Contribution au Développement de Méthodes Electriques pour la Caractérisation de la Dégradation NBTI

Abstract

Miniaturization of microelectronic components has resulted in an aggressive shrinking of the transistor gate dielectric thickness. With this size reduction, the reliability of transistors becomes critical, from one technology node to another, in terms of life prediction. Among the critical aspects, the NBTI/PBTI (Negative/Positive Bias Temperature Instability) degradation represents one of the major challenges in terms of reliability. This degradation is induced by the creation of traps in the gate dielectric and at the substrate/dielectric interface as well as their charge and discharge. Their study and modeling are becoming important in the current context of the microelectronics industry. Based on electrical methods, this thesis focuses on study and experimental characterization of NBTI/PBTI degradation. To do so, we have first studied the interface traps induced by BTI stress using OTFIT (on-the-fly interface trap) method, where we have proposed a model based on the reaction-diffusion (RD) of H +, H and H2 species. Secondly, we have evaluated the mobility degradation induced by NBTI stress using the geometric component of charge pumping (CP). In addition, we have implemented measurement techniques based on short measurement time (delay). In fact, we have implemented a fast Id-Vg technique for NBTI characterization with a measurement time of 10 µs. Finally, the impact of the dimensions of FinFET transistors on the BTI degradation has been conducted using the eMSM (extended Measure-Stress-Measure) technique, the latter offers a better measurement time (1ms) and captures a valuable quantity of information on transistor behavior under BTI stress. We have shown that FinFET transistors with taller fins are less affected by NBTI stress than those with lower fins. We believe this is related to a higher defectively in fin corners. In addition, the experimental results show higher activation energies for the lower fins compared to that of the taller ones. The PBTI shows a similar trend to that of the NBTI on increasing fin height, albeit with little or no significant temperature dependence.