"The Low Frequency Noise (LFN) in MOSFETs is critical to Signal-to-Noise Ratio (SNR) demanding circuits. Buried Channel (BC) MOSFETs are commonly used as the source-follower transistors for CCDs and CMOS image sensors (CIS) for lower LFN. It is essential to understand the BC MOSFETs noise mechanism based on trap parameters with different transistor biasing conditions. In this paper, we have designed and fabricated deep BC MOSFETs in a CIS-compatible process with 5 V rating. The 1/f Y LFN is found due to non-uniform space and energy distributed oxide traps. To comprehensively explain the BC MOSFETs noise spectrum, we developed a LFN model based on the Shockley-Read-Hall (SRH) theory with WKB tunneling approximation. This is the first time that the 1/f Y LFN spectrum of BC MOSFET has been numerically analyzed and modeled. The Random Telegraph Signal (RTS) amplitudes of each oxide traps are extracted efficiently with an Impedance Field Method (IFM). Our new model counts the noise contribution from each discretized oxide trap in oxide mesh grids. Experiments verify that the new model matches well the noise power spectrum from 10 to 10k Hz with various gate biasing conditions from accumulation to weak inversion."
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