  Real-space mapping of doping concentration in semiconductor devices is of
great importance for the microelectronic industry. In this work, a scanning
microwave impedance microscope (MIM) is employed to resolve the local
conductivity distribution of a static random access memory (SRAM) sample. The
MIM electronics can also be adjusted to the scanning capacitance microscopy
(SCM) mode, allowing both measurements on the same region. Interestingly, while
the conventional SCM images match the nominal device structure, the MIM results
display certain unexpected features, which originate from a thin layer of the
dopant ions penetrating through the protective layers during the heavy
implantation steps.
