CN109721021A - A kind of MEMS device and preparation method, electronic device - Google Patents
A kind of MEMS device and preparation method, electronic device Download PDFInfo
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- CN109721021A CN109721021A CN201711037349.2A CN201711037349A CN109721021A CN 109721021 A CN109721021 A CN 109721021A CN 201711037349 A CN201711037349 A CN 201711037349A CN 109721021 A CN109721021 A CN 109721021A
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Abstract
The present invention provides a kind of MEMS device and preparation methods, electronic device.The MEMS device includes: vibrating membrane；Backboard, positioned at the top of the vibrating membrane；Cavity, between the vibrating membrane and the backboard；Sacrificial layer, the outside between the vibrating membrane and the backboard and positioned at the cavity；Wherein, the sacrificial layer is in cone, the apex angle missing of the close cavity and the one end being in contact with the backboard in the cone.Structure of the present invention avoids the chipping problem of the backboard described in air pressure test (Air Pressure Test, APT).The method of the invention does not increase light shield, does not increase cost, improves the performance and yield of MEMS device.
Description
Technical field
The present invention relates to technical field of semiconductors, in particular to a kind of MEMS device and preparation method, electronic device.
Background technique
With the continuous development of semiconductor technology, sensor (motion sensor) class product in the market, intelligent hand
Machine, integrated CMOS and MEMS (MEMS) device have become most mainstream, state-of-the-art technology, and more with technology
Newly, the developing direction of this kind of transmission sensors product is the smaller size of scale, the electric property of high quality and lower loss.
Wherein, MEMS sensor is widely used in automotive electronics: as TPMS, engine oil pressure sensor, automobile are stopped
Vehicle system air pressure sensor, air intake manifold of automotive engine pressure sensor (TMAP), common rail for diesel engine pressure sensor；
Consumer electronics: such as tire gauge, sphygmomanometer, cupboard scale, health scale, washing machine, dish-washing machine, refrigerator, micro-wave oven, oven, dust suction
Device pressure sensor, A/C pressure sensor, washing machine, water dispenser, dish-washing machine, solar water heater Liquid level pressure
Sensor；Industrial electronic: such as digital pressure gauge, digital stream scale, industrial batching weighing, electronic audiovisual field: microphone etc.
Equipment.
MEMS microphone is a kind of senser element for acoustic energy being converted into electric signal, capacitor MEMS microphone principle
Exactly acoustic pressure is caused by acoustic aperture to vibrate vibration of membrane, and then changes capacitor.Primary structure has vibrating membrane (VP), air cavity
(Gap) and backboard.
Air pressure test (Air Pressure Test, APT) is one important reliable for MEMS microphone
Property parameter.Higher APT means that the performance of MEMS microphone is higher, tests (Air Pressure in air pressure at present
Test, APT) in would generally generating device fragmentation the problem of, limit the performance and yield of device.
Therefore it needs to be improved further the current device and preparation method, to eliminate the above problem.
Summary of the invention
A series of concept of reduced forms is introduced in Summary, this will in the detailed description section into
One step is described in detail.Summary of the invention is not meant to attempt to limit technical solution claimed
Key feature and essential features do not mean that the protection scope for attempting to determine technical solution claimed more.
In order to overcome the problems, such as that presently, there are the present invention provides a kind of MEMS device, the MEMS device includes:
Vibrating membrane；
Backboard, positioned at the top of the vibrating membrane；
Cavity, between the vibrating membrane and the backboard；
Sacrificial layer, the outside between the vibrating membrane and the backboard and positioned at the cavity；
Wherein, the sacrificial layer is in cone, in the cone close to the cavity and be in contact with the backboard one
The apex angle at end lacks.
Optionally, the shape of the apex angle deleted areas is to the groove being recessed far from the cavity direction.
Optionally, the angle between the surface of the groove and the surface of the backboard is obtuse angle.
Optionally, it is provided with relief hole in the region that the backboard is located above the apex angle deleted areas, for going
Except the apex angle of the one end being in contact in the cone with the backboard.
Optionally, the marginal position that the backboard is located above the apex angle deleted areas is further provided with by described
The outwardly extending extended area of marginal position, for increasing the backboard in the edge-smoothing degree of the apex angle deleted areas.
The present invention also provides a kind of preparation methods of MEMS device, which comprises
Form vibrating membrane；
Sacrificial layer is formed on the vibrating membrane；
Backboard is formed on the sacrificial layer；
Several acoustic aperture for penetrating the backboard and several relief holes on the outside of the acoustic aperture are formed on the backboard；
The sacrificial layer below the acoustic aperture is removed, to form cavity between the vibrating membrane and the backboard, together
When remove below the relief hole in the remaining sacrificial layer close to the cavity and one end for being in contact with the backboard
Apex angle.
Optionally, the shape for removing the angle position is to the groove being recessed far from the cavity direction, the release
Hole is located at the top of the groove.
Optionally, the angle between the surface of the groove and the surface of the backboard is obtuse angle.
Optionally, the marginal position that the backboard is located above the apex angle deleted areas is further provided with by described
The outwardly extending extended area of marginal position, for increasing the backboard in the edge-smoothing degree of the apex angle deleted areas.
Optionally, the method that the acoustic aperture and the relief hole are formed on the backboard includes:
Photoresist layer is formed on the backboard；
Light shield is provided, mask pattern corresponding with the acoustic aperture and the relief hole is formed on the light shield；
The light shield is selected to be exposed, develop to the photoresist layer, to cover described in the formation in the photoresist layer
Film figure；
Using the photoresist layer as backboard described in mask etch, to form the acoustic aperture and the relief hole.
The present invention also provides a kind of electronic device, the electronic device includes above-mentioned MEMS device.
The present invention provides a kind of MEMS device and preparation method thereof, in the outside of acoustic aperture in the device fabrication process
Relief hole is formed, to remove the remaining sacrificial layer simultaneously close to described when removing the sacrificial layer below the acoustic aperture
Cavity and the apex angle of the one end being in contact with the backboard, after removing the apex angle, top corner regions are no longer acute angle
Wedge angle, so as to avoid the chipping problem of backboard described in (Air Pressure Test, APT) is tested in air pressure.
The method of the invention does not increase light shield, does not increase cost, improves the performance and yield of MEMS device.
Detailed description of the invention
Following drawings of the invention is incorporated herein as part of the present invention for the purpose of understanding the present invention.Shown in the drawings of this hair
Bright embodiment and its description, principle used to explain the present invention.
In attached drawing:
Figure 1A shows a kind of structure sectional view of MEMS device；
Figure 1B shows the air pressure test schematic diagram of MEMS device described in Figure 1A；
Fig. 1 C is the top view of backboard and sacrificial layer described in a kind of MEMS device；
Fig. 1 D is the cross-sectional view of backboard and sacrificial layer described in a kind of MEMS device；
Fig. 2 shows the preparation technology flow charts of MEMS device of the present invention；
Fig. 3 A shows the top view of backboard described in MEMS device of the present invention and sacrificial layer；
Fig. 3 B shows the partial enlarged view of the pattern in Fig. 3 A circle；
Fig. 3 C shows the cross-sectional view of backboard described in MEMS device of the present invention and sacrificial layer；
Fig. 3 D shows the partial enlarged view of the pattern in Fig. 3 C circle；
Fig. 4 shows a kind of schematic diagram of electronic device according to the present invention.
Specific embodiment
In the following description, a large amount of concrete details are given so as to provide a more thorough understanding of the present invention.So
And it is obvious to the skilled person that the present invention may not need one or more of these details and be able to
Implement.In other examples, in order to avoid confusion with the present invention, for some technical characteristics well known in the art not into
Row description.
It should be understood that the present invention can be implemented in different forms, and should not be construed as being limited to propose here
Embodiment.On the contrary, provide these embodiments will make it is open thoroughly and completely, and will fully convey the scope of the invention to
Those skilled in the art.In the accompanying drawings, for clarity, the size and relative size in the area Ceng He may be exaggerated.From beginning to end
Same reference numerals indicate identical element.
It should be understood that when element or layer be referred to " ... on ", " with ... it is adjacent ", " being connected to " or " being coupled to " other members
When part or layer, can directly on other elements or layer, it is adjacent thereto, be connected or coupled to other elements or layer, or
There may be elements or layer between two parties.On the contrary, when element is referred to as " on directly existing ... ", " with ... direct neighbor ", " is directly connected to
To " or " being directly coupled to " other elements or when layer, then there is no elements or layer between two parties.Art can be used although should be understood that
Language first, second, third, etc. describes various component, assembly units, area, floor and/or part, these component, assembly units, area, floor and/or portion
Dividing should not be limited by these terms.These terms are used merely to distinguish a component, assembly unit, area, floor or part and another
Component, assembly unit, area, floor or part.Therefore, do not depart from present invention teach that under, first element discussed below, component, area,
Floor or part are represented by second element, component, area, floor or part.
Spatial relation term for example " ... under ", " ... below ", " below ", " ... under ", " ... on ",
" above " etc., herein can for convenience description and being used describe an elements or features shown in figure with it is other
The relationship of elements or features.It should be understood that other than orientation shown in figure, spatial relation term intention further include using with
The different orientation of device in operation.For example, then, being described as " below other elements " if the device in attached drawing is overturn
Or " under it " or " under it " elements or features will be oriented in other elements or features "upper".Therefore, exemplary term
" ... below " and " ... under " it may include upper and lower two orientations.Device, which can be additionally orientated, (to be rotated by 90 ° or other takes
To) and spatial description language as used herein correspondingly explained.
The purpose of term as used herein is only that description specific embodiment and not as limitation of the invention.Make herein
Used time, " one " of singular, "one" and " described/should " be also intended to include plural form, unless the context clearly indicates separately
Outer mode.It is also to be understood that term " composition " and/or " comprising ", when being used in this specification, determines the feature, whole
The presence of number, step, operations, elements, and/or components, but be not excluded for one or more other features, integer, step, operation,
The presence or addition of component, assembly unit and/or group.Herein in use, term "and/or" includes any of related listed item and institute
There is combination.
In order to thoroughly understand the present invention, detailed structure and step will be proposed in following description, to illustrate this
Invent the technical solution proposed.Presently preferred embodiments of the present invention is described in detail as follows, however other than these detailed descriptions, this hair
It is bright to have other embodiments.
MEMS microphone is a kind of senser element for acoustic energy being converted into electric signal, capacitor MEMS microphone principle
Exactly cause the vibration for vibrating mould by acoustic pressure, and then changes capacitor.Primary structure has vibrating membrane (VP), air cavity (Gap),
Backboard and metal pad (contact Pad) composition.
In the MEMS device preparation process, substrate 201, insulating layer 202, vibrating membrane 203, sacrificial layer are sequentially formed
204, backboard 205 and acoustic aperture 206, as shown in Figure 1A, the wherein gap oxide among the upper bottom crown of vibrating membrane and backboard
Mostly as sacrificial layer, by that can be etched away after BOE acid tank, to form cavity.
After MEME device is prepared, it will usually air pressure test (Air Pressure Test, APT) is carried out,
It is an important dependability parameter for MEMS microphone that air pressure, which tests (Air Pressure Test, APT),.
Higher APT means that the performance of MEMS microphone is higher, tests (Air Pressure Test, APT) in air pressure at present
In would generally generating device fragmentation the problem of, as shown in Figure 1B and 1D, limit the performance and yield of device.
Inventor has found that the position of device fragmentation is backboard by analysis, and is the intersection of backboard and sacrificial layer,
During forming the cavity, the region that the remaining sacrificial layer is contacted with the backboard is a pointy acute angle,
As shown in Figure 1 C and 1D, the backboard described in air pressure test (Air Pressure Test, APT) is by the wedge angle
Damage, causes subtle slight crack in backboard.
To solve the above-mentioned problems, this application provides a kind of MEMS device, as shown in figs. 3 a-3d, the MEMS device
Include:
Vibrating membrane 303；
Backboard 305, positioned at the top of the vibrating membrane；
Cavity, between the vibrating membrane and the backboard；
Sacrificial layer 304, the outside between the vibrating membrane and the backboard and positioned at the cavity；
Wherein, the sacrificial layer is in cone, in the cone close to the cavity and be in contact with the backboard one
The apex angle at end lacks, and as shown in circle position in Fig. 3 C, Fig. 3 D shows the partial enlarged view of the pattern in Fig. 3 C circle.
Optionally, the shape at the position of the apex angle missing is the groove being recessed to the edge direction far from the cavity.
Optionally, the angle between the surface of the groove and the surface of the backboard is obtuse angle, as shown in Figure 3 C.
Optionally, the region that the backboard is located above the apex angle deleted areas is provided with relief hole 307, for going
Except the apex angle of one end that the backboard is in contact.
Optionally, the marginal position that the backboard is located above the apex angle deleted areas is further provided with to outside
The extended area that edge extends, for increasing the smooth journey for the marginal position that the backboard is located above the apex angle deleted areas
Degree is become the shape in outside from inner shape as shown in Figure 3A.
In addition, the present invention also provides a kind of preparation methods of MEMS device, which comprises
Form vibrating membrane；
Sacrificial layer is formed on the vibrating membrane；
Backboard is formed on the sacrificial layer；
Several acoustic aperture for penetrating the backboard and the relief hole on the outside of the acoustic aperture are formed on the backboard；
The sacrificial layer below the acoustic aperture and the relief hole is removed, between the vibrating membrane and the backboard
Form cavity, while the remaining sacrificial layer is in cone on the outside of the cavity, in the cone close to the cavity and
The apex angle of the one end being in contact with the backboard lacks.
The present invention provides a kind of MEMS device and preparation method thereof, in the outside of acoustic aperture in the device fabrication process
Relief hole is formed, to remove the remaining sacrificial layer simultaneously close to described when removing the sacrificial layer below the acoustic aperture
Cavity and the apex angle of the one end being in contact with the backboard, after removing the apex angle, top corner regions are no longer acute angle
Wedge angle, so as to avoid the chipping problem of backboard described in (Air Pressure Test, APT) is tested in air pressure.
The method of the invention does not increase light shield, does not increase cost, improves the performance and yield of MEMS device.
It is described in detail below with reference to preparation method of Fig. 2 and Fig. 3 A-3D to MEMS device of the invention, Fig. 2 shows
The preparation technology flow chart of MEMS device of the present invention；Fig. 3 A has gone out backboard described in MEMS device of the present invention and sacrifice
The top view of layer；Fig. 3 B shows the partial enlarged view of the pattern in Fig. 3 A circle；Fig. 3 C shows MEMS device of the present invention
The cross-sectional view of backboard described in part and sacrificial layer；Fig. 3 D shows the partial enlarged view of the pattern in Fig. 3 C circle；
As shown in Figure 3 C, the MEMS device includes: in the present invention
Vibrating membrane 303；
Backboard 305, positioned at the top of the vibrating membrane；
Cavity, between the vibrating membrane and the backboard；
Sacrificial layer 304, the outside between the vibrating membrane and the backboard and positioned at the cavity；
Wherein, the sacrificial layer is in cone, in the cone close to the cavity and be in contact with the backboard one
The apex angle at end lacks, and as shown in circle position in Fig. 3 C, Fig. 3 D shows the partial enlarged view of the pattern in Fig. 3 C circle.
Specifically, as shown in Figure 3 C, wherein the MEMS element may include MEMS microphone, MEMS pressure sensor
With acceleration transducer etc., it is not limited to it is a certain, below to the preparation side of the MEMS device by taking MEMS microphone as an example
Method is described in detail.
Specifically, the MEMS substrate (not shown) can be following at least one of the material being previously mentioned: silicon,
Silicon (SSOI) is laminated on silicon-on-insulator (SOI), insulator, SiGe (S-SiGeOI), germanium on insulator are laminated on insulator
SiClx (SiGeOI) and germanium on insulator (GeOI) etc..
Insulating layer 302 is also formed on the MEMS substrate, wherein the insulating layer can be by using such as silica
The inorganic insulation layer of layer, silicon nitride layer or silicon oxynitride layer, includes polyvinyl phenol, polyimides or siloxanes etc.
Insulating layer etc. of layer is formed.In addition, polyvinyl phenol, polyimides or siloxanes can effectively pass through droplet discharging method, print
Brush art or spin-coating method are formed.Siloxanes can be classified into silica glass, alkyl siloxane polymer, alkyl according to its structure
Silsesquioxane (alkylsilsesquioxane) polymer, silsesquioxane hydride (silsesquioxane
Hydride) polymer, alkyl silsesquioxane hydride (alkylsilsesquioxane hydride) polymer etc..
In addition, insulating layer 302 can be formed with by various deposition methods commonly used in the art.
Wherein, the first groove is formed in the MEMS substrate.
Wherein, first groove is several square grooves being spaced apart from each other, such as first groove can be uniform
It is distributed in the edge of the MEMS substrate.
Wherein, the method for forming the first groove includes: that photoresist layer and exposure development are formed on the MEMS substrate, with
Exposure mask is formed, using the photoresist layer as MEMS substrate described in mask etch, is formed with the surface in the MEMS substrate described
Groove, as shown in Figure 3A.
Wherein the depth of the groove is not limited to a certain numberical range, can according to need and is set.
Dry etching, reactive ion etching (RIE), ion beam milling, plasma etching can be selected in this step.
The vibrating membrane 303 can select the materials such as polysilicon, SiGe, it is not limited to a certain.In this example, institute
It states vibrating membrane 303 and selects polysilicon.
Wherein, the deposition method of the vibrating membrane 303 can be chemical vapor deposition (CVD) method, physical vapour deposition (PVD)
(PVD) low-pressure chemical vapor deposition (LPCVD) of the formation such as method or atomic layer deposition (ALD) method, laser ablation deposition (LAD) with
And one of selective epitaxy growth (SEG), physical vapour deposition (PVD) (PVD) method is selected in the present invention.
It is formed with sacrificial layer on the vibrating membrane 303, specifically includes:
On the MEMS substrate and its upper formation backboard of the sacrificial layer of inside has 305, to cover the sacrifice
Layer.
Wherein, the backboard 305 can select the materials such as polysilicon, SiGe, it is not limited to a certain.In the example
In, the backboard 305 selects polysilicon.
Wherein, the deposition method of the backboard 305 can be chemical vapor deposition (CVD) method, physical vapour deposition (PVD) (PVD)
Low-pressure chemical vapor deposition (LPCVD), laser ablation deposition (LAD) and the choosing of the formation such as method or atomic layer deposition (ALD) method
One of epitaxial growth (SEG) is selected, physical vapour deposition (PVD) (PVD) method is used in the present invention.
Cavity is formed between the vibrating membrane and the backboard.
Also there is remaining sacrificial layer in the unprecedented outside, the sacrificial layer is used to support and fixes the backboard,
Wherein, the backboard is the shapes such as cone wide at the top and narrow at the bottom, such as trapezoidal pyramidal, it is not limited to a certain.
Wherein the cone is formed during etching solution etches to form the cavity, wherein institute in the cone
The shape for stating the position of apex angle missing is the groove being recessed to the edge direction far from the cavity, so that the apex angle of acute angle be gone
It removes.
Optionally, the angle between the surface of the groove and the surface of the backboard is obtuse angle, as shown in Figure 3 C.
Optionally, the region that the backboard is located above the apex angle deleted areas is provided with relief hole 307, for going
Except the apex angle of one end that the backboard is in contact.
Optionally, the marginal position that the backboard is located above the apex angle deleted areas is further provided with to outside
The extended area that edge extends, for increasing the smooth journey for the marginal position that the backboard is located above the apex angle deleted areas
Degree, as shown in Figure 3A, wherein Fig. 3 B shows the partial enlarged view of the pattern in Fig. 3 A circle, by changing to the backboard
Into can be set the relief hole, and then remove the wedge angle of the acute angle.
MEMS device of the present invention is after removing the apex angle, and top corner regions are no longer the wedge angle of acute angle, to keep away
Exempt to test the chipping problem of backboard described in (Air Pressure Test, APT) in air pressure.It is of the present invention
Method does not increase light shield, does not increase cost, improves the performance and yield of MEMS device.
The present invention also provides a kind of preparation methods of MEMS device, as shown in Fig. 2, the key step packet of the preparation method
It includes:
Step S1: vibrating membrane is formed；
Step S2: sacrificial layer is formed on the vibrating membrane；
Step S3: backboard is formed on the sacrificial layer；
Step S4: it is formed on the backboard and penetrates several acoustic aperture of the backboard and several on the outside of the acoustic aperture
Relief hole；
Step S5: removing the sacrificial layer below the acoustic aperture, to be formed between the vibrating membrane and the backboard
Cavity, while removing the close cavity in the remaining sacrificial layer in the relief hole lower section and being in contact with the backboard
One end apex angle.
The present invention provides a kind of MEMS device and preparation method thereof, in acoustic aperture opening in the device fabrication process
Outside forms relief hole, close to remove the remaining sacrificial layer simultaneously when removing the sacrificial layer below the acoustic aperture
The cavity and the apex angle of the one end being in contact with the backboard, after removing the apex angle, top corner regions are no longer sharp
The wedge angle at angle, so as to avoid testing in air pressure, backboard described in (Air Pressure Test, APT) is chipping
Problem.The method of the invention does not increase light shield, does not increase cost, improves the performance and yield of MEMS device.
In the following, being described in detail to the specific embodiment of the preparation method of MEMS device of the invention.
Firstly, executing step 1, MEMS substrate 301 is provided；Vibrating membrane 303 and sacrificial is sequentially formed on the MEMS substrate
Domestic animal layer 304.
Specifically, as shown in Figure 3, wherein the MEMS element may include MEMS microphone, MEMS pressure sensor and
Acceleration transducer etc., it is not limited to it is a certain, below to the preparation method of the MEMS device by taking MEMS microphone as an example
It is described in detail.
Specifically, the MEMS substrate (not shown) can be following at least one of the material being previously mentioned: silicon,
Silicon (SSOI) is laminated on silicon-on-insulator (SOI), insulator, SiGe (S-SiGeOI), germanium on insulator are laminated on insulator
SiClx (SiGeOI) and germanium on insulator (GeOI) etc..
Vibrating membrane 303 and sacrificial layer 304 are sequentially formed on the MEMS substrate, using as vibrating membrane, sacrificial layer, specifically
Ground forming method includes:
Specifically, insulating layer 302 is formed first on the MEMS substrate, wherein the insulating layer can be by using such as
The inorganic insulation layer of silicon oxide layer, silicon nitride layer or silicon oxynitride layer, such as comprising polyvinyl phenol, polyimides or silicon oxygen
Insulating layer of the layer of alkane etc. etc. is formed.In addition, polyvinyl phenol, polyimides or siloxanes can be arranged effectively by droplet
Method, the art of printing or spin-coating method is put to be formed.Siloxanes can be classified into silica glass according to its structure, alkylsiloxane polymerize
Object, alkyl silsesquioxane (alkylsilsesquioxane) polymer, silsesquioxane hydride (silsesquioxane
Hydride) polymer, alkyl silsesquioxane hydride (alkylsilsesquioxane hydride) polymer etc..
In addition, insulating layer 302 can be formed with by various deposition methods commonly used in the art.
Wherein, it is still further comprised before forming the insulating layer and patterned step is carried out to the MEMS substrate,
To form the first groove in the MEMS substrate.
Wherein, first groove is several square grooves being spaced apart from each other, such as first groove can be uniform
It is distributed in the edge of the MEMS substrate.
Wherein, it includes: that photoresist layer and exposure development are formed on the MEMS substrate that formation, which is the method for the first groove,
To form exposure mask, using the photoresist layer as MEMS substrate described in mask etch, to form institute on the surface of the MEMS substrate
Groove is stated, as shown in Figure 3A.
Wherein the depth of the groove is not limited to a certain numberical range, can according to need and is set.
Dry etching, reactive ion etching (RIE), ion beam milling, plasma etching can be selected in this step.
MEMS substrate described in O base etchant etching is selected in this step, selects O in an example of the invention2Gas
Other a small amount of gas such as CF can also be added in atmosphere simultaneously4、CO2、N2, the etching pressure can be 50-200mTorr, such as
100-150mTorr, power 200-600W, while biggish gas flow is selected in the present invention, optionally, in the present invention
The O2Flow be 30-300sccm.
Then the vibrating membrane is formed on the MEMS substrate and is patterned, such as vibration is formed in first groove
Dynamic film 303, to cover first groove.
The vibrating membrane 303 can select the materials such as polysilicon, SiGe, it is not limited to a certain.In this example, institute
It states vibrating membrane 303 and selects polysilicon.
Wherein, the deposition method of the vibrating membrane 303 can be chemical vapor deposition (CVD) method, physical vapour deposition (PVD)
(PVD) low-pressure chemical vapor deposition (LPCVD) of the formation such as method or atomic layer deposition (ALD) method, laser ablation deposition (LAD) with
And one of selective epitaxy growth (SEG), physical vapour deposition (PVD) (PVD) method is used in the present invention.
Sacrificial layer is formed on the vibrating membrane 303, specifically includes:
Step 1: on the vibrating membrane and forming the first sacrificial layer on the insulating layer；
Step 2: patterning first sacrificial layer, to form several second grooves in first sacrificial layer surface；
Step 3: the second sacrificial layer of conformal deposited, to cover first sacrificial layer.
Wherein, first sacrificial layer described in the step 1 select oxide, such as select with the vibrating membrane have compared with
The oxide of big etching selectivity.
In the step 2, first sacrificial layer is patterned, it is several uniform to be formed in first sacrificial layer surface
Second groove of distribution.
Wherein, second groove is conical socket.
The forming method of second groove is referred to the forming method of the first groove, and details are not described herein.
It is then followed by depositing second sacrificial layer, selects the method for conformal deposited to form described second in this step and sacrifices
Layer, it will form second groove in second sacrificial layer.
Wherein, second groove is formed in subsequent steps in the backboard, i.e., formed in backboard to
Under pattern outstanding, and then form the block piece 3072.
Wherein, first sacrificial layer and second sacrificial layer select identical material and identical forming method.
Step 2 is executed, the vibrating membrane, sacrificial layer are patterned, to remove the part vibrating membrane and the sacrificial layer simultaneously
Expose the MEMS substrate.
In the present invention in order to more simplify the processing step, the vibrating membrane is patterned, sacrificial layer step includes:
Mask layer, such as photoresist layer are formed on the vibrating membrane, sacrificial layer；
Development is exposed to the photoresist layer, to remove the part photoresist layer in outside, exposes the sacrifice
Layer；
Then using the mask layer as vibrating membrane, sacrificial layer described in mask etch, to remove the part vibrating membrane and institute
It states sacrificial layer and exposes the MEMS substrate.
Step 3 is executed, on the MEMS substrate of the exposing and its upper formation backboard of the sacrificial layer of inside
305, to cover the sacrificial layer.
Wherein, the backboard 305 can select the materials such as polysilicon, SiGe, it is not limited to a certain.In the example
In, the backboard 305 selects polysilicon.
Wherein, the deposition method of the backboard 305 can be chemical vapor deposition (CVD) method, physical vapour deposition (PVD) (PVD)
Low-pressure chemical vapor deposition (LPCVD), laser ablation deposition (LAD) and the choosing of the formation such as method or atomic layer deposition (ALD) method
One of epitaxial growth (SEG) is selected, physical vapour deposition (PVD) (PVD) method is used in the present invention.
Step 4 is executed, is formed on the backboard and penetrates several acoustic aperture of the backboard and on the outside of the acoustic aperture
Relief hole.
Specifically, it the described method comprises the following steps:
Step 1: the backboard is patterned, to form acoustic aperture 306 and releasing on the outside of the acoustic aperture in the backboard
Discharge hole 307 exposes the sacrificial layer；
Step 2: the sacrificial layer being removed by the method for buffered etch, to form the cavity.
In the step 1, the backboard is patterned first, to form opening in the backboard, using as several sound
Hole, in conducted acoustic waves to the cavity.
Specifically, patterned mask layer, such as photoresist layer are formed on the backboard first, then with the exposure mask
Layer is backboard described in mask etch, to be formed with several acoustic aperture and relief hole in the backboard.
Wherein, the acoustic aperture and relief hole for removing between the backboard and the vibrating membrane in subsequent steps
Sacrificial layer to form cavity, while being removed wedge angle at the top of the remaining sacrificial layer by the relief hole.
Wherein, the critical size of the relief hole is much smaller than the critical size of the acoustic aperture.
Wherein, the sacrificial layer is in cone, in the cone close to the cavity and be in contact with the backboard one
The apex angle at end lacks, and as shown in circle position in Fig. 3 C, Fig. 3 D shows the partial enlarged view of the pattern in Fig. 3 C circle.
Optionally, the shape at the position of the apex angle missing is the groove being recessed to the edge direction far from the cavity.
Optionally, the angle between the surface of the groove and the surface of the backboard is obtuse angle, as shown in Figure 3 C.
Optionally, the region that the backboard is located above the apex angle deleted areas is provided with relief hole 307, for going
Except the apex angle of one end that the backboard is in contact.
Optionally, the marginal position that the backboard is located above the apex angle deleted areas is further provided with to outside
The extended area that edge extends, for increasing the smooth journey for the marginal position that the backboard is located above the apex angle deleted areas
Degree is become the shape in outside from inner shape as shown in Figure 3A.
The method that the acoustic aperture and the relief hole are formed on the backboard includes:
Photoresist layer is formed on the sacrificial layer；
Light shield is provided, the mask pattern with the acoustic aperture and the relief hole is formed on the light shield；
The light shield is selected to be exposed, develop to the photoresist layer, to cover described in the formation in the photoresist layer
Film figure；
Using the photoresist layer as backboard described in mask etch, to form the acoustic aperture and the relief hole.
Specifically, additional increase light shield is not needed in this step, it is only necessary to light shield modify accordingly,
Such as the relief hole and the corresponding pattern of acoustic aperture opening are formed on light shield, i.e., as shown in Figure 3 C.
Dry etching or wet etching is selected to form the opening in this step, details are not described herein.
The sacrificial layer is removed by the method for buffered etch, it is empty to be formed between the backboard and the vibrating membrane
Chamber.
Specifically, the sacrificial layer is removed by the acoustic aperture etching in the backboard, in the vibrating membrane and the back
The cavity is formed between plate.
Such as buffered etch technique (Buffered Oxide Etch) etching is selected to remove the sacrificial layer.
The MEMS device is immersed in the buffered etch liquid, the buffered etch liquid BOE is HF and NH4F is not with
It mixes in proportion.
Such as 6:1BOE etching indicates 49%HF aqueous solution: 40%NH4F aqueous solution=1:6 (volume ratio) ingredient is mixed
It closes.Wherein, HF is main etching solution, NH4F is then used as buffer to use.Wherein, NH is utilized4F fixes H+Concentration, make
The certain rate of etch of holding.
The cavity can be obtained after removing the sacrificial layer.
It there remains the part sacrificial layer on the outside of the cavity in this step, using as support.
It can further include the step of cleaning to the MEMS device after forming the cavity.
So far, the introduction of the correlation step of the preparation method of the exemplary MEMS device of the present invention is completed.The method is also
It may include the step of forming transistor and other correlation steps, details are not described herein again.Also, in addition to the foregoing steps,
This exemplary preparation method can also include other steps, these steps among above-mentioned each step or between different steps
It can be realized by the various techniques in current technique, details are not described herein again.
This application provides a kind of preparation methods of MEMS device, in the outside shape of acoustic aperture in the device fabrication process
At relief hole, to remove the remaining sacrificial layer close to the sky simultaneously when removing the sacrificial layer below the acoustic aperture
Chamber and the apex angle of the one end being in contact with the backboard, after removing the apex angle, top corner regions are no longer the point of acute angle
Angle, so as to avoid the chipping problem of backboard described in (Air Pressure Test, APT) is tested in air pressure.This
Invention the method does not increase light shield, does not increase cost, improves the performance and yield of MEMS device.
The present invention also provides a kind of electronic devices comprising aforementioned MEMS devices.
The electronic device, can be mobile phone, tablet computer, laptop, net book, game machine, television set, VCD,
Any electronic product such as DVD, navigator, camera, video camera, recording pen, MP3, MP4, PSP or equipment, are also possible to have
The intermediate products of above-mentioned MEMS device, such as: the cell phone mainboard etc. with the integrated circuit.
Since the MEMS device for including has higher performance, which is equally had the above advantages.
Wherein, Fig. 4 shows the example of mobile phone handsets.Mobile phone handsets 400, which are equipped with, to be included in shell 401
Display portion 402, operation button 403, external connection port 404, loudspeaker 405, microphone 406 etc..
Wherein the mobile phone handsets include MEMS device above-mentioned, and the MEMS device includes vibrating membrane；Backboard, position
In the top of the vibrating membrane；Cavity, between the vibrating membrane and the backboard；Sacrificial layer, be located at the vibrating membrane and
Outside between the backboard and positioned at the cavity；Wherein, the sacrificial layer is in cone, the close sky in the cone
Chamber and the apex angle of the one end being in contact with backboard missing.The MEMS device is after removing the apex angle, apex angle area
Domain is no longer the wedge angle of acute angle, so as to avoid backboard described in (Air Pressure Test, APT) is tested in air pressure
Chipping problem.The method of the invention does not increase light shield, does not increase cost, improve MEMS device performance and
Yield.
The present invention is illustrated by above-mentioned example, but it is to be understood that, above-mentioned example is only intended to illustrate
With the purpose of explanation, and it is not intended to limit the invention in described example ranges.Furthermore those skilled in the art can be with
Understand, the invention is not limited to above-mentioned example, introduction according to the present invention can also make more kinds of modifications and repair
Change, all fall within the scope of the claimed invention for these variants and modifications.Protection scope of the present invention is by attached power
Sharp claim and its equivalent scope are defined.
Claims (11)
1. a kind of MEMS device, which is characterized in that the MEMS device includes:
Vibrating membrane；
Backboard, positioned at the top of the vibrating membrane；
Cavity, between the vibrating membrane and the backboard；
Sacrificial layer, the outside between the vibrating membrane and the backboard and positioned at the cavity；
Wherein, the sacrificial layer is in cone, close to the cavity and one end for being in contact with the backboard in the cone
Apex angle missing.
2. MEMS device according to claim 1, which is characterized in that the shape of the apex angle deleted areas is to far from institute
State the groove of cavity direction recess.
3. MEMS device according to claim 2, which is characterized in that the surface of the groove and the surface of the backboard it
Between angle be obtuse angle.
4. MEMS device according to claim 2, which is characterized in that be located on the apex angle deleted areas in the backboard
It is provided with relief hole in the region of side, for removing the apex angle of the one end being in contact in the cone with the backboard.
5. MEMS device according to claim 1, which is characterized in that the backboard is located above the apex angle deleted areas
Marginal position be further provided with by the outwardly extending extended area of the marginal position, for increasing the backboard in institute
State the edge-smoothing degree of apex angle deleted areas.
6. a kind of preparation method of MEMS device, which is characterized in that the described method includes:
Form vibrating membrane；
Sacrificial layer is formed on the vibrating membrane；
Backboard is formed on the sacrificial layer；
Several acoustic aperture for penetrating the backboard and several relief holes on the outside of the acoustic aperture are formed on the backboard；
The sacrificial layer below the acoustic aperture is removed, to form cavity between the vibrating membrane and the backboard, is gone simultaneously
Except the top of the close cavity and the one end being in contact with the backboard in the remaining sacrificial layer in the relief hole lower section
Angle.
7. according to the method described in claim 6, it is characterized in that, the shape for removing the angle position is to far from the sky
The groove of cavity direction recess, the relief hole are located at the top of the groove.
8. the method according to the description of claim 7 is characterized in that between the surface of the groove and the surface of the backboard
Angle is obtuse angle.
9. the method according to the description of claim 7 is characterized in that the backboard is located at the side above the apex angle deleted areas
Edge position is further provided with by the outwardly extending extended area of the marginal position, for increasing the backboard on the top
The edge-smoothing degree of angle deleted areas.
10. according to the method described in claim 6, it is characterized in that, forming the acoustic aperture and the release on the backboard
The method in hole includes:
Photoresist layer is formed on the backboard；
Light shield is provided, mask pattern corresponding with the acoustic aperture and the relief hole is formed on the light shield；
The light shield is selected to be exposed, develop to the photoresist layer, to form the exposure mask figure in the photoresist layer
Case；
Using the photoresist layer as backboard described in mask etch, to form the acoustic aperture and the relief hole.
11. a kind of electronic device, which is characterized in that the electronic device includes MEMS device described in one of claim 1 to 5
Part.
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| CN109721021B (en) | 2021-02-02 |
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