Dopant imaging of power semiconductor device cross sections

Abstract

Several Scanning Probe Microscopy (SPM) methods allow to image dopant profiles in a range from 10 14 cm-3 to 10 19 cm-3 on semiconducting samples. In our work we present Scanning Capacitance Force Microscopy (SCFM) and Kelvin Probe Force Microscopy (KPFM) experiments performed on cross sections of silicon (Si) and silicon carbide (SiC) power devices and epitaxially grown calibration layers. The KPFM signals show under illumination a reduced influence on surface defect states. In addition results from numerical simulation of these microscope methods are discussed.

Recent advances in hybrid measurement methods based on atomic force microscopy and surface sensitive measurement techniques

“…Another common area of application of KPFM is the analysis of semiconductors. 352,355,356 Here, the KPFM method is sensitive enough to determine the dopant concentration in the range of 10 14 cm À3 to 10 19 cm À3 . 356 However, the contact potential difference is altered by surface defects, 357 exploitable for detecting of defects.…”

“…352,355,356 Here, the KPFM method is sensitive enough to determine the dopant concentration in the range of 10 14 cm À3 to 10 19 cm À3 . 356 However, the contact potential difference is altered by surface defects, 357 exploitable for detecting of defects. 358 By illumination with a sub-bandgap laser, band bending is reduced and higher contrast in CPD in conjunction with reduced inuence on surface defect states is achieved.…”

“…358 By illumination with a sub-bandgap laser, band bending is reduced and higher contrast in CPD in conjunction with reduced inuence on surface defect states is achieved. 356 KPFM can be applied for Langmuir-Blodgett lms of organic molecules on water (subphase) to assess the packing of the organic molecules at varying surface pressure by means of the CPD. 353 Furthermore, KPFM can be utilized to ascertain charge transfer from Pt adsorbates to TiO 2 surface 359 and analysis of charge separation for the benchmark of organic solar cells, which for example consist of poly(3-hexylthiophene) (P3HT)/ fullerene (C60) acid-methyl ester (PCBM).…”

Measurement of electrostatic tip–sample interactions by time-domain Kelvin probe force microscopy

“…Kelvin probe force microscopy (KFM) is a technique used to quantitatively characterize such electrical proper-ties [1][2][3]. It is applied to map material compositions via changes in the work function, to localize charge distributions in dielectric samples [4,5], and to characterize doping profiles via scanning capacitance measurements [6]. Especially in the field of nanoelectronic devices, this kind of electrical characterizations is of great interest.…”

“…Namely, a static component (dc) as well as components at the modulation frequency ω m and at the second harmonic frequency 2ω m . These spectral components are defined by (5) with (6) (7) and (8) In conventional frequency-modulated (FM-) KFM, the contributions at ω m and 2ω m are detected via lock-in techniques, either at the Δf output of a phase-locked loop (PLL) [12] or by detecting the sidebands of the cantilever oscillation [13].…”