Cu互连中V、V-N和V/V-N薄膜的扩散阻挡性能

采用磁控溅射法在Si(100)基板上沉积厚度为50nm的V、V-N和V/V-N扩散阻挡层,并在扩散阻挡层上制备了厚度为300nm的Cu薄膜,最终获得了Cu/V/Si、Cu/V-N/Si和Cu/V/V-N/Si 3种多层薄膜.薄膜样品在300~750℃真空热处理1h后,通过X射线衍射(XRD)仪、扫描电子显微镜(SEM)和四探针电阻测试(FPP)仪对薄膜样品的晶体结构、微观组织形貌和方块电阻进行测试表征,对比分析了V、V-N和V/V-N 3种扩散阻挡层的扩散阻挡性能.实验结果表明:V、V-N和V/V-N扩散阻挡层均能够有效阻挡Cu原子向Si基板的扩散;Cu/V/Si和Cu/V-N/Si薄膜样品分别在600和650℃时能够保持良好的热稳定性;Cu/V/V-N/Si多层薄膜中由于堆栈结构的存在,样品在700℃还具有良好的热稳定性,表明堆栈结构的V/V-N是一种较理想的扩散阻挡层.     

Si/(Ni-Cr合金)/Cu扩散偶950℃相稳定性

在半导体硅片(Si)-扩散阻挡层(Ni-Cr合金)-金属互连材料(Cu)构成的体系中,Si和Ni-Cr合金之间以及Ni-Cr合金和Cu之间各构成一对扩散偶.通过制备扩散偶试样模拟相应的界面反应,实验测定950℃下界面反应产物的表观序列.从热力学的角度,分别对Cr-Ni-Si和Cr-Cu-Ni三元系中Si/(Ni-Cr)和(Ni-Cr)/Cu两个界面进行反应驱动力分析.计算获得的阶段性生成相表观序列与实验测得结果一致.     

梯度α-Ta(N)/TaN扩散阻挡层的微结构与热稳性定

本文提出了一种梯度氮化法制备出低阻、高稳定性的αTa(N)/TaN双层Cu扩散阻挡层,该方法有效地避免了异质元素的引入和高N含量导致的高电阻率.用四点探针(FPP)、X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)进行薄膜电性能和微结构的表征.分析结果表明,梯度氮化工艺能调控金属Ta膜的相结构,从而获得低阻αTa(N)/TaN双层Cu扩散阻挡层结构.高温老化退火的实验结果进一步证明此结构具有高的热稳定性,失效温度高达800 ℃.     

扩散阻挡层对NiCrAlYSi涂层不同条件下热腐蚀行为的影响

利用电弧离子镀技术在DSM11合金基体上制备含或不含扩散阻挡层(diffusion barrier,DB)的Ni Cr Al YSi涂层,对比研究2种涂层在900℃恒温热腐蚀行为和从900℃到室温的循环热腐蚀行为(表面混合盐质量分数为75%Na2SO4+25%K2SO4)。研究结果表明:在恒温热腐蚀条件下,含或不含扩散阻挡层的Ni Cr Al YSi涂层表面主要生成了α-Al2O3和γ/γ′相;腐蚀100 h后,Ni Cr Al YSi涂层出现了较多的Kirkendall孔洞,基体与涂层元素的互扩散明显。Ni Cr Al YSi/DB涂层的扩散阻挡层可有效地抑止基体与涂层的元素互扩散,防护效果比单一Ni Cr Al YSi涂层的效果好。在循环热腐蚀条件下,含或不含扩散阻挡层的Ni Cr Al YSi涂层表面主要生成α-Al2O3、尖晶石、Ti O2和γ/γ′相;腐蚀100 h后,Ni Cr Al YSi涂层内氧化和内硫化现象严重,Ni Cr Al YSi/DB涂层的扩散阻挡层界面易开裂,影响扩散阻挡层的效力,导致涂层体系比单一Ni Cr Al YSi涂层更快失效。     

Be/Cu/HR-1不锈钢扩散连接界面特性

以Cu为中间层材料,采用Greeble1500热模拟试验机对Be/HR-1不锈钢进行扩散连接试验,利用PME Olympus Tokyo光学显微镜、扫描电镜(SEM)、显微硬度计(HV-1000)、X射线衍射仪研究分析了其界面特性.研究表明,Cu层过渡材料能有效阻碍Be和Fe之间的互扩散以及阻挡不锈钢中合金元素Ni、Cr等向铍基体的扩散,从而阻碍了它们之间金属间化合物在扩散区内的形成,但它也带来了新的金属间化合物如Be2Cu;金属间化合物优先沿晶界生成,呈三维网状分布;元素的扩散主要沿晶界进行,且扩散不是各个部位均等的向前推进,也没有单一的金属间化合物薄层形成;试样的断裂位置在Be/Cu界面处.     

SiO2/Ta界面反应及其对Cu扩散的影响

利用磁控溅射方法在表面有SiO2层的Si基层上溅射Ta薄膜，采用X射线光电子能谱研究了SiO2/Ta界面以及Ta5Si3标准样品，并进行计算机谱图拟合分析，实验结果表明在制备态在SiO2/Ta界面处有更稳定的化合物新相Ta5Si3和Ta2O5生成，在采用Ta作阻挡层的ULSI铜互连结构中这些反应产物可能有利于对Cu扩散的阻挡。     

门极换向晶闸管(GCT)扩散阻挡层的研究

通过对多种阻挡层特性的分析,选定了熔点高、化学稳定性好、电阻率低的TiN薄膜作为门极换向晶闸管阳极的阻挡层.采用磁控溅射技术生长的TiN,经俄歇电子谱仪分析表明,TiN阻挡层系统能有效地阻挡硅和铝的相互扩散,可作为门极换向晶闸管阳极理想的阻挡层材料.     

铝钎焊接头中Cu的腐蚀与扩散行为

应用X射线衍射仪、扫描电镜和能谱分析仪 ,研究了Al Si Cu钎料中Cu在真空钎焊接头中的腐蚀与扩散行为 .研究结果表明 ,真空钎焊后的接头仍然存在腐蚀问题 ,如点蚀和晶间腐蚀等 ,并且随着w(Cu)的增加腐蚀加重 .Cu在钎焊接头中以晶界扩散为主 ,且晶界扩散比晶内扩散快 .     

强磁场对半无限Al/Cu固液扩散偶凝固组织的影响

采用半无限Al/Cu扩散偶法,对磁场下Al-Cu合金凝固组织进行研究.结果表明:由于沿扩散方向Cu原子分数逐渐减小,凝固时,沿凝固方向依次生成α-Al胞/枝状晶等组织、Al-Al2Cu共晶组织和Al2Cu过共晶组织;在不同磁感应强度下(0～12 T),各组织发生了明显变化,胞状晶消失,枝晶粗化并发生偏转;共晶组织层间距与磁感应强度呈非线性关系,组织被扭曲;过共晶组织界面形貌变平整;Cu原子扩散距离缩短.利用XRD对α-Al枝晶区进行衍射分析,发现磁场下α-Al(100)晶面峰值强度变弱,(111)晶面变强.理论分析认为,强磁场对熔体流动的抑制作用和磁场下晶体的磁各向异性是导致上述现象的主要原因...     

Cr,Mo对Cu/Si(100)薄膜体系结构、电阻率及扩散性能的影响

利用简易合金靶材在Si(100)基底单靶磁控溅射制备Cu(Cr)、Gu(Mo)薄膜.研究薄膜在300~500℃退火前后的结构、电学及扩散性能的变化.结果表明,Cr、Mo的加入增强了Cu薄膜的(111)织构,且溅射态薄膜电阻率显著增加.真空退火后,Cu(200)和Cu(220)衍射峰增强,但薄膜保持较强的(111)织构.Cu(1.19%Cr)薄膜电阻率随温度升高先减小后增加,400℃退火后电阻率最小,为2.76μΩ.cm,接近纯Cu薄膜(2.55μΩ.cm);而Cu(1.28%Mo)薄膜的电阻率一直呈下降趋势.Cu(1.28%Mo)薄膜在400℃退火30 min后,薄膜与Si基底间的互扩散深度约60 nm,与纯Cu薄膜(约70 nm)相似.而Cu(1.19%Cr)薄膜的互扩散深度较小为30 nm.Cr显著减小了Cu、Si之间的互扩散.这与Cr在薄膜/基体界面处的偏聚有关.     

垃圾填埋场中水泥土屏障对Cu2+的阻滞性能

通过室内模型试验,研究了不同水泥掺量的水泥土防渗屏障和上海老港填埋场的膨润土砂水泥(塑性混凝土)防渗屏障对Cu~(2+)的阻滞效果,并应用数值模拟的方法对Cu~(2+)在防渗屏障中的有效扩散系数进行求解.研究结果表明,随着水泥掺量和屏障厚度的增加,水泥土屏障对金属离子的阻滞效果会逐步提升;Cu~(2+)在水泥土中的有效扩散系数(1×10~(-7)~2.5×10~(-7) cm~2·s~(-1))是在土中的有效扩散系数(9.53×10~(-6)~1.14×10~(-5) cm~2·s~(-1))的1/35~1/100;上海老港填埋场中的塑性混凝土防渗屏障对Cu~(2+)有较好的阻滞效果.     

Cu(111)面上原子扩散势垒的密度泛函理论研究

用密度泛函理论(DFT)结合平板周期模型方法,对Cu在Cu(111)表面fcc洞位、hcp洞位的吸附模型进行了几何优化,并用从fcc洞位到hcp洞位过渡态计算的方法,研究了Cu在Cu(111)表面的扩散势垒.通过对不同基底层数、不同表面弛豫层数、不同覆盖率的比较,得到基底层数为4层、表面弛豫1层、覆盖率为1/4ML(monolayer)时,Cu在Cu(111)表面的扩散势垒和实验结果吻合得较好.在此基础上,计算了Fe、Ni、Co等磁性原子在Cu(111)表面的扩散势垒.     

Excellent mechanical properties and resistance to cavitation erosion for an ultra-low carbon CrMnN stainless steel through quenching and partitioning treatment

The retained austenite content (RAC), the mechanical properties, and the resistance to cavitation erosion (CE) of the 00Cr13Mn8MoN steel after quenching and partitioning (Q&P) processing were investigated. The results show that the Q&P process affected the RAC, which reached the maximum value after partitioning at 400℃ for 10 min. The tensile strength of the steel slightly decreased with increasing partitioning temperature and time. However, the elongation and product of strength and elongation first increased and then decreased. The sample partitioned at 400℃ for 10 min exhibited the optimal property: a strength-ductility of 23.8 GPa·%. The resistance to CE for the 00Cr13Mn8MoN steel treated by the Q&P process was improved due to work hardening, spalling, and cavitation-induced martensitic transformation of the retained austenite.     

Suppressing the formation of SRZ in a Ni-based single crystal superalloy by RuNiAl diffusion barrier

NiAl-based bond coats applied in thermal barrier coating (TBC) systems containing Ru and Pt have been studied in recent years. Interdiffusion between the coatings and the underlying superalloy substrates usually results in degradation of the mechanical properties of the substrates. In this paper, a NiAl/Ru coating was deposited onto a single crystal superalloy DD6 by electroplating and electron beam physical vapor deposition (EB-PVD). Interdiffusion behavior of the NiAl/Ru and NiAl coated specimens at 1100 1 C was comparatively investigated. For the NiAl coated specimen, after 100 h vacuum annealing, beneath the coating there was a 50 mm thickness secondary reaction zone (SRZ) with some needle-like topologically closed pack ed (TCP) phases. However no SRZ was observed in the NiAl/Ru coated specimen. This may be attributed to the RuNiAl that acted as a diffusion barrier to prevent the inward diffusion of Al from the coating and the outward diffusion of refractory elements from the substrate, and hence suppressing the formation of TCP phases and SRZ in the superalloy.     

A diffusion barrier maintains distribution of membrane proteins in polarized neurons

The asymmetric distribution of proteins to distinct domains in the plasma membrane is crucial to the function of many polarized cells. In epithelia, distinct apical and basolateral surfaces are maintained by tight junctions that prevent diffusion of proteins and lipids between the two domains. Polarized neurons maintain axonal and somatodendritic plasma membrane domains without an obvious physical barrier. Indeed, the artificial lipid Dil encounters no diffusion barrier at the presumptive domain boundary, the axon hillock. By measuring the lateral mobility of membrane proteins using optical tweezers, we show here that some membrane proteins exhibit markedly reduced mobility in the initial segment of the axon. Disruption of F-actin and low levels of dimethyl sulphoxide (DMSO) abolish this diffusion barrier and lead to redistribution of membrane markers that had previously been polarized. Immobilization in the initial segment may reflect, at least in part, differential tethering to cytoskeletal components. Therefore, the ability to maintain a polarized distribution of membrane proteins depends on a specialized domain at the initial segment of the axon, which restricts lateral mobility and serves as a new type of diffusion barrier that acts in the absence of cell-cell contact.     

CrN/Cr涂层对Ti22Al26Nb合金的高温防护研究

采用电弧离子镀技术在O相Ti22Al26Nb合金表面镀覆CrN以及CrN/Cr涂层并研究了其在800和900℃空气中的等温氧化行为,结果显示O相钛合金表面施加单一的CrN涂层后,涂层表面在氧化时形成了保护性的氧化膜Cr2O3层,因此合金受到了良好的高温防护,但是涂层和基体合金之间发生了明显的互扩散;在CrN涂层和钛合金基体之间施加纯Cr扩散障层后形成的CrN/Cr涂层,其表面除了象单一CrN涂层那样氧化后形成了一层连续、致密、结合良好的保护性氧化膜Cr2O3层外,还能有效的抑制涂层与基体合金之间的互扩散,此外扩散障Cr层的存在使得靠近其基体的晶粒也出现了长大现象。     

Ag雕塑薄膜生长的阴影效应研究

通过引入阴影效应、层内扩散和层间扩散势能,建立了倾斜沉积条件下金属雕塑薄膜生长的三维动力学蒙特卡罗模型。利用该模型模拟了Ag在倾斜沉积实验条件下的生长过程。模拟结果表明,由于阴影效应的加强,薄膜表面随着沉积角的增加明显变得粗糙并长成纳米柱结构。通过改变不同的沉积角,研究了薄膜表面形貌的变化,并统计分析了表明粗糙度随薄膜高度的变化关系,论证了雕塑薄膜生长过程中阴影效应与扩散效应的影响机制。     

粘接层预氧化对热障涂层TGO生长与抗高温氧化性能的影响

利用预氧化技术在热障涂层(TBC)的陶瓷层/粘接层界面形成致密Al₂O₃层,经过1 100 ℃高温氧化试验,研究了该Al₂O₃层通过抑制氧气扩散,降低热生长氧化物(TGO)生长速率的作用机理,阐明了粘接层预氧化对整体热障涂层氧化行为的影响规律.结果表明:喷涂态(A-TBC)与预氧化(P-TBC)试样的TGO厚度及氧化增重均随氧化时间的延长而增长.但是,P-TBC显著减少了整个过程氧的扩散,有效抑制了氧化初期TGO的急速生长,使得P-TBC能够长期保持有益的TGO结构、降低抛物线氧化速率,并最终提高热障涂层抗高温氧化性能.     

A mechanism for asymmetric segregation of age during yeast budding

Ageing and the mortality that ensues are sustainable for the species only if age is reset in newborns. In budding yeast, buds are made young whereas ageing factors, such as carbonylated proteins and DNA circles, remain confined to the ageing mother cell. The mechanisms of this confinement and their relevance are poorly understood. Here we show that a septin-dependent, lateral diffusion barrier forms in the nuclear envelope and limits the translocation of pre-existing nuclear pores into the bud. The retention of DNA circles within the mother cell depends on the presence of the diffusion barrier and on the anchorage of the circles to pores mediated by the nuclear basket. In accordance with the diffusion barrier ensuring the asymmetric segregation of nuclear age-determinants, the barrier mutant bud6Delta fails to properly reset age in buds. Our data involve septin-dependent diffusion barriers in the confinement of ageing factors to one daughter cell during asymmetric cell division.