Nec Research & Development 

About: Nec Research & Development is an academic journal. The journal publishes majorly in the area(s): Interconnection & The Internet. Over the lifetime, 575 publications have been published receiving 3184 citations.

Pulse-time-modulated ECR plasma discharge for highly selective, highly anisotropic and charge-free etching

Abstract: Highly selective, highly anisotropic, notch-free, and charge-build-up damage-free silicon etching is performed by using Electron Cyclotron Resonance (ECR) Cl 2 plasma modulated at a pulse timing of a few tens of microseconds. A large quantity of negative ions are produced in the afterglow of the pulse-time-modulated plasma. The decay times of electron density, electron temperature, and sheath potential are considerably reduced, which is attributable to negative-ion generation. Furthermore, the pulse-time-modulated plasma reduces the time averaged sheath potential. As a result of these effects, charged particles in the sheath are strongly modified from the continuous discharge, and they should improve the selective etching in the pulsed ECR plasma and eliminate charge accumulation on the substrate.

Pivot friction compensation using an accelerometer and a disturbance observer for Hard Disk drives

Abstract: This paper is concerned with the combined use of an accelerometer and a Disturbance Observer (DOB) to compensate for pivot nonlinearities that are subject to uncertainties in Hard Disk Drives (HDDs). The DOB estimates the bias due to pivot nonlinearities such as friction, and this estimate becomes a feedback signal for bias cancellation. Experiments have confirmed that the cancellation scheme is effective in the frequency range from 0 to 700 Hz. Since the proposed cancellation scheme can be implemented as an analog system, it provides wider-bandwidth bias rejection and better settling performance than traditional bias compensation schemes such as integral action based on sampled position error signal. The proposed method can make the distribution of the positioning error at the end of high-speed track-to-track seeks much smaller than that when a digital integral action is used.