ICP刻蚀损伤对金属场板结构SiC肖特基二极管电学性能的影响

本文通过电感耦合等离子体（ICP）系统地研究了各种刻蚀参数对4H-SiC刻蚀的影响,并进一步研究了刻蚀损伤对金属场板结构4H-SiC肖特基二极管电学性能的影响。研究表明刻蚀速率和SiC表面形貌都会受到ICP功率、RF功率、压强和刻蚀气体流量的影响。在高的ICP偏压下,观察到了刻蚀损伤（刻蚀坑和刻蚀锥）的形成。更深入的研究表明,这些刻蚀损伤的形成和SiC自身的缺陷有关。这些刻蚀损伤的存在会导致SiC肖特基二极管正反向I-V性能发生恶化。在刻蚀损伤严重的情况下,对比正反向I-V测试结果发现,在0~50V的绝对电压范围内,正向电流甚至远小于反向电流。     

凹栅槽AlGaN/GaN HEMTs器件退火处理效应

研究了如何减小等离子体干法刻蚀导致的大肖特基漏电.用X射线光电能谱(XPS)分析刻蚀前后的AlGaN表面,发现刻蚀后AlGaN表面出现了N窄位,导致肖特基栅电流偏离热电子散射模型,N空位做为一种缺陷使得肖特基结的隧穿几率增大,反向漏电增大,肖特基势垒降低.介绍了一种AlGaN/GaN HEMTs器件退火处理方法,优化退火条件为400℃,Nz氛围退火10min.退火后,栅金属中的Ni与Ga原子反应从而减少N空穴造成的缺陷,器件肖特基反向漏电减小三个量级,正向开启电压升高,理想因子从3.07降低到了2.08.     

TiN/n-GaAs肖特基势垒特性

本文用俄歇能谱(AES)、电流-电压(I-V)和电容-电压(C-V)电学测量等方法,研究了反应溅射制备的TiN/n-GaAs肖特基势垒特性.经800℃高温热退火后,TiN/n-GaAs势垒具有良好的整流特性和高温稳定性,其势垒高度为0.80cV,理想因子n为1.07.同时还观察到许多有意义的结果:即随着退火温度的升高(从500℃到800℃),TiN/n-GaAs肖特基二极管的势垒高度增大,势垒电容减小和二极管反向击穿电压增大.我们认为这可能与溅射过程中GaAs衬底中掺氮有关,并用Shannon模型(即金属/P-GaAs/n-GaAs结构)解释了以上结果.研究结果表明,在自对准GaAs MESFET工艺中,TiN是一种很有希望的栅材料.     

退火温度对Au/Ti/4H-SiC肖特基接触特性的影响

采用电子束蒸发法在4H-SiC表面制备了Ti/Au肖特基电极,研究了退火温度对Au/Ti/4H-SiC肖特基接触电学特性的影响.对比分析了不同退火温度下样品的电流密度-电压(J-V)和电容-电压(C-V)特性曲线,实验结果表明退火温度为500℃时Au/Ti/4H-SiC肖特基势垒高度最大,在.J-V测试和C-V测试中分别达到0.933 eV和1.447 eV,且获得理想因子最小值为1.053,反向泄漏电流密度也实现了最小值1.97×10-8 A/cm2,击穿电压达到最大值660 V.对退火温度为500℃的Au/Ti/4H-SiC样品进行J-V变温测试.测试结果表明,随着测试温度的升高,肖特基势垒高度不断升高而理想因子不断减小,说明肖特基接触界面仍然存在缺陷或者横向不均匀性,高温下的测试进一步证明肖特基接触界面还有很大的改善空间.     

不同退火温度对4H SiC 金半接触的影响

采用高真空电子束蒸发法制作了基于4H SiC外延材料的肖特基二极管,其中欧姆接触材料为Ti/Ni,肖特基接触材料为Ni。常温下,电流-电压(I-V)测试表明Ni/4H SiC肖特基二极管具有良好的整流特性,热电子发射是其主要输运机理。对比分析不同快速退火温度下器件的I-V特性,实验结果表明875 ℃退火温度下欧姆接触特性最好,400 ℃退火温度下器件肖特基接触I-V特性最好,理想因子为1.447,肖特基势垒高度为1.029 eV。     

凹栅槽AlGaN/GaN HEMTs器件退火处理效应

研究了如何减小等离子体干法刻蚀导致的大肖特基漏电. 用X射线光电能谱（XPS）分析刻蚀前后的AlGaN表面,发现刻蚀后AlGaN表面出现了N空位,导致肖特基栅电流偏离热电子散射模型,N空位做为一种缺陷使得肖特基结的隧穿几率增大,反向漏电增大,肖特基势垒降低. 介绍了一种AlGaN/GaN HEMTs器件退火处理方法,优化退火条件为400℃, N2氛围退火10min. 退火后,栅金属中的Ni与Ga原子反应从而减少N空穴造成的缺陷,器件肖特基反向漏电减小三个量级,正向开启电压升高,理想因子从3.07降低到了2.08.     

ZrN/n-GaAs肖特基势垒特性研究

本文用RBS,AES和电特性测量等方法,研究了ZrN/n-GaAs肖特基势垒.结果表明ZrN/GaAs势垒有良好的电特性和高温稳定性.经850℃高温退火后,势垒高度为0.90eV,理想因子n=1.02.同时我们观察到,随着退火温度升高(从500℃升高到850℃),ZrN/GaAs势垒电特性有明显改进:肖特基势垒高度增大、二极管反向电流减小、二极管电容减小和反向击穿电压增大.以上特点表明,ZrN/GaAs是用于自对准高速GaAs集成电路的较为理想的栅材料.     

ICP腔室压力对AlGaN表面刻蚀损伤的影响

对高Al组分AlxGa1-xN(x=50％)进行了ICP刻蚀实验研究,在刻蚀深度相同的前提条件下,对比分析了ICP腔室压力与AlGaN表面损伤之间的相互关系,并讨论了低温热退火对ICP刻蚀损伤的修复作用.XPS测试结果表明,与未经刻蚀的AlGaN表面相比,ICP刻蚀之后的AlGaN表面其表面氮空位VN明显增多,且Al2p、Ga3d等峰位均向高结合能方向漂移.分析讨论发现,ICP腔室压力过小或过大均不利于获得低损伤的刻蚀表面,此外,低温热退火(380℃-200s)对表面氮空位有一定的修复作用,但修复效果较为有限.     

用弹道电子发射显微术研究超薄金属硅化物/硅肖特基接触

采用弹道电子发射显微术 ( BEEM)技术对超薄 Pt Si/Si、Co Si2 /Si肖特基接触特性进行了研究 ,并与电流 -电压 ( I- V)及电容 -电压 ( C- V)测试结果进行了对比 .研究了 Ar离子轰击对超薄Pt Si/n- Si肖特基接触特性的影响 .BEEM、I- V/C- V技术对多种样品的研究结果表明 ,I- V/C- V测试会由于超薄硅化物层串联电阻的影响而使测试结果产生严重误差 ;BEEM测试则不受影响 .随着离子轰击能量增大 ,肖特基势垒高度降低 ,且其不均匀性也越大 .用 BEEM和变温 I- V对超薄 Co Si2 /n- Si肖特基二极管的研究结果表明 ,变温 I- V测试可在一定程度上获得肖特基势垒     

Ti/Al/Ni/Au在GaN N面上的欧姆接触

以Ti/Al/Ni/Au作为欧姆接触金属体系,通过电感耦合等离子体(ICP)刻蚀的预处理,在氢化物气相外延法生长的单晶氮化镓(GaN)材料的N面实现了良好的欧姆接触,其比接触电阻率为3.7×10-4 Ω·cm2.通过扫描电子显微镜、原子力显微镜、阴极荧光和光致发光谱对GaN N面的表面、光学特性进行了对比表征.结果表明:未刻蚀GaN衬底的N面表面存在一定的损伤层,导致近表面处含有大量缺陷,不利于欧姆接触的形成;而ICP刻蚀处理有效地去除了损伤层.X射线光电子能谱(XPS)分析显示刻蚀后样品的Ga 3d结合能比未刻蚀样品向高能方向移动了约0.3 eV,其肖特基势垒则相应降低,有利于欧姆接触的形成.同时对Fe掺杂半绝缘GaN的N面也进行了刻蚀处理,同样实现了良好的Ti/Al/Ni/Au欧姆接触,其比接触电阻率为0.12 Ω·cm2.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.