Double-Densified Vertically Aligned Carbon Nanotube Bundles for Application in 3D Integration High Aspect Ratio TSV Interconnects

The treatment of densification by vapor on pristine MWCNT bundles are necessary to improve the effective area of the CNT TSV. However, the CNT bundles might tilt partly because of the non-uniform densification at root of the bundle, especially when it comes to the high aspect ratio CNT bundles. In order to solve these problems, a double densification process has been proposed and developed here. First of all, the shape of partial densified CNT bundles were optimized as a function of time. After several steps such as transferring of partial densified CNT bundles into the via, second densification, epoxy filling and chemical mechanical polishing, the CNT filled TSV with aspect ratio of 10 was achieved. The current voltage response of the CNT TSV interconnection indicated good electrical connection was formed. The resistivity of CNT bundles in via was calculated to be around 2-3 mΩ·cm.