SELF-THICKNESS-LIMITED PLASMA POLYMERIZATION OF AN ULTRATHIN ANTIADHESIVE FILM

Ultrathin (<5 nm) fluorinated polymer films of homogeneous thicknesses have been deposited from a CF4/H-2 microwave discharge. The films hav e an extremely low surface energy of 4.2 mJ/m(2), which is more than f our times lower than that for polytetrafluoroethylene. The deposition was carried out in a type of ''self-thickness-limited'' mode, in which the thickness of the deposited polymer film is limited by the plasma parameters. The deposition can be separated into two phases, a growth and a treatment phase. During the treatment phase, the deposited film is fluorinated, which results in a dramatic decrease of the surface en ergy. The thickness limiting behavior of the plasma is explained by th e dualism of etching and polymerization occurring in fluorocarbon disc harges. The film was tested as antiadhesion film for the replication o f micro-optical structures, using a Ni shim with a very fine surface r elief grating (400 nm periodicity) to hot emboss (at 180 degrees C) po lycarbonate sheed. The tests demonstrate the excellent antiadhesive pr operty of the film with the polycarbonate and reveal a good adhesion o f the film with the Ni substrate. (C) 1996 American Vacuum Society.