1. Field of the Invention
This invention is directed to high resolution fabrication techniques, in general, and, more particularly, to a mask and method of making the mask for use in implementing the high resolution fabrication techniques.
2. Prior Art
In fabricating many devices of high resolution, such as magnetic bubble domain structures, semiconductor device structures, and the like, various techniques have been developed to improve the density and the resolution of the structures. These techniques include, inter alia, E-beam and X-ray lithography. These techniques have been used in replicating or fabricating microcircuits capable of resolution of better than 0.1 microns. In the past, however, the resolution has been limited primarily by two factors, viz. (1) the required thickness of a heavy metal absorber for absorbing the radiation from the source in order to provide adequate contrast and (2) the range of the electrons or photons produced by absorption of the X-rays or electrons in the mask resist. That is, the thickness of the absorber which is required generally limits the achievable line width inasmuch as the thickness/width aspect ratio of the absorber is generally limited to one or two.
In addition, various techniques of making masks for use in X-ray lithography have been described. However, for the most part, these masks are directed at complex, sophisticated techniques for placing materials on a suitable membrane and operating on the materials and/or the membrane to establish a suitable masking technique. In addition, these techniques frequently require a plurality of other masking stages using photoresist or the like with the resultant increase in cost of the masks and the decrease in yield of masks. It is, therefore, highly desirable to establish techniques for making high resolution lithographic masks in a manner which is as simple and inexpensive as possible.