Improving the data retention of phase change memory by using a doping element in selected Ge_2Sb_2Te_5
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摘要
The crystallization characteristics of a ubiquitous T-shaped phase change memory(PCM) cell, under SET current pulse and very small disturb current pulse, have been investigated by finite element modelling. As analyzed in this paper, the crystallization region under SET current pulse presents first on the corner of the bottom electron contact(BEC) and then promptly forms a filament shunting down the amorphous phase to achieve the low-resistance state, whereas the tiny disturb current pulse accelerates crystallization at the axis of symmetry in the phase change material. According to the different crystallization paths, a new structure of phase change material layer is proposed to improve the data retention for PCM without impeding SET operation.This structure only requires one or two additional process steps to dope nitrogen element in the center region of phase change material layer to increase the crystallization temperature in this confined region. The electrical-thermal characteristics of PCM cells with incremental doped radius have been analyzed and the best performance is presented when the doped radius is equal to the radius of the BEC.
The crystallization characteristics of a ubiquitous T-shaped phase change memory(PCM) cell, under SET current pulse and very small disturb current pulse, have been investigated by finite element modelling. As analyzed in this paper, the crystallization region under SET current pulse presents first on the corner of the bottom electron contact(BEC) and then promptly forms a filament shunting down the amorphous phase to achieve the low-resistance state, whereas the tiny disturb current pulse accelerates crystallization at the axis of symmetry in the phase change material. According to the different crystallization paths, a new structure of phase change material layer is proposed to improve the data retention for PCM without impeding SET operation.This structure only requires one or two additional process steps to dope nitrogen element in the center region of phase change material layer to increase the crystallization temperature in this confined region. The electrical-thermal characteristics of PCM cells with incremental doped radius have been analyzed and the best performance is presented when the doped radius is equal to the radius of the BEC.
The crystallization characteristics of a ubiquitous T-shaped phase change memory(PCM) cell, under SET current pulse and very small disturb current pulse, have been investigated by finite element modelling. As analyzed in this paper, the crystallization region under SET current pulse presents first on the corner of the bottom electron contact(BEC) and then promptly forms a filament shunting down the amorphous phase to achieve the low-resistance state, whereas the tiny disturb current pulse accelerates crystallization at the axis of symmetry in the phase change material. According to the different crystallization paths, a new structure of phase change material layer is proposed to improve the data retention for PCM without impeding SET operation.This structure only requires one or two additional process steps to dope nitrogen element in the center region of phase change material layer to increase the crystallization temperature in this confined region. The electrical-thermal characteristics of PCM cells with incremental doped radius have been analyzed and the best performance is presented when the doped radius is equal to the radius of the BEC.
引文
[1] Lai S. Current status of the phase change memory and its future.IEEE International Electron Devices Meeting, 2003,255
[2] Ovshinsky S R. Reversible electrical switching phenomena in disordered structures. Phys Rev Lett, 1968,21,1450
[3] Sun Z M, Zhou J, Ahuja R. Structure of phase change materials for data storage. Phys Rev Lett, 2006,96,055507
[4] Raoux S, Welnic W, lelmini D. Phase change materials and their application to nonvolatile memories. Chem Rev, 2009,110,240
[5] Kohary K, Wright C D. Electric field induced crystallization in phase-change materials for memory applications. Appl Phys Lett,2011,98,223102
[6] Li J M, Yang H M, Lim K G, Field-dependent activation energy of nucleation and switching in phase change memory. Appl Phys Lett, 2012,100,263501
[7] Lee B S, Bishop S G. phase change materials:optical and electrical properties of phase change materials. In:Springer Science+Business Media. New York, 2009,189
[8] Cai D L, Chen H P, Wang Q, et al. An 8-mb phase-change random access memory chip based on a resistor-on-via-stacked-plug storage cell. IEEE Electron Device Lett, 2012, 33,1270
[9] Liu Y, Song Z T, Ling Y, et al. Three-dimensional numerical simulation of phase-change memory cell with probe like bottom electrode structure. Jpn J Appl Phys, 2009,48,024502
[10] Xu Z, Liu B, Chen Y F, et al. The improvement of nitrogen doped Ge2Sb2Te, on the phase change memory resistance distributions.Solid-State Electron, 2016,116,119
[11] Johnson W A, Mehl R F. Reaction kinetics in processes of nucleation and growth. Trans Metall Soc AIME, 1939,135,416
[12] Volmer M, Weber A. Keimbildung in ubersattigten Gebilden.Zeitschrift fur physikalische Chemie, 1926,119,227
[13] Senkader S, Wright C D. Models for phase-change of Ge2Sb2Te5 in optical and electrical memory devices.J Appl Phys Lett, 2004,95(2), 504
[14] Bae J H, Kim B G, Byeon D S, et al. Simulation for thickness change of PRAM recording layer. J Ceram Soc Jpn, 2009,117(5), 588
[15] Gong Y F, Song Z T, Ling Y, et al. Simulation of voltage SET operation in phase-change random access memories with heater addition and ring-type contactor for low-power consumption by finite element modeling. Chin Phys Lett, 2010,27, 068501
[2] Ovshinsky S R. Reversible electrical switching phenomena in disordered structures. Phys Rev Lett, 1968,21,1450
[3] Sun Z M, Zhou J, Ahuja R. Structure of phase change materials for data storage. Phys Rev Lett, 2006,96,055507
[4] Raoux S, Welnic W, lelmini D. Phase change materials and their application to nonvolatile memories. Chem Rev, 2009,110,240
[5] Kohary K, Wright C D. Electric field induced crystallization in phase-change materials for memory applications. Appl Phys Lett,2011,98,223102
[6] Li J M, Yang H M, Lim K G, Field-dependent activation energy of nucleation and switching in phase change memory. Appl Phys Lett, 2012,100,263501
[7] Lee B S, Bishop S G. phase change materials:optical and electrical properties of phase change materials. In:Springer Science+Business Media. New York, 2009,189
[8] Cai D L, Chen H P, Wang Q, et al. An 8-mb phase-change random access memory chip based on a resistor-on-via-stacked-plug storage cell. IEEE Electron Device Lett, 2012, 33,1270
[9] Liu Y, Song Z T, Ling Y, et al. Three-dimensional numerical simulation of phase-change memory cell with probe like bottom electrode structure. Jpn J Appl Phys, 2009,48,024502
[10] Xu Z, Liu B, Chen Y F, et al. The improvement of nitrogen doped Ge2Sb2Te, on the phase change memory resistance distributions.Solid-State Electron, 2016,116,119
[11] Johnson W A, Mehl R F. Reaction kinetics in processes of nucleation and growth. Trans Metall Soc AIME, 1939,135,416
[12] Volmer M, Weber A. Keimbildung in ubersattigten Gebilden.Zeitschrift fur physikalische Chemie, 1926,119,227
[13] Senkader S, Wright C D. Models for phase-change of Ge2Sb2Te5 in optical and electrical memory devices.J Appl Phys Lett, 2004,95(2), 504
[14] Bae J H, Kim B G, Byeon D S, et al. Simulation for thickness change of PRAM recording layer. J Ceram Soc Jpn, 2009,117(5), 588
[15] Gong Y F, Song Z T, Ling Y, et al. Simulation of voltage SET operation in phase-change random access memories with heater addition and ring-type contactor for low-power consumption by finite element modeling. Chin Phys Lett, 2010,27, 068501