Biosensor devices and methods of forming the same

A method of forming a biosensor device comprising:

• forming a cavity, wherein the cavity comprises an opening that extends entirely through a first layer and a second layer, wherein the cavity is configured to receive one or more charged molecules;
• forming a transistor in the first layer, where the transistor includes source, drain, and channel regions that are spatially separated from the cavity in a lateral direction by an insulator material;
• and
• forming a gate of the transistor disposed below the cavity and extending between the cavity and the source, drain, and channel regions, wherein a voltage potential of the gate is based on a number of charged molecules in the cavity, the gate is above a top surface of a substrate, a top surface and a bottom surface of the cavity are both above a top surface of the gate, the source, drain and channel regions are within the second layer, and the gate is below a bottom surface of the second layer.

A method of forming a biosensor device comprising:

• extending a cavity through a first layer and a second layer, wherein the cavity is configured to receive one or more charged molecules;
• forming a transistor including source, drain, and channel regions that are spatially separated from the cavity by an insulator material;
• and
• forming a gate of the transistor, wherein the gate is disposed below the cavity and extends between the cavity and the source, drain, and channel regions, a bottom surface of the gate is above a top surface of a substrate, the cavity is above a top surface of the gate, the source, drain and channel regions are within the second layer, and the gate is below a bottom surface of the second layer.