Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 77: Methods: Scanning Probe Techniques I

O 77.3: Vortrag

Donnerstag, 28. Februar 2008, 16:00–16:15, MA 041

Evaluating Electrostatic Force Microscopies for the Investigation of Near-Surface Dopant Distribution in Silicon — •Markus Ratzke¹, Mario Birkholz², Joachim Bauer², Detlef Bolze², and Juergen Reif¹ — ¹LS Experimentalphysik II, BTU Cottbus und IHP/BTU JointLab, Konrad-Wachsmann-Allee 1, D-03046 Cottbus — ²IHP, lm Technologiepark 25, D-15236 Frankfurt (Oder)

The still ongoing decrease in semiconductor device dimensions, both laterally and in depth, requires a sub-micron-scale mapping of surface potential, surface capacitance and near surface dopant distribution. Corresponding methods should operate non-invasively, leaving the specimen intact. Scanning-probe based techniques like Scanning Kelvin Probe Microscopy (SKM) and non-contact Scanning Capacitance Microscopy (SCM) represent promising tools.

To evaluate these techniques doping patterns produced by standard CMOS technology on silicon were investigated experimentally. Lattices of alternating p- and n-type doping in the 10¹⁷ to 10¹⁹ cm⁻³ range and a pitch of 360 nm were prepared by As⁺ ion implantation. The results are compared to FEM calculations for a correlation with the expected carrier distributions. It turns out that SCM, mapping electrostatic forces at the second or third harmonic frequency of the AC driving voltage, yields higher resolution and contrast compared to SKM. In addition this technique appears to be less influenced by the actual surface conditions like roughness and surface charge. The physical significance of the higher harmonics will be considered.