X-ray Radiation Effects on Matching Properties of MOSFETs Implemented with Octagonal Layout Style: A Cluster-Based Statistical Approach

This work performs an experimental comparative study of the impact of X-rays ionizing radiation on the matching between Metal-Oxide-Semiconductor (MOS) Field Effect Transistors (MOSFETs), channel n, which were implemented with octagonal (Octo MOSFET, OnM) and conventional layout styles (Conventional MOSFET, CnM). Statistical techniques, including K -means clustering and ANOVA, were employed to analyze the electrical parameters of these devices, specifically those related to the saturation drain current (Idssat), maximum transconductance ($\text{gm}_{\max}$), and analogy efficiency (gm/Ids). The clustering methodology was instrumental in objectively quantifying the differences in their ionizing radiation response, validating the hypothesized separation, and precisely characterizing their respective variability, a key aspect of device matching. The results indicate statistically significant differences in these parameters between the devices. Notably, as the main results, the matching between OnM presents an X-ray radiation tolerance 1.742 times better than that measured for the matching between CnMs, demonstrating a lower variability and greater stability. Therefore, the octagonal layout style for MOSFETs can be considered an alternative strategy to boost the radiation-hardened-by-design (RHBD), mainly focusing on analog and radiofrequency Complementary MOS (CMOS) integrated circuits applications.