Electrical and Irradiation Performance of MNOS Arrays

Abstract

This paper describes the methods used to evaluate and characterize MNOS arrays and includes test data on the most important parameters of such arrays from the standpoint of large systems. MNOS 256-bit and 2240-bit charge storage memory arrays are evaluated, primarily, in terms of switching speed, level separation uniformity across the chip, nonvolatility, adjacent word disturb during writing, and the effects of temperature and γ-radiation. For a 2240-bit array, a minimum level separation of more than 5 volts across the chip was obtained using a 30 volt pulse with a one millisecond pulse width for writing and erasing and a read cycle time of 500 ns. The information can be stored for more than 10 years. The adjacent word disturb was less than 3% after 20000 successive write-clear cycles and it was not cumulative. There was no degradation of the cell after 109 successive cycles. In the temperature range -55 to +125°C, there was little degradation in the writing, erasing and storage characteristics. Useful information can be stored at radiation levels of up to 5×105 Rads (Si). The window is completely closed after a dosage of 106 Rads (Si), in good agreement with the model developed during this study.

Electromigration-induced drift in damascene and plasma-etched Al(Cu). I. Kinetics of Cu depletion in polycrystalline interconnects

“…While the stable intergranular precipitates coarsen rapidly as aging proceeds, the Ј phase inside the grains gradually transforms into relatively small intragranular -Al 2 Cu. 12 This evolution qualitatively corresponds to the observations of Fig. 3.…”

“…Although the size of Ј particles after deposition is significantly lower, Ј precipitates growing as large as 0.040 m 2 after aging have been reported by others. 12 On the other hand, area counting based only on top-view SEM unavoidably introduces errors, especially for precipitates inclined relative to the top surface. This certainly holds in the case of Ј -Al 2 Cu, which is typically plate-like and coherent on their ͕100͖ planes with the Al lattice.…”

“…11 As compared to the initial EM studies, aiming at a more fundamental understanding of the beneficial effect of Cu solutes, systematic reports on the effect of Al 2 Cu precipitation have only been published more recently. 12,13 This may be attributed partly to the introduction of new EM test structures at the beginning of this decade, around the same time as the introduction of W plugs in multilevel metalliza-a͒ Also with: Dept. of Materials Science, de Croylaan 2, B-3001 Leuven, Belgium, electronic mail: proost@deas.harvard.edu tion.…”

Control of Microstructure in Iron–Carbon Thin Films by Means of Electromigration

“…Prior to the formation of electromigration‐induced voids and hillocks, the early stages of electromigration‐induced transport may be expected to lead to redistribution of fast‐diffusing impurities and to changes in precipitate and grain structure. A few studies have observed the dissolution and formation of Cu‐based precipitates in Al due to electromigration, [ 10–12 ] which can be explained by flux divergences in the Cu atoms diffusing along the grain boundaries of Al. [ 10,13,14 ] One study performed under rather extreme electromigration conditions shows a single case of precipitate migration, [ 11 ] which according to modeling occurs by dissolution at one end of the precipitate and growth at the other.…”