Microelectronics technologies allow the creation of miniature accelerometers (MEMS structures) with stable metrological characteristics and other technical parameters allowing their use in a wide variety of technical devices, and solve a variety of scientific, technical and production problems.
As an example, consider some of the types of beam accelerometer based on silicon structures. Integral Beam accelerometer on silicon structures is mikrokonstruktsiyu (Fig. 1). It consists of a silicon crystal, oriented in the (100) plane. In the crystal using anisotropic etching made beam concentrator stress and massive part - the inertial mass, which can be done either with a silicon beam, or other material such as gold, as shown in Fig. 1. Beam is separated from the circular base of a slot. Silicon crystal is closed at the top and bottom glass lids that have etched cavities that form a closed chamber that protects tenzoelement beam and from the external environment and limiting the free running beam with overload. The covers are connected to silicon by anodic landing. On the top cover, in addition, made contact pads, joined by external wire leads. Dimensions accelerometer 2x3x0, 6 mm, weight 0.02 g, measurement range acceleration from 0.1 to 500 m/cm^2, in the frequency range from 0 to 100 Hz.
Fig. 1. The design of the integral beam accelerometer:
1 - pads, 2 - p + - Region 3 - p - region, 4-bar, 5 - air gap 6 - silicon, 7 - recess in the lid, 8 - air gap 9 - flywheel, 10 - conductor adhesive, 11 - glass cover
Integral Beam accelerometer. Integral Beam mehanoelektrichesky converter (Fig. 2) (MEMS transducer) is a tiny silicon chip, which is integral with its supporting base is made thin beam deflected under the influence of acceleration. Beams are connected at one end to the base, and the other three sides separated from the base of a thin slit aperture. In the place of fixing the beam is made of stress concentrator. The sensitive element is a full bridge circuit tensoresistance made by planar technology of integrated circuits in the beam close to the surface and place it secured. Gage made by ion implantation of impurities, which will significantly simplify the technology of manufacturing transformers.
Such Beam transducer can be used as a linear accelerometer, vibration transducer, the transducer position in space, etc. For example, if you use it as an accelerometer it has the following characteristics: the die is 5x2,5x0,3 mm thick beams 10-20 microns minimum measured acceleration to 10 2 m/s^2 (can be increased up to hundreds and thousands of m/s^2) natural frequency of 1 to several hundred kilohertz.
Fig. 2. The integral beam accelerometer:
References: V.I.Vaganov. Integral tensoconverters. Accelerometer