Microelectromechanical system comprising at least one contact column, method for producing the microelectromechanical system, and use of the microelectromechanical system

Abstract

The present invention relates to a microelectromechanical system (MEMS) (100) comprising a MEMS component (110) having a surface (120) and at least one contact column (1) which is provided on the surface (120) and has an upper face (2), the upper face (2) comprising a conductive material (4) and being designed and configured to supply the MEMS component (110) with a supply and / or signal voltage (130). The invention also relates to a method for producing a MEMS (100) of this kind having at least one contact column (1), and to the use of the MEMS (100) according to the invention in systems for interacting with fluids.

Description

[0001] R.415779

[0002] - 1 -

[0003] Description

[0004] title

[0005] Microelectromechanical system with at least one contact column, method for manufacturing the microelectromechanical system and use of the microelectromechanical system

[0006] Technical field

[0007] The present invention relates to a microelectromechanical system (MEMS) comprising a MEMS component with a surface and at least one contact column having a top surface, wherein the top surface comprises a conductive material and is designed and configured to supply the MEMS component with a supply and / or signal voltage. The invention further relates to a method for manufacturing such a MEMS with at least one contact column and to the use of the MEMS according to the invention in systems for interacting with fluids.

[0008] State of the art

[0009] Microelectromechanical systems (MEMS) are now integral components of numerous technical devices, particularly those that rely on fluid interaction, such as loudspeakers, microphones, pressure sensors, micropumps, and ultrasonic transducers. Developers of MEMS-based loudspeakers face the challenge of generating the highest possible sound pressure level (SPL) while simultaneously ensuring good sound quality.

[0010] SPL is defined as the decadic logarithm of the squared ratio between the RMS value of a measured sound pressure level and the reference value of 20 pPa commonly used in acoustics, and thus represents a measure of sound power. Devices exhibiting a high SPL can- R.415779

[0011] - 2 - can be operated with less power and still deliver the desired volume levels. In the case of sound quality, the THD factor (Total Harmonic Distortion) is a good indicator of the accuracy of an audio system. It is defined as the ratio of the sum of the power of all harmonic components to the power of the fundamental frequency, thus representing the existing harmonic distortion. Modern devices with a THD value of less than 0.1% are generally considered good audio systems, with high-quality systems usually aiming for a THD value of only about 0.01%.

[0012] MEMS loudspeakers known from the prior art are usually designed as planar systems comprising a vibrating diaphragm. By exciting the vibration of such a diaphragm, a fluid can be displaced or compressed vertically to the diaphragm plane, with the vibration exciting typically occurring via a piezoelectric or electrostatic effect, as shown, for example, in US 2021 / 0297787 A1.

[0013] A disadvantage of such systems is that the fluidically effective surface area, i.e., the area capable of displacing the fluid, is limited to the size of the individual membrane. Even if the membrane constitutes the majority of the MEMS component, the fluidically effective surface area would thus be dependent on the size of the MEMS component. Therefore, concepts were sought that incorporate multiple movable elements extending vertically in order to generate a larger overall surface area.

[0014] WO 2021 / 144400 A1 discloses a MEMS loudspeaker with a support and a diaphragm capable of oscillating in a vertical direction, wherein the diaphragm has two or more vertical sections, and at least one layer of an actuator material.

[0015] WO 2021 / 223886 A1 discloses a MEMS with a layered structure and a cavity arranged within the layered structure, which is fluidically coupled to the external environment via an opening in the layered structure. Furthermore, the MEMS comprises a movably arranged interaction structure for interacting with a fluid in a first MEMS layer, and an active structure mechanically coupled to the interaction structure in a second MEMS layer. The interaction structure, with its increased packing density, is intended to improve the efficiency of the MEMS, and the space required for the active structure is increased by separating it from the first layer. R.415779

[0016] - 3 -

[0017] DE 10 2019 203 914 B3 describes a MEMS with a substrate that has a cavity, wherein a movable layer arrangement is present in the cavity, which has a beam structure.

[0018] The prior art shows that elements formed perpendicular to the membrane can lead to an increased vibrating surface. However, if these perpendicular elements are too rigid, they can easily break off, especially during the manufacturing process. If they are too elastic, bonding methods, such as the thermosonic bonding method known to those skilled in the art, cannot be used. Furthermore, the overall resistance of the system increases with the increasing height of the perpendicular elements, and space is required on the surface of the MEMS component that is no longer available for other components.

[0019] Accordingly, the demand for MEMS that provide a robust, large, fluidically effective surface without negatively impacting overall resistance and surface space remains strong.

[0020] Disclosure of the invention

[0021] According to the invention, a microelectromechanical system (MEMS) is proposed, comprising a MEMS component with a surface and at least one contact column having a top surface located thereon, wherein the at least one contact column extends from the surface of the MEMS component in its height h to the top surface, wherein the top surface comprises a conductive material, and wherein the conductive material of the at least one contact column is designed and configured to supply the MEMS component with a supply and / or signal voltage.

[0022] A contact column according to the present invention is generally understood to be a body that extends vertically from the surface of the MEMS component to its top surface and is preferably freestanding. The contact column has a height h, a width b, and a depth t from the MEMS component to its top surface. The cross-sectional area Q of a contact column is not limited to a circle, as in a conventional column, but can have any geometry, such as, for example, R.415779.

[0023] - 4 -

[0024] A rectangle, an n-gon, an ellipse, a circle, an L-profile, a U-profile, a T-profile, a double-T-profile, or a hexagonal profile are all possible shapes. There are no limits to the design of the cross-section Q; all known motifs or imaginative shapes are conceivable. It is also possible for the cross-section of a contact column to change along its height h, meaning that it can increase or decrease in size or even change shape. The upper surface of a contact column according to the invention has a conductive material and serves to be connected to a power source in order to supply the MEMS component with a supply and / or signal voltage.

[0025] In configurations that have more than one contact column, these can vary in height h. x , their width b x and their depth t x They may differ and can also have a different cross-section Q xIn configurations with multiple contact columns, the cross-sectional geometries are preferably selected to interlock, thus creating a high packing density. In the case of multiple contact columns, these can also be stackable, meaning that one contact column is mounted on top of another, preferably separated by an insulating layer. The contact columns are preferably made of a conductive material, such as semiconductor materials like silicon, GaAs, or metals (e.g., aluminum, copper, gold). Alternatively, the contact columns can also be made of a non-conductive material, with a conductive layer located within or on the surface of the contact column transmitting the signal to the MEMS core.

[0026] In a preferred embodiment of the present invention, the conductive material of the top surface of a contact column is formed by at least one bond pad. The bond pad is preferably attached to the top surface of the contact column not by soldering, but by metallization, and has at least one bond wire, via which the supply and / or signal voltage can be applied. In preferred embodiments, the at least one bond pad occupies at least part of the top surface of the contact column, preferably not filling the entire top surface. Embodiments in which the at least one bond pad occupies at most half of the top surface of the contact column are preferred, and particularly preferably only a maximum of one quarter of the top surface of the contact column. In an alternative embodiment of the contact column according to the invention, the conductive material can also be formed by two or more bond pads. R.415779

[0027] - 5 -

[0028] Contact columns with a height h in the range of 5 pm to 5 mm, and especially in the range of 10 pm to 2 mm, have proven particularly suitable with regard to the interplay of strength, stiffness, and electrical resistance. Furthermore, widths b of the at least one contact column in the range of 5 pm to 500 pm, and especially in the range of 40 pm to 300 pm, have proven advantageous. Depth t of the at least one contact column in the range of 5 pm to 500 pm has proven effective, particularly in the range of 40 pm to 300 pm. Strength, stiffness, and electrical resistance can be further improved by selecting a suitable cross-section, and especially by adjusting the size of the cross-section.Possible cross-sections Q of the at least one contact column according to the invention include all cross-sections already discussed at the outset, such as rectangles, n-gons, ellipses, circles, L-profiles, U-profiles, T-profiles, double-T-profiles, hexagon profiles or any imaginative shapes.

[0029] In embodiments of the MEMS according to the invention, which have two or more contact columns, the first contact column has a cross-section Qi, the second contact column a cross-section Q2, the third contact column a cross-section Q3, etc. The cross-sections Q x , for example, for two contact columns, the cross-sections Qi and Q2 are designed so that they interlock.

[0030] Interlocking cross-sections, according to the invention, are understood to mean that the cross-section Qi of the first contact column has a geometry with recesses and protrusions that interact with the geometry of the cross-section Q2 of the second contact column, which also has recesses and protrusions, such that the protrusions of the cross-section Qi of the first contact column project into the recesses of the cross-section Q2 of the second contact column, and vice versa. For example, two semicircular cross-sections Qi and Q2 are conceivable, which interlock such that the arcs of the circles lie on opposite sides. In another possible embodiment, Qi is, for example, designed as an L-shape and Q2 as a rectangular shape that can abut the interior angle of the L-shape. The interlocking of the cross-sections should preferably result in the total cross-section of the contact columns being smaller than the sum of the individual cross-sections. R.415779

[0031] - 6 -

[0032] In embodiments of the contact columns according to the invention, in which the conductive material is formed by at least one bond pad, and thus the first contact column and the second contact column each comprise at least one bond pad on their respective upper surfaces, the cross-sections Qi and Q2 of the first and second contact columns interlock such that the bond pads of the first and second contact columns are arranged close together and form a bonding region. According to the invention, the bonding region thus comprises the bond pads of all interlocking contact columns.

[0033] In a further embodiment of the MEMS according to the invention, a first contact column has a height hi and a second contact column has a height h2, wherein the height hi is smaller than the height h2 and the second contact column furthermore has a cross-section Q that is variable in height h2 var with a maximum cross-section Qmax exhibits. This is under the maximum cross-section Q. max To understand the largest cross-section of the second contact column, the space for the second contact column on the MEMS component is thus defined by this cross-section Q. max determined. In the aforementioned embodiment, the first contact column is arranged on the second contact column such that the maximum cross-section Q max the second contact column remains, the cross-section Qi of the first column this cross-section Q max The first contact column is not overhanging at any point. The first contact column is separated from the second contact column by an insulating layer. According to the invention, the insulating layer can comprise plastics, technical ceramics, insulating paper, or glass. Other possible materials include air, vacuum, non-conductive fluids, silicon oxides, aluminum oxides, silicon nitrides, polymers, porous metal materials, and electrical or mechanical metamaterials.

[0034] According to the invention, a method for manufacturing a MEMS, in particular a MEMS according to the invention as described above, is further proposed, wherein the method according to the invention comprises wire bonding of the at least one contact column, in particular a plurality of contact columns, to the MEMS component. The wire bonding process step is familiar to those skilled in the art, with TS bonding (thermosonic ball-wedge bonding) being preferably used here.

[0035] Furthermore, a use of the MEMS according to the invention, in particular produced according to the method according to the invention, is proposed in systems designed and set up for interaction with fluids, in particular in R.415779.

[0036] - 7 -

[0037] Loudspeakers, microphones, pressure sensors, micropumps and ultrasonic transducers.

[0038] Advantages of the invention

[0039] The MEMS according to the invention, comprising at least one contact column, and in particular a plurality of contact columns, the cross-section of which is specifically selected, enables the creation of connection points for the power supply of the MEMS component that possess sufficient strength and stiffness to prevent breakage or delamination, particularly during the manufacturing process, which includes the wire bonding step. Furthermore, by increasing the cross-section of the individual contact columns, the overall resistance of the contact columns, which are tall compared to the MEMS component, can be reduced, thus reducing electrical losses in the system.The MEMS, comprising at least one contact column, can therefore provide a system that has an enlarged, fluidically effective surface area, particularly through its extension in the vertical direction, without compromising the stability of the system and, in particular, without leading to an increased overall resistance.

[0040] In the case of multiple contact columns, the cross-sections can be selected so that they interlock, which further improves the strength and stiffness of the contact columns and increases the packing density. Furthermore, this also allows the cross-section relevant for resistance to be increased. The interlocking of the cross-sections preferably also results in the total cross-section of the contact columns being smaller than the sum of the individual cross-sections. This ensures that the interlocking contact columns require less space on the corresponding MEMS component.

[0041] Particularly in configurations where the multiple contact columns have at least one bond pad on their upper surface, the interlocking cross-sections allow for a dense arrangement of the bond pads side by side, so that they form a common bonding area. This allows the individual bond pads on the respective contact columns to be made smaller and the distances between the terminals to be reduced. R.415779

[0042] - 8 -

[0043] Brief description of the drawings

[0044] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0045] They show:

[0046] Figure 1 shows a schematic side view of a first MEMS according to the invention;

[0047] Figure 2 shows a schematic side view and top view of a first contact column according to the invention, as well as a top view of two interlocking first contact columns according to the invention.

[0048] Figure 3 schematic top views of further interlocking contact columns according to the invention,

[0049] Figure 4 shows a schematic side view and top view of two contact columns according to the invention, as well as a top view of two alternative contact columns and

[0050] Figure 5 schematic top views of further contact columns according to the invention.

[0051] Embodiments of the invention

[0052] In the following description of embodiments of the invention, identical or similar elements are designated by the same reference numerals, and repeated descriptions of these elements are omitted in individual cases. The figures represent the subject matter of the invention only schematically.

[0053] The MEMS 100 according to Figure 1 shows a MEMS component 110 (indicated) with a surface 120 that has a first contact column 1 and a second contact column 12. The two contact columns 1, 12 have the same height h, extending from the surface 120 of the MEMS component 110 to the respective top surfaces 2, 14 of the contact columns 1, 12, as well as the same width b and the same depth t. In the embodiment shown, the two contact columns have a height h of 120, extending from the surface 120 of the MEMS component 110 to the respective top surfaces 2, 14 of the contact columns 1, 12, and the same width b and the same depth t. In the embodiment shown, the two contact columns have a height h of 120.

[0054] - 9 - clock columns 1, 12 rectangular cross-sections Qi, Q2 are arranged side by side. The upper surfaces 2, 14 comprise a conductive material 4, which here is designed as a bond pad 6, 16 and includes a bond wire 8. A supply and / or signal voltage 130 can be applied via the bond wire 8, which supplies the MEMS component 110 with energy.

[0055] Figure 2 shows a schematic side view 200 and a top view 202 of a first contact column 1 according to the invention, the MEMS component 110 being omitted for the sake of simplicity. In this embodiment, the contact column 1 has a cross-section Qi (not shown) with a right-angled U-profile. The upper surface 2 of the contact column 1 has a conductive material 4, which is also formed by a bond pad 6. It can be seen that the bond pad 6 only partially covers the upper surface 2 of the contact column 1; in particular, in the embodiment shown here, the bond pad 6 covers only about one-sixth of the upper surface 2 of the contact column 1. The top view 204 shows a previously described contact column 1, which is arranged with a second identical contact column 12 such that they interlock.The second contact column 12 also has a bond pad 16 on its upper surface 14, which likewise occupies only one-sixth of the upper surface 14 of the second contact column 12. The two bond pads 6, 16 are arranged so close together that they form a common bonding area 10.

[0056] The schematic top view 300 of Figure 3 shows the contact columns 1, 12 already described in Figure 2, with these further supplemented here by a third and fourth contact column 20, 26. The contact columns 1, 12, 20, 26 interlock in such a way that the legs of two contact columns (for example, 1 and 20) engage in the recess of another contact column (for example, 12). The bond pads 6, 16, 24, 30 are also arranged close together here and form a common bonding area 10.

[0057] The schematic top view 302 of Figure 3 shows an alternative arrangement of interlocking contact columns (for the sake of simplicity, the reference numerals for the contact columns, the top surface, and the bond pads are omitted here). These each have an L-shaped cross-section and form pairs by arranging the two L-shaped contact columns in a mirror-image configuration. The pairs are further arranged side by side as shown in R.415779.

[0058] - 10 - arranged so that the bond pads are also arranged close together and form a common bond area 10.

[0059] Figure 4 shows, in schematic side view 400 and schematic top view 402, an alternative embodiment of two contact columns 1 and 12, wherein the first contact column 1 is arranged on the second contact column 12. The first contact column 1 has a height hi and the second contact column 12 has a height h2, where the height h2 represents the maximum height of the second contact column 12, and where the height hi is less than the height h2. The second contact column 12 has a cross-section Qvar that varies with height h2, with a maximum cross-section Qmax. The first contact column 1 is arranged on the second contact column 12 such that the maximum cross-section Q maxthe second contact column 12 remains intact, meaning that the first contact column 1 does not protrude beyond the second contact column 12. In the illustrated variant, the first contact column 1 is separated from the second contact column 12 by an insulating layer 18. In this case as well, the bond pads 6, 16 form a common bonding area 10.

[0060] The design according to top view 404 differs from top view 402 in that the second contact column 12 has a different cross-section Q2.

[0061] Figure 5 shows schematic top views 500 to 518 of possible embodiments of contact columns according to the invention. For clarity, reference is made here to the reference numerals in the preceding figures. Combinations of contact columns with identical cross-sections, arranged simply side by side, are conceivable, as shown in top views 500, 502, and 504. It is also possible for contact columns with the same cross-section to be interlocked, as shown in top views 510, 5142, 516, and 518. Furthermore, combinations of contact columns with different cross-sections are also conceivable, as shown in top views 506 and 508. Despite having the same cross-sectional geometry, the bond pads can be attached at different locations on the surface, as shown in top views 500, 502, 504, and 510.

[0062] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, within the scope of R.415779

[0063] - 11 -

[0064] Within the specified area, a multitude of variations are possible, which fall within the scope of professional practice.

Claims

R.415779 - 12 - Claims 1. Microelectromechanical system (MEMS) (100) comprising a MEMS component (110) with a surface (120) and at least one contact column (1) with a top surface (2), wherein the at least one contact column (1) extends from the surface (120) of the MEMS component (110) in its height h to the top surface (2), wherein the top surface (2) comprises a conductive material (4), wherein the conductive material (4) of the at least one contact column (1) is designed and configured to supply the MEMS component (110) with a supply and / or signal voltage (130).

2. MEMS (100) according to claim 1, wherein the conductive material (4) of the top surface (2) is formed from at least one bond pad (6), wherein the at least one bond pad (6) comprises at least one bond wire (8), wherein the supply and / or signal voltage (130) can be applied via the at least one bond wire (8).

3. MEMS (100) according to claim 2, wherein the at least one bond pad (6) at least partially occupies the top surface (2) of the contact column (1), in particular, wherein the bond pad (6) occupies a maximum of half of the top surface (2) of the contact column (1), and more preferably a maximum of one quarter of the top surface (2) of the contact column (1).

4. MEMS (100) according to at least one of the preceding claims, wherein the height h of the at least one contact column (1) is in the range of 5 pm to 5 mm, in particular in the range of 10 pm to 2 mm.

5. MEMS (100) according to at least one of the preceding claims, wherein a width b of the at least one contact column (1) is in the range of 5 pm to 500 pm, in particular in the range of 40 pm to 300 pm. R.415779 - 13 - 6. MEMS (100) according to at least one of the preceding claims, wherein a depth t of the at least one contact column (1) is in the range of 5 pm to 500 pm, in particular in the range of 40 pm to 300 pm.

7. MEMS (100) according to at least one of the preceding claims, wherein the at least one contact column (1) has a cross-section Q, wherein the cross-section Q is formed as a rectangle, n-gon, ellipse, circle, L-profile, U-profile, T-profile, double-T-profile or hexagonal profile 8. MEMS (100) according to at least one of the preceding claims, comprising at least two contact columns (1 , 12), wherein the first contact column (1) has a cross-section Qi and the second contact column (12) has a cross-section Q2, wherein the cross-sections Qi and Q2 are configured to interlock.

9. MEMS (100) according to claim 8, wherein the first contact column (1) and the second contact column (12) each comprise at least one bond pad (6, 16) on their respective upper surfaces (2, 14), wherein the first contact column (1) and the second contact column (12) interlock such that the bond pads (6, 16) are arranged close together and form a bond area (10).

10. MEMS (100) according to at least one of claims 8 or 9, wherein the first contact column (1) has a height hi, wherein the second contact column (12) has a height h2 and a cross-section Q that is variable in height h2 var with a maximum cross-section Q max exhibits, wherein the height hi is less than the height h2, wherein the first contact column (1) is arranged on the second contact column (12) such that the maximum cross-section Q maxthe second contact column (12) is retained, wherein the first contact column (1) and the second contact column (12) are separated from each other by an insulating layer (18).

11. Method for producing a MEMS (100), in particular according to at least one of claims 1 to 10, wherein the method comprises: Wire bonding of the at least one contact column (1), in particular a plurality of contact columns (1 , 12), to the MEMS component (110). R.415779 - 14 - 12. Use of the MEMS (100) according to any one of claims 1 to 10, in particular manufactured according to a method according to claim 11, in systems designed and configured for interaction with fluids, in particular loudspeakers, microphones, pressure sensors, micropumps, and ultrasonic transducers.

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