KR20070031596A - A Probe Property Measuring Device Of A Scanning Probe Microscope - Google Patents

Abstract

The present invention relates to a probe characteristic measuring apparatus of a scanning probe microscope, the probe of the scanning probe microscope disposed on one side; An actuator connected to the probe such that the probe vibrates minutely; Sensing means correspondingly arranged to sense vibration of the probe; And detecting the changed characteristic of the probe based on the natural frequency of the probe, which is minutely changed by enabling the natural frequency calculation of the probe and the feedback to the actuator input signal based on the vibration signal of the sensing means. And a controller electrically connected to the means and the actuator. Wherein the probe is disposed so as to reflect and incident light from the probe to the sensing means and to irradiate a laser beam with respect to the probe so that the minute vibration of the probe can be modulated into an optical signal. It is preferable to include a reflector, and in this case, it is preferable that the sensing means is a light sensor capable of detecting a change in laser light from an optical signal reflected and incident from the reflector.

Atom, Microscope, Probe, Characteristics, Frequency, Controller, Feedback, Closed-Loop

Description

Probe Property Measuring Device Of A Scanning Probe Microscope

1 is a first embodiment for measuring probe characteristics of a conventional scanning probe microscope,

Figure 2 is a second embodiment for measuring the probe characteristics of a conventional scanning probe microscope,

Figure 3 is a frequency response graph according to the measurement of the probe characteristics of the conventional scanning probe microscope,

4 is a block diagram of a probe characteristic measuring apparatus of a scanning probe microscope according to the present invention.

Explanation of symbols on main parts of drawing

10: probe, 20: support,

30: tungsten sphere, 100: probe,

200: light irradiator, 300: reflector,

400: actuator, 500: light sensor,

600: controller

The present invention relates to an apparatus for measuring a characteristic change of a probe of a scanning probe microscope, which is an atomic microscope, and more particularly, to a characteristic of a probe that is changed by using a scanning probe microscope (eg, rigidity, effective mass, etc.). Actuator for micro-vibration of the probe to measure in real time) and a probe characteristic measuring device of a scanning probe microscope using a controller to configure a closed loop circuit by changing / controlling the output signal obtained according to the input signal .

In general, as a microscope structure capable of enlarging the shape of micromaterials, optical microscopes, electron microscopes, and the like have been developed and commercialized.

By the way, in such a conventional microscope structure, it is known that the optical microscope has a magnification of up to several thousand times, and the electron microscope has a magnification of up to several hundred thousand times.

In contrast, recently developed atomic microscopes have a magnification of up to tens of millions of times and include structures that allow individual atoms to be observed.

This atomic microscope structure is commonly referred to as a scanning probe microscope, the first STM (Scanning Tunneling Microscope), AFM (Atomic Force Microscope) that can measure non-conductor samples, and the shape of the material Magnetic Force Microscope (MFM) capable of measuring other characteristics, in addition to various types such as Lateral Force Microscope (LFM), Force Modulation Microscope (FMM), Electrostatic Force Microscope (EMF), Scanning Capacitance Microscope (SCM), etc. Is taking.

Although these atomic microscopes have a variety of structures, they generally include a cantilever-like probe, which is used to measure the properties of micromaterials. It is treated as a part.

However, the frequent use of the scanning probe microscope causes a change in the characteristics of the probe structure, thereby affecting the performance of the scanning probe microscope.

Accordingly, a method for measuring the probe characteristics of a scanning probe microscope such as an effective mass or rigidity has been developed and used. In order to identify and measure probe characteristics of a scanning probe microscope, a method of estimating characteristic change through the addition of minute mass has been conventionally used as shown in FIGS. 1 and 2.

As shown in FIG. 1, a cantilever structure probe 10 is disposed, and a support 20 is attached to a rear end thereof. In this state, the natural frequency of the probe 10 is measured.

And, as shown in Figure 2, after adding a tungsten sphere having a small mass to the front end of the probe 10, the natural frequency is measured.

As shown in FIG. 3, a change in the natural frequency when the tungsten sphere 30 is added or not is added. In FIG. 3, the x axis is a frequency value of a natural frequency (kHz) and the y axis is an amplitude. As shown in FIG. 3, the natural frequency of the probe 10 to which the tungsten sphere 30 is not added is displayed on the right side, and the natural frequency after the tungsten sphere 30 is added to the left side is displayed. It can be seen that the amplitude of the natural frequency of the probe 10 is reduced in the state in which the tungsten sphere 30 is added.

In this case, the effective mass and stiffness of the probe 10 can be measured by substituting the frequency of the natural frequency when the tungsten sphere 30 is not added and the natural frequency after the addition into the conventionally known formula.

Furthermore, it is necessary to measure the natural frequency while changing the mass of the added tungsten sphere 30 to statistically estimate the rigidity and the effective mass of the probe 10. Accordingly, if the regression analysis is performed by substituting the measured natural frequency into a known formula, a graph as shown in FIG. 3 may be obtained. Where the slope is the stiffness of the probe 10 and the absolute value of the y-axis intercept is the effective mass.

By the way, the conventional method of measuring the characteristics of the probe 10 has a cumbersome problem of repeating the measurement operation while installing a small mass such as tungsten sphere 30 at the end of the probe 10 each time.

In addition, since the operation of the tungsten sphere 30 and the measurement of the natural frequency are alternately performed, the characteristics of the probe 10 may be known.

Accordingly, there is a problem in that it is impossible to measure / identify the characteristics of the probe 10 more quickly in real time, and because it is not always possible to select the same location where the micromass is added, such as tungsten sphere 30, in the measurement process. There is a problem that an error may occur.

As a result, difficulties arise in the measurement process of the characteristic change of the probe 10, as well as more accurate and rapid changes in the characteristic of the probe 10 can not be measured, resulting in the performance of the scanning probe microscope equipped with the probe 10. There is a problem that affects.

Accordingly, the present invention has been derived in view of the above-described conventional problems, and a first object of the present invention is to scan a probe (for example, mass, stiffness, etc.) of a probe in a scanning probe microscope in real time. The present invention provides an apparatus for measuring probe characteristics of a probe microscope.

And a second object of the present invention is to provide a probe characteristic measuring apparatus of a scanning probe microscope which can measure the characteristic change of the probe more simply and quickly.

Such objects of the present invention, the probe of the scanning probe microscope disposed on one side; An actuator connected to the probe such that the probe vibrates minutely; Sensing means correspondingly arranged to sense vibration of the probe; And detecting the changed characteristic of the probe based on the natural frequency of the probe, which is minutely changed by enabling the natural frequency calculation of the probe and the feedback to the actuator input signal based on the vibration signal of the sensing means. It is achieved by the probe characteristic measuring apparatus of the scanning probe microscope comprising; and a controller electrically connected to the means and the actuator.

And a light irradiator for irradiating a laser beam to the probe so that the small vibration of the probe can be modulated into an optical signal, and a corresponding arrangement for reflecting and injecting an optical signal reflected from the probe based on the small vibration to the sensing means. It is preferable to include a reflector.

In addition, the sensing means is preferably a light sensor capable of detecting a change in the reflected laser light.

In addition, it is preferable that the said actuator is a piezoelectric structure.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and the preferred embodiments associated with the accompanying drawings.

Hereinafter, a probe characteristic measuring apparatus of a scanning probe microscope according to the present invention will be described in detail with the accompanying drawings.

4 is a block diagram of a probe characteristic measuring apparatus of a scanning probe microscope according to the present invention. The probe characteristic measuring apparatus according to the present invention detects the vibration of the probe 100 by the actuator 400 and calculates a natural frequency based on the vibration of the probe 100.

In particular, the probe 100 which is changed by using a scanning probe microscope by constructing a closed loop circuit which generates a micro vibration of a different probe 100 each time by feeding back the detected vibration signal to the actuator 400 and detects and calculates the vibration. It is a device configured to be able to measure the properties (for example, stiffness, effective mass, etc.).

As shown in FIG. 4, in the probe 100 characteristic measuring apparatus of the scanning probe microscope according to the present invention, the actuator 400 is connected to the probe 100 to vibrate the probe 100 minutely. Since the actuator 400 must vibrate the probe 100 having a small size slightly, it is preferable that the actuator 400 is driven by a piezoelectric principle.

The light irradiator 200 and the reflector 300 are provided to change the micro-vibration of the probe 100 into a change of light.

The light irradiator 200 is disposed to irradiate the laser beam to the probe 100. The irradiated laser light hits the probe 100 and is reflected again. The reflected laser light vibrates in the same manner as the small vibration of the probe 100 by the actuator 400. Therefore, the reflected laser light becomes an optical signal carrying data on the micro vibration of the probe 100.

The light sensor 500 is arranged to receive and detect such an optical signal.

The reflector 300 is disposed corresponding to the irradiation angle of the laser light of the light irradiator 200 and the reflection angle of the probe 100. The light sensor 500 is disposed corresponding to the reflection angle of the reflector 300. Therefore, the light sensor 500 is irradiated from the light irradiator 200 to the probe 100 to detect the light signal modulated based on the micro-vibration of the probe 100 by being incident from the reflector 300.

In addition, the controller 600 is electrically connected to the light sensor 500. The controller 600 calculates the natural frequency of the probe 100 based on the received optical signal. In addition, the controller 600 is electrically connected to the actuator 400 is fed back to the input signal to the actuator 400, the optical signal to calculate the natural frequency. As a result, a closed loop circuit in which an output signal called an optical signal in which the micro vibrations are modulated is formed as an input signal is configured.

At this time, the signal input to the actuator 400 is changed into a signal capable of vibrating to have a different deflection (for example, further deflection) based on the optical signal that has already been used as the basis of the calculation. Therefore, the actuator 400 receiving such an input signal vibrates the probe 100 to have a larger deflection. The probe 100 vibrates differently each time with the feedback of such a signal, and is calculated in real time by the controller 600, thereby providing a structure capable of measuring a characteristic change of the probe 100 based on the probe 100.

When sensitivity analysis is performed based on the natural frequencies thus obtained, the characteristics of the probe 100 such as stiffness and effective mass can be quickly and accurately measured.

In the probe characteristic measuring apparatus of the scanning probe microscope according to the present invention as described above, in addition to the light irradiator 200 and the reflector 300 and the light detector 500, irradiating infrared or ultrasonic waves to the probe and detecting the return signal Of course, it can be used in place of the sensing structure to measure by.

In addition to the structure driven by the piezoelectric principle, the actuator 400 may be used in place of a structure driven by a step motor.

According to the probe characteristic measuring apparatus of the scanning probe microscope according to the present invention as described above, there is a feature that can perform a simple and clear measurement procedure compared to the characteristic measurement by the addition of micro mass.

In addition, the signal feedback and closed-loop circuit configuration, the natural frequency of the probe is calculated in real time, there is an advantage that the changed characteristics of the probe can be measured quickly.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, various other modifications and variations may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the appended claims cover such modifications and variations as fall within the true scope of the invention.

Claims (4)

A probe of a scanning probe microscope disposed at one side; An actuator connected to the probe such that the probe vibrates minutely; Sensing means correspondingly arranged to sense vibration of the probe; And The detection means to measure the characteristic of the probe on the basis of the natural frequency of the probe that is small by changing the natural frequency of the probe and feedback to the actuator input signal based on the vibration signal of the detection means And a controller electrically connected to the actuator. The method of claim 1, So that the small vibration of the probe can be modulated into an optical signal A light irradiator for irradiating laser light to the probe; And a reflector disposed to correspond to and reflect an optical signal reflected from the probe on the basis of minute vibrations to the sensing means. The method of claim 2, The sensing means is a probe characteristic measuring apparatus of the scanning probe microscope, characterized in that for detecting the change in the laser light of the light signal reflected and incident from the reflector. The method of claim 1, And said actuator is a piezoelectric structure.

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