Method of fabricating an inertial sensor

Abstract

Fabrication of an inertial sensor comprising at least one measurement beam (23) and an active body formed of a proof body (13) and of deformable blades (14), said active body being maintained in suspension inside a hermetic enclosure via its blades (14), the measurement beam (23) linking a part of the proof body (13) to an internal wall of said enclosure, said measurement beam (23) exhibiting a thickness less than that of the proof body (13).

Description

technical field [0001] The invention relates to the field of inertial sensors, such as accelerometers or rate gyroscopes, formed in MEMS (“Micro Electro Mechanical Systems”) or NEMS (“Nano Electro Mechanical Systems”) technology. [0002] In particular, the invention relates to a method for producing an inertial beam measuring sensor resonant or having a varistor, for example piezoresistive. Background technique [0003] An inertial sensor, such as an accelerometer, is especially capable of measuring the acceleration of the object on which the accelerometer is mounted. Such sensors comprise in particular a proof mass (also called proof mass) joined to one or several measuring beams. As the sensor moves, the proof mass is subjected to inertial forces, causing tension in the beam. [0004] For resonant measuring beams, the tension caused by the mass of the proof mass causes a change in the frequency of the resonator. For variable resistance measuring beams, such as piezores...

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Problems solved by technology

However, small thickness polysilicon layers are still difficult to control, and their mechanical and electronic properties are not as good as monocrystalline silicon layers

Also, deposits this thin can be affected by tension, such as deformations that affect strain gage performance

Therefore, it is very difficult to obtain a strain gage with mechanical and electronic characteristics for optimum sensor sensitivity using this method

[0009] Such a solution is therefore unsatisfactory, since we have to choose between a low-thickness strain gauge that compromises the quality of the proof mass and a large mass proof mass that compromises the sensitivity of the strain gauge. choose

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