1/f noise suppression of pMOSFETs fabricated on Si(100) and Si(110) using an alkali-free cleaning process

This paper reports that the low-frequency noise in p-channel MOSFETs fabricated on [110] and (100) crystallographic oriented silicon is related to the microroughness of the silicon surface. Since the conventional RCA cleaning process makes the surface rough, especially in the case of [110] orientation, the authors developed the so-called 5-step room temperature cleaning process that does not use alkaline solution. The combination of this new cleaning process with the microwave-excited high-density plasma oxidation process for the formation of the gate oxide, instead of the standard 900°C thermal oxidation process, leads to a reduction of the microroughness and a drop in the 1/f noise level of more than one decade. Furthermore, this reduction is not only observed for the [110] orientation but also seen, albeit to a much lesser extent, for (100) if it is treated in the same way.