CN111170268B - MEMS device and method of manufacturing the same - Google Patents
MEMS device and method of manufacturing the same Download PDFInfo
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- CN111170268B CN111170268B CN201811344842.3A CN201811344842A CN111170268B CN 111170268 B CN111170268 B CN 111170268B CN 201811344842 A CN201811344842 A CN 201811344842A CN 111170268 B CN111170268 B CN 111170268B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
- B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
- B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
- B81C1/00182—Arrangements of deformable or non-deformable structures, e.g. membrane and cavity for use in a transducer
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
- B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
- B81B2201/00—Specific applications of microelectromechanical systems
- B81B2201/02—Sensors
- B81B2201/0257—Microphones or microspeakers
Abstract
The present invention provides a MEMS device and a method of manufacturing the same, the MEMS device comprising: the first electrode plate comprises a supporting area and a vibrating area, and the vibrating area is arranged in the first electrode plate; the sacrificial layer is positioned on the first electrode plate of the supporting area, and the material density of the first electrode plate is greater than that of the sacrificial layer; the second electrode plate comprises a connecting part penetrating through the sacrificial layer, a supporting part positioned on the sacrificial layer above the supporting area and a vibrating part positioned above the vibrating area, wherein the supporting part is connected with the connecting part and the first electrode plate, the connecting part is electrically insulated from the first electrode plate, and the first electrode plate, the vibrating part, the supporting part and the connecting part form a cavity. The special structure that the bottom of the second electrode plate is connected with the first electrode plate is arranged, so that the problem of internal stress change of the second electrode plate is avoided, and the reliability of the MEMS device is improved.
Description
Technical Field
The invention relates to the technical field of semiconductor manufacturing, in particular to an MEMS device and a manufacturing method thereof.
Background
Microelectromechanical systems (MEMS, micro-Electro-Mechanical System) are Micro devices based on microelectronics, micromachining, and materials science, and are designed, fabricated, and have specific functions. Microelectromechanical systems are a leading-edge high technology with strategic significance for cross-integration of various disciplines, and are one of the dominant industries in the future.
The advent and application of MEMS technology has led to microphones becoming smaller and smaller. MEMS microphones have many advantages, such as high signal-to-noise ratio, low power consumption, high sensitivity, compatibility of the used micro-package with the mounting process, small influence of reflow soldering on the performance of the MEMS microphone, excellent temperature characteristics, etc. In general, the manufacturing process of the MEMS microphone includes: a plurality of functional layers are deposited on the wafer, and then unnecessary materials are removed by etching to form a cavity on the wafer, and the cavity is covered with the vibrating diaphragm and the backboard. The backplate has good rigidity, adopts the through-hole structure, and ventilation performance is excellent, and the vibrating diaphragm is solid structure, and when the sound wave arouses atmospheric pressure and changes, the vibrating diaphragm will be crooked along with atmospheric pressure change, and when the vibrating diaphragm motion, the electric capacity between vibrating diaphragm and the backplate will change, and MEMS microphone converts the change of electric capacity into the signal of telecommunication.
In the prior art, the reliability of MEMS devices is to be further improved.
Disclosure of Invention
The invention solves the problem of providing an MEMS device and a manufacturing method thereof, and improves the reliability of the MEMS device.
In order to solve the above problems, the present invention provides a MEMS device comprising: the first electrode plate comprises a supporting area and a vibrating area, and an opening penetrating through the thickness of the first electrode plate is formed in the first electrode plate in the vibrating area; a sacrificial layer on the first electrode plate of the support region; the second electrode plate comprises a connecting part penetrating through the sacrificial layer, a supporting part positioned on the sacrificial layer above the supporting area and a vibrating part positioned above the vibrating area, wherein the supporting part is connected with the connecting part and the first electrode plate, the connecting part is electrically insulated from the first electrode plate, and the first electrode plate, the vibrating part, the supporting part and the connecting part form a cavity; the first electrode layer is positioned on the first electrode plate of the supporting area and is electrically connected with the first electrode plate; and the second electrode layer is positioned on the supporting part and is electrically connected with the second electrode plate.
The invention also provides a manufacturing method of the MEMS device, which comprises the following steps: forming a first electrode plate, wherein the first electrode plate comprises a supporting area and a vibrating area, an opening penetrating through the thickness of the first electrode plate is formed in the first electrode plate of the vibrating area, and a sacrificial film is filled in the opening; forming a sacrificial layer on the first electrode plate and the sacrificial film; forming at least one connection groove exposing the first electrode plate in the sacrificial layer above the supporting region; forming a second electrode plate on the surface of the sacrificial layer and in the connecting groove, wherein the second electrode plate comprises a connecting part filled in the connecting groove, a supporting part positioned on the sacrificial layer above the supporting area and a vibrating part positioned above the vibrating area, and the supporting part is connected with the connecting part; etching to remove the sacrificial film and the sacrificial layer of the vibration area, wherein the first electrode plate, the supporting part, the vibration part and the connecting part form a cavity; forming a first electrode layer on a first electrode plate of the supporting region, wherein the first electrode layer is electrically connected with the first electrode plate; a second electrode layer is formed on the support portion, and the second electrode layer is electrically connected to the second electrode plate.
Compared with the prior art, the technical scheme provided by the invention has the following advantages:
the invention provides an MEMS device with excellent structural performance, wherein a second electrode plate comprises a connecting part penetrating through a sacrificial layer of a supporting area, a supporting part positioned on the sacrificial layer above the supporting area and a vibrating part positioned above a vibrating area, wherein the supporting part is connected with the connecting part and a first electrode plate, and a cavity is formed by the first electrode plate, the vibrating part, the supporting part and the connecting part. Because connecting portion links to each other with first electrode plate, and first electrode plate has the characteristics that material compactness is good, consequently with time pass or external environment change, first electrode plate internal stress change can be ignored even zero, and is corresponding, with first electrode plate is the stress influence that connecting portion received of growth substrate is little to make connecting portion internal stress change neglect even zero, and then guarantee that second electrode plate internal stress is stable, improve MEMS device's reliability. And moreover, the connecting part is electrically insulated from the first electrode plate, so that the problem of short circuit between the first electrode plate and the second electrode plate is prevented, and the MEMS device can work normally.
Drawings
FIG. 1 is a schematic cross-sectional view of a MEMS device;
figure 2 is a schematic cross-sectional view of a MEMS device according to an embodiment of the present invention,
fig. 3 to 14 are schematic cross-sectional views illustrating steps of a method for manufacturing a MEMS device according to an embodiment of the invention.
Detailed Description
From the background, the performance of the MEMS device of the prior art needs to be improved.
Referring to fig. 1, fig. 1 is a schematic cross-sectional structure of a MEMS device, taking the MEMS device as a MEMS microphone as an example, the MEMS device includes:
a substrate 100, the substrate 100 having a first opening through a thickness thereof; a first sacrificial layer 101 on a part of the upper surface of the substrate 100; a patterned back plate on the upper surface of the first sacrificial layer, wherein the back plate comprises a first insulating layer 102, a conductive layer 103 and a second insulating layer 104, the patterned back plate comprises a supporting area and a vibrating area, the patterned back plate is provided with a second opening penetrating through the thickness of the patterned back plate, and the upper surface of the back plate of the vibrating area is provided with a blocking part 110; the second sacrificial layer 105 is positioned on the upper surface of the back electrode plate supporting area, and the second sacrificial layer 105, the back electrode plate and the first sacrificial layer 101 form a cavity; a patterned vibrating electrode over the cavity and on the upper surface of the second sacrificial layer 105, the vibrating electrode including a support portion (not shown) and a vibrating portion 106; a protective layer 107 covering the top and sidewalls of the second sacrificial layer 105, the back plate sidewalls, and the first sacrificial layer 101 sidewalls; a first conductive layer 108 on the top surface of the back plate in the support region; and a second conductive layer 109 on the upper surface of the support.
The reliability of the MEMS device is to be improved. The bottom of the vibration electrode is directly contacted with the second sacrificial layer 105, which is equivalent to using the second sacrificial layer 105 as a supporting substrate, however, the material of the second sacrificial layer 105 is usually silicon oxide, which is easy to absorb moisture in the external environment, so that the stress in the silicon oxide is changed, thereby influencing the stress in the second sacrificial layer 105 and further influencing the stress in the vibration electrode. Further analysis has found that in the process of manufacturing the MEMS device described above, the vibrating electrode is formed on the second sacrificial film, wherein the second sacrificial film provides a process basis for forming the second sacrificial layer 105, and the material of the second sacrificial film is typically silicon oxide, and thus corresponds to a process of forming the vibrating electrode using silicon oxide as a substrate. However, moisture in the external environment is easily adsorbed in the silicon oxide, so that the internal stress of the silicon oxide is changed, and even if the internal stress is slightly changed, the internal stress of the vibrating electrode on the silicon oxide is affected, thereby causing the problem of poor reliability of the MEMS device.
In order to solve the problem of the internal stress variation of silicon oxide, the following two means can be adopted: firstly, increasing the annealing temperature of silicon oxide, however, increasing the annealing temperature can cause serious wafer warpage, and subsequent process is difficult to carry out; secondly, the annealing time of the silicon oxide is prolonged, however, the silicon oxide has good compactness in a period of time after the silicon oxide is formed, but the internal stress in the silicon oxide still has larger change along with the time, so that the reliability problem of the MEMS device is difficult to fundamentally solve.
In order to solve the above problems, the present invention provides a MEMS device, where the second electrode plate includes a connection portion, a supporting portion and a vibration portion, and the supporting portion is connected to the first electrode plate through the connection portion, which is equivalent to that the bottom of the second electrode plate is directly contacted with the first electrode plate, and the second electrode plate uses the first electrode plate with more stable material as a substrate, and since the internal stress of the first electrode plate will not change with time, the second electrode plate formed by growing on the first electrode plate will also have a substrate with stable internal stress, thereby avoiding the problem that the internal stress of the second electrode plate is affected, and effectively improving the reliability of the MEMS device.
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
Fig. 2 is a schematic cross-sectional structure of a MEMS device according to an embodiment of the present invention.
Referring to fig. 2, the MEMS device includes:
the first electrode plate comprises a supporting area (not marked) and a vibrating area (not marked), and an opening (not marked) penetrating through the thickness of the first electrode plate is formed in the first electrode plate of the vibrating area;
a sacrificial layer 207 on the first electrode plate of the support region, and the material density of the first electrode plate is greater than the material density of the sacrificial layer 207;
a second electrode plate including a connection portion 210 penetrating the sacrificial layer 207, a supporting portion 211 located on the sacrificial layer 207 above the supporting region, and a vibrating portion 209 located above the vibrating region, wherein the supporting portion 211 is connected with the connection portion 210 and the first electrode plate, the connection portion 210 is electrically insulated from the first electrode plate, and the first electrode plate, the vibrating portion 209, the supporting portion 211, and the connection portion 210 enclose a cavity;
a first electrode layer 214 on the first electrode plate of the support region, and the first electrode layer 214 is electrically connected with the first electrode plate;
and a second electrode layer 215 on the supporting part 211, and the second electrode layer 215 is electrically connected with the second electrode plate.
The MEMS device provided by the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
In this embodiment, the MEMS microphone device is taken as an example for explanation. In other embodiments, the MEMS device may also be a MEMS acceleration sensor, a MEMS humidity sensor, or the like.
In this embodiment, the MEMS device further includes: the substrate 200, the substrate 200 has a back cavity penetrating through the thickness of the substrate 200, the first electrode plate is disposed on the substrate 200, the substrate 200 and the second electrode plate are respectively located at two opposite sides of the first electrode plate, and the back cavity is connected with the cavity.
The substrate 200 includes a semiconductor substrate, or the substrate 200 includes a semiconductor substrate and a semiconductor element located in the semiconductor substrate, where the semiconductor element is a semiconductor transistor or an interconnection structure, etc. The semiconductor substrate may be a silicon substrate, a germanium substrate, a silicon germanium substrate, or a silicon on insulator substrate, or the like.
The first electrode plate is disposed on the substrate 200, and the MEMS device further includes, in order to increase adhesion between the first electrode plate and the substrate 200: an adhesion layer 201 between the substrate 200 and the first electrode plate.
In this embodiment, the adhesion layer 201 exposes the edge surface of the substrate 200 near the vibration region. In other embodiments, the adhesion layer may also cover a portion of the surface of the substrate proximate to the vibration region. In this embodiment, the adhesion layer 201 also exposes an edge surface of the substrate 200 away from the support region.
The material of the adhesion layer 201 is silicon oxide or silicon oxynitride. In this embodiment, the material of the adhesion layer 201 is the same as that of the sacrificial layer 207, which is beneficial to reducing the difficulty of the manufacturing process of the MEMS device.
An opening penetrating through the thickness of the first electrode plate is formed in the first electrode plate of the vibration area, and the opening is connected with the cavity to form an acoustic channel of the MEMS device. The first electrode plate can be of a strip-shaped structure and also can be of a comb-tooth-shaped structure.
The first electrode plate is used as one of electrode plates of a capacitor structure in the MEMS device, so that at least one part of the structures in the first electrode plate are required to have a conductive function; meanwhile, the part of the structure with the conductive function needs to be electrically insulated from the connection part 210, so as to avoid the problem that the first electrode plate and the second electrode plate are unnecessarily electrically connected.
For this reason, in this embodiment, the first electrode plate includes a conductive electrode plate 203 and a top insulating electrode plate 204 located on the conductive electrode plate 203, where the conductive electrode plate 203 has a conductive function and can be used as one of electrode plates of a capacitor structure in the MEMS device, and the top insulating electrode plate 204 can ensure mutual insulation between the connection portion 210 and the conductive electrode plate 203, so as to prevent the second electrode plate from being electrically connected with the first electrode plate.
In order to further improve the interface performance between the adhesion layer 201 and the first electrode plate, in this embodiment, the first electrode plate further includes: a bottom insulated plate 202 under the conductive structure 203. That is, in this embodiment, the first electrode plate has a laminated structure of insulating layer-conductive layer-insulating layer, and the laminated structure can also improve the strength of the first electrode plate, so as to avoid the problem of breakage of the first electrode plate.
Correspondingly, in this embodiment, the sacrificial layer 207 is located on the surface of the top insulating plate 204 of the supporting area.
In addition, the material density of the top insulating plate 204 is greater than that of the sacrificial layer 207, which has the advantages that: because the material density of the top insulating polar plate 204 is greater, the change of the internal stress of the top insulating polar plate 204 is smaller than the change of the internal stress of the sacrificial layer 207 under the same external environment, and because the change of the internal stress of the top insulating polar plate 204 is small, the adverse effect on the connecting portion 210 positioned on the surface of the top insulating polar plate 204 is small, the internal stress of the connecting portion 210 is ensured to be stable, and correspondingly, the internal stress of the supporting portion 211 and the vibrating portion 209 is also stable, so that the MEMS reliability deterioration caused by the change of the internal stress of the connecting portion 210 is avoided.
In this embodiment, the material of the conductive plate 203 is polysilicon. In other embodiments, the material of the conductive electrode plate may also be metal.
In this embodiment, the material of the top insulating plate 204 is silicon nitride, and the material of the bottom insulating plate 202 is silicon nitride. In other embodiments, the material of the top insulating plate may be silicon oxynitride or silicon oxycarbonitride, and the material of the bottom insulating plate may be silicon nitride or silicon oxycarbonitride.
In this embodiment, the material of the sacrificial layer 207 is silicon oxide. In other embodiments, the material of the sacrificial layer may also be TEOS.
The second electrode plate includes a connection portion 210 filled in the connection groove, a supporting portion 211 positioned on the surface of the sacrificial layer 207 above the supporting region, and a vibration portion 209 positioned above the vibration region.
In this embodiment, the connection portion 210 is located on the surface of the top insulating plate 204 and contacts the top insulating plate 204.
In this embodiment, the connecting portion 210 has a columnar structure, and the width of the connecting portion 210 is not too small or too large in the direction parallel to the surface of the first electrode plate. If the width of the connection portion 210 is too small, the compactness of the connection portion 210 is poor, and if the width of the connection portion 210 is too large, the space occupied by the connection portion 210 by the MEMS device is large, which is not beneficial to miniaturization of the device. For this reason, in the present embodiment, the width of the connection portion 210 is in the range of 5 μm to 100 μm, for example, 10 μm, 20 μm, 50 μm, 70 μm, 85 μm in the direction parallel to the surface of the first electrode plate.
It should be noted that, in other embodiments, the connection portion may also be a closed hollow annular structure or a semi-closed hollow annular structure.
The number of the connection portions 210 may be one or more, for example, two, three, five, or the like, above the same supporting region, or above a supporting region located at one side of the vibration region. In this embodiment, the number of the connection portions 210 is plural above the same supporting area, wherein the first electrode plate, the second electrode plate and the connection portion 210 closest to the vibration area enclose the cavity.
Since the connection portion 210 is located on the surface of the top insulating electrode plate 204, it can be considered that the connection portion 210 uses the first electrode plate as a growth substrate or a supporting substrate, and the material density of the first electrode plate is greater than that of the sacrificial layer 207, and the first electrode plate has the characteristic of high material stability, so that the internal stress of the connection portion 210 is less affected by the first electrode plate, and the internal stress of the connection portion 210 is ensured to be stable, so that the internal stress of the supporting portion 211 and the internal stress of the vibration portion 209 are correspondingly kept stable, and the MEMS device is ensured to have high reliability.
The support portion 211 provides a supporting function for the vibration portion 209. In this embodiment, the supporting portion 211 and the connecting portion 210 are integrally formed, and the supporting portion 211 and the connecting portion 210 are formed in the same process step.
In this embodiment, the material of the second electrode plate is polysilicon, that is, the material of the connection portion 210 is polysilicon, the material of the supporting portion 211 is polysilicon, and the material of the vibration portion 209 is polysilicon. In other embodiments, the material of the second electrode plate may also be doped polysilicon.
The first electrode layer 214 is configured to electrically connect the first electrode plate, and the first electrode plate is electrically connected to an external circuit through the first electrode layer 214. In this embodiment, the MEMS device further includes: a conductive via extending through the sacrificial layer 207, and the first electrode layer 214 is located at the bottom of the conductive via. Specifically, the conductive hole further penetrates through the top insulating plate 204 of the first electrode plate to expose the conductive plate 203, so that the first electrode layer 214 is electrically connected to the conductive plate 203. In other embodiments, the first electrode layer may be located on the sidewall of the conductive via in addition to the bottom of the conductive via.
The second electrode layer 215 is configured to electrically connect to the second electrode plate, and electrically connect the second electrode plate to an external circuit through the second electrode layer 215. In this embodiment, the second electrode layer 215 is located on the upper surface of the supporting portion 211, so as to avoid the second electrode layer 215 from affecting the vibration effect of the vibration portion 210.
In this embodiment, the first electrode layer 214 and the second electrode layer 215 are respectively located on two opposite sides of the vibration portion 209. In other embodiments, the first electrode layer and the second electrode layer may be located on the same side of the vibration part.
In order to prevent the vibration portion 209 from touching the first electrode plate during vibration, in this embodiment, the MEMS further includes: and a limit post 206 positioned on the first electrode plate of the vibration region. Specifically, the limiting post 206 is located on the surface of the top insulating plate 204, and the limiting post 206 can block the vibration portion 209 from touching the first electrode plate. In this embodiment, the material of the limiting post 206 is polysilicon.
The MEMS device further comprises: and a protective layer 213, wherein the protective layer 213 covers the side wall of the sacrificial layer 207 away from the vibration region, and also covers the side wall of the first electrode plate away from the vibration region. In this embodiment, since the adhesion layer 201 is further disposed between the substrate 200 and the first electrode plate, for this purpose, the protection layer 213 also covers a sidewall of the adhesion layer 201 away from the vibration region.
The material of the protective layer 213 is different from the material of the sacrificial layer 207. In this embodiment, the material of the protection layer 213 is silicon nitride. In other embodiments, the material of the protective layer may also be silicon oxynitride or silicon oxycarbonitride.
In the MEMS device provided in this embodiment, the second electrode plate includes a connection portion 210 penetrating through the sacrificial layer 207 of the supporting area, and further includes a supporting portion 211 located on the sacrificial layer 207 above the supporting area and a vibrating portion 209 located above the vibrating area, where the supporting portion 211 is connected to the connection portion 210 and the first electrode plate, the vibrating portion 209, the supporting portion 211 and the connection portion 210 enclose a cavity. Because the connecting portion 210 is connected with the first electrode plate, and the first electrode plate has the characteristic of good material compactness, therefore, over time or external environment changes, the internal stress change of the first electrode plate can be ignored or even zero, and correspondingly, the stress influence on the connecting portion 210 taking the first electrode plate as a growth substrate is small, so that the internal stress change of the connecting portion 210 is ignored or even zero, the internal stress stability of the second electrode plate is further ensured, and the reliability of the MEMS device is improved.
And, the connection portion 210 is electrically insulated from the first electrode plate, so as to prevent a short circuit problem between the first electrode plate and the second electrode plate, and ensure that the MEMS device can work normally.
Correspondingly, the embodiment of the invention also provides a manufacturing method for manufacturing the MEMS device. Fig. 2 to 14 are schematic cross-sectional structures corresponding to steps of a method for manufacturing a MEMS device according to an embodiment of the present invention.
Hereinafter, a method for manufacturing a MEMS device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 3 to 6, a first electrode plate is formed, the first electrode plate includes a support region and a vibration region, and an opening penetrating through the thickness of the first electrode plate is formed in the first electrode plate of the vibration region, and the opening is filled with a sacrificial film 205.
In this embodiment, before forming the first electrode plate, the method further includes: a substrate 200 is provided, and the first electrode plate is formed on the substrate 200.
The process steps for forming the first electrode plate comprise:
referring to fig. 3, a first electrode film layer is formed on the substrate 200.
In this embodiment, in order to improve the adhesion between the substrate 200 and the first electrode plate, an adhesion layer 201 is further formed on the surface of the substrate 200 before the first electrode plate is formed. Accordingly, the first electrode film layer is formed on the surface of the adhesion layer 201. The material of the adhesion layer 201 is the same as that of the sacrificial layer formed later. In this embodiment, the material of the adhesion layer 201 is silicon oxide.
The first electrode film layer provides a foundation for the subsequent formation of the first electrode plate, and the patterning treatment is performed on the first electrode film layer to form the first electrode plate.
In this embodiment, the first electrode film layer includes: the device comprises a bottom insulating film layer 22, a conductive film layer 23 positioned on the surface of the bottom insulating film layer 22 and a top insulating film layer 24 positioned on the surface of the conductive film layer 23.
The material of the bottom insulating film layer 22 is silicon nitride, silicon oxynitride or silicon oxycarbonitride; the material of the conductive film layer 23 is polysilicon or metal; the top insulating film layer 24 is made of silicon nitride, silicon oxynitride or silicon oxycarbonitride.
In this embodiment, the bottom insulating film layer 22, the conductive film layer 23 and the top insulating film layer 24 are formed by a chemical vapor deposition process.
Referring to fig. 4, the first electrode film layer is subjected to patterning treatment to form the first electrode plate.
Specifically, forming a patterned photoresist layer on the surface of the first electrode film layer; and etching the first electrode film layer until the surface of the adhesion layer 201 is exposed by taking the patterned photoresist layer as a mask, so as to form a bottom insulating electrode plate 202, a conductive electrode plate 203 positioned on the surface of the bottom insulating electrode plate 202 and a top insulating electrode plate 204 positioned on the surface of the conductive electrode plate 203.
The first electrode plate comprises a supporting area and a vibrating area, and an opening is formed in the first electrode plate of the vibrating area to provide a process foundation for forming the sacrificial film.
Referring to fig. 5, an initial sacrificial film 25 filling the opening is formed, and the initial sacrificial film 25 also covers the top of the first electrode plate.
In this embodiment, the initial sacrificial film 25 is formed by a chemical vapor deposition process, and the material of the initial sacrificial film 25 is silicon oxide.
Referring to fig. 6, the initial sacrificial film 25 above the top of the first electrode plate is removed, forming a sacrificial film 205 filling the opening.
In this embodiment, the initial sacrificial film 25 is planarized.
Referring to fig. 7, a stopper post 206 is formed on the first electrode plate of the vibration region.
The material of the stopper post 206 is different from the material of the sacrificial film 205. In this embodiment, the material of the limiting post 206 is polysilicon.
The process steps for forming the spacing post 206 include: forming a stopper layer on the first electrode plate and the sacrificial film 205; the limiting layer is patterned, and the limiting post 206 is formed on the upper surface of the first electrode plate portion of the vibration region.
In this embodiment, the limiting post 206 is formed on the first electrode plate of the vibration region after the sacrificial film 205 is formed, and in other embodiments, the limiting post may be formed on the first electrode plate of the vibration region before the initial sacrificial film is formed.
Referring to fig. 8, a sacrificial layer 207 is formed on the first electrode plate and on the sacrificial film 205.
Specifically, the sacrificial layer 207 is formed to cover the upper surface of the first electrode plate, the stopper post 206, and the sacrificial film 205, and the stopper post 206 is located in the sacrificial layer 207 before the subsequent cavity is formed.
In this embodiment, the material of the sacrificial layer 207 is silicon oxide. In other embodiments, the material of the sacrificial layer may also be TEOS.
The sacrificial layer 207 is formed using a chemical vapor deposition, physical vapor deposition, or atomic layer deposition process.
Referring to fig. 9, at least one connection groove 208 exposing the first electrode plate is formed in the sacrificial layer 207 over the support region.
The connection slots 208 provide a process basis for subsequent formation of connections through the sacrificial layer 207.
In this embodiment, the connecting slot 208 exposes the top insulating plate 204 of the first electrode plate. The process steps for forming the connection groove 208 include: forming a patterned photoresist layer on the surface of the sacrificial layer 207; etching the sacrificial layer 207 above the supporting region until the surface of the top insulating polar plate 204 is exposed by using the patterned photoresist layer as a mask, so as to form the connecting groove 208; and removing the patterned photoresist layer.
In this embodiment, the connecting groove 208 has a hole structure. In other embodiments, the connecting groove may also be a closed loop structure or a semi-closed loop structure.
Above the same support area, the number of the connecting grooves 208 is one or more. In this embodiment, the number of the connecting grooves 208 is two above the same supporting area as an example.
Referring to fig. 10, a second electrode plate is formed on the surface of the sacrificial layer 207 and in the connection groove 208 (refer to fig. 9), wherein the second electrode plate includes a connection portion 210 filled in the connection groove 208, a supporting portion 211 on the sacrificial layer 207 above the supporting region, and a vibration portion 209 above the vibration region, and the supporting portion 211 is connected to the connection portion 210.
The process steps for forming the second electrode plate comprise: forming an electrode material layer filling the connection groove 208, and the electrode material layer is further positioned on the sacrificial layer 207; the electrode material layer on the sacrificial layer 207 is patterned to form the second electrode plate.
In this embodiment, the material of the second electrode plate is polysilicon. In other embodiments, the material of the second electrode plate may also be doped polysilicon.
The connection portion 210 is located on the surface of the second electrode plate. In this embodiment, the connection portion 210 is located on the surface of the top insulating plate 204, and the connection portion 210 contacts the first electrode plate, that is, the bottom of the second electrode plate contacts the first electrode plate.
Because the material density of the top insulating polar plate 204 and the conductive polar plate 203 is higher than that of the sacrificial layer 207, the performances of the top insulating polar plate 204 and the conductive polar plate 203 are more stable, the internal stress stability of the first polar plate is good, and the internal stress of the corresponding connecting part 210 connected with the first polar plate is not influenced by the internal stress of the first polar plate, so the internal stress of the second polar plate is stable, thereby improving the reliability of the manufactured MEMS device.
The subsequent process steps include forming a first electrode layer on a first electrode plate of the support region, the first electrode layer being electrically connected to the first electrode plate; a second electrode layer is formed on the support portion, and the second electrode layer is electrically connected to the second electrode plate. Regarding the process steps of forming the first electrode layer and the second electrode layer, the following will be described in detail with reference to the accompanying drawings.
Referring to fig. 11, the sacrificial layer 207 over the support region is etched until the surface of the conductive plate 203 is exposed, and a conductive hole 212 is formed in the sacrificial layer 207.
In this embodiment, after the sacrificial layer 207 exposes the top insulating plate 204, the exposed top insulating plate 204 is etched until the conductive plate 203 is exposed, so as to form the conductive hole 212, so that a first electrode layer electrically connected to the conductive plate 203 is formed later.
Referring to fig. 12, a protective layer 213 is formed to cover a sidewall of the sacrificial layer 207 remote from the vibration region, and the protective layer 213 also covers a sidewall of the first electrode plate remote from the vibration region.
In this embodiment, the protection layer 213 also covers the sidewall surface of the conductive via 212.
The material of the protective layer 213 is different from the material of the sacrificial layer 207. The protective layer 213 functions in: in the subsequent process step of etching the sacrificial layer 203 and the sacrificial layer 207 to form a cavity, the protection layer 213 provides protection for the sacrificial layer 207 and the sacrificial layer 203 in the support region, so as to prevent the sacrificial layer 207 and the sacrificial layer 203 in the support region from being etched away.
The material of the protective layer 213 is an insulating material. In this embodiment, the material of the protection layer 213 is silicon nitride. In other embodiments, the material of the protective layer may also be silicon nitride.
Referring to fig. 13, a first electrode layer 214 is formed at the bottom of the conductive via 212 (refer to fig. 12); a second electrode layer 215 is formed on the surface of the support portion 215.
In this embodiment, the material of the first electrode layer 214 is aluminum, and the material of the second electrode layer 215 is aluminum. In other embodiments, the material of the first electrode layer may also be copper or tungsten, and the material of the second electrode layer 215 may also be copper or tungsten.
The process steps of forming the first electrode layer 214 and the second electrode layer 215 include: forming an electrode film on the surface of the protective layer 213, the surface of the second electrode plate and the bottom of the conductive hole; the electrode film is patterned to form the first electrode layer 214 and the second electrode layer 215.
Referring to fig. 14, a substrate 200 located under the vibration region is etched, and a back cavity penetrating through the thickness of the substrate 200 is formed in the substrate 200.
The substrate 200 is etched to form the back cavity to expose the adhesion layer 201 under the vibration region, providing a process basis for removing the adhesion layer 201, the sacrificial film 205, and the sacrificial layer 207 in the vibration region by subsequent etching.
In this embodiment, the process steps of forming the back cavity include: forming a patterned photoresist layer on the back surface of the substrate 200; etching to remove the substrate 200 below the vibration area by using the patterned photoresist layer as a mask, so as to form the back cavity; and removing the patterned photoresist layer.
Next, as shown in fig. 2, the sacrificial film 205 and the sacrificial layer 207 in the vibration region are etched and removed, and the supporting portion 211, the vibration portion 209, the first electrode plate, and the connection portion 210 define a cavity.
Specifically, the adhesion layer 201 exposed by the back cavity is etched to expose the bottom of the sacrificial film 205; then, etching the exposed sacrificial film 205 to expose the bottom of the sacrificial layer 207; the exposed sacrificial layer 207 is etched until the vibration portion 209 and the connection portion 210 nearest to the vibration region are exposed, forming the cavity.
The sacrificial film 205 and the sacrificial layer 207 of the vibration region are etched using a wet etching process.
In this embodiment, the etching liquid used in the wet etching process is a hydrofluoric acid solution.
Compared with the scheme of forming the second electrode plate by taking the sacrificial layer as the growth substrate, in the manufacturing method of the MEMS device provided by the embodiment, the second electrode plate is formed by taking the more stable first electrode plate as the growth substrate, the bottom of the second electrode plate (namely, the bottom of the connecting part) is contacted with the first electrode plate, and the internal stress of the second electrode plate is not influenced, so that the reliability of the manufactured MEMS device is improved.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (20)
1. A MEMS device, comprising:
the first electrode plate comprises a supporting area and a vibrating area, and an opening penetrating through the thickness of the first electrode plate is formed in the first electrode plate in the vibrating area;
a sacrificial layer positioned on the first electrode plate of the supporting region, wherein the material density of the first electrode plate is greater than that of the sacrificial layer;
the second electrode plate comprises a connecting part penetrating through the sacrificial layer, a supporting part positioned on the sacrificial layer above the supporting area and a vibrating part positioned above the vibrating area, wherein the supporting part is connected with the connecting part, the supporting part is connected with the first electrode plate through the connecting part, the connecting part is electrically insulated from the first electrode plate, and a cavity is formed by the first electrode plate, the vibrating part, the supporting part and the connecting part;
the first electrode layer is positioned on the first electrode plate of the supporting area and is electrically connected with the first electrode plate;
and the second electrode layer is positioned on the supporting part and is electrically connected with the second electrode plate.
2. The MEMS device of claim 1, wherein the connection is a columnar structure, a closed hollow ring structure, or a semi-closed hollow ring structure.
3. A MEMS device according to claim 1 or 2, wherein the number of connections is one or more above the same support region.
4. The MEMS device of claim 1, wherein the number of connection portions is a plurality over the same support region, wherein the vibration portion and support portion of the first electrode plate, the second electrode plate, and the connection portion closest to the vibration region enclose the cavity.
5. The MEMS device of claim 1, wherein the first electrode plate comprises a conductive plate and a top insulating plate on the conductive plate; the connecting part is positioned on the surface of the top insulating polar plate.
6. The MEMS device of claim 5, wherein the first electrode plate further comprises a bottom insulating plate positioned below the conductive plate.
7. The MEMS device of claim 6, wherein the material of the conductive plate is metal or polysilicon; the top insulating polar plate is made of silicon nitride, silicon oxynitride or silicon oxycarbide; the material of the bottom insulating polar plate comprises silicon nitride, silicon oxynitride or silicon oxycarbide.
8. The MEMS device of claim 1, wherein the first electrode layer and the second electrode layer are located on opposite sides of the vibration portion, respectively.
9. The MEMS device of claim 1, wherein the connection portion is of unitary construction with the support portion.
10. The MEMS device of claim 1, further comprising: a limit column positioned on the first electrode plate of the vibration area; and the protective layer covers the side wall of the sacrificial layer far away from the vibration area and also covers the side wall of the first electrode plate far away from the vibration area.
11. The MEMS device of claim 1, further comprising: and the first electrode layer is positioned at the bottom of the conductive hole.
12. The MEMS device of claim 1, further comprising: the substrate is provided with a back cavity penetrating through the thickness of the substrate, the first electrode plate is arranged above the substrate, the substrate and the second electrode plate are respectively positioned at two opposite sides of the first electrode plate, and the back cavity is connected with the cavity.
13. The MEMS device of claim 12, further comprising: and an adhesive layer between the substrate and the first electrode plate.
14. A method of manufacturing a MEMS device, comprising:
forming a first electrode plate, wherein the first electrode plate comprises a supporting area and a vibrating area, an opening penetrating through the thickness of the first electrode plate is formed in the first electrode plate of the vibrating area, and a sacrificial film is filled in the opening;
forming a sacrificial layer on the first electrode plate and the sacrificial film, wherein the material density of the first electrode plate is greater than that of the sacrificial layer;
forming at least one connection groove exposing the first electrode plate in the sacrificial layer above the supporting region;
forming a second electrode plate on the surface of the sacrificial layer and in the connecting groove, wherein the second electrode plate comprises a connecting part filled in the connecting groove, a supporting part positioned on the sacrificial layer above the supporting area and a vibrating part positioned above the vibrating area, the supporting part is connected with the connecting part, and the connecting part is electrically insulated from the first electrode plate;
etching to remove the sacrificial film and the sacrificial layer of the vibration area, wherein the first electrode plate, the supporting part, the vibration part and the connecting part form a cavity;
forming a first electrode layer on a first electrode plate of the supporting region, wherein the first electrode layer is electrically connected with the first electrode plate;
a second electrode layer is formed on the support portion, and the second electrode layer is electrically connected to the second electrode plate.
15. The method of manufacturing of claim 14, wherein the first electrode plate comprises a conductive plate and a top insulating plate on the conductive plate; the process steps for forming the connecting groove comprise: and etching the sacrificial layer above the supporting area until the surface of the top insulating polar plate is exposed, so as to form the connecting groove.
16. The method of manufacturing of claim 15, wherein the process step of forming the first electrode layer comprises: etching part of the sacrificial layer above the supporting area until the surface of the conductive polar plate is exposed, and forming a conductive hole in the sacrificial layer; and forming the first electrode layer at the bottom of the conductive hole.
17. The method of manufacturing of claim 16, further comprising the step of, prior to etching the sacrificial film and the sacrificial layer of the vibration region: and forming a protective layer which covers the side wall of the sacrificial layer far away from the vibration area, wherein the protective layer also covers the side wall of the first electrode plate far away from the vibration area, and the protective layer also covers the surface of the side wall of the conductive hole.
18. The method of manufacturing of claim 14, wherein the process step of forming the second electrode plate comprises: forming an electrode material layer filled in the connecting groove, wherein the electrode material layer is also positioned on the sacrificial layer; and patterning the electrode material layer on the sacrificial layer to form the second electrode plate.
19. The method of manufacturing of claim 14, wherein the first electrode plate of the vibration region has a stopper post thereon, and wherein the stopper post is located within the sacrificial layer prior to forming the cavity;
the process steps for forming the sacrificial film, the limit column and the sacrificial layer comprise the following steps: forming an initial sacrificial film filling the opening, wherein the initial sacrificial film also covers the top of the first electrode plate; removing the initial sacrificial film positioned at the top of the first electrode plate to form the sacrificial film; forming a limit post on the first electrode plate of the vibration region before forming the initial sacrificial film or after forming the sacrificial film; and forming the sacrificial layer covering the upper surface of the first electrode plate, the limit column and the sacrificial film.
20. The method of manufacturing of claim 14, further comprising, prior to forming the first electrode plate: providing a substrate; forming the first electrode plate on the substrate;
after forming the second electrode plate and before forming the cavity, the method further comprises the steps of: etching a substrate below the vibration region, and forming a back cavity penetrating through the thickness of the substrate in the substrate; and after the back cavity is formed, etching the sacrificial film and the sacrificial layer exposed by the back cavity to form the cavity.
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