An Analytical Treatment on the Pattern Formation Process by Sputter Etching with a Mask

The pattern formation process, in which a substrate with a patterned mask is sputter-etched, is investigated by means of a theoretical analysis based on the dependence of the etch rate on the angle of ton incidence V (θ). By introducing a characteristic curve, determined only by function V (θ), the cross-sectional profile generated by masking cart be predicted. For various factors, such as the etch rates of the mask and the substrate V 1 and V 2 and the inclination angle of the mask pattern edge θ 1 , the side-wall slope of a pattern machined into the substrate surface θ 2 mostly depends only on the ratio of the etch rates V 2 / V 1 , and it increases discontinuously for V 2 / V 1 >1. Depending on whether V 1 < V 2 or V 1 > V 2 , the pattern formation processes are classified into two types. High resolution and sharply defined patterns are usually obtained under the condition V 1 < V 2 .