Marco Dienel

Bonding and deep RIE: a powerful combination for high-aspect-ratio sensors and actuators

In this paper we present the very promising results for two methods of the so-called Bonding and Deep RIE (BDRIE) technology, characterised by bonding of two wafers with pre-patterned vertical gaps and subsequent RIE trench etching of the active layer. In case of the anodically bonded silicon-glass compound detection electrodes for vertical movement are integrated. The silicon layer contains the movable structure as well as drive and detection electrodes for lateral movement. It is advantageous that finally the mechanical active elements consist of single crystalline silicon without any additional layers. The BDRIE approach allows a great variation of parameters. The active layer thickness can be defined due to application issues. Our examples show active layers thickness ranging from 30 up to 200 μm, patterned by dry etching steps with maximum aspect ratio between 20:1 and 30:1. Structures with trench width variations of more than 50 (widest/smallest trench) have been fabricated successfully. Methods and results of preventing notching and backside etching of the active layer are presented as well. The size of the vertical gap can be as small as 1.5 μm for a very sensitive detection or several tens or hundreds of microns in order to reduce damping and parasitic capacitance. Holes for release in the movable structure are not necessary and will therefore not restrict the design. However, restrictions are given by the minimum size of bond area and the relation between layer thickness, free standing area above the groove and bond pressure, which are discussed within the paper. Applications of BDRIE are inertial sensors like gyroscopes, step-by-step switchgears as well as micro mirrors.

SystemC-AMS Assisted Design of an Inertial Navigation System

This paper presents an approach for modeling and realization of an inertial navigation system. This system consists of two new 2-D acceleration sensor arrays, three gyroscopes, digital error correction, gravitation compensation, supporting point inclusion, and software application. Modeling is achieved using SystemC-AMS for analog parts and SystemC for digital and software components. The model is simulated and verified by stimulating with different accelerations and rotations representing sensor movements

Modeling of a new 2D Acceleration Sensor Array using SystemC-AMS

This paper presents an approach for modeling and simulation of a new 2D acceleration sensor array using SystemC-AMS. The sensor array consists of six single acceleration sensors with different detection axes. These single sensors comprise of four capacitive segments and one mass segment, aligned in a semicircle. The redundant sensor information is used for offset correction. Modeling of the single sensors is achieved using sensor structure simplification into 11 points and analytic equations for capacity changes, currents and torques. This model was expanded by a PWM feedback circuit to keep the sensor displacement in a linear region. In this paper the single sensor model is duplicated considering different positions of the seismic mass resulting in different detection axes for the single sensors. The measured accelerations of the sensors are merged with different weights depending on the orientation. This also reduces calculation effort.

MEMS acoustic emission sensor with mechanical noise rejection

The presented paper describes the use of a new approach to develop a high frequency acceleration sensor with good low frequency noise rejection and in contrast to conventional resonant sensors a short settling time, as it is needed for acoustic emission testing.