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Proceedings Paper

Fabrication of conductive atomic force microscope probes and their evaluation for carrier mapping
Author(s): Marc Fouchier; Pierre Eyben; David Alvarez; Natasja Duhayon; MingWei Xu; Sywert Brongersma; Judit Lisoni; Wilfried Vandervorst
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Paper Abstract

Scanning Spreading Resistance Microscopy (SSRM) and Scanning Capacitance Microscopy (SCM) are two techniques based upon the atomic force microscope (AFM), which are used to obtain two-dimensional carrier maps of a semiconductor device’s cross-section. As all AFM techniques, they require probes with sharp tips to get good resolution images. Additionally, a hard and wear resistant tip material is needed to withstand the extreme mechanical stress tips are submitted to while a good conductivity is necessary for the characterization of highly doped areas of modern devices. In this work, several types of materials are evaluated based upon their mechanical and electrical characteristics: metals, hardmetals, conductive oxides and doped diamond. Commercial metal and diamond coated silicon tips are currently used (only diamond for SSRM). However, tips with thin metal coatings wear fast while the high resistivity of diamond limits the dynamic range. In both cases, the radius of curvature of coated tips is fairly large limiting the resolution. Probes with tips made out of TiN, a hardmetal, were manufactured using the molding technique. Using these tips, an ohmic point contact was obtained on Si. In SSRM mode, resistivity contrast was observed for the first time for a metallic tip. TiN tips also proved to be hard enough to penetrate the oxide and obtain SSRM images on InP. A good contrast and a monotonic behavior on n-type silicon in the absence of bias were obtained in SCM. The wear rate of TiN tips is lower than that of coated Si tips. However, despite their high hardness, TiN tips wore fast under high pressure and the tips died after a few SSRM scan lines on Si, and after a few images on InP.

Paper Details

Date Published: 24 April 2003
PDF: 10 pages
Proc. SPIE 5116, Smart Sensors, Actuators, and MEMS, (24 April 2003); doi: 10.1117/12.498164
Show Author Affiliations
Marc Fouchier, IMEC (Belgium)
Pierre Eyben, IMEC (Belgium)
Katholeike Univ. Leuven (Belgium)
David Alvarez, IMEC (Belgium)
Katholieke Univ. Leuven (Belgium)
Infineon Technologies AG (Germany)
Natasja Duhayon, IMEC (Belgium)
Katholeike Univ. Leuven (Belgium)
MingWei Xu, IMEC (Belgium)
Katholeike Univ. Leuven (Belgium)
Sywert Brongersma, IMEC (Belgium)
Judit Lisoni, IMEC (Belgium)
Wilfried Vandervorst, IMEC (Belgium)
Katholieke Univ. Leuven (Belgium)

Published in SPIE Proceedings Vol. 5116:
Smart Sensors, Actuators, and MEMS
Jung-Chih Chiao; Vijay K. Varadan; Carles Cané, Editor(s)

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