阅读说明：本技术 高通量材料的表征方法 (Method for characterizing high-throughput materials ) 是由 王志强 张桂英 刘烁 董建设 于 2019-09-29 设计创作，主要内容包括：本发明涉及一种高通量材料的表征方法,包括电路设计步骤；材料-电路混合制备步骤；材料性能参数计算步骤。本发明可实现对多个样品物理参数的快速扫描式测量,从而建立一种高效率的高通量材料表征方法。本发明将把测量电路和被测材料融为一体,使每个高通量材料单元作为电路的一部分,只有这样才能实现高精度、快速测量。本发明对于每一个样品,可以一次性测量多个物理性质,实现对多种物理参数的协同表征。采用范德堡法作为基本测量单元,通过设置适当的测量策略,该电路可实现电阻率、霍尔电压、载流子迁移率等参数的测量。(The invention relates to a method for characterizing a high-flux material, which comprises the steps of circuit design; a material-circuit mixing preparation step; and calculating material performance parameters. The invention can realize the rapid scanning type measurement of the physical parameters of a plurality of samples, thereby establishing a high-efficiency high-flux material characterization method. The invention integrates the measuring circuit and the measured material into a whole, and each high-flux material unit is used as a part of the circuit, so that high-precision and quick measurement can be realized. The invention can measure a plurality of physical properties for each sample at one time, and realize the cooperative characterization of a plurality of physical parameters. The Van der Ware method is adopted as a basic measuring unit, and the circuit can realize the measurement of parameters such as resistivity, Hall voltage, carrier mobility and the like by setting a proper measuring strategy.)

1. A method of characterizing a high-throughput material, comprising:

comprises a circuit design step;

comprises a material-circuit mixing preparation step;

the method comprises a material performance parameter calculation step.

2. The method of characterizing a high-throughput material of claim 1, wherein: the circuit design step comprises the following circuit design steps:

the measuring unit circuit is used for measuring the electrical characteristics of the sample by adopting a Van der Pauw method;

the selection circuit is used for measuring a single sample;

and the interface circuit is used for realizing the switching of circuit signals to the computer.

3. The method for characterizing a high-throughput material according to claim 2, wherein: the measuring unit circuit is connected with the measuring unit circuit,

the device comprises a U1 unit, a voltage acquisition unit and a control unit, wherein the U1 unit is composed of AD524, a capacitor of 0.1uf and a resistor of 1000K and is used for performing gain amplification of 1000 times on an acquired voltage signal;

the circuit comprises a U2 unit and a U3 unit, and is two buffers, each buffer is composed of two AD795S units and is used for reducing direct-current voltage on an operational amplifier input end R1;

the device comprises a U4 unit, an AD630 square wave demodulator and a lock-in amplifier, wherein the U4 unit is formed by the AD630 square wave demodulator and is used for designing the lock-in amplifier;

the digital gain control circuit comprises a U5 unit and an AD711 programming gain instrument amplifier, wherein the fixed gain of the U5 unit is 1, 10, 100 or 1000 respectively, and a digital input end is selected;

the power amplifier comprises a U6 unit, is a bipolar operational amplifier and provides gain for the pico ampere level current through the function of internal compensation;

the U7 cell is included and is a relay to avoid situations where the input impedance is too low to cause the circuit to fail.

4. The method of characterizing a high-throughput material of claim 1, wherein: the material-circuit mixed preparation step is to manufacture a parallel measurement circuit part by adopting a circuit manufacturing process, reserve a sample area to be measured, and directly manufacture the display sample to be measured at the designated position of the measurement circuit by adopting a material high-flux preparation technology.

5. The method of characterizing a high-throughput material of claim 4, wherein: the high-flux preparation technology of the material comprises a jet printing synthesis method, a multi-element material diffusion method, a micro-electromechanical structure method, a micro-fluid structure method and a laser material increase method.

6. The method of characterizing a high-throughput material of claim 1, wherein: the material performance parameter calculation comprises material resistance calculation, and the formula is as follows:

in the formula, I is the current provided by the constant current source, V₁，V₂Respectively, the voltage values obtained by two measurements, f (V)₁/V₂) Is the van der Pauw coefficient.

7. The method of characterizing a high-throughput material of claim 1, wherein: the material performance parameter calculating step comprises the calculation of a material Hall coefficient, and the formula is as follows:

wherein B is the magnetic induction perpendicular to the sample, Δ V_pnRepresenting the change in potential difference between P, N after application of the magnetic field, I is the charge of the particles and d is the sample thickness.

8. The method of characterizing a high-throughput material of claim 1, wherein: the material performance parameter calculation step comprises the calculation of material mobility, and the formula is as follows:

wherein n and p are the concentrations of electrons and holes, respectively, in the semiconductor material_nAnd mu_pQ is the charge amount and ρ is the resistivity, which are the mobilities of electrons and holes.

Technical Field

The invention belongs to the field of high-flux materials, relates to measurement of material performance parameters, and particularly relates to a characterization method of a high-flux material.

Background

The high-flux material is characterized in that a large number of material samples containing different components are prepared at one time, and data such as the components, microstructures, macroscopic properties and the like of the different materials are rapidly acquired by a parallel processing method, so that a mapping relation of the three is established, and rapid material optimization is finally realized.

After the high-flux material is prepared, the next step is to measure the material performance parameters, so as to obtain a mapping table of material components-macroscopic performance parameters. It should be noted that the high flux material is usually a thin film material with a thickness of several tens of nanometers to several tens of micrometers.

Currently, high throughput characterization techniques based on optical methods are evolving vigorously. For example, Lawrence Berkeley National Laboratory integrated micro-area X-ray fluorescence and diffraction system in the United states develops a micro-area evanescent microwave probe microscope, has the spatial resolution of 10 mu m, and can simultaneously detect the components and the structure of a high-flux material. Professor L.Asinovski of the university of Maryland in America reports an entire sample characterization method based on an ellipsometry imaging technology, and high-throughput characterization of the thickness and the refractive index of an array sample can be realized. Except for the surface imaging ellipsometry analysis technology, the laser ellipsometer, the cathode fluorometer and the like can realize the high-flux micro-area optical property characterization.

Although the optical method-based high-throughput material characterization method has wide application, the method also has some defects. Firstly, different materials have different spectral characteristics, so different light sources and spectral means are selected according to different materials; secondly, electromagnetic waves cannot generally penetrate metals and polar media, so the characterization means by transmitted light cannot be used for these materials; finally, the measurement means based on laser interference and phase analysis have very high requirements on environmental temperature, humidity and vibration stability, which limits the large-scale use of the device to a certain extent.

High throughput characterization techniques based on electrical methods have developed relatively late. In 2005, professor k.c. hewitt, university of dalhousii, canada, developed a method of measuring the electrical properties of a 7 x 7 thin film sample library using a 28 x 28 array of probes, each sample having four probes in contact therewith, and then by means of contact. Similar contact-based measurement systems have also been made by the american marine national laboratory. Israel Bar Ilan university developed a multi-sample measurement scheme that utilized a set of probes scanned by an electromechanical device.

Although the method can realize rapid measurement, the sample size is not likely to be too small due to the contact mode of the contact points, the contact resistance, the geometrical size of the probe and other factors (the size of each sample is 8mm multiplied by 8 mm).

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a high-flux material characterization method taking a parallel circuit as a measurement means, and realizes the electrical property characterization of typical materials.

The technical scheme adopted by the invention for solving the technical problem is as follows:

a method for characterizing a high-throughput material,

comprises a circuit design step;

comprises a material-circuit mixing preparation step;

the method comprises a material performance parameter calculation step.

Moreover, the circuit design step includes the following circuit design steps:

the measuring unit circuit is used for measuring the electrical characteristics of the sample by adopting a Van der Pauw method;

the selection circuit is used for measuring a single sample;

and the interface circuit is used for realizing the switching of circuit signals to the computer.

Furthermore, the circuit of the measuring unit,

the device comprises a U1 unit, a voltage acquisition unit and a control unit, wherein the U1 unit is composed of AD524, a capacitor of 0.1uf and a resistor of 1000K and is used for performing gain amplification of 1000 times on an acquired voltage signal;

the circuit comprises a U2 unit and a U3 unit, and is two buffers, each buffer is composed of two AD795S units and is used for reducing direct-current voltage on an operational amplifier input end R1;

the device comprises a U4 unit, an AD630 square wave demodulator and a lock-in amplifier, wherein the U4 unit is formed by the AD630 square wave demodulator and is used for designing the lock-in amplifier;

the digital gain control circuit comprises a U5 unit and an AD711 programming gain instrument amplifier, wherein the fixed gain of the U5 unit is 1, 10, 100 or 1000 respectively, and a digital input end is selected;

the power amplifier comprises a U6 unit, is a bipolar operational amplifier and provides gain for the pico ampere level current through the function of internal compensation;

the U7 cell is included and is a relay to avoid situations where the input impedance is too low to cause the circuit to fail.

And the material-circuit mixed preparation step is to manufacture a parallel measurement circuit part by adopting a circuit manufacturing process, reserve a sample area to be measured, and directly manufacture the sample array to be measured at the designated position of the measurement circuit by adopting a material high-flux preparation technology.

The high-flux preparation technology of the material comprises a jet printing synthesis method, a multi-element material diffusion method, a micro-electromechanical structure method, a micro-fluid structure method and a laser material increase method.

Moreover, the calculation of the material performance parameters comprises the calculation of material resistance, and the formula is as follows:

in the formula, I is the current provided by the constant current source, V₁，V₂Respectively, the voltage values obtained by two measurements, f (V)₁/V₂) Is the van der Pauw coefficient.

And the material performance parameter calculating step comprises the calculation of a material Hall coefficient, and the formula is as follows:

wherein B is the magnetic induction perpendicular to the sample. Δ V_pnRepresenting the change in potential difference between P, N after application of the magnetic field. I is the charge of the particles and d is the sample thickness.

And the material performance parameter calculating step comprises material mobility calculation, and the formula is as follows:

wherein n and p are the concentrations of electrons and holes, respectively, in the semiconductor material_nAnd mu_pIs the mobility of electrons and holes. q is the charge amount and ρ is the resistivity.

The invention has the advantages and positive effects that:

(1) high parallelism of material characterization: the invention is a multi-path parallel measuring circuit, which can realize the rapid scanning type measurement of physical parameters of a plurality of samples, thereby establishing a high-efficiency high-flux material characterization method.

(2) Material-circuit integration: the invention integrates the measuring circuit and the measured material into a whole, and each high-flux material unit is used as a part of the circuit, so that high-precision and quick measurement can be realized.

(3) The characterizable parameters are rich: the invention can measure a plurality of physical properties for each sample at one time, and realize the cooperative characterization of a plurality of physical parameters. The Van der Ware method is adopted as a basic measuring unit, and the circuit can realize the measurement of parameters such as resistivity, Hall voltage, carrier mobility and the like by setting a proper measuring strategy.

(4) The material-circuit mixed structure provided by the invention overcomes the influence of the contact resistance of the traditional contact, and can realize high-precision measurement; the selection and access of the sample are realized through the selection circuit, and the rapid measurement can be realized; the whole measuring process is highly automatic, the influence of human factors is avoided, and the measuring consistency is ensured.

(5) Aiming at the array type high-throughput samples, the parallel 12 x 12 van der Waals measurement circuit is developed, and the rapid measurement of 3 physical parameters of 144 samples can be realized.

Drawings

FIG. 1 is a schematic diagram of the resistivity measurements by the Van der Pauw method;

FIG. 2 is a circuit diagram of a unit signal acquisition circuit;

FIG. 3 is a schematic diagram of a material-circuit hybrid;

FIG. 4 is a flow chart of the fabrication of a material-circuit hybrid structure;

FIG. 5 is a Van der Pauw circuit signal selection scheme;

figure 6 is a van der pol circuit measurement scheme.

Detailed Description

The present invention will be described in further detail with reference to the following embodiments, which are illustrative only and not limiting, and the scope of the present invention is not limited thereby.

A method for characterizing a high-throughput material comprises a measuring circuit design step, a material-circuit mixing preparation step and a material performance parameter calculation step.

The measuring circuit design step:

the electrical characteristics of the sample are measured by adopting a Van der Pauw method, and the sheet resistance of the sample can be obtained by four times of voltage and current alternation measurement by utilizing four edge measuring points with good contact. FIG. 1 shows two test pattern configurations of Van der Pauw method, where the cross points are the voltage points. Among them, fig. 1(a) has a complicated structure but the highest measurement accuracy, and fig. 1(b) has a low measurement accuracy but a simple structure. As the shape precision requirement of the sample of the type (a) in FIG. 1 is higher, the preparation complexity of a high-flux sample at the later stage is greatly increased, the advantages and disadvantages of the circuits (a) and (b) are further researched according to the specific requirement of material characterization in the invention, and a reasonable circuit form is finally selected.

Based on the above analysis, a unit signal acquisition circuit is designed, which is mainly composed of an instrumentation amplifier and a lock-in amplifier, as shown in fig. 2. The U1 unit is composed of AD524, a 0.1uf capacitor and a 1000K resistor and is mainly responsible for performing 1000-time gain amplification on the acquired voltage signal. The U2 and U3 units are two buffers, each of which is composed of two AD795S, and the main function is to reduce the direct-current voltage on the input end R1 of the operational amplifier; the U4 is formed by an AD630 square wave demodulator, mainly used to design lock-in amplifiers. U5 is composed of AD711 programmable gain instrumentation amplifier, the fixed gain of which is 1, 10, 100 or 1000 respectively, and the digital input end can be selected. U6 is a bipolar operational amplifier that provides gain for the pico amp level current primarily through the function of internal compensation. U7 is a relay and has the main function of avoiding situations where the input impedance is too low to make the circuit inoperable.

In order to quickly, accurately and highly parallelly measure the electrical characteristic parameters of 144 samples, the system samples the voltage of a measuring point in all the samples, automatically calculates and immediately displays the sheet resistance. This not only improves the test speed, but also monitors for reading anomalies (the sample in the cell measurement circuit fails to make full contact with the 4 measurement pins) and the effect of the measurement current on the sheet resistance reading can be observed. To eliminate the effect of the contact potential between the test circuit and the sample, two measurements of current in forward and reverse directions were taken and then averaged. In order to prevent static electricity and electromagnetic interference during measurement, a shielding cover is made of a high-saturation magnetic material to isolate the static electricity and the electromagnetic interference. Therefore, the reading is stable and reliable, and the measuring voltage is increased or decreased in direct proportion to the measuring current.

The interface circuit is connected with the computer by an RS232 serial port.

The material-circuit mixing preparation steps are as follows:

the designed material-circuit hybrid structure is shown in fig. 3, and mainly comprises two parts, wherein one part is a 12 × 12 high-throughput array part and is 144 sample areas to be tested (only four samples are drawn in the figure for illustration), and the other part is a high-throughput material characterization parallel measurement circuit area for completing the test of high-throughput material parameters. Four measuring points are designed for each sample to be measured between the sample to be measured and the parallel measuring circuit, so that the connection between the measuring circuit and the sample to be measured is realized.

The main fabrication flow of the material-circuit hybrid structure is shown in fig. 5. Firstly, a parallel measuring circuit part (yellow area in the figure) is manufactured by adopting a circuit manufacturing process, a sample area to be measured is reserved, and then a sample array to be measured is directly manufactured at a specified position of the measuring circuit by adopting a material high-flux preparation technology. At present, there are many high-throughput preparation techniques for materials, such as high-throughput composite material preparation techniques based on thin film deposition processes, jet printing synthesis methods, multi-element diffusion methods, micro-electromechanical structure methods, micro-fluidic structure methods, laser additive methods, and the like, and the high-throughput preparation techniques can be flexibly selected according to requirements of different application fields.

The step of calculating the material performance parameters

Material resistivity: the Van der Pauw method adopts two measurements, and the current flows through different measuring point pairs respectively to measure the voltage on the other two measuring points. There are 3 combinations of pairs of two measurement points, as shown in FIG. 5. The formulas for calculating the resistivity used by the three different combinations are different, the invention adopts the combination 2, and the calculation formula is

In the formula, I is the current provided by the constant current source, V₁，V₂Respectively, the voltage values obtained by two measurements, f (V)₁/V₂) Is the van der Pauw coefficient.

The measurement method is adopted, so long as the thickness of the sample is less than 3mm, no matter how large the other geometric dimensions are, the measurement result can be calculated by the same formula no matter where the sample is measured. Except the thickness correction factor, the thickness correction factor is not influenced by the mechanical property of the probe, and the accuracy of the measurement result is higher.

Hall effect measurement: the hall effect is a current magnetic effect (see fig. 6). When a sample is energized with a current I and a magnetic field is applied perpendicular to the current, a Hall potential difference is generated on two sides of the sample:

wherein I is the charge amount of the particles, B is the magnetic field strength, d is the sample thickness, and R_HIs Hall coefficient, V_HIs a hall potential difference.

As known from the van der pol method, a pair of non-adjacent stations (see fig. 1) are used for passing current through stations 1 and 3, and another pair of stations 2 and 4 are used for measuring potential difference. The Hall coefficient is given by

Wherein B is the magnetic induction intensity value perpendicular to the sample. Δ V_pnRepresenting the change in potential difference between P, N after application of the magnetic field. d is the sample thickness.

Mobility: the resistivity of the semiconductor material is given by:

wherein n and p are the concentrations of electrons and holes, respectively, in the semiconductor material_nAnd mu_pIs the mobility of electrons and holes. q is the charge amount and ρ is the resistivity.

Sample resistance R_sObtained by dividing the resistivity by the thickness d of the sample, and the density n of the sample_sIt is obtained by multiplying the doping concentration by the sample thickness d. Thus, it is possible to obtain:

μ_mfor mobility, q is the amount of charge, n_sIs the sample density, R_sIs the sample resistance.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept, and these changes and modifications are all within the scope of the present invention.