Effects of low-energy backsurface gettering on the properties of low-frequency excess noise in NH₃ and N₂O nitrided MOSFETs

Low-frequency noise in n-channel MOSFETs was studied over a wide range of temperatures and biases. The devices were subjected to nitridation by annealing in NH₃ and N₂O which were subsequently gettered by low-energy Ar⁺ ranging from 10 minutes to 40 minutes. The noise spectra for devices with different gettering times are compared to the ungettered devices. It is found that, for both types of devices, flicker noise is reduced by backsurface gettering for short gettering times. The low-frequency noise arises from thermal activation of carriers to traps at the Si-SiO₂ interface. Backsurface gettering results in the modification of the energy distribution of the interface traps, probably due to stress relaxation at the Si-SiO₂ interface.