title: Large area scanning probe microscope in ultra-high vacuum demonstrated for electrostatic force measurements on high-voltage devices.
abstract: BACKGROUND
  The resolution in electrostatic force microscopy (EFM), a descendant of atomic force microscopy (AFM), has reached nanometre dimensions, necessary to investigate integrated circuits in modern electronic devices. However, the characterization of conducting or semiconducting power devices with EFM methods requires an accurate and reliable technique from the nanometre up to the micrometre scale. For high force sensitivity it is indispensable to operate the microscope under high to ultra-high vacuum (UHV) conditions to suppress viscous damping of the sensor. Furthermore, UHV environment allows for the analysis of clean surfaces under controlled environmental conditions. Because of these requirements we built a large area scanning probe microscope operating under UHV conditions at room temperature allowing to perform various electrical measurements, such as Kelvin probe force microscopy, scanning capacitance force microscopy, scanning spreading resistance microscopy, and also electrostatic force microscopy at higher harmonics. The instrument incorporates beside a standard beam deflection detection system a closed loop scanner with a scan range of 100 μm in lateral and 25 μm in vertical direction as well as an additional fibre optics. This enables the illumination of the tip-sample interface for optically excited measurements such as local surface photo voltage detection.
  
  
  RESULTS
  We present Kelvin probe force microscopy (KPFM) measurements before and after sputtering of a copper alloy with chromium grains used as electrical contact surface in ultra-high power switches. In addition, we discuss KPFM measurements on cross sections of cleaved silicon carbide structures: a calibration layer sample and a power rectifier. To demonstrate the benefit of surface photo voltage measurements, we analysed the contact potential difference of a silicon carbide p/n-junction under illumination.
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Gysin
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: Thilo
authors.initials: T
authors.lastname: Glatzel
authors.affiliation: ABB Corporate Research Center, Segelhofstrasse 1K, CH-5404 Baden-Dättwil, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmölzer
authors.affiliation: Ascatron AB, Electrum 207, SE-16440 Kista, Sweden.
authors.forename: Adolf
authors.initials: A
authors.lastname: Schöner
authors.affiliation: Ascatron AB, Electrum 207, SE-16440 Kista, Sweden.
authors.forename: Sergey
authors.initials: S
authors.lastname: Reshanov
authors.affiliation: ABB Corporate Research Center, Segelhofstrasse 1K, CH-5404 Baden-Dättwil, Switzerland.
authors.forename: Holger
authors.initials: H
authors.lastname: Bartolf
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: Ernst
authors.initials: E
authors.lastname: Meyer
keywords: Kelvin probe force microscopy; copper alloy; electrostatic force microscopy; high-voltage device; silicon carbide (SiC); surface photo voltage