Radiation mask adapted to be aligned with a photoresist layer and method

Abstract

The present invention provides a procedure for achieving accurate alignment between an X-ray mask and a device substrate for the fabrication of multi-layer microstructures. A first photoresist layer on the substrate is patterned by a first X-ray mask to include first alignment holes along with a first layer microstructure pattern. Mask photoresist layers are attached to second and subsequent masks that are used to pattern additional photoresist layers attached to the microstructure device substrate. The mask photoresist layers are patterned to include mask alignment holes that correspond in geometry to the first alignment holes in the first photoresist layer on the device substrate. Alignment between a second mask and the first photoresist layer is achieved by assembly of the second mask onto the first photoresist layer using alignment posts placed in the first alignment holes in the first photoresist layer that penetrate into the mask alignment holes in the mask photoresist layers. The alignment procedure is particularly applicable to the fabrication of multi-layer metal microstructures using deep X-ray lithography and electroplating. The alignment procedure may be extended to multiple photoresist layers and larger device heights using spacer photoresist sheets between subsequent masks and the first photoresist layer that are joined together using alignment posts.