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1.
Nancy L. Michael Choong-Un Kim Qing-Tang Jiang R. A. Augur P. Gillespie 《Journal of Electronic Materials》2002,31(10):1004-1008
This paper reports on two different electromigration-failure mechanisms competing in Cu interconnects. Accelerated electromigration
tests are conducted on identical single-level, 0.25-μm Cu interconnects with SiN or SiCN passivation. The results indicate
that the failure mechanism can vary with the interface condition of the capping layer. The first failure mechanism, seen primarily
in SiN-capped samples, is characterized by extensive interface damage, believed to be a result of failure led by interface
electromigration. In this failure mode, damage initiates at the capping interface but gradually spreads along all interfaces
of the Cu to form an isolated strand. The competing failure mechanism, found in SiCN-capped samples, is characterized by the
formation and growth of a localized void without extensive interface damage. The absence of interface damage, in addition
to the higher activation energy for failure, suggests that the failure occurs at a more localized inhomogeneity than the interface,
such as grain boundaries. While the exact mechanism of how the capping layer suppresses one mechanism and promotes the other
is unknown, this study reveals that the passivation-interface material and condition have a decisive role in determining the
failure mechanism in Cu interconnects. 相似文献
2.
A new model is advanced to account for the evolution of annealing textures in copper and aluminum interconnects based on strain
and surface energies. The interconnects, whether they are conventionally or damascene-process fabricated, are subjected to
stresses during room temperature or elevated temperature annealing, which, in turn, gives rise to strain energies. The strain
energy of a deposit is influenced by its texture and geometry. The annealing texture of an interconnect line is determined
such that its elastic strain and surface energies are minimal. The measured textures in damascene-processed copper interconnects
and a published result of conventionally processed Al-1%Cu interconnects are discussed based on minimization of their strain
and surface energies. 相似文献
3.
Choong-Un Kim Jaeyong Park Nancy Michael Paul Gillespie Rod Augur 《Journal of Electronic Materials》2003,32(10):982-987
This paper presents a study of electron scattering in damascene-processed Cu interconnects. To understand the leading electron-scattering
mechanism responsible for the size effect, Cu interconnects with varying physical widths, 80–750 nm, were made, and their
resistivity characterized as a function of temperature, ranging from liquid He temperature (4.2 K) to 500 K. The resulting
data suggest that surface scattering, contrary to expectations, was not the primary cause of the size effect observed in this
investigation. Surface scattering was found to weaken with decreasing line width. Further analysis leads to the conclusion
that a substantial fraction of the size effect originates from impurity content scaling inversely with width in these samples. 相似文献
4.
《Microelectronics Reliability》2015,55(8):1205-1213
An accurate knowledge of the phenomenon is required to develop a predictive modeling of the electromigration failure. Thus, a hitherto unseen SEM in operando observation method is devised. The test structure with “high density” through silicon vias (TSV) is tested at 623 K with an injected current density of 1 MA/cm2. Regular shots of micrographs inform about the voids nucleation, forced in copper lines above the TSV, and about the scenario of their evolution. A clear relation is established between voids evolution and the one of the electrical resistance. The lack of impact of test conditions on the failure mechanism is demonstrated. Finally, the impact of microstructure on the depletion mechanism is discussed. Grain boundaries are preferential voids nucleation sites and influence the voids evolution. A probable effect of grain size and crystallographic orientation is revealed. 相似文献
5.
本文报道了铜互联体布线在交流电作用下产生的一种新的热疲劳失效行为,通过透射电子显微镜对热疲劳损伤部位的研究,并与纯机械疲劳载荷作用下的铜薄膜损伤行为进行比较,分析了铜互联体热疲劳损伤失效机理。 相似文献
6.
本文根据工业上使用的铜大马士革互连线尺寸建立了三维有限元模型,模拟计算了铜大马士革互连线中对应力诱导形成空洞很关键的静水应力分布,对比分析了不同低k介质、阻挡层材料和互连线深宽比对静水应力的影响。研究结果表明,静水应力受k介质、阻挡层材料和互连线深宽比影响很大,静水应力在铜大马士革互连线中分布不均匀且最大应力出现在互连线表面。 相似文献
7.
This work focuses on numerical modeling of hydrostatic stress,which is critical to the formation of stress-induced voiding(SIV) in copper damascene interconnects.Using three-dimensional finite element analysis, the distribution of hydrostatic stress is examined in copper interconnects and models are based on the samples, which are fabricated in industry.In addition,hydrostatic stress is studied through the influences of different low-k dielectrics,barrier layers and line widths of copper lines,and the results indicate that hydrostatic stress is strongly dependent on these factors.Hydrostatic stress is highly non-uniform throughout the copper structure and the highest tensile hydrostatic stress exists on the top interface of all the copper lines. 相似文献
8.
Daniele Contestable-Gilkes Deepak Ramappa Minseok Oh Sailesh M. Merchant 《Journal of Electronic Materials》2002,31(10):1047-1051
Voids in copper thin films, observed after electroplating, have been linked to seed aging that occurs when a wafer is exposed,
over time, to clean-room ambient. Oxidation of the copper seed surface prevents wetting during subsequent copper electroplating,
leading to voids. Several surface treatments were employed to counteract the seed aging effect, including reduction of the
copper oxide film by hydrogen, reverse plating of the copper surface, and rinsing the wafer surface with electrolyte. Each
treatment was applied to wafers increasingly aged from 2 to 14 days, just prior to electroplating. Results showed a significant
decrease in postelectroplating defects with all three treatments. The reduction of copper oxide by hydrogen exhibited the
most marked results. An increase in surface wetting is shown by a decrease in contact angle measurements and an increase in
film reflectivity for treated versus untreated copper wafers. This study shows that, although the copper surface exhibits
strong aging effects over a short period of time, using proper surface treatments can eliminate such effects and voids. 相似文献
9.
With the miniaturization of ULSI circuits and the associated increase of current density up to several MA/cm2, copper interconnects are facing electromigration issues at the top interface with the dielectric capping layer SiC(N). A promising solution is to insert selectively on top of copper lines a CoWP metallic self-aligned encapsulation layer, deposited using a wet electroless process. We study the impact of this process on electrical line insulation as a function of cap thickness at the 65 nm technology node and we investigate the physical origin of leakage currents. Below a critical thickness, only a slight leakage current increase of less than one decade is observed, remaining within the specification for self-aligned capping layer processes. Above this critical thickness, large leakage currents are generated due to the combined effect of lateral growth and the presence of parasitic redeposited nodules. We show that a simple phenomenological model allows to reproduce the experimental data, to assess quantitatively the contribution of parasitic defects, and to predict that the self-aligned barrier technology should be extendible up to the 32 nm node, provided that a thin cap layer of less than 8 nm is used. 相似文献
10.
Bi-directional current stressing was used for monitoring electromigration (EM) lifetime evolution in 45 nm node interconnects. Experimental results show that an initial bimodal distribution of lifetimes can be modified into a more robust mono-modal distribution. Since the bi-directional tests provide successive void nucleation and void healing phases, the Cu microstructure is thought to evolve once the formed void is filled thanks to EM induced matter displacement. FEM modeling is used to compare the predicted location of void nucleation for given microstructures at the cathode end: a multigrain structure is compared to a perfect bamboo microstructure. Experimental and modeling results let us assume that small grains (<linewidth or via diameter) at the cathode end present a risk of EM induced early fails. Indeed at this location void nucleates and grows nearby the via opening it shortly. On the contrary, the bamboo microstructure is thought to provide more robust lifetime because voids nucleate a few hundred nanometers in the line and grow down reaching the bottom diffusion barrier of the line. This latter case provides larger void size before circuit opening. 相似文献
11.
Jae-Young Cho Hyo-Jong Lee Hyoungbae Kim Jerzy A. Szpunar 《Journal of Electronic Materials》2005,34(5):506-514
Influence of annealing on the textural and microstructural transformation of Cu interconnects having various line widths is
investigated. Two types of annealing steps have been considered here: room temperature over 6 months and 200°C for 10 min.
The texture was determined by x-ray diffraction (XRD) of various cross-sectional profiles after electropolishing, and the
surface, microstructure, and grain boundary character distribution (GBCD) of Cu interconnects were characterized using electron
backscattered diffraction (EBSD) techniques. In order to analyze a relationship between the stress distribution and textural
evolution in the samples, microstresses were calculated with decreasing line widths at 200°C using finite element modeling
(FEM). In this investigation, it was found that the inhomogeneity of stress distribution in Cu interconnects is an important
factor, which is necessary for understanding textural transformation after annealing. A new interpretation of textural evolution
in damascene interconnects lines after annealing is suggested, based on the state of stress and the growth mechanisms of Cu
electrodeposits. 相似文献
12.
Ennis T. Ogawa Ki-Don Lee Hideki Matsuhashi Paul S. Ho Volker A. Blaschke Robert H. Havemann 《Journal of Electronic Materials》2002,31(10):1052-1058
Recent results on up-direction electromigration (EM) studies on Cu dual-damascene (DD) interconnects are presented. The issue
of the DD process and its potential effect on EM reliability is described with special focus on the peculiarities of the DD
interconnect architecture in comparison to the previous subtractively etched Al-based interconnect technology. Experiments
performed on multilink, DD interconnects that highlight EM reliability issues, such as early failure, and the Blech effect
are summarized. 相似文献
13.
The electromigration cumulative percent lifetime probability of dual Damascene Cu/SiLK interconnects was fitted using three, individual lognormal functions where the functional populations were grouped by void growth location determined from focused ion beam failure analysis of all 54 of the stressed structures. The early, first mode failures were characterized by small voids in the bottom of the vias. The intermediate mode failures had voids in the line and via bottom while the late mode failures had voids that formed in the line only. The three, individual lognormal functions provided good fits of the data. Failure mode population separation using comprehensive failure analysis suggested that only the first mode failures should be used in the prediction of the chip design current. 相似文献
14.
This study is devoted to thermomechanical response and modeling of copper thin films and interconnects. The constitutive behavior
of encapsulated copper film is first studied by fitting the experimentally measured stress-temperature curves during thermal
cycling. Significant strain hardening is found to exist. Within the continuum plasticity framework, the measured stress-temperature
response can only be described with a kinematic hardening model. The constitutive model is subsequently used for numerical
thermomechanical modeling of Cu interconnect structures using the finite element method. The numerical analysis uses the generalized
plane strain model for simulating long metal lines embedded within the dielectric above a silicon substrate. Various combinations
of oxide and polymer-based low-k dielectric schemes, with and without thin barrier layers surrounding the Cu line, are considered.
Attention is devoted to the thermal stress and strain fields and their dependency on material properties, geometry, and modeling
details. Salient features are compared with those in traditional aluminum interconnects. Practical implications in the reliability
issues for modern copper/low-k dielectric interconnect systems are discussed. 相似文献
15.
16.
P. Dannberg L. Erdmann A. Krehl C. Wchter A. Bruer 《Materials Science in Semiconductor Processing》2000,3(5-6):437-441
The UV-reaction molding technology enabling for the fabrication of microoptical elements with rectangular, triangular or circular cross-sections (waveguides, prisms, lenses) in optical polymers is described. Multimode waveguide optical interconnects, coupling prisms and holding structures for fibers can be fabricated in one step. A three-dimensional monomode waveguide interconnection module is presented. Stability tests of the microoptical elements are reported. 相似文献
17.
With the reduction of dimensions in interconnect copper lines, metal resistivity is seen to increase. This phenomenon is due to electron scattering on both sidewalls and grain boundaries. To reduce the grain boundary contribution and then resistivity, it becomes important to control microstructure. This paper focuses on the grain growth mechanism in a Damascene architecture. In this architecture, trenches are filled with copper. It is shown that the remaining copper on the top surface - the overburden - plays a key role in the final microstructure in the lines. Electrical results and observations are presented and discussed in terms of overburden grains extension inside the trenches. A method is proposed to quantify this grain extension. 相似文献
18.
19.
Cu互连线显微结构和应力的AFM及SNAM分析 总被引:1,自引:0,他引:1
在ULSI中采用Cu互连线代替Al以增加电子器件的传输速度和提高器件的可靠性,Cu的激活能约为1.2eV,而Al的激活能约为0.7eV,Cu互连线寿命约为Al的3-5倍。Cu大马士革互连线的制备工艺为:在硅衬底上热氧化生成的SiO2上开出凹槽,在凹槽中先后沉积阻挡层Ta和晶种层Cu,然后由电镀的Cu层将凹槽填满,最后采用化学机械抛光将凹槽外多余的Cu研磨掉,Cu互连线的尺寸为:200um长,0.5μm厚,宽度分别为0.35,0.5,1至3μm不等,部分样品分别在200℃,300℃和450℃下经过30min退火。利用原子力显微镜(AFM)和扫描近场声学显微镜(SNAM),同时获得形貌像和声像,分别了Cu大马士革凹槽构造引起的机械应力和沉积引起的热应力对Cu互连线显微结构及可靠性的影响,SNAM是在Topometrix公司AFM基础上建造的实验装置,实验采用的机械振动频率在600Hz-100kHz之间。分析测试结果如下:1.AFM和SNAM可以实现对微米和亚微米特征尺寸的Cu互连线的局域应力分布和显微结构的原位分析。2.采用AFM,TEM、XRD观察和测试了Cu互连线的晶体结构,分析了大马士革凹槽工艺 对Cu晶粒尺寸及取向的影响。平坦的沉积态Cu膜的晶粒尺寸约为100nm;而由大马士革工艺制备的凹槽中的Cu互连线的晶粒尺寸约为70-80nm,凹槽结构抑制了晶粒生长,平坦的沉积态Cu膜有较强的(111)织构;而凹槽中的Cu互连线的(111)织构减弱,(200)和其它的晶体取向分量增强。3.SNAM声阻尼信号对材料局域应力的变化敏感,SNAM声图衬底可显示出局域应力的分布,在沉积态的Cu互连线声图中,金属和SiO2介电层的界面处像衬度强,表明该处为应力较高的区域,而在退火后的Cu互连线的声图中,金属和SiO2介电层的界面处像衬度弱,表明退火后该处应力减小,我们对Cu膜进行了宏观应力的测试,退火后应力值从沉积态的661MPa减少至359Mpa,这与SNAM声成像的结果相符合。 相似文献
20.
R. Fang H. Gu M. J. O'Keefe T. J. O'Keefe W. S. Shih K. D. Leedy R. Cortez 《Journal of Electronic Materials》2001,30(4):349-354
Copper and palladium seed layers have been successfully deposited from organic solutions onto patterned and unpatterned pure
aluminum and Al(0.5%Cu) thin films using an immersion displacement process. The reaction occurs at ambient temperature and
pressure by a spontaneous electrochemical mechanism. Copper and palladium deposition using the organic solution was studied
as a function of reaction time and Cu or Pd concentration in the solution. It was found that both time and the intial ionic
metal concentration significantly influence deposit morphology, particle size and shape, and adherence. Nucleation of Cu or
Pd sub-micron particles on both Al and Al(Cu) surfaces occurred in less than one minute while nucleation density and particle
size increased with longer deposition times. Increasing the copper or palladium concentration in the organic solution resulted
in an increase in the final particle size of the seed crystals. However, an increase in deposition time and metal concentration
in the organic solution caused more extensive dissolution and pitting of the aluminum thin films. The Cu and Pd deposits were
effectively used as catalytic sites for subsequent electroless or electrolytic copper deposition using conventional aqueous
processes. 相似文献