AVS 58th Annual International Symposium and Exhibition
    Thin Film Division Wednesday Sessions
       Session TF1+EM-WeA

Invited Paper TF1+EM-WeA9
Characterizing the Effects of Processing on Materials for Phase Change and Spin Torque based Non-Volatile Memory Technologies

Wednesday, November 2, 2011, 4:40 pm, Room 109

Session: Nonvolatile Memory
Presenter: Eric Joseph, IBM T.J. Watson Res. Ctr.
Authors: E.A. Joseph, IBM T.J. Watson Res. Ctr.
R.M. Martin, IBM T.J. Watson Res. Ctr.
J.S. Washington, IBM T.J. Watson Res. Ctr.
D.W. Abraham, IBM T.J. Watson Res. Ctr.
S. Raoux, IBM T.J. Watson Res. Ctr.
J.L. Jordan-Sweet, IBM T.J. Watson Res. Ctr.
D. Miller, IBM Almaden Res. Ctr.
H.-Y. Cheng, Macronix International Co., Ltd, Taiwan, R.O.C.
M.C. Gaidis, IBM T.J. Watson Res. Ctr.
M. Gajek, IBM T.J. Watson Res. Ctr.
M. Breitwisch, IBM T.J. Watson Res. Ctr.
S.-C. Lai, Macronix International Co., Ltd, Taiwan, R.O.C.
Y. Zhu, IBM T.J. Watson Res. Ctr.
R. Dasaka, IBM T.J. Watson Res. Ctr.
R. Sawant, IBM T.J. Watson Res. Ctr.
D. Neumayer, IBM T.J. Watson Res. Ctr.
R.M. Shelby, IBM Almaden Res. Ctr.
H.-L. Lung, Macronix International Co., Ltd, Taiwan, R.O.C.
C.H. Lam, IBM T.J. Watson Res. Ctr.
N.C.M. Fuller, IBM T.J. Watson Res. Ctr.
Correspondent: Click to Email
Phase change memory (PCM) and spin-torque magnetic random access memory (ST-MRAM) have recently garnered significant interest for future non-volatile memory applications due to their promise for scalability beyond that of conventional DRAM and flash memory technologies. In addition, both PCM and ST-MRAM have potential to enable improvements in programming speed, low voltage operation and high endurance, as compared to current devices. However, the introduction of each technology not only brings with it new device challenges, but the fabrication process itself can also alter the properties of the materials, leading to performance degradation. In this work, we explore the effects of integration and processing on Ge2Sb2Te5 (GST) and CoFeB for PCM and ST-MRAM devices respectively, with relevance towards scaling to the 14nm node and beyond. Using multiple analysis techniques including time resolved laser reflectivity and X-ray diffraction, we determine that exposure to various etch and ash plasma chemistries can cause a significant reduction in the (re)crystallization speed of GST, while concurrently increasing the transition temperature from the rocksalt to the hexagonal phase. Furthermore, by utilizing optical emission spectroscopy, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) we are able to link the changes in crystallization to etch-induced modification of the GST stoichiometry. For CoFeB materials, vibrating sample magnetometry is used to determine the effect that plasma exposure (as used for both patterning and encapsulation) has on the magnetic moment. We find that even when relatively thick capping layers are present, magnetic moment can still be significantly degraded. The severity of this effect is heavily dependent on plasma chemistry. Further results of process-induced material modification and device degradation as a function of etch, encapsulation, and thermal processing will be presented, focusing primarily on the impact on scaling of these technologies. Finally, potential integration and processing solutions to circumvent these issues will also be discussed.