Browsing by Author "Lai, Yi-Shao"

Now showing 1 - 20 of 20

Blocking hillock and whisker growth by intermetallic compound formation in Sn-0.7Cu flip chip solder joints under electromigration
(2010-05-01)
Liang, S. W.
;
Chen, Chih
;
Han, J. K.
;
Xu, Luhua
;
Tu, K. N.
Mass extrusion occurs in electromigration at the anode in cross-sectioned Sn-0.7Cu flip-chip solder joints. In a pair of joints, the hillock squeezed out at the anode on the board side is more serious than the whisker grown at the anode on the chip side. The difference of mass extrusion has been found to be affected by the amount of intermetallic compound (IMC) formation in the solder bump. It is found that when a large amount of Cu-Sn IMCs form in the grain boundaries of Sn grains, small hillocks are extruded on the anode end. It is proposed that the excessive IMC formation may be able to block the diffusion path of Sn atoms, so the growth of both the Sn whiskers and hillocks are retarded. (C) 2010 American Institute of Physics. [doi:10.1063/1.3410796]
Characteristics of ZnO thin films prepared by radio frequency magnetron sputtering
(2008-03-01)
Yang, Ping-Feng
;
Wen, Hua-Chiang
;
Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Wu, Sean
We investigated in this study structural and nanomechanical properties of zinc oxide (ZnO) thin films deposited onto Langasite substrates at 200 degrees C through radio frequency magnetron sputtering with an radio frequency power at 200 W in an O(2)/Ar gas mixture for different deposition time at 1, 2, and 3 h. Surface morphologies and crystalline structural characteristics were examined using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The deposited film featured a polycrystalline nature, with (100), (002), and (101) peaks of hexagonal zinc oxide at 31.75 degrees, 34.35 degrees, and 36.31 degrees. As the deposition time increased, the ZnO film became predominantly oriented along the c-axis (002) and the surface roughness decreased. Through Berkovich nanoindentation following a continuous stiffness measurement technique, the hardness and Young's modulus of ZnO thin films increased as the deposition time increased, with the best results being obtained for the deposition time of 3 h. In addition, surface acoustic wave properties of ZnO thin films were also presented. (C) 2007 Elsevier Ltd. All rights reserved.
Cross-sectional transmission electron microscopy observations of structural damage in Al(0.16)Ga(0.84)N thin film under contact loading
(2008-02-01)
Jian, Sheng-Rui
;
Juang, Jenh-Yih
;
Lai, Yi-Shao
;
電子物理學系
;
Department of Electrophysics
This article reports a nanomechanical response study of the contact-induced deformation behavior in Al(0.16)Ga(0.84)N thin film by means of a combination of nanoindentation and the cross-sectional transmission electron microscopy (XTEM) techniques. Al(0.16)Ga(0.84)N thin film is deposited by using the metal-organic chemical vapor deposition method. Hardness and Young's modulus of the Al(0.16)Ga(0.84)N films were measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements mode. The obtained values of the hardness and Young's modulus are 19.76 +/- 0.15 and 310.63 +/- 9.41 GPa, respectively. The XTEM images taken in the vicinity just underneath the indenter tip revealed that the multiple "pop-ins" observed in the load-displacement curve during loading are due primarily to the activities of dislocation nucleation and propagation. The absence of discontinuities in the unloading segments of the load-displacement curve suggests that no pressure-induced phase transition was involved. (c) 2008 American Institute of Physics.
Cross-sectional transmission electron microscopy observations on the Berkovich indentation-induced deformation microstructures in GaN thin films
(2007-07-07)
Chien, Chi-Hui
;
Jian, Sheng-Rui
;
Wang, Chung-Ting
;
Juang, Jenh-Yih
;
Huang, J. C.
Nanoindentation-induced mechanical deformation in GaN thin films prepared by metal-organic chemical-vapour deposition was investigated using the Berkovich diamond tip in combination with the cross-sectional transmission electron microscopy (XTEM). By using focused ion beam milling to accurately position the cross-section of the indented region, the XTEM results demonstrate that the major plastic deformation was taking place through the propagation of dislocations. The present observations are in support of attributing the pop-ins that appeared in the load-displacement curves to the massive dislocation activities occurring underneath the indenter during the loading cycle. The absence of indentation-induced new phases might have been due to the stress relaxation via the substrate and is also consistent with the fact that no discontinuity was found upon unloading.
Effect of annealing treatment and nanomechanical properties for multilayer Si(0.8)Ge(0.2)-Si films
(2010-06-01)
He, Bo-Ching
;
Wen, Hua-Chiang
;
Lin, Meng-Hung
;
Lai, Yi-Shao
;
Wu, Wen-Fa
Multilayered silicon-germanium (SiGe) films consisting of alternating sublayers with different mechanical properties have been epitaxially deposited by an ultra-high vacuum chemical vapor deposition (UHV/CVD) system. We report engineering of the mechanical properties of SiGe multilayer films by a commercial nanoindenter. From annealing treatment, it consists of an ex situ thermal treatments in furnace (600 degrees C) and rapid thermal annealing (800 degrees C) system. Subsequent roughness and microstructure of SiGe multilayer films were characterized by means of atomic force microscope (AFM) and transmission electron microscopy (TEM). The annealing treatment not only produced misfit dislocations as a significant role in the critical pile-up event but also promoted hardness. The hardness of the films increased slightly and then gradually achieved a maximum value (from 12.6 +/- 0 4 GPa to 14.2 +/- 0.7 GPa) with increasing annealing temperature. This may be due to the relaxation effect from thermal annealing and is potential to provide the reliability behaviours to design periodical SiGe multilayer structure in further. (C) 2010 Published by Elsevier Ltd
Evaluating nanotribological behavior of annealing Si(0.8)Ge(0.2)/Si films
(2011-12-01)
Wu, Ming-Jhang
;
Wen, Hua-Chiang
;
Wu, Shyh-Chi
;
Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load. Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluating nanotribological behavior of annealing Si0.8Ge0.2/Si films
(2011-12-01)
Wu, Ming-Jhang
;
Wen, Hua-Chiang
;
Wu, Shyh-Chi
;
Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load. Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluation of the nanoindentation behaviors of SiGe epitaxial layer on Si substrate
(2010-01-01)
He, Bo-Ching
;
Cheng, Chun-Hu
;
Wen, Hua-Chiang
;
Lai, Yi-Shao
;
Yang, Ping-Feng
In this paper, ultra-high vacuum chemical vapor deposition (UHV/CVD) was employed to synthesize silicon-germanium (SiGe), and sequence to endure annealing treatment. Morphological characterization, roughness, and microstructural morphology were observed by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The elements distribution, crystallographic, and nanomechanical behavior were carried out using energy-dispersive Xray spectroscopy (EDS) mapping technique, X-ray diffraction (XRD), and nanoindentation technique. The annealing treated SiGe leads to the 2D germanium segregation on the surface. The phenomenon is interpreted in terms of dislocation-induced structural changes in annealing treatment, Thus, the dislocation propagation in the microstructure was observed. Subsequently hardness and elastic modulus were increased because of a comparatively unstable microstructure after annealing treatment. (C) 2009 Elsevier Ltd. All rights reserved.
Influence of Cu column under-bump-metallizations on current crowding and Joule heating effects of electromigration in flip-chip solder joints
(2012-02-15)
Liang, Y. C.
;
Tsao, W. A.
;
Chen, Chih
;
Yao, Da-Jeng
;
Huang, Annie T.
The electromigration behavior of SnAg solder bumps with and without Cu column under-bump-metallizations (UBMs) has been investigated under a current density of 2.16 x 10(4) A/cm(2) at 150 degrees C. Different failure modes were observed for the two types of samples. In those without Cu column UBMs, when SnAg solder bumps that had implemented 2 mu m Ni UBMs were current stressed at 2.16 x 10(4) A/cm(2), open failure occurred in the bump that had an electron flow direction from the chip side to the substrate side. However, in those with Cu column UBMs, cracks formed along the interface of Cu6Sn5 intermetallic compounds and the solder on the substrate side in the Sn-3.0Ag-0.5Cu solder bump that had an electron flow direction from the substrate side to the chip side. A three-dimensional simulation of the current density distribution was performed in order to obtain a better understanding of the current crowding behavior in solder bumps. The current crowding effect was found to account for the void formation on both the chip and the substrate side for the two kinds of solder bumps. One more important finding, as confirmed by infrared microscopy, is that the alleviation of current crowding by Cu column UBMs also helped decrease the Joule heating effect in solder bumps during current stressing. Therefore, the measured failure time for the solder joints with Cu column UBMs appears to be much longer than that of the ones with the 2 mu m Ni UBMs. (C) 2012 American Institute of Physics. [doi:10.1063/1.3682484]
Mechanical properties of InGaN thin films deposited by metal-organic chemical vapor deposition
(2008-06-15)
Jian, Sheng-Rui
;
Jang, Jason Shian-Ching
;
Lai, Yi-Shao
;
Yang, Ping-Feng
;
Yang, Chu-Shou
We report in this study characteristics of InGaN thin films developed by metal-organic chemical vapor deposition (MOCVD) at various growth temperatures. The effect of deposition temperatures on microstructures and mechanical properties are examined using X-ray diffraction (XRD), scanning probe microscopy (SPM), and nanoindentation techniques. The XRD analysis shows no evidence of phase separation for InGaN thin films. The SPM micrographs indicate that the films have relatively smooth surfaces. Hardness and Young's modulus of InGaN thin films vary according to the deposition temperature. As the deposition temperature increases from 730 to 790 degrees C, the grain size increases from 28 to 52 nm. Hardness for InGaN thin films dropped from 13.8 to 17.6 GPa in accordance with the increase of the grain size. By fitting experimental data with the Hall-Petch equation, a probable lattice friction stress of 3.48 GPa and Hall-Petch constant of 73.15 GPa nm(1/2) are obtained. (C) 2007 Elsevier B.V. All rights reserved.
Mechanical properties of the hexagonal HoMnO(3) thin films by nanoindentation
(2010-10-22)
Yen, Cheng-Yo
;
Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Yang, Ping-Feng
;
Liao, Ying-Yen
The structural and nanomechanical characteristics of the hexagonal HoMnO(3) (HMO) thin films are investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques in this study. The HMO thin films were deposited on YSZ(1 1 1) substrates by pulsed laser deposition (PLD). The XRD results reveal only pure (0 0 0 1)-oriented hexagonal HMO reflections without any discernible traces of impurity or secondary phases. Nanoindentation results exhibit discontinuities in the load-displacement curve (so-called multiple "pop-ins" event) during loading, indicating possible involvement of dislocation activities. No discontinuities were observed on unloading segment of the load-displacement curve. Continuous stiffness measurements (CSM) technique was carried out in the nanoindentation tests to determine the hardness and Young's modulus of the hexagonal HMO thin films. The obtained hardness and Young's modulus of the hexagonal HMO thin films are 14.2 +/- 0.7 GPa and 219.2 +/- 10.6 GPa, respectively with the room-temperature fracture toughness being in the order of 0.4 +/- 0.2 MPa m(1/2). (c) 2010 Elsevier B.V. All rights reserved.
Mechanical properties of the hexagonal HoMnO3 thin films by nanoindentation
(2010-10-22)
Yen, Cheng-Yo
;
Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Yang, Ping-Feng
;
Liao, Ying-Yen
The structural and nanomechanical characteristics of the hexagonal HoMnO3 (HMO) thin films are investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques in this study. The HMO thin films were deposited on YSZ(1 1 1) substrates by pulsed laser deposition (PLD). The XRD results reveal only pure (0 0 0 1)-oriented hexagonal HMO reflections without any discernible traces of impurity or secondary phases. Nanoindentation results exhibit discontinuities in the load-displacement curve (so-called multiple "pop-ins" event) during loading, indicating possible involvement of dislocation activities. No discontinuities were observed on unloading segment of the load-displacement curve. Continuous stiffness measurements (CSM) technique was carried out in the nanoindentation tests to determine the hardness and Young's modulus of the hexagonal HMO thin films. The obtained hardness and Young's modulus of the hexagonal HMO thin films are 14.2 +/- 0.7 GPa and 219.2 +/- 10.6 GPa, respectively with the room-temperature fracture toughness being in the order of 0.4 +/- 0.2 MPa m(1/2). (c) 2010 Elsevier B.V. All rights reserved.
Morphological, structural, and mechanical characterizations of InGaN thin films deposited by MOCVD
(2008-09-08)
Yang, Ping-Feng
;
Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Yang, Chu-Shou
;
Chen, Rong-Sheng
Presented in this study are surface roughness, crystalline structure, and nanomechanical properties of InGaN thin films deposited under various growth temperatures, obtained by means of X-ray diffraction (XRD), atomic force microscopy (AFM), and nanoindentation techniques. The InGaN thin films with different In contents were deposited on sapphire substrates through a metal-organic chemical-vapor deposition (MOCVD) system. Changes in mechanical properties for InGaN thin films are discussed in conjunction with deposition temperature, surface morphology and crystalline structure. The XRD measurements showed that there was no phase separation of In as the In composition went from 25 at.% to 34 at.%. Moreover, both XRD and AFM showed larger grain and surface roughness in In0.25Ga0.75N thin films. Nanoindentation results indicate that hardness and Young's modulus both decreased as the indentation depth increased. The contact stress-strain relationships were also analyzed. (C) 2007 Elsevier B.V. All fights reserved.
Nanoindentation-induced phase transformation of silicon
(2006)
Yang, Ping-Feng
;
Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Chen, Tsan-Hsien
;
Chen, Rong-Sheng
In this study, the deformation behavior of single-crystal Si (100) was examined using nanoindentation, followed by analysis using cross-sectional transmission electron microscopy (XTEM), scanning electron microscopy (SEM), and Raman microspectroscopy. XTEM samples were prepared by focused ion beam (FIB) milling to accurately position the cross-section through the indentations. The deformation via phase transformation was clearly observed with micro-Raman and XTEM, showing the presence of high-pressure crystalline phases Si-Ill and Si-XII following pressure release. The indentation fracture toughness of Si is also discussed.
Nanoindentation-Induced Structural Deformation in GaN/AIN Multilayers
(2010-12-01)
Jian, Sheng-Rui
;
Juang, Jenh-Yih
;
Chen, Nie-Chuan
;
Jang, Jason S. -C.
;
Huang, J. C.
The mechanical responses of GaN/AIN multilayers grown on Si(111) substrates by using the metal-organic vapor phase epitaxy (MOVPE) were investigated by combining the Berkovich nanoindentation and the cross-sectional transmission electron microscopy (XTEM) techniques. The prominent mechanical parameters such as the hardness and Young's modulus of GaN/AIN multilayers were obtained to be 21.6 +/- 0.8 GPa and 285.7 +/- 12.1 GPa, respectively by operating the Berkovich nanoindenter with the continuous contact stiffness measurements (CSM) mode. The structural deformation behaviors were delineated by XTEM observations taken in the vicinity regions just underneath the indenter tip. It was revealed that the "pop-ins" observed in the load displacement curve during loading are due primarily to the activities of dislocation nucleation and propagation. There is no evidence of either phase transformation or micro-crack formation observed in XTEM images of GaN/AIN multilayers, which is consistent with no distinct "pop-out" event displayed in unloading curves.
Nanomechanical characteristics of annealed Si/SiGe superlattices
(2011-08-15)
Wu, Ming-Jhang
;
Wen, Hua-Chiang
;
Wu, Shyh-Chi
;
Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the nanomechanical damage was investigated on the annealed Si/SiGe strained-layer superlattices (SLSs) deposited using an ultrahigh-vacuum chemical vapor deposition (UHVCVD). Nanoscratch, nanoindenter, atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques were used to determine the nanomechanical behavior of the SiGe films. With a constant force applied, greater hardness number and larger coefficients of friction (mu) were observed on the samples that had been annealed at 600 degrees C, suggesting that annealing of the Si/SiGe SLSs can induce greater shear resistance. AFM morphological studies of the Si/SiGe SLSs revealed that pile-up phenomena occurred on both sides of each scratch, with the formation of some pellets and microparticles. The Si/SiGe SLSs that had been subjected to annealing under various conditions exhibited significantly different features in their indentation results. Indeed, the TEM images reveal slight dislocation propagation in the microstructures. Thus, the hardness and elastic modulus can be increased slightly after annealing treatment because the existence of comparatively unstable microstructures. It is suggested that cracking phenomena dominate the damage cause of Si/SiGe SLSs. (C) 2011 Elsevier B. V. All rights reserved.
Nanotribological properties of ALD-processed bilayer TiO2/ZnO films
(2014-12-01)
Wang, Wun-Kai
;
Wen, Hua-Chiang
;
Cheng, Chun-Hu
;
Hung, Ching-Hua
;
Chou, Wu-Ching
TiO2/ZnO films grown by atomic layer deposition (ALD) demonstrated nanotribological behaviors using scratch testing. TEM profiles obtained an amorphous structure TiO2 and nanocrystalline structure ZnO, whereas the sample has significant interface between the TiO2/ZnO films. The experimental results show the relative XRD peak intensities are mainly contributed by a wurtzite oxide ZnO structure and no signal from the amorphous TiO2. With respect to tribology, increased friction causes plastic deformation between the TiO2 and ZnO films, in addition to delamination and particle loosening. The plastic deformation caused by adhesion and/or cohesion failure is reflected in the nanoscratch traces. The pile-up events at a loading penetration of 30 nm were measured at 21.8 mu N for RT, 22.4 mu N for 300 degrees C, and 36 mu N for 400 degrees C. In comparison to the other conditions, the TiO2/ZnO films annealed at 400 degrees C exhibited higher scratch resistance and friction with large debris, indicating the wear volume is reduced with increased annealing temperature and loading. (C) 2014 Elsevier Ltd. All rights reserved.
Nonuniform and Negative Marker Displacements Induced by Current Crowding During Electromigration in Flip-Chip Sn-0.7Cu Solder Joints
(2009-12-01)
Liang, S. W.
;
Hsiao, Hsiang-Yao
;
Chen, Chih
;
Xu, Luhua
;
Tu, K. N.
A quantitative analysis of the nonuniform distribution of current density and nonuniform rate of electromigration has been carried out by measuring the movement of an array of diffusion markers. Tiny marker arrays were fabricated by focused ion beam on the polished surface of flip-chip solder joints near the anode to measure the electromigration rate. The marker velocity at the current-crowding region was found to be at least five times larger than at locations far from the region. Some of the markers in the low-current-density region possess negative velocities, indicating that backflow occurs during the electromigration. The backflow, in which the atomic flow is against the electron flow, is explained by a constant-volume model as well as the back-stress induced by electromigration.
Surface morphological and nanomechanical properties of PLD-derived ZnO thin films
(2008-05-01)
Jian, Sheng-Rui
;
Teng, I-Ju
;
Yang, Ping-Feng
;
Lai, Yi-Shao
;
Lu, Jian-Ming
This study reports the surface roughness and nanomechanical characteristics of ZnO thin films deposited on the various substrates, obtained by means of atomic force microscopy (AFM), nanoindentation and nanoscratch techniques. ZnO thin films are deposited on (a- and c-axis) sapphires and (0001) 6H-SiC substrates by using the pulsed-laser depositions (PLD) system. Continuous stiffness measurements (CSM) technique is used in the nanoindentation tests to determine the hardness and Young's modulus of ZnO thin films. The importance of the ratio (H/E-film) of elastic to plastic deformation during nanoindentation of ZnO thin films on their behaviors in contact-induced damage during fabrication of ZnO-based devices is considered. In addition, the friction coefficient of ZnO thin films is also presented here.
The effects of hydrogen plasma pretreatment on the formation of vertically aligned carbon nanotubes
(2007-09-30)
Wang, Wen-Pin
;
Wen, Hua-Chiang
;
Jian, Sheng-Rui
;
Juang, Jenh-Yih
;
Lai, Yi-Shao
The effects of H-2 plasma pretreatment on the growth of vertically aligned carbon nanotubes (CNTs) by varying the flow rate of the precursor gas mixture during microwave plasma chemical vapor deposition (MPCVD) have been investigated in this study. Gas mixture of H-2 and CH4 with a ratio of 9:1 was used as the precursor for synthesizing CNTs on Ni-coated TiN/Si(1 0 0) substrates. The structure and composition of Ni catalyst nanoparticles were investigated by using scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (XTEM). Results indicated that, by manipulating the morphology and density of the Ni catalyst nanoparticles via changing the flow rate of the precursor gas mixture, the vertically aligned CNTs could be effectively controlled. The Raman results also indicated that the intensity ratio of the G and D bands (I-D/I-G) is decreased with increasing gas flow rate. TEM results suggest H-2 plasma pretreatment can effectively reduce the amorphous carbon and carbonaceous particles and. thus. is playing a crucial role in modifying the obtained CNTs structures. (c) 2007 Elsevier B.V. All rights reserved.