Integration of low-κ dielectric liner in through silicon via and thermomechanical stress relief

Abstract

Through silicon via (TSV) consists of a copper (Cu) core isolated by a dielectric liner. The thermomechanical stress originating from the mismatch in the coefficient of thermal expansion of Cu and silicon is a serious concern on mechanical reliability and electrical variability. The effect on thermomechanical stress by replacing the conventional liner (silicon dioxide) with a low-κ liner (carbon-doped silicon dioxide) is studied. By micro-Raman analysis, it is observed that the biaxial stress in silicon at the immediate vicinity of Cu-TSV is relieved by 29–45% with a low-κ liner due to its smaller elastic modulus.