CN209570661U - A kind of PN junction device impurity concentration/concentration gradient automatic measurement system - Google Patents
A kind of PN junction device impurity concentration/concentration gradient automatic measurement system Download PDFInfo
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Abstract
A kind of PN junction device impurity concentration/concentration gradient automatic measurement system, which includes: feed mechanism, for automatically delivering PN junction device to sample test platform；Fixinig plate, for fixing the both ends of PN junction device and keeping the good electrical contact between PN junction device electrode；Measurement module connects lock-in amplifier, and lock-in amplifier connects computer.Measurement module by the faint voltage division signal of acquisition circuit standard capacitance, be scaled the junction capacity of PN junction device and can real-time display go out PN junction device bias voltage-junction capacity relation curve；Automatic parameter transformation and fitting can be carried out to curve；And the type of PN junction is judged according to the related coefficient size of institute's fitting a straight line result；By the impurities concentration distribution coefficient or concentration gradient coefficient of the corresponding physical model conversion PN junction device of its type.The utility model is convenient to carry out the automatic detection of impurity concentration/concentration gradient of a large amount of PN junction samples, and counts to the uneven class size of the device in same batch products.
Description
Technical field
The utility model relates to the automatic test technology fields of semiconductor device parameter, more particularly, to a kind of PN junction device
Impurity concentration/concentration gradient automatic measurement system.
Background technique
Doping concentration distribution will directly affect its electrology characteristic in semiconductor devices.Generally according to required electrical properties,
Certain technique is used during the preparation process, artificially controls the important devices parameters such as impurity concentration/concentration gradient.Therefore, it is making
An extremely important problem is just become to the detection of Impurity Distribution in semiconductor devices after the completion of standby, it is on the one hand accurate efficient
Test method can verify that the validity of preparation process, on the other hand can also ensure the reliable of device parameters.Existing test doping
The technological means of concentration include using four probes, the gradually measurement methods such as the Hall effect of de-layer or Secondary Ion Mass Spectrometry, but
Device can be contacted/destroyed when measuring using aforesaid way, inevitably be will cause device damage, all belonged to the measurement damaged
Mode.
People prefer to by the way of lossless in actual measurement as a result, and current existing technological means includes optics
Detection method, such as: free-carrier Absorption measuring technique, (such as patent publication No. such as photocarrier radiometric technique
CN1971868, CN101159243, content involved by CN101527273A)；And electrical detection method, mainly include in principle
It is gone the case where calculating and obtain its impurities concentration distribution using the capacity effect of measurement semiconductor PN, main implemented method
Method (such as patent public affairs including carrying out capacitance measurement using LCR table (inductance-capacitnce resistance table) or dedicated capacitance measuring tester
Content involved by the number of opening 106093641A, CN206540992U).However it is needed in measuring device using the method for optical detection
Build more complicated optical system, be typically include light source, light path and optical detection system etc., cost that structure is complicated compared with
It is high；When in the way of electrical detection, required measuring device is although relatively simple, but measures signal-to-noise ratio and be easy by circuit noise etc.
The influence of uncertain parameter；The problems such as there are measurement data to need to carry out post-processing conversion, and the degree of the automation of measurement is lower；
And can not also parameter be summarized and be statisticallyd analyze in real time automatically after mass data measurement.Such as: automatic judgement PN junction
Type carries out abrupt junction and linear grading classification etc..
Summary of the invention
Technical problem to be solved in the utility model is in view of the above shortcomings of the prior art, to provide a kind of PN junction device
Impurity concentration/concentration gradient automatic measurement system, automatic measurement function provided by the utility model are convenient to carry out a large amount of PN
Tie sample the automatic detection of impurity concentration/concentration gradient, and conveniently to the uneven class size of the device in same batch products into
Row statistics.
The technical solution that the utility model is taken are as follows:
A kind of PN junction device impurity concentration/concentration gradient automatic measurement system, it is characterised in that the system includes feed machine
Structure, sample test platform, measurement module, lock-in amplifier, computer；
The driver of the feed mechanism connects computer, and feed mechanism is for automatically delivering PN junction device to sample test
Platform；The sample test platform connects measurement module, and sample test platform is equipped with fixed tabletting, for fixing the both ends of PN junction device
And the electrical contact between PN junction device electrode；The sample test platform connects measurement module；The measurement module connects locking phase
Amplifier, the lock-in amplifier connect computer.
The feed mechanism includes:
For being installed with the sample reel of PN junction device to be tested,
For guiding the guidance runner of PN junction device；
For furling the test reel for the PN junction device tested；
The sample reel connects the first rotating mechanism；
The test reel connects the second rotating mechanism, and second rotating mechanism connects driver by stepper motor,
The driver connects computer by RS232 serial ports or USB communication interface.
The sample test platform includes the pedestal with insulating surface and PN junction device fixing groove, and for fixing
One group of elastic pressuring plate of PN junction device and two end electrodes.
The measurement module includes: the test circuit for connecting with sample test platform；Standard electric for quantum chemical method
Hold C0；Measurement circuit for being detected to PN junction device；The signalling channel interfaces and reference channel of lock-in amplifier are provided
Interface；Basic interface circuit includes test device and standard capacitance C0Series loop；The reference signal of lock-in amplifier is made
For the pumping signal in entire circuit；Standard capacitance C0On measuring signal of the voltage division signal as lock-in amplifier；Measuring signal
Using voltage follower as connection buffer module between lock-in amplifier.
The computer, for realizing the operating parameter setting, the control of PN junction device bias, circulation measurement of lock-in amplifier
Parameter, measuring signal acquisition, data visualization.
A kind of PN junction device impurity concentration/concentration gradient method for automatic measurement, measurement module pass through fixed tabletting acquisition
PN junction device weak voltage signals, be scaled the junction capacity of PN junction device and can real-time display go out PN junction device bias voltage-knot
The relation curve of capacitor；Automatic parameter transformation and fitting further can be carried out to curve；And according to the phase of institute's fitting a straight line result
Coefficient magnitude is closed to judge the type of PN junction；By the impurities concentration distribution system of the corresponding physical model conversion PN junction device of its type
Several or concentration gradient coefficient.
The technical effect of the utility model is: by PN junction device impurity concentration/concentration gradient self-operated measuring unit
With the design of method, the measurement efficiency of PN junction device parameters is improved；Meanwhile different from the side based on LRC ammeter or capacitance meter
Method is conducive to inhibit system noise using the measurement method of coherent detection, more accurately to obtain measuring signal and device
Parameter.It is easy to operate when being measured using the invention to big metering device, high degree of automation.Compared to manually measuring,
The invention can also realize data acquisition, storage and online post-processing automatically；The measurement result of batch device can be sorted out
And statistics.On the one hand measurement efficiency is greatly improved, on the other hand can provide can not provide when only a small amount of sample test
Classification and statistical law.In addition, entire measuring system is easy to modularization, suitable for being integrated in industrial semiconductor detection device.
Detailed description of the invention
Fig. 1 is utility model device structural schematic diagram.
Fig. 2 is that schematic diagram is arranged in the COMPUTER PARAMETER of utility model device.
Fig. 3 is the utility model measuring method flow chart.
The PN junction device V of the same model batch of Fig. 4 (a) the utility model measurementR-CxOne of relation curve is typical to survey
Result figure is measured, which meets the physical model of abrupt junction after transformation.
Fig. 4 (b) is that Fig. 4 (a) is transformed to bias voltage VRWith 1/Cx 2Relationship shown in measurement result figure.
Fig. 4 (c) is that Fig. 4 (a) is transformed to bias voltage VRWith 1/Cx 3Relationship shown in measurement result figure.
Fig. 5 (a) is the PN junction device V of the same model batch of the utility model measurementR-CxOne typical case of relation curve
Measurement result figure one, the result meet the physical model of linear grading after transformation.
Fig. 5 (b) is the PN junction device V of the same model batch of the utility model measurementR-CxOne typical case of relation curve
Measurement result figure two, the result meet the physical model of linear grading after transformation.
Fig. 5 (c) is the PN junction device V of the same model batch of the utility model measurementR-CxOne typical case of relation curve
Measurement result figure three, the result meet the physical model of linear grading after transformation.
Fig. 6 is a typical consequence for carrying out automatic cluster in the PN junction device of same model batch according to related coefficient
Figure.
Specific embodiment
The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model
Clearly and completely describe.
As shown in Figure 1, a kind of PN junction device impurity concentration/concentration gradient automatic measurement system, the system include feed machine
Structure, sample test platform 2, measurement module 3, lock-in amplifier 4, computer 5.
The driver 6 of the feed mechanism connects computer 5, and feed mechanism is surveyed for automatically delivering PN junction device to sample
Test stand 2；The sample test platform 2 connects measurement module 3, and sample test platform 2 is equipped with fixed tabletting 7, for fixing PN junction device
The both ends of part and the electrical contact between PN junction device electrode；The sample test platform 2 connects measurement module 3；The measurement mould
Block 3 connects lock-in amplifier 4, and the lock-in amplifier 4 connects computer 5.
The feed mechanism includes:
For being installed with the sample reel 1.1 of PN junction device to be tested,
For guiding the guidance runner 1.2 of PN junction device；
For furling the test reel 1.3 for the PN junction device tested；
The sample reel 1.1 connects the first rotating mechanism；
The test reel 1.3 connects the second rotating mechanism, and second rotating mechanism is connected by stepper motor and driven
Device 6, the driver 6 connect computer 5 by RS232 serial ports or USB communication interface.
Driver 6 is mainly that the normal work of the stepper motor provides enough electric currents, the performed movement of driver 6
Instruction is generated by computer 5, and the instruction of execution movement includes rotation angle, direction of rotation and rotation speed etc., and passes through RS232
The modes such as serial ports or usb communication are transmitted.
The sample test platform 2 includes the pedestal with insulating surface and PN junction device fixing groove, and for solid
Determine one group of elastic pressuring plate of PN junction device and two end electrodes.
In actual operation, the working method of PN junction device example automatic feed is: one sample of every rotation of sample reel 1.1
Product, the PN junction device example tested will be pulled out under elastic pressuring plate by guidance runner 1.2, correspondingly a new PN junction device
Test sample will be pressed under elastic pressuring plate.PN junction device example is pressed in automatically on 2 pedestal of sample test platform by elastic pressuring plate
In fixing groove, and keep electrode contact good.
The measurement module 3 includes:
Test circuit for being connect with sample test platform 2；
Standard capacitance C for quantum chemical method0；Standard capacitance C0Using the monolithic capacitor of 10nF capacity.
Measurement circuit for being detected to PN junction device；
The signalling channel interfaces and reference channel interface of lock-in amplifier 4 are provided.
Basic interface circuit includes test device and standard capacitance C0Series loop；The reference of lock-in amplifier 4 is believed
Pumping signal number as entire circuit；Standard capacitance C0On measuring signal of the voltage division signal as lock-in amplifier 4；Measurement
Using voltage follower as connection buffer module between signal and lock-in amplifier 4.
The lock-in amplifier 4 is general or homemade circuit module, for realizing the phase of measuring signal and reference signal
Detection is closed, that is, has and will drown out the function that the signal extraction in noise comes out.Lock-in amplifier 4 uses Signal
The DSP7265 type two-phase lock-in amplifier of Recovery company
The computer 5, as shown in Fig. 2, can mainly be communicated with lock-in amplifier 4 and stepper motor driver 6,
Realize the running parameter setting of lock-in amplifier 4, the test bias voltage control of device, measuring signal the functions, Yi Jibu such as acquisition
The control etc. rotated into motor.The data collected of computer 5 can be converted to reverse biased-junction capacity relationship of PN junction device
Curve simultaneously carries out real-time display, updates；Automatic parameter transformation and fitting can be carried out to experiment curv；It can be intended according to transformation data
The related coefficient size of straight line is closed to judge automatically the type of PN junction device, and by its type calculate impurities concentration distribution coefficient or
Impurity concentration gradient coefficient.When carrying out a large amount of sample automatic measurements, the class of same batch of sample can be also provided automatically by related coefficient
Type distribution, provides the statistical information that a small amount of sample manual test can not provide.
A kind of PN junction device impurity concentration/concentration gradient method for automatic measurement, comprising the following steps:
Step 1: a simulation output end of lock-in amplifier 4 is arranged, as PN to be measured in connection 4 module of lock-in amplifier
The running parameter of lock-in amplifier 4 and the running parameter of loop test is arranged in the reverse bias voltage of junction device.Such as: ginseng
Examine frequency, the amplitude etc. of signal；And the running parameter of loop test, such as: the variation range of reverse bias voltage size, number
Strong point number and every time of integration etc..
Step 2: for a PN junction device, starting the work of measurement: gradually changing bias voltage value, waits corresponding
The time of integration reads the signal amplitude in lockin signal channel；In conjunction with the acceptance of the bid of measurement module 3 pseudo-capacitance C0Value and impedance partial pressure
Measuring signal is converted to PN junction device junction capacitance by proportionate relationship.
Step 3: computer 5 stores the relation data of bias voltage and junction capacity and draws curve at interface；It simultaneously will knot
Capacitor initial data is converted to capacitor square inverse and the capacitor cube relationship reciprocal between bias voltage, then respectively to change
The data changed carry out linear fit.
Step 4: the related coefficient size obtained according to fitting result judges automatically the type of PN junction, comprising: abrupt junction
And linear grading, it is such as classified as abrupt junction model, then calculates the low-doped side impurities concentration distribution coefficient of PN junction device；Such as return
For linear grading model, then the concentration gradient coefficient of PN junction device is calculated.
When carrying out a large amount of sample automatic measurements, additionally it is possible to provide the type distribution of same batch of sample automatically by related coefficient.
Embodiment:
Below to use a kind of impurity concentration/concentration gradient automatic measurement system of PN junction device of the utility model,
For surveying a kind of PN junction sample, the measurement method of the utility model is discussed in detail.
The step of specific measurement method, is as follows, and process is as shown in Figure 3:
1: sample loads initialization: the sample reel 1.1 of PN junction device being fixed in rotating mechanism, hand guided reel
Preceding several components of paper tape are by elastic pressuring plate and are loaded in test reel 1.3；Test the rotation of reel 1.3 and debugging step
Into motor corner, the parameters such as revolving speed, to ensure that subsequent device can preferably be caught in the lower section of elastic pressuring plate.
2: RS232 serial ports or USB initialization: can be used in connection computer 5 and lock-in amplifier 4, specific connection type
The mode of communication；After successful connection, the running parameter of lock-in amplifier 4 is set；The signal-to-noise ratio etc. for usually meeting measurement is wanted
It asks, it is ensured that the smooth degree of experiment curv selects the frequency for testing signal to test the amplitude size of signal in 30kHz or more
VtFor the work for not influencing practical reverse biased, it is set in 0.1V or so.
The scanning range and points of reverse biased are set, such as: for reverse biased range from 0V-10V, data point includes 200
It is a.It is automatic to calculate bias voltage V required every time in loop test according to bias range and number of test points in computer 5R；
By the time constant T of lock-in amplifier 4c, representative value is about in 500ms, automatic calculating measurement in the waiting of each data point
Between dT.After the parameters such as frequency, amplitude and the every waiting time of the test and excitation signal such as replacement different shaped PN junction device,
Debugging need to be re-started, to ensure experiment curv smooth-shaped and there is preferable signal-to-noise ratio.
3: starting the cycle over test, acquisition data and plot and display；According to test logic, a bias voltage is set first
VR, the dT time is then waited, measuring signal V is then readiAmplitude.It, can be according to series loop impedance point for each range value
The relationship and standard capacitance C of pressure0Numerical value, equal proportion is converted to barrier capacitance Cx, transformational relation is (Vi/Vt)*C0.Software
When cycle operation can real-time rendering go out VR-CxRelation curve.Fig. 4 (a) gives a VR-CxThe typical measurement of relation curve
As a result.Curve can be transformed to bias voltage V respectivelyRWith 1/Cx 2And 1/Cx 3Relationship, see and measure number shown in Fig. 4 (b), Fig. 4 (c)
According to.Then it carries out linear fit respectively again, obtains the linear fits result such as slope, related coefficient.It is cyclically updated after being measured
Bias voltage conditions re-start test again.
4: curve cluster: due to manufacture craft difference, common PN junction device model includes abrupt junction or linear grading.If
VR-1/C2The related coefficient of data linear fit is R1, VR-1/C3The related coefficient of data linear fit is R2.Work as R1>R2When, it says
Bright VR-1/C2The linear fit effect of data is more preferable, should be classified as abrupt junction model, such as Fig. 4 (b), Fig. 4 (c) measurement data, wherein 4
(b) the linearity is considerably better.
Fig. 5 (a), Fig. 5 (b), Fig. 5 (c), which give in the PN junction device of a same model batch, meets abrupt junction model
Typical measurement result.Wherein the linearity of Fig. 5 (c) is more preferable, i.e. R1<R2, V at this timeR-1/C3The linear fit effect of data is more
It is good, linear grading model should be classified as.
5: coefficient solves:
1) low-doped side impurities concentration distribution coefficient N in abrupt junction model is solvedD: according to the semiconductor of p-n junction device
It exhausts shelf theory and knows that there are following relationships: barrier capacitanceWhereinIt is dense for reduction
Degree, A are interface area.Therefore,I.e. for abrupt junction model, VRWith 1/Cx 2It is in a linear relationship.By
Straight slope (is equal to) doping reduced concentration N can be found out*.For one-sided step junction model, reduced concentration N*It can be by
Low-doped side concentration NDSubstitution.Furthermore contact potential V can also be found out by Linear interceptD。
2) it solves the impurity concentration gradient distribution of linear grading: shelf theory equally being exhausted by PN junction device semiconductor, it is right
In its barrier capacitance of linear gradingWherein: G is impurity concentration gradient.Therefore,I.e. for linear grading, VRWith 1/Cx 3It is in linear relation.Similarly, (it is equal to by straight slope) and intercept can find out impurity concentration gradient G and VD.Wherein, the mode for converting data fitting a straight line uses standard
Least square method carries out linear fit.
6: after measurement, system replaces next sample automatically, and the specific embodiment of the system returns to step 2 simultaneously
It is recycled.
According to the above method, statistics and analysis is carried out to the model of the PN junction device of same model batch after automatic measurement,
Such as to transformation data related coefficient measurement result carry out clustering, Fig. 6 give in the PN junction device of same batch by
The typical consequence of automatic cluster is carried out according to related coefficient, this result is convenient for further quantifying the process variations such as doping.
The above description is only the embodiments of the present invention, is not intended to limit the utility model, for this field
Technical staff for, various modifications and changes may be made to the present invention；Within the spirit and principle of the utility model,
Any modification, equivalent substitution, improvement and etc. at place should be included within the scope of the claims of the utility model.
Claims (6)
1. a kind of PN junction device impurity concentration/concentration gradient automatic measurement system, it is characterised in that: the system includes feed machine
Structure, sample test platform, measurement module, lock-in amplifier, computer；
The driver of the feed mechanism connects computer, and feed mechanism is for automatically delivering PN junction device to sample test
Platform；
The sample test platform connects measurement module, and sample test platform is equipped with fixed tabletting, for fixing PN junction device
Both ends and the electrical contact between PN junction device electrode；The sample test platform connects measurement module；The measurement module connects
Lock-in amplifier is connect, the lock-in amplifier connects computer.
2. a kind of PN junction device impurity concentration/concentration gradient automatic measurement system according to claim 1, feature exist
In: the feed mechanism includes:
For being installed with the sample reel of PN junction device to be tested, for guiding the guidance runner of PN junction device；
For furling the test reel for the PN junction device tested.
3. a kind of PN junction device impurity concentration/concentration gradient automatic measurement system according to claim 1, feature exist
In: the sample reel connects the first rotating mechanism；
The test reel connects the second rotating mechanism, and second rotating mechanism connects driver by stepper motor, described
Driver connects computer by RS232 serial ports or USB communication interface.
4. a kind of PN junction device impurity concentration/concentration gradient automatic measurement system according to claim 1, feature exist
In: the sample test platform includes the pedestal with insulating surface and PN junction device fixing groove, and for fixing PN
One group of elastic pressuring plate of junction device and two end electrodes.
5. a kind of PN junction device impurity concentration/concentration gradient automatic measurement system according to claim 1, feature exist
In: the measurement module includes: the test circuit for connecting with sample test platform；Standard capacitance C 0 for quantum chemical method
；
Measurement circuit for being detected to PN junction device；The signalling channel interfaces and reference channel of lock-in amplifier are provided
Interface；
Basic interface circuit includes the series loop for testing device and standard capacitance C 0；The reference signal of lock-in amplifier
Pumping signal as entire circuit；Measuring signal of the voltage division signal as lock-in amplifier on standard capacitance C 0；Measurement
Using voltage follower as connection buffer module between signal and lock-in amplifier.
6. a kind of PN junction device impurity concentration/concentration gradient automatic measurement system according to claim 1, feature exist
In: the computer, for realizing the operating parameter setting of lock-in amplifier, PN junction device bias voltage control, circulation measurement ginseng
Number, measuring signal acquisition, data visualization.
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| CN109490744A (en) * | 2018-12-14 | 2019-03-19 | 北京航空航天大学 | A kind of PN junction device impurity concentration/concentration gradient automatic measurement system and method |
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| CN109490744A (en) * | 2018-12-14 | 2019-03-19 | 北京航空航天大学 | A kind of PN junction device impurity concentration/concentration gradient automatic measurement system and method |
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