Motorola Corporation

Ed S Ramakrishnan

Wei-Yean Howng

Kenneth David Cornett

A method for forming a dielectric layer onto a substrate having a silicon surface includes initially depositing an oxidizable metal thin film onto the surface and thereafter depositing a thin film of a metal titanate compound, such as the zirconium titanate. The metal thin film is preferably formed of tantalum, titanium or zirconium. Following deposition of the metal titanate thin film, the metal titanate is annealed by heating in an oxidizing atmosphere at a temperature effective to recrystalize the titanate to increase the dielectric properties. During annealing, the metal film reacts with oxygen to form a metal oxide thin film intermediate the metal titanate thin film and the silicon surface. The oxidation of the metal thin film inhibits oxidation of the underlying silicon that would otherwise reduce the effective capacitance of the dielectric layer. The resulting coated substrate thus includes a dielectric layer that includes a thin film of the oxidized metal and an oxygen-annealed metal titanate thin film and exhibits an increased effective capacitance and improved dielectric properties, particularly in comparison to a comparable oxygen-annealed titanate films formed directly onto silicon surfaces.

Method for forming a titanate thin film on silicon, and device formed

A piezoelectric device, such as a surface acoustic wave filter, comprises a piezoelectric film composed of a lead zirconium titanate compound applied to a substrate formed of silicon or gallium arsenide. The device includes an intermediate film between the piezoelectric film and the substrate and composed of a lead-free zirconium titanate compound to prevent interaction between lead oxide in the piezoelectric material and the material of the substrate that would otherwise cause spilling or adversely effect the electrical properties of the substrate. The piezoelectric device is made by first applying the film of the lead-free zirconium titanate compound and thereafter applying the film of the lead zirconium titanate compound. Preferably, the lead-free zirconium titanate film is applied by sputtering and annealed to densify the material and increase the dielectric constant prior to depositing the piezoelectric material.

Piezoelectric lead zirconium titanate device and method for forming same

A piezoelectric device, such as a surface acoustic wave filter, comprises a piezoelectric film composed of a lead zirconium titanate compound applied to a substrate formed of silicon or gallium arsenide. The device includes an intermediate film between the piezoelectric film and the substrate and composed of a lead-free zirconium titanate compound to prevent interaction between lead oxide in the piezoelectric material and the material of the substrate that would otherwise cause spalling or adversely effect the electrical properties of the substrate. The piezoelectric device is made by first applying the film of the lead-free zirconium titanate compound and thereafter applying the film of the lead zirconium titanate compound. Preferably, the lead-free zirconium titanate film is applied by sputtering and annealed to densify the material and increase the dielectric constant prior to depositing the piezoelectric material.

Growing community of inventors

Albuquerque, NM, United States of America

Ed S Ramakrishnan