Differential thermal expansion mismatch between Cu and Si along with high aspect ratios required for TSV pose unique challenges to the integration and reliability of Cu TSV. A TSV structure that successfully mitigates these concerns has been integrated into CMOS with high K/metal gates. Data from test structures demonstrate no 'Cu pumping' or other deleterious effects to neighboring devices or interconnects. Functional 3D prototypes utilizing stacked embedded DRAMs were demonstrated showing no impact from TSV processing. © 2012 IEEE.