Micro mechanical capacitance type acceleration transducer, and fabricating method

Abstract

A method for preparing acceleration transducer of micromechanical capacity type includes forming rectangular mass block with no lobe compensation on single crystal silicon pellet by utilizing aeolotropic corrosion technique based on elastic beams being alternatively distributed at top and bottom surfaces of active mass block, forming straight elastic beam at two said surfaces of mass block, applying silicon-silicon bond technique to realize bond of three-layers silicon pellet, depositing lead wire pad of top electrode and active electrode and realizing electric signal isolation between two said electrodes.

Description

technical field [0001] The present invention relates to a micro-mechanical capacitive acceleration sensor and its manufacturing method. More precisely, the present invention uses silicon anisotropic corrosion as the key technology to manufacture the structure and manufacturing method of the micro-mechanical capacitive acceleration sensor. It belongs to the field of microelectromechanical systems. Background technique [0002] Silicon micro-accelerometers are very important micro-inertial devices that can be used in automobiles, robots, and various guidance and measurement and control systems. According to the sensitive principle, micromachined acceleration sensors can be roughly divided into: piezoresistive, piezoelectric, thick film strain gauge, electromagnetic, thermocouple, resonator and capacitive. Among them, the capacitive acceleration sensor can be divided into force balance type and non-force balance type. The movable mass forms a movable electrode of the variable...

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Problems solved by technology

This method makes the design of the device more complicated, and the size and shape control is more difficult

At the same time, when they made devices with beams on both sides of the mass block, they used two silicon wafers to etch the pattern of the mass block on one side respectively, and then performed silicon-silicon bonding to form a middle movable electrode with beams on both sides. This is undoubtedly Added to the complexity of the manufacturing process

Moreover, when making elastic beams and mass blocks, it is often carried out in two steps, first corroding the mass block pattern, and then using dry etching technology to make elastic beams, such as W.S.Henrion, et.al, Sensors structure with L-shaped springlegs, US Patent No.5,652,384, which also increases the complexity of the process, and requires the use of expensive equipment, increasing the cost of device manufacturing

[0005] In the manufacture of elastic beams, in the past, a highly doped self-stopping corrosion method (including the above two patents) was often used. Although the described method can control the thickness of the beam within a small range, due to the doped Inhomogeneity leads to inconsistencies in the thickness of the beam, and more importantly, doping introduces stress, which reduces the sensitivity of the device (L.Bruce Wilner, Differential capacitive transducer and method of making, US Patent no.4,999,735)

[0006] In the manufacture of the electrodes of the upper electrode plate, the middle movable electrode plate and the lower electrode plate, the previous electrode manufacturing methods are relatively complicated, such as W.S.Henrion, et.al, Sensors structure with L-shapedspring legs, US Patent No.5,652,384, They lead the wires out from the bonding surface and then through the side wall of the step, which increases the difficulty and complexity of the process

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