Low-Frequency Noise Measurements in Silicon Power MOSFETs as a Tool to Experimentally Investigate the Defectiveness of the Gate Oxide

In this work we analyse the applicability of low-frequency (LF) noise measurement in order to study the defectiveness in the gate oxide of power MOSFETs. To this purpose we implement a low-noise experimental set-up, which is able to measure the drain current flicker (“1/f”) noise of the device under test (DUT). First, we show how these measurements can be used to empirically detect the physical model and related compact expressions, which best describe the source of fluctuations in this type of devices. Then, accordingly to the selected physical model, the defect density in the gate oxide is extracted. In order to validate the proposed methodology, experimental data are reported and discussed in the case of trench power MOSFETs. The measured noise spectra confirm the suitability of the laboratory set-up for this type of analysis and, by means of an empirical fitting of the data, the defect density is estimated, in accordance with the typical values expected for the technology considered.