Multilayer structure for an elastic wave device

Abstract

The invention relates to a multilayer structure configured for an elastic wave device (11), in particular guided or quasi-guided with losses less than 5mdB / λ, the elastic wave device comprising at least one transducer (19) and operating with an elastic wave with a shear wavelength λ and preferably with a frequency less than 1GHz, in particular with a frequency between 500 MHz and 1 GHz, the multilayer structure comprising: a piezoelectric layer (3), a dielectric layer (5), and a base substrate (7), the piezoelectric layer (3) being made of lithium tantalate LiTaO3 (LTO), the dielectric layer (5) being made of silicon oxide (SiO2) and the base substrate (7) being a silicon substrate, in particular silicon (100) or (111).This structure is characterized in that the piezoelectric layer (3) has an orientation (YXl) / θ with θ between 30° and 50°, preferably θ = 42° or θ = 50° according to the IEEE 1949 std-176 standard definition, hLTO / λ is between 0.10 and 0.30, in particular between 0.15 and 0.25, hLTO being the thickness of the piezoelectric layer and λ the shear wavelength of the elastic wave device, and hSiO2 / λ is greater than 0.10, preferably between 0.15 and 0.30, hSiO2 being the thickness of the dielectric layer. The invention also relates to a manufacturing method. Fig. 1.