BAW RESONATOR ARRANGEMENT WITH RESONATORS HAVING DIFFERENT RESONANCE FREQUENCIES AND MANUFACTURING METHOD

Abstract

In at least one embodiment, the electric component comprises a first BAW-resonator (1), a second BAW-resonator (2) electrically connected to the first BAW-resonator and a carrier substrate (3) with a top side (30) on which the BAW-resonators are arranged. The first and the second BAW-resonator each comprise a bottom electrode (11,21) and a top electrode (12,22). The bottom electrodes are in each case located between the carrier substrate and the respective top electrode. A first piezoelectric layer (13) is arranged between the top electrode and the bottom electrode of the first BAW-resonator and laterally protrudes from the first BAW-resonator. The second BAW-resonator is mounted on the first piezoelectric layer in a region laterally next to the first BAW-resonator and comprises a second piezoelectric layer (23) between its top electrode and its bottom electrode. The two piezoelectric layers may have different thickness to realize resonators with different resonance frequencies on the same die.

Claims

1. An electric component comprising: a first BAW-resonator; a second BAW-resonator electrically connected to the first BAW-resonator; and a carrier substrate with a top side on which the BAW-resonators are arranged, wherein: the first and the second BAW-resonator each comprise a bottom electrode and a top electrode, the bottom electrodes are in each case located between the carrier substrate and the respective top electrode, a first piezoelectric layer is arranged between the top electrode and the bottom electrode of the first BAW-resonator and laterally extends from the first BAW-resonator, and the second BAW-resonator is mounted on the first piezoelectric layer in a region laterally next to the first BAW-resonator and comprises a second piezoelectric layer between the top electrode of the second BAW-resonator and the bottom electrode of the second BAW-resonator.

2. The electric component according to claim 1, wherein the first piezoelectric layer and the second piezoelectric layer have different thicknesses.

3. The electric component according to claim 1, wherein a dummy electrode is located between the second BAW-resonator and the carrier substrate.

4. The electric component according to claim 3, wherein the bottom electrode of the first BAW-resonator and the dummy electrode lie laterally next to each other in a common plane.

5. The electric component according to claim 3, wherein the dummy electrode is not electrically connected to another element for the operation of the electric component.

6. The electric component according to claim 3, wherein the dummy electrode is completely enclosed by the first piezoelectric layer and the carrier substrate.

7. The electric component according to claim 1, wherein in a region between the bottom electrode of the second BAW-resonator and the carrier substrate, the first piezoelectric layer is in direct contact to the carrier substrate.

8. The electric component according to claim 1, wherein the top electrode of the first BAW-resonator and the bottom electrode of the second BAW-resonator lie next to each other in a common plane.

9. The electric component according to claim 1, wherein: the electric component is or comprises an RF-filter, and the first BAW-resonator is a serial resonator and the second BAW-resonator is a shunt resonator or vice versa.

10. The electric component according to claim 1, wherein the carrier substrate comprises layers of different acoustic impedances stacked above each other along a direction perpendicular to the top side.

11. The electric component according to claim 1, wherein the first and the second BAW-resonator have different resonant frequencies.

12. The electric component according to claim 1, wherein the electric component is a chip.

13. The electric component according to claim 1, wherein the first piezoelectric layer laterally extends beyond the top electrode and the bottom electrode of the first BAW-resonator.

14. A method for manufacturing an electric component, comprising: providing a carrier substrate; depositing a first electrode layer on a top side of the carrier substrate; thereafter depositing a first piezoelectric layer on the first electrode layer; thereafter depositing a second electrode layer on the first piezoelectric layer; thereafter depositing a second piezoelectric layer on the second electrode layer; thereafter depositing a third electrode layer on the second piezoelectric layer; and thereafter removing the second piezoelectric layer in a region of a first BAW-resonator and keeping at least a portion of the third electrode layer and of the second piezoelectric layer in a region of a second BAW-resonator.

15. The method according to claim 14, wherein a bottom electrode of the first BAW-resonator is formed out of the first electrode layer.

16. The method according to claim 14, wherein a dummy electrode is formed out of the first electrode layer in the region of the second BAW-resonator.

17. The method according to claim 14, wherein a top electrode of the first BAW-resonator and a bottom electrode of the second BAW-resonator are formed out of the second electrode layer.

18. The method according to claim 14, wherein a top electrode of the second BAW-resonator is formed out of the third electrode layer.

19. The method according to claim 14, wherein the electrode layers and/or the piezoelectric layers are deposited by sputtering or vapor deposition.

Description

[0062] In the Figures:

[0063] FIGS. 1 and 11 show exemplary embodiments of the electric component in cross-sectional views,

[0064] FIGS. 2 to 10 show different positions in an exemplary embodiment of the method for manufacturing an electric component.

[0065] FIG. 1 shows a first exemplary embodiment of an electric component in a cross-sectional view. The electric component comprises a carrier substrate 3 with a base substrate 33. The base substrate 33 is, for example, formed of crystalline Si. On top of the base substrate 33, layers 31, 32 of different acoustic impedances are stacked one above the other. The layer stack comprises layers of higher acoustic impedance 31 and layers of lower acoustic impedance 32 stacked above each other in an alternating manner. The layers 31 are, for example, made of W, the layers 32 are, for example, made of SiO.sub.2. The layer stack terminates with a layer 32 forming a top side 30 of the carrier substrate 3.

[0066] On the top side 30 of the carrier substrate 3, two BAW-resonators 1, 2 are arranged laterally next to each other. The first BAW-resonator 1 comprises a bottom electrode 11 and a top electrode 12, wherein the bottom electrode 11 is arranged between the top electrode 12 and the carrier substrate 3. Between the top electrode 12 and the bottom electrode 11, a first piezoelectric layer 13 is arranged. The first piezoelectric layer 13 is, for example, made of AlN. The electrodes 11, 12, for example, comprises Al. The region between the electrodes 11, 12 is filled with the first piezoelectric layer 13 and forms an active region of the first BAW-resonator 1, in which bulk acoustic waves are created and propagate during operation.

[0067] The first piezoelectric layer 13 does not only fill the region between the electrodes 11, 12 but laterally extends out of this region so that it laterally protrudes from the first BAW-resonator 1. The second BAW-resonator 2 is mounted on a laterally protruding portion of the first piezoelectric layer 13. The second BAW-resonator 2 comprises a top electrode 22 and a bottom electrode 21 as well as a second piezoelectric layer 23 located between the electrodes 21, 22. Also here, the region between the electrodes 21, 22 filled with the second piezoelectric layer 23 forms an active region of the second BAW-resonator 2 for the creation and propagation of bulk acoustic waves. The second piezoelectric layer 23 may again be AlN, the electrodes 21, 22 may again comprise Al.

[0068] In FIG. 1, the thickness of the second piezoelectric layer 23 is larger than the thickness of the first piezoelectric layer 13. Particularly, the two BAW-resonators 1, 2 have different resonant frequencies. In an aspect, the thickness of the first piezoelectric layer 13 is constant over its entire lateral expansion. However, in other embodiments the thickness may be similar.

[0069] Between the first piezoelectric layer 13 and the carrier substrate 3, a dummy electrode 24 is located in the region of the second BAW-resonator 2. The dummy electrode 24 is not intended for an electrical connection during the operation of the electric component (floating electrode). For example, the dummy electrode 24 is completely enclosed by the first piezoelectric layer 13 and the carrier substrate 3, and there is no possibility for an external electrical connection of the dummy electrode 24. The dummy electrode 24 may be substantially identical to the bottom electrode 11 in terms of its thickness and material composition.

[0070] The layer stacks of layers 31, 32 of different acoustic impedances arranged below the first and second BAW-resonators 1, 2 in each case form a Bragg mirror for the acoustic waves produced in the BAW-resonators 1, 2. The first piezoelectric layer 13 and the dummy electrode 24 extending in the region below the second BAW-resonator 2 additionally contribute to the Bragg mirror for the second BAW-resonator 2. Particularly, the dummy electrode 24 and the first piezoelectric material 13 have different acoustic impedances.

[0071] FIG. 2 shows a first position in a method for manufacturing an electric component. In this position, a carrier substrate 3 is provided, which is identical to the carrier substrate 3 of FIG. 1. The top side 30 of the carrier substrate 3 is exposed.

[0072] FIG. 3 shows a second position in the method, in which a first electrode layer 101 is deposited directly on the top side 30. The first electrode layer 101 may be applied by sputtering or evaporation.

[0073] FIG. 4 shows a third position in the method, in which the first electrode layer 101 is structured into a bottom electrode 11 of a first BAW-resonator and a dummy electrode 24 of a second BAW-resonator. Structuring can, for example, be done with the help of a photolithographic mask and an etching process. The electrodes 11, 24 are separated and electrically isolated from each other. The electrodes 11, 24 lie in and extend along a common plane.

[0074] FIG. 5 shows a fourth position in the method, in which a first piezoelectric layer 13 is deposited on the first electrode layer 101 or on the electrodes 11, 24, respectively. The first piezoelectric layer 13 may be applied by sputtering or evaporation. The first piezoelectric layer 13 is deposited as a contiguous layer completely covering the electrodes 11, 24. A thickness of the first piezoelectric layer 13 is constant along its lateral expansion.

[0075] FIG. 6 shows a fifth position in the method, in which a second metal layer 102 is deposited on the first piezoelectric layer 13. Again, the second metal layer 102 may be deposited by sputtering or evaporation. For example, the second metal layer 102 is deposited such that, in a plan view, it completely covers the electrodes 11, 24.

[0076] FIG. 7 shows a sixth position in the method, in which the second metal layer 102 is structured into a top electrode 12 of the first BAW-resonator and a bottom electrode 21 of the second BAW-resonator. Structuring is, for example, done with the help of a mask and an etching process. The electrodes 12, 21 may be separated and electrically isolated from each other. In a plan view onto the top side 30 of the carrier substrate 3, the electrode 12 overlaps with electrode 11 and the electrode 21 overlaps with the dummy electrode 24. The electrodes 12 and 21 lie in and extend along a common plane.

[0077] FIG. 8 shows a seventh position in the method, in which a second piezoelectric layer 23 is deposited on the second metal layer 102 or on the electrodes 12, 21, respectively. The second piezoelectric layer 23 is deposited as a contiguous layer completely covering the electrodes 12, 21. The second piezoelectric layer 23 is deposited with a constant thickness over its entire lateral expansion. The second piezoelectric layer 23 is, for example, applied by sputtering or evaporation.

[0078] FIG. 9 shows an eighth position of the method, in which a third metallic layer 103 is deposited on the second piezoelectric layer 23. Again, the third metallic layer 103 may be deposited by sputtering or evaporation.

[0079] FIG. 10 shows a ninth position in the method, in which the third metal layer 103 is structured so that a top electrode 22 of the second BAW-resonator 2 is formed. Structuring is, for example, done by etching with the help of a mask. In the region of the first BAW-resonator 1, the third metal layer 103 is removed. Additionally, the second piezoelectric layer 23 is removed in the region of the first BAW-resonator 1. Also the second piezoelectric layer 23 may be removed by etching using a mask. After removing the second piezoelectric layer 23, the top electrode 12 of the first BAW-resonator 1 is exposed. FIG. 10 at the same time shows a finalized electric component. Particularly, the finalized electric component of FIG. 10 is identical to the electric component of FIG. 1.

[0080] FIG. 11 shows a further exemplary embodiment of the electric component in a cross-sectional view. The design is almost identical to that of the electric component of FIG. 1. The only difference is that no dummy electrode is present in the region below the second BAW-resonator 2. Such an electric component can be manufactured using the method described before. In the step of structuring the first metal layer 101, the first metal layer 101 is completely removed in the region of the second BAW-resonator.

[0081] The invention described herein is not limited by the description in conjunction with the exemplary embodiments. Rather, the invention comprises any new feature as well as any combination of features, particularly including any combination of features in the patent claims, even if said feature or said combination per se is not explicitly stated in the patent claims or exemplary embodiments.

REFERENCE SIGN LIST

[0082] 1 first BAW-resonator [0083] 2 second BAW-resonator [0084] 3 carrier substrate [0085] 11 bottom electrode of the first BAW-resonator [0086] 12 top electrode of the first BAW-resonator [0087] 13 first piezoelectric layer [0088] 21 bottom electrode of the second BAW-resonator [0089] 22 top electrode of the second BAW-resonator [0090] 23 second piezoelectric layer [0091] 24 dummy electrode [0092] 30 top side of the carrier substrate [0093] 31 layer [0094] 32 layer [0095] 33 base substrate [0096] 101 first electrode layer [0097] 102 second electrode layer [0098] 103 third electrode layer