A Semiconductor Nano-Patterning Approach Using AFM-Scratching Through Oxide Thin Layers
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A Semiconductor Nano-Patterning Approach Using AFM-Scratching Through Oxide Thin Layers L. Santinacci1,a T. Djenizian and P. Schmuki University of Erlangen-Nuremberg Department of Materials Science - LKO Martensstrasse 7, D-91058 Erlangen, Germany ABSTRACT AFM-scratching was performed through thin oxide layer which was either a native oxide layer (1.5 – 2 nm thick) or a thermal oxide layer (10 nm thick). Due to their insulating properties, the SiO2 films act as masks for the metal electrochemical deposition. In the scratched openings copper deposition can take place selectively and thus nano-scale metal lines could be successfully plated onto the p-type silicon substrates. Using particularly, if sufficiently thick thermal oxide has advantages over the native oxide, it allows a H-termination of the Si within the grooves (HF treatment) without eliminating the oxide layer on the rest of the surface. INTRODUCTION Since the recent incorporation of electrodeposited copper into electronic devices, a renewal of interest for electrodeposition and related technologies have found new applications in electronics manufacturing, especially for packaging and magnetic recording [1]. Usually photolithography is used in industrial processes to pattern surfaces in the micrometer range. However miniaturization and the promising properties of nano-scaled materials (“quantum confinement”) have stimulated research groups to explore alternative patterning techniques. Most of these structuring methods are based on lithography requesting therefore a masking process. Based on this principle high resolution patterning can be performed using electronbeam, x-rays, or scanning probe microscopies to sensitized the resist layer (see e.g., Ref. [2-4]). The other approaches consist of direct selective reactions at the semiconductor surfaces. Different techniques are proposed such as pre-sensitization of the surface by focused ion beam followed by selective electrochemical deposition or dissolution at the implanted locations [5,6]. Another example is the use of an electrochemical-scanning tunneling microscope (EC-STM) to deposit nanometer scaled metallic clusters onto metal and semiconductor surfaces [7]. Under the scanning of the optical tip of a scanning near-field optical microscope (SNOM), it is also possible to use the light to generate and control the local photocurrent that triggers the electrochemical reactions at the scanned locations with a high lateral resolution [8]. Other techniques are reported in literature and a review of these techniques is proposed in Ref. [9]. In a previous paper, an atomic force microscope (AFM) was used to created nano-scratches onto silicon surface covered by the native oxide layer. Due to the masking properties of this oxide film, it was possible to selectively deposit copper within the grooves with a sub-micrometer 1
On leave from: Swiss Federal Institute of Technology Lausanne (EPFL), Dept. Materials Science, LTP, CH-1015 Lausanne, Switzerland a Present address: University of Provence – CNRS, Dept. Ma
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