Film bulk acoustic resonator
Disclosed is a film bulk acoustic resonator (FBAR) including a substrate, a lower electrode formed above the substrate, a piezoelectric layer formed above the lower electrode, an upper electrode formed above the piezoelectric layer, and a first protection layer formed above the upper electrode. Here, the first protection layer covers the upper electrode while extending downward along a side surface of one end of the upper electrode to cover a certain area of the piezoelectric layer.
1. A film bulk acoustic resonator (FBAR) comprising:
a substrate;
a lower electrode formed above the substrate;
a piezoelectric layer formed above the lower electrode;
an upper electrode formed above the piezoelectric layer; and
a first protection layer formed above the upper electrode,
wherein the first protection layer covers the upper electrode while extending downward along a side surface of one end of the upper electrode to cover a certain area of the piezoelectric layer,
wherein the first protection layer seals an air gap formed between a lower end of the one end of the upper electrode and the piezoelectric layer,
wherein the first protection layer has a layer thickness for covering the piezoelectric layer which is at least greater than a gap height of the air gap, and
wherein the FBAR further includes a second protection layer formed between the first protection layer and the upper electrode, and the second protection layer covers the upper electrode.
2. The FBAR of claim 1 , wherein the first protection layer includes one or more dielectric materials of SiO x and SiN x (here, x is a positive real number greater than 0).
3. The FBAR of claim 1 , wherein the second protection layer includes one or more dielectric materials of AlN x , SiO x , and SiN x (here, x is a positive real number greater than 0).