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Dynamic change in distribution of strain generated in Si under a pad electrode was measured during ultrasonic ball bonding by using newly developed Si strain sensor. The sensor was designed to be able to determine strains in the directions normal and parallel to the surface. Bonding of Cu and Au was measured. It was clearly observed that the position of the largest compressive strain moved from the...
A novel low temperature wafer-level Cu-Cu bonding method using Ag nanoparticles (NP) was proposed and realized in this paper. A bonding structure consisted of Cu bonding pads, TiW barrier/adhesive layer was firstly fabricated on the silicon wafer. Ag NPs were then deposited by physical vapor deposition (PVD) on Cu pads. The morphology of Ag NPs annealed at different temperature was studied. Bonding...
The Josephson Arbitrary Waveform Synthesizer (JAWS) is currently being developed for generating precise voltage waveforms, for use in measurement standards. These system is based on superconducting Josephson junction arrays, and are operated by controlling the JAWS with high-speed (>10 GHz) current pulse trains in a cryogenic environment at 4K. Using an optical input rather than an electrical input,...
Pixelated LEDs are a new, high efficient light source which allows to control the beam pattern and which are therefore suitable for adaptive front light systems. We will present a concept for hybrid 3D flip chip stacking of pixelated LED chips onto an active matrix driver IC using a new interconnect structure to address thermal management and bonding robustness challenges. Two types of interconnect...
Room temperature and pressure bonding is shown for wafer-to-wafer (W2W) bonding but never for small chips. Usually, thermo-compression bonding (TCB) is employed for die-to-die (D2D) and die-to-wafer (D2W) bonding for 3D and MEMS application. TCB process is itself limited by tool capability and requires pressure and temperature for bonding which is not only time consuming but can induce coefficient...
Capacitive Micromachined Ultrasonic Transducers (CMUTs) fabricated using Silicon-On-Insulator (SOI) wafers often have large thickness variation of the flexible plate, which causes variation in both pull-in voltage and resonant frequency across the CMUT array. This work presents a bond and boron etch-stop scheme for fabricating the flexible plate of a CMUT. The proposed fabrication method enables precise...
We investigated why the blocking voltages of a power device are lowered during a durability test through a device simulation called Technology Computer Aided Design (TCAD) and measurements using the optical beam induced current (OBIC) method. We found that the spread of the depletion layer caused by the bonding wire is what decreased the blocking voltage.
We demonstrate coupling of surface and edge emitting InP lasers to silicon photonic chips using photonic wire bonding. We confirm that back-reflections from the silicon chip do not deteriorate the linewidth of the lasers.
Three-dimensional (3D) integration is considered as a good alternative solution to overcome the limitations of silicon scaling. Through Silicon Via (TSV) and wafer bonding are two key elements for 3D integration. This paper focuses on the realization of high density direct bonding interconnection. Hybrid Cu-Cu and SiO2-SiO2 bonding was chosen for direct inter-wafer interconnection. A mask set of Test-Vehicle...
Self-propagating exothermic reaction of Al/Ni multilayer film has been developed as a heat source with small heat region and high reaction rate in the field of bonding. In this paper, using this kind of localized and rapid heat source, solder preforms with different melting point such as SAC305 (217°C), Au80Sn20 (278°C) and A88Ge12 (356°C) have been applied to achieve the Si/Si bonding includes stacked...
Commercially available micron-sized Ag flake particles and submicron-sized Ag particles were used to make Ag paste. The Ag paste was used to connect Si dies to Ni-Ag plated Cu substrates to achieve die-bonding joint for high temperature application. The contact between die and Ag paste was affected by the loading pressure, and was realized with only 0.2 MPa pressure. And the shear strength depended...
This paper presents a high-performance bulk silicon comb-drive actuator with low driving voltage and large displacement. The bulk silicon comb-drive actuator is fabricated by a simple bulk micromachining process based on the low temperature Au-Au bonding technology. A cascade folded beam is designed to improve the displacement of comb-drive actuator at low driving voltages. The instability of the...
The integration of a varifocal mirror with a scanner using wafer bonding technology is presented. The wafer bonding technology enables us to enlarge the design possibility. A 2 mm diameter varifocal mirror is bonded on the scanner. The optical scanning angle is 7° at 3.59 kHz. The focal length changes from infinity to 139 mm.
We successfully fabricated Al-foil/p-Si junctions by surface activated bonding (SAB). We found that the junctions revealed Schottky properties by measuring their current-voltage characteristics. We also found that the reverse-bias current of the junctions was decreased, i.e., their electrical characteristics were improved by annealing at temperatures below 200 °C. These results demonstrate that the...
This paper reports on the development of packaging technology for the assembly of 30µm pitch micro Cu pillar bump (15µm diameter) on organic FCCSP substrate having bare Cu bondpad without NiAu or OSP surface protection. The assembly was performed by thermal compression bonding (TCB) with non-conductive paste (NCP). Finite element modeling and simulation were carried out to understand the Cu pillar...
For ultra-fine pitch and high density Cu pillar low temperature bonding (200°C), the surface contact between substrate and Cu pillar array is the key. Therefore, the fabrication quality of copper bump array affects severely the bonding results. The qualitative factors include (1) Cu pillar array height uniformity, (2) free of copper oxide layer, (3) Cu material property (e.g. elastic modulus, grain...
Wafer-to-wafer 3D integration has a potential tominimize the Si thickness, which enables us to connectmultiple wafers with significantly scaled through-Si vias. Inorder to achieve this type of 3D structure, backside thinningis a key step. Conventional mechanical grinding is known asthe best way to remove bulk Si in terms of cost of ownership(CoO). However, mechanical damage such as induceddislocations...
In this study we established a new process of the bonding and debonidng of the glasses for the handling of the ultra thin glass substrates. On the basis of the Surface Activated Bonding (SAB) method, the glasses were bonded using the Si and Fe intermediate layers at room temperature. The bond strength was evaluated before and after heating at 450°C, and the results showed the bond strength can be...
Direct Cu-Cu bonding has been pursued by the semiconductor industry as the next interconnection node, for its superior power-handling capability, thermal stability and reliability as compared to traditional solders. However, manufacturability of Cu interconnections has so far been severely limited by the relatively high modulus of Cu, requiring costly planarization processes to address non-coplanarities...
This paper reports on a feasibility study of using infrared (IR) laser ablation for silicon handler debonding for the first time. Various lasers were evaluated for the transmission through a Si handler and several release layers were studied for on low-power laser ablation. Debonding of silicon handler has been successfully demonstrated. Furthermore, a test vehicle based on through-silicon-via (TSV)...
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