MICROMECHANICAL COMPONENT, SOUND TRANSDUCER DEVICE, AND METHOD FOR PRODUCING A MICROMECHANICAL COMPONENT

Abstract

A micromechanical component for a sound transducer device. The micromechanical component includes a substrate, a diaphragm, at least one piezoelectric element, and at least one electrical contact connection. The diaphragm can vibrate and is connected to the substrate. The at least one piezoelectric element is disposed between the diaphragm and the substrate and is connected to the diaphragm. The at least one piezoelectric element is designed to produce and/or detect vibrations of the diaphragm in the ultrasonic range. The at least one electrical contact connection is electrically connected to the at least one piezoelectric element. The micromechanical component can be connected, using flip chip technology, to a control circuit such that the at least one piezoelectric element can be electrically connected to the control circuit by means of the at least one electrical contact connection.

Claims

1-15. (canceled)

16. A micromechanical component for a sound transducer device, comprising: a substrate; a vibrating diaphragm connected to the substrate; at least one piezoelectric element arranged between the diaphragm and the substrate and connected to the diaphragm, wherein the at least one piezoelectric element is configured to produce and/or detect vibrations of the diaphragm in an ultrasonic range; and at least one electrical contact connection electrically connected to the at least one piezoelectric element, wherein the micromechanical component is configured to be connected, using flip chip technology, to a control circuit such that the at least one piezoelectric element can be electrically connected to the control circuit using the at least one electrical contact connection; wherein the substrate is connected to the diaphragm and/or the at least one piezoelectric element using a bonded connection, wherein a circumferential insulation trench is formed in the substrate around at least one bonded connection.

17. The micromechanical component according to claim 16, wherein the bonded connection includes at least one of aluminum and germanium.

18. The micromechanical component according to claim 16, wherein an electrically insulating material is formed on a surface of the substrate in a region of the insulation trench.

19. The micromechanical component according to claim 16, wherein the at least one electrical contact connection includes at least one of at least one solder ball and a first conductive path on a side of the substrate facing away from the diaphragm.

20. The micromechanical component according to claim 16, wherein at least one of the at least one piezoelectric element is electrically connected to at least one bonded connection using a second conductive path, wherein a material of the second conductive path includes aluminum.

21. The micromechanical component according to claim 16, wherein the at least one piezoelectric element is surrounded by a completely circumferential bond frame, wherein the bond frame connects the substrate to the diaphragm.

22. A sound transducer device, comprising: a micromechanical component, including: a substrate, a vibrating diaphragm connected to the substrate, at least one piezoelectric element arranged between the diaphragm and the substrate and connected to the diaphragm, wherein the at least one piezoelectric element is configured to produce and/or detect vibrations of the diaphragm in an ultrasonic range, and at least one electrical contact connection electrically connected to the at least one piezoelectric element, wherein the substrate is connected to the diaphragm and/or the at least one piezoelectric element using a bonded connection, wherein a circumferential insulation trench is formed in the substrate around at least one bonded connection; and a control circuit, wherein the micromechanical component is connected, using flip chip technology, to the control circuit, and wherein the at least one piezoelectric element of the micromechanical component is electrically connected to the control circuit using the at least one electrical contact connection.

23. A method for producing a micromechanical component, comprising the following steps: providing a substrate; forming a vibrating diaphragm connected to the substrate; providing at least one piezoelectric element arranged between the diaphragm and the substrate and connected to the diaphragm, wherein the at least one piezoelectric element is configured to produce and/or detect vibrations of the diaphragm in an ultrasonic range; and forming at least one electrical contact connection electrically connected to the at least one piezoelectric element, wherein the micromechanical component is configured to be connected, using flip chip technology, to a control circuit such that the at least one piezoelectric element can be electrically connected to the control circuit using the at least one electrical contact connection; wherein the substrate is connected to the diaphragm and/or the at least one piezoelectric element using a bonded connection, wherein a circumferential insulation trench is formed in the substrate around the bonded connection.

24. The method according to claim 23, wherein the forming of the vibrating diaphragm connected to the substrate includes the following steps: forming an etch stop layer on a surface of a carrier substrate; forming a diaphragm layer on the etch stop layer; and at least partially removing the carrier substrate, at least in part using etching methods.

25. The method according to claim 24, wherein the carrier substrate and the etch stop layer are removed only partially and are structured at least in an edge region.

26. The method according to claim 23, wherein the diaphragm is connected to the substrate using the bonded connection.

27. The method according to claim 26, wherein for bonding, a layer including aluminum is used on the diaphragm side, and a layer including germanium is used on the substrate side.

28. The method according to claim 27, wherein an electrically insulating material is formed on a surface of the substrate in a region of the insulation trench.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG. 1 shows a sound transducer device according to the related art.

[0053] FIG. 2 shows a further sound transducer device according to the related art.

[0054] FIG. 3 shows a sound transducer device according to one embodiment of the present invention.

[0055] FIG. 4 shows a sound transducer device according to a further embodiment of the present invention.

[0056] FIGS. 5-19 show schematic illustrations of intermediate products in a method for producing a micromechanical component according to an embodiment of the present invention.

[0057] FIG. 20 shows a micromechanical component according to one embodiment of the present invention.

[0058] In all figures, identical or functionally identical elements and devices are provided with the same reference signs. The numbering of method steps is used for reasons of clarity and is generally not intended to imply any particular temporal order. In particular, several method steps may also be carried out simultaneously.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0059] FIG. 3 shows a sound transducer device 200 comprising a micromechanical component 100. The micromechanical component 100 comprises a substrate 20, which is preferably formed from doped silicon, as well as a vibrating diaphragm 45 connected to the substrate 20.

[0060] The diaphragm 45 preferably consists of silicon and is preferably thinner than 30 micrometers. The diaphragm 45 can be thicker in sub-regions or can be equipped with one or more additional layers in sub-regions. Preferably, the diaphragm 45 is completely closed.

[0061] A gel 8 is formed above the diaphragm 45. Piezoelectric elements 47 are arranged between the diaphragm 45 and the substrate 20 and are connected to the diaphragm 45. The piezoelectric elements 47 form an array and are designed to produce and/or detect vibrations of the diaphragm 45 in the ultrasonic range. In the substrate 20, vias 23 are provided, which are connected to the piezoelectric elements 47.

[0062] In a connection region 11, the micromechanical component 100 is connected by means of a flip chip method to an ASIC chip 12, which functions as a control circuit. By means of the vias 23, the control circuit 12 can control the piezoelectric elements 47 and can receive measurement signals from the piezoelectric elements 47.

[0063] FIG. 4 shows a further sound transducer device 300. In this case, a carrier substrate 43 and an etch stop layer 44 are structured in or toward an edge region so that the gel 8 is enclosed from the lateral edge. The suspension of the diaphragm 45 takes place by bond regions 60.

[0064] In FIGS. 5 to 21, method steps of a production method for producing a micromechanical component 100 are illustrated.

[0065] As shown in FIG. 5, a substrate 20, preferably of doped silicon, is provided first. Optionally, a spacer layer 40 is applied to a first side (front side) of the substrate 20 and structured.

[0066] As shown in FIG. 6, a first component 41 of a bond layer is applied to the first side of the substrate 20 and structured. The first component 41 of the bond layer preferably consists at least in part of germanium.

[0067] As shown in FIG. 7, a cavern 42 is optionally etched into the first side of the substrate 20. The etching of the cavern 42 may preferably and particularly inexpensively take place together with the etching of the first component 41 of the bond layer.

[0068] As shown in FIG. 8, on a first side of a carrier substrate 43 (i.e., a second substrate) which faces the substrate 20 in the finished state, an etch stop layer 44 and a diaphragm layer 45 are formed. The carrier substrate 43 and the etch stop layer 44 are optional here. However, a very thin and homogeneous diaphragm 45 can be produced by the use of carrier substrate 43 and etch stop layer 44.

[0069] At least one of an oxide layer, a nitride layer, and an oxide nitride layer may be used as etch stop layer 44.

[0070] The diaphragm layer 45 may preferably consist of silicon. The diaphragm layer 45 is preferably between 1.5 and 30 micrometers thick.

[0071] As shown in FIG. 9, an insulation layer 46 is applied to a side (rear side) of the diaphragm layer 45 which faces the substrate 20 in the finished state.

[0072] As shown in FIG. 10, piezoelectric elements 47 are applied to the insulation layer 46. The present invention is not limited to a particular number of piezoelectric elements 47. Preferably, a plurality of piezoelectric elements 47 arranged in the shape of an array are applied.

[0073] The piezoelectric elements 47 each consist of a lower electrode, the actual piezo material, and an upper electrode. Preferably, the piezo material comprises lead zirconate titanate (PZT) and/or potassium sodium niobate (KNN).

[0074] Optionally, a further layer (for example LaNiO.sub.3) may be used between the lower electrode and the PZT layer for better growth.

[0075] Optionally, the piezoelectric element 47 can be encapsulated with a protective layer for protection from environmental influences. Preferably, tantalum nitride and/or silicon nitride and/or alumina is used for the protective layer.

[0076] As shown in FIG. 11, a second component 48 of a bond layer is applied to the insulation layer 46 and structured. Preferably, the material of the second component 48 of the bond layer comprises aluminum.

[0077] Furthermore, a conductive path (conductive layer) 49 is applied to the insulation layer 46 and structured. With this conductive path 49, an electrical connection is produced between individual bonding surfaces described below and the electrodes of the piezoelectric elements 47.

[0078] Preferably, the material of the conductive layer 49 comprises aluminum. Preferably, the same layer is used as the second component 48 of the bond layer and as the conductive path 49 between the bonding surfaces and the electrodes.

[0079] As illustrated in FIG. 12, the carrier substrate 43 with the layers located thereon is bonded to the substrate 20 with the layers located thereon. This produces bonded connections (bonding surfaces) 21 between the substrate 20 and the diaphragm 45 or bonded connections (bonding surfaces) 25 between the substrate 20 and the piezoelectric elements 47. The bonded connections 21 between the substrate 20 and the diaphragm 45 form a bond frame, which preferably completely surrounds and thereby protects the piezoelectric elements 47.

[0080] Preferably, an eutectic bonding method is used. In particular, an aluminum-germanium-containing bonding method is preferably used.

[0081] Preferably, a bonding method is used, which has a maximum temperature of 400 to 470° C.

[0082] Optionally, the substrate 20 is thinned from the second side (rear side). For this purpose, the substrate 20 is particularly preferably thinned to a thickness of 20 to 450 micrometers.

[0083] As illustrated in FIG. 13, for substrate thicknesses of between 40 and 450 micrometers, an at least partially insulating auxiliary layer 51 is preferably applied and has very narrow access holes 52 or slits in a region extending around individual bonded connections.

[0084] As illustrated in FIG. 14, from the second side (rear side) of the substrate 20, an insulation trench 50 extending around individual bonded connections is trenched into the first substrate so that vias 23 are formed. A very narrow trench that is narrower than 8 micrometers in the opening region is preferably etched for thicknesses of the substrate 20 between 20 and 100 micrometers.

[0085] Furthermore, with a trench process having a large lateral over-etching, a continuous and contiguous trench is produced underneath the structured circumferential region.

[0086] As illustrated in FIG. 15, an insulation layer 53 is applied to the auxiliary layer 51 and structured. The insulation trenches 50 previously created in the first substrate are sealed by this insulation layer 53.

[0087] Preferably, the insulation layer 53 is an oxide layer. Preferably, the insulation trenches 50 are sealed only on the rear side, and sealed cavities remain in the substrate 20 itself in the insulation trenches 50.

[0088] As illustrated in FIG. 16, one or more conductive paths (conducting layers) 54 are optionally deposited and structured.

[0089] As illustrated in FIG. 17, additional insulation layers 56 may be deposited and structured.

[0090] As illustrated in FIG. 18, solder balls 55 or solderable layers or solder bumps are deposited on the conductive paths 54.

[0091] The conductive paths 49, the bonding connections 25, the vias 23, the conductive paths 54, and the solder balls 55 form electrical contact connections.

[0092] As shown in FIG. 19, the carrier substrate 43 is thinned from a first side (front side).

[0093] In a technically particularly simple variant, a mechanical back-thinning takes place first and then a plasma or wet etching process that stops at the etch stop layer 44.

[0094] As shown in FIG. 20, the etch stop layer 44 can optionally also be subsequently removed. Thus, a very precisely defined thickness of the diaphragm 45 can be achieved very simply despite high removal.

[0095] FIG. 20 shows the micromechanical component 100 in the finished state.

[0096] The carrier substrate 43 and the etch stop layer 44 may also be only partially removed and may be structured at least in an edge region, in order to obtain a structure shown in FIG. 4, for example. Thus, only sub-regions are thinned, or regions are thinned differently. As a result, an edge region may be formed in order to achieve better gellability and/or to produce higher mechanical robustness.

[0097] From here onward, standard further processing of the micromechanical component 100 can take place. The substrate 20 is separated and the chips are soldered to the control circuit, such as an ASIC, by flip chip methods.

[0098] Preferably, the vias 23 (substrate punches) illustrated in FIG. 20 are not used to support the movable diaphragm 45. The cut line is only selected so that the functionality of the contact punches is better illustrated. Preferably, the suspension of the diaphragm 45 substantially takes place by the bond regions 60 illustrated in FIG. 4, which are not insulated from the substrate by insulation trenches. This allows very robust suspensions to be realized. The bond regions 25 with circumferential insulation trenches 50 are preferably arranged in this arrangement outside the active region of the diaphragm 45.

[0099] The present invention is not limited to the exemplary embodiments described. Thus, on the first side (front side) of the substrate 20, a further insulation layer may be deposited and structured. This may be provided in particular in the region in which the insulation trenches 50 are located. This insulation layer can thus serve as a trench stop layer in the production of the insulation trenches 50. The etch gas then cannot penetrate into and damage the cavity in which the piezoelectric elements 47 are arranged.