MEMS LOUDSPEAKER DEVICE AND CORRESPONDING MANUFACTURING METHOD

Abstract

A MEMS loudspeaker device and a corresponding manufacturing method are described. The MEMS loudspeaker device includes a first substrate having a first front side and a first rear side, which includes a first rear side cavity, which is at least partially covered by a sound generation device; a second substrate having a second front side and a second rear side, which includes a second rear side cavity, which is covered by a first perforated plate device; the second rear side being bonded to the first front side in such a way that the second rear side cavity is situated above the sound generation device; and a second perforated plate device, which is attached above the first perforated plate device; at least one of the first perforated plate device and of the second plate device being elastically deflectable in such a way that a passage of sound of the sound generation device may be modulated by an interaction of the first perforated plate device and the second perforated plate device.

Claims

1. A MEMS loudspeaker device, comprising: a sound generation device; a first substrate having a first front side and a first rear side and including a first rear side cavity that is at least partially covered by the sound generation device; a first perforated plate device; a second substrate having a second front side and a second rear side and including a second rear side cavity that is covered by the first perforated plate device, wherein the second substrate is bonded to the first front side in such a way that the second rear side cavity is situated above the sound generation device; and a second perforated plate device attached above the first perforated plate device, wherein at least one of the first perforated plate device and the second perforated plate device is elastically deflectable in such a way that a passage of sound of the sound generation device may be modulated by an interaction of the first perforated plate device and the second perforated plate device.

2. The MEMS loudspeaker device as recited in claim 1, wherein: the first perforated plate device is a rigid backplate, and the second perforated plate device is an elastically deflectable closing device.

3. The MEMS loudspeaker device as recited in claim 1, wherein: the first perforated plate device is an elastically deflectable closing device, and the second perforated plate device is a rigid backplate.

4. The MEMS loudspeaker device as recited in claim 1, wherein: the first perforated plate device is an elastically deflectable closing device, and the second perforated plate device is an elastically deflectable closing device.

5. The MEMS loudspeaker device as recited in claim 1, wherein the second perforated plate device is formed on the second front side.

6. The MEMS loudspeaker device as recited in claim 1, further comprising: a third substrate including a third front side and including a third rear side cavity covered by the second perforated plate device, wherein the third front side is bonded to the second front side.

7. The MEMS loudspeaker device as recited in claim 1, wherein the sound generation device is one of a diaphragm device and a cantilever.

8. The MEMS loudspeaker device as recited in claim 7, wherein the diaphragm device includes ventilating holes provided preferably in an edge are of the diaphragm device, the holes being controllable for opening and closing.

9. The MEMS loudspeaker device as recited in claim 2, wherein at least one of the closing device and the sound generation device is elastically deflectable via one of a spring drive/piezo drive and a spring drive/electrostatic drive.

10. The MEMS loudspeaker device as recited in claim 2, wherein the backplate includes a variable degree of perforation that decreases from a center area of the backplate to an edge area of the backplate.

11. The MEMS loudspeaker device as recited in claim 1, further comprising: a fourth substrate to which the first rear side is bonded and which includes a through-opening that forms a fluid access to the first rear side cavity.

12. The MEMS loudspeaker device as recited in claim 1, which is mounted on a carrier substrate, wherein a chamber substrate surrounding the MEMS loudspeaker device is attached to the carrier substrate and a cover substrate is provided on the chamber substrate, the cover substrate including a sound outlet opening.

13. The MEMS loudspeaker device as recited in claim 12, wherein: the chamber substrate includes a central area in which the MEMS loudspeaker device is provided, and the chamber substrate includes an edge area that is fluidically connected to the first rear side cavity in the central area via a channel in the carrier substrate, and that is otherwise fluidically decoupled from the central area.

14. The MEMS loudspeaker device as recited in claim 12, wherein the chamber substrate includes an interior area, in which the MEMS loudspeaker device is provided, the carrier substrate including a through-opening that forms a fluid access to the first rear side cavity.

15. A method for manufacturing a MEMS loudspeaker device, comprising: forming a first substrate having a first front side and a first rear side, the first substrate including a first rear side cavity that is at least partially covered by a sound generation device; forming a second substrate having a second front side and a second rear side, the second substrate including a second rear side cavity that is covered by a first perforated plate device; bonding the second substrate to the first front side in such a way that the second rear side cavity is situated above the sound generation device; and forming a second perforated plate device that is attached above the first perforated plate device, wherein at least one of the first perforated plate device and the second perforated plate device is formed elastically deflectable in such a way that a passage of sound of the sound generation device may be modulated by an interaction of the first perforated plate device and the second perforated plate device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 schematically shows a cross-sectional view of a MEMS loudspeaker device according to a first specific embodiment of the present invention.

[0031] FIG. 2 schematically shows a top view of the shutter device of the MEMS loudspeaker device according to the first specific embodiment of the present invention.

[0032] FIG. 3 schematically shows a cross-sectional view of a MEMS loudspeaker device according to a second specific embodiment of the present invention.

[0033] FIG. 4 schematically shows a cross-sectional view of a MEMS loudspeaker device according to a third specific embodiment of the present invention.

[0034] FIG. 5 schematically shows a cross-sectional view of a MEMS loudspeaker device according to a fourth specific embodiment of the present invention.

[0035] FIG. 6 schematically shows a cross-sectional view of a MEMS loudspeaker device according to a fifth specific embodiment of the present invention.

[0036] FIG. 7 schematically shows a cross-sectional view of a MEMS loudspeaker device according to a sixth specific embodiment of the present invention.

DETAILED DESCRIPTION

[0037] In the figures, identical devices or functionally identical devices are identified by identical reference numerals.

[0038] FIG. 1 is a schematic cross-sectional view of a MEMS loudspeaker device according to a first specific embodiment of the present invention.

[0039] In FIG. 1, a MEMS loudspeaker device according to the first specific embodiment of the present invention, which includes a first substrate S1 having a first front side VS1 and a first rear side RS1 and a second substrate S2 having a second front side VS2 and a second rear side RS2, is identified in general by reference numeral 10.

[0040] First substrate S1 is a silicon substrate, for example, which includes a silicon carrier area 511 on top of which a silicon functional area S12 is mounted.

[0041] A first rear side cavity K1 is provided in silicon carrier area 511, which extends from first rear side RS1 to silicon functional area S12, and which has the function of a back volume. Diaphragm device M includes ventilating holes H1, which are provided preferably in its edge area and which are controllable preferably for opening and closing in a valve-like manner.

[0042] In the oscillating state, diaphragm device M moves along first movement direction B1. The functional elements of silicon functional area S12 are electrically controlled via electrical contact pads, identified herein, for example, by reference numerals P1, P2.

[0043] In the present example, the sound generation device is a diaphragm device M, it is, however, not limited thereto, but may also assume the shape of one or multiple oscillating beams or the like.

[0044] Second substrate S2 is an SOI substrate (silicon on insulator), for example. Second substrate S2 includes a silicon carrier area S21, a silicon oxide area S22, a first silicon functional area S23, a silicon oxide compound area S24 and a second silicon functional area S25.

[0045] Second substrate S2 includes a second rear side cavity K2, which extends from second rear side RS2 to first silicon functional area S23.

[0046] A backplate BP is formed above second rear side cavity K2 in first silicon functional area S23, which is essentially fixed and includes ventilating holes H2. It should include a preferably minimal flow resistance for the sound waves of diaphragm device M, and preferably a high perforation density in the area of the greatest deflection of the diaphragm device, i.e., in its central area.

[0047] Second substrate S2 is bonded with its second rear side RS2 to first front side VS1 of first substrate S1 with the aid of bond connections V1, V2 in such a way that second rear side cavity K2 is situated above diaphragm device M, preferably resulting in a preferably large sound passage.

[0048] In second silicon functional area S25, a plate-shaped shutter device or closing device SH is formed above backplate BP, which also includes ventilating holes H3, and which is elastically deflectable in its plate plane in a second movement direction B2. The deflection takes place via a drive area AB, which will be explained in greater detail below with reference to FIG. 2. Second movement direction B2 is selected essentially perpendicular to first movement direction B1 in such a way that a passage of sound of diaphragm device M may be modulated by an interaction of backplate BP and closing device SH, so that the loudspeaker function is implementable with the aid of acoustic beats. Electric contact pads, identified herein by P3, P4, for example, are also provided for driving closing device SH.

[0049] Since it is not possible in practice to implement a pure movement in the plate plane of closing device SH, stop bumps, identified herein by reference sign BU, may also be provided for safety reasons, both on backplate BP and on closing device SH.

[0050] Although closing device SH is located above backplate BP in the present example, the order may also be reversed, since only the possibility of acoustic modulation via the movement along second movement direction B2 is relevant for the functioning of the loudspeaker device.

[0051] During operation as a loudspeaker, a frequency of several hundred kHz is applied to diaphragm device M, for example, and this frequency is modulated with the same frequency +20 kHz or −20 kHz via closing device SH, the range of 0-20 kHz corresponding exactly to the acoustic audible range. It is also possible, of course, to operate closing device SH at a constant frequency and to operate diaphragm device M frequency modulated.

[0052] FIG. 2 is a schematic top view of the shutter device of the MEMS loudspeaker device according to the first specific embodiment of the present invention.

[0053] In FIG. 2, shutter device or closing device SH is depicted, which in this example 4 includes plate-shaped elastically suspended oscillating weights M1, M2, M3 and M4, which are operated in phase opposition as depicted by the arrows. Oscillating weights M1, M2, M3, M4 are each connected on both sides via webs ST to a corresponding spring drive/piezo drive FP1, FP2, FP3, FP4, each of which ensures the deflection in the plate plane out of the rest position, the return force being generated by the corresponding springs.

[0054] Stop bumps BU′ on oscillating weights M1, M2, M3 and M4 ensure that undesirable movements perpendicular to the second movement direction B2 are unable to cause any damage.

[0055] FIG. 3 is a schematic cross-sectional view of a MEMS loudspeaker device according to a second specific embodiment of the present invention.

[0056] In FIG. 3, a MEMS loudspeaker device according to the second specific embodiment, in which the structure and function of first substrate S1 are the same as described above in the first specific embodiment, is identified in general by reference numeral 10a.

[0057] In this specific embodiment, a second substrate S2′ having a second rear side cavity K2′ is also a SOI substrate including a silicon carrier area S21′, a silicon oxide area S22′ and a silicon functional area S23′. In contrast to the first specific embodiment, a closing device SH′ is provided in silicon functional area S23′, which is movable in second movement direction B2 and which includes ventilating holes H3′ above rear side cavity K2′, which extend from second rear side RS2′ to silicon functional area S23′. Second rear side RS2′ is bonded to first front side VS1 with the aid of bond connections V1, V2, similar to the first specific embodiment.

[0058] Electrical contact pads are used to drive closing device SH′, which is identified herein, for example, by reference numeral P3′. The function of closing device SH′ is identical, as is described above with reference to the first specific embodiment. The drive area is identified herein by reference sign AB′.

[0059] In the second specific embodiment, a third substrate S3 is also provided, which includes a third front side VS3 and a third rear side RS3.

[0060] Third substrate S3 in this example is also a SOI substrate including a silicon carrier area S31, a silicon oxide area S32 and a silicon functional area S33. In silicon functional area S33, an essentially rigid backplate BP′ including ventilating holes H2′ is provided, which interacts with closing device SH′ as in the first specific embodiment described above.

[0061] Third front side VS3 is bonded to second front side S2′ of second substrate S2′ with the aid of bond connections V3, V4, so that closing device SH′ and backplate BP′ lie on top of each other.

[0062] By implementing third rear side cavity K3, it is possible to achieve a more directed sound emission in this second specific embodiment. This third rear side cavity K3 is, of course, optional.

[0063] In the second specific embodiment as well, which uses three substrates S1, S2′, S3, it is possible to switch the order of closing device SH′ and backplate BP′, i.e., backplate BP′ is provided in second substrate S2′ and closing device SH′ is provided in third substrate S3.

[0064] FIG. 4 is a schematic cross-sectional view of a MEMS loudspeaker device according to a third specific embodiment of the present invention.

[0065] In FIG. 4, a MEMS loudspeaker device according to the third specific embodiment, in which the structure and function of first substrate S1 and of second substrate S2′ are the same as described above in the second specific embodiment, is identified in general by reference numeral 10b.

[0066] In contrast to the second specific embodiment, a second closing device or shutter device SH″ including ventilating holes H3″ above a third rear side cavity K3′ is provided in the third specific embodiment in third substrate S3′ having a third front side VS3′ and a third rear side RS3′, which is a SOI substrate and includes a silicon carrier area S21′, a silicon oxide area S22′ and a silicon functional area S23′. In this specific embodiment, first closing device SH′ and second closing device SH″ are operated in phase opposition, as is indicated by arrows B2′ and B2″.

[0067] As a result of the operation in phase opposition of first closing device SH′ and second closing device SH″, the mass to be driven is reduced. The individual elements of closing devices SH′ and SH″ may be mechanically coupled to one another via springs (not shown), in order to ensure an identical drive frequency and to prevent a divergence of the phases.

[0068] FIG. 5 is a schematic cross-sectional view of a MEMS loudspeaker device according to a fourth specific embodiment of the present invention.

[0069] In contrast to the third specific embodiment, a fourth substrate S4, for example, a silicon substrate, is provided below first substrate S1 in MEMS loudspeaker device 10c according to the fourth specific embodiment, to which first rear side RS1 of the first substrate is bonded with the aid of bond connections V5, V6. Fourth substrate S4 includes a through-opening LO in the area of first rear side cavity K1, which creates an external fluid access.

[0070] FIG. 6 is a schematic cross-sectional view of a MEMS loudspeaker device according to a fifth specific embodiment of the present invention.

[0071] In the fifth specific embodiment, MEMS loudspeaker devices 10, 10a, 10b, 10c described above are depicted in the packaged state. Here, the packaged loudspeaker device in general bears reference numeral 1a. For this purpose, any one of the MEMS loudspeaker devices 10, 10a, 10b, 10c is mounted on a carrier substrate TS with mounting pads SP. Attached to carrier substrate TS is a chamber substrate KS surrounding the MEMS loudspeaker device, a cover substrate DS being provided on chamber substrate KS, which includes a sound outlet opening SA for sound waves SW to exit above the MEMS loudspeaker device.

[0072] Chamber substrate KS includes a central area R1, in which MEMS loudspeaker device 10, 10, 10b, 10c is provided, as well as an edge area R2, which is fluidically connected to first rear side cavity K1 in central area R1 via a channel CH in carrier substrate TS, and is otherwise fluidically decoupled from central area R1. For this purpose, the channel includes a first opening OL and a second opening OC. Edge area R2 serves as back volume.

[0073] Additional components may be mounted in edge area R2 such as, for example, an ASIC with reference sign AC. It is also possible to provide additional components and corresponding electrical connections.

[0074] FIG. 7 is a schematic cross-sectional view of a MEMS loudspeaker device according to a sixth specific embodiment of the present invention.

[0075] In the sixth specific embodiment, the packaged loudspeaker device in general bears the reference numeral 1b. Here, the carrier substrate is identified by reference sign TS' and includes a through-opening KA as a fluid access for first rear side cavity K1 of MEMS loudspeaker device 10, 10a, 10b and 10c. The chamber substrate is identified by reference sign KS' and is designed in such a way that it includes a single interior space R0, in which MEMS loudspeaker device 10, 10a, 10b and 10c is mounted.

[0076] Cover substrate DS' includes, as in the fifth specific embodiment, a sound outlet opening SA for the passage of sound waves SW of MEMS loudspeaker device 10, 10a, 10b and 10c. The packaged loudspeaker device designed in this way is mountable on arbitrary carriers with the aid of mounting pads SP.

[0077] Although the present invention has been described based on preferred exemplary embodiments, it is not limited thereto. The cited materials and topologies, in particular, are merely exemplary and not limited to the explained examples.

[0078] Although the closing devices in the specific embodiments described above include multiple oscillating weights, it is of course possible in each case to provide one closing device, which includes only one single oscillating weight.

[0079] It should also be mentioned that it is possible, of course, to construct assemblies or arrays based on the loudspeaker devices described above, which include a plurality of sound generation devices or diaphragm devices arranged in a matrix, in each case, with closing devices and backplates located above. Either individual or multiple or all of the diaphragm devices or closing devices may each share a common cavity or rear side cavity. Nor is the present invention limited to the number of closing devices or backplates stacked on top of one another.