Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement

The design and fabrication of n-ISFET using Si₃N₄/SiO₂ structure for pH measurement has been carried out. In general Ion Sensitive Field Effect Transistor (ISFET) is a potentiometric pH sensor which widely used in chemical, biochemical and biomedical applications due to its advantages such as small...

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Main Author:	Nur Syuhada, Md. Desa
Format:	Thesis
Language:	English
Subjects:	pH sensor Ion Sensitive Field Effect Transistor (ISFET) Silicon Thin films ISFET device pH detection
Online Access:	http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/2/Full%20text.pdf
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spelling	my-unimap-324702014-03-09T13:04:51Z Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement Nur Syuhada, Md. Desa The design and fabrication of n-ISFET using Si₃N₄/SiO₂ structure for pH measurement has been carried out. In general Ion Sensitive Field Effect Transistor (ISFET) is a potentiometric pH sensor which widely used in chemical, biochemical and biomedical applications due to its advantages such as small size, low power consumption, robustness, and fast response time over the ion-selective electrode (ISE). In this study, the ISFET was designed and fabricated in-house in Micro Fabrication Cleanroom Laboratory using a standard Complementary Metal Oxide Semiconductor (CMOS) processes fabrication except the gate area was replaced by reference electrode, sensing membrane and electrolyte under test. The main objective of this study is to present a concept, the design, fabrication and testing appropriate to process flow in fabricating the n-ISFFET on silicon wafer, which will finally be characterized using a suitable test methodology. Hence, fabrication on p- type <100> 4 inch silicon wafer by photolithography, wet chemical etching, thermal oxidation, diffusion and metallization with focus on a pH measurement has been executed.The n-ISFET was operated when the surface absorption of the charges in the electrolyte under test simultaneously interact with both reference electrode and surface sensing membrane. Overall process has 5 mask levels consist of source mask and drains mask, gate mask, contact mask and metallization mask. The fifth mask was used to find the best thickness of silicon nitride for sensing membrane layer and 50 nm was selected. For sensing material, SiO2 insulator layer was used and later deposited on top with Si3N4 insulator layer by Plasma Enhanced Chemical Vapor Deposition (PECVD). The latter layer serves as a pH sensitive membrane. The electrical tests were performed using buffer solutions with varying pH values, indicated that the transistor can be employed to measure the pH of solutions at room temperature. The interaction between these methods will modulate a threshold voltage and simultaneously will extracted the output (IdVd) and transfer (IdVg) characteristic curves at three differences channel length; 250μm, 300 μm and 500 μm respectively.The best pH sensitivity achieved at the channel length 500 μm with the measurement value equal to 54.43 milivolt per pH (mV/pH). Universiti Malaysia Perlis (UniMAP) 2013 Thesis en http://dspace.unimap.edu.my:80/dspace/handle/123456789/32470 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/1/Page%201-24.pdf 2c4365e3ba1b4acd5f9b13a2cd3e34f4 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/2/Full%20text.pdf d30bc20e8abd21fa14387fc27fb46950 http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/3/license.txt 8a4605be74aa9ea9d79846c1fba20a33 pH sensor Ion Sensitive Field Effect Transistor (ISFET) Silicon Thin films ISFET device pH detection Institute of Nano Electronic Engineering
institution	Universiti Malaysia Perlis
collection	UniMAP Institutional Repository
language	English
topic	pH sensor Ion Sensitive Field Effect Transistor (ISFET) Silicon Thin films ISFET device pH detection
spellingShingle	pH sensor Ion Sensitive Field Effect Transistor (ISFET) Silicon Thin films ISFET device pH detection Nur Syuhada, Md. Desa Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement
description	The design and fabrication of n-ISFET using Si₃N₄/SiO₂ structure for pH measurement has been carried out. In general Ion Sensitive Field Effect Transistor (ISFET) is a potentiometric pH sensor which widely used in chemical, biochemical and biomedical applications due to its advantages such as small size, low power consumption, robustness, and fast response time over the ion-selective electrode (ISE). In this study, the ISFET was designed and fabricated in-house in Micro Fabrication Cleanroom Laboratory using a standard Complementary Metal Oxide Semiconductor (CMOS) processes fabrication except the gate area was replaced by reference electrode, sensing membrane and electrolyte under test. The main objective of this study is to present a concept, the design, fabrication and testing appropriate to process flow in fabricating the n-ISFFET on silicon wafer, which will finally be characterized using a suitable test methodology. Hence, fabrication on p- type <100> 4 inch silicon wafer by photolithography, wet chemical etching, thermal oxidation, diffusion and metallization with focus on a pH measurement has been executed.The n-ISFET was operated when the surface absorption of the charges in the electrolyte under test simultaneously interact with both reference electrode and surface sensing membrane. Overall process has 5 mask levels consist of source mask and drains mask, gate mask, contact mask and metallization mask. The fifth mask was used to find the best thickness of silicon nitride for sensing membrane layer and 50 nm was selected. For sensing material, SiO2 insulator layer was used and later deposited on top with Si3N4 insulator layer by Plasma Enhanced Chemical Vapor Deposition (PECVD). The latter layer serves as a pH sensitive membrane. The electrical tests were performed using buffer solutions with varying pH values, indicated that the transistor can be employed to measure the pH of solutions at room temperature. The interaction between these methods will modulate a threshold voltage and simultaneously will extracted the output (IdVd) and transfer (IdVg) characteristic curves at three differences channel length; 250μm, 300 μm and 500 μm respectively.The best pH sensitivity achieved at the channel length 500 μm with the measurement value equal to 54.43 milivolt per pH (mV/pH).
format	Thesis
author	Nur Syuhada, Md. Desa
author_facet	Nur Syuhada, Md. Desa
author_sort	Nur Syuhada, Md. Desa
title	Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement
title_short	Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement
title_full	Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement
title_fullStr	Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement
title_full_unstemmed	Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement
title_sort	design and fabrication of n-isfet using si₃n₄/sio₂ structure for ph measurement
granting_institution	Universiti Malaysia Perlis (UniMAP)
granting_department	Institute of Nano Electronic Engineering
url	http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/32470/2/Full%20text.pdf
_version_	1747836801863647232

Design and fabrication of n-isfet using SI₃N₄/SIO₂ structure for pH measurement

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