CN105635926B

CN105635926B - A kind of MEMS microphone and preparation method thereof, electronic device

Info

Publication number: CN105635926B
Application number: CN201410593751.9A
Authority: CN
Inventors: 张先明; 丁敬秀
Original assignee: Semiconductor Manufacturing International Shanghai Corp
Current assignee: Semiconductor Manufacturing International Shanghai Corp
Priority date: 2014-10-29
Filing date: 2014-10-29
Publication date: 2019-06-28
Anticipated expiration: 2034-10-29
Also published as: CN105635926A

Abstract

The present invention relates to a kind of MEMS microphones and preparation method thereof, electronic device.The described method includes: step S1: providing MEMS wafer, be formed with vibrating diaphragm in the MEMS wafer, be formed with sacrificial material layer on the vibrating diaphragm；Step S2: sequentially forming plasma enhancing SiN layer and low pressure SiN layer in the sacrificial material layer, to form backboard.The present invention has the advantages that (1) SiN layer surface will not be damaged, color will not be lost.(2) after depositing the plasma enhancing SiN layer, annealing steps are optional, it is not necessary to execution.(3) process costs are low.

Description

A kind of MEMS microphone and preparation method thereof, electronic device

Technical field

The present invention relates to semiconductor fields, in particular it relates to a kind of MEMS microphone and preparation method thereof, electronics Device.

Background technique

In consumer electronics field, multifunctional equipment is increasingly liked by consumer, compared to the simple equipment of function, Multifunctional equipment manufacturing process will be more complicated, for example need to integrate the chip of multiple and different functions in circuit version, thus go out 3D integrated circuit (integrated circuit, IC) technology is showed.

Wherein, microelectromechanical systems (MEMS) is in volume, power consumption, weight and in price with fairly obvious excellent Gesture, has developed a variety of different sensors so far, for example, pressure sensor, acceleration transducer, inertial sensor and Other sensors.

In the field MEMS, the working principle of capacitive MEMS device is to generate capacitor by the movement of vibrating diaphragm (Membrane) Variation, using capacitance change carry out operation and work, existing common MEMS microphone includes vibrating diaphragm, backboard and is located at Back chamber composition below backboard.Voice signal is converted into electric signal by vibrating diaphragm.

At present in the preparation process of MEMS microphone, need to remove after forming vibrating diaphragm and backboard the vibrating diaphragm and The sacrificial material layer of sacrificial material layer and the backboard other side between backboard, to be respectively formed cavity and back chamber.In the process Described in backboard usually select SiN, and select wet process BOE etching removal backboard two sides sacrificial material layer, it is etched at this Cheng Zhonghui damages the backboard SiN, since the backboard SiN has specific color, when the backboard SiN is damaged Bad when, occurs color and eliminates phenomenon (discolor), causes the yield of device and the reduction of performance.

Therefore, the preparation method of MEMS microphone is unfavorable for mass production there are above-mentioned drawback in the prior art, needs Current described MEMS microphone and preparation method thereof is improved further, to eliminate the 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.

The present invention is in order to overcome the problems, such as that presently, there are provide a kind of preparation method of MEMS microphone, comprising:

Step S1: MEMS wafer is provided, vibrating diaphragm is formed in the MEMS wafer, sacrifice is formed on the vibrating diaphragm Material layer；

Step S2: sequentially forming plasma enhancing SiN layer and low pressure SiN layer in the sacrificial material layer, to be formed Backboard.

Optionally, the method may further comprise:

Step S3: patterning the backboard, to form several openings in the backboard；

Step S4: sacrificial material layer again, to cover the backboard and fill the opening；

Step S5: MEMS technology is executed, removes the sacrificial material layer of the backboard two sides, then to be respectively formed wheat Gram wind cavity and back chamber.

Optionally, in the step S2, the low pressure SiN layer with a thickness of 100-200nm.

Optionally, in the step S2, the depositing temperature of the low pressure SiN layer is 700-800 DEG C.

Optionally, in the step S2, the sedimentation time of the low pressure SiN layer is 30-90min.

Optionally, in the step S2, the deposition pressure of the low pressure SiN layer is less than 1torr.

Optionally, the sacrificial material layer selects plasma enhanced oxidation object.

Optionally, buffered oxide etchant is selected to carry out wet etching in the step S5, to remove the sacrifice material The bed of material.

The present invention also provides a kind of MEMS microphones being prepared based on the above method.

The present invention also provides a kind of electronic devices, including above-mentioned MEMS microphone.

The present invention in order to solve the problems in the existing technology, deposition plasma enhancing SiN layer (PE-SiN) it It is further formed low pressure SiN layer above the plasma enhancing SiN layer (PE-SiN) afterwards, to form backboard, subsequent In wet process BOE etching process, the BOE etching is far smaller than the plasma to the etch-rate of the low pressure SiN layer and increases Strong SiN layer (PE-SiN), therefore the low pressure SiN layer will not be damaged, and low described in subsequent processing step It presses SiN layer without removal, can be used as a part of backboard, make the backboard being prepared that there is good pattern and performance, The method not only simple process, but also will increase process costs, while MEMS will not be improved there is a phenomenon where losing color The performance and yield of microphone.

The present invention has the advantages that

(1) SiN layer surface will not be damaged, and will not lose color.

(2) after depositing the plasma enhancing SiN layer, annealing steps are optional, it is not necessary to execution.

(3) process costs are low.

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, device used to explain the present invention and principle.In the accompanying drawings,

Fig. 1 a-1b is the preparation process schematic diagram of MEMS microphone described in the prior art；

Fig. 2 is the preparation process schematic diagram of MEMS microphone described in one embodiment of the invention；

Fig. 3 is the preparation technology flow chart of MEMS microphone in the embodiment of the 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 " it is other When element 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 by person.On the contrary, when element is referred to as " on directly existing ... ", " with ... direct neighbor ", " directly It is connected to " or " being directly coupled to " other elements or when layer, then there is no elements or layer between two parties.It should be understood that although can make Various component, assembly units, area, floor and/or part are described with term first, second, third, etc., these component, assembly units, area, floor and/ Or part should not be limited by these terms.These terms be used merely to distinguish a component, assembly unit, area, floor or part with it is another One component, assembly unit, area, floor or part.Therefore, do not depart from present invention teach that under, first element discussed below, portion Part, area, floor or part are represented by second element, component, area, floor or part.

Spatial relation term for example " ... under ", " ... below ", " below ", " ... under ", " ... it On ", " above " etc., herein can for convenience description and being used describe an elements or features shown in figure with The relationship of other elements or features.It should be understood that spatial relation term intention further includes making other than orientation shown in figure With the different orientation with the device in operation.For example, then, being described as " under other elements if the device in attached drawing is overturn Face " or " under it " or " under it " elements or features will be oriented in other elements or features "upper".Therefore, exemplary art Language " ... below " and " ... under " it may include upper and lower two orientations.Device can additionally be orientated (be rotated by 90 ° or its It is orientated) 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 step and detailed structure will be proposed in following description, so as to Illustrate technical solution of the present invention.Presently preferred embodiments of the present invention is described in detail as follows, however other than these detailed descriptions, this Invention can also have other embodiments.

The method of MEMS microphone is prepared in the prior art as shown in Fig. 1 a-1b, and offer MEMS wafer first (is not shown in figure Out), vibrating diaphragm 101 is then formed on the MEMS, sacrificial material layer 102 is then formed on the vibrating diaphragm, and described sacrificial Backboard 103 is formed in domestic animal material layer 102, the backboard 103 selects plasma enhancing SiN (PE-SiN), then executes annealing Technique.

Then the backboard 103 is patterned, to form several openings being spaced apart from each other on the backboard, then continues to sink The product sacrificial material layer 102, to cover the backboard and the opening, as shown in Figure 1a.

Then MEMS technology is executed, removes the expendable material of the backboard two sides by the opening in subsequent steps Layer, to be respectively formed microphone cavity and back chamber, as shown in Figure 1 b.In this step, wet process BOE etching removal backboard two is selected The sacrificial material layer of side can damage the backboard SiN in the etching process, since the backboard SiN is with specific Color, when the backboard SiN is damaged i.e. occur color eliminate phenomenon (discolor), cause the yield and property of device The reduction of energy.

Solution to the problems described above includes following two at present: first method is to increase plasma enhancing SiN (PE-SiN) depositing temperature is increased to 480 DEG C by depositing temperature, but the method is needed in special deposition chambers Middle execution brings many inconvenience to device preparation technology.

Second method is to increase the annealing of the annealing process executed after plasma enhancing SiN (PE-SiN) deposition Temperature and annealing time, such as anneal 3 hours at 650 DEG C, but the technique ampleness of the method (Little margin) becomes It is small, and the increase of annealing temperature and annealing time improves process costs.

Therefore, there is drawback in above two method, and the preparation method to the current MEMS microphone is needed to make into one The improvement of step, to eliminate the above problem.

Embodiment 1

In order to solve the problems in the existing technology, a kind of preparation method of MEMS microphone is provided, below with reference to Attached drawing 2 is further described the method.

Firstly, executing step 201, MEMS wafer is provided, and forms vibrating diaphragm 201 in the MEMS wafer.

Specifically, as shown in Figure 2, wherein the MEMS wafer can select one of Si, polysilicon, SiGe, not It is confined to a certain kind.

Vibrating diaphragm 201 is formed in the MEMS wafer, wherein the vibrating diaphragm 201 can select Si or polysilicon, rear The variation for generating capacitor in continuous step by the movement of vibrating diaphragm (Membrane) carries out operation and work using capacitance change Make, the MEMS microphone includes vibrating diaphragm, backboard and the back chamber composition below backboard, is converted voice signal by vibrating diaphragm At electric signal.

It should be noted that other conventional steps can also be further included before forming the vibrating diaphragm, it is no longer superfluous herein It states, those skilled in the art can be configured according to specific needs.

Execute step 202, the sacrificial material layer 202 on the vibrating diaphragm 201, to cover the vibrating diaphragm 201.

Specifically, as shown in Fig. 2, forming sacrificial material layer above the vibrating diaphragm, to remove in subsequent steps Microphone cavity is formed after the sacrificial material layer 202.

Optionally, the sacrificial material layer 202 can select oxide skin(coating), such as can select plasma enhanced oxidation Object (PE-Ox).

Further, the thickness of the plasma enhanced oxidation object (PE-Ox) is not limited to a certain numberical range, can be with It is configured according to specific needs.

Wherein, the deposition method of the plasma enhanced oxidation object (PE-Ox) can select chemical vapor deposition (CVD) Low-pressure chemical vapor deposition (LPCVD), the laser of the formation such as method, physical vapour deposition (PVD) (PVD) method or atomic layer deposition (ALD) method One of ablation deposition (LAD) and selective epitaxy growth (SEG).

Step 203 is executed, deposition plasma enhancing SiN layer 203 (PE-SiN) in the sacrificial material layer 202.

Specifically, as shown in Fig. 2, the deposition method of the plasma enhancing SiN layer 203 can select conventional deposition Method is not needed to improve depositing temperature, be carried out in conventional deposition chambers, to simplify processing step.

The target thickness with a thickness of backboard of the plasma enhancing SiN layer 203 (PE-SiN), or it is slightly smaller than described The target thickness of backboard.

Wherein, the deposition method of the plasma enhancing SiN layer 203 can select chemical vapor deposition (CVD) method, object Low-pressure chemical vapor deposition (LPCVD), the laser ablation of the formation such as physical vapor deposition (PVD) method or atomic layer deposition (ALD) method Deposit one of (LAD) and selective epitaxy growth (SEG).

The present invention is easy in the next steps in order to solve plasma enhancing SiN layer described in the prior art (PE-SiN) The problem of being damaged, losing color, in the followed by execution step for depositing the plasma enhancing SiN layer (PE-SiN) 204, low pressure SiN layer 204 is deposited, on the plasma enhancing SiN layer (PE-SiN) to form backboard.

Specifically, as shown in Fig. 2, in this step, one layer is deposited on the plasma enhancing SiN layer (PE-SiN) Low pressure SiN layer (LP-SiN) 204, to protect the plasma enhancing SiN layer (PE-SiN).

Wherein, the low pressure SiN layer (LP-SiN) can select low-pressure chemical vapor deposition (LPCVD), ultralow pressure chemistry Be vapor-deposited one of (VLPCVD), or selects other deposition methods commonly used in the art, it is not limited to a certain.

Optionally, it in order to improve the etch-resistance energy of the low pressure SiN layer (LP-SiN) in the next steps, needs to make low Press SiN layer (LP-SiN) have thickness appropriate, such as in the present invention the low pressure SiN layer (LP-SiN) with a thickness of 100- 200nm。

In addition, in order to reduce the damage to low pressure SiN layer (LP-SiN), the depositing temperature of the low pressure SiN layer is 700- 800℃。

Further, the sedimentation time of the low pressure SiN layer is 30-90min.

Further, the deposition pressure of the low pressure SiN layer is less than 1torr.

In subsequent wet process BOE etching process, the BOE etching is much small to the etch-rate of the low pressure SiN layer In the plasma enhancing SiN layer (PE-SiN), therefore the plasma enhancing SiN layer (PE-SiN) can be formed and be protected Shield, it is ensured that plasma enhancing SiN layer (PE-SiN) is not damaged, and the low pressure SiN described in subsequent processing step Layer can be used as a part of backboard, not only simple process, but also will increase process costs, while will not send out without removal Raw the phenomenon that losing color, improve the performance and yield of MEMS microphone.

Optionally, due to being formed with the low pressure SiN layer on the plasma enhancing SiN layer (PE-SiN), Annealing steps can be executed after the plasma enhancing SiN layer (PE-SiN) deposition, but the annealing steps are not It is necessary.

Step 205 is executed, the backboard is patterned, to form several openings in the backboard.

Specifically, patterned mask layer, such as photoetching are formed in the low pressure SiN layer 204 first in this step Glue-line, then using the mask layer as plasma enhancing SiN layer 203 (PE-SiN) and low pressure SiN layer described in mask etch (LP-SiN) 204, to be formed in the plasma enhancing SiN layer 203 (PE-SiN) and low pressure SiN layer (LP-SiN) 204 There are several openings.

Wherein, several openings for removing the sacrificial material layer of the backboard two sides in subsequent steps, with shape At microphone cavity and back chamber.

Wherein, the opening is spaced apart from each other setting, and the number of the opening is also not limited to a certain numberical range, can be with It is configured according to specific needs.

Step 206 is executed, again sacrificial material layer 202, to cover the backboard and fill the opening.

Specifically, the sacrificial material layer 202 can select oxide skin(coating), such as can select plasma enhanced oxidation Object (PE-Ox).

The step of can further include execution planarization after this step can select common planarization side Method, details are not described herein.

Step 207 is executed, MEMS technology is executed, then removes the sacrificial material layer of the backboard two sides, to be formed Microphone cavity and back chamber.

Specifically, after depositing the sacrificial material layer, other techniques can also be further included, such as in the vibration Opening is formed above film, to receive various vibration signals, but is not limited to the example, details are not described herein.

After having executed the MEMS technology, the sacrificial material layer of the backboard two sides is removed, to form Mike Wind cavity and back chamber.

In this step, buffered oxide etchant (Buffered Oxide Etchant, BOE) is selected to carry out wet process erosion It carves, to remove the sacrificial material layer.

Wherein, the BOE is that HF and NH4F are mixed according to different proportion.Wherein, HF is main etching solution, and NH4F is then It is used as buffer.The concentration that (H+) is fixed using NH4F is allowed to keep certain rate of etch to the sacrificial material layer, together When to the low pressure SiN layer (LP-SiN) 204 have lower etch-rate.

Further, the concentration of HF and NH4F can according to need and be adjusted in the BOE, it is not limited to a certain numerical value Range.

After the sacrificial material layer for removing the backboard two sides, MEMS microphone is formed between the vibrating diaphragm and backboard Cavity forms back chamber in the other side of the backboard, to form MEMS microphone.

So far, the introduction of the correlation step of the MEMS microphone preparation of the embodiment of the present invention is completed.Above-mentioned steps it It afterwards, can also include other correlation steps, details are not described herein again.Also, in addition to the foregoing steps, the preparation side of the present embodiment Method can also include other steps among above-mentioned each step or between different steps, these steps can be by existing Various techniques in technology realize that details are not described herein again.

The present invention has the advantages that

(1) SiN layer surface will not be damaged, and will not lose color.

(3) process costs are low.

Fig. 3 be the embodiment of the invention described in MEMS microphone preparation technology flow chart, specifically include with Lower step:

Embodiment 2

The present invention also provides a kind of MEMS device, the MEMS device is prepared by 1 the method for embodiment, It is formed with low pressure SiN layer in plasma enhancing SiN layer described in the MEMS device, forms protection to it, it will not be to described The surface of backboard damages, and will not improve the performance and yield of MEMS microphone there is a phenomenon where losing color.

Embodiment 3

The present invention also provides a kind of electronic devices, including MEMS device as described in example 2.Wherein, semiconductor devices For MEMS device as described in example 2, or the MEMS device obtained according to preparation method described in embodiment 1.

The electronic device of the present embodiment can be mobile phone, tablet computer, laptop, net book, game machine, TV Any electronic product such as machine, VCD, DVD, navigator, camera, video camera, recording pen, MP3, MP4, PSP or equipment can also be Any intermediate products including the MEMS device.The electronic device of the embodiment of the present invention, due to having used above-mentioned MEMS device Part, thus there is better performance.

The present invention has been explained by the above embodiments, but it is to be understood that, above-described embodiment is only intended to The purpose of citing and explanation, is not intended to limit the invention to the scope of the described embodiments.Furthermore those skilled in the art It is understood that the present invention is not limited to the above embodiments, introduction according to the present invention can also be made more kinds of member Variants and modifications, all fall within the scope of the claimed invention for these variants and modifications.Protection scope of the present invention by The appended claims and its equivalent scope are defined.

Claims

1. a kind of preparation method of MEMS microphone, comprising:

Step S1: MEMS wafer is provided, vibrating diaphragm is formed in the MEMS wafer, is formed with expendable material on the vibrating diaphragm Layer；

Step S2: sequentially forming plasma enhancing SiN layer and low pressure SiN layer in the sacrificial material layer, to form backboard；

Step S3: patterning the backboard, to form several openings in the backboard；

Step S5: MEMS technology is executed, removes the sacrificial material layer of the backboard two sides, then to be respectively formed microphone Cavity and back chamber.

2. the method according to claim 1, wherein in the step S2, the low pressure SiN layer with a thickness of 100nm-200nm。

3. the method according to claim 1, wherein in the step S2, the deposition temperature of the low pressure SiN layer Degree is 700 DEG C -800 DEG C.

4. the method according to claim 1, wherein in the step S2, when the deposition of the low pressure SiN layer Between be 30min-90min.

5. the method according to claim 1, wherein in the step S2, the deposition pressure of the low pressure SiN layer Power is less than 1torr.

6. the method according to claim 1, wherein the sacrificial material layer selects plasma enhanced oxidation Object.

7. the method according to claim 1, wherein selecting buffered oxide etchant to carry out in the step S5 Wet etching, to remove the sacrificial material layer.

8. a kind of MEMS microphone being prepared based on one of claim 1 to 7 the method.

9. a kind of electronic device, including MEMS microphone according to any one of claims 8.