Under-Bump Metallization Contact Resistance ( $R_{c}$ ) Characterization at 10- $\mu \text{m}$ Polymer Passivation Opening

Abstract

Under-bump metallization R c is a critical metric for high-density interconnect in electronic devices. We developed a test vehicle to characterize the impact of unit processes on R c for 10- $\mu \text{m}$ polymer passivation opening. We demonstrate that advanced preclean is necessary to achieve low (R c $\text{m}\Omega$ ) for future node extendibility, owing to reduction of both Al oxide and organometallic formation. This is achievable through a combination of low-temperature ( c performance. Influence of SiN etch on R c is also investigated, and it was found that Cl-chemistry is better than F-chemistry to achieve low R c .