CN115924838A - MEMS device, preparation method thereof and electronic device - Google Patents
MEMS device, preparation method thereof and electronic device Download PDFInfo
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Abstract
The invention provides an MEMS device, a preparation method thereof and an electronic device, wherein the method comprises the following steps: providing a substrate, wherein a first sacrificial layer is formed on the substrate, a vibrating diaphragm is formed on the first sacrificial layer, and a second sacrificial layer is formed on the vibrating diaphragm; forming an interface layer on the second sacrificial layer; forming a third sacrificial layer on the second sacrificial layer and the interface layer; forming a back plate layer on the third sacrificial layer, wherein release holes are formed in the back plate layer; removing part of the second sacrificial layer and part of the third sacrificial layer to form a cavity, and enabling part of the back plate layer to be suspended above the vibrating diaphragm; a back cavity is formed in the second surface of the substrate. According to the method, the interface layer is arranged, so that the etching damage to the material at the interface is reduced during etching, the interface property is improved, and further, the cracks at the interface are reduced.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to an MEMS (micro-electromechanical system) device, a preparation method thereof and an electronic device.
Background
With the continuous development of semiconductor technology, smart phones, integrated CMOS and micro-electromechanical systems (MEMS) devices are increasingly becoming the most mainstream and advanced technology in the market of sensor-like products, and with the updating of technology, the development is towards small size, high performance and low power consumption.
Among them, a Micro Electro Mechanical System (MEMS) microphone prepared and formed based on the MEMS process is widely used because of its advantages of small volume, low cost, stable performance, etc. compared with the conventional microphone. A typical MEMS microphone includes a diaphragm 101, a back plate 104, a back cavity 105, and the like, and converts a sound signal into an electrical signal through the diaphragm.
However, in some MEMS microphones, considering design and performance requirements, as shown in fig. 1, an etching stop layer cannot be formed on the sidewalls of the second sacrificial layer 102 and the third sacrificial layer 103, and after the sacrificial layer is removed by etching, the interface between the second sacrificial layer 102 and the third sacrificial layer 103 is easily damaged to form cracks, thereby reducing the product yield.
Disclosure of Invention
In this summary, concepts in a simplified form are introduced that are further described in the detailed description. The summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In view of the existing problems, the present invention provides a method for manufacturing a MEMS device, comprising:
providing a substrate, wherein a first sacrificial layer is formed on a first surface of the substrate, a vibrating diaphragm is formed on the first sacrificial layer, and a second sacrificial layer is formed on the vibrating diaphragm;
forming an interface layer on a surface of the second sacrificial layer, the interface layer covering a peripheral edge region of the second sacrificial layer;
forming a third sacrificial layer on the second sacrificial layer and the interface layer;
forming a back plate layer on a surface of the third sacrificial layer, the back plate layer having release holes formed therein to expose a portion of the surface of the third sacrificial layer;
removing a portion of the second sacrificial layer and a portion of the third sacrificial layer to form a cavity between the back plate layer and the diaphragm, such that a portion of the back plate layer is suspended above the diaphragm;
and forming a back cavity on the second surface of the substrate, wherein the second surface is opposite to the first surface, and the back cavity penetrates through the substrate and the first sacrificial layer from the second surface of the substrate and exposes a part of the surface of the diaphragm.
Illustratively, forming a back cavity on the second surface of the substrate includes:
thinning the substrate from the second surface of the substrate before removing a portion of the second sacrificial layer and a portion of the third sacrificial layer;
etching the substrate from the second surface of the substrate and stopping at the first sacrificial layer to form a cavity;
removing a portion of the first sacrificial layer while removing a portion of the second sacrificial layer and a portion of the third sacrificial layer to form the back cavity.
Illustratively, removing a portion of the first sacrificial layer, a portion of the second sacrificial layer, and a portion of the third sacrificial layer comprises:
and removing part of the first sacrificial layer, part of the second sacrificial layer and part of the third sacrificial layer by wet etching, wherein the first etching rate of the wet etching to the first sacrificial layer, the second sacrificial layer and the third sacrificial layer is higher than the second etching rate of the wet etching to the interface layer.
Illustratively, the first etch rate is two times or more than the second etch rate.
Illustratively, the method further comprises:
forming a through hole outside a region, where a cavity is scheduled to be formed, in the second sacrificial layer and the third sacrificial layer, wherein the through hole exposes a part of the surface of the diaphragm;
forming a rewiring layer which covers the bottom and the side wall of the through hole and partially extends to the surface of the third sacrificial layer;
and forming a first bonding pad on the rewiring layer, and forming a second bonding pad on the back plate layer, wherein the first bonding pad is electrically connected with the diaphragm through the rewiring layer, and the second bonding pad is electrically connected with the back plate layer.
Illustratively, the interface layer is ring-shaped.
Another aspect of the present invention provides a MEMS device, comprising:
a substrate comprising a first surface and a second surface opposite the first surface;
a first sacrificial layer covering a partial region of the first surface of the substrate;
a diaphragm positioned on the first sacrificial layer, wherein the peripheral edge area of the diaphragm is lapped on the first sacrificial layer;
the second sacrificial layer covers part of the diaphragm;
an interface layer covering a peripheral edge region of the second sacrificial layer;
a third sacrificial layer covering the second sacrificial layer and the interface layer;
a back plate layer, a part of which is suspended above the diaphragm, and the peripheral edge of the back plate layer covers the third sacrificial layer;
a cavity formed between the back plate layer and the diaphragm and penetrating through the second sacrificial layer and the third sacrificial layer;
and the back cavity penetrates through the substrate and the first sacrificial layer from the second surface of the substrate and exposes a part of the surface of the diaphragm.
Illustratively, the outer edge of the interface layer protrudes beyond the edges of the second and third sacrificial layers and/or the interface layer is annular.
Illustratively, the MEMS device further comprises:
a plurality of release holes which are arranged at intervals and penetrate through the back plate layer, and the release holes are exposed out of the diaphragm;
a rewiring layer, through holes are formed in the second sacrificial layer and the third sacrificial layer outside the cavity, the through holes expose partial surfaces of the diaphragms, and the rewiring layer covers the bottoms and the side walls of the through holes and partially extends to the surface of the third sacrificial layer;
the first bonding pad is arranged on the rewiring layer, the second bonding pad is arranged on the back plate layer, the first bonding pad is electrically connected with the diaphragm through the rewiring layer, and the second bonding pad is electrically connected with the back plate layer.
In still another aspect, the present invention provides an electronic device, which includes the MEMS device described above.
According to the MEMS device and the preparation method thereof, the interface layer is arranged, so that etching damage to materials at the interface is reduced during etching, the interface property is improved, cracks at the interface are reduced, and the product yield is improved.
Drawings
The following drawings of the present invention are included to provide a further understanding of the invention. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
In the drawings:
FIG. 1 is a schematic cross-sectional view of a device obtained by implementing a conventional MEMS device fabrication method;
FIG. 2 illustrates a flow chart of a method of fabricating a MEMS device in accordance with an embodiment of the present invention;
FIGS. 3A-3H are schematic cross-sectional views of devices obtained by sequential implementation of a method for fabricating a MEMS device in accordance with an embodiment of the present invention;
fig. 4 shows a schematic view of an electronic device according to an embodiment of the invention.
Detailed Description
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in 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," "adjacent to," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, 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.
Spatially relative terms, such as "under," "below," "beneath," "under," "above," "over," and the like, may be used herein for convenience in describing the relationship of one element or feature to another element or feature 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" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. 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, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, 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.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region shown as a rectangle will typically have rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted region. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The following detailed description of the preferred embodiments of the invention, however, the invention is capable of other embodiments in addition to those detailed.
Therefore, in view of the above technical problems, the present invention provides a method for manufacturing a MEMS device, as shown in fig. 2, which mainly includes the following steps:
step S1, providing a substrate, wherein a first sacrificial layer is formed on a first surface of the substrate, a vibrating diaphragm is formed on the first sacrificial layer, and a second sacrificial layer is formed on the vibrating diaphragm;
step S2, forming an interface layer on the surface of the second sacrificial layer, wherein the interface layer covers the peripheral edge area of the second sacrificial layer;
s3, forming a third sacrificial layer on the second sacrificial layer and the interface layer;
step S4, forming a back plate layer on the surface of the third sacrificial layer, wherein release holes exposing partial surface of the third sacrificial layer are formed in the back plate layer;
s5, removing part of the second sacrificial layer and part of the third sacrificial layer to form a cavity between the back plate layer and the diaphragm, so that part of the back plate layer is suspended above the diaphragm;
and S6, forming a back cavity on the second surface of the substrate, wherein the second surface is opposite to the first surface, and the back cavity penetrates through the substrate and the first sacrificial layer from the second surface of the substrate and exposes a part of the surface of the diaphragm.
According to the preparation method of the MEMS device, the interface layer is arranged, so that etching damage to materials at the interface is reduced during etching, the interface property is improved, cracks at the interface are reduced, and the product yield is improved.
Example one
Next, a method for manufacturing a MEMS device according to the present invention is described in detail with reference to fig. 2 to 3H, in which fig. 2 shows a flowchart of a method for manufacturing a MEMS device according to an embodiment of the present invention, and fig. 3A to 3H show schematic cross-sectional views of devices obtained by sequentially implementing the method for manufacturing a MEMS device according to an embodiment of the present invention.
Illustratively, the preparation method of the MEMS device comprises the following steps:
firstly, step S1 is executed, a substrate is provided, a first sacrificial layer is formed on a first surface of the substrate, a diaphragm is formed on the first sacrificial layer, and a second sacrificial layer is formed on the diaphragm.
The MEMS device may be any suitable device known to those skilled in the art, and the present embodiment mainly uses the case that the MEMS device is a MEMS microphone as an example to explain and explain the technical solution of the present invention.
Specifically, as shown in fig. 3A, the substrate 300 is a bulk silicon substrate, which may be at least one of the following mentioned materials: si, ge, siGe, siC, siGeC, inAs, gaAs, inP, inGaAs, or other III/V compound semiconductors, as well as multilayer structures of these semiconductors, or silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator-stacked germanium (S-SiGeOI), silicon-on-insulator-germanium (SiGeOI), and germanium-on-insulator (GeOI), and the like.
In one example, as shown in fig. 3A, a patterned first sacrificial layer 301 is formed on a first surface of a substrate 300, wherein the first sacrificial layer 301 is an oxide layer, such as silicon oxide and carbon-doped silicon oxide (SiOC), but not limited to the above example.
In addition, the first sacrificial layer 301 may be formed by various deposition methods commonly used in the art, for example, by a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method, an Atomic Layer Deposition (ALD) method, or the like.
The first sacrificial layer 301 is then patterned, optionally including the steps of:
forming a mask layer, such as a photoresist layer, on the first sacrificial layer 301;
the first sacrificial layer 301 is etched with the mask layer as a mask, and then the mask layer is removed.
Dry etching, reactive Ion Etching (RIE), ion beam etching, plasma etching may be selected in this step.
In one example, as shown in fig. 3B, a diaphragm 302 is formed on the first sacrificial layer 301 to cover the first sacrificial layer 301. The diaphragm 302 may be made of, but not limited to, polysilicon, siGe, etc.
The deposition method of the diaphragm 302 may be one of low-pressure chemical vapor deposition (LPCVD), laser Ablation Deposition (LAD), and Selective Epitaxial Growth (SEG) formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), or the like.
The diaphragm 302 is then patterned, optionally including the steps of:
forming a mask layer, such as a photoresist layer, on the diaphragm 302;
exposing and developing the photoresist layer to remove a part of the photoresist layer on the outer side and expose the vibrating diaphragm 302;
and then, etching the diaphragm by taking the mask layer as a mask, optionally, making the outer edge of the etched diaphragm substantially flush with the outer edge of the first sacrificial layer 301, and then removing the mask layer.
In one example, as shown in fig. 3C, a patterned second sacrificial layer 303 is formed on the diaphragm 302, wherein the second sacrificial layer 303 is an oxide layer, such as silicon oxide and carbon-doped silicon oxide (SiOC), but is not limited to the above example.
In addition, the second sacrificial layer 303 may be formed by various deposition methods commonly used in the art, for example, by a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method, an Atomic Layer Deposition (ALD) method, or the like.
The second sacrificial layer 303 is then patterned, optionally including the steps of:
forming a mask layer, such as a photoresist layer, on the second sacrificial layer 303;
the second sacrificial layer 303 is etched by using the mask layer as a mask to form a through hole and expose a part of the surface of the diaphragm 302, and then the mask layer is removed. The step of forming the through hole may be selectively performed, and in some embodiments, the mask layer may be further exposed to the edge region of the second sacrificial layer 303, and then the edge region of the second sacrificial layer 303 is etched by using the mask layer as a mask, where optionally, the etched second sacrificial layer 303 further surrounds the edges of the diaphragm and the first sacrificial layer.
Dry etching, reactive Ion Etching (RIE), ion beam etching, plasma etching may be selected for this step.
Subsequently, step S2 is performed to form an interface layer on the surface of the second sacrificial layer, the interface layer covering the peripheral edge region of the second sacrificial layer.
Specifically, as shown in fig. 3D, an interface material layer is deposited on the surface of the second sacrificial layer 303, and the interface material layer is patterned to form an interface layer 304. Optionally, the interface layer 304 covers the peripheral edge region of the second sacrificial layer 303, and the interface layer 304 has a ring-shaped structure, such as a ring shape, or other suitable shape.
In order to simplify the process steps more in the present invention, optionally, the step of patterning the interface material layer includes:
forming a mask layer, such as a photoresist layer, on the interface material layer;
the interface material layer is then etched using the mask layer as a mask to form an interface layer 304.
Dry etching, reactive Ion Etching (RIE), ion beam etching, plasma etching may be selected for this step.
In this embodiment, the material of the interfacial layer 304 may be silicon nitride, or other materials that can improve the interface, such as polysilicon.
The thickness of the interface layer 304 may be set according to practical requirements, for example, the thickness of the interface layer 304 is in the range of 5-100 angstroms, or other suitable ranges.
Alternatively, the interface layer 304 may use a material different from the first sacrificial layer, the second sacrificial layer, and the subsequent third sacrificial layer.
Subsequently, step S3 is performed to form a third sacrificial layer on the second sacrificial layer and the interface layer.
Specifically, as shown in fig. 3E, a patterned third sacrificial layer 305 is formed on the second sacrificial layer 303 and the interface layer 304, wherein the third sacrificial layer 305 is an oxide layer, such as silicon oxide and carbon-doped silicon oxide (SiOC), but not limited to the above example.
In addition, the third sacrificial layer 305 may be formed by various deposition methods commonly used in the art, for example, by a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method, an Atomic Layer Deposition (ALD) method, or the like.
The third sacrificial layer 305 is then patterned, optionally including the steps of:
forming a mask layer, such as a photoresist layer, on the third sacrificial layer 305;
the third sacrificial layer 305 is etched using the mask layer as a mask to form a through hole located outside a region where a cavity is to be formed and expose a portion of the surface of the diaphragm 302, and then the mask layer is removed. In some embodiments, the mask layer may be exposed at an edge region of the third sacrificial layer 305, and then the edge region of the third sacrificial layer 305 is etched using the mask layer as a mask, wherein optionally, the edge of the third sacrificial layer 305 after etching is substantially flush with the edge of the second sacrificial layer 303.
Dry etching, reactive Ion Etching (RIE), ion beam etching, plasma etching may be selected in this step.
Subsequently, step S4 is performed to form a back plate layer on the surface of the third sacrificial layer, the back plate layer having release holes formed therein to expose a part of the surface of the third sacrificial layer.
Specifically, in some embodiments, the method of forming the backsheet layer may include the steps of: as shown in fig. 3F, a backplate material layer is deposited to cover the surface of the third sacrificial layer 305, wherein the backplate material layer also covers the bottom and sidewalls of the through-holes when the through-holes exposing part of the surface of the diaphragm are formed in the second sacrificial layer and the third sacrificial layer.
In one example, as shown in fig. 3F, the backplane material layer is etched to form a backplane layer 307 and a redistribution layer 306 spaced apart from the backplane layer 307. The back plate layer 307 may be made of, but not limited to, polysilicon, siGe, and the like. In this embodiment of the application, the back plate layer 307 and the redistribution layer 306 may be formed simultaneously through the back plate material layer, and in other embodiments, the back plate layer and the redistribution layer 306 may also be formed sequentially through independent steps, so that the back plate layer 307 and the redistribution layer 306 may also be made of different materials.
The deposition method of the backplane material layer may be one of Low Pressure Chemical Vapor Deposition (LPCVD), laser Ablation Deposition (LAD) and Selective Epitaxial Growth (SEG) formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), or the like.
In one example, as shown in fig. 3F, a release hole is formed in the back plate layer 307 through the back plate layer 307, the release hole exposing a portion of the surface of the third sacrificial layer 305. The release holes may be formed by different processes of photolithography in combination with etching. Alternatively, the release hole may also serve as a sound hole.
In one example, as shown in fig. 3F, a re-routing layer 306 covers the bottom and sidewalls of the via and extends partially onto the surface of the third sacrificial layer 305.
Optionally, in other embodiments, the method of forming the redistribution layer 306 includes:
forming a through hole outside a region, where a cavity is to be formed, in the second sacrificial layer and the third sacrificial layer, where the through hole exposes a part of the surface of the diaphragm, where the through hole may be formed during the etching of the second sacrificial layer and the third sacrificial layer, or may be formed after a back plate layer is formed; a redistribution layer 306 is formed covering the bottom and sidewalls of the via and extending partially onto the surface of the third sacrificial layer, optionally a seed layer may also be deposited on the bottom and sidewalls of the via and a portion of the surface of the third sacrificial layer 305 prior to forming the redistribution layer 306.
Alternatively, the seed layer may be grown by electroplating or electroless plating. In some embodiments, the seed layer may be formed using physical vapor deposition or a suitable technique. The seed layer is a metal layer, which may include one or more metal layers. For example, the seed layer may include a first metal layer, which may be a titanium layer, and a second metal layer, which may be a copper layer, on the first metal layer. In some embodiments, other suitable metals may be used for the seed layer. In this embodiment, the redistribution layer 306 may be a plurality of layers, and the plurality of redistribution layers 306 may be repeatedly formed by using an electroplating process.
After forming the rewiring layer 306 and the back plane layer 307, the method further includes:
a first pad 308 is formed on the rewiring layer 306, and a second pad 309 is formed on the back plate layer 307, wherein the first pad 308 is electrically connected to the diaphragm 302 through the rewiring layer 306, and the second pad 309 is electrically connected to the back plate layer 307.
Subsequently, step S5 is performed to remove a portion of the second sacrificial layer and a portion of the third sacrificial layer, so as to form a cavity between the back plate layer and the diaphragm, so that a portion of the back plate layer is suspended above the diaphragm.
Specifically, as shown in fig. 3H, removing a portion of the second sacrificial layer 303 and a portion of the third sacrificial layer 305 through the release holes forms a cavity between the backplate layer 307 and the diaphragm 302, so that a portion of the backplate layer 307 is suspended above the diaphragm 302.
And finally, executing step S6, forming a back cavity on the second surface of the substrate, where the second surface is opposite to the first surface, and the back cavity penetrates through the substrate and the first sacrificial layer from the second surface of the substrate and exposes a part of the surface of the diaphragm.
Alternatively, as shown in fig. 3G and 3H, the step of forming the back cavity 311 includes:
thinning the substrate 300 from the second surface of the substrate 300, for example, thinning the substrate 300 by a chemical mechanical polishing process and/or an etching process, and the thickness of the thinned substrate 300 may be reasonably set according to actual needs, and is not specifically limited herein;
etching the substrate 300 from the second surface of the substrate 300 and stopping on the first sacrificial layer 301 to form a cavity, wherein in the step, dry etching or wet etching may be selected to remove a part of the substrate 300;
the portion of the first sacrificial layer 301 is removed at the same time as the portion of the second sacrificial layer 303 and the portion of the third sacrificial layer 305 are removed to form the back cavity 311, which may not be removed simultaneously, but may be removed sequentially in some embodiments.
In this embodiment, the steps of forming the back cavity 311 and forming the cavity may be performed simultaneously, or may be performed sequentially, or may be performed by using different etching methods. In some embodiments, the cavity and the back cavity 311 at least partially correspond.
In this embodiment, a wet etch is used to remove a portion of the first sacrificial layer 301, a portion of the second sacrificial layer 303, and a portion of the third sacrificial layer 305, wherein the wet etch has a first etch rate for the first sacrificial layer 301, the second sacrificial layer 303, and the third sacrificial layer 305 that is higher than a second etch rate for the interface layer 304. In this embodiment, the first etching rate is twice or more than the second etching rate. So that the interface layer 304 is still disposed at the boundary of the second sacrificial layer and the third sacrificial layer 305 when the etching of the first sacrificial layer 301, the second sacrificial layer 303 and the third sacrificial layer 305 is satisfactory. Alternatively, the wet etching method can use a hydrofluoric acid solution, such as a Buffered Oxide Etchant (BOE) or a hydrofluoric acid buffered solution (BHF) or hydrofluoric acid vapor.
It should be noted that the above steps are only examples, and the order of the above steps can be adjusted without conflict.
The description of the key steps of the method for manufacturing the MEMS device of the present invention is completed, and the complete manufacturing of the MEMS device may further include other steps, which are not described in detail herein.
In conclusion, the preparation method of the MEMS device provided by the invention has the advantages that the interface layer is arranged, so that the etching damage to the material at the interface is reduced during etching, the interface property is improved, the cracks at the interface are reduced, and the product yield is improved.
Example two
The present invention also provides a MEMS device prepared by the method of the first embodiment, as shown in fig. 3H, the MEMS device of the present invention includes:
a substrate 300, the substrate 300 comprising a first surface and a second surface opposite the first surface;
a first sacrificial layer 301 covering a partial region of a first surface of the substrate 300;
a diaphragm 302 which is located on the first sacrificial layer 301, and an outer peripheral edge region of the diaphragm 302 overlaps the first sacrificial layer 301;
a second sacrificial layer 303 covering a part of the diaphragm 302;
an interface layer 304 covering the peripheral edge region of the second sacrificial layer 303;
a third sacrificial layer 305 covering the second sacrificial layer 303 and the interface layer 304;
a back plate layer 307, a portion of the back plate layer 307 being suspended over the diaphragm 302, the peripheral edge of the back plate layer 307 covering the third sacrificial layer 305;
a cavity 310 formed between the back plate layer 307 and the diaphragm 302, and penetrating the second sacrificial layer 303 and the third sacrificial layer 305;
a back cavity 311, which penetrates the substrate 300 and the first sacrificial layer 301 from the second surface of the substrate 300 and exposes a part of the surface of the diaphragm 302.
Specifically, as shown in fig. 3H, the substrate 300 is a bulk silicon substrate, which may be at least one of the materials mentioned below: si, ge, siGe, siC, siGeC, inAs, gaAs, inP, inGaAs, or other III/V compound semiconductors, as well as multilayer structures of these semiconductors, or silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator-stacked germanium (S-SiGeOI), silicon-on-insulator-germanium (SiGeOI), and germanium-on-insulator (GeOI), and the like.
In this embodiment, the first sacrificial layer 301, the second sacrificial layer 303 and the third sacrificial layer 305 may be oxide layers, such as silicon oxide and carbon-doped silicon oxide (SiOC), but are not limited to the above example.
In this embodiment, the diaphragm 302 may be made of polysilicon, siGe, etc., but is not limited to one.
The deposition method of the diaphragm 302 may be one of Low Pressure Chemical Vapor Deposition (LPCVD), laser Ablation Deposition (LAD), and Selective Epitaxial Growth (SEG) formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), or the like.
As shown in fig. 3H, the outer edges of the interface layer 304 protrude beyond the edges of the second sacrificial layer 303 and the third sacrificial layer 305.
In this embodiment, the material of the interfacial layer 304 may be silicon nitride, or other materials that can improve the interface, such as polysilicon.
In this embodiment, the thickness of the interface layer 304 may be set according to practical requirements, for example, the thickness of the interface layer 304 is in the range of 5-100 angstroms, or other suitable ranges.
In this embodiment, the back plate layer 307 may be made of polysilicon, siGe, etc., but is not limited to one.
Among them, the deposition method of the back plate layer 307 may be one of Low Pressure Chemical Vapor Deposition (LPCVD), laser Ablation Deposition (LAD), and Selective Epitaxial Growth (SEG) formed by a Chemical Vapor Deposition (CVD) method, a Physical Vapor Deposition (PVD) method, an Atomic Layer Deposition (ALD) method, or the like.
Further, as shown in fig. 3H, the MEMS device of the present invention further includes:
a plurality of release holes that are provided at intervals from each other and penetrate the back plate layer 307, the release holes exposing the diaphragm 302, and the release holes may serve as sound holes of a microphone;
a redistribution layer 306, through holes are formed in the second sacrificial layer 303 and the third sacrificial layer 305 outside the cavity 310, the through holes expose part of the surface of the diaphragm 302, and the redistribution layer 306 covers the bottom and the side walls of the through holes and partially extends to the surface of the third sacrificial layer 305;
a first pad 308 and a second pad 309, where the first pad 308 is disposed on the redistribution layer 306, the second pad 309 is disposed on the back plate layer 307, the first pad 308 is electrically connected to the diaphragm 302 through the redistribution layer 306, and the second pad 309 is electrically connected to the back plate layer 307.
The MEMS device may be a MEMS microphone device, and during the operation of the MEMS microphone, gas enters the cavity through the release hole on the back plate layer 307, so that the sound pressure of the gas acts on the diaphragm 302 to cause the diaphragm 302 to vibrate, and further is discharged through the release hole on the back plate layer 307, wherein the diaphragm 302 and the back plate layer 307 may form a parallel plate capacitor, and when the external sound pressure acts on the diaphragm 100, the vibration of the diaphragm 302 may be caused, so that the distance between the diaphragm 302 and the back plate layer 307 may change, and further the change of the capacitor may be generated, and the capacitance change may be used to perform operation and work, so as to complete the conversion between the sound signal and the electrical signal.
The structure of the MEMS device of the present invention is described so far, and the complete device may include other constituent structures, which are not described in detail herein.
The MEMS device forms the interface layer, so that the etching damage to the material at the interface is reduced during etching, the interface property is improved, the cracks at the interface are reduced, and the product yield is improved.
EXAMPLE III
The invention also provides an electronic device comprising the MEMS device described in the second embodiment or the MEMS device prepared by the method described in the first embodiment.
The electronic device may be any electronic product or device such as a mobile phone, a tablet computer, a notebook computer, a netbook, a game machine, a television, a VCD, a DVD, a navigator, a camera, a video camera, a recording pen, an MP3, an MP4, a PSP, or an intermediate product having the MEMS device, for example: a mobile phone mainboard with the integrated circuit, and the like.
The electronic device also has the advantages described above, since the MEMS device comprised has a higher performance.
Wherein figure 4 shows an example of a mobile telephone handset. The mobile phone handset 400 is provided with a display portion 402, operation buttons 403, an external connection port 404, a speaker 405, a microphone 406, and the like, which are included in a housing 401.
The electronic device adopts the MEMS device, so that all the advantages of the MEMS device are achieved.
Although various embodiments are described herein, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the concepts of the present disclosure. More particularly, various modifications and changes may be made in the arrangement and/or composition of the subject matter within the scope of the disclosure, the drawings, and the appended claims. In addition to modifications and variations in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.
Claims (10)
1. A method of fabricating a MEMS device, the method comprising:
providing a substrate, wherein a first sacrificial layer is formed on a first surface of the substrate, a vibrating diaphragm is formed on the first sacrificial layer, and a second sacrificial layer is formed on the vibrating diaphragm;
forming an interface layer on a surface of the second sacrificial layer, the interface layer covering a peripheral edge region of the second sacrificial layer;
forming a third sacrificial layer on the second sacrificial layer and the interface layer;
forming a back plate layer on a surface of the third sacrificial layer, the back plate layer having a release hole formed therein to expose a portion of the surface of the third sacrificial layer;
removing a portion of the second sacrificial layer and a portion of the third sacrificial layer to form a cavity between the back plate layer and the diaphragm, such that a portion of the back plate layer is suspended above the diaphragm;
and forming a back cavity on the second surface of the substrate, wherein the second surface is opposite to the first surface, and the back cavity penetrates through the substrate and the first sacrificial layer from the second surface of the substrate and exposes a part of the surface of the diaphragm.
2. The method of claim 1, wherein forming a back cavity in the second surface of the substrate comprises:
thinning the substrate from the second surface of the substrate before removing a portion of the second sacrificial layer and a portion of the third sacrificial layer;
etching the substrate from the second surface of the substrate and stopping at the first sacrificial layer to form a cavity;
removing a portion of the first sacrificial layer while removing a portion of the second sacrificial layer and a portion of the third sacrificial layer to form the back cavity.
3. The method of claim 2, wherein removing portions of the first sacrificial layer, portions of the second sacrificial layer, and portions of the third sacrificial layer comprises:
and removing part of the first sacrificial layer, part of the second sacrificial layer and part of the third sacrificial layer by wet etching, wherein the first etching rate of the first sacrificial layer, the second sacrificial layer and the third sacrificial layer by the wet etching is higher than the second etching rate of the interface layer.
4. The method of claim 3, wherein the first etch rate is two or more times the second etch rate.
5. The method of claim 1, further comprising:
forming a through hole outside an area, in which a cavity is scheduled to be formed, of the second sacrificial layer and the third sacrificial layer, wherein the through hole exposes a part of the surface of the diaphragm;
forming a rewiring layer which covers the bottom and the side wall of the through hole and partially extends to the surface of the third sacrificial layer;
and forming a first bonding pad on the rewiring layer, and forming a second bonding pad on the back plate layer, wherein the first bonding pad is electrically connected with the diaphragm through the rewiring layer, and the second bonding pad is electrically connected with the back plate layer.
6. The method of claim 1, wherein the interfacial layer is ring-shaped.
7. A MEMS device, comprising:
a substrate comprising a first surface and a second surface opposite the first surface;
a first sacrificial layer covering a partial region of the first surface of the substrate;
a diaphragm positioned on the first sacrificial layer, wherein the peripheral edge region of the diaphragm is lapped on the first sacrificial layer;
the second sacrificial layer covers part of the diaphragm;
an interface layer covering a peripheral edge region of the second sacrificial layer;
a third sacrificial layer covering the second sacrificial layer and the interface layer;
a back plate layer, a part of which is suspended above the diaphragm, and the peripheral edge of the back plate layer covers the third sacrificial layer;
a cavity formed between the back plate layer and the diaphragm and penetrating through the second sacrificial layer and the third sacrificial layer;
and the back cavity penetrates through the substrate and the first sacrificial layer from the second surface of the substrate and exposes a part of the surface of the diaphragm.
8. The MEMS device, as recited in claim 7, wherein an outer edge of the interface layer protrudes beyond edges of the second sacrificial layer and edges of the third sacrificial layer; and/or the interface layer is annular.
9. The MEMS device, as recited in claim 7, further comprising:
a plurality of release holes which are arranged at intervals and penetrate through the back plate layer, and the diaphragm is exposed from the release holes;
a rewiring layer, through holes are formed in the second sacrificial layer and the third sacrificial layer outside the cavity, part of the surface of the diaphragm is exposed out of the through holes, and the rewiring layer covers the bottom and the side wall of the through holes and partially extends to the surface of the third sacrificial layer;
the first bonding pad is arranged on the rewiring layer, the second bonding pad is arranged on the back plate layer, the first bonding pad is electrically connected with the diaphragm through the rewiring layer, and the second bonding pad is electrically connected with the back plate layer.
10. An electronic device, characterized in that it comprises a MEMS device according to one of claims 7 to 9.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116199182A (en) * | 2023-04-28 | 2023-06-02 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN116199183A (en) * | 2023-04-28 | 2023-06-02 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN116281846A (en) * | 2023-05-12 | 2023-06-23 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN118083906A (en) * | 2024-04-23 | 2024-05-28 | 芯联越州集成电路制造（绍兴）有限公司 | MEMS device, preparation method thereof and electronic device |
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- 2022-12-28 CN CN202211694847.5A patent/CN115924838A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116199182A (en) * | 2023-04-28 | 2023-06-02 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN116199183A (en) * | 2023-04-28 | 2023-06-02 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN116199182B (en) * | 2023-04-28 | 2024-01-19 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN116281846A (en) * | 2023-05-12 | 2023-06-23 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN116281846B (en) * | 2023-05-12 | 2023-08-01 | 润芯感知科技(南昌)有限公司 | Semiconductor device and manufacturing method thereof |
| CN118083906A (en) * | 2024-04-23 | 2024-05-28 | 芯联越州集成电路制造（绍兴）有限公司 | MEMS device, preparation method thereof and electronic device |
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