从相变存储器(phase change random access memory,PCRAM)的基本结构和工作原理出发,首先介绍了PCRAM的技术优势、面临的技术挑战、常用的解决策略以及存在的相应问题;接着阐述了在微电子加工中广泛应用的关键工艺——侧墙技术,并将其在...从相变存储器(phase change random access memory,PCRAM)的基本结构和工作原理出发,首先介绍了PCRAM的技术优势、面临的技术挑战、常用的解决策略以及存在的相应问题;接着阐述了在微电子加工中广泛应用的关键工艺——侧墙技术,并将其在PCRAM中的应用成果进行了分类;然后从加热电极的制备、相变材料限制结构的制备、新相变材料的制备与表征和器件间互联等4个方面展开叙述;最后展望了该技术在相变存储领域应用发展的趋势。侧墙技术因其具备自对准的特点,制备工艺可控性好,制备精度不依赖于光刻精度,在纳米技术飞速发展的今天,侧墙技术将会在更高精度上发挥其作用。展开更多
In this letter, a phase change random access memory(PCRAM) chip based on Ti0.4Sb2Te3 alloy material was fabricated in a 40-nm 4-metal level complementary metal-oxide semiconductor(CMOS) technology. The phase change re...In this letter, a phase change random access memory(PCRAM) chip based on Ti0.4Sb2Te3 alloy material was fabricated in a 40-nm 4-metal level complementary metal-oxide semiconductor(CMOS) technology. The phase change resistor was then integrated after CMOS logic fabrication. The PCRAM was successfully embedded without changing any logic device and process, in which 1.1 V negative-channel metal-oxide semiconductor device was used as the memory cell selector. The currents and the time of SET and RESET operations were found to be 0.2 and 0.5 m A, 100 and 10 ns,respectively. The high speed performance of this chip may highlight the design advantages in many embedded applications.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
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
In order to fulfill the complex cognitive behaviors in neuromorphic systems with reduced peripheral circuits,the reliable electronic synapses mimicked by single device that achieves diverse long-term and short-term pl...In order to fulfill the complex cognitive behaviors in neuromorphic systems with reduced peripheral circuits,the reliable electronic synapses mimicked by single device that achieves diverse long-term and short-term plasticity are essential.Phase change random access memory(PCRAM)is of great potential for artificial synapses,which faces,however,difficulty to realize short-term plasticity due to the long-lasting resistance drift.This work reports the ruthenium-doped Ge_(2)Sb_(2)Te_(5)(RuGST)based PCRAM,demonstrating a series of synaptic behaviors of short-term potentiation,pair-pulse facilitation,longterm depression,and short-term plasticity in the same single device.The optimized RuGST electronic synapse with the high transformation temperature of hexagonal phase>380C,the outstanding endurance>108 cycles,the low resistance drift factor of 0.092,as well as the extremely high linearity with correlation coefficients of 0.999 and 0.976 in parts of potentiation and depression.Further investigations also go insight to mechanisms of Ru doping according to thorough microstructure characterization,revealing that Ru dopant is able to enter GST lattices thus changing and stabilizing atomic arrangement of GST.This leads to the short-term plasticity realized by RuGST PCRAM.Eventually,the proposed RuGST electronic synapses performs a high accuracy of94.1%in a task of image recognition of CIFAR-100 database using ResNet 101.This work promotes the development of PCRAM platforms for large-scale neuromorphic systems.展开更多
文摘从相变存储器(phase change random access memory,PCRAM)的基本结构和工作原理出发,首先介绍了PCRAM的技术优势、面临的技术挑战、常用的解决策略以及存在的相应问题;接着阐述了在微电子加工中广泛应用的关键工艺——侧墙技术,并将其在PCRAM中的应用成果进行了分类;然后从加热电极的制备、相变材料限制结构的制备、新相变材料的制备与表征和器件间互联等4个方面展开叙述;最后展望了该技术在相变存储领域应用发展的趋势。侧墙技术因其具备自对准的特点,制备工艺可控性好,制备精度不依赖于光刻精度,在纳米技术飞速发展的今天,侧墙技术将会在更高精度上发挥其作用。
基金supported by the‘‘Strategic Priority Research Program’’of the Chinese Academy of Sciences(XDA09020402)National Key Basic Research Program of China(2013CBA01900,2010CB934300,2011CBA00607,2011CB932804)+2 种基金National Integrate Circuit Research Program of China(2009ZX02023-003)National Natural Science Foundation of China(61176122,61106001,61261160500,61376006)Science and Technology Council of Shanghai(12nm0503701,13DZ2295700,12QA1403900,13ZR1447200,14ZR1447500)
文摘In this letter, a phase change random access memory(PCRAM) chip based on Ti0.4Sb2Te3 alloy material was fabricated in a 40-nm 4-metal level complementary metal-oxide semiconductor(CMOS) technology. The phase change resistor was then integrated after CMOS logic fabrication. The PCRAM was successfully embedded without changing any logic device and process, in which 1.1 V negative-channel metal-oxide semiconductor device was used as the memory cell selector. The currents and the time of SET and RESET operations were found to be 0.2 and 0.5 m A, 100 and 10 ns,respectively. The high speed performance of this chip may highlight the design advantages in many embedded applications.
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.
基金National Natural Science Foundation of China,Grant/Award Numbers:M0441,61634008,91964204111 Project of China,Grant/Award Number:B14040+3 种基金Open Project of National Key Laboratory of Materials for Integrated Circuits,Grant/Award Number:SKL202207Shanghai Research and Innovation Functional Program,Grant/Award Number:17DZ2260900National Key Projects of China,Grant/Award Number:2021XJTU0016Natural Sciences and Engineering Research Council of Canada,Grant/Award Numbers:RGPIN-2017-06915,RGPIN-2023-04416。
文摘In order to fulfill the complex cognitive behaviors in neuromorphic systems with reduced peripheral circuits,the reliable electronic synapses mimicked by single device that achieves diverse long-term and short-term plasticity are essential.Phase change random access memory(PCRAM)is of great potential for artificial synapses,which faces,however,difficulty to realize short-term plasticity due to the long-lasting resistance drift.This work reports the ruthenium-doped Ge_(2)Sb_(2)Te_(5)(RuGST)based PCRAM,demonstrating a series of synaptic behaviors of short-term potentiation,pair-pulse facilitation,longterm depression,and short-term plasticity in the same single device.The optimized RuGST electronic synapse with the high transformation temperature of hexagonal phase>380C,the outstanding endurance>108 cycles,the low resistance drift factor of 0.092,as well as the extremely high linearity with correlation coefficients of 0.999 and 0.976 in parts of potentiation and depression.Further investigations also go insight to mechanisms of Ru doping according to thorough microstructure characterization,revealing that Ru dopant is able to enter GST lattices thus changing and stabilizing atomic arrangement of GST.This leads to the short-term plasticity realized by RuGST PCRAM.Eventually,the proposed RuGST electronic synapses performs a high accuracy of94.1%in a task of image recognition of CIFAR-100 database using ResNet 101.This work promotes the development of PCRAM platforms for large-scale neuromorphic systems.
