Ti/Al/Ni/Au金属体系在N-polar GaN上的欧姆接触特性

利用金属有机化合物化学气相淀积(MOCVD)在SiC衬底上外延生长了N-polar GaN材料,采用传输线模型(TLM)分析了Ti/Al/Ni/Au金属体系在N-polar GaN上的欧姆接触特性.结果表明,Ti/Al/Ni/Au (20/60/10/50 nm)在N-polar GaN上可形成比接触电阻率为2.2×10-3Ω·cm2的非合金欧姆接触,当退火温度升至200℃,比接触电阻率降为1.44×10-3 Ω·cm2,随着退火温度的进一步上升,Ga原子外逸导致欧姆接触退化为肖特基接触.     

用于紫外探测器的AlGaN/GaN异质结构的Ti/Al/Ni/Au欧姆接触特性

采用Ti/Al/Ni/Au多层金属体系在Al0.27Ga0.73N/GaN异质结构上制备了欧姆接触.分别采用线性传输线方法(LTLM)和圆形传输线方法(CTLM)对其电阻率进行了测试.当Ti(10nm)/Al(100nm)/Ni(40nm)/Au(100nm)金属体系在650℃高纯N2气氛中退火30s时,测量得到的最小比接触电阻率为1.46×10-5Ω·cm2.并制备了Al0.27Ga0.73N/GaN光导型紫外探测器,通过测试发现探测器的暗电流.电压曲线呈线性分布.实验结果表明在Al0.27 Ga0.73N/GaN异质结构上获得了好的欧姆接触,能够满足制备高性能AlGaN/GaN紫外探测器的要求.     

锌白铜微米掺杂对纳米导电银胶性能的影响

纳米导电银胶因其便捷的使用条件被广泛地应用于芯片封装及电子制造业中,但纳米粒子容易团聚,导致导电银胶的导电性下降。为改善纳米银粒子的分散性,首次选用微米锌白铜颗粒对纳米银片进行掺杂改性,研究了纳米导电银胶中掺杂微米锌白铜颗粒对导电银胶导电性及热性能的影响。分析了不同接触类型的导电通路对纳米导电银胶导电性的影响。实验结果表明,锌白铜颗粒的加入可以改善纳米银片在环氧体系中的分散性,改善导电银胶导电性,当锌白铜添加量占填料质量分数的4%时,导电胶的体积电阻率可达1.68×10~(-4)Ω·cm。且锌白铜的加入有利于提升导电银胶的温度稳定性。当锌白铜添加量占填料质量分数的12%时,导电胶的平均电阻温度系数为0.0045/℃。     

用于紫外探测器的AlGaN/GaN异质结构的Ti/Al/Ni/Au欧姆接触特性

采用Ti/Al/Ni/Au多层金属体系在Al0.27Ga0.73N/GaN异质结构上制备了欧姆接触. 分别采用线性传输线方法(LTLM)和圆形传输线方法(CTLM)对其电阻率进行了测试. 当Ti(10nm)/Al(100nm)/Ni(40nm)/Au(100nm)金属体系在650℃高纯N2气氛中退火30s时,测量得到的最小比接触电阻率为1.46E-5Ω·cm2. 并制备了Al0.27Ga0.73N/GaN光导型紫外探测器,通过测试发现探测器的暗电流-电压曲线呈线性分布. 实验结果表明在Al0.27Ga0.73N/GaN异质结构上获得了好的欧姆接触,能够满足制备高性能AlGaN/GaN紫外探测器的要求.     

不锈钢纤维填充聚丙烯导电塑料的屏蔽效能研究

导电塑料是防止电磁波污染的一种重要防护性功能高分子材料.研究不锈钢纤维填充聚丙烯导电塑料(SS/PP)的制备和影响屏蔽效能(SE)的因素.在30～1500MHz范围内测试,不锈钢纤维(SS)添加量对导电塑料的力学性能和屏蔽效果影响较大.当添加量为3～10v%时,屏蔽效能(SE)为20～30dB;当纤维含量分别为15v%和45v%时,屏蔽效能(SE)可显著提高到40～50dB和55～65dB,但同时加工性能下降,冲击强度降低.     

n型4H-SiC上Ni/Pt和Ti/Pt欧姆接触(英文)

研究了Ni/Pt和Ti/Pt金属在n型4H-SiC上的欧姆接触。在1 020℃退火后,Ni/Pt与n型4H-SiC欧姆接触的比接触电阻为2.2×10-6Ω·cm2。Ti/Pt与n型4H-SiC欧姆接触的比接触电阻为5.4×10-6Ω·cm2,退火温度为1 050℃。虽然Ni的功函数比Ti的功函数高,但是Ni比Ti更容易与n型4H-SiC形成欧姆接触。使用能谱分析仪(EDX)分析了Ni/Pt和Ti/Pt金属与4HSiC接触面的元素,观察到C原子相对于Pt原子的原子数分数随退火温度的变化而不同。实验验证了在n型4H-SiC中退火导致的碳空位起施主作用是有利于欧姆接触形成的主要原因。     

非故意掺杂GaN上Ti/Al/Ni/Au欧姆接触研究

基于圆形传输线模型,研究了背景载流子浓度为71016cm3的非故意掺杂GaN与Ti/Al/Ni/Au多层金属之间欧姆接触的形成。样品在N2气氛中,分别经过温度450,550,700,800,900℃的1 min快速热退火处理后发现,当退火温度高于700℃欧姆接触开始形成,随着温度升高欧姆接触电阻持续下降,在900℃时获得了最低比接触电阻6.6106O·cm2。研究表明,要获得低的欧姆接触电阻,需要Al与Ti发生充分固相反应,并穿透Ti层到达GaN表面;同时,GaN中N外扩散到金属中,在GaN表面产生N空位起施主作用,可提高界面掺杂浓度,从而有助于电子隧穿界面而形成良好欧姆接触。     

含Ni量对Ni/BaTiO3基复合PTC材料的影响

加入金属Ni来降低正压电系数(PTC)陶瓷材料的室温电阻率是目前较可行的方法之一。该文主要研究了金属Ni的加入量对Ni/PTC陶瓷复合材料性能的影响。实验采用固相法制备粉体,样品在还原气氛中烧结,烧成后进行氧化处理。实验结果表明:Ni加入质量分数为5%~10%时,试样的室温电阻率可由不加Ni的试样的119.69Ω.cm降至10~15Ω.cm,升阻比可达102,体现出较好的PTC效应。。     

铝纤维填充工程塑料的制备与屏蔽性能研究

研究铝纤维(AIF)填充型工程塑料(AIF/PC)的制备和屏蔽效能(SE)的影响因素.铝纤维(AIF)轻质、纤维长径比大、接触面积大、搭接与分散好,易形成三维导电网络结构,可获得高的导电性能和电磁屏蔽性能.在30～1 500 MHz范围测试,当铝纤维(AIF)添加量为10 wt％时,屏蔽效能(SE)为28～34 dB;当铝纤维(AIF)添加量为30 wt％和40wt％时,SE分别为36～42 dB和43～57 dB.     

炭黑填充丁苯/天然橡胶的电磁屏蔽性能

研究炭黑分别填充丁苯橡胶和丁苯/天然（50：50）并用橡胶的力学性能、导电性能和电磁屏蔽效能。对比发现,单组分丁苯橡胶体系的硬度、拉伸和撕裂性能均小于丁苯/天然橡胶并用体系。由于炭黑在并用体系中分布偏聚,体系的导电渗流阈值降低,相同炭黑含量时并用体系样品的体电阻率变小,电磁屏蔽效能增大。采用并用橡胶体系是减小复合材料导电渗流阈值,改善其力学性能的有效方法。     

Electromigration effect upon the Zn/Ni and Bi/Ni interfacial reactions

This study investigates the electromigration effect upon the Zn/Ni and Bi/Ni interfacial reactions by using reaction couple techniques. Three phases, β₁-NiZn, γ-Ni₅Zn₂₁, and δ-NiZn₈ formed in the Zn/Ni couples reacted at 150°C and 200°C for 4 h to 360 h, and the reaction layers grow thicker with longer reaction time. Passage of a 300 A/cm² current through the Zn/Ni couples has no significant effect upon the interfacial reaction. There is no noticeable difference in the phase formation and layer thickness of the two kinds of Zn/Ni couples with and without the passage of electric currents. Only NiBi₃ phase was found in the Bi/Ni couples reacted at 150, 170, 185 and 200°C. Passage of a 300 A/cm² electric current through the Bi/Ni couples did not change the phase formation, and growth rates of the NiBi₃ phase in the couples reacted at 185°C and 200°C were not affected by passage of electric currents either. However, growth rate of the NiBi₃ phase was enhanced in the Bi/Ni couples reacted at 150°C and 170°C with the passage of a 300 A/cm² electric current. A mathematical model was proposed to describe the electromigration effect upon the growth of the intermetallic compounds. Physical parameters in the models were determined by optimization based on experimental measurements, and the results indicate that the values of the apparent effective charge of Bi and Ni decreased sharply with increasing temperatures.     

基于Ni/Ag/Pt的P型GaN欧姆接触

提出了新型的Ni/Ag/Pt结构作为具有高光学反射率、低比接触电阻率(SCR)的p-GaN欧姆接触电极。在Ni/Ag/Pt厚度分别为3 nm/120 nm/2 nm的条件下,在500℃、O2气氛中退火3 min,获得了80%的光学反射率(460 nm处)和4.43×10-4Ω.cm2的SCR,样品的表面均方根(RMS)粗糙度约为8nm。俄歇电子能谱(AES)分析表明,Pt很好地改善了Ag基电极退火后的表面形貌,Ni、Ag对形成良好的欧姆接触起了重要的作用。     

Mechanical properties and intermetallic compound formation at the Sn/Ni and Sn-0.7wt.%Cu/Ni joints

The Ni/Sn/Ni and Ni/Sn-0.7wt.%Cu/Ni couples are reacted at 200°C for various lengths of time. The tensile strengths of these annealed specimens are determined at room temperature. In addition, the interfacial reactions and fracture surfaces of the specimens are examined as well. These properties are important for the evaluation of the usage of Sn-0.7wt.%Cu lead-free solders, which has been not available in the literature. Only the Ni₃Sn₄ phase is formed at the Sn/Ni interface, but both the Cu₆Sn₅ and Ni₃Sn₄ phases are formed at the Sn-0.7wt.%Cu/Ni interface. The thickness of the intermetallic compound layers grows, while the joint strength decreases with longer reaction time. With a 1-h reaction at 200°C, the fracture surface is in the solder matrix for both of the two kinds of couples. Shifting toward the compound layer with longer reaction time, the fracture surface is in the Ni₃Sn₄ layer in the Sn/Ni couple and is at the interface between the Cu₆Sn₅ and Ni₃Sn₄ in the Sn-0.7wt.%Cu/Ni after reacting at 200°C for 240 h.     

Au/Ge/Ni ohmic contacts to n-Type InP

The relationship between the electrical properties and microstructure for annealed Au/Ge/Ni contacts to n-type InP, with an initial doping level of 10¹⁷ cm^-3, have been studied. Metal layers were deposited by electron beam evaporation in the following sequence: 25 nm Ni, 50 nm Ge, and 40 nm Au. Annealing was done in a nitrogen atmosphere at 250-400‡C. The onset of ohmic behavior at 325‡C corresponded to the decomposition of a ternary Ni-In-P phase at the InP surface and the subsequent formation of Ni₂P plus Au₁₀In₃, producing a lower barrier height at the InP interface. This reaction was driven by the inward diffusion of Au and outward diffusion of In. Further annealing, up to 400‡C, resulted in a decrease in contact resistance, which corresponded to the formation of NiP and Au₉ln₄ from Ni₂P and Au₁₀In₃,respectively, with some Ge doping of InP also likely. A minimum contact resistance of 10^-7 Ω-cm² was achieved with a 10 s anneal at 400‡C.     

采用Ni/Ti/Ni多层金属在N型4H-SiC衬底改善粘附性和界面的欧姆接触

The Ni/Ti/Ni multilayer ohmic contact properties on a 4H-SiC substrate and improved adhesion with the Ti/Au overlayer have been investigated. The best specific contact resistivity of 3.16 × 10^-5 Ω.cm^2 was obtained at 1050 ℃. Compared with Ni/SiC ohmic contact, the adhesion between Ni/Ti/Ni/SiC and the Ti/Au overlayer was greatly improved and the physical mechanism under this behavior was analyzed by using Raman spectroscopy and X-ray energy dispersive spectroscopy （EDS） measurement. It is shown that a Ti-carbide and Ni-silicide compound exist at the surface and there is no graphitic carbon at the surface of the Ni/Ti/Ni structure by Raman spectroscopy, while a large amount of graphitic carbon appears at the surface of the Ni/SiC structure, which results in its bad adhesion. Moreover, the interface of the Ni/Ti/Ni/SiC is improved compared to the interface of Ni/SiC.     

化学沉镍金漏镀渗金的原因和措施

本文阐述了化学沉镍金工艺渗金和漏镀产生的原因以及预防改善措施。     

封装中无铅焊锡与不锈钢及铁镍的界面反应

文章介绍了Sn、Sn-3.0Ag-0.5Cu(SAC)、Sn-0.7Cu(SC)、Sn-9Zn(SZ)、Sn-58Bi(SB)等五种无铅焊锡与金/镍/不锈钢(Au/Ni/SUS304)与铁-42wt%Ni(Alloy42)基材的界面反应。在不锈钢基材方面:与Sn反应仅生成Ni3Sn4相,与SAC反应初期生成Ni3Sn4相。随反应时间增长则生成(Cu,Ni)6Sn5相且剥离界面;另于界面处则有FeSn2相生成。与SC反应则生成层状(Cu,Ni)6Sn5相,随反应延长产生大规模剥离,并在界面生成FeSn2相。仅有Ni5Zn21相生成于SZ/Au//Ni/SUS304系统。SB/Au//Ni/SUS304系统也仅有Ni3Sn4相生成。在Alloy42基材方面:与纯Sn的界面反应仅生成FeSn2相。SAC焊锡与Alloy42基材反应生成(Fe,Ni,Cu)Sn2相,随反应时间延长该相形态变成连续及块状两层结构。在SC/Alloy42反应系统中仅观察到FeSn2相的生成。仅有(Ni,Fe)5Zn21层生成于SZ/Alloy42系统。与SC/Alloy42系统相似,与SB/Alloy42系统只有FeSn2相的生成,并无其他介金属相的生成。     

Characteristic diode parameters in thermally annealed Ni/p-InP contacts

The Ni/p-InP Schottky diodes（SDs） have been prepared by DC magnetron sputtering deposition. After the diode fabrication, they have been thermally annealed at 700 ℃ for 1 min in N2 atmosphere. Then, the current–voltage characteristics of the annealed and non-annealed（as-deposited） SDs have been measured in the measurement temperature range of 60–400 K with steps of 20 K under dark conditions. After 700 ℃ annealing,an improvement in the ideality factor value has been observed from 60 to 200 K and the barrier height（BH）value approximately has remained unchanged in the measurement temperature range of 200–400 K. The BH of the annealed diode has decreased obeying the double-Gaussian distribution（GD） of the BHs with decreasing measurement temperature from 200 to 60 K. The BH for the as-deposited diode has decreased with decreasing temperature obeying the single-GD over the whole measurement temperature range. An effective Richardson constant value of54:21 A/cm²K² for the as-deposited SD has been obtained from the modified Richardson plot by the single-GD plot, which is in very close agreement with the value of 60 A/K²cm² for p-type InP. The series resistance value of the annealed SD is lower than that of the non-annealed SD at each temperature and approximately has remained unchanged from 140 to 240 K. Thus, it can be said that an improvement in the diode parameters has been observed due to the thermal annealing at 700 ℃ for 1 min in N₂ atmosphere.     

Effect of annealing temperature on Ti/Al/Ni/Au ohmic contacts on undoped AlN films

The Ti/Al/Ni/Au metals were deposited on undoped AlN films by electron beam evaporation. The influence of annealing temperature on the properties of contacts was investigated. When the annealing temperatures were between 800 and 950℃, the AlN-Ti/Al/Ni/Au contacts became ohmic contacts and the resistance decreased with the increase of annealing temperature. A lowest specific contacts resistance of 0.379 Ω·cm² was obtained for the sample annealed at 950℃. In this work, we confirmed that the formation mechanism of ohmic contacts on AlN was due to the formation of Al-Au, Au-Ti and Al-Ni alloys, and reduction of the specific contacts resistance could originate from the formation of Au₂Ti and AlAu₂ alloys. This result provided a possibility for the preparation of AlN-based high-frequency, high-power devices and deep ultraviolet devices.     

影响Ni/Cu电极Y5V MLCC耐焊接热失效的原因

研究了铜电极端浆以及不同的烧端工艺对MLCC耐焊接热的影响。结果表明:选择粒径小且均匀的片状铜粉,可提高MLCC端头的致密性,提升其耐焊接热能力;选用Zn-B-Si作为玻璃体系,对片容的耐焊接热具有明显的改善作用;在端头不被氧化的前提下,烧端工序充足的氧含量对改善耐焊接热具有积极作用。通过以上改进,在实际生产中RSH失效率已由改进前的100×10–6以上降到了5×10–6以下。