Paul A. Sullivan

A silicon-on-silicon multichip module technology with integrated bipolar components in the substrate

To address the needs of cost driven, mixed signal applications, we have developed a silicon-on-silicon technology that incorporates both passive and active devices in the module substrate. The technology combines a simple, double-diffused epitaxial bipolar technology with our thin-film MCMs. We describe the basic elements of the technology, typical active device properties and some examples of their use in a low-cost MCM.<<ETX>>

Thin film resistors and capacitors for advanced packaging

Integrated passive components are important for high frequency hybrid microelectronics. We have fabricated resistors using reactively sputtered TaN/sub x/ (x<0.5) and Ta/sub 2/Si thin films. We report on the resistivity, temperature coefficient of resistance (TCR), microstructure, composition, and thermal stability as a function of deposition conditions. The resistivity can be tuned, for example, by varying the nitrogen concentration. We have also fabricated capacitors with high capacitance density (70 nF/cm/sup 2/) using Ta/sub 2/O/sub 5/ dielectric films. The Ta/sub 2/O/sub 5/ dielectric films were prepared by various methods such as reactively sputtered Ta/sub 2/O/sub 5/, anodization of reactively sputtered TaN,, and anodization of Ta,Si films. We report on the capacitance density, leakage current, breakdown voltage, and dissipation factor up to high frequencies. We also report on the temperature coefficient of capacitance (TCC) and thermal stability of these capacitors during subsequent processing. A variety of analytical techniques were used to characterize the film properties. These anodic Ta/sub 2/O/sub 5/ capacitors have exceptionally low leakage currents (<1 nA/cm/sup 2/ at 10 V), high breakdown fields (>4 MV/rm), and high capacitance densities (70 nF/cm/sup 2/). The ac measurements of the capacitors showed ideal behavior up to 10 MHz Generally, anodic capacitors degrade upon subsequent processing above 200/spl deg/C due to dielectric and electrode metal interaction. By engineering the dielectric and the electrode materials, we have fabricated anodic Ta/sub 2/O/sub 5/ capacitors that are stable up to 350/spl deg/C with excellent capacitor properties. These capacitors are useful as integrated passive components for advanced packaging applications.

Tantalum pentoxide obtained from TaNx and TaSi2 anodisation: an inexpensive and thermally stable high k dielectric

Abstract We summarise the main performances of tantalum oxide films fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thickness ranging from 100 to 4500 A. These films exhibit greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Thermal treatments at temperatures up to 400°C do not degrade the insulator. We have proposed a set of selection guides to select the more appropriate process parameter values and electrode materials for a given application of these capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure. We have characterised the physical nature of the conduction mechanisms in the dielectric films. Poole–Frenkel effect and modified Poole–Frenkel effect from defect in the insulator are suggested. Finally, we report on conductance transient measurements ( G – t ) carried out on films of tantalum oxide fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thickness ranging from 100 to 4500 A. One of the causes of the good properties of anodic tantalum pentoxide is the presence of nitrogen atoms in the dielectric. The influence of the nitrogen content on the anodisation precursor is showed up along the paper.

Electrical characteristics of anodic tantalum pentoxide thin films under thermal stress

Abstract In this work, we report on electrical characteristics of tantalum oxide films fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thicknesses ranging from 100 to 4500 A. These films exhibit greatly improved leakage currents, breakdown voltage and a very low defect density, thus allowing the fabrication of large area capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure.

DLTS and conductance transient investigation on defects in anodic tantalum pentoxide thin films

In this work we report on deep level transient spectroscopy (DLTS) and conductance transient measurements (G-t) carried out on films of tantalum oxide fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thickness ranging from 10 to 450 nm. These films exhibit greatly improved leakage currents, breakdown voltage and very low defect density, thus allowing the fabrication of large area capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure. We have characterized the physical nature of the conduction mechanisms in the dielectric films. The Poole–Frenkel effect and the modified Poole–Frenkel effect are suggested. No DLTS signals have been obtained, because transients do not change for temperatures ranging from 77 to 300 K. Conductance transients have important dependencies on voltage bias pulse amplitude and frequency that seem to be closely related to the physical nature of the anodic tantalum pentoxide.