Electricoacoustic component with structured conductor and dielectric layer

Abstract

An electroacoustic component includes a substrate configured to carry acoustic waves. The electroacoustic component can be a guided bulk acoustic wave (GBAW) device, for example. A structured electric conductive layer is arranged on the substrate and an electrically dielectric layer (for example, aluminum oxide) is also arranged over the substrate.

Claims

1. An electroacoustic component comprising: a substrate configured to carry acoustic waves; a structured electrically conductive layer arranged directly on the substrate; a SiO.sub.2 layer arranged directly on the structured electrically conductive layer; a dielectric layer arranged directly on the SiO.sub.2 layer, wherein: the dielectric layer has at least one first region comprising Al.sub.2O.sub.3 and one or more second regions each comprising a metal; and the one or more second regions extend through the dielectric layer and a portion of the SiO.sub.2 layer; and an insulating covering layer arranged directly on the dielectric layer and the SiO.sub.2 layer, wherein the insulating covering layer comprises a material different from Al.sub.2O.sub.3.

2. The electroacoustic component according to claim 1, wherein the electroacoustic component operates with guided bulk acoustic waves.

3. The electroacoustic component according to claim 1, wherein the substrate is configured to carry a guided bulk acoustic wave having a wavelength, and wherein the first region of the dielectric layer is thicker than half the wavelength of the bulk acoustic wave.

4. The electroacoustic component according to claim 1, wherein the structured electrically conductive layer comprises Cu, Ag, Au, Pt, or Ti.

5. The electroacoustic component according to claim 1, wherein the substrate comprises LiNbO.sub.3 or LiTaO.sub.3.

6. The electroacoustic component according to claim 1, wherein the dielectric layer has a thickness of 1 m to 30 m.

7. An electroacoustic component comprising: a substrate comprising LiNbO.sub.3 or LiTaO.sub.3; an electrically conductive layer arranged directly on the substrate, wherein the electrically conductive layer is structured to form an electroacoustic transducer; a SiO.sub.2 layer arranged directly on the electrically conductive layer and the substrate; a dielectric layer arranged directly on the SiO.sub.2 layer, wherein: the dielectric layer comprises a plurality of first regions each comprising aluminum oxide, and a plurality of second regions each comprising a metal; the plurality of second regions extend through the dielectric layer and a portion of the SiO.sub.2 layer; and the substrate, the electrically conductive layer and the dielectric layer each comprise a part of a guided bulk acoustic wave device; an electrically conductive Al layer arranged directly on the dielectric layer, wherein the electrically conductive Al layer is connected to the electrically conductive layer via the plurality of second regions of the dielectric layer; and an insulating covering layer arranged directly on the dielectric layer, the SiO.sub.2 layer and the electrically conductive Al layer, wherein the insulating covering layer comprises a material different from aluminum oxide.

8. The electroacoustic component according to claim 7, wherein the SiO.sub.2 layer is thicker than half a wavelength of a bulk acoustic wave of the guided bulk acoustic wave device.

9. The electroacoustic component according to claim 7, wherein the electrically conductive layer further comprises Cu, Ag, Au, Pt, or Ti.

10. The electroacoustic component according to claim 7, wherein the dielectric layer has a layer thickness of 1 m to 30 m.

11. An electroacoustic component comprising: a substrate configured to carry acoustic waves; a structured electrically conductive layer arranged directly on the substrate; a SiO.sub.2 layer arranged directly on the structured electrically conductive layer; a dielectric layer arranged directly on the SiO.sub.2 layer, wherein: the dielectric layer has a first region comprising Al.sub.2O.sub.3 and a plurality of second regions comprising a metal; and the plurality of second regions extend through the dielectric layer and a portion of the SiO.sub.2 layer; electrical contacts connecting the structured electrically conductive layer through the SiO.sub.2 layer and the plurality of second regions of the dielectric layer to a contact outside of the electroacoustic component; and an insulating covering layer arranged directly on the dielectric layer, wherein the insulating covering layer comprises a material different from Al.sub.2O.sub.3.

12. The electroacoustic component according to claim 11, wherein the substrate is configured to carry a guided bulk acoustic wave having a wavelength, and wherein the dielectric layer is thicker than half the wavelength of the bulk acoustic wave.

13. The electroacoustic component according to claim 11, wherein the structured electrically conductive layer comprises Cu, Ag, Au, Pt, or Ti.

14. The electroacoustic component according to claim 11, wherein the dielectric layer has a thickness of 1 m to 30 m.

15. The electroacoustic component according to claim 11, wherein the substrate comprises LiNbO.sub.3 or LiTaO.sub.3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Specific embodiments of the invention will be explained in greater detail below with reference to the figures:

(2) In the figures:

(3) FIGS. 1a to 1g show schematic illustrations of an electric component in different method stages;

(4) FIGS. 2a to 2i show schematic illustrations of a further electric component in different method stages;

(5) FIGS. 3a to 3c show schematic illustrations of different embodiment variants of the electrical component;

(6) FIG. 4 shows a schematic illustration of an embodiment of the electric component; and

(7) FIG. 5 shows a schematic illustration of a further embodiment of the electric component.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(8) FIG. 1 shows a schematic illustration of an embodiment of the electric component. This component comprises a substrate 1, a structured electric conductive layer 2 arranged thereon and also an electrically nonconductive layer 3 arranged thereon. Such an electric component is obtained by means of the following method steps, for example: providing an electric substrate 1, applying an electrically conductive layer 2 to the substrate, structuring the electrically conductive layer 2, and applying an electrically nonconductive layer 3 to the structured conductive layer 2.

(9) In this case, the electrically conductive layer 2 can be structured to form an electroacoustic transducer. The transducer can have, for example, comb-like electrodes that intermesh. In this case, each electrode can have electrode fingers which are realized as strip-type structures of the electrically conductive layer and which extend perpendicularly to the wave propagation direction. The electrically conductive layer 2 can furthermore have acoustic reflectors, for example. In this case, each reflector can have at least one strip, for example. The width of the strip is preferably approximately wavelength. In the case of a plurality of strips, the distance between the strips can likewise be wavelength. The transducer can be shaped such that it is suitable for unidirectional and for bi-directional emission of an acoustic wave. The materials are preferably chosen such that the propagation speed of an acoustic wave is lower in the electrically nonconductive layer 3 than in the adjoining layers.

(10) FIG. 1b shows an embodiment of the electric component, which could arise from the component illustrated in FIG. 1a by virtue of a resist 4 being applied to partial regions of the electrically nonconductive layer 3.

(11) FIG. 1c shows the schematic illustration of an embodiment of the electrical component, which could arise from a component illustrated in FIG. 1b. In order to arrive at the component illustrated in FIG. 1c, yet another method step can be performed, applying a base metallization 5.

(12) The embodiment of the electric component as illustrated schematically in FIG. 1d could arise, for example, from the component illustrated in FIG. 1c. For this purpose, in one method step, the resist 4 with the base metallization 5 deposited thereon can be removed again. Furthermore, the base metallization can be thickened to form a thick metal layer with the aid of an electrolytic method, for example. The metallic layer 6 could result from this.

(13) FIG. 1e shows the schematic illustration of an embodiment of the electric component, which could arise for example from the component illustrated in FIG. 1d. For this purpose, the metallic layer 6 can be oxidized to form the dielectric layer. In a further method step, the electrically nonconductive layer 3 can now be structured with the aid of an etching method. The etching is illustrated schematically by arrows in FIG. 1e. One possible etching method would be reactive ion etching, for example. The dielectric layer 7 can serve as a mask during the etching process. By way of example, partial regions of the structured electrically conductive layer 2 can be uncovered by the etching process.

(14) FIG. 1f schematically illustrates an embodiment of the electric component, which could arise, for example, from the component illustrated in FIG. 1e. For this purpose, a resist 4 can be applied on a partial region of the dielectric layer 7. Afterward, a contact layer 9 can be applied on the surface of the component. The contact layer 9 can serve for subsequently making electrical contact with the component.

(15) FIG. 1g schematically illustrates an embodiment of a component, which could arise, for example, from the component illustrated in FIG. 1f. For this purpose, the resist layer 4 with the contact layer deposited thereon can be removed. In a further method step, an electrically insulating covering layer 10 can be applied on the component.

(16) FIG. 2a schematically illustrates an embodiment of the electric component, which could arise, for example, from a component as illustrated in FIG. 1a. For this purpose, the electrically nonconductive layer 3 can be structured. In a further method step, a base metallization 5 can then be applied to the structured surface.

(17) FIG. 2b schematically illustrates an embodiment of the electric component, which could arise from a component as illustrated in FIG. 2a. For this purpose, the base metallization 5 illustrated in FIG. 2a can be thickened to form a metallic layer 6. This can be done with the aid of an electrolytic method, for example.

(18) The embodiment of the electric component as illustrated schematically in FIG. 2c can arise, for example, from the component illustrated in FIG. 2b by means of a resist 4 being applied to a partial region of the metallic layer 6.

(19) The embodiment of the electric component as illustrated schematically in FIG. 2d can arise, for example, from the electric component illustrated in FIG. 2c by means of the metallic layer 6 being etched and the resist 4 subsequently being removed.

(20) The embodiment of the electric component as illustrated schematically in FIG. 2e can arise, for example, from the electric component illustrated in FIG. 2d by means of an oxidation resist 11 being applied to a partial region of the metallic layer 6.

(21) The embodiment of the electric component as illustrated schematically in FIG. 2f can arise, for example, from an electric component as illustrated in FIG. 2e. For this purpose, the metallic layer 6 is selectively oxidized. This means that the partial regions which are not protected by an oxidation resist, for example, are fully oxidized in their entirety, whereas the partial regions which are protected by an oxidation resist, for example, remain as metallic regions. Consequently, a layer of the component can comprise the metallic layer 6 in partial regions and the dielectric layer 7 in other partial regions.

(22) The embodiment of the electric component as illustrated schematically in FIG. 2g can arise, for example, from the component illustrated in FIG. 2f by means of the oxidation resist 11 being removed. However, the electrolytically thickened, thick metallic layer present before the oxidation need not already be structured, as in FIG. 2g, but rather can appear as in FIG. 2b. The then continuous metallic layer 6 can then be selectively oxidized, as described in FIG. 2f.

(23) The embodiment of the electric component as illustrated schematically in FIG. 2h can arise, for example, from the electric component illustrated in FIG. 2g by virtue of the fact that, in a first method step, a resist 4 is applied to partial regions of the surface of the electric component, and, in a further method step, a contact layer 9 is deposited onto the surface of the electric component.

(24) The embodiment of the electric component as illustrated schematically in FIG. 2i can arise, for example, from the electric component illustrated in FIG. 2h. For this purpose, the resist 4 and the contact layer 9 deposited on the resist would be removed. In a further method step, an electrically insulating covering layer 10 is applied to a partial region of the surface of the electric component.

(25) The embodiment of the electric component as illustrated schematically in FIG. 3a can arise, for example, from the electric component illustrated in FIG. 2g by means of a contact layer 9 being deposited onto the uncovered surface of the metallic layer 6.

(26) The embodiment of the electric component as illustrated in schematically in FIG. 3b can arise, for example, from the electric component illustrated schematically in FIG. 3a. For this purpose, the electric component illustrated in FIG. 3a is applied to a circuit board 12. In this case, by way of example, the contact layer 9 is in electrically conductive contact with the conductor tracks 13 of the circuit board 12.

(27) The embodiment of the electric component as illustrated schematically in FIG. 3c can arise, for example, by a combination of the components as illustrated in FIG. 2g and FIG. 3a. For this purpose, the two components are joined together such that the contact layer 9 of the component illustrated in FIG. 3a comes into electrically conductive contact with the uncovered surface of the metallic layer 6 of the component illustrated in FIG. 2g. As a result, the structured electrically conductive layers 2 of the two previously separate components can now be electrically conductively connected.

(28) FIG. 4 shows the schematic illustration of an embodiment of an electric component. The latter comprises a substrate 1, on the edge regions of which contact layers 9 for making electrical contact are deposited. Furthermore, the component comprises two passivation layers 8. The passivation layer 8 can comprise Si.sub.3N.sub.4 for example. Arranged between the two passivation layers 8 is a layer with a sequence of metallic layers 6 and dielectric layers 7. By way of example, coils can be defined by means of such a sequence of correspondingly structured layers. In this case, one of the metallic layers 6 can be electrically conductively connected to one contact layer 9, and a further metallic layer 6 can be electrically conductively connected to another contact layer 9.

(29) FIG. 5 shows the schematic illustration of an embodiment of an electric component, which could arise, for example, by the combination of two components of identical type. For this purpose, one component was turned and joined together with the first component by way of the corresponding areas.

(30) The component thus produced comprises a substrate 1, on which two structured electrically conductive layers 2 are present. An electrically nonconductive layer 3 is applied on the electrically conductive layers 2. Partial regions of the two electrically conductive layers 2 are connected to one another via a contact layer 9. A dielectric layer 7 is situated on the electrically nonconductive layer 3. The electric component is provided with an electrically insulating covering layer 10.

(31) In a further method variant, the base metallization 5 is structured before the layer is thickened. In this case, the base metallization 5 can be removed in partial regions. This has the advantage that no or only a thinner thickened metallic layer 6 is formed at these locations. This in turn has the advantage that now the thick metallic layer 6 need not be structured. Consequently, in a simple manner, by way of example, contact holes can be provided or it is also possible that, at locations at which singulation is intended to take place subsequently, the metallic layer 6 and the dielectric layer 7 arising therefrom are not actually produced at all. A further advantage afforded by this method is that, on account of the continuous thick metallic layer 6 being absent, fewer strains occur. In this case, the base metallization 5 can also be structured by means of methods that do not involve a high resolution, such as contact exposure, for example.

(32) A method variant is also conceivable in which a first base metallization 5 is applied, which is then thickened to form a metallic layer 6 by means of an electrolytic method, for example. Afterward, a second base metallization 5 is applied and it, too, is in turn thickened to form a metallic layer 6. Afterward, both metallic layers 6 can then be oxidized in one method step. A method variant is likewise conceivable in which firstly a first metallic layer 6 is generated by means of a thickening method, the layer is then oxidized, a second metallic layer 6 is generated on the first oxidized layer, and the second metallic layer is then likewise oxidized in a second oxidation step.

(33) In the case of electronic components which operate with bulk acoustic waves, the layer thickness of the dielectric layer is preferably thicker than half the wavelength of the bulk acoustic wave. In some embodiments, it is preferably even thicker than the wavelength. With the methods described above it is possible, for example, to produce dielectric layers 7 with a layer thickness of 1 to 30 m.

(34) The dielectric layer 7 produced according to one of the methods described above is suitable, for example, for use in radiofrequency technology. The methods are suitable, for example, for the production of GBAW components, capacitances, coils, resistors or else lines. Furthermore, a use, for example, for the production of switches, semiconductor components or else components which operate with surface waves is also conceivable. In the case of the GBAW components, the waveguiding can be effected by means of the layer sequence/layer system.

(35) The layer forming processes when thickening the base metallization 5 can be influenced or controlled by different factors. In the case of an electrolytic method, the current density, the voltage, the choice of electrolyte, the electrolyte concentration and temperature can be mentioned here, by way of example. Furthermore, the formation of the layer thickness can be directly related to the duration of the treatment. The oxidation of aluminum, for example, can be performed in various ways. Immersion in a bath for electrolytic oxidation, passage through such a bath, purely chemical oxidation or plasma-assisted oxidation methods can be mentioned here, by way of example.

(36) The invention is not restricted by the description of the exemplary embodiments. Rather, the invention encompasses any novel feature and also any combination of features, which in particular includes any combination of features in the patent claims, even if individual features themselves or their combination itself are not explicitly specified in the patent claims or exemplary embodiments.