The present invention relates generally to micro-electronic mechanical systems (MEMS), and more particularly to air pressure sensors with temperature compensation.
With the continuous development of semiconductor technology, among the motion sensors available in the market, smartphones, CMOS integrated circuits and MEMS devices are the mainstream products with the most technological advance. The development of motion sensors tends towards smaller size, high quality and high performance, and high resistant to wear and tear.
MEMS pressure sensors are widely used in automotive electronics, such as tire pressure monitoring systems (TPMS), engine oil pressure sensors, car brake system air pressure sensors, automotive engine intake manifold pressure sensors (TMAP), common rail pressure sensors of diesel engines. Other MEMS pressure sensors are found in consumer electronics, such as fetal monitoring instruments (manometers), blood pressure monitors, kitchen scales, washing machines, dishwashers, refrigerators, microwave ovens, vacuum cleaners, washing machines, water dispensers, solar water heaters with level control pressure sensors; and in industrial electronics, such as digital pressure gauges, digital flow meters, industrial weighing of ingredients, and so forth.
A typical MEMS capacitive pressure sensor includes a sense capacitor Cs and a reference capacitor Cr. An ambient pressure can be measured by the capacitive difference between the sense capacitor Cs and the reference capacitor Cr. However, the structures of the sense capacitor Cs and the reference capacitor Cr differ from each other, so that the sense capacitor Cs and the reference capacitor Cr have different temperature variation characteristics that cannot be uniformly compensated for. Thus, the temperature offset between the sense capacitor Cs and the reference capacitor Cr results in measurement errors that affect the sensor reliability.
In general, a capacitive pressure sensor is susceptible to ambient temperature. The cavity of the capacitive pressure sensor is under a thermal expansion and contraction, leading to changes in the sensing capacitor Cs.
In view of the foregoing, there is a need for a novel method and apparatus for manufacturing a semiconductor device that can overcome the deficiencies of the prior art.