JPH09251026A - Scanning probe microscope - Google Patents

Abstract

(57) [Summary] (Modified) [Problem] Atomic force and frictional force can be separated and detected efficiently, and the difference in the shape, composition and structure of the material surface can be analyzed and evaluated. (EN) Provided is a device having a probe capable of detecting a precise position even in processing / recording. SOLUTION: A support base 7, levers 3 and 4 whose both ends are flexibly attached to the support base, a probe 2 attached to a surface of the lever opposite to the support base, and the probe are sandwiched therebetween. The lever has a pair of strain gauges a, b, c, d formed on the surface of the lever for detecting the deflection of the lever. Further, the strain gauges are provided on both front and back surfaces of the lever, and are individually bridged. A circuit is formed, and the magnitude of the frictional force is obtained from the output voltage of each bridge circuit. Further, a means for applying an oscillating voltage having a frequency in the range of 100 KHz to 100 MHz is provided to the probe of the scanning probe microscope so as to remove dust attached to the probe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe such as an atomic force microscope or a friction force microscope for evaluating the fine morphology and structure of a surface by detecting the atomic force or frictional force on the surface of an object. Regarding the microscope.

[0002]

2. Description of the Related Art A scanning probe microscope (SPM) scans the surface of a sample by bringing a sharpened probe close to the sample to scan a tunnel current flowing between the probe and the sample and the probe and the sample. By detecting the atomic force, magnetic force, or frictional force that acts between the two, it is possible to measure and analyze the characteristics such as the minute morphology and structure difference at the atomic level of the sample surface, magnetic characteristics, electronic state, etc. It is capable of measuring the surface, and has the highest resolution as a device, such as semiconductor materials, semiconductor elements, high-density recording materials, surfaces of organic monolayers, and biological / biochemical materials such as bacteria and genes. It is used in a wide range of technical fields even for observing natural objects. In addition, the possibility of ultra-high density recording method based on this scanning probe microscope and element formation technology by atom / molecule manipulation (atom manipulation) in ultra-high integration semiconductor memory elements are studied. atom·
Research on ultrafine processing devices for molecular processing or ultrafine recording devices for reading and recording electric charges and magnetic recording has been attempted. As described above, the technique related to the scanning probe microscope is considered to be an extremely promising technique as a technique for processing / inspecting / recording in the nano region including the semiconductor field in the future.

In such a scanning probe microscope, it is necessary that the position detection accuracy of the probe has high reliability regardless of the environment in which the microscope is placed, in any of processing, inspection and recording. The position detection method currently used is mainly a probe method in which a probe is attached to a cantilever. As shown in FIG. 9, a record needle-shaped fine probe is attached to the tip of a plate made of metal or the like, and a sample is attached to the sample. Scan the surface with a probe to detect the tunnel current flowing between the sample and the probe, or
By detecting the atomic force and frictional force acting between the sample and the probe by the optical detection method or strain gauge detection method, feedback is given to the piezo element to obtain a two-dimensional image of the structure and electronic state of the sample surface. ing.

In the measurement of atomic force and frictional force, optical detection methods such as an optical lever method and an optical interference method are used as a method capable of detecting the vertical movement of a probe with high sensitivity. However, these methods are methods that irradiate the laser beam to the cantilever to capture the displacement, so it is necessary to adjust the optical axis.When installing the probe inside a device such as a vacuum device, the axis alignment operation is required. Was difficult. Furthermore, when a probe is installed inside a film forming apparatus or dry etching apparatus, it is exposed to various active gases, and there is a problem that the mirror and detector are contaminated and corroded. It was In particular, in the case of a semiconductor process, most of the formation and processing of fine elements are performed in vacuum and in various active gases, so the detection method using light cannot be said to be appropriate. Further, there is a problem in that the optical axis is displaced due to the influence of vibration and the like, and the reliability is deteriorated for a long time.

On the other hand, the strain gauge method is a method in which a strain gauge is attached to a cantilever and the deflection of the cantilever is detected as a resistance change of the strain gauge, and there is no need to adjust the optical axis as in the photodetection method, and a vacuum device is used. It can be easily incorporated into the inside for measurement. Furthermore, it is possible to perform measurement even in an atmosphere such as an active gas by means such as protective coating of the surface of the strain gauge, and it has been adopted as a detection method that eliminates the drawbacks of the light detection method.

[0006]

A conventional strain gauge type cantilever has a structure as shown in FIG.
The sample surface is scanned by the cantilever, and the deflection of the cantilever due to the interaction between the sample surface and the probe is measured. Therefore, with the detection method using such a strain gauge, although the vertical displacement due to the unevenness of the sample surface can be detected, the torsion of the cantilever due to frictional force or the like cannot be detected efficiently. In other words, as a position detection means in the analysis / processing / recording at the atomic / molecular level, it is possible to distinguish between the displacement of the probe due to the frictional force generated by the difference in the composition and structure of the sample surface and the displacement due to the unevenness of the sample surface. It was not possible, and it was not sufficient in terms of positioning accuracy and reliability.

Further, when the surface of a substance is analyzed, processed, or recorded by using these scanning probe microscope or a device based on the scanning probe microscope, dust or the like adheres to the probe,
There is a problem that it is difficult to analyze, process and record the material surface. That is, the probe of the scanning probe microscope scans the sample surface while being normally brought into contact with the sample or being controlled so as to keep a distance from the sample surface at an extremely short distance on the order of nanometers. Therefore, even very small dust that has not been a problem in the past on the surface of the sample adheres to the probe due to electrostatic force or physical or chemical force, and affects the operation of the probe. This means that accurate position detection cannot be performed.

Conventionally, when dust adheres to the probe, the probe is conventionally replaced each time. However, replacing the probe each time is troublesome and costly, and the measurement conditions are high. There is a problem that is different.

Therefore, the present invention solves the drawbacks of the conventional position detection method using the strain gauge method, and in the measurement evaluation of the material surface by the scanning probe microscope, the atomic force and the friction force are separated and efficiently detected, We provide a device with a probe that can analyze and evaluate the difference in the shape, composition and structure of the material surface and can detect the precise position even at the processing and recording at the atomic and molecular level, and at the time of operation such as measurement and processing. Another object of the present invention is to provide a method for removing dust and the like adhering to a probe to enable smooth operation.

[0010]

A scanning probe microscope according to the present invention comprises a support base, a lever having both ends attached to the support base so as to bend, and a probe attached to a surface of the lever opposite to the support base. And a pair of strain gauges formed on the surface of the lever with the probe interposed therebetween to detect the deflection of the lever. Further, the strain gauges are characterized in that they are formed on both front and back surfaces of the lever to individually form bridge circuits, and the magnitude of the frictional force is obtained from the output voltage of each bridge circuit.
In other words, the bridge circuit is made with one strain gauge installed on the back of the lever on one side of the probe and on the front side, and also for the strain gauge of the lever on the other side. Is created and the sum and difference of the individual output voltages obtained from these bridge circuits are obtained, and the atomic force and the frictional force are separated and efficiently detected.

Further, according to the present invention, in a scanning probe microscope equipped with a probe having a probe for scanning a sample surface and detecting a change in characteristics of the sample surface, dust on the probe is removed, 100 KHz for the probe
It is a scanning probe microscope characterized by having a means for applying an oscillating voltage having a frequency in the range of -100 MHz.

In the probe used in the present invention, both ends of a belt-shaped lever having a probe in the central portion are fixed to a support base, and the central probe portion is the lowermost portion so that the probe and the sample surface face each other. However, the probe portion of the lever to which this probe is attached can move freely by the force received from the sample surface. That is, the lever is elastically deformable in the direction in which the probe portion at the bottom of the lever moves toward and away from the support base by the repulsive force or attractive force acting between the probe and the sample surface. The probe portion at the bottom of the lever is provided so that it can be elastically deformed in the left-right direction with respect to the support base by a force such as a frictional force acting between the needle and the sample surface. As a result, the lever bends not only in the vertical direction but also in the horizontal direction with respect to the sample, and the minute deformation of the lever due to this deflection is detected using the strain gauges installed on the left and right levers. That is, when the probe part moves up and down only in the vertical direction, the deformation of the left and right levers becomes symmetrical, but when a force such as a frictional force acts, the left and right levers are deformed in the horizontal direction. The levers show an asymmetrical deformation, with one lever extending while the other contracts. Therefore, it is possible to measure the force in the horizontal direction by detecting the resistance change of the strain gauge attached to the lever for this slight deformation of the lever. For example, the difference in the adsorption force depending on the site of the molecule adsorbed on the sample substrate, It is possible to measure differences in the molecular structure of the sample surface.

The curve is formed by giving a curvature to the lever so that the lever is easily bent in both horizontal and vertical directions. The curve is formed in a convex arc shape or a parabola shape in which a probe portion is projected downward, or a probe shape. The part may be formed in a shape such as a concave arc shape or a parabola shape with both sides protruding downward. Therefore, in the case of a probe having a "V" shape without bending the lever, it suffices if the lever itself is made of a material that can be deformed. , The degree of freedom of the probe part is reduced, and it is less likely to cause deflection.Therefore, there is no problem in measuring the repulsive force among atomic forces, but among the atomic forces, horizontal force such as attractive force and frictional force Detectability tends to decrease. Therefore, in order to easily bend the probe portion, it is preferable to bend the lever so as to give it a curvature.

The strain gauge used in the present invention is only required to be capable of detecting a slight deflection of the lever, that is, a slight deformation. As such a strain gauge, for example, a resistance wire made of a semiconductor material such as silicon is used. The deflection of the lever can be detected by measuring the change in the resistance value of the strain gauge.

Further, according to the present invention, by mounting these strain gauges on both front and back surfaces of a lever which is formed in a curved shape, detection sensitivity is improved by simultaneously detecting extension and contraction of the lever, and further, it is installed on both front and back surfaces of the lever. With the strain gauge, a bridge circuit is formed for each of the left and right levers.

Therefore, when the left and right levers are bent in the same way due to the vertical displacement, the output voltages from the left and right bridge circuits show the same value, but the horizontal lever receives the left or right lever. When displaced in the direction, the deflection of the left and right levers becomes different, and the output voltages from the left and right bridge circuits also show different values. Therefore, the difference between the output voltages from the left and right bridge circuits indicates the horizontal displacement amount, and by measuring this value, the horizontal force such as the frictional force can be evaluated and analyzed.

From such a point of view, it is preferable that the left and right levers that sandwich the probe be formed as symmetrically as possible, and the strain gauges be arranged at symmetrical positions. Further, the probe of the present invention crosses the above belt-shaped levers and measures the deflection of each lever caused by the probe attached to the crossed portion, so that not only the force acting in the left-right direction but also the longitudinal direction is acted. It is also possible to obtain the horizontal force to perform.

Various materials can be used for the probe depending on the object to be measured and the purpose. For example, by using a probe coated with a magnetic substance on the probe of the present invention,
It becomes possible to measure the deflection of the lever due to the magnetic field on the sample surface, and it occurs depending on the permittivity of the conductive sample surface and the distribution of charge or polarization by application as a magnetic force microscope or by using a conductive probe. It can be used as another type of scanning probe microscope, such as a Maxwell stress microscope that detects Maxwell stress and the like.

Further, in the scanning probe microscope using the probe of the present application, the deflection of the lever is directly measured by a strain gauge, and the operation method is any of contact mode, non-contact mode and tapping mode. Can also be applied.

The probe as described above is not limited to the scanning probe microscope, but also an ultrafine processing apparatus for performing atomic / molecular processing based on these scanning probe microscopes, an ultrafine processing apparatus for performing charge / magnetic recording and reading thereof. The same can be used in the recording device as a means for detecting the position, and can be applied to these devices.

On the other hand, the present invention also provides a method of removing dust from the probe in order to prevent the trouble that the dust adheres to the probe and makes the measurement difficult when measuring using a scanning probe microscope. To do.

Generally, the dust attached to the probe is of a very small size of 1 μm or less, and has many insulators, and is attached to the sample by being charged, and from the sample to the probe. Therefore, when a voltage is applied to the probe, a minute dust is scattered from the probe due to an electric force, but there is a high possibility that the dust will adhere to the sample or the probe again simply by applying the voltage. That is, for example, when a negative potential is applied to the probe, the negatively charged insulator is detached from the probe, but since the sample is at a positive potential, the detached dust will adhere to the sample. .

Such an adverse effect can be prevented by applying an oscillating voltage to the probe and the sample. When an oscillating voltage is applied, the dust attached to the probe vibrates partly by the alternating electric field, and when the vibration diverges, the dust flies out of the probe. The condition of divergence depends on the mass of the vibrating dust and the magnitude of the applied electric force. Therefore, the dust can be removed from the probe by changing the frequency of the alternating electric field according to the mass number and charge of the dust.

[0024] Usually, a dust of a size that is a problem has a mass number of nanogram or less and an electric charge of 10 ^-12 coulomb or less. When such dust vibrates, the
If it is in the electric field of V,

[Equation 1] Therefore, the resonance frequency of dust can be calculated from the above equation.

The smallest dust is 10 ^-18 g in size,
If the charge is 10 ^-13 coulombs, the resonance frequency is about 10
0 MHz. If the largest dust is 10 ⁻¹² g and the electric charge is 10 ⁻¹³ coulomb, the resonance frequency is 100 KHz. Therefore, 100 KHz to 10
If an oscillating voltage with a frequency of 0 MHz is applied, problematic dust can be removed.

The oscillating voltage can be applied to the probe by applying the oscillating voltage between the sample and the probe using a high frequency generating circuit such as an RF oscillator.

The timing of voltage application may be at the end of scanning in the X-axis direction or during scanning of the probe. During scanning, turn off the feedback circuit in the Z-axis direction for a short time, hold the position of the probe to temporarily stop the measurement of tunnel current and atomic force, and quickly in the meantime A high frequency voltage is applied between and. The application time may be on the order of microseconds, and voltage can be applied to remove dust without affecting the measurement system.

The frequency used is 100 KH as described above.
Even if the entire range is scanned from z to 100 MHz, of the frequencies in this range, for example, 100 KHz, 50 MHz, 1
The frequency may have a width so that a specific frequency such as 00 MHz is sequentially applied. Also, the same result can be obtained by using a low frequency matched to the largest dust. This is because small dust particles have a higher speed than large dust particles, and when large dust particles are scattered due to a low frequency, small dust particles are scattered with the large dust particles out of the probe-sample system. .

The method of removing dust from the probe by the above-mentioned method includes all scanning probe microscopes having a probe and an ultrafine processing apparatus for performing atomic / molecular processing based on these and charge or magnetic recording. It can also be applied to an ultra-fine recording device for reading the data, and it is possible to remove dust adhering to the probe that hinders the operation.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Next, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1A shows the structure of the entire probe. The levers 3 and 4 are made of a highly rigid material such as spring steel and processed into the shape as shown in the figure. That is, the base 5 for fixing the probe 2 is adhered to the tip of the lever, and the probe 2 is attached to the base 5 by means such as adhering or sandwiching.
The strain gauges a to d are 0.8 mm × 1 mm, and the resistance wire strain gauge of a silicon semiconductor gauge having a thickness of 10 μm is used for levers (thickness 0.1 mm, width 1 mm, length 5 mm) 3 and 4 made of Invar alloy. Stick it in place by alloying. Further, clasps 6 for fixing to the support base 7 are attached to both ends of the lever, and the clasps are provided with screw holes so that they can be fixed to the support base 7. 1B shows a state in which the lever is curved by narrowing the distance between both ends of the lever, and the lever is fixed to the support base 7 in this state. The state of the probe thus attached is shown in D of FIG. FIG.
C of the figure shows a state in which the entire probe is viewed obliquely.

FIG. 2 shows the configuration of the entire scanning probe microscope including the control system. Reference numeral 10 indicates a probe for X, Y,
Piezo elements driven in the Z-axis direction, reference numeral 1
Reference numerals 13 and 12 designate a voltage measuring circuit for detecting the output voltage of the bridge circuits 11 and 12, respectively. Reference numeral 14 is a servo circuit for receiving the output voltage of the voltage measuring circuit and controlling the movement of the piezo element in the Z-axis direction. Driving of the probe in the X and Y axis directions, servo in the Z axis direction and comparison of voltage and conversion into displacement amount are controlled by the control device 15, and a two-dimensional uneven image and a frictional force image of the sample surface are displayed. Display device 1
6 is displayed.

Since the resistance value of the semiconductor gauge and the resistance value of the bridge circuit are slightly different,
To measure the magnitude of displacement, calibrate with a standard sample with known irregularities. In addition, the output voltage in the state in which the probe load is not applied, that is, in the state in which the probe is not bent, is checked before measurement, and the servo voltage is controlled by the computer by setting this to 0 point.

Next, the deflection of each lever and the detection of the deflection when scanning the sample surface using the probe 1 attached as shown in FIG. 1D will be described with reference to FIGS. 3 and 4.

In FIG. 3A, reference numeral 2 is a probe of a scanning probe microscope, reference numerals 3 and 4 are levers for supporting the probe made of the same material, and are bent symmetrically with the probe interposed therebetween. It has the following structure. The levers 3 and 4 have resistance wire strain gauges a on both front and back surfaces.
Install b, c and d. Reference numeral 7 is a support base that supports the probe 2 and the levers 3 and 4, and is configured to be driven in the X, Y, and Z axis directions by a piezo element.
Reference numeral 8 is an individual sample to be measured.

FIG. 4 shows bridge circuits 11 and 12 of a resistance line strain gauge composed of strain gauges. In the figure, resistors R1 to R4 are resistance values Ra, Rb and R of the resistance line strain gauges a, b, c and d.
c and Rd have almost the same resistance value, where R is R1 = R2 = R3 = R4 = Ra
= Rb = Rc = Rd = R. When the lever is not bent (A in FIG. 1), resistance wire strain gauges a, b, c
Since the resistance values Ra, Rb, Rc and Rd of d and d are the same value R, even if the voltage E is applied to the bridge circuit, V1 =
Since V2 = 0, no voltage is generated.

When the lever is bent as shown in FIG. 3A, the resistance line strain gauges a and c expand and b and d contract, but since the levers 2 and 3 have the same curvature, The resistance wire strain gauges a and c increase in resistance by the same amount, and the resistance wire strain gauges b and d decrease in resistance by the same amount. If the amount of change in this resistance value is ΔR,

[Equation 2] And V1 and V2 are

(Equation 3) Output voltage is generated. If no force acts on the probe, it is held in this state.

Next, when the probe moves up and down due to the unevenness of the surface of the sample, the curvature of the curvature of the lever changes according to the amount of vertical movement, and the resistance wire attached to the front and back of the lever. A change appears in the amount of strain gauge expansion and contraction.
That is, when the probe is pushed up by the repulsive force of the atomic force due to the convex portion of the sample surface as shown in FIG. 3B, the levers 2 and 3 are further bent and the curvature also increases. As a result, the resistance wire strain gauges a and c attached to the lever are further extended and the resistance value increases, and the resistance wire strain gauge b.
And c further shrink and the resistance value decreases. Since the amount of displacement of the lever is small, if this changed resistance value is Δr,
Ra = Rc = R + .DELTA.R + .DELTA.r and Rb = Rd = R-.DELTA.
R-Δr, and when the voltage E is applied to the bridge circuit,
Same output voltage for V1 and V2

(Equation 4) Occurs. Therefore, the difference in the output voltage from the equations (2) and (3) is

(Equation 5) Then, by measuring this, the amount of displacement can be obtained.

On the other hand, when the probe is pushed down by the attraction force between atoms by the concave portion of the sample surface as shown in FIG. 3C, the levers 2 and 3 are extended and the curvature is reduced. Therefore, the resistance wire strain gauges a and c attached to the lever
3 further shrinks from the state of A in FIG. 3 to reduce the resistance value, and the resistance wire strain gauges b and d further extend to the state of FIG. 3A to increase the resistance value. Since the displacement of the lever is small, if this changed resistance value is Δr ', Ra = Rc = R +
.DELTA.R-.DELTA.r 'and Rb = Rd = R-.DELTA.R + .DELTA.r', and when voltage E is applied to the bridge circuit, V1 and V1
Same output voltage for 2

(Equation 6) Occurs. Therefore, the voltage difference between the equation (2) and the equation (4) is

(Equation 7) Then, by measuring this, the amount of reverse displacement can be obtained.

Next, considering the case where the probe receives a frictional force due to a change in the composition of the sample and a substance attached to the sample, it is as follows. At this time, the lever is deformed as shown in D of FIG. 3, one of the levers is bent and the other lever is deformed so as to be extended. That is, since the displacement amount is small in this case as well, the amount of change in resistance of the resistance line strain gauges a and b attached to the bent lever is Δr1, and the resistance line strain gauges c and d of the other stretched lever are If the amount of change in resistance is Δr2, the resistance of the resistance wire strain gauge is
Ra = R + ΔR + Δr1, Rb = R-ΔR-Δr1, R
c = R + .DELTA.R-.DELTA.r2 and Rd = R-.DELTA.R + .DELTA.r2, and when the voltage E is applied to the bridge circuit, the following output voltages are generated at V1 and V2.

[0041]

(Equation 8)

[Equation 9] Therefore, V1 and V2 show different voltages and this difference

(Equation 10) By measuring, the magnitude of the frictional force can be obtained.

Therefore, when the frictional force and the atomic force act simultaneously, the atomic force is V1 + V2 and the frictional force is V1 -V.
It can be detected by 2 and the forces of both can be separated and obtained separately.

When the lever is bent to give a curvature, it is not bent to be convex as shown in A of FIG. 3 but is curved to be convex as shown in FIG. You may let me. In this case, the relationship of expansion and contraction of each resistance line strain gauge attached to the lever is the opposite relationship to the above description, and the signs are opposite, but the atomic force and the frictional force can be obtained respectively. .

As described above, according to the present invention, the sensitivity is increased by 2 to 4 times by attaching the four strain gauges to the front and back surfaces of the levers on the left and right sides of the probe, and the friction force and the atomic force are increased. You will be able to separate and obtain.

FIG. 6 shows the result of measuring the surface of synthetic rubber by this apparatus. In the figure, A is an image (topography) showing the state of surface irregularities, and B is an image shown by frictional force. The image of the frictional force clearly shows that the synthetic rubber is composed of different components, and it can be seen that the frictional force information and the unevenness information can be obtained independently without being influenced by each other.

Next, regarding the method of removing dust adhering to the probe that is a problem during measurement, an atomic force microscope using a photodetection method, which is one of scanning probe microscopes, will be taken as an example.
This will be described with reference to FIG. In this example, unlike the case of FIG. 2, a method is adopted in which the sample mounting table on which the sample is mounted is moved by a piezo element to perform scanning.

FIG. 7 shows the structure of the main part of a scanning probe microscope for carrying out the method for removing dust from a probe according to the present invention. The apparatus body includes a sample mounting table 17 on which a sample 8 is mounted, a stepping motor for moving the sample mounting table 17 in the X, Y, and Z axis directions, a piezo element 10 for fine adjustment, and a probe 1 including a probe 2. An optical interferometer 18 for detecting the position of the probe and a circuit for applying a high frequency voltage between the probe 2 and the sample 8, for example, an RF oscillator 19 are provided, and scanning of the probe and position detection by the laser interferometer are provided. And its feedback is performed by the controller 15. Further, the application of the high-frequency voltage applied between the probe and the sample is controlled by the controller 15 so that it can be applied at an arbitrary position and time separately from the control of the measurement system.

The high frequency voltage is set by the RF oscillator in four stages from 1 MHz to 100 MHz in 40 μs, that is, at 1, 20, 50 and 100 MHz.
It was generated intermittently every 0 μsec and applied between the probe and the sample. A high resistance of 1 M ohm was installed in series in the circuit to prevent current from flowing between the probe and the sample. The high frequency voltage was applied by inserting it 1 to 5 times during one scan in the X-axis direction.

FIG. 8 is a comparison of the topographic images when the high frequency voltage is applied in this way and when it is not applied. In the figure, A is the case where no voltage is applied and B is the case where it is applied. Is shown. When no high frequency voltage is applied, noise is seen due to the adhesion of dust, but an image without noise is obtained by applying voltage.

As described above, the circuit for applying the high frequency voltage is provided between the probe and the sample, and the dust applied to the probe is removed by applying the voltage to the probe in the above-mentioned example. Not only the atomic force microscope using the illustrated optical interferometer, but also other atomic force microscopes that use the position detection method for the strain gauge described in the present specification, as well as scanning probes that use all probes such as scanning tunneling microscopes. Applicable to microscope.

[0051]

According to the scanning probe microscope of the present invention,
A scanning probe microscope can be installed in a device that has been difficult in the past, such as in a vacuum or in various gases, to easily separate and measure the unevenness and frictional force of the sample surface.Semiconductor substrates, organic thin films, biological samples It is extremely effective for evaluation analysis, atomic / molecular operations in semiconductor microfabrication, and read / write technology in ultra-high density recording technology. Specifically, the following effects are obtained.

(1) Instead of the conventional cantilever method, the curved and bent levers are used at both ends, and the deflection of each lever is measured. Differences in composition and structure due to differences in force can be easily detected.

(2) Since the laser is not used for position detection and the strain gauge is used, the measurement is simplified without the need for preliminary operation such as adjustment of the optical axis at the time of measurement.

(3) It is also possible to install and measure in a vacuum such as a film forming apparatus or an etching apparatus and in an atmosphere such as an active gas.

Further, according to the present invention for removing dust from a probe, it has been difficult in the prior art in a scanning tunneling microscope or an atomic force microscope using a probe, an ultra high density recording device or an ultrafine processing device using a probe. It is possible to prevent the obstacle due to the adhesion of dust to the probe during the existing scanning, and by removing the dust during measurement, an image with less noise and image distortion can be obtained. Further, unlike the conventional case, it is not necessary to frequently replace the probe, and the labor and cost required for replacement can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a probe used in the invention of the present application, in which A is a structure of the entire probe, B is a state in which a gap between both ends of the lever is narrowed, and the lever is curved, C shows a state in which the entire probe is viewed obliquely, and D shows a state in which the probe is attached to the support base.

FIG. 2 is a diagram showing a configuration of an entire scanning probe microscope including a control system.

3A and 3B are diagrams illustrating the deflection of each lever and the detection of the deflection when scanning the sample surface using the probe 1, where A is a state in which the lever is bent to form a probe, and B is a sample. The convex portion of the surface receives the repulsive force of the atomic force to push the probe up, C is the concave portion of the sample surface receiving the attractive force between the atoms and the probe is pushed down, and D is the probe. It shows a state in which the sample is horizontally bent due to a change in the composition of the sample and a frictional force caused by a substance attached to the sample.

FIG. 4 is a diagram showing a bridge circuit configured by strain gauges for detecting the deflection of each lever.

FIG. 5 is a diagram showing another example of a lever that is curved.

FIG. 6 is a diagram showing the results of measuring the surface of synthetic rubber, where A is an image (topograph) showing the state of surface irregularities, and B is an image shown by frictional force.

FIG. 7 is a diagram showing a configuration of a scanning probe microscope for performing a method of removing dust attached to a probe.

FIG. 8 is a topographic image showing that dust is removed by applying a high frequency voltage, where A is a case where the high frequency voltage is not applied and B is a case where the high frequency voltage is applied. .

FIG. 9 is a view showing a probe having a probe attached to a cantilever, which is currently used.

FIG. 10 is a diagram showing a structure of a conventional strain gauge type probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 probe 2 probe 3, 4 lever 5 pedestal 6 clasp 7 support base 8 sample 10 piezo element 11 bridge circuit with strain gauges a and b 12 bridge circuit with strain gauges c and d 13 voltage measurement circuit 14 servo circuit 15 controller 16 display device 17 sample mounting table 18 optical interferometer 19 RF oscillator a, b, c, d strain gauge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Suzuki, Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa, Ltd., within the Toshiba Research and Development Center (72) Inventor, Mitsuhiro Tomita Komukai-Toshiba, Kawasaki-shi, Kanagawa 1 Incorporated Toshiba Research and Development Center (72) Inventor Chie Takakuwa Komukai Toshiba Town, Kouki-ku, Kawasaki City, Kanagawa Prefecture 1 Incorporated Toshiba Research and Development Center (72) Inventor Mamoru Takahashi Komukai, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Toshiba Town 1 Stock Company Toshiba Research and Development Center

Claims (3)

[Claims] 1. A support base, a lever whose both ends are flexibly attached to the support base, a probe attached to a surface of the lever opposite to the support base, and a surface of the lever with the probe interposed therebetween. And a pair of strain gauges for detecting the deflection of the lever, the scanning probe microscope. 2. The strain gauge is formed on each of the front and back surfaces of the lever to individually form a bridge circuit, and the magnitude of the frictional force is determined from the output voltage of each bridge circuit. The scanning probe microscope described. 3. A scanning probe microscope comprising a probe having a probe for scanning the surface of the sample and detecting a change in the characteristics of the sample surface, wherein the probe is 100 KHz so as to remove dust adhering to the probe. ~ 100MHz
A scanning probe microscope having means for applying an oscillating voltage having a frequency within the range.