CN114339507B - MEMS microphone and manufacturing method thereof - Google Patents
MEMS microphone and manufacturing method thereof Download PDFInfo
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- CN114339507B CN114339507B CN202210229246.0A CN202210229246A CN114339507B CN 114339507 B CN114339507 B CN 114339507B CN 202210229246 A CN202210229246 A CN 202210229246A CN 114339507 B CN114339507 B CN 114339507B
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Abstract
The invention provides an MEMS microphone and a manufacturing method thereof.A contact prevention part is formed on the inner edge of an anchor area fixing part of a vibrating diaphragm or the outer edge of a vibrating part, and comprises at least one of a limiting bulge, a limiting column and a limiting baffle, so that the problem of clamping or overlapping between the vibrating part of the vibrating diaphragm and the anchor area fixing part during vibration can be effectively prevented, and the performance of a device is improved.
Description
Technical Field
The invention relates to the technical field of integrated circuit manufacturing, in particular to an MEMS microphone and a manufacturing method thereof.
Background
At present, a Microphone with more applications and better performance is a Micro-Electro-Mechanical-System Microphone (also called a silicon-based condenser Microphone, hereinafter referred to as an MEMS Microphone). The MEMS microphone is an electroacoustic transducer manufactured by a micromachining technology and has the characteristics of small volume, good frequency response characteristic, low noise and the like.
Referring to fig. 1, a conventional MEMS microphone generally includes a silicon substrate 100, a diaphragm 101 and a backplate 103 disposed on the silicon substrate 100, the backplate 103 is usually exposed to air, and has sound holes for receiving external sound, the diaphragm 101 is opposite to the backplate 103 and separated by a cavity 102, the diaphragm 101 and the backplate 103 form a plate capacitor, the diaphragm 101 and the backplate 103 are respectively used as two electrodes of the plate capacitor, the diaphragm 101 vibrates under the action of sound waves to change the distance between the diaphragm and the backplate 103, and thus the capacitance of the plate capacitor is changed, so as to convert sound wave signals into electrical signals. In order to increase the vibration sensitivity of the diaphragm 101, a channel 101c penetrating through the diaphragm 101 is currently engraved in the diaphragm 101, the anchor region fixing portion 101b is separated from the vibrating portion 101a, and the vibrating portion 101a of the diaphragm 101 is fixed at only several point positions 101d, as shown in fig. 2.
However, since the vibrating portion 101a of the diaphragm 101 is fixed at a point rather than a full fixation, a small displacement occurs in the plane of the diaphragm during vibration, so that the vibrating portion 101a of the diaphragm 101 and the anchor region fixing portion 101b are in contact and cannot be rebounded, which causes the problem of the clamping as shown in fig. 3 or the problem of the overlapping as shown in fig. 4, and affects the performance of the MEMS microphone chip.
Disclosure of Invention
The invention aims to provide an MEMS microphone and a manufacturing method thereof, which can prevent the problem of clamping or overlapping of a vibration part and an anchor area fixing part when a vibrating diaphragm vibrates and improve the performance of a device.
In order to achieve the above object, the present invention provides an MEMS microphone having a diaphragm and a channel penetrating the diaphragm, the channel dividing the diaphragm into a vibrating portion and an anchor region fixing portion surrounding the periphery of the vibrating portion, wherein an outer edge of the vibrating portion and/or an inner edge of the anchor region fixing portion is provided with a contact prevention portion; and at least part of the side wall of the contact preventing part is convexly arranged in the channel, and/or at least one end of the top end and the bottom end of the contact preventing part is convex relative to the diaphragm.
Optionally, the contact preventing portion includes at least one limiting protrusion, and each limiting protrusion protrudes from the channel in a direction parallel to the top surface of the diaphragm.
Optionally, the limiting protrusion on the inner edge of the anchor region fixing part is integrally formed with the anchor region fixing part, and/or the limiting protrusion on the outer edge of the vibrating part is integrally formed with the vibrating part.
Optionally, the anti-contact portion includes at least one limiting pillar, adjacent limiting pillars are spaced apart from each other, each limiting pillar extends along a direction perpendicular to the top surface of the diaphragm, and at least one of the top end and the bottom end is convex relative to the diaphragm; and/or the contact preventing part comprises at least one limit baffle, each limit baffle extends along a direction perpendicular to the top surface of the vibrating diaphragm, and at least one end of the top end and the bottom end is convex relative to the vibrating diaphragm.
Optionally, the limiting column and the limiting baffle are both only fixedly arranged on the inner edge of the anchoring area fixing part.
Optionally, the material of the limiting column and the limiting baffle comprises at least one of silicon nitride, silicon oxynitride, polysilicon and metal.
Optionally, the MEMS microphone further includes a substrate and a plurality of point fixing members, each of the point fixing members fixing the vibrating portion to a corresponding point of the substrate, and an outer edge of the anchor fixing portion is integrally fixed to the substrate.
Based on the same inventive concept, the invention also provides a manufacturing method of the MEMS microphone, which comprises the following steps:
forming a first sacrificial layer on a substrate, and depositing a diaphragm on the first sacrificial layer;
etching the vibrating diaphragm to form a channel penetrating through the vibrating diaphragm, wherein the channel divides the vibrating diaphragm into a vibrating part and an anchor area fixing part surrounding the periphery of the vibrating part;
forming a second sacrificial layer and a back plate on the vibrating diaphragm;
in the step of etching the diaphragm, at least one limiting bulge located on the outer edge of the vibrating part or the inner edge of the anchor region fixing part is further formed in the channel, and at least part of the side wall of each limiting bulge is convexly arranged in the channel;
and/or, before or after the step of forming the second sacrificial layer on the diaphragm, a stopper post and/or a stopper baffle on an outer edge of the vibrating portion or an inner edge of the anchor fixing portion are further formed in the channel, at least one of a top end and a bottom end of the stopper post and/or the stopper baffle being convex with respect to the diaphragm.
Optionally, the method for manufacturing a MEMS microphone further includes, after forming the back plate:
forming a plurality of sound holes on the back plate;
releasing the second sacrificial layer and the first sacrificial layer to form a vibration space required for the vibration part.
Optionally, the method for manufacturing a MEMS microphone further includes, after forming a plurality of sound holes on the back plate:
forming a conductive bonding pad electrically connected with the back plate and a conductive bonding pad electrically connected with the vibrating diaphragm on the back plate respectively;
etching the back surface of the substrate to form a back cavity exposing the back surface of the first sacrificial layer;
wherein the second sacrificial layer and the first sacrificial layer are released through the acoustic aperture and the back cavity.
Compared with the prior art, the technical scheme of the invention has at least one of the following beneficial effects:
the contact portion is prevented in the formation on the outward flange of the inward flange of the anchor region fixed part of vibrating diaphragm or vibration portion, should prevent that the contact portion includes at least one in spacing arch, spacing post and limit baffle, can effectively prevent because the vibration portion of vibrating diaphragm takes place screens or lapped problem with the anchor region fixed part when the vibration, improves the device performance.
Drawings
Fig. 1 is a schematic top view of a conventional MEMS microphone (not shown in the figures, the back plate, the conductive pads, etc.).
Fig. 2 is a schematic sectional view taken along line a-a' in fig. 1.
Fig. 3 is a schematic view showing a problem of seizing of the vibrating portion and the anchor fixing portion of the diaphragm shown in fig. 2.
Fig. 4 is a schematic view showing a problem of overlapping between the vibrating portion and the anchor fixing portion of the diaphragm shown in fig. 2.
Fig. 5 is a schematic top view of an example of the MEMS microphone according to the first embodiment of the present invention (the back plate, the conductive pad, and the like are not shown).
Fig. 6 is a schematic sectional view taken along line a-a' in fig. 5.
Fig. 7 is a schematic top view of another example of the MEMS microphone according to the first embodiment of the present invention (the structures of the backplate, the conductive pads, and the like are not shown).
FIG. 8 is a schematic top view of an example of a MEMS microphone (not shown) with a back plate, conductive pads, etc. in accordance with a second embodiment of the present invention
Fig. 9 is a schematic sectional view taken along line a-a' in fig. 8.
Fig. 10 is a schematic top view of another example of the MEMS microphone according to the second embodiment of the present invention (the structures of the backplate, the conductive pads, and the like are not shown).
Fig. 11 is a schematic top view of a MEMS microphone according to a third embodiment of the invention (not shown in the figures, the back plate, the conductive pads, and the like).
Fig. 12 is a schematic cross-sectional view of a device in a method of manufacturing a MEMS microphone according to a fourth embodiment of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention. It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout. It will be understood that when an element is referred to as being "connected to" other elements, it can be directly connected to the other elements or intervening elements may be present. In contrast, when an element is referred to as being "directly connected to" another element, there are no intervening elements present. Although the directional terms "top," "bottom," etc. may be used to describe various elements, components, and/or sections or positional relationships among each other, these elements, components, and/or sections or positional relationships among each other should not be limited by these terms, such as the "top" or "top" of a component may become the "bottom" or "bottom" of the component after the component is turned over 180 °. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" are used in an inclusive sense to specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
The technical solution proposed by the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
First embodiment
Referring to fig. 5 and 6, the present embodiment provides a MEMS microphone, which has a diaphragm 201 and a channel 201c penetrating the diaphragm 201 from the top to the bottom (or from the top to the bottom), wherein the channel 201c divides the diaphragm 201 into a vibrating portion 201a and an anchor fixing portion 201b surrounding the vibrating portion 201 a.
As an example, at least one limiting protrusion 201e serving as a contact prevention part is provided on the inner edge of the anchor fixing part 201b (i.e., the edge of the anchor fixing part 201b facing the vibration part 201 a), and the limiting protrusions 201e may be distributed in a dot or island shape on the inner edge of the anchor fixing part 201 b. Each of the limiting protrusions 201e is located in the channel 201c and is integrally formed with the anchor fixing portion 201 b. Each of the limiting protrusions 201e extends in a direction parallel to the top surface of the diaphragm 201 such that at least a part of the sidewall of each limiting protrusion 201e protrudes toward the vibrating portion 201 a. Further optionally, the limiting protrusion 201e is a circular protrusion, a conical protrusion, a semicircular column, or a protrusion with any other suitable shape, so that even though the vibrating portion 201a may slightly displace in the plane of the vibrating diaphragm 201 during vibration, the side wall of the vibrating portion 201a contacts with the limiting protrusion 201e, and is not in surface-to-surface contact, but in point-to-surface contact or line-to-surface contact, so that the vibrating portion 201a easily rebounds, and the problem of clamping between the vibrating portion 201a and the anchor region fixing portion 201b is avoided to the greatest extent.
In addition, the MEMS microphone of this embodiment further includes a substrate 200, a first dielectric layer 204, a second dielectric layer 205, a backplate 203, and a conductive pad 206, wherein the diaphragm 201 is formed on the first dielectric layer 204, a back cavity 200a in the substrate 200 not only penetrates through the substrate 200 from the back side, but also penetrates through the first dielectric layer 204 to expose the back side of the diaphragm 201, a cavity 202 penetrating through the second dielectric layer 205 is disposed between the backplate 203 and the diaphragm 201, and a plurality of sound holes (not shown) penetrating through the backplate 203 and communicating with the cavity 202 are further disposed on the backplate 203. The backplate 203 may be a stacked structure including a conductive layer (which may be polysilicon or metal, etc.) 203a and a dielectric protective layer 203 b. The conductive pads 206 are formed on the backplate 203 and electrically connected to the conductive layer 203a in the backplate 203 to electrically lead out the backplate 203 and the diaphragm 201, respectively.
Further, the vibrating portion 201a of the diaphragm 201 is fixed to the substrate 200 by a plurality of point fixing members 201d, and the point fixing members 201d may be a part of the first medium layer 204 or a part different from the first medium layer 204. These point fixing pieces 201d achieve an effect of fixing the vibrating portion 201a of the diaphragm 201 only at several point positions, whereby the vibration sensitivity of the diaphragm 201 can be improved.
The outer edge of the anchor region fixing portion 201b of the diaphragm 201 is integrally fixed to the substrate 200 through the first medium layer 204.
It should be understood that any suitable material in the prior art may be used as the material of each structure in the MEMS microphone of this embodiment, and details thereof are not described here.
As another example, referring to fig. 7, all the limiting protrusions 201e are disposed on the outer edge of the vibrating portion 201a (i.e., the edge of the vibrating portion 201a facing the anchor fixing portion 201 b) at intervals, and are integrally formed with the vibrating portion 201 a.
In another example of this embodiment, please refer to fig. 5 and 7, a portion of the limiting protrusions 201e are dispersedly disposed on the outer edge of the vibrating portion 201a, another portion of the limiting protrusions 201e are dispersedly disposed on the inner edge of the anchor fixing portion 201b, and the limiting protrusions 201e on the outer edge of the vibrating portion 201a and the limiting protrusions 201e on the inner edge of the anchor fixing portion 201b can be aligned or distributed in a staggered manner. At this time, the stopper protrusion 201e on the inner edge of the anchor fixing portion 201b is integrally formed with the anchor fixing portion 201b, and the stopper protrusion 201e on the outer edge of the vibrating portion 201a is integrally formed with the vibrating portion 201 a.
Second embodiment
Referring to fig. 8 to 10, the present embodiment provides an MEMS microphone, which includes a diaphragm 201 and a channel 201c penetrating the diaphragm 201 from a top surface to a bottom surface (or from a top to a bottom surface), wherein the channel 201c divides the diaphragm 201 into a vibrating portion 201a and an anchor fixing portion 201b surrounding the vibrating portion 201 a.
The present embodiment differs from the first embodiment in that the inner edge of the anchor region fixing portion 201b (i.e., the edge of the anchor region fixing portion 201b toward the vibrating portion 201 a) and/or the outer edge of the vibrating portion 201a (i.e., the edge of the vibrating portion 201a toward the anchor region fixing portion 201 b) is provided with a contact preventing portion 201f, the contact preventing portion 201f extending in a direction perpendicular to the top surface of the diaphragm 201, and the top end and the bottom end are both convex with respect to the diaphragm 201. That is, when the top end of the contact preventing portion 201f is convex with respect to the diaphragm 201, the top surface of the contact preventing portion 201f is higher than the top surface of the diaphragm 201, and when the bottom end of the contact preventing portion 201f is convex with respect to the diaphragm 201, the bottom surface of the contact preventing portion 201f is lower than the bottom surface of the diaphragm 201.
Optionally, the material of the contact preventing portion 201f may be the same as or different from that of the diaphragm 201, and the material of the contact preventing portion 201f may include at least one of silicon nitride, silicon oxynitride, polysilicon, and metal, for example.
As an example, referring to fig. 8 and 9, the contact preventing portion 201f includes a plurality of limiting pillars, each of the limiting pillars may be uniformly distributed on the inner edge of the anchor region fixing portion 201b, and may be spaced apart from each other, or may be non-uniformly distributed, each of the limiting pillars extends along a direction perpendicular to the top surface of the diaphragm 201, and a top end and a bottom end of each of the limiting pillars are protruded with respect to the diaphragm 201, that is, a top surface of each of the limiting pillars is higher than a top surface of the vibrating portion 201a and a top surface of the anchor region fixing portion 201b, and a bottom surface of each of the limiting pillars is lower than a bottom surface of the vibrating portion 201a and a bottom surface of the anchor region fixing portion 201 b. Therefore, even if the translation of the vibrating part 201a exceeds the requirement during vibration, the translation does not exceed the top end and the bottom end of the limiting column under the blocking action of the corresponding limiting column, so that the problem that the vibrating part 201a is overlapped with the anchor area fixing part 201b during vibration can be solved.
It should be understood that the top end and the bottom end of the limiting column shown in fig. 8 and 9 are both convex with respect to the diaphragm 201, but the technical solution of the present embodiment is not limited thereto. In another example of the embodiment, the top ends of a part of the limiting columns may be protruded with respect to the diaphragm 201, and the bottom ends of another part of the limiting columns are protruded with respect to the diaphragm 201, so that the problem that the vibrating portion 201a overlaps with the anchor region fixing portion 201b during vibration can be improved. In another example of the embodiment, when only a bad condition that the vibrating portion is overlapped above or below the anchor portion occurs in the use process of the MEMS microphone due to process errors and the like, the top ends or the bottom ends of all the limiting posts may be adaptively set to be convex with respect to the diaphragm 201 according to the problem condition.
Further optionally, the limiting column is a circular column or a triangular prism or any other suitable column structure, so that the vibrating portion 201a is easily rebounded when moving to the surface of the side wall of the limiting column, and the problem of overlapping between the vibrating portion 201a and the anchor area fixing portion 201b is avoided to the greatest extent. In addition, when the diaphragm 201 is in contact with the limiting column due to vibration, the protruding degree of the limiting column in the direction perpendicular to the top surface of the diaphragm exceeds the amplitude of the vibrating portion, so that the vibrating portion 201a is not easily overlapped with the anchor region fixing portion 201b, and the problem of clamping between the vibrating portion 201a and the anchor region fixing portion 201b can be avoided.
As another example, referring to fig. 10, the contact preventing portion 201f includes at least one limit baffle surrounding the inner edge of the anchor fixing portion 201b with a desired width and extending in a direction perpendicular to the top surface of the diaphragm 201, and both top and bottom ends of the limit baffle are convex with respect to the diaphragm 201, i.e., the top surface of the limit baffle is higher than the top surface of the vibrating portion 201a and the top surface of the anchor fixing portion 201b, and the bottom surface of the limit baffle is lower than the bottom surface of the vibrating portion 201a and the bottom surface of the anchor fixing portion 201 b. Therefore, even if the vibrating portion 201a vibrates, the vibrating portion 201a does not extend beyond the top end and the bottom end of the limit baffle due to the blocking effect of the limit baffle, and therefore the problem that the vibrating portion 201a overlaps the anchor fixing portion 201b does not occur.
Further, it is to be understood that the limit stop is actually a member having a larger width extending along the inner edge of the anchor fixing portion 201b, with respect to the above-described limit post, the maximum width of the limit stop corresponding to a closed enclosure wall surrounding the inner edge of the anchor fixing portion 201b for one turn, and the minimum width of the limit stop corresponding to the limit post, the width of which is the minimum width allowed by the process, and therefore, the cross-sectional structure of the MEMS microphone having the limit stop can be referred to as shown in fig. 9. In addition, in the example, when the limiting baffle can be manufactured by filling corresponding materials in the groove with a large length, the process window relative to the limiting column and the limiting protrusion is larger, and the process difficulty can be reduced. But the scheme of spacing post, the scheme of relative limit baffle, more material saving also can be better play prevent the overlap joint prevent the purpose of screens simultaneously.
Further optionally, a surface (i.e., an inner side surface) of a side wall of the position-limiting baffle facing the vibrating portion 201a is a smooth curved surface, so that the vibrating portion 201a is easily rebounded when moving to the surface of the side wall of the position-limiting baffle, thereby avoiding the problem of overlapping or blocking between the vibrating portion 201a and the anchor area fixing portion 201b during vibration to the greatest extent.
It should be noted that the top end and the bottom end of the limiting baffle in the above example are both convex with respect to the diaphragm 201, but the technical solution of the present embodiment is not limited thereto. In another example of this embodiment, for the same limiting baffle, the top end of one partial region of the limiting baffle may be set to be convex relative to the top end of the diaphragm 201, while the bottom end of the other partial region may be set to be convex relative to the bottom end of the diaphragm 201; alternatively, for a plurality of limiting baffles, the top ends of a part of the limiting baffles may be protruded relative to the top end of the diaphragm 201, while the bottom ends of another part of the limiting baffles may be protruded relative to the bottom end of the diaphragm 201. Thus, the combined effect of the top and bottom ends of the position-limiting baffles can avoid the problem that the vibrating part 201a is overlapped or clamped with the anchoring area fixing part 201b during vibration. In another example of the embodiment, when only the vibrating portion is overlapped above or below the anchor portion during the use of the MEMS microphone due to process errors and the like, the top ends or the bottom ends of all the limiting baffles may be adaptively set to be convex with respect to the diaphragm 201 according to the problem.
It should be understood that, in the examples shown in fig. 8 to 10, the contact preventing portions 201f are each fixed on the inner edge of the anchor fixing portion 201b, thereby avoiding affecting the sensitivity of the vibrating portion 201 a. However, the technical solution of the present embodiment is not limited to this, and in another example of the present embodiment, the contact preventing portion 201f may be fixedly disposed on the outer edge of the vibrating portion 201a in a case where the vibrating space of the vibrating portion 201a is sufficiently large and the sensitivity of the vibrating portion 201a allows. In another example of the present embodiment, in a case where the vibration space of the vibrating portion 201a is large enough and the sensitivity of the vibrating portion 201a allows, there may be a part of the limiting column or the limiting baffle disposed on the outer edge of the vibrating portion 201a and another part of the limiting column or the limiting baffle disposed on the inner edge of the anchor region fixing portion 201b, and the contact preventing portion on the outer edge of the vibrating portion 201a and the contact preventing portion on the inner edge of the anchor region fixing portion 201b may be aligned or distributed in a misaligned manner. In yet other examples of this embodiment, the contact preventing portion 201f on the inner edge of the anchor fixing portion 201b and/or the outer edge of the vibrating portion 201a may have both a stopper post and a stopper baffle.
Third embodiment
Referring to fig. 11, the present embodiment provides an MEMS microphone, which has a diaphragm 201 and a channel 201c penetrating the diaphragm 201 from top to bottom, the channel 201c dividing the diaphragm 201 into a vibrating portion 201a and an anchor fixing portion 201b surrounding the vibrating portion 201 a.
In this embodiment, the contact preventing portion 201f includes both the limiting protrusion provided in the first embodiment and the limiting baffle and/or the limiting post provided in the second embodiment.
As an example, each limiting protrusion is a structure independent from the limiting baffle or the limiting column, that is, each limiting protrusion is not only spaced apart from each other, but also spaced apart from the adjacent limiting baffle or the limiting column.
As another example, each limit protrusion may be disposed on a side wall of the corresponding limit baffle or limit post, and in this case, each limit protrusion and the corresponding limit baffle or limit post may be integrally formed.
Other structures of the MEMS microphone of the present embodiment are the same as those of the first and second embodiments, and reference is made to the above, and detailed description thereof is omitted.
Fourth embodiment
Referring to fig. 5 to 12, the present embodiment further provides a method for manufacturing a MEMS microphone, including:
s1, forming a first sacrificial layer on the substrate, and depositing a diaphragm on the first sacrificial layer;
s2, etching the diaphragm to form a channel penetrating through the diaphragm, wherein the channel divides the diaphragm into a vibrating part and an anchor area fixing part surrounding the periphery of the vibrating part;
s3, forming a second sacrificial layer and a back plate on the diaphragm;
s4, forming a plurality of sound holes on the back plate;
s5, releasing the second sacrificial layer and the first sacrificial layer to form a vibration space required for the vibration part.
Referring to fig. 12 (a), in step S1, first, a substrate 200 is provided, where the substrate 200 may be at least one of the following materials: silicon, silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator-silicon-germanium (S-SiGeOI), silicon-on-insulator-silicon-germanium (SiGeOI), and germanium-on-insulator (GeOI), among others. Then, a patterned first sacrificial layer 204 is formed on the substrate 200, specifically, a sacrificial material film layer, which may be an inorganic insulating layer such as a silicon oxide layer, a silicon nitride layer, or a silicon oxynitride layer, and may be an organic insulating layer including polyvinyl phenol, polyimide, or siloxane, is covered on the substrate 200 by a suitable process method such as deposition or coating, and the sacrificial material film layer is further etched by photolithography and etching processes until the surface of the substrate 200 is exposed, so as to form the patterned first sacrificial layer 204, wherein the purpose of patterning the first sacrificial layer 204 may be to define a formation region of the diaphragm 201, and/or to define a portion of the first sacrificial layer 204 used for forming a back cavity and a portion used for being finally left as a vibration portion 201a and an anchor region fixing portion 201b for fixing the diaphragm 201. Next, the first sacrificial layer 204 and the exposed surface of the substrate 200 are covered with the diaphragm 201 by a suitable process, such as a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method, or an Atomic Layer Deposition (ALD) method, wherein the material of the diaphragm 201 may be, but is not limited to, metal, polysilicon doped with N-type ions, such as phosphorus, polysilicon doped with P-type ions, such as boron.
With continued reference to fig. 12 (a), in step S2, a mask plate for diaphragm lithography is used to perform lithography and etching processes, the diaphragm 201 is etched to the top surface of the first sacrificial layer 204, an excess portion of the diaphragm 201 on the outer edge of the first sacrificial layer 204 is removed, and a channel 201c penetrating the diaphragm 201 is formed in the diaphragm 201, and the channel 201c divides the remaining diaphragm 201 into a vibrating portion 201a and an anchor region fixing portion 201 b. This step is to pattern the diaphragm 201.
It should be noted that the method for forming the first sacrificial layer 204 and the diaphragm 201 is not limited to the above examples, and any suitable method known to those skilled in the art may be used to form the patterned first sacrificial layer 204 and the diaphragm 201 on the substrate 200. For example, a channel (not shown) is formed in the first sacrificial layer 204 by depositing, photolithography and etching a sacrificial material film, and then the diaphragm 201 filled in the channel of the first sacrificial layer 204 is formed by depositing, planarizing and the like; for another example, a channel (not shown) is formed in the substrate 200 by photolithography and etching processes, and a desired first sacrificial layer 204 is formed in the channel of the substrate 200 by sacrificial material deposition in combination with Chemical Mechanical Polishing (CMP) and/or etch-back, and then the diaphragm 201 on the substrate 200 and the first sacrificial layer 204 is formed by diaphragm material deposition in combination with photolithography, Chemical Mechanical Polishing (CMP), etch-back, and/or etch-back, and the like.
Referring to (B) and (D) of fig. 12, in step S3, first, a patterned second sacrificial layer 205 is formed on the surface of the remaining diaphragm 201 and the exposed first sacrificial layer 204 by sacrificial material deposition, photolithography and etching, wherein the material of the patterned second sacrificial layer 205 may be an inorganic insulating layer such as a silicon oxide layer, a silicon nitride layer or a silicon oxynitride layer, and may be an organic insulating layer including polyvinyl phenol, polyimide or siloxane, and the purpose of forming the patterned second sacrificial layer 205 includes defining a contact hole for exposing the diaphragm vibrating portion 201a for outward leading, and/or defining a portion of the second sacrificial layer for forming a cavity and a portion of a support structure for being finally left as a back plate. Then, a back plate material is covered on the second sacrificial layer 205 and the exposed surfaces of the diaphragm 201, the first sacrificial layer 204 and the substrate 200 by a suitable process such as a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method or an Atomic Layer Deposition (ALD) method to form the back plate 203. The backplate 203 includes a backplate conductive layer 203a and a backplate protective layer 203b, and the backplate conductive layer 203a may be made of metal, polysilicon doped with N-type ions such as phosphorus, polysilicon doped with P-type ions such as boron, or the like, but is not limited to any one.
Referring to fig. 12 (E), in step S4, acoustic holes (not labeled) are formed in the back plate 203 through the back plate 203 by corresponding photolithography and etching processes.
Optionally, after the step S4 is executed and before the step S5 is executed, the method for manufacturing a MEMS microphone of this embodiment further includes: forming a conductive pad 206 electrically connected with the backplate 203 and a conductive pad 206 electrically connected with the diaphragm 201 on the backplate 203; back thinning is performed on the substrate 200; and etching the back surface of the substrate 200 (i.e., the surface of the substrate 200 facing away from the diaphragm 201) by corresponding photolithography and etching processes to form a back cavity 200a exposing a portion of the surface of the first sacrificial layer 204.
With continued reference to fig. 12 (E), in step S5, the first sacrificial layer 204 and the second sacrificial layer 205 are wet-etched through the acoustic holes and the back cavity 200a to remove a portion of the second sacrificial layer 205 between the backplate 203 and the diaphragm 201 and a portion of the first sacrificial layer 204 between the diaphragm 201 and the substrate 200, so as to form a cavity 202, and the back cavity 200a exposes the back surface of the diaphragm 201.
As an example, in the above-described step S2, the mask plate for diaphragm lithography is used which has not only the patterns of the vibration portion 201a, the anchor region fixing portion 201b, and the channel 201c but also the pattern of the stopper protrusion 201e serving as the contact preventing portion required in fig. 5 to 7. Thus, in step S2, after the diaphragm 201 is subjected to photolithography and etching processes using the mask plate for diaphragm photolithography, the vibration portion 201a, the anchor region fixing portion 201b, and the channel 201c are formed, and at the same time, the limiting protrusion 201e is formed on the outer edge of the vibration portion 201a and/or the inner edge of the anchor region fixing portion 201 b.
Further alternatively, after the vibration part 201a, the anchor fixing part 201b, the channel 201c, and the stopper protrusion 201e are formed, the sidewall of the channel 201c may be rounded such that the sidewall surface of the stopper protrusion 201e protrudes toward the sidewall of the vibration part 201a and is rounded.
As another example, after step S2 and before forming the back plate 203 in step S3, the manufacturing method of the MEMS microphone of the present embodiment requires that a stopper post and/or a stopper baffle serving as the contact preventing portion 201f be fabricated on the outer edge of the vibrating portion 201a and/or the inner edge of the anchor fixing portion 201 b.
Specifically, in step S3, first, referring to (a) and (B) in fig. 12, a second sacrificial layer 205a is deposited, wherein the thickness of the second sacrificial layer 205a is enough to fill the channel 201c and cover the diaphragm 201 with a desired thickness, and the thickness is not less than the height difference between the top ends of the position-limiting pillars and position-limiting baffles and the top surface of the diaphragm 201. Then, the second sacrificial layer 205a and the first sacrificial layer 204 with a partial thickness at the channel 201c are etched to form a groove 201c ' with a depth greater than that of the channel 201c, the bottom surface of the groove 201c ' is lower than that of the diaphragm 201, a height difference between the bottom surface of the groove 201c ' and the bottom surface of the diaphragm 201 is equal to a height difference between the bottom ends of the position-limiting pillar and the position-limiting baffle and the bottom surface of the diaphragm 201, a width of the groove 201c ' is smaller than that of the channel 201c, and a sidewall of one side of the groove 201c ' is exposed out of a sidewall of the anchor region fixing portion 201b or a sidewall of the vibrating portion 201 a. Next, referring to fig. 12 (C), a material layer for forming the stopper and the stopper is deposited on the second sacrificial layer 205a, and the material layer fills the groove 201C'. Thereafter, the excess material layer on the surface of the second sacrificial layer 205a may be removed by an etching process or a chemical mechanical polishing CMP process to form a desired stopper post and/or stopper serving as the contact prevention portion 201 f. Then, referring to (D) of fig. 12, a second sacrificial material layer 205b is deposited on the second sacrificial layer 205a and the contact preventing portion 201f, so that the second sacrificial layer 205a and the second sacrificial layer 205b together form the desired second sacrificial layer 205.
After releasing second sacrificial layer 205 and first sacrificial layer 204 in step S5, the stopper posts and/or stopper plates are left to solve the problem of overlapping of vibrating portion 201a and anchor fixing portion 201 b.
In summary, according to the technical scheme of the present invention, the anti-contact portion is formed on the inner edge of the anchor region fixing portion or the outer edge of the vibrating portion of the diaphragm, and the anti-contact portion includes at least one of the limiting protrusion, the limiting post and the limiting baffle, so that the problem of clamping or overlapping between the vibrating portion of the diaphragm and the anchor region fixing portion during vibration can be effectively prevented, and the device performance is improved.
The above description is only for the purpose of describing the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the present invention.
Claims (10)
1. An MEMS microphone is provided with a vibrating diaphragm and a channel penetrating through the vibrating diaphragm, wherein the channel divides the vibrating diaphragm into a vibrating part and an anchor area fixing part surrounding the periphery of the vibrating part, and is characterized in that an anti-contact part is arranged on the outer edge of the vibrating part and/or the inner edge of the anchor area fixing part; and at least part of the side wall of the contact preventing part is arranged in the channel in a protruding mode, and/or at least one end of the top end and the bottom end of the contact preventing part is protruded relative to the vibrating membrane.
2. The MEMS microphone of claim 1, wherein when at least a portion of the sidewall of the contact prevention part is protrudingly provided in the channel, the contact prevention part comprises at least one stopper protrusion, each of which is protrudingly provided in the channel in a direction parallel to the top surface of the diaphragm.
3. The MEMS microphone of claim 2, wherein the stopper protrusion on the inner edge of the anchor fixing portion is integrally formed with the anchor fixing portion, and/or the stopper protrusion on the outer edge of the vibrating portion is integrally formed with the vibrating portion.
4. The MEMS microphone as claimed in claim 1 or 2, wherein when at least one of a top end and a bottom end of the contact preventing portion is protruded with respect to the diaphragm, the contact preventing portion includes at least one stopper pillar, adjacent ones of the stopper pillars are spaced apart from each other, and each of the stopper pillars extends in a direction perpendicular to the top surface of the diaphragm and at least one of the top end and the bottom end is protruded with respect to the diaphragm; and/or the contact preventing part comprises at least one limit baffle, each limit extends along a direction vertical to the top surface of the vibrating diaphragm, and at least one end of the top end and the bottom end is convex relative to the vibrating diaphragm.
5. The MEMS microphone of claim 4, wherein the retaining post and the retaining stop are each fixedly disposed only on an inner edge of the anchor fixing portion.
6. The MEMS microphone of claim 4, wherein the material of the retaining post and the retaining stop comprises at least one of silicon nitride, silicon oxynitride, polysilicon, and metal.
7. The MEMS microphone of claim 1, further comprising a substrate and a plurality of point fasteners, each of the point fasteners securing the vibrating portion to a corresponding point of the substrate, an outer edge of the anchor region securing portion being integrally secured to the substrate.
8. A method of manufacturing a MEMS microphone, comprising:
forming a first sacrificial layer on a substrate, and depositing a diaphragm on the first sacrificial layer;
etching the vibrating diaphragm to form a channel penetrating through the vibrating diaphragm, wherein the channel divides the vibrating diaphragm into a vibrating part and an anchor area fixing part surrounding the periphery of the vibrating part;
forming a second sacrificial layer and a back plate on the vibrating diaphragm;
the method is characterized in that in the step of etching the vibrating diaphragm, at least one limiting bulge is further formed in the channel and positioned on the outer edge of the vibrating part or the inner edge of the anchor area fixing part, and at least part of the side wall of each limiting bulge is convexly arranged in the channel;
and/or, before or after the step of forming the second sacrificial layer on the diaphragm, a stopper post and/or a stopper baffle on an outer edge of the vibrating portion or an inner edge of the anchor fixing portion are further formed in the channel, at least one of a top end and a bottom end of the stopper post and/or the stopper baffle being convex with respect to the diaphragm.
9. The method of manufacturing a MEMS microphone according to claim 8, further comprising, after forming the backplate:
forming a plurality of sound holes on the back plate;
releasing the second sacrificial layer and the first sacrificial layer to form a vibration space required for the vibration part.
10. The method of manufacturing a MEMS microphone according to claim 9, further comprising, after forming the plurality of sound holes on the back plate:
forming a conductive bonding pad which is electrically connected with the back plate and a conductive bonding pad which is electrically connected with the vibrating diaphragm on the back plate respectively;
etching the back surface of the substrate to form a back cavity exposing the back surface of the first sacrificial layer;
wherein the second sacrificial layer and the first sacrificial layer are released through the acoustic aperture and the back cavity.
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| CN117835132A (en) * | 2022-09-29 | 2024-04-05 | 歌尔微电子股份有限公司 | Micro-electromechanical chip |
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Effective date of registration: 20220920 Address after: No. 518, Linjiang Road, Gaobu Town, Yuecheng District, Shaoxing City, Zhejiang Province Patentee after: Shaoxing SMIC integrated circuit manufacturing Co.,Ltd. Patentee after: SEMICONDUCTOR MANUFACTURING INTERNATIONAL (SHANGHAI) Corp. Address before: 518 Shaoxing Road, Zhejiang Province Patentee before: Shaoxing SMIC integrated circuit manufacturing Co.,Ltd. |