Novel Process For Fabricating Low Distortion X-Ray Masks Of Submicron Gold Patterns

A novel process for fabricating x-ray masks of submicron gold patterns using a copper plating base is presented and discussed in detail. In the E-beam writing of x-ray masks, the trilevel resist layers and the metal layer for x-ray absorber patterning cause a proximity effect which determines the masks' resolution. Based on E-beam simulations and experimental results, copper plating base is selected as the best metal-layer material to reduce the above effect. To fabricate submicron gold patterns on the copper base, two gold-electroplating steps are newly introduced. These are strike plating and pulse-current plating. Stress change in the plated gold and positional accuracy changes are also measured throughout the heating process. Finally, sequential steps for the fabrication of x-ray masks with plating base are shown.