Piezoelectric actuator device and method for manufacturing same

A piezoelectric actuator device comprising:

• a vibrator including:
• a lower vibration layer configured to vibrate, and
• an upper vibration layer coupled to an upper surface of the lower vibration layer and configured to vibrate together with the lower vibration layer;
• and
• a driver configured to vibrate the vibrator, the driver including:
• an upper electrode layer provided on a lower surface of the lower vibration layer,
• a piezoelectric layer provided on a lower surface of the upper electrode layer, and
• a lower electrode layer provided on a lower surface of the piezoelectric layer, the driver being configured to vibrate the vibrator,
• wherein the lower vibration layer of the vibrator is mainly made of certain organic material,
• wherein the upper vibration layer of the vibrator is mainly made of certain inorganic material,
• wherein the lower vibration layer has a smaller longitudinal elastic modulus than the upper vibration layer, and
• wherein the lower vibration layer and the upper vibration layer are configured such that:
• the lower vibration layer is made of one or more first inorganic materials and one or more first organic materials including the certain organic material, and a total of volume ratios of volumes of the one or more first organic materials to a volume of the lower vibration layer is not smaller than ⅓, and is larger than a volume ratio of a volume of each of the one or more first inorganic materials to the volume of the lower vibration layer;
• or
• the upper vibration layer is made of one or more second organic materials and one or more second inorganic materials including the certain inorganic material, and a total of volume ratios of volumes of the one or more second inorganic materials to a volume of the upper vibration layer is not smaller than ⅓, and is larger than a volume ratio of each of volumes of the one or more second organic materials to the volume of the upper vibration layer.

A method for manufacturing a piezoelectric actuator device, comprising:

• forming a driver which includes a lower electrode layer provided on an upper surface of a substrate, a piezoelectric layer provided on an upper surface of the lower electrode layer, and an upper electrode layer provided on an upper surface of the piezoelectric layer;
• forming a lower vibration layer mainly made of certain organic material on an upper surface of the upper electrode layer of the driver by a photo-crosslinking reaction with use of photosensitive elastic resin;
• and
• forming an upper vibration layer mainly made of certain inorganic material on an upper surface of the lower vibration layer by a plating method,
• wherein the lower vibration layer has a smaller longitudinal elastic modulus than the upper vibration layer, and
• wherein the lower vibration layer and the upper vibration layer are configured such that:
• the lower vibration layer is made of one or more first inorganic materials and one or more first organic materials including the certain organic material, and a total of volume ratios of volumes of the one or more first organic materials to a volume of the lower vibration layer is not smaller than ⅓, and is larger than a volume ratio of a volume of each of the one or more first inorganic materials to the volume of the lower vibration layer;
• or
• the upper vibration layer is made of one or more second organic materials and one or more second inorganic materials including the certain inorganic material, and a total of volume ratios of volumes of the one or more second inorganic materials to a volume of the upper vibration layer is not smaller than ⅓, and is larger than a volume ratio of each of volumes of the one or more second organic materials to the volume of the upper vibration layer.