MEMS device and method of manufacturing a MEMS device

Abstract

The invention relates to a MEMS device and a method of manufacturing a MEMS device. The MEMS device (10) comprises a functional element (12) fluidly connected to the environment, where the functional element (12) comprises a total surface region (50) having at least a first sub-section (50-1) and an adjacent second sub-section (50-2), where the functional element (12) is less susceptible to surface contamination (48) in the first sub-section (50-1) of the total surface region (50) than in the second sub-section (50-2) of the total surface region (50); and wherein the first sub-section (50-1) of the total surface area (50) has a first surface structure (52) having a higher liquid wettability than a second surface structure (54) of the second sub-section (50-2) of the total surface area (50).

Description

Technical Field

[0001] Embodiments of this disclosure relate to microelectromechanical systems (MEMS) based devices and methods for manufacturing MEMS-based devices. More specifically, embodiments relate to the field of MEMS sensors or MEMS actuators, such as MEMS acoustic transducers (MEMS microphones or MEMS speakers), MEMS pressure sensors, MEMS gas sensors, MEMS environmental sensors, or MEMS devices having an environmentally robust design achieved by providing local hydrophobic gradients or differences on surface regions of functional elements of the MEMS device. Furthermore, embodiments also relate to combinations of hydrophilic and hydrophobic surface coatings (surface structures) for functional elements of MEMS devices (e.g., MEMS acoustic transducers (MEMS microphones or MEMS speakers)) to increase environmental robustness, and methods for manufacturing such MEMS devices. Background Technology

[0002] MEMS-based devices are becoming increasingly important in sensing physical, mechanical, chemical, and environmental parameters in the ambient atmosphere. MEMS devices (such as MEMS acoustic transducers or MEMS pressure sensors) essentially function as transducer elements that convert static pressure changes or acoustic pressure waves into analog electrical signals in response to the deflection of the membrane in the MEMS device.

[0003] When designing MEMS devices with (deflectable) functional elements that are fluidly connected to the environment, it is generally desirable to specify the MEMS device as immersion-resistant. Immersion-resistant generally means that immersion of the MEMS device, and especially its functional elements, in liquids (e.g., deionized (DI) water, distilled water, tap water, oil, and other liquids) will not cause a deterioration in the operating characteristics of the functional elements. However, due to surface drying treatment after the surface areas of the functional elements have been exposed to liquids, surface contamination from liquid residues or contaminants (e.g., water residues in the form of salt, chalk, or other types of particulate matter) can cause a significant deterioration in the (electromechanical) operating characteristics of the functional elements of the MEMS device.

[0004] Therefore, there is a continuous need in the field of MEMS devices to realize MEMS devices with functional elements that are fluidly connected to the environment, for example, because surface contamination caused by the surface drying of the surface area of ​​the functional element after exposure to liquid (e.g., tap water) does not lead to a significant deterioration of the (electromechanical) operating characteristics of the functional element (e.g., sensitivity, noise, signal-to-noise ratio (SNR), angular frequency, flexibility, etc.).

[0005] This need can be met by a MEMS device manufactured according to the MEMS device of independent claim 1 and a MEMS device manufactured according to the manufacturing method of independent claim 12.

[0006] Furthermore, specific embodiments of the MEMS device are defined in the dependent claims. Summary of the Invention

[0007] According to one embodiment, a MEMS device includes a (deflectable) functional element in fluid communication with the environment, wherein the functional element includes a total surface region having at least a first sub-segment and an adjacent second sub-segment, wherein the functional element is (configured) to be less susceptible to surface contamination in the first sub-segment of the total surface region than in the second sub-segment of the total surface region, and wherein the first sub-segment of the total surface region has a first surface structure having a higher liquid wettability than the second surface structure of the second sub-segment of the total surface region.

[0008] According to one embodiment, the total surface area of ​​the functional element is configured such that surface contamination of the first sub-segment caused by surface drying after exposure to liquid may result in a smaller degradation of the electrical or mechanical properties of the functional element compared to the corresponding surface contamination of the second sub-segment.

[0009] According to one embodiment, the total surface area includes morphological differences or gradients in the liquid contact angle over the total surface area, resulting in different liquid wettability in the first sub-segment and the second sub-segment. In this specification, the term "morphology" refers to the geometry and physical and chemical properties of the (technical) surface structure (e.g., nanostructure or microstructure) of a functional element.

[0010] According to one embodiment, a first sub-segment of the total surface area is configured to form a liquid collection area during a liquid drying event of the total surface area of ​​the functional element. A second sub-segment of the total surface area is configured to form a liquid repulsion area during a liquid drying event of the total surface area of ​​the functional element.

[0011] According to different embodiments, in the context of this disclosure, the term "less susceptible" (less sensitive to) surface contamination, for example, due to surface drying after exposure to a liquid, generally means that surface contamination of the first sub-segment of the total surface area results in a lower degradation of the electrical or mechanical properties (e.g., operating characteristics) of the functional element compared to (comparative or equivalent) surface contamination (e.g., due to surface drying after exposure to a liquid) of the second sub-segment of the total surface area.

[0012] The (electromechanical) operating characteristics of functional elements include, for example, the sensitivity of the functional element, membrane flexibility, achievable SNR, internal resistance, parasitic capacitance, etc.

[0013] According to one embodiment, a manufacturing method includes the steps of: providing a MEMS device having functional elements that are fluidly connected to an environment, wherein the functional elements include a total surface region having a first sub-segment and an adjacent second sub-segment; and providing (e.g., forming) a first surface structure on the first sub-segment of the total surface region, the first surface structure having a higher liquid wettability than a second surface structure on the second sub-segment of the total surface region.

[0014] According to one embodiment, a manufacturing method includes the step of forming a (morphological) difference or gradient of liquid contact angle over a total surface area to provide a first sub-segment and a second sub-segment with different liquid wettability.

[0015] The inventors of this disclosure have observed and recognized that immersing a MEMS device having deflectable functional elements in a fluidly connected environment into a liquid (e.g., tap water) can lead to a significant deterioration of the electrical or mechanical properties (e.g., operational properties) of the functional elements, thereby resulting in a significant deterioration of the electrical or mechanical properties of the MEMS device.

[0016] After a functional element is exposed to a liquid (e.g., tap water), surface drying of the functional element can lead to the accumulation or deposition of liquid residues on the surface areas of the functional element in a MEMS device. This surface contamination of the functional element due to liquid residues or contaminants (e.g., water residues in the form of salt, chalk, or other particulate matter) resulting from surface drying after exposure to a liquid (e.g., tap water) can, for example, provide leakage between electrically isolated sections of the functional element, leakage between (electrically isolated) conductive traces on the surface areas of the functional element, leakage between the functional element and the substrate (or other conductive structures of the MEMS device), mechanical obstruction of through-holes (vents) of the functional element, or other degradation of the (electro- or mechanical) operating characteristics of the functional element. The functional element may include a deflectable film of a MEMS sensor, MEMS actuator, or MEMS environmental sensor, such as a deflectable film structure of an acoustic transducer (microphone and / or speaker) or MEMS pressure sensor. Therefore, the functional element may include a transducer (e.g., sensing and / or actuating) MEMS element.

[0017] The inventors of this disclosure further recognized, for example, from optical micrographs, that a high number or large area of ​​contamination on functional elements does not necessarily lead to a high failure rate of functional elements in MEMS devices. Only contamination at specific "critical" areas of the functional elements (the second sub-segment of the total surface area) actually causes damage to the functional elements of the MEMS device, or a significant deterioration of the (electromechanical) operating characteristics of the functional elements, or even damage or malfunction (functional failure) of the functional elements. Such deterioration or damage can be caused by electrical leakage between (electrically separated) surface areas of the functional elements or between the surface area of ​​the functional elements and another conductive structure of the MEMS device, where, as a result of electrical leakage, failures in the SNR of the MEMS device may occur. However, contamination does not cause failure (damage or malfunction) on most of the surface area (e.g., the membrane structure) of the functional elements (the first sub-segment), making it necessary only to keep specific areas (the second sub-segment) of the surface area of ​​the functional elements "clean" to prevent surface contamination, for example, due to surface drying treatment after exposure to a liquid (e.g., tap water).

[0018] Therefore, a first sub-segment of the total surface of the functional element has a first surface structure that has higher liquid wettability than a second surface structure of a second sub-segment of the total surface area of ​​the functional element. Thus, the hydrophobicity of the materials involved in the functional element of the MEMS device can be controlled to guide liquid, along with contaminants therein (during a drying process after the functional element has been exposed to the liquid), to different (predetermined) drying zones on the surface area of ​​the functional element. Therefore, the critical surface area of ​​the functional element (the second sub-segment) can remain clean (free from contaminants in the liquid) from contaminants in the liquid.

[0019] Therefore, according to this disclosure, the functional elements of a MEMS device may include a liquid contact angle gradient or a liquid contact angle gradient difference (or liquid contact angle gradient / difference) along its total surface area, wherein the more hydrophilic portion of the surface area of ​​the functional element, i.e., a first sub-segment of the total surface area (having a second surface structure with higher liquid wettability than a second sub-segment of the total surface area), acts as or serves as a “water / liquid collection” area during the drying process of the functional element after the surface area of ​​the functional element has been exposed to a liquid (e.g., tap water).

[0020] Therefore, this method allows the fabrication of MEMS devices (e.g., MEMS acoustic transducers or other MEMS sensors or MEMS actuators) with enhanced environmental robustness levels, particularly for water immersion and particulate or contamination-induced and electrical leakage due to surface drying after exposure to liquids, wherein the MEMS element has a functional element with a specifically selected sub-segment of the total surface area of ​​the functional element, which has higher liquid wettability than the remaining sub-segments of the total surface area of ​​the functional element.

[0021] According to this embodiment, the functional elements of the MEMS device have a liquid contact angle gradient or difference (or water contact angle (WCA) gradient or difference) along their surface regions, wherein the more hydrophilic portion of the surface region (the first sub-segment) acts as a "liquid collection" region (water collection region) during the drying process. According to one embodiment, during a liquid drying event of the total surface region of the functional element, a second sub-segment of the total surface region can form a liquid "repulsion" region.

[0022] Therefore, the MEMS device according to this disclosure allows for the construction of liquid-resistant (water-resistant) MEMS devices (e.g., MEMS microphones) without the need for an external environmental barrier. Consequently, the module cost of liquid-resistant (water-resistant) MEMS devices can be significantly reduced.

[0023] Enhanced liquid (water) immersion resistance of MEMS devices can eliminate the need for external environmental barriers, or automatically allow the use of less liquid (water) resistant external environmental barriers. In both cases, this will enhance the operational characteristics of MEMS devices (e.g., system SNR) and reduce the cost of the resulting MEMS device modules. Attached Figure Description

[0024] Embodiments of this disclosure are described in more detail below with reference to the accompanying drawings, in which:

[0025] Figure 1A A schematic cross-sectional view of a MEMS device according to an embodiment of the present disclosure is shown;

[0026] Figure 1B -C illustrates a schematic cross-sectional view and a schematic top view (plan view) of a MEMS device in the form of a MEMS microphone according to an embodiment of the present disclosure;

[0027] Figure 2 An exemplary schematic flowchart of a method for manufacturing a MEMS device according to an embodiment of the present disclosure is shown;

[0028] Figure 3A -D shows a schematic cross-sectional view of a portion of the surface region of a functional element of a MEMS device according to an embodiment of the present disclosure during a drying process following exposure to a liquid;

[0029] Figure 4A A schematic cross-sectional view of a MEMS device with a surface structure having functional elements according to another embodiment of the present disclosure is shown.

[0030] Figure 4B An enlarged schematic cross-sectional partial view of a MEMS device according to an exemplary embodiment of a surface structure having functional elements in accordance with another embodiment of the present disclosure is shown;

[0031] Figure 5A -C shows an exemplary schematic flowchart of an embodiment of a method 100 for providing a MEMS device having functional elements having different (first and second) surface structures over a total surface area, according to an embodiment of the present disclosure.

[0032] Figure 6A -B shows a schematic cross-sectional view and an enlarged schematic partial cross-sectional view of an exemplary embodiment of a MEMS device with a surface structure having functional elements according to another embodiment of the present disclosure;

[0033] Figure 7A -C shows a schematic cross-sectional view and an enlarged schematic partial cross-sectional view of an exemplary embodiment of a MEMS device with a surface structure having functional elements according to another embodiment of the present disclosure;

[0034] Figure 8A -C illustrates a schematic cross-sectional view of an exemplary embodiment of a MEMS device having a surface structure of functional elements according to another embodiment of the present disclosure, an enlarged schematic partial cross-sectional view of the surface structure of the functional elements, and a schematic top view (planar view) of the surface structure of the functional elements.

[0035] Figure 9A -C illustrates a schematic cross-sectional view of an exemplary embodiment of a MEMS device having a surface structure of functional elements according to another embodiment of the present disclosure, an enlarged schematic partial cross-sectional view of the surface structure of the functional elements, and a schematic top view (planar view) of the surface structure of the functional elements.

[0036] Figure 10A -D illustrates an exemplary schematic flowchart of a method for manufacturing the surface structure of a functional element of a MEMS device according to another embodiment of the present disclosure;

[0037] Figure 11 A schematic cross-sectional view of a MEMS device with a surface structure having functional elements according to another embodiment of the present disclosure is shown.

[0038] Figure 12A schematic cross-sectional view of a MEMS device with a surface structure having functional elements according to another embodiment of the present disclosure is shown.

[0039] Figure 13A -C illustrates an exemplary schematic flowchart of a method for manufacturing the surface structure of a functional element of a MEMS device according to another embodiment of the present disclosure;

[0040] Figure 14A -E illustrates an exemplary schematic flowchart of a method for manufacturing the surface structure of a functional element of a MEMS device according to another embodiment of the present disclosure;

[0041] Figure 15A -D illustrates an exemplary schematic flowchart of a method for manufacturing the surface structure of a functional element of a MEMS device according to another embodiment of the present disclosure;

[0042] Figure 16A -C illustrates a schematic cross-sectional view of a MEMS device according to an exemplary embodiment of a surface structure having functional elements, based on another embodiment of this disclosure; and

[0043] Figure 17A -E illustrates an exemplary schematic flowchart of a method for manufacturing the surface structure of a functional element of a MEMS device according to another embodiment of the present disclosure;

[0044] Before discussing this embodiment in more detail using the accompanying drawings, it should be noted that in the drawings and description, the same elements and elements having the same function and / or the same technical or physical effect are generally provided with the same reference numerals or identified by the same names, such that the descriptions of these elements and their functions illustrated in different embodiments can be interchanged or applied to each other in different embodiments. Detailed Implementation

[0045] In the following description, embodiments are discussed in detail; however, it should be understood that the embodiments provide many applicable concepts that can be embodied in various fields of MEMS devices (e.g., MEMS sensors or actuators, or dual-film MEMS sensors or actuators). The specific embodiments discussed are merely illustrative of specific ways of implementing and using the concepts and do not limit the scope of the embodiments. In the following description of the embodiments, the same or similar elements having the same function are provided with the same reference numerals or are identified by the same name, and repeated descriptions of elements provided with the same reference numerals or identified by the same name are generally omitted. In the following description, several details are set forth to provide a more thorough explanation of embodiments of the invention.

[0046] However, those skilled in the art will understand that other embodiments can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the examples described herein. Furthermore, features of the different embodiments described herein can be combined with each other unless specifically indicated otherwise.

[0047] It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. Conversely, when an element is referred to as "directly" connected ("connected" or "coupled") to another element, there are no intermediate elements. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" to "directly between," "adjacent" to "directly adjacent," and "on" to "directly on," etc.).

[0048] For ease of description of different embodiments, the figures include a Cartesian coordinate system x, y, z, where the xy plane corresponds to (i.e., parallel to) the first primary surface region of the substrate or the (un-deflected) surface region of the functional element (reference plane / xy plane), where the direction perpendicularly upward relative to the reference plane (xy plane) corresponds to the "+z" direction, and where the direction perpendicularly downward relative to the reference plane (xy plane) corresponds to the "-z" direction. In the following description, the term "lateral" means a direction parallel to the x and / or y directions (i.e., parallel to the xy plane), and the term "vertical" means a direction parallel to the z direction.

[0049] In the following description, the thickness of a component typically indicates its vertical dimension. Different components are not necessarily drawn to scale in the accompanying drawings. Therefore, the dimensions shown for different components are not necessarily drawn to scale.

[0050] In the description of the embodiments, the terms and text paragraphs placed in parentheses next to the described elements or functions should be understood as further explanations, exemplary configurations, exemplary additions and / or exemplary substitutions of the described elements or functions.

[0051] Figure 1A A schematic cross-sectional view of a MEMS device 10 according to an embodiment of the present invention is shown. The MEMS device 10 can be arranged as an SBP (single backplane) structure, such as a single backplane or a single-film acoustic transducer 10.

[0052] Figure 1B -C shows a schematic cross-sectional view and a schematic top view (planar view) of a MEMS device 10 according to another embodiment of the present disclosure. Figure 1B-C and the following figures exemplarily illustrate a MEMS device 10 in the form of a dual-film MEMS microphone or a hermetically sealed dual-film (SDM) MEMS microphone according to various embodiments of the present disclosure. However, the following description of the MEMS device 10 is equivalent to any MEMS sensor, MEMS actuator, or MEMS environmental sensor, wherein the MEMS device 10 includes a (deflectable) functional element 12 (e.g., having a membrane structure 14) in fluid communication with the environment. According to embodiments, the functional element 12 of the MEMS device 10 (MEMS sensor or MEMS actuator) may be part of a transduction operation based on a capacitive, piezoelectric, or piezoresistive transduction (sensing or actuation) mechanism or an optical sensing mechanism.

[0053] according to Figure 1A In the embodiment shown in -C, the MEMS device 10 includes a functional element 12 that is fluidly connected (communicating) with the environment "E". The functional element 12, which may include a deflectable structure 14 (e.g., a membrane structure), includes a total surface region 50 having at least a first sub-segment 50-1 and an adjacent or directly adjacent second sub-segment 50-2. The functional element 12 is configured (arranged) to be less susceptible to surface contamination in the first sub-segment 50-1 of the total surface region 50 compared to in the second sub-segment 50-2. The first sub-segment 50-1 of the total surface region 50 has a first surface structure 52 that has higher liquid wettability than a second surface structure 54 of the second sub-segment 50-2 of the total surface region 50.

[0054] According to one embodiment, the total surface area 50 of the functional element 12 can be configured such that, compared with the corresponding surface contamination of the second sub-segment 50-2, the surface contamination of the first sub-segment 50-1 due to surface drying after the functional element 12 is exposed to liquid results in a smaller degradation of the electrical or mechanical properties of the functional element 12.

[0055] According to one embodiment, the total surface area 50 of the functional element 12 relates to the exposed portion of the surface area of ​​the functional element 12, which is connected to an ambient fluid (gas and liquid).

[0056] According to this disclosure, the surface characteristic of "not easily affected by surface contamination" means that, compared with the (equivalent) surface contamination (e.g., due to surface drying after exposure to liquid) of the second sub-segment 50-2 of the total surface region 50, surface contamination (e.g., due to surface drying after exposure to liquid) of the first sub-segment 50-1 of the total surface region 50 results in a lower degradation of the (electro- or mechanical) operating characteristics (e.g., sensitivity, film flexibility, SNR (signal-to-noise ratio), internal resistance, parasitic capacitance, etc.) of the functional element 12.

[0057] The first sub-segment 50-1 of the total surface area 50 can be regarded as a (specific) "non-critical" area of ​​the functional element 12, wherein surface contamination (e.g., due to surface drying after exposure to liquid) will not affect the (significant) degradation of the operating characteristics of the functional element 12, or the functional failure or malfunction of the functional element 12, and therefore will not affect the functional failure or malfunction of the MEMS device 10.

[0058] The second sub-segment 50-2 of the total surface area 50 can be regarded as a (specific) "critical" area of ​​the functional element 12, where surface contamination (e.g., due to surface drying after exposure to liquid) will affect the (significant) degradation of the operating characteristics of the functional element 12, or even affect the functional failure or malfunction of the functional element 12, and thus affect the functional failure or malfunction of the MEMS device 10.

[0059] According to the embodiment, the (significant) degradation of the operating characteristics of the functional element 12 (e.g., a decrease in the SNR of the MEMS device 10) can be avoided by preventing the accumulation or deposition of liquid residues on the second sub-segment 50-2 of the surface region 50 of the functional element 12 (e.g., due to the surface drying of the functional element 12 after exposure to liquid (e.g., tap water)). Otherwise, it may lead to electrical leakage between the (typically) electrically isolated regions of the functional element 12 of the MEMS device 10 in the second sub-segment 50-2 of the total surface region 50.

[0060] The following embodiments relate to possible implementations and methods of different liquid wettability of the first sub-segment 50-1 and the second sub-segment 50-2 of the total surface area 50 of the functional element 12.

[0061] According to an embodiment, the total surface area 50 may include morphological differences or gradients in the liquid contact angle over the total surface area, which result in different liquid wettability of the first sub-segment 50-1 and the second sub-segment 50-2.

[0062] According to an embodiment, a first sub-segment 50-1 of the total surface area 50 can form a liquid collection area during a liquid drying event of the total surface area 50 of the functional element 12. According to an embodiment, a second sub-segment 50-2 of the total surface area 50 can form a liquid "repulsion" area during a liquid drying event of the total surface area 50 of the functional element 12.

[0063] Because the first sub-segment 50-1 (non-critical area) of the total surface area 50 has higher liquid wettability compared to the second sub-segment 50-2 (critical area), droplets (along with contaminants) will move from the second sub-segment 50-2 (critical area) to the first sub-segment 50-1 (non-critical area) and / or may remain in the first sub-segment 50-1 (non-critical area) during the drying process after the functional element 12 is exposed to the liquid. Therefore, contamination of the second sub-segment 50-2 (critical area) of the total surface area 50 of the functional element 12 can be avoided after drying the droplets.

[0064] According to this disclosure, a first sub-segment 50-1 of the total surface region 50 of the functional element 12 has a first surface structure 52 (first surface characteristic) that has a higher liquid wettability than a second surface structure 54 (second surface characteristic) of a second sub-segment 50-2 of the total surface region 50 of the functional element 12. Therefore, the hydrophobicity of the material involved in the functional element 12 of the MEMS device 10 (which provides different surface structures or surface characteristics for the functional element 12) can be controlled to guide the movement of liquids or droplets along with contaminants therein (e.g., during a drying process after the functional element 12 has been exposed to liquid) to different (predetermined) drying areas of the functional element (i.e., the first sub-segment 50-1 of the total surface region 50). Thus, the “critical” surface region of the functional element 12 (i.e., the second sub-segment 50-2 of the total surface region 50) can remain clean from contaminants in the liquid (free from contaminants in the liquid).

[0065] Therefore, according to this disclosure, the functional element 12 of the MEMS device 10 may include a liquid contact angle gradient or liquid contact angle (LCA) gradient difference (or LCA gradient / difference) along its total surface region 50, wherein the more hydrophilic portion 50-1 of the surface region 50 of the functional element 12 (i.e., the first sub-segment 50-1 of the total surface region 50) has higher liquid wettability than the second surface structure of the second sub-segment 50-2 of the total surface region 50, and serves as a "liquid collection" area during the drying process of the functional element 12 after the surface region 50 of the functional element 12 has been exposed to a liquid (e.g., tap water).

[0066] According to an embodiment, the first surface structure of the first sub-segment 50-1 may include a lower liquid contact angle (LCA) or a lower water contact angle (WCA) compared to the second surface structure of the second sub-segment 50-2 of the total surface region 50. A small contact angle of less than 90° can be considered to correspond to high wettability or hydrophilicity, while a large contact angle of greater than 90° can be considered to correspond to low wettability or hydrophobicity.

[0067] According to this disclosure, the total surface region 50 of the functional element 12 includes a wettability gradient between a first sub-segment 50-1 and a second sub-segment 50-2, wherein this wettability gradient can guide the movement of droplets to the first sub-segment 50-1 (a non-critical region) of the total surface region 50 without any external force. Therefore, by having different sub-segments 50-1 and 50-2 with different wettabilities 52 and 54 on the surface region 50, droplets containing particles can then be delivered / manipulated in terms of position.

[0068] According to an embodiment, the first surface structure of the first surface sub-segment 50-1 may have hydrophilic surface properties, and the second surface structure of the second surface sub-segment 50-2 may have hydrophobic surface properties.

[0069] In the context of this specification, the terms “first (hydrophilic) surface structure 52 of first surface sub-segment 50-1” and “second (hydrophobic) surface structure 54 of second surface sub-segment 50-2” for functional element 12 may also mean that, according to an embodiment, the first surface structure 52 of the first surface sub-segment 50-1 may include lower hydrophobic surface properties compared to the second surface structure 54 of the second surface sub-segment 50-2, or according to another embodiment, the first surface structure 52 of the first surface sub-segment 50-1 may include higher hydrophilic surface properties compared to the second surface structure 54 of the second surface sub-segment 50-2.

[0070] Therefore, this method allows the fabrication of MEMS devices 10 (e.g., MEMS acoustic transducers or other MEMS sensors or MEMS actuators) with enhanced levels of environmental robustness (especially against liquid (e.g., water) immersion and electrical leakage caused by particles or contaminants due to surface drying after exposure to liquid), wherein the MEMS device 10 has a functional element 12 having a specifically selected sub-segment 50-1 of the total surface area 50, which has higher liquid wettability compared to the remaining sub-segment 50-2 of the total surface area 50 of the functional element 12.

[0071] Because the functional element 12 of the MEMS device 10 has a surface segment 50-1 that acts as a "liquid collection" area (water collection area) during the drying process, liquid-resistant (waterproof) MEMS devices (e.g., MEMS acoustic transducers) can be constructed without the need for an external environmental barrier. Therefore, the module cost of the MEMS device 10 can be significantly reduced.

[0072] Enhanced liquid immersion resistance of the MEMS device 10 can eliminate the need for external environmental barriers, or alternatively, smaller liquid-resistant (water-resistant) external environmental barriers can be used. Both scenarios will enhance the operational characteristics of the MEMS device 10, such as system SNR, and reduce the cost of the resulting module. External environmental barriers are typically used to minimize or prevent contact between the functional components of a MEMS device and water or any liquid from the environment.

[0073] According to an embodiment, the functional element 12 may include at least one of an electrical operating element, a mechanical operating element, and / or a fluid operating element 13 in the second sub-section. Therefore, the functional element 12 may include at least one of a conductive trace 13-1, a dielectric segment 13-2, or a vent 13-3 in the second sub-section 50-2 of the total surface area 50.

[0074] During a liquid drying event of the total surface area 50 of the functional element 12, a first sub-segment 50-1 of the total surface area 50 can form a liquid collection area, while a second sub-segment 50-2 of the total surface area 50 can form a liquid "repellent" area. Therefore, the MEMS device 10 having the functional element 12 as described above can avoid or at least greatly reduce surface contamination of the second sub-segment 50-2 of the total surface area 50 of the functional element 12 due to liquid residues (e.g., water residues in the form of salt, chalk, etc.) resulting from surface drying treatment after the surface area 50 of the functional element 12 has been exposed to liquid (e.g., tap water). Therefore, the MEMS device 10 having the functional element 12 can avoid or at least greatly reduce leakage between electrically isolated segments of the functional element (e.g., a microphone diaphragm), leakage between (electrically isolated) conductive traces on the surface area of ​​the functional element, leakage between the functional element (e.g., a microphone diaphragm) and the substrate (or other conductive structures of the MEMS device), mechanical obstruction of through-holes (vents) of the functional element, etc.

[0075] According to an embodiment, the first (hydrophilic) surface structure 52 of the first surface sub-segment 50-1 of the functional element 12 may include at least one of the following: nanopillars or micropillars, locally deposited or patterned self-assembled monolayers (SAMs), selectively laser-processed surface structures, such as nanoparticle structures applied by inkjet printing, nanopatterning, nanopatterning combined with liquid injectors or lubricant injectors, nanopatterning combined with SAM coatings, and printed hydrophobic nanoparticles or SAM structures.

[0076] According to an embodiment, the second (hydrophobic) surface structure 54 of the second surface sub-segment 50-2 of the functional element 12 may include at least one of the following: nanopillars or micropillars, locally deposited or patterned SAM, selectively laser-treated surface structure, nanoparticle structure (e.g., applied by inkjet printing), nanopatterning, nanopatterning in combination with liquid injector or lubricant injector, nanopatterning in combination with SAM coating, and printed hydrophilic nanoparticle or SAM structure.

[0077] According to another embodiment, the first sub-segment 50-1 and the second sub-segment 50-2 of the functional element 12 having different liquid wettability can be achieved by using different materials for the functional element 12 having different wettability, liquid / water contact angle or hydrophobicity (e.g., Si to SiN).

[0078] The first surface structure of the first surface sub-segment 50-1 and the second surface structure of the second surface sub-segment 50-2 of the functional element 12 are further described in detail, for example, based on the following Figures 3 to 16.

[0079] like Figure 1A As shown, the MEMS device 10 includes a functional element 12 having a deflectable film structure 14. The MEMS device 10 may also optionally include a rigid electrode structure 16, for example, to provide a capacitive transducer mechanism in a configuration perpendicular (along the z-direction) to and overlapping the deflectable film structure 14, and may include a substrate 18 (e.g., a semiconductor substrate (e.g., a Si substrate)) having a through opening 18-1, such as a so-called Bosch cavity, between a first main surface region 18-A (e.g., front side) and a second main surface region 18-B (e.g., back side) of the substrate 18. The through opening 18-1 has sidewalls 18-C. An insulating structure 28 is provided at the peripheral portions of the film structure 14 and the rigid electrode structure 16. The insulating structure 28 is provided to fix the peripheral portions of the film structure 14 and the rigid electrode structure 16 relative to each other and relative to the substrate 18. Therefore, the MEMS device 10 can be arranged as an SBP (single backplane) structure, such as a single backplane acoustic transducer 10. The membrane structure 14 and the rigid electrode structure 16 may include polycrystalline silicon material (Si = silicon), wherein the rigid electrode structure 16 may also include a SiN4 material (intermediate) layer.

[0080] Regarding the different embodiments and alternatives of this disclosure, it should be noted that the MEMS device 10 can be formed as an SBP (single backplane) structure (see example...). Figure 1A However, it can also be formed as an SDM structure (see example). Figure 1B-C), formed as a DBP (dual backplane) structure, formed as a MEMS pressure sensor, or generally formed as a MEMS transducer (sensor or actuator) or MEMS environmental sensor, wherein the MEMS device 10 includes a (deflectable) functional element 12 (e.g., having a membrane structure) in fluid communication with the environment. According to embodiments, the membrane structure may include, for example, a circular, elliptical, oval, square, rectangular, hexagonal, or any regular convex polygonal shape.

[0081] according to Figure 1A The MEMS device 10 shown in the example has functional elements 12 (e.g., having an acoustic transduction portion) including, for example, a deflectable (movable) film structure 14, a rigid electrode structure (also referred to as a stator, backplate, or counter electrode), a substrate 18, and an insulating structure 28.

[0082] Figure 1B -C shows a schematic cross-sectional view and a schematic top view (planar view) of a MEMS device 10 according to another embodiment of the present disclosure. Figure 1B -C and the following figures exemplarily illustrate a MEMS device 10 in the form of a dual-diaphragm MEMS microphone or a hermetically sealed dual-diaphragm (SDM) MEMS microphone according to various embodiments of the present disclosure. However, the following description of the MEMS device 10 is equally applicable to any MEMS sensor or MEMS environmental sensor, wherein the MEMS device 10 includes a (deflectable) functional element 12 in fluid communication with the environment, such as an acoustic transducer having a membrane structure.

[0083] As in Figure 1B As exemplarily shown in the cross-sectional view, the MEMS device 10 can be formed as a dual-film MEMS microphone 10, which includes a functional element 12 having a first deflectable film structure 14, a rigid electrode structure 16, and a second deflectable film structure 15, which are arranged vertically (along the z-direction). The rigid electrode structure 16 is disposed between the first deflectable film structure 14 and the second deflectable film structure 15, wherein the first deflectable film structure 14 and the second deflectable film structure 15 each include deflectable portions 14-1 and 15-1. The deflectable portions 14-1 of the first deflectable film structure 14 and the deflectable portions 15-1 of the second deflectable film structure 15 are mechanically connected to each other by mechanical connecting elements (e.g., pillars or cylinders) 17 and are mechanically decoupled from the rigid electrode structure 16.

[0084] The (sealed) dual-film MEMS microphone form of MEMS device 10 may include a substrate 18 having a through opening 18-1 between a first main surface region 18-A (e.g., front side) and a second main surface region 18-B (e.g., back side) of the substrate 18, such as a so-called Bosch cavity.

[0085] A first deflectable (movable) membrane structure 14, a rigid electrode structure (also referred to as a stator, backplate, or counter electrode) 16, and a second deflectable (movable) membrane structure 15 form the acoustic transducer portion (functional element) 12 of the MEMS device 10. The acoustic transducer portion 12 of the MEMS device 10 can be disposed at a first main surface region 18-A of the substrate 18 and can at least partially (or completely) span a through opening 18-1 in the substrate 18. The acoustic transducer portion 12 senses the pressure difference between its front and back sides by mechanically coupling the first deflectable membrane structure 14 and the second deflectable membrane structure 15 to corresponding deflections relative to the rigid electrode structure 16. According to an embodiment, the cavity or space 20 between the first membrane structure 14 and the second membrane structure 15 can be opened relative to the environment, for example, through an opening 22 or multiple openings (perforations). Alternatively, the cavity 20 between the first membrane structure 14 and the second membrane structure 15 can be closed with a laterally closed through-hole (vent) 24, or even hermetically sealed (sealed) relative to the environment, for example to provide a sealed dual-membrane (SDM) MEMS microphone 10. A sealed configuration can provide improved dust and moisture protection.

[0086] The terms “electrode” and “structure” are intended to indicate that the film structures 14, 15 and the rigid electrode structure 16 may each include a semiconductor or conductive layer, or may also include a sequence or stack of layers having multiple different layers, wherein at least one of the layers is conductive, for example including a metallization layer and / or a conductive semiconductor (e.g., polycrystalline silicon) layer.

[0087] like Figure 1C As shown in the exemplary plan view, the MEMS device 100 may further include electrical contact elements 26-1, 26-2, 26-3, and 26-4 for providing electrical connections to another electrical component or circuit (e.g., an ASIC (Application-Specific Integrated Circuit)). An insulating structure 28 is provided between the peripheral portions of the film structures 14 and 15 and the rigid electrode structure 16. The insulating structure 28 is provided to secure the peripheral portions of the film structures 14 and 15 and the rigid electrode structure 16. The electrical contact elements 26-1, 26-2, 26-3, and 26-4 may be arranged within or at the insulating structure 28. For example, the insulating structure 28 may comprise SiO2 material based on tetraethyl orthosilicate (TEOS) deposition.

[0088] In a hermetically sealed dual-membrane (SDM) configuration, a first membrane structure 14 and a second membrane structure 15 are arranged in a hermetically sealed configuration, with a cavity 20 formed therebetween. The sealed cavity 20 is formed as an encapsulation structure or a vacuum cavity, sealing off a reduced atmospheric pressure compared to ambient pressure, wherein, for example, the reduced atmospheric pressure in the low-pressure region is a vacuum or near-vacuum (e.g., less than about 10% or 1% of ambient pressure or standard atmospheric pressure (101.325 kPa), or for example, less than 50 kPa, 20 kPa, or less than 5 kPa). Once the first (mechanically coupled) membrane structure 14 and the second (mechanically coupled) membrane structure 15 deflect ±Δz relative to the rigid electrode structure 14, this deflection or displacement can be capacitively read out to provide an output signal dependent on the deflection (gap change) relative to the rigid electrode structure 16. According to another embodiment, the transducer may also include piezoelectric, piezoresistive, or optical sensing schemes.

[0089] according to Figure 1B The MEMS device 10 illustrated in -C includes a functional element 12 (acoustic transducer portion) comprising a first mechanically coupled membrane structure 14 and a second mechanically coupled membrane structure 15, as well as, for example, a rigid electrode structure (if fluidly connected to the environment) 16, a substrate 18, and an insulating structure 28.

[0090] Figure 2 An exemplary schematic flowchart of a method 100 for manufacturing a MEMS device 10 according to an embodiment of the present disclosure is shown.

[0091] According to an embodiment, the manufacturing method includes the following steps: providing a MEMS device 10 having a functional element 12 in fluid communication with the environment, wherein the functional element 12 includes a total surface region 50 having a first sub-segment 50-1 and an adjacent or directly adjacent second sub-segment 50-2; and providing (forming) a first surface structure 52 120 on the first sub-segment 50-1 of the total surface region 50, which has higher liquid wettability compared to a second surface structure 54 on the second sub-segment 50-2 of the total surface region 50.

[0092] According to an embodiment, the step of providing a first surface structure 52 on a first sub-segment 50-1 of the total surface region 50 includes at least one of the following steps: providing (forming) on ​​the first sub-segment 50-1 of the total surface region 50 nanopillars or micropillars of a substrate material that is hydrophilic compared to the second surface structure 54, locally deposited or patterned SAM, selectively laser-treated surface structures, nanoparticle structures, nanopatterning, nanopatterning combined with liquid injectors or lubricant injectors, nanopatterning combined with SAM coatings, and printed structures of hydrophilic nanoparticles or SAM.

[0093] According to an embodiment, the step of providing a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50 includes at least one of the following steps: providing (forming) on ​​the second sub-segment 50-2 of the total surface region 50 nanopillars or micropillars of a substrate material that is hydrophobic compared to the first surface structure 52, locally deposited or patterned SAM, selectively laser-treated surface structures, nanoparticle structures, nanocarbon coatings (such as graphite or diamond-like carbon), chemically modified nanocarbon coatings, nanopatterning, nanopatterning combined with liquid injectors or lubricant injectors, nanopatterning combined with SAM coatings, and printed structures of hydrophobic nanoparticles or SAM.

[0094] According to an embodiment, method 100 further includes the step of forming a (morphological) difference or gradient of liquid contact angle on the total surface area 50 of functional element 12 for providing a first sub-segment 50-1 and a second sub-segment 50-2 with different liquid wettability.

[0095] Before describing other embodiments, it should be noted that in the current description of the embodiments, the same or similar elements having the same structure and / or function are provided with the same reference numerals or the same names, wherein a detailed description of such elements will not be repeated for each embodiment. Therefore, the above regarding Figure 1A -C and Figure 2 The description also applies to the other embodiments described below. In the following description, the following concepts are discussed in detail. Figure 1A -C、 Figure 2 The differences or additions (e.g., additional elements or method steps) of the illustrated embodiments, and the resulting technical effects.

[0096] Figure 3A -D shows a schematic cross-sectional view of a partial cross-section of the surface region 50 of the functional element 12 of the MEMS device 10 during a drying process following exposure of the functional element 12 to a liquid 40 containing contaminants and / or particles 48, according to an embodiment of the present disclosure.

[0097] like Figure 3A As exemplarily shown, the surface region 50 of the functional element 12 is at least partially or completely covered by the liquid 40 (e.g., due to the MEMS device 10 being immersed in the liquid 40 (e.g., tap water)). Since the functional element 12 is in fluid contact with the environment, the immersion of the MEMS device 10 in the liquid results in the wetting of the surface region 50 of the functional element 12. Contaminants and / or particles 48 may (equally) be distributed in the liquid 40.

[0098] like Figure 3BAs shown, during the drying process of the surface region 50 of the functional element 12, droplets 42 of liquid 40 are guided to the more hydrophilic surface region 50-1 (the first sub-segment 50-1 of the total surface region 50).

[0099] like Figure 3C As shown, the second sub-segment (the less hydrophobic or less hydrophilic portion) 50-2 of the total surface region 50 forms a liquid repulsion region during the liquid drying event of the functional element 12, wherein the more hydrophilic portion of the total surface region 50 (the first sub-segment 50-1) acts as a liquid collection region (water collection region) during the drying process. Therefore, during the drying process, droplets 42 are guided to the more hydrophilic region 50-1 of the functional element 12.

[0100] Finally, as Figure 3D As shown, after the surface of the wetted functional element 12 dries, liquid residues (contaminants and / or particles) 48 accumulate or precipitate in the more hydrophilic region (first sub-segment 50-1) of the total surface area 50 of the functional element 12.

[0101] In summary, the non-critical region (first sub-segment) 50-1 of the functional element 12 of the MEMS device 10 is formed to be hydrophilic or less hydrophobic compared to the critical region (second sub-segment) 50-2 of the total surface area 50 of the functional element 12 of the MEMS device 10. Therefore, during the drying process, droplets will move to the (more) hydrophilic or (more) hydrophobic region that serves as the drying zone. Thus, after drying the droplets 42, ideally, no contaminating particles remain on the critical region 50-2 of the functional element 12.

[0102] Figure 4A A schematic cross-sectional view of a MEMS device 10 is shown, which is an exemplary embodiment of surface structures 52, 54 of functional elements according to another embodiment of the present disclosure.

[0103] Figure 4B An enlarged schematic cross-sectional partial view of the functional element 12 of the MEMS device 10 is shown, which has an exemplary embodiment of the surface structure of the functional element according to another embodiment of the present disclosure.

[0104] like Figure 4AAs exemplarily illustrated, the surface structures 52, 54 of the functional element 12 may include nano / microstructures 23 (such as nanopillars (nanocylinders) or micropillars (microcylinders)), nano / microfins, nano / microcones, and laser-induced periodic surface structures (LIPSS) 23. The lateral diameter of the nanostructures (e.g., nanopillars) may range from 10 nm to 1000 nm, and the lateral diameter of the microstructures (e.g., micropillars) may range from 1 μm to 10 μm. Typically, the geometry (lateral cross-sectional area) of the nano / microstructures 23 is selected to provide a liquid contact angle gradient or gradient difference along the total surface area 50 of the functional element 12. The nano / microstructures 23 may be configured to provide (rectangular, circular, or oval) rods or pillars having a distributed variation in lateral cross-sectional area and spacing (distance) to provide a linear gradient variation or gradual gradient difference in the liquid contact angle over the surface area 50 of the functional element 12.

[0105] Therefore, the more hydrophilic portion 50-1 (having the first surface structure 52) of the surface region 50 of the functional element 12, i.e., the first sub-segment 50-1 of the total surface region 50, has higher liquid wettability compared to the second sub-segment 50-2 (having the second surface structure 54) of the total surface region 50, and acts as a liquid collection area during the drying process of the functional element 12 after it has been exposed to liquid. During the liquid drying event of the total surface region of the functional element 12, the second sub-segment 50-2 of the total surface region 50 forms a liquid repulsion area.

[0106] like Figure 4A The MEMS device 10, exemplarily illustrated in section -B, having a functional element 12 in the form of an SDM microphone, includes gradient nanopatterns 52, 54 of a top film structure 14 and a bottom film structure 15. The nanopatterns 52, 54 of the first film structure 14 and the second film structure 15 of the functional element 12 can be formed by a combination of laser processing and photolithography etching. The design of the nanostructures (nanopatterns or micropatterns) provides a (linear or stepwise) topographic gradient.

[0107] It should also be noted that, according to another embodiment, gradient nanopatterning 52, 54 can be formed individually on either the bottom film 14 or the top film 15, such that a local hydrophobic gradient can be provided on either the top or bottom side of the functional element 12 of the MEMS device 10. Therefore, at least one (one or both) of the film structures 14, 15 of the functional element 12 can be surface modified.

[0108] According to another embodiment, gradient nanopatterning 52, 54 may also be selectively formed on the sidewall 18-C of the through opening (Bosch cavity) 18-1, which may also form part of the surface region 50 of the functional element 12 to provide a first surface structure 52 (e.g., a more hydrophilic structure or coating) of the first surface region 50-1 on the exposed inner surface 18-C of the through opening 18-1 of the substrate 18, or to provide a linear gradient change or gradual gradient difference of liquid contact angle on the sidewall 18-C of the through opening (Bosch cavity) 18-1.

[0109] In summary, the non-critical region 50-1 of the functional element 12 is formed to be either more hydrophilic or less hydrophobic compared to the critical region 50-2 of the functional element 12, resulting in a wettability gradient between the critical region 50-2 and the non-critical region 50-1 of the MEMS device. During the drying process of the functional element 12, droplets 42 will form and migrate to the more hydrophilic or less hydrophobic region 50-1 of the functional element 12. Therefore, ideally, there is no contamination on the critical region 50-2 when the droplets 42 are dried. To achieve the migration of droplets from the critical region 50-2 to the non-critical region 50-1 of the functional element 12, only a sufficiently large wettability gradient is required, where “superhydrophobicity” of the surface region 50 is not necessary.

[0110] In the following description of another embodiment of the manufacturing method 100 for providing a MEMS device 10 having a functional element 12, it should also be noted that corresponding surface modifications 52, 54 according to different embodiments of the manufacturing method 100 can be formed individually on the bottom film 14 or the top film 15, such that a local hydrophobic gradient or difference can be provided on either the top side or the bottom side of the functional element 12 of the MEMS device 10. Therefore, at least one (only one or both) of the film structures 14, 15 of the functional element 12 can be surface modified. Furthermore, corresponding surface modifications 52, 54 can be selectively formed on the sidewall 18-C of the through opening (Bosch cavity) 18-1, which can also form part of the surface region 50 of the functional element 12.

[0111] Figures 5A to 5C An exemplary schematic flowchart of an embodiment of a method 100 for providing a MEMS device 10 having a functional element 12 according to an embodiment of the present disclosure is shown, wherein the functional element 12 has different surface structures 52, 54 (first surface structure 52, second surface structure 54) of a total surface area 50.

[0112] According to an embodiment, manufacturing method 100 includes the step of providing a MEMS device 110 having a functional element 12 in fluid communication with the environment, wherein the functional element 12 includes a total surface region 50 having a first sub-segment 50-1 and an adjacent second sub-segment 50-2. Figure 5A As exemplarily illustrated, a hermetically sealed dual-film (SDM) MEMS device 10 having functional element 12 is provided (manufactured). For example... Figure 5A As exemplarily shown in -C, the functional element 12 (acoustic transducer portion) of the MEMS device 10 includes a first deflectable (movable) film structure 14 and a second deflectable (movable) film structure 15, and optionally includes a rigid electrode structure (if fluidly connected to the environment) 16, a substrate 18, and an insulating structure 28.

[0113] also, Figure 5B -C exemplarily illustrates step 120 (with partial steps 120-1+120-2) of providing (e.g., forming) a first surface structure 52 on a first sub-segment 50-1 of the total surface region 50, the first surface structure 52 having higher liquid wettability compared to a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50.

[0114] More specifically, such as Figure 5B As exemplarily shown, selective laser patterning 120-1 is performed on the top membrane structure 15 as a subtraction method for providing nano / microstructures 23 (such as nanopillars (nanocylinders) or micropillars (microcylinders) 23). Depending on the laser parameters employed, other nano / microstructures 23 (e.g., nano / microfins, nano / micro cones, and laser-induced periodic surface structures (LIPSS)) can also be created. Their geometries (e.g., the depth / height and width of the structure) are adjustable. Various laser types can be suitable for this purpose (e.g., picosecond lasers, femtosecond lasers, and nanosecond lasers). Figure 5B As exemplarily shown, the laser-patterned surface region 50-2 has hydrophobic properties, while the remaining surface region 50-1 (without or with reduced laser patterning) has hydrophilic properties (surface properties).

[0115] like Figure 5C As exemplarily shown, selective laser patterning 120-2 is performed on the bottom film structure 14 to provide a nano / micro structure 23, wherein the laser beam travels directly through the Bosch cavity 18-1 of the substrate 18.

[0116] therefore, Figure 5A-C illustrates a possible implementation of a laser-based fabrication method 100, wherein a first surface structure 52 on a first sub-segment 50-1 and a second surface structure 54 on a second sub-segment 50-2 of a total surface region 50 are provided (formed) on a functional element 12 of a MEMS device 10, wherein the first surface structure 52 on the first sub-segment 50-1 has higher liquid wettability compared to the second surface structure 54 on the second sub-segment 50-2 of the total surface region 50 of the functional element 12. Typically, the geometry (lateral cross-sectional area) of the nano / micro structure 23 is chosen to provide a liquid contact angle gradient or gradient difference along the total surface region 50 of the functional element 12.

[0117] This laser processing is cheaper than etching processes (e.g., reactive ion etching (RIE)) or conventional photolithography following bottom-up growth / deposition. Figure 5C As shown, the laser beam can directly reach the bottom film 14 to remove unwanted material (to pattern the bottom film structure 14), whereas in photolithography, it is difficult to achieve uniform spin-coating of the resist material due to the high aspect ratio of the Bosch cavity (i.e., trenches / cavities with a height of approximately 400 μm). Furthermore, the laser beam can penetrate to regions near the etched Bosch cavity edges, leading to the possibility of structuring the film edges. These advantages are primarily achieved when functional elements 12, which are already almost entirely fabricated on the wafer (e.g., have already undergone metallization), are used or subjected to nano / micron structuring. Laser structuring is a physical process, therefore no chemical solution is required to cover the target surface.

[0118] In short, Figure 5A -C illustrates a reduction method 100 for selectively providing laser-patterned structures 52, 54 (i.e., a first surface structure 52 on a first sub-segment 50-1 and a second surface structure 54 on a second sub-segment 50-2) on a bottom film 14 and a top film 15, thereby providing functional elements 12 of a MEMS device 10 with local hydrophobicity gradients.

[0119] Figure 6A -B shows a schematic cross-sectional view and an enlarged schematic partial cross-sectional view of an exemplary embodiment of a MEMS device 10 having surface structures 52, 54 with functional elements 12 according to another embodiment of the present disclosure.

[0120] As in Figure 6A As illustrated in -B, such as regarding Figure 4A -B and Figure 5AThe gradient nano or micro patterns 52, 54 described in -C can be combined with an injection of liquid and / or lubricant 30. According to one embodiment, the first sub-segment 50-1 and the second sub-segment 50-2 of the total surface region 50 of the functional element 12 can be (at least partially or completely) covered with lubricant 30. Lubricant 30 is a substance that helps reduce friction between contacting surfaces. Lubricant 30 is deposited onto and between the gradient nanostructures or microstructures 23 to enhance the motion control of droplets (e.g., water droplets) 42, i.e., to add a "smoothing" effect. According to one embodiment, different types of lubricant 30 can result in different directions of movement of the liquid (water) droplets 42. More specifically, the specific type of lubricant 30 can define which regions form the first (non-critical) sub-segment 50-1 and the second (critical) sub-segment 50-2 of the total surface region 50 of the functional element 12.

[0121] Figure 7A -C shows a schematic cross-sectional view and an enlarged schematic partial cross-sectional view of an exemplary embodiment of a MEMS device 10 having a surface structure with functional element 12 according to another embodiment of the present disclosure.

[0122] like Figure 7A As exemplarily shown in section -B, the gradient nano- or micro-pattern 23 can be combined with a SAM (self-assembled monolayer) coating or layer 5. Thus, a SAM layer 58 is coated on the gradient nano- or micro-structures 52, 54 of the functional element 12. To improve the robustness of the functional device 12 (i.e., to further avoid potential electrical leakage on the MEMS surface), a (very) thin insulating layer 59 made of oxides (e.g., SiO2, AlO2, Al2O3, or TiO2) can first be deposited on films 14, 15 prior to SAM coating, for example using molecular vapor deposition (MVD) or atomic layer deposition (ALD) techniques. Based on the applied SAM layer 58, the hydrophilic and hydrophobic properties of the different patterns of nano- or micro-pillars 23 used to provide the total surface area 50 of the functional element 12 can be enhanced or amplified.

[0123] Figure 7C It also shows Figure 7B Two enlarged schematic cross-sectional views of one of the nanopillars or micropillars 23. According to an embodiment, the nanopillar or micropillar 23 ( Figure 7C The left element may include a polycrystalline silicon material on which a SAM coating or layer 58 is applied (only). According to another embodiment, nano or micro pillars 23 ( Figure 7CThe right-hand component may include a polycrystalline silicon material on which a (thin) insulating layer 59 (e.g., an oxide layer having SiO2, AlO2, Al2O3, or TiO2) is applied, and a SAM coating or layer 58 is applied on the (thin) insulating layer 59. The SAM coating or layer 58 may have a thickness, for example, less than 3 nm or between 0.3 nm and 2.4 nm. The (thin) insulating layer 59 (e.g., an oxide layer, SiO2, AlO2, Al2O3, or TiO2) may have a thickness, for example, less than or equal to 15 nm or between 2 nm and 15 nm.

[0124] According to an embodiment, the material used for the employed SAM layer 58 can be selected from materials including perfluoroalkyl substances and polyfluoroalkyl substances (PFAS) or PFAS-free materials. PFAS-containing SAM materials may include FDTS (perfluorodecyltrichlorosilane), FOTS (fluoro-octyltrichlorosilane), FOMMS, FOTES, and FOMDS. PFAS-free SAM materials may include DDMS (dichlorodimethylsilane), ODS (octadecylsilane or octadecyltrihydridosilane), ODTS (octadecyltrichlorosilane), OTS (octyltrichlorosilane), and OTMS (octadecyltrimethoxysilane).

[0125] Figure 8A -C shows a schematic cross-sectional view of a MEMS device 10 having surface structures 52, 54 of functional elements 12 according to another embodiment of the present disclosure, an enlarged schematic partial cross-sectional view of the surface structures 52, 54 of functional elements 12, and a schematic top view (planar) view of the surface structures 52, 54 of functional elements 12.

[0126] like Figure 8AAs shown in -C, the surface structure 54 of the second (critical) sub-segment 50-2 of the total surface region 50 of the functional element 12 can be formed by a patterned hydrophobic SAM 60 (self-assembled monolayer), wherein the patterned SAM 60 is formed (deposited) on the SiO2 / polysilicon material stack (hydrophilic TEOS(SiO2) 14-A on polysilicon 14-B) of the film structures 14, 15 of the functional element 12. The material of the film structure of the functional element 12 may include, for example, a hydrophilic TEOS material (SiO2). Therefore, the first surface structure 52 of the first sub-segment (hydrophilic TEOS(SiO2)) 50-1 has higher liquid wettability compared to the second surface structure 54 of the second sub-segment 50-2 (hydrophobic SAM) of the total surface region 50 of the functional element 12. Therefore, the surface region 50 of the functional element 12 may include (single) hydrophobic SAM 60 to form the second sub-segment 50-2 of the total surface region 50. Furthermore, a very thin insulating layer made of oxides (e.g., SiO2, AlO2, Al2O3, or TiO2) can be deposited on the film before SAM coating, for example using molecular vapor deposition (MVD) or atomic layer deposition (ALD) techniques. This insulating layer is hydrophilic and can be used to enhance electrical leakage caused by conductive contamination that may remain on the film after liquid drying (dehumidification) treatment, affecting the functional element 12 pair.

[0127] Figure 9A -C shows a schematic cross-sectional view of a MEMS device 10 having surface structures 52, 54 of functional elements 12 according to another embodiment of the present disclosure, an enlarged schematic partial cross-sectional view of surface structures 52, 54 of functional elements 12, and a schematic top view (planar) view of surface structures 52, 54 of functional elements 12.

[0128] like Figure 9A As shown in -C, the hybrid hydrophobic / hydrophilic SAM 60 can be used to form the first (non-critical) sub-segment 60-1 and the second (critical) sub-segment 50-2 of the total surface region 50 of the functional element 12. The first SAM pattern 60-1 and the second SAM pattern 60-2 are formed (deposited) on the oxide / polycrystalline silicon material stack (e.g., hydrophilic TEOS (SiO2) or AlO2, Al2O3, or TiO2) of the film structures 14, 15 of the functional element 12. More specifically, as... Figure 9AAs exemplarily shown in -C, a (more) hydrophilic SAM pattern 60-1 can form a first surface structure 52 of a first sub-segment 50-1 of the functional element 12, wherein a (more) hydrophobic SAM pattern 60-2 can form a second surface structure 54 of a second sub-segment 50-2 of the total surface region 50 of the functional element 12. Therefore, the first surface structure 52 of the first sub-segment 50-1 has (more) hydrophilic SAM pattern 60-1, and compared to the second surface structure 54 of the second sub-segment 50-2 having (more) hydrophobic SAM pattern 60-2 on the total surface region 50 of the functional element 12, it has higher liquid wettability.

[0129] Figure 10A -D shows an exemplary schematic flowchart of a method 100 for manufacturing the surface structures 52, 54 of the functional elements 12 of a MEMS device 10 according to another embodiment of the present invention.

[0130] According to an embodiment, the manufacturing method 100 includes the step of providing a MEMS device 10 having a functional element 12 in fluid connection with the environment, wherein the functional element 12 includes a total surface region 50 having a first sub-segment 50-1 and an adjacent second sub-segment 50-2. Figure 10A A partial view of the functional element 12 of the MEMS device 10 is shown as an example, including a Si substrate 18 having SiO2 / Si stacks 14-A, 14-B, or a deflectable (movable) film structure 14, for example, having SiO2 / polysilicon stacks 14-A, 14-B. Therefore, the functional element 12 may include, for example, a top layer having deposited hydrophilic TEOS material (SiO2) or naturally (thermally) grown SiO2 material.

[0131] also, Figure 10B -D exemplarily illustrates step 120 of providing (e.g., forming) a first surface structure 52 on a first sub-segment 50-1 of the total surface region 50, the first surface structure 52 having higher liquid wettability compared to a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50.

[0132] More specifically, such as Figure 10B As exemplarily shown, a hydrophobic self-assembled monolayer (SAM) 58 is deposited, for example, by MVD (molecular vapor deposition) or by immersion over the entire surface of the functional element 12.

[0133] like Figure 10CAs exemplarily shown, a UV lithography process using UV source 70 and photomask 72 is performed to pattern SAM58. The longer the UV exposure time, the more hydrophilic the UV-exposed regions of SAM 58 become. The UV-exposed regions of SAM become hydrophilic due to the formation of SiOH clusters, while the non-exposed regions of SAM 58 remain unchanged, for example, hydrophobic octadecyl or phenyl in the case where OTS (octadecyltrichlorosilane) is selected for SAM 58.

[0134] like Figure 10D As shown, the UV-exposed region of SAM 60 is removed, in which patterned hydrophobic SAM 60 is realized on a hydrophilic SiO2 / Si layer stack (wafer).

[0135] Therefore, the exposed SiO2 layer of the functional element 12 forms a first surface structure 52 on the first sub-segment 50-1, wherein patterned hydrophobic SAM 60 forms a second surface structure 54 on the second sub-segment 50-2 of the total surface region 50 of the functional element.

[0136] therefore, Figure 10A -D illustrates a possible implementation of a fabrication method 100 based on the deposition of patterned SAM 60, which is used to provide a MEMS device 10 with functional elements 12 having local hydrophobicity gradients.

[0137] Figure 11 A schematic cross-sectional view of a MEMS device 10 having surface structures 52, 54 with functional elements 12 according to another embodiment of the present disclosure is shown.

[0138] like Figure 11 As exemplarily shown, the surface structure 54 of the second (critical) sub-segment 50-2 of the total surface region 50 of the functional element 12 can be formed by a patterned nanoparticle layer 62, wherein the patterned nanoparticle layer 62 is formed (deposited) on the dielectric / polycrystalline silicon material stack (e.g., hydrophilic TEOS (SiO2), AlO2, Al2O3, or TiO2 on polycrystalline silicon) of the film structures 14, 15 of the functional element 12. The material of the film structure of the functional element 12 may include, for example, a hydrophilic TEOS material (SiO2). Therefore, the first sub-segment (hydrophilic TEOS (SiO2)) 50-1 has a first surface structure 52 which has a higher liquid wettability compared to the second surface structure 54 of the second sub-segment 50-2 (hydrophobic nanoparticle layer 62) of the total surface region 50 of the functional element 12. Therefore, the surface region 50 of the functional element 12 may include (single) hydrophobic nanoparticle layers (patterns) 62 to form the second sub-segment 50-2 of the total surface region 50.

[0139] Figure 12 A schematic cross-sectional view of a MEMS device 10 having surface structures 52, 54 with functional elements 12 according to another embodiment of the present invention is shown.

[0140] like Figure 12 As exemplarily shown, the hybrid hydrophilic / hydrophobic nanoparticle patterns 62-1, 62-2 can be used to form the first (non-critical) sub-segment 50-1 and the second (critical) sub-segment 50-2 of the total surface region 50 of the functional element 12. For example, the first nanoparticle pattern 62-1 and the second nanoparticle pattern 62-2 are formed (deposited) on the SiO2 / polycrystalline silicon material stack (hydrophilic TEOS(SiO2) on polycrystalline silicon) of the film structures 14, 15 of the functional element 12. More specifically, as... Figure 12 As exemplarily shown, a first nanoparticle pattern 62-1 can form a first surface structure 52 of a first sub-segment 50-1 of the functional element 12, wherein a hydrophobic nanoparticle pattern 62-2 can form a second sub-segment 50-2 of the total surface region 50 of the functional element 12. Therefore, the first surface structure 52 of the first sub-segment 50-1 has a hydrophilic nanoparticle pattern 62-1, which has higher liquid wettability compared to a second surface structure 54 having a second sub-segment 50-2 with a hydrophobic nanoparticle pattern 62-2 on the total surface region 50 of the functional element 12.

[0141] like Figure 12 As exemplarily shown, a hybrid combination of hydrophilic / hydrophobic nanoparticle patterns 62-1, 62-2 can be deposited (applied) onto the exposed surface region 50 of the functional element 12 to form a first surface structure 52 of the first sub-segment 50-1 and a second surface structure 54 of the second sub-segment 50-2 of the functional element 12.

[0142] An example of hydrophilic polymer nanoparticle pattern 62-1 is:

[0143] Polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyacrylamide, N-(2-hydroxypropyl)methacrylamide (HPMA), polyphosphates and polyphosphazenes.

[0144] An example of hydrophobic polymer nanoparticles used for hydrophobic nanoparticle pattern 62-2 is as follows:

[0145] Polyesters (poly(lactic acid) (PLA), poly(glycolic acid), poly(hydroxybutyrate), poly-ε-caprolactone (PCL), poly-β-malic acid, poly(dioxane)), polyanhydride (poly(adipic acid)), polyamide (poly(amino acid)), poly(cyanoacrylate), polyurethane, polyorthoester, poly(styrene) (PS), poly(lactic-co-glycolic acid) (PLGA), poly(isobutyl cyanoacrylate), poly(alkyl cyanoacrylate) (PACA), and polyacetal.

[0146] Figure 13 shows an exemplary schematic flowchart of a method 100 for manufacturing the surface structures 52, 54 of the functional elements 12 of a MEMS device 10 according to another embodiment of the present invention.

[0147] According to an embodiment, the manufacturing method 100 includes the step of providing a MEMS device 10 having a functional element 12 in fluid communication with the environment, wherein the functional element 12 includes a total surface region 50 having a first sub-segment 50-1 and an adjacent second sub-segment 50-2. Figure 13A As exemplarily shown, a hermetically sealed dual-film (SDM) MEMS device 10 having functional element 12 is provided (manufactured). For example... Figure 13A As exemplarily shown in -C, the functional element 12 (acoustic transducer portion) of the MEMS device 10 includes a first deflectable (movable film structure 14) and a second deflectable (movable) film structure 15, and optionally includes a rigid electrode structure (if fluidly connected to the environment) 16, a substrate 18, and an insulating structure 28.

[0148] also, Figure 13A -C exemplarily illustrates step 120 (with partial steps 120-1, 120-2) of providing (e.g., forming) a first surface structure 52 on a first sub-segment 50-1 of the total surface region 50, the first surface structure 52 having higher liquid wettability compared to a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50.

[0149] More specifically, such as Figure 13A As exemplarily shown in the example, by using an inkjet printer 74 (in Figure 13A -B (only the nozzle is shown) selectively inkjet prints an aqueous emulsion containing, for example, nanoparticles / nanomaterials to create (apply) hydrophobic regions 62 (second surface structure 54) on surface regions 50-2 of the top film 15. The hydrophobic regions 62 are applied (printed) as a patterned layer of nanomaterials. According to this method, different hydrophobic nanomaterials can be selected to modify the surface regions 50 of the functional element 12, including metals (e.g., Ag or Au nanoparticles), carbon (e.g., graphene sheets, graphene oxide nanoparticles), and polymers (e.g., polyimide, polyamide).

[0150] like Figure 13B As exemplarily shown, once the printing process 120-1 on the top film surface 15 has been completed, the MEMS device (wafer) 10 can be flipped over, and then the same nanomaterial printing process 120-2 is performed on the surface area of ​​the bottom film structure 14.

[0151] Here, the nanoparticles applied to the second surface structure 54 on the second surface region 50-2 of the functional element 12 are first dried before printing onto the bottom film structure 14. Depending on the aqueous solution used, additional heat treatment may be required to accelerate the drying process of the applied nanomaterial 62.

[0152] like Figure 13C As exemplarily shown, printing and drying processes 120 (120-1, 120-2) have been completed, wherein a first surface structure 52 (hydrophilic surface region) of a first (non-critical) sub-segment 50-1 and a second surface structure 54 of a second (critical) sub-segment 50-2 are obtained on the surface regions 50 of the functional element 12 on both the top film structure 14 and the bottom film structure 15 of the functional element 12.

[0153] In short, Figure 13A -C illustrates an additional method 100 for selectively printing hydrophilic / hydrophobic surface structures 52, 54 on a first sub-segment 50-1 and a second sub-segment 50-2 by printing nanoparticles 62 or SAM 60 to provide a functional element 12 with a local hydrophobicity gradient for a MEMS device 10.

[0154] Regarding the embodiments shown in Figures 8-13, it should be noted that different embodiments can be combined because the first surface structure 52 of the first (non-critical) sub-segment 50-1 can be formed by a hydrophilic SAM pattern 60-1 or a hydrophilic polymer nanoparticle pattern 62-1, wherein the second surface structure 54 of the second (critical) sub-segment 50-2 can be formed by a hydrophobic SAM pattern 60-2 or a hydrophobic polymer nanoparticle pattern 62-2.

[0155] Therefore, a hydrophilic / hydrophobic nanoparticle pattern 60 or a SAM pattern 62 can also be provided on the surface region 50 of the functional element 12 to form the first sub-segment 50-1 and the second sub-segment 50-2 of the functional element 12. As described above, the nanoparticle patterns 62, 62-1, and 62-2 can be provided to the surface region 50 of the functional element 12 by additional methods (e.g., printing or inkjet printing methods (method step 120)).

[0156] Figure 14A-E shows an exemplary schematic flowchart of a method 100 for manufacturing the surface structures 52, 54 of the functional elements 12 of a MEMS device 10 according to another embodiment of the present invention.

[0157] According to an embodiment, the manufacturing method 100 includes the step of providing a MEMS device 10 having a functional element 12 in fluid connection with the environment, wherein the functional element 12 includes a total surface region 50 having a first sub-segment 50-1 and an adjacent second sub-segment 50-2.

[0158] Figure 14A A partial view of a functional element 12 of a MEMS device 10 is shown in the figure, which includes a hydrophilic material (e.g., silicon or polycrystalline silicon) or a hydrophilic surface property.

[0159] also, Figure 14B -E exemplarily illustrates step 120 of providing (e.g., forming) a first surface structure 52 on a first sub-segment 50-1 of the total surface region 50, the first surface structure 52 having higher liquid wettability compared to a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50.

[0160] More specifically, such as Figure 14B As exemplarily illustrated (“hydrophobic layer deposition”), a hydrophobic layer 64 (e.g., diamond-like carbon (DLC)) is deposited over, for example, the entire surface of a functional element 12. The deposited layer 64 is more hydrophobic or less hydrophilic (having lower liquid wettability) compared to the material or surface properties of the functional element 12. In other words, the material or surface properties of the functional element 12 are more hydrophilic or less hydrophobic (having higher liquid wettability) compared to the material of the deposited layer 64.

[0161] like Figure 14C As exemplarily illustrated in the document (“Mask and Patterning”), masking and patterning steps are performed to deposit a patterned mask on a hydrophobic layer. Figure 14D The exemplary illustration (“etching”) removes the exposed areas of the hydrophobic layer, wherein a patterned hydrophobic layer 64 is implemented on a hydrophilic surface (wafer).

[0162] like Figure 14E The exemplary illustration (“mask removal”) shows the removal of a patterned mask, wherein the exposed surface (layer) of the functional element 12 forms a first surface structure 52 on a first sub-segment 50-1, and wherein a patterned hydrophobic layer 64 forms a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50 of the functional element 12.

[0163] therefore, Figure 14A-E illustrates a possible implementation of a fabrication method 100 based on the deposition of a patterned hydrophobic layer 64, which is used to provide a MEMS device 10 with functional elements 12 having local hydrophobicity gradients. More specifically, Figure 14A -E illustrates an inexpensive processing flow for providing a (relatively) large wettability gradient between the first sub-segment 50-1 and the second sub-segment 50-2 of the total surface area 50 of the functional element 12.

[0164] Figure 15A -D shows an exemplary schematic flowchart of a method 100 for manufacturing the surface structures 52, 54 of the functional elements 12 of a MEMS device 10 according to another embodiment of the present disclosure.

[0165] According to an embodiment, the manufacturing method 100 includes the step of providing a MEMS device 110 having a functional element 12 in fluid connection with the environment, wherein the functional element 12 includes a total surface region 50 having a first sub-segment 50-1 and an adjacent second sub-segment 50-2.

[0166] Figure 15A A partial view of a functional element 12 of a MEMS device 10 is shown in the figure, which includes a hydrophilic material (e.g., silicon or polycrystalline silicon) or a hydrophilic surface property.

[0167] also, Figure 15B -D exemplarily illustrates step 120 of providing (e.g., forming) a first surface structure 52 on a first sub-segment 50-1 of the total surface region 50, the first surface structure 52 having higher liquid wettability compared to a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50.

[0168] like Figure 15B As exemplarily shown in the example (“masking and patterning”), a masking and patterning step is performed to deposit a patterned mask 72 on the hydrophilic surface of the functional element 12.

[0169] like Figure 15C As exemplarily illustrated (“hydrophilic layer deposition”), a hydrophobic layer 64 (e.g., diamond-like carbon (DLC)) is deposited on the exposed surface regions of the patterned mask 72 and the surface of the functional element 12. The deposited layer 64 is hydrophobic or less hydrophobic (having lower liquid wettability) compared to the material or surface properties of the functional element 12. In other words, the material or surface properties of the functional element 12 are hydrophilic or less hydrophobic (having higher liquid wettability) compared to the material of the deposited layer 64.

[0170] like Figure 15DIn the exemplary illustration (“stripping”), a patterned mask (with a hydrophobic layer thereon) is removed, wherein a patterned hydrophobic layer 64 is realized on the hydrophilic surface (wafer). A first surface structure 52 is formed on the exposed surface (layer) of the functional element 12 in a first sub-segment 50-1, wherein the patterned hydrophobic layer 64 forms a second surface structure 54 on a second sub-segment 50-2 of the total surface region 50 of the functional element 12.

[0171] therefore, Figure 15A -D illustrates a possible implementation of a fabrication method 100 based on a deposited patterned hydrophobic layer 64, which is used to provide a MEMS device 10 with functional elements 12 having local hydrophobicity gradients. More specifically, Figure 15A -D illustrates an inexpensive processing flow for providing a (relatively) large wettability gradient between the first sub-segment 50-1 and the second sub-segment 50-2 of the total surface area 50 of the functional element 12.

[0172] Figure 16A -C shows a schematic cross-sectional view of a MEMS device 10 having surface structures 52, 54 with functional elements 12 according to another embodiment of the present disclosure.

[0173] MEMS device 10 can be formed as an SBP (single backplane) structure (see example). Figure 1A However, it can also be formed as an SDM structure (see example). Figure 1B -C), formed as a DBP (dual backplane) structure, formed as a MEMS pressure sensor, or generally formed as a MEMS sensor or MEMS environmental sensor, wherein the MEMS device 10 includes a (deflectable) functional element 12 (e.g., having a membrane structure) in fluid connection with the environment.

[0174] according to Figure 16A The MEMS device 10 illustrated in -C includes, for example, a transducer element 12', a substrate 18, and an insulating structure 28.

[0175] In the case of SBP (single backplane) structure (see example) Figure 1A The transducer element 12' may include a deflectable diaphragm structure 14 and a rigid electrode structure 16. In the case of a dual-film MEMS microphone or a hermetically sealed dual-film (SDM) MEMS microphone (see, for example...), Figure 1B -C), the transducer element 12' may include deflectable (movable) and mechanically coupled membrane structures 14 and 15, rigid electrode structure 16, substrate 18 and insulating structure 28.

[0176] The substrate 18 has a through opening 18-1 (e.g., a so-called Bosch cavity) between the first main surface region 18-A (e.g., the front side) and the second main surface region 18-B (e.g., the back side). An insulating structure 28 is provided for securing the peripheral portion of the transducer element 12' to the substrate 18.

[0177] according to Figure 16A In the embodiment shown in -C, the MEMS device 10 includes a functional element 12 that is fluidly connected (communicating) with the environment "E". The functional element 12 includes a total surface region 50 having at least a first sub-segment 50-1 and an adjacent second sub-segment 50-2.

[0178] like Figure 16A As exemplarily shown in -C, the first surface structure 52 (e.g., a hydrophilic coating) of the first surface region 50-1 extends (is applied thereto) on the exposed inner surface (sidewall) 18-C of the substrate 18. Furthermore, the second surface structure 54 (e.g., a hydrophobic coating) of the second surface region 50-2 extends on the (exposed) second main surface region 12'-B (back side) of the transducer element 12', the exposed inner surface 28-A of the insulating structure 28, and the exposed portion of the first main surface region 18-A (front side) of the substrate 18.

[0179] The first sub-segment 50-1 of the total surface region 50 is configured to form a liquid collection area during a liquid drying event of the total surface region of the functional element 12, wherein the second sub-segment 50-2 of the total surface region 50 is configured to form a liquid repulsion area during a liquid drying event of the total surface region of the functional element 12.

[0180] like Figure 16B As exemplarily shown in -C, after immersing the functional element 12 of the MEMS device 10 in liquid 40 (e.g., tap water), surface contamination of the second (critical) sub-segment of the total surface area 50 can be avoided or at least significantly reduced (e.g., as a result of surface drying after exposure to the liquid), because the resulting liquid drying (e.g., the water drying characteristics of the functional element 12) will move the particles 48 away from the transducer element 12' into the Bosch cavity 18-1.

[0181] Figure 17A -E shows an exemplary schematic flowchart of a method 100 for manufacturing the surface structures 52, 54 of the functional elements 12 of a MEMS device 10 according to another embodiment of the present disclosure.

[0182] like Figure 17A As exemplarily illustrated, a semiconductor substrate (e.g., a Si substrate) 18 is provided, having a stack of an insulating structure 28 and an acoustic transducer structure 12' included on a first main surface region 18-A of the substrate. Figure 17AAs further shown, a through opening 18-1 (e.g., a so-called Bosch cavity) is formed (e.g., etched using a Bosch cavity) in the substrate 18 between the first main surface region 18-A (e.g., the front side) and the second main surface region 18-B (e.g., the back side).

[0183] like Figure 17B As exemplarily shown, back-side surface preparation (e.g., oxidation of the hydrophilic material or MVD (molecular vapor deposition)) is performed to apply the hydrophilic material layer 44 to the (exposed) second main surface region 28-B (back side) of the insulating structure 28, the exposed (lateral) inner surface 18-C of the substrate 18, and the exposed second main surface region 18-B (back side) of the substrate 18.

[0184] like Figure 17C As exemplarily illustrated, an etching process, such as full-area anisotropic plasma etching, is performed to remove the hydrophilic material layer 44 (SiO2 layer or MVD layer) from the (exposed) second main surface region 28-B (back side) of the insulating structure 28 and from the exposed second main surface region 18-B (back side) of the substrate 18. The hydrophilic material layer 44 (first surface structure 52) remains on the exposed (lateral) inner surface 18-C of the substrate 18.

[0185] like Figure 17D As exemplarily shown, etching (e.g., final release etching) is performed through the through opening 18-1 (Bosch cavity) to partially remove material from the insulating structure 28, thereby providing the remaining insulating structure 28 for securing the peripheral portion of the transducer element 12' to the substrate 18. A stable hydrophilic material layer 52 (first surface structure) remains on the exposed (lateral) inner surface 18-C of the substrate 18 during the release etching.

[0186] like Figure 17E As exemplarily shown, further back-side surface preparation (e.g., oxidation or MVD (molecular vapor deposition)) of a hydrophobic material (e.g., FDTS) is performed to apply a hydrophobic material layer 46 (a second surface structure 54, which is not grown on the hydrophilic material layer 44) to the (exposed) second main surface region 12'-B (back side) of the transducer element 12', the exposed (lateral) inner surface 28-A of the insulating structure 28, and the exposed first main surface region 18-A (front side) of the substrate 18.

[0187] Therefore, based on Figure 17A Method 100 of -E is implemented. Figure 16AThe functional element 12 of the MEMS device 10 of the -C, wherein the first surface structure 52 (e.g., a hydrophilic coating) of the second surface region 50-2 extends (is applied thereto) on the exposed (lateral) inner surface 18-C of the substrate 18. Furthermore, the second surface structure 54 (e.g., a hydrophobic coating) of the second surface region 50-2 extends on the (exposed) second main surface region 12'-B (back side) of the transducer element 12', the exposed (lateral) inner surface 28-A of the insulating structure 28, and the exposed first main surface region 18-A (front side) of the substrate 18.

[0188] Figure 17A Method 100 of -E provides a combination of hydrophilic and hydrophobic surface coatings for MEMS device 10 with acoustic transducer 12' to increase environmental robustness.

[0189] Additional embodiments and aspects are described that can be used alone or in combination with the features and functions described herein.

[0190] According to an embodiment, a MEMS device includes a functional element that is fluidly connected to an environment, wherein the functional element includes a total surface region having at least a first sub-segment and an adjacent second sub-segment, wherein the functional element is less susceptible to surface contamination in the first sub-segment of the total surface region than in the second sub-segment of the total surface region; and wherein the first sub-segment of the total surface region has a first surface structure having higher liquid wettability compared to a second surface structure of the second sub-segment of the total surface region.

[0191] According to an embodiment, the total surface area of ​​the functional element is configured such that surface contamination of the first sub-section caused by surface drying after exposure to liquid results in a smaller degradation of the electrical or mechanical properties of the functional element compared to the corresponding surface contamination of the second sub-section.

[0192] According to an embodiment, the total surface area includes morphological differences or gradients in the liquid contact angle over the total surface area, resulting in different liquid wettability in the first sub-segment and the second sub-segment.

[0193] According to an embodiment, a first sub-segment of the total surface area is configured to form a liquid collection area during a liquid drying event of the total surface area of ​​the functional element.

[0194] According to an embodiment, the functional element in the second sub-section includes at least one of an electrical operating element, a mechanical operating element, and / or a fluid operating element.

[0195] According to an embodiment, the first surface structure of the first sub-segment includes a lower liquid contact angle (LCA) compared to the second surface structure of the second sub-segment of the total surface region.

[0196] According to an embodiment, the first surface structure of the first surface sub-segment includes lower hydrophobic surface properties compared to the second surface structure of the second surface sub-segment.

[0197] According to an embodiment, the first surface structure of the first surface sub-segment includes higher hydrophilic surface properties compared to the second surface structure of the second surface sub-segment.

[0198] According to an embodiment, the first surface structure of the first surface sub-segment has hydrophilic surface properties, and the second surface structure of the second surface sub-segment has hydrophobic surface properties.

[0199] According to an embodiment, the first surface structure of the first surface sub-segment includes at least one of the following: nanopillars or micropillars of a substrate material that is hydrophilic compared to the second surface structure; locally deposited or patterned SAM (self-assembled monolayer); a surface structure selectively laser-treated; a nanoparticle structure (e.g., applied by inkjet printing); a nanocarbon coating (such as graphite or diamond-like carbon); a chemically modified nanocarbon coating; nanopatterning; nanopatterning combined with a liquid injector or lubricant injector; nanopatterning combined with a SAM coating; and a structure of printed hydrophobic nanoparticles or SAM.

[0200] According to an embodiment, the second surface structure of the second surface sub-segment includes at least one of the following: nanopillars or micropillars of a substrate material that is hydrophobic compared to the first surface structure, locally deposited or patterned SAM (self-assembled monolayer), selectively laser-treated surface structure, nanoparticle structure (e.g., applied by inkjet printing), nanocarbon coating (such as graphite or diamond-like carbon), chemically modified nanocarbon coating, nanopatterning, nanopatterning in combination with liquid injectors or lubricant injectors, nanopatterning in combination with SAM coating, and a structure of printed hydrophilic nanoparticles or SAM.

[0201] According to an embodiment, the manufacturing method includes the following steps: providing a MEMS device having functional elements that are fluidly connected to an environment, wherein the functional elements include a total surface region having a first sub-segment and an adjacent second sub-segment; and providing a first surface structure on the first sub-segment of the total surface region and a second surface structure on the second sub-segment, wherein the first surface structure on the first sub-segment has higher liquid wettability compared to the second surface structure on the second sub-segment of the total surface region.

[0202] According to an embodiment, the step of providing a first surface structure on a first sub-segment of the total surface region includes forming at least one of the following on the first sub-segment of the total surface region: nanopillars or micropillars, locally deposited or patterned SAM, selectively laser-treated surface structures, nanoparticle structures applied, for example by inkjet printing, nanocarbon coatings (such as graphite or diamond-like carbon), chemically modified nanocarbon coatings, nanopatterning, nanopatterning in combination with liquid injectors or lubricant injectors, nanopatterning in combination with SAM coatings, and structures of printed hydrophilic nanoparticles or SAM.

[0203] According to an embodiment, the step of providing a second surface structure on a second sub-segment of the total surface region includes forming at least one of the following on the second sub-segment of the total surface region: nanopillars or micropillars, locally deposited or patterned SAM, selectively laser-treated surface structures, nanoparticle structures, nanocarbon coatings (such as graphite or diamond-like carbon), chemically modified nanocarbon coatings, nanopatterning, nanopatterning in combination with liquid injectors or lubricant injectors, nanopatterning in combination with SAM coatings, and structures of printed hydrophobic nanoparticles or SAM.

[0204] According to an embodiment, the method further includes the step of forming a morphological difference or gradient of liquid contact angle over the total surface area to provide a first sub-segment and a second sub-segment with different liquid wettability.

[0205] Although some aspects have been described as features within the context of the device, it is obvious that such a description can also be considered a description of the corresponding features of the method.

[0206] Depending on the requirements of certain implementations, embodiments of the control circuitry may be implemented in hardware or software, or at least partially in hardware or at least partially in software. Typically, embodiments of the control circuitry may be implemented as a computer program product having program code that, when run on a computer, can be manipulated to perform one of the methods. The program code may, for example, be stored on a machine-readable medium.

[0207] As can be seen from the foregoing detailed description, various features are combined in the examples for the purpose of simplifying this disclosure. The approach of this disclosure should not be construed as reflecting an intention to require more features than are expressly recited in each claim. Rather, as reflected in the following claims, the subject matter may be present in fewer than all features of a single disclosed example. Therefore, the following claims are thus combined with the detailed description, wherein each claim may be presented independently as a separate example. While each claim may be presented independently as a separate example, it should be noted that although dependent claims may refer in the claims to a specific combination with one or more other claims, other examples may also include combinations of the subject matter of the dependent claim with each other dependent claim or combinations of each feature with other dependent or independent claims. Such combinations are presented herein unless indicated to imply no specific combination. Furthermore, even if a claim is not directly dependent on an independent claim, it is intended to include the features of that claim in any other independent claim.

[0208] Although specific embodiments have been shown and described herein, those skilled in the art will understand that various alternatives and / or equivalent implementations may be used to replace the specific embodiments shown and described without departing from the scope of these embodiments. This application is intended to cover any modifications or variations of the specific embodiments discussed herein. Therefore, the embodiments are intended to be limited only by the claims and their equivalents.

Claims

1. MEMS devices (10), including: Functional element (12), in fluid connection with the environment, The functional element (12) includes a total surface area (50) having at least a first sub-segment (50-1) and an adjacent second sub-segment (50-2). The functional element (12) is less susceptible to surface contamination (48) in the first sub-segment (50-1) of the total surface area (50) than in the second sub-segment (50-2) of the total surface area (50); and The first sub-segment (50-1) of the total surface region (50) has a first surface structure (52) which has higher liquid wettability than the second surface structure (54) of the second sub-segment (50-2) of the total surface region (50).

2. The MEMS device (10) according to claim 1, wherein the total surface area (50) of the functional element (12) is configured such that, compared with the corresponding surface contamination (48) of the second sub-segment (50-2), the surface contamination (48) of the first sub-segment (50-1) caused by the surface drying of the functional element (12) after exposure to the liquid (40) results in a smaller degradation of the electrical or mechanical properties of the functional element (12).

3. The MEMS device (10) according to claim 1 or 2, wherein the total surface area (50) includes morphological differences or gradients of liquid contact angles on the total surface area (50), resulting in the first sub-segment (52) and the second sub-segment (54) having different liquid wettability.

4. The MEMS device (10) according to any one of the preceding claims, wherein the first sub-segment (50-1) of the total surface area (50) is configured to form a liquid collection area during a liquid drying event of the total surface area (50) of the functional element (12).

5. The MEMS device (10) according to any one of the preceding claims, wherein the functional element (12) in the second surface sub-section (50-2) includes at least one of an electrical operating element, a mechanical operating element and / or a fluid operating element (13).

6. The MEMS device (10) according to any one of the preceding claims, wherein the first surface structure (52) of the first surface sub-segment (50-1) includes a lower liquid contact angle (LCA) than the second surface structure (54) of the second sub-segment (50-2) of the total surface region (50).

7. The MEMS device (10) according to any one of the preceding claims, wherein the first surface structure (52) of the first surface sub-segment (50-1) has lower hydrophobic surface properties than the second surface structure (54) of the second surface sub-segment (50-2).

8. The MEMS device (10) according to any one of the preceding claims, wherein the first surface structure (52) of the first surface sub-segment (50-1) has higher hydrophilic surface properties than the second surface structure (54) of the second surface sub-segment (50-2).

9. The MEMS device (10) according to any one of the preceding claims, wherein the first surface structure (52) of the first surface sub-segment (50-1) has hydrophilic surface properties, and the second surface structure (54) of the second surface sub-segment (50-2) has hydrophobic surface properties.

10. The MEMS device (10) according to any one of the preceding claims, wherein the first surface structure (52) of the first surface sub-segment (50-1) comprises at least one of the following: Compared to the second surface structure, the hydrophilic substrate material has nanopillars or micropillars. Locally deposited or patterned self-assembled monolayer SAM, Surface structures selectively laser-treated, For example, nanoparticle structures applied via inkjet printing. Nanoscale carbon coatings, such as graphite or diamond-like carbon, Chemically modified nano-carbon coating, Nanopatterning, Nanopatterning in combination with liquid or lubricant injectors, Nanopatterning combined with SAM coating, and The structure of printed hydrophobic nanoparticles or SAM.

11. The MEMS device (10) according to any one of the preceding claims, wherein the second surface structure (54) of the second surface sub-segment (50-2) comprises at least one of the following: Compared to the first surface structure, the hydrophobic substrate material consists of nanopillars or micropillars. Locally deposited or patterned self-assembled monolayer SAM, Surface structures selectively laser-treated, For example, nanoparticle structures applied via inkjet printing. Nanoscale carbon coatings, such as graphite or diamond-like carbon, Chemically modified nano-carbon coating, Nanopatterning, Nanopatterning in combination with liquid or lubricant injectors, Nanopatterning combined with SAM coating, and The structure of printed hydrophilic nanoparticles or SAM.

12. A manufacturing method (100), comprising: Provided (110) a MEMS device having functional elements fluidly connected to an environment, wherein the functional elements include a total surface area having a first sub-segment and an adjacent second sub-segment, and A first surface structure (120) is provided on a first sub-segment of the total surface region, and a second surface structure (120) is provided on a second sub-segment of the total surface region, wherein the first surface structure on the first sub-segment has higher liquid wettability than the second surface structure on the second sub-segment of the total surface region.

13. The method (100) of claim 12, wherein the step of providing (120) a first surface structure on the first sub-segment of the total surface region comprises forming at least one of the following on the first sub-segment of the total surface region: Nanopillars or micropillars Locally deposited or patterned SAM, Surface structures selectively laser-treated, For example, nanoparticle structures applied via inkjet printing. Nanoscale carbon coatings, such as graphite or diamond-like carbon, Chemically modified nano-carbon coating, Nanopatterning, Nanopatterning in combination with liquid or lubricant injectors, Nanopatterning combined with SAM coating, and The structure of printed hydrophilic nanoparticles or SAM.

14. The method (100) according to claim 12 or 13, wherein the step of providing (120) a second surface structure on the second sub-segment of the total surface region comprises forming at least one of the following on the second sub-segment of the total surface region: Nanopillars or micropillars Locally deposited or patterned SAM, Surface structures selectively laser-treated, Nanoparticle structure, Nanoscale carbon coatings, such as graphite or diamond-like carbon, Chemically modified nano-carbon coating, Nanopatterning, Nanopatterning in combination with liquid or lubricant injectors, Nanopatterning combined with SAM coating, and The structure of printed hydrophobic nanoparticles or SAM.

15. The method (100) according to any one of claims 12 to 14, further comprising: The morphological differences or gradients of the liquid contact angle are formed on the total surface area to provide the first sub-segment and the second sub-segment with different liquid wettability.

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