55 nm硅-氧化硅-氮化硅-氧化硅-硅闪存单元的γ射线和X射线电离总剂量效应研究
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摘要
基于~(60)Co-γ射线和10 keV X射线辐射源,系统地研究了55 nm硅-氧化硅-氮化硅-氧化硅-硅闪存单元的电离总剂量效应,并特别关注其电学特性退化的规律与物理机制.总剂量辐照引起闪存单元I-V特性曲线漂移、存储窗口变小和静态电流增大等电学特性的退化现象,并对其数据保持能力产生影响.编程态闪存单元的I_d-V_g曲线在辐照后显著负向漂移,而擦除态负向漂移幅度较小.对比两种射线辐照,擦除态的I_d-V_g曲线漂移方向不同.相比于擦除态,富含存储电子的编程态对总剂量辐照更为敏感;且相比于~(60)Co-γ射线,本文观测到了显著的X射线剂量增强效应.利用TCAD和Geant 4工具,从能带理论详细讨论了55 nm硅-氧化硅-氮化硅-氧化硅-硅闪存单元电离总剂量效应和损伤的物理机制,并模拟和深入分析了X射线的剂量增强效应.
The total ionizing dose(TID) effects on 55 nm SONOS flash cell, caused by ~(60)Co-γ ray and 10 keV X-ray radiation source, are systematically investigated in this paper. The degradation of electrical characteristics is discussed while the underlying physical mechanism is analyzed. The drift of I-V characteristic curve, the degradation of memory window, and the increase of stand-by current are observed after TID irradiation separately by the two radiation sources. The data retention capability is also affected by the TID irradiation.The I-Vg curve of the programmed single flash cell significantly drifts towards the negative direction after TID irradiation, while the negative drift of erased state is much slower. Referring to the erased state, the drift directions of I_d-V_g curves for γ-and X-ray radiation source are obviously different. The physical mechanism of irradiation damage in a 55 nm SONOS single flash cell is discussed in detail by the energy band theory and TCAD simulations. The storage charge loss in silicon nitride layer, the charge accumulation, and the generation of interface states all together lead to the degradation of threshold voltage and stand-by current after TID irradiation. Another cause for the increase of stand-by current is the positive trapped charges in the isolated oxide induced by irradiation, which leads to the generation of leakage paths. Significant dose enhancement effect of X-ray irradiation is observed in this paper. Device model of memory transistor c is established while the dose enhancement effect of X-rays is investigated by Geant 4 tool. The high-Z materials above the polysilicon gate lead to the dose enhancement effect of X-rays' irradiation, which results in the higher degradation.The density of electron-hole pairs produced by irradiation in W layer is much higher than in Cu layer. In particular, W layer is a critical factor regardless of the thickness, which can be obviously observed in the simulation.
The total ionizing dose(TID) effects on 55 nm SONOS flash cell, caused by ~(60)Co-γ ray and 10 keV X-ray radiation source, are systematically investigated in this paper. The degradation of electrical characteristics is discussed while the underlying physical mechanism is analyzed. The drift of I-V characteristic curve, the degradation of memory window, and the increase of stand-by current are observed after TID irradiation separately by the two radiation sources. The data retention capability is also affected by the TID irradiation.The I-Vg curve of the programmed single flash cell significantly drifts towards the negative direction after TID irradiation, while the negative drift of erased state is much slower. Referring to the erased state, the drift directions of I_d-V_g curves for γ-and X-ray radiation source are obviously different. The physical mechanism of irradiation damage in a 55 nm SONOS single flash cell is discussed in detail by the energy band theory and TCAD simulations. The storage charge loss in silicon nitride layer, the charge accumulation, and the generation of interface states all together lead to the degradation of threshold voltage and stand-by current after TID irradiation. Another cause for the increase of stand-by current is the positive trapped charges in the isolated oxide induced by irradiation, which leads to the generation of leakage paths. Significant dose enhancement effect of X-ray irradiation is observed in this paper. Device model of memory transistor c is established while the dose enhancement effect of X-rays is investigated by Geant 4 tool. The high-Z materials above the polysilicon gate lead to the dose enhancement effect of X-rays' irradiation, which results in the higher degradation.The density of electron-hole pairs produced by irradiation in W layer is much higher than in Cu layer. In particular, W layer is a critical factor regardless of the thickness, which can be obviously observed in the simulation.
引文
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[4]Takeuchi H,King T J 2003 IEEE Electr.Device Lett.24 309
[5]Cellere G,Paccagnella A,Lora S,Pozza A,Tao G 2004 IEEETrans.Nucl.Sci.51 2912
[6]Cellere G,Paccagnella A,Visconti A,Bonanomi M,Candelori A 2006 IEEE Trans.Nucl.Sci.52 2372
[7]Oldham T R,Mclean F B 2003 IEEE Trans.Nucl.Sci.50483
[8]Bi J S,Han Z S,Zhang E X,Mccurdy M W,Reed R A,Schrimpf R D,Fleetwood D M,Alles M L,Weller R A,Linten D,Jurczak M,Fantini A 2013 IEEE Trans.Nucl.Sci.60 4540
[9]Fleetwood D M 2013 IEEE Trans.Nucl.Sci.60 1706
[10]Wang Z,Liu C,Ma Y,Wu Z,Wang Y 2015 IEEE Trans.Nucl.Sci.62 527
[11]Bi J S,Xi K,Li B,Wang H B,Ji L L 2018 Chin.Phys.B 27098501
[12]Oldham T R,Chen D,Friendlich M,Carts M A,Seidleck CM,LaBel K A 2011 IEEE Trans.Nucl.Sci.58 2904
[13]Petrov A,Vasil’ev A,Ulanova A,Chumakov A,Nikiforov A2014 Central Eur.J.Phys.12 725
[14]Duncan A R,Gadlage M J,Roach A H,Kay M J 2016 IEEETrans.Nucl.Sci.63 1276
[15]Bagatin M,Gerardin S,Paccagnella A,Visconti A,Bonanomi M 2015 IEEE Trans.Nucl.Sci.62 2815
[16]Snyder E S,McWhorter P J,Dellin T A,Sweetman J D 1989IEEE Trans.Nucl.Sci.36 2131
[17]Puchner H,Ruths P,Prabhakar V,Kouznetsov I,Geha S2014 IEEE Trans.Nucl.Sci.61 3005
[18]Adams D A,Mavisz D,Murray J R,White M H 2002 IEEE Aerospace Conference Proceedings(Cat.No.01TH8542)Big Sky,MT,USA,March 10-17,2001 p2295
[19]Adams D A,Smith J T,Murray J R,White M H,Wrazien S2005 2004 Proceedings IEEE Computational Systems Bioinformatics Conference Stanford,CA,USA,November 17,2004 p36
[20]Qiao F,Yu X,Pan L,Ma H,Wu D,Xu J 2012 19th IEEEInternational Symposium on the Physical and Failure Analysis of Integrated Circuits Singapore,July 2-6,2012 p1
[21]Bassi S,Pattanaik M 2014 18th International Symposium on VLSI Design and Test Coimbatore,India,July 16-18,2014p1
[22]Qiao F,Pan L,Blomme P,Arreghini A,Liu L 2014 IEEETrans.Nucl.Sci.61 955
[23]Qiao F Y 2013 Ph.D.Dissertation(Beijing:Tsinghua University)(in Chinese)[谯凤英2013博士学位论文(北京:清华大学)]
[24]Yoshii I,Hama K,Maeguchi K 1989 IEEE Trans.Nucl.Sci.36 2124
[25]Li L L,Yu Z G,Xiao Z Q,Zhou X J 2011 Acta Phys.Sin.60098502(in Chinese)[李蕾蕾,于宗光,肖志强,周昕杰2011物理学报60 098502]
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[27]Ning B X,Zhang Z X,Liu Z L,Hu Z Y,Chen M 2012 Microelectron.Reliab.52 130
[28]Liu Z L,Hu Z Y,Zhang Z X,Shao H,Ning B X 2011 Acta Phys.Sin.60 116103(in Chinese)[刘张李,胡志远,张正选,邵华,宁冰旭2011物理学报60 116103]
[29]Pei Y P,Huang R,An X,Liu W,Tian J Q 2012 J.Appl.Phys.51 1295
[30]Barnaby H J 2006 IEEE Trans.Nucl.Sci.53 3103
[31]Chen P X,Zhou K M 1997 Physics 12 725(in Chinese)[陈盘训,周开明1997物理12 725]
[32]Wu Z X,He C F,Lu W,Guo Q,Aierken A 2013 Nucl.Technol.36 060201(in Chinese)[吴正新,何承发,陆妩,郭旗,艾尔肯·阿不列木2013核技术36 060201]
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[35]Allison J,Amako K,Apostolakis J,Arce P,Asai M 2016Nucl.Instrum.Meth.A 835 186
[36]Allison J,Amako K,Apostolakis J,Araujo H,Dubois P A2006 IEEE Trans.Nucl.Sci.53 270
[37]Agostinelli S,Allison J,Amako K,Apostolakis J,Araujo H2003 Nucl.Instrum.Meth.A 506 250