Nanometer resolution mask lithography with matter waves: Near-field binary holography

TL;DR

This paper introduces a near-field binary holography technique for atom mask lithography, enabling nanometer resolution patterning with metastable helium, offering a cost-effective alternative to EUV lithography.

Contribution

The authors extend binary holography to near-field conditions and develop a mask design method for high-resolution atom lithography using matter waves.

Findings

Achieved nanometer resolution patterning with metastable helium sources.

Demonstrated potential for comparable patterning speeds to EUV lithography.

Extended holography methods to hexagonal subcell grids for versatile wave-beam applications.

Abstract

Mask-based pattern generation is a crucial step in microchip production. The next-generation extreme-ultraviolet- (EUV) lithography instruments with a wavelength of \SI{13.5}{\nano\meter} is currently under development. In principle, this should allow patterning down to a resolution of a few nanometers in a single exposure. However, there are many technical challenges, including those due to the very high energy of the photons. Lithography with metastable atoms has been suggested as a cost-effective, less-complex alternative to EUV lithography. The great advantage of atom lithography is that the kinetic energy of an atom is much smaller than that of a photon for a given wavelength. However, up till now no method has been available for making masks for atom lithography that can produce arbitrary, high resolution patterns. Here we present a solution to this problem. First, traditional binary holography is extended to near-field binary holography, based on Fresnel diffraction. By this technique, we demonstrate that it is possible to make masks that can generate arbitrary patterns in a plane in the near field (from the mask) with a resolution down to the nanometer range using a state of the art metastable helium source. We compare the flux of this source to that of an established EUV source (ASML, NXE:3100) and show that patterns can potentially be produced at comparable speeds. Finally, we present an extension of the grid-based holography method for a grid of hexagonally shaped subcells. Our method can be used with any beam that can be modeled as a scalar wave, including other matter-wave beams such as helium ions, electrons or acoustic waves.