JP3137799B2 - Scanning probe microscope apparatus and measuring method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscope apparatus for measuring the surface shape, electrical characteristics, magnetic characteristics, and the like of a sample using a tunnel microscope, an atomic force microscope, or the like.

[0002]

2. Description of the Related Art In a scanning probe microscope, a probe having a sharp tip is brought close to the sample to the order of nanometers (nm), and a tunnel current or an atomic force generated between the probe and the sample is then reduced. By measuring, the shape of the sample surface,
This is a device for measuring electric characteristics, magnetic characteristics, and the like. The scanning range of such a scanning probe microscope is several hundred at most.
μm.

FIG. 11 is a side view of the basic structure of a scanning probe microscope. In this figure, X, Y, and Z indicate coordinate axes (the same applies to each figure below). Reference numeral 1 denotes an X stage driven in the X-axis direction, and reference numeral 2 denotes a Y stage driven in the Y-axis direction. 4 is XY
A sample to be measured placed on the stage 3, 5 is a probe facing the sample 4, 6 is a fine movement mechanism for slightly displacing the probe 5 in X, Y, and Z-axis directions, and 7 is a probe 5 at the start of measurement. Is a Z-axis mechanism for moving the sample to the sample 4 (moving in the Z-axis direction). Numeral 8 denotes a phenomenon occurring between the probe 5 and the sample 4 (tunnel current in the case of a tunnel microscope, atomic force in the case of an atomic force microscope).
2 shows a detector for detecting.

FIG. 12 is a perspective view of the fine movement mechanism 6 shown in FIG. In this figure, 60 is a cylindrical piezoelectric element, 6X is two electrodes attached to the surface of the piezoelectric element 60 in the X-axis direction, and 6Y is attached to the surface of the piezoelectric element 60 in the Y-axis direction. The two electrodes, 6Z, are electrodes provided on the surface circumference of the piezoelectric element 60.

Next, the operation of the scanning probe microscope will be briefly described. First, the XY stage 3 is driven to move the measurement position of the sample 4 to a position facing the probe 5. As described above, since the scanning range of the probe is several hundred μm, the measurement position of the sample 4 cannot be visually opposed to the probe 5. For this reason, an optical microscope is usually used. First, the measurement position of the sample 4 is captured within the visual field of the optical microscope, and then the XY stage is moved by the distance (known) between the center of the visual field of the optical microscope and the probe 5. Are moved so that they face each other.

In this state, when the Z-axis mechanism 7 is driven to move the probe 5 toward the measurement position of the sample 4, when the distance between the two reaches a certain distance, the detector 8 detects the tunnel current or Atomic forces are detected. After that, the fine movement mechanism 6 is driven to perform scanning by the probe 5. This scanning is performed by applying a predetermined voltage to the electrodes 6X and 6Y of the fine movement mechanism 6. During this scanning, a voltage is applied to the electrode 6Z of the fine movement mechanism 6 so that the detection value of the detector 8 becomes constant.
This voltage is the value measured by the scanning probe microscope.

[0007]

Incidentally, in the above-mentioned scanning probe microscope apparatus, there are cases where a plurality of points are measured on one sample. In such a measurement, for example, measurement of the shape of several pits existing on the same track on an optical disc, measurement of the shape of an element connected by one conductor on a semiconductor chip, and measurement of two or more measurement objects The location often exists along a known trajectory (designed reference line). When the measurement target locations have the above-described relationship, if the XY stage 3 is moved along the reference line from one measurement target location to the next measurement target location, optical measurement is performed for each measurement location. The measurement can be performed without performing positioning using a microscope, and troublesome labor should be saved.

However, the actual reference line on the sample is usually smaller than the designed reference line but has an error. Therefore, even if the XY stage is moved along the reference line, During the movement, the probe gradually deviates from the actual reference line, and as a result, it is often impossible to accurately position the probe 5 at the measurement target location, and the measurement is often impossible.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a scanning probe microscope apparatus that can automatically and reliably follow a Y stage along a certain reference line.

[0010]

In order to achieve the above object, the present invention provides an XY stage for moving a sample in the X-axis and Y-axis directions, a probe facing the sample, and an X-ray stage. A fine movement mechanism for moving in the axis, Y-axis and Z-axis directions;
In a scanning probe microscope apparatus having a measurement unit that obtains information on the sample surface based on the movement of the fine movement mechanism in the Z-axis direction, a movement vector for moving the XY stage along a predetermined reference line is determined. First calculating means for calculating, and XY in accordance with a calculation result of the first calculating means.
Fine movement mechanism driving means for moving the fine movement mechanism in a direction in which the probe crosses the reference line when the stage moves,
A second calculating means for calculating an error vector between characteristic points of adjacent measured values obtained by driving the fine movement mechanism driving means, and the first calculation based on the error vector calculated by the second calculating means. Correction means for correcting the operation value of the means.

The present invention further provides an XY stage for moving a sample in the X-axis and Y-axis directions, a probe facing the sample, and a fine movement mechanism for moving the probe in the X-axis, Y-axis and Z-axis directions. And a measuring unit for obtaining information on the surface of the sample based on the movement of the fine movement mechanism in the Z-axis direction. In the scanning probe microscope apparatus, the XY stage is moved in a predetermined angular direction with respect to a predetermined reference line. A measuring means for performing measurement by the probe during the movement, and when a characteristic point is generated in a measured value by the measuring means, the XY stage is moved in the direction of the reference line to search for a line composed of a series of characteristic points. Searching means; and reflecting direction moving means for moving the XY stage in the reflecting direction of the moving direction of the XY stage at the feature point occurrence location with respect to the line obtained by the searching means. Also characterized in that digit.

[0012]

According to the first aspect of the present invention, the XY on which the sample is mounted is provided.
The stage is intermittently or continuously moved at a low speed along a predetermined reference line. During this movement, the fine movement mechanism moves across the reference line to acquire a measurement image. In such an operation, a comparison is made between each characteristic point of the previously acquired measurement image and each characteristic point of the measurement image acquired this time, an error in the current movement is found from both characteristic points, and the next movement is corrected using this error. Thus, the XY stage can be accurately moved along the reference line.

According to the third aspect of the invention, first, the XY stage is moved at a predetermined angle with respect to the reference line.
During this movement, the measurement image is collected by the fine movement mechanism and the probe. When a feature point appears in the measurement image, a continuous line of the feature point is found by moving the XY stage along the direction of the reference line. Then, the next movement is performed on the continuous line in the reflection direction of the movement direction at the feature point. By repeating this operation, the XY stage can be accurately moved along the reference line.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a perspective view of a scanning probe microscope according to an embodiment of the present invention. In FIG. 1, the same or equivalent parts as those shown in FIG. 9
Is a bridge that supports the probe 5, the fine movement mechanism 6, the Z-axis mechanism 7, and the detector 8. The bridge 9 also supports an optical microscope, but is not shown. v (x), v
(Y) and v (z) are calculated by a fine movement controller, which will be described later, and given to the fine movement mechanism 6 in the X, Y, and Z-axis directions, and S (z) is given to the Z-axis mechanism 7. The command values S (x) and S (y) are command values to the XY stage 3 calculated by the XY stage controller described later, and B
Indicates a detection value of the detector 8. Further, f (x, y) represents a function of a locus (reference line) along an area to be measured by the probe 5 like a track on the optical disk when the sample 4 is an optical disk, for example, and C is the reference. The start point of the line, E, indicates the movement locus of the probe 5.

In the present embodiment, the reference line can be automatically followed, but the measurement by the probe 5 is used for the following. Therefore, the principle of measurement will be described first with reference to FIGS. FIG. 2 shows the function f
When the reference line represented by (x, y) is a straight line,
FIG. 9 is a diagram illustrating a measurement operation when f (x, y) = x. In this figure, C indicates the starting point of the reference line, and 11 indicates the relative trajectory of the probe 5. First, the probe 5 and the starting point C are opposed to each other using an optical microscope or the like as described above, and the probe 5 is moved by the Z-axis mechanism 7.
After approaching the starting point C until the detection value of the detector 8 reaches a predetermined value, measurement is started.

First, the probe 5 is moved to Y by the command value v (y).
It is moved by a small distance Δh / 2 in the negative axis direction, and during this movement, a measurement value based on the command value v (z) is obtained. Next, the X stage 1 is moved by a small distance Δi by the command value S (x).
After moving in the axial direction, the movement is stopped. Next, the probe 5 is moved in the positive Y-axis direction by a small distance Δh by the command value v (y).
Move only for measurement. Further, the X stage 1 is moved in the axial direction by a minute distance Δi and stopped by the command value S (y), and thereafter the probe 5 is moved in the negative direction of the Y axis by a minute distance Δh to perform measurement. This movement is a movement crossing the reference line in the orthogonal direction. By repeating such an operation, the probe 5 relatively draws the illustrated trajectory 11, and this trajectory can be continued as necessary.

FIG. 3 is a diagram showing a measuring operation when the reference line is a circular arc. In the figure, C indicates the starting point of the reference line, O indicates the origin of the arc, and r indicates the radius of curvature of the arc. In this case, the command value S
(X), the X stage 1 and the Y stage 2 are simultaneously moved by S (y), and the reference line of the arc is intermittently drawn by a small distance Δi, and the probe 5 sets the command value every time the XY stage 3 stops. The measurement is performed by alternately reciprocating a small distance Δh in a direction orthogonal to the arc by v (x) and v (y). In this case, the probe 5 draws the illustrated trajectory 11 and has the same effect as that shown in FIG.

FIG. 4 is a diagram showing the measuring operation when the reference line is a straight line in the X-axis direction, and C is the starting point of the reference line. FIG.
In the measurement operation shown in FIG. 4, the command value S (x) is a command to move the X stage 1 intermittently, and the command value v (y) is a command to move the probe 5 intermittently. In the illustrated measurement operation, the command value S (x) is a command for continuously moving the X stage 1 at a constant low speed, and the command value v (y) is also the probe 5
Is a command to continuously reciprocate. By such a command, the probe 5 draws a saw-like trajectory 12 as shown in the figure, and in this case also, the same effect as that shown in FIG. 2 is obtained.

In the measuring operation shown in FIG. 4, it is difficult to move the X stage 1 continuously at a constant low speed with a normal driving mechanism. For this reason, a combination of a static pressure guide and an electromagnetic motor is required. An appropriate drive mechanism such as a friction drive mechanism or a drive mechanism using a combination of an elastic guide and a piezoelectric element is used.

FIG. 5 is a diagram showing the measuring operation when the reference line is the same arc as the one shown in FIG. 3, and C indicates the starting point of the reference line. In the measurement operation shown in FIG.
(X) and S (y) are commands to move the XY stage 3 intermittently, and command values v (x) and v (y) are commands to move the probe 5 intermittently. In the measurement operation shown in (1), the command values S (x) and S (y) are
This is a command for moving the stage 2 continuously at a constant low speed and simultaneously, and the command value v (x,) v (y) is also a command for causing the probe 5 to reciprocate continuously. By such a command, the probe 5 draws the illustrated trajectory 12, and the same effect as that shown in FIG. 2 is achieved. In this case, the same drive mechanism as that used in the case of the measurement operation shown in FIG. 4 is used.

Here, the operation of the present embodiment for following the reference line will be described. FIG. 6 is a block diagram of the controller for driving the scanning probe microscope shown in FIG. In this figure, the same parts as those shown in FIG. 1 are denoted by the same reference numerals. Reference numeral 15 denotes a controller;
5a and an XY stage controller 15b. The function f (x, y) of the reference line to be drawn by the XY stage 3 is input to the XY stage controller 15b in advance. The operation of the controller 15 will be described with reference to FIGS.

FIG. 7 is an enlarged perspective view of a part of a portion serving as a reference line on the sample, and FIG. 8 is a diagram showing a measurement image of the sample shown in FIG. In FIG. 7, reference numeral 4 denotes a sample, and reference numeral 40 denotes a surface of the sample 4. 4
Numeral 1 denotes a V-shaped groove to be measured formed on the surface 40 with the same width, and is formed along a reference line represented by a function f (x, y). Hereinafter, an operation in the case where the above groove 41 is measured by intermittent driving as in the case shown in FIG. 3 will be described.

As in the case shown in FIG. 3, the starting point is positioned, the probe 5 is driven, and the XY stage 3 is first moved by a small distance Δi.
a indicates that the probe 5 has a velocity vector v ₁ (x
Drive in y). This velocity vector v ₁ (xy) is expressed by X
Based on the velocity vector S (xy) output from the XY stage controller 15b when the Y stage 3 is moved by the minute distance Δi, the fine movement controller 15
It is calculated by a. The calculated velocity vector v ₁ (x
In order to drive the probe 5 in accordance with y), the fine movement mechanism 6 receives the speed vector command value v as shown in the vector diagram of FIG.
₁ (x) and v ₁ (y) are output.

During the movement of the probe 5 according to the command values v ₁ (x) and v ₁ (y), the detection value of the detector 8 is input to the fine movement controller 15a, and the corresponding command value v (z) Is output to obtain a measurement image. This measured image is denoted by reference numeral 4 in FIG.
0J ₁ and 41J ₁ are shown. 40 J ₁ measurement image of the surface 40 of the sample 4, 41J ₁ is a measurement image of the groove 41.
Incidentally, K ₁ an aspect of the measurement image, indicating the starting point in this case groove 41. On the other hand, the XY stage controller 15b also receives the detection value of the detector 8 and obtains a measurement image. The measurement image may be a measurement image obtained by the fine movement mechanism 6.

Next, since the XY stage controller 15b moves the minute distance Δi along the function f (x, y), the velocity vector S ₁ (shown by a broken line in FIG. 8) based on the function f (x, y). xy), and outputs command values S (x) and S (y) for driving the XY stage 3 in accordance with the calculated values. The XY stage 3 stops after moving according to this command value. Next, in the same manner as described above, the probe 5 moves at the velocity vector v ₂ (xy) as shown in FIG. 7 according to the command value of the fine movement controller 15a, and the surface measurement image 40J ₂ and the groove shown in FIG. obtaining a measurement image 41J _2.

Here, the XY stage controller 15b
The previous measurement image, based on and the current measurement image previously calculated the velocity vector S ₁ (xy), the velocity vector S ₁ characteristic point at the tip and the current measurement image (xy) K ₂
Is calculated (error vector).
If the movement of the minute distance Δi of the XY stage 3 exactly follows the function f (x, y), the tip of the velocity vector S ₁ (xy) from the feature point K ₁ of the first measurement image and the next Should coincide with the characteristic point K ₂ of the measurement image. But,
In the case of the example shown in FIG. 8, the error vector δS ₁ (x
y) has occurred. Therefore, the XY stage controller 15b calculates the error vector δS ₁ (xy), corrects the error, and as shown in FIG. 8, the velocity vector S ₂ (xy) for the next movement of the minute distance Δi. ) << = S ₁
(Xy) + δS ₁ (xy) >>, and outputs command values S (x) and S (y) according to the calculation. Thereafter, the same processing is repeated, and the XY stage 3 moves along the function f (x, y) that is given exactly.

As described above, in this embodiment, the XY stage is moved along the locus of the reference line along the measurement target area,
During the movement, the probe is reciprocated across the reference line to perform the measurement, and the movement of the XY stage is corrected based on the measurement image, so that the XY stage is automatically moved along the reference line. It can be moved precisely and accurately.

FIG. 9 is an explanatory view for explaining a reference line automatic tracking means according to another embodiment of the present invention. In this figure, 20
Indicates a part of the surface of the semiconductor pattern. Reference numerals 21 and 22 denote circuit elements of the semiconductor pattern 20, respectively, and reference numeral 23 denotes a conductor (corresponding to a reference line) connecting the circuit elements 21 and 22. As shown in FIG. 10, the conductor portion 23 is formed in a trapezoidal shape protruding from the surface, and has a corner (characteristic point) P.
In this embodiment, a controller corresponding to the controller shown in FIG. 6 is also provided, but illustration thereof is omitted.

Here, the means for measuring the circuit element 21 and subsequently measuring the circuit element 22 will be described. When the measurement of the circuit element 21 is completed, the position and the direction of the conductor 23 are known. Therefore, the XY stage controller moves the XY stage 3 at a predetermined angle with respect to the extending direction of the conductor 23 (direction of the reference line). The trajectory of this movement is indicated by a broken line 25 in FIG. During this movement, the surface shape of the conductor portion 23 is measured by the probe 5. The continuing such movement and measurement operation, probe 5 reaches the characteristic point P ₂₆ of the conductor 23, detects this.

When the characteristic point P ₂₆ is detected, X is applied in the extending direction of the conductor 23 by the same means as in the previous embodiment, or
The measurement is performed while moving the Y stage 3, and the characteristic point P
One or more feature points subsequent to ₂₆ are detected, and a straight line connecting them is determined. This straight line is indicated by reference numeral 26 in FIG. Next, the XY stage controller calculates the straight line 26
It calculates the incident angle theta of the trajectory 25 in the feature point P ₂₆ for in turn moves the XY stage 3 to the reflecting direction (reflection angle theta) of the trajectory 25 with respect to the straight line 26. The trajectory of this movement is indicated by a broken line 27 in FIG.

By repeating the above operation, the XY stage 3 can automatically and reliably follow the conductor portion 23, and the probe 5 can automatically face the circuit element 22. The measurement of the circuit element 23 is performed.

[0032]

As described above, according to the present invention, the XY stage is moved along a predetermined reference line, feature points are sequentially detected, and the movement error is corrected based on adjacent feature points. Or by moving the XY stage at a predetermined angle along the reference line to detect a feature point by measurement, and changing the movement direction to the reflection direction of the movement direction up to that point when the feature point is detected. Since such an operation is repeated, the XY stage can be automatically and reliably followed along the reference line.

[Brief description of the drawings]

FIG. 1 is a perspective view of a scanning probe microscope according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a measurement operation of the scanning probe microscope shown in FIG.

FIG. 3 is an explanatory diagram of a measurement operation of the scanning probe microscope shown in FIG.

FIG. 4 is an explanatory diagram of a measurement operation of the scanning probe microscope shown in FIG.

5 is an explanatory diagram of a measurement operation of the scanning probe microscope shown in FIG.

6 is a block diagram of a controller that controls a measurement operation of the scanning probe microscope shown in FIG.

FIG. 7 is an enlarged perspective view of a part of a reference line on a sample.

FIG. 8 is a view showing a measurement image of the sample shown in FIG. 7;

FIG. 9 is a plan view of a part of the semiconductor pattern.

FIG. 10 is a sectional view taken along line XX shown in FIG. 9;

FIG. 11 is a side view of a conventional scanning probe microscope.

12 is a perspective view of the fine movement mechanism shown in FIG.

[Explanation of symbols]

3 XY stage 4 Sample 5 Probe 6 Fine movement mechanism 8 Detector v (x), v (y), v (z), S (x), S (y)
Command value

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-66127 (JP, A) JP-A-3-231108 (JP, A) JP-A-63-220305 (JP, A) JP-A-57- 79404 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 21/00-21/32 G01B 5/00-7/34 102 G01N 13/10-13/24 G01N 37 / 00 H01J 37/28

Claims (5)

(57) [Claims] 1. An XY stage for moving a sample in the X-axis and Y-axis directions, a probe facing the sample, a fine movement mechanism for moving the probe in the X-axis, Y-axis and Z-axis directions.
In a scanning probe microscope apparatus having a measurement unit that obtains information on the sample surface based on the movement of the fine movement mechanism in the Z-axis direction, a movement vector for moving the XY stage along a predetermined reference line is determined. First calculating means for calculating, and XY in accordance with a calculation result of the first calculating means.
Fine movement mechanism driving means for moving the fine movement mechanism in a direction in which the probe crosses the reference line when the stage moves,
A second calculating means for calculating an error vector between characteristic points of adjacent measured values obtained by driving the fine movement mechanism driving means, and the first calculation based on the error vector calculated by the second calculating means. A scanning probe microscope apparatus comprising: a correction unit for correcting a calculation value of the unit. 2. The scanning probe microscope apparatus according to claim 1, wherein said fine movement mechanism driving means drives said probe in a direction orthogonal to said reference line. 3. An XY stage for moving a sample in the X-axis and Y-axis directions, a probe facing the sample, a fine movement mechanism for moving the probe in the X-axis, Y-axis, and Z-axis directions.
In scanning probe microscope apparatus having a measuring unit for obtaining information of the sample surface based on the movement of the Z-axis direction of the fine movement mechanism is moved in a predetermined angular direction with the XY stage with respect to a predetermined reference line Measuring means for performing measurement by the probe during the movement, searching means for searching a line consisting of a continuation of the characteristic points for a predetermined length when a characteristic point is generated in the measured value by the measuring means, and searching means obtained by the searching means. A scanning direction moving means for moving the XY stage in the direction of movement of the XY stage at the point of occurrence of the characteristic point with respect to the obtained line. 4. A sample is placed on an XY stage for moving a sample in the X-axis and Y-axis directions, and a probe is arranged to face the sample, and the probe is placed on the X-axis, the Y-axis and the X-axis and Y-axis. Using a scanning probe microscope apparatus that obtains information on the surface of the sample by a fine movement mechanism that moves in the Z-axis direction perpendicular to the axis, a predetermined reference line for moving the XY stage is defined by a function f (x, y). The motion vector is calculated so that the XY stage moves along the reference line, and based on the calculation result, the probe is moved in the Z-axis direction by the fine movement mechanism while moving the XY stage. The X-axis and / or the Y-axis are moved across the reference line to measure the surface of the sample, and the characteristic points of the measured values obtained as a result of the measurement are detected, and other characteristic points adjacent thereto are detected. A measuring method for calculating an error between the two, and correcting the movement vector based on the calculated error. 5. A sample is placed on an XY stage for moving a sample in the X-axis and Y-axis directions, and a probe is arranged to face the sample, and at least this probe is a Z-axis orthogonal to the X-axis and the Y-axis. By a fine movement mechanism to move in the direction, using a scanning probe microscope apparatus to obtain information on the surface of the sample, a predetermined reference line for moving the XY stage,
The fine movement mechanism is moved in the Z-axis direction while the XY stage is tilted and moved in a predetermined angle direction with respect to the reference line to measure the sample surface, and the characteristic points of the measured values obtained from the measurement are measured. When detected, the XY stage is moved by a predetermined length along the reference line to find a continuous line of the feature point, and after obtaining the continuous line of the feature point, the XY stage is moved with respect to the reference line until then. A measuring method characterized by repeating the measurement by inclining and moving in a reflection direction with respect to a direction in which it has moved in a predetermined angular direction.