非易失铁电存储器的进展和若干问题

铁电薄膜与半导体集成,产生了新一代非易失存储器。它的功耗之小,写入速度之快,可重写次数之多以及抗辐照能力之强是目前任何一种半导体存储器所不及的。文章介绍了非易失铁电存储器的原理、特点、进展和应用,并讨论了这类存储器在进入大规模商业生产时所面临的若干材料、工艺和器件失效等问题。     

不同工艺尺寸CMOS器件单粒子闩锁效应及其防护方法

基于建立的不同工艺尺寸的CMOS器件模型,利用TCAD器件模拟的方法,针对不同工艺CMOS器件,开展了不同工艺尺寸CMOS器件单粒子闩锁效应(SEL)的研究。研究表明,器件工艺尺寸越大,SEL效应越敏感。结合单粒子闩锁效应触发机制,提出了保护带、保护环两种器件级抗SEL加固设计方法,并通过TCAD仿真和重离子试验验证防护效果,得出最优的加固防护设计。结果表明,90nm和0.13μm CMOS器件尽量选用保护带抗SEL结构,0.18μm或更大工艺尺寸CMOS器件建议选取保护环抗SEL结构。     

液晶相位调控器件的高功率激光应用相关问题

液晶相位调控器件在聚变点火、激光加工、光电对抗、激光雷达、激光通讯、激光防护等高功率激光领域有着非常广泛的应用及应用前景。但受限于构成器件材料自身抗激光损伤能力的限制以及缺乏对高功率激光辐照下液晶相位调控器件相位调控性能退化及损伤特性的系统研究,目前液晶相位调控器件的激光耐受力还难以满足高功率激光系统的应用和发展需求。为指导高激光耐受力液晶相位调控器件的制备工艺优化,对液晶相位调控器件在高峰值和高平均功率激光应用下出现的损伤现象以及性能退化进行了综述,最后对液晶相位调控器件激光耐受力提升方法做了总结和归纳。     

抗激光减反射膜

介绍１．０～１．８μｍ抗激光宽带减反射膜的薄膜设计，制备工艺，测试方法及结果。通过采取一系列工艺改进措施，大幅度提高了膜片的抗激光性能，制备的膜片抗光损伤阈达到５００ｍＷ／ｃｍ＾２。     

波导厚度变动、偏振变动以及折射率变动脱敏高分子宽带耦合器设计

针对高分子光波导在制造工艺中波导芯厚度难以控制、芯层和包层的折射率差变动时的随机性以及材料各向异性引起的偏振态依赖性等实际问题,提出了采用抗波导芯厚度误差、抗折射率差变动和抗偏振变动的宽带波导耦合器回路结构的解决方案,给出了设计的理论和方法。在实测数据的基础上,进行了带宽为120nm的3dB氟化聚酰亚胺波导耦合器设计。由该器件的三维BPM仿真结果表明,在上述带宽上,波导芯厚度的变动范围为7～8μm、相对折射率差变动范围为0 24%～0.30%,两个正交偏振态都具有(50±2.0)%功率输出比的良好特性。     

电致发光的完全悬空超薄硅衬底氮化镓基蓝光LED器件的制备与表征

为提升硅衬底氮化镓基LED(发光二极管)器件的光电性能和出光效率,本文提出了一种利用背后工艺实现的悬空薄膜蓝光LED器件。结合光刻工艺、深反应离子刻蚀和电感耦合等离子体反应离子刻蚀的背后工艺,制备了发光区域和大部分正负电极区域的硅衬底完全掏空,并减薄大部分氮化镓外延层的悬空薄膜LED器件。对悬空薄膜LED器件进行三维形貌表征,发现LED悬空薄膜表面平坦,变形程度小,证明背后工艺很好地解决了氮化镓外延层和硅衬底之间由于应力释放造成的薄膜变形问题。表征了LED器件的电流电压曲线和电致发光光谱等光电特性,对不同结构、不同发光区域尺寸的LED器件进行对比,发现悬空薄膜LED器件的光电性能和出光效率比普通LED器件更优越,且发光区尺寸变化对LED器件性能的影响更明显。在15 V驱动电压下,与普通LED器件相比,发光区直径为80μm的悬空LED器件的电流从4.3 mA提升至23.9 mA。在3 mA电流的驱动下,峰值光强提升了约5倍,而发光区直径为120μm的悬空器件与发光区直径为80μm的悬空器件相比,出光效率提升更为明显。本研究为发展高性能悬空氮化物薄膜LED器件提供了更多可能性。     

用于FED和PDP平板显示高压驱动电路的CMOS器件

在Synopsys TCAD软件环境下,结合中国科学院微电子研究所0.8μm标准CMOS工艺条件对于高压CMOS器件进行了工艺和器件模拟。由于考虑到与标准CMOS工艺的兼容性,高压CMOS器件均采用LDMOS结构;根据RESURF技术,对于器件的漂移区进行了优化。器件模拟结果表明,高压NMOS器件源漏击穿电压为220 V;阈值电压和驱动能力分别为0.8 V和1×10-4A/μm。高压PMOS器件源漏击穿电压为-135 V;阈值电压和驱动能力分别为-9.7 V和1.8×10-4A/μm。高压CMOS器件的研制可为进一步研制FED和PDP平板显示高压驱动电路奠定基础。     

有机薄膜电致发光器件工艺检测的一种简便方法——覆膜加热观测法

提出了一种简便易行、并与有机薄膜电致发光器件制备工艺完全兼容的工艺检测方法－－覆膜加热观测法。这种方法是在器件的制备工艺过程中,同时在铟锡氧化物（ITO）电极的各层有机薄膜上覆盖一层不透气的薄膜（如金属Al膜等）,接着进行快速加热,最后对器件表面进行形貌观测。采用这种方法,观察了器件表面气泡的形成过程,观察了加热温度、ITO表面处理以及有机物纯度对敢泡形成的影响。实验表明,覆膜加热观测法能有效地对工艺进行对比检测,从而达到改进工艺、提高器件质量的目的。     

对偏振变动和膜厚变动脱敏的高分子波导宽带耦合器

针对高分子光波导制造工艺中波导芯厚度的均匀性难以控制,以及材料较大的折射率各向异性引起的偏振态依赖性的实际问题,提出了采用抗波导芯厚度误差、抗偏振变动的宽带波导耦合器回路结构的解决方案,并给出了优化设计的理论和方法.在实测了含氟聚酰亚胺薄膜的色散特性的基础上,采用该方法做了中心波长为1550 nm、带宽为120 nm的3 dB含氟聚酰亚胺波导耦合器设计.该器件的三维BPM仿真运行结果表明,在上述带宽上,波导芯厚度变动在7～8 μm的范围内,两个正交偏振态均可实现(50±1.0)% 功率输出比的良好特性.     

含氟聚酰亚胺光波导120 nm宽带耦合器的抗温度变动设计

提出一种适合于宽带光波导耦合器的抗温度变动的优化设计理论和方法。使用该理论和方法 ,在 1490～16 10nm带域上 ,对含氟聚酰亚胺光波导做了宽带光波导 3dB耦合器的抗温度变动设计。器件经三维波束传播法模拟运行验证 ,结果表明 ,在 12 0nm带宽上 ,从零下 10℃至零上 40℃的温度变动中 ,器件实现了 ( 0 .5 0 0± 0 .0 0 7)功率输出比的良好特性。同时报道了含氟聚酰亚胺薄膜波导的制备工艺及其温度特性和色散特性的测试。     

Universal memory based on phase-change materials: From phase-change random access memory to optoelectronic hybrid storage

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.     

Three-Dimensional Simulations of RESET Operation in Phase-Change Random Access Memory with Blade-Type Like Phase Change Layer by Finite Element Modeling

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 0.67 mA to 0.32 mA.Therefore,the BTL cell will be appropriate for high performance PCRAM device with lower power consumption and lower RESET current.     

相变光存储研究的新进展

光存储朝着高密度、大容量、高数据传输速率、多功能方向发展。可擦重写相变光存储介质和技术吸引着越来越多研究者的兴趣。本文主要综述了相变光存储原理、材料性能改进和高密度相变存储技术方面的现状和新进展。     

相变光存储研究的新进展

光存储朝着高密度、大容量、高数据传输速率、多功能方向发展。可擦重写相变光存储介质和技术吸引着越来越多研究者的兴趣。本文主要综述了相变光存储原理、材料性能改进和高密度相变存储技术方面的现状和新进展     

Nano-scale gap filling and mechanism of deposit-etch-deposit process for phase-change material

Ge2Sb2Te5 gap filling is one of the key processes for phase-change random access memory manufacture.Physical vapor deposition is the mainstream method of Ge2Sb2Te5 film deposition due to its advantages of film quality,purity,and accurate composition control.However,the conventional physical vapor deposition process cannot meet the gapfilling requirement with the critical device dimension scaling down to 90 nm or below.In this study,we find that the deposit-etch-deposit process shows better gap-filling capability and scalability than the single-step deposition process,especially at the nano-scale critical dimension.The gap-filling mechanism of the deposit-etch-deposit process was briefly discussed.We also find that re-deposition of phase-change material from via the sidewall to via the bottom by argon ion bombardment during the etch step was a key ingredient for the final good gap filling.We achieve void-free gap filling of phase-change material on the 45-nm via the two-cycle deposit-etch-deposit process.We gain a rather comprehensive insight into the mechanism of deposit-etch-deposit process and propose a potential gap-filling solution for over 45-nm technology nodes for phase-change random access memory.     

基于库仑阻塞原理的多值存储器

设计了一种基于库仑阻塞原理的新型单电子多值存储器.器件包括两个多隧穿结结构和一个单电子晶体管，其中单电子晶体管起到一个静电计的作用来实现数据的读取.两个隧穿结库仑阻塞区域的大小不同使得器件具有三个稳定的存储状态.利用这个原理可以制备出多值的动态随机存储器和非挥发性的随机存储器.这种低功耗的单电子多值存储器可以实现信息的超高密度存储. 关键词： 库仑阻塞 单电子晶体管     

Atomic crystals resistive switching memory

Facing the growing data storage and computing demands, a high accessing speed memory with low power and non volatile character is urgently needed. Resistive access random memory with 4F~2 cell size, switching in sub-nanosecond cycling endurances of over 10~(12) cycles, and information retention exceeding 10 years, is considered as promising nex generation non-volatile memory. However, the energy per bit is still too high to compete against static random acces memory and dynamic random access memory. The sneak leakage path and metal film sheet resistance issues hinder th further scaling down. The variation of resistance between different devices and even various cycles in the same device hold resistive access random memory back from commercialization. The emerging of atomic crystals, possessing fin interface without dangling bonds in low dimension, can provide atomic level solutions for the obsessional issues. Moreove the unique properties of atomic crystals also enable new type resistive switching memories, which provide a brand-new direction for the resistive access random memory.     

Simulation of Phase-Change Random Access Memory with Ring-Type Contactor for Low Reset Current by Finite Element Modelling

A three-dimensional finite element models for phase change random access memory （PCRAM） is established to simulate thermal and electrical behaviours during RESET operation. The RESET behaviours of the conventional structure （CS） and the ring-type contact in bottom electrode （RIB） are compared with each other. The simulation results indicate that the RIB cell has advantages of high heat efficiency for melting phase change material in cell, reduction of contact area and lower RESET current with maintaining good resistance contrast. The RESET current decreases from 1.26mA to 1.2mA and the heat consumption in CST material during programming increases from 12% to 37% in RIB structure. Thus the RIB structure PCRAM cell is suitable for future device with high heat efficiency and smaller RESET current.     

阻变式存储器存储机理

阻变式存储器(resistive random access memory,RRAM)是以材料的电阻在外加电场作用下可在高阻态和低阻态之间实现可逆转换为基础的一类前瞻性下一代非挥发存储器.它具有在32nm节点及以下取代现有主流Flash存储器的潜力,成为目前新型存储器的一个重要研究方向.但阻变式存储器的电阴转变机理不明确,制约它的进一步研发与应用.文章对阻变式存储器的体材料中几种基本电荷输运机制进行了归纳,总结了目前对阻变式存储器存储机理的理论模型.     

Design of broadband achromatic metasurface device based on phase-change material Ge2Sb2Te5

Based on the phase-change material Ge₂Sb₂Te₅ (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 μm to 13 μm are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems.