Smart-MEMS based inertial measurement units: gyro-free approach to improve the grade

Microsystem Technologies - Inertial measurement units (IMU) are essentially a combination of acceleration and rotation rate sensors, generating position and attitude information. For tactical and...     

TEM analysis of near-coincidence grain boundaries in silicon

High-precision characterization of grain boundaries with a deviation from the ideal coincidence is presented. The analysis is based on the shift of Kikuchi lines at grain boundaries. The accuracy was controlled using Frank's relationship applied to intrinsic secondary dislocations which accommodate the orientation deviation. An application is presented to coincidences with Σ = 25 and 3 observed in polycrystalline silicon.     

Noise analysis of a first-order thermal ΣΔ architecture for convective accelerometers

This paper presents the study of an original closed-loop conditioning approach for fully-integrated convective inertial sensors. The method is applied to an accelerometer manufactured on a standard CMOS technology using an auto-aligned bulk etching step. Using the thermal properties of the sensor, a first order sigma-delta modulator is built. This “electro-physical” modulator realizes an analog-to-digital conversion of the acceleration signal. Besides, the feedback mode of operation improves the sensor overall performance.     

A Behavioral Model of MEMS Convective Accelerometers for the Evaluation of Design and Calibration Strategies at System Level

This paper presents a behavioral model that can be used to improve the manufacturability of systems based on MEMS convective sensors. This model permits to handle faults related to process scattering, taking into account not only the electrical and lateral geometrical parameters but also the influence of the cavity depth. Moreover correlations between conductive and convective phenomena are included. The model is validated with respect to FEM simulations and a very good agreement is obtained between the behavioral model and FEM results. The proposed model can then be used in system-level simulations, for instance to evaluate the impact of process scattering on the performances of the sensing part and/or to investigate different design and calibration strategies with respect to the system robustness.     

Use of test structures for characterization and modeling of inter and intra-layer capacitances in a CMOS process

In this paper, we present a global approach for inter- and intralayer capacitance characterization and modeling. Using an accurate on-chip measurement method, we have characterized realistic test patterns, i.e., test patterns consistent with capacitive couplings encountered in a layout. These reference values have allowed us to point out some limitations of current models and to propose new simple analytical models suitable for small dimension capacitive patterns. This paper emphasizes inter- and intralayer modeling     

Electrical and photoluminescence properties of evaporated CuIn1−xGaxTe2 thin films

Polycrystalline thin films of CuIn_1−xGa_xTe₂ have been deposited by flash evaporation on Corning glass 7059 substrates at T_s=200°C. Hall and resistivity measurements have been carried out down to 77 K. These films are p-type and the variation of the resistivity may be linked to defects, disorder of the material or grain boundaries. The PL spectra of these films after annealing in argon atmosphere at T_a=450°C have showed a broad band emission between 0.98 and 1.12 eV in which the main peak appears at 1.05 eV (at 4.2 K).     

Cobalt intergranular segregation in WC-Co composites

Interfaces between carbide grains in the tungsten carbide-cobalt composite have been considered. Different techniques, such as transmission electron microscopy and energy dispersive X-ray analysis have been used to characterize the orientation relationship, the nature of the planes and the chemical composition of the grain boundaries.The cobalt concentration at WC-WC grain boundaries was determined by X-ray energy selective analysis in the TEM. Cobalt profiles were performed across low-angle grain boundaries, coincidence and general grain boundaries. Cobalt segregation was found whenever dislocations were imaged in the grain-boundary plane of a low-energy grain boundary. The segregation value was compared with the segregation ratio measured in special grain boundaries characterized by a coincidence site lattice.