Plasma‐Developed X‐Ray Resists

A novel plasma‐development method using an oxygen plasma and new materials which optimize sensitivity have been evaluated as x‐ray resists at the 4.37Å wavelength. Both negative and positive tone images can be obtained upon plasma development. To date, negative tone images are more technologically important. X‐ray absorbing host polymers and moderately volatile guest monomers are used. Images are developed after exposure and low temperature fixing under vacuum by differential development in an oxygen plasma. Examples are presented for monomers which are locked by free radical and cationic mechanisms. One composition which has optimum properties is a mixture of 81 weight percent poly(2,3‐dichloro‐1‐propyl acrylate) and N‐vinyl carbazole. With it features as small as 0.3 μm were resolved for a short 1.5 min exposure time. These resists and processes are suitable only for multilevel resist processing schemes which are demonstrated.