Piezoresistive biaxial acceleration sensor chip and preparation method thereof

Abstract

The invention discloses a piezoresistive biaxial acceleration sensor chip and a preparation method thereof. The piezoresistive biaxial acceleration sensor chip comprises a sensing chip and a glass substrate which are bonded, wherein the sensing chip comprises a chip outer frame, fixed peninsulas, mass blocks, a support beam, piezoresistive micro beams and hinge beams; the inner walls of the chip outer frame are each provided with one of the fixed peninsulas, the eight mass blocks are arranged in the chip outer frame, a movement gap is formed between every two adjacent mass blocks, and every two mass blocks connected to the same fixed peninsula are connected into a whole through one hinge beam; one piezoresistive micro beam is connected between each mass block and the corresponding fixed peninsula; and each piezoresistive micro beam is provided with a piezoresistor, and the eight piezoresistors are connected with bonding pads through metal leads to form two Wheatstone full bridges. According to the piezoresistive biaxial acceleration sensor chip and the preparation method thereof, the supporting elements are separated from the sensitive elements, so that the cross sensitivity interference in the in-plane biaxial acceleration detection is reduced, and the measurement requirements on high sensitivity and high resonant frequency of the acceleration can be met.

Description

technical field [0001] The invention belongs to the technical field of measurement of micromechanical electronic sensors, and in particular relates to a piezoresistive biaxial acceleration sensor chip and a preparation method thereof. Background technique [0002] With the development of Micro Electro Mechanical Systems (MEMS) technology, acceleration sensors based on different principles have been widely used, such as piezoresistive, capacitive, electromagnetic, piezoelectric, resonant, fiber optic and thermal resistance, etc. Acceleration sensors with different sensitivity principles have different advantages and disadvantages. For example, piezoelectric accelerometers are widely used in vibration measurement due to their advantages such as wide measurement frequency range, large measurement range and no external power supply. With the development of the field of vibration detection, piezoelectric accelerometers cannot better meet the needs of vibration monitoring and fau...

AI Technical Summary

Problems solved by technology

With the development of the field of vibration detection, piezoelectric accelerometers cannot better meet the needs of vibration monitoring and fault diagnosis due to factors such as large size, poor compatibility with CMOS technology, and high signal processing costs; capacitive acceleration sensors It has the advantages of high sensitivity, small temperature drift, and low power consumption, but has a large input impedance, is easily affected by parasitic capacitance, is sensitive to electromagnetic interference in the surrounding environment, and has a low response frequency. The highly symmetrical structure requires an increase in chip structure. The complexity of the sensor, and the processing technology is difficult; the piezoresistive acceleration sensor is easily affected by temperature, but it has a wide measurement range, can measure static and dynamic signals, has good dynamic response characteristics, and simple processing circuits, etc.

[0003] The commonly used structures of traditional piezoresistive acceleration sensors include single cantilever beam, double cantilever beam, double-end fixed support beam, four-side four fixed support beam and other structures. Beams and double cantilever beam structures have high sensitivity, but low natural frequency and narrow frequency response range; fixed-supported beam structures such as double-ended fixed-support beams, four-sided four-fixed-support beams, and double-sided four-fixed-support beams have high natural frequencies, but low sensitivity

[0004] With the advancement of technology, the current piezoresistive acceleration sensors have been difficult to meet the requirements of high sensitivity, high natural frequency and low cross-sensitivity in different fields, such as automotive intelligent detection, high-speed precision machine tools, fault diagnosis and monitoring of high-speed moving parts, electronic Component vibration control, etc.

For the traditional piezoresistive acceleration sensor, because the sensitive element is generally made on the surface of the supporting structure, its natural frequency and sensitivity are mutually restricted, resulting in easy distortion during measurement. Therefore, research on acceleration sensors that can alleviate the contradictory relationship between natural frequency and sensitivity , it is of great significance to reduce the influence of cross-sensitivity and realize high-sensitivity and high-response measurement of acceleration

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