Ion Trap Micro-Fabrication on High Reflective Coatings

Abstract

Electrochemical fabrication offers unique advantages for nano/microfabrication of 2D and 3D microsystems. Precise control of deposition molds and thicknesses allows significant challenges to be solved through electrodeposition that are beyond the capabilities of standard silicon methods and conventional machining techniques. Previous work has enabled enhanced measurement techniques and reduction of anomalous motional heating in surface electrode ion traps1. This talk will focus on a recently designed two layer ion trap fabricated on top of a high reflective (HR) coated substrate creating a cavity beneficial to interrogating the ion. First, a lift-off profile lithography mold is patterned on a HR fused silica substrate, then a thin gold metal layer is deposited 1-2 micron in thickness, and finally a 10 micron thick electroforming process defines the second layer features. The effects of processing lithography molds on a surface that is highly reflective at the same wavelength used for the lithographic patterning will be presented. These details, along with a second layer of patterned gold, will be characterized using scanning electron microscopy, profilometry, and energy dispersive spectroscopy to better understand the resulting geometry of fabricated traps, surface topology, and quantify additive concentrations in the gold layers. These results will be compared to the original mask design for a feedback loop leading to future generations of cavity ion traps. Final traps will be singulated and packaged onto an interposer that is attached to a ceramic pin grid array (CPGA) package. The die is precisely aligned and attached to the interposer with a high thermally and electrically conductive ultra-high vacuum (UHV) compatible epoxy. An automated wire bonder is used to repetitively make low profile wire bonds for optimum optical access to the surface of the chip. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2015-10657A 1 C. L. Arrington, K. S. McKay, E. D. Baca, J. J. Coleman, Y. Colombe, P. Finnegan, D. A. Hite, A. E. Hollowell, R. Jordens, J. D. Jost, D. Leibfried, A. M. Rowen, U. Warring, M. Weides, A. C. Wilson, D. J. Wineland, and D. P. Pappas, 'Micro-Fabricated Stylus Ion Trap', Review of Scientific Instruments, 84 (2013).