Improved X-Ray Mask Lithography Structure and Process
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
A technique is described whereby an improved X-ray mask structure, as used in X-ray lithography, eliminates distortion of membranes due to polyimide shrinkage. Described is a process whereby a reinforced membrane is applied to the back of the mask by means of a polyimide layer deposited by solventless evaporation. This eliminates distortion of the membrane so that precise distances can be maintained between the wafer and the mask. Typically, X-ray mask structures formed by a membrane of a low atomic weight material, such as BN, B-doped Si, etc., are quite brittle and require that the substrate be reinforced with an overcoat of polyimide. Generally, the polyimide is deposited on the top of the membrane by spinning or spraying from a solution containing organic solvents, usually xylenes and NMP.