BAW component, lamination for a BAW component, and method for manufacturing a BAW component

Abstract

A BAW component, a lamination for a BAW component, and a method for manufacturing a BAW component are provided. A lamination for a BAW component includes a first layer with a first piezoelectric material and a second layer with a second piezoelectric material that is different than the first piezoelectric material. The first and the second piezoelectric material can be Sc doped AlN and AlN, respectively.

Claims

1. A BAW component, comprising: a first bulk acoustic wave (BAW) resonator having a first bottom electrode, a first top electrode and a lamination between the first bottom electrode and the first top electrode, wherein: the lamination comprises a first layer with a first piezoelectric material comprising Sc doped AlN and a second layer with a second piezoelectric material that is different from the first piezoelectric material and arranged over the first layer; a carrier chip; and a second BAW resonator consisting of a second bottom electrode, a second top electrode, and a piezoelectric layer between the second bottom electrode and the second top electrode, wherein: the first BAW resonator and the second BAW resonator are arranged on the carrier chip; and the piezoelectric layer is a layer of the first piezoelectric material, substantially free of the second piezoelectric material.

2. The BAW component of claim 1, wherein the lamination of the first BAW resonator has first thickness, and the piezoelectric layer of the second BAW resonator has a second thickness different from the first thickness.

3. The BAW component of claim 1, wherein the first piezoelectric material and the second piezoelectric material have a different etching selectivity with respect to an etching agent.

4. The BAW component of claim 3, wherein the etching agent is a wet etching agent.

5. The BAW component of claim 4, wherein the etching agent comprises 2.36% Tetramethyl ammonium hydroxyl in combination with a wetting agent.

6. The BAW component of claim 3, wherein the etching agent is a dry etching agent.

7. The BAW component of claim 1, wherein the second piezoelectric material is AlN.

8. The BAW component of claim 1, wherein the BAW component is a duplexer and the first BAW resonator is a resonator of a TX filter of the duplexer.

9. A method for manufacturing a BAW component, the method comprising: providing a carrier chip; providing a first bottom electrode on the carrier chip; providing a second bottom electrode on the carrier chip; arranging a first layer of a first piezoelectric material comprising Sc doped AlN over the first bottom electrode; arranging a second layer of the first piezoelectric material over the second bottom electrode; arranging a first layer of a second piezoelectric material, different from the first piezoelectric material, over the first layer of the first piezoelectric material; arranging a second layer of the second piezoelectric material over the second layer of the first piezoelectric material; selectively removing the second layer of the second piezoelectric material; arranging, after the selectively removing the second layer of the second piezoelectric material, a first top electrode over the second layer of the first piezoelectric material; and arranging a second top electrode over the first layer of the second piezoelectric material.

10. The method of claim 9, wherein the first piezoelectric material and the second piezoelectric material have a different etching selectivity with respect to an etching agent used during the selectively removing step.

11. The method of claim 10, wherein the etching agent is a wet etching agent.

12. The method of claim 11, wherein the etching agent comprises 2.36% Tetramethyl ammonium hydroxyl in combination with a wetting agent.

13. The method of claim 10, wherein the etching agent is a dry etching agent.

14. The method of claim 9, wherein the second piezoelectric material is AlN.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples of BAW components, laminations and methods for manufacturing and the respective working principles are shown in the schematic figures.

(2) FIG. 1 shows a basic BAW resonator stack with a lamination L;

(3) FIG. 2 shows a BAW component with two BAW resonator stacks;

(4) FIG. 3 shows elements of a BAW component comprising acoustic mirrors;

(5) FIG. 4 shows a stage of a manufacturing process;

(6) FIG. 5 shows a stage of a manufacturing process;

(7) FIG. 6 shows a stage of a manufacturing process;

(8) FIG. 7 shows a final stage of a manufacturing process; and

(9) FIG. 8 shows a component with piezoelectric switches with different closing voltages.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(10) FIG. 1 shows a BAW component BAWC comprising a lamination L between a bottom electrode BE and a top electrode TE. The lamination comprises a first layer with a first piezoelectric material PM1 and a second layer with a second piezoelectric material PM2. The second piezoelectric material PM2 is arranged between the first piezoelectric material PM1 and the top electrode TE. The first piezoelectric material PM1 is different from the second piezoelectric material PM2. This allows high quality BAW components with more than one BAW resonators on a common carrier chip where different resonators have different resonance frequencies.

(11) FIG. 2 shows a BAW component BAWC where a first BAW resonator BAWR1 is arranged next to a second BAW resonator BAWR2. Both resonators can be arranged on or above a carrier substrate CS. Both resonators comprise a bottom electrode BE and a top electrode TE and the first piezoelectric material PM1. Only the first BAW resonator BAWR1 comprises a second piezoelectric material PM2. The piezoelectric material of the first BAW resonator BAWR1 is thicker than the piezoelectric material of the second resonator BAWR2. Thus, both resonators have different resonance frequencies although they can be manufactured with easy to perform manufacturing steps one next to the other on or above a common carrier substrate CS.

(12) FIG. 3 shows main components of a BAW component BAWC where mainly the top electrode is omitted. Two resonator stacks are arranged on respective acoustic mirrors AM. The acoustic mirrors AM comprise a layer system with alternating high and low acoustic impedance. The acoustic mirror AM confines acoustic energy and allows to establish a resonance mode of the respective resonator.

(13) FIG. 4 shows a stage during one of several possible manufacturing processes where two resonator stacks are arranged next to another on a common carrier substrate CS. After depositing and structuring a bottom electrode BE, the first piezoelectric material PM1 is deposited and structured on the bottom electrode BE for both resonator stacks.

(14) It may not be necessary to structure one or more layers.

(15) FIG. 5 shows a further stage of a manufacturing process where a second piezoelectric material PM2 is arranged on the first piezoelectric material. However, the second piezoelectric material PM2 is only needed in one of the resonator stacks and needs to be removed in the respective other resonator stack.

(16) Accordingly, FIG. 6 shows a stage where a resist film RES is arranged on the lamination of the first resonator. The resist film RES protects the lamination of the later first resonator BAWR1 but the piezoelectric material PM2 is removed from the second resonator stack, the later second resonator BAWR2, shown on the left. Different properties of the different piezoelectric materials ensure that an etching agent etches the second piezoelectric material in such a way that the etching process stops when the second piezoelectric material PM2 is completely removed. The upper surface of the first piezoelectric material of the left resonator stack establishes an etch stop zone for the process.

(17) FIG. 7 shows a final manufacturing stage where a top electrode TE has been deposited and structured on both resonator stacks.

(18) FIG. 8 shows a BAW component where a lamination comprising a first piezoelectric material PM1 and a second piezoelectric material PM2 are arranged between a bottom electrode BE and a top electrode TE to establish a cantilever shaped switch SW1. The switch is arranged next to a switch SW2 without the second piezoelectric material PM2. The different constructions of the two switches allow different closing voltages.

(19) Neither the BAW component nor the lamination for a BAW component nor the method for manufacturing a BAW component are limited to the embodiments described in the specification or shown in the figures. Components, laminations and methods comprising further materials or layers or components comprising further resonators or methods comprising further deposition steps or etching steps or combinations thereof are also comprised by the present invention.