Nonmonotonic behavior of the scanning capacitance microscope for large dynamic range samples

The phenomenon of contrast reversal in scanning capacitance microscopy (SCM ) imaging will be discussed, taking into account the implications for sampl es which contain both p-type and n-type dopants. Experiments show that a mo notonic change in SCM output versus dopant concentration for large dynamic range samples (10(14)-10(20) cm(-3)) is dependent on the applied de bias. I ncorrect adjustment of this parameter can lead to contrast reversal in the SCM images causing a problem for conversion algorithms and dopant quantific ation. Simulation results demonstrating this feature will be presented. In addition, the appearance of shifting bands which are common in voltage-depe ndent measurements of p-n junctions complicates the data interpretation and extraction of length measurements within an image, such as the effective e lectrical channel length in the case of transistor characterization. The si gnificance of these problems with respect to the SCM response curve will be discussed. (C) 2000 American Vacuum Society. [S0734-211X(00)08001-X].