Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
ELECTRIC COMPONENT, ELECTRIC DEVICE AND METHOD FOR MANUFACTURING A PLURALITY OF ELECTRIC COMPONENTS
Document Type and Number:
WIPO Patent Application WO/2020/249467
Kind Code:
A1
Abstract:
Electric component, electric device and method for manufacturing a plurality of electric components In at least one embodiment, the electric component (10) comprises a piezoelectric layer (1a), an electrode structure (2) with a first electrode (21) on a top side (11) of the piezoelectric layer, a metallic frame (3) on the top side of the piezoelectric layer and a cover sheet (4) on top of the metallic frame. The electrode structure together with the piezoelectric layer forms a resonator for acoustic waves. A first section (21a) of the first electrode overlaps with an active region of the resonator. The cover sheet, the metallic frame and the piezoelectric layer surround a gas filledcavity (5). The first section of the first electrode is located in the cavity and is spaced from the cover sheet.

Inventors:
POH SIEW LI (US)
POIREL CEDRIC (US)
VALTERE MARKUS (US)
Application Number:
EP2020/065527
Publication Date:
December 17, 2020
Filing Date:
June 04, 2020
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
RF360 EUROPE GMBH (DE)
International Classes:
H01L41/047; H01L41/053
Foreign References:
JP2016066989A2016-04-28
US20140191617A12014-07-10
US20130119490A12013-05-16
Attorney, Agent or Firm:
HESELBERGER, Johannes et al. (DE)
Download PDF:
Claims:
Claims

1. Electric component (10), comprising

- a piezoelectric layer (la),

- an electrode structure (2) with a first electrode (21) on a top side (11) of the piezoelectric layer (la),

- a metallic frame (3) on the top side (11) of the

piezoelectric layer (la),

- a cover sheet (4) on top of the metallic frame (3), wherein

- the electrode structure (2) together with the piezoelectric layer (la) forms a resonator for acoustic waves,

- a first section (21a) of the first electrode (21) overlaps with an active region of the resonator,

- the cover sheet (4), the metallic frame (3) and the

piezoelectric layer (la) surround a gas-filled cavity (5),

- the first section (21a) of the first electrode (21) is located in the cavity (5) and is spaced from the cover sheet (4) .

2. Electric component (10) according to claim 1, wherein the metallic frame (3) is electrically connected to the electrode structure (2) .

3. Electric component (10) according to claim 1 or 2, wherein the cover sheet (4) comprises or consists of at least one of the following materials: polymer, polyimide, photoresist,

SU8, graphene, acryl, epoxy.

4. Electric component (10) according to one of the preceding claims, wherein

the cover sheet (4) comprises a matrix material in which particles of a thermally conductive material are embedded, wherein the thermal conductivity of the thermally conductive material is greater than that of the matrix material.

5. Electric component (10) according to one of the preceding claims, wherein

- a side surface (32) of the metallic frame (3) and a side surface (12) of the electric component (10) terminate flush with each other,

- the side surface (32) of the metallic frame (3) and/or the side surface (12) of the electric component (10) show traces of a physical or chemical material removal.

6. Electric component (10) according to one of the preceding claims, wherein

- the electric component (10) comprises interconnect

structures (6) on the top side (11) of the piezoelectric layer (la) which are configured for an electrical and

mechanical connection of the electric component (10) to an external connection carrier,

- the interconnect structures (6) project beyond the cover sheet (4) in a direction away from the piezoelectric layer (la) .

7. Electric component (10) according to claim 6, wherein, in a plan view on the top side of the piezoelectric layer (la), at least one interconnect structure (6) is completely surrounded by the cover sheet (4) .

8. Electric component (10) according to claim 6 or 7, wherein, in a plan view on the top side (11) of the

piezoelectric layer (la), a region of the electric component (10) between an interconnect structure (6) and a side surface (12) of the component (10) is free of the cover sheet (4) . 9. Electric device, comprising

- an electric component (10) according to one of the

preceding claims 6 to 8,

- a connection carrier (8) with connection areas (81), wherein

- the electric component (10) is arranged on the connection carrier (8) with the top side (11) facing the connection carrier ( 8 ) ,

- the interconnect structures (6) are electrically and mechanically connected to the connection areas (81) .

10. Electric device according to claim 9, further comprising

- a mold material (7), wherein

- the electric component (10) is embedded in the mold material ( 7 ) .

11. Electric device according to claim 10, wherein

- at least one interconnect structure (6) is at least partially embedded in the mold material (7) .

12. Electric device according to claim 10 or 11, wherein

- the cover sheet (4) is spaced from the connection carrier (8) by an intermediate space,

- the intermediate space is at least partially filled with the mold material (7) .

13. Method for manufacturing a plurality of electric

components (10) comprising the steps of:

A) Providing a piezoelectric layer (la),

B) Forming a plurality of electrode structures (2) each comprising a first electrode (21) on a top side (11) of the piezoelectric layer (la), C) Forming metallic frames (3) on the top side (11) of the piezoelectric layer (la),

D) Attaching a cover sheet layer (40) on top of the metallic frames (3), wherein the cover sheet layer (40), the metallic frames (3) and the piezoelectric layer (la) surround gas- filled cavities (5) in which first sections (21a) of the first electrodes (21) are located, wherein the cover sheet layer (40) is spaced from the first sections (21a) of the first electrodes (21),

E) Separating the composite comprising the piezoelectric layer (la), the first electrodes (21), the metallic frames (3) and the cover sheet layer (40) into a plurality of electric components (10), wherein each electric component (10) comprises

- a section of the piezoelectric layer (la),

- an electrode structure (2) with a first electrode (21),

- a metallic frame (3),

- a cover sheet (4) which is a section of the cover sheet layer (40), wherein in each electric component (10)

- the electrode structure (2) together with the piezoelectric layer (la) forms a resonator for acoustic waves and the first section (21a) of the first electrode (21) overlaps with an active region of the resonator.

14. Method according to claim 13 further comprising the steps :

F) Structuring the cover sheet layer (40) by forming openings into the cover sheet layer (40),

G) Forming interconnect structures (6) configured for an electrical and mechanical connection to an external

connection carrier in the regions of the openings, wherein - the interconnect structures (6) project beyond the cover sheet layer (40) in the direction away from the piezoelectric layer ( la) .

Description:
Description

Electric component, electric device and method for

manufacturing a plurality of electric components

An electric component is specified. Furthermore, an electric device and a method for manufacturing a plurality of electric components are specified.

One object to be achieved is to specify an electric component with high thermal stability. Further objects to be achieved are to specify an electric device with such an electric component and a method for producing such electric

components .

These objects are achieved, inter alia, by the subject- matters of claims 1, 9 and 13. Advantageous embodiments and further developments are the subject of the further dependent claims .

First, the electric component is specified. Particularly, the electric component is a filter, preferably an RF filter. The electric component can be a surface acoustic wave filter (SAW filter) or a bulk acoustic wave filter (BAW filter) .

Particularly preferably, the electric component is a chip resulting from the separation of a wafer. Side surfaces of the electric component may therefore show traces of a

separation process.

According to at least one embodiment, the electric component comprises a piezoelectric layer. For example, the

piezoelectric layer comprises or consists of one or more of the following materials: AIN, ZnO, AlScN, lithium tantalate, lithium niobate, quartz. The piezoelectric layer is

preferably mounted on a support. The support is the

stabilizing element of the electric component and carries all elements applied on the support. The support is, for example, made of a semiconductor material. The support may comprise or consist of silicon, sapphire, silicon carbide, diamond or aluminum nitride. Alternatively, the piezoelectric layer itself forms the support.

The thickness of the support is preferably at least 30 pm or at least 50 pm or at least 100 pm and/or at most 500 pm or at most 300 pm. If the support is different from the

piezoelectric layer, the piezoelectric layer is preferably a thin-film. The thickness of the support is measured

perpendicularly to the top side of the piezoelectric layer. Here and in the following, the term "thickness" either refers to the minimum thickness or the maximum thickness or the average thickness.

According to at least one embodiment, the electric component comprises an electrode structure with a first electrode on a top side of the piezoelectric layer. The first electrode is preferably in direct contact with the piezoelectric layer.

The electrode structure is preferably made of a metal. For example, the electrode structure comprises or consists of one or more of the following metals: Al, Cu, Ti, Cr, Au, Pd, Mo, Ni . In the case that the electric component comprises a support different from the piezoelectric layer, the top side of the piezoelectric layer is the side facing away from the support. A rear side of the piezoelectric layer is the side opposite to the top side. According to at least one embodiment, the electric component comprises a metallic frame on the top side of the

piezoelectric layer. The metallic frame is preferably in direct contact with the piezoelectric layer. For example, the metallic frame comprises the same material as the electrode structure. The mean thickness of the metallic frame, measured perpendicular to the top side of the piezoelectric layer, is for example at least 500 nm or at least 1 pm or at least 3 pm. Additionally or alternatively, the mean thickness is at most 20 pm or at most 10 pm. A width of the metallic frame, measured parallel to the top side of the piezoelectric layer, is, for example, at least 1 pm or at least 5 pm. Additionally or alternatively, the width of the metallic frame is at most 50 pm or at most 20 pm or at most 10 pm.

The metallic frame and/or the electrode structure are

preferably covered with a thin passivation layer of an electrically isolating material. For example, the passivation layer comprises or consists of SiN, SiOg or AlgOg. The thickness of the passivation layer is preferably at most 500 nm or at most 100 nm or at most 50 nm.

According to at least one embodiment, the electric component comprises a cover sheet on top of the metallic frame. For example, the cover sheet is in direct contact with the metallic frame or with the passivation layer. For example, the cover sheet is made of an electrically isolating

material. Alternatively, the cover sheet is made of an electrically conductive material, like a metal. In this case the cover sheet is preferably electrically isolated from the metallic frame. A mean thickness of the cover sheet is preferably at least 10 pm or at least 25 pm. Additionally or alternatively, the mean thickness of that cover sheet is at most 100 mpi or at most 75 mih. Preferably, the cover sheet has the geometrical shape of a plate or a film with two

essentially parallel main sides.

According to at least one embodiment, the electrode structure together with the piezoelectric layer forms a resonator for acoustic waves. For example, the resonator is a SAW resonator or a BAW resonator. For this purpose, the electrode structure preferably comprises a second electrode besides the first electrode. In the case of an SAW resonator, the second electrode is also applied to the top side of the

piezoelectric layer. The first and the second electrode then each comprise a busbar and a plurality of fingers connected by the busbar. In each electrode, the fingers are arranged in a comb-like manner. The fingers of the first electrode and the fingers of the second electrode interdigitate but are electrically isolated from one another. In other words, the first and the second electrodes are interdigital electrodes.

If the resonator is a BAW resonator, the second electrode is arranged on the rear side of the piezoelectric layer opposite to the top side.

For example, the resonator formed by the electrode structure has a resonant frequency of at least 0.4 GHz or at least 2.5 GHz or at least 5 GHz or at least 6 GHz.

According to at least one embodiment, a first section of the first electrode overlaps with an active region of the

resonator. The active region of the resonator is the region in which acoustic waves are produced and/or propagate. The first section, particularly its mass and geometrical shape, influences the acoustic properties of the resonator. The fact that the first section of the first electrode overlaps with the active region of the resonator means that, in a plan view on the top side of the piezoelectric layer, the first section overlaps with the active region. Analogously, the second electrode comprises a first section overlapping with the active region of the resonator.

In the case of an SAW resonator, the first sections are in each case defined by the fingers of the electrode. In the case of a BAW resonator, the first section of the first and second electrode is defined by the overlap region of the first and second electrode, when both electrodes are

projected onto the top side.

According to at least one embodiment, the cover sheet, the metallic frame and the piezoelectric layer surround a gas- filled cavity.

According to at least one embodiment, the first section of the first electrode is located in the cavity and is spaced from the cover sheet. Analogously, the first section of the second electrode is located in the cavity and spaced from the cover sheet in the case of a SAW resonator.

The metallic frame laterally surrounds the cavity, whereas the cover sheet and the piezoelectric layer close the cavity from the top and from the bottom. Thus, the metallic frame laterally surrounds the first section of the first electrode. For example, the metallic frame completely laterally

surrounds the first section of the first electrode.

Preferably, however, the metallic frame almost completely laterally surrounds the first section of the first electrode. In this case, the metallic frame is not formed contiguously but is interrupted. For example, a closed loop can be drawn around the first section of the first electrode wherein the metallic frame extends over at least 75 % or at least 80 % or at least 85 % of the length of the loop but not over the full length of the loop. Here and in the following, a lateral direction is a direction parallel to the top side or main extension plane of the piezoelectric layer.

The first section of the first electrode is spaced from the cover sheet, which means that the first section is not in direct contact with the cover sheet. In this way, the cover sheet does not bring an additional mass load to the first section of the first electrode and thus does not influence the acoustic properties of the resonator. For example, a minimum distance between the cover sheet and the first section of the first electrode is at least 500 nm or at least 1 pm or at least 3 pm or at least 5 pm. The interspace between the cover sheet and the first section of the first electrode is only filled with gas, like air.

In a plan view onto the top side of the piezoelectric layer, the first section of the first electrode is preferably completely covered by the cover sheet. In the same way, in a plan view on the rear side of the piezoelectric layer, the first section of the first electrode is completely covered by the piezoelectric layer. Preferably, the cover sheet and/or the piezoelectric layer extend over the full lateral extent of the electric component. The cover sheet and/or the

piezoelectric layer are preferably formed contiguously.

The distance between the cover sheet and the first section of the first electrode is preferably realized by the metallic frame being thicker than the first section of the first electrode. For example, the thickness of the metallic frame is at least two times or at least ten times or at least 50 times the thickness of the first electrode in the first section .

All features disclosed herein in connection with the first electrode and the first section of the first electrode are also disclosed for the second electrode and the first section of the second electrode, especially in the case that the resonator is a SAW resonator. Particularly, all sections of the electrode structure which are arranged on the top side of the piezoelectric layer and which contribute to and overlap with the active region of the resonator are located in the cavity and are spaced from the cover sheet.

Preferably, the electric component comprises two or more electrode structures, each with a first electrode and a second electrode, wherein in each case the first electrode is arranged on the top side. The electrode structures each form a resonator together with the piezoelectric layer. All features disclosed for one electrode structure/resonator are also disclosed for the other electrode structures/resonators of the electric component. Particularly, the metallic frame laterally surrounds all the first sections of the first electrodes. All the first sections of the first electrodes are preferably located in the cavity formed by the metallic frame, the piezoelectric layer and the cover sheet.

The resonators are connected in series or in anti-series or in parallel or in anti-parallel and, for example, realize a filter. In this case, the piezoelectric layer preferably extends contiguously over the plurality of electrode

structures . In at least one embodiment, the electric component comprises a piezoelectric layer, an electrode structure with a first electrode on a top side of the piezoelectric layer, a

metallic frame on the top side of the piezoelectric layer and a cover sheet on top of the metallic frame. The electrode structure together with the piezoelectric layer forms a resonator for acoustic waves. A first section of the first electrode overlaps with an active region of the resonator.

The cover sheet, the metallic frame and the piezoelectric layer surround a gas filled-cavity . The first section of the first electrode is located in the cavity and is spaced from the cover sheet.

The present invention is based, inter alia, on the

recognition that RF components are getting smaller and smaller, which leads to a higher acoustic density and which therefore increases the heat density. Moreover, the drive towards high-power RF components also leads to an increase of density. The challenge is to design an electric component in such a way that material of high heat conductivity is used which spreads the heat on the component before it can leave the component. In the present invention, the metallic frame helps to efficiently distribute heat generated in the

electric component. Additionally, heat distribution is obtained by the cover sheet, which preferably extends over the full lateral extent of the electric component.

Another technical advantage of the present invention is that the metallic frame, the cover sheet and the piezoelectric layer define a cavity, and the first section of the first electrode contributing to the active region of the resonator is located therein. With such a cavity, the first section can be protected from external influences, particularly during mounting and molding the electric component.

According to at least one embodiment, the metallic frame is electrically connected to the electrode structure. For example, the metallic frame is electrically connected to the first and/or second electrode of the electrode structure. Particularly, a part of the metallic frame forms second sections of first electrode and/or of the second electrode. For example, the second sections are the busbars of the first and/or second electrodes connecting the fingers. The second section (s) preferably do not overlap with the active region of the resonator.

The metallic frame may form a conductor track between an input terminal or output terminal or ground terminal and the first and/or second electrode. Particularly, the metallic frame is electrically connected to electric structures of the electric component which, during the intended operation, lie on different electric potentials. In this case, in order to avoid short-circuits, the metallic frame is not formed contiguously but is interrupted.

Alternatively, the metallic frame is electrically isolated from the first and/or second electrode. In this case, the metallic frame may be formed contiguously. The metallic frame may be electrically isolated from any electric structure of the electric component.

According to at least one embodiment, the cover sheet

comprises or consists of at least one of the following materials: polymer, polyimide, photoresist, SU8, graphene, acryl, epoxy. According to at least one embodiment, the cover sheet

comprises a matrix material in which particles of a thermally conductive material are embedded, wherein the thermal conductivity of the thermally conductive material is greater than that of the matrix material. The matrix material is, for example, one of the materials mentioned above. For example, the thermally conductive material is aluminum nitride, beryllium oxide or silicon carbide. The thermal conductivity of the thermally conductive material is preferably at least 150 W/ (m-K) or at least 200 W/ (m-K) . The thermal conductivity of the cover sheet is for example at least 2.5 W/ (m-K) or at least 5 W/ (m-K) or at least 10 W/ (m-K) . The cover sheet with an increased thermal conductivity can further improve the thermal properties of the electric component.

According to at least one embodiment, a side surface of the metallic frame and a side surface of the electric component terminate flush with each other. The side surfaces extend perpendicularly or transversely to the top side of the piezoelectric layer. For example, the electric component has the shape of a cuboid with four side surfaces extending transversely to the top side of the piezoelectric layer. The metallic frame may terminate flush which each of these side surfaces. Alternatively, the metallic frame is spaced from the side surfaces and shifted to the center.

According to at least one embodiment, the side surface of the metallic frame and/or the side surface of the electric component show traces of a physical or chemical material removal. As already mentioned above, the electric component is preferably a chip resulting from separating a wafer. When separating the wafer, the separation planes may run through the metallic frame. According to at least one embodiment, the electric component comprises interconnect structures on the top side of the piezoelectric layer. The interconnect structures are

configured for an electrical and mechanical connection of the electric component to an external connection carrier. For example, the electric component comprises at least four interconnect structures. The interconnect structures may be placed on the metallic frame. The interconnect structures are, for example, solder bumps or pillars or LGA pads (LGA = Land Grid Array) . Particularly, the interconnect structures are electrically connected to the electrode structure and/or to the metallic frame. In an unmounted configuration of the electric component, the interconnect structures are freely accessible .

According to at least one embodiment, the interconnect structures project beyond the cover sheet in a direction away from the piezoelectric layer. For example, the interconnect structures project beyond the cover sheet by at least 5 pm or at least 10 pm or at least 20 pm.

According to at least one embodiment, in a plan view on the top side of the piezoelectric layer, at least one

interconnect structure is completely surrounded by the cover sheet. For example, several or all interconnect structures are completely surrounded by the cover sheet in this plan view. In other words, the cover sheet comprises at least one hole, in which one interconnect structure is arranged. Once again in other words, at least one interconnect structure is completely surrounded by the cover sheet in the lateral directions . According to at least one embodiment, in a plan view on the top side of the piezoelectric layer, the region of the electric component between an interconnect structure and a side surface of the component is free of the cover sheet. In other words, the cover sheet does not completely surround the interconnect structure in this plan view. The interconnect structure is then placed in a recess of the cover sheet. This may apply to several or all interconnect structures of the electric component.

Next, the electric device is specified. The electric device comprises an electric component as specified herein. The electric device may comprise several electric components, for example several electric components as specified herein. The electric device is for example a duplexer or a multiplexer.

According to at least one embodiment, the electric device comprises a connection carrier with connection areas. The connection carrier is, for example, a laminate based on a polymer with embedded conductor tracks. For example, the connection carrier is a printed circuit board. The connection areas are electrically conductive, preferably metallic. The connection areas are configured to provide an electrical connection to the electric component.

According to at least one embodiment, the electric component is arranged on the connection carrier with the top side facing the connection carrier. In other words, the first electrode of the electrode structure and the cover sheet are located between the connection carrier and the piezoelectric layer . According to at least one embodiment, the interconnect structures are electrically and mechanically connected to the connection areas. Particularly, the interconnect structures are soldered to the connection areas.

According to at least one embodiment, the electric device further comprises a mold material. The electric component is embedded in the mold material. Preferably, the mold material completely covers the electric component and laterally completely surrounds the electric component. The mold

material preferably establishes an additional mechanical connection between the electric component and the connection carrier .

For example, the mold material is based on a silicone or an epoxy. The mold material may comprise thermally conductive particles distributed in a matrix material. The thermally conductive particles may be made of the thermally conductive material mentioned above. In this way an improved thermal connection between the electric component and the connection carrier can be achieved.

According to at least one embodiment, at least one

interconnect structure is at least partially embedded in the mold material. This means that the mold material is in direct contact with the interconnect structure. Preferably, the mold material laterally completely surrounds the interconnect structure. Each interconnect structure can be partially or completely embedded in the mold material.

According to at least one embodiment, the cover sheet is spaced from the connection carrier by an intermediate space. Thus, the electric component is mounted on the connection carrier in such a way that the cover sheet is spaced from the connection carrier. Particular preferably, no part of the cover sheet is in direct contact with the connection carrier. The intermediate space may be partially or completely filled with gas. The distance between the cover sheet and the connection carrier is, for example, at least 5 pm or at least 10 pm or at least 20 pm.

According to at least one embodiment, the intermediate space is at least partially filled with the mold material. The mold material may completely or by at least 50 % or by at least 75 % fill the intermediate space between the cover sheet and the connection carrier. The rest of the intermediate space is preferably filled with gas.

For example, the mold material extends at least in regions contiguously between the connection carrier and the electric component so that the mold material gives additional

mechanical support to the electric component. Thus, the electric component is not only mechanically connected to the connection carrier by the interconnect structures but also by the mold material.

The mold material additionally supporting the electric component allows to reduce the sizes of the interconnect structures without increasing the risk of cracks due to thermal stress. However, the use of the mold material is only advantageous if the mold material does not disturb the properties of the resonator of the electric component. Thus, it should be avoided that the mold material comes into contact with those parts of the electrode structure on the top side of the piezoelectric layer, defining the resonator' s properties. Especially, a direct contact to the first section of the first and eventually of the second electrode, which overlap with the active region of the resonator, should be avoided. In the present case, this is achieved by placing the first section of the first electrode and possibly of the second electrode in a gas-filled cavity formed by the

metallic frame, the cover sheet and the piezoelectric layer. The cover sheet and the metallic frame prevent the mold material from reaching the first section of the electrodes. For this purpose, it is not even necessary that the metallic frame completely surrounds the first section in the lateral direction. Also an interrupted metallic frame with small trenches is sufficient.

Next, the method for manufacturing a plurality of electric components is specified. Particularly, the method is suitable for producing an electric component as specified herein.

Thus, all features specified for the electric component are also specified for the method and vice versa.

According to at least one embodiment, the method comprises a step A) , in which a piezoelectric layer is provided. The piezoelectric layer is preferably provided as part of a wafer composite. For example, the piezoelectric layer is provided as a layer on top of a substrate wafer, wherein the substrate wafer is made of a different material than the piezoelectric layer. The substrate wafer is for example made of a

semiconductor material. The piezoelectric layer preferably extends contiguously over the wafer substrate.

According to at least one embodiment, the method comprises a step B) , in which a plurality of electrode structures is formed. For each electrode structure a first electrode is formed on a top side of the piezoelectric layer. According to at least one embodiment, the method comprises a step C) , in which metallic frames are formed on the top side of the piezoelectric layer.

According to at least one embodiment, the method comprises a step D) , in which a cover sheet layer is attached on top of the metallic frames, wherein the cover sheet layer, the metallic frames and the piezoelectric layer surround gas- filled cavities in which first sections of the first

electrodes are located. The cover sheet layer is spaced from the first sections of the first electrodes. The cover sheet layer is, for example, applied as a contiguous layer without interruptions .

According to at least one embodiment, the method comprises a step E) , in which the composite comprising the piezoelectric layer, the first electrodes, the metallic frames and the cover sheet layer is separated into a plurality of electric components, wherein each electric component comprises a section of the piezoelectric layer, an electrode structure with a first electrode, a metallic frame and a cover sheet which is a section of the cover sheet layer. In each electric component, the electrode structure together with the

piezoelectric layer forms a resonator for acoustic waves. The first section of the first electrode overlaps with an active region of the resonator.

Separating can, for example, be done by forming trenches in the composite from the side of the cover sheet layer, wherein the trenches define the borders between adjacent electric components. For example, the trenches completely penetrate the cover sheet layer and the piezoelectric layer and end in the substrate wafer. Afterwards, the substrate wafer can be grinded from a side opposite to the piezoelectric layer until individual electric components are obtained. Alternatively, the composite is first grinded from the side opposite the piezoelectric layer and afterwards the composite is separated by forming trenches from the side of the cover sheet layer, for example by plasma dicing.

According to at least one embodiment, the steps A) to E) are performed one after the other in the stated sequence.

According to at least one embodiment, the method further comprises a step F) , in which the cover sheet layer is structured by forming openings into the cover sheet layer. Structuring the cover sheet layer with the openings is, for example, done with a photolithography process. The cover sheet layer is preferably made of a photoresist, like SU8.

According to at least one embodiment, the method comprises a step G) , in which interconnect structures configured for an electrical and mechanical connection to an external

connection carrier are formed in the regions of the openings. The interconnect structures project beyond the cover sheet layer in the direction away from the piezoelectric layer.

The interconnect structures may be formed on the metallic frame. For example, the interconnect structures are formed as solder bumps. Alternatively, the interconnect structures are each formed as a pillar or a LGA pad. In this case, the interconnect structures are preferably formed by plating. For example, after structuring the cover sheet layer, first a seed layer is applied to the cover sheet layer and inside the openings. Afterwards the interconnect structures are grown on the seed layer and the seed layer is removed from the cover sheet layer.

Preferably, the steps F) and G) are performed before the step E) .

Hereinafter, an electric component, an electric device and a method for manufacturing a plurality of electric components described herein will be explained in more detail with reference to drawings on the basis of exemplary embodiments. Same reference signs indicate same elements in the individual figures. However, the size ratios involved are not to scale, individual elements may rather be illustrated with an

exaggerated size for a better understanding.

As shown in:

Figures 1A to 3 exemplary embodiments of electric components in different views,

Figure 4 an exemplary embodiment of the electric device in a sectional view,

Figures 5A to 6 different positions in exemplary embodiments of the method.

Figure 1 shows a first exemplary embodiment of an electric component 10 in different views. Figures IB and ID are plan views of the electric component 10, whereas figures 1A and 1C are cross-sectional views along the lines AA' and CC' of figures IB and ID.

The electric component 10 comprises a piezoelectric layer la, for example of LiTaOg or LiNbOg . The piezoelectric layer la is placed on top of a support lb (see figures 1A and 1C) . The support lb is the mechanically stabilizing element of the electric component 10 and also carries the piezoelectric layer la. For example, the support lb is of silicon.

On a top side 11 of the piezoelectric layer la, an electrode structure 2 with a first electrode 21 and a second electrode 22 is located. The first 21 and second 22 electrodes are interdigital electrodes with a plurality of fingers

interdigitating (see also figure IB) . All fingers belonging to one electrode 21, 22 are electrically connected by a busbar. The electrode structure 2 with the first electrode 21 and the second electrode 22 together with the piezoelectric layer la form a SAW resonator. A first section 21a of the first electrode 21 and a first section 22a of the second electrode 22 overlap with an active region of the resonator, in which acoustic waves propagate during operation. In the present case, the first sections 21a, 22a are defined by the fingers of the electrodes 21, 22.

A metallic frame 3 is also placed on the top side 11 of the piezoelectric layer la. The metallic frame 3 surrounds the fingers of the electrodes 21, 22 in a lateral direction, measured parallel to the top side 11 of the piezoelectric layer la. The thickness of the metallic frame 3 is larger than a thickness of the fingers of the electrodes 21, 22.

On top of the metallic frame 3, a cover sheet 4 is located. For example, the cover sheet 4 is made of a polyimide, in which thermally conductive particles are embedded. The cover sheet 4 together with the metallic frame 3 and the

piezoelectric layer la enclose a cavity 5. The cavity 5 is filled with gas, like air. The first sections 21a, 22a of the electrodes 21, 22 are located inside the cavity 5 and are spaced from the cover sheet 4 by a gas-filled interspace. Thus, the cover sheet 4 is not in direct contact with parts of the electrodes 21, 22 which overlap with the active region of the resonator.

In figure 1 it can also be seen that interconnect structures 6 are placed on the metallic frame 3 and project beyond the cover sheet 4 in a direction away from the piezoelectric layer la. Here, the interconnect structures 6 are solder bumps which are in direct contact with the metallic frame 3. The interconnect structures 6 are configured for a mechanical and electrical connection to a connection carrier.

The electric component 10 of figure 1A is a chip,

particularly an RF filter chip. Side surfaces 12 of the component 10, running transversely to the top side 11, for example show traces of a material removal.

In figure IB a plan view on the top side 11 of the

piezoelectric layer la is shown. In order to see the electric structures, the cover sheet 4 is not shown in this view. As can be seen in figure IB, the electric component 10 actually comprises three electrode structures 2, each of which forms a resonator with the piezoelectric layer la. The piezoelectric layer la extends contiguously over all resonators. Each resonator is a SAW resonator with interdigitating electrodes 21, 22. Two resonators are connected in series and one resonator is a shunt resonator connected in parallel to the two serially connected resonators. The electric component 10 may comprise even more than three resonators. The metallic frame 3 is in electric contact to the electrode structures 2 of all resonators. Especially, parts of the metallic frame 3 form busbars of the electrodes 21, 22. The metallic frame 3 laterally surrounds the first sections 21a, 22a of all first and second electrodes 21, 22. In order to avoid short-circuits, the metallic frame 3 is not formed contiguously but is interrupted. The interruptions, however, are so small that only very little mold material will

penetrate into the cavity 5 when the electric component 10 is casted with the mold material.

In figure IB it can also be seen that the interconnect structures 6 are located on top of the metallic frame 3 in corners of the metallic frame 3. The upper two interconnect structure 6 are, for example, assigned to input and output terminals of the electric component 10, whereas the lower two interconnect structures 6 are connected to ground terminals.

In figure 1C the cross-sectional view through line CC' of figure IB is shown. It can be seen that the cover sheet 4 comprises openings, in which the interconnect structures 6 are located and electrically connected to the metallic frame

3.

In figure ID a plan view of the electric component 10 is shown. The same view as in figure IB is shown, but this time including the cover sheet 4. It can be seen that the cover sheet 4 completely covers the electrode structures 2 of the electric component 10 and extends over the entire electric component 10. In the regions of the interconnect structures 6, the cover sheet 4 comprises openings. The cover sheet 4 laterally completely surrounds each of the interconnect structures 6. Figures 2A and 2B show cross-sectional views of a second exemplary embodiment of an electric component 10. The

electric component 10 is similar to the electric component 10 of figure 1. In this exemplary embodiment, however, side surfaces 32 of the metallic frame 3 terminate flush with the side surfaces 12 of the electric component 10. For example, the side surfaces 32 of the metallic frame 3 also show traces of a material removal.

In figure 2C a plan view of the second exemplary embodiment of the electric component 10 is shown. Since in the second exemplary embodiment the metallic frame 3 is located closer to the side surfaces 12 of the electric component 10, also the interconnect structures 6 are located closer to the side surfaces 12. The interconnect structures 6 are placed in recesses of the cover sheet 4. In this plan view, regions of the electric component 10 between the interconnect structures 6 and the side surfaces 12 of the component 10 are free of the cover sheet 4.

This design is advantageous when mounting the electric component 10 and molding it with a molding material. In fact, as the interconnect structures 6 are located close to the side surfaces 12 of the component 10, they are exposed to thermal stress during operation of the component 10. The thermal stress is larger than in the case of figure 1, since in figure 1 the interconnect structures 6 are located closer to the center of the electric component 10. Due to the recesses in the cover sheet 4, which extend from the

interconnect structures 6 to the side surfaces 12, mold material can more easily penetrate into the interspace between the electric component 10 and a connection carrier and thus can provide additional mechanical support for the electric component.

Figure 3 shows a third exemplary embodiment of an electric component 10, again in a cross-sectional view. In principle, it is the same cross-section as in figure 1C. In contrast to figure 1C, however, the interconnect structures 6 are not solder bumps but are pillars or LGA pads, which are for example produced by electroplating on the metallic frame 3.

LGA pads are particularly advantageous as they provide large area support when mounting the electric component 10. The mold material, penetrating into the interspace between the electric component and the connection carrier, is not

necessarily needed in this case.

In all the exemplary embodiments of the electric component shown so far, the electrodes are interdigital electrodes forming SAW resonators. However, this is just an example and it is also possible that the electrode structures together with the piezoelectric layer form BAW resonators. In this case, the second electrodes are preferably located between the piezoelectric layer la and the support lb.

Figure 4 shows an exemplary embodiment of an electric device. The electric device in this case comprises the electric component 10 of figure 1. The electric component 10 is mounted on a connection carrier 8 with the top side 11 of the piezoelectric layer la facing the connection carrier 8. The connection carrier 8 comprises connection areas 81 for an electric connection. The connection areas 81 are, for

example, made from a metal, like A1 or Au. The interconnect structures 6 are soldered to the connection areas 81 and in this way the electric component 10 is

mechanically and electrically connected to the connection carrier 8. It can be seen that the interconnect structures 6 still project beyond the cover sheet 4 in the direction away from the top side 11. Due to this an interspace is formed between the connection carrier 8 and the cover sheet 4. If there would not be a mold material 7, the interconnect structures 6 would form the only mechanical support for the electric component 10. In the present case, however, a mold material 7 is placed on top of the electric component 10. The mold material 7 surrounds the electric component 10 and also penetrates into the intermediate space between the cover sheet 4 and the connection carrier 8. The mold material 7 is, for example, based on silicone and or epoxy and comprises thermally conductive particles. The mold material 7 encloses the interconnect structures 6 and contiguously extends from the connection carrier 8 to the cover sheet 4. In this way the mold material 7 provides additional mechanical support for the electric component 10 on the connection carrier 8.

The thermal stress occurring during the operation of the electric device is thus not solely carried by the

interconnect structures 6. Therefore, the lifetime of the whole electric device is increased.

In the present invention, the mold material 7 can penetrate in the intermediate space between the connection carrier 8 and the electric component 10, because the first sections 21a, 22a of the first and second electrodes 21, 22, which overlap with the active region of the resonators, are located in the cavity 5 and are protected by the cover sheet 4 and the metallic frame 3 from the mold material 7. The

interruptions in the metallic frame 3 are so small that the mold material 7 can hardly enter into the cavity 5. In this way it is guaranteed that the application of the mold

material 7 does not result in additional mass load on the first sections 21a, 22a of the electrodes 21, 22, which would influence the acoustic behavior of the resonators.

Figure 5A shows a first position in a method for

manufacturing a plurality of electric components. A

piezoelectric layer la on top of a substrate wafer lb is provided. On a top side 11 of the piezoelectric layer la a plurality of electrode structures 2, each comprising a first electrode 21 and a second electrode 22, are applied.

Additionally, metallic frames 3 are applied on the top side 11, wherein the metallic frames 3 surround the electrode structures 2.

In figure 5B a second position in the method is shown, in which the thickness of the metallic frames 3 is increased so that it becomes thicker than fingers of the electrodes 21,

22.

Figure 5C shows a third position in the method, in which a cover sheet layer 40 is placed on the top side 11 of the piezoelectric layer la. The cover sheet layer 40 is formed contiguously and without interruptions. The cover sheet layer 40, together with the metallic frames 3 and the piezoelectric layer la, forms a plurality of cavities 5, in which at least sections of the electrode structures 2 are located. For each first electrode 21 a first section 21a is placed in a cavity 5 and is spaced from the cover sheet layer 40.

In figure 5D a fourth position of the method is shown in which interconnect structures 6 are formed. The interconnect structures 6 are, for example, formed by structuring the cover sheet layer 40 with a photolithography process. During the structuring, openings in the regions of the metallic frame 3 are formed in the cover sheet layer 40. The

interconnect structures 6 are then applied in the regions of these openings directly onto the metallic frames 3.

In figure 5E a fifth position of the method is shown, where the composite comprising the substrate wafer lb, the

piezoelectric layer la, the cover sheet layer 40, the metallic frames 3 with the interconnect structures 6 and the electrode structures 2 is separated into a plurality of electric components 10. In figure 5E the separation planes are indicated as dashed lines. The separation planes extend through the cover sheet layer 40, the piezoelectric layer la and the substrate wafer lb.

Figures 6 shows a position in a second exemplary embodiment of a method for manufacturing electric components. Figure 6 is similar to figure 5E with the difference that the

separation planes 6 extend also through the metallic frames 3. With the method of figure 5, electric components as, for example, shown in figure 1 may be produced, whereas with the method of figure 6, electric components as shown in figure 2 may be produced.

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: la piezoelectric layer

lb support/substrate wafer

2 electrode structure

3 metallic frame

4 cover sheet

5 gas-filled cavity

6 interconnect structure

7 mold material

8 connection carrier

10 electric component

11 top side of the piezoelectric layer

12 side surface of the electric component

21 first electrode

21a first section of first electrode

22 second electrode

22a first section of second electrode 32 side surface of metallic frame

40 cover sheet layer

81 connection area