Realization of hexagonal barium ferrite thick films on Si substrates using a screen printing technique

Hexagonal barium ferrite thick films (50?200??m) have been deposited on Si and Al2O3/Si substrates using a screen printing technique. X-ray diffractometry, scanning electron microscopy and magnetometry were used to characterize and correlate the ferrite films' microstructure and magnetic properties. The experiments indicated that an Al2O3 underlayer was effective in preventing silicon diffusion into the barium ferrite films during a final sintering treatment at temperatures above 1100??C. A two-stage sintering process allowed a reasonable tradeoff between mechanical and magnetic properties. This work reveals the feasibility of fabrication of thick ferrite films on large substrates (up to 25?mm in diameter) for future planar microwave devices compatible with semiconductor integrated circuits processing.