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TCAD Study of Responsivity of n-channel MOS Dosimeter Fabricated in CMOS Processes
Authors
	Bekenova A.T.
	Artamonova E.A.
	Krasukov A.Yu.
Date of publication
	2022
DOI
	10.31114/2078-7707-2022-3-89-94
Abstract
	Radiation MOS dosimeters fabricated in standard CMOS processes are widely used in various fields due to low power consumption, small sizes, low cost. Also, it makes possibly of integrating the readout electronics and control circuits with the dosimeters on a single chip. The responsivity of a MOS transistor to total doses of ionizing radiation caused by the positive oxide charge accumulated in the oxide increases with the gate oxide thickness Tox. In order to achieve high responsivities, the dosimeters are usually built with oxide thicknesses from several hundreds of nanometers to few micrometers. These oxides are much thicker than the regular gate oxides available in standard CMOS process. Over the past decades researchers have proposed the variants of MOS dosimeters fabricated in standard CMOS processes. In this work we present the results of TCAD study of the VT shift and sensitivity of n-channel MOS dosimeter fabricated in standard CMOS process with LOCOS isolation – FOXFET. Thick field oxide thickness Tox in FOXFET acting as the gate oxide for the sensor. Two CMOS processes were considered with oxide thicknesses 400 nm and 650 nm. The results show that VT shift growing significantly with an increase of the radiation dose from 20 to 700 kRad – up to 40 V/Rad for Tox=650 nm and 12 V/Rad for Tox=400 nm. However, growth stops at higher doses due to oxide charge saturation with the dose. Responsivity decreases with the radiation dose, the greatest decline is observed at low doses up to 50 kRad. At the same time, responsivity of the dosimeter increases with a field oxide layer thickness. Thus, a CMOS dosimeter with a sensitivity of 47 to 122 μV/Rad for doses in the range of 20 to 1000 kRad can be obtained for the process with Tox=650 nm, and two times less for Tox=400 nm. Additionally, the dependences of FOXFET responsivity on local oxidation modes for 0.6 μm CMOS process with LOCOS isolation were obtained by technological and device modeling.
Keywords
	MOSFET, simulation, TCAD, radiation sensor, electrical specifications.
Library reference
	Bekenova A.T., Artamonova E.A., Krasukov A.Yu. TCAD Study of Responsivity of n-channel MOS Dosimeter Fabricated in CMOS Processes // Problems of Perspective Micro- and Nanoelectronic Systems Development - 2022. Issue 3. P. 89-94. doi:10.31114/2078-7707-2022-3-89-94
URL of paper
	http://www.mes-conference.ru/data/year2022/pdf/D033.pdf