The method for making of a kind of MEMS pressure resistance type pressure chip and sensor
Technical field
The present invention relates to field of semiconductor manufacture, the method for making of particularly a kind of MEMS pressure resistance type pressure chip and sensor.
Background technology
At present, generally adopt the pressure resistance type pull pressure sensor to measure the suffered pressure of horizontal direction.The pressure resistance type pull pressure sensor is formed structure and comprised the two large divisions: elastic sensing element and resistance are pressed and are become sheet.Wherein, elastic sensing element is a sensitive element, can design or choice structure and form according to measured parameter; It is the conversion element that the pressure that horizontal direction is suffered converts resistance variations to that resistance is pressed the effect that becomes sheet; It is the core parts of pressure resistance type pull pressure sensor that resistance is pressed the change sheet.The elastic sensing element effect lower surface of pressure in the horizontal direction produces strain.The resistance that causes sticking on the elastic sensing element surface presses the resistance value that becomes sheet to change.Thereby press the resistance change that becomes sheet through measuring resistance, confirm the size of measured parameter.Resistance presses the change sheet can be divided into according to material type: tinsel, paper tinsel metal crimp become sheet and semiconductor is pressed change sheet etc.Resistance is pressed and is become sheet is pressed change sheet pull pressure sensor as resistance-type most critical ingredient.Many in the prior art with paper tinsel metal crimp change sheet; But because the paper tinsel metal crimp becomes the processing technology complicacy of sheet, even needs manual process, so the pressure resistance type pull pressure sensor of using the paper tinsel metal crimp to become sheet exists the production difficulty big; Cost is higher, can't realize low-cost production in enormous quantities the in enormous quantities.Along with development of semiconductor, microelectromechanical systems (MEMS) pressure transducer arises at the historic moment, and mainly is divided into MEMS piezoresistive pressure sensor and MEMS capacitance pressure transducer; The both is the micromechanics electronic sensor that generates on the wafer of silicon substrate having; The output signal that the MEMS piezoresistive pressure sensor has is big, and subsequent treatment is simple, and chip volume is little; Advantage such as be easy to produce in enormous quantities and with low cost, be widely used gradually.In the prior art, the resistance of most critical pressure change sheet partly is to be pressed by the semiconductor of semi-conducting material manufacturing to become sheet in the MEMS pressure resistance type pull pressure sensor, is called MEMS pressure resistance type pressure chip again; It is a rectangle structure; Comprise a square sense film and support section on every side, four voltage dependent resistor (VDR)s that the central area of sense film has are formed resistance bridge as power electricity conversion metering circuit, change like no pressure; It is output as zero, power consumption hardly.Adopt the MEMS pressure resistance type pull pressure sensor of resistance bridge, higher measuring accuracy, lower power consumption and extremely low cost.
Sense film and voltage dependent resistor (VDR) are to be made on silicon substrate with semiconductor technology; Silicon substrate is the crystal of semiconductor material; When receiving external force effect meeting on crystalline axis direction, sense film produces stress; Carrier mobility takes place and changes in the inner charge carrier of silicon substrate under stress, because carrier mobility has determined the resistance value of voltage dependent resistor (VDR) on the silicon substrate, thereby measure the suffered pressure of horizontal direction through the resistance change of voltage dependent resistor (VDR) composition electric bridge.
In the prior art; Elder generation is that the wafer device side of the N type silicon substrate 100 of electronics forms oxide layer 101 as insulation course at the conduction type that provides; Adopting diffusion technique then is that the p type impurity in hole is diffused in the silicon substrate 100 of oxide layer 101 belows with conduction type; Form one deck P-type conduction layer 102 as thin as a wafer as voltage dependent resistor (VDR), behind etching fairlead above the P-type conduction layer 103, splash-proofing sputtering metal aluminium is processed electrode 103 in fairlead then; Draw lead 104 from electrode 103 tops with ultrasound wave or the welding of hot bonding method again, finally process the cross-sectional view of MEMS pressure resistance type pressure chip as shown in Figure 1.The advantage of this MEMS pressure resistance type pressure chip is a good stability; Mechanical hysteresis and creep are little; Temperature-coefficient of electrical resistance is also than the little one magnitude of general semiconductor gauge, the diffusion technique application of MEMS pressure resistance type pull pressure sensor that in silicon substrate, formed issues limit such as the consistance of voltage dependent resistor (VDR) is poor, leakage current is restive but shortcoming is.
Summary of the invention
In view of this, the technical matters that the present invention solves provides the method for making of a kind of MEMS pressure resistance type pressure chip and sensor thereof, improve voltage dependent resistor (VDR) consistance, reduce leakage current, solve the consistency problem in producing in batches.
For addressing the above problem, technical scheme of the present invention specifically is achieved in that
A kind of method for making of MEMS pressure resistance type pressure chip, provide one have a N type silicon substrate wafer, this method comprises:
Wafer device side and back side growth oxide layer at wafer;
The silicon substrate intermediate ion of the said oxide layer below of wafer device side injects and forms voltage dependent resistor (VDR);
Diffuse to form p type district around the said voltage dependent resistor (VDR);
The said oxide layer and the silicon substrate of corrosion chip back surface form sense film;
After etching was positioned at the oxide layer formation fairlead of the wafer device side above the said p type district, splash-proofing sputtering metal was processed lead in fairlead, and said lead is electrically connected said voltage dependent resistor (VDR) and forms resistance bridge;
MEMS pressure resistance type pressure chip is isolated in scribing.
Said silicon substrate is (100) crystal face.
Said voltage dependent resistor (VDR) is divided into two groups according to the crystal orientation, and one group is the voltage dependent resistor (VDR) of forming class along the equivalent crystal orientation of [01-1] crystal orientation or its, another group for along [011] crystal orientation or its equivalent crystal orientation form the voltage dependent resistor (VDR) of class.
The material that said ion injects is the ion of boron ion or other III major elements, and said ion implantation dosage is 2E18 atom/square centimeter.
The said p of diffuseing to form type district is the diffused with boron ion, and the dosage of said diffusion is 5E19 atom/square centimeter.
A kind of method for making of MEMS pressure resistance type pull pressure sensor, provide one have a N type silicon substrate wafer, the metallic substrates of pcb circuit board and rectangle structure, this method comprises:
Wafer device side and back side growth oxide layer at wafer;
The silicon substrate intermediate ion of the said oxide layer below of wafer device side injects and forms voltage dependent resistor (VDR);
Diffuse to form p type district around the said voltage dependent resistor (VDR);
The said oxide layer and the silicon substrate of corrosion chip back surface form sense film;
After etching was positioned at the oxide layer formation fairlead of the wafer device side above the said p type district, splash-proofing sputtering metal was processed lead in fairlead, and said lead is electrically connected said voltage dependent resistor (VDR) and forms resistance bridge;
MEMS pressure resistance type pressure chip is isolated in scribing;
Bonding said MEMS pressure resistance type pressure chip on the said metallic substrates;
Said pcb circuit board is bonded to said metallic substrates, the lead of MEMS pressure resistance type pressure chip is electrically connected with the pcb circuit board;
The MEMS pressure resistance type pressure chip that exposes is partly carried out the embedding protection, the lead of PCB circuit board is drawn.
Said silicon substrate is (100) crystal face.
The number of said voltage dependent resistor (VDR) is four, and it is parallel that class is formed in two said voltage dependent resistor (VDR) [01-1] crystal orientation, edge or its equivalent crystal orientation, and it is parallel that class is formed in two other said voltage dependent resistor (VDR) [011] crystal orientation, edge or its equivalent crystal orientation.
The material that said ion injects is the ion of boron ion or other III major elements, and said ion implantation dosage is 2E18 atom/square centimeter.
The said p of diffuseing to form type district is the diffused with boron ion, and the dosage of said diffusion is 5E19 atom/square centimeter.
Visible by above-mentioned technical scheme, MEMS pressure resistance type pressure chip and sensor production method that the present invention proposes are significantly improved the consistance of voltage dependent resistor (VDR), reduce the output at zero point and the zero temperature drift of the resistance bridge that above-mentioned voltage dependent resistor (VDR) forms; With sense film with above-mentioned resistance bridge as semiconductor gauge; Solve the problem that consistance is poor, stability is low and leakage current is restive of MEMS pressure resistance type pressure chip and sensor thereof, also improved the making yield rate of MEMS pressure resistance type pressure chip and sensor thereof.
Description of drawings
Fig. 1 is the cross-sectional view of MEMS pressure resistance type pressure chip in the prior art;
Fig. 2 is the making step process flow diagram of MEMS pressure resistance type pressure chip of the present invention;
Fig. 3 is the circuit diagram of four voltage dependent resistor (VDR) composition resistance bridges in the MEMS pressure resistance type pressure chip of the present invention;
Fig. 4 is the making step process flow diagram of MEMS pressure resistance type pull pressure sensor of the present invention;
Fig. 5 is a MEMS pressure resistance type pull pressure sensor structural drawing of the present invention.
Embodiment
For make the object of the invention, technical scheme, and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, to further explain of the present invention.
The present invention proposes the method for making of a kind of MEMS pressure resistance type pressure chip and sensor thereof, the making step process flow diagram of the MEMS pressure resistance type pressure chip of the present invention shown in following detailed description Fig. 2:
The layout design of step 200, MEMS pressure resistance type pressure chip is found out the optimum position of the voltage dependent resistor (VDR) on the sense film through emulation;
The structure of the MEMS pressure resistance type pressure chip of prior art comprises: have the sense film of making on the wafer of silicon substrate, four voltage dependent resistor (VDR)s, the lead that connects voltage dependent resistor (VDR) and the support sections around the sense film; Wherein, Four voltage dependent resistor (VDR)s are positioned on the sense film, and being electrically connected by lead is connected into resistance bridge.
The wafer device side of step 201, silicon substrate and back side growth oxide layer;
In this step, provide one to have N type silicon substrate and be of a size of 4 inches wafer, in the prior art, the one side of growing semiconductor device on the wafer is become device side, the opposite face of device side is called the back side.After on (100) of silicon substrate crystal face wafer device side and the back side being carried out twin polishing and cleans; Silicon substrate is put into boiler tube; Furnace tubing aerating oxygen time the in boiler tube; The oxide layer of growing simultaneously at the wafer device side of silicon substrate and the back side, through heating-up temperature, oxygen flow and the heat time heating time of adjustment boiler tube control thickness of oxide layer, this step is a prior art, repeat no more.
Step 202, ion implantation technology form four voltage dependent resistor (VDR)s in silicon substrate;
In this step; Voltage dependent resistor (VDR) is arranged in the oxide layer below of silicon substrate wafer device side; The material that ion injects is the ion of boron ion or other III major elements; Ion implantation dosage is 2E18 atom/square centimeter, and the energy that ion injects makes ion inject the below that the voltage dependent resistor (VDR) that forms is positioned at the oxide layer of wafer device side by the thickness of oxide layer decision of step 201 growth; It should be noted that; The voltage dependent resistor (VDR) of making in this step is divided into two groups according to the crystal orientation; As shown in Figure 3, one group is the voltage dependent resistor (VDR) 301 of forming class along the equivalent crystal orientation of [01-1] crystal orientation or its, another group for along [011] crystal orientation or its equivalent crystal orientation form the voltage dependent resistor (VDR) 302 of class.Voltage dependent resistor (VDR) of the present invention adopts ion injection method to make, because the control accuracy of the implantation dosage of ion implantation technology is higher than traditional diffusion technique far away, therefore can significantly improve the consistance of voltage dependent resistor (VDR), reduces output at zero point and zero temperature drift.
The diffused with boron ion forms p type district around step 203, the voltage dependent resistor (VDR);
Adopt traditional diffusion technique in this step; The dosage of diffused with boron ion is 5E19 atom/square centimeter, and the dosage of comparing boron ion in this step of ion implantation dosage of step 202 is bigger, so the carrier concentration in the p type district that forms in this step is bigger; Resistance is littler; P type district around the voltage dependent resistor (VDR) can be used as the bonding pad of voltage dependent resistor (VDR), and subsequent step 205 is electrically connected voltage dependent resistor (VDR) and lead through p type district after etching fairlead and splash-proofing sputtering metal above the p type district form lead.Before the step 203 or after the step 203 before the step 204, can also in the silicon substrate between the adjacent voltage dependent resistor (VDR), spread the ion formation n+ isolated area of P elements after the step 202, be used for the isolation between the voltage dependent resistor (VDR).
Step 204, corrosion chip back surface form sense film;
In this step, with the oxide layer and the silicon substrate of potassium hydroxide (KOH) solution corrosion chip back surface, attenuate oxide layer and silicon substrate form sense film.After this step is accomplished, in order to guarantee also to need further inspection sense film thickness to corroding the sense film quality that the back forms.
Behind the etching fairlead, splash-proofing sputtering metal is made lead in fairlead on step 205, the sense film, accomplishes being electrically connected of voltage dependent resistor (VDR);
In this step; Etching fairlead in the oxide layer above p type island region; The method of etching fairlead and splash-proofing sputtering metal is a prior art, and this repeats no more, and it should be noted that; Splash-proofing sputtering metal as shown in Figure 3 forms the lead that alloy processes and is divided into two types: internal connecting line 303 and connect lead 304 outward; Wherein, two internal connecting lines 303 crystal orientation is identical two end of voltage dependent resistor (VDR) on the same group link to each other with the head and the tail two ends of a voltage dependent resistor (VDR) with different crystal orientations respectively, and two other internal connecting line 303 above-mentioned crystal orientation is identical two other end of voltage dependent resistor (VDR) on the same group links to each other with the head and the tail two ends of another voltage dependent resistor (VDR) with different crystal orientations respectively; Draw outside coupled four from four internal connecting lines respectively again and connect lead 304; To connect lead 304 outward and be divided into two groups; Wherein, Connect and draw two on two internal connecting lines of different voltage dependent resistor (VDR)s to connect lead 304 outward be one group, one group of output terminal when measuring arm resistance, another is organized as input end; With four voltage dependent resistor (VDR)s and in connect, connect the closed-loop path that lead forms outward and be called resistance bridge.
MEMS pressure resistance type pressure chip is isolated in step 206, scribing.
Semiconductor fabrication process can be made a plurality of MEMS pressure resistance type pressure chip structures simultaneously on a wafer, therefore need scribing to isolate each independently MEMS pressure resistance type pressure chip.
So far, the making step of MEMS pressure resistance type pressure chip is accomplished.
Below in conjunction with MEMS pressure resistance type pull pressure sensor structure shown in Figure 5, the manufacturing process of MEMS pressure resistance type pull pressure sensor in the key diagram 4, concrete steps are following.
The metallic substrates 501 of step 401, employing rectangle structure, bonding MEMS pressure resistance type pressure chip 503 on metallic substrates 501;
In this step, MEMS pressure resistance type pressure chip 503 is MEMS pressure resistance type pressure chips 503 that above-mentioned steps 200 is made to step 206, and its making step repeats no more.
Step 402, bonding switching pcb circuit board 502 draw the lead that connects MEMS pressure resistance type pressure chip and are electrically connected with pcb circuit board 502 to metallic substrates 501;
Step 403, MEMS pressure resistance type pressure chip 503 parts that expose are carried out embedding protection, the lead on the pcb circuit board 504 is drawn;
In this step, it is blocked up or thin excessively to it should be noted that the embedding protection is difficult for, to guarantee to process the consistance of MEMS pressure resistance type pull pressure sensor.
So far, MEMS pressure resistance type pull pressure sensor is made and is finished.In order to check whether MEMS pressure resistance type pull pressure sensor can accurately measure pressure, also need carry out device and detect, for example the output of the inspection resistance bridge arm resistance of step 404 and zero point it.
Step 404, detection resistance bridge arm resistance and output at zero point;
In this step, in the MEMS pressure resistance type pressure chip that MEMS pressure resistance type pull pressure sensor is used, four resistance bridges that voltage dependent resistor (VDR) is formed, the detection method of its arm resistance and output at zero point is a prior art, this repeats no more,
After the final detection of step 405, completion MEMS pressure resistance type pull pressure sensor, with MEMS pressure resistance type pull pressure sensor dress box and warehouse-in.
The present invention proposes the method for making of a kind of MEMS pressure resistance type pressure chip and sensor; This method adopts ion injection method in silicon substrate, to make voltage dependent resistor (VDR); The resistance bridge that the voltage dependent resistor (VDR) of using this method to make is formed; Because the control accuracy of the implantation dosage of ion implantation technology is higher than traditional diffusion technique far away,, reduce the output at zero point and the zero temperature drift of the resistance bridge of above-mentioned voltage dependent resistor (VDR) composition so significantly improve the consistance of voltage dependent resistor (VDR); With sense film with above-mentioned resistance bridge as semiconductor gauge; Thereby solved the problem that consistance is poor, stability is low and leakage current is restive of MEMS pressure resistance type pressure chip and sensor thereof, also improved the making yield rate of MEMS pressure resistance type pressure chip and sensor thereof.
The above is merely preferred embodiment of the present invention, and is in order to restriction the present invention, not all within spirit of the present invention and principle, any modification of being made, is equal to replacement, improvement etc., all should be included within the scope that the present invention protects.