We have monitored the 610 MHz flux density of 21 pulsars on a daily basis for five years. The flux density time series for these pulsars range from nearly constant for the most distant and heavily scattered pulsars to rapidly varying, saturated time series for more nearby pulsars. The measured stability of the flux density from the most distant pulsars (variations less than 5%) implies that the average radio emission from pulsars, before it has been affected by propagation through the ISM, is constant in strength over five years. The flux variations for 12 of the pulsars are consistent with a Kolmogorov turbulence spectrum over a range of more than three orders of magnitude in scattering strength, with no detectable presence of an inner scale (si ≥ 107cm). The flux variations are greater than predicted by this model for five pulsars – including the Crab and Vela – but this group is consistent with a Kolmogorov spectrum and an inner scale of ∼ 1010cm.

Electromigration lifetimes of multilayered metallizations of Al alloy (Al-0.5%Cu-l.0%Si) sandwiched with refractory metal films have been correlated to the interconnect microstructure and interactions with the underlying layer. In this study, Median Time to Failure (t50%, MTTF) data was obtained for multilayered Al alloy films by varying the Al deposition temperature from 200°C to 400° and the composition of the underlying substrate films. The Al alloys examined in this study were deposited over substrate films of sputtered Ti, reactively sputtered TiN and CVD TEOS deposited SiO2. All Al alloys were capped with a reactively sputtered TiN layer and covered with passivation.

Physical characterization using TEM, XRD, SIMS, and AFM, was performed to determine the microstructural and chemical properties of the films and correlate them to the MTTF of the packaged interconnects. The role of material properties such as the grain size and interactions of the metallization with the underlying layers were found to substantially impact the electromigration lifetime.

Based on data obtained from these studies, a number of interconnect metallization options will be discussed with respect to reliability and associated integration issues.

A wide range of electrode materials have been investigated for use in ferroelectric-silicon CMOS technology. Numerous metal and metal-oxide films were deposited on silicon substrates and coated with sol-gel derived ferroelectric thin films. The films were sintered in either a diffusion furnace or by rapid thermal processing. Transmission electron microscopy was used to investigate the evolution of the resulting ferroelectric thin film microstructure and ferroelectric / electrode material interactions.

Microstructural differences such as the volume fraction of the ferroelectric perovskite and pyrochlore phase, domains and grain structure are correlated with electrical results. A strong microstructural dependence on the substrate was found for the Cr, Zr, Hf and Ni electrode materials. In general, chromium and other metal-oxide films had high leakage currents and large volume fractions of the non-ferroelectric pyrochlore phase. Nickel electrodes displayed the best electrical results, but the microstructure is very different from the other ferroelectric films.

Annealing behavior in oxygen ambients of the of the ferroelectric PZT on Hf and Zr electrodes has been studied in the temperature range of 500-800°C using the 3.045MeV O16(∝,∝)O16 resonance in backscattering spectrometry. Internal oxidation of the buried metal electrode was observed. Oxygen concentration of the PZT film decreases with increasing temperature. Pb loss of the PZT film occurred above 700°C.

Thin film ferroelectric structures are being investigated for use as storage capacitors for Non-volatile Random-Access Memories. To integrate ferroelectrics with standard silicon semiconductor processing, a great deal of effort must be spent identifying compatible materials. These materials must be able to withstand both ferroelectric and silicon processing steps involving different temperatures and environments.

In this paper we have used Rutherford backscattering spectrometry (RBS) to study the diffusion of ferroelectric Pb(Zr.5Ti.5)O3 elements into thin films of TiOx, TiNx, ZrNx and ZrOx deposited onto thermally grown SiO2. The sample matrix was annealed at various temperatures in argon ambient and analyzed using 2 MeV He+. Diffusion profiles (concentration vs. depth profiles) of the ferroelectric constituents were determined for the different barrier films. Results indicated that ZrN is the most promising barrier layer so far, having shown the least interdiffusion at 700°C.

Low energy (6 keV) BF2 implantation was carried out using single crystal, Ge-preamorphized, and Si-preamorphized silicon substrates. Implanted substrates were rapid thermal annealed at temperatures from 600°C to 1050'C and boron channeling, diffusion, and activation were studied. Ge and Si preamorphization energies were chosen to produce nearly identical amorphous layer depths as determined by TEM micrographs (approximately 40 nm in both cases). Boron segregation to the end-of-range damage region was observed for 6 keV BF2 implantation into crystalline silicon, although none was detected in preamorphized substrates. Junction depths as shallow as 50 nm were obtained. In this ultra-low energy regime for ion implantation, boron diffusion was found to be as important as boron channeling in determining the junction depth, and thus, preamorphization does not result in a significant reduction in junction depth. However, the formation of junctions shallower than 100 rmu appears to require RTA temperatures below 1000°C which can lead to incomplete activation unless the substrate has been preamorphized. In the case of preamorphized samples, Hall measurements revealed that nearly complete electrical activation can be obtained for preamorphized samples after a 10 second rapid thermal anneal at temperatures as low as 600°C.