A high-flux compact X-ray free-electron laser for next-generation chip metrology needs

Abstract

Recently, considerable work has been directed at development of a ultra-compact X-ray free-electron laser based on emerging techniques in high field cryogenic acceleration, with attendant dramatic improvements in electron beam brightness, and state-of-the-art concepts in beam dynamics, magnetic undulators, and X-ray optics. A full conceptual design of a 1 nm XFEL with a length and cost over an order of magnitude below current XFELs has resulted from this effort. This instrument has been developed with an emphasis on permitting exploratory scientific research in a wide variety of fields in a university setting. Concurrently, compact FELs are being urgently developed for use as an instrument to enable next generation chip manufacturing through use as a high flux, few-nm lithography source. This new role suggests consideration of XFELs to addressed urgently emerging demands in this sector, as identified by recent national need studies, for new radiation sources aimed at chip manufacturing: a coherent hard X-ray source which enables frontier metrology methods. Indeed, it has been shown that one may use coherent X-rays to perform 10 nm-class resolution surveys of macroscopic, cm-scale structures such as chips, using ptychographic laminography. As the XFEL is a very promising candidate for realizing such methods, we present here an analysis of the issues and likely solutions associated with extending the UCXFEL to harder X-rays (above 7 keV), much higher fluxes and levels of coherence, and methods of applying such a source for ptychographic laminography to micro-electronic device measurements. We discuss the development path to move the concept to rapid realization of a transformative FEL-based application, outlining FEL and metrology system challenges.

Improving Cathode Testing with a High-Gradient Cryogenic Normal Conducting RF Photogun

“…The next version of the UCXFEL photoinjector development will use the the same cavity design but modified for low-temperature operation. The further context of the new design is presented in the following [53].…”

“…and RF cavity figures of merit (i.e., temperature-dependent properties, etc.) as a stepping stone to a UCXFEL photoinjector, which is designed to operate at 45 K, so the inclusion of theoretical performance is useful [53].…”

An Ultra-Compact X-ray Regenerative Amplifier Free-Electron Laser

“…This paper studies the possible implementation of a compact X-ray Regenerative Amplifier Free-Electron Laser (XRAFEL) at the proposed Ultra-Compact X-ray Free-Electron Laser (UC-XFEL) facility [11]. The scientific motivation and the accelerator designs are reported in a companion paper of this proceedings [13], and our paper focuses on the FEL design and simulations. An XRAFEL is a type of cavity-based XFEL (CBXFEL) that couples a high-gain FEL undulator to an X-ray cavity [14].…”