水平冷壁CVD生长4H-SiC同质外延膜

采用自行设计的水平冷壁低压化学气相沉积（LPCVD）方法在偏向〈11-20〉晶向8°的n型4H-SiC（0001）衬底上进行了同质外延生长．在5.3e3Pa的低压下，外延膜生长速率超过3μm/h．电容电压法测试表明在非有意掺杂外延膜中净施主浓度为8.4e16cm－3．Nomarski显微镜观察表明厚外延膜的表面光滑，生长缺陷密度很低．AFM测试显示表面均方根粗糙度为0.3nm，没有观察到宏观台阶结构．Raman谱线清晰锐利，表现出典型的4H-SiC特征．在低温PL谱中，近带边区域出现很强的自由激子峰，表明样品是高质量的．     

氯基条件下4H-SiC衬底的同质外延生长研究

利用课题组自主研发的热壁低压化学气相沉积(HWLPCVD)系统,在朝[11-20]方向偏转4°的(0001)Si面4H-SiC衬底上进行快速同质外延生长,研究了生长温度及氯硅比(Cl/Si比)对外延生长速率的影响机理.研究发现,外延生长速率随生长温度的提高呈线性增加,而Cl/Si比的改变对生长速率的影响不大.文章进一步探究了Cl/Si比对4H-SiC外延层表面缺陷的影响.较低的Cl/Si比(0.4～2)可以减少或消除三角缺陷,Cl/Si比较高(大于5)时,表面质量反而下降,因而,适当的Cl/Si比对于获得表面形貌良好的4H-SiC外延层至关重要.     

氢气体积流量对n型4H-SiC同质外延生长的影响

在商业化偏4°导电型4H碳化硅(SiC)衬底上采用化学气相沉积(CVD)的方法进行n型4H-SiC同质外延层生长,研究反应过程中氢气(H₂)对外延生长的影响,并使用表面缺陷测试仪、汞探针和红外膜厚仪等设备对外延层进行分析和表征。结果表明,氢气体积流量由基础值80增加到120 L/min,生长速率呈先增加后降低的趋势,生长速率的增加值最大为2μm/h,但缺陷呈先减少后增加的趋势。在高温CVD外延过程中,生长速率阶段性变化的原因：一是生长速率由气相质量转移系数和表面化学反应速率共同决定;二是氢气体积流量过大时,大量的析出氢难以及时离开生长表面,不利于反应物的有效分解和再沉积过程。综上所述,采用100 L/min氢气体积流量的生长工艺可在较高生长速率下制备高质量、厚度均匀性0.91%和载流子浓度均匀性1.81%的SiC外延片。     

Si~+注入SOS中退火固相外延再生长改善结晶质量

本文研究Si~+室温深注入(150～160keV,1～3×10~15/cm~2)SOS中600+1050℃两步退火固相外延再生长改善SOS膜界面附近结晶质量和Si~+室温浅注入(85keV,3×10~(15)/cm~2)SOS中600+1050℃两步退火固相外延再生长改善SOS膜表面结晶质量的工艺.180keVH~+沟道效应—背散射测量表明,两步Si~+注入和两步退火团相外延再生长工艺能够有效地改善SOS膜结晶质量°表面归一化最小产额x_o、界面最小产额x_i 和退道率dx/dz分别减小到0.06、0.12和0.19/μm.     

外延生长6H-SiC/Si薄膜的微结构研究

采用 Si H4 -C3H8-H2 气体反应体系 ,通过 APCVD工艺在 Si(1 0 0 )衬底上进行 Si C薄膜生长时 ,严格控制缓冲层生长的工艺条件 ,即 1 3 0 0°C碳化温度较高的 C3H8饱和浓度 ,可以获得结晶质量良好的 6H-Si C单晶外延层。利用 SEM、X射线衍射能谱 (XRD)及光致发光谱 (PL)分析了薄膜微结构并讨论了其微观机制     

水平冷壁CVD生长4H-SiC同质外延膜

采用自行设计的水平冷壁低压化学气相沉积(LPCVD)方法在偏向〈1120〉晶向8°的n型4H-SiC(0001)衬底上进行了同质外延生长.在5.3×103Pa的低压下,外延膜生长速率超过3μm/h.电容-电压法测试表明在非有意掺杂外延膜中净施主浓度为8.4×10 15cm-3.Nomarski显微镜观察表明厚外延膜的表面光滑,生长缺陷密度很低.AFM测试显示表面均方根粗糙度为0.3nm,没有观察到宏观台阶结构.Raman谱线清晰锐利,表现出典型的4H-SiC特征.在低温PL谱中,近带边区域出现很强的自由激子峰,表明样品是高质量的.     

形成SOI结构的ELO技术研究

本文研究了在常压外延系统中,利用 SiCl_4/H_2/Br_2体系在SiO_2上外延横向生长(ELO)单晶硅技术.比较了Br_2和HCl对硅的腐蚀速率,发现前者对娃的腐蚀速率约比后者慢一个数量级,指出Br_2的引入有着重要意义.给出了Br_2和H_2对Si和SiO_2的腐蚀速率曲线,讨论了外延横向生长速率对SOI结构的材料表面形貌的影响.在该 SOI膜上制造了 MOS/SOI器件,其N沟最大电子迁移率为360cm~2/V.s(沟道掺杂浓度为 1×10~(16)/cm~3),源-漏截止电流为 9.4×10~(-10)A/μm.     

小切角衬底上4H-SiC同质外延薄膜的形貌

4H-SiC外延薄膜是加工高频、大功率电子电力器件的理想半导体材料,而使用不同斜切角的衬底进行外延生长的工艺不同.在1.2°小切角的4H-SiC离轴衬底上采用化学气相沉积(CVD)法生长同质外延薄膜.为了改善外延薄膜的表面形貌,对生长温度、原位表面处理和C/Si比这三个重要的生长参数进行了优化.利用光学显微镜和原子力显微镜(AFM)观察外延薄膜的表面形貌,发现较高的生长温度和较低的C/Si比可以有效降低缺陷密度和表面粗糙度.在生长前使用硅烷气体进行原位表面处理可以有效减小外延薄膜表面的台阶聚束效应.低温光致发光测试表明生长的外延薄膜质量良好.     

PECVD法制备的ZnO薄膜结晶性能的影响

报道了在等离子体作用下,以CO2/H2为氧源,Zn(C2H5)2为锌源,N2为载气,在Si(111)衬底上采用自行设计等离子体化学气相沉积(PECVD)装置来生长的ZnO薄膜。采用X射线衍射仪(XRD)、原子力显微镜(AFM)和场发射扫描电镜分别对不同衬底温度生长的薄膜样品进行了组成、表面和横截面的形貌表征,并且测试了薄膜的PL谱。研究结果表明,衬底温度直接影响薄膜的结晶质量。随衬底温度的升高,ZnO薄膜的结晶取向性开始增强,晶粒尺寸增大。在衬底温度约为450℃时,生长的ZnO薄膜有很强的择优取向性。     

Si上Si_(1-x-y)Ge_xC_y三元合金薄膜的生长

研究了 Si衬底上 Si Ge C合金薄膜的生长。以 C2 H4 为 C源、采用快速加热超低压化学气相淀积 (RTP/VL P- CVD)的非平衡生长技术 ,在 Si(10 0 )衬底上生长出具有一定代位式 C含量的硅基 Si Ge C合金。实验表明 :较低的生长温度和较高的 Si H4 /C2 H4 流量比有利于代位式 C原子的形成和材料晶体质量的提高。     

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.