The aim of this project is the design and fabrication of two type of micromachined capacitive pressure sensor for industrial and biomedical application. The fabricated pressure sensors are based on the deflecting micromachined thin silicon diaphragm anchored to glass substrate, forming variable capacitor with the applied pressure. Silicon micromachining process allows the implamentation of thousands of pressure sensors on the same wafer , which is the main reason for low cost production.
The bulk micromachining technology and the boron etch-stop dissolved wafer process have been succesfully utilized in device fabrication. The dynamic ranges of the sensors designed for industrial applications vary between 0-50 mmHg and 0-1200 mmHg over atmospheric pressure, and each sensor accupies an area of 3.2 x 1.8 mm2. The new sensor structure for biomedical lapplications can be implanted inthe body and can be monitored telemetriclly without using any wire that breaks the skin. This is achieved by using a gold electroplated coil, which is fabricated to gether with the pressure sensor. This implantable sensor measured 1.5mm x 2.5mm x 0.5mm in size and provides a dynamic range of 0-50 mmHg over atmospheric pressure.
Figure shows batch fabricated twelve pressure sensors on a human finger. Die area measures 11.7 x 8.6 mm2.
- Process control