Using the Hexagonal Layout Style for MOSFETs to Boost the Device Matching in Ionizing Radiation Environments

Abstract

This paper describes an experimental comparative study of the matching between conventional (rectangular gate shape) and Diamond (hexagonal gate geometry) n-channel Metal-Oxide-Semiconductor (MOS) Field Effect Transistors (MOSFETs), which were manufactured in an 130 nm Silicon-Germanium Bulk Complementary MOS (CMOS) technology and exposed to different X-rays Total Ionizing Doses (TIDs). The results indicate that the Diamond layout style with alpha () angle equal to 90˚ for MOSFETs is capable of boosting the device matching by at least 17% regarding the electrical pa-rameters studied (Threshold Voltage and Subthreshold Slope) as compared with the conventional MOSFET counterparts, considering that they present the same gate area, channel width, bias conditions and for the same TID. This is due to the Longitudinal Corner Effect (LCE). Parallel MOSFETs with Different Channel Length Effect (PAMDLE) and Deactivation of Parasitic MOSFETs in the Bird’s Beak Regions Effect (DEPAMBBRE) present in the structure of Diamond MOSFETs. Therefore, the Diamond layout style can be consid-ered an alternative hardness-by-design (HBD) layout strategy to boost the electrical performance and TID tolerance of MOSFETs enabling analog or radio-frequency CMOS inte-grated circuits (ICs) applications.