Acoustic transducer and method for manufacturing acoustic transducer

Patent metadata

Field	Value
Publication number	US-12267646-B2
Application number	US-202318110860-A
Country	US
Kind code	B2
Filing date	Feb 16, 2023
Priority date	Feb 16, 2023
Publication date	Apr 1, 2025
Grant date	Apr 1, 2025

Abstract

An acoustic transducer includes: substrate including first silicon layer, first oxide layer and second silicon layer, back chamber is formed therethrough; second oxide layer on the substrate; piezoelectric unit on the second oxide layer and including first electrode layer, piezoelectric layer and second electrode layer; slit and opening formed in the second electrode layer; metal pad stacked on the first electrode layer at the opening; and additional film layer including first, second and third parts, the first part is in the slit, side wall and bottom wall of the first part form groove, and through slot is formed in the third part to expose metal pad.

First claim

What is claimed is:

1. An acoustic transducer, comprising:
a substrate including a first silicon layer, a first oxide layer and a second silicon layer sequentially stacked from bottom to top, wherein a back chamber is formed in the substrate, the back chamber sequentially penetrates through the first silicon layer and the first oxide layer, and the second silicon layer is exposed by the back chamber;
a second oxide layer formed on the substrate;
a piezoelectric unit formed on the second oxide layer and including a first electrode layer, a piezoelectric layer and a second electrode layer sequentially stacked from bottom to top;
a slit formed in the middle of the second electrode layer and penetrating through the second electrode layer, the piezoelectric layer, the first electrode layer, the second oxide layer and the second silicon layer;
an opening formed at an edge of the second electrode layer and penetrating through the second electrode layer and the piezoelectric layer, wherein the first electrode layer is exposed by the opening;
a metal pad stacked on the first electrode layer at the opening; and
an additional film layer including a first part, a second part and a third part, wherein the first part is formed in the slit, a side wall of the first part is attached to an inner wall surface of the slit, a bottom wall of the first part covers a bottom opening of the slit, and the side wall and the bottom wall of the first part surround to form a groove having a top opening, the second part is formed on the second electrode layer, and the third part is formed in the opening and wraps the metal pad, a through slot is formed penetrating through the third part and corresponding to the metal pad, and the metal pad is exposed by the through slot.

2. The acoustic transducer according to claim 1 , wherein the first part, the second part and the third part have a same thickness, and the thicknesses of the first part, the second part and the third part are consistent at each position.

3. The acoustic transducer according to claim 1 , wherein the metal pad has a thickness smaller than the piezoelectric layer.

4. The acoustic transducer according to claim 1 , wherein an axis of the groove is coaxial with an axis of the back chamber.

5. The acoustic transducer according to claim 1 , wherein a plane where a bottom of the groove is located intersects with the second silicon layer.

6. A method for manufacturing an acoustic transducer, comprising:
providing a substrate, wherein the substrate includes a first silicon layer, a first oxide layer and a second silicon layer sequentially stacked from bottom to top;
sequentially forming a second oxide layer, a first electrode layer, a piezoelectric layer and a second electrode layer on top of the second silicon layer from bottom to top;
forming a slit by etching in the middle of the second electrode layer and forming an opening by etching at an edge of the second electrode layer, wherein the slit sequentially penetrates through the second electrode layer, the piezoelectric layer, the first electrode layer, the second oxide layer and the second silicon layer, the opening penetrates through the second electrode layer and the piezoelectric layer, and the first electrode layer is exposed by the opening;
forming a metal pad on the first electrode layer at the opening;
forming an additional film layer, wherein a first part of the additional film layer is deposited in the slit, a side wall of the additional film layer covers an inner wall surface of the slit, a bottom wall of the first part covers the first oxide layer, and the side wall and the bottom wall surround to form a groove having a top opening, a second part of the additional film layer is deposited on the second electrode layer, and a third part of the additional film layer is deposited in the opening and wraps the metal pad, a through slot is formed penetrating through the third part and corresponding to the metal pad, and the metal pad is exposed by the through slot; and
forming a back chamber on bottom of the first silicon layer, wherein the back chamber sequentially penetrates through the first silicon layer and the first oxide layer, and the second silicon layer is exposed by the back chamber.

7. The method according to claim 6 , wherein the additional film layer is made of a poly-p-xylylene material.

8. The method according to claim 7 , wherein the additional film layer is formed by a vapor deposition process.

9. The method according to claim 7 , wherein the vapor deposition process comprises a physical vapor deposition process or a chemical vapor deposition process.

10. The method according to claim 6 , wherein the piezoelectric layer is made of one of lead zirconate titanate, aluminum nitride, barium titanate, or any combination thereof.

Assignees

• Aac Technologies Pte Ltd

Inventors

• Goh Kianheng
• Li Chungmin
• Dan qiang
• Lai Kahkeen

Classifications

• H04R31/006

  Interconnection of transducer parts (of diaphragm and outer suspension by moulding H04R31/003) · CPC title

• H04R17/005 Primary

  using a piezoelectric polymer · CPC title

• H04R31/00

  Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor {(manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182)} · CPC title

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• C23C16/409

  of the type ABO3 with A representing alkali, alkaline earth metal or lead and B representing a refractory metal, nickel, scandium or a lanthanide · CPC title