Product news

A scalable piezoresistive MEMS technology platform for highly precise yet cost-effective sensors was developed at the CiS Forschungsinstitut für Mikrosensorik. The goal was to significantly reduce the zero offset typically found in piezoresistive Wheatstone bridges, as well as its temperature dependence, already at wafer and chip level. This reduces the need for complex external compensation, simplifies later sensor integration, and lowers costs.
The platform is based on micromachined structures with a thin membrane and is suitable for a wide range of applications, such as microforce measurement or highly precise differential pressure sensing. A particular focus was placed on a robust chip design that minimizes structural asymmetries, manufacturing tolerances, and temperature-sensitive effects. To achieve this, extensive simulations were carried out, various chip variants were designed, and numerous wafer technology process parameters were optimized and qualified.
As a result, offset values within the target range of ±1 mV/V were achieved, and their temperature dependence could be reproducibly limited over a range from -40 to 150 °C. For chips with larger deviations, additional integrated compensation structures were used. Through a stud-bumping process, small resistors can be selectively switched on or off to improve bridge balancing directly on the chip. In addition, micromachined fuses and microheaters were investigated as scalable options for on-chip compensation and self-test.
As a demonstrator, the platform achieved sensitivities of more than 2 mV/V/kPa when used as a differential pressure sensor in the low- to medium-pressure range.