Emilien Bouyssou

Leakage current evolution versus dielectric thickness in lead zirconate titanate thin film capacitors

In this paper, the evolution of lead zirconate titanate (PZT) capacitor leakage current mechanism as a function of dielectric thickness has been investigated. It has been pointed out that PZT leakage current switches from Schottky to Poole–Frenkel conduction mechanisms as PZT thickness decreases. The leakage current evolution seems to be dependant on the presence of a dead layer at metal/PZT interface. The dead layer thickness is estimated at about 40 nm. The switch from an interface limited conduction mode to a bulk limited mode can be attributed to the presence of a higher defect concentration in the dead layer in comparison with PZT bulk.

Understanding the Failure Mechanisms of Protection Diodes During System Level ESD: Toward Repetitive Stresses Robustness

In electronic systems, the ever-increasing level of integration is paced by component scaling. Consequently, system-level protection improvements in electrostatic discharge (ESD) reliability during a devices lifetime are mandatory. To this end, we have investigated bidirectional system-level ESD protection diodes that have been subjected to repetitive human metal model stresses. Our goal was to develop robust ESD components by understanding the physical and electrical behaviors of components after multiple ESD surges. In this paper, three ESD-induced failure modes of protection devices are demonstrated and analyzed in terms of severity, i.e., charge trapping in the silicon-oxide interface, metallic diffusion toward the contacts, and melted filaments in the silicon bulk at the junction periphery.

Percolation theory applied to PZT thin films capacitors breakdown mechanisms.

Abstract Time-Dependent Dielectric Breakdown (TDDB) mechanisms remain the key issue to understand in order to enhance the reliability of new capacitors technologies. In this work we tried to model capacitors failure mechanism according to percolation theory, in agreement with the statistical behavior of PZT capacitors times to breakdown ( t bd ). The role of microstructural defects such as interlayers and cavities in failure mechanism has been emphasized.

Impact of Lanthanum on PZT Resistance Degradation

This work presents the impact of lanthanum doping on PZT leakage current behavior by comparing the amplitude of the maximum Schottky barrier lowering between PZT and lanthanum doped PZT (PLZT). PZT and PLZT films have been also estimated in terms of capacitors reliability. The time to breakdown distribution obtained with PLZT capacitors drifts by a factor 2.5, which tends to demonstrate also the benefits of lanthanum doping on improving reliability.

Cavity origin and influence on reliability in lead zirconate titanate thin film capacitors

This paper deals with the origin of void defects in lead zirconale titanate (PZT) microstructure, appearing after top electrode postdeposition heat treatment. The process conditions of void apparition are especially investigated, as well as the consequences of these defects on capacitor’s electrical properties. We point out that structures presenting the biggest cavities exhibit the shortest time to breakdown (tbd). This result indicates that cavities might play an important role in PZT capacitor degradation mechanisms.

ELECTRICAL CHARACTERIZATION AND RELIABILITY OF LANTHANUM DOPED PZT THIN FILMS CAPACITORS

ABSTRACT The resistance degradation phase of PZT capacitors leakage current is known to be related to the migration of oxygen vacancies species under a constant voltage stress. This phenomenon is associated with an increasing leakage current up to two orders of magnitude, and it is usually attributed to a Schottky barrier height lowering induced by the accumulation of oxygen vacancies at the cathode interface. Waser et al. [1] emphasized the role of oxygen vacancies by correlating the effect of donor doping on the amplitude of the resistance degradation. In the behavioral model of leakage current evolution developed by Zafar et al. [2], the oxygen vacancies concentration can be qualitatively determined by evaluating the maximum barrier lowering at the end of the resistance degradation process. By comparing the amplitude of maximum Schottky barrier lowering at the end of the degradation resistance mechanism between PZT capacitors and PLZT capacitors, this work points out the influence of lanthanum doping on oxygen vacancies concentration. Moreover, the role of oxygen vacancies is also featured by evaluating the reliability behavior: the times to breakdown distribution obtained with PLZT capacitors drifts by a factor of 2.5 in comparison with PZT capacitors. This result tends to demonstrate the role of lanthanum doping on reliability improvement.

Investigation on Statistical Tools to Analyze Repetitive-Electrostatic-Discharge Endurance of System-Level Protections

To fulfill the requirement of final-user uncontrolled ESD environment, system-level ESD protection devices must survive repeated ESD stresses. This paper deals with the assessment of ESD protection device reliability toward repetitive stresses using statistical distribution. The proposed method could lead to better ESD robustness improvement than the simplistic “higher ESD robustness” requirement.

Electrothermal model for MIM TaON capacitors during ESD HBM pulses

This work focuses on ESD HBM robustness of metal insulator metal TaON capacitors. An electrothermal model including a complete leakage current description and a thermal RC network is proposed to explain the ESD experimental results. The leakage current description is based on a Poole-Frenkel mechanism combined with a TDDB theory.

Reliability study of TaON capacitors : From leakage current characterization to ESD robustness prediction

Abstract Electrostatic discharges are a permanent threaten for integrated metal–insulator–metal capacitors. Hence, the development of comprehensive models able to predict the capacitors robustness against ESD aggression is of major importance to adopt the adequate protection strategies. This work focuses more particularly on the failure mechanisms of TaON capacitors submitted to HBM ESD waves. From leakage current characterization to thermal dissipation effects, we propose a complete reliability model which accurately foresees not only ESD failure voltage, but also TDDB capacitors lifetime.

TDDB characterization of BST capacitors exhibiting bimodal Weibull distributions

BST thin-film capacitors breakdown have been studied as a function of applied voltage and temperature. This paper deals with a bimodal behaviour observed from Time Dependent Dielectric Breakdown (TDDB) experiments. This double population makes it difficult to assess properly the components reliability. We show that these two populations are related to two intrinsic and distinct failures. Through an extensive study of leakage current conduction mechanisms, we exhibit that the Poole-Frenkel model can be used for both populations with two distinct trap heights of 0.6 and 0.9 eV directly related to this reliability behaviour.