Hopping and tunnelling trap assisted current in metallic oxide based non volatile memories

Defense of doctoral thesis by Nazim AIT ABDELKADER, for the  University  Grenoble Alpes, speciality  " NANO ELECTRONIC & NANO TECHNOLOGIES "

Abstract :
Resistive Random Acccess Memory, and more specifically Oxide RAM (OxRAM), are considered as key enabling technologies for emerging applications due to their high density, high speed, good endurance and integration in the back-end-of-line. However, the mechanisms that rule their conduction have been heavily debated in the last fifteen years. A new method, involving the solution of the traps Fermi levels is presented in this manuscript, to ensure constant current between traps, which allows to include two models for the conduction and avoid the identification of the most conducting path. A generalized Tsu-Esaki model is detailed, which is based on a conduction between continuum of states. It is found that this model is not able to provide a suitable fit of the current-voltages (I-V) curves in both resistance states of an OxRAM. A second model, based on Miller and Abrahams equation and hence on the conduction model between bound states has proved its ability to provide an excellent agreement with experimental data, employing a much more reasonable number of traps compared to already existing approaches. Thermal activation energy are finally computed to investigate the possibility to experimentally identify these mechanisms. Ultimately, an experimental component has been incorporated into this thesis. This involved an endeavor towards electrical characterization as a function of temperature, aiming to identify conduction mechansims involved in OxRAMs.

Jury members:  :

• Quentin RAFHAY, ASSISTANT PROFESSOR - HDR - Grenoble INP : Supervisor    
• Marc  BOCQUET, UNIVERSITY PROFESSOR - PROFESSEUR DES UNIVERSITES  - Aix-Marseille University : Reviewer
• Damien  QUERLIOZ, RESEARCH DIRECTOR - CNRS DELEGATION ILE-DE-FRANCE SUD : Reviewer
• Damien DELERUYELLE, UNIVERSITY PROFESSOR - INSA Lyon : Examiner
• Jean-Christophe TOUSSAINT, UNIVERSITY PROFESSOR - Grenoble INP : Examiner
• Abdelkader SOUIFI, UNIVERSITY PROFESSOR - INSA Lyon : Examiner