Patent ID: 8878257

Claim:
An ISFET structure comprising: a substrate; a source region and a drain region formed within the substrate and having a channel region provided therebetween; a gate dielectric layer formed over the channel region; a floating gate structure formed on the gate dielectric over the channel region, the floating gate structure being electrically coupled to a first conductive structure configured to electrically communicate with a fluid having an ion concentration; and at least one control gate structure formed at least partially in the substrate and electrically coupled to the floating gate structure, the control gate structure configured to accept a voltage bias and to cause the movement of charge between the floating gate structure and the control gate structure in response to the voltage bias; wherein the at least one control gate structure comprises a control gate electrode coupled to the substrate via a conductive interconnect, and a capacitor structure formed by the substrate, the floating gate, and an oxide layer provided therebetween.