Low-Frequency Noise in Integrated N-WELL Resistors

Low-frequency noise in integrated N-WELL resistors is studied. Noise at low frequencies is 1/f^γ, where γ ~ 1. The origin of flicker 1/f^γ noise is mainly due to trapping and detrapping of charge carriers at n⁺Si/shallow trench isolation (STI) interface, supporting number fluctuation theory. The noise coefficients were comparable for varying process conditions, mainly due to smaller process deltas, but varied significantly with STI depth. Based on simulated doping profiles, the distance between dopant peak and the n⁺Si/STI interface is the primary factor that impacts noise. In this case, the peak coincides with the interface in deeper STI resistors, leading to higher 1/f noise.