Electromigration behavior and reliability of bamboo Al(Cu) interconnects for integrated circuits

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.Includes bibliographical references (leaves 103-108).by V.T. Srikar.Ph.D

Miniaturization limits for single-chamber micro-solid oxide fuel cells with coplanar electrodes

Single-chamber solid oxide fuel cells with coplanar microelectrodes were operated in methane-air mixtures (Rmix = 2) at 700°C. The performance of cells with one pair of NiO-YSZ (yttria stabilized zirconia) anode and (La0.8Sr0.2)0.98MnO3-YSZ cathode, arranged parallel on a YSZ electrolyte substrate, was found to be significantly dependent on the electrode width. For an interelectrode gap of ~250m, cells with average electrode widths exceeding ~850m could establish a stable open circuit voltage (OCV) of ~0.8 V, while those with widths less than ~550 µm could not establish any OCV. In the intermediate range, the cells exhibited significant fluctuations in voltage and power under our testing conditions. This behavior suggests that a lower limit to electrode dimensions exists for cells with single electrode pairs, below which neither a stable difference in oxygen partial pressure, nor an OCV, can be established. Conversely, increasing the electrode width imposes a penalty in the form of an increase in the ohmic resistance. However, both size limits can be circumvented by employing multiple pairs of microscale electrodes in an interdigitated configuration

Analysis of Nonlinear Thermoelastic Dissipation in Euler-Bernoulli Beam Resonators.

The linear theory of thermoelastic damping (TED) has been extensively developed over the past eight decades, but relatively little is known about the different types of nonlinearities that are associated with this fundamental mechanism of material damping. Here, we initiate the study of a dissipative nonlinearity (also called thermomechanical nonlinearity) whose origins reside at the heart of the thermomechanical coupling that gives rise to TED. The finite difference method is used to solve the nonlinear governing equation and estimate nonlinear TED in Euler-Bernoulli beams. The maximum difference between the nonlinear and linear estimates ranges from 0.06% for quartz and 0.3% for silicon to 7% for aluminum and 28% for zinc

Achieving High Quality Factor Without Vacuum Packaging by High Density Proof Mass Integration in Vibration Energy Harvesters

International audienc

Atomistic simulations of material damping in amorphous silicon nanoresonators

Atomistic simulations using molecular dynamics (MD) are emerging as a valuable tool for exploring dissipation and material damping in nanomechanical resonators. In this study, we used isothermal MD to simulate the dynamics of the longitudinal-mode oscillations of an amorphous silicon nanoresonator as a function of frequency (2 GHz–50 GHz) and temperature (15 K–300 K). Damping was characterized by computing the loss tangent with an estimated uncertainty of 7%. The dissipation spectrum displays a sharp peak at 50 K and a broad peak at around 160 K. Damping is a weak function of frequency at room temperature, and the loss tangent has a remarkably high value of ~0.01. In contrast, at low temperatures (15 K), [...] as the frequency increases from 2 GHz to 50 GHz. The mechanisms of dissipation are discussed

Thermal and Structural Considerations in the Design of a Rankine Vapor Microturbine

Abstract: This paper reports a global modeling and design approach to design a Rankine Microturbine for micro power generation from waste heat. The primary performance metrics and design challenges were identified, and models were developed for conjugate thermal and structural analyses. The results of these models, and their implications for size, shape, and materials selection, are presented. The need for low conductivity materials for the rotor and static structure of the microturbine is highlighted and a viable device configuration is proposed for elevated temperature operation

Self-assembly of micro- and nanoparticles on internal micromachined silicon surfaces

We report a simple and versatile processing technique, based on convective self-assembly, to form ordered arrays of colloidal micro- and nanoparticles on the internal surfaces of geometrically complex, bulk-micromachined silicon structures. The self-assembled layers are densely packed, exhibit excellent surface coverage over large (not, vert, similarmm2) areas, and contain a low density of crystallographic defects. Potential applications include, but are not limited to, (i) the incorporation of catalysts into microchemical reactors and (ii) colloidal lithography on internal surfaces for controlling biocompatibility in microsystems used in biology and medicine

Thermomechanical material properties at 300 K [19].

<p>Thermomechanical material properties at 300 K [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0164669#pone.0164669.ref019" target="_blank">19</a>].</p

Methods for Atomistic Simulations of Linear and Nonlinear Damping in Nanomechanical Resonators

Atomistic simulations can be used to compute damping from first principles and gain unprecedented insights into the mechanisms of dissipation. However, the technique is still in its infancy and many foundational aspects remain unexplored. As a step toward addressing these issues, we present here a comparative study of five different methods for estimating damping under isothermal conditions. Classical molecular dynamics was used to simulate the fundamental longitudinal-mode oscillations of nanowires and nanofilms of silicon and nickel at room temperature (300 K) in the canonical ensemble using the Nosé-Hoover thermostat. In the subresonant regime, damping was quantified using the loss tangent and loss factor during steady-state harmonic vibration. The quality factor was obtained by analyzing the spectrum of thermomechanical noise and also from the Duffing-like nonlinearity in the frequency response under harmonic excitation. In addition, the nonlinear logarithmic decrement was obtained from the Hilbert transform of freely decaying oscillations. We discuss the factors that must be considered while selecting simulation parameters, establish criteria for convergence and linearity, and highlight the relative merits and limitations of each method