# Tung-Han Chuang's research while affiliated with National Taiwan University and other places

## Publications (209)

Preprint
This article presents a study of the influence of the substrate bias on the microstructure, preferred orientation, and mechanical and electrical properties of nanotwinned Cu film. The formation of a nanotwinned structure and (111) surface orientation can be properly controlled by applied substrate bias. High density nanotwinned structures were intr...
Article
Ag-alloy bonding wire has excellent physical properties and is widely applied in microelectronics, but growing concerns about circuit failure induced by electromigration (EM) have raised doubts about this material. One point of frequent debate is the diffusion mechanism. This study provides a novel perspective by investigating the evolution of the...
Article
To improve the adhesion between nickel (Ni) and silver (Ag) films in Ti/Ni/Ag backside-metallized silicon (Si) wafers, an additional layer of copper (Cu) film was added between the Ni and Ag layers. It was found that high-temperature storage caused the formation of voids in the Ag layer and degraded the whole structure. During high-temperature meta...
Article
The morphology and growth kinetics of the intermetallic compound formed during the reaction between liquid Sn-20In-2.8Ag solder and Ag substrate are studied in the temperature range 225–325 °C. The results indicate that the intermetallic compound Ag2+x(In, Sn) of scallop shape appears at the interface. The intermetallic thickness versus reaction ti...
Article
Full-text available
Due to the combined advantages of low cost, good soldering properties, and appropriate melting temperature range, novel Sn8Zn3Bi1Mg active solder was developed for direct soldering of transparent conductive oxide (TCO) ceramic targets with oxygen-free copper at 200°C in air. The TCO specimens have aluminum-doped zinc oxide (AZO) and zinc oxide (ZnO...
Article
For the production of Ag thin films containing a high density of nanotwins, evaporated Ag films were bombarded with an Ar+ ion beam with voltage of about 0.1 KeV. After the post-evaporation ion bombardment for 15 min, the equiaxial coarse grains in the surface region of the originally as-evaporated Ag films transformed into slender nanotwinned colu...
Article
Full-text available
In this study, AA6061/AA6061 and AA6061/alumina were directly brazed with Al10.8Si10Cu, Al10Si10Cu4Ti and Al10Si10Cu4Ti0.1RE filler alloys at 530 °C for 10 min without the use of flux. The addition of titanium and rare-earth elements into Al10.8Si10Cu alloy effectively improved the bonding shear strengths of AA6061/AA6061 and AA6061/alumina joints....
Article
Zn4Sb3 has received interest for thermoelectric (TE) applications due to its low cost and low environmental impact. In this study, the Zn4Sb3 TE material was diffusion-bonded with multiple electrode materials of Ni, Ag, Cu, Pd and Ti for evaluation of the manufacturing of TE modules. Intermetallic compounds formed at the interfaces of the Zn4Sb3 di...
Article
Full-text available
The precipitation-hardenable aluminum alloy 6061 (AA 6061) is favored for aerospace components and automotive parts. However, the tenacious oxide layer on the surface greatly limits the quality and applicability of joining AA 6061. In this study, the joining method of solid-state diffusion bonding was implemented for AA 6061 plates, and the effects...
Article
Full-text available
In this study, a novel method for producing high-density 〈111〉-oriented nanotwinned Ag film is proposed so as to improve the performance of backside metallization for power devices. Negative bias voltages were applied during sputtering to facilitate the formation of densely stacked nanotwinned columnar structures. In addition, the effects of substr...
Article
High-density Ag nanotwinned films with a very thin twin spacing of about 6.05 nm have been deposited by electron beam evaporation for the first time. With ion beam assistance, Ag thin films with a highly <111> textured structure can be deposited on Si substrates pre-coated with Ti/Ag (111) seed layers. In contrast, the Ag films deposited without io...
Article
In this study, different grain growth paths after aging at various temperatures for 1 hour were observed in Ag nanotwinned thin films with and without substrate bias voltage, which led to large differences in thermal stability. As-deposited Ag nanotwinned thin films with and without substrate bias voltage were characterized by FIB, EBSD, and TEM, w...
Article
Ion migration and corrosion behavior in Ag-4Pd alloy wires with fine and coarse grains in the outer regions were evaluated with water drop tests. The results from the in situ observations and measurements of Ag ion migration in both Ag-4Pd bonding wires indicated that the fine-grained wire had much shorter times of dendrite contact and short circui...
Article
Cheap, environmentally-friendly zinc antimonide is considered more favorable than conventional tellurite-based and skutterudite thermoelectric (TE) materials. Although the highly mobile zinc atoms located in the interstitial sites of the Zn4Sb3 crystalline structure greatly increase the figure of merit (ZT) of TE materials, the high chemical activi...
Article
Full-text available
For improving the performance of backside metallization for power electronic devices, an innovative Ag film with ultra-high twin density is proposed in this study. Experimentally, nanotwinned Ag films with thicknesses ranging from 2 to 8 µm and a strong (111) preferred orientation were sputtered on Si (100) wafers with and without a Ti thin film. T...
Article
In this study, low-temperature AgAg direct bonding was achieved at 150–250 °C in 10–60 min by using high (111)-preferred orientation films with densely-packed nanotwins fabricated by magnetron sputtering process. The focused ion beam (FIB) and transmission electron microscopy (TEM) results showed great bonding interfaces with almost no voids. The t...
Article
Zn-Sb alloys are potential low-cost and non-toxic p-type thermoelectric materials for applications in the temperature range between 300 and 700 K. In this experiment, Zn-Sb alloy films were prepared by electron beam evaporation through an ion beam assisted deposition (IBAD). Our studies have confirmed that the structural phase, chemical composition...
Article
In this study, the microstructural evolution of Ag-4Pd ribbon under various annealing conditions was investigated via electron backscatter diffraction (EBSD) technique. The as-manufactured Ag-4Pd ribbon, with an initial grain size of 3.66 µm and twin density of 53.1%, was held under different annealing treatment conditions of 623 K to 1073 K for ti...
Article
The bondability and reliability of Ag–5Pd–3.5Au alloy wire was verified previously for application in light-emitting diode (LED) packages. This Ag-alloy bonding wire has an electrical resistivity of 4.6 $\mu \Omega \cdot$ cm, lower than those of the ternary Ag–3Pd–20Au (8.6 $\mu \Omega \cdot$ cm) and Ag–3Pd–8Au wires (5.0 $\mu \Omega \cdot$...
Article
The wettability and growth of intermetallic compounds (IMCs) of stud bump materials Ag, Ag-4Pd, Cu, and Au with Sn-3Ag-0.5Cu (SAC305) solder have been investigated. Stud bumps produced using wire bonding techniques are widely employed in flip chip assembly, especially in 3D integrated circuit packaging. The material of stud bumps is a key factor in...
Article
Stud bumping using a traditional wire bonding process followed by the severing of the wire material from the ball bond has been widely applied in flip chip packages. Traditionally, Au stud bumps were employed because of the physical properties of gold, but the mediocre reliability of Au with Al pads and the cost of gold make this material unfavorab...
Article
Titanium thin film has been commonly used in the semiconductor industry as an adhesive layer to enhance the bonding strength between a metallic film and Si substrate. Depositing a Ti interlayer to alleviate the lattice mismatch for the epitaxial growth of nanotwinned Ag films on Si substrates with (100), (110) and (111) orientations by magnetron sp...
Article
High power impulse magnetron sputtering (HiPIMS) technology with extremely high target ionization rate is employed to deposit Ni³⁺-rich NiO films with enhanced p-type conductivity. However, the HiPIMS technique possesses a significant disadvantage; that is, its low deposition rate. In order to overcome this drawback, superimposed HiPIMS (HiPIMS + M...
Article
With the development of automotive power electronics and high power integrated circuits, ribbon bonding is currently in the spotlight for its superior properties to those of traditional heavy wire bonding. In this study, innovative ribbon materials made of Ag and Ag-4Pd are introduced. The ultrasonic bonding of Ag and Ag-alloy ribbons on direct bon...
Article
The development of Bi2Te3 thin films has huge potential in the pursuit of efficient thermoelectric micro/nanodevices due to their high Seebeck coefficient, high electrical conductivity and low thermal conductivity. The optimization of experimental parameters of BiTe thin films produced by co-evaporation will be investigated in this study. Co-evapor...
Article
A Bi0.5Sb1.5Te3 thermoelectric (TE) element was directly soldered to a Cu electrode using Sn-3Ag-0.5 Cu alloy. The interface was sound and the bonding strength was satisfactory (8.6 MPa). However, the solder layer was exhausted quickly during high-temperature storage (HTS) tests at 150°C for 300 h and 600 h, and the bonding strength drastically dec...
Article
This study investigated the mechanism of interfacial reaction of Ag-alloy wires in the gold bond pad of an LED die after a wire bonding process, and their reliability. The results showed that in the as-bonded condition, no IMC formed between the Ag-alloy wire and the gold bond pad and that the interfacial reaction mechanism was diffusional solid so...
Article
Full-text available
The evolutions of the surface morphologies, cross-sectional microstructures, and mechanical properties of two types of Ag-based alloy wires with different Au contents under a 10⁵ A/cm² electrical current density across various times were compared in this study. Ag-based alloy wires that contain 8 wt% Au and 15 wt% Au with 3 wt% Pd were produced via...
Article
Full-text available
The potential applications of perovskite manganite R1-xAxMnO3 (R = rare earth element; A = Sr, Ca) thin films have been continuously explored due to their multi-functional properties. In particular, the optimally hole-doped La0.67Ca0.33MnO3 thin film demonstrates a colossal magneto-resistance that is beneficial to the performance of spintronic devi...
Article
Full-text available
In this study, the microstructure and performance of different Ag-based conductive wires were investigated. Ag-based wires that contain 8, 15, 20, and 28 wt% Au were produced by multiple drawing and rapid annealing processes to substitute commercial gold wires in electronic packaging industries. The cross-sectional gain structures observed using fo...
Article
NiO thin films have been widely studied recently due to their intrinsic p-type conductivity and potential applications in various domains as transparent conductive oxides. However, the intrinsic p-type resistivity (ρ) of NiO is as high as 10 ¹³ Ω·cm, which needs to be optimized. In the current work, we devised an experiment to improve the electrica...
Article
In this work, (Al, Co)-ZnO films were co-sputtered on glass substrate through radio frequency sputtering at 100 °C. The film's structure, electrical and magnetic properties as a function of Al doping content is investigated. The results indicate that (Al, Co)-ZnO films crystallinity can be suppressed by Co doping or (Co, Al) co-doping. With the sub...
Article
The failure mechanism of the electromigration in Ag-Pd bonding wires was investigated through stressing with a current density of 1.23 × 105 A/cm2 at temperatures of 150 °C to 300 °C. It was found that the grains of the wire materials grew rapidly during current stressing for 100 minutes at various temperatures. In contrast, the grain structure rem...
Article
Silver-based bonding wires such as Ag-4Pd and Ag-8Au-3Pd have drawn remarkable attention in the packaging industry because they are cheaper and more conductive than Au- and Cu-based wires, respectively. This study aimed to investigate the intermetallic compound (IMC) formation and growth at the bonding interface between Ag-4Pd wire and Al-pads and...
Article
Full-text available
In this work, p-type non-stoichiometric Ni1−xO thin films were deposited by oxygen ion beam assisted RF sputtering on glass substrates. The influence of the oxygen flow ratio (0–100%) on the films’ optoelectronic properties was investigated. In our experimental conditions, all the films are crystallized in the cubic NiO phase. However, their crysta...
Article
During Ag ion migration in an aqueous water drop covering a pair of parallel Ag-Pd wires under current stressing, hydrogen bubbles form first from the cathode, followed by the appearance of pure Ag dendrites on the cathodic wire. In this study, Ag dendrites with a diameter of 0.2–0.4 μm grew toward the anodic wire. The growth rate (v) of these dend...
Article
The corrosion resistances of various Ag-alloy wires for the interconnection of integrated circuit and light-emitting diode packages were compared with those of traditional Au, Al, Cu, and pure Ag bonding wires through potentiodynamic polarization tests in 3.5 wt% NaCl aqueous solution. The results indicated that alloying the Ag bonding wires with P...
Article
We report a systematic study on the bilayers of ferromagnetic Sm1-xSrxMnO3 (SSMO) and superconducting YBa2Cu3O7 (YBCO). The bilayer structure is composed of one SSMO layer of 10 nm and one layer of YBCO with various thicknesses. The measurements of x-ray diffraction/reflectivity, resistivity and magnetization were carried out for determining the cr...
Article
Thanks to the intrinsic p-type conductivity, NiO films show great potential for applications in various domains. In this work, NiOx films were deposited in three dimensional physical vapor deposition (3D-PVD) system from metallic nickel target in pure oxygen conditions. Optical emission spectroscopy (OES) was employed to analyze the plasma state du...
Article
CuxO thin films were deposited on glass and silicon substrates by High Power Impulse Magnetron Sputtering (HiPIMS) at room temperature from a metallic copper target. The influence of pulse off-time on the films’ structural, morphological and optoelectronic properties was investigated. It was found that the power intensity applied on the Cu target w...
Article
In this study, Ni31Si69, Ni43Si57 and Ni63Si37 thin films with the thickness of 16 nm were deposited at room temperature by co-sputtering using Ni and Si targets. From the result of reflectivity-temperature measurement, it was found the NiSi layers possessed two temperature ranges of reflectivity change, i.e. 150–270 °C and 320–370 °C. Microstructu...
Article
A Bi0.5Sb1.5Te3 thermoelectric material electroplated with a Ni barrier layer and a Ag reaction layer was bonded with a Ag-coated Cu electrode at low temperatures of 448 K (175 °C) to 523 K (250 °C) using a 4-μm-thick In interlayer under an external pressure of 3 MPa. During the bonding process, the In thin film reacted with the Ag layer to form a...
Article
Herein, a novel method of high-power impulse magnetron sputtering (HiPIMS) was used to prepare Cu2O thin films, which were deposited at ambient temperature without further thermal treatment. The films with varying optoelectronic properties as a function of oxygen flow ratio ( ) were investigated. The results demonstrate that the film's performances...
Article
The ZnSb intermetallic compound may have thermoelectric applications because it is low in cost and environmentally friendly. In this study, a Zn4Sb3 thermoelectric element coated with a Ni barrier layer and a Ag reaction layer was bonded with a Ag-coated Cu electrode using a Ag/Sn/Ag solid–liquid interdiffusion bonding process. The results indicate...
Article
In this study, [Co0.05GaxZn(0.95 − x)O] films with different Ga contents were co-sputtered on glass substrates by rf magnetron sputtering. The content of Co in the films was fixed at ~ 5 at.%. The content of x [Ga/(Ga + Co + Zn)] varied from 0 to 3.2 at.%. As analyzed by Hall effect measurement, the resistivity (ρ) of the film is 42.90 Ω·cm when x...
Article
The materials characteristics of annealing-twinned Ag-alloy wires with various Au and Pd contents were evaluated in this paper. The results indicated that both Ag-8Au-3Pd and Ag-15Au-3Pd have higher strength and corrosion resistance than do pure Ag and binary Ag-Pd wires. On the other hand, the pure Ag, Ag-0.5Pd, Ag-3Pd, and Ag-4Pd wires possess th...
Article
In this study, the reliability performance of two capillary-type underfill materials with different glass transition temperatures (Tg) and coefficients of thermal expansion (CTE) were assessed for a chip stacking architecture. The microbumps for integrating four chips on a Si interposer were with a pitch size of 20 lm and composed of 5 μm Cu/3 μm N...
Article
The spin injection effects from C-type antiferromagnetic Nd0.35Sr0.65MnO3 (NSMO) to superconductor YBa2Cu3O7−δ (YBCO) are investigated via the measurement of temperature dependent resistivity with input current from 10−2 mA to 90 mA. The superconducting transition temperature (Tco) of YBCO decreases with increasing current but at a higher rate with...
Article
The mechanism of electromigration in Ag-alloy wires containing different amounts of Pd and Au has been studied. Thinning and thickening accompanying grain growth were observed in worn bonding wire after current stress. The mean time-to-failure of bonding wires stressed with different current densities is highly dependent on their electrical resisti...
Article
An annealing twinned Ag-4Pd binary alloy wire has been produced as an alternate material for a previously developed Ag-8Au-3Pd ternary alloy wire to meet requirements for high electrical conductivity and low cost. The electrical resistivity of this annealing twinned Ag-alloy bonding wire decreased drastically from the original value of 3.5 μΩ·cm to...
Article
A (Pb, Sn)Te thermoelectric element plated with a Ni barrier layer and a Ag reaction layer has been joined with a Cu electrode coated with Ag and Sn thin films using a solid-liquid interdiffusion bonding method. This method allows the interfacial reaction between Ag and Sn such that Ag3Sn intermetallic compounds form at low temperature and are stab...
Article
A (Pb, Sn)Te thermoelectric (TE) material coated with a Ni barrier layer and a Ag reaction layer was bonded with a Ag-coated Cu electrode at low temperatures in the range of 175–250 °C with an In thin film. The In film reacted initially with the Ag layer to form a double layer of Ag3In and Ag2In intermetallic compounds, which then completely reacte...
Article
Full-text available
Ag-4Pd binary alloy wire has been produced as an alternative to a previously developed Ag-8Au-3Pd ternary alloy wire to meet requirements for high electrical conductivity and low cost. The electrical resistivity of this Ag-4Pd bonding wire, manufactured with a conventional method, is 3.7 μΩ cm, close to the values of traditional 3N Au wire (3.5 μΩ...
Conference Paper
Recently, 3-D IC and 2.5-D IC packages become more popular and Cu pillars are often employed as their conductive bumps. However, since the Cu pillars are hard and rigid, it is difficult to plastically deform for the solid contact between the Cu pillars and bonding pads during the assembly process utilizing hot pressing. In this case, a coplanar pro...
Article
This paper presents a solid liquid inter-diffusion (SLID) bonding process using nickel-tin. By using two metals with different melting points, Ni3Sn4, an intermetallic compound (IMC) at 523K was formed. Unlike pure metal, the IMC can be used in high temperature applications of up to 800K without failure. The formation energy of Ni3Sn4 IMC was calcu...
Article
The durability against electromigration of an annealing twinned Ag-8Au-3Pd wire is about double that of the conventional grained wire under electrical current stressing of 1.23 × 105 A/cm2. During electromigration, a particular morphology of surface reconstruction comprising a stepwise structure and hillocks can be observed in this annealing twinne...
Conference Paper
Binary Ag-Pd alloy wires designed for both requirements of high reliability and low electrical resistivity have been developed and patented by Wire Technology Co. in Taiwan. The electrical resistivity of these Ag-Pd bonding wires are 1.98 to 3.5μΩ·cm. After stressing with various current densities, their mean times to failure are much higher than t...
Article
Rapid whisker growth was significantly alleviated in a Sn-58Bi alloy doped with 0?5 wt-%La. Experimental results showed that many thin, plate form intermetallic phases appeared in the solder matrix. The absence of tin whiskers was correlated to the shape effect of RE containing intermetallic plates. After reflowing, Cu6Sn5 intermetallic compounds a...
Article
For the production of thermoelectric modules, Bi0.5Sb1.5Te3 was sequentially electroplated with a 4-μm Ni barrier layer and a 10-μm Ag layer and then diffusion soldered with the Cu electrode, which was also electroplated with 4-μm Ag and 4-μm Sn layers. The Bi0.5Sb1.5Te3 and Ni interface with no sufficient chemical bonds resulted in a bonding stren...
Article
An innovative Ag-8Au-3Pd bonding wire with a high twin density has been produced. The grain size of this annealing-twinned wire changes moderately during electrical stressing, unlike that of the conventional grained wire, which increases drastically and even leads to a bamboo structure. In addition, the durability against electromigration of the an...
Article
Wire bonding on Al pad packages with an innovative annealing twinned Ag-8Au-3Pd alloy wire results in a sufficient interfacial intermetallic layer at the initial as-bonded stage, while its growth during the further temperature cycling test and pressure cooker test is very slow. Even after prolonged high-temperature storage at 150°C for 500 h, the t...
Conference Paper
Wide band gap (WBG) semiconductors such as SiC and GaN devices are expected to replace Si power devices in the next generation power modules for renewable energy and smart grid to enhance their energy conversion efficiency through a characteristic of high frequency switching. However, the temperature of the WBG power module may reach 250°C as opera...
Article
An innovative Ag-8Au-3Pd bonding wire containing a large amount of annealing twins has been produced. In contrast to the apparent grain growth in a conventional Ag-8Au-3Pd wire during aging at 600°C, the grain size of this annealing-twinned Ag alloy wire remains almost unchanged. The high thermal stability of the grain structure leads to a smaller...
Conference Paper
An innovative annealing twinned Ag-(8-30%)Au-(0.01-6%) Pd wire for IC and LED packaging has been developed. It exhibits high thermal stability during aging at 600°C and a small heat affected zone after wire bonding. The mean failure time of this annealing twinned Ag-Au-Pd wire when stressed with a current density of 1.23 × 105A/cm2 is about double...
Article
In a Ag–8Au–3Pd wire, a large number of annealing twins can be observed. In contrast to the rapid grain growth in Au and Cu wires during aging at 600 °C, the grain size of this Ag alloy wire remained almost unchanged. The annealing twins in this material also possess the dual merits of increasing strength and elongation with aging time, while the e...
Article
This paper presents the microstructure and Vickers microhardness of Sn3.5Ag0.5Cu solder doped with trace amounts of TiO2 nanopowders, obtained with different cooling rate and aging conditions. The experiment results that the coupling effect by cooling rate and TiO2 nanopowders additions significantly affected primary β-Sn phase, Ag3Sn grain size an...
Article
In this research, thousands of 20-$\mu{\rm m}$ pitch microbumps with a diameter of 10 $\mu{\rm m}$ and a structure of a pure Sn cap on a Cu pillar were electroplated on 8-inch wafers, and those wafers were then respectively singularized as a top chip and bottom Si interposer for stacking. Two methods, namely conventional reflow and solid–liquid int...
Article
Directly coating a GeTe(Pb) thermoelectric device with a Ni barrier layer and an Ag reaction layer and then diffusion soldering with a Cu electrode coated with Ag and Sn leads to breakage at the GeTe(Pb)/Ni interface and low bonding strengths of about 6 MPa. An improved process, precoating with 1 μm Sn film and heating at 250°C for 3 min before ele...
Article
In this work, TiO2 nanoparticles were successfully incorporated into Sn3.5Ag and Sn3.5Ag0.7Cu solder, to synthesize novel lead-free composite solders. Effects of the TiO2 nanoparticle addition on the microstructure, melting property, microhardness, and the interfacial reactions between Sn3.5AgXCu and Cu have been investigated. Experimental results...
Article
To improve the properties of the eutectic Sn3.5Ag0.5Cu lead-free solder, various amounts of mixed nano-Al2O3 particles were added. The microstructure, thermal analysis, density, thermal expansion coefficient (CTE), and mechanical behavior were studied. The results of differential scanning calorimetry (DSC) indicate that the melting point of the com...
Article
Through the refinement of the (Ce, Zn)Sn3 intermetallic phase, the formation of tin whiskers, previously observed on the surface of a Sn-3Ag-0.5Cu-0.5Ce solder, was prevented in a Sn-9Zn-0.5Ce alloy. However, whisker growth can still occur on the surface of Sn-8Zn-3Bi-0.5Ce solder after air storage at room temperature and at 150 °C due to the forma...
Article
Rapid growth of tin whiskers has been observed on the surface of rosette-shaped NdSn3 intermetallic phase in a Sn-3Ag-0.5Cu-0.5Nd alloy after air storage. It is shown that various cross sections of NdSn3 rosettes in the solder matrix reveal different morphologies of tin whiskers, which can be classified as four types: long fibers, short fibers, tin...
Article
Although it has been verified that tin whiskers can be prevented by the addition of 0.5wt.% Zn into a Sn–3Ag–0.5Cu–0.5Ce solder, no detailed studies have been conducted on interfacial reactions and mechanical properties of Sn–3Ag–0.5Cu–0.5Ce–xZn solder joints with an immersion Ag surface finish. The intermetallic compounds formed during the reflow...