A SAW device manufacturing method includes a piezoelectric ceramic substrate polishing step of polishing a first surface of the piezoelectric ceramic substrate, a support substrate polishing step of polishing a first surface of the support substrate, a bonding step of bonding the first surface of the piezoelectric ceramic substrate to the first surface of the support substrate to thereby form a stacked substrate, a grinding step of grinding a second surface of the piezoelectric ceramic substrate, and a vibration diffusion layer forming step of applying a laser beam to the stacked substrate in the condition where the focal point of the laser beam is positioned inside the piezoelectric ceramic substrate to thereby form a modified layer as a vibration diffusion layer inside the piezoelectric ceramic substrate.

Laser-marked packaged surface acoustic wave devices are provided. The laser-marked packaged surface acoustic wave device may include a package structure encapsulating a surface acoustic wave device on a first side of a piezoelectric substrate. The opposite side of the piezoelectric substrate can be directly marked using a laser. The laser may be a deep ultraviolet laser. By directly marking the piezoelectric substrate itself, the use of a separate marking film can be avoided, making the packaged surface acoustic wave device thinner. When the laser has a wavelength readily absorbed by the piezoelectric substrate, a relatively shallow marking may be made in the piezoelectric substrate. The markings can extend less than 1 micrometer into the piezoelectric substrate, so as not to affect the structural integrity of the piezoelectric substrate or the operation of the packaged surface acoustic wave device.

A substrate for a surface acoustic wave device is constituted of a piezoelectric material and includes a first surface on which a surface acoustic wave propagates, and a second surface located opposite to the first surface. The second surface has an arithmetic mean roughness (Ra) of 0.2 m to 0.4 m, and there is satisfied either of the relationship between the arithmetic mean roughness (Ra) and mean spacing (S) of local peaks of Ra/S11, and the relationship between the arithmetic mean roughness (Ra) and mean spacing (Sm) of irregularities of Ra/Sm6.7. Further, the second surface has a maximum height (Rmax) of 2.5 m to 4.5 m, and there is satisfied either of the relationship between the maximum height (Rmax) and mean spacing (S) of local peaks of Rmax/S130, and the relationship between the maximum height (Rmax) and mean spacing (Sm) of irregularities of Rmax/Sm80.

A hybrid structure for a surface acoustic wave device comprises a useful layer of piezoelectric material having a free first surface and a second surface disposed on a support substrate that has a lower coefficient of thermal expansion than that of the useful layer. The hybrid structure further comprises a trapping layer disposed between the useful layer and the support substrate, and at least one functional interface of predetermined roughness between the useful layer and the trapping layer.

A surface acoustic wave device includes: a substrate; an electrode disposed on the substrate in a first direction; a dummy bar disposed to be spaced apart from the electrode by a predetermined distance in the first direction; and an additional film formed on the dummy bar, wherein the electrode and the dummy bar are disposed in plurality in parallel in a second direction perpendicular to the first direction, and the dummy bars are alternately disposed on a left side or a right side of the electrode to be spaced apart from the electrode by the predetermined distance, and the additional film is formed on the predetermined distance between the electrode and the dummy bar and on the plurality of dummy bars.

An acoustic wave resonator includes: a piezoelectric substrate; a pair of comb-shaped electrodes that is located on the piezoelectric substrate and excites an acoustic wave, each of the pair of comb-shaped electrodes including a plurality of electrode fingers; and a polycrystalline substrate that is located at an opposite side of the piezoelectric substrate from a surface on which the pair of comb-shaped electrodes is located, an average particle size of the polycrystalline substrate being equal to or less than 66 times an average pitch of the plurality of electrode fingers.

A structure includes a substrate including a wafer or a portion thereof; and a piezoelectric bulk material layer comprising a first portion deposited onto the substrate and a second portion deposited onto the first portion, the second portion comprising an outer surface having a surface roughness (Ra) of 4.5 nm or less. Methods for depositing a piezoelectric bulk material layer include depositing a first portion of bulk layer material at a first incidence angle to achieve a predetermined c-axis tilt, and depositing a second portion of the bulk material layer onto the first portion at a second incidence angle that is smaller than the first incidence angle. The second portion has a second c-axis tilt that substantially aligns with the first c-axis tilt.

A method for processing a lithium tantalate crystal substrate includes providing a lithium tantalate crystal substrate and a metallic sheet, roughening at least one of the lithium tantalate crystal substrate and the metallic sheet, bringing the lithium tantalate crystal substrate and the metallic sheet into contact with each other after the at least one thereof is roughened, and subjecting the lithium tantalate crystal substrate to a reduction treatment. The reduction treatment is conducted at a temperature not higher than a Curie temperature of the lithium tantalate crystal substrate.

A SAW device manufacturing method includes a piezoelectric ceramic substrate polishing step of polishing a first surface of the piezoelectric ceramic substrate, a support substrate polishing step of polishing a first surface of the support substrate, a bonding step of bonding the first surface of the piezoelectric ceramic substrate to the first surface of the support substrate to thereby form a stacked substrate, a grinding step of grinding a second surface of the piezoelectric ceramic substrate, and a vibration diffusion layer forming step of applying a laser beam to the stacked substrate in the condition where the focal point of the laser beam is positioned inside the piezoelectric ceramic substrate to thereby form a modified layer as a vibration diffusion layer inside the piezoelectric ceramic substrate.

A bonded body includes a supporting body composed of a ceramic, a bonding layer provided over a surface of the supporting body and composed of one or more material selected from the group consisting of mullite, alumina, tantalum pentoxide, titanium oxide and niobium pentoxide, and a piezoelectric single crystal substrate bonded with the bonding layer. The surface of the supporting body has an arithmetic average roughness Ra of 0.5 nm or larger and 5.0 nm or smaller.