Effects of Ar⁺ back-surface gettering on the properties of flicker noise in n-channel nitrided MOSFETs

Flicker noise in back-surface gettered, nitrided n-channel metal-oxide-semiconductor field-effect transistors is characterized over a wide range of temperature and biases. The gettering was performed using a low-energy (550 eV) argon ion beam, and the gettering time ranged from 10 to 40 min. The noise power spectra for devices with different gettering times are compared to the ungettered devices which serve as the control. It is found that flicker noise is reduced by back-surface gettering for short gettering times. However, a rebound in the noise magnitude is observed for long gettering times. Investigation of the temperature dependences of the noise power spectra indicates that the low-frequency noise arises from thermal activation of carriers to traps at the Si-SiO₂ interface. Back-surface gettering results in the modification of the energy distribution of the interface traps, probably due to stress relaxation at the Si-SiO₂ interface.