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EP-4741834-A1 - CONDUCTIVE ATOMIC MICROSCOPE

EP4741834A1EP 4741834 A1EP4741834 A1EP 4741834A1EP-4741834-A1

Abstract

Disclosed is a conductive atomic microscope in which the current flowing in a sample and a probe can be maintained constant by adjusting the voltage supplied to the sample on the basis of the current flowing in the probe. The conductive atomic microscope comprises: a voltage supply device for supplying voltage to a sample; a current detection device for detecting the current generated by the supplied voltage; and a controller for adjusting the voltage value supplied to the sample by the voltage supply device on the basis of the current value detected by the current detection device.

Inventors

  • JO, AHJIN
  • AHN, BYOUNG-WOON
  • PARK, SANG-IL

Assignees

  • Park Systems Corp.

Dates

Publication Date
20260513
Application Date
20240705

Claims (9)

  1. A conductive atomic microscope (C-AFM, conductive-AFM) that scans the surface of a sample by measuring the current flowing inside the sample through a tip of a cantilever comprising: a voltage supply device for supplying voltage to the sample; a current detection device for detecting a current generated by the supplied voltage; and a controller for adjusting a voltage value supplied to the sample by the voltage supply device based on a current value detected by the current detection device.
  2. The conductive atomic microscope of claim 1, the cantilever and the current detection device are connected by a conducting wire through which the current generated by the supplied voltage flows, and a current amplifier which amplifies the current transmitted from the cantilever is installed on the conducting wire.
  3. The conductive atomic microscope of claim 2, the controller controls the voltage supply device based on a current value flowing through the conducting wire to maintain the current value flowing through the tip within the set point current range.
  4. The conductive atomic microscope of claim 3, when the current value detected by the current detection device exceeds the set point current, the controller controls the voltage supply device to lower the voltage supplied to the sample.
  5. The conductive atomic microscope of claim 4, when the current value detected by the current detection device is less than the set point current, the controller controls the voltage supply device to increase the voltage supplied to the sample.
  6. The conductive atomic microscope of claim 5, the set point current is characterized by being 10 pA to 20 pA.
  7. The conductive atomic microscope of claim 3, when the current value detected by the current detection device exceeds a preset breakdown limit current value, the controller controls the voltage supply device to lower the voltage supplied to the sample.
  8. The conductive atomic microscope of claim 7, characterized in that after lowering the voltage supplied to the sample, the controller increases the voltage supplied to the sample to the Max Voltage when the current value detected by the current detection device is less than a first current value.
  9. The conductive atomic microscope of claim 8, characterized in that after increasing the voltage supplied to the sample to the Max Voltage, the controller adjusts the voltage supplied to the sample based on the current value detected by the current detection device when the current value detected by the current detection device exceeds a second current value.

Description

Technical Field The present disclosure relates to a conductive atomic microscope, and more particularly, to a conductive atomic microscope that scans the surface of a sample by means of a tip of a cantilever that contacts the surface of the sample. Background Art An atomic force microscope (AFM) acquires surface information of a sample using a tip. The atomic force microscope includes a tip and a cantilever connected to the tip. The cantilever possesses a high degree of flexibility and bends due to the atomic repulsive force-specifically, attractive and repulsive forces-acting between the sharp tip suspended at its end and the sample surface, and by measuring the degree of this bending through changes in the reflection angle of laser light, surface information of the sample can be obtained. The atomic force microscope can be divided into a contact mode and a non-contact mode. The atomic force between the tip and the sample changes from repulsive force to van der Waals attractive force as the distance between the two increases. The contact mode AFM uses repulsive force, and the non-contact mode AFM uses attractive force. The magnitude of the repulsive force used in the contact mode is very small, ranging from 1 to 10 nN, but the cantilever with the tip is also very sensitive, so it is bent by a small change in force. The angular displacement of the cantilever that occurs at this time also bends the angle of the laser beam reflected off the cantilever's upper surface, and by measuring the deflection angle of this laser beam using a PSPD (position sensitive photodiode), it is possible to recognize very small changes in surface elevation. Cantilevers are usually 100µm long, 10µm wide, and 1µm thick, and play a role in amplifying the microscopic interaction between the tip and the sample and transmitting it to the macroscopic world. The tip attached to the end of the cantilever is usually 10µm high and the diameter of the end of the tip is about 10nm. The contact mode AFM has the advantage of relatively easy operation and fast response speed. The contact mode AFM includes a conductive atomic microscope (C-AFM). The conductive atomic microscope obtains surface information of a sample by applying a voltage to the sample and/or the tip and measuring the current flowing inside the sample due to the potential difference thereof. A conventional conductive atomic microscope measured the IV characteristics of the sample by providing a constant voltage to the sample and/or tip. Here, the IV characteristics include the resistance between the tip and the sample, the threshold voltage, etc. However, as in the conventional conductive atomic microscope, when a constant voltage is supplied to a sample and/or tip while scanning the surface of the sample, there is a problem that the current flowing through the sample and/or tip may temporarily exceed a reference range, and the current exceeding the reference range may damage the sample and/or tip. Disclosure of Invention Technical Problem An object of the present disclosure for solving the above-described problem is to provide a conductive atomic microscope in which the current flowing in a sample and a tip can be maintained constant by adjusting the voltage supplied to the sample based on the current flowing in the tip. Solution to Problem In order to achieve the above-described object, a conductive atomic microscope according to an embodiment of the present disclosure is a conductive atomic microscope (C-AFM, conductive-AFM) that scans the surface of the sample by measuring the current flowing inside the sample through a tip of a cantilever, and the conductive atomic microscope comprises: a voltage supply device for supplying voltage to the sample; a current detection device for detecting the current generated by the supplied voltage; and a controller for adjusting the voltage value supplied to the sample by the voltage supply device based on the current value detected by the current detection device. The cantilever and the current detection device are connected by a conducting wire through which the current generated by the supplied voltage flows, and a current amplifier which amplifies the current transmitted from the cantilever is installed on the conducting wire. The controller controls the voltage supply device based on the current value flowing through the conducting wire to maintain the current value flowing through the tip within the set point current range. When the current value detected by the current detection device exceeds the set point current, the controller controls the voltage supply device to lower the voltage supplied to the sample. When the current value detected by the current detection device is less than the set point current, the controller controls the voltage supply device to increase the voltage supplied to the sample. The set point current is characterized by being 10 pA to 20 pA. When the current value detected by the current detection device exce