Random telegraph noise in nanometer-scale CMOS transistors exposed to ionizing radiation

Abstract

Nanometer-scale transistors often exhibit random telegraph noise (RTN) with high device-to-device variability. Recent experiments up to Grad total ionizing dose (TID) demonstrate stable RTN in planar bulk-Si metal-oxide-semiconductor (MOS) transistors and in Si fin field-effect transistors (FinFETs). In these cases, pre-existing defects in the ultrathin gate dielectrics dominate the device low-frequency 1/f noise (LFN). In contrast, III–V MOS devices with lower quality oxide/semiconductor interfaces show significant increases in LFN at much lower doses, due to the TID-induced activation of high densities of border traps. Aggressively scaled devices fabricated in Si gate-all-around nano-wire FET technology exhibit prominent defects leading to LFN and RTN. Increases or decreases of LFN in these devices during irradiation and annealing results primarily from the activation or passivation of border traps and interface traps.

Low-frequency noise in nanowires

“…74,199–201 Under the conventional assumption that these RTN are due to charge exchange with border traps in a standard number fluctuation model, estimates of trap locations were inferred, with defects identified in both the near-interfacial SiO 2 and the HfO 2 layer of the dielectric stack. 74 However, in at least some cases, this typical interpretation 74,199–201 may not be complete or correct, 76,77 as we now discuss.…”

“…This demonstrates the importance of mobility fluctuations in the RTN of these devices. 76,77,110,111 At these voltages, the strength of scattering needed to account for the RTN magnitudes is much greater than likely from remote Coulomb scattering from border traps. 59,69,76,77,138…”

“…In recent decades, metallic and semiconducting nanowires (NWs) have enabled investigations of a wide range of phenomena including Anderson localization, electron–electron interactions, and quantum-mechanical decoherence; 1–23 magnetism, including Aharonov–Bohm oscillations and the Kondo effect; 11,18,23–39 superconductivity, macroscopic quantum tunnelling, and Majorana bound states; 39–50 and low-frequency noise, random-telegraph noise, and universal conductance fluctuations. 51–77…”

“…5–9,12,20 As microelectronic fabrication techniques advanced, NW fabrication techniques evolved from substrate step and templating methods to state-of-the-art lithography capable of producing nanostructures in volume and integrating semiconductor NWs into architectures that facilitate fabrication and measurement. 5–9,12,20,71–77,81,82…”

“…Some active defects in as-processed devices are passivated during irradiation, some defects are newly activated via irradiation, and other defects are remarkably stable through the full irradiation and measurement sequence. 74,77…”