When the pressure sensor is not under pressure, its output voltage should be zero. It is made by ion beam sputtering and photolithography Sputtering thin film pressure sensor The process can not guarantee the uniform resistance of the four arms of Wheatstone bridge, and the balance condition of the bridge can not be satisfied. Therefore, even if the sensor is not under pressure, the sensor in operation will have output signal.
In order to control the "zero point output" within a certain range, a "zero compensation" must be introduced when making the sensor, that is, an external resistance is connected to make the Wheatstone bridge reach the balance state as far as possible. However, the temperature drift of the sensor changes due to the difference of the resistance temperature coefficient between the external resistance material and the film resistance. The larger the resistance of external resistance, the greater the influence on temperature drift. In order to make the temperature drift meet the requirements, it is necessary to use external resistance to compensate temperature. The connection of the temperature compensation resistor will affect the mismatch of the zero compensation resistance, and the two affect each other. Therefore, it must be adjusted repeatedly to meet the requirements of zero point output and temperature drift. It can be seen that "zero compensation" and "temperature compensation" are time-consuming and laborious in the manufacturing process of the sensor, which not only increases the cost input, but also has a negative impact on the quality and stability of the sensor. It is pointed out that "zero point and temperature compensation must be carried out in the manufacture of the sensor. For the pressure sensor, the additional balance and compensation resistance may be the most unstable factor in the system."
If most of the zero compensation resistors can be directly made on the pressure chip, it will certainly be conducive to the improvement of the sensor technology and quality. After analyzing the possibility of this idea, making zero compensation resistor on pressure chip is regarded as one of the key technologies of pressure chip process research. This article comes from Zetian sensor, please keep the source.