JP3942915B2 - Method for discovering sample on substrate using scanning probe microscope, method for moving sample on substrate using scanning probe microscope, and scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to run査型probe microscope.
[0002]
[Prior art]
The scanning probe microscope of the prior art is mainly intended for image observation of samples, and there are disadvantages in moving or arranging a plurality of observed samples to arbitrary locations. For example, when samples such as carbon nanotubes, DNA, and fine particles are dispersed on the substrate, it takes a lot of time to quickly find these particles, move them to predetermined positions, and arrange them.
[0003]
It took difficult to nonlinearity of the piezoelectric element used in scanners and hysteresis and thermal drift or the like in alignment to fine sintered sample position (contact). In order to improve the nonlinearity and hysteresis of these piezo elements, S. Desogus, S. Lany, R. Nerino, GBPicotto, etc. incorporate a linear element such as a capacitance sensor in the piezo scanner and adjust it to the reading amount of the element. Thus, a method of controlling the applied voltage of the piezo scanner in a closed loop was adopted (J. Vac . Sci . Technol . B12 (3), 1665-1668, 1994) . In this method, the apparatus becomes complicated, and since the three-axis sensor is attached to the piezo scanner, the weight of the sensor increases, and the responsiveness of the piezo scanner deteriorates. In addition, since a moving fine sample cannot be observed, some alternative means is necessary.
[0004]
M.Finch, V.Chi, RMFalvo, M. Washburn, R. Superfine, etc., from the University of North Carolina have a paper (ACMSIGGRAPH, NewYork, 1995.pp.13-18.) That controls atomic force microscopy (AFM). It describes a manipulator. In addition, 3rdTecn in the United States takes an image measured by AFM, reproduces the image by computer graphics, displays a virtual probe on the image, and when this probe contacts the sample of the computer graphic image, A device has been developed that generates a pseudo reaction force signal on the lever to be operated and notifies the operator . These methods are actually AFM probe does not reflect the interactions that are in contact with the minute sample, remained improved operability without increasing the certainty of the specimen movement.
[0005]
[Problems to be solved by the invention]
When a fine sample is moved to a predetermined position using a scanning probe microscope, it is first necessary to find the moving sample, confirm the movement destination position, touch the sample, move the sample, and the like. In this series of operations , the moving sample is widely dispersed on the substrate, and it takes time for discovery. For example, when searching for a fine particle having a diameter of about 0.05 μm dispersed on a substrate from a 100 μm area, 5000 or more scanning lines are required for both XY. In this case, when the measurement contour is set to 10 μm, it is necessary to measure 100 images, and it takes a lot of time for measurement for finding the sample.
[0006]
Piezo scanners commonly used in scanning probe microscopes are non-linear elements, and the position of the sample fluctuates with time due to hysteresis and creep, or the sample position fluctuates due to thermal effects. It is difficult to contact the sample once.
[0007]
Because it can not observe the sample in the moving, or out the sample that is actually moving, when encountering an obstacle, or deviated if so, a plurality of signal sources to inform the operator or avoiding an obstacle Is required.
[0008]
The present invention provides a novel scanning probe microscope.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The scanning probe microscope according to the embodiment of the present invention finds a target sample by performing raster scanning at a predetermined high magnification area when a predetermined position or a predetermined condition is reached while performing raster scanning at a low magnification. Alternatively, it has a mechanism for stopping the probe when it comes into contact with the sample (raster scanning / specimen discovery / probe stop mechanism).
[0010]
In other scanning probe microscopes, the signal indicating the height immediately below the probe (Z signal) during movement and the amount of deviation from the initial setting of the Z-direction force acting on the probe and the substrate or sample immediately below the probe Proportional signals (error signals) and horizontal force signals (friction signals) acting between the sample and the substrate directly under the probe or the sample are detected, and these signals are displayed as time-series signals and instantaneous positioning signals. Or a mechanism for notifying the operator of an error signal as a Z direction reaction force and a friction signal as an XY direction reaction force via an operation lever .
[0011]
<Device configuration>
To explain by using a less schematic of specimen movement and processing the scanning probe microscope according to the present invention Figure (Figure 1).
[0012]
As shown in FIG. 1 , an XYZ scanner [2] is fixed to a Z coarse motion system mechanism [1], and a cantilever part [4] is attached via a piezo diaphragm [3]. The cantilever part [4] faces the substrate [5] fixed to the sample stage [6]. The back surface of the cantilever [4] is irradiated with a laser beam [7], and the reflected light is incident on the quadrant position detector [8]. The signals from the upper and lower sensors of the quadrant position detector [8] are amplified by the preamplifier [10] as a signal in the height direction, and the difference signal from the Z-direction force setting (Δ1 : force Set) (round) 2 error signal) is input to the Z servo system [12]. The output signal (full 1Z direction height signal) is amplified by the high-voltage amplifier [13], the Z-axis of the XYZ scanner [2] expands and contracts, and the distance between the probe and the sample becomes constant so that the deflection of the cantilever becomes constant. It is controlled. On the other hand, the signals of the quadrant position detector [8] left and right sensors are amplified by the preamplifier [9] to become a friction signal.
[0013]
These Z height signal (full 1), error signal (full 2), and friction signal (full 3) are converted into digital signals by analog / digital converters (A / D converters) [20, 21, 22] , respectively. Each instantaneous value (FIG. 2A) and this value are displayed on the display [42] as time-series data (FIG. 2B) displayed in time series from the start of the movement of the sample.
[0014]
The microscope, an error signal as the XY direction reaction force friction signal in the Z-direction reaction force, after digital-to-analog converter [43], a mechanism for notifying by the reaction force to the operator operating the operating lever [44].
[0015]
Z height signal (Maru 1), the error signal (Maru 2), the friction signal (Maru 3) values respectively comparator [16, 17, 18] of the set value (△ 1 ': height Set, △ 2: When the error Set, Δ3 : friction Set) is exceeded, a signal is transmitted to the XY scan controller [14] , and the XY scan controller [14] stops increasing the triangular wave for XY scan, and the Z height signal The movement of the probe is stopped until the (round 1) , error signal (round 2) , and friction signal (round 3) are below the set value.
[0016]
The XY scanning controller [14] inputs a raster scanning triangular wave to the digital-analog converter in the XY controller [14] , applies the output to the high-voltage amplifier [15] , and drives the XY piezo scanner [2] . A shape image is calculated from the Z height signal and the XY raster signal, an error signal image is calculated from the error signal and the XY raster signal, and a friction image is calculated from the friction signal and the XY raster signal. ] to display.
[0017]
Further , as shown in the figure, when the Z direction height signal (round 1), error signal (round 2) and / or friction signal (round 3) exceeds a threshold value, a scanning stop signal (round 4) is generated. The XY controller [14] configured and receiving this signal holds the voltage value of XY and fixes the probe at a predetermined position. That is, the scanning stop signal, the Z-height signal (Maru 1), the error signal (Maru 2), the friction signal (Maru 3) stops scanning on the substrate surface by the probe in case of greater than or equal to the specified value It is a signal to make it .
[0018]
<Raster scan / Sample detection / Stop probe>
3 (A) is, the screen capture view of raster scan / sample discovery / probe stop operation (schematic diagram showing a state of scanning lines), FIG. 3 (B), the output voltage of the XY scanning controller [14] It is an example of time series display. The raster scanning / specimen discovery / probe stop operation will be described below.
This series of operations in order to discover the fine sample being widely distributed on the base plate, shown in FIG. 3 (A), scans the low magnification (wide area), needle object that is supposed to sample when previously detected, by scanning the periphery thereof at a high magnification (narrow region), it is an operation that facilitates discovery of fine sample.
As shown in FIG. 3 ( A ) , the outline of a wide area is L, and the number of scanning lines is N (lines) . A narrow area where high magnification is measured is l, and the number of scans is n (lines) . The offset O from the initial scan line position of the start point of the run査and O = pnxL / N.
[0019]
Also not a, a low magnification (wide area) scanned with offset zero, the instantaneous value of Z height just below the tips may become higher than the set value (signal Maru 1), the instantaneous value of the error signal immediately below the probe XY scanning controller [14] triggered by the fact that it becomes larger than the set value (signal round 2) or the instantaneous value of the friction signal immediately below the probe becomes larger than the set value (signal round 3) There generates a signal full 5, the indicator which has received the signal full 5 [42], the position of the probe on the substrate when the trigger signal full 5 has occurred (scanning position), corresponding to this position The display is set to be the center of the display [42] .
The XY scan controller [14] generates the trigger signal (5) and measures a high-magnification image (high-magnification measurement) of the number n of scans in a narrow area l. After that (after the measurement for the region 1 is completed), the trigger is returned to the trigger generation point on the substrate , and the interrupted low-magnification scanning is continued (scanning by the setting performed before the trigger signal (maru 5) is generated (low-magnification scanning). ) Is resumed from the point of interruption.)
[0020]
XY scan controller [14], if the sample is not found even after scanning N lines ( even if the substrate is scanned according to the above setting) , the offset amount is set to O = (1/2) (L / N) based on the bisection method to) low magnification scan the N lines Nau again. Still successively O = (1/4) (L / N) of the offset amount if it is not found, O = (3/4) (L / N) to be the low magnification scanning again ... performed N present, fine sample Search for (sample) . FIG. 3 ( B ) shows a triangular waveform for low magnification / high magnification XY scanning.
With this scanning method, it was widely distributed on a substrate (substrate surface) fine specimen can be found in a short time.
[0021]
Next, as shown in FIG. 3 (A), in a case / substrate surface presence is detected of a sample (target product) in the case of a sample that is an object is found (the substrate surface by the low magnification measured image (When the approximate position of the sample is found), a method for bringing the probe into contact with the sample accurately and stopping the probe at that position will be described.
In the above method, assuming that the trigger generation point is reached by performing 2-3 raster scanning with the low-magnification contour L , then, the high-magnification contour l shown in FIG. There is a high magnification scanning a detection range. Also in this scanning, the raster scanning is stopped with the point where the height signal, error signal, or friction signal exceeds the set value as a new sample contact position.
Adopted to the configuration for detecting the sample on the substrate as described above (Method This movement), and a raster scanning can linearity correction to approach the sample, for performing high magnification measurements were or exactly exploration A needle can contact the sample.
[0022]
<Each signal monitor during sample movement>
Next, a method of moving the sample on the substrate. Movement of the sample, usually by Turkey Ntakutomo de controls such that a force between the probe and the sample becomes constant, is moved by pressing the sample to a predetermined location. First, as described above, Ru determine the destination of the sample. For example, to identify a location on the substrate (position), and the like or decide the direction of movement, Ru decided moving route. The display [42] may be displayed on the screen .
[0023]
Scanning probe microscope according to the present embodiment, a high magnification screen, No clogging the Karaso shape of the sample specified by the information obtained by scanning in the Ekuruwa l of high magnification as shown in FIG. 3 (A) The position of the center of gravity is calculated, the pressing position (FIG. 5 ( A ) ) to the sample is determined based on the direction in which the sample is moved and the position of the center of gravity , the probe is moved to that position , the sample is pressed, and the sample is placed on the substrate. Move to the desired position above . The pressing position may be indicated on the image display [42] .
[0024]
<Specifying and displaying the probe position>
Current position on the substrate surface of the probe may the pressure amplifier as described above [15] is indexed than the voltage applied to the XY piezo scanner is displayed on the screen 1.
[0025]
<Treatment method when sample and obstacle collide>
The board (substrate surface) where smooth, the moving speed of the probe is constant. When the friction signal as shown in FIG. 5 (B) increases for initial static friction, quickly become constant. The error signal and the Z height signal are also constant. However, when the sample hits the obstacle such as a step, increases the frictional signal and the error signal as shown in FIG. 2 (B), the height signal Z increases late. In this case, the probe is damaged or so as not to damage the sample, it stops moving until the signal returns below the error signal value. A reaction force proportional to the increased friction signal and error signal is generated on the operation lever to allow the operator to experience it or display it on the screen .
[0026]
<How to avoid obstacles>
Next, a method of avoiding when the sample is blocked by an obstacle such as a protrusion ( a method for dealing with the case where the sample cannot be moved to the target position due to the presence of the obstacle on the substrate surface) will be described.
In the example shown in FIG. 2 (B), if the specimen is hit an obstacle such as a step (time t), the friction signal and error signal before and after increases its height signal Z is increased with a delay . Therefore, if the above three signals continue to increase , it can be determined that the sample has contacted the obstacle ( highly likely ) . In such a case, once Ru stop the movement of the probe.
[0027]
After stopping the relative movement of the probe relative to the substrate surface, as shown as "vector F1, F2" in FIG. 6, the pressing from the direction of the range of +/- 45 degrees in the current mobile A to the sample To do. In other words, observing the change of the three signals by changing the pressing direction. Then, the three signals start moving again in a direction to return to a constant value before the obstacle contact. After successful start moving, it is moving in the direction of the re-time basis to correct the direction.
[0028]
<Treatment method when the sample comes off the probe>
Next, what to do when the sample is removed from the probe for some reason is described.
When positive always moving showing friction signal a constant value. However , if the sample is removed from the probe for some reason, the area that moves in contact with the substrate decreases, and the frictional force suddenly decreases as shown at time t2 in FIG. In this case , the relative movement of the probe with respect to the substrate surface is stopped, high magnification measurement is performed at that point, the position and shape of the sample are reconfirmed, the pressing position on the sample is again obtained, and the movement is resumed.
[0029]
The above embodiment is an embodiment according to the present invention, and it goes without saying that the present invention is interpreted based on the idea and spirit disclosed in the present specification and drawings. The technical ideas described below are naturally disclosed in the present specification and drawings.
[0030]
Technical thought (1)
Scanning the vicinity of the sample surface with a fine cantilever with a probe (cantilever), obtaining the shape and physical property information of the sample surface from the deflection signal of the cantilever, and then using a scanning probe microscope that moves the sample, A mechanism that detects the amount of error (error signal) from the initial setting of the force acting between the needles and displays a signal proportional to the amount of deviation on the display, and the operation lever is perpendicular to the sample surface (Z direction) A scanning probe microscope characterized by having a mechanism for transmitting force.
[0031]
Technical thought (2)
The scanning probe microscope according to the technical idea (1), which has a mechanism for automatically adjusting the moving speed of the sample so that the deviation amount falls within a certain setting range.
[0032]
Technical thought (3)
Scan the vicinity of the sample surface with a cantilever with a fine probe (cantilever), obtain the shape and physical property information of the sample surface from the deflection signal of the cantilever, and then move the sample in a scanning probe microscope that moves the sample A mechanism that detects the friction force acting between the sample and the probe and displays a signal (friction signal) proportional to the friction force on the display, and a reaction force parallel to the sample surface (XY direction) on the control lever A scanning probe microscope characterized by having a transmission mechanism as
[0033]
Technical thought (4)
The scanning probe microscope according to the technical idea (3), further comprising a mechanism that automatically adjusts the moving speed of the sample so that the friction amount falls within a certain setting range.
[0034]
Technical thought (5)
Scanning probe microscope that scans the vicinity of the sample surface with a fine cantilever with a probe (cantilever), obtains the shape and physical property information of the sample surface from the deflection signal of the cantilever, and then moves the sample and processes the sample surface In order to find a fine sample widely dispersed on the substrate, a wide range image is captured while performing raster scanning at a low magnification, and the height signal just below the probe, the error signal, and the friction signal are set in advance during scanning. A scanning probe microscope that generates a trigger signal when a value is exceeded, collects a high-magnification image at a point where the trigger signal is received, returns to the trigger point again, and performs raster scanning at a low magnification.
[0035]
Technical thought (6)
After the low-magnification raster scan, an initial offset position based on the bisection method is added to the scan start position for the purpose of interpolating between the rasters, 1/2, 1/4 and 3/4,. The scanning probe microscope according to the technical idea (5), wherein a fine sample buried between rasters is discovered while performing magnification raster scanning.
[0036]
Technical thought (7)
Scanning probe microscope that scans the vicinity of the sample surface with a fine cantilever with a probe (cantilever), obtains the shape and physical property information of the sample surface from the deflection signal of the cantilever, and then moves the sample and processes the sample surface After determining the moving position and moving direction of the sample based on the measured low magnification measurement screen, if an obstacle is encountered when moving the sample, the direction in which the sample is pushed by the probe is set to the height signal, error signal, A scanning probe microscope characterized in that the obstacle signal is moved to avoid the obstacle by changing the direction so that the friction signal approaches the state before the obstacle encounter.
[0037]
Technical thought (8)
Scanning probe microscope that scans the vicinity of the sample surface with a fine cantilever with a probe (cantilever), obtains the shape and physical property information of the sample surface from the deflection signal of the cantilever, and then moves the sample and processes the sample surface The scanning probe characterized in that, after determining the moving position and moving direction of the sample based on the measured low-magnification measurement screen, the movement of the moving sample from the probe is detected from the change in the friction signal. microscope.
[0038]
Some of the actions and effects exhibited by the above-described embodiment are shown in the following bulleted list.
1. It has become easier to find fine samples dispersed over a wide range of substrates.
2. The probe can be easily brought into contact with a fine sample dispersed widely on the substrate.
3. Since the height signal, the friction signal, and the error signal can be observed during the movement of the sample, the state of the moving sample can be easily estimated, and the reliability of the sample movement is improved.
4). The set value of the height signal, friction signal and error signal is determined during the movement of the sample, and a mechanism is provided to interrupt movement when the set value is exceeded. Cantilever breakage, sample and substrate damage were reduced.
[Brief description of the drawings]
FIG. 1 is a system schematic diagram showing one aspect of an embodiment according to the present invention.
2A is an example of display of instantaneous values of height signals, error signals, and friction signals, and FIG. 2B is a display example of time series values of Z height signals, error signals, and friction signals. (When hitting an obstacle at the right end)
FIG. 3A is a diagram of a scanning line by a raster scanning / sample finding / probe stop mechanism.
(B) It is a figure of the voltage-time by a raster scan / sample discovery / probe stop mechanism.
4A is an example of processing by one-stroke scanning, and FIG. 4B is an example of processing by raster scanning.
FIGS. 5A and 5B are display examples of time-series values of a Z pressure signal, an error signal, and a friction signal. FIG. (At the start of sample movement)
FIG. 6 is an example of avoidance when a sample hits an obstacle.
FIG. 7 is a display example of time series values of a Z height signal, an error signal, and a friction signal. (When the sample comes off)
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Z coarse movement mechanism 2 XYZ fine movement scanner 3 Piezo diaphragm 4 Cantilever part 5 Substrate 6 Sample stand 7 Laser beam 8 4 division position detector 9 Preamplifier 10 Preamplifier 11 Error amplifier 12 Z Servo system 13 High voltage amplifier 14 XY scan controller 15 High voltage Amplifier 16, 17, 18 Comparator 20, 21, 22 Analog-digital converter 30 Bus line 41 Computer 42 Display 43 Digital-analog converter 44 Operation lever

Claims (12)

A sample on a substrate using a scanning probe microscope that first scans at a low magnification and immediately ends the scan at a low magnification when an object assumed to be a sample is detected and scans the periphery at a high magnification. A method of discovering
It is determined that the object has been detected when a predetermined trigger signal is received, and immediately after the low-magnification scanning is finished and the probe of the scanning probe microscope is stopped, the high-magnification scanning is started. A method for discovering a sample on a substrate using a scanning probe microscope. The method of claim 1, comprising:
The instantaneous value in the height direction input from the probe of the scanning probe microscope, the instantaneous value of the error signal input from the probe, and the instantaneous value of the friction signal input from the probe are monitored. A method for detecting a sample on a substrate using a scanning probe microscope, wherein the trigger signal is generated when at least one of instantaneous values becomes larger than a set value. A method according to claim 1 or claim 2, wherein
After the high-magnification scan is completed, the low-magnification scan is resumed from the place where the low-magnification scan was performed immediately before the start of the high-magnification scan. Method. A sample on a substrate using a scanning probe microscope that first scans at a low magnification and immediately ends the scan at a low magnification when an object assumed to be a sample is detected and scans the periphery at a high magnification. A method of discovering
After the high-magnification scan is completed, the low-magnification scan is resumed from the place where the low-magnification scan was performed immediately before the start of the high-magnification scan. Method. A method according to any one of claims 1 to 4, comprising
For low-magnification scanning, the offset from the scan line position (initial scan line position) at the start of the first scan is set to zero, and if an object assumed to be a sample is not detected, the offset is changed. A method of finding a sample on a substrate using a scanning probe microscope, which performs scanning at the same magnification again.   Information on the position of the sample on the substrate identified by the method for finding a sample on the substrate using the scanning probe microscope according to any one of claims 1 to 5, and a target of the sample on the substrate A substrate using a scanning probe microscope that determines the position and pressing direction of the sample with the probe of the scanning probe microscope based on the information on the moving position, and moves the sample by pressing the probe with the probe based on the determination. A method of moving the sample above. The method of claim 6, comprising:
When it is determined that the probe has come off the sample, the vicinity of the probe position on the substrate at the time of the determination is scanned at a high magnification to detect the sample, information on the position of the detected sample and target movement of the sample on the substrate Based on the information on the position, the position and the pressing direction of the sample are again determined by the probe, and the sample on the substrate using the scanning probe microscope is moved based on the determination. How to make. A sample on a substrate using a scanning probe microscope that first scans at a low magnification and immediately ends the scan at a low magnification when an object assumed to be a sample is detected and scans the periphery at a high magnification. The position and direction of pressing the sample with the probe of the scanning probe microscope are determined based on the information on the position of the sample on the substrate specified by the method for discovering and the information on the target movement position of the sample on the substrate. Then, based on the determination, push the sample with the probe and move it,
When it is determined that the probe has come off the sample, the vicinity of the probe position on the substrate at the time of the determination is scanned at a high magnification to detect the sample, information on the position of the detected sample and target movement of the sample on the substrate Based on the information on the position, the position and the pressing direction of the sample are again determined by the probe, and the sample on the substrate using the scanning probe microscope is moved based on the determination. How to make. A method according to any one of claims 6 to 8, comprising
When it is determined that the sample has collided with an obstacle, the direction of pressing the sample is changed and the sample is pushed and moved in a movable direction, and then information on the position of the sample and information on the target position of the sample on the substrate A method of moving a sample on a substrate using a scanning probe microscope, which again determines a position and a pressing direction for pressing the sample with a probe, and presses and moves the sample with the probe based on the determination. A method according to any one of claims 6 to 9, comprising
A sample on the substrate using the scanning probe microscope that monitors a friction signal input from the probe of the scanning probe microscope and determines that the probe has come off the sample based on a change in the friction signal. How to move.   A scanning probe microscope for discovering a sample on a substrate by the method for discovering a sample on a substrate using the scanning probe microscope according to any one of claims 1 to 5.   A scanning probe microscope that moves a sample on the substrate using the method of moving a sample on the substrate using the scanning probe microscope according to claim 6.

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