MEMS acoustic transducer and microphone device

Abstract

This disclosure relates to MEMS acoustic transducers and microphone devices. One MEMS acoustic transducer includes: a substrate having an opening formed therein; and a diaphragm including a slotted insulating layer and a first conductive layer. The slotted insulating layer is attached to the substrate around its periphery and above the opening, and the first conductive layer is disposed on a first surface of the slotted insulating layer. A backplate is separate from the diaphragm and disposed on the side of the diaphragm opposite to the substrate.

Description

Technical Field

[0001] This disclosure generally relates to a microelectromechanical system (MEMS) device with a diaphragm, and more specifically, to a MEMS acoustic transducer having a diaphragm including a grooved layer. Background Technology

[0002] It is widely accepted that multilayer diaphragms used in MEMS acoustic transducers can suffer from performance degradation due to CTE mismatch between layers. As described herein, a groove disposed through one of the layers separates the two layers and also minimizes stress in the grooved layer. Summary of the Invention

[0003] One aspect of the present invention relates to a microelectromechanical system (MEMS) acoustic transducer, the MEMS acoustic transducer comprising: a substrate having an opening formed therein; a diaphragm including a slotted insulating layer and a first conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer; and a backplate separated from the diaphragm and disposed on a side of the diaphragm opposite to the substrate.

[0004] Another aspect of the present invention relates to a microphone device comprising: a base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; an integrated circuit (IC) disposed on the first surface of the base; the aforementioned MEMS acoustic transducer disposed on the first surface of the base; and a cover disposed above the first surface of the base to cover the MEMS acoustic transducer and the IC.

[0005] Another aspect of the present invention relates to a microelectromechanical system (MEMS) acoustic transducer, the MEMS acoustic transducer comprising: a substrate having an opening formed therein; a diaphragm including a slotted insulating layer, a first conductive layer and a second conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer and having a plurality of first holes disposed therethrough, and the second conductive layer being disposed on a second surface of the slotted insulating layer and having a plurality of second holes disposed therethrough; and at least one backplate being separate from the diaphragm and attached to the substrate around its periphery.

[0006] Another aspect of the present invention relates to a microphone device comprising: a base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; an integrated circuit (IC) disposed on the first surface of the base; the aforementioned MEMS acoustic transducer disposed on the first surface of the base; and a cover disposed above the first surface of the base to cover the MEMS acoustic transducer and the IC.

[0007] Another aspect of the present invention relates to a microphone device, the microphone device comprising: a microelectromechanical system (MEMS) acoustic transducer, the MEMS acoustic transducer comprising: a substrate having an opening formed therein; a diaphragm including a slotted insulating layer and a first conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer; and at least one backplate, the at least one backplate being separate from the diaphragm and attached to the substrate around its periphery. Attached Figure Description

[0008] The foregoing and other features of this disclosure will become more apparent from the accompanying drawings, the following description, and the appended claims. These drawings depict only a few embodiments according to this disclosure and should not be considered as limiting its scope.

[0009] Figure 1A This is a cross-sectional schematic diagram of the MEMS acoustic transducer according to the first embodiment.

[0010] Figure 1B yes Figure 1A A three-dimensional cross-sectional schematic diagram of a portion of the diaphragm of a MEMS acoustic transducer.

[0011] Figure 2A This is a cross-sectional schematic diagram of the MEMS acoustic transducer according to the second embodiment.

[0012] Figure 2B yes Figure 2A A three-dimensional cross-sectional schematic diagram of a portion of the diaphragm of a MEMS acoustic transducer.

[0013] Figure 2C This is a cross-sectional schematic diagram of a MEMS acoustic transducer according to the third embodiment.

[0014] Figure 2D This is a cross-sectional schematic diagram of a MEMS acoustic transducer according to the fourth embodiment.

[0015] Figure 3 This is a cross-sectional view of the microphone assembly according to an embodiment.

[0016] Figure 4A Depicts Figure 1A This is a stage in the manufacturing process of a MEMS acoustic transducer.

[0017] Figure 4B Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4A The stage following the stage shown.

[0018] Figure 4C Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4B The stage following the stage shown.

[0019] Figure 4D Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4C The stage following the stage shown.

[0020] Figure 4E Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4D The stage following the stage shown.

[0021] Figure 4F Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4E The stage following the stage shown.

[0022] Figure 4G Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4F The stage following the stage shown.

[0023] Figure 4H Depicts Figure 1A In the manufacturing process of a part of a MEMS acoustic transducer Figure 4G The stage following the stage shown.

[0024] Figure 5A Depicts Figure 2A This is a stage in the manufacturing process of a MEMS acoustic transducer.

[0025] Figure 5B Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5A The stage following the stage shown.

[0026] Figure 5C Depicts Figure 2AIn the manufacturing process of a part of a MEMS acoustic transducer Figure 5B The stage following the stage shown.

[0027] Figure 5D Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5C The stage following the stage shown.

[0028] Figure 5E Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5D The stage following the stage shown.

[0029] Figure 5F Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5E The stage following the stage shown.

[0030] Figure 5G Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5F The stage following the stage shown.

[0031] Figure 5H Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5G The stage following the stage shown.

[0032] Figure 5I Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5H The stage following the stage shown.

[0033] Figure 5J Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5I The stage following the stage shown.

[0034] Figure 5K Depicts Figure 2A In the manufacturing process of a part of a MEMS acoustic transducer Figure 5J The stage following the stage shown.

[0035] In the following detailed description, various embodiments are described with reference to the accompanying drawings. Those skilled in the art will understand that the drawings are schematic and simplified for clarity. The same reference numerals always refer to the same elements or parts. Therefore, it is not necessary to describe the same elements or parts in detail with respect to the various figures. Detailed Implementation

[0036] The insulating and conductive layers of MEMS diaphragms are made of different materials with different coefficients of thermal expansion (CTE), which can generate undesirable stresses between the layers within a certain temperature range. This stress degrades the diaphragm's performance. For example, when used as part of a microphone, a diaphragm with additional internal stress can exhibit reduced compliance / acoustic sensitivity and / or temperature-dependent compliance / acoustic sensitivity. This is a known problem in the MEMS industry and has been addressed to some extent using specific diaphragm materials or multilayer diaphragms. However, the performance degradation due to CTE mismatch is inherent in all constrained multilayer diaphragms, including those with corrugated characteristics in one of the multiple layers.

[0037] Several methods exist to address the undesirable stresses caused by CTE mismatch. One approach is to select materials with similar CTE values ​​for both layers to minimize the effects of CTE mismatch and the resulting temperature-induced stresses. Another method is to modify the internal structure of one of the multiple layers, for example, to reduce the elastic modulus of that layer, which significantly reduces its inherent stiffness. Grooves formed through the insulation layer can isolate or separate the two layers. Furthermore, when the stress in the insulation layer relaxes, the grooves open, reducing the stress at the center of the insulation layer and thus providing high acoustic compliance. Therefore, grooved insulation layers provide both layer separation and stress reduction, both effects that cannot be achieved with layers that have corrugated features but no grooves.

[0038] Generally, this document discloses MEMS devices having diaphragms including grooved material layers and microphones incorporating such MEMS devices. Details of both will be explained more fully with reference to the accompanying drawings.

[0039] According to an embodiment, the MEMS acoustic transducer includes: a substrate having an opening formed therein; a diaphragm including a slotted insulating layer and a first conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer; and a backplate separated from the diaphragm and disposed on the side of the diaphragm opposite to the substrate.

[0040] In one embodiment, the MEMS acoustic transducer includes: a substrate having an opening formed therein; a diaphragm including a slotted insulating layer, a first conductive layer and a second conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer and having a plurality of first holes disposed therethrough, the second conductive layer being disposed on a second surface of the slotted insulating layer and having a plurality of second holes disposed therethrough; and at least one backplate being separate from the diaphragm and attached to the substrate around its periphery.

[0041] According to an embodiment, a microphone device includes a MEMS acoustic transducer, the MEMS acoustic transducer comprising: a substrate having an opening formed therein; a diaphragm including a slotted insulating layer and a first conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer; and at least one backplate being separate from the diaphragm and attached to the substrate around its periphery.

[0042] In one embodiment, the microphone device further includes: a base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; an integrated circuit (IC) disposed on the first surface of the base; wherein a MEMS acoustic transducer is disposed on the first surface of the base; and a cover disposed above the first surface of the base to cover the MEMS acoustic transducer and the IC.

[0043] According to an embodiment, the substrate includes silicon, the grooved insulating layer includes a silicon nitride layer with a thickness in the range of about 0.5 μm to about 1.5 μm, and the first conductive layer includes a polysilicon layer with a thickness in the range of about 150 nm to about 300 nm.

[0044] Turning Figure 1A This illustration shows a MEMS acoustic transducer according to an embodiment. The MEMS acoustic transducer, typically designated 100, includes a backplate 102, a first spacer 104, a diaphragm 106, a second spacer 108, and a substrate 110. The diaphragm 106 and the backplate 102 can be of any shape. The first spacer 104, the second spacer 108, and the substrate 110 can all be part of a single, monolithic body. In this embodiment, the diaphragm 106 is made of an insulating layer 106A and a conductive layer 106B. In this embodiment, the insulating layer 106A is made of silicon nitride, the conductive layer 106B is made of polycrystalline silicon, and the substrate 110 is made of silicon. Further details the additional structure and fabrication process of the diaphragm 106 used in the MEMS acoustic transducer 100 are described below.

[0045] In one embodiment, the backplate 102 has a first surface 102A and a second surface 102B opposite to the first surface 102A, the first surface 102A being part of an insulating or dielectric layer, and the second surface 102B being part of a conductive layer (first electrode). A diaphragm 106 is supported and constrained between and by a first spacer 104 (which contacts the insulating layer 106A) and a second spacer 108 (which also contacts the insulating layer 106A). The first spacer 104 has a curved inner wall 104A. The second surface 102B of the backplate 102, the inner surface of the diaphragm 106, and the inner wall 104A of the first spacer 104 define a cavity 112. In another embodiment, the backplate 102 includes one or more holes 105 disposed therethrough.

[0046] The second spacer 108 has a curved inner wall 108A. The diaphragm 106 is fully constrained along a boundary defined by a curve (along which the inner wall 104A of the first spacer 104 intersects with the diaphragm 106) (by the first spacer 104 and the second spacer 108). The substrate 110 also has a curved inner wall 110A defining an opening 116 extending through the substrate 110. In this embodiment, the first spacer 104 and the second spacer 108 are part of the sacrificial material of the MEMS acoustic transducer 100, and the walls 104A and 108A of the spacers are formed by a time-etched front side of the sacrificial material.

[0047] Now for reference Figure 2C A MEMS acoustic transducer 600 according to another embodiment is shown. The MEMS acoustic transducer 600 shares already known about... Figure 1A The MEMS acoustic transducer 100 described herein contains many components. Therefore, many of the same reference numerals appear in the figures. Figure 2C In the middle, to describe and Figure 1A The components are similar to those described in the previous section. However, the MEMS acoustic transducer 600 includes additional structures not present in the MEMS acoustic transducer 100. For example, the MEMS acoustic transducer 600 includes a second backplate 103, wherein a diaphragm 106 is disposed between the first backplate 102 and the second backplate 103.

[0048] There are many possible implementations of the backplate 102, backplate 103, and diaphragm 106. For example, the second backplate 103 may or may not be present. In another example, the first backplate 102 and / or the second backplate 103 may include an insulating layer or a dielectric layer and a conductive layer deposited on or otherwise connected to the dielectric layer. Similar to the backplate 102, in implementations such as Figure 2CThe backplate 103 shown has a first surface 103A and a second surface 103B opposite to the first surface 103A. The first surface 103A is part of an insulating or dielectric layer, and the second surface 103B is part of a conductive layer (electrode). The second surface 103B of the backplate 103, the inner surface of the diaphragm 106, and the inner wall 108A of the second spacer 108 define a cavity 113. In an embodiment, the backplate 103 includes one or more holes 105 disposed therethrough.

[0049] The diaphragm 106 can be made entirely of a conductive layer. In other implementations, the diaphragm 106 includes, for example... Figure 1A The insulating layer 106A and conductive layer 106B shown are similar to the first backplate 102 and the second backplate 103. In another implementation, the diaphragm 106 includes a conductive layer 106B and an insulating layer 106A, and one or both of the first backplate 102 and the second backplate 103 are formed entirely of conductive layers. The conductive layers of the backplates 102, 103 and the diaphragm 106 may face each other without any material between them, or may be separated from each other by the insulating layers of the diaphragm 106 and / or the backplates 102, 103. The insulating layers of the backplates 102, 103 and the diaphragm 106 may be made of, for example but not limited to, silicon nitride or other suitable insulating materials. The conductive layers on the backplates 102, 103 and / or the diaphragm 106 may be made of, for example but not limited to, polysilicon, metal or other suitable conductors.

[0050] refer to Figure 1A In one embodiment, the insulating layer 106A of the diaphragm 106 includes a plurality of grooves 118 disposed therethrough. Figure 1A The slot 118 shown is presented in a schematic context and is not intended to accurately represent the size, shape, arrangement or orientation of the slot 118.

[0051] refer to Figure 1B The wedge-shaped portion of the diaphragm 106 is illustrated, showing the insulating layer 106A without the conductive layer 106B. Figure 1B Shown Figure 1A The exemplary arrangement of the slots 118 provides examples of their relative dimensions, shapes, arrangements, and orientations. For example, in a first embodiment, each slot 118A is an elongated curved slot having a long dimension and a short dimension and being oriented such that the long dimension is generally circumferentially aligned about the center of the slotted insulating layer 106A. In another embodiment, each slot 118B is an elongated straight slot, the long dimension of which is generally radially aligned relative to the center of the slotted insulating layer 106A. In yet another embodiment, the slot 118 may be a combination of curved slots 118A and / or straight slots 118, each as shown in the example. Figure 1B The shown or each of them may have any other size, shape, arrangement or orientation.

[0052] Still referencing Figure 1A and Figure 1B In embodiments, the short dimension of each of slots 118, 118A, and 118B is in the range of about 2 μm to about 8 μm. The long dimension of the curved slot 118A is generally referred to as the curve length of the arc. The long dimension of each of slots 118, 118A, and 118B can vary with the overall size of the diaphragm 106. In embodiments, for example, for a diaphragm 106 with a radius in the range of about 250 μm to about 700 μm, the long dimension of each of slots 118, 118A, and 118B is in the range of about 10 μm to about 500 μm. The long dimension of each of slots 118, 118A, and 118B can have a length within this range, or for a diaphragm with a radius outside the range of about 250 μm to about 700 μm, the long dimension of each of slots 118, 118A, and 118B can be shorter or longer than this range.

[0053] Still referencing Figure 1A and Figure 1B In one embodiment, the slotted insulating layer 106A comprises a silicon nitride layer. In another embodiment, the thickness of the slotted insulating layer 106A is in the range of about 0.5 μm to about 1.5 μm. In another embodiment, the conductive layer 106B comprises a polycrystalline silicon layer, and in yet another embodiment, the thickness of the conductive layer 106B is in the range of about 150 nm to about 300 nm. In yet another embodiment, layers 106A and 106B of the diaphragm 106 are made of other materials and / or have other thicknesses that may be desired in the art or otherwise known.

[0054] Now for reference Figure 2A A MEMS acoustic transducer 200 according to another embodiment is shown. The MEMS acoustic transducer 200 shares already known about... Figure 1A The MEMS acoustic transducer 100 described herein contains many components. Therefore, many of the same reference numerals appear in the figures. Figure 2A In the middle, to describe and Figure 1A The components are similar to those described in the text. However, the diaphragm 206 of the MEMS acoustic transducer 200 includes additional structures not present in the diaphragm 106. For example, the diaphragm 206 includes a grooved insulating layer 206A (as in grooved insulating layer 106A) and a first conductive layer 206B (as in conductive layer 106B). However, the diaphragm 206 also includes a second conductive layer 206C disposed on the surface of the grooved insulating layer 206A opposite to the first conductive layer 206B.

[0055] In one embodiment, the second conductive layer 206C is made of polycrystalline silicon; however, in another embodiment, the second conductive layer 206C may be made of, for example but not limited to, a metal or other suitable conductors known in the art. In one embodiment, the thickness of each of the first conductive layer 206B and the second conductive layer 206C is in the range of about 150 nm to about 300 nm. In another embodiment, each of the first conductive layer 206B and the second conductive layer 206C of the diaphragm 206 is made of other materials and / or has other thicknesses that may be desired in the art or otherwise known.

[0056] refer to Figure 2D A MEMS acoustic transducer 700 according to another embodiment is shown. The MEMS acoustic transducer 700 shares already known about... Figure 2A The MEMS acoustic transducer 200 is described, which includes many components. Therefore, many of the same reference numerals appear in the figures. Figure 2D In the middle, to describe and Figure 2A The components are similar to those described above. However, the MEMS acoustic transducer 700 includes additional structures not present in the MEMS acoustic transducer 200. For example, the MEMS acoustic transducer 700 includes a second backplate 103, wherein the diaphragm 206 is disposed between the first backplate 102 and the second backplate 103. This has already been discussed above regarding... Figure 2C The MEMS acoustic transducer 600 shown describes the second backplane 103.

[0057] Now for reference Figure 2B The diagram illustrates a wedge-shaped portion of a diaphragm 206, wherein a first conductive layer 206B is visible at the top of the diaphragm 206, while a second conductive layer 206C is not visible but is indicated by a curved arrow. In an embodiment, each of the first conductive layer 206B and the second conductive layer 206C includes a plurality of holes disposed therethrough. Figure 2B An example is shown of a first plurality of holes 228A (schematically shown as solid circles 228) disposed through the first conductive layer 206B. Figure 2B A second plurality of holes 228B (schematically shown as dashed circles 228B) are further illustrated through the second conductive layer 206C. For clarity, the first plurality of holes 228A and the second plurality of holes 228B are not shown in the diagram. Figure 2A As shown in the figure, but clearly illustrated in the following description of the exemplary manufacturing process of the diaphragm 206. In the embodiment, at least one of the first plurality of holes 228A is geometrically aligned with at least one of the plurality of second holes 228B (e.g., see [reference]). Figure 5KThe top hole set 528A and bottom hole set 528B are shown in the embodiment. In this embodiment, the first plurality of holes and the second plurality of holes are used in the final release step of the manufacturing process of the diaphragm 206 and the MEMS acoustic transducer 200. The additional structure and manufacturing process of the diaphragm 106 used in the MEMS acoustic transducer 200 are further described below.

[0058] During operation of the MEMS acoustic transducers 100, 200, 600, and 700, charge is applied to the conductive layers of at least one backplate 102, 103 and the conductive layers of diaphragms 106, 206, thereby inducing an electric field between at least one backplate 102, 103 and the diaphragms 106, 206 and generating an electrostatic bias voltage on the diaphragms 106, 206. Movement of air (e.g., generated by sound waves) pushes the surfaces of the diaphragms 106, 206 facing the opening 116, causing the diaphragms 106, 206 to deflect (enter a deflected state) and deform. This deformation results in a change in capacitance between at least one backplate 102, 103 and the diaphragms 106, 206, which can be detected and interpreted as sound.

[0059] Go to Figure 3 MEMS acoustic transducers 100, 200, 600, and 700 are configured to be mounted within a microphone assembly, typically designated 300. Assembly 300 includes a housing comprising a base 302, a cover 304 (e.g., a housing cover), and an acoustic port 306. In one implementation, the base 302 is a printed circuit board. The cover 304 is coupled to the base 302 (e.g., the cover 304 may be mounted to the peripheral edge of the base 302). Together, the cover 304 and the base 302 form an enclosed volume 308 of assembly 300. Figure 3 As shown, acoustic port 306 is disposed on base 302 and configured to transmit sound waves to MEMS acoustic transducers 100, 200 located within enclosed volume 308. In other implementations, acoustic port 306 is disposed on cover 304 and / or sidewall of cover 304. In some embodiments, component 300 forms part of a compact computing device (e.g., portable communication device, smartphone, smart speaker, Internet of Things (IoT) device, etc.), wherein one, two, three or more components may be integrated to pick up and process various types of acoustic signals (such as speech and music).

[0060] Component 300 includes circuitry disposed within an enclosed volume 308. The circuitry includes an integrated circuit (IC) 310. IC 310 may be an application-specific integrated circuit (ASIC). Alternatively, IC 310 may include a semiconductor die integrating various analog, analog-to-digital, and / or digital circuitry.

[0061] exist Figure 3In component 300, MEMS acoustic transducers 100, 200, 600, and 700 convert the sound waves received through acoustic port 306 into corresponding electric microphone signals. Figure 3 Examples are shown as follows Figure 1A The diagram shows the structure of the MEMS acoustic transducer 100; however, the reference numerals 100, 200, 600, and 700 specifically indicate that... Figure 3 Examples can also be given as follows: Figure 2A , Figure 2C or Figure 2D The diagram shows the structure of the MEMS acoustic transducer 200, 600, or 700.

[0062] Transducers 100, 200, 600, or 700 generate an electrical signal (e.g., voltage) at their output in response to acoustic activity incident on port 306. Figure 3 As shown, the transducer output includes a transducer pad or terminal that is electrically connected to the circuit via one or more connection wires 312. Figure 3 Component 300 also includes an electrical contact, schematically shown as contact 314, typically disposed on the bottom surface of base 302. Contact 314 is electrically connected to a circuit. Contact 314 is configured to electrically connect component 300 to one of a variety of host devices.

[0063] Figures 4A to 4H A portion of a MEMS acoustic transducer 100 in a sequential manufacturing process is depicted. The workpiece being manufactured is illustrated in cross-section, with the "top" side positioned on the left side of the cross-section for illustrative purposes. It should be noted that... Figures 4A to 4H The reference numerals used in the description of the manufacturing process shown are from the 400 series, which corresponds to... Figure 1A and Figure 1B The 100 series numbering is used for similar structures. Therefore, for example, as a result of the manufacturing process, Figures 4A to 4H The cylindrical chip 410 in the middle eventually becomes Figure 1A The substrate 110 is shown. Furthermore, all deposition steps for adding material layers as described below can be performed, for example, but not limited to, via vapor deposition processes, such as low-pressure chemical vapor deposition processes known in the art.

[0064] from Figure 4AInitially, a tetraethyl orthosilicate (TEOS) oxide layer 408 is deposited onto a portion of the top side of a cylindrical wafer 410, which includes, but is not limited to, a substrate material (shown in cross-section) such as, but not limited to, silicon. In one embodiment, the TEOS oxide layer 408 is deposited over all areas of the top surface of the wafer 410 except for the annular ring 409. In one embodiment, the thickness of the deposited TEOS oxide layer 408 is in the range of about 0.5 μm to about 1.5 μm. In another embodiment, the thickness of the wafer 410 is in the range of about 500 μm to about 725 μm. After depositing the TEOS oxide layer 408, the workpiece is annealed at a temperature of about 1075°C for about one hour. In other embodiments, the thickness of the deposited TEOS oxide layer 408, the thickness of the wafer 410, and the annealing temperature and time may vary.

[0065] Figure 4B The second stage of the manufacturing process is illustrated, in which a silicon nitride layer 406A is applied to the top and bottom sides of wafer 410, as shown, thereby completely covering the TEOS oxide layer 408. In this embodiment, the thickness of the silicon nitride layer 406A is in the range of about 0.5 μm to about 2.5 μm.

[0066] Figure 4C Another stage in the manufacturing process is illustrated, in which the pattern of the groove 418 is cut into the silicon nitride layer 406A on the top side of the workpiece, for example, by cutting, perforation, grinding, etching, or other chemical processes known in the art. Subsequently, a polysilicate glass (PSG) sacrificial layer 411 is deposited over the groove 418 and the silicon nitride layer 406A, thereby also filling the groove 418. In this embodiment, the thickness of the PSG layer 411 is approximately 2.3 μm.

[0067] Figure 4D Another stage in the manufacturing process is illustrated, in which the silicon nitride layer 406A on the bottom side of wafer 410 is removed, for example, by grinding, etching, or polishing. In this stage, a PSG layer is applied to the bottom side of wafer 410 and subsequently ground, etched, or polished to leave an annular PSG layer 419 as shown. Also in this stage, the top side of the workpiece is polished to remove the continuous PSG layer 411 and leave a silicon nitride layer 406A approximately 1.1 μm thick. Figure 4E In this embodiment, the workpiece has polysilicon layers 406B applied over the top and bottom sides as shown in the figure. In this embodiment, the thickness of each polysilicon layer 406B is in the range of about 150 nm to about 300 nm.

[0068] refer to Figure 4F For example, the peripheral portion of the polysilicon layer 406B can be removed by grinding, etching, or polishing, and the remaining polysilicon layer 406B can be pierced with a hole 420, as also shown in... Figure 1AThe hole 420 is not necessarily at the geometric center of the polysilicon layer 406B, and may be slightly offset from that geometric center as shown in the figure. The hole 420 is sized and located on the polysilicon layer 406B for the purpose of controlling the low-frequency roll-off performance of the MEMS acoustic transducer 100.

[0069] exist Figure 4G In this process, for example, the bottom polysilicon layer 406B and the central portion of the wafer 410 were removed by grinding, etching, or polishing. Finally, in Figure 4H In this process, the TEOS oxide layer 408 and the PSG layers 411 and 419 are removed or released by grinding, etching, polishing or another chemical process known in the art. Figure 4H The remaining structure shown is schematically represented. Figure 1A The structure of the MEMS acoustic transducer 100 shown is without a backplate 102 and a first spacer 104.

[0070] Figures 5A to 5K A portion of a MEMS acoustic transducer 200 in a sequential manufacturing process is depicted. The workpiece being manufactured is illustrated in cross-section, with the "top" side positioned on the left side of the cross-section for illustrative purposes. It should be noted that... Figures 5A to 5K The reference numerals used in the description of the manufacturing method shown are from the 500 series, which corresponds to... Figure 2A and Figure 2B The 200 series numbering is used for similar structures. Therefore, for example, as a result of the manufacturing method, Figures 5A to 5K The cylindrical chip 510 in the middle eventually became Figure 2A The substrate 110 shown.

[0071] from Figure 5A Initially, a PSG layer 511 is deposited onto a portion of the top side of a cylindrical wafer 510, which includes, but is not limited to, a substrate material (shown in cross-section) such as, but not limited to, silicon. In this embodiment, the PSG layer 511 is deposited on all areas of the top surface of the wafer 510 except for the annular ring 509.

[0072] Figure 5B An example is illustrated where a PSG layer has been applied to the bottom side of wafer 510 and subsequently ground, etched, or polished to leave an annular PSG layer 519 as shown. In one embodiment, the thickness of each of the deposited PSG layers 511 and 519 is in the range of about 0.3 μm to about 1.5 μm. In another embodiment, the thickness of wafer 510 is in the range of about 500 μm to about 725 μm. After depositing PSG layers 511 and 519, the workpiece is annealed at a temperature of about 1075°C for about one hour. In other embodiments, the thicknesses of the deposited PSG layers 511 and 519, the thickness of wafer 510, and the annealing temperature and time may vary.

[0073] Now for reference Figure 5C A first polysilicon layer 506C is deposited above the central portion of the PSG layer 511. In this embodiment, the thickness of the first polysilicon layer 506C is in the range of about 150 nm to about 300 nm. A first plurality of vias 528B are configured to penetrate the first polysilicon layer 506C, for example, by means of perforation, etching, polishing, or other methods known in the art. A polysilicon layer 506D is also deposited on the bottom side of the workpiece.

[0074] Figure 5D Another stage in the manufacturing process is illustrated, in which a PSG sacrificial layer 512 is applied to the top side of the workpiece to fill the first plurality of holes 528B. After the PSG sacrificial layer 512 is deposited, the workpiece is annealed at a temperature of about 1050°C for a period ranging from about 1 hour to about 3 hours.

[0075] exist Figure 5E In this process, for example, holes, spaces, or openings 506E are created by cutting, perforating, grinding, etching, or other chemical processes through the PSG sacrificial layer 512, thereby re-exposing the annular ring 509. Figure 5F In this embodiment, the hole 506E and the annular ring 509 are filled with a silicon nitride layer 506A applied above the top side of the workpiece. In this embodiment, the maximum thickness of the silicon nitride layer 506A, measured at the annular ring 509, is approximately 2.42 μm. A silicon nitride layer 506F is also deposited on the bottom side of the workpiece.

[0076] refer to Figure 5G For example, by grinding, etching, or polishing, a continuous portion of the silicon nitride layer 506A on the top side of the workpiece and the layer 506F on the bottom side of the workpiece can be removed. Figure 5H In this embodiment, a second polysilicon layer 506B is deposited above the central portion of the top of the workpiece, at least spanning the annular ring 509 (which is now filled with silicon nitride). In this embodiment, the thickness of the second polysilicon layer 506B is in the range of about 150 nm to about 300 nm. A second plurality of vias 528A are disposed through the second polysilicon layer 506B, for example by perforation, etching, polishing, or other methods known in the art. In this embodiment, at least one of the second plurality of vias 528A is geometrically aligned with at least one of the first plurality of vias 528B. Referring now to... Figure 5I A PSG layer 525 is deposited on the top side of the workpiece, and the workpiece is annealed at a temperature of about 1050°C for a period of about 1 hour to about 3 hours.

[0077] exist Figure 5J In this process, for example, the polysilicon layer 506D on the bottom side of the workpiece and the central portion of the wafer 510 were removed by grinding, etching, or polishing. Finally, in Figure 5KIn this process, the PSG layers 511, 512 and 525 are removed or released by grinding, etching, polishing or another chemical process known in the art. Figure 5K The remaining structure shown is schematically represented. Figure 2A and Figure 2B The structure of the MEMS acoustic transducer 200 shown does not include the backplate 102 and the first spacer 104, and in particular, for clarity, Figure 2A The first plurality of holes 228A and the second plurality of holes 228B are not shown.

[0078] Regarding the use of plural and / or singular terms in this document, those skilled in the art can translate from plural to singular and / or from singular to plural depending on the context and / or application. For clarity, various singular / plural substitutions may be explicitly described herein.

[0079] Unless otherwise stated, the use of words such as “approximately,” “about,” “probably,” and “basically” indicates a plus or minus of ten percent.

[0080] The foregoing description of exemplary embodiments has been presented for purposes of illustration and description. The precise forms disclosed are not intended to be exhaustive or limiting, and modifications and variations are possible in accordance with the foregoing teachings, or may be derived from practice of the disclosed embodiments. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A microelectromechanical system (MEMS) acoustic transducer, the MEMS acoustic transducer comprising: A substrate having an opening formed therein; A diaphragm, the diaphragm comprising a slotted insulating layer and a first conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer; as well as A backplate, which is separate from the diaphragm and disposed on the side of the diaphragm opposite to the substrate. The grooved insulating layer includes a plurality of grooves disposed therethrough, each groove having a long dimension and a short dimension, wherein the grooves are selected from a group of grooves including curved grooves, straight grooves, and combinations thereof, the curved grooves being oriented such that their long dimensions are circumferentially aligned around the center of the grooved insulating layer, the long dimensions of the straight grooves being radially aligned relative to the center of the grooved insulating layer, and wherein the short dimension is in the range of 2 μm to 8 μm.

2. The MEMS acoustic transducer according to claim 1, wherein, The substrate includes silicon, wherein the grooved insulating layer includes a silicon nitride layer with a thickness in the range of 0.5 μm to 1.5 μm, and wherein the first conductive layer includes a first polysilicon conductive layer with a thickness in the range of 150 nm to 300 nm.

3. The MEMS acoustic transducer according to claim 2, further comprising a second conductive layer, the second conductive layer comprising a second polysilicon conductive layer, the thickness of the second polysilicon conductive layer being in the range of 150 nm to 300 nm and disposed on the second surface of the grooved insulating layer, wherein, Each of the first polycrystalline silicon conductive layer and the second polycrystalline silicon conductive layer includes a plurality of holes disposed therethrough.

4. The MEMS acoustic transducer according to claim 3, wherein, At least one of the plurality of holes disposed through the first conductive layer is geometrically aligned with at least one of the plurality of holes disposed through the second conductive layer.

5. A microphone device, the microphone device comprising: A base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; An integrated circuit (IC) is disposed on the first surface of the base; According to claim 1, the MEMS acoustic transducer is disposed on the first surface of the base; and A cover is disposed above the first surface of the base, thereby covering the MEMS acoustic transducer and the IC.

6. A microelectromechanical system (MEMS) acoustic transducer, the MEMS acoustic transducer comprising: A substrate having an opening formed therein; The diaphragm includes a slotted insulating layer, a first conductive layer and a second conductive layer. The slotted insulating layer is attached to the substrate around its periphery and above the opening. The first conductive layer is disposed on a first surface of the slotted insulating layer and has a plurality of first holes disposed therethrough. The second conductive layer is disposed on a second surface of the slotted insulating layer and has a plurality of second holes disposed therethrough. as well as At least one back plate, said at least one back plate being separate from the diaphragm and attached to the substrate around its periphery. The grooved insulating layer includes a plurality of grooves disposed therethrough, each groove having a long dimension and a short dimension, wherein the grooves are selected from a group of grooves including curved grooves, straight grooves, and combinations thereof, the curved grooves being oriented such that their long dimensions are circumferentially aligned around the center of the grooved insulating layer, the long dimensions of the straight grooves being radially aligned relative to the center of the grooved insulating layer, and wherein the short dimension is in the range of 2 μm to 8 μm.

7. The MEMS acoustic transducer according to claim 6, wherein, The at least one backplate includes two backplates, and the diaphragm is disposed between the two backplates.

8. The MEMS acoustic transducer according to claim 6, wherein, The substrate includes silicon, the grooved insulating layer includes a silicon nitride layer with a thickness in the range of 0.5 μm to 1.5 μm, the first conductive layer includes a first polysilicon layer with a thickness in the range of 150 nm to 300 nm, and the second conductive layer includes a second polysilicon layer with a thickness in the range of 150 nm to 300 nm.

9. The MEMS acoustic transducer according to claim 6, wherein, At least one of the plurality of first holes is geometrically aligned with at least one of the plurality of second holes.

10. A microphone device, the microphone device comprising: A base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; An integrated circuit (IC) is disposed on the first surface of the base; The MEMS acoustic transducer according to claim 6, wherein the MEMS acoustic transducer is disposed on the first surface of the base; and A cover is disposed above the first surface of the base, thereby covering the MEMS acoustic transducer and the IC.

11. A microphone device, the microphone device comprising: Microelectromechanical systems (MEMS) acoustic transducers, wherein the MEMS acoustic transducers include: A substrate having an opening formed therein; A diaphragm, the diaphragm comprising a slotted insulating layer and a first conductive layer, the slotted insulating layer being attached to the substrate around its periphery and above the opening, the first conductive layer being disposed on a first surface of the slotted insulating layer; and At least one back plate, said at least one back plate being separate from the diaphragm and attached to the substrate around its periphery. The grooved insulating layer includes a plurality of grooves disposed therethrough, each groove having a long dimension and a short dimension. The grooves are selected from a group of grooves including curved grooves, straight grooves, and combinations thereof. The curved grooves are oriented such that their long dimensions are circumferentially aligned around the center of the grooved insulating layer, and the long dimensions of the straight grooves are radially aligned relative to the center of the grooved insulating layer. The short dimensions are in the range of 2 μm to 8 μm.

12. The microphone device according to claim 11, further comprising: A base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; and An integrated circuit (IC) is disposed on the first surface of the base; wherein the MEMS acoustic transducer is disposed on the first surface of the base; and A cover is disposed above the first surface of the base, thereby covering the MEMS acoustic transducer and the IC.

13. The microphone device according to claim 11, wherein, The substrate includes silicon, the grooved insulating layer includes a silicon nitride layer with a thickness in the range of 0.5 μm to 1.5 μm, and the first conductive layer includes a first polysilicon conductive layer with a thickness in the range of 150 nm to 300 nm.

14. The microphone device of claim 13, further comprising a second polysilicon conductive layer, the second polysilicon conductive layer having a thickness in the range of 150 nm to 300 nm and disposed on the second surface of the slotted insulating layer, wherein, Each of the first polycrystalline silicon conductive layer and the second polycrystalline silicon conductive layer includes a plurality of holes disposed therethrough.

15. The microphone device of claim 14, further comprising: A base having a first surface, an opposite second surface, and a port, wherein the port extends between the first surface and the second surface; and An integrated circuit (IC) is disposed on the first surface of the base, wherein the MEMS acoustic transducer is disposed on the first surface of the base; and A cover is disposed above the first surface of the base, thereby covering the MEMS acoustic transducer and the IC.

16. The microphone device according to claim 14, wherein, The at least one backplate includes two backplates, and the diaphragm is disposed between the two backplates.

17. The microphone device according to claim 14, wherein, At least one of the plurality of holes disposed through the first polysilicon conductive layer is geometrically aligned with at least one of the plurality of holes disposed through the second polysilicon conductive layer.

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