Unexpected Surface Implanted Layer in Static Random Access Memory   Devices Observed by Microwave Impedance Microscope
  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. 
Worasom Kundhikanjana, Yongliang Yang, Qiaochu Tang, Kun Zhang Keji   Lai, Yue Ma, Mike Kelly, Xinxin Li and Zhi-Xun Shen
cond-mat.mes-hall