Influence of contact dimension on end resistance characterization for transmission line model

The influence of contact dimension and semiconductor sheet resistance on end resistance, R_E, was investigated with ISE TCAD simulator. Since it is difficult to accurately measure R_E experimentally due to its mathematical definition, potential distributions in the vicinity of the contacts were simulated in order to extract relationship between the apparent and actual R_E value. The simulation was built on circular and linear transmission line model (TLM) structures. It was found that apparent R_E obtained through measurement was lower than its actual value in large width contacts (down to 0.1% of actual R_E) and also in those deposited on thin semiconductor substrate. This trend was also found in semiconductor substrate with smaller modified sheet resistance. The results presented here can serve as a guideline to design TLM structures with less deviated value of apparent RE when end resistance characterization is necessary.