No abstract

The effect of electron traps on the current-voltage (J-V) relationship and the charge distribution in insulators, under conditions of space-charge-limited current flow, is well understood. This paper extends the consideration of trapping effects into the region of emission-limited current flow. Trapped space charge distorts the field in the insulator so that the usual J-V relationship for emission-limited current in a vacuum, J ∝ exp [(constant) V½], which is often applied to insulators, will not be observed initially. It is shown that at sufficiently high voltages, however, the trapped space charge becomes negligible and the above J-V relationship is obtained. A calculation is done to obtain the J-V characteristic in an insulator throughout the emission-limited region, for typical values of trapping depth, trapping density, and barrier height. The resulting curves show that the transition from space-charge-limited to emission-limited current occurs at reasonable voltages, and that at these voltages, space-charge effects are large enough to be readily observed in practice. It is shown that the absence of space-charge effects at higher voltages is a consequence of field lowering of the barriers around trapping sites. In addition, several general results are obtained concerning field and charge distributions in insulators containing traps.

Electromigration-induced failure of near-bamboo interconnects depends strongly on the number and lengths of both polygranular clusters and bamboo segments in a line. We have used numerical techniques to calculate the stress profile as a function of position and time for near-bamboo lines with a variety of microstructures. Our results show that coupling of stress profiles between nearby clusters can affect the time to reach a pre-defined critical, or failure, stress. The degree of coupling depends both on the spacing between clusters and the ratio of the diffusivities between polygranular and single crystal regions. Electromigration failure is therefore sensitive to the distribution and lengths of bamboo segments, and the likelihood of long polygranular clusters coinciding with adjacent short bamboo segments.

Silicon oxynitride was formed by rf reactive sputtering of silicon in mixtures of N~ + N20. The dependence of dielectric constant, etch rate, breakdown strength, and IR transmittance on the N20 concentration in the plasma was determined. Five to ten per cent N20 gave an average breakdown strength of 1.1 x l0 T V/cm for metal-insulator-metal capacitors having molybdenum electrodes. The other capacitor parameters were also measured. An explanation of the high breakdown strengths in these capacitors is suggested.The properties of rf reactively sputtered silicon nitride and silicon oxynitride have been studied as part of a program to investigate new dielectric materials for use in passive components in integrated circuits,