Ion-sensitive field effect transistor and preparation method thereof

Abstract

The invention relates to a transistor, and discloses an ion-sensitive field effect transistor. The ion-sensitive field effect transistor comprises a semiconductor substrate 202, and a source 101 and a drain 102 which are located on the semiconductor substrate 202 and formed by doping; a groove structure etched to the interior of the semiconductor substrate 202 is arranged between the source 101 and the drain 102, an ion-sensitive membrane 103 is formed on the surface of the groove structure, and thus a gate insulating layer is formed. Because the groove structure is etched to the interior of the semiconductor substrate 202 with a certain depth, the structure can play a role of shielding and protecting measured hydrogen ions in a solution 201, so that interference of an electromagnetic field in the surrounding environment can be avoided when the concentration of the hydrogen ions is measured, and thus the accuracy and the repeatability of measurement results are effectively improved.

Description

technical field [0001] The invention relates to a field effect transistor, in particular to an ion sensitive field effect transistor and a preparation method thereof. Background technique [0002] In the prior art, the structure of the Ion Sensitive Field Effect Transistor (ISFET) device is very similar to that of the Metal Oxide Semiconductor Field Effect Transistor (MOSFET) without the metal gate, such as figure 1 As shown in Fig. 2, its gate insulating layer is a planar part between the source electrode 101 and the drain electrode 102, and a layer of sensitive layer 103 covered on the gate insulating layer directly contacts with the measured solution 201, due to the hydrogen in the measured solution 201 In the presence of ions, a tiny Nernst response potential sensitive to hydrogen ions is induced on the interface between the ion-sensitive membrane 103 and the measured solution 201: [0003] Φ I = Φ ...

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Problems solved by technology

[0005] Since the measurement of the concentration of hydrogen ions present in the solution 201 is easily disturbed by the surrounding electromagnetic field, and in the prior art, because the gate insulating layer of the ISFET device is a planar area, it cannot counteract the hydrogen ions in the solution 201 to be measured. The shielding effect of the surrounding electromagnetic field, and the Nernst response potential between the ion-sensitive membrane 103-the measured solution 201 interface is very small, and a slight deviation will make the measurement result unstable, poor in repeatability, and low in reliability

[0006] There are also great defects in the formation of the source and drain in the prior art. The current process is to dope the positions corresponding to the source and drain on the semiconductor substrate 202, leaving a space for the gate insulating layer in the middle, so that The method will cause the diffusion of source and drain doping to the channel region, affecting the actual effective size of the channel

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