A new positive resist composed of a bifunctional vinyl ether monomer as crosslinker and a photoacid generator and an acidic base resin was investigated. This resist system utilizes the unique reaction of the vinyl ether monomer; the vinyl ether forms crosslinks of base resins by prebaking and the crosslinks are decoupled by acidolytic reaction via generation of an acid upon exposure. In order to investigate the lithographic properties for x-ray lithography, effects of crosslinker concentration and process conditions on the resist were evaluated, The resist has a high sensitivity of 35 mJ/cm(2) and a high gamma value of 10. A good profile for 0.3 mu m lines and spaces patterns is obtained. Furthermore, it is found that this resist system has high thermal resistance up to 180 degrees C against both pattern deformation and resist thickness loss.