Piezoelectric microphone
The present invention discloses a piezoelectric microphone. The piezoelectric microphone comprises a substrate having a cavity-backed, and a piezoelectric film connected to the upper side of the substrate via an insulating layer. A position on the piezoelectric film, which is located at the inner side of a junction of the piezoelectric film and the substrate, is provided with a plurality of hollowed-out holes. The hollowed-out holes in the piezoelectric film are at least partly overlapped with the substrate. A gap is provided between the substrate and the position, where the hollowed-out holes are located, on the piezoelectric film. The gap and the hollowed-out holes a together form a channel. Compared with the traditional hollowed-out structure, the gap of the present invention can hinder the sound from directly spreading via the hollowed-out holes, thereby greatly reducing the amount of leakage of low-and-intermediate frequency signals of the piezoelectric microphone and improving the performance of the piezoelectric microphone. In addition, the gap can also effectively prevent a chip from being damaged by the invasion of dust, particles and water.
1. A piezoelectric microphone, comprising:
a substrate having a cavity-backed; and
a piezoelectric film connected to the upper side of the substrate via an insulating layer, wherein:
a position on the piezoelectric film, which is located at the inner side of a junction of the piezoelectric film and the substrate, is provided with a plurality of hollowed-out holes;
the hollowed-out holes in the piezoelectric film are at least partly overlapped with the substrate;
a gap is provided between the substrate and the position, where the hollowed-out holes are located, on the piezoelectric film; and
the gap and the hollowed-out holes together form a channel.
2. The piezoelectric microphone according to claim 1 , wherein the plurality of hollowed-out holes is distributed around the cavity-back of the substrate.
3. The piezoelectric microphone according to claim 1 , wherein the insulating layer between the substrate and the piezoelectric film is of a continuous ring structure.
4. The piezoelectric microphone according to claim 1 , wherein the insulating layer between the substrate and the piezoelectric film is of a discontinuous ring structure.
5. The piezoelectric microphone according to claim 4 , wherein the hollowed-out holes penetrate to the edge of the piezoelectric film and are distributed between two discontinuous insulating layers in an opposing manner.
6. The piezoelectric microphone according to claim 1 , wherein a portion on the piezoelectric film from the hollowed-out holes to the center of the piezoelectric film is overlapped with the substrate.
7. The piezoelectric microphone according to claim 1 , wherein the gap between the piezoelectric film and the substrate is 0.5 um to 3 um.
8. The piezoelectric microphone according to claim 1 , wherein the hollowed-out holes are circular, rectangular, oval, fan-shaped or trapezoidal.
9. The piezoelectric microphone according to claim 1 , wherein the piezoelectric film sequentially comprises a first electrode layer, a piezoelectric intermediate layer and a second electrode layer which are combined together.
10. The piezoelectric microphone according to claim 9 , wherein the first electrode layer, the piezoelectric intermediate layer and the second electrode layer are combined together by way of deposition.