应用于堆叠纳米线MOS器件的STI工艺优化研究

在传统Fin FET集成工艺上,通过Ge Si/Si叠层量子阱结构外延生长再形成堆叠纳米线MOS场效应晶体管的方案,是实现5 nm及其以下CMOS集成电路工艺技术最具可能的器件方案。由于Ge元素在该技术中的引入,导致器件工艺中的浅沟槽隔离(STI)工艺部分产生严重的低温高深宽比工艺(HARP) SiO_2腐蚀速率控制问题。本文针对堆叠纳米线MOS器件STI工艺中的低温HARP SiO_2回刻腐蚀速率调节与均匀性控制问题,进行了全面的实验研究。实验中使用HF溶液对不同工艺条件下的HARP SiO_2进行回刻腐蚀,并对其腐蚀速率变化进行了详细研究,具体包括不同退火时长以及相同退火温度不同厚度HARP SiO_2位置处的腐蚀速率。通过实验结果发现,在退火温度相同的情况下,随着退火时长的增加,SiO_2腐蚀速率逐渐变小;而对于同一氧化层来说,即使退火条件相同,SiO_2不同厚度位置处的腐蚀速率表现也不同,即顶部的速率最大,而底部则最小。由此可以看出,随着退火时长的增加,低温HARP SiO_2腐蚀速率逐渐减小,并且对STI具有深度依赖性。该实验结果对成功制作5 nm技术代以下堆叠纳米线器件的STI结构起到了重要的技术支撑作用。     

应用于堆叠纳米线MOS器件的STI工艺优化研究北大核心CSCD

在传统Fin FET集成工艺上,通过Ge Si/Si叠层量子阱结构外延生长再形成堆叠纳米线MOS场效应晶体管的方案,是实现5 nm及其以下CMOS集成电路工艺技术最具可能的器件方案。由于Ge元素在该技术中的引入,导致器件工艺中的浅沟槽隔离(STI)工艺部分产生严重的低温高深宽比工艺(HARP) SiO_2腐蚀速率控制问题。本文针对堆叠纳米线MOS器件STI工艺中的低温HARP SiO_2回刻腐蚀速率调节与均匀性控制问题,进行了全面的实验研究。实验中使用HF溶液对不同工艺条件下的HARP SiO_2进行回刻腐蚀,并对其腐蚀速率变化进行了详细研究,具体包括不同退火时长以及相同退火温度不同厚度HARP SiO_2位置处的腐蚀速率。通过实验结果发现,在退火温度相同的情况下,随着退火时长的增加,SiO_2腐蚀速率逐渐变小;而对于同一氧化层来说,即使退火条件相同,SiO_2不同厚度位置处的腐蚀速率表现也不同,即顶部的速率最大,而底部则最小。由此可以看出,随着退火时长的增加,低温HARP SiO_2腐蚀速率逐渐减小,并且对STI具有深度依赖性。该实验结果对成功制作5 nm技术代以下堆叠纳米线器件的STI结构起到了重要的技术支撑作用。     

薄膜电极技术及其应用进展

伴随电化学学科的发展，薄膜电极制作技术已经与最新的材料制作技术链接。结合薄膜电极在军事、能源、环境保护、催化反应以及生物化学等领域的应用，综述了薄膜电极分类、各种电极的制备技术，特别是ITO电极、纳米晶体管电极和导电高分子薄膜晶体管电极，在电子纸等显示器件方面的应用。认为复合电极是未来的发展方向，分子自组合有序膜技术在薄膜电极加工方面用途广泛。     

激光诱导液相电极腐蚀新方法

提出了一种激光诱导液相腐蚀新方法—电极腐蚀法。电极腐蚀法是指进行激光化学液相腐蚀时,在腐蚀溶液中添加电极,以吸引反应中间离子脱离基片表面,实现腐蚀的持续稳定进行。理论分析和实验结果都表明,电极腐蚀法可以有效地加快激光腐蚀的进程;吸附在基片表面的离子在电极作用下,快速迁移出基片表面,保证了基片表面腐蚀溶液构成的稳定,进而得到更加均匀的腐蚀表面;利用电流随腐蚀速率变化而变化的特点,使腐蚀速率和深度的直接监控转变为对腐蚀电流的间接控制,简化腐蚀控制方法。基于以上优点,电极腐蚀法可以克服现有激光腐蚀方法的诸多弊端,改善激光腐蚀性能,在特殊结构光电器件的制作和半导体的微细加工中具有广阔的应用前景。     

射频等离子体改性工艺与氧化铟锡薄膜性能研究

采用正交实验方法研究了氧气等离子体表面改性中各工艺因素对ITO薄膜表面性质的影响,获得了IID表面改性的最佳工艺条件,并且通过XPS,AFM,透射光谱的分析以及薄膜表面接触角和方块电阻的测量,表征了优化工艺条件下氧气等离子体处理前后ITO薄膜的表面性质.结果表明,氧气等离子体处理降低了ITO表面的粗糙度和方块电阻,改善了ITO表面的化学组分和浸润性能.另外,以表面处理前后的ITO基片作为空穴注入电极,采用真空热蒸镀技术制备了有机薄膜电致发光(OTFEL)器件,并对器件的电流.电压.亮度特性以及电流效率进行了测试和分析,实验结果显示,氧气等离子体处理降低了启亮电压和驱动电压,提高了发光亮度和电流效率,有效地改善了OTFEL器件的光电性能.     

原子力显微镜与X射线光电子能谱对ITO表面改性的研究

采用氧气等离子体(OP)处理对氧化铟锡(ITO)薄膜进行表面改性,通过原子力显微镜(AFM)、X射线光电子能谱(XPS)和四探针等测试手段对薄膜样品进行表征,研究了OP处理对ITO表面性质的影响.实验结果表明OP处理有效去除了ITO表面的污染物,优化了ITO表面的化学组分,降低了ITO表面的粗糙度和方块电阻,改善了ITO的表面形态.与此同时,通过XPS监测研究了OP处理后ITO表面化学组分随老化时间的变化,结果显示经过优化的化学组分随老化时间增加而逐渐退化.另外,以OP处理后经过不同老化时间的ITO样品作为空穴注入电极,制备了有机电致发光器件(OELD),通过测试器件的电压-电流-亮度特性,进一步研究了ITO表面性质对于OELD光电性能的影响.     

激光刻图在制造 a-Si 光伏器件中的应用

描述了在集成型 a-Si 光伏器件的制造中,利用高功率激光束进行刻图的新方法。作为激光刻图中材料除去的模型,被刻蚀材料的蒸汽压对材料除去会带来很大的影响。在制备 a-Si 光伏器件中,侧边接触的器件结构对激光刻图技术是很合适的。激光的平均功率或激励电流,重复频率、焦距和扫描速度是激光刻图技术的基本参数。我们列出了刻蚀 TCO、a-Si 和背电极薄膜的一些刻蚀条件,可以发现要刻蚀不同的薄膜,需控制这些条件以达到最佳化。     

低损耗液晶光开关器件用透明电极的制备

液晶可以用来制作光通讯系统中的光开关,液晶器件的损耗主要取决于透明电极的透射率, ITO(氧化铟锡)在可见光范围具有高的透射率,但在红外损耗较大。在测定ITO复折射率的基础上,本文借鉴光学薄膜中诱导滤光片的设计思想,设计、制备出了在红外1.5mm~1.6mm范围内高透射率的透明电极,使整个器件的损耗<0.4dB,相应的方块电阻为350W/□。     

柔性储能电池电极的设计、制备与应用EI北大核心CSCD

随着便携式、可穿戴电子器件的迅速发展,柔性储能器件的研究逐渐转向微型化、轻柔化和智能化等方向。同时人们对器件的能量密度、功率密度和力学性能有了更高的要求。电极材料作为柔性储能器件的核心部分,是决定器件性能的关键。柔性储能电子器件的发展,又迫切需要新型电池技术和快速、低成本且可精准控制其微结构的制备方法。因此,柔性锂/钠离子电池、柔性锂硫电池、柔性锌空电池等新型储能器件的研发成为目前学术界研究的热点。本文论述了近年来柔性储能电池电极的研究现状,着重对柔性电极材料的设计(独立柔性电极和柔性基底电极)、不同维度柔性电极材料的制备工艺(一维材料、二维材料和三维材料)和柔性储能电极的应用(柔性锂/钠离子电池、柔性锂硫电池、柔性锌空电池)进行对比分析,并对电极材料的结构特性和电化学性能进行了讨论。最后,指出了柔性储能器件目前所面临的问题,并针对此类问题展望了柔性储能器件未来的重点在于新型固态电解质的研发、器件结构的合理设计及封装技术的不断优化。     

溅射工艺对ITO膜性能的影响

采用磁控反应溅射技术在玻璃表面上淀积大面积掺锡氧化铟薄膜(英文缩写为ITO),成功的应用到各种除冰霜用挡风电热玻璃、液晶显示透明电极和场致发光器件等。本文主要讨论不同的靶材比例、溅射电压、氧分压、基片温度、膜层厚度等工艺参数对ITO膜特性的影响。     

Influence of ITO patterning on reliability of organic light emitting devices

Indium tin oxide (ITO) films are widely used for a transparent electrode of organic light emitting devices (OLEDs) because of its excellent conductivity and transparency. Two types of ITO substrates with different surface roughness were selected to use as anode of OLEDs. In addition, two types of etching process of ITO substrate, particularly the etching time, were also carried out. It was found that the surface roughness and/or the etching process of ITO substrate strongly influenced on an edge of ITO surface, further affected the operating characteristics and reliability of devices.     

Process development of ITO source/drain electrode for the top-gate indium-gallium-zinc oxide transparent thin-film transistor

Indium-tin oxide (ITO) has been widely used as electrodes for LCDs and OLEDs. The applications are expanding to the transparent thin-film transistors (TTFT_S) for the versatile circuits or transparent displays. This paper is related with optimization of ITO source and drain electrode for TTFTs on glass substrates. For example, un-etched ITO remnants, which frequently found in the wet etching process, often originate from unsuitable ITO formation processes. In order to improve them, an ion beam deposition method is introduced, which uses for forming a seed layer before the main ITO deposition. We confirm that ITO films with seed layers are effective to obtain clean and smooth glass surfaces without un-etched ITO remnants, resulting in a good long-run electrical stability of the top-gate indium-gallium-zinc oxide-TTFT.     

聚焦离子束(FIB)刻蚀在光电子器件方面的应用

聚焦离子束无掩模微细加工技术逐渐引起人们的兴趣，它包括聚焦离子束无掩模刻蚀、注入、往积、光刻等。聚焦离子束刻蚀能在半导体激光器材料上加工得到具有光学精度的表面。首先论述聚焦离子束刻蚀的特点，然后概括说明目前它在光电子器件方面的若干应用。     

Facile patterning of reduced graphene oxide film into microelectrode array for highly sensitive sensing

In this study, we develop a new technique to fabricate a reduced graphene oxide (rGO)-based microelectrode array (MEA) with low-cost soft lithography. To prepare patterned rGO, a polydimethylsiloxane (PDMS) mold with an array of microwells on its surface is fabricated using soft lithography, and GO is assembled on an indium tin oxide (ITO) electrode with a layer-by-layer method. The rGO pattern is formed by closely contacting the assembled GO film onto the ITO electrode with the PDMS mold filled with hydrazine solution in the microwells to selectively reduce the localized GO into the rGO. The MEA with patterned rGO as the microelectrode is characterized with Kelvin probe force microscopy (KFM), atomic force microscopy (AFM), and cyclic voltammetry (CV) with ferricyanide in aqueous solution as the redox probe. The KFM and AFM results demonstrate that each rGO pattern prepared under the present conditions is 3 μm in diameter, which is close to that of the PDMS mold we use. The CV results show that the rGO patterned onto the ITO exhibits a sigmoid-shaped voltammogram up to 200 mVs(-1) with a microampere level current response, suggesting that the rGO-based electrode fabricated with soft lithography behalves like a MEA. To demonstrate the potential electroanalytical application of the rGO-based MEA, prussian blue (PB) is electrodeposited onto the rGO-based MEA to form the PB/rGO-based MEA. Electrochemical studies on the formed PB/rGO-based MEA reveal that MEA shows a lower detection limit and a larger current density for the detection of H(2)O(2), as compared with the macroscopic rGO electrode. The method demonstrated here provides a simple and low-cost strategy for the fabrication of graphene-based MEA that are useful for electroanalytical applications.     

Flexible a‐Si:H Solar Cells with Spontaneously Formed Parabolic Nanostructures on a Hexagonal‐Pyramid Reflector

Flexible amorphous silicon (a‐Si:H) solar cells with high photoconversion efficiency (PCE) are demonstrated by embedding hexagonal pyramid nanostructures below a Ag/indium tin oxide (ITO) reflector. The nanostructures constructed by nanoimprint lithography using soft materials allow the top ITO electrode to spontaneously form parabolic nanostructures. Nanoimprint lithography using soft materials is simple, and is conducted at low temperature. The resulting structure has excellent durability under repeated bending, and thus, flexible nanostructures are successfully constructed on flexible a‐Si:H solar cells on plastic film. The nanoimprinted pyramid back reflector provides a high angular light scattering with haze reflectance >98% throughout the visible spectrum. The spontaneously formed parabolic nanostructure on the top surface of the a‐Si:H solar cells both reduces reflection and scatters incident light into the absorber layer, thereby elongating the optical path length. As a result, the nanopatterned a‐Si:H solar cells, fabricated on polyethersulfone (PES) film, exhibit excellent mechanical flexibility and PCE increased by 48% compared with devices on a flat substrate.     

A route to fabricate nanocontacts by X-ray lithography for the realization of single electron transistors and highly sensitive biosensors

The fabrication of single electron transistors and/or highly sensitive biosensors is still a challenging task on account of the tight control required to get proper shapes and size of the electrodes. The nanosized tips and the separation of a few nanometers between electrode pairs are critical features. Conventional lithography is not suited to obtain these features because of the resolution limits, so that previous alternative approaches have involved the use of electron beam lithography, focused ion beam lithography or scanning probe nanolithography. The novel approach presented in this letter is the exploitation of X-ray lithography in the Elettra synchrotron to fabricate arrays of nanocontacts spaced a few nanometers, devoted to the design of a new class of nanodevices based on nanoparticles and/or single molecules, including single electron transistors and highly sensitive biosensors. The method to fabricate such devices is illustrated and discussed. Experimental details of the fabrication process are given and preliminary results are presented through SEM and AFM images. It is worth noting that this paper presents a viable method to produce nanocontacts by using the X-ray lithography by synchrotron radiation source, that has not yet been reported together with experimental, though preliminary, data.     

New silicon architectures by gold-assisted chemical etching

Silicon nanowires (SiNWs) were produced by nanosphere lithography and metal assisted chemical etching. The combination of these methods allows the morphology and organization control of Si NWs on a large area. From the investigation of major parameters affecting the etching such as doping type, doping concentration of the substrate, we demonstrate the formation of new Si architectures consisting of organized Si NW arrays formed on a micro/mesoporous silicon layer with different thickness. These investigations will allow us to better understand the mechanism of Si etching to enable a wide range of applications such as molecular sensing, and for thermoelectric and photovoltaic devices.     

Electrochemical tuning of silver nanoparticles fabricated by nanosphere lithography

An electrochemical method is developed to quantitatively modify and spectroscopically monitor the size and shape of Ag nanotriangles fabricated by nanosphere lithography (NSL) on an indium tin oxide (ITO) electrode surface. AFM and SEM results demonstrate that the preferential order of electrochemical oxidation for a nanotriangle is, surprisingly, bottom edges first, then triangular tips, then out-of-plane height.     

Laser direct write patterning technique of indium tin oxide film

The circuit patterns of transparent conductive oxide films (TCO films) have widely formed using the traditional photolithography method. The indium tin oxide (ITO) films of flat panel displays are one of the TCO films and usually ablated using the wet etching, which is widely adopted in the semiconductor processing. However, the chemical wet etching techniques usually appear with more disadvantages in the procedure, including the chemical pollution, the under-cut effect, the swelling and the costly. Therefore, the dry etching would be replaced the photolithography procedures. The laser directing method is one of the dry etching techniques and could form the circuit pattern on the ITO glasses. Moreover, the laser directing techniques could flexibility make the circuit pattern in the TCO film and the substrate would be not eroded by the laser ablation. The investigation is interested in circuit patterning of glass substrate using the laser direct writing techniques to ablate the ITO films by a UV laser materials processing system. The UV laser is a third-harmonic Nd: YAG laser with a 355 nm of wavelength and the power is 1.0 W. In this paper, the ITO films are ablated by the UV laser materials processing system which used the different repetition rate and the feeding speeds of tables. The results of laser pattering of ITO films are measured using the optical microscope (OM) and the scanning electron microscope (SEM), and it indicates the repetition rate of laser would affect the width of line.     

Graphite patterning in a controlled gas environment

Although a number of methods using scanning probe lithography to pattern graphene have already been introduced, the fabrication of real devices still faces limitations. We report graphite patterning using scanning probe lithography with control of the gas environment. Patterning processes using scanning probe lithography of graphite or graphene are normally performed in air because water molecules forming the meniscus between the tip and the sample mediate the etching reaction. This water meniscus, however, may prevent uniform patterning due to its strong surface tension or large contact angle on surfaces. To investigate this side effect of water, our experiment was performed in a chamber where the gas environment was controlled with methyl alcohol, oxygen or isopropanol gases. We found that methyl alcohol facilitates graphite etching, and a line width as narrow as 3?nm was achieved as methyl alcohol also contains an oxygen atom which gives rise to the required oxidation. Due to its low surface tension and highly adsorptive behavior, methyl alcohol has advantages for a narrow line width and high speed etching conditions.