This paper investigates the effect of single-point diamond machining conditions, such as the Berkovich tip orientation (0 β’ , 45 β’ , and 90 β’ ) and the normal load (0.1, 0.3, 0.5, 1, 2, 3, 4, 5 mN and 0.1 N), on the both deformation behavior and the chemical properties of single-crystal silicon through nanoscratch with 20 wt.% KOH-etching tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.16 to 0.38, the material removal mode, and the KOH-etching property of silicon. In normal load ranges from 0.1 to 1 mN, the friction coefficient remarkably increased with decreasing normal. KOH-etching results showed that, as a whole, the size of etch-hillock structures increased with an increasing normal load, indicating that that the higher the load that is applied to the material surface, the more the etch-mask effect of the mechanically affected layer increases. Contrarily, the groove surface machined under a very low load (0.1 N) showed only the etch-promotion effect. The evolution of the morphology of a scratched Si(1 0 0) surface during the etching process was visualized by 20 wt.% KOH-etching tests under dipping times ranging from 0 to 30 min. The initial size of the etch-hillock structure was closely related to that of the contact zone between the diamond tip and materials.