Synthesis of Aptes-Capped Self-Adsorption Pd Nanoparticles and Application in Metallization on Glass Substrate with High Adhesion

Abstract

Palladium is the most used catalysts in the electroless deposition process. The technology that use the amino silane compound (3-Aminopropyl) Triethoxysilane (APTES) as surface modifier is quite mature. Therefore, an innovative idea that one step palladium catalyst APTES-Pd with APTES as capping agent and surface modifier appeared. APTES-Pd is capable to adsorb on surface of glass substrate by forming Si-O covalent bond. Comparing to commercial palladium catalysts, the process is complex and need to work at high concentration, APTES-Pd has easier process and able to work at low concentration. The particle size of APTES-Pd is characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The configuration of APTES-Pd as well as the effect of modification on glass substrate is explained by X-ray photoelectron spectroscopy (XPS).Glass substrate is a good option as an interposer substrate. It has serval advantages, such as low k, high resistivity, high stability, low coefficient of thermal expansion (CTE) mismatch with copper material and good mechanical properties. However, because glass substrate (SiO2) is stable and surface is smooth, it’s hard to electroless deposit Cu layer with high adhesion on it. The adhesion that using commercial palladium catalysts Sn/Pd for electroless copper deposition is too low to pass tape test. Because interaction between Sn/Pd and substrate is electrostatic adsorption which is lower than covalent bond. Using APTES-Pd for electroless copper deposition is capable to improve the interaction between glass and Cu layer. APTES-Pd can pass tape test on glass substrate. But its adhesion is still too low to be measured by T-Peel. To enhance the adhesion of the metal films on glass substrates, we coat titanium dioxide (TiO2) as adhesion promoter. TiO2 can not only bond to glass substrate but increase surface roughness. After coating TiO2 film, the adhesion of metal film increases to 122 gf/cm.