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CN105181217B - MEMS pressure sensor and its manufacturing method - Google Patents

MEMS pressure sensor and its manufacturing method Download PDF

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Publication number
CN105181217B
CN105181217B CN201510221463.5A CN201510221463A CN105181217B CN 105181217 B CN105181217 B CN 105181217B CN 201510221463 A CN201510221463 A CN 201510221463A CN 105181217 B CN105181217 B CN 105181217B
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varistor
back side
sensitive film
pressure sensitive
pressure
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CN105181217A (en
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谢勇
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Suzhou Man Pulasi Sensing Science And Technology Ltd
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Suzhou Man Pulasi Sensing Science And Technology Ltd
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Abstract

A kind of MEMS pressure sensor and its manufacturing method, including a pressure sensitive film, at least four front varistors and at least four back side varistors, the wherein described pressure sensitive film has a front and a back side, the front and back of the pressure sensitive film is respectively arranged on per the front varistor and per the back side varistor, an at least Wheatstone bridge is formed after electrical connection, resistance value changing in the opposite direction with pressure set on the front and the varistor of the back side opposite position, to offset the error generated due to process conditions and/or extraneous factor between each varistor, improve the stability and precision of the MEMS pressure sensor output.

Description

MEMS pressure sensor and its manufacturing method
Technical field
The present invention relates to the field microelectromechanical systems (Micro-Electro-Mechanical Systems, MEMS), More particularly to a kind of MEMS pressure sensor and its manufacturing method.
Background technology
MEMS pressure sensor is a kind of thin-film component, suitable for being used for sensing pressure, has small, light-weight, precision Height, high sensitivity, advantage at low cost, traditional sensor has been replaced in many fields.With the quick hair of microelectric technique Exhibition, will be used wider and wider for MEMS pressure sensor is general, be now widely used in automotive system measure gasbag pressure, Fuel pressure, engine oil pressure, admission line pressure and tire pressure etc., can also be applied to medical market and other The pressure measurement of industrial circle.
Currently, the MEMS pressure sensor of mainstream is based on varistor principle, when to act on silicon pressure-sensitive for external pressure When diaphragm, silicon materials lattice compression and stretching can be caused, and then the resistance value of varistor can occur to reduce and increased variation.One As for, varistor is produced on the upper surface of pressure sensitive film, and Figure 1A show MEMS piezo-resistive pressure sensors The schematic diagram of traditional structure, including a pressure sensitive film 1, four varistors 2, multiple connecting keys 3 and a substrate 4, wherein described Varistor 2 is set to the front of the pressure sensitive film 1 and forms a Wheatstone bridge, to sense pressure, the presser sensor Film 1 is connected with the substrate 4, so that the substrate 4 is able to that the pressure sensitive film 1, the connecting key 3 is supported also to be set to On the pressure sensitive film 1, in order to which the MEMS pressure sensor is connected to other circuits, pressure is used for after being suitably packaged Detection.
It needs to consider that a more problem is its sensibility to temperature and pressure in MEMS device, for pressure-sensitive Resistance-type MEMS pressure sensor will especially consider this problem, and therefore, MEMS pressure sensor still remains some problems And defect, this is because in traditional structure, the resistance value of four resistance is equal, and the piezoresistance coefficient of adjacent resistor is on the contrary, face Two resistance piezoresistance coefficients it is identical, but be typically due to the limitation of fabrication error or the disturbing factor in the external world, four resistance it is quiet State value will not exactly match, and four resistance is caused to be not completely equivalent, and Wheatstone bridge is uneven.Therefore, in MEMS pressure sensings During device works, with the variation of temperature, the unequal resistance variation with temperature amount of resistance value differs, and as a result will make It changes at the absolute standard of pressure sensor.In addition, four varistors of Wheatstone bridge are exhausted in MEMS chip To symmetrical, but for the chip after entirely encapsulating, four varistors are simultaneously asymmetric, when temperature or stress variation, cause The deformation of pressure sensitive film, and then cause the variation of varistor, but the changing value of varistor will not be identical.Above-mentioned feelings The result of condition can cause in the case where no pressure changes, and the output of pressure sensor can still change, and cause the shakiness of output It is qualitative, it is bigger to show as temperature drift.
Traditional MEMS pressure sensor there are the problem of and defect limit its scope of application, with science and technology not Disconnected development, the demand to MEMS is also increasing, therefore, solves problems of the prior art and further studies precision more High MEMS pressure sensor is imperative.The present invention be directed to MEMS piezo-resistive pressure sensor traditional structures the problem of and Defect, proposition targetedly improves, to improve its precision.
Invention content
It is an object of the present invention to provide a kind of MEMS pressure sensor and its manufacturing methods, by traditional group It is modified at four varistors of Wheatstone bridge, makes it have better symmetry and consistency, can preferably resist Ambient temperature and stress variation export variation caused by it, to improve the precision of MEMS pressure sensor.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing methods, by presser sensor Four varistors are respectively set in the corresponding position of front and back of film so that the pressure of the front and back of opposite position The resistance value of quick resistance is equal, and resistance value changes in the opposite direction with pressure, to be modified, improves the stability of its output.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing methods, and pressure sensitive film is just The varistor at face and the back side respectively forms a Wheatstone bridge, is exported respectively, in a manner of fully differential, to two groups of favours Stone electric bridge is attached, and is reached insensitive to extraneous stress, temperature, is significantly improved the defeated of MEMS pressure sensor Go out stability.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing method, by by two groups of favours this Energization bridge is used cooperatively, and can effectively be reduced since resistance value mismatches the harmful effect caused by output.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing methods, not by front and back Varistor with position is connected two-by-two, is averaged to the varistor of different location, then reformulates a Wheatstone bridge, To offset existing error between traditional varistor.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing methods, by the pressure The front and back of sensitive membrane etches to form dovetail groove to increase the sensibility of pressure sensitive film sensitizing range, and is conducive to arrange Metal lead wire and varistor, to extend the service life of MEMS pressure sensor.
It is simple for process another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing method, and it is normal The technological process of rule is compatible with.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing methods and traditional MEMS phases Than cost need not be increased, therefore realizes the stability of high-precision and output on the basis of lower-cost.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing methods, can keep original On the basis of small volume, the precision of MEMS pressure sensor is improved.
Another object of the present invention is to provide a kind of MEMS pressure sensor and its manufacturing method, sensitivity and precision are all It is higher, expand the application range of MEMS pressure sensor.
To meet object above of the invention and other objects of the present invention and advantage, the present invention provides a kind of MEMS pressures Force snesor, including:
One pressure sensitive film has a front and a back side;
At least four front varistors;And
At least four back side varistors are respectively arranged on described per the front varistor and per the back side varistor The front and back of pressure sensitive film, wherein being able to per the front varistor and per the back side varistor after electrical connection Sense pressure.
According to one embodiment of the invention, the pressure is located at per the back side varistor per the front varistor The corresponding position of power sensitive membrane front and back, by will be described in one of the different location front varistor and one Back side pressure surface resistance is in series, and four varistors pair are formed after all connecting by predetermined way, will be per the varistor to electricity Connection forms a Wheatstone bridge.
Preferably, the varistor is electrically connected to an integrated circuit in turn to being electrically connected to form after Wheatstone bridge, into Row signal exports, and obtains the signal value of the MEMS pressure sensor.
Preferably, the identical front varistor of piezoresistance coefficient and the back side varistor are in series.
Preferably, by inside the pressure sensitive film preset conductive material connecting per the front varistor and Per the back side varistor.
According to one embodiment of the invention, the pressure is located at per the back side varistor per the front varistor The corresponding position of power sensitive membrane front and back is electrically connected to form a Wheatstone bridge, often per the front varistor The back side varistor is electrically connected to form a Wheatstone bridge.
Preferably, the Wheatstone bridge that the front varistor and the back side varistor are formed after being respectively electrically connected It is electrically connected in an integrated circuit and is carried out respectively signal output, the signal value of two groups of outputs is averaged, is obtained described The signal value of MEMS pressure sensor.
Preferably, it is set to the front varistor of the opposite position of the front and back of the pressure sensitive film Resistance value is equal with the resistance value of back side varistor, and resistance value is opposite with the variation of pressure.
Preferably, the back side of the pressure sensitive film includes two back side steps and is bonded slot with a back side, wherein described Back side step is trapped among the edge of the back side bonding slot, wherein the pressure sensitive film is suitable for through the back side step and a lining Bottom is connected, and the back side bonding slot is suitable for the back side varistor of arranging.
A kind of manufacturing method of MEMS pressure sensor, the manufacturing method include the following steps:
It (a) will at least four front varistors and at least four back side varistors are correspondingly set to a presser sensor respectively The front and back of film;
(b) arrangement metal lead wire is sensed with being electrically connected the front varistor and/or the back side varistor Pressure;And
(c) multiple connecting keys are set so that the MEMS pressure sensor be suitable for being electrically connected to an at least integrated circuit into Row signal exports.
According to one embodiment of the invention, in the step (b), by one of the different location front varistor and One back side varistor is in series, and four varistors pair, the varistor are formed after all connecting by predetermined way To being electrically connected to form a Wheatstone bridge by the metal lead wire, it is further electrically connected to an integrated circuit, into Row signal exports to obtain the signal value of the MEMS pressure sensor.
Preferably, the identical front varistor of piezoresistance coefficient and the back side varistor are in series.
Preferably, the preset conductive material in the pressure sensitive film, with the pressure-sensitive electricity in front for different location of connecting Resistance and the back side varistor.
According to one embodiment of the invention, in the step (b), the front varistor by the metal lead wire according to Secondary to be electrically connected to form a Wheatstone bridge, the back side varistor is sequentially connected electrically to form one by the metal lead wire Wheatstone bridge, two Wheatstone bridges are respectively connected on the integrated circuit and carry out signal output respectively, to two groups of outputs Signal value be averaged, obtain the signal value of the MEMS pressure sensor.
Preferably, it is set to the front varistor of the opposite position of the front and back of the pressure sensitive film Resistance value is equal with the resistance value of back side varistor, and resistance value is opposite with the variation of pressure.
Preferably, before the step (a), further comprise two steps:Using wet etching, in the presser sensor A back side dovetail groove is etched in the middle part of the back side of film, and forms two back side steps, the pressure at the edge of the pressure sensitive film Power sensitive membrane is suitable for being connected with a substrate by the back side step;With using wet etching, in the pressure sensitive film Positive Middle face etches a front dovetail groove, is suitable for arrange the front varistor and the metal lead wire.
Preferably, it etches a back side using bottom of the wet etching in the middle part of the back side dovetail groove and is bonded slot, with suitable In the back side varistor and the metal lead wire of arranging.
Preferably, in the above-mentioned methods, it by injecting ions into the front and back of the pressure sensitive film, and anneals and swashs The ion of injection living forms the front varistor and the back side varistor with lattice is repaired.
Preferably, in the above-mentioned methods, heavy in the front and back of the pressure sensitive film by vapor deposition or sputtering technology The product metal lead wire.
Preferably, the metal lead wire positive to the pressure sensitive film performs etching to form the connecting key.
Description of the drawings
Figure 1A is a kind of diagrammatic cross-section of MEMS pressure sensor traditional structure.
Figure 1B is a kind of traditional connected mode schematic diagram of the varistor in MEMS pressure sensor.
Fig. 2 be a kind of MEMS pressure sensor of a preferred embodiment of the present invention pressure sensitive film front for including and The varistor at the back side is in series to form the schematic diagram of a Wheatstone bridge.
Fig. 3 A are the pressure sensitive film fronts that a kind of MEMS pressure sensor of a preferred embodiment of the present invention includes Varistor connection type schematic diagram.
Fig. 3 B are the presser sensor back of the membrane that a kind of MEMS pressure sensor of a preferred embodiment of the present invention includes Varistor connection type schematic diagram.
Fig. 4 A are cuing open for the pressure sensitive film that a kind of MEMS pressure sensor of the above preferred embodiment of the present invention includes Face schematic diagram.
Fig. 4 B and Fig. 4 C are that a kind of back-etching of MEMS pressure sensor of the above preferred embodiment of the present invention is trapezoidal The diagrammatic cross-section of step.
Fig. 4 D to Fig. 4 F are that a kind of back side making of MEMS pressure sensor of the above preferred embodiment of the present invention is pressure-sensitive The diagrammatic cross-section of resistance.
Fig. 5 A to Fig. 5 C are that a kind of front etching of MEMS pressure sensor of the above preferred embodiment of the present invention is trapezoidal The diagrammatic cross-section of step.
Fig. 5 D and Fig. 5 E are that a kind of front making of MEMS pressure sensor of the above preferred embodiment of the present invention is pressure-sensitive The diagrammatic cross-section of resistance.
Fig. 5 F are that a kind of section for MEMS pressure sensor structure that the above preferred embodiment of the present invention completes shows It is intended to.
Specific implementation mode
It is described below for disclosing the present invention so that those skilled in the art can realize the present invention.It is excellent in being described below Embodiment is selected to be only used as illustrating, it may occur to persons skilled in the art that other obvious modifications.It defines in the following description The present invention basic principle can be applied to other embodiments, deformation scheme, improvement project, equivalent program and do not carry on the back Other technologies scheme from the spirit and scope of the present invention.
As shown in Figure 1B, for traditional MEMS pressure sensor, one group of favour stone electricity is formed on pressure sensitive film 1 Bridge comprising four varistors be respectively R1/R2/R3/R4, the piezoresistance coefficient of adjacent resistor on the contrary, face two electricity It is identical to hinder piezoresistance coefficient, when ambient pressure acts on pressure sensitive film 1, the edge of film has stress presence, and this is answered Power can cause the change in resistance of varistor, and the current direction of R1 and R3 are parallel with stress direction, the current direction of R2 and R4 with Stress direction is vertical, causes when there is pressure to act on pressure sensitive film, the change sign phase of R1 and R3 and R2 and R4 resistance Instead.When no pressure inputs, the initial resistance of varistor R1/R2/R3/R4 is zero, bridge balance, output zero, outer when having Boundary's pressure input, when acting on pressure sensitive film, causes varistor to change, and when R1 and R3 increase, R2 and R4 reduce, Or R1 and R3, when reducing, R2 and R4 increase, then Wheatstone bridge not rebalancing, there is signal output.But MEMS pressure sensings It needs to consider that its sensibility to temperature and stress, traditional MEMS piezo-resistive pressure sensors use four in device device Varistor makes Wheatstone bridge, since the resistance value of four varistors can't be essentially equal, leads to its change with temperature Change amount is unequal, and the absolute standard for causing stress sensor changes, and due to after encapsulation four varistors it is not right Title property, can cause in the case where no pressure changes, and the output of pressure sensor can still change, and cause the unstable of output Property.
Varistor is produced on the front and back of pressure sensitive film by the present invention, makes two groups of Wheatstone bridges or will just Reformulate a Wheatstone bridge after the series connection of the varistor at face and the back side, with to form the varistor of Wheatstone bridge into Row is corrected so that varistor has better symmetry and consistency, preferably to resist ambient temperature and stress variation pair Variation is exported caused by it.
Specifically, as illustrated in figure 5f, the present invention provides a kind of MEMS pressure sensor, including a pressure sensitive film 10, extremely Few four front varistors 20, at least four back side varistors 30 and a substrate 40, wherein the pressure sensitive film 10 is connected to The substrate 40 so that the substrate 40 is able to support the pressure sensitive film 10, per the front varistor 20 and every institute It states back side varistor 30 and is respectively arranged on the front 11 and a back side 12 that the pressure sensitive film 10 has, according to predetermined way It is electrically connected and carries out signal output, will hereafter be expanded on further.
It is noted that being equipped with two back side steps 121, a back side dovetail groove at the back side of the pressure sensitive film 10 122 and one the back side be bonded slot 123, wherein the back side step 121 is located at the edge at 10 back side of the pressure sensitive film, the back of the body Face dovetail groove 122 is located at the middle part of the pressure sensitive film 10, and the back side bonding slot 123 is located at the back side dovetail groove 122 The middle part of bottom wall is conducive to the arrange back side varistor 30 and back metal lead 15, to ensure that the MEMS pressure passes Sensor is able to sensing ambient pressure.Wherein lead to per between the front varistor 20 and per between the back side varistor 30 It crosses metal lead wire to be electrically connected, the metal lead wire includes front metal lead 14 and back metal lead 15, wherein described Front metal lead 14 is able to every front varistor 20 being electrically connected, and the back metal lead 15 is able to will be every The back side varistor 30 is electrically connected.
It is worth noting that, the back side dovetail groove 122 and back side bonding slot 123 are intended only as illustrating, and it is unlimited The system present invention, those skilled in the art are contemplated that other deformations, the back side of the pressure sensitive film 10 only need to be arranged One slot freely up and down moves conducive to the pressure sensitive film 10, and the back side varistor 30 is arranged according to actual conditions Cloth is in place.
Further, it is set to the pressure-sensitive electricity of the front varistor 20 and the back side on 10 two sides of the pressure sensitive film Resistance 30 is there are two types of connection and the way of output, and one is the front varistors that will be set to described positive 11 and the back side 12 20 resistance identical with the piezoresistance coefficient in the back side varistor 30 are cascaded one by one, by the pressure sensitive film 10 Varistor electrical connection one Wheatstone bridge of composition on two sides, is exported with single ASIC accesses (integrated circuit), obtains institute The signal value of MEMS pressure sensor output is stated, another kind is by the front varistor 20 and the back side varistor 30 Respectively electrical connection is respectively formed a Wheatstone bridge, and is connected to an ASIC accesses (integrated circuit), two groups of favour stones The signal of electric bridge exports respectively, is then averaged to two groups of output signal values, as MEMS pressure sensor output Signal value.
The present embodiment is illustrated by taking four front varistors 20 and four back side varistors 30 as an example. The front varistor 20 and the back side varistor 30 are respectively arranged on the front 11 and the back side of the pressure sensitive film 10 12, the connection type of the front varistor 20 and the back side varistor 30 is as shown in Fig. 2, form one group of favour stone electricity Bridge, to sense ambient pressure, wherein being connected by front metal lead 14 per between the front varistor 20, per described It is connected by the back metal lead 15 between back side varistor 30, the front varistor 20 and back side pressure It is connected by conducting wire 13 between quick resistance 30, wherein the conducting wire 13 is pre-set at 10 inside of the pressure sensitive film Conductive material, the front metal lead 14 and the back metal lead 15 are formed by etching, and in the pressure Multiple connecting keys 16 are set at the front 11 of sensitive membrane 10, to make 20 He of front varistor by the connecting key 16 The Wheatstone bridge that the back side varistor 30 is formed is connected to an ASIC access, with output signal.
It is worth noting that, the Directional words such as front mentioned in the present invention, the back side, top, lower part are all opposite, It is to preferably explain the relativeness of varistor, be not intended to limit the present invention.
It is noted that the back side varistor 30 and the front varistor 20 be correspondingly set to it is described The back side and front of pressure sensitive film 10 make it preferably resist ambient temperature and answer to correct the front varistor 20 Power variation exports variation caused by it.In other words, alternate respectively at the front 11 of the pressure sensitive film 10 and the back side 12 It is set there are four the front varistor 20 and four back side varistors 30 every ground, per the front varistor 20 In the top of every back side varistor 30, the pressure sensitive film 10 is accompanied therebetween.
As shown in Fig. 2, four front varistors 20 are respectively resistance Ru-1, resistance Ru-2, resistance Ru-3 and electricity Ru-4, four back side varistors 30 respectively resistance Rd-1, resistance Rd-2, resistance Rd-3 and resistance Rd-4 are hindered, wherein Resistance Ru and Rd subsequent digital 1,2,3,4 indicates the resistance of different location respectively, and resistance Ru-1 and resistance Rd-1 is to be located at The resistance of the opposite position on 10 two sides of the pressure sensitive film, i.e. resistance Ru-1 are on co-located with resistance Rd-1 The varistor of front and back, be below in this way, resistance Ru-2 and resistance Rd-2 be front on co-located and The varistor at the back side, resistance Ru-3 and resistance Rd-3 are the varistor of the front and back on co-located, resistance Ru-4 and resistance Rd-4 is the varistor of the front and back on co-located.
Input and output after the front varistor 20 is connected with the back side varistor 30 are as shown in Figure 2.It will 10 front and back different location of the pressure sensitive film, the identical resistance of piezoresistance coefficient link together two-by-two, i.e. Ru-1 It is in series with Rd-2, Ru-2 is in series with Rd-3, and Ru-3 is in series with Rd-4, and Ru-4 is in series with Rd-1, two to be in series Resistance forms a varistor pair, four varistors pair is formed after all connecting by predetermined way, then by four institutes Varistor is stated to reformulating a Wheatstone bridge again, and by Wheatstone bridge to be connected with an ASIC access, To carry out signal acquisition.
In this kind of connection type, it is equivalent to the pressure-sensitive electricity of the different location of 10 front and back of the pressure sensitive film Resistance is cascaded, and is equal to and is averaged to the varistor of different location, can be very good to solve traditional MEMS pressure biography Sensor exports the problem of being not zero, and can offset the error between each resistance in the case where no pressure inputs, and solves tradition MEMS pressure sensor export unstable problem so that the output of the MEMS pressure sensor provided by the invention is more Stablize, and precision is higher.
It is noted that the front varistor 20 set on the opposite position of the pressure sensitive film 10 and institute It is equal to state 30 resistance value of back side varistor, resistance value is opposite, i.e. resistance Ru-1/Ru-3, Rd-2/ with the change direction of pressure When Rd-4 is increasedd or decreased, resistance Ru-2/Ru-4, Rd-1/Rd-3 are reduced or increased, i.e., when resistance Ru-1 is increasedd or decreased, Resistance Rd-1 corresponding thereto is reduced or increased;When resistance Ru-2 is increasedd or decreased, resistance Rd-2 corresponding thereto subtracts Small or increase;When resistance Ru-3 is increasedd or decreased, resistance Rd-3 corresponding thereto is reduced or increased;When resistance Ru-4 increases Or when reducing, resistance Rd-4 corresponding thereto is reduced or increased.
In short, when 20 stretching/compressing of front varistor positive set on the pressure sensitive film 10, corresponding thereto The back side varistor 30 set on 10 back side of the pressure sensitive film answered is compression/stretching, is set in other words described When the resistance value of the positive front varistor of pressure sensitive film 10 20 increases/reduces, corresponding thereto be set to the pressure The resistance value of the back side varistor 30 at 10 back side of power sensitive membrane is to reduce/increased, the front varistor 20 and institute The variation for stating the corresponding varistor of back side varistor 30 be it is opposite, by piezoresistance coefficient sign it is identical it is described just Face varistor 20 and the back side varistor 30 link together two-by-two so that the back side varistor 30 can be to institute It states front varistor 20 to be modified so that each varistor has better symmetry and consistency, described in increase The stability of MEMS pressure sensor output.
Fig. 3 A and Fig. 3 B show another connection side of the front varistor 20 and the back side varistor 30 Formula, as shown in Figure 3A and Figure 3B, the two sides of the pressure sensitive film 10 form two Wheatstone bridges, and each Wheatstone bridge is each Including four varistors, i.e., the described front varistor 20 and the back side varistor 30 are respectively formed Wheatstone bridge, ASIC accesses are connected to, the signal of two groups of Wheatstone bridges exports respectively, and the MEMS pressure is obtained after being averaged and is passed The signal value of sensor.
Specifically, four front varistors 20 are respectively resistance Ru-1, resistance Ru-2, resistance Ru-3 and resistance Ru-4, four back side varistors 30 are respectively resistance Rd-1, resistance Rd-2, resistance Rd-3 and resistance Rd-4, wherein electricity Resistance Ru and Rd subsequent digital 1,2,3,4 indicates the resistance of different location respectively, and resistance Ru-1 and resistance Rd-1 is to be located at institute State the resistance of the opposite position on 10 two sides of pressure sensitive film, i.e. resistance Ru-1 and resistance Ru-2 be on co-located just The varistor in face and the back side is in this way, resistance Ru-2 and resistance Rd-2 is front and the back of the body on co-located below The varistor in face, resistance Ru-3 and resistance Rd-3 are the varistor of the front and back on co-located, resistance Ru- 4 and resistance Rd-4 is the varistor of the front and back on co-located.
It is noted that set on 10 front and back of the pressure sensitive film the front varistor 20 with it is described The resistance value of back side varistor 30 changes in the opposite direction, i.e. resistance Ru-1 and resistance Rd-1's changes in the opposite direction, resistance Ru- 2 change in the opposite direction with resistance Rd-2, and resistance Ru-3 changes in the opposite direction with resistance Rd-3's, resistance Ru-4 and resistance Rd-4 Change in the opposite direction.In other words, when resistance Ru-1/Ru-3, Rd-2/Rd-4 is increasedd or decreased, resistance Ru-2/Ru-4, Rd- 1/Rd-3 is reduced or increased, i.e., when resistance Ru-1 is increasedd or decreased, resistance Rd-1 corresponding thereto is reduced or increased;Work as electricity When resistance Ru-2 is increasedd or decreased, resistance Rd-2 corresponding thereto is reduced or increased;When resistance Ru-3 is increasedd or decreased, with it Corresponding resistance Rd-3 is reduced or increased;When resistance Ru-4 is increasedd or decreased, resistance Rd-4 corresponding thereto reduce or Increase.
In Fig. 3 A and Fig. 3 B, two groups of favour stones of the front varistor 20 and the back side varistor 30 composition The input of electric bridge is all made of unified input Vin, and output is respectively Vout1 and Vout2, finally makees and asks flat Vout1 and Vout2 , the Vout of final output, i.e., the signal value of the described MEMS pressure sensor output are obtained.
In this kind of connection type, due to the front varistor 20 each varistor and corresponding thereto described in The resistance value of back side varistor 30 is equal, and resistance value is opposite with the change direction of pressure so that the back side varistor 30 are able to be modified the front varistor 20, reach insensitive to extraneous stress, temperature, can effectively reduce resistance value The influence caused by output is mismatched, the stability and precision of the MEMS pressure sensor are significantly improved.
Fig. 4 A to Fig. 5 F show it is provided by the invention as described in MEMS pressure sensor manufacturing process, pass through following works Skill makes the MEMS pressure sensor with double-faced pressure-sensitive resistor stripe.The present embodiment is with the front varistor 20 and phase It is carried out for the MEMS pressure sensor of one Wheatstone bridge of formation after the corresponding back side varistor 30 is connected Explanation.
(A) prepare sensitive layer of the wafer (wafer) with silicon perforation (TSV) as the MEMS pressure sensor, That is the pressure sensitive film 10.
The wherein described pressure sensitive film 10 has a front 11 and a back side 12, and in advance in the pressure sensitive film 10 A plurality of conducting wire 13 is arranged in portion, wherein the conducting wire 13 is formed by conductive material, is after making silicon perforation in the wafer, Conductive material is filled, the conductive material forms the conducting wire 13, i.e., the pressure-sensitive electricity of the described front varistor 20 and the back side Resistance 30 is electrically connected by being preset in the conductive material of the pressure sensitive film 10.
(B) slot at the back side is formed.Including two steps:
(B.1) at the back side of the pressure sensitive film 10 12 etch a back side dovetail groove 122, the back side 12 remaining Part then forms two back side steps 121, wherein the back side dovetail groove 122 can be implemented by wet etching to corrode, institute It states back side step 12 and surrounds the back side dovetail groove 122, and positioned at the edge of the pressure sensitive film 10, the pressure sensitive film 10 are suitable for being bonded with 40 phase of the substrate by the back side step 121.Preferably, corroded using wet etching and 3 μm or so The back side dovetail groove 122 of depth, conducive to the back metal lead 15 of subsequently arranging.
(B.2) further slot 123 is bonded in one back side of etching in the bottom of the back side dovetail groove 122, wherein the back side Bonding slot 123 can be implemented by wet etching to corrode.Preferably, the back side bonding slot 123 is about 15 μm or so The slot of the trapezoidal shape of depth, in favor of the injection of the back side varistor 30 and the winding displacement of the back metal lead 15.
It is noted that the depth of the back side dovetail groove 122 is the depth that 3 μm and the back side are bonded slot 123 It is intended only as illustrating for 15 μm, however it is not limited to which the size, those skilled in the art can make other rulers according to actual conditions Very little slot.
(C) preparation of the back side varistor 30.Including three steps:
(C.1) back side varistor 30 is formed using ion implantation, that is, uses the method for ion implanting by predetermined Arrangement implants ions into the bottom of the back side bonding slot 123 at 10 back side of the pressure sensitive film at intervals, forms institute State the blank of back side varistor 30, and by subsequent annealing, activation and etc. form the back side varistor 30.
(C.2) the back metal lead 15 is deposited, specifically, is drawn the back metal using vapor deposition or sputtering technology Line 15 deposits to the back side 12 of the pressure sensitive film 10, wherein the back metal lead 15 deposits to the back side step 121, the back side dovetail groove 122 and the back side are bonded slot 123, and will successively be electrically connected per the back side varistor 30 It connects.
(C.3) the back metal lead 15 is performed etching, i.e. the metal lead wire to the back side step 121 and described Metal lead wire between back side varistor 30 carries out partial etching, so that according to pre- between every back side varistor 30 Determine mode to be attached, so that each back side varistor 30 is able to sensing pressure.
(D) it is bonded, the pressure sensitive film 10 is overturn so that the back side step 121 of the pressure sensitive film 10 It is bonded with the substrate 40, so that the substrate 40 is able to support the pressure sensitive film 10, being convenient for subsequently will be described MEMS pressure sensor is installed to specific occasion and is applied.
It is noted that after the pressure sensitive film 10 is bonded with 40 phase of the substrate, then the back side dovetail groove 122 And back side bonding slot 123 is positioned there between, is freely up and down moved conducive to the pressure sensitive film 10.
(E) front dovetail groove 112 is formed, wherein the front dovetail groove 112 can be wet by being utilized on described positive 11 Method etching is implemented to corrode, and the front dovetail groove 112 advantageously reduces the presser sensor of the pressure sensitive film 10 The thickness in region, to increase sensitivity, wherein positive 11 other parts then form front step 111.
It is noted that when the thickness of wafer is larger, before forming the front dovetail groove 112, will can first make It is thinned for the wafer of the pressure sensitive layer, with reach can be to extraneous pressure-sensitive thickness.
It will be further appreciated that when the pressure sensitive film 10 is sufficient to extraneous presser sensor, shape can not had to It at the front dovetail groove 112, i.e., only needs to form dovetail groove at the back side of the pressure sensitive film 10, passes through back side ladder Shape slot 122 and/or the back side bonding slot 123 and the substrate 40 form closed cavity, the pressure sensitive film 10 just Face can be smooth.This preferred embodiment why be arranged in the middle part of the front and back of the pressure sensitive film 10 it is described just Face dovetail groove 112, back side dovetail groove 122 and back side bonding slot 123 also help other than many merits of above-mentioned introduction Increase the sensibility of the pressure sensitive area of the pressure sensitive film 10, while can ensure the edge of the pressure sensitive film 10 It is thicker, to increase the service life of the MEMS pressure sensor.
(F) preparation of the front varistor 20.Include the following steps:
(F.1) the front varistor 20 is formed using ion implantation, that is, uses the method for ion implanting by predetermined Arrangement implants ions into the bottom of the positive front dovetail groove of the pressure sensitive film 10 112 at intervals, forms institute State the blank of front varistor 20.
(F.2) it anneals, to activate the ion of described positive 11 and the injection of the back side 12, and repairs lattice, that is, activate institute Front varistor 20 and the back side varistor 30 are stated, pressure can be sensed.
(F.3) the front metal lead 14 is deposited, specifically, is drawn the front metal using vapor deposition or sputtering technology Line 14 deposits to the front 11 of the pressure sensitive film 10, wherein the front metal lead 14 deposits to the front step 111, the front dovetail groove 112, and each front varistor 20 is electrically connected successively.
(F.4) the front metal lead 14 is performed etching, i.e. the metal lead wire to the positive back side step 111 and institute The metal lead wire stated between front varistor 20 carries out partial etching, so that each front varistor 20 is according to predetermined Mode is electrically connected, and is etched and formed multiple connecting keys 16, and the described positive 11 pressure-sensitive electricity in front will be located at Hinder 20 and the back side varistor 30 extraction positioned at the back side 12.
It is noted that the connecting key 16 is able to connect an at least ASIC accesses, in order to which the MEMS pressure passes Sensor is electrically connected with the ASIC accesses carries out signal output, with applied to different occasions so that the front varistor 20 and the back side varistor 30 by the pressure transmission signal of sensing give the ASIC accesses, carry out signal output.
It is noted that in above steps, the conducting wire 13 of arranging, the front metal lead 14 and the back of the body When the metal lead wire 15 of face, obtain so that the front varistor 20 of different location and the back side varistor 30 carry out two-by-two Series connection, then re-forms a Wheatstone bridge, and be connected to an ASIC access, and then is able to sensing ambient pressure simultaneously Carry out signal output.
The pressure sensitive film 10, the substrate 40, the front varistor 20 and the back side varistor 30, institute It states conducting wire 13, the front metal lead 14, the back metal lead 15 and the connecting key 16 and tradition may be used The material and technique of MEMS pressure sensor corresponding portion make, and can also carry out transformation appropriate.
It is worth noting that, above steps is intended only as illustrating, it is not intended to limit the present invention, those skilled in the art can The sequence of above steps will be replaced according to actual conditions.
It should be understood by those skilled in the art that the embodiment of the present invention shown in foregoing description and attached drawing is only used as illustrating And it is not intended to limit the present invention.The purpose of the present invention has been fully and effectively achieved.The function and structural principle of the present invention exists It shows and illustrates in embodiment, under without departing from the principle, embodiments of the present invention can have any deformation or modification.

Claims (25)

1. a kind of MEMS pressure sensor, which is characterized in that including:
One pressure sensitive film has a front and a back side;
At least four front varistors;And
At least four back side varistors are respectively arranged on the pressure per the front varistor and per the back side varistor The front and back of sensitive membrane, wherein being sensed per the front varistor and per the back side varistor after electrical connection Pressure;
Further there is the wherein described pressure sensitive film slot, the slot to be formed in the back side of the pressure sensitive film Portion, wherein be located in the slot per the back side varistor set on the back side of the pressure sensitive film, wherein Set on the pressure sensitive film it is described it is positive per the front varistor respectively the pressure sensitive film it is described just Face corresponds to set on the back side of the pressure sensitive film per the back side varistor.
2. MEMS pressure sensor as described in claim 1, by by one of the different location front varistor and One back side varistor is in series, and four varistors pair are formed after all connecting by predetermined way, will be per described pressure-sensitive Resistance is to being electrically connected to form a Wheatstone bridge.
3. MEMS pressure sensor as claimed in claim 2, the varistor is laggard to being electrically connected to form Wheatstone bridge And it is electrically connected to an integrated circuit, signal output is carried out, the signal value of the MEMS pressure sensor is obtained.
4. MEMS pressure sensor as claimed in claim 2, by the identical front varistor of piezoresistance coefficient and described Back side varistor is in series.
5. MEMS pressure sensor as claimed in claim 3, by the identical front varistor of piezoresistance coefficient and described Back side varistor is in series.
6. MEMS pressure sensor as described in claim 1 is electrically connected to form a favour stone per the front varistor Electric bridge is electrically connected to form a Wheatstone bridge per the back side varistor.
7. MEMS pressure sensor as claimed in claim 6, the front varistor and the back side varistor are respectively The Wheatstone bridge formed after electrical connection is electrically connected in an integrated circuit and carries out respectively signal output, to two groups of output Signal value is averaged, and obtains the signal value of the MEMS pressure sensor.
8. the MEMS pressure sensor as described in claim 2 to 7 is any is set to the front and back of the pressure sensitive film The resistance value of the front varistor of opposite position is equal with the resistance value of back side varistor, and resistance value is with pressure Variation is opposite.
9. the MEMS pressure sensor as described in any in claim 2 to 5 is led by preset inside the pressure sensitive film Electric material is connected per the front varistor and per the back side varistor.
10. the back side of MEMS pressure sensor as claimed in claim 8, the pressure sensitive film includes two back side steps, institute The slot for stating pressure sensitive film forms back side bonding slot, wherein the back side step is trapped among the side of the back side bonding slot Edge, wherein the pressure sensitive film is suitable for being connected with a substrate by the back side step, the back side bonding slot is suitable for row Back side varistor described in cloth.
11. a kind of manufacturing method of MEMS pressure sensor, which is characterized in that the manufacturing method includes the following steps:
(a) by least four front varistors and at least, four back side varistors are correspondingly set to a pressure sensitive film respectively Front and back;
(b) arrangement metal lead wire is able to sensing pressure to be electrically connected the front varistor and/or the back side varistor Power;And
(c) multiple connecting keys are set so that the MEMS pressure sensor, which is suitable for being electrically connected to an at least integrated circuit, carries out letter Number output;
Further there is the wherein described pressure sensitive film slot, the slot to be formed in the back side of the pressure sensitive film Portion, wherein be located in the slot per the back side varistor set on the back side of the pressure sensitive film, wherein Set on the pressure sensitive film it is described it is positive per the front varistor respectively the pressure sensitive film it is described just Face corresponds to set on the back side of the pressure sensitive film per the back side varistor.
12. manufacturing method as claimed in claim 11, wherein in the step (b), by one of different location it is described just Face varistor and a back side varistor are in series, and four varistors pair are formed after all connecting by predetermined way, The varistor is further electrically connected to being electrically connected to form a Wheatstone bridge by the metal lead wire described in one Integrated circuit carries out signal and exports to obtain the signal value of the MEMS pressure sensor.
13. manufacturing method as claimed in claim 12, by the identical front varistor of piezoresistance coefficient and the back side Varistor is in series.
14. manufacturing method as claimed in claim 12, wherein the preset conductive material in the pressure sensitive film, to connect not The front varistor with position and the back side varistor.
15. manufacturing method as claimed in claim 13, wherein the preset conductive material in the pressure sensitive film, to connect not The front varistor with position and the back side varistor.
16. manufacturing method as claimed in claim 11, wherein in the step (b), the front varistor passes through institute It states metal lead wire to be sequentially connected electrically to form a Wheatstone bridge, the back side varistor is electric successively by the metal lead wire Connection forms a Wheatstone bridge, and two Wheatstone bridges are respectively connected on the integrated circuit and progress signal is defeated respectively Go out, the signal value of two groups of outputs is averaged, obtains the signal value of the MEMS pressure sensor.
17. the manufacturing method as described in any in claim 11 to 16, wherein set on the front of the pressure sensitive film and the back of the body The resistance value of the front varistor of the opposite position in face is equal with the resistance value of back side varistor, and resistance value is with pressure The variation of power is opposite.
18. manufacturing method as claimed in claim 17 further comprises two steps before the step (a):Utilize wet method Etching, etches a back side dovetail groove, and in the edge shape of the pressure sensitive film in the middle part of the back side of the pressure sensitive film At two back side steps, the pressure sensitive film is suitable for being connected with a substrate by the back side step;With using wet etching, A front dovetail groove is etched in the positive Middle face of the pressure sensitive film, be suitable for arranging the front varistor and described Metal lead wire.
19. manufacturing method as claimed in claim 18 further comprises a step:It is trapezoidal at the back side using wet etching Bottom in the middle part of slot etches the slot, wherein the slot is back side bonding slot, is suitable for the back side varistor of arranging With the metal lead wire.
20. the manufacturing method as described in any in claim 11 to 16, in the above-mentioned methods, by injecting ions into the pressure The front and back of power sensitive membrane, and the ion for activation injection of annealing forms the front varistor and institute with lattice is repaired State back side varistor.
21. manufacturing method as claimed in claim 17, in the above-mentioned methods, by injecting ions into the pressure sensitive film Front and back, and the ion for activation injection of annealing and reparation lattice are pressure-sensitive to form the front varistor and the back side Resistance.
22. manufacturing method as claimed in claim 19, in the above-mentioned methods, by injecting ions into the pressure sensitive film Front and back, and the ion for activation injection of annealing and reparation lattice are pressure-sensitive to form the front varistor and the back side Resistance.
23. the manufacturing method as described in any in claim 11 to 16 is existed by vapor deposition or sputtering technology in the above-mentioned methods The front and back of the pressure sensitive film deposits the metal lead wire.
24. manufacturing method as claimed in claim 22, in the above-mentioned methods, quick in the pressure by vapor deposition or sputtering technology The front and back for feeling film deposits the metal lead wire.
25. manufacturing method as claimed in claim 24, in the above-mentioned methods, the metal positive to the pressure sensitive film Lead performs etching to form the connecting key.
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