AVS 58th Annual International Symposium and Exhibition
    Electronic Materials and Processing Division Monday Sessions
       Session EM2-MoA

Paper EM2-MoA8
ALD/PEALD CMOS Compatible Oxides for Resistive RAM Devices

Monday, October 31, 2011, 4:20 pm, Room 210

Session: Dielectrics for Ultra Dense Memory Devices
Presenter: Amélie Salaün, CEA Leti, France
Authors: A. Salaün, CEA Leti, France
V. Beugin, CEA Leti, France
H. Grampeix, CEA Leti, France
C. Licitra, CEA Leti, France
N. Rochat, CEA Leti, France
E. Martinez, CEA Leti, France
P. Gergaud, CEA Leti, France
P. Gonon, LTM CNRS/CEA Leti, France
C. Vallée, LTM-CNRS/CEA Leti, France
C. Mannequin, CEA Leti, France
C. Gaumer, STMicroelectronics, France
S. Jeannot, STMicroelectronics, France
J. Buckley, CEA Leti, France
V. Jousseaume, CEA Leti, France
J.P. Barnes, CEA Leti, France
M. Veillerot, CEA Leti, France
F. Pierre, CEA Leti, France
I. Kieffer, CEA Leti, France
Correspondent: Click to Email
Due to an increase of memory needs, the investigation of novel technologies to improve data storage has emerged recently. Resistive Random Access Memories (ReRAMs) are considered as promising candidates for next generation non-volatile memory (NVM) downscaled applications. Compared with other NVM, ReRAM devices potentially offer high performances using a simpler fabrication process [1]. Metal-Insulator-Metal (MIM) structures including CMOS compatible materials such as NiO and HfO2 could be used for such applications as recently reported [2-3]. Moreover an improvement of ReRAM operational performances is obtained with downscaling. The mechanisms at the origin of the resistive switching have been recently reviewed [4] but not fully understood until now. The present work is focused on the physical and chemical characterization of high κ oxides frequently used in Metal-Insulator-Metal capacitors, such as HfO2, Ta2O5 and ZrO2, grown on various electrodes (Pt, TiN…) using Atomic Layer Deposition (ALD) and Plasma Enhanced Atomic Layer Deposition (PEALD). The structural properties of ALD films were studied as a function of the nature of bottom electrode, high κ thickness and annealing conditions using X-Ray Diffraction (XRD) and Attenuated Total Reflectance (ATR). Spectroscopic ellipsometry (SE) was performed in order to determine material refractive index (n) and band gap (Eg), but also to detect eventual interface or/and bulk defects. X-ray Photoelectron Spectroscopy (XPS), Rutherford Backscattering Spectrometry (RBS) and Secondary Ion Mass Spectrocopy (SIMS) depth profiling were required in order to get accurate data on impurities, layer stœchiometry and chemical composition of interfaces. Surface morphology and roughness were also observed using Atomic Force Microscopy (AFM). The resistive switching properties of stacks including various high κ oxides (HfO2, Ta2O5 and ZrO2) and electrodes (top & bottom) were tested for comparison, in order to conclude on the best candidates for the ReRAM device integration. Vacancy and defect engineering is considered to be key method for modifying the resistive switching behaviour (in terms of forming and set/reset voltages, retention…). Consequently, the correlation between structure (crystallinity, density, oxygen vacancies, impurities…), interface effects and the formation of the filament was investigated in detail in this work. [1] A. Sawa, Materials Today, 11 (2008) 28. [2] V. Jousseaume et al., Solid State Electronics, 58 (2011) 62. [3] P. Gonon et al. Journal of Applied Physics 107 (2010) 074507. [4] H. Akinaga and H. Shima, Proceedings of the IEEE, 98 (2010) 2237.