Time-dependent breakdown of silicon dioxide films

Raider, S. I.

doi:10.1063/1.1654726

Cited by 44 publications

(22 citation statements)

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“…Worthing (5) reported a time-dependent breakdown mechanism in MOS structures for silicon biased negatively and an intrinsic, time-independent mechanism for silicon positive. The breakdown time for Si (--) followed an empirical Peek's law relationship, i.e., E oc t-zz4, where t is the time to breakdown at field E; this time dependence is the same as that observed earlier by Raider (2) in sodium contaminated SiO2 films. Other work (4,(6)(7)(8) has failed to find this Peek's law behavior in high quality oxides.…”

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confidence: 73%

The Effect of Mobile Sodium Ions on Field Enhancement Dielectric Breakdown in SiO[sub 2] Films on Silicon

Osburn¹,

Raider²

1973

J. Electrochem. Soc.

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The presence of mobile sodium ions in SiO~ films, thermally grown on silicon, can lead to time-dependent conduction and subsequent dielectric breakdown. When this occurs, it will be shown that anomalously high (ten orders of magnitude) electronic currents can result, presumably because of a modification of the shape of the injecting barrier, due to the high electric field created by the presence of the uncompensated positive charge. The time (t) required to break down the SiO2 film under an applied field (E) was found to approximate the empirically known Peek's law relationship, i.e., E cc t-1/4. Moreover, it will be demonstrated that field enhancement in the oxide due to space charge effects provides the fundamental breakdown mechanism. Capacitance-voltage measurements of the silicon flatband voltage were used to determine the internally created field, and thereby to demonstrate that breakdown occurred when the total field reached the breakdown strength of the film. It will be seen that the limiting time before breakdown, with sodium-contaminated samples, correlates with the kinetics of ionic motion, e.g., it exhibits the same activation energy and varies roughly as the square of the oxide thickness. The other statistical variations in breakdown times can be quantitatively attributed to defects present in the starting oxide films.Despite the high reliability of solid-state semiconductor devices, increasing reliability requirements, particularly for large MOSFET memory arrays, make a thorough understanding of any time-dependent deterioration mechanism necessary. Since the gate oxide region of an FET is normally subjected to electric fields approaching one-fourth of the intrinsic breakdown strength of SiO2 (i.e., ~ 9 mV/cm), it is subject to dielectric breakdown. It has been known for some time that mobile ions (1) can be responsible for threshold voltage shifts over a period of time; nevertheless, little work has focused on the influence of mobile ions on the dielectric integrity of thermally grown SiO~ films. Recently, Raider (2) found that mobile ions can be responsible for time-dependent dielectric breakdown.Several recent papers (3-9) have been concerned with the dielectric breakdown of SiO2 layers on thermally grown Si. Wide variabilities in breakdown strength across a Si wafer were usually observed and attributed to oxide defects. Various materials and processing parameters were tested to determine their influence on defects. For example, sodium contamination was introduced during oxide growth in one study (7), but it did not increase the defect density although it did lower the maximum breakdown strength. Unfortunately, however, very little attention has been directed in the earlier work to the time dependence of breakdown in relatively defect-free SiO2 films, such as would be present in high quality MOSFET devices. Worthing (5) reported a time-dependent breakdown mechanism in MOS structures for silicon biased negatively and an intrinsic, time-independent mechanism for silicon positive. The breakdown time ...

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confidence: 73%

The Effect of Mobile Sodium Ions on Field Enhancement Dielectric Breakdown in SiO[sub 2] Films on Silicon

Osburn¹,

Raider²

1973

J. Electrochem. Soc.

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“…6͑a͒. 16 Copper atoms are partially dissolved into SiO 2 as mobile ions during the stress test. Mobile Cu ions drift from the positive Cu electrode to the negative Si substrate due to the application of an electric field.…”

Section: Discussionmentioning

confidence: 99%

Passivation effect of silicon nitride against copper diffusion

Miyazaki

Kojima

Hinode

1997

Journal of Applied Physics

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The use of Cu in ultralarge scale integrated ͑ULSI͒ conductors has resulted in the need to prevent Cu diffusion. We evaluated the passivation effect of plasma-enhanced chemical-vapor-deposited silicon nitride ͑PECVD-SiN͒ using secondary ion mass spectrometry and atomic absorption spectrometry. From these measurements, it was found that a large amount of Cu diffused through PECVD-SiN films during the heat treatments of the metallization process, probably due to the rapid diffusion paths along the microdefects of PECVD-SiN films. However, Cu contamination was barely detected in the current-voltage measurements and bias-temperature stressing tests of Cu/PECVD-SiN/SiO 2 /Si capacitors because the leakage current through SiN films slightly increased as a result of Cu diffusion. This result is attributed to the electric-field relaxation caused by a large number of electrons trapped in the PECVD-SiN films, of which the negative charge compensates the positive charge of Cu ions. Although the degradation of electrical characteristics is not explicitly observed in simulation using Cu/PECVD-SiN/SiO 2 /Si capacitors, Cu atoms reach Si devices in the actual process. Therefore, the passivation effect of PECVD-SiN films is insufficient to allow application to ULSI devices.

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“…Several researchers have shown that the injection of Cu ϩ ions from a Cu electrode into the dielectrics can accelerate the breakdown of MIS capacitors. 14,19,20 This is believed to be caused by the increase in electric field near substrate due to the pile up of Cu ϩ ions at the interface. The increasing electric field can transport more electrons from the substrate through the dielectrics.…”

Section: Time-dependent Dielectrics Breakdown Testsmentioning

confidence: 98%