KR102102637B1 - Topography signal and option signal acquisition apparatus, method and atomic force microscope having the same - Google Patents

Abstract

The present invention relates to a method and apparatus for obtaining a topography signal and an option signal, and an atomic microscope having the same, which can increase the reliability of an image obtained from the signals by obtaining the topography signal and the option signal at a stationary state at every point.
A method for obtaining a topography signal and an optional signal for a surface to be measured according to an embodiment of the present invention, a topography signal and an optional signal for the surface of the measurement object using a cantilever with a tip Is the way to get it. The method includes the step of approaching the cantilever on the surface of the measurement object, and obtaining a topography signal at a specific point using the cantilever while the measurement object is stopped at a predetermined position. ; A lifting step of dropping the cantilever and the measurement object in a Z direction after the topography signal acquisition step; Obtaining an option signal after the lifting step, an option signal obtaining step; And moving at least one of the measurement target and the cantilever in the XY direction. Including, the topography signal acquisition step, the lifting step, the option signal acquisition step and the moving step is repeated at least two times in succession, the option signal when performing one or more of the approaching step and the lifting step Get

Description

A method for obtaining a topography signal and an optional signal, an apparatus and an atomic microscope equipped with the same {TOPOGRAPHY SIGNAL AND OPTION SIGNAL ACQUISITION APPARATUS, METHOD AND ATOMIC FORCE MICROSCOPE HAVING THE SAME}

The present invention relates to a method and apparatus for obtaining a topography signal and an option signal, and an atomic microscope having the same, more specifically, the reliability of an image obtained from signals by obtaining the topography signal and the option signal in a stationary state at every point It relates to a method and apparatus for obtaining a topography signal and an optional signal, and an atomic microscope having the same.

Scanning Probe Microscope (SPM) refers to a microscope that scans and passes a microscopic probe made through MEMS process on the surface of a sample (Scanning) to measure the surface characteristics of the sample and show it in a 3D image. The scanning probe microscope is subdivided into an atomic force microscope (AFM, atomic force microscope), a scanning tunneling microscope (STM), and the like, according to a measurement method.

In the case of an atomic microscope, a probe with a cantilever tip is used. By performing a specific treatment on the cantilever tip, various physical properties of the surface of the sample can be mapped in addition to topography. Typically, there are EFM (Elecrostatic Force Microscopy), MFM (Magnetic Force Microscopy), etc. EFM is an atomic microscope-specific measurement method that maps the electrical properties of a sample surface and MFM is a magnetic property.

EFM is a measurement method that maps the electrical properties of the sample surface by measuring the constant power between the cantilever and the surface to which the bias voltage is applied. In the EFM, a voltage is applied between the tip and the sample while the cantilever tip does not touch the surface and turns over the surface. The cantilever is bent by the constant power between the sample surface and the cantilever tip, and the constant power can be measured.

MFM is similar in measurement method to EFM, but the difference is that the tip is coated with a ferromagnetic thin film or magnetized to use a tip for MFM. In other words, the MFM measures magnetic force with a surface using a magnetic tip.

1 is a schematic perspective view showing the structure of an atomic force microscope, FIG. 2 is a conceptual diagram illustrating the principle of measuring the bending of a cantilever, FIG. 3 is a flow chart illustrating a method of measuring surface properties using an atomic force microscope, and FIG. It is a conceptual diagram explaining the 2 iteration technique used in EFM and MFM.

Referring to FIG. 1, the atomic force microscope 10 includes a cantilever (probe) 11 that follows the surface of the measurement object 1 in a contact or non-contact state, and the measurement object 1 in the X and Y directions in the XY plane. The XY scanner 12 to scan with, the Z scanner 13 connected to the cantilever 11 to move the cantilever 11 with a relatively small displacement in the Z direction, and the cantilever 11 and Z scanner 13 It comprises a Z stage 14 which moves in the Z direction with a relatively large displacement, and a fixed frame 15 that fixes the XY scanner 12 and the Z stage 14.

The atomic force microscope 10 scans the surface of the measurement object 1 with a cantilever 11 to obtain an image such as topography. The relative movement of the surface of the measurement object 1 and the cantilever 11 in the horizontal direction can be performed by the XY scanner 12, and the cantilever 11 is moved up and down to follow the surface of the measurement object 1. This can be done by the Z scanner 13.

Referring to FIG. 2, the deflection of the cantilever 11 can be measured by a laser system. Specifically, the deflection measurement is performed by the photodiode sensor 17 that reflects the laser beam 16 that is scanned and reflected by the cantilever 11. ) Can be performed by sensing. What can be measured by the photodiode sensor 17 may be not only the bending information of the cantilever 11, but also the amplitude or phase when the cantilever 11 is vibrating.

When the topography signal is thus obtained, the cantilever 11 is scanned while the measurement object 1 is scanned along the scan line by the XY scanner 12 with the cantilever 11 being brought into contact with the surface of the measurement object 1. Variation of the vibration of the cantilever 11 without contacting the surface of the measurement object 1 while vibrating the cantilever 11 and the contact mode to obtain a topographic image by measuring the degree of power of For example, a non-contact mode in which a topographic image is obtained by feedbacking frequency, amplitude, phase, etc.) can be implemented as the system of FIG. 2.

Referring to FIG. 3, the measurement object 1 has a surface whose surface characteristics are changed along the scan line (S10), whereby the interaction force between the cantilever tip and the measurement object 1 surface is changed ( S20). This change causes bending of the cantilever 11 (in contact mode) or change in amplitude and phase of vibration of the cantilever 11 (in non-contact mode) (S30). Due to this, the laser signal measured by the photodiode sensor 17 is changed (S40), and the changed laser signal is transmitted to the atomic force microscope (or controller) as an electrical signal (S50). By processing this electrical signal, a two-dimensional or three-dimensional image is generated (S60), and accordingly, surface characteristics of the surface of the measurement object 1 are mapped.

Here, the surface properties may be topography, electrical properties, magnetic properties, thermal properties, etc. Basically, the method of mapping these properties follows the measurement method of FIG. 3. In particular, the electrical and magnetic properties can be obtained by applying a bias voltage to the cantilever 11 (for EFM) or by applying a ferromagnetic thin film coating to the cantilever 11 surface (for MFC), which is This is to generate a mutual force by generating a force (static power, magnetic force, etc.) other than the van der Waals force used when obtaining topography.

Inevitably, mutual forces can overlap each other, for example, the van der Waals force can be influenced when measuring constant power in EFM mode. In this case, an image in which the electrical characteristics of the surface to be measured (1) is mapped may reflect a curvature of the surface, and thus an image with low reliability may be obtained. Therefore, it is important in terms of image reliability to separate overlapping forces to obtain non-overlapping EFM or MFM images.

To solve the above problems, the force range technique and the two pass technique were developed in the art. The force range technique is a first scan to obtain a topographic image by scanning the tip in a region where van der Waals forces predominate, and by changing the set point to move and scan the tip into a region predominantly electrostatic or magnetic force to scan the EFM or MFM image. Say how to get.

Referring to FIG. 4, the second repetition technique obtains a topography image in the first scan, increases the distance between the tip-surface to be measured in the second scan, and a bias voltage is applied along the shape line of the surface obtained in the first scan. Refers to a method of obtaining an EFM image by scanning a tip (this is explained in terms of EFM, but MFM is similar).

Since the shape line is a line having a constant distance between the tip and the surface to be measured, and consequently, the van der Waals force is the same as a constant line, the change in force affecting the signal of the second scan is only a change in static power. Accordingly, it is possible to obtain an EFM image in which the topography image is not superimposed.

However, the above-described two-repeat technique requires that the cantilever 11 is accurately moved along the contour line in the second scan after the first scan, and the reliability of the image is inevitably questioned if it is not secured. In addition to increasing the precision of the XY scanner 12 and the Z scanner 13, in order to increase the reliability of the image through the two-time iteration technique, position variation factors that may be caused by a time difference between the first scan and the second scan ( For example, it is necessary to minimize thermal drift and creep.

Moreover, in the first scan, the static power may affect the tip to some extent, and the interference of the static power may distort the topographic image. Accordingly, even if it moves along the shape line of the second scan obtained using the topography image, there is a possibility that the distance between the tip and the surface to be measured is not kept constant.

However, Atomic Force Microscopy has proposed a solution for minimizing the position fluctuation factors caused by the time difference between the first scan and the second scan, and a method for keeping the distance between the tip and the surface to be measured constant during the second scan. The device is not currently disclosed.

The present invention has been devised to solve the above problems, and the problem to be solved in the present invention is to increase the reliability of an image obtained from signals by obtaining a topography signal and an option signal in a stopped state at every point. It is to provide a method and apparatus for obtaining a topography signal and an optional signal, and an atomic microscope having the same.

The problems of the present invention are not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The method for obtaining a topography signal and an optional signal for a surface to be measured according to an embodiment of the present invention for solving the above problems is a topography signal for a surface of a measurement object using a cantilever with a tip and This is how to get the option signal. The method includes: obtaining a topography signal at a specific point using the cantilever while the measurement object is stopped at a predetermined position; A lifting step of dropping the cantilever and the measurement object in the Z direction after the topography signal acquisition step; Obtaining an option signal after the lifting step, an option signal obtaining step; And moving at least one of the measurement target and the cantilever in the XY direction. It includes, the topography signal acquisition step, the lifting step, the option signal acquisition step and the moving step is repeated at least twice in succession.

Further, according to another feature of the present invention, the step of obtaining the option signal is performed after waiting for the vibration of the cantilever to disappear.

Further, according to another feature of the present invention, when the lifting step is repeated, the height between the cantilever and the measurement object is constant.

Further, according to another feature of the present invention, in the moving step, the measurement object is scanned in a straight line along a straight scan line.

Further, according to another feature of the present invention, the step of acquiring the topography signal includes approaching the cantilever to the surface of the measurement object.

In addition, according to another feature of the present invention, the approaching step is a step of approaching the cantilever to contact the surface of the measurement object, and the lifting step of extracting a force-distance curve It further includes.

Further, according to another feature of the present invention, in the approaching step or the lifting step, the cantilever is approached or lifted in a sine motion.

Further, according to another feature of the present invention, in the moving step, the measurement object is moved in a sine motion.

Further, according to another feature of the present invention, the option signal is a signal by an electric force or a signal by a magnetic force.

Further, according to another feature of the present invention, an optional signal is obtained when performing the lifting step.

In addition, according to another feature of the present invention, when performing the approaching step, an option signal is obtained.

In addition, according to another feature of the present invention, further comprising the step of performing a three-dimensional mapping according to the height using the option signal obtained when performing the lifting step.

In addition, according to another feature of the present invention, further comprising the step of performing a three-dimensional mapping according to the height using the option signal obtained when performing the approach step.

Further, according to another feature of the present invention, further comprising the step of determining a lifting parameter (lifting parameter) in the lifting step using the three-dimensional map obtained in the step of performing the three-dimensional mapping.

An apparatus for acquiring a topography signal and an option signal according to an embodiment of the present invention for solving the above problems includes: XY moving means for relatively moving at least one of a measurement target and a cantilever in an XY direction; Z moving means for moving at least one of the measurement object and the cantilever relative to the Z direction; And a control device that controls movements of the XY moving means and the Z moving means and receives signals obtained from the cantilever. Including, the control device, the XY moving means in a state of stopping the cantilever with the Z moving means to approach the specific point to obtain the topography signal of the specific point, and then the Z moving means to the cantilever By lifting in the Z direction from the measurement object, and then obtaining an option signal, a topography signal and an option signal at the specific point are obtained, and then at least one of the measurement object and the cantilever is obtained using the XY moving means. It is characterized in that the XY moving means and the Z moving means are controlled so as to repeat at least two times in succession to obtain a topography signal and an optional signal at a specific point different from the specific point by moving in the XY direction.

Further, according to another feature of the present invention, the XY moving means is an XY scanner configured to move the measurement object in the XY direction.

Further, according to another feature of the present invention, the Z moving means is a Z scanner configured to move the cantilever in the Z direction.

Further, according to another feature of the present invention, the option signal is a signal by an electric force or a signal by a magnetic force.

The atomic microscope according to an embodiment of the present invention for solving the above problems includes the above-described topography signal and an optional signal acquisition device.

According to the method and apparatus for obtaining a topography signal and an option signal according to the present invention, the topography signal is not superimposed on the option signal, and the tip-to-pixel distance is maintained at a constant distance at each point, and thus the time is not changed. Accordingly, it is possible to obtain a more reliable option image by minimizing deformation caused by heat or creep. In addition, according to the above-described method and apparatus for obtaining the topography signal and the option signal, since the topography signal and the option signal are obtained in a stopped state, moving averaging by the existing topography signal and the option signal obtained while moving By minimizing the effect, a clearer topography signal and an optional signal can be obtained. In addition, it is possible to obtain a more reliable signal by minimizing the overlap of the option signal with the topography signal.

1 is a schematic perspective view showing the structure of an atomic force microscope.
2 is a conceptual diagram illustrating the principle of measuring the bending of a cantilever.
3 is a flowchart illustrating a method of measuring surface properties using an atomic force microscope.
4 is a conceptual diagram illustrating a two-time iteration technique utilized in EFM and MFM.
5 is a plan view of the measurement surface of the measurement object as viewed from above.
6 is a flowchart of a method for obtaining a topography signal and an option signal of a surface to be measured according to an embodiment of the present invention.
7 is a conceptual diagram schematically showing an approach state.
8 is a graph showing the movement method and the AB signal of the XY scanner and the Z scanner.
Fig. 9 is a graph showing the movement method and the AB signal of the XY scanner and the Z scanner in the case of obtaining the option signal in the lifting step and the approach step.
10 are diagrams for explaining that 3D mapping is performed with the option signal obtained in the method of FIG. 9.
11 shows a three-dimensional map and cross-sectional view of an option signal obtained by obtaining an option signal during a lifting step or approach.
12 is a graph of the bending value obtained while approaching the cantilever and the amount of current applied to the cantilever using the CCM method of SThM.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and the ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims.

An element or layer being referred to as another element or layer "on" includes all instances of other layers or other elements immediately above or in between.

Although the first, second, etc. are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are only used to distinguish one component from another component. Therefore, it goes without saying that the first component mentioned below may be the second component within the technical spirit of the present invention.

The same reference numerals refer to the same components throughout the specification.

The size and thickness of each component shown in the drawings are illustrated for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated component.

Each of the features of the various embodiments of the present invention may be partially or totally combined with or combined with each other, and technically various interlocking and driving may be possible as those skilled in the art can fully understand, and each of the embodiments may be independently implemented with respect to each other. It can also be implemented together in an association relationship.

1. Basic topography signal and optional signal acquisition method and device

Hereinafter, a method and apparatus for obtaining a topography signal and an optional signal on a surface to be measured according to the present invention will be described with reference to the accompanying drawings.

The method of obtaining the topography signal and the optional signal of the surface to be measured can be utilized in various devices, but for convenience of explanation, it is exemplified that it is implemented in the atomic microscope 10 of FIGS. 1 and 2.

5 is a plan view of the measurement surface of the measurement object as viewed from above, and FIG. 6 is a flowchart of a method for obtaining a topography signal and an option signal of the measurement object surface according to an embodiment of the present invention. In addition, FIG. 7 is a conceptual diagram schematically showing the approach state, and FIG. 8 is a graph showing the movement method and the A-B signal of the XY scanner and the Z scanner.

Referring to FIG. 5, in the atomic microscope 10 as shown in FIG. 1, a topography signal and an optional signal can be obtained by scanning a rectangular scan area MA among the surfaces of the measurement object 1. The portion of the scan area MA that acquires a signal is indicated by points A1, A2, A3 ..., and a topography signal and an optional signal are obtained for each of these points (ie, pixels). These points may be mapped in a grid form and set in advance.

The measurement order of the points on the surface of the measurement object (1) can be variously set, for example, A1 (1, 1) → A2 (2, 1) → A3 (3, 1). In this case, the scan line l ₁ is formed in a direction parallel to the X axis.

When the acquisition of the signal on the scan line l ₁ is completed, the scan on the next scan line l ₂ proceeds. At this time, the scan may proceed from the point on the right to the point on the left, or vice versa. The scan direction can be freely selected. For example, the scan line may or may not be parallel to the Y axis. However, considering the complexity of the image processing process after acquiring the signal, it is preferable that the scan line is straight as shown in FIG. 5.

When signal acquisition at all points in the scan area MA is completed, an image according to a topography signal at each point and an optional signal can be schematically derived by processing by a controller (not shown). Hereinafter, a specific signal acquisition method will be described with reference to FIGS. 6 to 8.

Referring to FIG. 6, a method for obtaining a topography signal and an optional signal on a surface to be measured according to an embodiment of the present invention includes a topography signal acquisition step (S110), a lifting step (S120), and an optional signal acquisition step (S130) , It comprises a moving step (S140).

First, a topography signal at a specific point is obtained using a cantilever (ie, a probe) 11 while the measurement object 1 is stopped at a predetermined position (S110). The topography signal can be obtained by placing the tip formed on the cantilever 11 in an approach state to the surface of the measurement object 1. Here, the specific point may be a predetermined point such as A1, A2, A3 of FIG. 5.

As shown in FIG. 7, the approach state refers to a state prepared to obtain a topography signal while being able to feedback in a state in which an interaction force is applied to a certain degree by a van der Waals force with the surface of the object to be measured (1). , This approach state may be variously defined according to the measurement mode of the atomic force microscope 10. For example, such an approach state is a state in which the tip of the cantilever 11 is brought into contact with the surface of the measurement object 1, so that it is fed back in a state of being deflected to a certain degree [this is called an approach state in contact mode]. ], And the cantilever 11 is vibrated at a resonant frequency and then brought close to the surface of the object 1 to be measured, and the cantilever 11 is moved in a state in which the oscillating frequency is moved to a certain degree without contacting the surface of the object 1 to be measured. It may include a state that is fed back so that it is located (this is called an approach state in a non-contact mode). In addition, the approach state may also include a state in which the cantilever 11 is fed back by hitting the surface of the measurement object 1 while vibrating at a constant frequency (this is referred to as an approach state in a tapping mode). .

The topography signal corresponds to a signal relating to the height of the cantilever 11 when the cantilever 11 is positioned in an approach state, for example, a length signal of the Z scanner 13 in a feedback on state (Z servo on). Here, the length signal of the Z scanner 13 may be a length variation signal of the actuator that drives the Z scanner 13, for example, a voltage signal applied to the actuator, or a strain gauge sensor attached to the actuator. It may be a signal related to the length of the actuator measured by. In addition, the topography signal may be obtained in various ways, and may include known methods.

That is, the topography signal is obtained within a region where mutual forces due to van der Waals forces between the surface of the measurement object 1 and the tip of the cantilever 11 are applied. Accordingly, the cantilever 11 is lowered to be in an approach state with the surface of the measurement target 1.

After the approach, the topography signal is obtained while waiting for a certain period of time. In this case, it is desirable to maintain the feedback-on state. The feedback-on state refers to a state in which the Z scanner 13 is fed back in contact with each other so that the cantilever bending is maintained at a certain level in the contact mode, and in the non-contact mode, the resonance of the cantilever The state in which the Z scanner 13 is fed back is shown so that the frequency is maintained at a constant frequency. That is, the feedback-on state means a state in which the feedback operates to maintain a constant distance between the tip of the cantilever 11 and the surface of the measurement object 1, or to allow the bending of the cantilever 11 to be constant.

Here, the constant time for obtaining the topography signal may be several milliseconds, for example, 2 to 3 ms. The topography signal may be obtained by measuring multiple times and obtaining an average value, or may be obtained by other methods.

When the topography signal is obtained, the cantilever 11 is lifted from the surface of the measurement object 1 in the Z direction (S120). At this time, it is preferable to first make the feedback off state (Z servo off) and then lift the cantilever (11).

The height at which the cantilever 11 is lifted is varied so that the optional signal can be effectively obtained without obtaining a topography signal (i.e., a van der Waals force having little or no effect on the cantilever 11). Can be set. For example, when an EFM signal is to be obtained as an optional signal, the height at which the cantilever 11 is lifted may be about 50 to 200 nm. Since the setting of the height may vary depending on the size of the electrical and magnetic forces of the measurement object 1, the type of the measurement object 1, etc., it may be appropriately selected during measurement. In addition to this, the height may be appropriately selected by measurement, which will be described later in detail.

In addition, it is preferable that the height at which the cantilever 11 is lifted is set to be constant when the lifting step S120 is repeated. That is, it is preferable to set the height at which the cantilever 11 is lifted during the image of one scan area MA.

On the other hand, when the cantilever 11, which was approached in the contact mode, is lifted, the degree of bending of the cantilever 11 by the photodiode sensor 17 can be measured, and utilizing this, force-distance curve This can be obtained. According to the force-distance curve, surface information such as viscosity of a surface contaminant and thickness of a lubricating material can be obtained. Therefore, if you want to obtain more force-distance curves, it is desirable to obtain a topography signal after approaching in contact mode.

On the other hand, it is also possible to obtain an option signal in the lifting step (S120). This will be described later in detail.

After the lifting step (S120), an option signal is obtained (S130). Here, the option signal may be an electrical force signal (EFM signal) or a magnetic force signal (MFM signal).

Specifically, immediately after the lifting step (S120), for example, AC bias is applied to the cantilever 11 (for EFM) or the cantilever 11 is vibrated (for MFC). Details will be described later.

Additional preparation may be necessary for a basic atomic microscope to obtain an optional signal. For example, in order to obtain an EFM signal, the cantilever 11 must be coated with a conductive material, and in order to obtain an MFM signal, the cantilever 11 must be coated with a ferromagnetic material or magnetized by an external magnet. Examples of cantilevers for EFM include NSC14 / CR-AU, NSC36 / CR-AU from Micromasch, PPP-NCSTAu, PPP-EFM, CDT-CONTR, CDT-NCHR from Nanosensors, etc. have.

Various methods can be adopted to obtain the option signal. For example, in order to measure electrical force, AC biases having the form of V _ac cosωt are applied to the measurement object 1 and the cantilever 11, respectively, and vibration information of the cantilever 11 is transmitted from the photodiode sensor 17. Processed by a lock in amplifier to obtain the amplitude and phase for the cantilever 11 vibrating at ω. Here, the amplitude and phase for ω are varied by the constant power between the cantilever 11 and the surface of the measurement object 1, and measurement of this can provide information on the electrical force.

In addition, for example, to measure the magnetic force, after vibrating the cantilever 11 at a constant frequency, a change in amplitude or phase of vibration of the cantilever due to magnetic force is obtained. Therefore, the amplitude and phase (or the amount of change) of the vibration of the cantilever may correspond to the MFM signal. Again, a lock-in amplifier can be used.

On the other hand, it should be noted that the lock-in amplifier may be embedded inside the controller of the atomic microscope, or may be separately provided outside.

In addition to the EFM signal and the MFM signal described above, there may be various types of option signals. It should be noted that the option signals collectively refer to signals other than the topography signal. For example, the SThM signal (SThM error value, current applied to the cantilever, bending value, etc.) may also be included in this. However, since the SThM signal is obtained by a method different from that of obtaining the EFM signal and the MFM signal, this will be described later separately.

On the other hand, immediately after the lifting step 120S is completed, since vibrations that occur when the cantilever 11 falls from the measurement object 1 may remain, it is preferable to wait for a certain period of time to obtain an option signal.

In addition, as shown in FIG. 8, the option signal acquisition step (S130) may be maintained for a certain period and a measurement value may be averaging, in which case a more accurate option signal may be obtained.

The measurement object is moved in the XY direction (S140). Here, the moving step (S140) should be performed after the option signal obtaining step (S130) is completed.

If the topography signal and the optional signal in A1 (1, 1) are obtained in Fig. 5, the cantilever tip is facing A2 (2, 1) after completion of the moving step (S140). That is, the measurement target 1 or the cantilever 11 may be moved to A2, the next point for measurement. In this case, if it is determined that the predetermined scan has not been completed (No in S150), the topography signal acquisition step (S110) is repeated, and the lifting step (S120), the optional signal acquisition step (S130), and the moving step (S140) are sequentially performed. Is repeated. When the acquisition of signals at all points to be measured is repeated and completed (Yes in S150), the method ends.

Referring to FIG. 8, the above-described steps will be described again with a graph of a movement amount in the XY direction, an A-B signal, and a movement amount in the Z direction over time.

Referring to (a) of FIG. 8, the measurement object 1 is not continuously moved in the XY direction, but is moved in one direction (ie, the scan direction) while having a stop section excessively. Further, referring to FIG. 8 (c), the distance between the tip of the cantilever 11 and the surface of the object to be measured 1 is periodically close and farther away, but has a stop section excessively.

Referring to FIG. 8 again, in the topography signal acquisition step (S110), the cantilever 11 is moved downward in the Z direction to approach the surface of the measurement object 1 and acquires the topography signal for a certain time. At this time, the measurement target 1 does not move in the XY direction. Thereafter, the cantilever 11 is lifted in the Z direction (S120), and then an option signal is obtained while the movement in the Z direction is stopped (S130). While obtaining the option signal, the measurement target 1 is not moved in the XY direction (S130) and is stopped. When the option signal is obtained, the measurement object 1 is moved in the XY direction (S140), and then the topography signal acquisition step (S110) is started again at another point.

Referring to FIG. 8B, the signal acquisition method will be described. The A-B signal refers to the difference between the voltages obtained in the upper region and the lower region of the photodiode sensor 17 of FIG. 2, and as a result, means the degree of deflection of the cantilever 11.

While the tip is approached to the surface of the object to be measured (1), the cantilever (11) moves downward toward the object to be measured (1) in the Z direction. ), The moment the tip touches the surface (or the moment it is affected by the van der Waals force), the cantilever 11 bends (increases the AB signal), and after completing the approach, the AB signal is fed back on (Z servo on).

Then, after obtaining the topography signal and raising the cantilever 11 again, the A-B signal is reduced again. Thereafter, in the step of acquiring the optional signal (S130), the cantilever 11 is vibrated by the interaction of AC bias and constant power (for EFM), and the interaction between the magnetic force and magnetic force of the tip (for MFC), and AB The signal vibrates. After the option signal acquisition step (S130), the A-B signal remains constant again.

On the other hand, in the approach process (included in S110) and in the lifting step (S120), the cantilever 11 is approached or lifted in a sine motion to minimize vibration after stopping, the tip of the cantilever 11 It is preferable in that it can prevent damage.

In addition, it is preferable in the moving step (S140) that the object to be measured (1) is moved in a sine motion to minimize vibration after stopping.

The method for obtaining the topography signal and the optional signal on the surface of the measurement object 1 described above can be performed by an atomic force microscope (AFM). Hereinafter, a specific device configuration will be described with reference to FIGS. 1 and 2.

The performing of the moving step S140 can be performed by XY moving means. The XY moving means relatively moves at least one of the measurement target 1 and the cantilever 11 in the XY direction. In the example of FIG. 1, the XY moving means moves the measurement object 1 in the XY direction as the XY scanner 13.

As an example of an XY scanner, reference may be made to Korean Patent Publication No. 10-2004-0106699 and Korean Patent Publication No. 10-2014-0065031, in addition, between the measurement object (1) and the cantilever (11) in the XY direction. Any type of scanner can be used as long as it is a scanner capable of precisely positioning relative positions.

The performance of the topography signal acquisition step (S110) and the lifting step (S120) can be performed by Z moving means. The Z moving means relatively moves at least one of the measurement target 1 and the cantilever 11 in the Z direction. In the example of FIG. 1, the Z moving means is the Z scanner 14, and moves the cantilever 11 in the Z direction.

As an example of the Z scanner, reference may be made to Korean Patent Publication No. 10-2003-0068375 and Korean Patent Application No. 10-2013-0078245, in addition, between the measurement object 1 and the cantilever 11 in the Z direction. Any type of scanner can be used as long as it is a scanner capable of precisely positioning relative positions.

The control device controls the movement of the XY moving means and the Z moving means, receives signals obtained from the cantilever 11, and processes them. The control device generates a control signal so that the XY driving means and the Z driving means can be moved as shown in FIG. 8 described above, and sends them to the XY driving means and the Z driving means, and performs feedback in the feedback on state of the cantilever 11, Constructed to create a topography image from the obtained topography signal, and perform an image for the option signal (e.g., EFM amplitude image, EFM phase image, MFM amplitude image, MFM phase image, etc.) with the obtained option signal, etc. do.

The control device may include a controller composed of several boards, a computer, and a lock-in amplifier. That is, the control device may be a system in which everything is built in one, or may be a set of devices that physically separate and perform each function.

Meanwhile, a known system may be used for the laser systems related to FIGS. 1 and 7, and a system of Korean Patent Registration No. 10-0646441 may also be used.

According to the above-described method and apparatus for obtaining the topography signal and the option signal, the topography signal is not superimposed on the option signal, and the tip-for-pixel distance is maintained at a constant distance. By minimizing the deformation caused by heat or creep, it is possible to obtain a more reliable option image. Further, according to the above-described method and apparatus for obtaining the topography signal and the option signal, since the topography signal and the option signal are obtained in a stopped state, moving averaging by the existing topography signal and the option signal obtained while moving By minimizing the effect, a clearer topography signal and an optional signal can be obtained. In addition, it is possible to obtain a more reliable signal by minimizing the overlap of the option signal with the topography signal.

2. 3D mapping by acquiring optional signals during the lifting phase or approaching

Hereinafter, it is described that the option signal is obtained in the lifting step (S120) or approaching (S111) and 3D mapped data is obtained through the option signal.

Fig. 9 is a graph showing the movement method and AB signal of the XY scanner and the Z scanner in the case of obtaining the option signal in the lifting step and the approach step, and Fig. 10 performs three-dimensional mapping with the option signal obtained in the method of Fig. 9 These are drawings for explaining.

For 3D mapping, basically, the method of the above-described embodiment is followed. Here, the detailed description of the steps already described is omitted, and only the added configuration will be described in detail.

Referring to FIG. 9, the method for acquiring the topography signal and the option signal of the present embodiment is characterized in that the option signal is obtained even while performing the lifting step S120. That is, while lifting the cantilever 11 using the Z scanner 13, the same operation as in the optional signal acquisition step S130 is obtained to obtain the optional signal.

Also, an option signal may be obtained during the approach (S111) during the topography signal acquisition step (S110). In the present embodiment, it is exemplified to obtain the option signal both in the lifting step (S120) and during the approach (S111), but only one of them may obtain the option signal.

Referring to FIG. 10, through the method of this embodiment, an option signal at each point in the XYZ direction of the cantilever 11, that is, in three dimensions, is obtained. Through this, it is possible to map the option values at the same height (ie, cross-section), and it is also possible to map the contours by connecting parts with the same option signal values. Through this mapping, the distribution of the option signal in the 3D space can be intuitively understood and easily understood.

3. Parameter tuning using 3D mapping

After performing the 3D mapping as described above, it is possible to calculate an appropriate lifting height in the lifting step S120 using the 3D map. This will be described with reference to FIG. 11.

11 shows a three-dimensional map and cross-sectional view of an option signal obtained by obtaining an option signal during a lifting step or approach.

Referring to FIG. 11, a two-dimensional map at each lifting height can be obtained in the form of a cross-sectional view. The sharpness or contrast of the image of the 2D map thus obtained is calculated. The method of calculating the sharpness or contrast may be a known method.

The lifting height of the cantilever may be determined by using a height having the maximum value of the obtained sharpness or contrast. Here, as a method of determining the lifting height, a variety of methods may be adopted, such as determining the maximum height of sharpness or contrast, or determining a value larger than the maximum height as the lifting height.

The parameter tuning method is preferably performed first before the method of FIG. 6 is performed to obtain the option signal in earnest. At this time, since the tuning of the parameter is not performed to obtain an accurate 3D map, but is performed to determine an appropriate lifting height, it is preferable to reduce the measurement time by performing a measurement point. For example, if the desired measurement point of the 3D map is 256X256X16, the measurement point for parameter tuning can be set to 128X128X8.

Using this parameter tuning method, it is possible to automatically select the optimal lifting height.

4. Application in SThM mode

SThM is a mode of atomic force microscope used to measure the temperature and thermal conductivity of a sample surface. The cantilever (probe) for SThM is sensitive to measure the change in local temperature, and can be manufactured using, for example, a thermocouple. However, the present invention is not limited thereto, and the structure of the cantilever and device for SThM can be used without a known technique.

SThM measurement methods include TCM (temperature contrast mode) and CCM (conductivity contrast mode). CCM is used to measure thermal conductivity. CCM is performed by flowing a current through the cantilever to self-heat the cantilever and controlling the current so that the cantilever maintains a constant temperature. The current applied to the cantilever is used to image the contrast of thermal conductivity.

12 is a graph of the bending value obtained while approaching the cantilever and the amount of current applied to the cantilever using the CCM method of SThM.

Referring to FIG. 12, it can be seen that when the cantilever gradually approaches the sample, the amount of current applied to the cantilever gradually increases without bending before the cantilever contacts the sample. This is thought to be due to the heat transfer between the air and the cantilever.

The contact of the cantilever with the sample can be seen through the graph of A-B. That is, when the cantilever starts to bend, the cantilever is in contact with the sample, and the amount of current applied to the cantilever increases rapidly at the moment of contact. Thereafter, the amount of current is almost constant after the contact.

Here, when the amount of current that is rapidly and discontinuously increased, that is, ΔC, the thermal characteristics of the sample can be known. It can also be used to calculate local thermal conductivity. These techniques can be performed without limitation through known methods.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, a person skilled in the art to which the present invention pertains may be implemented in other specific forms without changing the technical spirit or essential features of the present invention. You will understand. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

One… Measurement target 10… Atomic microscope
11… Cantilever 12… XY scanner (XY vehicle)
13… Z Scanner (Z Vehicle) 14… Z stage
16… Laser light 17… Photodiode sensor

Claims (19)

As a method for obtaining a topography signal and an option signal for a surface of a measurement object using a cantilever with a tip,
A step of approaching the cantilever to the surface of the measurement object, and obtaining a topography signal at a specific point using the cantilever while the measurement object is stopped at a predetermined position;
A lifting step of dropping the cantilever and the measurement object in the Z direction after the topography signal acquisition step;
Obtaining an option signal after the lifting step, an option signal obtaining step; And
A moving step of moving at least one of the measurement object and the cantilever in an XY direction; It includes,
The topography signal acquisition step, the lifting step, the option signal acquisition step and the moving step are repeated at least twice in succession,
A method for obtaining a topography signal and an option signal for a surface to be measured, characterized in that an option signal is obtained when performing one or more of the approaching step and the lifting step. delete delete delete delete According to claim 1,
The lifting step is characterized in that it further comprises the step of extracting a force-distance curve (Force-Distance Curve), a method for obtaining a topography signal and an optional signal for a surface to be measured. delete delete According to claim 1,
The option signal, characterized in that at least one of a signal by electrical force, a signal by magnetic force, and a signal by temperature, a method for obtaining a topography signal and an option signal for a surface to be measured. delete delete According to claim 1,
Obtain an option signal at least when performing the lifting step,
And performing a three-dimensional mapping according to a height using an option signal obtained when performing the lifting step, a method for obtaining a topography signal and an option signal for a surface to be measured. According to claim 1,
At least the option signal is obtained when performing the approach step,
And performing a three-dimensional mapping according to height using an option signal obtained when performing the approaching step. The method of claim 12 or 13,
And determining a lifting parameter in the lifting step using the 3D map obtained in the step of performing the 3D mapping, a topography signal and options for a surface to be measured. Signal acquisition method. XY moving means for relatively moving at least one of the measurement object and the cantilever in the XY direction;
Z moving means for moving at least one of the measurement object and the cantilever relative to the Z direction; And
A control device that controls movements of the XY moving means and the Z moving means and receives signals obtained from the cantilever; It includes,
The control device approaches the cantilever with the Z moving means at a specific point while the XY moving means is stopped to obtain a topography signal at the specific point, and then uses the Z moving means to move the cantilever from the measurement target. By lifting in the Z direction, and then obtaining the option signal, the topography signal and the option signal at the specific point are obtained, and then at least one of the measurement object and the cantilever is moved in the XY direction using the XY moving means. By repeating at least two successive acquisitions of a topography signal and an optional signal at a specific point different from the specific point, and while approaching the cantilever to a specific point and lifting the Z-direction from the measurement object. To get the optional signal from one or more, the XY Means for obtaining, and the topography signal option signal, characterized in that for controlling the Z movement device means. The method of claim 15,
The XY moving means is characterized in that the XY scanner configured to move the measurement object in the XY direction, a topography signal and an optional signal acquisition device. The method of claim 15,
The Z moving means is a Z scanner configured to move the cantilever in the Z direction, a topography signal and an optional signal acquisition device. The method of claim 15,
The option signal is characterized in that at least one of a signal by electrical force, a signal by magnetic force, and a signal by temperature, a device for obtaining a topography signal and an option signal. An atomic microscope comprising the apparatus for obtaining the topographic signal and an optional signal according to any one of claims 15 to 18.

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