Failure dynamics of the IGBT during turn-off for unclampedinductive loading conditions

The internal failure dynamics of the insulated gate bipolar transistor (IGBT) for unclamped inductive switching (UIS) conditions are studied using simulations and measurements. The UIS measurements are made using a unique, automated nondestructive reverse-bias safe operation area test system. Simulations are performed with an advanced IGBT circuit simulator model for UIS conditions to predict the mechanisms and conditions for failure. It is shown that the conditions for UIS failure and the shape of the anode voltage avalanche-sustaining waveforms during turn-off vary with the IGBT temperature, and turn-off current level. Evidence of single- and multiple-filament formation is presented and supported with both measurements and simulations     

Scalability study of laser-induced vertical make-link structure

The scalability of a direct metal-to-metal connection between two different levels of metallizations has been extrapolated to be compatible with modern semiconductor fabrication technology. A simple equation to evaluate the scalability was formulated based on focused ion beam (FIR) cross-sectional images of larger link structures with various sizes. With a 0.6-μm-thick metal 1 line and a 0.5-μm-thick interlevel dielectric (ILD), a width of less than 0.5 μm is evaluated to be possible for the metal 1 line. Two limitations exist in the process of scaled-down link structures, which are the ratio of the thickness of ILD to the thickness of the metal 1 line, t_ILD/t _m, and the quality of laser beam parameters including the spot size and positioning error. However, modern processing technologies and advanced laser processing systems are considered to allow the scalability of a vertical make-link structure. Two layouts of two-level interconnects were designed with increased interconnect densities with a 1-μm pitch of a 0.5-μm-wide metal 1 line. These results demonstrate the application of commercially viable vertical linking technology to very large-scale integration (VLSI) applications     

Reliability of ultrathin silicon dioxide under combined substratehot-electron and constant voltage tunneling stress

An experimental investigation of breakdown and defect generation under combined substrate hot-electron and tunneling electrical stress of silicon oxide ranging in thickness from 2.0 nm to 3.5 nm is reported. Using independent control of the gate current for a given substrate and gate bias, the time-to-breakdown of ultrathin silicon dioxide under substrate hot-electron stress is observed to be inversely proportional to the gate current density. The thickness dependence (2.0 nm to 3.5 nm) of substrate hot-electron reliability is reported and shown to be similar to constant voltage tunneling stress. The build-up of defects measured using stress-induced-leakage-current and charge-pumping for both tunneling and substrate hot-electron stress is reported. Based on these and previous results, a model is proposed to explain the time-to-breakdown behavior of ultrathin oxide under simultaneous tunneling and substrate hot-electron stress. The results and model provide a coherent understanding for describing the reliability of ultrathin SiO₂ under combined substrate hot-electron injection and constant voltage tunneling stress     

Low-noise MEMS vibration sensor for geophysical applications

The need exists for high-sensitivity, low-noise vibration sensors for various applications, such as geophysical data collection, tracking vehicles, intrusion detectors, and underwater pressure gradient detection. In general, these sensors differ from classical accelerometers in that they require no direct current response, but must have a very low noise floor over a required bandwidth. Theory indicates a capacitive micromachined silicon vibration sensor can have a noise floor on the order of 100 ng/√Hz over 1 kHz bandwidth, while reducing size and weight tenfold compared to existing magnetic geophones. With early prototypes, we have demonstrated Brownian-limited noise floor at 1.0 μg/Hz, orders of magnitude more sensitive than surface micromachined devices such as the industry standard ADXL05     

Global stabilization of systems containing a double integrator using a saturated linear controller

In this paper, we present a Lyapunov function for systems containing a double integrator and with controller saturation. This Lyapunov function is composed of a positive-semidefinite quadratic term and an integral term. The main result provides a sufficient condition that guarantees a system with a double integrator can be globally stabilized by a saturating linear controller. For a triple-integrator system the saturated linear controller does not satisfy the sufficient condition, which agrees with the known result. Copyright © 1999 John Wiley & Sons, Ltd.