Intel 3D Crosspoint(XPoint)Memory關(guān)鍵技術(shù)點(diǎn)及意義

1、Intel 3D CrosspointIntel 3D Crosspoint（XPointXPoint）MemoryMemory關(guān)鍵技術(shù)點(diǎn)關(guān)鍵技術(shù)點(diǎn)及意義及意義張貴福張貴福 學(xué)號：學(xué)號：P15104038單位：中物院研究生院單位：中物院研究生院報(bào)告提綱1.1. IntelIntel發(fā)布的發(fā)布的RRAMRRAM2.2. RRAMRRAM簡介簡介3.3. RRAMRRAM材料及機(jī)理材料及機(jī)理4.4. 關(guān)鍵技術(shù)點(diǎn)猜測與展望關(guān)鍵技術(shù)點(diǎn)猜測與展望5.5. 小結(jié)（意義）小結(jié)（意義）6.6. 參考文獻(xiàn)參考文獻(xiàn)7.7. 附圖附圖IntelIntel發(fā)布的發(fā)布的RRAMRRAM3DXpoint的基本特點(diǎn)的基本特

2、點(diǎn) 由橫豎交叉的位線(BL)、字線(WL)、選擇門(selector)、記憶單元(memory cell)等組成工作原理：通過縱橫的字線位線之間的電阻值作為01二進(jìn)制信息，綠色塊的電阻(memory cell)用來儲存信息;灰色塊 (selector)可以控制改變綠色塊電阻，選擇讀或?qū)?。核心問題并沒有公布：1.1. SelectorSelector的工作原理和制作材料的工作原理和制作材料2.2. MemoryCell MemoryCell 的工作原理和制作材料的工作原理和制作材料RRAM-RRAM-Resistive Random Access Memory 阻變隨機(jī)存儲器 無源1D1R（1S

3、1R） 有源1T1R 單極型 雙極型RRAMRRAM簡介簡介來自講義來自講義RRAMRRAM存儲單元存儲單元其他已有的其他已有的存儲單元存儲單元1. 寫（Write）操作參數(shù)Vwr，twr Vwr為寫入電壓。一般在幾百mV至幾V之間；twr為寫入數(shù)據(jù)時(shí)間。傳統(tǒng)器件中，DRAM、SRAM和Flash的twr分別為100ns、10ns和10us數(shù)量級。為了與傳統(tǒng)器件相比顯示出優(yōu)勢，RRAM的twr期望可以達(dá)到100ns數(shù)量級甚至更小。2. 讀（Read）操作參數(shù)Vrd，Ird，trd Vrd為讀取電壓。一般Vrd值要明顯小于Vwr，而由于器件原理限制，Vrd亦不能低于Vwr的1/10。Ird為讀操

4、作所需電流。一般不能低于1uA。trd為讀操作時(shí)間，與twr同等數(shù)量級甚至更小。3. 開關(guān)電阻比值 ROFF/RON ROFF和RON分別為器件處于關(guān)態(tài)與開態(tài)時(shí)的元件阻值。盡管在MRAM中，大小僅為1.21.3的ROFF/RON亦可以被應(yīng)用，對RRAM的ROFF/RON一般要求至少達(dá)到10以上，以減小外圍放大器的負(fù)擔(dān)，簡化放大電路。4. 器件壽命 指器件能夠正常維持工作狀態(tài)的周期數(shù)目。一般，NVM器件的工作壽命希望達(dá)到1012周期。5. 保持時(shí)間tret保存數(shù)據(jù)信息的時(shí)間。一般需要保持10年甚至更久。 RRAM的幾個(gè)主要性能參數(shù)之間，存在制約的關(guān)系，如Vrd與Vwr的比值受到tret和trd限

5、制。故而尋求高密度、低功耗的理想RRAM器件，需要從各個(gè)性能參數(shù)的角度共同考慮，尋求最佳的平衡點(diǎn)。RRAMRRAM簡介簡介主要器件參數(shù)RRAMRRAM簡介簡介比較供選材料摘自博士論文新型阻變存儲器材料及其電阻轉(zhuǎn)變機(jī)理研究_陳超RRAM材料和機(jī)理RRAM阻變材料主要關(guān)心的導(dǎo)電類型（目前物理意義明確）單極型材料：金屬導(dǎo)電細(xì)絲熔斷/ 連接ECM雙極型材料：氧空位致導(dǎo)電細(xì)絲通斷VCM（局域效應(yīng)類）摘自： R. Waser, R. Dittmann, G. Staikov, et. al, Redox-based resistive switching memories nanoionic mechan

6、isms, prospects, and challenges, Adv. Mater., 2009, 21, 2632-2663最新機(jī)理文章”Thermometry of Filamentary RRAM Devices”IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 62, NO. 9, SEPTEMBER 2015. 以HfOx為研究對象單純電阻構(gòu)成的crossbar結(jié)構(gòu)，存在大量的竄擾。根據(jù)材料不同形成了幾種結(jié)構(gòu)：1T1R1T1R 、1D1R1D1R、1S1R1S1R、1R1R單極型材料1D1R雙極型材料具備自整流1R一般的雙極型材料1S1R阻變

7、材料及機(jī)理VOx、NbQx、TiOx、TaOx等；正負(fù)偏壓下電流對稱， 交叉陣列中常用的1/2VRead電壓讀法Co-Occurrence of Threshold Switching and Memory Switching in Pt/NbCVPt Cells for Crosspoint Memory ApplicationsJ Electron Device Letters, IEEE. 2012，33(2): 236-238 Selector供選材料RRAM材料和機(jī)理不對稱的情況（Si加氧化物） Epitaxial Si Punch-Through based Selector fo

8、r Bipolar RRAM自整流的情況，Al/ZnO/Si，也可單獨(dú)使用新型阻變存儲器材料及其電阻轉(zhuǎn)變機(jī)理研究_陳超導(dǎo)電類型：蒲爾-弗朗克效應(yīng)，反應(yīng)時(shí)間慢！閾值轉(zhuǎn)變特性（TS）材料一種非線性電阻導(dǎo)電類型：未知，反應(yīng)時(shí)間未知制作在硅外延層上，估計(jì)不適合crossbar結(jié)構(gòu)猜測與展望猜測與展望 根據(jù)國際上其他研究機(jī)構(gòu)和intel公司2012年以來發(fā)表的文章，阻變材料集中在HfOx上，尤其是2015年文獻(xiàn)特別集中；HfO2用作CMOS柵極絕緣材料已久，工藝成熟。阻變材料的選擇初步判斷初步判斷INTELINTEL采用了采用了HfOxHfOx“Real-Time Study of Switching

9、Kinetics in Integrated 1T/ HfOx 1R RRAM: Intrinsic Tunability of Set/Reset Voltage and Trade-off with Switching Time”， 1SEMATECH Austin, TX 78741 and Albany, NY 12203, USA; 2Intel Corporation, 2200 Mission College Blvd., Santa Clara, CA95054. 這篇intel 參與的文章，發(fā)表于2012年，是目前對一種阻變材料研究最為全面的文章，測試圖見附圖附圖A A。國內(nèi)

10、一個(gè)引人注意的材料是Ta2Ox，清華和北大均有多個(gè)單位研究，其中最新且比較全面的見文章： Kun Wang, Huaqiang Wu *, Xinyuan Wang, Xinyi Li, He Qian,” Study of doping effects on Ta20s-xl TaOy based bilayer RRAM devices”, Institute of Microelectronics, Tsinghua University.測試圖見附圖附圖B B。猜測與展望猜測與展望selector的選擇字線和位線形成閉合回路，且存儲字線和位線形成閉合回路，且存儲cell規(guī)模很大，是不可

11、能的。不管什么規(guī)模很大，是不可能的。不管什么selector！非對稱與此類似非對稱與此類似讀取過程壓差較小，每個(gè)泄漏點(diǎn)電流小讀取過程壓差較小，每個(gè)泄漏點(diǎn)電流小寫入過程壓差較大，每個(gè)泄漏點(diǎn)電流大寫入過程壓差較大，每個(gè)泄漏點(diǎn)電流大非對稱時(shí)，泄漏逐漸由非對稱時(shí)，泄漏逐漸由一維轉(zhuǎn)為二維一維轉(zhuǎn)為二維Selector的的I/V特性需要特性需要與電阻讀寫與電阻讀寫I/V特性匹特性匹配，閾值要遠(yuǎn)大于配，閾值要遠(yuǎn)大于Vwr一維泄漏一維泄漏二維泄漏二維泄漏讀取過程壓差較小，每個(gè)泄漏點(diǎn)電流小讀取過程壓差較小，每個(gè)泄漏點(diǎn)電流小寫入過程壓差較大，每個(gè)泄漏點(diǎn)電流大寫入過程壓差較大，每個(gè)泄漏點(diǎn)電流大Selector的的I/

12、V特性需要特性需要與電阻讀寫與電阻讀寫I/V特性匹特性匹配配猜測：小猜測：小Cell+T（晶體管），合適的（晶體管），合適的selector配合，即配合，即1TnR（1S1R）。）。 Crossbar結(jié)構(gòu)需要尚需進(jìn)一步探索。猜測與展望猜測與展望selector的選擇Kai-Shin Li1 et al. , “Study of Sub-5 nm RRAM, Tunneling Selector and Selector Less Device”, 1NDL /NARLabs, Hsinchu, Taiwan, 2015 TiO2 selection device (1 5 nm2) and H

13、fO2 based RRAM device (1 3 nm2), 疊層制造過程疊層制造過程IV curves tunneling selection devices with 60, 90, 120 and 150 sec oxidation time這個(gè)來自臺灣最新文章，給出了一個(gè)selector的指標(biāo)，應(yīng)該可信Selector 底電極是ALD TiN，上電極是/PVD TiN ，結(jié)構(gòu)對稱復(fù)旦大學(xué)將這種對稱結(jié)構(gòu)取名2D1RYinyin Lin et al., “3D Vertical RRAM Architecture and Operation Algorithms with Effect

14、ive IR-Drop Suppressing and Anti-Disturbance”, ASIC and System State Key Laboratory, Fudan University,2015, supported by Samsung GRO project猜測與展望猜測與展望selectorselector的選擇的選擇V. S. Senthil Srinivasan1, B. Das2, V. Sangwan2, C. Pinto G6mez1, M. Oehmel, U. Ganguly2 and J. Schulze1, “Low Temperature Epita

15、xial Germanium P+IN+IP+ Selector for RRAM”, Device Research Conference (DRC), 2015 73rd Annual, 2015.FAST selector. (a) Transmission electron microscopy image of a fabricated FAST selector. (b) DC IV characteristics of FAST selectors. The threshold voltage of a selector can be tuned by controlling t

16、he thickness of an SLT medium. Device size: 100 nm 100 nm. All electrical measurement was done in single sweeps (e.g., 0 V 2 V and 0 V 2 V) with current compliance of 100 A.Sung Hyun Jo et al., “Cross-Point Resistive RAM Based on Field-Assisted Superlinear Threshold Selector”, IEEE TRANSACTIONS ON E

17、LECTRON DEVICES,2015本文在架構(gòu)的意見：From an architectural point of view, RRAM integration can be classified as either 1T1R or 1TnR (1S1R)1.現(xiàn)有材料體系應(yīng)該還有挖掘空間；2.Selector能否不局限于電？3.能否引入量子器件解決問題？展望猜測與展望猜測與展望1.根據(jù)文獻(xiàn)，估計(jì)RRAM采用的架構(gòu)是1TnR或者1 T n(1S1R)，可以和NAND相比較；2.根據(jù)文獻(xiàn)，估計(jì)selector采用的是氧化物實(shí)現(xiàn)，一定電壓(較大)下導(dǎo)通，滿足雙極型材料的讀寫要求。WLWL與與BL

18、BL形成回路方式（基于形成回路方式（基于intelintel發(fā)布產(chǎn)品圖片表現(xiàn)）發(fā)布產(chǎn)品圖片表現(xiàn)）WLWL與與BLBL不形成回路方式（也許不形成回路方式（也許intelintel故意誤導(dǎo)）故意誤導(dǎo)）不需要特別的選通器（selector），1T1R結(jié)構(gòu)；也許可以借鑒NAND的層疊方案；最新的架構(gòu)方面分析文章：最新的架構(gòu)方面分析文章：Manan Suri et al., “Exploiting Intrinsic Variability of Filamentary Resistive Memory for Extreme Learning Machine Architectures”, IEEE

19、Transactions on Nanotechnology,2015.1. RRAM的特點(diǎn)是高密度、高度、非易失、低功耗。采用RRAM，未來電子系統(tǒng)將具有體積更小、功耗更低、性能更強(qiáng)大。2. 會改變處理器設(shè)計(jì)和生產(chǎn)的格局。小結(jié)(意義)參考文獻(xiàn)（因篇幅所限，只列2015年HfOx方面的文獻(xiàn)名）1.Real-Time Study of Switching Kinetics in Integrated 1T/ HfOx 1R RRAM: Intrinsic Tunability of Set/Reset Voltage and Trade-off with Switching Time,20122

20、.Investigation of Single-Bit and Multiple-Bit Upsets in Oxide RRAM-Based 1T1R and Crossbar Memory Arrays3.Reliability of low current filamentary HfO2 RRAM discussed in the framework of the hourglass SET/RESET model 4.Relationship among current fluctuations during forming, cell-to-cell variability an

21、d reliability in RRAM arrays5.Study of Multilevel High-Resistance States in HfOx-Based Resistive Switching Random Access Memory by Impedance Spectroscopy6.Understanding the influence of Ea and band-offset toward the conductance modulation in Ah03 and Hf02 synaptic RRAM7.Ultra-Low Power Ni/HfO2/TiOx/

22、TiN Resistive Random Access Memory With Sub-30-nA Reset Current8.Study of Sub-5 nm RRAM, Tunneling Selector and Selector Less Device9.Voltage-Controlled Cycling Endurance of HfOx-Based Resistive-Switching Memory10.A Novel Program-Verify Algorithm for Multi-Bit Operation in HfO2 RRAM11.Improving the

23、Resistive Switching Reliability via Controlling the Resistance States of RRAM 12.Validation and Extension of Local Temperature Evaluation of Conductive Filaments in RRAM Devices13.Mechanism of Nonlinear Switching in HfO2-Based Crossbar RRAM With Inserting Large Bandgap Tunneling Barrier Layer14.RRAM

24、-based 7T1R Nonvolatile SRAM with 2x Reduction in Store Energy and 94x Reduction in Restore Energy for Frequent-Off Instant-On Applications15.Quantitative endurance failure model for filamentary RRAM16.Thermometry of Filamentary RRAM Devices17.IMPROVEMENT ON SWITCHING UNIFORMITY OF HFOx-BASED RRAM D

25、EVICE FABRICATED BY CMP18.A Novel Approach to Identify the Carrier Transport Path and Its Correlation to the Current Variation in RRAM19.Multi-state resistance switching and variability analysis of HfOx Based RRAM for ultra-high density memory applications20.Impact of Intercell and Intracell Variability on Forming and Switching Parameters in RRAM Arrays21.Investigation of the Resistive Switching Behavior in Ni/HfO2-based RRAM Devices22.Monte Carlo Model of Res