The present invention discloses a
field effect transistor structure-based
pH sensing device and a manufacturing method thereof. The manufacturing method is as follows: firstly, a front
gate oxide layer and a gate layer are deposited on the surface of a
semiconductor layer of a
semiconductor substrate on an insulating layer, a gate
electrode structure is formed by
etching of the front
gate oxide layer and the gate layer; secondly, a source-drain structure is formed by
doping of the
semiconductor layer of the semiconductor substrate on the insulating layer on both sides of the gate
electrode structure, and the gate
electrode structure and the source-drain structure together form a field-effect
transistor structure; and further,
photolithography is performed on the back surface of a
silicon substrate on the insulating layer, a supporting substrate and a
buried oxide layer are etched until the lower surface of the semiconductor layer, and a back
gate oxide layer is deposited on the lower surface of the etched semiconductor layer to complete the preparation of the
pH sensing device. The method utilizes the contact between a solution to be tested and a back gate of the field-effect
transistor to form a double-electric-layer structure on the surface of the back gate, by changing of the
Zeta potential of the double-electric-layer on the surface of the back gate in different pH solutions, the
threshold voltage of the field-effect transistor can be changed, the change of the resistance of the sensing device under a fixed bias
voltage can be further led, the pH value of the solution can be tested.