The ferroelectric multilayer thin film structure using the difference of thermal expansion coefficient between ferroelectric layer and substrate for variable microwave device

摘要

The present invention relates to an electrical permittivity maximum variability structure to adjust the strain direction of the ferroelectric thin films using thermal mismatch as, more particularly, in the microwave device such as the variable phase shifters such as to change the phase or frequency during microwave transmission, to adjust the strain direction of the ferroelectric thin film using a thermal mismatch with the dielectric constant variation characteristic in accordance with the voltage applied to the electrical permittivity variability relates to maximize structural ; and the substrate electrically variable dielectric constant to adjust the strain direction maximize structure of the ferroelectric thin film using a thermal mismatch of the present invention is to take advantage of the dielectric constant variation characteristic in accordance with the voltage applied; And a ferroelectric thin film formed on the substrate; And a microwave transmission line is installed adjacent to one surface of the ferroelectric thin film; Installed adjacent to a ground line on the other surface of the ferroelectric thin film; in the multi-layer thin film structure comprising a one end of the substrate and the tension caused in the ferroelectric direction according to the thermal expansion coefficient difference between the ferroelectric thin film has a microwave transmission line and arranged to The other end of the tension direction is characterized in that made by placing a ground line. ; The present invention, by implementing a multi-layer thin film structure of the new structure, variable reproducibility than the ferroelectric element using the conventional MgO substrate or LAO substrate is high, and can greatly contribute to the variable type microwave device fabrication with a high variable characteristics. Phase converter and filter device to which the invention is applied also has an effect to significantly improve the transmission characteristics and is also very high dielectric loss reducing properties.