A composite sensor and its manufacturing method

Abstract

The invention relates to the technical field of sensor processing, and especially relates to a composite sensor and a production method. The composite sensor comprises a silicon substrate, and at least one first preset cavity, at least one second preset cavity and at least one third preset cavity in the silicon substrate. A plurality of semiconductor doped resistors for forming an acceleration sensor, a pressure sensor and a temperature sensor are formed at preset positions on the surface of the silicon substrate. The semiconductor doped resistors are electrically connected with conductive wires. A first release slot is formed on suspended silicon film at the upper side of the at least one first preset cavity. A second release slot is formed on suspended silicon film at the upper side of the at least one third preset cavity. The first release slot is combined with the second release slot, thus forming a suspended release structure. A limiting baffle plate is arranged out of the movable structure of the acceleration sensor. The limiting baffle plate has precise overload limiting protection effect. Moreover, an overload limiting device is simple in structure. The production process is relatively easy to grasp. The batch production of the product can be realized.

Description

technical field [0001] The invention relates to the technical field of sensor processing, in particular to a composite sensor based on MEMS processing technology and a manufacturing method. Background technique [0002] With the continuous development of MEMS technology and the maturity of silicon micromachining process, the composite sensor integrating silicon micromachining acceleration sensor, pressure sensor and temperature sensor is widely used because of its low price, high precision and suitable for mass production. . [0003] The Chinese invention patent with application number CN104058361A discloses a processing method for an integrated piezoresistive accelerometer and pressure gauge based on a prefabricated cavity SOI substrate, such as figure 1 As shown, the accelerometer includes a base made of silicon, a cantilever beam made of silicon, a sensitive mass made of silicon, a force sensitive resistor made of silicon, and metal leads. The pressure gauge includes a ...

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Problems solved by technology

[0004] The disadvantage of the above technical solution is that the overload protection of the acceleration sensor part depends on the prefabricated buried cavity depth c 1 and the distance from the protective cap to the top layer of the accelerometer mass block c 2 to fulfill

Usually buried cavity depth c 1 Formed by etching, and then the buried cavity depth c can be controlled during the fabrication process 1 ; while c 2 It is relatively difficult to control, because c 2 not only as deep as the cavity inside the cap c 3 It is also related to the mass block thickness c on the acceleration sensor 4 It is related, and usually the quality block is realized by electroplated metal. It is well known that it is difficult to maintain the relative consistency of the electroplating process. The manufacturing error of the electroplating process in the wafer-level process is usually about 15%, which leads to For processed sensors, some limit spacing c2 meets the limit distance requirements, while some limit spacing c 2 Too large, unable to achieve its limit protection purpose, and some limit spacing c 2 It is too small, which limits the normal range of the acceleration sensor, which in turn leads to a decrease in the detection accuracy of the acceleration sensor. A large number of substandard products

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