Replication of 175-Å lines and spaces in polymethylmethacrylate using x-ray lithography

A new technique for fabricating high contrast x-ray masks with simple patterns of lines and spaces less than 50 Å in width is described. The successful replication of 175-A lines and spaces in polymethylmethacrylate (PMMA) using the carbon K (45-Å) x-ray is reported. It was found that PMMA structures smaller than 150 Å in width lost their physical integrity and would not adhere to SiO2 substrates.