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1.
Mechanical behavior of thin metallic films has been investigated on aluminum films deposited on a flexible polyimide substrate.
Aluminum thin films exhibit a higher tensile strength than bulk aluminum. As film thickness decreases from 480 to 60 nm tensile
strength increases from 196 to 408 MPa. These mechanical behaviors are correlated with the microstructure and its evolution
with the thickness of aluminum thin films. Films are consisted of fine columnar grains and average grain size increases monotonically
with the film thickness. The volume fraction of (111)-textured grains increases and the dispersion of texture axis becomes
narrow as the film thickens. The relative contributions of the film thickness, grain size, and texture to the strength of
aluminum thin films are estimated using an empirical strengthening model. The result indicates that the high strength of aluminum
thin films is due largely to their small grain size, followed by the strengthening due to the film thickness and texture. 相似文献
2.
Hyeonggeun Yu Ching‐Chang Chung Nate Shewmon Szuheng Ho Joshua H. Carpenter Ryan Larrabee Tianlei Sun Jacob L. Jones Harald Ade Brendan T. O'Connor Franky So 《Advanced functional materials》2017,27(21)
Next‐generation wearable electronics call for flexible nonvolatile devices for ubiquitous data storage. Thus far, only organic ferroelectric materials have shown intrinsic flexibility and processability on plastic substrates. Here, it is shown that by controlling the heating rate, ferroelectric hafnia films can be grown on plastic substrates. The resulting highly flexible capacitor with a film thickness of 30 nm yields a remnant polarization of 10 µC cm?2. Bending tests show that the film ferroelectricity can be retained under a bending radius below 8 mm with up to 1000 bending cycles. The excellent flexibility is due to the extremely thin hafnia film thickness. Using the ferroelectric film as a gate insulator, a low voltage nonvolatile vertical organic transistor is demonstrated on a plastic substrate with an extrapolated date retention time of up to 10 years. 相似文献
3.
Stuart C. Wimbush Meicheng Li Mary E. Vickers Boris Maiorov D. Matt Feldmann Quanxi Jia Judith L. MacManus‐Driscoll 《Advanced functional materials》2009,19(6):835-841
To understand the origin of the increase in critical current density of rare earth barium cuprate superconductor thin films with decreasing thickness, a series of sub‐300‐nm EuBa2Cu3O7?δ thin films deposited on SrTiO3 substrates are studied by X‐ray diffraction and electrical transport measurements. The out‐of‐plane crystallographic mosaic tilt and the out‐of‐plane microstrain both increase with decreasing film thickness. The calculated density of c‐axis threading dislocations matches the extent of the observed low‐field enhancement in critical current density for fields applied parallel to c. The in‐plane mosaic twist and in‐plane microstrain are both around twice the magnitude of the out‐of‐plane values, and both increase with decreasing film thickness. The results are consistent with the observed stronger field enhancement in critical current density for fields applied parallel to ab. The lattice parameter variation with thickness is not as expected from consideration of the biaxial strain with the substrate, indicative of in‐plane microstrain accommodation by oxygen disorder. Collectively, the results point to an enhancement of critical current by interfacial strain induced oxygen disorder which is greatest closest to the film‐substrate interface. The findings of this study have important implications for other thin functional oxide perovskite films and nanostructures where surface and interfacial strains dominate the properties. 相似文献
4.
As a result of the large difference in thermal expansion coefficients between metal and Si, high stresses can develop in thin
metallic films attached to Si substrates in microelectronic devices during thermal excursions experienced in processing steps
or during usage. These stresses may induce plastic deformation of the thin films accompanied by creep and interfacial sliding,
and have a pronounced effect on the reliability of microelectronic devices and components. Even though various methods have
been proposed to study thermal stress, methodologies for studying plastic deformation of thin films are not well established.
Here, we report the results of a study of plastic deformation and interfacial sliding of thin Al and Cu films on Si substrates
during thermal cycling. Cross-sectional profiles of pattern-grown Al and Cu films of nominally 250 nm thickness were measured
before and after thermal cycling by employing an atomic force microscope. Through statistical analysis, the size changes of
the thin films induced by thermal cycling were determined. Finite element (FE) analyses were conducted to compute the stress
and strain states within the thin film and at the interface, and the results were utilized to interpret the atomic force microscopy
(AFM) observations. Experiments revealed that, following thermal cycling, Al films expanded relative to the Si substrate,
whereas Cu films shrank, resulting in an alteration of the film-footprint on the substrate in both cases. Based on the FE
calculations, this was attributed to net inelastic deformation of the thin films via creep and yielding, with the deformation
being accommodated at the interface by diffusion-controlled interfacial sliding. 相似文献
5.
T. Pienkos A. Proszynski D. Chocyk L. Gladyszewski G. Gladyszewski 《Microelectronic Engineering》2003,70(2-4):442-446
This work presents results of stress measurements during deposition of thin silver and copper films on 100 μm Si substrate. The stress in thin films has been determined by means of an optical system for the measurement of sample’s curvature. This system was applied in situ in a high vacuum deposition system. For Ag films the stress occurring during deposition goes from a low compressive value to tensile for thickness less than 30 nm and to compressive above this. For Cu films we observe tensile stress for thickness less 20 nm and above 50 nm. The same general trend of stress evolution with thickness is present in all cases at initial stage. There is the same growth mode for Cu and Ag because of the similar shapes of stress curves for thickness lower than 30 nm The behavior of stress evolution was explained by island nucleation and growth, island coalescence and continuous film growth. The difference in the stress evolution above 30 nm is caused by the fact that silver may be less sensitive than copper to adsorption of impurities. Adsorbed contamination inhibits compressive stress increase generated by grain boundary and defects remaining in the film. 相似文献
6.
Qi Zhang Haomiao Yu Fenggui Zhao Liying Pei Jinpeng Li Kai Wang Bin Hu 《Advanced functional materials》2019,29(35)
Solution‐processing hybrid metal halide perovskites are promising materials for developing flexible thin‐film devices. This work reports the substrate effects on the spin–orbit coupling (SOC) in perovskite films through thermal expansion under thermal annealing. X‐ray diffraction (XRD) measurements show that using a flexible polyethylene naphthalate (PEN) substrate introduces a smaller mechanical strain in perovskite MAPbI3?xClx films, as compared to conventional glass substrates. Interestingly, the linear/circular photoexcitation‐modulated photocurrent studies find that decreasing mechanical strain gives rise to a weaker orbit–orbit interaction toward decreasing the SOC in the MAPbI3?xClx films prepared on flexible PEN substrates relative to rigid glass substrates. Simultaneously, decreasing the mechanical strain causes a reduction in the internal magnetic parameter inside the MAPbI3?xClx films, providing further evidence to show that introducing mechanical strain can affect the SOC in hybrid perovskite films upon using flexible substrates toward developing flexible perovskite thin‐film devices. Furthermore, thermal admittance spectroscopy indicates that the trap states are increased in the perovskite films prepared on flexible PEN substrates as compared to glass substrates. Consequently, PEN and rigid glass substrates lead to shorter and longer photoluminescence lifetimes, respectively. Clearly, these findings provide an insightful understanding on substrate effects on optoelectronic properties in flexible perovskite thin‐film devices. 相似文献
7.
8.
Microcalorimeter based on suspended SiO2 membrane structures has been designed and fabricated. The geometry of suspension arms is optimized by ANSYS simulation to ensure that it provides maximum thermal isolation between the membrane structure and the supporting substrate. The microcalorimeter is intended to be a sample carrier onto which other thin films can be deposited for thermal property measurement. An ac modulation method has been used to measure the specific heat of aluminum thin film with thickness from 13.5 to 370 nm. The measurements demonstrated clearly the dependence of specific heat on thin film thickness. 相似文献
9.
10.
E. A. Irene 《Journal of Electronic Materials》1976,5(3):287-298
The mechanical stress caused by Si3N4 films on (111) oriented Si wafers was studied as a function of the Si3N4 film thickness, deposition rate, deposition temperature and film composition. The Si3N4 films were prepared by the reaction of gaseous SiH4 and NH3 in the temperature range 700–1000°C. The curvature of the Si substrates caused by the Si3N4. films is related to the film stress; the substrate curvature was measured by an optical interference technique. The measured Si3N4. film stress was found to be highly tensile with a magnitude of about 1010 dynes/cm2. For the thickness range of 2000–5000Å, there was no change in the measured stress. The total film stress was observed to decrease for decreasing deposition rate and increasing deposition temperature. A large change in film stress was observed for films containing excess Si; the stress decreased with increasing Si content. Based on published values for the thermal expansion coefficients for Si and Si3N4, a published value for Young’s Modulus for Si3N4, and the measured total stress values, a consistent argument is developed in which the total stress consists of a compressive component due to thermal expansion coefficient mismatch and a larger tensile intrinsic stress component. Both the thermal and intrinsic stress components vary with film deposition temperature in directions which decrease the total room temperature stress for higher deposition temperatures. 相似文献
11.
CdTe thin films were prepared using e-beam evaporation technique. The prepared films were irradiated by Ar+ ions at different fluencies using multipurpose aluminum (Al) probe as in-situ. This could also be used in ion bombardment for cleaning the substrate prior to coating. The as grown and Ar+ ion irradiated films were confirmed to be of polycrystalline nature with X-ray technique. Ar+ ion irradiation enhances the growth of (1 1 1) oriented CdTe crystals and the Cd enrichment on the surface of CdTe thin films. Higher Ar+ ion flux helps to grow (2 2 0) oriented CdTe thin film. A considerable change in structural parameters like crystallite size, lattice parameter, internal strain, etc. could be observed as a result of high Ar+ ion flux. The applied in-plan stress in both as grown and irradiated film was identified to be of tensile nature. The applied stress was observed between 0.016 and 0.067 GPa for all Ar+ ion irradiated samples. As a result of the Ar+ ion irradiation, the in-plan stress varies between 1.38×109 and 5.58×109 dyn/cm2. The observed bad gap was increased for higher Ar+ ion flux. It shows the effect of Ar+ ion irradiation on the modifications of optical properties. The observed results were encouraging on the use of simple multipurpose Al probe for Ar+ ion irradiation process as in-situ. 相似文献
12.
Thin, free standing aluminum and alumina films were produced by physical vapor deposition and tensile properties were measured.
Young’s modulus of the aluminum was microstructure insensitive, but the plastic behavior was very structure sensitive. The
natural surface oxide of the aluminum had no apparent affect on the measured value ofYoung’s modulus. The alumina films showed
true brittle behavior, but Young’s modulus was lower than bulk. Impurities residing at the grain boundaries were observed
in the aluminum films using transverse Auger electron spectroscopy (AES). The films were well characterized using AES, transmission
electron microscopy, Rutherford backscattering spectroscopy, and secondary electron microscopy. Well characterized, thin three-layered
aluminum/alumina compositionally modulated films were produced by alternate depositions and tensile properties were measured.
Young’s modulus was found to be less than a weighted thickness average of Young’s modulus of the individual constituents.
Otherwise, the mechanical measurements yielded typical bulk behavior. 相似文献
13.
The gold ball bonding process is widely used for making interconnections between integrated circuit chips and package lead
frames, yet the relationships between the wire/substrate materials properties and the bond formation processes are not yet
well understood. While the creation of a metallurgical bond at the interface between the wire and substrate is required, the
deformation of the wire and substrate also play an important role in bond formation. Bonding to thin film substrates is of
particular interest, since thin films often exhibit mechanical behavior distinctly different from bulk materials. In the present
study, a systematic investigation has been conducted to understand the effects of the structure and properties of aluminum
thin films on the quality of gold ball bonds. A series of aluminum thin films was fabricated with systematic variations in
hardness, roughness, thickness, and composition. Gold wires were ball bonded to these substrates, and the bondability and
bond shear strengths were assessed. Metallographic sections of several of these specimens were made and examined in the scanning
electron microscope. The results show that the film thickness has the most dominant effect on the bondability and bond strength;
films that were 0.5 μm thick often exhibited low strength or poor bondability. Very hard films also gave poor results. Ultimately,
these results can be used to predict the wire bond reliability expected from various types of thin film metallization. 相似文献
14.
Douglas I. Kushner Ahmet Kusoglu Nikolas J. Podraza Michael A. Hickner 《Advanced functional materials》2019,29(37)
The effects of film thickness and substrate composition on the ionomer structure in porous electrodes are critical in understanding pathways toward developing higher performance electrochemical devices, including fuel cells and batteries. Insights are gained into the molecular and nanostructural orientation dependence for thin Nafion films (12–300 nm thick) on gold, platinum, and SiO2 model substrates. Molecular orientation is determined from the birefringence measured using spectroscopic ellipsometry, while the nanostructural orientation of the ionic domains is measured using grazing‐incidence small‐angle X‐ray scattering. Density functional theory calculations for the molecular polarizability of the Nafion backbone and side chain show complimentary contributions to the measured birefringence values for the material. Nafion films prepared on SiO2 substrates exhibit a nearly isotropic molecular and nanostructural orientation. Films on gold and platinum display parallel backbone orientations, relative to the substrate, with decreasing film thickness. However, a birefringence transition toward molecular isotropy is observed for 30 nm thick films on Au and Pt; while the ionic nanostructured domains continuously align parallel to the substrate. This apparent isotropic molecular orientation with increasing domain orientation highlights the difference between the backbone and side chain orientation, a key finding for elucidating transport in confined films at the interfaces. 相似文献
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16.
为了获得具有一定厚度的四面体非晶碳薄膜,利用过滤阴极真空电弧(FCVA)沉积技术,通过交替改变衬底偏压的方法制备了多层四面体非晶碳(ta?鄄C)薄膜。多层膜由富sp2子膜层Ai与富sp3子膜层Bi交替组成(i=1,2,3),各子膜层厚度比dAi/dBi约为1.0,总的膜厚约为1 m。根据Stoney公式计算多层膜的各子膜层压应力呈交替起伏变化。多层四面体非晶碳膜在500 ℃以下的真空退火处理后,可见光Raman谱表明,多层膜的富sp3杂化结构基本保持不变,纳米压痕测量的薄膜硬度与杨氏模量略微增加,纳米划擦实验表明,多层膜具有优良的耐磨性与附着性。因此,多层ta?鄄C膜具有优良的力学性能和热稳定性,是一种优异的航空航天用光学元件的表面保护膜。 相似文献
17.
Meysam Sharifzadeh Mirshekarloo Kui Yao Thirumany Sritharan 《Advanced functional materials》2012,22(19):4159-4164
Coupling effects among mechanical, electrical and magnetic parameters in thin film structures including ferroic thin films provide exciting opportunity for creating device functionalities. For thin films deposited on a substrate, their mechanical stress and microstructure are usually determined by the composition and processing of the films and the lattice and thermal mismatch with the substrate. Here it is found that the stress and structure of an antiferroelectric (Pb0.97,La0.02)(Zr0.90,Sn0.05,Ti0.05)O3 (PLZST) thin film are changed completely by a ferroelastic strain in a magnetic shape memory (MSM) alloy Ni‐Mn‐Ga (NMG) thin film on the top of the PLZST, despite the existence of the substrate constraint. The ferroelastic strain in the NMG film results in antiferroelectric (AFE) to ferroelectric (FE) phase transformation in the PLZST layer underneath. This finding indicates a different strategy to modulate the structure and function for multilayer thin films and to create unprecedented devices with ferroic thin films. 相似文献
18.
Tensile Behaviors and Ratcheting Effects of Partially Sintered Chip-Attachment Films of a Nanoscale Silver Paste 总被引:2,自引:0,他引:2
The mechanical behaviors of partially sintered thick films of a nanoscale silver paste used for attaching semiconductor chips
are studied. The films, about 150 μm thick, were made by repeatedly stencil-printing the paste on a ceramic substrate and sintering by a recommended heating
profile suitable for device attachment. The partially sintered films were lifted off the substrate, and their tensile behaviors,
i.e., stress–strain curves, were measured at temperatures between −60°C and 300°C using a dynamic mechanical analyzer (DMA).
The elastic modulus and tensile strength of the sintered silver films decreased with increasing temperature. Ratcheting behaviors
of the films under cyclic tension at 150°C were also tested by using the DMA by examining the effects of loading rate, mean
stress, and stress amplitude. The ratcheting strain grew with increasing mean stress or stress amplitude and with decreasing
loading rate. 相似文献
19.
用脉冲激光沉积(PLD)方法在Si(111)和蓝宝石衬底上制备的氧化锌薄膜,在不同的退火温度和不同的退火氛围中进行了退火处理.退火温度及退火氛围对ZnO薄膜的结构和发光特性的影响用X射线衍射(XRD)谱和光致发光谱进行了表征.实验结果表明,随着退火温度的提高,ZnO薄膜的压应力减小,并向张应力转化.在不同的退火温度退火... 相似文献
20.
O. Rabin P.R. Herz Y.‐M. Lin A.I. Akinwande S.B. Cronin M.S. Dresselhaus 《Advanced functional materials》2003,13(8):631-638
A method for the fabrication of thick films of porous anodic alumina on rigid substrates is described. The anodic alumina film was generated by the anodization of an aluminum film evaporated on the substrate. The morphology of the barrier layer between the porous film and the substrate was different from that of anodic films grown on aluminum substrates. The removal of the barrier layer and the electrochemical growth of nanowires within the ordered pores were accomplished without the need to remove the anodic film from the substrate. We fabricated porous anodic alumina samples over large areas (up to 70 cm2), and deposited in them nanowire arrays of various materials. Long nanowires were obtained with lengths of at least 9 μm and aspect ratios as high as 300. Due to their mechanical robustness and the built‐in contact between the conducting substrate and the nanowires, the structures were useful for electrical transport measurements on the arrays. The method was also demonstrated on patterned and non‐planar substrates, further expanding the range of applications of these porous alumina and nanowire assemblies. 相似文献