热处理对96.5Sn3.5Ag焊点中Cu-Sn合金层的影响

在焊点与铜基之间形成的Ｃｕ－Ｓｎ合金成分对表面安装器件的疲劳寿命起着关键性的作用。本文着重研究了９３．５Ｓｎ３．５Ａｇ（简写为Ｓｎ－Ａｇ）焊料与Ｃｕ基界面间形成的合金层,通过电子扫描显微镜（ＳＥＭ）,Ｘ衍射（ＸＤＡ）及能谱Ｘ射线（ＥＤＸ）等分析发现,在Ｓｎ－Ａｇ与Ｃｕ基界面上存在Ｃｕ６Ｓｎ５及Ｃｕ３Ｓｎ两种合金成分,且随着热处理时间增加,Ｃｕ６Ｓｎ５合金层增厚,并在该处容易出现裂纹而导致焊点强度减弱,从而使焊点产生疲劳失效。     

热处理对96.5Sn3.5Ag焊点中Cu—Sn合金层的影响

在焊点与铜基之间形成的Ｃｕ－Ｓｎ合金成分对表面安装器件的疲劳寿命起着关键性的作用。本文着重研究了９３．５Ｓｎ３．５Ａｇ焊料与Ｃｕ界面间形成的合金层,通过电子扫描显微镜,Ｘ衍射及能谱Ｘ射线等分析发现。     

片式元件焊点的热循环应力应变模拟技术研究

采用ANSYS软件,以0402片式元件焊点为对象,系统探讨了焊点热应变损伤的有限元仿真方法,分析了焊点在热循环过程中的应力应变响应,并基于修正的Coffin-Manson方程,预测了焊点的热疲劳寿命。结果显示:焊点应力集中区域和应变最大区域均位于焊点与PCB焊盘的交界面,基于应变失效原则,推断焊点裂纹将在此界面萌生和扩展,直至失效。指出了焊点有限元热应变损伤模拟技术的不足及未来的研究方向。     

Au／AuGeNi／n－GaAs欧姆接触失效机理的研究

对Ａｕ／ＡｕＧｅＮｉ／ｎ－ＧａＡｓ欧姆接触进行了三种不同的应力试验：（１）高温存储（ＨＴＳ），（２）常温大电流（ＨＣ），（３）高温适当电流。试验结果表明，三种试验均造成了试验后期欧姆接触电阻增大，最后导致欧姆接触失效。ＡＥＳ分析表明，试验后的样品发生了Ｎｉ、Ａｎ和ＧａＡｓ的互扩散。     

BGA封装倒装焊点不同接触面跌落失效的研究

采用自由跌落的试验方法,研究了BGA(球栅阵列)封装自由跌落到不同材质基板后的可靠性,对比分析焊点裂纹产生、扩展直至断裂的机理。对失效封装芯片进行了染色处理,观察BGA封装中焊点的失效位置和焊点内部裂纹的形貌。结果表明,不同接触面上焊球裂纹都经历稳态-扩展-失效的过程,石质接触面上裂纹出现最早,裂纹扩展最快,失效最快,钢质接触面次之,最后是木质接触面。木质接触面的焊点失效模式主要是焊盘失效;钢质和石质接触面的焊点的失效模式以金属间化合物失效为主。比例风险模型(PHM)估计得到的寿命值与试验结果误差较小,能有效预测焊点自由跌落条件下的寿命。     

Au／AuGeNi／n－GaAs欧姆接触失效机理的研究

本文对Ａｕ／ＡｕＧｅＮｉ／ｎ－ＧａＡｓ欧姆接触进行了三种不同的应力试验：（１）高温存储（ＨＴＳ），（２）常温大电流（ＨＣ），（３）高温适当电流。试验结果表明，三种试验均造成了实验后期欧姆接触电阻增大，最后导致欧姆接触失效。ＡＥＳ分析表明，试验后的样品发生了Ｎｉ，Ａｕ和ＧａＡｓ的互扩散。     

添加Sn-Ag对Sn-Bi焊接特性的改善

研究了ｘ４２Ｓｎ５８Ｂｉ－（１－ｘ）９６．５Ｓｎ３．５Ａｇ系中不同组成的焊料。研究表明在４２Ｓｎ５８Ｂｉ（简称ＳＢ）焊料中添加适量的９６．５Ｓｎ３．５Ａｇ（简称ＳＡ）,能改善焊点的焊接温度。通过对焊点切向拉力的测试分析,发现适量的ＳＡ能提高焊点的强度,并在高低温分别为＋１２５℃和－４０℃下进行热冲击１０００次后,其强度减小程度远小于纯的ＳＢ焊料焊点。表明其焊点的机械及疲劳性能都得到了提高。通过透射Ｘ射线及扫描电子显微镜（ＳＥＭ）分析,发现Ｓｎ－Ａｇ的添加可以减少焊点中孔洞的出现。     

温度与振动耦合条件下的电路板级焊点失效模式与疲劳寿命分析

基于正交试验法研究不同温度与振动耦合条件下的板级焊点失效行为与模式,采用L₉（34）混合水平正交表设计了不同温度（T）、加速度功率谱密度（PSD）与频率（V）条件下的加速寿命试验,结果表明三者对焊点可靠性影响程度为T>PSD>V,且温度是影响焊点失效模式的主要因素,随温度的升高,焊点裂纹逐渐从近封装侧的界面金属化合物（IMC）层向钎体内部扩展,焊点失效模式从脆性断裂向韧性断裂演化.基于焊点失效数据分析,发现焊点疲劳寿命对数值与PCB板背侧最大应变范围存在关联关系,并采用多项式拟合的方法建立了焊点疲劳寿命模型,拟合结果显示,该模型能较好的评估温度与振动耦合条件下的焊点寿命,预测精度较高.     

IC芯片凸点的制作与可靠性考核

用多种方法制作了Ａｕ凸点、Ｃｕ／Ａｕ凸点、Ｎｉ／Ａｕ凸点、Ｃｕ／Ｐｂ－Ｓｎ凸点及Ｃ４凸点微型Ａｕ凸点直径为１０μｍ,间距３０μｍ高度５～８μｍ,芯片上微凸点近１０００个,还对各种不同的制作方法进行了研究,并对芯片凸点的可靠性进行了一定的考核,效果良好。文中给出一组试验芯片的Ｃｕ／Ｐｂ－Ｓｎ凸点可靠性考核数据：经１２５℃,１０００ｈ电老化,其接触电阻变化范围为０．１％～０．７％,经－５５℃～＋１２５     

具有热稳定性的Ge／Ni／TiWN／Au与n－GaAs接触性能的研究

采用Ｇｅ／Ｎｉ／ＴｉＷＮ／Ａｕ多层金属化结构与ｎ－ＧａＡｓ的固－固相反应来获得理想的欧姆接触性能。经６００℃热处理可获得７．３×１０￣（－７）Ω·ｃｍ的最小接触电阻率，俄歇能谱分析表明ＴｉＷＮ与Ａｕ之间，以及它们与ＧａＡｓ界面之间的互扩散较小，具有良好的热稳定性。     

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.     

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.     

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.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its