AVS 49th International Symposium
    Nanometer Structures Friday Sessions
       Session NS-FrM

Paper NS-FrM7
Factors Influencing the Capacitance-Voltage Characteristics Measured by the Scanning Capacitance Microscope

Friday, November 8, 2002, 10:20 am, Room C-207

Session: Novel Surface Nanoprobes
Presenter: G.H. Buh, National Institute of Standards and Technology and Seoul Nat'l Univ., Korea
Authors: G.H. Buh, National Institute of Standards and Technology and Seoul Nat'l Univ., Korea
J.J. Kopanski, National Institute of Standards and Technology
J.F. Marchiando, National Institute of Standards and Technology
A.G. Birdwell, National Institute of Standards and Technology
Y. Kuk, Seoul National University, Korea
Correspondent: Click to Email
The scanning capacitance microscope (SCM) can be used to measure two-dimensional dopant profiles in semiconductors with nanometer scale resolution. Dopant concentration information is extracted from the local capacitance-voltage (C-V) characteristics measured between the SCM tip and the semiconductor sample. Two important artifact effects on C-V curves measured via SCM are discussed. It is found that the stray light from the laser of the atomic force microscope (AFM) dramatically affects the measured C-V curve. The difference between the usual SCM C-V curves measured under this high stray light condition and SCM C-V curves measured in a true dark condition will be shown and discussed. The distortion of C-V curves caused by the lock-in modulation voltage will also be discussed. After reducing these effects, SCM C-V curves are obtained that show markedly different behavior from that of conventional one-dimensional C-V curves. These measured C-V curves have a much stretched-out shape and non-zero dC/dV signals in the depletion and inversion region. Measured C-V curves are compared with three-dimensional calculations of the capacitance between the tip and sample. Determination of the dopant density directly from SCM C-V curves will be discussed. Finally, we will discuss optimal SCM imaging conditions, which overcome effects from surface charge and work function variation, and produce more accurate dopant profile measurements.