Thermal Imidization of Fluorinated Poly(amic acid)s on Si(100) Surfaces Modified by Plasma Polymerization and Deposition of Glycidyl Methacrylate

Abstract

Plasma polymerization of glycidyl methacrylate (GMA) on pristine and plasma-pretreated Si(100) surfaces was carried out. The epoxide functional groups of the plasma-polymerized GMA (pp-GMA) could be preserved, to a large extent, by controlling the glow discharge parameters. The pp-GMA film was used as an adhesion promotion layer for the thermal imidization of fluorinated poly(amic acid) (FPAA) precursors on Si substrates. The fluorinated polyimide (FPI)/pp-GMA−Si laminates so formed exhibited a 180°-peel adhesion strength as high as 10 N/cm. This value was much higher than the negligible adhesion strength for the FPI/Si laminates obtained from thermal imidization of the FPAAs on either the pristine or the argon-plasma-treated Si surfaces. The high adhesion strengths of the FPI/pp-GMA−Si laminates were attributed to the synergistic effect of coupling the curing of the epoxide groups in the pp-GMA layer with the imidization process of the FPAAs and the fact that the plasma-deposited GMA chains were covalently tethered on the Si(100) surface. Comparison of the adhesion strengths of the FPI/pp-GMA−Si laminates to that of the polyimide (PI)/pp-GMA−Si laminate, formed by thermal imidization of the poly(amic acid) precursor of poly(pyromellitic dianhydride-co-4,4‘-oxydianiline) on pp-GMA−Si, suggests that the presence of fluorine-containing groups, such as −CF3, in the PI chains has a negligible effect on the adhesion property of the FPIs on the Si(100) wafer surface modified by the present interfacial molecular design and lamination technique.