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0.5 um SOI CMOS for Extreme Temperature Applications
Authors
	Chaplygin Yu.A.
	Krupkina T.Yu.
	Krasukov A.Yu.
	Artamonova E.A.
Date of publication
	2016
Abstract
	Some applications require silicon devices and integrated circuits designed to work at extreme ambient temperatures. It is well known that increasing the temperature of the MOSFETs causes increasing the leakage current and decreasing the threshold voltage [1]–[2] of the devices. Silicon-on-insulator (SOI) substrate suppresses leakage current [3] but in turn may lead to self-heating effects also affecting the electrical characteristics of the transistors. In the paper we study the influence of process variation, self-heating effect and extreme ambient temperatures on the electrical characteristics of 0.5 um SOI MOSFETs. 2D models of 0.5 um SOI p- and nMOSFETs resulting from Sentaurus TCAD technology simulation have been created: the buried oxide thickness Tbox = 0.15 um, the thin substrate thickness Tsi = 0.19 um, the transistor’s channel length L = 0.5 um. The output current-voltage characteristics for different gate-source voltages and ambient temperatures T = -60ºC, +25ºC and +225ºC have been simulated and analysed. The simulation showed that the leakage current of the SOI nMOSFET is weakly dependent on the drain-source voltage Vds at all temperatures. At the same time the leakage current of the SOI pMOSFET increases significantly at the temperature T = -60ºC and Vds > 3V. At Vds = 5V the leakage current of SOI pMOSFET become comparable for temperatures T = 25ºC and -60ºC. Also at this voltage the temperature dependences of the output current-voltage characteristics for both transistors are approximately the same. Additionally the influence of the self-heating effect [4]-[9] on the transistor’s output characteristics at T= -60ºÑ, +25ºÑ è +225ºC have been studied. Simulation results shows that at T= -60ºC the self-heating has the greatest impact on the output current-voltage characteristic, which has a pronounced negative differential resistance section. The relative decrease in operating current caused by the self-heating effect in this case is about 24%. At the same time at T= +225ºC the self-heating has the least impact on the output characteristics and the relative decrease of the operating current is about 11%. The influence of channel doping dose and gate oxidation time on the threshold voltages, leakage currents and maximum drain currents at T= -60ºÑ, +25ºÑ è +225ºC has been calculated. For both transistors the threshold voltages are significantly reduced with increasing temperature from -60ºC to 225ºC: 0.4 V for the SOI-n- and p-MOS transistor. At the same time the leakage currents are increased by an average of 10 orders for the SOI-n-MOSFET and 4 orders for the SOI-p-MOS transistor and the saturation currents are 1.5-2-fold decreased.
Keywords
	The electrical characteristics of 0.5 um SOI CMOS transistors at the ambient temperatures -60°C, +25°C and +225°C have been studied using TCAD simulation tools. Results for the influence of technology and self-heating effect on the electrical characteristics of the CMOS transistors at the different ambient temperatures are presented.
Library reference
	Chaplygin Yu.A., Krupkina T.Yu., Krasukov A.Yu., Artamonova E.A. 0.5 um SOI CMOS for Extreme Temperature Applications // Problems of Perspective Micro- and Nanoelectronic Systems Development - 2016. Proceedings / edited by A. Stempkovsky, Moscow, IPPM RAS, 2016. Part 4. P. 10-15.
URL of paper
	http://www.mes-conference.ru/data/year2016/pdf/D056.pdf