Extraction of Ultra-Low Contact Resistivity by End-Resistance Method

Accuracy of extracting ultra-low contact resistivity by the end-resistance method is evaluated. As the contact length becomes smaller than the transfer length, the end-resistance approaches the contact resistance, and the error decreases with the reduction of contact length and contact resistivity. The contact resistivity lower than $10^{-9}\Omega-\mathrm{c}\mathrm{m}^{2}$ can be extracted with accuracy lower than $3\times 10^{-10}\Omega-\mathrm{c}\mathrm{m}^{2}$. This end-resistance method is verified by self-aligned transmission line model test structure. Statistic analysis of the distribution of contact resistance and the uniformity of the contact interface are also demonstrated.