MEMS devices

Abstract

A micro-electromechanical systems (MEMS) device comprises a flexible membrane disposed over a substrate and a first backplate disposed over the flexible membrane. The first backplate comprises a first plurality of bumps facing the flexible membrane. The MEMS device further comprises a plurality of features disposed on the flexible membrane, wherein each of the plurality of features is associated with a corresponding one of the first plurality of bumps.

Description

Technology Field

[0001] The present invention generally relates to electronic devices, and in certain embodiments, to structures for microelectrical mechanical systems (MEMS) devices. Background Technology

[0002] Sensors are devices containing transducing elements. Transducers are employed within electronic devices to convert signals from one domain to another. For example, some transducers can convert mechanical signals into electrical signals. Acoustic microphones containing transducing elements that convert sound waves into electrical signals are an example of this. Information from electronic signals is collected and then transmitted to a signal processor that decodes the received signals and delivers the output through reading mechanisms within the sensing device.

[0003] MEMS-based sensors include various transducers such as accelerometers, oscillators, resonators, gyroscopes, and microphones. MEMS-based sensors are fabricated using various microfabrication techniques similar to those used in the manufacture of integrated circuits.

[0004] Conventional electrostatic MEMS microphones utilize capacitive behavior to transduce physical stimuli, such as speech, into electrical signals. In these applications, capacitive changes in the sensor are converted into voltage signals using interface circuits. These MEMS devices consist of a flexible membrane structure arranged parallel to a rigid backplate structure. Together, they function as two electrode plates within the capacitive MEMS device. As sound waves penetrate through cavities within the device, they induce oscillations between the flexible membranes due to pressure differences. This ultimately causes variability in the distance of the air gap between the flexible membrane and the backplate. Consequently, variations in the air gap between the flexible membrane and the backplate are directly proportional to changes in the capacitance of the MEMS device.

[0005] Often, when this deflection occurs between the flexible membrane and the backplate, electrostatic forces buildup can cause the two surfaces to stick together when they come into contact. To mitigate this, anti-sticking bumps are fabricated within the bottom surface of the backplate and are therefore positioned between the two electrode surfaces. These anti-sticking bumps serve the purpose of maintaining a certain working distance between the flexible membrane and the backplate to reduce the amount of contact area between the two electrode surfaces. means of solving the problem

[0006] According to an embodiment of the present invention, a micro-electromechanical systems (MEMS) device comprises a flexible membrane disposed above a substrate and a first backplate disposed above the flexible membrane. The first backplate comprises a first plurality of bumps facing the flexible membrane. The MEMS device further comprises a plurality of features disposed on the flexible membrane, wherein each of the plurality of features is associated with a corresponding one of the first plurality of bumps.

[0007] According to another embodiment of the present invention, a microelectromechanical systems (MEMS) device comprises a deflectable layer disposed above a substrate and a first backplate disposed above the deflectable layer. The first backplate comprises a first plurality of anti-sticking structures facing the deflectable layer. The MEMS device further comprises a plurality of reinforcement regions disposed in the deflectable layer, wherein the plurality of reinforcement regions are configured to reinforce the deflectable layer against stress-induced failure, and the plurality of reinforcement regions are associated with a corresponding one of the first plurality of anti-sticking structures.

[0008] According to another embodiment of the present invention, a micro-electromechanical systems (MEMS) device comprises a first backplate comprising a first plurality of anti-sticking bumps, and a flexible membrane comprising a first main surface and a second main surface opposite, a second plurality of anti-sticking bumps on the first main surface, and a plurality of features on the second main surface. Each of the plurality of features is associated with a corresponding one of the second plurality of anti-sticking bumps. The MEMS device further comprises a second backplate, wherein the flexible membrane is disposed between the first backplate and the second backplate. Brief explanation of the drawing

[0009] For a more complete understanding of the present invention and its advantages, reference is now made to the following description taken together with the accompanying drawings; FIG. 1a illustrates a cross-sectional view of an embodiment of a MEMS microphone in which additional material is deposited on the top of a flexible membrane at the level of bumps, wherein FIG. 1b represents an enlarged portion of the dashed area illustrated by FIG. 1a; FIG. 2a illustrates a cross-sectional view of an embodiment of a MEMS microphone in which alternative embodiments for a side profile are illustrated, wherein FIG. 2b and FIG. 2c represent enlarged portions of the dashed regions illustrated by FIG. 2a; FIG. 3 illustrates a cross-sectional view of an embodiment of a MEMS microphone in which additional material is not only deposited on the top surface but is also placed under a flexible membrane at the level of the bumps; FIG. 4 illustrates a cross-sectional view of an embodiment of a MEMS microphone in which an additional material attached to the top of a stretchable membrane is made of the same material; FIG. 5 illustrates a cross-sectional view of an embodiment of a MEMS microphone in which an additional material disposed beneath a flexible membrane is made of the same material; FIG. 6a illustrates a cross-sectional view of an embodiment of a MEMS microphone in which sections of a stretchable membrane are replaced by an alternative material, wherein FIG. 6b represents an enlarged portion of the dashed area illustrated by FIG. 6a; and FIG. 7 illustrates a cross-sectional view of an embodiment of a dual-plate type MEMS microphone comprising an additional material deposited on top of the elastic membrane as well as anti-sticking bumps added below the elastic membrane, wherein the additional material is deposited on top of the anti-sticking bumps of the membrane. Specific details for implementing the invention

[0010] The structure and use of various embodiments of MEMS microphones are discussed in detail below. However, it should be appreciated that the various embodiments described herein may be applicable in a wide variety of disciplines. The specific embodiments described herein are merely illustrative of specific ways of manufacturing and using the various embodiments and should not be interpreted in a limited scope.

[0011] Conventional MEMS devices, such as microphones, are susceptible to damage from dust and particles during operation or assembly. For example, random particles traveling at sufficiently high velocities can damage electrodes. These high-velocity particles can be generated in many ways. For instance, mechanical shock can eject loosely attached, or otherwise latent, particles within the duct between the device exterior and the port. Similarly, particles suspended in the air can be accelerated toward the microphone during device assembly or during the air-gun cleaning process after packaging.

[0012] The inventors of this application have determined that the stretchable membrane is a significantly sensitive part of the microphone due to stress induced by particles. In particular, the inventors of this application have determined that areas of the stretchable membrane designed to contact anti-sticking bumps are more sensitive due to stress concentration in small areas. Embodiments of the present invention describe MEMS devices that are optionally more immune to failure due to particle damage, for example, by forming additional features on the plates of the MEMS devices as well as the stretchable membrane.

[0013] The structural design of the MEMS device will first be described using FIGS. 1a to 1b and FIGS. 2a to 2c. Alternative designs of the MEMS device will then be described using FIGS. 3 to 7.

[0014] FIG. 1a illustrates a cross-sectional view of an embodiment of a MEMS microphone, wherein FIG. 1b represents an enlarged portion of the dashed area illustrated by FIG. 1a.

[0015] Referring to FIG. 1a, in one or more embodiments, a micro-electromechanical systems (MEMS) device (100) comprises a substrate (101), a first clamping layer (102) and a second clamping layer (104), a flexible membrane (103), and a first backplate (105). In one embodiment, the MEMS device (100) is a microphone.

[0016] FIG. 1b shows an enlarged portion of the MEMS device (100) indicated by the dashed area in FIG. 1a. In these embodiments, the flexible membrane (103) is a deflectable sensing membrane that forms a parallel plate capacitor with the first backplate (105). Sound pressure waves are incident on the flexible membrane (103) from a cavity (112) connected to a sound port (not shown) in the MEMS microphone. During operation, sound pressure waves incident from the cavity (112) can cause oscillations in the flexible membrane (103) toward and away from the first backplate (105), thereby changing the distance between the flexible membrane (103) and the first backplate (105), which ultimately changes the capacitance between the flexible membrane (103) and the first backplate (105). For example, the change in capacitance can be detected by reading electronic devices coupled to the flexible membrane (103) and the first backplate (105) through conductive lines (not shown).

[0017] A first backplate (105) positioned above the elastic membrane (103) is a rigid layer. In one embodiment, the first backplate (105) comprises a first insulating layer (108) and a second insulating layer (110), a conductive layer (109), and a first plurality of bumps (107). The first plurality of bumps (107) serve as anti-sticking bumps to mitigate sticking caused by electrostatic forces that may be induced when the elastic membrane (103) comes into contact with the first backplate (105). The anti-sticking bumps contribute to maintaining a certain distance between the first backplate (105) and the elastic membrane (103), thereby assisting in reducing surface contact. According to some embodiments, the first backplate (105) may include perforations (106) of varying diameter sizes ranging from small to large. The perforations (106) may serve as release holes during the etch manufacturing step in which portions of the second clamping layer (104) are removed. In one or more embodiments, the perforations (106) may include numerous small diameter holes arranged closely together and around the perimeter of the deflectable portion of the elastic membrane (103). The spacing and size of the perforations (106) may be used to control both the position and smoothness of the second clamping layer (104) and the second clamping layer edges (113), respectively.

[0018] According to various embodiments, the substrate (101) may be made of a silicon material or any other material that can be used to form a support substrate structure for various layers within a MEMS device (100).

[0019] A cavity (112) is formed within the substrate (101). In various embodiments, the cavity (112) may be formed using an etch manufacturing technique, such as Bosch process etch, which creates scalloped edges along the substrate sidewall (115). The elastic membrane (103) may include a fixed portion supported by a first clamping layer (102) and a second clamping layer (104), and a non-fixed portion disposed above the cavity (112). According to various embodiments, the elastic membrane (103) may be made of any conductive material, such as doped polysilicon.

[0020] A first clamping layer (102) is disposed on a substrate (101). In some embodiments, the substrate sidewall (115) of the substrate (101) may extend past the first clamping layer edge (114). Alternatively, in other embodiments, the first clamping layer edge (114) may extend past the substrate sidewall (115) into a cavity (112). In some embodiments, the first clamping layer (102) may be made of an insulating material such as tetraethyl orthosilicate (TEOS) oxide. Alternatively, the first clamping layer (102) may be formed of any other insulating material such as another oxide or dielectric.

[0021] The second clamping layer (104) is placed over the elastic membrane (103) and effectively fits as a support structure by "clamping" a fixed portion of the elastic membrane (103). In various embodiments of the MEMS device (100), the first and second clamping layers (102 and 104) may be rearranged so that the first clamping layer (102) extends beyond the substrate sidewall (115) and into the cavity (112), wherein the second clamping layer (104) does not extend beyond the substrate sidewall (115). In some embodiments, the second clamping layer (104) may be thicker than the first clamping layer (102), and vice versa. Similar to the first clamping layer (102), the second clamping layer (104) may be made of an insulating material such as tetraethyl orthosilicate (TEOS) oxide or any other oxide or dielectric.

[0022] The first backplate (105) is formed on the top of the second clamping layer (104) and, as described, comprises a first insulating layer (108), a conductive layer (109), and a second insulating layer (110). In one embodiment, the first and second insulating layers (108 and 110) are formed as silicon nitride layers. However, the conductive layer (109) is formed as a doped polysilicon layer. Generally, the first backplate (105) can be manufactured from any combination of insulating or conductive materials known in the art. The air gap existing between the first backplate (105) and the elastic membrane (103) can typically have a distance ranging from 500 nm to 5 μm. As previously described, the first backplate (105) also includes a first plurality of bumps (107) that serve as anti-sticking bumps to alleviate sticking caused by electrostatic forces that may be induced when the elastic membrane (103) comes into contact with the first backplate (105). These first plurality of bumps (107) are made of layers from the second insulating layer (110) and the conductive layer (109) of the first backplate (105). Thus, in one embodiment of the MEMS device (100), the first plurality of bumps (107) may be made of a layer of silicon nitride and a layer of doped polysilicon. In other embodiments, the first plurality of bumps (107) may be made from any other combination of insulating or conductive materials known in the art. The first plurality of bumps (107) may have a size of 100 nm to 2000 nm in height and may have a variablely sharp tip with a radius of curvature ranging from 10 nm to 1000 nm. Likewise, the first plurality of bumps (107) may have a flatter tip near a size of 50 nm to 500 nm.

[0023] As illustrated in FIGS. 1a and 1b, a first plurality of features (111a) are disposed on a flexible membrane (103). The first plurality of features (111a) include protrusions extending from the flexible membrane (103) in a direction toward the first plurality of bumps (107). Each of the first plurality of features (111a) is associated with a corresponding one of the first plurality of bumps (107). The first plurality of features (111a) include protrusions extending from the flexible membrane (103) in a direction toward the first plurality of bumps (107). According to some embodiments, (as illustrated in FIGS. 1a and 1b) the first plurality of features (111a) may comprise a material different from the flexible membrane (103).

[0024] Each of the first plurality of features (111a) includes sidewalls orthogonal to the main outer surface of the elastic membrane (103). According to some embodiments, (as shown in FIG. 1a and FIG. 1b) the first plurality of features (111a) may be made of a material different from the material of the elastic membrane (103).

[0025] In various embodiments, the first plurality of features (111a) comprises a material that is more immune to cracking than the elastic membrane (103) and, in particular, has a higher fracture toughness than the elastic membrane (103). For example, the elastic membrane made of polysilicon has a fracture toughness Kc of about 1 MPa.sqrt(m). However, in one or more embodiments, materials having similar or even lower fracture toughness (e.g., silicon oxide) may be used, as the thickness increase provided by the first plurality of features (111a) helps dissipate stress energy within the first plurality of features (111a) and thereby prevents stress energy from reaching the elastic membrane (103). This is because the cracks formed on the first plurality of features (111a) do not have a functional effect on the operation of the MEMS device, unlike the cracks on the elastic membrane (103).

[0026] In various embodiments, the material of the first plurality of features (111a) is more rigid than the elastic membrane (103) to help minimize deformation of the elastic membrane (103) placed underneath. Due to the higher rigidity of the first plurality of features (111a), it is less susceptible to stress-induced failure. Accordingly, excessive stress applied by the first plurality of bumps, which would otherwise have caused cracking of the elastic membrane, is absorbed by the first plurality of features (111a), thereby minimizing damage to the elastic membrane (103).

[0027] Accordingly, the first plurality of features (111a) may be made of silicon nitride layers (SiN), silicon oxide layers (SiO2), silicon carbide layers (SiC), or any other combination of insulating materials known in the art.

[0028] In various embodiments, the first plurality of features (111a) may be formed through conventional microfabrication methods. For example, an insulating material such as those mentioned above may be applied to the top surface of the flexible membrane (103). The first plurality of features (111a) may be formed through various photolithographic and etching steps combined with additional microfabrication processing methods known to those skilled in the art, such as cleaning and flattening.

[0029] FIG. 2a illustrates a cross-sectional view of an embodiment of a MEMS device (100) in which alternative embodiments for a side profile of a first plurality of features (111a) are illustrated. FIG. 2b and FIG. 2c represent enlarged portions of the dashed regions illustrated by FIG. 2a.

[0030] As described above, the edges of the first plurality of features (111a) can be etched in a manner that achieves a vertical sidewall profile (as illustrated in FIG. 2b). In other embodiments of the MEMS device (100), the sidewalls (111c) of the first plurality of features (111a) can be etched in a manner that achieves a more angled sidewall profile (as illustrated in FIG. 2c). The rationale behind this is that a more angled sidewall profile for the first plurality of features (111a) reduces the concentration of sustained stress at the interface where the edges of the first plurality of features (111a) meet the top surface of the elastic membrane (103) (indicated by the arrows in FIG. 2b).

[0031] The first plurality of features (111a) may have a thickness ranging from 10 nm to 1 μm and may have a lateral dimension of about 500 nm to 5 μm, which is larger than the lateral dimension of the contact area of ​​the first plurality of bumps (107).

[0032] FIG. 3 illustrates a cross-sectional view of an alternative embodiment of a MEMS device (200). In this particular embodiment of the MEMS microphone, a material is not only deposited on the top of the flexible membrane in the form of a first plurality of features (111a) (as described above), but an identical or similar insulating material is additionally disposed below the flexible membrane (103) in the form of a second plurality of features (111b).

[0033] The second plurality of features (111b) placed beneath the elastic membrane (103) provide additional reinforcement for the elastic membrane (103), which would otherwise be brittle. Additionally, the second plurality of features (111b) balance stress induced by additional material on the elastic membrane (103).

[0034] FIG. 4 illustrates a cross-sectional view of an embodiment of a MEMS device (400).

[0035] In this embodiment, the third plurality of features (111d) attached to the top of the elastic membrane (103) may be made of the same material as the elastic membrane (103). In other words, in this embodiment, the portions of the elastic membrane (103) that are more likely to be sensitive to stress-induced failure are made thicker.

[0036] Accordingly, additional material added to the elastic membrane (103) can be conceived as a local thickening of the membrane material. The third plurality of features (111d) can be manufactured using similar manufacturing techniques adopted for the composition of the first plurality of features (111a). Alternatively, in some embodiments, the third plurality of features (111d) can be formed together with the elastic membrane (103), wherein regions not having the third plurality of features (111d) are recessed.

[0037] FIG. 5 illustrates a cross-sectional view of an embodiment of a MEMS device (500).

[0038] In this embodiment, additional material is disposed on the bottom of the elastic membrane (103) as a fourth plurality of features (111e) which may also be made of the same material as the elastic membrane (103). Advantageously, this embodiment reinforces the elastic membrane (103) without any change in capacitance between the elastic membrane (103) and the first backplate (105).

[0039] As previously discussed, the fourth plurality of features (111e) may be manufactured using similar manufacturing techniques adopted for the construction of the first plurality of features (111a). Alternatively, the fourth plurality of features (111e) may be formed together with a stretchable membrane (103), wherein regions not having the fourth plurality of features (111e) are recessed.

[0040] FIG. 6a illustrates a cross-sectional view of an embodiment of a MEMS device (600), while FIG. 6b illustrates an enlarged portion of the dashed area illustrated by FIG. 6a. In this embodiment, sections of the elastic membrane (103) at the level of the first plurality of bumps (107) are replaced by an alternative reinforcing material in the form of a fifth plurality of features (111f). The fifth plurality of features (111f) may be made of a material different from that of the elastic membrane (103). In various embodiments, the fifth plurality of features (111f) comprise a material that is more immune to cracking than the elastic membrane (103), and in particular, has higher fracture toughness than the elastic membrane (103). The fifth plurality of features (111f) may comprise materials that are more rigid than the elastic membrane (103). For example, the fifth plurality of features (111f) may be made of silicon nitride layers (SiN), silicon oxide layers (SiO2), silicon carbide layers (SiC), TiN, TaN, and others.

[0041] Each of the fifth plurality of features (111f) includes sidewalls that may be orthogonal to the main outer surface of the elastic membrane (103) or may have an inclination to the main outer surface. The fifth plurality of features (111f) includes a first portion filled within through holes in the elastic membrane (103). A second annular region extends above a portion of the top surface of the elastic membrane (103). The second annular region may include protrusions extending from the elastic membrane (103) in a direction toward the first plurality of bumps (107).

[0042] The fifth plurality of features (111f) can be constructed using conventional micromanufacturing methods, many of which are described herein in various embodiments.

[0043] FIG. 7 illustrates a cross-sectional view of an embodiment of a MEMS device, which is a dual backplate MEMS microphone.

[0044] The dual backplate MEMS microphone design provides a differential MEMS sensor. Thus, the dual backplate MEMS microphone outputs two symmetrical 180-degree phase-shifted signals due to the movement of the flexible membrane.

[0045] Unlike previous embodiments, this embodiment includes a different design for anti-stick bumps and protrusions due to the additional backplate. In one or more embodiments, the anti-stick bumps and protrusions on the elastic membrane (205) can be directly aligned in a vertical direction.

[0046] Similar to previous embodiments, the MEMS device (700) comprises a substrate (201), first, second, and third clamping layers (202, 204, and 206), a bottom backplate (203), a flexible membrane (205), and a top backplate (207). According to various embodiments, the flexible membrane (205) is positioned between the bottom backplate (203) and the top backplate (207). The first clamping layer (202) is positioned between the substrate (201) and the bottom backplate (203). The second clamping layer (204) is positioned between the bottom backplate (203) and the flexible membrane (205). The third clamping layer (206) is positioned between the flexible membrane (205) and the top backplate (207). According to an embodiment of the MEMS device (200), the elastic membrane (205) separates the lower cavity (215a) from the upper cavity (215b).

[0047] Similar to previous embodiments, some of the clamping layers may be retracted further inward than the substrate edge (216) and / or other clamping layers within the device. For example, in one embodiment, the second clamping layer (204) extends further into the bottom cavity (215a) than its other corresponding portions, namely the first clamping layer (202) and the third clamping layer (206). In various embodiments, the extension of the first, second, and third clamping layers (202, 204, and 206) may be determined by the size and location of the perforations (208) made within the bottom and top backplates (203 and 207).

[0048] Details regarding the functionality and characteristics of the perforations (208) may be referenced above for the perforations (106) described in the discussions regarding the single backplate MEMS device in FIG. 1a. In some embodiments, some clamping layers may be thicker than other clamping layers. For example, in one embodiment, the first clamping layer (202) may be much thinner than the second clamping layer (204) or the third clamping layer (206).

[0049] According to various embodiments, the substrate (201) may be made of a silicon material or any other material that can be used to form a support substrate structure for various layers within the MEMS device (200). A bottom cavity (215a) is formed within the substrate (201) as previously described. The first, second, and third clamping layers (202, 204, and 206), discussed in earlier references, are used as support structures for various layers within the MEMS device (200). More specifically, the first, second, and third clamping layers (202, 204, and 206) help to provide support for the bottom and top backplates (203 and 207) as well as the elastic membrane (205). The first, second, and third clamping layers (202, 204, and 206) may be made of an insulating material such as tetraethyl orthosilicate (TEOS) oxide in some embodiments. Alternatively, the first, second, and third clamping layers (202, 204, and 206) may be formed of any other insulating material such as another oxide or dielectric.

[0050] A bottom backplate (203) positioned between the first clamping layer (202) and the second clamping layer (204) is a rigid structure composed of first and second insulating layers (210 and 212) and a conductive layer (211). According to some embodiments, the bottom backplate (203) may also include perforations (208) of various diameters ranging from small to large, together with connecting members (231). As previously discussed, the perforations (208) may serve as release holes for the etch manufacturing step. In various embodiments, the perforations (208) may include numerous small-diameter perforations arranged closely together and around the periphery of the deflectable portion of the elastic membrane (205). The spacing and size of the perforations (208) may be used to control both the position and the smoothness of any adjacent clamping layer edges.

[0051] The top backplate (207) positioned on the third clamping layer (206) may also be a rigid structure composed of the first and second insulating layers (210 and 212) and the conductive layer (211).

[0052] Similar to previous embodiments, the top backplate (207) may include a first plurality of anti-sticking bumps (209) that minimize adhesion with the elastic membrane (205). The first plurality of anti-sticking bumps (209) are composed of layers from the second insulating layer (212) and the conductive layer (211) of the top backplate (207). Therefore, in an embodiment, the first plurality of anti-sticking bumps (209) may be composed of a layer of silicon nitride and a layer of doped polysilicon. In other embodiments, the first plurality of anti-sticking bumps (209) may be manufactured from any other combination of insulating or conductive materials known in the art. Very similar to the bottom backplate (203), the top backplate (207) may also include perforations (208) of various diameters.

[0053] The first plurality of anti-stick bumps (209) are shown aligned with the plurality of features (213), but in various embodiments, they may be located in other areas of the upper backplate (207). In contrast, in various embodiments, the second plurality of anti-stick bumps (214) are aligned with the connecting members (231) rather than the perforations (208) on the lower backplate (203).

[0054] Embodiments of the MEMS device (700) include a flexible membrane (205) positioned between a lower backplate (203) and an upper backplate (207); more specifically, between second and third clamping layers (204 and 206). The flexible membrane (205) includes a first main surface (214s) and an opposite second main surface (213s).

[0055] A second plurality of anti-sticking bumps (214) are disposed on the first main surface (214s). The second plurality of anti-sticking bumps (214) relieve adhesion of the elastic membrane (205) to the bottom backplate (203). The inventors of this application have identified that the portion of the second main surface (213s) overlaying the second plurality of anti-sticking bumps (214) is a point having a high stress intensity after particle impact. Therefore, a sixth plurality of features (213) are disposed on the elastic membrane (205) to overlap perpendicularly with the second plurality of anti-sticking bumps (214).

[0056] As in previous embodiments, the sixth plurality of features (213) include protrusions extending from the second main surface (213s) of the elastic membrane (205) in a direction toward the first plurality of anti-sticking bumps (209). Each of the sixth plurality of features (213) is associated with a corresponding one of the second plurality of anti-sticking bumps (214). However, since the sixth plurality of features (213) overlap perpendicularly with the second plurality of anti-sticking bumps (214), they do not overlap with the first plurality of anti-sticking bumps (209), but rather are staggered with respect to the first plurality of anti-sticking bumps (209).

[0057] Similar to previous embodiments, each of the sixth plurality of features (213) may include sidewalls orthogonal to the main outer surface of the elastic membrane (205) (e.g., as previously discussed in FIG. 2b). However, in other embodiments, each of the sixth plurality of features (213) may include angled sidewalls (as illustrated in FIG. 2c) to relieve the accumulation of concentrated stress on the main outer surface of the elastic membrane (205).

[0058] According to some embodiments, the sixth plurality of features (213) may be made of a material different from the material of the elastic membrane (205). As in previous embodiments, the sixth plurality of features (213) may be made of silicon nitride layers (SiN), silicon oxide layers (SiO2), silicon carbide layers (SiC), or other insulating materials.

[0059] In various embodiments, the sixth plurality of features (213) may be formed through conventional microfabrication processes. For example, an insulating material such as those mentioned above may be applied to the top surface of the stretchable membrane (205). The formation of the sixth plurality of features (213) is revealed through various photolithographic and etching steps combined with additional microfabrication processing methods known in the art, such as cleaning and planarization. As previously noted, the edges of the sixth plurality of features (213) may be etched in a manner that achieves a vertical sidewall profile (as illustrated in FIG. 2b). In other embodiments, the edges of the sixth plurality of features (213) may be etched in a manner that achieves a more angled sidewall profile (as illustrated in FIG. 2c). The sixth plurality of features (213) may have a thickness ranging from 10 nm to 1 μm and may have a transverse dimension of about 500 nm to 5 μm, which is larger than the transverse dimension of the contact area of ​​the first plurality of anti-sticking bumps (209).

[0060] The second plurality of anti-sticking bumps (214) may be manufactured using similar manufacturing techniques described herein; and may also include the same material used for the elastic membrane (205).

[0061] The advantages of the various embodiments described herein may include devices exhibiting improved toughness against impact and loud sound pressure waves. Additionally, improvements may be shown with respect to membranes that become particularly sensitive when particles strike near anti-stick bumps, causing highly destructive stress during the deflection of the elastic membrane. The various embodiments described herein avoid destructive damage to the layers of the MEMS microphone, particularly by reinforcing the elastic membrane to be tougher in areas near any anti-stick bumps.

[0062] Examples of one embodiment of the invention are summarized herein. Other embodiments may also be understood from the claims filed herein as well as from the entire specification.

[0063] Example 1. A microelectromechanical systems (MEMS) device comprises: a flexible membrane disposed over a substrate; a first backplate disposed over the flexible membrane—the first backplate comprises a first plurality of bumps facing the flexible membrane—; and a plurality of features disposed on the flexible membrane—each of the plurality of features is associated with a corresponding one of the first plurality of bumps.

[0064] Example 2. As a MEMS device of Example 1, a plurality of features are aligned with a corresponding one of the first plurality of bumps.

[0065] Example 3. As a MEMS device of either Example 1 or 2, a plurality of features include locally thicker regions of a stretchable membrane.

[0066] Example 4. A MEMS device of any one of Examples 1 to 3, wherein a plurality of features include protrusions extending from a flexible membrane in a direction toward a first plurality of bumps.

[0067] Example 5. A MEMS device of any one of Examples 1 to 4, wherein a plurality of features include protrusions extending from a flexible membrane in a direction away from a first plurality of bumps.

[0068] Example 6. As a MEMS device of any one of Examples 1, 2, 4, and 5, a plurality of features include a material different from a stretchable membrane.

[0069] Example 7. As a MEMS device of any one of Examples 1 to 6, a plurality of features are disposed above a flexible membrane and are disposed between the flexible membrane and a first plurality of bumps.

[0070] Example 8. A MEMS device of any one of Examples 1 to 7, wherein a plurality of features comprises: a first set of regions disposed above a stretchable membrane and located between the stretchable membrane and a first plurality of bumps; and a second set of regions disposed below the stretchable membrane, wherein the stretchable membrane is disposed between the second set of regions and the first plurality of bumps.

[0071] Example 9. As a MEMS device of any one of Examples 1, 2, 4, 6, and 7, a plurality of features are disposed within a flexible membrane.

[0072] Example 10. A MEMS device of any one of Examples 1 to 9 further comprises: a second backplate disposed between a flexible membrane and a substrate; and a second plurality of bumps disposed on the flexible membrane, wherein the plurality of features are aligned with a corresponding one of the second plurality of bumps.

[0073] Example 11. As a MEMS device of any one of Examples 1 to 10, each of the first plurality of features comprises sidewalls inclined to the main outer surface of the stretchable membrane.

[0074] Example 12. A MEMS device of any one of Examples 1 to 11, wherein each of the first plurality of features comprises sidewalls orthogonal to the main outer surface of the stretchable membrane.

[0075] Example 13. A microelectromechanical systems (MEMS) device comprises: a deflectable layer disposed above a substrate; a first backplate disposed above the deflectable layer—the first backplate comprises a first plurality of anti-sticking structures facing the deflectable layer—and a plurality of reinforcing regions disposed in the deflectable layer—the plurality of reinforcing regions are configured to reinforce the deflectable layer from stress-induced failure, and the plurality of reinforcing regions are associated with a corresponding one of the first plurality of anti-sticking structures.

[0076] Example 14. As a MEMS device of Example 13, a plurality of reinforcement regions include regions of locally thicker deflectable layers.

[0077] Example 15. As a MEMS device of Example 13, a plurality of reinforcing regions include a material different from the deflectionable layer.

[0078] Example 16. As a MEMS device of any one of Examples 13 to 15, a plurality of reinforcement regions are disposed within a deflectable layer.

[0079] Example 17. A microelectromechanical systems (MEMS) device comprises: a first backplate comprising a first plurality of anti-sticking bumps; a first main surface and a second main surface opposite, a second plurality of anti-sticking bumps on the first main surface, and a flexible membrane comprising a plurality of features on the second main surface—each of which is associated with a corresponding one of the second plurality of anti-sticking bumps—; and a second backplate—the flexible membrane is disposed between the first backplate and the second backplate.

[0080] Example 18. As a MEMS device of Example 17, one of the first plurality of anti-stick bumps is placed between adjacent features among the plurality of features.

[0081] Example 19. As a MEMS device of any one of Examples 17 or 18, the second backplate comprises a plurality of openings and connecting members, and the second plurality of anti-stick bumps are aligned with the connecting members in a direction orthogonal to the main surface of the second backplate.

[0082] Example 20. As a MEMS device of any one of Examples 17 to 19, each of the plurality of features is aligned with a corresponding one of the second plurality of anti-stick bumps in a direction orthogonal to the main surface of the second backplate.

[0083] Although the embodiments of the present application have been described in a specific context using MEMS microphones, various embodiments include other MEMS devices and structures, including MEMS capacitive acoustic transducer systems, MEMS microphone systems, silicon microphone systems, single and dual backplate microphone systems, and mechanically supported MEMS microphone systems.

[0084] Although the invention has been described with reference to exemplary embodiments, this description is not intended to be interpreted in a limiting sense. Various modifications and combinations of the exemplary embodiments, as well as other embodiments of the invention, will be apparent to those skilled in the art upon reference to this description. Therefore, the appended claims are intended to encompass any such modifications or embodiments.

Claims

Claim 1 A micro electrical mechanical systems (MEMS) device comprising: a flexible membrane disposed above a substrate; a first backplate disposed above the flexible membrane, wherein the first backplate comprises a first plurality of bumps facing the flexible membrane; and a plurality of features disposed on the flexible membrane, wherein each of the plurality of features is associated with a corresponding one of the first plurality of bumps and configured to reinforce the flexible membrane against stress-induced failure; wherein the plurality of features have a thickness in the size range of 10 nm to 1 μm and a lateral dimension of 500 nm to 5 μm. Claim 2 A MEMS device according to claim 1, wherein the plurality of features are aligned with a corresponding one of the first plurality of bumps. Claim 3 A MEMS device according to claim 1, wherein the plurality of features comprises (i) protrusions extending from the elastic membrane in a direction toward the first plurality of bumps or (ii) protrusions extending from the elastic membrane in a direction away from the first plurality of bumps, or both of the protrusions of (i) and (ii). Claim 4 A MEMS device according to claim 1, wherein the plurality of features comprises a material different from the elastic membrane. Claim 5 In paragraph 4, the plurality of features comprises an insulating material, in a MEMS device. Claim 6 A MEMS device according to claim 4, wherein the plurality of features are disposed above the elastic membrane and disposed between the elastic membrane and the first plurality of bumps. Claim 7 A MEMS device according to claim 4, wherein the plurality of features comprises: a first set of regions disposed above the elastic membrane and located between the elastic membrane and the first plurality of bumps; and a second set of regions disposed below the elastic membrane—the elastic membrane being disposed between the second set of regions and the first plurality of bumps. Claim 8 In paragraph 4, the plurality of features are disposed within the elastic membrane, in a MEMS device. Claim 9 A MEMS device according to claim 1, further comprising: a second backplate disposed between the elastic membrane and the substrate; and a second plurality of bumps disposed on the elastic membrane—the plurality of features being aligned with a corresponding one of the second plurality of bumps. Claim 10 A MEMS device according to claim 1, wherein each of the plurality of features comprises sidewalls inclined with respect to the main outer surface of the stretchable membrane. Claim 11 A MEMS device according to claim 1, wherein each of the plurality of features comprises sidewalls orthogonal to the main outer surface of the stretchable membrane. Claim 12 As a microelectromechanical systems (MEMS) device, a first backplate comprising a first plurality of anti-sticking bumps; a first main surface and a second main surface opposite, a second plurality of anti-sticking bumps on the first main surface, and a plurality of features on the second main surface—each of the plurality of features being associated with a corresponding one of the second plurality of anti-sticking bumps and disposed on the elastic membrane to overlap perpendicularly with the second plurality of anti-sticking bumps—; A MEMS device comprising: a second backplate—the elastic membrane being disposed between the first backplate and the second backplate—; wherein one of the first plurality of anti-sticking bumps is disposed between adjacent features among the plurality of features such that the first plurality of anti-sticking bumps do not overlap perpendicularly with the plurality of features; and wherein the plurality of features have a thickness in the size range of 10 nm to 1 μm and a lateral dimension of 500 nm to 5 μm. Claim 13 A MEMS device according to claim 12, wherein the second backplate comprises a plurality of openings and connecting members, and the second plurality of anti-sticking bumps are aligned with the connecting members in a direction orthogonal to the main surface of the second backplate. Claim 14 A MEMS device according to claim 12, wherein each of the plurality of features is aligned with a corresponding one of the second plurality of anti-sticking bumps in a direction orthogonal to the main surface of the second backplate. Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete

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