Single-crystal silicon holds a prominent position as one of the most widely used materials in advanced industries, particularly in the fields of optics, semiconductors, and microelectronics. On the other hand, ultra-precision machining of single-crystal silicon using a single-point diamond tool is a pivotal method for manufacturing optical and semiconductor components. In this study, the influence of undeformed chip thickness (hmax) on surface quality and subsurface alterations was investigated. The results indicated that increasing hmax leads to variations in machining efficiency time and the formation of a surface amorphous layer. X-ray Diffraction (XRD) analysis confirmed the reduction in crystalline peak intensity and validated the formation of the amorphous layer. Furthermore, the examination of crystallographic orientations revealed that surface damage predominantly occurs along the <110> direction. Machining time plots demonstrated that the time required to reach the surface roughness threshold varies across different undeformed chip thicknesses. The tests were categorized based on hmax, and an favorable operating range of approximately 100 nm was identified within the tested conditions. These findings can serve as a basis for optimizing the ultra-precision machining process of single-crystal silicon.