MEMS sensors from epitaxially grown piezoresistors

Stanford engineers have created a patented method for fabricating highly sensitive piezoresistors on vertical walls of microstructures by epitaxial growth of doped silicon. In-plane inertial sensors produced with this technique are up to 7 times more sensitive with a lower noise level than their ion-implanted counterparts. These benefits are achieved by growing mono-crystalline piezoresistors on a mono-crystalline substrate (epitaxial crystal growth), which creates an efficient, high-quality sensing structure. End user applications for this technology include accelerometers, gyroscopes and shear stress sensors.

Stage of Research
The inventors built and tested the piezoresistors and demonstrated sensitivity and resolution comparable to single-crystal ion implanted piezoresistors and better than most polysilicon or diffusion-based piezoresistors.