Method of extracting effective channel length for nano-scale n-MOSFETs

摘要

This paper proposes a method of extracting the effective channel length L_(eff) of nano-scale n-MOSFETs. This method requires only one MOSFET; therefore, the L_(eff) extraction is not affected either by variation of carrier mobility due to differences in gate length or by changes in MOSFET parameters due to differences in fabrication processes. The method is based on the facts that the gate tunneling current I_(gb) to the substrate depends on L_(eff), and that the gate tunneling current I_(gsd) to the source and drain depends on the gate-source/drain overlap length ΔL. Curves of I_(gb) and I_(gsd) versus the gate dielectric voltage V_(ox) were obtained from the measured curves of I_(gb) and I_(gsd) versus gate voltage V_g in n-MOSFETs fabricated using a 90 nm CMOS technology. L_(eff) was extracted from the ratio I_(gb)/I_(gsd) for a given V_(ox). Comparison of the drain current I_d versus V_d curves calculated using the extracted L_(eff)S with the same curves obtained using previous methods shows that the proposed method is much more accurate than the previous ones.