Through-Silicon Vias Filled With Densified and Transferred Carbon Nanotube Forests

Through-silicon vias (TSVs) filled with densified and transferred carbon nanotube (CNT) forests are experimentally demonstrated. The filling is achieved by a postgrowth low-temperature transfer process at 200 degrees C instead of direct CNT growth in the vias normally requiring high temperature. A vapor densification method is also applied to densify the as-grown CNT forests, which allows for packing more CNTs in the vias to reduce their resistances. CNT-filled TSVs fabricated based on these two key steps show CMOS compatibility and roughly one order of magnitude reduction in resistivity compared to the TSVs filled with as-grown undensified CNT forests.