ABSTRACT
Polyimides are employed as dielectric layers in microelectronic applications such as printed circuit boards and multichip modules [1–3], since they have low dielectric constant, high thermal stability, good mechanical properties, and processability [4–6]. The key to achieving high-performance packages is the embedding of high-density wiring in a low dielectric matrix. The thin film packaging structure (Fig. 1) of the IBM Enterprise System/9000 processor consists of the following interfaces: polyimide/glass-ceramic, metal/polyimide, polyimide/metal, and polyimide/polyimide. Reliable adhesion at each of these interfaces is required for high-yield device production and field performance. However, polyimide materials with the best chemical and mechanical properties often give poor adhesion. To improve the adhesion of a metal or polymer to the substrate polymer film, the polymer surface is usually modified by dry processes such as plasma, corona discharge, x-ray, laser, ion beam, or flame treatments [7–11]. Recently, interest in wet-process surface modification of polymers has increased because of its simplicity and low cost. In a typical wet process or immersion treatment for polymer surface modification the polymer substrate is immersed into or sprayed with a chemical solution, and subsequently the excess reagents are rinsed off with a solvent followed by drying if necessary.
