ELECTRO ACOUSTIC FILTER COMPONENT AND METHOD OF MANUFACTURING TO REDUCE INFLUENCE OF CHIPPING

Abstract

An electro acoustic filter component with improved acoustic and/or electro acoustic performance is provided. The component comprises a piezoelectric material (PM) the sides of which are plane and preferably free from chipping defects. The piezoelectric material may be arranged above a carrier substrate (CS). A functional layer (FL) with plane sides may be arranged above an electrode structure (ES) as trimming, TCF or passivation layer. In the manufacturing method the piezoelectric material and the functional layer are removed from the dicing line, such that no chipping occurs for these layers.

Claims

1. An electro acoustic filter component, comprising: a piezoelectric material in a piezoelectric layer, an electrode structure in an electrode layer arranged on the piezoelectric layer; and a cavity above the electrode structure, wherein sides of the piezoelectric material are plane.

2. The electro acoustic filter component according to claim 1, wherein the plane sides of the piezoelectric layer are free from chipping.

3. The electro acoustic filter component according to claim 1, further comprising a functional layer on or above the electrode structure, wherein sides of the functional layer are plane.

4. The electro acoustic filter component according to claim 1, wherein the plane sides of the functional layer are free from chipping.

5. The electro acoustic filter component according to claim 4, wherein the functional layer covers the sides of the piezoelectric material.

6. The electro acoustic filter component according to claim 1, wherein the functional layer: is a TCF compensation layer, a trimming layer or a passivation layer; and comprises or consists of a material selected from a dielectric material, a nitride, SiN.sub.4, an oxide, a silicon oxide, SiO.sub.2.

7. The electro acoustic filter component according to claim 1, wherein the cavity is formed by a thin film package, TFAP.

8. The electro acoustic filter component according to claim 1, wherein the piezoelectric material is arranged on or above a carrier substrate.

9. The electro acoustic filter component according to claim 8, wherein the piezoelectric material and/or the functional layer has an extension in a lateral direction that is smaller than the extension of the carrier substrate.

10. The electro acoustic filter component according to claim 8, wherein the carrier substrate has diced sides.

11. The electro acoustic filter component according to claim 1, further comprising an additional layer between the piezoelectric material and the carrier substrate.

12. The electro acoustic filter component according to claim 11, wherein the additional layer is a waveguiding layer.

13. A method of manufacturing an electro acoustic filter component, comprising: providing a wafer material as a material for carrier substrates; arranging a piezoelectric material on or above the wafer material; structuring an electrode structure on the piezoelectric material; and dicing the wafer material into individual pieces, wherein when dicing the wafer material is free from the piezoelectric material at the dicing positions.

14. The method of claim 13, further comprising: structuring the piezoelectric material to have no piezoelectric material at the dicing positions.

Description

[0046] In the figures:

[0047] FIG. 1 shows a cross-section through an electro acoustic filter component FC comprising intact sides of the piezoelectric material;

[0048] FIG. 2 shows the possibility of covering the sides of the piezoelectric material with material of the functional layer;

[0049] FIG. 3 shows the possibility of enclosing the piezoelectric material and the functional layer within the cavity enclosed by the thin film package and the carrier substrate, too;

[0050] FIG. 4 illustrates a cross-section through an electro acoustic filter component having chipping defects in the piezoelectric material and in the functional layer.

[0051] FIG. 5 shows the possibility of a arranging the functional layer between the piezoelectric material and the carrier substrate.

[0052] FIG. 1 shows a cross-section through an electro acoustic filter component FC with an improved acoustic performance. The component comprises a carrier substrate CS on which the piezoelectric material PM is arranged in a piezoelectric layer. On the piezoelectric material PM an electrode structure ES is arranged. The electrode structure ES comprises interdigitated electrode fingers extending along the transversal direction y perpendicular to the longitudinal direction x and to the vertical direction z. The electrode structure ES is covered by material of a functional layer FL. The top surface of the active structure comprising the electrode structure in the piezoelectric material is covered by the thin film cap of a thin film package TFP.

[0053] The lateral extension of the piezoelectric material PM in a longitudinal direction x or in a lateral direction y being smaller than the corresponding extension of the carrier substrate CS allows that the dicing tool that is used to singulate the pieces for the carrier substrate CS does not get in contact with the piezoelectric material PM. Thus, the sides of the piezoelectric material PM is free from defects such as chipping defects.

[0054] FIG. 2 shows the possibility of extending the functional layer FL around the sides of the piezoelectric material PM to protect the corresponding sides of the piezoelectric material. Thus, the piezoelectric material is fully enclosed within the functional layer FL and the carrier substrate CS.

[0055] FIG. 3 further shows the possibility of extending the cap of the thin film TFP to the vertical position z of the top side of the carrier substrate CS such that a further improvement of the hermetical sealing is obtained.

[0056] FIG. 4, in contrast, shows a filter component FC where the piezoelectric material PM and the material of the functional layer FL is in a longitudinal direction (x) and lateral (y) essentially flush with the material of the carrier substrate CS. As a consequence thereof, chipping defects can take place in the sides of the piezoelectric material PM and in the sides of the material of the functional layer FL as indicated in FIG. 4.

[0057] FIG. 5 shows a cross-section through an electro acoustic filter component FC where an additional layer is arranged between the carrier substrate CS and the piezoelectric material PM. The additional layer can be a waveguiding layer WGL.

[0058] Further, the sides of the piezoelectric material, of the waveguiding layer and at the specific position of the functional layer FL are oriented in an angle between 0° and 90° with respect to the top surface of the carrier substrate. The angle can be in the interval from 20° to 70°.

[0059] Further, FIG. 5 shows chipping defects CD that exist in the carrier substrate at its sides but the piezoelectric material PM, the functional layer FL and the additional waveguiding layer WGL are free from chipping defects.

[0060] The electro acoustic filter component and the method of manufacturing such a component are not limited to the technical details described above or shown in the figures. Components can comprise further structural elements, e.g. for establishing a wanted acoustic wave mode and further electrical connections to other circuit components of the filter or to an external circuit environment.

LIST OF REFERENCE SIGNS

[0061] CD: chipping defect [0062] CS: carrier substrate [0063] ES: electrode structure [0064] FC: electro acoustic filter component [0065] FL: functional layer [0066] PM: piezoelectric material [0067] TFCP: thin film package [0068] WGL: waveguiding layer [0069] x: longitudinal direction [0070] z: vertical direction