Enhancement of the light output of GaN-based light-emitting diodes using surface-textured indium-tin-oxide transparent ohmic contacts

InGaN/GaN multi-quantum well (MQW) light-emitting diodes (LEDs) with indium tin oxide (ITO) as widow layers were fabricated. The ITO surface was textured utilizing the natural lithography combined with the inductively coupled plasma (ICP) etching technology by use of polystyrene spheres as the etching mask. The morphologies of the textured ITO surface were characterized by a scanning electron microscope (SEM) and an atomic force microscope (AFM). The electrical and optical properties of surface-textured ITO/GaN LEDs were measured and analyzed. The influence and dependence of ICP etching time on the light output of the fabricated LEDs was investigated. Experimental results indicated that ITO/GaN LEDs with nano-islands with a depth of about 120 nm and a diameter about 320 nm on the surfaces exhibited a 60% or more enhancement in the output power. The typical 20 mA driven forward voltage is only 0.2 V higher than that of conventional planar ITO/GaN LED. The fabricated surface-textured GaN LED chips from the whole 2″ wafer presented a quite good conformance in electrical and optical characteristics, and the proposed method demonstrated a good reliability. The results indicate that the surface-textured ITO method utilizing the natural lithography combined with the inductively coupled plasma (ICP) etching technology has high potential in future large-area high-power GaN LED applications.     

The effect of the crystallization of indium tin oxide on indium tin oxide wet etching based on gate line with the structure of copper/indium tin oxide

In thin film transistor-liquid crystal display (TFT-LCD), the copper/indium tin oxide (Cu/ITO) layer was often used to be gate line. In this event, the patterning of ITO is necessary and important. However, the high temperature generated during Cu deposition will cause ITO to crystallize, which is not conducive to ITO etching. In this paper, the ITO films prepared by radio frequency (RF) magnetron sputtering were annealed according to the monitoring results of production line to simulate and study the effect of crystallization on the etching properties of ITO film. When the annealing temperature was less than 200°C, no large size grains were detected in ITO films, and the ITO films could be easily etched by etchant. However, the ITO films transformed from amorphous structure to polycrystalline structure after being annealed more than 200°C. After wet etching experiments, the polycrystalline ITO films could be hardly removed by etchant. The X-ray photoelectron spectroscopy (XPS) results showed that high temperature annealing induced a large amount of Sn⁴⁺ on ITO films surface. The Sn⁴⁺ was difficult to be dissolved by acid under normal conditions, which might be the most important factors that led to the greatly decreased etching rate for polycrystalline ITO films.     

ICP刻蚀Si／PMMA选择比工艺研究

为了将聚甲基丙烯酸甲酯（PMMA）上的图案等比例的转移到硅基材料上,对基于感应耦合等离子体技术（InductivelyCoupledPlasma,ICP）的si和PMMA的刻蚀速率进行了研究。结合英国牛津仪器公司的ICPl80刻蚀系统,以SF6和O2混合气体为反应气体,研究了在其他参数相同的情况下,不同气体比例对两种材料刻蚀速率的影响,得到刻蚀速率随气体比例变化的曲线,并得出了对于Si和PMMA刻蚀速率相同时的气体比例。实验发现,如果增加反应气体中sR的比重,会加快Si的刻蚀速率而降低PMMA的刻蚀速率,反之,若降低SF6的比重而增加O2的比重,则会相应降低Si的刻蚀速率而增加PMMA的刻蚀速率。据此,通过调节反应气体的比例,实现对Si和PMMA的同速率去除。     

Indium tin oxide anode modification for enhanced polymer light‐emitting devices

Abstract— Effort has been focused on exploring indium tin oxide (ITO) anode modification for enhanced performance of polymer light‐emitting diodes (PLEDs). It was found that oxidative treatment, e.g., a commonly used oxygen plasma, modifies ITO surface effectively to produce a low‐conductivity oxygen‐rich region. As a consequence, oxygen plasma‐treated ITO behaves somewhat similarly to specimens where there is an ultra‐thin insulating layer on its surface. It shows that the presence of such an ultra‐thin insulating interlayer between the ITO and the polymer layer favors the efficient operation of the PLEDs. The result of this effort provides an insight to better understand optimal anode contact for enhanced PLED performance.     

Investigation of fused silica glass etching using C4F8/Ar inductively coupled plasmas for through glass via (TGV) applications

Through glass via (TGV) technology is considered to be a cost effective enabler for the integration of micro electromechanical systems and radio frequency devices. Inductively coupled plasma and Bosch etching process comprise one of the most pervasive methods for through silicon via (TSV) formation. Unfortunately an equivalent process for glass etching remains elusive. In this paper, the influence of plasma etching for fused silica glass were investigated to find the best tradeoff between etch rate and profile of TGVs. The process parameters including bias power, gas flow rate, ratio of etching gases and reaction chamber pressure using Ar/C₄F₈ inductively coupled plasmas were studied. The etching results show that all these three parameters have a significant impact on the etch rate. Furthermore, the adjustment including total flow rate and ratio of Ar/C₄F₈ and chamber pressure can be used to control the via profile. Constant fused silica glass etch rate greater than 1 μm/min was obtained when chiller temperature was 40 °C with etching time of 60 min. The profile angle of TGVs with nearly 90° was also achieved.     

Electron‐beam deposition of MgO on plastic substrate and manufacturing flexible flat fluorescent lamp

Abstract— A flexible fluorescent lamp that utilizes the same plasma discharge mode as in PDPs has been manufactured. The structure of the flexible lamp is simple and easy to manufacture. All‐plastic materials including plastic substrates, barrier ribs (spacers), and sealants for low‐temperature manufacturing processing have been adopted except for the phosphor and MgO thin film. The MgO thin films were coated on the plastic substrates as a protection layer against the plasma discharge. The adhesion and biaxial texture of MgO thin film deposited on the plastic substrates, poly‐ethyle‐nenaphthalate (PEN) and polycarbonate (PC), at low temperature (100–180°C) has been characterized. The MgO film on PEN shows good adhesion under a repeated bending test. The manufactured flexible lamp consists of two plastic substrates of about 3 in. on the diagonal, barrier rib (spacer), and external ITO electrodes. The Ne‐Xe (5%) gas mixture at 100–200 Torr was used for the discharge gas. A maximum surface luminance of about 100 cd/m² was achieved for a 1 ‐kHz AC pulse.     

碳化硅薄膜的ICP浅刻蚀工艺研究

选用SF6/O2 混合气体对等离子体增强化学气相淀积( PECVD)法制备的碳化硅( SiC)薄膜进行了浅槽刻蚀,并通过正交试验设计方法,研究了感应耦合等离子体( ICP)刻蚀技术中反应室压强、偏压射频( BRF)功率、O2 比例三个工艺参数对碳化硅薄膜刻蚀速率的影响及其显著性.实验结果表明:BRF功率对于刻蚀速率的影响具有高度显著性,各因素对刻蚀速率的影响程度依次为BRF功率>反应室压强>O2 比例,并讨论了所选因素对碳化硅薄膜刻蚀速率的影响机理.     

ICP工艺参数对刻蚀Pyrex玻璃影响的实验研究

影响ICP刻蚀的工艺参数包括反应室压力,偏置射频功率,氩气流量比率。通过正交试验的方法,以CHF3和Ar的混合物作为反应气体,利用电感耦合等离子体技术刻蚀Pyrex玻璃。并采用回归分析方法建立了二次回归方程模型描述腐蚀速率和三个因素之间的关系。实验结果表明,氩气的流量比率（总气体流量（CHF3+Ar）是恒定的）对刻蚀速率的影响最大,影响程度的主次顺序为氩气的流量比率,反应室压力,偏置射频功率。腐蚀速率和三个因素之间的数学表达式为：腐蚀速率=532.6800+2.0556×Ar+0.0127×（偏置射频功率）-0.9641×压力-0.0655×Ar2-0.0067×Ar×（偏置射频功率）+0.0217×（偏置射频功率）×压力-0.0504×（压力）2,实验结果证明数学拟合结果良好。     

Surface micromachining of unfired ceramic sheets

Conventional surface micromachining techniques including photolithography and both wet and dry etching have been directly applied to an unfired sheet of yttria-stabilized zirconia ceramic material. Reversible bonding methods were investigated for affixing unfired ceramic samples to silicon handle wafers in order to perform photolithography. Three types of photoresist were investigated. Thin film photoresist allowed a line-width feature size of 8 μm to be obtained. Thick film photoresist exhibited a coverage gradient after being spun on. Chemical etching was successfully performed isotropically with concentrated hydrofluoric acid. A dry thick film resist applied by lamination provided coverage during plasma etching. Neither an oxygen plasma nor a mixture of sulfur hexafluoride and oxygen plasma proved successful at etching the unfired ceramic. Embossing was performed on the meso-scale with feature shrinkage of approximately 45% after sintering.     

Fabrication of microchannels in single crystal diamond for microfluidic systems

A growth of single crystal diamond (SCD) microchannels on HPHT diamond substrate has been carried out successfully by a simple and novel method. Firstly, aluminum film was patterned on SCD diamond substrate surface by magnetron sputtering, photolithography and dry etching techniques. Secondly, the aluminum patterns were transferred onto diamond substrate via inductively coupled plasma etching to form grooves on diamond surface. Finally, microchannels were achieved by epitaxial lateral overgrowth of SCD on the surface of prepared substrate by microwave plasma chemical vapor deposition system. After that, fluorescent liquid was introduced to check hollowness of the microchannels. This work provides a simple and time saving method to fabricate SCD microchannels for microfluidic system, which offers a great potential for hard environment applications.     

Glass barrier ribs for a transparent AC plasma display

Abstract— Transparent glass barrier ribs are proposed for the development of a transparent plasma display. Glass barrier ribs were fabricated via a wet‐etching process with a 20% hydrofluoric acid. Two different etching methods for glass barrier ribs are investigated: a single‐sided etching method and a double‐sided etching method. Simulation and measurement results show that glass barrier ribs formed by the double‐sided etching method are more transparent compared to those formed by a single‐sided etching method. A fabricated transparent AC plasma display with glass barrier ribs showed good transparency and was operated by using a conventional driving scheme.     

Effects of six different highlighting modes on visual search performance in menu options

Highlighting (HI), for example of menu options, is usually considered as improving information processing efficiency. Particularly relevant are the attention effects of valid (target) highlighting, when contrasted with the effects of highlighting distracting information (invalid HI). A visual search experiment was conducted to analyze the requirements of such an overall performance gain under valid HI. The efficiency of six different modes of highlighting (brightness increase, reverse video, color [red], reverse color, blue‐on‐yellow, and red‐on‐green) on a black screen background was determined. Sixty‐two subjects indicated the presence of a prespecified menu option in a list of CAD menu options, of which a subset was highlighted on every trial. Also varied was familiarity of highlighting. Dependent measures were the absolute performance scores (search time and accuracy) and highlighting benefits. Significant absolute performance differences between the modes were found. They were accompanied by a marked dissociation between the absolute and the benefit measures. The HI benefits were calculated as the individual performance differences between target‐highlighted trials (valid HI) and target‐standard (invalid HI) conditions. The bright white mode, which caused the shortest absolute search time, did not result in a benefit. In contrast, the red color condition produced a large benefit, accompanied by only mid‐range absolute performance. The widely used reverse video modes generally led to the poorest performance. Familiarity of highlighting had a differential effect, depending on the dependent measure preferred. Recommendations for the use of highlighting in display design are given.     

Single mask fabrication process for movable MEMS devices

The current work reports on the realization of movable micromachining devices using self-aligned single-mask fabrication process. Only dry etching process utilizing inductively coupled plasma reactive ion etching was used to release 3D micro structures from single crystal silicon substrate. No wet etching process is required to release the structures as is the case with silicon on insulator (SOI) wafers. Also the developed process does not require an SOI substrate and accordingly dispensing with the application of a wet etching step, thus yielding uniform structures without stiction. The optimized process was applied to realize thermally actuated microgrippers. The article presents the development of the fabrication process and demonstrates the operation of the fabricated device. The optimized process provides an avenue for low cost fabrication of movable micromachining devices without the use of complicated wet etching steps typically associated with SOI substrates.     

ITO薄膜的气敏特性􀀁

本文研究了胶体法制备的ＩＴＯ薄膜的气敏特性;并同时研究了各种掺杂杂质对ＩＴＯ薄膜的气敏特性的影响。通过实验发现ＩＴＯ薄膜对乙醇气体具有最高的灵敏度,对二氧化氮等也有较好的敏感特性。一般催化剂型掺杂物如贵金属等掺杂杂对提高ＩＴＯ薄膜的灵敏度没有多大帮助。ＩＴＯ薄膜与ＳｎＯ２薄膜相比具有更高的稳定性。ＩＴＯ薄膜的气敏特性既具有表面控制型的特征,又权有体效应气敏材料的敏感特性。     

Thin‐film barriers using transparent conducting oxides for organic light‐emitting diodes

Abstract— This study covers thin‐film barriers using inorganic barriers of transparent conducting oxides (TCOs) such as zinc oxide (ZnO) and indium tin oxide (ITO). The TCOs were fabricated using a sputtering method with a process gas of pure argon at room temperature. ITO showed better properties as a barrier than the ZnO and exhibited the electronic performance necessary to perform additional functions. The ITO has superior barrier performance because it has a lower crack density due to its partial amorphous phase. For organic/inorganic multilayer barriers, the organic underlayer decreased the water‐vapor transmission rate (WVTR) more than the organic upper layer, indicating that the planarization effect was important in reducing the WVTRs. The results of this organic/ITO multilayer barrier study are expected to be useful in finding a practical solution to OLED encapsulation.     

Etching processes for High Aspect Ratio Micro Systems Technology (HARMST)

 This paper reports on the development of a dry etching based HARMS-Technology which will offer the potential to manufacture micro-engines, micro-turbines, micro-sensors, micro-actuators, and electronic circuits onto a single silicon IC chip. This technology is based on the highly anisotropic and selective dry etching of Si-monocrystals. The suitability of reactive ion etching for the fabrication of micro electro mechanical systems (MEMS) has been evaluated by characterising the change of lateral dimensions vs. depth in etching deep structures in silicon. Fluorine, chlorine and bromine containing gases have provided the basis for this investigation. A conventional planar RIE (Reactive Ion Etching) reactor has been used, in some cases with magnetic field enhancement or ICP (Inductive Coupled Plasma) Source and low substrate temperature. For reactive ion etching based on Cl₂ or Cl₂/HBr plasma a slightly “positive” (top wider than bottom) slope is achieved when etching structures with a depth of several 10 μm, whereas a “negative” slope is obtained when etching with an SF₆/CCl₂F₂ based plasma. Pattern transfer with vertical walls is obtained for reactive ion etching based on SF₆ (with O₂ added) when maintaining the substrate at low temperature (in range ≈−100 °C). Further optimisation of plasma chemistries and reactive ion etching procedures should result in runouts in the order or 0.1 μm/100 μm depth in Si as well as in organic materials. Etching processes for HARMST is demonstrated in the realisation in Si microturbine. Axes or stators (nonmoving parts) are etched into the initial Si-wafer. The movable parts (rotors, beams, etc.) are prepared from electro-chemically etched Si-membranes with defined thicknesses that, all movable parts are created lithographically on the SiN_xO_y surface. This is followed by dry etching the mono-crystalline Si-membrane down to the SiN_xO_y sacrificial layer on the back side of the membrane by an RIE-process. The wafer with the movable parts is flipped onto the wafer with the already etched axis and then positioned and centred. The SiN_xO_y-sacrificial layer is then dissolved by a chemical wet or vapour etch process. Subsequent bonding with a Pyrex glass wafer seals the parts. Received: 30 October 1995/Accepted: 20 May 1996     

Advanced four‐mask a‐Si TFT array fabrication process using improved materials

Abstract— In order to achieve higher‐performance and lower‐cost a‐Si TFT array manufacturing, an advanced four‐mask fabrication process using low‐resistant metals, a new pixel electrode material, and improved unit processes was developed. Slit (or gray‐tone) photolithography, in combination with a continuous all‐in‐one dry‐etching process, solved the chronic problems of the current four‐mask process. Additionally, a new combination of materials and a new wet etchant for the gate‐line patterning made it possible to achieve stabilized wet‐etching results and reduced the number of process steps. Our advanced a‐Si TFT‐array fabrication process is applicable to both notebook and monitor displays, and will further improve the market position of TFT‐LCDs by improved performance and manufacturing process simplification.     

基于氧化石墨烯/聚吡咯-铟锡氧化物微电极的细胞阻抗生物传感器构建及细胞粘附增殖行为检测

构建一种基于氧化石墨烯/聚吡咯-铟锡氧化物GO/PPy-ITO（Graphene Oxide/Polypyrrole-Indium Tin Oxide）微电极的细胞阻抗生物传感器并用于细胞粘附增殖行为学检测。ITO微电极采用光刻技术对感光干膜绝缘层蚀刻而成,通过一步法电聚合技术在ITO微电极表面沉积GO/PPy纳米复合膜制备GO/PPy-ITO微电极;形状测量激光显微镜和扫描电子显微镜分别对GO/PPy表面粗糙度和拓扑形貌进行表征;电化学循环伏安法及阻抗谱表征GO/PPy-ITO微电极的电化学性质;人肺癌细胞株A549粘附、铺展和增殖实验考察GO/PPy界面的生物相容性;以GO/PPy-ITO微电极作为传感电极,利用电化学阻抗谱技术对A549细胞的粘附增殖行为进行检测。结果显示,ITO微电极表面上电沉积的GO/PPy纳米复合物表面平整,分布大量的微孔结构;电化————————————学实验结果显示GO/PPy-ITO微电极比裸ITO微电极具有更低的阻抗特征和更高的电化学活性;GO/PPy比纯PPy膜更能促进A549细胞粘附、铺展和增殖;GO/PPy-ITO微电极表面A549细胞的粘附增殖行为改变电极系统的阻抗谱特征,通过对阻抗谱数据进行等效电路拟合分析获得细胞粘附增殖行为学信息。本文发展的GO/PPy-ITO微电极兼具优良的电化学性质和细胞生物相容性,基于该电极系统构建的细胞阻抗生物传感器可用于细胞病理生理学行为、药物筛选等研究领域。     

High aspect ratio silicon trench fabrication by inductively coupled plasma

Very high aspect ratio silicon trench with nearly vertical sidewall profile had been demonstrated by inductively coupled plasma (ICP) etching. This silicon trench with aspect ratio more than 30 and vertical sidewall were basically fabricated by STS ASE^TM technology and controlled at proper process parameters. We controlled the appropriate platen power and reaction gas to solve the problem of more positive profile at high aspect ratio trench and avoid the bowing formation on the sidewall simultaneously. Different feature sizes for silicon trench were designed to study the aspect ratio dependent etching properties. The 2.2 μm wide trench etched had aspect ratio of 33 and etching rate of 1.8 μm/min while the 5.0 μm wide trench had aspect ratio of 20 and etching rate of 2.5 μm/min. Received: 7 July 1990/Accepted: 25 August 1999     

Characteristics of ACPDP test panels with aluminum fence electrode formed via anodic bonding with soda‐lime glass

Abstract— In an attempt to reduce materials and processing costs of ACPDPs, aluminum fence electrodes were prepared on soda‐lime glass substrates by chemically etching aluminum foil bonded directly onto the substrate via an anodic‐bonding process. Several different fence‐electrode patterns were designed and coated either with a glass dielectric layer or with an anodic aluminum oxide layer. Firing voltages, operation margin, luminance, and luminous efficiency of such test panels were evaluated. The results indicated that the performance of test panels with aluminum fence electrodes is comparable with conventional test panels with ITO/Ag electrodes, demonstrating the possibility of a dramatic reduction in the costs of ACPDPs.