Piezoelectric micro-acoustic transducer and method of fabricating the same
Provided are a piezoelectric micro-acoustic transducer and a method of fabricating the same. In the piezoelectric micro-acoustic transducer, a diaphragm is divided into a first region and a second region. The first region may be formed of a material capable of maximizing the exciting force, and the second region may be formed of a material having less initial stress and a lower Young's modulus than the first region. Also, the second region has a corrugated shape.
1. A piezoelectric micro-acoustic transducer comprising:
a substrate comprising a hole formed therethrough; and
a diaphragm which is disposed on the substrate and covers the hole, the diaphragm comprising:
a first vibration layer which covers a first region of the hole, and
a second vibration layer which covers a second region of the hole,
wherein a Young's modulus of the second vibration layer is lower than a Young's modulus of the first vibration layer, and the second vibration layer has a corrugated shape.
2. The piezoelectric micro-acoustic transducer of claim 1 , wherein the first region corresponds to a center of the hole and the second region corresponds to an edge of the hole.
3. The piezoelectric micro-acoustic transducer of claim 2 , further comprising:
a piezoelectric driver disposed on the first vibration layer, the piezoelectric driver comprising a first electrode layer, a piezoelectric layer, and a second electrode layer stacked on the first vibration layer; and
a feeder cable unit which is electrically connected to the first electrode layer and the second electrode layer, and having a corrugated shape corresponding to the corrugated shape of the second vibration layer.
4. The piezoelectric micro-acoustic transducer of claim 3 , further comprising:
a first pad and a second pad, each connected to an external power supply,
wherein the feeder cable unit connects the first pad to the first electrode layer through the second region and connects the second pad with the second electrode layer through the second region.
5. A piezoelectric microspeaker comprising:
a substrate comprising a hole formed therethrough;
a diaphragm comprising:
a first vibration layer disposed in a first region of the hole, and
a second vibration layer disposed in the first portion over the first vibration layer and in a second region of the hole, such that the second vibration layer overlaps the hole and an area of the substrate surrounding the hole;
wherein a portion of the second vibration layer disposed in the second region has a corrugated shape; and
wherein a Young's modulus of the second portion is lower than a Young's modulus of the first portion.
6. The piezoelectric microspeaker of claim 5 , further comprising:
a piezoelectric driver disposed in the first region between the first vibration layer and the second vibration layer, the piezoelectric driver comprising:
a first electrode layer disposed on the first vibration layer,
a piezoelectric layer disposed on the first electrode layer, and
a second electrode layer disposed on the piezoelectric layer;
a first feeder cable unit electrically connected to the first electrode layer and extending through the second region; and
a second feeder cable unit electrically connected to the second electrode layer and extending though the second region;
wherein the first and second feeder cable units each have corrugated shapes corresponding to the corrugated shape of the section vibration layer in the second region.