Film bulk acoustic resonator and method of forming the same

A film bulk acoustic resonator having an activation area resonating with a predetermined frequency signal, comprising:

• a substrate;
• a membrane support layer formed on the substrate and having an air gap;
• a membrane layer formed on the membrane support layer and having a portion corresponding to the activation area and having a thickness less than the other portion of the membrane layer;
• a first electrode formed on the membrane layer;
• a piezoelectric layer formed on the first electrode layer;
• and
• a second electrode formed on the piezoelectric layer.

A film bulk acoustic resonator having an activation area resonating with a predetermined frequency signal, comprising:

• a substrate;
• a membrane support layer formed on the substrate and having an air gap;
• a membrane layer formed on the membrane support layer;
• a first electrode formed on the membrane layer;
• a piezoelectric layer formed on the first electrode layer;
• a second electrode formed on the piezoelectric layer;
• and
• at least one via hole formed in the first electrode, the piezoelectric layer, and the second electrode to communicate with the air gap.

A film bulk acoustic resonator having an activation area resonating with a predetermined frequency signal, comprising:

• a substrate having the high insulation resistance selected from a group of consisting of non-doped high resistance Si wafer(>5000 Ω), glass wafer, quartz wafer, sapphire, LiNbO3 and LiTiO3;
• a membrane support layer formed on the substrate and having an air gap;
• a membrane layer formed on the membrane support layer;
• a first electrode formed on the membrane layer;
• a piezoelectric layer formed on the first electrode layer;
• and
• a second electrode formed on the piezoelectric layer.

A method of forming a film bulk acoustic resonator having an activation area resonating with a predetermined frequency signal, the method comprising:

• forming an insulation layer on a substrate;
• forming a sacrificing layer on the insulation layer;
• partially removing the sacrificing layer except a portion of the sacrificing layer corresponding to an air gap forming area;
• forming a membrane support layer on the insulation layer on which the sacrificing layer is removed;
• forming a membrane layer on the membrane support layer and the portion of the sacrificing layer;
• forming a first electrode on the membrane layer;
• forming a piezoelectric layer on the first electrode layer;
• forming a second electrode on the piezoelectric layer;
• and
• forming an air gap by removing the portion of the sacrificing layer.

A method of forming a film bulk acoustic resonator having an activation area resonating with a predetermined frequency signal, the method comprising:

• forming a sacrificing layer on a substrate;
• partially removing the sacrificing layer except a portion of the sacrificing layer corresponding to an air gap forming area;
• forming a membrane support layer on the insulation layer on which the sacrificing layer is removed;
• forming a membrane layer on the membrane support layer and the portion of the sacrificing layer;
• etching on a top surface of the membrane layer corresponding to the activation area using a dry etching process to have a predetermined thickness;
• forming a first electrode on the membrane layer;
• forming a piezoelectric layer on the first electrode layer;
• forming a second electrode on the piezoelectric layer;
• and
• forming an air gap by removing the portion of the sacrificing layer.

A method of forming a film bulk acoustic resonator having an activation area resonating with a predetermined frequency signal, the method comprising:

• forming a sacrificing layer on a substrate;
• partially removing the sacrificing layer except a portion of the sacrificing layer corresponding to an air gap forming area;
• forming a membrane support layer on the insulation layer on which the sacrificing layer is removed;
• forming a membrane layer on the membrane support layer and the portion of the sacrificing layer;
• forming a first electrode on the membrane layer;
• forming a piezoelectric layer on the first electrode layer;
• forming a second electrode on the piezoelectric layer;
• forming at least one via hole in the first electrode, the piezoelectric layer, and the second electrode to couple an external portion to the sacrificing layer;
• and
• forming an air gap by removing the portion of the sacrificing layer.