Angular Dependence ot Sputtering Yield of Various Targets Bombarded by Argon Ions and its Application to Observation of Etched Surface in SEM

Abstract

The sputtering yields of Al and red blood cells of the human have been measured at oblique angles of incident beam for Ar ion irradiation in the energy region from 5 to 15 keV. The yields were determined from the weight loss of the target. The maximum yield was found to be at angle of incidence θ=74° (5keV), where θis the angle measured from the surface normal. At a large θ, the sputtering yield increases more than 1/cosθ, and the curve passes through a maximum between 70° and 88°. Then, according to the negative defocusing effects caused by spacecharge and the consistent theory of sputtering (Kanaya theory), the dependence of the sputtering on the incident angle (θ) and dead angle (α), dependent on incident ion energy, is given by s (θ) =s (0) · cos^1/2-1/n (θ+α) /cosθ, where n is dependent on incident ion energy. The formula is in good agreement with experimental results. Furthermore, ion beam sputtering has been used to remove the surface layer from Red Blood Cells.