CN208317008U - A kind of capacitive MEMS microphone with frequency selection function - Google Patents
A kind of capacitive MEMS microphone with frequency selection function Download PDFInfo
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- CN208317008U CN208317008U CN201820763847.9U CN201820763847U CN208317008U CN 208317008 U CN208317008 U CN 208317008U CN 201820763847 U CN201820763847 U CN 201820763847U CN 208317008 U CN208317008 U CN 208317008U
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- polysilicon
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- vibrating diaphragm
- selection function
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Abstract
The utility model relates to a kind of capacitive MEMS microphones with frequency selection function.Existing capacitive MEMS microphone does not have selection or adjusts the pickup frequency range function of microphone.The utility model successively includes silicon substrate, SiO from bottom to top2Etching stop layer, lower polysilicon round loop electrode, SiO2Supporting layer, polysilicon vibrating diaphragm layer.Through silicon substrate, SiO2Etching stop layer and lower polysilicon round loop electrode offer back chamber, run through SiO2Supporting layer offers damping cavity, and the back chamber and damping cavity of connection are stepped cylinder shape.Polysilicon vibrating diaphragm layer is erected in damping cavity；Polysilicon vibrating diaphragm layer is provided with the elastic construction of circular ring shape close to edge placement.The utility model is arranged damping cavity between polysilicon vibrating diaphragm layer and silicon substrate, and when diaphragm oscillations, cavity can generate damping action to vibrating diaphragm, act on according to different damping caused by alternative sounds frequency, realize the frequency selection function of microphone.
Description
Technical field
The utility model belongs to the technical fields such as MEMS and acoustic sensor, and in particular to one kind has frequency choosing
Select the capacitive MEMS microphone of function.
Background technique
Microphone is a kind of miniature acoustic sensor, mainly includes column Electret microphone (ECM) and MEMS wheat
Gram wind (referred to as: MEMS microphone).Relative to traditional column Electret microphone, MEMS microphone has the small, cost including size
Less, the low in energy consumption, advantages such as reliability is high.According to working principle and electrology characteristic, the type of MEMS microphone includes condenser type, pressure
Electric-type and photo-electric etc..Wherein, capacitive MEMS microphone is the market mainstream.
Capacitive MEMS microphone is similar to variable capacitance, and there are two electrodes, i.e. backboard and vibrating diaphragm for tool.Vibrating diaphragm have compared with
Good elasticity, can vibrate under acoustic wave excitation, generate change in displacement, change the spacing of backboard and vibrating diaphragm, to make Mike
The capacitor of wind changes；The circuit of rear end can be by detection capacitance variations to obtain acoustic signal.In general, have and pass
In intermediate working frequency section, (such as 100Hz to 10KHz) is that comparison is flat to the response curve of the capacitive MEMS microphone for structure of uniting
Smooth, and in 100Hz or less low frequency region, sensitivity is lower；In the section 10KHz or more, it may appear that helmholtz resonance peak is deposited
Very strong non-linear.
Microphone with flat frequency response curve can pick up voice signal in very wide frequency range, be suitable for
Different application.However, either in daily life, or in professional domain, in a specific job, need
Frequency range often do not need it is very wide.For example, person to person talks, audible frequency usually at hundred hertz between kHz,
The sound of its frequency does not need to be picked, and also needs specially to filter out after acquisition.Under such application background, frequency selection
It is very important.For practical application, the pickup frequency range selected or adjust microphone is existing capacitive MEMS
The function that microphone does not have.
Summary of the invention
The purpose of this utility model provides a kind of capacitor with frequency selection function aiming at the deficiencies in the prior art
Formula MEMS microphone realizes centre frequency pickup nearby, and filtering low and high-frequency sound on physical layer solve existing capacitor
Formula microphone cannot achieve the problem of frequency selection.
The utility model successively includes silicon substrate, SiO from bottom to top2Etching stop layer, lower polysilicon round loop electrode, SiO2
Supporting layer, polysilicon vibrating diaphragm layer.
Through silicon substrate, SiO2Etching stop layer and lower polysilicon round loop electrode offer columnar back chamber；Through SiO2
Supporting layer offers columnar damping cavity；Chamber and damping cavity coaxial arrangement are carried on the back, the circular cross section diameter for carrying on the back chamber is less than damping
The circular cross section diameter of chamber, the back chamber and damping cavity of connection are stepped cylinder shape.
Circular polysilicon vibrating diaphragm layer is erected in damping cavity；Polysilicon vibrating diaphragm layer is provided with circle close to edge placement
The circumference outer of the elastic construction of annular, elastic construction is corresponding with damping cavity wall.
The elastic construction is made of the multiple groups through slot of circumferential arrangement, increases the upper polycrystalline of elastic construction ring-shaped inner part point
Silicon vibrating diaphragm elasticity.
Further, the silicon substrate with a thickness of 300~500um.
Further, the SiO2Etching stop layer is the SiO with a thickness of 200~1000nm2Film.
Further, the lower polysilicon round loop electrode is the polysilicon membrane with a thickness of 100~500nm.
Further, the SiO2Supporting layer is the SiO with a thickness of 200~1000nm2Film.
Further, the polysilicon vibrating diaphragm layer is the polysilicon membrane with a thickness of 100~500nm.
Further, the through slot is snakelike tank, or the interdigitated slot formed by two pectination slots.
The frequency selection function of microphone mainly passes through the influence realization for adjusting press-filming damping in damping cavity, press-filming damping
Size generally with diaphragm oscillations frequency dependence.For example, when incident acoustic wave frequency is 500Hz, in damping cavity, press-filming damping value is most
It is small, thus in this frequency microphone sensitivity highest.It may be said that can realize the highly sensitive of microphone near the frequency
Degree, and when sound frequency is excessive or too small, the sensitivity of microphone is all significantly reduced.Therefore, by adjusting in damping cavity
Frequency selection function can be realized in the size of press-filming damping.Damping cavity is arranged in the utility model between vibrating diaphragm and substrate, is shaking
When film vibrates, cavity can generate damping action to vibrating diaphragm, act on, realize according to different damping caused by alternative sounds frequency
The frequency selection function of microphone.
Detailed description of the invention
Fig. 1 is the schematic diagram of the section structure of the utility model；
Fig. 2 is the structural schematic diagram of polysilicon vibrating diaphragm in Fig. 1.
Specific embodiment
A kind of capacitive MEMS microphone with frequency selection function, it is shown in Figure 1.
It from bottom to top successively include silicon substrate 1, SiO2Etching stop layer 2, lower polysilicon round loop electrode 3, SiO2Supporting layer 4,
Polysilicon vibrating diaphragm layer 5.Polysilicon vibrating diaphragm layer 5 is for perceiving sound wave and vibration.Wherein, silicon substrate 1 with a thickness of 300~
500um；SiO2Etching stop layer 2 is the SiO with a thickness of 200~1000nm2Film；Lower polysilicon round loop electrode 3 be with a thickness of
The polysilicon membrane of 100~500nm；SiO2Supporting layer 4 is the SiO with a thickness of 200~1000nm2Film；Polysilicon vibrating diaphragm layer
5 be the polysilicon membrane with a thickness of 100~500nm.
Through silicon substrate 1, SiO2Etching stop layer 2 and lower polysilicon round loop electrode 3 offer columnar back chamber 6.It passes through
Wear SiO2Supporting layer 4 offers columnar damping cavity 7.Columnar back chamber 6 and damping cavity 7 are coaxially disposed, and carry on the back the circle of chamber 6
Cross-sectional diameter is less than the circular cross section diameter of damping cavity 7, and the back chamber 6 and damping cavity 7 of connection are stepped cylinder shape.
Circular polysilicon vibrating diaphragm layer 5 is erected in damping cavity 7.The structure of polysilicon vibrating diaphragm layer 5 institute referring to fig. 2
Show.
Polysilicon vibrating diaphragm layer 5 is provided with the elastic construction of circular ring shape, the circumference outer of elastic construction close to edge placement
It is corresponding with 7 inner wall of damping cavity.The elastic construction is made of the multiple groups through slot 8 of circumferential arrangement, which is linear grooves, can be
Snakelike tank, or the interdigitated slot formed by two pectination slots.The setting of elastic construction can increase in elastic construction annular
The elasticity of partial polysilicon vibrating diaphragm, while the effect of venthole can be served as again.
The frequency selection function of microphone mainly passes through the influence realization for adjusting press-filming damping in damping cavity, press-filming damping
Size generally with diaphragm oscillations frequency dependence.When incident acoustic wave frequency is 500Hz, press-filming damping value is minimum in damping cavity, because
The sensitivity highest of this microphone in this frequency.It may be said that the high sensitivity of microphone can be realized near the frequency, and
When sound frequency is excessive or too small, the sensitivity of microphone is all significantly reduced.Therefore, it is hindered by adjusting press mold in damping cavity
Frequency selection function can be realized in the size of Buddhist nun.
The processing step for making the capacitive MEMS microphone is as follows:
Step 1. is existed using chemical vapour deposition technique (CVD), thermal oxidation method or ethyl orthosilicate (TEOS) thermal decomposition method
With a thickness of preparation on 300~500um silicon substrate with a thickness of the SiO of 200~1000nm2Film, the SiO2Film layer is SiO2It carves
Lose stop-layer；
Step 2. is in SiO2It is prepared on etching stop layer using chemical vapour deposition technique (CVD) with a thickness of 100~500nm
Polysilicon membrane, which is lower polysilicon electrode layer；
Step 3. according to the circular ring shape of design channel patterns, using chemical wet etching method (litho-etch) by lower polycrystalline
Silicon electrode layer is cut through, as lower polysilicon round loop electrode；
Step 4. used on lower polysilicon round loop electrode ethyl orthosilicate (TEOS) thermal decomposition method cladding thickness for 200~
The SiO of 1000nm2Film, the SiO2Film layer is SiO2Supporting layer；
Step 5. is in SiO2It is prepared on supporting layer using chemical vapour deposition technique (CVD) with a thickness of the more of 100~500nm
Polycrystal silicon film, the layer polysilicon film are polysilicon vibrating diaphragm layer；
Step 6. uses chemical wet etching method (litho-etch), opens up in polysilicon vibrating diaphragm layer close to edge placement
Through slot, multiple through slot circumferential arrangements, forms the elastic construction of circular ring shape；
Step 7. is by the lower surface of silicon substrate, corresponding lower polysilicon round loop electrode lead to the hole site, using chemical wet etching
Method (litho-etch) cuts through silicon substrate, forms silicon substrate through-hole；
Step 8. is by SiO2The lower surface of etching stop layer starts, and uses gaseous state hydrofluoric acid corrosion technology along silicon substrate through-hole
Or hydrofluoric acid wet etching method is by SiO2Etching stop layer and SiO2Supporting layer is cut through；
Step 9. is downward by the through slot of polysilicon vibrating diaphragm layer circumferential arrangement, using gaseous state hydrofluoric acid corrosion technology or hydrogen fluorine
Sour wet etching method, by SiO2Supporting layer corresponds to the SiO within the scope of the elastic construction of circular ring shape2Thin film corrosive is clean；Silicon substrate
Through-hole, lower polysilicon round loop electrode through-hole, SiO2Etching stop layer through-hole forms back chamber, SiO2Supporting layer through-hole forms damping cavity,
The back chamber and damping cavity of connection are ladder circle tubular.
Wherein, step 2 and 5 adulterates skill using gas using in the deposition process of chemical vapour deposition technique (CVD) in place
Art carries out P elements doping；Etching procedure in chemical wet etching method described in step 7 uses deep reaction ion etching method
(DRIE)。
Claims (7)
1. a kind of capacitive MEMS microphone with frequency selection function, it is characterised in that:
It from bottom to top successively include silicon substrate (1), SiO2Etching stop layer (2), lower polysilicon round loop electrode (3), SiO2Supporting layer
(4), polysilicon vibrating diaphragm layer (5)；
Through silicon substrate (1), SiO2Etching stop layer (2) and lower polysilicon round loop electrode (3) offer columnar back chamber (6)；
Through SiO2Supporting layer (4) offers columnar damping cavity (7)；
Columnar back chamber (6) and damping cavity (7) coaxial arrangement, the circular cross section diameter of back chamber (6) are less than damping cavity (7)
Circular cross section diameter, the back chamber and damping cavity of connection are stepped cylinder shape；
Circular polysilicon vibrating diaphragm layer (5) is erected on damping cavity (7)；
Polysilicon vibrating diaphragm layer (5) is provided with the elastic construction of circular ring shape close to edge placement, the circumference outer of elastic construction with
Damping cavity (7) inner wall is corresponding；
The elastic construction is made of the multiple groups through slot (8) of circumferential arrangement, increases the upper polycrystalline of elastic construction ring-shaped inner part point
Silicon vibrating diaphragm elasticity.
2. a kind of capacitive MEMS microphone with frequency selection function as described in claim 1, it is characterised in that: described
Silicon substrate (1) with a thickness of 300~500um.
3. a kind of capacitive MEMS microphone with frequency selection function as described in claim 1, it is characterised in that: described
SiO2Etching stop layer (2) is the SiO with a thickness of 200~1000nm2Film.
4. a kind of capacitive MEMS microphone with frequency selection function as described in claim 1, it is characterised in that: described
Lower polysilicon round loop electrode (3) be polysilicon membrane with a thickness of 100~500nm.
5. a kind of capacitive MEMS microphone with frequency selection function as described in claim 1, it is characterised in that: described
SiO2Supporting layer (4) is the SiO with a thickness of 200~1000nm2Film.
6. a kind of capacitive MEMS microphone with frequency selection function as described in claim 1, it is characterised in that: described
Polysilicon vibrating diaphragm layer (5) be polysilicon membrane with a thickness of 100~500nm.
7. a kind of capacitive MEMS microphone with frequency selection function as described in claim 1, it is characterised in that: described
Through slot (8) be snakelike tank, or the interdigitated slot formed by two pectination slots.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201820763847.9U CN208317008U (en) | 2018-05-22 | 2018-05-22 | A kind of capacitive MEMS microphone with frequency selection function |
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| CN201820763847.9U CN208317008U (en) | 2018-05-22 | 2018-05-22 | A kind of capacitive MEMS microphone with frequency selection function |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108419193A (en) * | 2018-05-22 | 2018-08-17 | 杭州电子科技大学 | Capacitive MEMS microphone and preparation method thereof with frequency selection function |
| CN109831729A (en) * | 2019-01-30 | 2019-05-31 | 武汉大学 | Compact high sensitivity MEMS capacitive sensor |
-
2018
- 2018-05-22 CN CN201820763847.9U patent/CN208317008U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108419193A (en) * | 2018-05-22 | 2018-08-17 | 杭州电子科技大学 | Capacitive MEMS microphone and preparation method thereof with frequency selection function |
| CN108419193B (en) * | 2018-05-22 | 2024-03-08 | 上饶市经纬自动化科技有限公司 | Capacitive MEMS microphone with frequency selection function and manufacturing method thereof |
| CN109831729A (en) * | 2019-01-30 | 2019-05-31 | 武汉大学 | Compact high sensitivity MEMS capacitive sensor |
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| GR01 | Patent grant | ||
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Granted publication date: 20190101 Termination date: 20210522 |