退火对Ni/3C-SiC欧姆接触的影响

采用溅射法在液相外延 3 C-Si C上制备 Ni电极 ,并利用圆形传输线法研究了退火温度对欧姆接触特性的影响 ,实验表明对于 Ni/n-Si C金半接触 ,经过 80 0～ 1 0 0 0°C高温退火 5分钟后 ,肖特基整流特性退化为欧姆接触 ,表现出良好的欧姆接触特性 ,且随退火温度的提高 ,接触电阻进一步下降 ,1 0 0 0°C退火后 ,可获得最低的接触电阻为 5 .0× 1 0 - 5Ω· cm2。     

Si上外延的n型3C-SiC欧姆接触研究

用LPCVD在Si(111)上异质外延了n型3C-SiC,并在所外延的3C-SiC上蒸发Au/Ti,通过不同温度下的RTA(快速热退火)形成欧姆接触。用两种不同的传输线模型对Ti/3C-SiC欧姆接触的ρc(比接触电阻率)进行测量,在750°C退火后Ti/3C-SiC的ρc达到了最低值为3.68×10-5Ω·cm2,这满足了应用的要求。AES分析结果还表明由于Ti的氧化,更高温度下的退火会使ρc增大。     

Ohmic contacts to single-crystalline 3C-SiC films for extreme-environment MEMS applications

This paper describes the ohmic contacts to single-crystalline 3C-SiC thin films heteroepitaxially grown on Si (0 0 1) wafers. In this work, a TiW (titanium-tungsten) film was deposited as a contact material by RF magnetron sputter and annealed through the vacuum and rapid thermal anneal (RTA) process. Contact resistivity between the TiW film and the n-type 3C-SiC substrate was measured by the circular transmission line model (C-TLM) method. The contact phases and interface of the TiW/3C-SiC were evaluated with X-ray diffraction (XRD), scanning electron microscope (SEM) and Auger electron spectroscopy (AES) depth-profiles. The TiW film annealed at 1000 °C for 45 s with the RTA plays an important role in the formation of ohmic contact with the 3C-SiC film and the contact resistance is less than 4.62×10⁻⁴ Ω cm². Moreover, the inter-diffusion at the TiW/3C-SiC interface was not generated during, before and after annealing, and was kept in a stable state. Therefore, the ohmic contact formation technology of single-crystalline 3C-SiC films by using the TiW film is very suitable for high-temperature micro-electro-mechanical system (MEMS) applications.     

化学沉积电极与BaTiO3系PTCR半导瓷的欧姆接触

研究了在BaTiO3系PTCR半导体陶瓷上化学沉积镍和铜电极的接触电阻及稳定性，并与烧渗Ag-Zn、烧渗Al电极进行了比较。根据实验结果，用量子力学从理论上讨论了欧姆接触的可能模型，提出场发射是金属－半导体陶瓷形成欧姆接触的机理之一。陶瓷表面经过处理后，元件的电性能要发生一些变化，但不会恶化陶瓷的体性能。     

p-GaN Ni/Au 电极退火后NiO的除去

The Ni/Au contact was treated with oxalic acid after annealing in 02 ambient, and its 1-V characteristic showed the property of contact has been obviously improved. An Auger electron spectroscopy （AES） depth profile of the contact as-annealed showed that the top layer was highly resistive NiO, while an X-ray photo-electron spectroscopy （XPS） of oxalic acid treated samples indicated that the NiO has been removed effectively. A scanning electron microscope （SEM） was used to observe the surface morphology of the contacts, and it was found that the lacunaris surface right after annealing became quite smooth with lots of small Au exposed areas after oxalic acid treatment. When the test probe or the subsequently deposited Ti/Au was directly in contact with these small Au areas, they worked as low resistive current paths and thus decrease the specific contact resistance.     

NiO removal of Ni/Au Ohmic contact to p-GaN after annealing

The Ni/Au contact was treated with oxalic acid after annealing in O2 ambient, and its I-V characteristic showed the property of contact has been obviously improved. An Auger electron spectroscopy (AES) depth pro-file of the contact as-annealed showed that the top layer was highly resistive NiO, while an X-ray photo-electron spectroscopy (XPS) of oxalic acid treated samples indicated that the NiO has been removed effectively. A scanning electron microscope (SEM) was used to observe the surface morphology of the contacts, and it was found that the lacunaris surface right after annealing became quite smooth with lots of small Au exposed areas after oxalic acid treatment. When the test probe or the subsequently deposited Ti/Au was directly in contact with these small Au areas, they worked as low resistive current paths and thus decrease the specific contact resistance.     

抛光液中各组分对Co CMP性能的影响

钴(Co)的化学机械抛光(CMP)要求有较高的去除速率(大于100 nm/min)和洁净平整的表面。采用新型弱碱性抛光液,研究不同成分(如过氧化氢(H₂O₂)、1,2,4-三氮唑(TAZ)、异辛醇聚氧乙烯醚(JFCE))对Co CMP性能的影响。结果表明,抛光液中H₂O₂体积分数为0.4%、pH值为8、甘氨酸(GLY)浓度为0.266 mol/L时,Co的去除速率最大,为763.53 nm/min。为了缓解Co表面的化学腐蚀,加入0.022 mol/L的TAZ作为抑制剂和体积分数为1.3%的JFCE作为表面活性剂后,Co的去除速率得到有效抑制,为489.74 nm/min。对抛光前后的Co表面进行原子力显微镜(AFM)测试,结果表明,Co表面湿润性增加,表面粗糙度明显下降。研究结果对Co布线的工业应用具有一定的指导意义。     

Ti/Al/Ni/Au在GaN N面上的欧姆接触

以Ti/Al/Ni/Au作为欧姆接触金属体系,通过电感耦合等离子体(ICP)刻蚀的预处理,在氢化物气相外延法生长的单晶氮化镓(GaN)材料的N面实现了良好的欧姆接触,其比接触电阻率为3.7×10-4 Ω·cm2.通过扫描电子显微镜、原子力显微镜、阴极荧光和光致发光谱对GaN N面的表面、光学特性进行了对比表征.结果表明:未刻蚀GaN衬底的N面表面存在一定的损伤层,导致近表面处含有大量缺陷,不利于欧姆接触的形成;而ICP刻蚀处理有效地去除了损伤层.X射线光电子能谱(XPS)分析显示刻蚀后样品的Ga 3d结合能比未刻蚀样品向高能方向移动了约0.3 eV,其肖特基势垒则相应降低,有利于欧姆接触的形成.同时对Fe掺杂半绝缘GaN的N面也进行了刻蚀处理,同样实现了良好的Ti/Al/Ni/Au欧姆接触,其比接触电阻率为0.12 Ω·cm2.     

Surface planarization of ZnO thin film for optoelectronic applications

In this paper, surface morphology and optical properties are investigated to find the optimum microstructure of zinc oxide (ZnO) thin films deposited by radio frequency (RF) magnetron sputtering. To achieve a high transmittance and a low resistivity, we examined various film deposition conditions. The transmittance and surface morphology of ZnO thin films were measured by an ultraviolet (UV)-visible spectrometer and atomic force microscopy (AFM), respectively. In order to improve the surface quality of ZnO thin films, we performed chemical mechanical polishing (CMP) by change of process parameters, and compared the optical properties of polished ZnO thin films. As an experimental result, we were able to obtain good uniformity and improved transmittance efficiency by the CMP technique.     

化学机械抛光对铜互连器件的影响及失效分析

探讨了Cu化学机械抛光(CMP)工艺引起Cu互连器件失效的原因以及对可靠性的影响,对Cu CMP工艺缺陷导致器件失效的案例进行分析.由于CMP的技术特点,不可避免地会产生一些工艺缺陷和工艺误差,从而引起器件失效.必须根据标准要求,出厂或封装前对圆片进行芯片功能参数测试和严格的镜检,以便在封装前剔除存在潜在工艺缺陷的芯片,达到既定可靠性要求.     

Polishing behaviors of single crystalline ceria abrasives on silicon dioxide and silicon nitride CMP

The effects of single crystalline ceria (CeO₂) abrasives in chemical mechanical polishing (CMP) slurries were investigated for silicon dioxide (SiO₂) and silicon nitride (Si₃N₄) CMP process. The size of ceria abrasives was controlled by varying hydrothermal reaction conditions. Polishing removal rate was measured with four slurries, with different mean primary particle size of 62, 116, 163 and 232 nm. The polishing results showed that the single crystalline ceria abrasives were not easily broken-down by mechanical force during CMP process. It was found that the removal rate of oxide and nitride film strongly depend upon abrasive size, whereas the surface uniformity deteriorates as abrasive size increases. The observed polishing results confirmed that there exists an optimum abrasive size (163 nm) for maximum removal selectivity between oxide and nitride films. The polishing behavior of the single crystalline ceria abrasives was discussed in terms of morphological properties of the abrasive particle.     

Preparation of silica/ceria nano composite abrasive and its CMP behavior on hard disk substrate

A novel silica/ceria nano composite abrasive was synthesized by homogeneous precipitation using carbamide, ammonium ceric nitrate and silica. The abrasive was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and scanning electron microscopy (SEM), respectively. Then, the chemical mechanical polishing performances of the composite abrasive on hard disk substrate with nickel-phosphorous plated were investigated. Atomic force microscopy images show that the prepared abrasive gives much lower topographical variations than before polishing. The average waviness (Wa) of the polished hard substrate surface can be reduced from 15.5 Å before polishing to 8.36 Å, and the average of roughness (Ra) can be reduced from 14 Å before polishing to 4.80 Å.     

Evolution of surface morphology of alloyed AuGe/Ni/Au ohmic contacts to GaAs microwave FETs

During post-deposition alloying of AuGe/Ni/Au ohmic contacts to microwave transistors, there is interdiffusion of alloy materials and GaAs into each other. Outdiffusion from substrate greatly influences the surface roughness of the contacts as a function of alloying temperature. During our experiments, we have observed that the RMS roughness of the contact surface followed the trend of contact resistance with alloying temperature. We seek to explain this evolution of surface morphology using a model involving the phenomena of coalescence and outdiffusion occurring simultaneously.     

碱性抛光液对硬盘基板抛光中表面状况的影响

阐述了化学机械抛光(CMP)技术在硬盘基板加工中发挥的重要作用,介绍了SiO2碱性抛光液的化学机械抛光机理以及抛光液在化学机械抛光中发挥的重要作用。使用河北工业大学研制的SiO2碱性抛光液对硬盘基板表面抛光,分析研究了抛光液中的浓度、表面活性剂以及去除量对抛光后硬盘基板表面状况的影响机理。总结了硬盘基板表面粗糙度随抛光液中的浓度、表面活性剂及去除量的变化规律以及抛光液的这些参数如何影响到硬盘基板的表面状况。在总结和分析这些规律的基础上,对抛光结果进行了检测。经检测得出,改善抛光后的硬盘基板表面质量(Ra=0.3926nm,Rrms=0.4953nm)取得了显著效果。     

新型碱性抛光液对300mm TaN镀膜片CMP效果评估

TaN由于其良好的性能广泛用于布线铜与介质之间的阻挡层和黏附层.在对直径为300 mm的TaN镀膜片进行化学机械抛光(CMP)后,对比并分析了两种碱性抛光液对TaN去除速率、片内非均匀性、去除速率选择性和表面粗糙度的影响.结果表明,经过自主研发且不合氧化剂的碱性阻挡层抛光液抛光后,TaN的去除速率为40.1 nm/min,片内非均匀性为3.04％,介质、TaN与Cu的去除速率之比为1.69∶1.26∶1,中心、中间以及边缘的表面粗糙度分别为0.371,0.358和0.366 nm.与商用抛光液抛光结果相比,虽然采用自主研发的抛光液抛光的去除速率低,但片内非均匀性以及选择性均满足商用要求,且抛光后TaN表面粗糙度小,易清洗,无颗粒沾污.综合实验结果表明,自主研发的高性能碱性抛光液对TaN镀膜片具有良好的抛光效果,适合工业生产.     

阴离子对铜化学机械抛光的影响

在化学机械抛光过程中,抛光液的组成对抛光速率和表面质量有重要影响。利用自制抛光液,研究了在过硫酸铵体系抛光液中不同阴离子(硝酸根离子、溴离子、氯离子)对抛光速率的影响;采用动电位极化扫描技术对各抛光液在金属表面的成膜性能进行分析。结果表明,硝酸根离子的加入加快了阳极溶解反应,低浓度硝酸根离子的加入对抛光速率影响的波动性较大,随着浓度的增加抛光速率逐渐趋于初始值;随着氯离子(≥1mmol/L)或溴离子浓度的增加,抛光液的氧化性能降低,抛光速率不断降低;当溴离子浓度为0.1mmol/L时,Icorr值最小,抛光时对金属铜表面腐蚀程度较小。     

抛光液各组分在SiO_2介质CMP中的作用机理分析

介绍了超大规模集成电路中SiO2介质的化学机械抛光机理及抛光液在化学机械抛光中扮演的重要角色。通过单因素实验法,在低压力的实验环境下,着重分析了抛光液中表面活性剂、pH值调节剂、纳米磨料等成分在SiO2介质化学机械抛光中的具体作用及影响机理。最终得出,最优化的实验配比,即当表面活性剂的浓度为30mol/L,pH值为11.30,硅溶胶与去离子水的体积比为2:1时,在保证较低表面粗糙度的同时得到了较高的抛光速率476nm/min。     

Microstructural analysis of the Ge/Pd(Zn) ohmic contact to p-InP

The interfacial microstructural analysis of the Ge/Pd(Zn) ohmic contact to p-InP, based on the solid-phase regrowth principle, is reported. Typical contact resistivities of low 10⁻⁴ to low 10⁻⁵ Ω-cm² can be obtained for this contact scheme annealed at temperatures higher than 400°C. Cross-sectional transmission electron microscopy, energy dispersive x-ray composition mapping, and con-verge beam electron diffraction were utilized in this study for the interfacial microstructure analysis. The solid-phase regrowth process has been confirmed in this contact system on InP. Precipitates of trapped materials during solid phase regrowth have also been observed. The correlation between the electrical and microstructural properties is addressed.     

Effect of multistep annealing on mechanical and surface properties of electroplated Cu thin films

Electroplated (EP) Cu films demonstrate a microstructural transition at room temperature, known as self-annealing, that involves grain growth and texture changes. In this paper, we have investigated the annealing behavior of EP Cu films grown on a Cu seed layer deposited on top of a TaN barrier layer. A grazing incident x-ray diffraction (GIXRD) pattern shows stronger x-ray reflections form Cu (111) and (220) planes but weaker reflections from (200), (311), and (222) planes in all the EP Cu samples. Nanoindentation was performed on all the samples using the continuous stiffness measurement technique. The elastic modulus varied from 121 GPa to 132 GPa, while the hardness varied from 1 GPa to 1.3 GPa, depending on the annealing conditions. The surface morphology and roughness of the Cu films were characterized using atomic force microscopy (AFM). The tribological properties of the copper films were measured using the Bench Top chemical mechanical polishing (CMP) tester (CETR, Inc., Campbell, CA). Nanoindentation was performed on the samples after CMP, and an increase in hardness and modulus was observed. This may be attributed to the work hardening of the Cu films during CMP.     

Au/Pt/AuGe/Ni中Pt扩散阻挡层对n-GaAs欧姆接触的影响

The multi-layer metals of Ni/Au Ge/Pt/Au with a Pt diffusion barrier layer of ohmic contact to n-GaAs were studied. The surface morphology and ohmic contact resistivity of multi-layer metals were characterized, with and without the Pt diffusion barrier layer for comparison. The SEM and EDS measurements show the Pt diffusion barrier layer can block the interdiffusion of atoms in multi-layer metals, and improve the surface morphology.The TLM results show that the samples with a Pt diffusion barrier layer have uniform ohmic contact resistance,indicating that the Pt diffusion barrier layer can increase the repetition and uniformity of ohmic contact to n-GaAs,and improve the thermal stability and reliability of GaAs-based devices.