Liquid ejecting head and manufacturing method

A method for manufacturing a piezoelectric device in which

• a first substrate, a second substrate, a diaphragm, and a piezoelectric element are stacked in this order,
• the method comprising:
• a step of depositing a flexible film as the diaphragm on one side of the second substrate;
• a step of forming the piezoelectric element on the flexible film;
• a step of forming a space in the second substrate, the step including forming
• a first opening located on the one side of the second substrate,
• a second opening located on the other side of the second substrate, and
• a wall portion coupling the first opening to the second opening, the wall portion including at least one recess portion and at least one protruding portion located farther than the at least one recess portion from the second opening and the at least one protruding portion being closer to the second opening than a bottom of the at least one recess portion;
• and
• a step of bonding, by using an adhesive, the first substrate at the other side of the second substrate disposed with the second opening up.

A liquid ejecting head comprising:

• a flow channel substrate having a space forming a flow channel guiding liquid to a nozzle;
• a pressure chamber substrate having a pressure chamber space coupled to the space of the flow channel substrate;
• a diaphragm disposed at a position overlapping the pressure chamber space;
• and
• an actuator that vibrates the diaphragm to apply pressure to the liquid inside the pressure chamber space, wherein
• the flow channel substrate, the pressure chamber substrate, the diaphragm, and the actuator are stacked in this order in a first direction,
• the flow channel substrate and the pressure chamber substrate are bonded by an adhesive, and
• the pressure chamber substrate includes
• a first opening formed in a surface on a diaphragm side and exposing a portion of the diaphragm to the pressure chamber space,
• a second opening formed in a surface on a flow channel substrate side, and coupling the pressure chamber space to the flow channel,
• a first wall portion being an inner wall portion partitioning the pressure chamber space and coupling the first opening to the second opening,
• a first recess portion formed on the first wall portion and recessed in the first direction, and
• a first protruding portion formed on the first wall portion and protruding in a direction opposite to the first direction, the protruding portion being disposed between the first recess portion and the first opening in a direction from the second opening toward the first opening, the first protruding portion being closer to the second opening than a bottom of the first recess portion.