USA As Represented by Secretary of the Navy

Paratek Microwave Incorporated

Wontae Chang

Douglas B Chrisey

Manfred Kahn

James S Horwitz

Jeffrey M Pond

Steven W Kirchoefer

Adriaan Carter

Tunable dielectric thin films are provided which possess low dielectric losses at microwave frequencies relative to conventional dielectric thin films. The thin films include a low dielectric loss substrate, a buffer layer, and a crystalline dielectric film. Barium strontium titanate may be used as the buffer layer and the crystalline dielectric film. The buffer layer provides strain relief during annealing operations.

Strain-relieved tunable dielectric thin films

A multicomponent film on a substrate can be annealed at higher temperatures in oxygen by using a specifically designed annealing vessel. The vessel is formed of a multicomponent material which has at least all of the components of the first multicomponent material of the film or, in the case where there are nonvolatile components, then the vessel is formed of a second multicomponent material which has at least the same composition of relatively volatile components as the first multicomponent film. As the multicomponent film is annealed for a sufficient time within the vessel the multicomponent film remains in contact with a vapor of the first multicomponent material and the vessel material. This process called bomb annealing prevents loss of volatile components from the film and roughening of the film surface and leads to films with lower dielectric loss. Preferred thin film materials are ferroelectric materials although any material could be used. The annealing can be done in oxygen at temperatures higher than 900&deg; C.

Bomb annealing of thin films

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Reston, VA, United States of America

Wontae Chang