CN103596110B - A kind of MEMS microphone structure and its manufacturing method - Google Patents
A kind of MEMS microphone structure and its manufacturing method Download PDFInfo
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- CN103596110B CN103596110B CN201310631581.4A CN201310631581A CN103596110B CN 103596110 B CN103596110 B CN 103596110B CN 201310631581 A CN201310631581 A CN 201310631581A CN 103596110 B CN103596110 B CN 103596110B
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Abstract
The invention discloses a kind of MEMS microphone structures, including the substrate with cavity；First medium layer has the through-hole communicated with cavity；Lower electrode layer, including back electrode interconnected and the first lead division, back electrode are located above through-hole；Top electrode structure comprising the vibrating membrane formed by upper electrode layer, the second lead division being connected with vibrating membrane, and the ring-shaped groove filled with a layer insulating；Ring-shaped groove bottom is supported in lower electrode layer and is located at back electrode with exterior domain；Insulating layer extends inwardly to below vibrating membrane from ring-shaped groove inner sidewall upper end level, is suspended on vibrating membrane above back electrode by ring-shaped groove；Air-gap is formed between vibrating membrane and back electrode；And relief hole, it is formed in back electrode, is connected to air-gap and through-hole.The present invention can be avoided back electrode and vibrating membrane and sustain damage or fall off in release process.
Description
Technical field
The present invention relates to technical field of microelectronic mechanical systems, in particular to a kind of MEMS microphone structure and its manufacturer
Method.
Background technique
Microphone is divided into dynamic microphones and Electret Condencer Microphone.Traditional dynamic microphones by coil, vibrating diaphragm and
Permanent magnet group is at it is the faradic principle of movement generation based on coil in magnetic field；And Electret Condencer Microphone is main
Structure is two pieces of capacitor plates, i.e. vibrating membrane (Diaphragm) and back electrode (Backplate), its working principle is acoustic pressure
The deformation for causing vibrating membrane, causes capacitance to change, to be converted to electric signal output.
MEMS microphone is one of most successful MEMS product so far.MEMS microphone is by simultaneous with IC manufacturing
The surface of appearance processes or the microphone of Bulk micro machining manufacture, due to can use persistently miniature CMOS technology technology,
MEMS microphone can be made very small, it is allowed to be widely applied to mobile phone, laptop, tablet computer and video camera
In equal portable equipments.
MEMS microphone is usually capacitive, and wherein back electrode (lower electrode) is supported on substrate by dielectric layer, with
The cavity of substrate is opposite, and vibrating membrane (top electrode) is then hanging to be arranged above back electrode, provides support by silica and silicon nitride.
It is air-gap between vibrating membrane and back electrode.A problem existing for this mode be when carry out release process removal vibrating membrane with
When dielectric layer between back electrode and between back electrode and substrate is to form air-gap, need to be subject to sternly the release process time
Lattice control, if process time too long can completely remove the dielectric layer below back electrode causes falling off for back electrode.
Summary of the invention
The purpose of the present invention is to provide a kind of MEMS microphone structure and its manufacturing methods, and release process can be made automatic
Stop, will not because the process time it is too long caused by back electrode or vibrating membrane damage or fall off.
To reach above-mentioned purpose, the present invention provides a kind of MEMS microphone structure, comprising: substrate, with cavity；First
Dielectric layer is formed in the upper surface of substrate, has the through-hole communicated with the cavity；Lower electrode layer, at least partly with it is described
The upper surface of first medium layer contacts, and the lower electrode layer includes back electrode interconnected and the first lead division, the back electricity
Pole is located at the top of the through-hole；Top electrode structure comprising vibrating membrane, the second lead division being connected with the vibrating membrane and
Ring-shaped groove filled with a layer insulating；Second lead division is two parts by ring-shaped groove partition；The insulation
Layer extends inwardly to below the vibrating membrane from ring-shaped groove inner sidewall upper end level, is suspended on the vibrating membrane described
Above back electrode；Wherein the vibrating membrane, the second lead division are formed by upper electrode layer；The ring-shaped groove includes interconnecting piece, institute
Upper electrode layer is stated to be deposited on the insulating layer of the interconnecting piece so that two parts of second lead division are connected；The annular ditch
The insulation layer supports of trench bottom on the lower electrode layer and be located at the back electrode with exterior domain；Wherein, the back electrode is
Gear shape comprising circular body portion and extend outwardly from the circular body portion and in the equally distributed multiple teeth in its edge
Portion；The vibrating membrane is circle, shape of the insulating layer from the part that ring-shaped groove inner sidewall upper end level extends internally
Shape is corresponding with the multiple teeth portion；Air-gap is formed between the vibrating membrane and the back electrode；And relief hole, shape
In the circular body portion of back electrode described in Cheng Yu, it is connected to the air-gap and the through-hole.
Optionally, the arc length of the interconnecting piece is less than or equal to 1/10th of the ring-shaped groove perimeter.
Optionally, the upper electrode layer be filled in the ring-shaped groove except the interconnecting piece with outer portion, and not with institute
Vibrating membrane is stated to be connected.
Optionally, it is higher than between the insulating layer and upper electrode layer of the interconnecting piece filled with one layer of etching selection ratio described exhausted
The third dielectric layer of edge layer.
Optionally, cross sectional shape of the ring-shaped groove in the direction perpendicular to the upper surface of substrate is rectangle or the ladder that falls
Shape, the ratio between depth and bottom opening width are more than or equal to 5:1.
The present invention also provides a kind of manufacturing methods of above-mentioned MEMS microphone structure, comprising the following steps: on substrate
Sequentially form first medium layer, patterned lower electrode layer and second dielectric layer；The lower electrode layer is defined to be released with multiple
The back electrode of discharge hole and the first lead division being connected with the back electrode；The back electrode is gear shape comprising round
Main part and extend outwardly from the circular body portion and in the equally distributed multiple teeth portion in its edge；Other than the back electrode
Second dielectric layer described in the chemical wet etching of region is to form the ring-shaped groove that bottom extends to the lower electrode layer, the ring-shaped groove
With interconnecting piece；In one layer of insulating materials of above structure disposed thereon and graphically to remove the part institute above the back electrode
Insulating materials is stated, be filled in the ring-shaped groove with being formed and is extended internally from ring-shaped groove inner sidewall upper end level
Insulating layer；Wherein the insulating layer is from the shape of the part that ring-shaped groove inner sidewall upper end level extends internally and described more
A teeth portion is corresponding；Upper electrode layer and graphical is deposited on above structure, with formed circular vibrating membrane and with the vibration
The second connected lead division of film, wherein the vibrating membrane is located within the ring-shaped groove inner sidewall and bottom margin covers at least
For the part insulating layer from the part that ring-shaped groove inner sidewall upper end level extends internally, second lead division is described
Ring-shaped groove is divided into two parts, and the upper electrode layer is covered on the insulating layer of the interconnecting piece of the ring-shaped groove so that described
Two parts of second lead division are connected；Form top electrode electrical connection and the electrical connection of lower electrode；Form the chamber for running through the substrate
Body, the cavity top are located at the back electrode with the lower section of inner region；And release process is carried out by the relief hole, it goes
Except the first medium layer and second dielectric layer above the cavity, make to be formed between the back electrode and the vibrating membrane empty
Air gap.
Optionally, the arc length of the interconnecting piece is less than or equal to 1/10th of the ring-shaped groove perimeter.
Optionally, it is one layer that the upper electrode layer deposits in the ring-shaped groove, and is located at other than the interconnecting piece
The upper electrode layer is not connected with the vibrating membrane.
Optionally, it is filled in the ring-shaped groove in formation and prolongs out of the ring-shaped groove inner sidewall upper end horizontal direction
After the step of insulating layer stretched, it is higher than the third dielectric layer of the insulating layer in one layer of etching selection ratio of above structure disposed thereon
And remove the third dielectric layer other than the interconnecting piece of the ring-shaped groove.
Optionally, cross sectional shape of the ring-shaped groove in the direction perpendicular to the upper surface of substrate is rectangle or the ladder that falls
Shape, the ratio between depth and bottom opening width are more than or equal to 5:1.
The advantage of the invention is that keeping the release process to form air-gap automatic by the ring-shaped groove filled with insulating layer
Ring-shaped groove inner sidewall is stopped at, to avoid the defect for causing back electrode to fall off because of release process overlong time；And by only
Connect vibrating membrane and backboard in the interconnecting piece of ring-shaped groove, can reduce MEMS microphone vibrating membrane with exterior domain upper/lower electrode it
Between capacitor.It is associated in addition, top electrode/stress between lower electrode and silicon wafer can be isolated by insulating layer；Simultaneously by exhausted
The part connection vibrating membrane of edge layer dentation can be further improved the sensitivity of MEMS microphone.
Detailed description of the invention
Fig. 1 is the cross-sectional view of the MEMS microphone structure of one embodiment of the invention；
Fig. 2 a and Fig. 2 b are the top electrode structure of MEMS microphone structure shown in FIG. 1 and the top view of back electrode；
Fig. 3 is the schematic diagram of the interconnecting piece of the MEMS microphone structure ring-shaped groove of another embodiment of the present invention；
Fig. 4 a and Fig. 4 b are respectively the fragmentary sectional view of the MEMS microphone structure ring-shaped groove of another embodiment of the present invention；
Fig. 5 to Figure 12 is the cross-sectional view of MEMS microphone structure manufacturing method of the present invention.
Specific embodiment
To keep the contents of the present invention more clear and easy to understand, below in conjunction with Figure of description, the contents of the present invention are made into one
Walk explanation.Certainly the invention is not limited to the specific embodiment, general replacement known to those skilled in the art
It is included within the scope of protection of the present invention.
Firstly, the MEMS microphone structure to one embodiment of the invention is illustrated.As shown in Figure 1, MEMS microphone knot
Structure includes semiconductor substrate 101, first medium layer 102, lower electrode layer 103 and top electrode structure.Wherein, it is formed in substrate
Cavity 110, shape can be cylindrical or cone.First medium layer 102 is formed in 101 upper surface of semiconductor substrate, tool
There is the through-hole being connected to cavity 110.Lower electrode layer 103 includes back electrode 103a interconnected and the first lead division 103b, on
Electrode structure include vibrating membrane 106a, the closed ring-shaped groove 105 filled with a layer insulating 104 and with vibrating membrane 106a phase
The second lead division 106b even.
Referring to FIG. 1, back electrode 103a is drawn by the first lead division 103b.Wherein back electrode 103a is located on through-hole
Side, the first lead division 103b are contacted with the upper surface of first medium layer 102.As shown in Fig. 2 b, back electrode 103a is gear shape
Shape extends outwardly with circular body portion and from circular body portion and in the equally distributed multiple teeth portion in its edge；First
Lead division 103b then can be rectangle.Air-gap is formed for carrying out release process in addition, having in the circular body portion of back electrode
Multiple relief holes (not showing in Fig. 2 b).The material of lower electrode layer is, for example, conductive material, such as Al, W, Cu metal, or is mixed
Miscellaneous polysilicon or amorphous silicon.102 material of first medium layer is, for example, the silica of hot oxide growth, plasma enhanced chemical gas
Mutually the non-impurity-doped silica (USG) of deposition (PECVD) method deposition, the silica (PSG) of p-doped or the silica mixed with boron phosphorus
(BPSG).
Vibrating membrane 106a is drawn by the second lead division 106b, and vibrating membrane 106a and the second lead division 106b are by powering on
Pole layer 106 is formed.As shown in Figure 2 a, vibrating membrane 104a be circle, a small amount of stomata (not shown) is generally also distributed with, for
The external world carries out gas exchanges.The insulating layer 104 of the bottom of ring-shaped groove 105 is supported on lower electrode layer 103, ring-shaped groove 105
Internal diameter is greater than the diameter of back electrode 103a, therefore ring-shaped groove 105 is to be located at back electrode 103a with exterior domain.Second lead division
106b is divided into two parts by ring-shaped groove.Ring-shaped groove 105 includes interconnecting piece 105a, and upper electrode layer 106 is filled in the company
The two parts of socket part to connect the second lead division 106b, so as to draw vibrating membrane 106a.The insulation of ring-shaped groove 105
The lower section that layer 104 extends inwardly to vibrating membrane 106a from 105 inner sidewall upper end level of ring-shaped groove, enables vibrating membrane 106a
It is suspended on above back electrode 103a by ring-shaped groove 105, as shown, insulating layer 104 is from 105 inner sidewall upper end of ring-shaped groove
The shape for the part that level extends internally is corresponding with the shape of back electrode teeth portion.In this way, vibrating membrane 106a and back electrode can be made
Air-gap 111, the relief hole of air-gap 111 and back electrode 103a and the through-hole phase of first medium layer 102 are formed between 103a
It is logical.By being connected to vibrating membrane 106a with insulating layer part corresponding with the shape of back electrode teeth portion, when vibrating membrane occurs
When vibration, Round Membranes will translationally be vibrated, without whole in bowl-shape earthquake motion.
Preferably, vibrating membrane adheres to (when such as wet process discharges) with back electrode in wet environment in order to prevent, in vibrating membrane
106a also has multiple bulge-structures towards the side of back electrode 103a, these bulge-structures are coated by insulating dielectric materials,
Depth is, for example, 0.3 micron to 1 micron.Wherein, the material of the insulating layer 104 of ring-shaped groove 105 can be silicon nitride or other are exhausted
Edge material, the insulating dielectric materials for coating bulge-structure can be identical as 104 material of insulating layer.The material of upper electrode layer 106 can be
The metals such as conductive material such as Al, W, Cu, or the polysilicon membrane or amorphous silicon membrane of doping.
With continued reference to FIG. 1, in the present embodiment, upper electrode layer 106 is filled on the insulating layer 104 of ring-shaped groove 105
It is one layer, but in addition to interconnecting piece 105a is not connected with outer portion with vibrating membrane 106a, thus can prevents vibrating membrane 106a connection
Capacitor is formed between the lower electrode layer other than back electrode 103a into ring-shaped groove.Preferably, the arc length of interconnecting piece 105a accounts for
The ratio of 105 perimeter of entire ring-shaped groove, which should control, is being less than or equal to 10%.Be filled in ring-shaped groove 105 not with vibrating membrane
106a connected upper electrode layer can further strengthen the supporting role of ring-shaped groove.
Further, since at the interconnecting piece of ring-shaped groove 105, it is only exhausted every one layer between top electrode structure and lower electrode layer
Edge layer is easy to produce overlap capacitance, for the capacitor being reduced as far as between the upper electrode layer and lower electrode layer in interconnecting piece, compared with
Good, another etch compared to insulating layer with height can be filled between the upper electrode layer and insulating layer of ring-shaped groove interconnecting piece to be selected
The third dielectric layer for selecting ratio, as shown in Fig. 3.The third dielectric layer can be non-impurity-doped silica (USG), the silica of p-doped
(PSG) or mixed with boron phosphorus silica (BPSG).It certainly, in other embodiments can also be by the way that ring-shaped groove be set as zanjon
Slot leads to the problem of overlap capacitance to improve ring-shaped groove interconnecting piece upper/lower electrode.Please refer to Fig. 4 a, ring-shaped groove perpendicular to
The cross sectional shape in upper surface of substrate direction is rectangle, and the width of rectangle will be far smaller than length, the length of its preferable section rectangle
Width is than being that thus can occur to seal phenomenon when insulating layer inserts ring-shaped groove more than or equal to 5:1, so that deposition is on the insulating layer
Upper electrode layer in ring-shaped groove there is no fill, can so reduce overlap capacitance.It refer again to Fig. 4 b, due to sealing phenomenon
Cavity may be generated in ring-shaped groove, for the generation for avoiding cavity, ring-shaped groove cross sectional shape can be set as inverted trapezoidal,
Bottom width is far smaller than trench depth, preferably, the ratio between trench depth and bottom width be more than or equal to 5:1, thus when after
When continuous depositing insulating layer, insulating layer will can also comparatively fast fill up in ring-shaped groove, with increase at interconnecting piece 105a upper/lower electrode it
Between distance, play similar effect.
It, can be directly in the first lead division 103b and the second lead division when upper electrode layer and lower electrode layer are metal material
106b forms electrical connection.Wherein, it for the first lead division 103b, can be formed in 105 lateral wall of ring-shaped groove with exterior domain
Bottom extends to the contact hole of the first lead division 103b, thus the first lead division 103b of exposure.If upper electrode layer and lower electrode layer
It, then as shown in Figure 1, can be in contact hole bottom formation lower metal electrode liner 108, second for the polysilicon or amorphous silicon of doping
Electrode of metal liner 109 is formed on lead division 106b, to form electrical connection.
In conclusion the present invention utilizes ring-shaped groove, the release process can be automatic when forming air-gap using release process
It stops inside ring-shaped groove, the process time is longer to cause back electrode to fall off；Furthermore by being deposited on ring-shaped groove
Insulating layer vibrating membrane is isolated with back electrode, upper/lower electrode will not be shorted, and top electrode/lower electrode and silicon wafer can more be isolated
Between stress association, be connected with vibrating membrane furthermore with insulating layer so that vibrating membrane translates shakes, MEMS Mike also can be improved
The sensitivity of wind.
The manufacturing method of MEMS microphone structure of the invention is carried out specifically below in conjunction with specific embodiments
It is bright.Technical solution in order to better illustrate the present invention please refers to Fig. 5 to Figure 12 as MEMS microphone structure of the present invention manufacture
Method cross-sectional view.
Firstly, referring to FIG. 5, sequentially form first medium layer 102 in semiconductor substrate 101, patterned lower electrode
Layer and second dielectric layer 102 '.Specifically, first medium layer 102 is deposited first.The material of substrate 101 can be silicon, germanium or
Germanium silicon.First medium layer 102 can be silica, plasma enhanced chemical vapor deposition (PECVD) method of hot oxide growth
The non-impurity-doped silica (USG) of deposition, the silica (PSG) of p-doped or the silica (BPSG) mixed with boron phosphorus.Then first
Lower electrode layer 103 is deposited on dielectric layer 102 and graphically to form connected back electrode 103a and the first lead division 103b.Back electricity
Pole 103a is gear shape, is extended outwardly with circular body portion and from circular body portion and equally distributed at its edge
Multiple teeth portion, the first lead division 103b can be rectangle.Multiple releases for subsequent release process are formed in back electrode 103a
Hole.Lower electrode layer material can be the conductive material of the metals such as Al, W, Cu, or the polysilicon or amorphous silicon material of doping.It
Afterwards, second dielectric layer 102 ' is deposited on patterned lower electrode layer 103 and first medium layer 102.Second dielectric layer 102 ' is made
For the sacrificial layer material between MEMS microphone structure vibrating membrane and back electrode, thickness may be defined as final products vibrating membrane and
The height of air-gap between back electrode.Second dielectric layer 102 ' equally can be silica, the plasma enhancing of hot oxide growth
Chemical vapor deposition (pecvd) method deposition non-impurity-doped silica (USG), p-doped silica (PSG) or mixed with boron phosphorus
Silica (BPSG).
Then, referring to FIG. 6, in lower electrode layer to etch closed ring-shaped groove in the dielectric layer 102 ' of exterior domain
105.105 inner sidewall area encompassed of ring-shaped groove is used as the vibration diaphragm area of MEMS microphone structure, and outside ring-shaped groove
Region other than side wall is then used to form MEMS microphone structure vibrating membrane lead-out area.Wherein, the bottom of ring-shaped groove 105 is prolonged
Extend to lower electrode layer 103.Preferably, as shown in fig. 6, depth can also be etched in the second dielectric layer 102 ' in vibration diaphragm area
Degree be 0.3um~1um(be no more than second dielectric layer 102 ' thickness) equally distributed square hole or circular hole, then can be in side
Silicon nitride or other insulating dielectric materials are filled in hole or circular hole, to prevent the upper electrode layer deposited thereafter in wet environment
(when such as wet process discharges) top electrode vibrating membrane is sticked together with back electrode.
With continued reference to FIG. 7, depositing one layer of insulating materials and graphical, removal back electrode in the structure being previously formed
Portions of insulating material above 103a is filled in ring-shaped groove 105 and to be formed from 105 inner sidewall upper end water of ring-shaped groove
The flat insulating layer 104 to extend internally.Wherein, insulating layer from the part that 105 inner sidewall upper end level of ring-shaped groove extends internally with
The teeth portion of back electrode is corresponding, is similarly dentation.Optionally, as shown in fig. 7, insulating layer 104 is filled in second dielectric layer simultaneously
In the square hole or circular hole etched on 102 ', to prevent the upper electrode layer deposited thereafter in wet environment (when such as wet process discharges)
Vibrating membrane is sticked together with back electrode.
Then, referring to FIG. 8, depositing upper electrode layer 106 in the structure being previously formed.The material of upper electrode layer 106 can
To be the metals such as Al, W, Cu, or the polysilicon or amorphous silicon material of doping.
Later as shown in figure 9, graphical upper electrode layer 106, to form vibrating membrane 106a and the second lead division 106b, wherein
Vibrating membrane 106a is to be located at 105 inner sidewall of ring-shaped groove with inner region, and shape can be circle, and bottom margin covers at least partly
Insulating layer 104 from the part that 105 inner sidewall upper end level of ring-shaped groove extends internally.Due to the part insulating layer 104 with
The teeth portion of back electrode is corresponding, is in equally dentation, vibrating membrane 106a is connected to by the partial insulative layer of dentation, works as vibration
Film will translationally vibrate when vibrating, without whole in bowl-shape earthquake motion.Second lead division 106b and vibrating membrane 106a phase
Even, two parts are divided by ring-shaped groove.Ring-shaped groove 105 has for connecting the second lead division 106b by separation two parts
Interconnecting piece 105a, be filled in the interconnecting piece upper electrode layer make the second lead division 106b two parts be connected, thus can will shake
Dynamic film 106a leads to the draw-out area other than ring-shaped groove lateral wall.Preferably, in the ring-shaped groove being located at other than the interconnecting piece
Upper electrode layer 105 be not connected with vibrating membrane 105a, thus can prevent vibrating membrane 105a be connected in ring-shaped groove and with back electricity
Capacitor is formed between lower electrode layer other than the 103a of pole, while these upper electrode layers not being connected with vibrating membrane 106a can further add
The supporting role of strong ring-shaped groove.The ratio that the arc length of preferable interconnecting piece accounts for entire ring-shaped groove perimeter, which should control, to be less than
Equal to 10%.In addition, for the capacitor between the upper electrode layer and lower electrode layer that are reduced as far as in interconnecting piece 105a, in this hair
In a bright preferred embodiment, another compare can be first deposited after patterned insulator layer 104, before deposition upper electrode layer 106
After the third dielectric layer that insulating layer 104 has high etching selection ratio, then remove in addition to ring-shaped groove interconnecting piece 105a is with outside
Point third dielectric layer, which can be non-impurity-doped silica (USG), the silica (PSG) of p-doped or mixed with boron phosphorus
Silica (BPSG).Since third dielectric layer is only filled between the upper/lower electrode layer in groove interconnecting piece 105a, increase
The distance between upper/lower electrode layer, the problem of overlap capacitance between upper electrode layer and lower electrode layer can be improved.Certainly, of the invention
In other preferred embodiments, it can also be improved by the control to ring-shaped groove depth-to-width ratio in interconnecting piece and be overlapped between upper/lower electrode
The problem of capacitor.Specifically, it when etching ring-shaped groove 105, is etched perpendicular to the cross sectional shape in upper surface of substrate direction
To be far smaller than length for the width of rectangle, and rectangle, more than or equal to 5:1, thus the length-width ratio of its preferable section rectangle is
It can occur to seal phenomenon in ring-shaped groove 105 when subsequent deposition insulating layer 104, then being deposited on insulating layer 104 later
Upper electrode layer 106 can not be just filled in ring-shaped groove, and the distance between upper/lower electrode layer is increased, and can so be reduced overlapping
Capacitor.Further, it is contemplated that sealing phenomenon may generate cavity in ring-shaped groove, for the generation for avoiding cavity, may be used also
Ring-shaped groove cross sectional shape is etched as inverted trapezoidal, bottom width is far smaller than trench depth, preferably, trench depth and bottom
The ratio between portion's width is more than or equal to 5:1, and thus when subsequent deposition insulating layer 104, insulating layer 104 can also be in ring-shaped groove 105
It is interior comparatively fast to fill up, to increase the distance between upper/lower electrode in interconnecting piece 105a, play similar effect.
Then, referring to FIG. 10, forming the contact hole for extending to lower electrode layer with exterior domain in ring-shaped groove lateral wall
107, to expose the first lead division 103b.In the present embodiment, upper/lower electrode layer is polysilicon or amorphous silicon material, then
Lower electrode metal liner 108 and upper electrode metal are respectively formed on the first lead division 103b and the second lead division 105b later
Liner 109, to be electrically connected, as shown in figure 11.Certainly, in other embodiments, metal material can be used in upper/lower electrode layer
Material, then the first lead division 103b and the second lead division 105b can be directly as liner, without additionally using metal film or metal
Line is drawn, and process complexity can be reduced.
Figure 12 is please referred to again, the back side of substrate 101 is patterned, to form the cavity 110 for running through substrate.It is specific next
It says, one layer of protection materials being easily removed is coated first above above structure, the front protecting of completed structure is got up,
Go out cavity 110 in the region etch that the back side of substrate 101 corresponds to back electrode later, removes protection materials later.Wherein etch chamber
The step of body include by substrate back upward；It overleaf coats photoresist and carries out exposure and imaging；Use deep silicon etching equipment
It performs etching, so that the silicon of substrate exposure position is removed completely；Remove photoresist etc..Cavity 110 is cylindrical or cone
Cavity, top should be located at back electrode 103a area inside lower section.Protection materials can be photoresist or blue film (blue
Tape) etc..
Finally, being discharged by relief hole with the release process such as wet corrosion technique or gaseous corrosion technique, by cavity
The first medium layer 102 and second dielectric layer 102 ' of top remove.Wet etching medical fluid for release be, for example, HF solution or
The mixed solution BOE of hydrogen fluoride HF and ammonium fluoride NH4F.In this way, form air between vibrating membrane 106a and back electrode 103a
Gap 111, to ultimately form MEMS microphone structure as shown in Figure 1.
As a result, by being filled with the ring-shaped groove 105 of insulating layer 104, release when forming air-gap using release process
Technique can be automatically stopped in ring-shaped groove inner sidewall, even if the process time is too long, upper/lower electrode can also consolidate support and will not
It is shorted.
In conclusion compared with prior art, not only manufacturing process is simple for MEMS microphone structure provided by the present invention,
And can effective protection top electrode main part and back electrode it is without damage in release process or fall off, furthermore by being filled in ditch
The insulating layer of slot can be isolated top electrode/stress between lower electrode and silicon wafer and be associated with, and insulating layer is connected more with vibrating membrane can be improved
The sensitivity of MEMS microphone.
Although the present invention is disclosed as above with preferred embodiment, right many embodiments are illustrated only for the purposes of explanation
, it is not intended to limit the invention, those skilled in the art can make without departing from the spirit and scope of the present invention
Several changes and retouches, and the protection scope that the present invention is advocated should be subject to described in claims.
Claims (9)
1. a kind of MEMS microphone structure characterized by comprising
Substrate, with cavity；
First medium layer is formed in the upper surface of substrate, has the through-hole communicated with the cavity；
Lower electrode layer is at least partly contacted with the upper surface of the first medium layer, and the lower electrode layer includes interconnected
Back electrode and the first lead division, the back electrode are located at the top of the through-hole；
Top electrode structure comprising vibrating membrane, the second lead division being connected with the vibrating membrane and be filled with a layer insulating
Ring-shaped groove；Second lead division is two parts by ring-shaped groove partition；The insulating layer is from the ring-shaped groove
Inner sidewall upper end level extends inwardly to below the vibrating membrane, is suspended on the vibrating membrane above the back electrode；Wherein
The vibrating membrane, the second lead division are formed by upper electrode layer；The ring-shaped groove includes interconnecting piece, and the upper electrode layer is deposited on
So that two parts of second lead division are connected on the insulating layer of the interconnecting piece；The insulating layer branch of the ring-shaped groove bottom
Support on the lower electrode layer and be located at the back electrode with exterior domain；Wherein, the back electrode is gear shape comprising circle
Shape main part and extend outwardly from the circular body portion and in the equally distributed multiple teeth portion in its edge；The vibrating membrane is circle
Shape, shape and the multiple teeth portion phase of the insulating layer from the part that ring-shaped groove inner sidewall upper end level extends internally
It is corresponding；
Air-gap is formed between the vibrating membrane and the back electrode；And
Relief hole is formed in the circular body portion of the back electrode, is connected to the air-gap and the through-hole；
Wherein it is higher than the insulating layer filled with one layer of etching selection ratio between the insulating layer and upper electrode layer of the interconnecting piece
The ratio between the depth of third dielectric layer or the ring-shaped groove and bottom opening width are more than or equal to 5:1.
2. MEMS microphone structure as described in claim 1, which is characterized in that the arc length of the interconnecting piece is less than or equal to described
/ 10th of ring-shaped groove perimeter.
3. MEMS microphone structure as described in claim 1, which is characterized in that the upper electrode layer is filled in the annular ditch
Except the interconnecting piece is with outer portion in slot, and it is not connected with the vibrating membrane.
4. MEMS microphone structure as described in claim 1, which is characterized in that the depth and bottom opening of the ring-shaped groove
The ratio between width is more than or equal to 5:1, and cross sectional shape of the ring-shaped groove in the direction perpendicular to the upper surface of substrate is square
Shape or inverted trapezoidal.
5. a kind of manufacturing method of MEMS microphone structure, which comprises the following steps:
First medium layer, patterned lower electrode layer and second dielectric layer are sequentially formed on substrate；The lower electrode layer definition
The first lead division providing the back electrode of multiple relief holes and being connected with the back electrode；The back electrode is gear shape
Shape comprising circular body portion and extend outwardly from the circular body portion and in the equally distributed multiple teeth portion in its edge；
Second dielectric layer described in the chemical wet etching of region extends to the lower electrode layer to form bottom other than the back electrode
Ring-shaped groove, the ring-shaped groove have interconnecting piece；
In one layer of insulating materials of above structure disposed thereon and graphically to remove the part insulation above the back electrode
Material, to form the insulation for being filled in the ring-shaped groove and extending internally from ring-shaped groove inner sidewall upper end level
Layer；Wherein shape and the multiple tooth of the insulating layer from the part that ring-shaped groove inner sidewall upper end level extends internally
Portion is corresponding；
Upper electrode layer and graphical is deposited on above structure, with form circular vibrating membrane and be connected with the vibrating membrane the
Two lead divisions, wherein the vibrating membrane is located within the ring-shaped groove inner sidewall and bottom margin covering is at least partly described exhausted
Edge layer is from the part that ring-shaped groove inner sidewall upper end level extends internally, and second lead division is by the ring-shaped groove point
Two parts are divided into, the upper electrode layer is covered on the insulating layer of the interconnecting piece of the ring-shaped groove so that second lead division
Two parts be connected；
Form top electrode electrical connection and the electrical connection of lower electrode；
The cavity for running through the substrate is formed, the back electrode is located at the top of the cavity with the lower section of inner region；And
Release process is carried out by the relief hole, removes the first medium layer and the second dielectric layer above the cavity,
Make to form air-gap between the back electrode and the vibrating membrane.
6. the manufacturing method of MEMS microphone structure as claimed in claim 5, which is characterized in that the arc length of the interconnecting piece is small
In equal to 1/10th of the ring-shaped groove perimeter.
7. the manufacturing method of MEMS microphone structure as claimed in claim 5, which is characterized in that the upper electrode layer is described
Deposit is one layer in ring-shaped groove, and the upper electrode layer being located at other than the interconnecting piece is not connected with the vibrating membrane.
8. the manufacturing method of MEMS microphone structure as claimed in claim 5, which is characterized in that be filled in the ring in formation
After the step of in shape groove and from the insulating layer that ring-shaped groove inner sidewall upper end level extends internally, above above structure
One layer of etching selection ratio is deposited to be higher than the third dielectric layer of the insulating layer and remove other than the interconnecting piece of the ring-shaped groove
The third dielectric layer.
9. the manufacturing method of MEMS microphone structure as claimed in claim 5, which is characterized in that the ring-shaped groove is vertical
In the direction of the upper surface of substrate cross sectional shape be rectangle or inverted trapezoidal, the ratio between depth and bottom opening width for greater than
Equal to 5:1.
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| CN104980858B (en) * | 2014-04-02 | 2019-03-29 | 中芯国际集成电路制造(上海)有限公司 | The forming method of MEMS microphone |
| CN107786929B (en) * | 2016-08-26 | 2023-12-26 | 华景科技无锡有限公司 | silicon microphone |
| DE102017102190B4 (en) * | 2017-02-03 | 2020-06-04 | Infineon Technologies Ag | Membrane components and method for forming a membrane component |
| CN108100988A (en) * | 2017-12-19 | 2018-06-01 | 苏州工业园区纳米产业技术研究院有限公司 | Silicon chip carries on the back chamber lithographic method and silicon wafer devices |
| CN112637748B (en) * | 2020-12-22 | 2022-04-26 | 上海交通大学 | Piezoelectric MEMS loudspeaker with double annular surrounding circular vibrating membrane and preparation method |
| CN113613151B (en) * | 2021-07-30 | 2023-08-04 | 歌尔微电子股份有限公司 | Micro-electromechanical system microphone, microphone unit and electronic equipment |
| CN117376759B (en) * | 2023-12-07 | 2024-02-02 | 苏州敏芯微电子技术股份有限公司 | Microphone assembly and microphone |
| CN117641215B (en) * | 2024-01-25 | 2024-04-16 | 镭友芯科技(苏州)有限公司 | Microphone sensor and preparation method thereof |
| CN117915251B (en) * | 2024-03-19 | 2024-06-18 | 苏州敏芯微电子技术股份有限公司 | Acoustic-electric conversion structure, manufacturing method thereof and microphone |
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