The surface topography of Si(100) modified by low energy Ar+ bombardment was characterized by Atomic Force Microscopy (AFM). AFM images show that ripples can be formed by 500eV Ar+ at incidence angle 40°. The spacing wavelength of ripples is around 70nm with wave vector parallel to the projected direction of ion beam. Direct bonding and mechanical delamination of Si wafer pairs with ripples are investigated. Delamination energy measured by crack-opening method along the direction perpendicular to the wave vector,γ⊥, is always smaller than that along the wave vector direction,γ„; Both γ⊥ and γ„ are found to decrease with sputtering time. The AFM images after delamination indicate that the bonding and delamination process do not eliminate the ripples on the wafer surface.