PH SENSOR WITH SUBSTRATE OR BONDING LAYER CONFIGURED TO MAINTAIN PIEZORESISTANCE OF THE ISFET DIE

摘要

Embodiments described herein provide for a pH sensor that is configured for use over a pressure and temperature range. The ISFET die of the pH sensor is bonded to the substrate of the pH sensor with a bonding layer that is disposed between the substrate and the ISFET die. The pressure and temperature change across the pressure and temperature range generates an environmental force in the pH sensor. Further, the substrate or the bonding layer or both change volume over the pressure and temperature range, and the substrate or the bonding layer or both are configured such that the volume change induces a counteracting force that opposes at least a portion of the environmental force. The counteracting force is configured to maintain the change in piezoresistance of the ISFET die from the drain to the source to less than 0.5% over the pressure and temperature range.