Biasing

About: Biasing is a research topic. Over the lifetime, 29422 publications have been published within this topic receiving 301035 citations.

Electronic structure and spin-dependent tunneling conductance under a finite bias

Abstract: We present a spin-polarized self-consistent density functional theory (DFT) method for calculation of the electronic structure and transport properties of a system under a finite bias voltage. This method is implemented within the layer Korringa-Kohn-Rostoker approach. We calculate the tunneling conductance and the magnetoresistance (MR) of Fe/FeO/MgO/Fe tunneling junctions as functions of bias voltage. We find that the change in the electronic structure is minimal as a function of bias. The effective capacitance is consistent with the dielectric constant of MgO. The tunneling conductance is highly nonlinear. At low biases the TMR ratio is greatly reduced due to the large contribution to the tunneling current from interface resonance states. This contribution diminishes as the bias voltage increases, leading to an increase of the TMR ratio as a function of bias.

Adaptive control of operating and body bias voltages

Abstract: Adaptive control of operating and body bias voltages. In accordance with a first embodiment of the present invention, a desirable operating frequency for the microprocessor is determined. Information stored within and specific to the microprocessor is accessed. The information can comprise coefficients of a quadratic approximation of a frequency-voltage characteristic of the microprocessor for a set of body biasing conditions. An efficient voltage for operating the microprocessor at the desirable operating frequency is computed. The microprocessor is operated at the efficient voltage and the set of body biasing conditions.

Ion bombardment energy and SiO2/Si fluorocarbon plasma etch selectivity

Abstract: The role of ion bombardment in the plasma etch selectivity of silicon dioxide to silicon has been investigated in a CHF3/H2 plasma using a method that produces a narrow ion energy distribution (IED) at the substrate surface. The effects of the narrow IED is compared with the broad, bimodal IED produced by the conventional sinusoidal bias voltage wave form (at 5 and 20 MHz). A comparison of the etch rate versus the average ion bombardment energy shows a higher ion energy threshold for etching, a larger gap between the thresholds for the two materials, and a high selectivity over a wider range of bias voltage with the narrow IED. A physical explanation of the observed phenomena is proposed. Additionally, reported models of the reactive sputter etch rate as a function of ion energy are used to show that the etch rate in this regime is higher for a narrow IED than for a broad one.

CMOS substrate biasing for threshold voltage control

Abstract: A semiconductor device includes a PMOS transistor and an NMOS transistor. In a standby state, a potential of Vcc level is applied to the substrate of the PMOS transistor and a potential of Vss level is applied to the substrate of the NMOS transistor. Therefore, the voltage between the source and substrate of the P and NMOS transistors becomes 0 V. In an active state, potentials that render the voltage between the source and substrate lower than the built-in potential are applied to respective substrates of the P and NMOS transistors. Therefore, the threshold voltage of the transistor is lowered in an active state than in a standby state, and almost no leakage current flows between the source and substrate.