Embedded memory,which heavily relies on the manufacturing process,has been widely adopted in various industrial applications.As the field of embedded memory continues to evolve,innovative strategies are emerging to en...Embedded memory,which heavily relies on the manufacturing process,has been widely adopted in various industrial applications.As the field of embedded memory continues to evolve,innovative strategies are emerging to enhance performance.Among them,resistive random access memory(RRAM)has gained significant attention due to its numerousadvantages over traditional memory devices,including high speed(<1 ns),high density(4 F^(2)·n^(-1)),high scalability(~nm),and low power consumption(~pJ).This review focuses on the recent progress of embedded RRAM in industrial manufacturing and its potentialapplications.It provides a brief introduction to the concepts and advantages of RRAM,discusses the key factors that impact its industrial manufacturing,and presents the commercial progress driven by cutting-edge nanotechnology,which has been pursued by manysemiconductor giants.Additionally,it highlights the adoption of embedded RRAM in emerging applications within the realm of the Internet of Things and future intelligent computing,with a particular emphasis on its role in neuromorphic computing.Finally,the review discusses thecurrent challenges and provides insights into the prospects of embedded RRAM in the era of big data and artificial intelligence.展开更多
Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,...Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,introducing electrical variation among different RRAM devices.In this work,an optical physical verification methodology for the RRAM array is developed,and the effects of different layout parameters on important electrical characteristics are systematically investigated.The results indicate that the RRAM devices can be categorized into three clusters according to their locations and lithography environments.The read resistance is more sensitive to the locations in the array(~30%)than SET/RESET voltage(<10%).The increase in the RRAM device length and the application of the optical proximity correction technique can help to reduce the variation to less than 10%,whereas it reduces RRAM read resistance by 4×,resulting in a higher power and area consumption.As such,we provide design guidelines to minimize the electrical variation of RRAM arrays due to the lithography process.展开更多
Using computer-aided design three-dimensional （3D） simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi...Using computer-aided design three-dimensional （3D） simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings. It cannot exhibit the recovery effect. It is also indicated that the upset linear energy transfer （LET） threshold is kept constant while the recovery LET threshold increases as the spacing increases. Additionally, the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect, thus strengthening the recovery ability.展开更多
An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell ...An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.展开更多
The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,...The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,computing devices use the von Neumann architecture with separate computing and memory units,which exposes the shortcomings of“memory bottleneck”.Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck.Phase-change random access memory(PCRAM)is called one of the best solutions for next generation non-volatile memory.Due to its high speed,good data retention,high density,low power consumption,PCRAM has the broad commercial prospects in the in-memory computing application.In this review,the research progress of phase-change materials and device structures for PCRAM,as well as the most critical performances for a universal memory,such as speed,capacity,and power consumption,are reviewed.By comparing the advantages and disadvantages of phase-change optical disk and PCRAM,a new concept of optoelectronic hybrid storage based on phase-change material is proposed.Furthermore,its feasibility to replace existing memory technologies as a universal memory is also discussed as well.展开更多
This paper investigated phase change Si1Sb2Te3 material for application of chalcogenide random access memory. Current-voltage performance was conducted to determine threshold current of phase change from amorphous pha...This paper investigated phase change Si1Sb2Te3 material for application of chalcogenide random access memory. Current-voltage performance was conducted to determine threshold current of phase change from amorphous phase to polycrystalline phase. The film holds a threshold current about 0.155 mA, which is smaller than the value 0.31 mA of Ge2Sb2Te5 film. Amorphous Si1Sb2Te3 changes to face-centred-cubic structure at ~ 180℃ and changes to hexagonal structure at ~ 270℃. Annealing temperature dependent electric resistivity of Si1Sb2Te3 film was studied by four-point probe method. Data retention of the films was characterized as well.展开更多
Recent progresses in magnetic tunnel junctions with perpendicular magnetic anisotropy （PMA） are reviewed and summarized. At first, the concept and source of perpendicular magnetic anisotropy （PMA） are introduced. ...Recent progresses in magnetic tunnel junctions with perpendicular magnetic anisotropy （PMA） are reviewed and summarized. At first, the concept and source of perpendicular magnetic anisotropy （PMA） are introduced. Next, a historical overview of PMA materials as magnetic electrodes, such as the RE-TM alloys TbFeCo and GdFeCo, novel tetragonal manganese alloys Mn-Ga, L10-ordered （Co, Fe）/Pt alloy, multilayer film [Co, Fe, CoFe/Pt, Pd, Ni, AU]N, and ultra-thin magnetic metal/oxidized barrier is offered. The other part of the article focuses on the optimization and fabrication of CoFeB/MgO/CoFeB p-MTJs, which is thought to have high potential to meet the main demands for non-volatile magnetic random access memory.展开更多
In this letter,the Ta/HfO/BN/TiN resistive switching devices are fabricated and they exhibit low power consumption and high uniformity each.The reset current is reduced for the HfO/BN bilayer device compared with that...In this letter,the Ta/HfO/BN/TiN resistive switching devices are fabricated and they exhibit low power consumption and high uniformity each.The reset current is reduced for the HfO/BN bilayer device compared with that for the Ta/HfO/TiN structure.Furthermore,the reset current decreases with increasing BN thickness.The HfOlayer is a dominating switching layer,while the low-permittivity and high-resistivity BN layer acts as a barrier of electrons injection into TiN electrode.The current conduction mechanism of low resistance state in the HfO/BN bilayer device is space-chargelimited current(SCLC),while it is Ohmic conduction in the HfOdevice.展开更多
As an industry accepted storage scheme, hafnium oxide（HfO_x） based resistive random access memory（RRAM）should further improve its thermal stability and data retention for practical applications. We therefore fabri...As an industry accepted storage scheme, hafnium oxide（HfO_x） based resistive random access memory（RRAM）should further improve its thermal stability and data retention for practical applications. We therefore fabricated RRAMs with HfO_x/ZnO double-layer as the storage medium to study their thermal stability as well as data retention. The HfO_x/ZnO double-layer is capable of reversible bipolar switching under ultralow switching current（〈 3 μA） with a Schottky emission dominant conduction for the high resistance state and a Poole–Frenkel emission governed conduction for the low resistance state. Compared with a drastically increased switching current at 120℃ for the single HfO_x layer RRAM, the HfO_x/ZnO double-layer exhibits excellent thermal stability and maintains neglectful fluctuations in switching current at high temperatures（up to 180℃）, which might be attributed to the increased Schottky barrier height to suppress current at high temperatures. Additionally, the HfO_x/ZnO double-layer exhibits 10-year data retention @85℃ that is helpful for the practical applications in RRAMs.展开更多
Synergistic effects of the total ionizing dose （TID） on the single event upset （SEU） sensitivity in static random access memories （SRAMs） were studied by using protons. The total dose was cumulated with high flu...Synergistic effects of the total ionizing dose （TID） on the single event upset （SEU） sensitivity in static random access memories （SRAMs） were studied by using protons. The total dose was cumulated with high flux protons during the TID exposure, and the SEU cross section was tested with low flux protons at several cumulated dose steps. Because of the radiation-induced off-state leakage current increase of the CMOS transistors, the noise margin became asymmetric and the memory imprint effect was observed.展开更多
A novel slow-down set waveform is proposed to improve the set performance and a 1 kb phase change random access memory chip fabricated with a 13nm CMOS technology is implemented to investigate the set performance by d...A novel slow-down set waveform is proposed to improve the set performance and a 1 kb phase change random access memory chip fabricated with a 13nm CMOS technology is implemented to investigate the set performance by different set programming strategies based on this new set pulse. The amplitude difference （I1 - I2） of the set pulse is proved to be a crucial parameter for set programming. We observe and analyze the cell characteristics with different I1 - I2 by means of thermal simulations and high-resolution transmission electron microscopy, which reveal that an incomplete set programming will occur when the proposed slow-down pulse is set with an improperly high I1 - I2. This will lead to an amorphous residue in the active region. We also discuss the programming method to avoid the set performance degradations.展开更多
The impact of ionizing radiation effect on single event upset（SEU） sensitivity of ferroelectric random access memory（FRAM） is studied in this work. The test specimens were firstly subjected to ^60Co γ-ray and the...The impact of ionizing radiation effect on single event upset（SEU） sensitivity of ferroelectric random access memory（FRAM） is studied in this work. The test specimens were firstly subjected to ^60Co γ-ray and then the SEU evaluation was conducted using ^209Bi ions. As a result of TID-induced fatigue-like and imprint-like phenomena of the ferroelectric material, the SEU cross sections of the post-irradiated devices shift substantially. Different trends of SEU cross section with elevated dose were also found, depending on whether the same or complementary test pattern was employed during the TID exposure and the SEU measurement.展开更多
We investigate the effect of the formation process under pulse and dc modes on the performance of one transistor and one resistor （1 T1R） resistance random access memory （RRAM） device. All the devices are operated...We investigate the effect of the formation process under pulse and dc modes on the performance of one transistor and one resistor （1 T1R） resistance random access memory （RRAM） device. All the devices are operated under the same test conditions, except for the initial formation process with different modes. Based on the statistical results, the high resistance state （FIRS） under the dc forming mode shows a lower value with better distribution compared with that under the pulse mode. One of the possible reasons for such a phenomenon originates from different properties of conductive filament （CF） formed in the resistive switching layer under two different modes. For the dc forming mode, the formed filament is thought to be continuous, which is hard to be ruptured, resulting in a lower HRS. However, in the case of pulse forming, the filament is discontinuous where the transport mechanism is governed by hopping. The low resistance state （LRS） can be easily changed by removing a few trapping states from the conducting path. Hence, a higher FIRS is thus observed. However, the HRS resistance is highly dependent on the length of the gap opened. A slight variation of the gap length will cause wide dispersion of resistance.展开更多
Amorphous NbS_(2)was proposed as the resistive switching(RS)layer for conductive-bridge random access memory(CBRAM)for the first time,with Cu and Au as the top and bottom electrodes,respectively.NbS_(2)films were prep...Amorphous NbS_(2)was proposed as the resistive switching(RS)layer for conductive-bridge random access memory(CBRAM)for the first time,with Cu and Au as the top and bottom electrodes,respectively.NbS_(2)films were prepared at room temperature,which exhibited an amorphous structure and did not crystalize even annealed at 500°C,showing good thermal stability.The amorphous NbS_(2)CBRAM devices present stable bipolar non-volatile RS characteristics.Repetitive RS behavior is demonstrated in amorphous NbS_(2)CBRAMs.The operating voltage during all RS cycles is less than 1 V,demonstrating that the NbS_(2)CBRAM is a low-operation voltage memory device.The distribution of the high and low resistive state resistance is relatively concentrated,and the on-off ratio has been kept above 100,offering a sufficient data read/write window.The formation and fracture of the Cu metal conductive filament is considered to be the RS mechanism by analyzing the dependence of current and voltage in logarithmic coordinates.Our study demonstrated that amorphous NbS_(2)is a promising material for lowoperation voltage CBRAM.展开更多
Magnetoresistive random access memory(MRAM)is a promising non-volatile memory technology that can be utilized as an energy and space-efficient storage and computing solution,particularly in cache functions within circ...Magnetoresistive random access memory(MRAM)is a promising non-volatile memory technology that can be utilized as an energy and space-efficient storage and computing solution,particularly in cache functions within circuits.Although MRAM has achieved mass production,its manufacturing process still remains challenging,resulting in only a few semiconductor companies dominating its production.In this review,we delve into the materials,processes,and devices used in MRAM,focusing on both the widely adopted spin transfer torque MRAM and the next-generation spin-orbit torque MRAM.We provide an overview of their operational mechanisms and manufacturing technologies.Furthermore,we outline the major hurdles faced in MRAM manufacturing and propose potential solutions in detail.Then,the applications of MRAM in artificial intelligent hardware are introduced.Finally,we present an outlook on the future development and applications of MRAM.展开更多
As a typical representative of nanomaterials,carbon nanomaterials have attracted widespread attention in the construction of electronic devices owing to their unique physical and chemical properties,multi-dimensionali...As a typical representative of nanomaterials,carbon nanomaterials have attracted widespread attention in the construction of electronic devices owing to their unique physical and chemical properties,multi-dimensionality,multi-hybridization methods,and excellent electronic properties.Especially in the recent years,memristors based on carbon nanomaterials have flourished in the field of building non-volatile memory devices and neuromorphic applications.In the current work,the preparation methods and structural characteristics of carbon nanomaterials of different dimensions were systematically reviewed.Afterwards,in depth discussion on the structural characteristics and working mechanism of memristors based on carbon nanomaterials of different dimensions was conducted.Finally,the potential applications of carbon-based memristors in logic operations,neural network construction,artificial vision systems,artificial tactile systems,and multimodal perception systems were also introduced.It is believed that this paper will provide guidance for the future development of high-quality information storage,high-performance neuromorphic applications,and highsensitivity bionic sensing based on carbon-based memristors.展开更多
In this paper, different electrical measurement and operation methods of resistive random access memory （RRAM） have been summarized, including voltage sweeping mode （VSM）, current sweeping mode （CSM）, co lstant ...In this paper, different electrical measurement and operation methods of resistive random access memory （RRAM） have been summarized, including voltage sweeping mode （VSM）, current sweeping mode （CSM）, co lstant current stress （CCS）, constant voltage stress （CVS）, rectangular pulse mode （RPM）, and triangle pulse mode （TPM）. Meanwhile, the effects of these meas- urement methods on the forming, set, reset and read operation as well as endurance performance have been compared. Finally, their respective controllability of various resistive switching parameters have been summar zeal and analyzed.展开更多
Metal phthalocyanine is considered one of the most promising candidates for the design and fabrication of flexible resistive random access memory(RRAM)devices due to its intrinsic flexibility and excellent functionali...Metal phthalocyanine is considered one of the most promising candidates for the design and fabrication of flexible resistive random access memory(RRAM)devices due to its intrinsic flexibility and excellent functionality.However,performance degradation and the lack of multi-level capability,which can directly expand the storage capacity in one memory cell without sacrificing additional layout area,are the primary obstacles to the use of metal phthalocyanine RRAMs in information storage.Here,a flexible RRAM with pristine nickel phthalocyanine(Ni Pc)as the resistive layer is reported for multi-level data storage.Due to its high trap-concentration,the charge transport behavior of the device agrees well with classical space charge limited conduction controlled by traps,leading to an excellent performance,including a high on-off current ratio of 10^(7),a long-term retention of 10^(6)s,a reproducible endurance over6000 cycles,long-term flexibility at a bending strain of 0.6%,a write speed of 50 ns under sequential bias pulses and the capability of multi-level data storage with reliable retention and uniformity.展开更多
The on-chip memory performance of embedded systems directly affects the system designers＇ decision about how to allocate expensive silicon area. A novel memory architecture, flexible sequential and random access memo...The on-chip memory performance of embedded systems directly affects the system designers＇ decision about how to allocate expensive silicon area. A novel memory architecture, flexible sequential and random access memory （FSRAM）, is investigated for embedded systems. To realize sequential accesses, small “links”are added to each row in the RAM array to point to the next row to be prefetched. The potential cache pollution is ameliorated by a small sequential access buyer （SAB）. To evaluate the architecture-level performance of FSRAM, we ran the Mediabench benchmark programs on a modified version of the SimpleScalar simulator. Our results show that the FSRAM improves the performance of a baseline processor with a 16KB data cache up to 55%, with an average of 9%; furthermore, the FSRAM reduces 53.1% of the data cache miss count on average due to its prefetching effect. We also designed RTL and SPICE models of the FSRAM, which show that the FSRAM significantly improves memory access time, while reducing power consumption, with negligible area overhead.展开更多
Lead halide perovskites have attracted increasing attention in photovoltaic devices,light-emitting diodes,photodetectors,and other fields due to their excellent properties.Besides optoelectronic devices,growing number...Lead halide perovskites have attracted increasing attention in photovoltaic devices,light-emitting diodes,photodetectors,and other fields due to their excellent properties.Besides optoelectronic devices,growing numbers of studies have focused on the perovskite-based electrical devices in the past few years,such as transistors and resistive random access memories(RRAMs).Here,this article summarizes the recent progress the researchers have made of RRAM devices.Primarily,the working mechanism and the key parameters of RRAM are introduced.Generally,the working principles,including the conductive filament model(containing the types of the model of the metal cationsinduced filament and the model of the ions migration in bulk),the interface effect,and the electronic effect are the origins of the RRAM behaviors,and hence,various factors that affect the device performance are explored.Then,RRAMs based on organolead halide perovskite and all-inorganic perovskite are discussed in terms of different structures,different compositions,and different fabrication methods.Finally,a brief conclusion and a broad outlook are given on the progress and challenges in the field of perovskite-based RRAMs.展开更多
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2021B0909060002)National Natural Science Foundation of China(Grant Nos.62204219,62204140)+1 种基金Major Program of Natural Science Foundation of Zhejiang Province(Grant No.LDT23F0401)Thanks to Professor Zhang Yishu from Zhejiang University,Professor Gao Xu from Soochow University,and Professor Zhong Shuai from Guangdong Institute of Intelligence Science and Technology for their support。
文摘Embedded memory,which heavily relies on the manufacturing process,has been widely adopted in various industrial applications.As the field of embedded memory continues to evolve,innovative strategies are emerging to enhance performance.Among them,resistive random access memory(RRAM)has gained significant attention due to its numerousadvantages over traditional memory devices,including high speed(<1 ns),high density(4 F^(2)·n^(-1)),high scalability(~nm),and low power consumption(~pJ).This review focuses on the recent progress of embedded RRAM in industrial manufacturing and its potentialapplications.It provides a brief introduction to the concepts and advantages of RRAM,discusses the key factors that impact its industrial manufacturing,and presents the commercial progress driven by cutting-edge nanotechnology,which has been pursued by manysemiconductor giants.Additionally,it highlights the adoption of embedded RRAM in emerging applications within the realm of the Internet of Things and future intelligent computing,with a particular emphasis on its role in neuromorphic computing.Finally,the review discusses thecurrent challenges and provides insights into the prospects of embedded RRAM in the era of big data and artificial intelligence.
基金supported in part by the Open Fund of State Key Laboratory of Integrated Chips and Systems,Fudan Universityin part by the National Science Foundation of China under Grant No.62304133 and No.62350610271.
文摘Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,introducing electrical variation among different RRAM devices.In this work,an optical physical verification methodology for the RRAM array is developed,and the effects of different layout parameters on important electrical characteristics are systematically investigated.The results indicate that the RRAM devices can be categorized into three clusters according to their locations and lithography environments.The read resistance is more sensitive to the locations in the array(~30%)than SET/RESET voltage(<10%).The increase in the RRAM device length and the application of the optical proximity correction technique can help to reduce the variation to less than 10%,whereas it reduces RRAM read resistance by 4×,resulting in a higher power and area consumption.As such,we provide design guidelines to minimize the electrical variation of RRAM arrays due to the lithography process.
基金supported by the State Key Program of the National Natural Science Foundation of China (Grant No.60836004)the National Natural Science Foundation of China (Grant Nos.61076025 and 61006070)
文摘Using computer-aided design three-dimensional （3D） simulation technology, the recovery mechanism of single event upset and the effects of spacing and hit angle on the recovery are studied. It is found that the multi-node charge collection plays a key role in recovery and shielding the charge sharing by adding guard rings. It cannot exhibit the recovery effect. It is also indicated that the upset linear energy transfer （LET） threshold is kept constant while the recovery LET threshold increases as the spacing increases. Additionally, the effect of incident angle on recovery is analysed and it is shown that a larger angle can bring about a stronger charge sharing effect, thus strengthening the recovery ability.
基金Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA09020402the National Integrate Circuit Research Program of China under Grant No 2009ZX02023-003+1 种基金the National Natural Science Foundation of China under Grant Nos 61261160500,61376006,61401444 and 61504157the Science and Technology Council of Shanghai under Grant Nos 14DZ2294900,15DZ2270900 and 14ZR1447500
文摘An optimized device structure for reducing the RESET current of phase-change random access memory （PCRAM） with blade-type like （BTL） phase change layer is proposed. The electrical thermal analysis of the BTL cell and the blade heater contactor structure by three-dimensional finite element modeling are compared with each other during RESET operation. The simulation results show that the programming region of the phase change layer in the BTL cell is much smaller, and thermal electrical distributions of the BTL cell are more concentrated on the TiN/GST interface. The results indicate that the BTL cell has the superiorities of increasing the heating efficiency, decreasing the power consumption and reducing the RESET current from 0.67mA to 0.32mA. Therefore, the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.
基金the National Natural Science Foundation of China(Grant Nos.21773291,61904118,and 22002102)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190935 and BK20190947)+3 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant Nos.19KJA210005,19KJB510012,19KJB120005,and 19KJB430034)the Fund from the Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices(Grant No.SZS201812)the Science Fund from the Jiangsu Key Laboratory for Environment Functional Materialsthe State Key Laboratory of Transducer Technology,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences.
文摘The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,computing devices use the von Neumann architecture with separate computing and memory units,which exposes the shortcomings of“memory bottleneck”.Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck.Phase-change random access memory(PCRAM)is called one of the best solutions for next generation non-volatile memory.Due to its high speed,good data retention,high density,low power consumption,PCRAM has the broad commercial prospects in the in-memory computing application.In this review,the research progress of phase-change materials and device structures for PCRAM,as well as the most critical performances for a universal memory,such as speed,capacity,and power consumption,are reviewed.By comparing the advantages and disadvantages of phase-change optical disk and PCRAM,a new concept of optoelectronic hybrid storage based on phase-change material is proposed.Furthermore,its feasibility to replace existing memory technologies as a universal memory is also discussed as well.
文摘This paper investigated phase change Si1Sb2Te3 material for application of chalcogenide random access memory. Current-voltage performance was conducted to determine threshold current of phase change from amorphous phase to polycrystalline phase. The film holds a threshold current about 0.155 mA, which is smaller than the value 0.31 mA of Ge2Sb2Te5 film. Amorphous Si1Sb2Te3 changes to face-centred-cubic structure at ~ 180℃ and changes to hexagonal structure at ~ 270℃. Annealing temperature dependent electric resistivity of Si1Sb2Te3 film was studied by four-point probe method. Data retention of the films was characterized as well.
基金supported by the State Key Project of Fundamental Research of Ministry of Science and Technology,China(Grant No.2010CB934400)the National Natural Science Foundation of China(Grant Nos.51229101 and 11374351)
文摘Recent progresses in magnetic tunnel junctions with perpendicular magnetic anisotropy （PMA） are reviewed and summarized. At first, the concept and source of perpendicular magnetic anisotropy （PMA） are introduced. Next, a historical overview of PMA materials as magnetic electrodes, such as the RE-TM alloys TbFeCo and GdFeCo, novel tetragonal manganese alloys Mn-Ga, L10-ordered （Co, Fe）/Pt alloy, multilayer film [Co, Fe, CoFe/Pt, Pd, Ni, AU]N, and ultra-thin magnetic metal/oxidized barrier is offered. The other part of the article focuses on the optimization and fabrication of CoFeB/MgO/CoFeB p-MTJs, which is thought to have high potential to meet the main demands for non-volatile magnetic random access memory.
基金supported by the National Natural Science Foundation of China(Grant Nos.61274113,11204212,61404091,51502203,and 51502204)the Tianjin Natural Science Foundation,China(Grant Nos.14JCZDJC31500 and 14JCQNJC00800)the Tianjin Science and Technology Developmental Funds of Universities and Colleges,China(Grant No.20130701)
文摘In this letter,the Ta/HfO/BN/TiN resistive switching devices are fabricated and they exhibit low power consumption and high uniformity each.The reset current is reduced for the HfO/BN bilayer device compared with that for the Ta/HfO/TiN structure.Furthermore,the reset current decreases with increasing BN thickness.The HfOlayer is a dominating switching layer,while the low-permittivity and high-resistivity BN layer acts as a barrier of electrons injection into TiN electrode.The current conduction mechanism of low resistance state in the HfO/BN bilayer device is space-chargelimited current(SCLC),while it is Ohmic conduction in the HfOdevice.
基金supported by the National Natural Science Foundation of China(Grant Nos.61006003 and 61674038)the Natural Science Foundation of Fujian Province,China(Grant Nos.2015J01249 and 2010J05134)+1 种基金the Science Foundation of Fujian Education Department of China(Grant No.JAT160073)the Science Foundation of Fujian Provincial Economic and Information Technology Commission of China(Grant No.83016006)
文摘As an industry accepted storage scheme, hafnium oxide（HfO_x） based resistive random access memory（RRAM）should further improve its thermal stability and data retention for practical applications. We therefore fabricated RRAMs with HfO_x/ZnO double-layer as the storage medium to study their thermal stability as well as data retention. The HfO_x/ZnO double-layer is capable of reversible bipolar switching under ultralow switching current（〈 3 μA） with a Schottky emission dominant conduction for the high resistance state and a Poole–Frenkel emission governed conduction for the low resistance state. Compared with a drastically increased switching current at 120℃ for the single HfO_x layer RRAM, the HfO_x/ZnO double-layer exhibits excellent thermal stability and maintains neglectful fluctuations in switching current at high temperatures（up to 180℃）, which might be attributed to the increased Schottky barrier height to suppress current at high temperatures. Additionally, the HfO_x/ZnO double-layer exhibits 10-year data retention @85℃ that is helpful for the practical applications in RRAMs.
基金supported by the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices,China(Grant No.KFJJ201306)
文摘Synergistic effects of the total ionizing dose （TID） on the single event upset （SEU） sensitivity in static random access memories （SRAMs） were studied by using protons. The total dose was cumulated with high flux protons during the TID exposure, and the SEU cross section was tested with low flux protons at several cumulated dose steps. Because of the radiation-induced off-state leakage current increase of the CMOS transistors, the noise margin became asymmetric and the memory imprint effect was observed.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDA09020402the National Key Basic Research Program of China under Grant Nos 2013CBA01900,2010CB934300,2011CBA00607,and 2011CB932804+2 种基金the National Integrate Circuit Research Program of China under Grant No 2009ZX02023-003the National Natural Science Foundation of China under Grant Nos 61176122,61106001,61261160500,and 61376006the Science and Technology Council of Shanghai under Grant Nos 12nm0503701,13DZ2295700,12QA1403900,and 13ZR1447200
文摘A novel slow-down set waveform is proposed to improve the set performance and a 1 kb phase change random access memory chip fabricated with a 13nm CMOS technology is implemented to investigate the set performance by different set programming strategies based on this new set pulse. The amplitude difference （I1 - I2） of the set pulse is proved to be a crucial parameter for set programming. We observe and analyze the cell characteristics with different I1 - I2 by means of thermal simulations and high-resolution transmission electron microscopy, which reveal that an incomplete set programming will occur when the proposed slow-down pulse is set with an improperly high I1 - I2. This will lead to an amorphous residue in the active region. We also discuss the programming method to avoid the set performance degradations.
文摘The impact of ionizing radiation effect on single event upset（SEU） sensitivity of ferroelectric random access memory（FRAM） is studied in this work. The test specimens were firstly subjected to ^60Co γ-ray and then the SEU evaluation was conducted using ^209Bi ions. As a result of TID-induced fatigue-like and imprint-like phenomena of the ferroelectric material, the SEU cross sections of the post-irradiated devices shift substantially. Different trends of SEU cross section with elevated dose were also found, depending on whether the same or complementary test pattern was employed during the TID exposure and the SEU measurement.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00602,2010CB934200,2011CB921804,2011CB707600,2011AA010401,and 2011AA010402the National Natural Science Foundation of China under Grant Nos61322408,61334007,61376112,61221004,61274091,61106119,61106082,and 61006011
文摘We investigate the effect of the formation process under pulse and dc modes on the performance of one transistor and one resistor （1 T1R） resistance random access memory （RRAM） device. All the devices are operated under the same test conditions, except for the initial formation process with different modes. Based on the statistical results, the high resistance state （FIRS） under the dc forming mode shows a lower value with better distribution compared with that under the pulse mode. One of the possible reasons for such a phenomenon originates from different properties of conductive filament （CF） formed in the resistive switching layer under two different modes. For the dc forming mode, the formed filament is thought to be continuous, which is hard to be ruptured, resulting in a lower HRS. However, in the case of pulse forming, the filament is discontinuous where the transport mechanism is governed by hopping. The low resistance state （LRS） can be easily changed by removing a few trapping states from the conducting path. Hence, a higher FIRS is thus observed. However, the HRS resistance is highly dependent on the length of the gap opened. A slight variation of the gap length will cause wide dispersion of resistance.
基金supported by“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Nos.2021C01SA 301612 and 2023C01235).
文摘Amorphous NbS_(2)was proposed as the resistive switching(RS)layer for conductive-bridge random access memory(CBRAM)for the first time,with Cu and Au as the top and bottom electrodes,respectively.NbS_(2)films were prepared at room temperature,which exhibited an amorphous structure and did not crystalize even annealed at 500°C,showing good thermal stability.The amorphous NbS_(2)CBRAM devices present stable bipolar non-volatile RS characteristics.Repetitive RS behavior is demonstrated in amorphous NbS_(2)CBRAMs.The operating voltage during all RS cycles is less than 1 V,demonstrating that the NbS_(2)CBRAM is a low-operation voltage memory device.The distribution of the high and low resistive state resistance is relatively concentrated,and the on-off ratio has been kept above 100,offering a sufficient data read/write window.The formation and fracture of the Cu metal conductive filament is considered to be the RS mechanism by analyzing the dependence of current and voltage in logarithmic coordinates.Our study demonstrated that amorphous NbS_(2)is a promising material for lowoperation voltage CBRAM.
基金supported in part by the Youth Innovation Promotion Association of Chinese Academy of Sciences(CAS)under Grant 2020118Beijing Nova Program under Grant 20230484358Beijing Superstring Academy of Memory Technology:under Grant No.E2DF06X003。
文摘Magnetoresistive random access memory(MRAM)is a promising non-volatile memory technology that can be utilized as an energy and space-efficient storage and computing solution,particularly in cache functions within circuits.Although MRAM has achieved mass production,its manufacturing process still remains challenging,resulting in only a few semiconductor companies dominating its production.In this review,we delve into the materials,processes,and devices used in MRAM,focusing on both the widely adopted spin transfer torque MRAM and the next-generation spin-orbit torque MRAM.We provide an overview of their operational mechanisms and manufacturing technologies.Furthermore,we outline the major hurdles faced in MRAM manufacturing and propose potential solutions in detail.Then,the applications of MRAM in artificial intelligent hardware are introduced.Finally,we present an outlook on the future development and applications of MRAM.
基金supported in part by the National Key Research and Development Program of China under Grant 2021YFF0603500in part by the National Nature Science Foundation of China under Grants 62174068,62311540155,and U22A2014+1 种基金in part by the Shandong Provincial Natural Science Foundation of China under Grant(ZR2023ZD03)in part by the Jinan City University Integration Development Strategy Project under Grant(JNSX2023017).
文摘As a typical representative of nanomaterials,carbon nanomaterials have attracted widespread attention in the construction of electronic devices owing to their unique physical and chemical properties,multi-dimensionality,multi-hybridization methods,and excellent electronic properties.Especially in the recent years,memristors based on carbon nanomaterials have flourished in the field of building non-volatile memory devices and neuromorphic applications.In the current work,the preparation methods and structural characteristics of carbon nanomaterials of different dimensions were systematically reviewed.Afterwards,in depth discussion on the structural characteristics and working mechanism of memristors based on carbon nanomaterials of different dimensions was conducted.Finally,the potential applications of carbon-based memristors in logic operations,neural network construction,artificial vision systems,artificial tactile systems,and multimodal perception systems were also introduced.It is believed that this paper will provide guidance for the future development of high-quality information storage,high-performance neuromorphic applications,and highsensitivity bionic sensing based on carbon-based memristors.
基金supported by the National Natural Science Foundation of China(Grant Nos.61322408,61221004,61422407,61334007,61474136,61274091,61376112,61306117,61106119,and 61106082)National Basic Research Program of China(Grant No.2011CBA00602)National High Technology Research and Development Program of China(Grant Nos.2014AA032900,2013AA030801,2011AA010401 and 2011AA-010402)
文摘In this paper, different electrical measurement and operation methods of resistive random access memory （RRAM） have been summarized, including voltage sweeping mode （VSM）, current sweeping mode （CSM）, co lstant current stress （CCS）, constant voltage stress （CVS）, rectangular pulse mode （RPM）, and triangle pulse mode （TPM）. Meanwhile, the effects of these meas- urement methods on the forming, set, reset and read operation as well as endurance performance have been compared. Finally, their respective controllability of various resistive switching parameters have been summar zeal and analyzed.
基金supported by National Natural Science Foundation of China(Nos.61574143,61704175,51502304)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB30000000)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(No.ZDBS-LY-JSC027)Liaoning Revitalization Talents Program(No.XLYC1807109)the National Key Research and Development Program of China(2016YFB0401104)。
文摘Metal phthalocyanine is considered one of the most promising candidates for the design and fabrication of flexible resistive random access memory(RRAM)devices due to its intrinsic flexibility and excellent functionality.However,performance degradation and the lack of multi-level capability,which can directly expand the storage capacity in one memory cell without sacrificing additional layout area,are the primary obstacles to the use of metal phthalocyanine RRAMs in information storage.Here,a flexible RRAM with pristine nickel phthalocyanine(Ni Pc)as the resistive layer is reported for multi-level data storage.Due to its high trap-concentration,the charge transport behavior of the device agrees well with classical space charge limited conduction controlled by traps,leading to an excellent performance,including a high on-off current ratio of 10^(7),a long-term retention of 10^(6)s,a reproducible endurance over6000 cycles,long-term flexibility at a bending strain of 0.6%,a write speed of 50 ns under sequential bias pulses and the capability of multi-level data storage with reliable retention and uniformity.
文摘The on-chip memory performance of embedded systems directly affects the system designers＇ decision about how to allocate expensive silicon area. A novel memory architecture, flexible sequential and random access memory （FSRAM）, is investigated for embedded systems. To realize sequential accesses, small “links”are added to each row in the RAM array to point to the next row to be prefetched. The potential cache pollution is ameliorated by a small sequential access buyer （SAB）. To evaluate the architecture-level performance of FSRAM, we ran the Mediabench benchmark programs on a modified version of the SimpleScalar simulator. Our results show that the FSRAM improves the performance of a baseline processor with a 16KB data cache up to 55%, with an average of 9%; furthermore, the FSRAM reduces 53.1% of the data cache miss count on average due to its prefetching effect. We also designed RTL and SPICE models of the FSRAM, which show that the FSRAM significantly improves memory access time, while reducing power consumption, with negligible area overhead.
基金National Natural Science Foundation of China(61704131)National Key Research and Development Program of China(grant 2018YFB2202900)+1 种基金Key Research and Development Program of Shaanxi Province(grant 2020GY-310)Fundamental Research Funds for the Central Universities.
文摘Lead halide perovskites have attracted increasing attention in photovoltaic devices,light-emitting diodes,photodetectors,and other fields due to their excellent properties.Besides optoelectronic devices,growing numbers of studies have focused on the perovskite-based electrical devices in the past few years,such as transistors and resistive random access memories(RRAMs).Here,this article summarizes the recent progress the researchers have made of RRAM devices.Primarily,the working mechanism and the key parameters of RRAM are introduced.Generally,the working principles,including the conductive filament model(containing the types of the model of the metal cationsinduced filament and the model of the ions migration in bulk),the interface effect,and the electronic effect are the origins of the RRAM behaviors,and hence,various factors that affect the device performance are explored.Then,RRAMs based on organolead halide perovskite and all-inorganic perovskite are discussed in terms of different structures,different compositions,and different fabrication methods.Finally,a brief conclusion and a broad outlook are given on the progress and challenges in the field of perovskite-based RRAMs.
