Atomic Force Microscopy Observations of Si Surfaces after Rinsing in Ultrapure Water with Low Dissolved Oxygen Concentration

Contact‐mode and tapping‐mode atomic force microscopy have been used to observe hydrogen‐terminated (111) and (001) Si surfaces. The surfaces were prepared by rinsing in ultrapure water with very low dissolved oxygen after removal of the native oxide using 1% HF acid at room temperature. With the tapping‐mode atomic force microscopy, clear steps and triangular‐shaped holes were observed on the (111) Si surface. The step shape varied according to the misorientation angle of the sample. The (001) Si surface consisted of round‐shaped "mountains." The roughness of the (001) surface increased with longer rinsing in ultrapure water. This type of Si surface etching is very similar to that observed in the case of etching with solution (pH 8).