Invention content
The purpose of the present invention is be all that external zeroing circuit adjusts electric bridge to solve existing sensing chip for sensorBalance, cannot propose that a kind of adjustable HI high impact of zero passes the shortcomings that returning to zero on acceleration sensor chipSensor chip and preparation method thereof, extends zeroing function on chip.
The zero adjustable height shock transducer chip and preparation method thereof of the present invention, using surface silicon process technology,Several groups zeroing exclusion and interconnection line circuit are processed on chip, return to zero exclusion and arm resistance serial or parallel connection,Realize the adjusting of the offset output of electric bridge.And it is formed electrically mutually by spun gold between the zeroing exclusion in every groupEven, spun gold is bonded between pressure drag item, hooks break a part therein to control the row of access bridge as neededHinder quantity, the overall resistance value of compensation sealed in or be incorporated to control, required hook break quantity by offset output notBalance bridge pressure determines.
A kind of zero adjustable height shock transducer chip, including silicon frame, sensitive diaphragm, mass block, fourPressure drag force sensing resistance, series compensation exclusion, shunt compensation exclusion, series connection coarse adjustment exclusion, interconnection line, spun goldArray.
Sensor chip is E type film island structures along the section of symmetry axis, passes through silicon micromachining technique sum aggregateAt circuit planes technology, overall processing forms on a square body single crystal silicon material.Silicon frame is with oneThe square monocrystalline silicon frame of fixed width degree and thickness；Symmetrical stereochemical structure centered on mass block is located at silicon frameFrame inside center forms " returning " font groove with silicon frame, and thickness is less than the thickness of silicon frame；It is sensitiveDiaphragm is less than the thickness of mass block between silicon frame and mass block；The quick resistance phase of four pressure resistancesDeng an axis of symmetry and " returning " font groove outer trough edge edge and interior trough rim positioned at sensitive diaphragm upper surfaceFour point of intersection on edge.
Outer trough edge edge where the length direction of four pressure drag force sensing resistances and " returning " font groove and interior trough rimAlong parallel or vertical.The axis of symmetry where four pressure drag force sensing resistance centers is place single-axis sensors coreThe maximum crystal orientation of piece piezoresistance coefficient.
The series compensation exclusion, shunt compensation exclusion, series connection coarse adjustment exclusion are laid in chip upper surface,On silicon frame.Coarse adjustment exclusion of connecting includes 4 length and width, the identical resistor stripe of spacing, series compensation rowResistance, shunt compensation exclusion respectively include 8 length and width, the identical resistor stripe of spacing；Three groups of exclusions are first logicalCross interconnection line and be unified into one group, then with the quick resistance serial or parallel connection of pressure resistance, realize and the quick resistance value of pressure resistanceCompensation, reaches bridge balance.The adjustable Standard resistance range of series connection coarse adjustment exclusion is more than series compensation exclusion and parallel connectionCompensate exclusion.
Interconnection line is laid in single-axis sensors chip upper surface, and steaming gold process by vacuum is process, by spun goldWheatstone bridge circuits are connected into four pressure drag force sensing resistances.
Spun gold is connected between exclusion or between exclusion and interconnection line, and more spun golds form spun gold array, packetThe spun gold of control exclusion break-make is included, and resistor coupled in parallel is connected into the spun gold of resistance row.If hooking the exclusion that breaks by handBetween spun gold, so that the resistance quantity of parallel connection is reduced, exclusion resistance value increase, then increase series compensationThe exclusion resistance value of function reduces the exclusion resistance value of shunt compensation；If bridge arm has balanced, do not have to compensation zeroing,Then hook the disconnected spun gold connected between exclusion and interconnection line so that whole exclusion not with bridge serial or parallel connection.
The manufacture craft of zero adjustable height shock transducer chip of the present invention is：
Step 1, the monocrystalline silicon piece of (100) chip N-type twin polishing is selected, and it is clear to carry out chemistry to silicon chipIt washes；
Step 2, certain thickness silicon dioxide layer is grown on silicon chip two sides, for sheltering heavily boron diffusion and the back sideMake litho pattern；
Step 3, the low-resistance that dual surface lithography makes resistance end, resistance is drawn is sunken cord and line, pressure welding pad regions,Chip back makes membrane island structure (using wet method or dry method)；The chip that wet processing is produced, the back sideOn mass block, angle is self-corrosion angular stop between silicon frame and sensitive diaphragm, dry process is produced thenFor 90 ° of angles；
Step 4, dense boron preformed precipitate and main diffusion process concentrated boron area；
Step 5, secondary photoetching, single side etch light boron resistance diffusion region, light boron preformed precipitate and light boron main diffusion,Ultimately form resistance；
Step 6, third photo etching etches the chip interconnection point of Wheatstone bridge；
Step 7, vacuum steams gold, realizes the Ohmic contact between silicon and metal lead wire；
Step 8, DRIE etches trench area, forms the areas Mo Dao of E type power sensing structures；
Step 9, chip is divided into the unit of n × n with sand-wheel slice cutting machine.
The zeroing process of zero adjustable height shock transducer chip of the present invention is：
Step 1, the resistance value size of four pressure drag force sensing resistances is measured by probe station；
Step 2, series compensation exclusion, shunt compensation exclusion, coarse adjustment exclusion of connecting are measured by probe stationThe size of each single resistance；
Step 3, it measures and obtains the size of chip zero point offset amount, in conjunction with the resistance value of step 1 and step 2,Calculate the number of series compensation exclusion, shunt compensation exclusion, series connection coarse adjustment exclusion access bridge circuit exclusion；
Step 4, the spun gold for the corresponding exclusion that breaks is hooked so that the resistance number of residue access circuit meets step 3 and obtainsNumber；
Step 5, bridge circuit detection is carried out with test equipment, if meeting condition, is pressed with a batch of chipSame steps carry out chip-scale zero and quickly adjust.If being unsatisfactory for condition, step 3 and step 5 are repeated, untilMeet chip precision.
Advantageous effect
The chip-scale zeroing of the present invention, has reduced the needs of design and configuration peripheral circuit, has reduced pressure resistance typeThe complexity of HI high impact sensor bridge balancing circuitry saves a large amount of assembly spaces, easy to process, operationIt is convenient, substantially increase the practicability of HI high impact sensor.The production method of the present invention is that HI high impact MEMS addsVelocity sensor engineering method, meets that HI high impact sensor is light-weight, small, impact resistance is strong wantsIt asks, the method for making full use of structure itself " vigour zero " greatly improves the precision of HI high impact sensor, forThe development aspect of military sensor has a very important significance and application prospect.
Description of the drawings
Fig. 1 is the single-axis acceleration sensors of single thread mounting structure；Wherein, (a) is that uniaxial pressure resistance type is highMEMS acceleration transducers are impacted, are (b) single-axis piezoelectric formula high-impact acceleration sensor；
Fig. 2 is the zero adjustable height shock transducer chip structure schematic diagram of the present invention；
Fig. 3 is the zero adjustable height shock transducer chip fabrication technique flow chart of the present invention；
Fig. 4 is the zero adjustable height shock transducer chip back structural schematic diagram of the present invention；Fig. 4 (a) isWet etching is process, and Fig. 4 (b) is process for dry etching；
Fig. 5 (a) is the zero adjustable height shock transducer chip vertical view of the present invention；Fig. 5 (b) is of the inventionZero adjustable height shock transducer chip A-A structure sectional views；Fig. 5 (c) is the zero adjustable height punching of the present inventionHit sensor chip B-B structure sectional views；
Fig. 6 is the piezoresistance coefficient curve of monocrystalline silicon (100) crystal face in specific implementation mode；
Fig. 7 is the pressure drag force sensing resistance full-bridge circuit of acceleration detection in specific implementation mode；
Fig. 8 is the acceleration detection stress diagram of sensitive chip in specific implementation mode；
Fig. 9 is that type testing data and curves are tested in HI high impact in specific implementation mode.
Label declaration
1a- circuits a points correspond to pad, and 1b- circuits b points correspond to pad, and 1c- circuits c points correspond to pad, 1d-Circuit d points correspond to pad, and 1e- circuits e points correspond to pad, 2- interconnection lines, 3a-R1 series compensation exclusion Rx1,The public terminal interconnection of 3b-R3 series compensation exclusion Rx2,4a-Rx1 exclusions, the interconnection of 4b-Rx2 exclusions common endLine, 5a- series compensation exclusion Rx1 spun gold arrays, 5b- series compensation exclusion Rx2 spun gold arrays, 6R1-One pressure drag force sensing resistance, 6R2- the second pressure drag force sensing resistances, 6R3- third pressure drag force sensing resistances, 6R4- the 4thPressure drag force sensing resistance, 7a-R4 shunt compensation exclusion Rp2,7b-R2 shunt compensation exclusion Rp1,8a- parallel connections are mendedRepay the public terminal interconnections of exclusion Rp2, the public terminal interconnections of 8b- shunt compensation exclusion Rp1,9a- shunt compensationsExclusion Rp2 spun gold arrays, 9b- shunt compensation exclusion Rp1 spun gold arrays, 10a- exclusion Rp2 break-makes control goldSilk, 10b- exclusion Rp1 break-makes control spun gold, 11a- series connection coarse adjustment exclusion Rs2,11b- series connection coarse adjustment exclusionsRs1,12a- coarse adjustment exclusion Rs2 spun gold arrays, 12b- coarse adjustment exclusion Rs1 spun gold arrays, 13a- coarse adjustment exclusionsRs2 break-makes control spun gold, and 13b- coarse adjustment exclusion Rs1 break-makes control spun gold, 14a- coarse adjustment exclusion Rs2 spun gold battle arraysRow initiating terminal, 14b- coarse adjustment exclusion Rs2 spun gold array initiating terminals, the light boron diffusion resistances of 15-, the resistance of 16- squaresIt is worth testing weld pad, 17- silicon frames, 18- sensitive diaphragms, 19- mass blocks, 20- outer trough edges edge, trough rim in 21-Edge, 22- mass block self-corrosions stop surface, 23- silicon frame self-corrosions stop surface.
Specific implementation mode
In order to better illustrate objects and advantages of the present invention, come with reference to the accompanying drawings and examples to the present inventionContent is described further.
As shown in Fig. 2, the present invention zero adjustable height shock transducer chip, including with bridge a, b, c, d, ePotential point corresponding pad 1a, 1b, 1c, 1d, 1e, interconnection line 2, series compensation exclusion 3a, 3b, series connection are mendedRepay exclusion public terminal interconnection 4a, 4b, series compensation exclusion spun gold array 5a, 5b, pressure drag force sensing resistanceR1, R2, R3, R4, shunt compensation exclusion 7a, 7b, exclusion public terminal interconnection 8a, 8b in parallel, exclusion in parallelSpun gold array 9a, 9b, exclusion break-make control spun gold 10a, 10b, series connection coarse adjustment exclusion 11a, 11b, coarse adjustment rowHinder spun gold array 12a, 12b, coarse adjustment exclusion break-make control spun gold 13a, 13b, light boron diffusion resistance 15, squareResistance value testing weld pad 16, silicon frame 17, sensitive diaphragm 18, mass block 19.Interconnection line 2 be open by pressure dragForce sensing resistance R1, R2, R3, R4 and pad 1a, 1b, 1c, 1d, 1e interconnection form Wheatstone bridge, are designed toBe open electric bridge, can accurately measure each arm resistance value, facilitates compensation zero point output and sensitivity temperature drift, Ke YiyongElectric-resistivity method adjusts bridge balance in parallel or series.
Electric connecting relation is：Series compensation exclusion 3a passes through public terminal interconnection 4a and pressure drag force sensing resistanceR1 connects, and series compensation exclusion 3b is connected by public terminal interconnection 4b and pressure drag force sensing resistance R3, in parallelIt is in parallel with pressure drag force sensing resistance R4 by public terminal interconnection 8a and break-make control spun gold 10a to compensate exclusion 7a,Shunt compensation exclusion 7b controls spun gold 10b and pressure drag force sensing resistance R2 by public terminal interconnection 8b and break-makeParallel connection, series connection fine tuning exclusion 11a control spun gold 14a and R4 series connection, string by common end interconnection line and break-makeConnection fine tuning exclusion 11b controls spun gold 14b and R2 series connection by common end interconnection line and break-make.
Series compensation exclusion 3a, 3b determine required resistance quantity according to resistance value, must proximally be hooked toward distal end disconnectedSpun gold quantity in spun gold array 5a, 5b determines, is unable to contrary operation.
Break-make control spun gold 10a and 10b determine whether shunt compensation exclusion 7a and 7b access bridge respectively,Break-make control spun gold 10a and 10b original state be bonded to exclusion 7a and 7b first block of proximal end resistance andBetween interconnection line, it is connected to exclusion in parallel, 7a and 7b are in parallel with R2 and R4 respectively, play shunt compensationEffect；After breaking 10a and 10b by hooking by hand, then entire row exclusion 7a and 7b is gone functionalization.RootThe resistance quantity needed for shunt compensation exclusion 7a and 7b determined according to resistance value passes through the disconnected shunt compensation exclusion of hookThe quantity of spun gold is completed in spun gold array 9a and 9b, and operation is can be with any position.
Series connection fine tuning exclusion 11a, 11b, required resistance quantity is determined according to resistance value, must be from distance 1b padsDistal end the spun gold quantity broken in spun gold array 12a, 12b is hooked toward proximal end to determine, be unable to contrary operation；AndAnd needing to hook open close disconnected control spun gold 13a, 13b can just make series connection fine tuning exclusion 11a, 11b access favour stone electricityBridge.The case where this controls spun gold 10a and 10b with shunt compensation break-make is opposite.
By probe test pad 16, the concentration of light boron diffusion resistance 15 can be tested out, to the side of testing outBlock resistivity.
As shown in figure 3, the fabrication processing figure of the zero adjustable height shock transducer chip of the present invention, altogetherUsing three pieces of masks, it is divided into two kinds of techniques of dry and wet etching.Select the N-type twin polishing of (100) chipMonocrystalline silicon piece, it is desirable that dislocation-free, sheet resistance for microarea rate uniformity are good, wafer size be 6 inch plaques, thickness300 ± 20 μm, piece edge has<100>Crystal orientation trimming；DRIE etches trench area, 260 μm of etching depth；Chip is divided into the unit of 2.12 × 2.12mm with sand-wheel slice cutting machine.
As shown in figure 4, for the rear view of single-axis sensors chip, the left side is process for dry etching,The right is process for wet etching.Chip is E type film island structures, including silicon frame along the section of symmetry axis17, sensitive diaphragm 18, mass block 19.Silicon frame 17 is rectangular bulk single crystal si and has one fixed width and thicknessThe square-shaped frame of degree；Sensitive diaphragm 18 be located at the centre of silicon frame 17, chip upper surface；Mass block 19Centered on symmetrical stereochemical structure, be located at 18 central area of sensitive diaphragm lower surface, with silicon frame 17 itBetween formed " returning " font groove, thickness be less than silicon frame 17 thickness, more than sensitive diaphragm 18 thicknessDegree；According to the chip that wet etching is process, Back Word connected in star and sensitive diaphragm connecting portion form oneThe joint face of a inclined-plane with self-corrosion angle, mass block 19 and sensitive diaphragm 18 is mass block self-corrosion face22, the joint face of silicon frame 17 and sensitive diaphragm 18 is silicon frame self-corrosion face 23.
Single-axis sensors chip is rectangular at one all by miromaching and integrated circuit planar techniqueOverall processing forms on bulk single crystal si material.Single crystal silicon material can select (100) crystal face, or (111)Crystal face, or (110) crystal face single crystal silicon material.Symmetrical structure centered on the mass block 19, shapeShape is square, can also be truncated rectangular pyramids, six terrace with edges, eight terrace with edges, cylinder and round platform etc..
As shown in figure 5, pad 1a, 1b, 1c, 1d, 1e, arm resistance R1, R2, R3, R4, series compensation rowThe location diagram of resistance Rx1, Rx2, shunt compensation exclusion Rp1, Rp2, series connection roughly adjusted rheostat Rs1, Rs2.R1It is connected with Rx1,1a, 1e, R2 is connected with Rp1, Rs2,1a, 1b, R3 and Rx2,1c, 1dIt is connected, R4 is connected with Rp2, Rs2,1b, 1c.
Four pressure drag force sensing resistances (the first pressure drag force sensing resistance 6R1, the second pressure drag force sensing resistance 6R2, thirdPressure drag force sensing resistance 6R3, the 4th pressure drag force sensing resistance 6R4) it is laid in positive silicon base；Four pressure resistancesQuick resistance is equal, and it is corresponding with " returning " font groove quick to be located at the 22 upper surface axis of symmetry of sensitive diaphragmFeel the outer trough edge of diaphragm upper surface along 20 and the point of intersection inside groove edge 21, their length direction and " returning "The place outer trough edge of font groove is parallel or vertical with inside groove edge 21 along 20.Four pressure drag force sensing resistancesThe axis of symmetry where center is the maximum crystal orientation of corresponding single-axis sensors chip piezoresistance coefficient.It is being embodiedIn the process, the length-width ratio of pressure drag force sensing resistance can be selected as 6: 1-12: 1, and one kind as the present invention is preferablyScheme, length-width ratio can be selected as 10: 1.The resistor stripe of compensation function is played, width is identical with spacing, about2-6 times of the quick resistor width of pressure resistance, the width of of length no more than silicon frame.Connect coarse adjustment exclusion RS1, RS2Parallel resistance quantity is about series compensation exclusion Rx and the half of shunt compensation exclusion Rp in group, therefore adjustableRange is two times of Rx and Rp.Fig. 5 (b) is the structure sectional view along the paths A-A, and Fig. 5 (c) is along B-BThe structure sectional view in path, from structure sectional view, it can be seen that compensation exclusion is all located on silicon frame.
Below by taking single crystal silicon material (100) crystal face as an example, illustrate 3-axis acceleration operation principle.
As shown in fig. 6, the piezoresistance coefficient curve of single crystal silicon material (100) crystal face, X axisCrystal orientation[011] crystal orientation piezoresistance coefficient is maximum；Y-axisCrystal orientation andCrystal orientation piezoresistance coefficient is maximum, and above-mentionedThe piezoresistance coefficient of four crystal orientation is equivalent.
The Hui Si for being made up of four pressure drag force sensing resistances 6R1,6R2,6R3 and 6R4 the interconnection line 2 that is openLogical full-bridge circuit is as shown in Figure 7, wherein 6R1,6R2 are inIn crystal orientation, 6R3 and 6R4 are inIn crystal orientation, pressure drag force sensing resistance length direction is in along X-directionIn crystal orientation；R1 and R3 connectResistance Rx1 and Rx3 are compensated, connects roughly adjusted rheostat Rs1, R4 after R2 shunt compensation resistance RP1 again similarly simultaneouslyConnect roughly adjusted rheostat Rs2 again after connection compensation resistance RP2；Input electricity to applying on arm electric bridge node for one group whereinPressure achievees the purpose that acceleration analysis by detecting another group to the voltage change of arm electric bridge node.
When by Z axis outwardly acceleration effect as shown in Figure 8, mass block 19 is acted on by inertia forceIt is moved on 18 direction of sensitive diaphragm, elastic deformation occurs for sensitive diaphragm 17, according to piezoresistive effect originalReason, pressure drag force sensing resistance 6R1 and 6R4 are reduced by action of compressive stress, resistance, pressure drag force sensing resistance 6R2With 6R3 by action of pulling stress, resistance increases；And series compensation resistance Rx1, Rx2, shunt compensation resistanceRp1, Rp2, roughly adjusted rheostat Rs1, Rs2, are all located on silicon frame, stress variation very little, so change in resistanceAlso very little；Four pressure drag force sensing resistances 6R1,6R2,6R3 and 6R4 constitute favour stone full-bridge circuit output electricityPressure reaction acceleration change, to achieve the purpose that acceleration analysis.
Since the present embodiment uses following technical proposals, the sensitivity of sensor output is substantially increased：
(1) since pressure drag force sensing resistance 6R1,6R2,6R3 and 6R4 are laid in the outer groove of sensitive diaphragm 18Edge 20 and inside groove edge 21, stress variation are maximum；
(2) crystal orientation where pressure drag force sensing resistance 6R1,6R2,6R3 and 6R4 is the maximum crystalline substance of piezoresistance coefficientTo；
(3) four pressure drag force sensing resistances 6R1,6R2,6R3 and 6R4 constitute favour stone full-bridge circuit.
As shown in fig. 7, quickly the process instance of zero adjustment is as follows：
Assuming that the resistance value of the single resistance of exclusion is R0, the resistance value R of four pressure drag force sensing resistances1、R2、R3、R4It is identical, Rx1、Rx2For series compensation exclusion, RP1、RP2For shunt compensation resistance, Rs1、Rs2For series connection coarse adjustment electricityResistance：R1=R2=R3=R4=r
Known to theory analysis：The maximum adjustable Standard resistance range of bridge arm
(Rx1+R1)max=R0+r
If a, both ends c power supply Ui, d, e are connected by spun gold,
Design resistance value R1=R2=R3=R4=r
And initial conditions, Rp1And Rp2, Rs1And Rs2, Rx1And Rx2Corresponding connection spun gold quantity is identical,Raec=2Rae, Rabc=2Rab, offset output int (Uo)=0
Because the temperature drift etc. of manufacturing process inconsistency and silicon materials leads to resistance value and differs, analyze for convenience,Only take relative variation, it is assumed that R1Changes delta r, R2, R3, R4It is still equal, i.e., it will generate offset output Uo',
It needs to measure R at this timeaeAnd RecResistance value, the quantity of control two bridge arms connection spun gold, to make as possibleBy UoIt is down to small quantity, eliminates this offset output.Such as assumeInitial connection spun gold is 8,The resistance value of bridge arm aeThe resistance value of bridge arm ec
Rae=Rec,
Design resistance value r=3R0, then the series connection exclusion R on n=2, bridge arm ecx2The six roots of sensation spun gold that breaks is hooked, is only retainedTwo spun gold connections.
If Δ r betides R2Or R4On, the Principles of Regulation of bridge arm ab and bc and above-mentioned identical.The resistance value of two-armExclusion control respectively is adjusted by two, adjustable range is wider, and the resistance value combination of two adjusting exclusions determines bridge armResistance value, so method is not unique, there are many schemes to carry out zero adjustment.
Above-described specific descriptions have carried out further the purpose, technical solution and advantageous effect of inventionIt is described in detail, it should be understood that above is only a specific embodiment of the present invention, for explaining this hairIt is bright, it is not intended to limit the scope of protection of the present invention, all within the spirits and principles of the present invention, is doneAny modification, equivalent substitution, improvement and etc. should all be included in the protection scope of the present invention.