Experimental study of the influence of X-ray ionizing radiations on Mosfets with octagonal gate layout style with 130 NM silicon-germanium CIS CMOS fabrication technology

The application of the octogonal gate layout style is an alternative to improve the electrical performance of MOSFETs and increase the tolerance of these devices to ionizing radiation, mainly by the new effects LCE, PAMDLE and DEPAMBBRE present in its structure. Therefore, the application of this layout can improve the performance of analog and digital integrated circuits, without causing any additional cost to the current, sophisticated and established manufacturing processes of ICs CMOS. Known as MOSFET Octo (OM), this MOSFET presents a better electrical performance than the one found in the conventional (rectangular gate layout) MOSFETs (CM), and it is a great alternative to increase tolerance to ionizing radiations. This work presents experimental comparative studies, presenting electrical performance data before and after X-rays irradiation for OM and CM, considering the same gate area, channel width and bias conditions. The OM presented better electrical performance and better tolerance to X-rays ionizing radiations than CM (considering the same bias conditions and same exposure to ionizing radiation conditions). When compared to the CM with the same gate area, channel width and bias conditions, the OM presented, for example, 138% higher on-state drain current, 9% lower off-state drain current and 48% lower on-state resistance. With regard to the variations of the electrical characteristics due to TID, the OM presented better results compared to the CM, considering the same bias conditions and exposure to ionizing radiation. The slope of the subthreshold varied about 2 times less in the OM in floating mode. The IOFF varied about 6,5 times less in the OM in ON bias mode. The ILEAK varied about 3,5 times less in the OM in OFF bias mode. The studies of the effects of TID on MOSFETs were performed for a TID of the order of Mrad in the study when the devices were non-biased (in floating) and of the order of krad in the studies of biased devices in ON, OFF and Analog modes. The results of this study indicate the Octo MOSFET as an alternative device for space, medical and nuclear CMOS ICs applications. (author)