A.J. Hof

The impact of deuterated CMOS processing on gate oxide reliability

In recent literature, a controversy has arisen over the question whether deuterium improves the stability of the MOS gate dielectric. In particular, the influence of deuterium incorporation on the bulk oxide quality is not clear. In this letter, deuterium or hydrogen is introduced during either the gate oxidation, postoxidation anneal, and/or the postmetal anneal (PMA). The oxide bulk degradation was evaluated using charge-to-breakdown and stress-induced leakage current; and the oxide interface degradation using hot-carrier degradation and low-frequency noise. The obtained results show that the oxide bulk does not benefit from the presence of deuterium, regardless of the stage of deuterium introduction, or the gate oxide thickness. The oxide interface is more stable only when deuterium is introduced in the PMA.

Impact of hot-carrier degradation on the low-frequency noise in MOSFETs under steady-state and periodic large-signal excitation

This letter reports the diagnostic power of the low-frequency noise analysis (steady-state and periodic large-signal excitation) in MOSFETs subjected to hot-carrier degradation. The LF noise under periodic large-signal excitation is shown to increase more rapidly than the LF noise in steady-state. Moreover the improvement in the LF noise performance due to periodic large-signal excitation, observed for fresh devices, gradually diminishes as the devices are subjected to hot-carrier stress.

Low-frequency noise in hot-carrier degraded nMOSFETs

This paper discusses the low-frequency (LF) noise in submicron nMOSFETs under controlled transistor aging by hot-carrier stress. Both traditional, steady-state LF noise as well as the LF noise under periodic large-signal excitation were found to increase upon device degradation, for both hydrogen passivated and deuterium passivated Si–SiO2 interfaces. As hot-carrier degradation is slower in deuterium- annealed MOSFETs, so is the increase of the noise in these devices. The noise-suppressing effect of periodic OFF switching is gradually lost during hot-carrier degradation, as the LF noise under periodic large-signal excitation increases more rapidly than the LF noise in steady-state.

Reduced temperature dependence of hot carrier degradation in deuterated nMOSFETs

Deuterated oxides exhibit prolonged hot carrier lifetimes at room temperature. We report evidence that this improved hot carrier hardness exists over the temperature range between -25 °C and 200 °C. However, the benefit of deuterium incorporation deceases with increasing stress temperature. Furthermore the

On the Oxidation Kinetics of Silicon in Ultradiluted H2O and D2O Ambient

V_T

Gate oxide reliability and deuterated CMOS processing

-shift shows a remarkable absence of temperature dependence for the deuterated samples. The results are compared to the existing vibration-relaxation model.

An approach to modeling of silicon oxidationin a wet ultra-diluted ambient

This work presents a wide range of growth rate data of thin (1-60 nm) silicon oxides grown in an ultradiluted ambient of H2O or D2O in the temperature range 750-950 °C. A considerable and constant difference of 18% in oxidation rate is found between the two oxidizing species. Modeling of the obtained oxidation data with the Deal-Grove, Reisman, and Wolters models results in poor fits. The extracted activation energy suggests the presence of a rapid initial oxidation regime for the first 10 nm, not incorporated in the investigated models

Investigating Hot-Carrier Degradation in MOSFETs using Constant and Switched Biased Low-Frequency Noise measurements

In recent literature, a controversy has arisen over the question whether deuterium improves the stability of the MOS gate dielectric. It appears as if this controversy finds its origin in the different stages (e.g. oxidation or post metal anneal) deuterium is introduced in the CMOS process. This paper investigates this in detail. The obtained results show that the hot carrier degradation only benefits from an isotope effect when deuterium is introduced in the post metal anneal. At the same time, charge to breakdown for high quality oxides does not benefit from an isotope effect, regardless of the processing stage deuterium is introduced, or the gate oxide thickness used. This is verified on two different sets of wafers fabricated in two different laboratories.