John J. Plombon

High-frequency electrical properties of individual and bundled carbon nanotubes

Bundles of single wall carbon nanotubes have been proposed as an interconnect that could potentially replace copper in state-of-the-art ultralarge-scale-integrated circuits if theoretically predicted inductance, resistance, and capacitance scale with the number of carbon nanotubes within the bundle. The authors report direct measurement of the kinetic inductance of individual single wall carbon nanotubes and measurement of the high-frequency impedance of bundles showing that the bundle inductance scales with the number of individual carbon nanotubes.

Influence of phonon, geometry, impurity, and grain size on Copper line resistivity

The authors report on the resistivity of submicron copper lines ranging from 75to500nm linewidths as a function of temperature in the 10Kto380K interval. Their estimate of the contributions to electron scattering at 20K for the narrowest line (75nm linewidth) is 29% from copper surfaces, 25% from grain boundaries, and 30% from impurities, with the bulk resistivity making up the remaining 16%. It should be noted that at 300K, the contribution of electron-phonon scattering is about 60% illustrating the benefit of studying different scattering mechanisms at cryogenic temperatures.

Connecting Single Molecule Electrical Measurements to Ensemble Spectroscopic Properties for Quantification of Single-Walled Carbon Nanotube Separation

We directly compared ensemble spectroscopic measurements to a statistically rigorous single molecule electrical characterization of individual SWNT devices using a high throughput electrical probe station and reported, for the first time, a highly accurate extinction coefficient ratio for metallic to semiconducting SWNTs of 0.352 +/- 0.009. The systematic counting of metallic and semiconducting types from solution also allows us to examine the variances associated with device properties and therefore provide the first measure of potential defect generation during processing methods.

Electron transport properties of sub-3-nm diameter copper nanowires

Intel Corporation (Intel-Tyndall research collaboration sponsored by Intel Components Research); Irish Research Council (Postgraduate scholarship); QuantamWise A/S (support and access to the QUANTUMWISE simulation software); Science Foundation Ireland (SFI Investigator program, Grant No. 13/IA/1956.)

Effect of strain, thickness, and local surface environment on electron transport properties of oxygen-terminated copper thin films

Electron transport is studied in surface oxidized single-crystal copper thin films with a thickness of up to 5.6 nm by applying density functional theory and density functional tight binding methods to determine electron transport properties within the ballistic regime. The variation of the electron transmission as a function of film thickness as well as the different contributions to the overall electron transmission as a function of depth into the the films is examined. Transmission at the oxidized copper film surfaces is found to be universally low. Films with thickness greater than 2.7 nm exhibit a similar behavior in local transmission per unit area with depth from the film surface; transmission per unit area initially increases rapidly and then plateaus at a depth of approximately 0.35--0.5 nm away from the surface, dependent on surface facet. Unstrained films tend to exhibit a higher transmission per unit area than corresponding films under tensile strain.

Demonstration of a sidewall capacitor to evaluate dielectrics and metal barrier thin films

A sidewall planar capacitor (SW CAP) vehicle is developed to closely simulate processing conditions for metal barrier and dielectric in an integrated structure. For a known tantalum barrier for copper on a low-K dielectric, SW CAP TDDB is similar to those measured on an integrated vehicle. SW CAP results are useful for comparing electrical reliability of different dielectric systems, and effective in determining physical continuity of copper metal barriers.

Demonstration of new planar capacitor (PCAP) vehicles to evaluate dielectrics and metal barrier thin films

Planar capacitors can quickly test material properties of metals and dielectrics for interconnects. A sidewall capacitor device is used to evaluate metal thin-film barriers. Etch stop planar capacitors in turn can test multi-layer etch stops, exposing differences between leaky and good etch stop films. Fillable planar capacitors are also fabricated and results presented for that class of fill materials.

Nickel silicide for interconnects

Nickel silicide is an attractive option for interconnects at small dimensions because of its short electron mean free path and good electromigration behavior. Nickel silicide interconnects can be integrated using either a subtractive or damascene process. Precise control of final metal composition ratio is important for obtaining low resistivity, as shown in thin-film and patterned structure measurements.