GaAs衬底共面波导S参数标准样片研制

GaAs等固态微波裸芯片电性能测试需要采用探针将共面波导参考面过渡到同轴参考面。设计制作了用于微波探针校准的GaAs衬底的计量级标准样片,包括SOLT 和TRL 校准模块,以及匹配传输线、衰减及驻波等验证模块。提出了平衡电桥结构,兼具衰减驻波标准,带内平坦,且工艺适应性好。经过与国外校准片比对,验证了频率覆盖100 MHz ~50 GHz,驻波比测量范围:1.1,1.5,2.5,5,10;衰减测量范围:-1 dB,-2 dB,-3 dB,-10 dB,-20 dB,-30 dB,-40 dB;匹配负载反射损耗小于-30 dB。同时提取了SOLT校准模块的矢网校准用参数。     

一种基于RF MEMS开关的四端口电子校准件设计

针对射频多端口器件微波测试需求,基于SOLT校准原理设计了一种工作频率在DC~12 GHz范围内、基于RF MEMS开关的四端口电子校准件。数值仿真结果表明,在短路状态下,器件的回波损耗小于0.15 dB;在直通状态下,器件的插入损耗小于0.5 dB,端口之间的隔离度大于20 dB;在开路状态下,器件的回波损耗小于0.3 dB,端口之间的隔离度大于25 dB;同时采用微表面加工工艺,利用磁控溅射工艺对负载电阻进行了制备,其测试结果约为50 Ω,符合设计要求。设计的基于RF MEMS开关的四端口校准件,具有射频性能好、体积小、易于集成等优点,能够满足X波段微波多端口器件在片测试的应用需求。     

一种用于氮化镓晶体管建模的TRL 校准方法

直通-反射-延迟线(TRL)校准相对于短路-开路-负载-直通(SOLT)校准是一种更加准确且易于实现的 校准方法,尤其适用于二端口及多端口的非同轴测量。文中针对Wolfspeed 公司的氮化镓晶体管CGH40010F 的S 参数 测量问题,分析讨论了TRL 校准在网络分析仪中的误差盒模型,在此基础上设计制作了一套TRL 校准件,其工作频率 范围为1~6 GHz,在此频段内直通和延迟线均达到Sii(i =1,2)幅值小于-15 dB,Sij(i,j =1,2;i≠j)幅值大于-0. 8 dB;将 该校准件特性指标内置到矢量网络分析仪中进行校准测试,实测结果表明,经过TRL 校准后的氮化镓晶体管小信号S 参数与官方数据手册中一致,验证了该校准测量方法及据此设计制作的TRL 校准件是有效的。     

一种小型化射频MEMS电子校准件设计

通过短路-开路-负载-直通(SOLT)校准原理与MEMS开关结合,设计了一种小型化多功能电子校准件。仿真结果表明,在0.1~20 GHz频段内,该电子校准件的双端口校准仅需2步;直通状态插入损耗≤0.9 dB,开路状态回波损耗≤0.48 dB,短路状态回波损耗≤0.39 dB。整体尺寸为2.5 mm×1.2 mm×0.8 mm。该MEMS电子校准件体积小,损耗低,成本低,校准准确度高,效率高,适用于毫米波测量和小型智能化校准领域。     

在片LRRM校准件研制及标定

研制了75~110 GHz氧化铝陶瓷衬底在片LRRM校准件,建立了校准件的电路模型。为了实现LRRM校准件高准确度的标定,还研制了多线TRL校准件。通过测量和计算相结合的方式对LRRM校准件中传输线标准的特征阻抗、延时、损耗,反射标准的延时和匹配负载的电阻、电感进行标定。分别采用标定的校准件、研制的多线TRL校准件和商用校准件104-783A对在片S参数测量系统进行校准,测量相同的衰减器和短路标准,结果显示,在75~110 GHz频段传输幅度最大偏差0.07 dB,传输相位最大偏差1.5°,反射幅度最大偏差0.02(线性值),反射相位最大偏差2.9°。     

提取共面微波探针S 参数的方法*

共面微波探针是裸芯片测量信号输入/输出的重要媒介,通过与晶圆片物理接触,建立起测量系统与芯片之间 的信号连接通道。为了获得共面微波探针完整准确的S 参数,设计并实现了“两步法”测量方案,首先在同轴端口进行校准,然 后在探针尖端口进行第二步校准。通过与出厂数据进行对比分析,证明了方案的可行性,同时指出在片校准件预校准的重要 性。另外,讨论了氧化铝和砷化镓两种材料在片SOLT 校准件对于探针S 参数提取中的影响,实验显示二者相角偏差达到 39.8°,回波损耗呈现规则性的变化,全部测量数据的频段覆盖1~40 GHz,最终给出了优化的测量方案。     

毫米波单刀双掷开关的设计与制作

以0.25μm GaAs PHEMT为基础,介绍了微波单片集成电路开关模型的设计、测试及建模过程,并以此平台开展了单刀双掷开关芯片的设计与研制.讨论了PHEMT开关建模的重要性,解决了建模中的关键问题,包括开关的设计、测试系统的校准、模型参数的提取,建立了毫米波范围内高精度的等效电路模型.单刀双掷开关的设计采用了并联式反射型电路拓扑,开关的测试采用了微波探针在片测试系统,在18～30 GHz获得了优异的电性能,插入损耗IL≤1.5 dB,输入/输出驻波比VSWR≤1.5:1,关断状态下的隔离度ISO≥30 dB,芯片尺寸为1.2 m/mm×1.8 mm×0.1 mm.     

MEMS铜基微同轴传输线性能仿真及测试

研究了一种新型的MEMS超宽带铜基微同轴传输系统。设计了特性阻抗为50Ω铜基微同轴传输线结构,其仿真电压驻波比(VSWR)在DC～110 GHz内低于1.15。且设计了可用于探针台测试和芯片金丝键合的地-信号-地(GSG)转接结构,仿真插入损耗低于0.1 dB。采用该微同轴结构和GSG转接结构设计了用于探针台测试的直通-反射-传输线(TRL)校准套件,利用薄膜工艺加工得到了铜基微同轴传输线及校准件实物,通过实验测试得到该微同轴传输线DC～40 GHz最大插入损耗为0.35 dB/cm,通过仿真拟合推算其110 GHz下的插入损耗约为0.65 dB/cm,该插入损耗性能显著优于平面印刷传输线,同时,该微同轴传输线的体积远小于波导传输结构,可以用于研制小型化、高性能、高集成密度微波/毫米波系统。     

MMIC芯片衰减器的设计与检测

本文提供了一种单片微波集成电路(MMIC)芯片衰减器,采用氮化钽薄膜作为电阻材料,利用嵌套掩膜刻蚀技术将芯片衰减器结构一层一层套刻在陶瓷基片上。主要研究了利用氮化钽薄膜电阻制作芯片衰减器的优点,结合HFSS仿真软件,建立3 dB和10 dB芯片衰减器的有限元模型,并对实物产品进行测试验证。试验结果表明:3 dB芯片衰减器在DC～20 GHz工作频率内有较好的衰减响应,回波损耗在整个宽频带内都小于-20 dB,衰减量偏差在DC～12 GHz工作频率内小于±0.3 dB。10 dB芯片衰减器在DC～20 GHz工作频率内也有较好的衰减响应,回波损耗在整个宽频带内都小于-19 dB,衰减量偏差在DC～12 GHz工作频率内小于±0.35 dB。     

共面微波探针在片测试技术研究

本文描述了使用共面微波探针的半导体芯片在片测试技术.设计研制出的多种微波探针性能参数稳定,使用寿命在十万次以上,用于在片检测各种GaAs共面集成电路芯片.触头排列为GSG的微波探针,-3dB带宽及反射损耗分别为14GHz和小于-10dB.     

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.     

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.     

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.     

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.     

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.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.