ELECTROACOUSTIC COMPONENT WITH IMPROVED ACOUSTICS

Abstract

An electro-acoustic component with improved acoustics is specified. The component comprises a rectangular chip whose side edges are rotated relative to the piezoelectric axis.

Claims

1. An electro-acoustic component (EAB), comprising a carrier chip (CH) having a piezoelectric material with a piezoelectric axis (PA), AW transducer structures (EAWS) having electrode fingers (EF) which are arranged on the carrier chip (CH), wherein the electrode fingers (EF) are oriented at a right angle with respect to the piezoelectric axis (PA) and the piezoelectric axis (PA) does not intersect at a right angle with any of the substrate edges (SK).

2. The electro-acoustic component according to the previous claim, wherein the carrier chip (CH) has a rectangular cross-section.

3. The electro-acoustic component according to the previous claim, wherein the piezoelectric axis (PA) and a substrate edge (SK) form an angle 2 which is within an interval [80, . . . , 87].

4. The electro-acoustic component according to any of the previous claims, wherein the piezoelectric material is a monocrystal.

5. The electro-acoustic component according to any of the previous claims, wherein the piezoelectric material is LiTaO.sub.3 or LiNbO.sub.3.

6. The electro-acoustic component according to any of the previous claims, wherein the transducer structures (EAWS) have two busbars (BB) which are oriented at a right angle to the electrode fingers (EF).

7. The electro-acoustic component according to any of the previous claims, wherein the transducer structures (EAWS) comprise DMS structures.

8. The electro-acoustic component according to any of the previous claims, wherein the transducer structures (EAWS) comprise ladder-type structures.

9. HF filter with an electro-acoustic component according to any of the previous claims.

10. A wafer (W), comprising a piezoelectric material with a piezoelectric axis (PA), a first marking (PF) which is provided to indicate the orientation of the wafer (W), wherein the marking (PF) comprises an edge section progressing in a straight line, and the piezoelectric axis (PA) intersects the edge section at an angle 3 that deviates from a right angle.

11. The wafer according to the previous claim, wherein the deviation |390| is within an interval [3, . . . , 10].

12. A method for producing a plurality of electro-acoustic components (EAB) according to any of claims 1 to 9, comprising the steps: Provision of a wafer (W) according to the previous claim; Formation of the transducer structures (EAWS) of the components (EAB) on the wafer; Separation of the components (EAB) by separating the wafer (W) into chips (CH) in which the edges (SK) are oriented parallel or at a right angle to the marking (PF) of the wafer (W).

13. A method for producing a plurality of electro-acoustic components according to any of claims 1 to 9, comprising the steps: Provision of a wafer (W); Formation of the transducer structures (EAWS) of the components (EAB) on the wafer; Separation of the components (EAB) by separating the wafer (W) in chips (CH).

14. The method according to the previous claim, wherein the wafer (W) is sawed during separation.

15. The method according to either of the two previous claims, in which the transducer structures (EAB) are rotated by an angle 1 within an interval [3, . . . , 10] relative to the right-angled orientation of the subsequent chip edges (SK).

Description

[0047] The component, correspondingly designed wafer, and method for producing components shall be explained in more detail by means of schematic and non-limiting Figures. The following is shown:

[0048] FIG. 1: the relative orientation between chip and transducer structures;

[0049] FIG. 2: the relative orientation of the piezoelectric axis, of the chip edges, and of the wafer in an embodiment;

[0050] FIG. 3: the relative arrangement of the piezoelectric axis, of the chip edges, and of the marking of the wafer in an alternative embodiment;

[0051] FIG. 4: the arrangement of multiple, subsequent chips on a wafer;

[0052] FIG. 5: the improvement of the insertion loss with electro-acoustic components of the aforementioned type;

[0053] FIG. 1 shows an electro-acoustic component EAB in which electro-acoustic transducer structures EAWS are arranged on a chip CH. The chip comprises a piezoelectric material with a piezoelectric axis PA. The chip CH has a rectangular footprint with four side edges SK. The transducer structures EAWS comprise busbars BB and a plurality of electrode fingers EF and reflector elements REF. The electrode fingers EF and the reflector elements REF are thereby arranged in the acoustic trace of the component EAB. The electrode fingers EF are thereby arranged at a right angle to the piezoelectric axis PA in order to enable optimal electro-acoustic coupling. The side edges SK of the chip CH are rotated at an angle 1 as compared to conventional components. The piezoelectric axis thus forms, with a side edge SK, an angle 2 which deviates from a right angle by 1. The surface area requirements of the chip CH are thereby increased as compared to conventional components because the surface of the piezoelectric chip cannot be used for transducer structures with a rectangular cross-section in the area of the four chip edges.

[0054] FIG. 2 shows how the chip, piezoelectric axis PA, and wafer W are oriented relative to one another. The electrode fingers on the chip are positioned vertically on the piezoelectric axis PA. A chip edge forms, with the piezoelectric axis, an angle 2 which deviates from a right angle. The chip CH is thereby cut from a wafer W by sawing. The orientation of the marking (primary flat) PF of the wafer forms the angle 3 with the piezoelectric axis PA. If 3 characterizes a right angle, then wafer W corresponds to a customary wafer.

[0055] FIG. 3 shows an advantageous wafer W in which the marking PF is rotated relative to the piezoelectric axis PA, analogous to the side edge of the chip. The marking PF and the piezoelectric axis PA form an angle 3, equal to the angle 2 that the chip edge and the piezoelectric axis PA enclose. Angles 2 and 3 in this case deviate from a right angle by the angle that is preferably between 3 and 10. The transducer structures can thereby be oriented orthogonal to the piezoelectric axis and obtain a good electro-acoustic coupling. Simultaneously, a production method is simplified because the cut edges of the subsequent chips are oriented parallel or orthogonal to the marking PF of the transducer.

[0056] FIG. 4 shows how a plurality of subsequent chips (for example here four) can be arranged relative to one another and relative to the marking PF of the wafer W. The individual chips CH with the transducer structures thereupon are obtained by sawing of the wafer W.

[0057] FIG. 5 shows the progression of a plurality of individual, actually implemented measurements of the insertion loss (IL) for a plurality of conventional components IL1 and for a plurality of similar improved components IL2 in which rectangular transducer structures are arranged on rectangular chips, the electrode fingers of the transducer structures are oriented at a right angle with respect to the piezoelectric axis, and the substrate edges of the chip are rotated by a few degrees as compared to the piezoelectric axis. The components thereby realize bandpass filters with a DMS structure and at least one basic element of a ladder-type structure. The bandpass filter itself has a passband range between 734 MHz and 756 MHz. The insertion loss at 790 MHz is improved by 4.5 dB, on average.

[0058] The component is thereby not limited to the embodiments described. Components comprising additional component structures, such as additional electrode fingers or reflector elements, also represent embodiments according to the invention.

LIST OF REFERENCE SIGNS

[0059] BB: busbar [0060] CH: chip [0061] EAB: electro-acoustic component [0062] EAWS: electro-acoustic transducer structure [0063] EF: electrode finger [0064] IL1: insertion loss of conventional component [0065] IL2: insertion loss of components in which the rectangular chip is rotated relative to the piezoelectric axis [0066] PA: piezoelectric axis [0067] PF: marking of the wafer [0068] REF: reflector elements [0069] SK: side edge of chip [0070] 1: angle by which the substrate edges are rotated relative to conventional components or angle between the electrode fingers and a side edge [0071] 2: angle between the substrate edge SK and the piezoelectric axis PA [0072] 3: angle between the marking of the wafer and the piezoelectric axis