The cover of Journal of Vacuum Science & Technology B.
TUSCALOOSA, Alabama – A paper co-authored by a University of Alabama researcher and her advisor is featured on the cover of the Journal of Vacuum Science and Technology.
The SEM image of carbon nanotubes after densification process before electrodeposition of copper is on the cover of the journal’s March/April 2015 edition.
The paper in the journal is authored by Dr. Ying Feng, a post-doctoral researcher under Dr. Susan Burkett, the Alabama Power Foundation Endowed Professor of Electrical and Computer Engineering. Feng is sponsored by the Research Stimulation program on campus.
The paper is entitled “Fabrication and Electrical Performance of Through Silicon Via Interconnects Filled with a Copper/Carbon Nanotube Composite.”
The abstract states: “In this work, through silicon vias (TSVs) were fabricated using a materials system consisting of a composite of copper (Cu) and vertically grown carbon nanotubes (CNTs) as a possible solution to the problems encountered when using Cu-based interconnects. A metallic seed layer, tungsten, was deposited prior to CNT growth. Tungsten replaces Cu as a seed layer due to the thermal sensitivity of Cu at CNT growth temperatures. CNTs were grown both on the wafer surface and inside the silicon vias by chemical vapor deposition (CVD). A self-directed densification process was applied to modify the shape of the CNTs from a forest with equal top and bottom dimensions into bundles with a significantly smaller dimension at the top compared to the bottom. This process maximizes the contact area between the Cu electroplating solution and the CNTs. Cu was deposited by periodic pulse electroplating after CNT growth to form the Cu/CNT composite. Wafer thinning and polishing completed the TSV fabrication forming a test configuration to evaluate electrical performance. Experimental results were compared for interconnects filled with pure Cu to those filled with the Cu/CNT composite. The results indicate potential application of the Cu/CNT composite as a TSV interconnect material.”