A substrate includes a first substrate which has a first substrate through hole, and a second substrate which has a second substrate through hole and directly or indirectly overlaps the first substrate, the first substrate through hole and the second substrate through hole directly or indirectly communicate with each other to form a liquid supply path and a width D1 of an opening portion of the first substrate through hole on a surface of the first substrate closer to the second substrate, a width D2 of an opening portion of the second substrate through hole on a surface of the second substrate closer to the first substrate, a width D3 of an opening portion of the second substrate through hole on a surface of the second substrate farther from the first substrate have a relationship of D1<D2 and D3<D2.

A liquid discharging head includes a nozzle configured to discharge liquid, a pressure chamber communicated with the nozzle, and an individual channel communicated with the pressure chamber through a narrow part. The liquid discharging head also includes a common channel communicated with the individual channel, an energy generation element configured to generate energy, and a diaphragm configured to convey the energy to the pressure chamber. A metal oxide film is formed at inner walls of the nozzle, the pressure chamber, the narrow part, the diaphragm, and the individual channel, and a hydroxyl group has come out from the metal oxide film.

Provided are a liquid jetting structure and its applications. The liquid jetting structure includes: a nozzle substrate on which a nozzle for jetting a liquid is formed; and a flow passage substrate on which a liquid flow passage communicating with the nozzle is formed, in which a first layer, a second layer, and a liquid-repellent layer are provided in this order on a jetting surface of the nozzle substrate, the first layer and the second layer are provided in this order on an inner wall of the liquid flow passage, the first layer is a layer containing at least one selected from the group consisting of tantalum oxide, zirconium oxide, titanium oxide, and hafnium oxide, and the second layer is a layer containing at least one selected from the group consisting of SiO.sub.2, SiC, SiN, SiCN, and SiON.

A method for manufacturing a liquid discharge head comprising: a substrate, a protective layer covering at least a part of the substrate, and a laminate member formed on the protective layer, wherein the method comprises steps of: forming the protective layer on at least a part of the substrate; forming the laminate member on the protective layer with a part of the protective layer exposed, the protective layer comprises at least Si and C, a content of oxygen in a bulk of the protective layer is less than 20 atomic % in terms of an element composition ratio, a modified layer with a content of oxygen of 20 atomic % or more in terms of an element composition ratio is present on a surface of the protective layer, and a thickness of the modified layer between the protective layer and the laminate member is 3.40 nm or less.

A substrate with an electrical connection section or a substrate for liquid ejection head comprises a wiring layer, a diffusion prevention layer laid on the wiring layer and a connection member laid on the diffusion prevention layer for establishing an electrical connection to an outside. An insulation layer having a wiring-layer-exposing opening is arranged on the wiring layer and the diffusion prevention layer is arranged in the opening, while the connection member is arranged on the diffusion prevention layer so as to cover an outer peripheral edge of the diffusion prevention layer.

An actuator includes a substrate, a diaphragm on the substrate, a lower electrode on the diaphragm, a piezoelectric body on the lower electrode, and an upper electrode on the piezoelectric body. A ratio of lead (Pb) and zirconium (Zr) in atomic percent (atm %) present at a grain boundary in the piezoelectric body satisfies a relation of Pb/Zr>1.7.

A substrate joined body including: a first substrate; a second substrate; an organic film that comprises silicon and carbon and joins the first substrate and the second substrate; and a protective film that comprises an inorganic element and is formed over the organic film from at least a part of the surface of the first substrate and at least a part of the surface of the second substrate, wherein the protective film comprises a region in which the ratio of carbon to silicon based on atomic percentage is from 0.0 to 5.0 in a region within 50 nm in a thickness direction from a surface of the organic film on the protective film side, when the surface is measured by X-ray photoelectron spectroscopy.

Disclosed is a method of manufacturing, a metal nozzle plate, in which is formed a nozzle for discharging a liquid and that is to be bonded with adhesive to a head chip provided with an actuator for discharging the liquid, the method including: forming the nozzle in a metal plate-like member; forming a groove in the metal plate-like member; and performing exterior processing with respect to the nozzle plate.

A piezoelectric device includes a substrate, a diaphragm; and a piezoelectric actuator, in which the substrate, the diaphragm, and the piezoelectric actuator are laminated in this order in a first direction, the diaphragm includes a first layer containing silicon as a constituent element, a third layer disposed between the first layer and the piezoelectric actuator and containing zirconium as a constituent element, and a second layer disposed between the first layer and the third layer and containing at least one impurity element selected from the group consisting of a metal, a metalloid, and a semiconductor other than silicon and zirconium, as a constituent element, and the impurity element diffuses into the third layer.

The diaphragm includes a first layer containing silicon as a constituent element, a third layer disposed between the first layer and the piezoelectric actuator and containing zirconium as a constituent element, and a second layer disposed between the first layer and the third layer and containing at least one selected from the group consisting of a metal other than iron, silicon, and zirconium, a metalloid, and a semiconductor, as a constituent element, in the second layer and the third layer, a position with a highest concentration of impurities other than the constituent elements of the second layer and the third layer is in the second layer, a position with a highest concentration of zirconium is in the third layer, and a position with a highest concentration of silicon is in the first layer.