High resolution X-ray mask having high aspect ratio absorber patterns

A method for fabricating a high resolution X-ray mask having high aspect ratio absorber patterns thereon comprising the steps of

• Step 1) on the top of an X-ray transparent membrane substrate, lithographically forming a pattern of X-ray absorbing material, said pattern of X-ray absorbing material having a first thickness and sidewalls substantially perpendicular to said top of said membrane;
• Step 2) coating said patterned absorbing material and top membrane surfaces with a single layer of X-ray resist material;
• Step 3) directing X-rays through the bottom of said membrane substrate to expose said single layer of X-ray resist material, said portions of said X-ray resist material disposed over said surfaces of said absorbing material on said membrane remaining unexposed;
• Step 4) developing and etching said X-ray resist material to remove said unexposed portions disposed over said absorbing material;
• Step 5) electroplating the surfaces of said absorbing material on said membrane substrate with an additional layer of absorbing material having a second thickness;
• and
• Step 6) removing said remaining X-ray resist material on said membrane substrate to leave said pattern of absorbing material on said membrane, said absorbing material having a resultant height consisting of said first thickness plus said second thickness of said additional absorbing material.