In conjunction with sputtering a metal, especially copper, into high aspect-ratio holes in a wafer, an oblique ion milling method in which argon ions or other particles having energies in the range of 200 to 1500 eV are directed to the wafer at between 10 and 35 to the wafer surface to sputter etch material...http://www.google.de/patents/US20040222082?utm_source=gb-gplus-sharePatent US20040222082 - Oblique ion milling of via metallization
