流延硅基PZT厚膜工艺研究

研究了基于流延技术制备硅基锆钛酸铅（PZT）厚膜的工艺。考虑衬底特性对厚膜品质的影响,在不同的种子层上分别制备了PZT厚膜,测试工艺结果,证实了种子层的作用。分析了高温烧结时间对流延PZT厚膜品质的影响,确定了最优高温烧结时间。文章提出的硅基PZT厚膜工艺可用于制备射频天线的介质基片。     

热压对PTFE基复合介质结构性能的影响

为制备高强度低损耗复合介质,采用热压工艺进行复合介质的成型与烧结,系统地探讨了加热温度、成型压力等工艺参数,对聚四氟乙烯（PTFE）树脂复合陶瓷介质材料微观结构、介电性能与力学性能的影响。采用SEM、X射线衍射分别对复合介质的微观结构及其相组成进行了观察与分析,并获得了制备低损耗复合介质的最佳热压工艺制度。     

低烧ZnO-TiO2微波陶瓷介电特性及片式多层带通滤波器研究

采用材料特性、器件设计及制备工艺相结合的三位一体研究模式,研究了低烧ZnO-TiO2微波陶瓷介电特性,利用高频结构仿真软件HFSS对低烧陶瓷带通滤波器微波特性进行建模,重点介绍材料介电特性对片式带通滤波器性能影响的优化仿真,采用LTCC制造工艺技术制备片式多层带通陶瓷滤波器。研究结果表明:ZnO-TiO2微波陶瓷在895~910℃烧结,陶瓷相ZnTiO3、TiO2稳定存在,具有较佳的微波介质特性,在900℃烧结3h,其介电性能:εr=27.05、Qf=19822GHz、τf=2ppm/℃,该材料与Ag电极能较好匹配。模拟仿真表明:低烧材料的相对介电常数偏差是器件设计制备中的关键要素,仿真优化结果与LTCC试验样品的测试结果吻合较好。制备出的片式多层带通滤波器适用于表面贴装技术。     

高频高Q值MLCC的设计与制作

采用了四种电子材料和工艺分别制作高频高Q值片式多层陶瓷电容器(MLCC).研究、对比了这四种电容器高频特性.结果表明:采用高钯高温烧结体系MLCC的Q值优于其它体系MLCC,但制造成奉高,四种设计方案各有优劣.     

薄膜绝缘层对陶瓷厚膜电致发光显示器件的影响

采用丝网印刷技术，在Al2O3陶瓷板上印刷、高温烧结内电极及绝缘层制备出陶瓷厚膜基板，进而制备了新型厚膜电致发光显示器（TDEL），整个器件结构为陶瓷基板／内电极／厚膜绝缘层／发光层／薄膜绝缘层／ITO透明电极。对用不同薄膜绝缘材料制备的显示器件的特性进行测试、比较、分析，结果表明薄膜绝缘介质层对器件的阈值电压、发光亮度均有一定的影响，以复合绝缘层的性能最优。最后对器件的衰减特性进行了初步分析。     

多层介质膜红外空芯光纤的传输特性

提出了一种计算多层介质膜空芯光纤损耗谱特性的方法,理论分析了介质—金属膜结构红外空芯光纤的传输损耗特性.将各层膜的厚度、材料色散和表面粗糙度等特性引入理论计算后,根据实测损耗谱估算了每层介质膜厚度.通过比较实测和理论计算损耗谱,调整优化了工艺参数.采用液相镀膜法,制作了在中红外波长带有低损耗特性的Ag/SiO2/AgI/SiO2三层介质膜结构空芯光纤.     

杜洛埃有机介质上集成薄膜电阻工艺研究

杜洛埃有机介质广泛应用于高频微波集成电路,由于材料表面固有特性而增加了集成薄膜电阻的难度。通过改变杜洛埃介质表面的形貌获得良好的平滑表面,并采用薄膜电路制造工艺,实现了在无铜箔的杜洛埃介质上制作微波混合集成电路。已成功实现了功分器、微波天线等产品的制作。对集成薄膜电阻的性能进行了详细工艺分析和讨论。     

溶胶-凝胶法制备Bi2O3-ZnO-Nb2O5薄膜及GaNMIS结构C-V特性

采用溶胶-凝胶法制备出高介电常数的Bi2O3-ZnO-Nb2Os(BZN)薄膜.总结出适合作为GaN金属-绝缘层-半导体场效应晶体管(MIS FET)栅介质的BZN薄膜的原料配比、烧结温度和保温时间等工艺参数,解决了原料溶解、粘稠度、浸润度等工艺问题.同时,结合半导体工艺制造出以BZN薄膜为绝缘介质的GaN MIS结构,通过测量到的高频C-V特性曲线,得到薄膜的相对介电常数为91,MIS结构的强反型电压为-3.4V,平带电压为-1.9V.     

溶胶-凝胶法制备Bi2O3-ZnO-Nb2O5薄膜及GaNMIS结构C-V特性

采用溶胶-凝胶法制备出高介电常数的Bi2O3-ZnO-Nb2Os(BZN)薄膜.总结出适合作为GaN金属-绝缘层-半导体场效应晶体管(MIS FET)栅介质的BZN薄膜的原料配比、烧结温度和保温时间等工艺参数,解决了原料溶解、粘稠度、浸润度等工艺问题.同时,结合半导体工艺制造出以BZN薄膜为绝缘介质的GaN MIS结构,通过测量到的高频C-V特性曲线,得到薄膜的相对介电常数为91,MIS结构的强反型电压为-3.4V,平带电压为-1.9V.     

吸收式气敏传感空芯光纤的设计和制备

研发了红外波段吸收式气敏传感空芯光纤.空芯光纤的内面镀有银膜和介质膜,在目标波长提高反射率从而降低损耗.银膜和介质膜分别采用化学银镜反应法和液相镀膜法成膜.优化介质膜的材料和膜厚.光纤在可见光到中红外波段实现了低损耗特性.空芯光纤不仅可以用作气体传感的光吸收气室,而且也可用作红外光的传输媒介.初步实验结果显示这种空芯光纤可以替代普通的气体吸收气室,实现传感系统小型化.     

12.5-gbps operation of 850-nm vertical-cavity surface-emitting lasers with reduced parasitic capacitance by BCB planarization technique

12.5-Gbps operation of 850-nm AlGaAs-based VCSEL fabricated using low-k benzocyclobutene (BCB) planarization technique is reported. The BCB has lowest dielectric constant of 2.65 among conventional passivation dielectrics including polyimide and thick passivation can be easily formed by simple planarization technique, resulting in very low parasitic capacitance especially at around the pad electrode. The thick BCB film buried around the epitaxial post structure reduces the parasitic capacitance down to 0.041 pF which is one third as low as that of the conventional SiN passivated VCSELs. The fabricated BCB-planarized VCSEL exhibits very high relaxation oscillation frequency of 12 GHz for the oxide aperture of 6.5 /spl mu/m, which corresponds to high modulation bandwidth f/sub 3dB/ of 16 GHz with relaxation oscillation frequency of 11 GHz for the oxide aperture of 8.5 /spl mu/m. These values are as comparably high as the reported highest values. Open eye-diagrams up to 12.5 Gbps are also confirmed implying that the presented VCSEL is applicable to the optical data network systems such as Giga-bit Ethernet at higher bit rates. Preliminary reliability test result shows stable optical output power at constant operating current at 100 /spl deg/C over 1000 h.     

Analysis of reliability characteristics of high capacitance density MIM capacitors with SiO2-HfO2-SiO2 dielectrics

In this paper, reliability as well as electrical properties of high capacitance density metal-insulator-metal (MIM) capacitor with hafnium-based dielectric is analyzed in depth. The fabricated MIM capacitor exhibits not only high capacitance density but also low voltage coefficient of capacitance (VCC) and low temperature coefficient of capacitance (TCC). It also has a low leakage current level of about ∼1 nA/cm² at room temperature and 1 V. However, it is shown that voltage linearity has a different dependence on the polarity of applied bias as temperature increases maybe due to the bulk traps between the metal electrode and high-k dielectric interface. In addition, the effect of charge trapping and de-trapping on the voltage linearity is analyzed under constant voltage stress.     

Integrating High-k Ceramic Thin Film Capacitors into Organic Substrates Via Low-Cost Solution Processing

Current organic package-compatible embedded decoupling capacitors are based on thick film (8-16 m) polymer-ceramic composites with dielectric constant (k) of 20-30 and do not have sufficient capacitance density to meet the impedance requirements for emerging high-speed circuits and high power density microprocessors. High-k/high capacitance density ceramics films that can meet the performance targets are generally deposited by high-temperature processing or costly vacuum technology (radio frequency sputtering, PECVD) which are expensive and also incompatible with organic packages. The objective of this project is to develop ultra thin films (100-300nm) with high dielectric constant using organic compatible processes to meet future decoupling applications. In the current study, direct deposition of crystalline ceramic films on organic boards at temperatures less than 100C was demonstrated with the hydrothermal method. Post-hydrothermal treatments were shown to minimize the defects in the as-synthesized hydrothermal barium titanate films and improve the breakdown voltage (BDV) and leakage characteristics. Thin films with high capacitance densities and breakdown voltages of 10V were demonstrated. As an alternate technique, sol-gel technology was also demonstrated to integrate ceramic thin films in organic packages. A major barrier to synthesis of sol-gel films on copper foils is the process incompatibility of the sol-gel barium titanate with the copper electrodes. To enable process compatibility, process variables like sol pyrolysis temperature and time, and sintering conditions/atmosphere were optimized. Capacitance densities above 1.1F/cm was demonstrated on commercial copper foils with a BDV above 10 V. The two technologies reported in this study can potentially meet midfrequency decoupling requirements of digital systems.     

Ni/Cu电极耐中压MLCC的试制

Ni/Cu电极MLCC具有高可靠性、低成本的特点,但是耐中高压性能较差.本文通过下述设计与改进后的工艺制得耐中压的Ni/Cu电极MLCC:介质叠层40层,介质层厚度为55um,在高温烧结后在40PPM的O2中再氧化3小时,制作出容量为1μF,尺寸为3035规格,温度系数是X7R特性的MLCC产品,该MLCC平均耐电压达到了950V,可以满足500V工作电压的要求.     

Inkjet‐Printed Flexible Gold Electrode Arrays for Bioelectronic Interfaces

Bioelectronic interfaces require electrodes that are mechanically flexible and chemically inert. Flexibility allows pristine electrode contact to skin and tissue, and chemical inertness prevents electrodes from reacting with biological fluids and living tissues. Therefore, flexible gold electrodes are ideal for bioimpedance and biopotential measurements such as bioimpedance tomography, electrocardiography (ECG), electroencephalography (EEG), and electromyography (EMG). However, a manufacturing process to fabricate gold electrode arrays on plastic substrates is still elusive. In this work, a fabrication and low‐temperature sintering (≈200 °C) technique is demonstrated to fabricate gold electrodes. At low‐temperature sintering conditions, lines of different widths demonstrate different sintering speeds. Therefore, the sintering condition is targeted toward the widest feature in the design layout. Manufactured electrodes show minimum feature size of 62 μm and conductivity values of 5 × 10 ⁶ S m^?1. Utilizing the versatility of printing and plastic electronic processes, electrode arrays consisting of 31 electrodes with electrode‐to‐electrode spacing ranging from 2 to 7 mm are fabricated and used for impedance mapping of conformal surfaces at 15 kHz. Overall, the fabrication process of an inkjet‐printed gold electrode array that is electrically reproducible, mechanically robust, and promising for bioimpedance and biopotential measurements is demonstrated.     

Inkjet and microcontact printing of functional materials on foil for the fabrication of pixel-like capacitive vapor microsensors

The work presented demonstrates the utilization of micro-contact printing of self-assembled monolayers (SAMs) of gold nanoparticles (NPs) to pattern the porous thin metallic film composing the top electrode of an ultra-fast capacitive relative humidity sensor based on miniaturized parallel-plates electrodes. The rest of the device, which occupies an area of only 0.0314 mm², is fabricated by inkjet printing stacked individual drops of functional materials, namely gold NPs for the bottom electrode and a polymeric humidity sensing layer, on a polymeric foil. Compared to other printing methods, the use of microcontact printing to pattern the top electrode enables the additive transfer of a solvent-free metallic layer that does not interact chemically with the sensing layer, permitting the thinning of the latter without risk of short-circuits between electrodes, and broadening the range of usable sensing materials for detection of other gases. Thinning the sensing layer yields to ultra-fast response devices with high values of capacitance and sensitivity per surface area. The fabrication process is compatible with low heat-resistant polymeric substrates and scalable to large-area and large-scale fabrication, foreseeing the development of low-cost vapor sensing sheets with high space–time resolution, where every sensor would correspond to a pixel of a large array.     

Analysis and performance of a light-sensitive capacitor

A comprehensive study has been made of a duo-dielectric capacitor in which one of the dielectrics is photoconducting and the other inert. Under dark conditions, device capacitance per unit area is set by the respective dielectric coefficients, conductivities, and thicknesses. Illumination causes device capacitance to change, and decreases the interfacial polarization relaxation time. Analysis reveals the means to optimize device performance, and the existence of a light-dark capacitance ratio-cutoff frequency limitation. A fabricated unit, utilizing CdS with BaTiO3, exhibited a capacitance change of 2500 times and a frequency span extending to 0.22 Mc/s. A CdS:silicone plastic unit showed a maximum capacitance change of 20 times and a frequency span of ∼10 Mc/s, but had degraded dark performance attributed to electron traps, and an interesting piezo-electric resonance that affected both capacitance and dissipation factor at 0.315 Mc/s. Applications of this type of a light-sensitive capacitor are limited to specialized situations where a maximizing dissipation factor and a varying frequency bandwidth can be tolerated.     

A Multiscale Description of the Electronic Transport within the Hierarchical Architecture of a Composite Electrode for Lithium Batteries

The broadband dielectric spectroscopy technique is applied, for the first time, to a composite material used as an electrode for lithium battery. The electrical properties (permittivity and conductivity) are measured from low (a few Hz) to microwave (a few GHz) frequencies. The results demonstrate that the broadband dielectric spectroscopy technique is very sensitive to the different scales of the electrode architecture involved in electronic transport, from interatomic distances to macroscopic sizes, as well as to the morphology at these scales, coarse or fine distribution of the constituents. This work opens up new prospects for a more fundamental understanding and more rational optimization of the electronic transport in composite electrodes for lithium batteries and other electrochemical energy storage technologies (including other batteries, supercapacitors, low‐ and medium‐temperature fuel cells), electrochemical sensors and conductor–insulator composite materials.