AVS 50th International Symposium
    Semiconductors Wednesday Sessions
       Session SC+EM-WeP

Paper SC+EM-WeP3
Metal-Oxide-Semiconductor Field Effect Transistors Investigated by Scanning Capacitance Force Microscopy

Wednesday, November 5, 2003, 11:00 am, Room Hall A-C

Session: Poster Session
Presenter: K. Kimura, Kyoto University, Japan
Authors: K. Kimura, Kyoto University, Japan
K. Kobayashi, Kyoto University, Japan
H. Yamada, Kyoto University, Japan
K. Usuda, Toshiba Corporation, Japan
K. Matsushige, Kyoto University, Japan
Correspondent: Click to Email
We have recently developed a novel scanning probe technique, scanning capacitance force microscopy (SCFM) capable of measuring two-dimensional (2D) dopant profiling of semiconducting sample. SCFM, of which operating principle is based on the detection of an electric force between the conducting tip and sample, does@aa n@t utilize ultrahigh frequency capacitance sensor required for conventional scanning capacitance microscopy (SCM). In SCFM, an electric field alternating at an angular frequency @omega@ is applied between the tip and the semiconducting sample and then the induced electric force (ESF) oscillating at its third harmonic frequency (3@omega@) is detected using a lock-in amplifier as an SCFM signal. This is because the magnitude of the induced ESF is proportional to the square of the applied electric field and the capacitance of the semiconducting sample, which is also modulated at @omega@. Thus the amplitude-and-phase (Acos @phi@) signal of the induced ESF alternating at 3@omega@ contains information on the differential capacitance (dC/dV). We performed cross-sectional SCFM imaging of a n-channel metal-oxide-semiconductor field effect transistor (n-MOSFET). In source and drain regions, dopant density decreases from 10@super 21@ cm@super -3@ at the surface to 10@super 17@ cm@super -3@ at about 100 nm in the depth direction. Channel length is 500 nm and dopant density in channel region is 10@super 17@ cm@super -3@. We observed a drastic change in SCFM signal at about 100 nm in the depth direction of the source or drain regions. We also observed a characteristic contrast at the depleted area under the gate oxide corresponding to the channel region. In the presentation, we present SCFM images on MOSFETs obtained both in contact mode and dynamic mode. We discuss the interpretation of the obtained contrast and its dependence on the applied DC voltage. We also compare those SCFM images with SCM images and SIMS profiles.