SCIL nanoimprint solutions: turning your surfaces into functions--direct patterning of nano-photonics

Abstract

Nano-photonic applications are on the brink of disrupting the optics we know. Examples are augmented reality glasses based on diffractive waveguide combiners (DWC) using surface relief gratings and meta-lenses consisting of high aspect ratio pillars. The challenge will be fabricating 100’s of millions of these large area devices with high yield and low cost. In this paper we will demonstrate the direct replication of nano-photonic patterns using a nanoimprint method in combination with inorganic functional optical resist materials. SCIL Nanoimprint solutions always developed the materials, processes and nanoimprint hardware as an integral system for optimal results. The same imprint technology scales from 100mm up to 300mm wafers. A unique approach of SCIL is to directly pattern inorganic materials with single-nm precision and keep this accuracy for over the full stamp lifetime. For nanophotonic applications the direct replication of nano-patterning in materials with a high refractive index (1.7 – 2.0) is highly desired. With this slow and expensive process steps such as optical- and hard mask layer deposition and reactive ion etching of these materials after the lithography step can be omitted. As another example augmented reality glasses with a high efficiency require 3 slanted gratings with varying orientations, resulting in 2 additional lithography and etching steps. We will show the direct nanoimprint patterning of slanted gratings in all orientations with a refractive index up to n=1.92 (@550nm). For these nano-photonic devices to work within specification, the absolute size of the patterns needs to be within 1-5nm variation and the refractive index to be controlled to the 3rd decimal (depending on the application). To verify the full nanoimprint production process in a close-coupled manner a fast non-destructive test method based on Fourier imaging scatterometry will be introduced. This method can determine the relevant sub-micron feature sizes with single nmprecision.