Fabrication of ultra-thin free-standing chromium foils supported by a Si 3N 4 membrane-structure with search pattern

• Published in: Microelectronic engineering Vol. 46; no. 1; pp. 435 - 438
• Main Authors: Stepanov, I.S., van Aken, R.H., Zuiddam, M.R., Hagen, C.W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1999
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/S0167-9317(99)00127-6

A microfabrication process is described to produce samples with a search pattern that enables finding a small area of interest with Scanning Tunnelling Microscopy (STM). This area is a 100 μm square membrane, containing 0.6 – 3 μm square windows with 5 – 8 nm thick free-standing Cr foils. All three components — search pattern, membranes and the small windows — are patterned on the sample and aligned with respect to each other with Electron Beam Lithography. For subsequent material removal both wet etches and dry plasma etches are used. With E-gun evaporation a Cr layer is deposited on the front side, to obtain a conducting surface, and on the backside for the free-standing foils. Search pattern and foils are tested successfully with STM.