A method includes receiving a substrate having a substrate feature; forming a first material layer over the substrate and in physical contact with the substrate feature; forming an etch mask over the first material layer; and applying a dynamic-angle (DA) plasma etching process to the first material layer through the etch mask to form a first material feature. Plasma flux of the DA plasma etching process has an angle of incidence with respect to a normal of the first material layer and the angle of incidence changes in a dynamic mode during the DA plasma etching process.