Cathodic Electrophoretic Deposition of Ceramic Nano-Particle Manganese Zinc Ferrite

Abstract

The electrophoretic deposition (EPD) of micro/nano-particle manganese zinc ferrite (Mnx Zn1-xFe2O4) material has been carried out on silicon substrates. EPD is performed in isopropanol (IPA) solutions containing charging and adhesion agents. The ferrite powders were prepared by grinding ceramic sintered toroids of a commercial high permeability Mn-Zn ferrite. The ferrite film has been deposited up to 4μm in thickness in 30 minutes showing good selectivity to silicon patterned with 250nm thermally grown silicon dioxide. Additionally, selective deposition has been observed on heavily doped p-type regions in n-type silicon substrates. The deposition process is a self limiting process with the initial high elerophoretic current declining to 10% of its value in 10 minutes. This result suggests that majority of ferrite deposition occurs in first 10 minutes. The deposition rate and zeta potential measurements indicate a high particle velocity on the order 5.7x10-3 cm/s with an electric field of 160V/cm generated across the 2 cm electrode spacing. An amorphous like interfacial layer is observed in as deposited substrates. The scanning electron micrographs indicate pattern filling and conformal deposition on copper planar micro-inductors fabricated by chemical mechanical planarization. These results are promising for powder ferrite material (hard and soft) to be selectively deposited for a wide variety of applications in microelectronics passive components and in MEM’s based applications