CN113259821B - Microphone and method for manufacturing the same - Google Patents
Microphone and method for manufacturing the same Download PDFInfo
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- CN113259821B CN113259821B CN202110669390.1A CN202110669390A CN113259821B CN 113259821 B CN113259821 B CN 113259821B CN 202110669390 A CN202110669390 A CN 202110669390A CN 113259821 B CN113259821 B CN 113259821B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/005—Electrostatic transducers using semiconductor materials
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R19/00—Electrostatic transducers
- H04R19/04—Microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
- H04R2201/003—Mems transducers or their use
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- Manufacturing & Machinery (AREA)
- Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
Abstract
The invention provides a microphone and a manufacturing method thereof, wherein the thickness of a film layer material for manufacturing a back cavity can be relatively increased by adding a groove on the front surface of a substrate, a larger debugging space is provided for etching the back cavity, the increase of etching time from the direction of adjusting a process formula is facilitated, and then a sharp corner formed on the front surface of the substrate after etching the back cavity is improved or eliminated, and when the sharp corner formed on the front surface of the substrate after etching the back cavity can not be completely eliminated by adjusting the process formula, the distance from the sharp corner on the front surface of the substrate to a vibrating diaphragm can be increased by adding the groove, so that the vibrating diaphragm can not touch the sharp corner during vibration, and the reliability and the yield of devices are improved. In addition, the groove on the front surface of the substrate is additionally arranged, so that the thickness of the first sacrificial layer on the periphery of the groove can be reduced on the premise of not sacrificing the performance of the device, and the microphone can be developed towards smaller size.
Description
Technical Field
The invention relates to the technical field of semiconductor device manufacturing, in particular to a microphone and a manufacturing method thereof.
Background
Referring to fig. 1, a conventional MEMS (Micro-Electro-Mechanical System) microphone is manufactured by a process including: etching the back surface of the substrate 100 to open the substrate 100 to form an opening, wherein the sacrificial layer 101 serving as an etching stop layer of the substrate 100 needs to have a certain thickness in the process; then, a portion of the sacrificial layer 101 is etched and removed through the opening to form a back cavity 101a exposing the diaphragm 102, and a certain amount of the sacrificial layer 101 is required to be left after the back cavity 101a is formed to serve as a supporting fence for supporting the diaphragm 102.
As the technology advances, the MEMS microphone is developed toward smaller size, high quality electrical performance and lower loss, and the thickness of the sacrificial layer 101 and the diaphragm 102 therein is also reduced as the size of the MEMS microphone is reduced. However, in the above-mentioned manufacturing process of the MEMS microphone, on one hand, after the back cavity 101a is formed, a sharp corner 100a is easily formed at a position of the opening of the substrate 100 close to the diaphragm 102, so that the diaphragm 102 easily touches the sharp corner 100a during vibration, and the diaphragm 102 is broken, and the device fails, resulting in yield loss; on the other hand, if the sacrificial layer 101 is designed to be thin, it will create a huge challenge for etch debugging of the back cavity 101 a.
In addition, since the sacrificial layer 101 is spread on the front surface of the substrate 100, when the process recipe is adjusted, for example, a certain degree of over-etching is performed when the substrate 100 is etched to form an opening, so as to eliminate the sharp corner 100a, if the over-etching process causes the sacrificial layer 101 in the back cavity 101a area to be etched open, thereby exposing the diaphragm 102, the diaphragm 102 may be abnormal when the sacrificial layer 101 in the back cavity 101a area is subsequently released through the opening. Moreover, the abnormality of the diaphragm can affect the performance of the device and even cause the failure of the device.
Disclosure of Invention
The invention aims to provide a microphone and a manufacturing method thereof, which not only can increase the debugging space of back cavity etching, but also can avoid the problem that a vibrating diaphragm is broken due to the fact that the vibrating diaphragm touches the sharp corner of a substrate and improve the yield of devices.
In order to solve the above technical problem, the present invention provides a method for manufacturing a microphone, including:
providing a substrate with a front surface and a back surface, and forming a groove with the depth not penetrating through the substrate on the front surface of the substrate;
filling an etching stop layer in the groove and forming a first sacrificial layer covering the groove on the front surface of the substrate;
sequentially forming a vibrating diaphragm and a back plate of the microphone on the first sacrificial layer;
performing back etching on the substrate to form an opening exposing part of the back surface of the etching stop layer, wherein the boundary of one side of the opening, which is close to the etching stop layer, falls within the range of the bottom surface of the groove;
and etching the etching stop layer and the first sacrificial layer through the opening to form a back cavity exposing the back surface of the diaphragm and a first supporting wall surrounding the back cavity.
Based on the same inventive concept, the present invention also provides a microphone, comprising:
the substrate is provided with a front surface and a back surface, a groove with the depth not penetrating through the substrate is formed on the front surface of the substrate, an opening communicated with the groove is formed on the back surface of the substrate, and the boundary of the opening close to one side of the bottom surface of the groove falls within the range of the bottom surface of the groove;
a diaphragm positioned above the front side of the substrate;
the first supporting wall is at least clamped between the vibrating diaphragm and the substrate and surrounds a back cavity between the vibrating diaphragm and the front surface of the substrate, and the back cavity is communicated with the groove;
the back plate is positioned above the vibrating diaphragm;
and the second support wall is at least clamped between the vibrating diaphragm and the back plate and surrounds a cavity between the vibrating diaphragm and the back plate.
Compared with the prior art, the technical scheme of the invention has at least one of the following beneficial effects:
1. the thickness of a film layer material for manufacturing the back cavity can be relatively increased by additionally arranging the groove on the front surface of the substrate, a larger debugging space is provided for back cavity etching, the etching time can be prolonged from the direction of adjusting a process formula (recipe), and then a sharp corner formed on the front surface of the substrate after the back cavity etching is improved or eliminated.
2. When the sharp corner formed on the front surface of the substrate after back cavity etching can not be completely eliminated by adjusting the process formula, the distance from the sharp corner on the front surface of the substrate to the vibrating diaphragm can be increased by the additionally arranged groove, so that the vibrating diaphragm can not touch the sharp corner during vibration, and the reliability and yield of devices are improved.
3. By additionally arranging the groove on the front surface of the substrate, the thickness of the first sacrificial layer on the periphery of the groove is favorably reduced on the premise of not sacrificing the performance of the device, and further, the microphone is favorably developed towards smaller size.
Drawings
Fig. 1 is a schematic cross-sectional structure diagram of a MEMS microphone in the prior art.
Fig. 2 is a flow chart of a method of manufacturing a microphone according to an embodiment of the invention.
Fig. 3 to 11 are schematic cross-sectional views of device structures in a method for manufacturing a microphone according to an 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. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like reference numerals refer to like elements throughout. It will be understood that when an element or layer is referred to as being "on" …, "or" connected to "other elements or layers, it can be directly on, connected to, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …", "directly connected to" other elements or layers, there are no intervening elements or layers present. Although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. Spatial relationship terms such as "below … …", "below", "lower", "above … …", "above", "upper", and the like may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" … …, or "beneath" would then be oriented "on" other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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," when used in this specification, 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. In addition, in the present application, the "front surface" of a certain component is also the top surface and the upper surface thereof, and the "back surface" of a certain component is also the bottom surface and the lower surface thereof, for example, the front surface of a substrate is the top surface and the upper surface of the substrate, the back surface of the substrate is the bottom surface and the lower surface of the substrate, the top surface of a groove is the upper surface and the front surface of the groove, and is also the boundary of the groove on the side of the front surface of the substrate, and the bottom surface of the groove is the lower surface and the back surface of the groove, and is also the boundary of the groove on the side of the front surface facing away from the substrate; the top surface of the opening formed by back-etching the substrate, i.e., the boundary of the opening on the side close to the etching stopper layer, is also the front surface of the opening, and the bottom surface of the opening formed by back-etching the substrate, i.e., the boundary of the opening on the side close to the back surface of the substrate, is also the back surface of the opening.
The technical solution proposed by the present invention will be further described in detail 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.
Referring to fig. 2, a method for manufacturing a microphone according to an embodiment of the present invention includes:
s1, providing a substrate with a front surface and a back surface, and forming a groove with a depth not penetrating through the substrate on the front surface of the substrate;
s2, filling an etching stop layer in the groove and forming a first sacrificial layer covering the groove on the front surface of the substrate;
s3, sequentially forming a diaphragm and a back plate of the microphone on the first sacrificial layer;
s4, performing back etching on the substrate to form an opening exposing partial back of the etching stop layer, wherein the boundary of the opening close to the etching stop layer is in the range of the bottom surface of the groove;
and S5, etching the etching stop layer and the first sacrificial layer through the opening to form a back cavity exposing the back surface of the diaphragm and a first supporting wall surrounding the back cavity.
Referring to fig. 3, in step S1, first, a substrate 200 having a front side S1 and a back side S2 opposite to each other is provided, wherein 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. In which elements such as transistors may be formed, device isolation structures may be formed, and the like. Then, a groove 200a having a depth not penetrating through the substrate 200 is formed on the front surface S1 of the substrate 200 by photolithography and etching processes.
Referring to fig. 4 and 5, in step S2, first, an etching stop layer 201 is filled in the recess 200a through a chemical vapor deposition process or a thermal oxidation process until the etching stop layer fills the recess 200 a; then, the front surface of the etch stop layer 201 is planarized to be flush with the front surface 200a of the substrate 200 by a Chemical Mechanical Planarization (CMP) process; a first sacrificial layer 202 is then covered on the front side S1 of the substrate 200 and the front side of the etch stop layer 201 by a suitable process method such as deposition or coating. The material of the etch stop layer 201 may be different from the material of the first sacrificial layer 202. The material of the etching stop layer 201 includes at least one of silicon oxide, silicon nitride, silicon oxynitride, and carbon-doped silicon nitride, and the material of the first sacrificial layer 202 may include an inorganic insulating layer of at least one of a silicon oxide layer, a silicon nitride layer, and a silicon oxynitride layer, an organic insulating layer including at least one of polyvinyl phenol, polyimide, siloxane, or the like, or a film structure in which an inorganic insulating layer and an organic insulating layer are stacked. The stacking thickness of the first sacrificial layer 202 and the etch stop layer 201 at the groove 200a needs to meet the requirement of the microphone on the depth of the back cavity, the thickness of the first sacrificial layer 202 on the substrate 200 at the periphery of the groove 200a needs to meet the requirement of the microphone on the height of the first support wall, for example, the thickness of the first sacrificial layer 202 on the substrate 200 at the periphery of the groove 200a is less than or equal to 0.5 micrometer, and the thickness of the etch stop layer 201 (i.e., the depth of the groove 200 a) may be in a micrometer level or a submicron level. In addition, in the present invention, the materials of the etch stop layer 201 and the first sacrificial layer 202 are not limited to the above examples, and may be any suitable materials known to those skilled in the art.
Optionally, after depositing the first sacrificial layer 202, the front surface of the first sacrificial layer 202 is planarized to a thickness and a flatness of the first sacrificial layer 202, which both meet the manufacturing requirements of the microphone.
Referring to fig. 5, in step S3, a diaphragm 203 and a back plate of a microphone are sequentially formed on the front surface of the first sacrificial layer 202, which includes the following specific steps:
first, the first sacrificial layer 202 is etched by photolithography and etching processes to expose a portion of the surface of the substrate 200 at the periphery of the groove 200a, so as to pattern the first sacrificial layer 202. Then, a diaphragm material is covered on the first sacrificial layer 202 and the exposed front surface S1 of 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, and the deposited diaphragm material is patterned by a photolithography and etching process to form a diaphragm 203 required for a microphone, where a part of the surface of the first sacrificial layer 202 is exposed by the diaphragm 203. The material of the diaphragm 203 may be 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. Of course, the material of the diaphragm 203 is not limited to the above examples, and may be any suitable material known to those skilled in the art.
Then, a second sacrificial layer 204 is covered on the diaphragm 203 and the exposed front surface of the first sacrificial layer 202 and the substrate 200 by a suitable process method such as deposition or coating, the material of the second sacrificial layer 204 may be an inorganic insulating layer including at least one of a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, or the like, and may be an organic insulating layer including at least one of polyvinyl phenol, polyimide, siloxane, or the like, and the second sacrificial layer 204 is further patterned by a photolithography and etching process. In addition, the same material and the same deposition or coating method can be used for the first sacrificial layer 202 and the second sacrificial layer 204, thereby simplifying the process.
Next, a back plate material is covered on the front surface of the second sacrificial layer 204 and the exposed front surface S1 of the substrate 200, the diaphragm 203 and the front surface of the first sacrificial layer 202 by a suitable process such as a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method or an Atomic Layer Deposition (ALD), and the back plate material is a stacked structure and may include a bottom dielectric layer (not shown), a back plate electrode layer 205 and a top dielectric layer 206 which are stacked in sequence. Before the back plate electrode layer 205 is deposited, the bottom dielectric layer is patterned through photoetching and etching processes; patterning the back plate electrode layer 205 by photolithography and etching processes between the deposited top dielectric layers 206; after the top dielectric layer 206 is deposited, the backplane is formed, i.e. the backplane now consists of a patterned bottom dielectric layer (not shown), a patterned backplane electrode layer 205, and a top dielectric layer 206. The material of the back plate electrode layer 205 may be 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. The material of the bottom dielectric layer and the top dielectric layer may be the same, but the material of the bottom dielectric layer is different from that of the second sacrificial layer 204. The material of the bottom dielectric layer and the top dielectric layer can be at least one selected from silicon oxide, silicon nitride and silicon oxynitride.
Optionally, after depositing the top dielectric layer 206, the top dielectric layer 206 is patterned by photolithography and etching processes, contact holes are formed in the top dielectric layer 206, and the contact holes are filled with a conductive material to form the contact plugs 207a and 207 b.
Optionally, after forming the contact plugs 207a, 207b, the top dielectric layer 206, the backplate electrode layer 205 and the bottom dielectric layer are etched to expose part of the surface (i.e. part of the front surface) of the second sacrificial layer 204 to form a number of release holes 208 through the backplate, the release holes 208 remaining after the microphone fabrication is completed and serving as sound holes for the microphone.
Referring to fig. 5 and 6, in step S4, the substrate 200 is back-etched from the back side S2 of the substrate 200 to form an opening 200b exposing a portion of the back side of the etch stop layer 201.
It should be noted that some flaring and offset phenomena may be allowed to occur when etching from the front side of the substrate 200 to form the recess 200a and etching from the back side of the substrate to form the opening 200 b. For example, the size of the opening of the recess 200a on the front surface of the substrate 200a is allowed to be larger than or smaller than or equal to the size of the opening of the bottom surface of the recess 200a, and the recess 200a may have a shape with a large top and a small bottom, or a large top and a small bottom; for another example, the opening 200b is allowed to take a shape of large top and small bottom or the same size as top and bottom; as another example, the center of the opening 200b is allowed to be perfectly aligned with or offset from the center of the recess 200 a. However, in any case, in this step S4, it is necessary to ensure that the boundary of the opening 200b on the side next to the etching stop layer 201 falls entirely within the range of the bottom surface of the recess 200a shown in fig. 3, that is, the opening size of the opening 200b on the side next to the etching stop layer 201 is required to be smaller than the opening size of the recess 200a, or the opening size is required to be stopped within the range defined by the bottom surface of the recess 200a when the substrate 200 is subjected to back etching.
In addition, the shape of the opening 200b and the groove 200a may be any suitable shape such as a circle, a polygon, an ellipse, a ring, etc., and the present invention is not particularly limited thereto.
Referring to fig. 6 and 7, in step S5, the etching stop layer 201 and the first sacrificial layer 202 are isotropically etched through the opening 200b, and the second sacrificial layer 204 is isotropically etched through the release hole 208, which may be a wet etching process or a vapor etching process, so as to form a back cavity 202a exposing a portion of the back surface of the diaphragm 203 and first support walls (i.e., including at least the remaining first sacrificial layer 202) surrounding the back cavity 202a, and form a cavity 204a exposing a portion of the front surface of the diaphragm 203 and second support walls (i.e., the remaining second sacrificial layer 204) surrounding the cavity 204 a.
As an example, after the back cavity 202a is formed, the etching stop layer 201 is remained, and it constitutes the first support wall together with the remaining first sacrificial layer 202.
In this embodiment, due to the existence of the groove 200a, the thickness from the front surface of the first sacrificial layer 201 to the bottom surface of the groove 200a is relatively increased, so that a larger debugging space can be provided for back cavity etching, and the increase of etching time from the direction of adjusting the process recipe is facilitated to improve the problem of sharp corners generated on the top end of the opening 200b at the bottom surface of the groove 200 a. For example, in one case, the process recipe can be adjusted during the etching process of the opening 200b formed on the back surface of the substrate 200, so as to eliminate the sharp corner generated at the top end of the opening 200b at the bottom surface of the groove 200a, as shown in fig. 7; in another case, even if the process recipe is adjusted during the process of etching the back surface of the substrate 200 to form the opening 200b, the sharp corner 200c generated at the top end of the opening 200b at the bottom surface of the groove 200a cannot be completely eliminated, as shown in fig. 8, but in this case, since the groove 200a increases the vertical distance from the sharp corner 200c to the diaphragm 203 (i.e., the distance between the two is increased by h compared to the prior art shown in fig. 1), the diaphragm 203 cannot touch the sharp corner 200c during vibration, thereby improving the reliability of the device.
Tests prove that when the thickness of the first sacrificial layer required between the substrate 200 and the vibrating diaphragm 203 is less than or equal to 0.5 micrometer, and when an opening 200b is formed from the back of the substrate 200 through an over-etching process and sharp corners are eliminated in the prior art, the vibrating diaphragm 203 is easily damaged due to loss of the first sacrificial layer 202, and the problem of diaphragm breaking is further caused.
It should be noted that the technical solution of the present invention is not limited to the above examples, and those skilled in the art can adaptively make reasonable changes to the scheme according to the needs.
For example, referring to fig. 9 and 10, after the recess 200a is formed in step S1, in step S2, the etching stop layer 201 and the first sacrificial layer 202 are directly formed by the same deposition process or thermal oxidation process, that is, the first sacrificial layer 202 fills the recess 200a and extends to cover the front surface S1 of the substrate 200 at the periphery of the recess 200a, which may be regarded as the same material for the etching stop layer 201 and the first sacrificial layer 202.
For another example, in an embodiment of the present invention, no matter the material of the etch stop layer 201 and the first sacrificial layer 202 is the same or different, after the back cavity 202a is formed by etching, no etch stop layer 201 and no first sacrificial layer 202 remain in the groove 200a, and at this time, the first support wall is located at the periphery of the groove 200a and is the remaining first sacrificial layer 202.
In addition, in other embodiments of the present invention, the etching stop layer 201 filled in the groove 200a does not necessarily need to be top-planarized (i.e. the front surface thereof is CMP-planarized), if the subsequently formed diaphragm 203 is required to be planarized, the etching stop layer filled in the groove 200a and the deposited additional first sacrificial layer 202 need to be top-planarized (i.e. the front surface thereof is CMP-planarized), the top planarization process may be performed after the etching stop layer 201 is filled in the groove 200, or after the first sacrificial layer 202 is deposited, or may be performed after a dielectric film layer exceeding the required stack thickness of the first sacrificial layer 202 and the etching stop layer 201 is deposited at one time.
Furthermore, in other embodiments of the present invention, if the design requires the diaphragm 203 to be corrugated, one way is: the etching stop layer 201, the first sacrificial layer 202 and the diaphragm 203 can be formed by sinking after the groove 200a is etched, the recess brought by the groove 200a cannot be eliminated by the conformal covering of the etching stop layer 201 and the first sacrificial layer 202, and the required folds are formed after the diaphragm 203 is conformal covered, so that the CMP leveling of the etching stop layer 201 and the first sacrificial layer 202 is not needed; the other method is as follows: after filling the etching stop layer 201 in the groove 200a, the etching stop layer 201 may be first subjected to CMP planarization, and/or, after depositing the first sacrificial layer 202, the first sacrificial layer 202 may be subjected to CMP planarization; thereafter, the required corrugations of the diaphragm 203 are made on the first sacrificial layer 202 by photolithography and etching processes.
In addition, in other embodiments of the present invention, the shape of the groove 200a may be any suitable shape, and is not limited to a circle, a polygon, etc., and may also be a concentric circle, a polygon ring, etc., but it is required that the finally formed back cavity 202a is recessed downward to a certain depth on the front surface of the substrate 202.
Based on the same inventive concept, please refer to fig. 4 to 11, an embodiment of the invention provides a microphone, which can be formed by the method for manufacturing the microphone of the invention. The microphone includes: a substrate 200, a first support wall, a diaphragm 203, a second support wall, and a back plate.
The substrate 200 has a front side S1 and a back side S2, a groove 200a with a depth not penetrating through the substrate 200 is formed on the front side S1 of the substrate 200, an opening 200b communicating with the groove 200a is formed on the back side S2 of the substrate 200, and a side boundary of the opening 200b close to the bottom surface of the groove 200a falls within the range of the bottom surface of the groove 200 a.
The diaphragm 203 is located above the front side S1 of the substrate 200, and a first supporting wall (i.e., the remaining first sacrificial layer 202) is at least sandwiched between the diaphragm 203 and the front side S1 of the substrate 200 and surrounds a back cavity 202a between the diaphragm 203 and the front side S1 of the substrate 200, wherein the back cavity 202a is communicated with the groove 200 a. Alternatively, the first support wall includes only the insulating film layer (i.e., the remaining first sacrificial layer 202) on the front surface S1 of the substrate 200 at the periphery of the recess 200 a; alternatively, the first support wall includes the etching stop layer 201 located in the recess 200a and located on the edge of the recess 200a, and the insulating film layer (i.e., the remaining first sacrificial layer 202) located on the front surface S1 of the substrate 200 at the periphery of the recess 200 a.
The back plate is located above the diaphragm 203, and the second support wall is at least sandwiched between the diaphragm 203 and the back plate and surrounds a cavity 204a between the diaphragm 203 and the back plate. The back plate has a plurality of sound holes (i.e., release holes 208) formed therethrough and communicating with the cavity 204 a.
Optionally, the backplate includes a bottom dielectric layer (not shown), a backplate electrode layer 205 and a top dielectric layer 206 sequentially stacked over the second support walls and the cavity 204 a.
In summary, according to the microphone and the manufacturing method thereof of the present invention, the thickness of the film material for manufacturing the back cavity can be relatively increased by adding the groove on the front surface of the substrate, a larger debugging space is provided for etching the back cavity, which is beneficial to increase the etching time from the direction of adjusting the process recipe (recipe), and further improve or eliminate the sharp corner formed on the front surface of the substrate after etching the back cavity, and when the sharp corner formed on the front surface of the substrate after etching the back cavity cannot be completely eliminated by adjusting the process recipe, the distance from the sharp corner on the front surface of the substrate to the diaphragm can be increased by adding the groove, so that the diaphragm cannot touch the sharp corner during vibration, and the reliability and yield of the device are improved. In addition, the groove on the front surface of the substrate is additionally arranged, so that the thickness of the first sacrificial layer on the periphery of the groove can be reduced on the premise of not sacrificing the performance of the device, and the microphone can be developed towards smaller size.
The above description is only for the purpose of describing the preferred embodiments 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 according to the above disclosure are within the scope of the present invention.
Claims (10)
1. A method of manufacturing a microphone, comprising:
providing a substrate with a front surface and a back surface, and forming a groove with the depth not penetrating through the substrate on the front surface of the substrate;
filling an etching stop layer in the groove and forming a first sacrificial layer covering the groove on the front surface of the substrate;
sequentially forming a vibrating diaphragm and a back plate of the microphone on the first sacrificial layer;
performing back etching on the substrate to form an opening exposing part of the back of the etching stop layer, wherein the boundary of one side of the opening close to the etching stop layer is positioned in the range of the bottom surface of the groove;
and etching the etching stop layer and the first sacrificial layer through the opening to form a back cavity exposing the back surface of the diaphragm and a first support wall surrounding the back cavity, wherein the opening and the groove enable the substrate on the side wall of the back cavity to have a step.
2. The method of claim 1, wherein the etch stop layer and the first sacrificial layer are made of the same material and are formed by a same deposition process or a thermal oxidation process, or the etch stop layer and the first sacrificial layer are made of different materials.
3. The method of manufacturing a microphone according to claim 2, further comprising: after the etching stop layer is filled in the groove and before the first sacrificial layer is formed, flattening the front surface of the etching stop layer to be flush with the front surface of the substrate; and/or after the first sacrificial layer is formed and before the diaphragm is formed on the first sacrificial layer, the thickness and the flatness from the front surface of the first sacrificial layer to the first sacrificial layer are both satisfactory.
4. The method of manufacturing a microphone according to claim 1, wherein the step of sequentially forming a diaphragm and a back plate of the microphone on the first sacrificial layer comprises:
patterning the first sacrificial layer by a photolithography and etching process;
depositing a diaphragm material, and patterning the diaphragm material through corresponding photoetching and etching processes to form the diaphragm;
depositing a second sacrificial layer to mask the diaphragm, and patterning the second sacrificial layer through corresponding photoetching and etching processes;
depositing a backplate material to mask the diaphragm, and patterning the backplate material by a corresponding photolithography and etching process to form the backplate.
5. The method of manufacturing a microphone according to claim 4, further comprising: after the back plate is formed and before the substrate is subjected to back etching, the back plate is etched to form a plurality of release holes exposing part of the second sacrificial layer.
6. The method of claim 5, wherein the etching stop layer and the first sacrificial layer are etched through the opening to form the back cavity, and simultaneously the second sacrificial layer is etched through the release hole to form a cavity exposing the front surface of the diaphragm and a second support wall surrounding the cavity.
7. The method of manufacturing a microphone according to claim 1, wherein the etching stopper layer in the groove is partially left after the back cavity is formed to form the first support wall together with the remaining first sacrificial layer; or, after the back cavity is formed, the etching stop layer in the groove is completely removed, and the remaining first sacrificial layer is used as the first support wall.
8. A microphone, comprising:
the substrate is provided with a front surface and a back surface, a groove with the depth not penetrating through the substrate is formed on the front surface of the substrate, an opening communicated with the groove is formed on the back surface of the substrate, and the boundary of the opening close to one side of the bottom surface of the groove falls within the range of the bottom surface of the groove;
a diaphragm positioned above the front side of the substrate;
the first supporting wall is at least clamped between the vibrating diaphragm and the substrate and surrounds a back cavity between the vibrating diaphragm and the front surface of the substrate, the back cavity is communicated with the groove, and the opening and the groove enable the substrate on the side wall of the back cavity to have a step;
the back plate is positioned above the vibrating diaphragm;
and the second support wall is at least clamped between the vibrating diaphragm and the back plate and surrounds a cavity between the vibrating diaphragm and the back plate.
9. The microphone of claim 8, wherein the first support wall includes only an insulating film layer on a front surface of the substrate at a periphery of the recess; or the first support wall comprises an etching stop layer which is positioned in the groove and positioned on the edge of the groove and an insulating film layer which is positioned on the front surface of the substrate at the periphery of the groove.
10. The microphone of claim 8, wherein the back plate has a plurality of sound holes formed therethrough and in communication with the cavity.
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| CN114827881B (en) * | 2022-06-29 | 2023-03-24 | 绍兴中芯集成电路制造股份有限公司 | Back cavity forming method, device with back cavity, MEMS microphone and preparation method |
| CN114827882B (en) * | 2022-07-01 | 2022-11-04 | 绍兴中芯集成电路制造股份有限公司 | Preparation method of microphone |
| CN117069053A (en) * | 2023-09-04 | 2023-11-17 | 武汉敏声新技术有限公司 | Semiconductor device and method for manufacturing the same |
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