Abstract: A piezoelectric resonator includes; a lower electrode 24 formed on a substrate 11; a piezoelectric film 23 formed on the lower electrode 24; an upper electrode 25 formed on the piezoelectric film 23 and obtaining, in collaboration with the lower electrode 24, a signal having a predetermined resonance frequency by a propagation of a bulk acoustic wave inside the piezoelectric film 23; and an acoustic multilayer reflective film 28 including an SiO2 film 28a having a predetermined acoustic impedance and an AIN film 28b having an acoustic impedance higher than the SiO2 film 28a, and reflecting the bulk acoustic wave, the SiO2 film 28a and the AIN film 28b being alternately stacked on the upper electrode 25, and the SiO2 film 28a being in contact with the upper electrode 25.

Abstract: A method of manufacturing a piezoelectric thin film resonator forms, after forming a piezoelectric film on a substrate so as to cover a lower electrode formed on the substrate, an electrode material layer for forming an upper electrode above the piezoelectric film, forms a mask of a predetermined form on the electrode material layer, and then etches the electrode material layer to form the upper electrode. Before a step of forming the electrode material layer, a protective layer for protecting the piezoelectric film during etching of the electrode material layer is formed so as to cover at least a part of the piezoelectric film where the upper electrode is not formed, and the electrode material layer is then formed so as to cover the protective layer.

Abstract: A substrate for an electronic device comprises a base, an adhesion film stacked on the base, and a conductor film stacked on the adhesion film. The adhesion film is a non-epitaxial film including a crystal having a wurtzite crystal structure. The electronic device comprises the substrate and a functional film having a specific function and disposed on the substrate.

Abstract: A filter device is provided which is low in power loss, small in size and operates in wide bands. The filter device includes a first signal-side resonator having an input signal electrode, an output signal electrode, a first piezoelectric film, an input electrode film, and a common electrode film being commonly used by a second signal-side resonator and sandwiching the first piezoelectric film using the input electrode film, a second signal-side resonator having a second piezoelectric film formed in layers on the first piezoelectric film, an output electrode film, a common electrode film sandwiching the second piezoelectric film using the output electrode film and being acoustically coupled to the first signal resonator, and a ground-side resonator connected between the common electrode film and a ground electrode and operating in a specified resonant frequency and in an anti-resonant frequency almost conforming to resonant frequencies in which the first and second signal-side resonators operate.

Abstract: In a filter device 10 constituted by circuit elements formed on a single substrate 11, the circuit elements includes a first wing section 14 formed between an input signal electrode 12 and an output signal electrode 13, first resonators 15a, 15b, 15c located in the first wiring section 14 and having a predetermined resonance frequency, second wiring sections 17a, 17b, 17c, 17d formed between the first wiring section 14 and a ground electrode 16, second resonators 18a, 18b, 18c, 18d located in the second wiring sections 17a, 17b, 17c, 17d and having an anti-resonance frequency forming a pass-band with the predetermined resonance frequency of the first resonators 15a, 15b, 15c. An effective electric and mechanical coupling factor of the second resonator 18a is different from those of the other resonators 15a, 15b, 15c, 18b, 18c, 18d.

Abstract: A thin-film bulk acoustic oscillator comprises: a base; a barrier layer disposed on the base; a lower electrode disposed on the barrier layer; a piezoelectric thin film disposed on the lower electrode; and an upper electrode disposed on the piezoelectric thin film. The piezoelectric thin film includes a columnar crystal that extends in the direction intersecting the film surface. The top surface of the piezoelectric thin film is flattened by polishing so as to have a root mean square roughness of 2 nm or smaller.

Abstract: A method for manufacturing a piezo-resonator including: a first step of forming an upper electrode layer 20 on the piezoelectric film 14, a second step of coating the upper electrode layer 20 with a resist 21 and of performing patterning on the resist so as to have a shape of the upper electrode, a third step of masking the patterned resist 21 and removing the upper electrode layer 20 other than masked portions and forming two or more first upper electrodes 15a, a fourth step of removing the resist 21, a fifth step of coating the first upper electrodes 15a with a resist and performing patterning on the resist so that the first upper electrodes 15a are partially exposed, a sixth step of etching each of the exposed first upper electrodes 15a by a specified thickness to form a second upper electrode 15b, and a seventh step of removing the resist 22.

Abstract: A piezoelectric resonant filter includes a group of series resonators and a group of parallel resonators for forming a ladder-type filter circuit. Each of the resonators has a piezoelectric thin film having piezoelectric characteristic, and lower and upper electrodes disposed on opposite surfaces of the piezoelectric thin film for applying an excitation voltage to the piezoelectric thin film. The group of the parallel resonators exhibits a low frequency side attenuation extremum in the filter whereas the group of the series resonators exhibits a high frequency side attenuation extremum in the filter. At least one of the group of the series resonators and the group of the parallel resonators has a temperature compensating layer for bringing the temperature coefficient of the resonant frequency close to zero.

Abstract: A method for manufacturing a piezo-resonator including: a first step of forming an upper electrode layer 20 on the piezoelectric film 14, a second step of coating the upper electrode layer 20 with a resist 21 and of performing patterning on the resist so as to have a shape of the upper electrode, a third step of masking the patterned resist 21 and removing the upper electrode layer 20 other than masked portions and forming two or more first upper electrodes 15a, a fourth step of removing the resist 21, a fifth step of coating the first upper electrodes 15a with a resist and performing patterning on the resist so that the first upper electrodes 15a are partially exposed, a sixth step of etching each of the exposed first upper electrodes 15a by a specified thickness to form a second upper electrode 15b, and a seventh step of removing the resist 22.

Abstract: An electronic device substrate structure including a substrate 2, a metal thin film 4 as a (111)-oriented film of a face-centered cubic structure or as a (0001)-oriented film of a hexagonal closest packed structure formed on the substrate 2, and a wurtzite type thin film 5 as a (0001)-oriented film of a wurtzite crystal structure formed on the metal thin film 4, wherein: each of the two thin films is a polycrystalline film containing at least two kinds of crystal grains different in direction of crystal orientation in the plane; when the metal thin film 4 is a (111)-oriented film, <11-20> axes in the plane of the wurtzite type thin film 5 are parallel to <1-10> axes in the plane of the metal thin film 4; and when the metal thin film 4 is a (0001)-oriented film, <11-20> axes in the plane of the wurtzite type thin film 5 are parallel to <11-20> axes in the plane of the metal thin film 4.

Abstract: A substrate for an electronic device comprises a base, an adhesion film stacked on the base, and a conductor film stacked on the adhesion film. The adhesion film is a non-epitaxial film including a crystal having a wurtzite crystal structure. The electronic device comprises the substrate and a functional film having a specific function and disposed on the substrate.

Abstract: A filter device is provided which is low in power loss, small in size and operates in wide bands. The filter device includes a first signal-side resonator having an input signal electrode, an output signal electrode, a first piezoelectric film, an input electrode film, and a common electrode film being commonly used by a second signal-side resonator and sandwiching the first piezoelectric film using the input electrode film, a second signal-side resonator having a second piezoelectric film formed in layers on the first piezoelectric film, an output electrode film, a common electrode film sandwiching the second piezoelectric film using the output electrode film and being acoustically coupled to the first signal resonator, and a ground-side resonator connected between the common electrode film and a ground electrode and operating in a specified resonant frequency and in an anti-resonant frequency almost conforming to resonant frequencies in which the first and second signal-side resonators operate.

Abstract: A piezoelectric resonator includes; a lower electrode 24 formed on a substrate 11; a piezoelectric film 23 formed on the lower electrode 24; an upper electrode 25 formed on the piezoelectric film 23 and obtaining, in collaboration with the lower electrode 24, a signal having a predetermined resonance frequency by a propagation of a bulk acoustic wave inside the piezoelectric film 23; and an acoustic multilayer reflective film 28 including an SiO2 film 28a having a predetermined acoustic impedance and an AIN film 28b having an acoustic impedance higher than the SiO2 film 28a, and reflecting the bulk acoustic wave, the SiO2 film 28a and the AIN film 28b being alternately stacked on the upper electrode 25, and the SiO2 film 28a being in contact with the upper electrode 25.

Abstract: A thin-film bulk acoustic oscillator comprises: a base; a barrier layer disposed on the base; a lower electrode disposed on the barrier layer; a piezoelectric thin film disposed on the lower electrode; and an upper electrode disposed on the piezoelectric thin film. The piezoelectric thin film includes a columnar crystal that extends in the direction intersecting the film surface. The top surface of the piezoelectric thin film is flattened by polishing so as to have a root mean square roughness of 2 nm or smaller.

Abstract: In a filter device 10 constituted by circuit elements formed on a single substrate 11, the circuit elements includes a first wing section 14 formed between an input signal electrode 12 and an output signal electrode 13, first resonators 15a, 15b, 15c located in the first wiring section 14 and having a predetermined resonance frequency, second wiring sections 17a, 17b, 17c, 17d formed between the first wiring section 14 and a ground electrode 16, second resonators 18a, 18b, 18c, 18d located in the second wiring sections 17a, 17b, 17c, 17d and having an anti-resonance frequency forming a pass-band with the predetermined resonance frequency of the first resonators 15a, 15b, 15c. An effective electric and mechanical coupling factor of the second resonator 18a is different from those of the other resonators 15a, 15b, 15c, 18b, 18c, 18d.

Abstract: A method of manufacturing a piezoelectric thin film resonator forms, after forming a piezoelectric film on a substrate so as to cover a lower electrode formed on the substrate, an electrode material layer for forming an upper electrode above the piezoelectric film, forms a mask of a predetermined form on the electrode material layer, and then etches the electrode material layer to form the upper electrode. Before a step of forming the electrode material layer, a protective layer for protecting the piezoelectric film during etching of the electrode material layer is formed so as to cover at least a part of the piezoelectric film where the upper electrode is not formed, and the electrode material layer is then formed so as to cover the protective layer.

Abstract: A piezoelectric resonant filter includes a group of series resonators and a group of parallel resonators for forming a ladder-type filter circuit. Each of the resonators has a piezoelectric thin film 15 having piezoelectric characteristic, and lower and upper electrodes 14 and 16 disposed on opposite surfaces of the piezoelectric thin film 15 for applying an excitation voltage to the piezoelectric thin film 15. The group of the parallel resonators exhibits a low frequency side attenuation extremum in the filter whereas the group of the series resonators exhibits a high frequency side attenuation extremum in the filter. At least one of the group of the series resonators and the group of the parallel resonators has a temperature compensating layer 20 for bringing the temperature coefficient of the resonant frequency close to zero.

Abstract: An electronic device substrate structure including a substrate 2, a metal thin film 4 as a (111)-oriented film of a face-centered cubic structure or as a (0001)-oriented film of a hexagonal closest packed structure formed on the substrate 2, and a wurtzite type thin film 5 as a (0001)-oriented film of a wurtzite crystal structure formed on the metal thin film 4, wherein: each of the two thin films is a polycrystalline film containing at least two kinds of crystal grains different in direction of crystal orientation in the plane; when the metal thin film 4 is a (111)-oriented film, <11-20> axes in the plane of the wurtzite type thin film 5 are parallel to <1-10> axes in the plane of the metal thin film 4; and when the metal thin film 4 is a (0001)-oriented film, <11-20> axes in the plane of the wurtzite type thin film 5 are parallel to <11-20> axes in the plane of the metal thin film 4.

Abstract: The invention has for its objects to provide a multilayer thin film comprising a ferroelectric thin film preferentially (001) oriented on an Si substrate, its fabrication process, and an electron device. To attain these object, the invention provides a multilayer thin film formed on a substrate by epitaxial growth, which comprises a buffer layer comprising an oxide and a ferroelectric thin film, with a metal thin film and an oxide thin film formed in this order between the buffer layer and the ferroelectric thin film, its fabrication process, and an electron device.

Abstract: The invention has for its objects to provide a multilayer thin film comprising a ferroelectric thin film preferentially (001) oriented on an Si substrate, its fabrication process, and an electron device. To attain these object, the invention provides a multilayer thin film formed on a substrate by epitaxial growth, which comprises a buffer layer comprising an oxide and a ferroelectric thin film, with a metal thin film and an oxide thin film formed in this order between the buffer layer and the ferroelectric thin film, its fabrication process, and an electron device.