Johannes Vanpaemel

Electrochemical Deposition of Subnanometer Ni Films on TiN

In this paper, we show the electrochemical deposition of a subnanometer film of nickel (Ni) on top of titanium nitride (TiN). We exploit the concept of cluster growth inhibition to enhance the nucleation of new nuclei on the TiN substrate. By deliberately using an unbuffered electrolyte solution, the degree of nucleation is enhanced as growth is inhibited more strongly. This results in a very high particle density and therefore an ultralow coalescence thickness. To prevent the termination of Ni deposition that typically occurs in unbuffered solutions, the concentration of Ni(2+) in solution was increased. We have verified with RBS and ICP-MS that the deposition of Ni on the surface in this case did not terminate. Furthermore, annealing experiments were used to visualize the closed nature of the Ni film. The closure of the deposited film was also confirmed by TOF-SIMS measurements and occurs when the film thickness is still in the subnanometer regime. The ultrathin Ni film was found to be an excellent catalyst for carbon nanotube growth on conductive substrates and can also be applied as a seed layer for bulk deposition of a smooth Ni film on TiN.

Electrical and structural characterization of 150 nm CNT contacts with Cu damascene top metallization

This paper discusses the electrical and structural characterization of 150 nm diameter contacts filled with carbon nanotubes (CNTs) and a Cu damascene top metal. We present the first images of CNTs in direct contact with the top metal. A CNT tip clean before metallization reduced the single CNT contact hole resistance from 4.8 kΩ down to 2.8 kΩ (aspect ratio 2.4). The first basic electrical breakdown experiments with Kelvins resulted in high breakdown currents of 5-13 MA/cm2.