New BST–silica suspension coating material for dielectric thin films fabricated at low temperatures

Abstract

A new Ba0·7Sr0·3TiO3 (BST)–silica suspension has been developed as a coating material for dielectric thin films. Using a spin on glass (SOG) wet process, a thin layer consisting of nanoparticles of BST and silica was formed on an Al/SiO2/Si wafer. The BST–silica suspension was made by mixing a BST nanoparticle dispersion with methyl siloxane oligomer. A silicon wafer was coated with the BST–silica suspension using a spin coater and heat treated. The sample was then coated with methyl siloxane oligomer and heat treated again, and finally, a top electrode was applied. The Al/SiO2/BST–SiO2/Al/SiO2/Si stack thus prepared is a metal insulator metal (MIM) capacitor. The electrical properties of the MIM capacitor were evaluated and its capacitance, dissipation factor and voltage coefficient of capacitance were determined to be 1054 pF mm−2, <0·1 and <100 ppm V−1 respectively.