PPT07 Series Silicon Piezoresistive Sensors for Semiconductors

    The PPT07 series semiconductor silicon piezoresistive sensor with Wheatstone bridge signal adopts a Wheatstone bridge composed of semiconductor resistance strain gauges as the force-to-electricity conversion measurement circuit, featuring high measurement accuracy, low power consumption, and extremely low cost.

    Both the upper and lower layers of the silicon piezoresistive diffused silicon pressure sensor are made of glass, with the middle layer being a silicon wafer. The central part of the silicon wafer is shaped like a teacup, commonly referred to in the industry as a silicon cup. The upper part of the stressed silicon membrane is a cavity, and the pressure environment here determines the type of pressure measured by the pressure transmitter. For example, in a general gauge pressure transmitter, this cavity is connected to the external environment during production, meaning the pressure in the cavity is actually the atmospheric pressure of the external environment. In another example, for an absolute pressure transmitter, when we want the pressure value to be referenced to a standard atmospheric pressure value, this cavity is made into a sealed chamber and artificially filled with a standard atmospheric pressure value.

    On the side where the stressed silicon membrane connects to the vacuum cavity, a resistance strain gauge bridge circuit is formed through photolithography. When external pressure enters the silicon cup of the sensor through the pressure cavity, the stressed silicon membrane slightly bulges under the force, causing elastic deformation. As a result, the resistance of the four resistance strain gauges changes, disrupting the balance of the original Wheatstone bridge circuit, and the bridge outputs a voltage signal proportional to the pressure.

    The pressure of the diffused silicon pressure sensor acts directly on the sensor's diaphragm (stainless steel or ceramic), causing the diaphragm to produce micro-displacement proportional to the medium pressure, thereby changing the sensor's electrical value. An electronic circuit is used to detect the pressure change and convert it into a standard measurement signal corresponding to the pressure.