BAW Resonator Arrangement and Manufacturing Method

Abstract

In at least one embodiment, an electrical component comprises: a first BAW resonator (1); a second BAW resonator (2) electrically connected to the first BAW resonator; and a carrier substrate (3) having a top side (30) on which the BAW resonators are arranged. The first and second BAW resonators each include a bottom electrode (11, 21) and a top electrode (12, 22). The bottom electrode is 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 protrudes laterally from the first BAW resonator. The second BAW resonator is mounted on the first piezoelectric layer in a region laterally adjacent to the first BAW resonator and includes a second piezoelectric layer (23) between its top electrode and its bottom electrode. The two piezoelectric layers may have different thicknesses to implement resonators with different resonance frequencies on the same die.

Description

Field of the Invention

[0001] Electrical components and a method for manufacturing electrical components. The present invention specifies an electrical component. In addition, the present invention specifies a method for manufacturing an electrical component. Summary of the Invention

[0002] One aspect of the present invention relates to the task of providing an electrical component with high efficiency. Another task to be solved is to provide a method for easily and inexpensively manufacturing such an electrical component.

[0003] According to at least one embodiment, the electrical component includes a first BAW resonator and a second BAW resonator (BAW = bulk acoustic wave). The second BAW resonator is electrically connected to the first BAW resonator. The electrically connected BAW resonators are resonators in which one electrode of one resonator and one electrode of the other resonator are electrically connected to each other. The first BAW resonator and the second BAW resonator can be connected in parallel or in anti-parallel.

[0004] "Connected in parallel" means that the bottom electrodes of the two BAW resonators are electrically connected to each other and are at the same electrical potential during operation. In addition, the top electrodes of the two BAW resonators are electrically connected to each other and are at the same electrical potential during operation.

[0005] "Connected in anti-parallel" means that the bottom electrode of one BAW resonator is electrically connected to the top electrode of the other BAW resonator such that these two electrodes are at the same electrical potential during operation. In addition, the top electrode of one BAW resonator is electrically connected to the bottom electrode of the other BAW resonator such that these two electrodes are at the same electrical potential during operation.

[0006] According to at least one embodiment, the electrical component includes a carrier substrate having a top side on which the BAW resonators are arranged. The carrier substrate mechanically supports the BAW resonators. The carrier substrate is mechanically self-supporting. The lateral surface of the carrier substrate extending transversely to the top side may include traces of chemical or physical material removal, such as sawing grooves.

[0007] According to at least one embodiment, each of the first BAW resonator and the second BAW resonator includes a bottom electrode and a top electrode. The top electrode and the bottom electrode are intended to have an alternating voltage applied therebetween, such as having an RF frequency. The top electrode and the bottom electrode are electrically connected to another electrical component of the electrical component, such as being electrically connected to another resonator or a terminal.

[0008] During operation of the electrical component, an alternating voltage having an RF frequency, for example, is applied between a top electrode and a bottom electrode of a respective BAW resonator. Thereby, an alternating electric field is generated between the top electrode and the bottom electrode. A piezoelectric material is arranged between the top electrode and the bottom electrode and is mechanically deformed due to this alternating electric field. Thereby, a bulk acoustic wave is generated and propagates in the piezoelectric material. The region between the top electrode and the bottom electrode filled with the piezoelectric material is the active region of the BAW resonator.

[0009] The electrodes comprise a conductive material. The electrodes may comprise a metal. For example, each of the electrodes may comprise one or more of the following: Al, Cu, Ti, Cr, Au, Pt, Ru, or Mo. For illustrative purposes, each of the electrodes may each have an average thickness between 50 nm and 300 nm (inclusive of the endpoints) measured perpendicular to the top side of the carrier substrate.

[0010] Here and hereinafter, the terms “top” and “bottom” and “top side” and “bottom side” or similar terms must in no way be understood as being limited to directions anti-parallel and parallel to the direction of gravity. Instead, they are generally used, for example, to identify relative regions or objects or directions.

[0011] According to at least one embodiment, the bottom electrode is in each case located between the carrier substrate and its respective top electrode. In a plan view, on the top side of the carrier substrate, the top electrode and the bottom electrode of each BAW resonator overlap each other.

[0012] According to at least one embodiment, a first piezoelectric layer is arranged between the top electrode and the bottom electrode of the first BAW resonator. The first piezoelectric layer extends or protrudes laterally from the first BAW resonator.

[0013] The first piezoelectric layer may be formed in one piece, i.e., integrally formed. For example, the top electrode and the bottom electrode of the first BAW resonator are in direct mechanical contact with the first piezoelectric layer. In particular, the first piezoelectric layer completely fills the gap between the top electrode and the bottom electrode of the first BAW resonator.

[0014] For example, the first piezoelectric layer comprises one or more of the following: AlN or ZnO or AlScN. As an example, the average thickness of the first piezoelectric layer (measured as its expansion between the top electrode and the bottom electrode of the first BAW resonator) is at most 5 μm or at most 1 μm or at most 100 nm.

[0015] Additionally or optionally, the average thickness of the first piezoelectric layer is at least 5 nm or at least 50 nm or at least 75 nm.

[0016] The first piezoelectric layer extends or protrudes laterally from the first BAW resonator. This means that the first piezoelectric layer not only fills the gap between the top electrode and the bottom electrode of the first BAW resonator, but also extends laterally beyond this gap. In other words, the first piezoelectric layer extends laterally beyond the top electrode and / or the bottom electrode of the first BAW resonator. Here and below, "laterally" means along the lateral direction, where the lateral direction is the direction parallel to the top side of the carrier substrate. For example, the first piezoelectric layer protrudes laterally from the first BAW resonator and / or from the top electrode and / or from the bottom electrode by at least 10 μm or at least 50 μm or at least 100 μm. Thus, in a plan view, on the top side of the carrier substrate, a part of the first piezoelectric layer is arranged adjacent to the top electrode and the bottom electrode of the first BAW resonator and does not overlap with the top electrode and the bottom electrode. The first piezoelectric layer can be formed continuously. In a plan view, on the top side of the carrier substrate, the first piezoelectric layer can cover the top side by at least 75% or at least 90% or completely.

[0017] The part of the first piezoelectric layer that fills the gap between the top electrode and the bottom electrode can be regarded as part of the first BAW resonator.

[0018] The bottom electrode of the first BAW resonator can be placed directly on the top side of the carrier substrate. Thus, in the region of the first BAW resonator, the first piezoelectric layer is spaced apart from the top side of the carrier substrate by the bottom electrode. The part of the first piezoelectric layer that protrudes laterally from the first BAW resonator can be located directly on the top side of the carrier substrate.

[0019] According to at least one embodiment, a second BAW resonator is mounted on the first piezoelectric layer in a region that is laterally adjacent to the first BAW resonator. The second BAW resonator includes a second piezoelectric layer between a top electrode of the second BAW resonator and a bottom electrode of the second BAW resonator.

[0020] In other words, in a plan view, on the top side of the carrier substrate, the second BAW resonator is positioned adjacent to the first BAW resonator. The part of the first piezoelectric layer that protrudes laterally from the first BAW resonator is arranged between the second BAW resonator and the carrier substrate. The bottom electrode of the second BAW resonator can be placed directly on the first piezoelectric layer, and the first piezoelectric layer is arranged between the bottom electrode of the second BAW resonator and the carrier substrate.

[0021] For example, the average thickness of the first piezoelectric layer is the same in the region of the first BAW resonator and in the region between the carrier substrate and the second BAW resonator.

[0022] The portion of the first piezoelectric layer between the second BAW resonator and the carrier substrate is not intended to form the active region of the resonator. Thus, during the intended operation of the electrical component, this portion does not form the active region of the BAW resonator. The active region of the resonator is the region where acoustic waves are intentionally generated and propagate. Thus, during the intended operation of the electrical component, acoustic waves are not intentionally generated in this portion of the first piezoelectric layer.

[0023] The second piezoelectric layer can be formed in one piece. For example, the top electrode and the bottom electrode of the second BAW resonator are in direct mechanical contact with the second piezoelectric layer. For example, the second piezoelectric layer includes one or more of the following: AlN or ZnO or AlScN. As an example, the average thickness of the second piezoelectric layer (measured as its extension between the top electrode and the bottom electrode of the second BAW resonator) is at most 5 μm or at most 1 μm or at most 100 nm. Additionally or optionally, the average thickness of the second piezoelectric layer is at least 5 nm or at least 50 nm or at least 75 nm. In particular, the second piezoelectric layer is not formed continuously with the first piezoelectric layer. For example, in a plan view, on the top side of the carrier substrate, the second piezoelectric layer does not overlap with the first BAW resonator.

[0024] In particular, the second piezoelectric layer does not overlap with the top electrode of the first BAW resonator.

[0025] The top electrode and / or the bottom electrode of the BAW resonator can be laterally spaced apart from each other, for example by at least 10 μm or at least 50 μm or at least 100 μm. In particular, the top electrode of the second BAW resonator is positioned further away from the carrier substrate than the top electrode of the first BAW resonator.

[0026] The electrical component can include a plurality of first BAW resonators and a plurality of second BAW resonators, where each second BAW resonator is electrically connected to a first BAW resonator. The features disclosed herein for one first BAW resonator and one second BAW resonator are also disclosed respectively for all other first BAW resonators and second BAW resonators. In particular, the first piezoelectric layers of all first BAW resonators can be formed by a common, continuous first piezoelectric layer. All second BAW resonators can be mounted on this common first piezoelectric layer.

[0027] In at least one embodiment, an electrical component comprises: a first BAW resonator; a second BAW resonator electrically connected to the first BAW resonator; and a carrier substrate having a top side on which the BAW resonators are disposed. The first and second BAW resonators each include a bottom electrode and a top electrode. The bottom electrode is in each case located between the carrier substrate and the respective top electrode. A first piezoelectric layer is disposed between the top electrode and the bottom electrode of the first BAW resonator and extends laterally from the first BAW resonator. The second BAW resonator is mounted on the first piezoelectric layer in a region laterally adjacent to the first BAW resonator and includes a second piezoelectric layer between the top electrode of the second BAW resonator and the bottom electrode of the second BAW resonator.

[0028] The present invention is in particular based on the recognition that for electrical filters, such as ladder filters, at least two resonators with different resonance frequencies are used. In BAW resonators, the resonance frequency can be changed by adjusting the stack or layer thickness. Generally, a detuning layer or a thinning layer is added to shift the resonance frequency of the respective BAW resonator. In order to achieve the highest possible effective coupling, an optimal ratio of the electrode thickness to the piezoelectric layer thickness must be achieved. Therefore, it is desirable to have different piezoelectric layer thicknesses in different BAW resonators in order to obtain different resonance frequencies.

[0029] Another aspect to be considered is that for optimal coupling and thus for high efficiency of the BAW resonator, the growth conditions of the piezoelectric layer and the electrode should be optimal. Removing the piezoelectric material in the region of the resonator is harmful because etching deteriorates the growth conditions in this region. In fact, removing the grown piezoelectric material affects the quality of the interface with the top electrode. Removing the piezoelectric material completely together with the bottom electrode and starting the manufacture of the entire resonator again is very expensive.

[0030] As will be explained below, the electrical component specified herein can be manufactured without deteriorating the growth conditions. Therefore, the BAW resonators of the electrical component have good coupling and thus high efficiency. Since the second BAW resonator includes a second piezoelectric layer (which is different from the first piezoelectric layer of the first BAW resonator), two BAW resonators can be selected to have different resonance frequencies.

[0031] According to at least one embodiment, the first piezoelectric layer and the second piezoelectric layer have different thicknesses. In particular, this relates to the average thickness of the piezoelectric layer in the active region of the resonator. For example, the thickness of the first piezoelectric layer differs from the thickness of the second piezoelectric layer by at least 2% or at least 5% or at least 10%. As described above, different thicknesses of the piezoelectric layer are advantageous because they allow different resonance frequencies for different BAW resonators.

[0032] According to at least one embodiment, an electrical component includes a dummy electrode located between a second BAW resonator and a carrier substrate. The dummy electrode may include one or more of the materials disclosed for the electrodes of the BAW resonator. Additionally, the dummy electrode may have a thickness specified for the electrodes of the BAW resonator. For example, the dummy electrode has the same average thickness and the same material composition as the bottom electrode of the first BAW resonator. Here and below, "the same" means the same within manufacturing tolerances.

[0033] The dummy electrode is located between the second BAW resonator and the carrier substrate. In this region, the dummy electrode may be located between the first piezoelectric layer and the carrier substrate and may be in direct mechanical contact with both.

[0034] In a plan view, on the top side of the carrier substrate, the dummy electrode partially or completely overlaps, for example, the top and / or bottom electrodes of the second BAW resonator. The dummy electrode may be separated from the bottom electrode of the first BAW resonator. In particular, the dummy electrode may be electrically isolated from the electrodes of the first and second BAW resonators.

[0035] According to at least one embodiment, the bottom electrode of the first BAW resonator and the dummy electrode are positioned adjacent to each other laterally in a common plane. In particular, the common plane extends parallel to the top side of the carrier substrate. In each case, the bottom electrode of the first BAW resonator and the dummy electrode extend along the common plane. In other words, the bottom electrode of the first BAW resonator and the dummy electrode have a common main extension plane (within manufacturing tolerances). In a plan view, on the top side of the substrate, the bottom electrode of the first BAW resonator and the dummy electrode are positioned adjacent to each other and do not overlap.

[0036] According to at least one embodiment, the dummy electrode is not electrically connected to another component or is not intended to be electrically connected for the operation of the electrical component. Thus, during the intended operation of the electrical component, the dummy electrode is not electrically connected, for example, not even to ground. The dummy electrode is a so-called floating electrode. For example, the dummy electrode is electrically isolated from all other components of the electrical component, in particular from all other electrodes.

[0037] According to at least one embodiment, the dummy electrode is completely encapsulated by the first piezoelectric layer and the carrier substrate. Thus, no part of the dummy electrode is exposed and freely accessible. In particular, the dummy electrode cannot be electrically contacted from the outside, i.e., there is no exposed and freely accessible electrical connection to the dummy electrode.

[0038] The arrangement of the dummy electrode and the first piezoelectric layer together with the portion between the dummy electrode and the bottom electrode of the second BAW resonator advantageously forms a mirror, in particular a Bragg mirror, for the acoustic waves generated in the second BAW resonator. For the acoustic waves generated in the second BAW resonator, the first piezoelectric layer and the dummy electrode have different acoustic impedances, also known as mechanical impedances.

[0039] According to at least one embodiment, in the region between the bottom electrode of the second BAW resonator and the carrier substrate, the first piezoelectric layer is in direct contact with the carrier substrate. For example, in the region between the bottom electrode of the second BAW resonator and the carrier substrate, the first piezoelectric layer is in direct contact with the carrier substrate everywhere.

[0040] According to at least one embodiment, the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator are positioned adjacent to each other in a common plane. Also, this common plane can extend parallel to the top side of the carrier substrate. The top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator each extend along the common plane. The common plane is the main extension plane of both the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator. In a plan view, on the top side of the carrier substrate, the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator are positioned adjacent to each other and do not overlap each other.

[0041] For example, the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator have the same average thickness and the same material composition.

[0042] According to at least one embodiment, the electrical component is or includes an RF filter, wherein the first BAW resonator and the second BAW resonator are part of the RF filter. For example, the RF filter is a band - pass filter, although other filter types are also possible. The resonance frequencies of the first BAW resonator and the second BAW resonator can each be at least 0.5 GHz or at least 1 GHz or at least 5 GHz or at least 6 GHz or at least 8 GHz.

[0043] The electrical component can be a multiplexer including a plurality of RF filters. For example, the electrical component can be used in a communication device such as a mobile phone.

[0044] According to at least one embodiment, the first BAW resonator is a series resonator and the second BAW resonator is a shunt resonator, and vice versa. A shunt resonator is also known as a parallel resonator. The series resonator can be connected to the input or output terminals of the RF filter. The shunt resonator is, for example, electrically connected to a ground terminal. The RF filter can have a ladder topology.

[0045] According to at least one embodiment, the carrier substrate includes layers having different acoustic impedances stacked on top of each other in a direction perpendicular to the top side. For example, the layer stack is arranged below the BAW resonator. In this case, the BAW resonator can be referred to as an SMR (solidly mounted resonator).

[0046] The layers having different acoustic impedances form a mirror, in particular a Bragg mirror, for the acoustic waves generated and propagated in the BAW resonator. For example, the higher acoustic impedance layer is formed of a metal (e.g., W), and the lower acoustic impedance layer is formed of a dielectric material (e.g., SiO2).

[0047] The higher acoustic impedance layers and the lower acoustic impedance layers can be stacked in an alternating manner. One of the dielectric layers can form the top side of the carrier substrate. The metal layer can be embedded between the dielectric layers and is interrupted, for example, in the region between the BAW resonators to avoid additional coupling between the BAW resonators. One or more metal layers can be uniquely assigned to each of the BAW resonators. This indicates that in a plan view, on the top side of the carrier substrate, the metal layer only overlaps with the assigned BAW resonator.

[0048] The carrier substrate can also include a base substrate on which the layer stack having different acoustic impedances is arranged. The layer stack having different acoustic impedances is arranged between the base substrate and the BAW resonator. The base substrate is, for example, a mechanically stable element of the electrical component. For example, the base substrate is formed of a semiconductor material, such as crystalline silicon or sapphire.

[0049] As an alternative or addition to the layers having different impedances, the carrier can include a recess or cavity in the region below the BAW resonator. In this case, the BAW resonator can be a so-called FBAR (film bulk acoustic resonator).

[0050] According to at least one embodiment, the first BAW resonator and the second BAW resonator have different resonance frequencies. For example, the resonance frequencies of the two BAW resonators differ by at least 5 MHz or at least 10 MHz or at least 30 MHz.

[0051] According to at least one embodiment, the electrical component is a chip. Here and below, a chip is understood to be an element that can be operated independently and can be electrically contacted. Specifically, a chip is formed by separating from a wafer composite. For example, the chip includes a continuous carrier substrate. The lateral surface of the carrier substrate can include traces of material removal resulting from separating the chip from the wafer composite. For example, the lateral expansion of the chip is at most 1% or at most 5% or at most 10% larger than the lateral expansion of the carrier substrate. All the electrical functional regions of the chip can be carried by the carrier substrate.

[0052] Next, the present invention specifies a method for manufacturing an electrical component. In particular, the method is applicable to manufacturing the electrical component as specified herein. Accordingly, all features related to the electrical component are also disclosed for the present method, and vice versa.

[0053] In at least one embodiment of the method, a carrier substrate is provided in step a). In step B), a first electrode layer is deposited on the top side of the carrier substrate. Thereafter, in step C), a first piezoelectric layer is deposited on the first electrode layer. Thereafter, in step D), a second electrode layer is deposited on the first piezoelectric layer. Thereafter, in step E), a second piezoelectric layer is deposited on the second electrode layer. Thereafter, in step F), a third electrode layer is deposited on the second piezoelectric layer. Thereafter, in step G), the second piezoelectric layer is removed in the region of the first BAW resonator. At least a portion of the third electrode layer and the second piezoelectric layer remains in the region of the second BAW resonator.

[0054] At least some of the different layers, particularly the piezoelectric layers, can be deposited such that they completely cover the previously deposited layers. For example, the layers are first deposited as a continuous layer without interruption. Thereafter, the layers (particularly the metal layers) can be structured. For example, the layers mentioned are deposited directly on top of each other.

[0055] As an example, the second piezoelectric layer in the region of the first BAW resonator can be removed by etching. A mask (such as a photolithography mask) can be used to remove the second piezoelectric layer in the region of the first BAW resonator and to preserve and not erode the second piezoelectric layer in the region of the second BAW resonator. In step F), the third electrode layer can also be deposited in the region of the first BAW resonator. In this case, in step G), the third electrode layer (before or together with the second piezoelectric layer) can be removed in the region of the first BAW resonator. The first piezoelectric layer is not removed in the region of the first BAW resonator.

[0056] The features disclosed in connection with the electrodes of the BAW resonator (particularly those related to the material and thickness) are also disclosed for the electrode layers.

[0057] According to at least one embodiment, the bottom electrode of the first BAW resonator is formed by the first electrode layer. For example, an etching process is applied after step B) and before step C) to form the bottom electrode of the first BAW resonator from the first electrode layer. Optionally, a lift-off process is applied between steps B) and C) to form the bottom electrode of the first BAW resonator. In the step of forming the bottom electrode of the first BAW resonator, the first electrode layer can be removed in all remaining regions of the top side of the carrier substrate that are not intended for the first BAW resonator, such that only the bottom electrode of the first BAW resonator remains.

[0058] According to at least one embodiment, in the region of the second BAW resonator, the dummy electrode is formed by the first electrode layer. The dummy electrode can be formed in a common step together with the bottom electrode of the first BAW resonator. The same process disclosed for forming the bottom electrode can be used to form the dummy electrode. By forming the bottom electrode and the dummy electrode of the first BAW resonator, the first metal layer is interrupted in the region between these two electrodes.

[0059] According to at least one embodiment, the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator are formed by the second electrode layer. These electrodes can again be formed by etching or stripping. In the region between these electrodes, the second electrode layer is interrupted. Forming the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator can be completed in one step. For example, this step is performed after step D) and before step E).

[0060] According to at least one embodiment, the top electrode of the second BAW resonator is formed by the third electrode layer. Again, this can be done by etching or stripping. Forming the top electrode of the second BAW resonator can be performed after step F) and before or simultaneously with step G).

[0061] According to at least one embodiment, the electrode layer and / or the piezoelectric layer are deposited by sputtering or chemical vapor deposition. Different deposition methods may be used for different layers. The piezoelectric layer can be deposited by sputtering.

[0062] Considering the quality of the resulting BAW resonators, the method is advantageous. In particular, each of the BAW resonators does not grow / form in the region where the etching process has been applied previously. Thus, the growth conditions are very good for both BAW resonators, which is advantageous in terms of the efficiency of the resulting BAW resonators. Description of the Drawings

[0063] Further preferred embodiments and developments of the electrical component and the method for manufacturing the electrical component are described below with reference to the drawings. In the drawings, equal or similar elements and elements having equal functions are denoted by the same reference signs. The scale of the drawings and the elements shown in the figures should not be regarded as true scale. Instead, for better representation and / or better understanding, individual elements (especially layers) can be exaggerated in magnitude.

[0064] In the drawings:

[0065] Figure 1 and Figure 11 An exemplary embodiment of the electrical component is shown in cross-section,

[0066] Figures 2 to 10 showing different positions in an exemplary embodiment of the method for manufacturing the electrical component. Detailed implementation mode

[0067] Figure 1 A first exemplary embodiment of an electrical component is shown in a cross-sectional view. The electrical component includes a carrier substrate 3 having a base substrate 33. The base substrate 33 is formed of crystalline Si, for example. On top of the base substrate 33, layers 31, 32 having different acoustic impedances are stacked on top of each other. The layer stack includes a higher acoustic impedance layer 31 and a lower acoustic impedance layer 32 stacked on top of each other in an alternating manner. Layer 31 is made of W, for example, and layer 32 is made of SiO2, for example. The layer stack terminates at layer 32 that forms the top side 30 of the carrier substrate 3.

[0068] On the top side 30 of the carrier substrate 3, two BAW resonators 1, 2 are arranged adjacent to each other laterally. The first BAW resonator 1 includes a bottom electrode 11 and a top electrode 12, where the electrode 11 is arranged between the top electrode 12 and the carrier substrate 3. A first piezoelectric layer 13 is arranged between the top electrode 12 and the bottom electrode 11. The first piezoelectric layer 13 is made of AlN, for example. The electrodes 11, 12 include Al, for example. The region between the electrodes 11, 12 is filled with the first piezoelectric layer 13 and forms the active region of the first BAW resonator 1, where body acoustic waves are generated and propagated during operation.

[0069] The first piezoelectric layer 13 not only fills the region between the electrodes 11, 12, but also extends laterally out of this region, such that it protrudes laterally from the first BAW resonator 1. The second BAW resonator 2 is mounted on the laterally protruding portion of the first piezoelectric layer 13. The second BAW resonator 2 includes a top electrode 22 and a bottom electrode 21 and a second piezoelectric layer 23 located between the electrodes 21, 22. Again here, the region between the electrodes 21, 22 filled with the second piezoelectric layer 23 forms the active region of the second BAW resonator 2 for generating and propagating body acoustic waves. The second piezoelectric layer 23 can also be AlN, and the electrodes 21, 22 can also include Al.

[0070] In Figure 1 the thickness of the second piezoelectric layer 23 is greater than the thickness of the first piezoelectric layer 13. In particular, the two BAW resonators 1, 2 have different resonance frequencies. In one aspect, the thickness of the first piezoelectric layer 13 is constant over its entire lateral extent. However, in other embodiments, the thickness can be approximate.

[0071] 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 electrical connection during the operation of the electrical component (floating electrode). For example, the dummy electrode 24 is completely encapsulated by the first piezoelectric layer 13 and the carrier substrate 3, and there is no possibility of an external electrical connection of the dummy electrode 24. In terms of its thickness and material composition, the dummy electrode 24 can be substantially the same as the bottom electrode 11.

[0072] Laminates of layers 31, 32 with different acoustic impedances disposed below the first BAW resonator 1 and the second BAW resonator 2 respectively form Bragg mirrors for the acoustic waves generated in the BAW resonators 1, 2. A first piezoelectric layer 13 and a dummy electrode 24 extending in the region below the second BAW resonator 2 additionally contribute to the Bragg mirror of the second BAW resonator 2.

[0073] In particular, the dummy electrode 24 and the first piezoelectric material 13 have different acoustic impedances.

[0074] Figure 2 A first position in a method for manufacturing an electrical component is shown. At this position, a carrier substrate 3 is provided, which is the same as the Figure 1 carrier substrate 3. The top side 30 of the carrier substrate 3 is exposed.

[0075] Figure 3 A second position in the method is shown, where a first electrode layer 101 is directly deposited on the top side 30. The first electrode layer 101 can be applied by sputtering or evaporation.

[0076] Figure 4 A third position in the method is shown, where the first electrode layer 101 is structured into the bottom electrode 11 of the first BAW resonator and the dummy electrode 24 of the second BAW resonator. For example, the structuring can be accomplished by means of a photolithography mask and an etching process. The electrodes 11, 24 are separated from each other and electrically isolated. The electrodes 11, 24 are located in a common plane and extend along the common plane.

[0077] Figure 5 A fourth position in the method is shown, where 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 can be applied by sputtering or evaporation. The first piezoelectric layer 13 is deposited as a continuous layer that completely covers the electrodes 11, 24.

[0078] The thickness of the first piezoelectric layer 13 is constant along its lateral extent.

[0079] Figure 6 A fifth position in the method is shown, where a second metal layer 102 is deposited on the first piezoelectric layer 13. Again, the second metal layer 102 can be deposited by sputtering or vapor deposition. For example, the second metal layer 102 is deposited such that in a plan view, it completely covers the electrodes 11, 24.

[0080] Figure 7Shows the sixth position in the method, where the second metal layer 102 is structured as the top electrode 12 of the first BAW resonator and the bottom electrode 21 of the second BAW resonator. For example, the structuring is accomplished by means of a masking and etching process. Electrodes 12, 21 may be separated from each other and electrically isolated. In a plan view of the top side 30 of the carrier substrate 3, electrode 12 overlaps electrode 11 and electrode 21 overlaps dummy electrode 24. Electrodes 12 and 21 are located in a common plane and extend along the common plane.

[0081] Figure 8 Shows the seventh position in the method, where the second piezoelectric layer 23 is deposited on the second metal layer 102 or on electrodes 12, 21 respectively. The second piezoelectric layer 23 is deposited as a continuous layer that completely covers electrodes 12, 21. The second piezoelectric layer 23 is deposited with a constant thickness over its entire lateral extent. The second piezoelectric layer 23 is applied, for example, by sputtering or vapor.

[0082] Figure 9 Shows the eighth position in the method, where the third metal layer 103 is deposited on the second piezoelectric layer 23. Again, the third metal layer 103 can be deposited by sputtering or vapor.

[0083] Figure 10 Shows the ninth position in the method, where the third metal layer 103 is structured such that the top electrode 22 of the second BAW resonator 2 is formed.

[0084] For example, the structuring is accomplished by etching with the aid of a mask. In the region of the first BAW resonator 1, the third metal layer 103 is removed. Additionally, in the region of the first BAW resonator 1, the second piezoelectric layer 23 is removed. Furthermore, the second piezoelectric layer 23 can 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. Figure 10 Simultaneously shows the finally completed electrical component. In particular, Figure 10 the finally completed electrical component is the same as Figure 1 the electrical component of

[0085] Figure 11 Shows another exemplary embodiment of the electrical component in cross-section. The design is almost the same as that of Figure 1 the electrical component of

[0086] The invention described herein is not limited by the description of the exemplary embodiments. On the contrary, the invention includes any new feature and any combination of features, in particular any combination of features included in the patent claims, even if such features or such combination are not explicitly stated in the patent claims or in the exemplary embodiments.

Claims

1. An electrical component, comprising - a first BAW resonator, - a second BAW resonator electrically connected to the first BAW resonator, and - a carrier substrate having a top side on which the BAW resonators are disposed, wherein - the first BAW resonator and the second BAW resonator each include a bottom electrode and a top electrode, - the bottom electrodes are respectively located between the carrier substrate and the corresponding top electrodes, - a first piezoelectric layer is disposed between the top electrode and the bottom electrode of the first BAW resonator and extends laterally from the first BAW resonator, - the second BAW resonator is directly mounted on the first piezoelectric layer in a region laterally adjacent to the first BAW resonator and includes a second piezoelectric layer between the top electrode of the second BAW resonator and the bottom electrode of the second BAW resonator.

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

3. The electrical component according to claim 1 or 2, wherein a dummy electrode is located between the second BAW resonator and the carrier substrate.

4. The electrical component according to claim 3, wherein the bottom electrode of the first BAW resonator and the dummy electrode are laterally adjacent to each other in a common plane.

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

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

7. The electrical component according to claim 1 or 2, 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 with the carrier substrate.

8. The electrical component according to claim 1 or 2, wherein the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator are located adjacent to each other in a common plane.

9. The electrical component according to claim 1 or 2, wherein - the electrical component is an RF filter or includes an RF filter, - the first BAW resonator is a series resonator and the second BAW resonator is a shunt resonator, or the first BAW resonator is a shunt resonator and the second BAW resonator is a series resonator.

10. The electrical component according to claim 1 or 2, wherein the carrier substrate includes layers having different acoustic impedances stacked on top of each other in a direction perpendicular to the top side.

11. The electrical component according to claim 1 or 2, wherein the first BAW resonator and the second BAW resonator have different resonance frequencies.

12. The electrical component according to claim 1 or 2, wherein the electrical component is a chip.

13. The electrical component according to claim 1 or 2, wherein the first piezoelectric layer extends laterally beyond the top electrode and the bottom electrode of the first BAW resonator.

14. A method for manufacturing an electrical component, comprising A) providing a carrier substrate, B) depositing a first electrode layer on the top side of the carrier substrate, C) then depositing a first piezoelectric layer on the first electrode layer, D) then depositing a second electrode layer on the first piezoelectric layer, E) then depositing a second piezoelectric layer on the second electrode layer, F) then depositing a third electrode layer on the second piezoelectric layer, G) then removing the second piezoelectric layer in the region of a first BAW resonator and retaining at least a portion of the third electrode layer and the second piezoelectric layer in the region of a second BAW resonator such that the second BAW resonator is directly mounted on the first piezoelectric layer in a region laterally adjacent to the region of the first BAW resonator.

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

16. The method according to claim 14 or 15, wherein dummy electrodes are formed by the first electrode layer in the region of the second BAW resonator.

17. The method according to claim 14 or 15, wherein the top electrode of the first BAW resonator and the bottom electrode of the second BAW resonator are formed by the second electrode layer.

18. The method according to claim 14 or 15, wherein the top electrode of the second BAW resonator is formed by the third electrode layer.

19. The method according to claim 14 or 15, wherein the electrode layer and / or the piezoelectric layer are deposited by sputtering or chemical vapor deposition.

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