From powerful research platform for industrial EUV photoresist development, to world record resolution by photolithography: EUV interference lithography at the Paul Scherrer Institute

Abstract

Extreme ultraviolet interference lithography (EUV-IL, λ = 13.5 nm) has been shown to be a powerful technique not only for academic, but also for industrial research and development of EUV materials due to its relative simplicity yet record high-resolution patterning capabilities. With EUV-IL, it is possible to pattern high-resolution periodic images to create highly ordered nanostructures that are difficult or time consuming to pattern by electron beam lithography (EBL) yet interesting for a wide range of applications such as catalysis, electronic and photonic devices, and fundamental materials analysis, among others. Here, we will show state-of the-art research performed using the EUV-IL tool at the Swiss Light Source (SLS) synchrotron facility in the Paul Scherrer Institute (PSI). For example, using a grating period doubling method, a diffraction mask capable of patterning a world record in photolithography of 6 nm half-pitch (HP), was produced. In addition to the description of the method, we will give a few examples of applications of the technique. Well-ordered arrays of suspended silicon nanowires down to 6.5 nm linewidths have been fabricated and are to be studied as field effect transistors (FETs) or biosensors, for instance. EUV achromatic Talbot lithography (ATL), another interference scheme that utilizes a single grating, was shown to yield well-defined nanoparticles over large-areas with high uniformity presenting great opportunities in the field of nanocatalysis. EUV-IL is in addition, playing a key role in the future introduction of EUV lithography into high volume manufacturing (HVM) of semiconductor devices for the 7 and 5 nm logic node (16 nm and 13 nm HP, respectively) and beyond while the availability of commercial EUV-tools is still very much limited for research.

EUV/Soft X-Ray Interference Lithography

“…Through a combination of advantages of IL and the short wavelength of EUV, EUV-IL technology has been proved as a powerful tool for high-resolution nanostructure fabrication over large areas. So far, several EUV-IL beamlines have been built in different synchrotron facilities, such as the XILII beamline in swiss light source (SLS) [1], the EUV-IL beamline in shanghai synchrotron radiation facility (SSRF) [2], the EUV-IL beamline in New SUBARU synchrotron radiation facility [3], the EUV-IL beamline at the University of Wisconsin-Madison [4] and the EUV-IL beamline in the national synchrotron radiation research center (NSRRC), Taiwan [5]. Up to now, the highest-resolution line structures with 6-nm half pitch (HP) have been afforded in PSI XILII [1].…”

High-efficiency diffraction gratings for EUV and soft x-rays using spin-on-carbon underlayers

“…Diffraction optics, such as gratings and Fresnel zone plates, for extreme ultraviolet (EUV) and x-rays with high resolution and diffraction efficiency are challenging to fabricate because of the challenges in patterning high-resolution nanostructures with high aspect ratios [1][2][3]. One such application of diffractive optics is EUV interference lithography (EUV-IL), used for patterning periodic nanostructures with relatively high throughput over large areas for a wide range of applications [4][5][6][7][8][9][10][11]. The major challenge in increasing the resolution of EUV-IL is the fabrication of diffraction gratings with high resolution and diffraction efficiency on thin Si 3 N 4 membranes using electron beam lithography (EBL).…”

Extreme-UV interference lithography at the Paul Scherrer Institute

“…Such structures can be difficult or time-consuming to pattern by EBL, but are interesting for a wide range of applications, such as nanocatalysis, 5 electronic 6 and photonic devices, 7 and fundamental materials analysis. 8 In this work, 9 we discuss the long-term performance and capabilities of EUV-IL activities at the Paul Scherrer Institute (PSI), Switzerland. We also describe some of the state-of-the-art research that has been conducted at PSI.…”