In this study, we reveal that Si(110) surface is flatted using HF(0.5wt%)/H2-UPW solution in N2 ambience without light illumination. We demonstrate that the electron effective mobility on Si(110) is obviously improved by introducing this new chemical surface flattening process. Especially, the improvement of electron mobility become larger while the effective field is increased. As a result, the electron mobility is improved about 1.4 times at the high effective field equals 1 MV/cm, which is mostly limited by surface roughness. We consider that the improvement of the electron mobility is originated in the good suppression of surface micro-roughness in this experiment. However, the 1/f noise level is almost the same even introducing the chemical surface flattening process. In this paper, it is observed that the 1/f noise level of MOSFETs on Si(110) is suppressed very well by introducing the novel accumulation mode device structures.