Lithographic processing of polymers using plasma-generated electron beams

Pattern definition in polymer films is achieved using electron beams generated in soft vacuum (0.05-0.50 torr) glow discharges either on a continuous or a pulsed (20-100 ns) basis. With the continuous-mode electron beam, 7-μm transmission mask features are replicated in both polymethyl methacrylate (PMMA) and polyimide resists. Using a pulsed electron-beam submicron (~0.5 μm) features are transferred from an electron-transmitting stencil mask into the PMMA. The soft-vacuum pulsed electron beam is also eminently suited for polymer stabilization. Pulsed electron-beam hardening of 0.05-3.5 μ-thick AZ-type and MacDermid resist patterns is also demonstrated with hardened resist patterns stable to temperatures between 200° and 350°C. The demonstrated replication and pattern stabilization technique may be applicable in microelectronics packaging lithography where the resist thickness is substantial, linewidths are 1-10 μm, and registration requirements are less stringent