二次退火对Au/Ni/Au/Ni/p-AlGaN欧姆接触组织结构的影响

在蓝宝石衬底上,利用金属-有机物化学气相沉 积(MOCVD)方法制备p-i-n结构AlGaN基体,采 用常规工艺制作台面型紫外探测器。电子束蒸发蒸镀Ni/Au/Ni/Au(20nm/20 nm)结构制备 p 电极。经空气中550℃/3min一次退火和N₂气氛中750℃/30s二次退火后得到欧姆接触。利用高分 辨透射电镜(HRTEM)和能谱(EDS)研究不同退火条件下p 电极接触的组织结构演变。结果 表明:一 次退火p电极金属层出现明显扩散,但仍维持初始的分层状态,金属/半导体接触界面产生 厚约4nm 的非晶层;二次退火后,金属电极分层现象和界面非晶层消失。金/半界面结构表现为半共 格关系,界面结 构有序性提高。Ni向外扩散,Au向内扩散,Ga扩散至金属电极,造成界面附近金属层富 集Au、Ga元素,导致p电极欧姆接触的形成。     

Ni层厚度对p-GaN/Ni/Au欧姆接触特性的影响

对p-GaN/Ni/Au欧姆接触特性与Ni金属层厚度之间的相关性进行了对比实验研究,利用XRD衍射结果与表面金相显微分析手段对Ni/Au双层金属电极在合金退火过程中的行为特性进行了细致探讨。分析结果表明:在Ni/Au电极结构中,由双层互扩散机制与NiO氧化反应机理决定,Ni层与Au层之间的厚度比率对p型GaN欧姆接触特性的优劣有重要影响,在Ni、Au层厚度相当时可获得最佳的p型欧姆接触。     

Ni/Au与p-GaN的比接触电阻率测量

通过采用环形传输线方法(CILM),电流-电压(I-V)曲线、表面形貌等方法,研究不同的Ni/Au厚度比和空气气氛下合金退火温度对p型氮化镓欧姆接触特性造成的影响。根据Ni/Au与p型氮化镓欧姆接触的形成机制,采用合适的Ni/Au厚度比及退火温度,得到比接触电阻率(ρc)为1.09×10-5Ω.cm2的Ni/Au-p-GaN电极,并分析了Ni在退火过程中对形成良好的欧姆接触中所起到的作用。     

快速热退火对Au/AuBe/Au与GaP结构的影响

采用金属有机化学气相沉积(MOCVD)制备了GaAs基A1GaInP发光二极管(LED),其中在p-GaP上制作Au/AuBe/Au接触电极,经不同温度快速热退火后,使用扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)和俄歇电子能谱仪(AES)对样品的欧姆接触的界面特性进行了分析和表征.使用光电测试仪对样品的电性能进行了测试.结果表明,随着退火温度的升高,各元素的扩散深度和强度增加,Au表面出现灰色片状聚合物,其主要成分为AuGa和BeO;在490～550℃时,金属层与GaP界面表层Au中含有Ga和Be元素,GaP中含有Au和Be元素;Ga元素扩散至Au层中,Au3Be相分解并形成β-AuGa,金属层物相结构转变成Au与3-AuGa两相的混合.在490～550℃时LED的正向电压保持不变.     

Au/Zn/Au/p-In P欧姆接触的界面研究

研究了离子束溅射制备的Au/Zn/Au/p-InP欧姆接触的界面特性.在480℃退火15s比接触电阻达到最小,为1.4×1 0-5 Ω·cm 2.利用俄歇电子能谱(AES)和X射线光电子能谱(XPS)研究了接触界面的冶金性质.实验结果表明,在室温下InP中的In就可以扩散到接触的表面,退火后可与Au形成合金.退火后,Zn的扩散可以在p-InP表面形成重掺杂层,从而降低接触势垒高度,减小势垒宽度,有助于欧姆接触的形成;在接触与p-InP的界面产生一个P聚集区,同时Au与InP反应生成Au2P3,其P的2p3/2电子的结合能约为129.2 eV.     

重掺杂p型SiC晶片Ni/Al欧姆接触特性

系统研究了Al和Ni/Al两种金属体系在重掺杂p型SiC晶片上的欧姆接触特性和电学性质。利用X射线衍射、扫描电子显微镜和综合物性测量系统对这两种电极表面的微观结构和样品的电学性质进行了表征。结果表明：在真空环境下经过800℃退火后Al电极可呈现出欧姆接触行为,其比接触电阻率为1.98×10^-3Ω·cm²,退火处理后Al电极与SiC在接触界面形成化合物Al₄C₃,有助于提高接触界面稳定性。在Ni/Al复合体系中,当Ni金属层厚度为50 nm时,其比接触电阻率显著降低至4.013×10^-4Ω·cm²。退火后Ni与SiC在接触界面生成的Ni₂Si有利于欧姆接触的形成和降低比接触电阻率。研究结果可为开发液相法生长的p型SiC晶片电子器件提供参考。     

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.     

氧化Au/Ni/p-GaN欧姆接触形成的机理

用卢瑟福背散射(RBS)和同步辐射X射线衍射(XRD)研究了p-GaN上的Ni/Au电极在空气下不同温度合金后的微结构的演化,并揭示这种接触结构的欧姆接触形成机制.研究不同温度下比接触电阻(ρc)的变化,发现从450℃开始Au扩散到GaN的表面在p-GaN上形成外延结构以及O向电极内部扩散反应生成NiO对降低ρc起到了关键的作用.在500℃时,Au的外延结构进一步改善,O进一步向样品内部扩散生成NiO,ρc也达到了最低值.但当合金温度升高到600℃时,金属-半导体界面NiO的大部分或全部向外扩散,从而脱离与p-GaN的接触,使ρc显著升高.     

氧化Au/Ni/p-GaN欧姆接触形成的机理

用卢瑟福背散射（RBS）和同步辐射X射线衍射（XRD）研究了p-GaN上的Ni/Au电极在空气下不同温度合金后的微结构的演化，并揭示这种接触结构的欧姆接触形成机制．研究不同温度下比接触电阻(ρc)的变化，发现从450℃开始Au扩散到GaN的表面在p-GaN上形成外延结构以及O向电极内部扩散反应生成NiO对降低ρc起到了关键的作用．在500℃时，Au的外延结构进一步改善，O进一步向样品内部扩散生成NiO,ρc也达到了最低值．但当合金温度升高到600℃时，金属-半导体界面NiO的大部分或全部向外扩散，从而脱离与p-GaN的接触，使ρc显著升高．     

Au/p-CdZnTe欧姆接触的研究

研究了在60℃下大气中退火不同时间对Au/p-CdZnTe(CZT)欧姆接触特性的影响.通过I-V测试发现,退火2 h时,Au/p-CZT能得到较好的欧姆接触特性.用SEM和XPS进一步分析发现,在2 h退火过程中,Au大量向CZT体表层扩散,作为受主杂质占据Cd位,对CZT体表层进行了p型重掺杂,形成了M-p -p型欧姆接触.Cd、Te在退火过程中几乎未向Au层扩散,Au在扩散过程中未与CZT中的元素形成任何化合物.同时,CZT侧面有27.01%的Te氧化成有钝化作用的TeO2.     

Mechanical reliability of Au and Cu wire bonds to Al, Ni/Au and Ni/Pd/Au capped Cu bond pads

This work is an assessment of the mechanical reliability of Au and Cu ball bonds to Al, Ni/Au and Ni/Pd/Au surfaces in terms of high temperature storage. All systems show very good shear strength after thermal storage for up to 120 days at 150 °C. The Au ball bonds on Al surface show Kirkendall voiding starting from 60 days. This did not decrease their mechanical strength but it is expected to become a reliability issue in the long run. The Cu wire bonds on Al caps show a higher initial strength, much slower intermetallics formation and no Kirkendall voiding. This makes them a potentially better industrial solution. Excellent bond strength was found for Cu- and Au-bonds on Ni/Au and Ni/Pd/Au caps. No intermetallics formation or other microstructural change have been found on these interfaces up to 120 days at 150 °C, which was related to the full solubility of the materials along these interfaces. This result suggests that they can be a successful industrial solution for the next generation of packages.     

Solid-state interfacial reactions at the solder joints employing Au/Pd/Ni and Au/Ni as the surface finish metallizations

A tri-layer of nickel/palladium/gold (Au/Pd/Ni) is a promising candidate to replace the conventional Au/Ni bi-layer as the surface finish metallization for lead-free packaging. A surface finish metallization (Au/Pd/Ni or Au/Ni) and a Sn layer are sequentially deposited on a Cu substrate and then are subjected to thermal aging at 150 and 200 °C to investigate the interfacial reactions in the stacking multilayer structure made by low-temperature solid-state bonding. Because of the absence of the reflow process, the Pd and Au layers do not dissolve in the Sn matrix but remain at the interface and participate in the interfacial reaction to form the (Pd,Ni,Au)Sn₄ and (Au,Ni)Sn₄ phases at the Au/Pd/Ni- and Au/Ni-based interfaces, respectively. Though the Pd layer was only 0.4 μm, its resulting (Pd,Ni,Au)Sn₄ phase is much thicker than the (Au,Ni)Sn₄ phase. These two intermetallic compounds exhibit very different microstructural evolution which significantly affects the interfacial microstructures and growth rate of other intermetallic compound formed at the same interfaces.     

Atmospheric corrosion resistance of electroplated Ni/Ni–P/Au electronic contacts

Atmospheric corrosion has vast consequences on the reliability of electronic connectors. This study determined the corrosion resistance of Ni/Ni–P plating metallurgy as a function of plating current density and plating thickness. Discrepancy was observed in the neutral salt spray (NSS) and mixed flowing gas (MFG) tests. Thicker Ni–P deposits displayed superior corrosion resistance in MFG tests while thinner Ni–P deposits performed better in NSS tests. This disparity was attributed to the intrinsic corrosion susceptibility of Ni–P against chlorine or sulfur assisted corrosion. Corrosion products were analysed for better understanding of the corrosion mechanism. NSS test produced green corrosion residues consisting of CuCl (nantokite) and CuCl₂(OH)₃ (clinoatacamite) and brown residues consisting of Cu₂O (cuprite). MFG test produced sulfides of copper (major) and nickel (minor).     

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.     

Ni/Pd/Au镀层的键合可靠性

研究了陶瓷外壳不同厚度Ni/Pd/Au镀层的键合可靠性,并分析了金丝球焊、硅铝丝楔焊和粗铝丝楔焊经300℃不同时间贮存后键合强度变化及键合失效模式变化,并与Ni/Au镀层键合进行了对比。研究结果表明,随着Au层厚度的增加,相同键合参数、相同镀层的金丝球焊的键合强度一致性有明显提升,随高温贮存时间增加,Ni/Pd/Au镀层的金丝键合强度一致性变差;相同实验条件下、不同镀层外壳的硅铝丝键合强度基本一致,300℃、1 h贮存后硅铝丝键合强度降低,随着高温贮存时间的增加,硅铝丝键合强度变化不大;随Au层厚度的增加,粗铝丝楔焊键合强度一致性变差,且失效模式主要为键合点脱落。     

Au/Pt/Ti/Ni ohmic contacts to p-ZnTe

Ohmic contacts of Au/Pd/Ti/Ni to p-ZnTe show a minimum specific contact resistance of 10^-6 Ωcm² for a p-type doping level of 3×10¹⁹ cm^-3 and at an annealing temperature of 300°C. The Ni and Ti layers are very effective in improving the electrical properties of these contact     

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。     

p型GaN的Ni/Au合金电极的I-V特性

运用传输线方法(TLM)测量了p型GaN合金后的Ni/Au电极的接触电阻率和电流-电压(I-V)关系,推导了合金的Ni/Au电极和p型GaN接触处的电流密度与电压(J-V)的关系.在考虑热发射机制和镜像力的基础上,通过对p型GaN的Ni/Au合金电极的I-V特性分析,进一步得出势垒高Φb=0.41eV,受主浓度Na=4×1019cm-3,能带弯曲Vi=0.26V,和EF-Ev:0.15eV.这些结果与理论值和其他实验结果符合得很好.     

p型GaN的Ni/Au合金电极的I-V特性

运用传输线方法(TLM)测量了p型GaN合金后的Ni/Au电极的接触电阻率和电流-电压(I-V)关系,推导了合金的Ni/Au电极和p型GaN接触处的电流密度与电压(J-V)的关系.在考虑热发射机制和镜像力的基础上,通过对p型GaN的Ni/Au合金电极的I-V特性分析,进一步得出势垒高Φb=0.41eV,受主浓度Na=4×1019cm-3,能带弯曲Vi=0.26V,和EF-Ev:0.15eV.这些结果与理论值和其他实验结果符合得很好.