| Title |
The Characteristic of ITO-ISFET pH Sensor by Fluorination |
| Authors |
김대훈(Dae Hoon Kim) ; 송광섭(Kwang Soup Song) |
| DOI |
https://doi.org/10.5573/ieie.2023.60.5.81 |
| Keywords |
Indium tin oxide; ISFET; Fluorine treatment; Drift characteristic; Hysteresis characteristic |
| Abstract |
In this study, a fluorine surface modification method was used to increase the reliability of an ion sensitive field-effect transistor (ISFET) pH sensor. An indium tin oxide (ITO) thin film was deposited by RF sputtering method. An ITO-ISFET with a channel length of 80 μm and a width of 2000 μm was fabricated through a photolithography process. The pH sensitivity of the ITO-ISFET was 60.2 mV/pH, the drift characteristic was 4.1 mV/h, and the hysteresis characteristic was 21.1 mV. The gate channel surface of the ITO-ISFET was functionalized to improve the drift and hysteresis characteristics. Functionalization was performed using a high-frequency plasma treatment method in a C3F8 gas environment, and the fluorine-treated ITO thin film was evaluated using X-ray photoelectron spectroscopy (XPS). The ITO-ISFET functionalized with fluorine by the plasma treatment exhibited the pH sensitivity of 58.7 mV/pH. The drift and hysteresis characteristics were 2.6 mV/h and 4.0 mV, respectively. The reliability of the ITO-ISFET was increased by fluorine functionalization. |