Random telegraphic signals and low-frequency noise in rapid-thermal-annealed silicon-silicon oxide structures

Abstract

Random telegraphic signals (RTSs) were observed in aluminium-silicon oxide-silicon (Al-SiO2-Si) metal-oxide-semiconductor capacitors with large contact areas of about 7.85 × 10-3 cm2, which have been subjected to rapid thermal annealing (RTA) in an argon ambient at 600 to 700°C for 50 s. The RTSs change from a two-level RTS to a multilevel RTS as the device bias voltage or temperature is increased. Samples showing RTSs generally exhibit low breakdown voltages and show a Lorentzian spectrum at a frequency between 30 to 400 Hz. Furthermore, the interface-state density from samples exhibiting RTSs is generally higher than that from samples that do not show any RTSs. We suggest that the RTA process over a specific temperature range has produced weak spots in the devices. The filling and emptying processes of a trap near a weak spot modulate the barrier height, resulting in the RTS and the Lorentzian spectrum observed in these devices.