BAW component and method for manufacturing a BAW component

Abstract

A BAW component is provided. A method for manufacturing a BAW component is also provided. The component includes a bottom electrode, a top electrode and a first piezoelectric material. The first piezoelectric material is between the bottom electrode and the top electrode. The first piezoelectric material has a higher piezoelectric coefficient than AlN.

Claims

1. A bulk acoustic wave (BAW) component, comprising: a bottom electrode; a top electrode; a first piezoelectric layer between the bottom electrode and the top electrode, wherein the first piezoelectric layer comprises a first piezoelectric material having a higher piezoelectric coefficient than aluminum nitride (AlN); and a second piezoelectric layer between the bottom electrode and the first piezoelectric layer, wherein the second piezoelectric layer comprises a second piezoelectric material that is a different material than the first piezoelectric material.

2. The BAW component of claim 1, wherein the piezoelectric material comprises scandium (Sc) doped AIN.

3. The BAW component of claim 1, wherein a lattice parameter mismatch of the first piezoelectric layer's material and the second piezoelectric layer's material is less than 10%.

4. The BAW component of claim 1, wherein the second piezoelectric layer has a (002) texturation at an interface towards the first piezoelectric layer.

5. The BAW component of claim 1, further comprising a third piezoelectric layer between the first piezoelectric layer and the top electrode.

6. The BAW component of claim 5, wherein the third piezoelectric layer comprises a third piezoelectric material that is a different material than the first piezoelectric material.

7. The BAW component of claim 1, wherein the second piezoelectric layer comprises AIN.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples and working principles are shown in the schematic figures.

(2) FIG. 1 shows a BAW component with a piezoelectric layer between two electrodes;

(3) FIG. 2 shows the relationship between an electrical field an a mechanical distortion of a piezoelectric material;

(4) FIG. 3 shows a BAW component comprising three piezoelectric layers between two electrodes;

(5) FIG. 4 shows a BAW component with a second piezoelectric layer between the first piezoelectric layer and a bottom electrode;

(6) FIG. 5 shows a BAW component with a third piezoelectric layer between the first piezoelectric layer and an top electrode; and

(7) FIG. 6 shows a BAW resonator with an acoustic mirror.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(8) FIG. 1 shows a BAW component BAWC comprising a bottom electrode BE and a top electrode TE. Between the two electrodes, a first piezoelectric layer PL1 is arranged. The first piezoelectric layer PL1 comprises a piezoelectric material having a higher piezoelectric coefficient c than AlN.

(9) FIG. 2 shows two versions of a piezoelectric material being arranged between two electrodes. An electric voltage is applied to the electrodes resulting in an electric field causing the piezoelectric material to expand in a vertical direction which may be a direction parallel to the piezoelectric axis. In contrast, a reverse voltage, i.e., the same voltage with different sign, is applied to the piezoelectric material as shown in the piezoelectric material on the right-hand side. The electrical field causes the piezoelectric material to shrink in a vertical direction.

(10) FIG. 3 shows a BAW component comprising a second piezoelectric layer PL2 between the first piezoelectric layer PL1 and the bottom electrode. Further, a third piezoelectric layer PL3 is arranged between the first piezoelectric layer PL1 and the top electrode TE. The materials of the piezoelectric layer and the respective layer thicknesses can be chosen to provide an excellent BAW component as the materials and the thicknesses can be chosen to fulfill elastic and electric requirements.

(11) FIG. 4 shows an embodiment of a BAW component where the third piezoelectric layer PL3 shown in FIG. 3 is omitted.

(12) FIG. 5 shows the BAW component where the second piezoelectric layer PL2 of FIG. 3 is omitted.

(13) FIG. 6 shows a BAW component BAWC where an acoustic mirror AM is arranged between the layer stack with the electrodes and the piezoelectric material on one side and a carrier substrate CS on the other side. The acoustic mirror AM is a possibility to confine acoustic energy in the stack so that a resonance can be established. The acoustic mirror AM can comprise two or more layers with alternating acoustic impedance.

(14) A BAW component or a method for manufacturing BAW components are not limited to the embodiments described in the specification or shown in the figures. Components comprising further elements such as layers or materials or methods comprising further deposition steps or structuring steps or combinations thereof are also comprised by the present invention.