Impedance spectrum testing and fitting method of memristor
Technical Field
The invention relates to an impedance spectrum testing and fitting method of a memristor, and belongs to the technical field of microelectronic technology and semiconductor devices.
Background
The memristor has the advantages of small size, high reading and writing speed, low power consumption, nonvolatile storage, extremely high integration level, compatibility with a CMOS (complementary metal oxide semiconductor) process and the like, and is a fourth basic passive device. At present, the mature storage technologies such as SRAM, DRAM, Flash and the like all adopt transistors to construct storage bits, with the continuous increase of the integration degree of microelectronic technology and process, the size of the traditional CMOS process is gradually close to the physical limit, and the memory resistance device is likely to solve the problem of calculating a storage wall, so that the moore's law is continued.
The impedance spectrum measurement is developed and perfected for decades and has been widely applied in various scientific research and industrial production fields such as batteries, material characterization, electrical analysis and the like. The impedance measurement method has the advantages of wide measurement frequency range, high accuracy, evaluation and differentiation of the electrical properties of the material from different angles, and the like. In 2013, Wang Li Shi et al (patent number: CN 101871974B) of university of southern China invented a method for measuring impedance spectra, but the test frequency range can only achieve 1Hz-100kHz, and the method is not suitable for testing memristive systems.
However, the application of measurement and analysis of the impedance spectrum in the memristive system is still limited at home and abroad at present, the equivalent circuit is not unique, the physical interpretation of each part of the complex impedance spectrum is not clear, and the like, so that the analysis and the use of the impedance spectrum on the test characterization in the memristive system are limited. Based on the method, the universal measuring and fitting method for applying the impedance spectrum to the electrical performance analysis of the memristor system is provided, the research on the physical mechanism of the memristor system can be enriched, the commercial development of memristor devices is accelerated, and the Morel's law is continued.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to analyze the internal relation between the memristor impedance spectrum and a resistance switching mechanism and provide an effective and reasonable analysis means for the research of the internal physical mechanism of a memristor system, namely, a method for testing and fitting the impedance spectrum of the memristor is provided, and the rapid and accurate impedance spectrum testing and fitting are realized.
In order to achieve the above purpose and solve the problems existing in the prior art, the invention adopts the technical scheme that: an impedance spectrum testing method of a memristor comprises the following steps:
step 1, self-making a measuring clamp, namely reassembling the measuring clamp by adopting a German technology 16048H testing clamp, and specifically comprising the following substeps:
(a) the Lcur end and the Lpot end on the 16048H test fixture are connected through a T-shaped conversion head to form a first output port 101;
(b) connecting an Hcur end and an Hpot end on the 16048H test fixture through a T-shaped conversion head to form a second output port 102;
(c) connecting the first output port 101 through a triaxial conversion head to form a third output port 103;
(d) connecting the second output port 102 through a three-coaxial conversion head to form a fourth output port 104, and finishing the self-control of the measuring clamp;
step 2, connecting the impedance analyzer with the test probe station, placing a tested device into a vacuum chamber of the test probe station, connecting the end A of the self-made measurement clamp with an Aglient 4294A/Keithley E4990A/HP41 4192A impedance analyzer, connecting the output ports 103 and 104 in the end B of the self-made measurement clamp with the test probe station respectively, and realizing the connection of the impedance analyzer and the test probe station through the self-made measurement clamp;
step 3, setting a measuring environment of the impedance analyzer, initializing the impedance analyzer, configuring an adapter, and performing compensation calibration including open-circuit and short-circuit calibration;
step 4, testing the low-resistance-state impedance spectrum of the memristive device, connecting a test probe station with a Keithley4200-SCS/Keysight B1500A semiconductor parameter analyzer, and setting the limiting current to 10-120.105A, applying direct current voltage of 0.1-60V to the memristor to be tested, starting the memristor to change into a low-resistance state, connecting the impedance analyzer with the test probe station, setting the alternating current oscillation amplitude value to be 0.1-1.0V, the bias voltage to be 0.1-0.5V, setting the test frequency range to be 5Hz-110MHz, adjusting the display mode to be R-X/| Z | -theta/G-B, and finally transmitting the data to a computer end through a GPIB cable to acquire the data, thereby completing the test of the low-resistance state impedance spectrum of the memristor;
and step 5, testing a high-resistance-state impedance spectrum of the memristor, connecting a test probe station with a Keithley4200-SCS/Keysight B1500A semiconductor parameter analyzer, applying a direct-current voltage to the tested memristor to scan the range of-60-0V, inverting the memristor into a high-resistance state, connecting the impedance analyzer with the test probe station, setting the alternating-current oscillation amplitude value to be 0.1-1.0V, the bias voltage to be 0.1-0.5V, setting the test frequency range to be 5Hz-110MHz, adjusting the display mode to be R-X/| Z | -theta/G-B, and finally transmitting data to a computer end through a GPIB cable to finish testing the high-resistance-state impedance spectrum of the memristor.
An impedance spectrum fitting method of a memristor device adopting the testing method comprises the following steps:
step 1, determining an equivalent circuit model of a memristor impedance spectrum, obtaining test results of high and low resistance state impedance spectrums of the memristor and a circuit model proposed by related documents according to the test method, and determining the equivalent circuit model of the high and low resistance state impedance spectrums of the memristor;
step 2, obtaining parameters of each element in the memristor impedance spectrum equivalent circuit, and fitting the obtained memristor high-resistance state impedance spectrum data and low-resistance state impedance spectrum data obtained by the testing method through Zview software to obtain parameters of each element in the memristor high-resistance state impedance spectrum equivalent circuit and low-resistance state impedance spectrum equivalent circuit;
and 3, deriving the original data and the fitting data in the Zview software in the step 2, and mapping the original data and the fitting data into origin.
The invention has the beneficial effects that: a method for testing and fitting an impedance spectrum of a memristor device is provided, wherein the testing method comprises the following steps: (1) the method comprises the steps of (1) self-making a measuring clamp, (2) connecting an impedance analyzer with a test probe station, (3) setting a measuring environment of the impedance analyzer, (4) testing a low-resistance-state impedance spectrum of the memristive device, and (5) testing a high-resistance-state impedance spectrum of the memristive device. The fitting method comprises the following steps: (1) determining an equivalent circuit model of a memristor impedance spectrum, (2) obtaining parameters of each element in the memristor impedance spectrum equivalent circuit, and (3) deriving raw data and fitting data in Zview software to be plotted in origin. Compared with the prior art, the method can quickly obtain the impedance spectrum of the memristor, provides an effective test and analysis means for the research of the thin film microstructure of the memristor system, can enrich the research of the switch mechanism of the memristor system, and has very important research significance for perfecting the internal physical mechanism of the memristor system.
Drawings
FIG. 1 is a flow chart of the steps of the impedance spectroscopy test method of the present invention.
FIG. 2 is a schematic connection diagram of the self-made measuring fixture manufacturing process of the present invention.
FIG. 3 is a flow chart of the steps of the impedance spectrum fitting method of the present invention.
FIG. 4 is a TiN/HfO2A direct current-voltage characteristic curve diagram of a high-resistance state and a low-resistance state of a/TiN-structure memristor is shown.
FIG. 5 is a TiN/HfO2A curve graph of a real part and an imaginary part of an impedance spectrum with frequency change is formed when the memristor device of a TiN structure is in a low-resistance state.
FIG. 6 is a TiN/HfO2A curve graph of a real part and an imaginary part of an impedance spectrum with frequency change is formed when the memristor device of a TiN structure is in a high-resistance state.
FIG. 7 is a TiN/HfO2An equivalent circuit model diagram of a low-resistance-state impedance spectrum of a memristor with a TiN structure.
FIG. 8 is a TiN/HfO2The fitting result of a low-resistance-state impedance spectrum of the memristor with the TiN structure is shown.
FIG. 9 is a TiN/HfO2An equivalent circuit model diagram of a high-resistance-state impedance spectrum of a memristor with a TiN structure.
FIG. 10 is a TiN/HfO2The fitting result of a high-resistance-state impedance spectrum of the memristor with the TiN structure is shown.
Detailed Description
The invention will be further explained with reference to the drawings.
As shown in fig. 1, a method for testing an impedance spectrum of a memristive device includes the following steps:
step 1, self-making a measuring clamp, namely reassembling the measuring clamp by adopting a German technology 16048H testing clamp, and specifically comprising the following substeps:
(a) the Lcur end and the Lpot end on the 16048H test fixture are connected through a T-shaped conversion head to form a first output port 101;
(b) connecting an Hcur end and an Hpot end on the 16048H test fixture through a T-shaped conversion head to form a second output port 102;
(c) connecting the first output port 101 through a triaxial conversion head to form a third output port 103;
(d) the second output port 102 is connected through a triaxial adapter to form a fourth output port 104, the measurement fixture is self-made, and the connection schematic diagram of the manufacturing process is shown in fig. 2.
Step 2, connecting an impedance analyzer and a test probe station, and combining TiN/HfO2the/TiN-structure memristor is placed in a vacuum chamber of a test probe station, and the A end of the self-made measuring clamp is connected with an Aglient 4294A impedance analyzerAnd output ports 103 and 104 in the B end of the self-made measuring clamp are respectively connected with the test probe station, and the impedance analyzer is connected with the test probe station through the self-made measuring clamp.
Step 3, setting a measuring environment of the impedance analyzer, initializing the impedance analyzer, configuring an ADAPTER, selecting ADAPTER [ ] - [ NONE ], and then performing compensation calibration, including open-circuit and short-circuit calibration; open circuit calibration: [ Cal ] -FIXTURE COMPEN-OPEN, OPEN ON OFF to OPEN ON OFF; short circuit calibration: the home-made measurement FIXTURE was attached to the test probe station and the two probes were gently touched, [ Cal ] -FIXTURE COMPEN-SHORT, SHORT ON OFF was changed to SHORT ON OFF.
Step 4, testing the memristor low-resistance-state impedance spectrum, connecting a test probe station with a Keithley4200-SCS semiconductor parameter analyzer, setting the limiting current to be 0.1nA, and testing the TiN/HfO to be tested2The method comprises the steps of applying a direct-current voltage of 0-3V to a memristor device with a TiN structure, starting the memristor device, changing the memristor device into a low-resistance state, connecting an impedance analyzer with a test probe station as shown by a black solid line in figure 4, setting the alternating-current oscillation amplitude to be 100mV, the bias voltage to be 100mV, and setting the test frequency range to be 40Hz-10MHz, wherein the specific operation method is [ Sweep]-PARAMETER[]-FREQ-[Start]-40Hz-[Stop]-10M, adjusting the display mode to be R-X, and specifically operating the method to be display]-[R-X]Finally, the data is transmitted to a computer end through a GPIB cable to acquire data, and the TiN/HfO is finished2Testing a low-resistance state impedance spectrum of the memristor with the TiN structure; TiN/HfO2The variation curve of the real part and the imaginary part of the impedance spectrum in the low-resistance state of the memristor device with the TiN structure along with the frequency is shown in FIG. 5.
Step 5, testing the high-resistance-state impedance spectrum of the memristor, connecting a test probe station with a Keithley4200-SCS semiconductor parameter analyzer, and testing the TiN/HfO to be tested2The applied direct-current voltage of the memristor with the TiN structure is in a scanning range of-3-0V, the memristor is turned into a high-resistance state, as shown by a dotted line in figure 4, the impedance analyzer is connected with the test probe station, the alternating-current oscillation amplitude is set to be 100mV, the bias voltage is set to be 100mV, the test frequency range is set to be 40Hz-20MHz, and the specific operation method is [ Sweep]-PARAMETER[]-FREQ-[Start]-40Hz-[Stop]-20M, adjusting display modeFor R-X, the specific operating method is display]-[R-X]Finally, the data is transmitted to a computer end through a GPIB cable to acquire data, and the TiN/HfO is finished2And testing a high-resistance-state impedance spectrum of the memristor with the TiN structure. TiN/HfO2The variation curve of the real part and the imaginary part of the impedance of the memristor device in a high-impedance state along with the frequency is shown in FIG. 6.
As shown in fig. 3, a method for fitting an impedance spectrum of a memristive device includes the following steps:
step 1, determining an equivalent circuit model of a memristor impedance spectrum, and obtaining TiN/HfO according to the memristor impedance spectrum testing method2The test result of the low-resistance-state impedance spectrum of the memristor device with the TiN structure is shown as a hollow circular curve in fig. 8, and the TiN/HfO is determined2A model diagram of a low-resistance-state impedance spectrum equivalent circuit of a memristor device with a TiN structure is shown in FIG. 7, and the model diagram is formed by a resistor RPAnd a capacitor CPConnected in parallel and then connected with a resistor RS1Are connected in series; the obtained test result of the high-resistance-state impedance spectrum of the memristive device is shown as a hollow rectangular curve in FIG. 10, and TiN/HfO is determined2A model diagram of a high-resistance-state impedance spectrum equivalent circuit of a memristor device with a TiN structure is shown in figure 9 and is formed by parallel components R2C2With parallel component R1C1After being connected in series with RS2Are connected in series.
Step 2, obtaining parameters of each element in the memristor impedance spectrum equivalent circuit, and testing the obtained TiN/HfO by using the memristor impedance spectrum testing method2Fitting high and low resistance state impedance spectrum data of the memristor with the TiN structure through Zview software to obtain parameters of each element in the high and low resistance state impedance spectrum equivalent circuits of the memristor. Wherein: TiN/HfO2The parameters of each element in the low-resistance-state impedance spectrum equivalent circuit of the memristor with the TiN structure are shown in Table 1. TiN/HfO2The parameters of each element in the high-resistance-state impedance spectrum equivalent circuit of the memristor with the TiN structure are shown in Table 2.
And 3, deriving the original data and the fitting data in the Zview software in the step 2 to origin for drawing, wherein: TiN/HfO2Fitting result diagram of low-resistance-state impedance spectrum of memristor with TiN structureTiN/HfO as shown in FIG. 82The fitting result chart of the high-resistance-state impedance spectrum of the memristor with the TiN structure is shown in FIG. 10.
TABLE 1
Component
|
Value of
|
Error of fit
|
Percentage of error
|
RS1 |
297.4
|
3.4603
|
1.1635
|
RP |
6127
|
42.179
|
0.688
|
CP |
2.05E-10
|
1.19E-12
|
0.251 |
TABLE 2
Component
|
Value of
|
Error of the measurement
|
Percentage of error
|
RS2 |
131.7
|
13.387
|
10.165
|
R1 |
292.4
|
13.838
|
5.7585
|
C1 |
6.17E-11
|
6.405E-12
|
10.377
|
R2 |
237.2
|
80.619
|
33.988
|
C2 |
1.77E-09
|
6.687E-10
|
37.769 |