Full field tabletop EUV coherent diffractive imaging in a transmission geometry

Bosheng Zhang,Elisabeth R Shanblatt,Farhad Salmassi,Eric M Gullikson,Weilun Chao,Justin M Shaw,Matthew D Seaberg,Dennis F Gardner,Daniel E Adams,Henry C Kapteyn,Margaret M Murnane

doi:10.1364/oe.21.021970

Abstract

We demonstrate the first general tabletop EUV coherent microscope that can image extended, non-isolated, non-periodic, objects. By implementing keyhole coherent diffractive imaging with curved mirrors and a tabletop high harmonic source, we achieve improved efficiency of the imaging system as well as more uniform illumination at the sample, when compared with what is possible using Fresnel zone plates. Moreover, we show that the unscattered light from a semi-transparent sample can be used as a holographic reference wave, allowing quantitative information about the thickness of the sample to be extracted from the retrieved image. Finally, we show that excellent tabletop image fidelity is achieved by comparing the retrieved images with scanning electron and atomic force microscopy images, and show superior capabilities in some cases.

Highlights

Coherent diffractive imaging (CDI) [1,2,3,4,5,6] is a powerful technique for imaging at the nanoscale
We demonstrate the first tabletop extreme ultraviolet (EUV) microscope that can image extended, nonisolated, non-periodic, objects by implementing keyhole CDI using a tabletop EUV source
We significantly increase the utility of keyhole CDI by using a curved EUV mirror instead of a Fresnel zone plates (FZP) to focus the light onto the sample

Summary

Introduction

Coherent diffractive imaging (CDI) [1,2,3,4,5,6] is a powerful technique for imaging at the nanoscale. Keyhole CDI, first demonstrated using light from a synchrotron source, uses a FZP focusing optic with smaller diameter than the incident beam to confine the illumination on the sample [31]. This approach has three major advantages: first, it represents the first general tabletop full field EUV coherent microscope; second, it demonstrates higher photon flux throughput relative to a FZP at the illumination wavelength of 29 nm; and third, it produces a more uniform illumination on the sample since there is no need for a central beam stop when a curved focusing optic is used.

Results

Conclusion