Piezoelectric device and a package

A piezoelectric device comprising:

• a piezoelectric plate provided with at least one electrode at almost a central portion corresponding to a thinner portion of each face, one face thereof having a recessed portion, the other face thereof being made flat,
• a first plate made of an ionic material having a recessed portion to cover said at least one electrode at one face to face said flat face of said piezoelectric plate, and
• a second plate made of an ionic material having a flat face to face said face having said recessed portion of said piezoelectric plate,
• wherein each of said at least one electrodes is formed, and then packaged by direct bonding said piezoelectric plate with said first plate and said second plate so as to be sandwiched therebetween with no intervening adhesive or structure and subsequently annealing the device at a temperature where said piezoelectric plate is crystallographically stable.

A piezoelectric device comprising:

• a piezoelectric plate provided with at least one electrode at almost a central portion corresponding to a thinner portion of each face having a recessed portion,
• a first plate made of an ionic material having a flat face to face said piezoelectric plate, and
• a second plate made of an ionic material having a flat face to face said piezoelectric plate,
• wherein each of said at least one electrodes is formed, and then packaged by direct bonding said piezoelectric plate with said first plate and said second plate so as to be sandwiched therebetween with no intervening adhesive or structure and subsequently annealing the device at a temperature where said piezoelectric plate is crystallographically stable.

A method of making a piezoelectric device comprising the steps of:

• providing a piezoelectric plate;
• forming at least one electrode at almost a central portion of each face of the piezoelectric plate;
• providing a first plate made of an ionic material having a recessed portion to cover said at least one electrode at one face to face said piezoelectric plate;
• providing a second plate made of an ionic material having a recessed portion to cover said at least one electrode at one face to face said piezoelectric plate;
• packaging each of said at least one electrodes by direct bonding said piezoelectric plate with said first plate and said second plate so as to be sandwiched therebetween with no intervening adhesive or structure;
• and,
• annealing the device at a temperature where said piezoelectric plate is crystallographically stable.