Design, fabrication and characterization of CMOS ISFET for pH measurements
The Ion Sensitive Field Effect Transistor (ISFET) is a potentiometric pH sensor that is easily adapted to a wide range of chemical, biochemical and biomedical applications. The operation of an ISFET is based on the surface adsorption of charges from the test solution in the solid-electrolyte inte...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Subjects: | |
| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/12919/1/p.%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/12919/2/Full%20Text.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The Ion Sensitive Field Effect Transistor (ISFET) is a potentiometric pH
sensor that is easily adapted to a wide range of chemical, biochemical and
biomedical applications. The operation of an ISFET is based on the surface
adsorption of charges from the test solution in the solid-electrolyte interface that
is part of the gate of the ISFET. As a result of this process, the threshold
voltage of the ISFET is modulated.This thesis describes the design, simulation,
fabrication and characterization of ISFET for pH measurement of an aqueous
solution. Prior to fabrication, the ISFET is simulated via TCAD TSUPREM4
process and MEDICI device simulator. The ISFET is fabricated in-house in the
Micro Fabrication Cleanroom Laboratory (MFCL) at Universiti of Malaysia Perlis
(UniMAP) by using CMOS fabrication technology. This goal is achieved due to
the compatibility of ISFET and CMOS. Silicon nitride was used as an ion
sensitive membrane and it was deposited by using Plasma Enhanced Chemical
Vapour Deposition (PECVD) technique. A total of six masks were used in this
fabrication to create the CMOS ISFET. The ISFET fabricated is aimed at pH
measurement of aqueous solution. In order to obtain an accurate
characterization of the ISFET, a semiconductor characterization system (SCS)
comprises of a micro probe station and a parameter analyzer was utilized. For
the analysis of ISFET in test solution, an Ag/AgCl electrode is used as a
reference electrode and three types of standard aqueous pH buffer solutions of
pH 4, pH 7 and pH 10 were used during the experiment of ISFET analysis. The
sensitivity of the ISFETs measured is 40mV/pH for n-channel ISFET and
30mV/pH for p-channel ISFET. These results demonstrate that the in-house
fabricated CMOS ISFET is functional as expected. |
|---|