CdTe and HgTe surface growth kinetics for molecular and metalorganic molecular beam epitaxy

The surface growth kinetics of CdTe and HgTe have been investigated during molecular and metalorganic molecular beam epitaxy. The surface growth kinetics was studied through in-situ measurements of the growth rate as a function of flux ratio and substrate temperature on the (001), (111)B, and (211)B CdTe surface orientations. For the (001) and (111)B CdTe growth kinetics, the existence of low binding energy surface precursor sites was proposed for both molecular and atomic growth species before lattice incorporation. Intensity oscillations were observed during HgTe growth on misoriented (111)B surfaces and during CdTe growth on the (211)B orientation. The (211)B surface reconstructions displayed both vicinal and singular surface characteristics, depending on the growth flux ratio.     

Fabrication and characterization of low-cost ultrathin flexible polyimide interposer

A passive interposer, which is a way to bridge the feature gap between the integrated circuit (IC) and the package substrate, is a key building block for high performance 3-D systems. In this paper, polyimide (PI) is proposed as an alternative to glass and silicon based interposers for cost-effective 2.5-D/3-D IC integration. The development of interconnect technology using an ultrathin flexible polyimide interposer (UFPI) for 2.5-D/3-D packaging applications is described in detail. A semi-additive process consisting of copper seed layer deposition, photolithography, and electrolytic copper pattern plating is used for fabricating a double-sided flexible fan out interposer. A UFPI with electrodeposited micro-scale copper (Cu) fine patterns and laser drilling microvia is investigated using a scanning electron microscope (SEM), energy-dispersive spectrometry (EDS), X-ray spectrometry, and an optical 3-D profilometer. The UFPI with fine pitch on 12.5 μm thin PI substrates has been demonstrated. The result is a proof-of-concept to exploit the opportunities of cost-effective 2.5D flexible interposer production.     

AlN多层基板的研制

MCM技术推动了现代微电子技术迅猛发展,已广泛应用于各种通讯系统的收发组件之中。AIN基板作为MCM技术多层基板主流之一,由于其高热导率、与硅片匹配的热膨胀系数、高介电常数、兼容各种芯片组装工艺的优点,在各个领域均获得了广泛的应用。文章结合一个微波组件AIN基板的研制,阐述了在AIN基板研制过程中解决的工艺难点,如粉料配制、流延、层压、烧结等,对研制的AIN基板进行了物理性能与电性能测试,结果表明AIN基板完全可以满足大功率毫米波／微波组件的实用化要求。     

Effect of abrasive particle concentration on preliminary chemical mechanical polishing of glass substrate

Effect of abrasive particle concentration on material removal rate (MRR), MRR per particle and the surface quality in the preliminary chemical mechanical polishing (CMP) of rough glass substrate was investigated. Experimental results showed that the MRR increases linearly with the increase of abrasive concentration and reaches to the maximum when the abrasive concentration is 20 wt.%, and then tends to be stable. When the abrasive concentration increases from 2 to 5 wt.%, the MRR per particle increases greatly and reaches a peak. Then the MRR per particle decreases almost linearly with the increase of the abrasive concentration. The root mean squares (RMS) roughness almost decreases with increasing particle concentration. In addition, in situ coefficient of friction (COF) was also conducted during the polishing process and the zeta potentials of abrasive particles in slurry with different solid concentration were also characterized. Results show that COF value is not related to zeta potential but be sensitive to glass surface conditions in terms of rough peaks in preliminary polishing of glass substrate.     

半模SAFSIW谐振腔耦合带通滤波器设计与实现

空气隙填充基片集成波导(Slab Air-Filled Substrate Integrated Waveguide,SAFSIW)作为一种新型的导波结构,被广泛应用于毫米波传输线以及无源电路的设计,由于SAFSIW 中空气隙的存在,其相较于传统的SIW 具有更高Q值。本文基于半模双腔耦合SAFSIW 设计并实现了一款中心频率为19 GHz 的带通滤波器。为了改善滤波器的带外抑制,通过给谐振器并联枝节线结构,在滤波器的上边28 GHz 处,引入一个传输零点,大大改善了滤波器的带外抑制特性。利用双面覆铜的LCP 基板进行了滤波器的加工,并对其进行测试。测试结果表明,该滤波器中心频率为19 GHz,相对带宽达18%,插入损耗优于-4.2 dB,回波损耗小于-16 dB。由于上边带传输零点的引入,该滤波器在28.5 GHz 时,上边带抑制达到-36 dB 以下。实物测试相比于仿真结果有一定的恶化,主要原因是由于SMA转接头带来的损耗以及HMSAFSIW谐振腔的加工误差所导致。     

国内外碳化硅功率器件发展综述

对国内外碳化硅(Silicon Carbide,SiC)单晶衬底技术、外延片技术、功率器件性能特点进行了归纳分析,指出SiC功率器件产品在应用中面临的问题:SiC功率器件驱动技术和保护技术尚不成熟、电磁兼容问题未完全解决和应用的电路拓扑不够优化等.针对这些问题应从以下几个方面着手发展:降低单晶衬底和外延片材料成本、降低SiC器件在高温下的损耗和开发新的适合SiC功率器件的封装技术.     

Preparation and characterization of new window material CdS thin films at low substrate temperature (<300 K) with vacuum deposition

Low-temperature vacuum deposition instead of the commonly used vacuum deposition at high substrate temperatures has been applied to prepare new window material CdS thin films. The structural, optical and electrical properties of vacuum-evaporated CdS thin films were investigated as a function of substrate temperature (100–300 K) and the post-deposition annealing temperature (at 473, 573 and 673 K). It was determined that films deposited at all substrate temperatures were polycrystalline in nature with hexagonal structure and a strong (0 0 2) texture. The AFM and SEM studies showed that the microstructures of the as-deposited films agreed with the expectations from structure zone model. X-ray diffraction studies showed that the crystallinity of the CdS films was improved on annealing. Optical spectroscopy results of the films indicated that the optical band gap value increased from 2.40 to 2.42 eV with decreased substrate temperature. Increasing the annealing temperature sharpened the band edge. The dark resistivity increased from 4.5×10³ to 7.3×10³ Ω cm and the carrier concentration decreased from 4.7×10¹⁷ to 3.5×10¹⁵ cm⁻³ as the substrate temperature decreased from 300 to 100 K.     

直流偏压对脉冲激光烧蚀沉积非晶碳膜的影响

在不同的负直流衬底偏压下，用脉冲激光沉积法在单晶Si和K9玻璃衬底上沉积上水晶碳膜，用扫描电镜观察膜的表面形貌；用椭偏法测量沉积在K9玻璃上的厚茺和折射率；显微硬度相对于硅衬底测量；对沉积在硅衬底上的膜进行了Raman光谱分析，光谱表现为3个峰。在激光能量相同时，线宽随偏压不同而不同，膜的硬度随偏压不同而不同。     

LTCC多层微波互连基板布局布线设计及制造技术

采用低温共烧陶瓷 (LTCC)技术制造多层微波互连基板 ,可以研制出高密度的T/R组件。讨论了多层基板中微带线和带状线的结构及其优化设计技术 ,介绍了制造工艺流程和关键工艺难点。     

薄膜金属化LTCC基板的薄膜阻碍层对共晶焊的影响

讨论了LTCC工在板薄膜金属化技术中,有效阻碍层的选择对基板共晶焊的影响。实验结果表明,Ti/Ni是一种高可靠性的阻碍层,而且Ti/Ni/Au也是一种较理想的LTCC基板薄膜金属化结构。