Aminosilane and Metal Modifications of Polyimide Surfaces

Abstract

Alterations in polyamic acid-polyimide surfaces produced by the use of different methods of curing (oven vs. hot plate), the application of a silane adhesion promotor (γ-aminopropyltriethoxysilane), and the deposition of copper have been studied using ESCA. Our objective was to develop chemical state information (elemental composition, chemical bonding features) about the modifications occurring in the outermost few tens of angstroms of polyimide films. The results show different C 1s spectral features for hot plate vs. oven cured films but identical stoichiometries. The silane treated amic acid surface showed an additional N 1s component at 402.0 eV due to NH⁺. Heat treatment of this film resulted in the formation of a silicon-polyimide. Grazing angle ESCA results showed that the silane diffused into the sub-surface of the amic-acid film. Analysis of cured polyimide films after the etch (FeCl₃) removal of a copper film indicates that unzipping of the polymer may have occurred. A disrupted polyimide matr ix that is vertically inhomogeneous in elemental composition was detectable after the sputter deposition of ~1.5 nm of Cu onto a cured polyimide film.

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