Sensing Characteristic Enhancement of CMOS-Based ISFETs with Three-Dimensional Extended- Gate Architecture
Journal
IEEE Sensors Journal
Journal Volume
21
Journal Issue
7
Pages
8831-8838
Date Issued
2021
Author(s)
Abstract
As the CMOS-based ion-sensitive field-effect transistor (ISFET) is scaling down to achieve a compact sensing array with high spatial resolution, reduction of sensing layer capacitance attenuates capacitive coupling efficiency of environmental input signals and decreases sensitivity performance. To address this issue, a concept of three-dimensional (3D) sensing structure is proposed and examined in this study. This can increase the sensing layer capacitance for a given footprint area. Based on our designs, a series of 3D sensing structures can be implemented with a standard CMOS foundry service and CMOS-compatible post processes. Our experimental results show that an $8.5^{2}\mu \text{m}^{2}$ footprint design of the 3D sensing structure can obtain approximately 2-fold increase in transconductance compared with a traditional ISFET with the same footprint. This enables pH sensitivity to be improved 1.5-fold in current response and 1.15-fold in voltage response. Therefore, the proposed 3D-structure ISFET can pave the way toward an ISFET sensing array with high sensitivity and high spatial resolution. ? 2001-2012 IEEE.
Subjects
Capacitance; Image resolution; Ion sensitive field effect transistors; Capacitive couplings; Current response; High sensitivity; High spatial resolution; Sensing characteristics; Sensitivity performance; Threedimensional (3-d); Voltage response; CMOS integrated circuits
Type
journal article