Elastic wave device and method for producing the same

A method for producing an elastic wave device, the method comprising:

• forming an IDT electrode on a piezoelectric thin film including first and second main surfaces opposite to each other;
• forming a sacrificial layer on the first main surfaces of the piezoelectric thin film so as to cover the IDT electrode;
• forming a supporting substrate, which includes an upper surface with a recessed portion formed therein, so as to cover the sacrificial layer;
• forming an intermediate layer including third and fourth main surfaces opposite to each other, the intermediate layer being formed on the second main surface, the second main surfaces being remote from the sacrificial layer;
• forming a through hole in the piezoelectric thin film and the intermediate layer so that the through hole extends from the third main surface to the sacrificial layer, the third main surface being remote from the piezoelectric thin film;
• removing the sacrificial layer by etching through the through hole so that a portion where the sacrificial layer has been formed forms a space;
• and
• forming a cover member on the one of the main surfaces of the intermediate layer remote from the piezoelectric thin film so as to cover an opening end of the through hole.