Fabrication of µm period implantation masks for 16 Mbit bubble memories

Using test mask plates containing 2 µm period propagation patterns for 16 Mbits/cm²bubble chips, we have studied the problems of making the implantation mask with two different exposure methods : contact printing and 10X step and repeat projection printing. Concerning the implantation mask itself, we have selected three different materials : gold, silica and UV-hardened resist The fabrication technique adopted for each case is described. The results are shown and compared using SEM pictures taken under a couple of angles. We have observed a better delineation of patterns with contact printing and especially with silica mask.