Method for manufacturing resonator
A method for manufacturing a resonator of the present invention includes the steps of (a) forming a resonator film including a piezoelectric film made of piezoelectric material and (b) preparing a resonator substrate for supporting the resonator film. The method further comprises the step of (c) bonding the resonator film formed in the step (a) and the resonator substrate prepared in the step (b).
1. A method for manufacturing a resonator comprising the steps of:
forming a piezoelectric film, and a second thin film to be a lower electrode on a preparation substrate in this order;
forming a third thin film having an opening on a resonator substrate;
forming an air gap by bonding the second thin film and the third thin film;
after the step of forming the air gap, removing the preparation substrate; and
after the step of removing the preparation substrate, forming an upper electrode on the piezoelectric film.
2. The method according to claim 1 , wherein
in the step of forming the second thin film, the second thin film is formed to include Sn, and
in the step of forming the third thin film, the third thin film is formed to include Au.
3. A method for manufacturing a resonator comprising the steps of:
forming a piezoelectric film, a conductive film to be a lower electrode, and a first layer having an opening on a preparation substrate in this order;
forming an air gap by bonding the first layer to a main surface of a resonator substrate;
after the step of forming the air gap, removing the preparation substrate; and
after the step of removing the preparation substrate, forming an upper electrode on the piezoelectric film.
4. The method according to claim 3 , wherein
the first layer is a conductive film.
5. The method according to claim 1 , wherein
the step of forming the piezoelectric film on the preparation substrate includes forming a buffer layer between the preparation substrate and the piezoelectric film, and
the buffer layer is made of a AlN film and a GaN film formed on the preparation substrate in this order.
6. The method according to claim 1 , further comprising the step of:
before the step of forming the piezoelectric film, forming a first thin film on the preparation substrate, wherein
the piezoelectric film is formed to be in contact with the first thin film.
7. The method according to claim 6 , wherein
the first thin film is a conductive film to be an upper electrode, and
the second thin film is a conductive film to be a lower electrode.
8. The method according to claim 1 , wherein the preparation substrate is removed by wet etching.
9. The method according to chum 1 , wherein the preparation substrate is removed by dry etching.
10. The method according to claim 1 , wherein
the preparation substrate is made of SiC or sapphire.
11. A method for manufacturing a resonator comprising the steps of:
forming a piezoelectric film on a preparation substrate;
forming a through hole on a resonator substrate;
forming an air gap by bonding the piezoelectric film and the resonator substrate directly;
after the step of forming the air gap, removing the preparation substrate; and
after the step of removing the preparation substrate, forming an upper electrode on the piezoelectric film, and a lower electrode below the piezoelectric film.
12. A method for manufacturing a resonator comprising the steps of:
forming a piezoelectric film, and a second thin film to be a lower electrode on a preparation substrate in this order;
forming a through hole on a resonator substrate;
forming an air gap by bonding the second thin film and the resonator substrate directly;
after the step of forming the air gap, removing the preparation substrate; and
after the step of removing the preparation substrate, forming an upper electrode on the piezoelectric film.
13. A method for manufacturing a resonator comprising the steps of:
forming a piezoelectric film, and a second thin film to be a lower electrode on a preparation substrate in this order;
forming a concave on a resonator substrate;
forming an air gap by bonding the second thin film and the resonator substrate directly;
after the step of forming the air gap, removing the preparation substrate; and
after the step of removing the preparation substrate, forming an upper electrode on the piezoelectric film.