynamically change the pattern, an “electronic” mask with a set of MEMS-based elements can be used that redirect X-rays towards the projection lens and are responsible for the formation of a single image pixel on the substrate. The role of such MEMS elements can be performed by a matrix of torsional micromirrors, the electromechanical control of which manipulates the angle of reflection of the incident X-ray radiation from the micromirror surface and ensures the transfer of a given pattern to the X-ray resist. In this work, a numerical analysis of the electromechanical deformation of a torsional micromirror based on Mo/Si multilayer membranes was performed. It was shown that the rotation of the micromirror to a stable state (by an angle of about 5°) to effectively reflect X-Ray radiation occurs at a voltage of less than 15 V for a time of $150 \mu \mathrm{s}$. The maximum temperature of the reflecting micromirror surface at a 0.1 ns X-ray pulse with a wavelength of 13.5 nm does not exceed $220^{\circ} \mathrm{C}$, which does not cause serious thermal stresses in the Mo/Si membrane. The results obtained can be applied to the development of the design of a reflection-type dynamic mask with a matrix of electrostatically actuated MEMS micromirrors.