A piezoresistive acceleration sensor and its manufacturing method

Abstract

The invention provides a piezoresistive acceleration sensor and a manufacturing method thereof. The sensor is improved by comprising a sensitive structure part. The left and right sides of a mass block in the sensitive structure are symmetrically provided with four mutually independent sensitive girders. Each sensitive girder is provided with a force-sensitive resistor. The two sides of the four sensitive girders are respectively provided with one support girder for supporting the mass block. The force-sensitive resistors are arranged on the mutually independent sensitive girders, so that the widths of the sensitive girders are reduced. Therefore, the influence of the sensitive girders on the stiffness coefficient of the sensitive structure is significantly reduced, so that the high sensitivity and the high figure of merit are realized. The sensitive girders are arranged closer to the centerline of the mass block, thus being smaller in deflection. The paraxial sensitivity is reduced. The support girders are closer to the edge of the mass block, thus being large in the arm of force. Therefore, the twist of the mass block, caused by the paraxial acceleration, can be better inhibited. The upper surfaces of the support girders are lower and are free of any oxidation layer. Therefore, the structural deflection, caused by the stress of the oxidation layer, can be reduced. The thickness of the sensitive girders is larger than the thickness of the support girders, so that the stress concentration can be achieved. As a result, the sensitivity and the figure of merit are improved.

Description

technical field [0001] The invention relates to a piezoresistive acceleration sensor and a manufacturing method thereof, in particular to a piezoresistive acceleration sensor which uses support beams and sensitive beams with different thicknesses to improve sensor performance and a manufacturing method thereof. Background technique [0002] Micromachined accelerometers are one of the pillar products in the field of Micro Electro Mechanical Systems (MEMS) technology. They have the advantages of small size, low cost, and high reliability. They are widely used in consumer electronics, automotive electronics, industrial control and It has a wide range of applications in national defense and other fields. Micromachined accelerometers can be divided into piezoresistive, piezoelectric, tunnel, capacitive, etc. according to the detection principle. Among them, the resistive accelerometer has the advantages of simple interface circuit, strong anti-interference ability, and simple pr...

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Problems solved by technology

[0010] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a piezoresistive acceleration sensor and its manufacturing method, which are used to solve the problem of the low merit value of the acceleration sensor in the prior art and the sensitivity to side-axis and overcome the difficulty of poor stress matching of traditional accelerometers

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