STLM: A Sidewall TLM Structure for Accurate Extraction of Ultralow Specific Contact Resistivity

We propose a very large scale integration compatible, modified transfer length method (TLM) structure, called sidewall TLM, to minimize the effect of spreading resistance and thus improving the resolution of the TLM method. This is achieved by allowing uniform current collection perpendicularly through the sidewall of the contact. We demonstrate statistically significant specific contact resistivity (ρ_c) extraction of 2×10^-8Ω cm² and 5×10^-9Ω cm² for n-type and p-type NiSi contacts, respectively, on a 300-mm wafer, which are about 50% less than those extracted using the conventional TLM structure. The proposed structure also shows a tighter distribution in the extracted ρ_c values. The results show the importance of such test structures to accurately extract ultralow ρ_c values relevant to sub-14-nm technology nodes.