Hanan Bar

Bio: Hanan Bar is an academic researcher from Intel. The author has contributed to research in topics: Electrode & Silicon. The author has an hindex of 10, co-authored 12 publications receiving 279 citations.

Metal contact reliability of RF MEMS switches

Abstract: It is well-recognized that MEMS switches, compared to their more traditional solid state counterparts, have several important advantages for wireless communications. These include superior linearity, low insertion loss and high isolation. Indeed, many potential applications have been investigated such as Tx/Rx antenna switching, frequency band selection, tunable matching networks for PA and antenna, tunable filters, and antenna reconfiguration. However, none of these applications have been materialized in high volume products to a large extent because of reliability concerns, particularly those related to the metal contacts. The subject of the metal contact in a switch was studied extensively in the history of developing miniaturized switches, such as the reed switches for telecommunication applications. While such studies are highly relevant, they do not address the issues encountered in the sub 100μN, low contact force regime in which most MEMS switches operate. At such low forces, the contact resistance is extremely sensitive to even a trace amount of contamination on the contact surfaces. Significant work was done to develop wafer cleaning processes and storage techniques for maintaining the cleanliness. To preserve contact cleanliness over the switch service lifetime, several hermetic packaging technologies were developed and their effectiveness in protecting the contacts from contamination was examined. The contact reliability is also very much influenced by the contact metal selection. When pure Au, a relatively soft metal, was used as the contact material, significant stiction problems occurred when clean switches were cycled in an N 2 environment. In addition, various mechanical damages occurred after extended switching cycling tests. Harder metals, while more resistant to deformation and stiction, are more sensitive to chemical reactions, particularly oxidation. They also lead to higher contact resistance because of their lower electrical conductivity and smaller real contact areas at a given contact force. Contact reliability issues could also be tackled by improving mechanical designs. A novel collapsing switch capable of generating large contact forces (>300μN) was shown to be less vulnerable to contamination and stiction.

A hybrid iii-v silicon laser formed by direct bonding

Abstract: Described herein is a hybrid III-V Silicon laser comprising a first semiconductor region including layers of semiconductor materials from group III, group IV, or group V semiconductor to form an active region; and a second semiconductor region having a silicon waveguide and bonded to the first semiconductor region via direct bonding at room temperature of a layer of the first semiconductor region to a layer of the second semiconductor region.

Uniformity study of wafer-scale InP-to-silicon hybrid integration

Abstract: In this paper we study the uniformity of up to 150 mm in diameter wafer-scale III–V epitaxial transfer to the Si-on-insulator substrate through the O2 plasma-enhanced low-temperature (300°C) direct wafer bonding. Void-free bonding is demonstrated by the scanning acoustic microscopy with sub-μm resolution. The photoluminescence (PL) map shows less than 1 nm change in average peak wavelength, and even improved peak intensity (4% better) and full width at half maximum (41% better) after 150 mm in diameter epitaxial transfer. Small and uniformly distributed residual strain in all sizes of bonding, which is measured by high-resolution X-ray diffraction Omega-2Theta mapping, and employment of a two-period InP–InGaAsP superlattice at the bonding interface contributes to the improvement of PL response. Preservation of multiple quantum-well integrity is also verified by high-resolution transmission electron microscopy.

Bump style MEMS switch

Abstract: A microelectromechanical system switch may be formed with a protrusion defined on the substrate which makes contact with a deflectable member arranged over the substrate. The deflectable member may, for example, be a cantilevered arm or a deflectable beam. The protrusion may be formed in the substrate in one embodiment using field oxide techniques.

Collapsible contact switch

Abstract: Embodiments of the invention describe a contact switch, which may include a bottom electrode structure including a bottom actuation electrode and a top electrode structure including a top actuation electrode and one or more stoppers able to maintain a predetermined gap between the top electrode and the bottom electrode when the switch is in a collapsed state.

Hybrid Integrated Platforms for Silicon Photonics

Abstract: A review of recent progress in hybrid integrated platforms for silicon photonics is presented. Integration of III-V semiconductors onto silicon-on-insulator substrates based on two different bonding techniques is compared, one comprising only inorganic materials, the other technique using an organic bonding agent. Issues such as bonding process and mechanism, bonding strength, uniformity, wafer surface requirement, and stress distribution are studied in detail. The application in silicon photonics to realize high-performance active and passive photonic devices on low-cost silicon wafers is discussed. Hybrid integration is believed to be a promising technology in a variety of applications of silicon photonics.

Mechanical meta-materials

Abstract: The present invention provides meta-materials with an actively controllable mechanical property. The meta-material includes a deformable structure and a set of activation elements. The activation elements are controllable between multiple states. The meta-material includes a first value for a mechanical property when one or more of the activation elements is in the first activation state and includes a second value for the mechanical property when the activation elements have been activated to the second activation state. In one aspect, the meta-material resembles a composite material where the connectivity between the component materials or shape and arrangement of the component materials is dynamically controllable so as to affect a mechanical property of the meta-material.

Mechanisms for room temperature direct wafer bonding

Abstract: Reducing the temperature needed for high strength bonding which was and is driven by the need to reduce effects of coefficient of thermal expansion mismatch, reduce thermal budgets, and increase throughput has led to the development of plasma treatment procedures capable of bonding Si wafers below 300 °C with a bond strength equivalent to Si bulk. Despite being widely used, the physical and chemical mechanisms enabling low temperature wafer bonding have remained poorly understood. We developed an understanding of the beneficial surface modifications by plasma and a model based on short range low temperature diffusion through bonding experiments combined with results from spectroscopic ellipsometry, depth resolving Auger electron spectroscopy, and transmission electron microscopy measurements. We also present experimental results showing that even at room temperature reasonable bond strength can be achieved. We conclude that the gap closing mechanism is therefore a process which balances the lowering of the total energy by minimizing the sum of the free surface energy (maximizing the contact area between the surfaces) and strain energy in the oxide at the bond interface.

Integrated finely tunable microring laser on silicon

Abstract: Finely tunable microring laser exploits integrated capacitive structure. Large-scale computer installations are severely limited by network-bandwidth constraints and energy costs that arise from architectural designs originally based on copper interconnects1. Wavelength-division multiplexed (WDM) photonic links can increase the network bandwidth but are sensitive to environmental perturbations and manufacturing imperfections that can affect the precise emission wavelength and output power of laser transmitters2,3. Here, we demonstrate a new design of a three-terminal hybrid III–V-on-silicon laser that integrates a metal-oxide-semiconductor (MOS) capacitor into the laser cavity. The MOS capacitor makes it possible to introduce the plasma-dispersion effect4 and thus change the laser modal refractive index and free-carrier absorption (FCA) loss to tune the laser wavelength and output power, respectively. The approach enables a highly energy efficient method to tune the output power and wavelength of microring lasers, with future prospects for high-speed, chirp-free direct laser modulation. The concept is potentially applicable to other diode laser platforms.

Heterogeneous Silicon/III–V Semiconductor Optical Amplifiers

Abstract: We report high output power and high-gain semiconductor optical amplifiers integrated on a heterogeneous silicon/III–V photonics platform. The devices produce 25 dB of unsaturated gain for the highest gain design, and 14 dBm of saturated output power for the highest output power design. The amplifier structure is also suitable for lasers, and can be readily integrated with a multitude of silicon photonic circuit components. These devices are useful for a wide range of photonic integrated circuits. We show a design method for optimizing the amplifier for the desired characteristics. The amplifier incorporates a low loss and low reflection transition between the heterogeneous active region and a silicon waveguide, and we report transition loss below 1 dB across the entire measurement range and parasitic reflection coefficient from the transition below $1\cdot 10^{ - 3}$ .