CN105635926A

CN105635926A - MEMS microphone, preparing method thereof and electronic device comprising MEMS microphone

Info

Publication number: CN105635926A
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: 2016-06-01
Anticipated expiration: 2034-10-29
Also published as: CN105635926B

Abstract

The invention relates to an MEMS microphone, a preparing method thereof and an electronic device comprising the MEMS microphone. The preparing method comprises the steps of a step S1, providing an MEMS wafer on which a diaphragm is formed, and a sacrificial material layer is formed on the diaphragm; and a step S2, successively forming a plasma reinforced SiN layer and a low-voltage SiN layer on the sacrificial material layer, thereby forming a backboard. The microphone, the preparing method thereof and the electronic device are advantageous in that (1) the surface of the SiN layer is not damaged, and color fading is prevented; (2) after deposition of the plasma reinforced SiN layer, an annealing step is selective and is not necessary; and (3) low process cost is realized.

Description

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

Technical field

The present invention relates to semiconductor applications, in particular it relates to a kind of MEMS microphone and preparation method thereof, electronic installation.

Background technology

At consumer electronics field, multifunctional equipment is increasingly subject to liking of consumer, compared to the simple equipment of function, multifunctional equipment manufacturing process will be more complicated, than the chip if desired for multiple difference in functionalitys integrated in circuit version, thus occur in that 3D integrated circuit (integratedcircuit, IC) technology.

Wherein, microelectromechanical systems (MEMS) is in volume, power consumption, weight and has fairly obvious advantage in price, so far multiple different sensor is had been developed over, for instance pressure transducer, acceleration transducer, inertial sensor and other sensor.

In MEMS field, the operation principle of capacitive MEMS device is to be produced the change of electric capacity by the motion of vibrating diaphragm (Membrane), utilizing capacitance change to carry out computing and work, existing conventional MEMS microphone includes vibrating diaphragm, backboard and is positioned at the back of the body chamber composition below backboard. Acoustical signal is converted to the signal of telecommunication by vibrating diaphragm.

At present in the preparation process of MEMS microphone, after forming vibrating diaphragm and backboard, need the sacrificial material layer of sacrificial material layer and the backboard opposite side removing between described vibrating diaphragm and backboard, to form cavity and back of the body chamber respectively. SiN generally selected by described backboard in this process, and select wet method BOE etching to remove the sacrificial material layer of backboard both sides, described backboard SiN can be caused damage by this etching process, owing to described backboard SiN has specific color, occur when described backboard SiN is damaged color to eliminate phenomenon (discolor), cause the yield of device and the reduction of performance.

Therefore, in prior art there is above-mentioned drawback in the preparation method of MEMS microphone, is unfavorable for mass production, it is necessary to current described MEMS microphone and preparation method thereof is improved further, in order to eliminate this problem.

Summary of the invention

Introducing the concept of a series of reduced form in Summary, this will further describe in detailed description of the invention part. The Summary of the present invention is not meant to the key feature and the essential features that attempt to limit technical scheme required for protection, does not more mean that the protection domain attempting to determine technical scheme required for protection.

The present invention is in order to overcome the problem of presently, there are, it is provided that the preparation method of a kind of MEMS microphone, including:

Step S1: MEMS wafer is provided, is formed with vibrating diaphragm in described MEMS wafer, is formed with sacrificial material layer on described vibrating diaphragm;

Step S2: sequentially form plasma enhancing SiN layer and low pressure SiN layer in described sacrificial material layer, to form backboard.

Alternatively, described method may further comprise:

Step S3: pattern described backboard, to form some openings in described backboard;

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

Step S5: perform MEMS technology, then remove the described sacrificial material layer of described backboard both sides, to form microphone cavity and back of the body chamber respectively.

Alternatively, in described step S2, the thickness of described low pressure SiN layer is 100-200nm.

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

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

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

Alternatively, described sacrificial material layer selects plasma enhanced oxidation thing.

Alternatively, buffered oxide etch agent is selected to carry out wet etching in described step S5, to remove described sacrificial material layer.

Present invention also offers a kind of MEMS microphone prepared based on said method.

Present invention also offers a kind of electronic installation, including above-mentioned MEMS microphone.

The present invention is to solve problems of the prior art, low pressure SiN layer is formed further over described plasma enhancing SiN layer (PE-SiN) after deposition plasma strengthens SiN layer (PE-SiN), to form backboard, in follow-up wet method BOE etching process, the etch-rate of described low pressure SiN layer is far smaller than described plasma enhancing SiN layer (PE-SiN) by described BOE etching, cause damage thus without to described low pressure SiN layer, and low pressure SiN layer is without removal described in follow-up processing step, can as a part for backboard, the backboard prepared is made to have good pattern and performance, described method not only technique is simple, and process costs can be increased, the phenomenon of color will not be lost simultaneously, improve performance and the yield of MEMS microphone.

It is an advantage of the current invention that:

(1) SiN layer surface will not suffer damage, and will not lose color.

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

(3) process costs is low.

Accompanying drawing explanation

The drawings below of the present invention is used for understanding the present invention in this as the part of the present invention. Shown in the drawings of embodiments of the invention and description thereof, it is used for explaining assembly of the invention and principle. In the accompanying drawings,

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

Detailed description of the invention

In the following description, a large amount of concrete details is given to provide more thorough understanding of the invention. It is, however, obvious to a person skilled in the art that the present invention can be carried out without these details one or more. In other example, in order to avoid obscuring with the present invention, technical characteristics more well known in the art are not described.

It should be appreciated that the present invention can implement in different forms, and should not be construed as being limited to embodiments presented herein. On the contrary, provide these embodiments will make openly thoroughly with complete, and will fully convey the scope of the invention to those skilled in the art. In the accompanying drawings, in order to clear, the size in Ceng He district and relative size are likely to be exaggerated. Same reference numerals represents identical element from start to finish.

It is understood that, when element or layer be referred to as " ... on ", " with ... adjacent ", " being connected to " or " being coupled to " other element or during layer, its can directly on other element or layer, adjacent thereto, be connected or coupled to other element or layer, or can there is element between two parties or layer. On the contrary, when element be referred to as " directly exist ... on ", " with ... direct neighbor ", " being directly connected to " or " being directly coupled to " other element or during layer, then be absent from element between two parties or layer. Although it should be understood that and term first, second, third, etc. can being used to describe various element, parts, district, floor and/or part, these elements, parts, district, floor and/or part should not be limited by these terms. These terms are used merely to distinguish an element, parts, district, floor or part and another element, parts, district, floor or part. Therefore, without departing under present invention teach that, the first element discussed below, parts, district, floor or part are represented by the second element, parts, district, floor or part.

Spatial relationship term such as " ... under ", " ... below ", " following ", " ... under ", " ... on ", " above " etc., here can be used thus the relation of shown in description figure a element or feature and other element or feature for convenient description. It should be understood that except the orientation shown in figure, spatial relationship term is intended to also include the different orientation of the device in using and operating. Such as, if the device upset in accompanying drawing, then, be described as " below other element " or " under it " or " under it " element or feature will be oriented to other element or feature " on ". Therefore, exemplary term " ... below " and " ... under " upper and lower two orientations can be included. Device can additionally orientation (90-degree rotation or other orientation) and as used herein spatial description language correspondingly explained.

As used herein term only for purpose of describing specific embodiment and the restriction not as the present invention. When using at this, " one ", " one " and " described/to be somebody's turn to do " of singulative is also intended to include plural form, unless context is expressly noted that other mode. It is also to be understood that term " composition " and/or " including ", when using in this specification, determine the existence of described feature, integer, step, operation, element and/or parts, but be not excluded for one or more other feature, integer, step, operation, element, the existence of parts and/or group or interpolation. When using at this, term "and/or" includes any of relevant Listed Items and all combinations.

In order to thoroughly understand the present invention, detailed step and detailed structure will be proposed in following description, in order to explaination technical scheme. Presently preferred embodiments of the present invention is described in detail as follows, but except these detailed descriptions, the present invention can also have other embodiments.

Prior art is prepared the method for MEMS microphone such as shown in Fig. 1 a-1b, first MEMS wafer (not shown) is provided, then on described MEMS, form vibrating diaphragm 101, then on described vibrating diaphragm, form sacrificial material layer 102, and in described sacrificial material layer 102, form backboard 103, plasma enhancing SiN (PE-SiN) selected by described backboard 103, then performs annealing process.

Then pattern described backboard 103, to form some spaced openings on described backboard, then continue to deposit described sacrificial material layer 102, to cover described backboard and described opening, as shown in Figure 1a.

Then perform MEMS technology, removed the sacrificial material layer of described backboard both sides in subsequent steps by described opening, to form microphone cavity and back of the body chamber respectively, as shown in Figure 1 b. In this step, wet method BOE etching is selected to remove the sacrificial material layer of backboard both sides, described backboard SiN can be caused damage by this etching process, owing to described backboard SiN has specific color, occur when described backboard SiN is damaged color to eliminate phenomenon (discolor), cause the yield of device and the reduction of performance.

Current solution to the problems described above includes following two: first method is increase the depositing temperature of plasma enhancing SiN (PE-SiN), described depositing temperature is increased to 480 DEG C, but described method needs to perform in special deposition chambers, brings a lot of inconvenience to device preparation technology.

Second method is for increasing annealing temperature and the annealing time of the annealing process performed after described plasma enhancing SiN (PE-SiN) deposits, such as anneal 3 hours at 650 DEG C, but the technique enough and to spare (Littlemargin) of described method diminishes, and the increase of annealing temperature and annealing time makes process costs improve.

Therefore, all there is drawback in above two method, it is necessary to the preparation method of current described MEMS microphone is improved further, in order to eliminates the problems referred to above.

Embodiment 1

In order to solve problems of the prior art, it is provided that the preparation method of a kind of MEMS microphone, below in conjunction with accompanying drawing 2, described method is further described.

First, perform step 201, it is provided that MEMS wafer, and in described MEMS wafer, form vibrating diaphragm 201.

Specifically, as in figure 2 it is shown, wherein, described MEMS wafer can select the one in Si, polysilicon, SiGe, it is not limited to a certain.

Described MEMS wafer is formed vibrating diaphragm 201, wherein said vibrating diaphragm 201 can select Si or polysilicon, to be produced the change of electric capacity in subsequent steps by the motion of vibrating diaphragm (Membrane), capacitance change is utilized to carry out computing and work, described MEMS microphone includes vibrating diaphragm, backboard and is positioned at the back of the body chamber composition below backboard, converts acoustical signal to the signal of telecommunication by vibrating diaphragm.

It should be noted that and can also comprise other conventional steps further before forming described vibrating diaphragm, not repeating them here, those skilled in the art can be configured according to specific needs.

Performing step 202, sacrificial material layer 202 on described vibrating diaphragm 201, to cover described vibrating diaphragm 201.

Specifically, as in figure 2 it is shown, be formed over sacrificial material layer at described vibrating diaphragm, in order to remove described sacrificial material layer 202 in subsequent steps and be subsequently formed microphone cavity.

Alternatively, described sacrificial material layer 202 can select oxide skin(coating), for instance can select plasma enhanced oxidation thing (PE-Ox).

Further, the thickness of described plasma enhanced oxidation thing (PE-Ox) is not limited to a certain numerical range, it is possible to be configured according to specific needs.

Wherein, the deposition process of described plasma enhanced oxidation thing (PE-Ox) can select the one in low-pressure chemical vapor deposition (LPCVD), laser ablation deposition (LAD) and selective epitaxy growth (SEG) that chemical vapour deposition (CVD) (CVD) method, physical vapour deposition (PVD) (PVD) method or ald (ALD) method etc. are formed.

Performing step 203, in described sacrificial material layer 202, deposition plasma strengthens SiN layer 203 (PE-SiN).

Specifically, as in figure 2 it is shown, the deposition process of described plasma enhancing SiN layer 203 can select the deposition process of routine, it is not necessary to improve depositing temperature, carry out in conventional deposition chambers, in order to Simplified flowsheet step.

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

Wherein, the deposition process of described plasma enhancing SiN layer 203 can select the one in low-pressure chemical vapor deposition (LPCVD), laser ablation deposition (LAD) and selective epitaxy growth (SEG) that chemical vapour deposition (CVD) (CVD) method, physical vapour deposition (PVD) (PVD) method or ald (ALD) method etc. are formed.

The present invention is to solve that plasma enhancing SiN layer described in prior art (PE-SiN) is easily subject to damage in subsequent step, the problem losing color, then step 204 is performed after depositing described plasma enhancing SiN layer (PE-SiN), in described plasma enhancing SiN layer (PE-SiN) upper deposition low pressure SiN layer 204, to form backboard.

Specifically, as in figure 2 it is shown, in this step, described plasma enhancing SiN layer (PE-SiN) one layer of low pressure SiN layer (LP-SiN) 204 of upper deposition, to protect described plasma enhancing SiN layer (PE-SiN).

Wherein, described low pressure SiN layer (LP-SiN) can select the one in low-pressure chemical vapor deposition (LPCVD), ultralow pressure chemical vapour deposition (CVD) (VLPCVD), or select other deposition process commonly used in the art, it is not limited to a certain.

Alternatively, in order to improve the described low pressure SiN layer (LP-SiN) anti-etching performance in subsequent step, need to make low pressure SiN layer (LP-SiN) have suitable thickness, for instance the thickness of described low pressure SiN layer (LP-SiN) is 100-200nm in the present invention.

Additionally, in order to reduce the damage to low pressure SiN layer (LP-SiN), the depositing temperature of described low pressure SiN layer is 700-800 DEG C.

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

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

In follow-up wet method BOE etching process, the etch-rate of described low pressure SiN layer is far smaller than described plasma enhancing SiN layer (PE-SiN) by described BOE etching, therefore described plasma enhancing SiN layer (PE-SiN) can be formed protection, guarantee that plasma enhancing SiN layer (PE-SiN) is not subjected to damage, and low pressure SiN layer is without removal described in follow-up processing step, can as a part for backboard, not only technique is simple, and process costs can be increased, the phenomenon of color will not be lost simultaneously, improve performance and the yield of MEMS microphone.

Alternatively, owing to being formed with described low pressure SiN layer on described plasma enhancing SiN layer (PE-SiN), therefore can perform annealing steps after described plasma enhancing SiN layer (PE-SiN) deposits, but described annealing steps is not necessarily.

Perform step 205, pattern described backboard, to form some openings in described backboard.

Specifically, first in described low pressure SiN layer 204, form the mask layer of patterning in this step, such as photoresist layer, then with described mask layer for plasma enhancing SiN layer described in mask etch 203 (PE-SiN) and low pressure SiN layer (LP-SiN) 204, to be formed with some openings in described plasma enhancing SiN layer 203 (PE-SiN) and low pressure SiN layer (LP-SiN) 204.

Wherein, described some openings are for removing the sacrificial material layer of described backboard both sides in subsequent steps, to form microphone cavity and back of the body chamber.

Wherein, the spaced setting of described opening, the number of described opening is also not limited to a certain numerical range, it is possible to be configured according to specific needs.

Perform step 206, again sacrificial material layer 202, to cover described backboard and to fill described opening.

Specifically, described sacrificial material layer 202 can select oxide skin(coating), for instance can select plasma enhanced oxidation thing (PE-Ox).

Can further include the step performing planarization after this step, it is possible to select conventional flattening method, do not repeat them here.

Perform step 207, perform MEMS technology, then remove the described sacrificial material layer of described backboard both sides, to form microphone cavity and back of the body chamber.

Specifically, after depositing described sacrificial material layer, it is also possible to comprise other techniques further, for instance be formed over opening at described vibrating diaphragm, in order to accept various vibration signal, but be not limited to this example, do not repeat them here.

After having performed described MEMS technology, remove the described sacrificial material layer of described backboard both sides, to form microphone cavity and back of the body chamber.

In this step, buffered oxide etch agent (BufferedOxideEtchant, BOE) is selected to carry out wet etching, to remove described sacrificial material layer.

Wherein, described BOE is that HF and NH4F mixes according to different proportion. Wherein, HF is main etching solution, and NH4F then uses as buffer agent. Utilize NH4F to fix the concentration of (H+), so as to described sacrificial material layer is kept certain rate of etch, described low pressure SiN layer (LP-SiN) 204 is had relatively low etch-rate simultaneously.

Further, in described BOE, the concentration of HF and NH4F can be adjusted as required, it is not limited to a certain numerical range.

After removing the sacrificial material layer of described backboard both sides, forming MEMS microphone cavity between described vibrating diaphragm and backboard, the opposite side at described backboard forms back of the body chamber, to form MEMS microphone.

So far, the introduction of correlation step prepared by the MEMS microphone of the embodiment of the present invention is completed. After the above step, it is also possible to include other correlation step, repeat no more herein. Further, in addition to the foregoing steps, the preparation method of the present embodiment can also include other steps among each step above-mentioned or between different steps, and these steps all can be realized by various techniques of the prior art, repeats no more herein.

It is an advantage of the current invention that:

(1) SiN layer surface will not suffer damage, and will not lose color.

(3) process costs is low.

Fig. 3 is the preparation technology flow chart of MEMS microphone described in the embodiment of the invention, specifically includes following steps:

Embodiment 2

Present invention also offers a kind of MEMS; described MEMS is prepared by method described in embodiment 1; plasma enhancing SiN layer described in described MEMS is formed low pressure SiN layer; it is formed protection; damage will not be caused in the surface of described backboard; the phenomenon of color will not be lost, improve performance and the yield of MEMS microphone.

Embodiment 3

Present invention also offers a kind of electronic installation, including the MEMS described in embodiment 2. Wherein, semiconductor device is the MEMS described in embodiment 2, or the MEMS that the preparation method according to embodiment 1 obtains.

The electronic installation of the present embodiment, can be mobile phone, panel computer, notebook computer, net book, game machine, television set, VCD, DVD, navigator, photographing unit, video camera, recording pen, any electronic product such as MP3, MP4, PSP or equipment, it is possible to for any intermediate products including described MEMS. The electronic installation of the embodiment of the present invention, owing to employing above-mentioned MEMS, thus has better performance.

The present invention is illustrated already by above-described embodiment, but it is to be understood that, above-described embodiment is only intended to citing and descriptive purpose, and is not intended to limit the invention in described scope of embodiments. In addition it will be appreciated by persons skilled in the art that and the invention is not limited in above-described embodiment, more kinds of variants and modifications can also be made according to the teachings of the present invention, within these variants and modifications all fall within present invention scope required for protection. Protection scope of the present invention is defined by the appended claims and equivalent scope thereof.

Claims

1. a preparation method for MEMS microphone, including:

2. method according to claim 1, it is characterised in that described method may further comprise:

3. method according to claim 1, it is characterised in that in described step S2, the thickness of described low pressure SiN layer is 100-200nm.

4. method according to claim 1, it is characterised in that in described step S2, the depositing temperature of described low pressure SiN layer is 700-800 DEG C.

5. method according to claim 1, it is characterised in that in described step S2, the sedimentation time of described low pressure SiN layer is 30-90min.

6. method according to claim 1, it is characterised in that in described step S2, the deposition pressure of described low pressure SiN layer is less than 1torr.

7. method according to claim 1, it is characterised in that described sacrificial material layer selects plasma enhanced oxidation thing.

8. method according to claim 2, it is characterised in that select buffered oxide etch agent to carry out wet etching in described step S5, to remove described sacrificial material layer.

9. the MEMS microphone prepared based on the described method of one of claim 1 to 8.

10. an electronic installation, including the MEMS microphone one of claim 1-9 Suo Shu.