JPH07181036A - Scanning probe measuring system and measuring method - Google Patents

Abstract

PURPOSE:To enhance the reliability of measurement data by storing a plurality of measurement data, attained by scanning on one scanning line a plurality of times, in a memory means and calculating the average value of a plurality of measurement data read out therefrom. CONSTITUTION:An XYZ stage 12 is shifted in XYZ direction by means of an XYZ positioning system 13. When the surface profile of a sample 11 is measured, the surface of sample 11 is set at a position spaced apart slightly from the point of a probe 15 and the initial positional data Z0 in Z direction is stored in a memory section 21. The stage 12 is then shifted in X direction and the positional data (X1Y1Z1, X2Y2Z2) in X and Z directions are stored at each moment of time. The measurement is repeated at each angle. An operating section 23 reads out the data Z0 and the first and second time data (X1Y1Z1, X2Y2Z2) from the memory section 21 to prepare line profiles which are then added and divided by 2 thus producing an average line profile. This constitution reduces vibration and noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe measuring system and a measuring method using the same.

[0002]

2. Description of the Related Art A scanning probe measuring technique is a technique for measuring the geometrical shape of the surface of a sample by using a scanning probe microscope (SPM). SPM
Is an atomic force microscope (AFM).
e) and scanning tunneling microscope (STM: Scanning Tunnel M
icroscope) and the like, but the operation principle of the former AFM will be described as an example with reference to FIG.

When the tip portion of the probe 2 provided on the lower surface of the tip portion of the cantilever 1 is brought closer to the surface 3a of the sample 3 (Z direction), atoms near the surface 3a of the sample 3 are atomized by atoms of the sample 3. Due to the existence of the region 4 to which the interfacial force is exerted, the cantilever 1 is flexed by the repulsive force due to the atomic force, and the tip of the probe 2 is held at a position slightly separated from the surface 3a of the sample 3. It Then, while controlling this state, that is, the repulsive force due to the atomic force, to be maintained constant,
When the probe 2 is moved in the X direction, the repulsive force due to the atomic force reflects the geometrical shape of the surface 3a of the sample 3, so that the tip of the probe 2 moves in the Z direction toward the surface of the sample 3. It is moved in the X direction while being displaced along the unevenness of 3a. This makes it possible to measure the movement position of the tip of the probe 2 in the X direction and the displacement amount in the Z direction at the movement position.
In this way, by scanning the probe 2 in the XY directions, the geometrical shape of the surface 3a of the sample 3 can be three-dimensionally measured.

[0004]

However, in such a conventional scanning probe measuring method, physical vibration or sound
There was a problem that the reliability of measurement data was poor due to the influence of (air vibration). In addition, if you take perfect anti-vibration and soundproofing measures, such a problem will not occur, but it is not only extremely difficult as a practical problem, but above all there is a big merit that it can be installed and used easily. It will fade. An object of the present invention is to provide a scanning probe measuring system and a measuring method using the scanning probe measuring system, which can improve the reliability of measurement data even under the influence of physical vibration or sound.

[0005]

The invention according to claim 1 is
In a scanning probe measuring system for measuring the geometrical shape of the surface of a sample with a probe, a storage means for storing a plurality of measurement data for the same scanning line obtained by scanning the same scanning line a plurality of times, And an arithmetic means for calculating an average value based on a plurality of measurement data for the same scanning line called from the storage means. According to the invention of claim 2, in a scanning probe measuring system for measuring the geometrical shape of the surface of the sample by a probe, a storage means for storing a plurality of measurement data obtained by performing a plurality of XY direction scans. And an arithmetic means for calculating an average value thereof based on the plurality of measurement data retrieved from the storage means. According to a third aspect of the present invention, the geometrical shape of the surface of the sample is measured by the scanning probe measuring system according to the first or second aspect.

[0006]

According to the present invention, when the same scan line is measured a plurality of times, the geometrical shape of the surface of the sample corresponding to the scan line is always constant, whereas the physical vibration or Since the effect of sound is random, calculating the average value based on multiple measurement data for the same scan line can reduce physical vibration and noise due to the effect of sound, and thus The reliability of the measurement data can be improved even when affected by sound.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic structure of a scanning probe measuring system according to an embodiment of the present invention. This scanning probe measuring system is provided with an XYZ on which a sample 11 is placed.
The stage 12 is provided. XYZ stage 12 is X
By driving an X-direction modulation piezo (not shown), a Y-direction modulation piezo (not shown), and a Z-direction modulation piezo 12a, which are driven and controlled by the YZ positioning system 13,
Direction, Y direction and Z direction. A cantilever 14 is fixedly arranged above the XYZ stage 12. A probe 15 is provided on the lower surface of the tip of the cantilever 14.

A laser source 16 is provided above the tip of the cantilever 14. The laser light 17 from the laser source 16 is reflected by the upper surface of the tip portion of the cantilever 14 and input to the sensor 18. That is, the sensor 18 receives the laser beam 17 reflected by the upper surface of the tip of the cantilever 14 to expand the amount of bending of the tip of the cantilever 14, that is, the amount of displacement of the probe 15 in the Z direction by an optical lever method. Is detected.
Then, the sensor 18 sends a detection signal corresponding to the amount of displacement of the probe 15 in the Z direction to the AFM feedback system 19. The AFM feedback system 19 sends a Z direction drive control signal corresponding to the detection signal from the sensor 18 to the X direction.
The data is sent to the YZ positioning system 13. XY
The Z positioning system 13 responds to the Z direction drive control signal from the AFM feedback system 19 to move the Z of the XYZ stage 12 to the Z position.
The direction modulation piezo 12a is driven and controlled, and the Z direction drive control signal at that time is sent to the A / D converter 20. The A / D converter 20 converts the Z-direction drive control signal (voltage), which is an analog signal, into Z-direction position data, which is a digital signal, and sends it to the memory unit 21. The memory unit 21 is connected to the system control unit 22.

The system control unit 22 is for controlling the entire circuit of the scanning probe measuring system.
In addition to the memory unit 21, the system control unit 22 includes
An XYZ positioning system 13, a sensor 18, an AFM feedback system 19, a calculation unit 23, etc. are connected. Of these, the memory unit 21 is the X that is sent from the system control unit 22.
The direction position data and the Y direction position data, the Z direction position data sent from the A / D conversion unit 20, the operation data sent from the operation unit 23 are temporarily stored, and other processing data are temporarily stored. To do. The arithmetic unit 23 performs a predetermined arithmetic operation based on the data called from the memory unit 21 and sends the arithmetic data to the memory unit 21.

Next, the case of measuring the geometrical shape of the surface of the sample 11 with this scanning probe measuring system will be described. First, the sample 11 is placed at a predetermined position on the XYZ stage 12. Then, from the system control unit 22
When the initial state setting signal is sent to the Z positioning system 13,
A rising drive signal is sent from the XYZ positioning system 13 to the Z-direction modulation piezo 12a of the XYZ stage 12. Then, the XYZ stage 12 ascends, the surface of the sample 11 placed on the XYZ stage 12 approaches the tip of the probe 15, and the cantilever 14 bends due to the repulsive force due to the atomic force. At this time, the laser beam 17 from the laser source 16 is reflected by the upper surface of the tip portion of the cantilever 14 and is input to the sensor 18. The sensor 18 AF outputs a detection signal according to the input laser beam 17, that is, according to the Z-direction displacement amount of the probe 15.
It is sent to the M feedback system 19. The AFM feedback system 19 sends a Z-direction drive control signal corresponding to the detection signal from the sensor 18 to the XYZ positioning system 13. X
When the Z-direction drive control signal from the AFM feedback system 19 coincides with a preset setting signal, the YZ positioning system 13 determines that the cantilever 14 is bent by a predetermined amount, and stops the XYZ stage 12 from rising. . Then, the surface of the sample 3 is located at a position slightly away from the tip of the probe 2. Then, the XYZ positioning system 13
At this time point, the Z-direction initial position signal having the same voltage as the drive signal (voltage) sent to the Z-direction modulation piezo 12a of the XYZ stage 12 is sent to the A / D conversion unit 20. The Z-direction initial position data (Z ₀ ) converted into a digital signal in 20 is stored in the storage unit 21.

[0011] Then, X-direction position signal Y ₁ scan line from the system controller 22 to the XYZ positioning system 13 (X
₁ Y ₁ , X ₂ Y _1, ...) Is sent out, and the XYZ stage 12 moves in the X direction together with the sample 11. In this case, the probe 15
Is lowered when it is in a state of facing the concave portion on the surface of the sample 11, and is raised when it is in a state of facing the convex portion, and the bending amount of the cantilever 14 is changed accordingly. This change is detected by the sensor 18, and the detection signal is sent to the AFM feedback system 19. AFM feedback system 19
Sends a Z-direction drive control signal corresponding to the detection signal from the sensor 18 to the XYZ positioning system 13. The XYZ positioning system 13 moves the XYZ stage 12 to the sample 1 based on the Z direction drive control signal from the AFM feedback system 19.
Increase or decrease with 1. As a result, the repulsive force due to the interatomic force is controlled to be maintained constant. In this case, the XYZ positioning system 13 sends to the A / D converter 20 a Z-direction drive control signal having the same voltage as the drive signal (voltage) sent to the Z-direction modulation piezo 12a of the XYZ stage 12 at each time point. Then, the Z direction position data (Z ₁ , Z ₂₎ converted into a digital signal by the A / D conversion unit 20.
......) is stored in the storage unit 21.

Therefore, in the memory unit 21, the X direction position data for the Y ₁ scan line from the system control unit 22 and the corresponding Z direction position data (X ₁ Y ₁ Z ₁ ,
X ₂ Y ₁ Z ₂ ......) will be stored. For convenience of explanation, again, X-direction position signal (X ₁ Y ₁ of Y ₁ scan line from the system controller 22 to the XYZ positioning system 13,
X ₂ Y ₁ ......) is sent out and the second position data (X ₁ Y ₁ Z ₁ , X ₂ Y ₁ Z ₂ ......) is stored in the memory unit 21 by the same operation as above. .

Next, the operation of the arithmetic unit 23 will be described. The computing unit 23 firstly reads from the memory unit 21 the Z-direction initial position data (Z ₀ ) and the first position data (X ₁ Y ₁ Z ₁ ,
X ₂ Y ₁ Z ₂ ......) is called and a predetermined calculation is performed. In this case, first the Z direction initial position data (Z ₀ ) and each Z
Differences (ΔZ ₁ , ΔZ ₂ ) from the direction position data (Z ₁ , Z ₂ ...)
......) is calculated, and then a line profile is created according to the calculation result. Then, the result of the first line profile creation is stored in the memory unit 21. Next, the calculation unit 23 receives the Z-direction initial position data from the memory unit 21.
(Z ₀ ) and the second position data (X ₁ Y ₁ Z ₁ , X ₂ Y ₁ Z ₂ ...
...) and call a predetermined operation. In this case, the difference (ΔZ ₁ , ΔZ ₂ ...) Between the Z direction initial position data (Z ₀ ) and each Z direction position data (Z ₁ , Z ₂ ...) Is _first calculated, and then this difference is calculated. Create a line profile according to the calculation results. The result of the second line profile creation is also stored in the memory unit 21.

Here, it is assumed that the geometrical shape (line profile) on the Y ₁ scan line of the surface of the sample 11 is as shown in FIG. 2 (A). Then, it is assumed that the first line profile is as shown in FIG. 2B and the second line profile is as shown in FIG. 2C due to the influence of physical vibration and sound. In this case, while the geometrical shape of the surface of the sample 11 corresponding to the Y ₁ scan line is always constant, the influence of physical vibration or sound at each measurement is random, and therefore, FIG. The first line profile shown in) and the second line profile shown in FIG. 2C have different noise generation sites due to the effects of physical vibration and sound.

Continuing the description of the operation of the arithmetic unit 23, the arithmetic unit 23 calls the first line profile creation result and the second line profile creation result from the memory unit 21 and performs a predetermined operation. The operation in this case is
First, the first line profile shown in FIG. 2B and FIG.
The line profile shown in FIG. 2D is created by adding the line profile shown in FIG. 2C to the second line profile, and the line profile shown in FIG.
The line profile shown in (E) is created. The line profile creation result shown in FIG.
Stored in 1.

In the thus obtained line profile shown in FIG. 2 (E), the first line profile shown in FIG. 2 (B) and the second line profile shown in FIG. 2 (C) are physically 2) The physical vibration and sound of the first line profile shown in FIG. 2 (B) and the physical vibration and sound of the second line profile shown in FIG. Each noise will be halved due to the effect of. In this case, the average value of the line profile obtained by the two measurements is calculated, but as the number of measurements on the Y ₁ scan line increases, the noise due to the influence of physical vibration and sound decreases, and FIG. It is possible to bring it closer to the true line profile shown in (A), and therefore, the reliability of the measurement data can be improved even under the influence of physical vibration or sound.

In the above description, the Y scan line is measured a plurality of times and an average line profile is obtained from the measurement results. However, scanning in the XY directions is performed and three-dimensional position data is stored in the memory section. It is needless to say that the storage unit 21 may be repeated a plurality of times, and then the arithmetic unit 23 may perform an arithmetic operation with an XY matrix to obtain an average three-dimensional image.

Further, this scanning probe measuring system does not need to be housed in one cabinet as a whole,
What is necessary is just to combine each independent functional part so as to form one system as a whole.

[0019]

As described above, according to the present invention, the average value is calculated based on a plurality of measurement data for the same scanning line, so that noise due to the influence of physical vibration or sound is reduced. Therefore, it is possible to improve the reliability of the measurement data even under the influence of physical vibration or sound.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a scanning probe measuring system according to an embodiment of the present invention.

2A to 2E are diagrams showing line profiles in respective states.

FIG. 3 is a diagram for explaining the operation principle of a conventional AFM.

[Explanation of symbols]

 11 sample 12 XYZ stage 13 XYZ positioning system 14 cantilever 15 probe 19 AFM feedback system 21 memory unit 22 system control unit 23 arithmetic unit

Claims (3)

[Claims] 1. A scanning probe measuring system for measuring a geometrical shape of a surface of a sample by a probe, storing a plurality of measurement data for the same scanning line obtained by scanning the same scanning line a plurality of times. A scanning probe measuring system comprising: a storage unit; and a calculation unit that calculates an average value thereof based on a plurality of measurement data for the same scanning line called from the storage unit. 2. A scanning probe measuring system for measuring the geometrical shape of the surface of a sample by a probe, a storage unit for storing a plurality of measurement data obtained by performing a plurality of XY direction scans, A scanning probe measuring system comprising: an arithmetic unit that calculates an average value based on the plurality of measurement data called from the storage unit. 3. A scanning probe measuring method, characterized in that the scanning probe measuring system according to claim 1 or 2 is used to measure the geometrical shape of the surface of a sample.