Stress-Free Magnetic Film
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2005-Feb-15
A nickel-iron film layer is often used as a high density magnetic recording material. The film thickness can vary from several nanometers to several micrometers depending on the application. However, the shear stress at the substrate/film interface increases as the film thickness increases. When a critical thickness is reached, the shear stress is greater than the yield stress of the interface, thereby causing the film adhesion to fail. Therefore, the in-plane stress of the film has to be controlled very carefully to ensure the film's reliability. A process to deposit a relatively thick layer of nickel-iron has been developed. The process uses RF sputtering with a very fast deposition rate, on the order of 50 nanometers per minute. The film in-plane stress is compressive and has been found to be very low.