A metal oxide adhesion layer prepared with water based coating solution for wet Cu metallization of glass interposer

Inorganic interposers made of glass are attractive for advanced high frequency applications and ultra- fine line patterning technology. Because glass combines a couple of benefits like large form factor, good coefficient of thermal expansion (CTE) matching to silicon, smooth surface and a low dielectric constant and loss tangent. Recently much progress has been made with respect to glass electrical and physical properties. This allows for handling of thin glass sheets down to 100 μm in a typical PCB panel format. Also advances have been made in the area of laser drilling allowing aspect ratio up to 1:10 for 25 μm diameter of through glass via (TGV). Another major challenge is the cost competitive and reliable metallization of smooth glass, a critical prerequisite for the use of glass substrates in the electronic packaging market. Plated copper does not adhere directly to glass. Sputtering technology typically also requires a 50 nm thick adhesion promoting metal layer (like Ti) before copper can be seeded....