Automated device for local electrical characterization of materials

Abstract

This utility model relates to instrumentation and measurement technology, specifically to equipment for studying the electrical properties of materials. A device for the local electrical characterization of materials comprises a three-axis manipulator with a sample-mounting stage, a measuring probe, and an electrical module. The measuring probe is a spring-loaded conductive electrode electrically connected to the electrical module, which includes a controller capable of automatically controlling the manipulator's movement and changing the voltage for measuring the volt-ampere characteristic. The technical result consists in increasing the efficiency of the electrical characterization procedure for materials by ensuring automated cyclic testing. 3 clauses, 1 fig.

Description

[0001] This utility model relates to instrumentation and measurement technology, specifically to equipment for studying the electrical properties of thin-film materials and structures. The device can be used for local electrical characterization of functional coatings, including resistive random access memory (ReRAM) materials, metal-organic framework films, memristive structures, and other thin-film micro- and nanoelectronic components.

[0002] Stationary probe stations and specialized scanning microscopy systems are widely used to study the electrical properties of thin-film materials and resistive memory structures. Existing technical solutions allow for point measurements of current-voltage characteristics, and the study of resistive switching processes and state durability. However, in most cases, such devices do not provide the required degree of automation, local positioning accuracy, or adaptive algorithmic measurement control.

[0003] The industry currently offers two types of solutions for materials characterization. The first family includes probe stations for analyzing microelectronic structures.

[0004] A probe station [1] is known for electrical and optical measurements of microelectronic structures. The probe station [1] utilizes two independent working platforms: one for electrical probes and one for optical probes, enabling the combined electrical and optical diagnostics of the devices under study. The substrate is fixed on a sample mounting stage, which can move in the X–Y plane (where X is the abscissa axis and Y is the ordinate axis), while the electrical probes move primarily along the Z axis (the applicate axis) to establish electrical contact. Probe positioning is performed manually or semiautomatically, and the system is designed for testing already formed microelectronic structures with accessible contact pads.

[0005] The disadvantages of this device include the need for operator intervention when aligning the probe with the contact area, limited ability to automatically sequentially scan large surface areas, and the lack of means for implementing complex cyclic electrical effects. Furthermore, the probe station is designed to work with standard silicon substrates and standard microelectronic chips, thin-film coatings, and prototypes obtained during the scientific development of new functional materials.

[0006] The second family of well-known technical solutions pertains to scanning probe microscopy systems, including atomic force microscopy (AFM), potential probe force microscopy (KPFM), and conductive atomic force microscopy (CS-AFM). These systems utilize a movable micromechanical probe placed in contact with the surface of the sample being studied or at a small distance from it. Applying an electrical voltage between the probe and the substrate records the electric current or local potential change, enabling the acquisition of point current-voltage characteristics, conductivity maps, and the distribution of local electrical properties of the material.These technical solutions are widely used for the study of memristive and resistive-switched thin-film structures due to the high spatial resolution and sensitivity provided, which is confirmed, in particular, by the work [2].

[0007] The closest analogue to the claimed utility model is a scanning probe microscope [3], designed for studying the surface of objects with nanometer spatial resolution, implementing the method of atomic force microscopy and related modes of scanning probe microscopy. The prototype comprises a base with vibration isolation, a probe with a tip, a piezoelectric scanning unit used as a manipulator, providing movement of the probe or the studied sample along the coordinate axes X, Y and Z, a table for fixing the sample, as well as an electrical module consisting of a signal recording system and a feedback system, designed to maintain a given mode of interaction between the probe and the surface of the sample during the scanning process.The device is designed with the ability to measure the parameters of interaction between the probe and the surface of the sample during discrete positioning of the probe within the area being studied, while the feedback system is functionally connected to the scanning unit and is designed to control its movement in order to compensate for surface irregularities and form an image of the area being studied.

[0008] The key disadvantages of this invention are its inapplicability to large-scale samples with a contact area greater than 1 mm^2, the low speed of movement of the substrate manipulator, and the lack of the ability to set and accurately measure currents and voltages in a wide range of modes.

[0009] Scanning probe microscopy systems are the closest to the utility model under consideration in terms of the nature of the tasks being solved, but despite the high information content and development of these methods, they have a number of significant disadvantages.

[0010] The main disadvantages of scanning probe microscopy systems include a limited range of permissible voltages and currents, which complicates measurements typical of the actual operating modes of resistive memory elements. The scanning area and probe speed are limited. The stability of mechanical contact and sensitivity to surface defects reduce the reproducibility of local measurements, particularly for thin-film coatings obtained through recent synthesis, which limits their applicability for screening new materials. Furthermore, such systems are focused on analyzing individual points or small areas and do not provide automated cyclic testing, long switching series, or sequential examination of large numbers of points without operator intervention.

[0011] The proposed utility model allows to overcome the above mentioned disadvantages due to automated positioning of the measuring probe, an extended range of electrical influences and a high degree of automation of the measuring process.

[0012] The technical problem is the need to develop a device capable of reproducing local measurements, conducting cyclic tests, increasing the speed of probe movement, increasing the range of permissible voltages and currents, to facilitate measurements.

[0013] The technical result of the utility model is to increase the efficiency of the procedure for electrical characterization of materials by ensuring automated execution of cyclic tests.

[0014] The technical result is achieved in that in an automated device for local electrical characterization of materials, containing a three-coordinate manipulator with a table for attaching a sample, a measuring probe and an electrical module, the measuring probe is made in the form of a spring-loaded conductive electrode having an electrical connection with the electrical module, which includes a controller, designed with the possibility of automated control.

[0015] In the embodiment of an electromechanical three-coordinate manipulator based on stepper motors with encoders that provide the ability to move the measuring probe along the X, Y and Z axes with a resolution of at least 1 μm due to the presence of two components: a Z-axis manipulator and an XY-axis manipulator.

[0016] In the embodiment of the measuring probe made of gold with a diameter of 50 μm.

[0017] In an embodiment of an electrical module that switches off a bypass unit, a controller, a polarity reversal unit, a current and voltage setting and change unit, and a power supply network interference filtering unit.

[0018] In the embodiment of automated control of the controller with the ability to move the manipulator, perform specified algorithms of electrical effects and record the electrical parameters of the material at local points of the surface of the sample being studied.

[0019] In an embodiment capable of operating in real time.

[0020] The utility model is illustrated by a drawing, which shows a schematic image of an automated device for local electrical characterization of materials.

[0021] The following positions are indicated on the drawing:

[0022] 1 – manipulator base,

[0023] 2 – three-coordinate manipulator,

[0024] 3 – sample mounting table,

[0025] 4 – static probe,

[0026] 5 – movable measuring probe,

[0027] 6 – electrical module,

[0028] 7 – controller,

[0029] 8 – Power line interference filtering unit,

[0030] 9 – current and voltage setting and measurement unit,

[0031] 10 – polarity reversal block,

[0032] 11 – bypass block.

[0033] The proposed device comprises a manipulator base 1, a three-coordinate manipulator 2, with a table for attaching a sample 3 and a static probe 4, a movable measuring probe 5 and an electrical module 6 containing a controller 7, a power supply interference filtering unit 8, a current and voltage setting and changing unit 9, a polarity reversal unit 10 and a shunting unit 11.

[0034] The utility model operates as follows.

[0035] The base of the manipulator 1 is installed on a flat surface. The position of the three-axis manipulator 2 with the sample mounting table 3 and the static probe 4, as well as the position of the movable measuring probe 5, are determined by the electrical module 6, namely the controller 7. The device is powered through the power supply noise filter unit 8, which removes noise from the current coming from the power supply. The current then passes through the control and current and voltage measurement unit 9, where the desired voltage level is set by the controller 7. The current then passes through the polarity reversal unit 10, pre-selected by the controller 7, after which the current is applied to the sample via the electrode of the movable measuring probe 5 for subsequent volt-ampere analysis in the shunt unit 11.

[0036] The utility model is explained by an example.

[0037] To assess the influence of the utility model design on the efficiency of material characterization, tests were conducted in the laboratory of ITMO University.

[0038] During the study, the researcher mounted a glass substrate coated with a conductive ITO (Indium Tin Oxide) layer onto the sample mounting stage. The substrate's surface was pre-coated with a thin-film HKUST-1 metal-organic framework (Hong Kong University of Science and Technology) structure, designed to study resistive switching properties. The researcher connected the bottom layer of the substrate to the device's static probe.

[0039] Before starting measurements, the researcher entered the required coordinates of the sample areas to be studied, after which the controller moved the movable measuring probe to its initial position over the desired area on the sample surface. The Z-axis manipulator then lowered until it made electrical contact with the sample.

[0040] To measure the current-voltage characteristic in the region of interest, the controller set a voltage sequence from 0 to 8 V in 0.05 V increments. The current was recorded by the controller using a shunt block, and the data was stored in the controller's memory, linked to the measurement coordinates. Upon reaching the current threshold, the maximum current was limited using a 10 kOhm shunt block, preventing irreversible degradation of the sample.

[0041] After recording the I–V characteristic (voltage-ampere characteristic), the controller performed a series of resistive switching cycles. A single I–V measurement cycle consisted of successively changing the applied voltage from 0 to a threshold value of 8 V in a set increment of 0.05 V and back, after which the polarity of the applied voltage was reversed. After each cycle, the controller recorded the sample resistance at a low test voltage of 0.2 V.

[0042] In this study, 100 switching cycles were performed using the controller, the results were recorded and displayed on the stability of the formation and destruction of conductive channels in the sample, interpreted through the recording of logical states. <0> And <1> With the ability to construct a two-dimensional map of the electrical parameter distribution by scanning a 20x20 point area with a 100 µm increment. At each point, the I-V characteristic was automatically measured, and the required setting voltage for forming conductive channels, an important characterization parameter, was determined. After completing the scan, the researcher used software to obtain the necessary set of characteristic parameters for sample analysis, as well as their distribution.

[0043] Thus, the operation of an automated device for local electrical characterization of materials is demonstrated to improve the efficiency of the electrical characterization procedure of materials by providing automated cyclic testing.

[0044] Bibliography

[0045] 1. Patent No. 7,368,925 US, IPC G01R 31 / 28 (2006.01). PROBE STATION WITH TWO PLATENS : No. 10 / 728,394 : declared 05.12.2003 : published 06.05.2008 / Navratil P., Froemke B., Stewart C., Lord A., Spencer J., Runbaugh S., Fisher G., McCann P., Jones R. ; applicant Cascade Microtech, Inc. – 12 p.

[0046] 2. Lee MH, Hwang CS Resistive switching memory: observations with scanning probe microscopy / / Nanoscale. – 2011. – T. 3. – No. 2. – pp. 490-502.

[0047] 3. Patent No. 2334214 Russian Federation, IPC G01N 13 / 16 (2006.01). SCANING PROBE MICROSCOPE : No. 2005102703 / 28A : application. 04.07.2005 : published. 10 / 27 / 2008 / Miles M. D., Humphreys E. D. L., Hobbs D. K.. - 20 s.

Claims

1. A device for the local electrical characterization of materials, comprising a three-coordinate manipulator with a table for attaching a sample, a measuring probe and an electrical module, characterized in that the measuring probe is made in the form of a spring-loaded conductive electrode having an electrical connection with the electrical module, which includes a controller, designed with the possibility of automated control of the movement of the manipulator and the change in voltage for measuring the volt-ampere characteristic.

2. A device for local electrical characterization of materials according to paragraph 1, characterized in that the three-coordinate manipulator is made electromechanically based on stepper motors with encoders that provide the ability to move the measuring probe along the X (abscissa), Y (ordinate) and Z (applicate) axes with a resolution of at least 1 μm due to the presence of two component parts: a Z-axis manipulator and an XY-axis manipulator.

3. A device for local electrical characterization of materials according to paragraph 1, characterized in that the measuring probe is made of gold with a diameter of 50 µm.

4. A device for local electrical characterization of materials according to paragraph 1, characterized in that the device is designed with the ability to operate in real time.

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