Improving the conductivity of platinum-containing nano-structures created by electron-beam-induced deposition

Electron-beam-induced deposition (EBID) allows nano-scale three-dimensional rapid prototyping and is a promising nano-lithography alternative. One application is to write conductive lines at a position chosen by the scanning electron microscope (SEM) operator, for example to create contact electrodes to nano-devices. Therefore the deposited material's resistivity should be as close as possible to the bulk metal resistivity namely 10.62 mu Omega cm in the case of platinum, but incorporation of carbon in the deposit resulting from the use of the traditional organometallic precursors negatively impacts conductivity. Firstly, for deposition from the standard organometallic platinum precursor MeCpPtMe3, we show that for optimal platinum content the beam power density at the substrate surface needs to exceed 10 mu W/mu m(2). Secondly, we present a novel post-treatment method for improving the conductivity of these nano-deposits ex-situ: exposure to atomic hydrogen flow. On structures deposited from MeCpPtMe3, the carbon content decreases from (81 +/- 2) to (65 +/- 2) at.% and the resistivity is decreased to (2.2 +/- 0.7) x 10(4) mu Omega cm. Thirdly, we present our investigations with a carbon-free platinum precursor, Pt(PF3)(4), where resistivities of (690 +/- 30) mu Omega cm were achieved, and furthermore report the dependence of conductivity with substrate temperature during deposition. (C) 2008 Elsevier B.V. All rights reserved.