JPH06323844A - Measuring method for scanning probe microscope - Google Patents

Abstract

PURPOSE:To provide a measuring method for scanning probe microscope by which an objective point can be measured repeatedly and accurately. CONSTITUTION:When an objective point is measured for the first time, the straight line distance X0 between two opposing marks on a sample and the distance Y0 of a perpendicular from another mark on the sample to the straight line are measured. An XY stage is then shifted based on the coordinate values x0, y0 at the measuring point and the objective point is measured. In the second and subsequent measurements where the sample is thermally expanded, a straight line distance (X1) and a perpendicular distance (Y1) are measured and a control section operates the values (X1/X0), (Y1/Y0) which are then multiplied by the coordinate values x0, y0 to determine the corrected coordinate values(x1=ax0.X1/X0, y1=y0.Y1/Y0). The XY table is then shifted depending on the corrected coordinate values and the objective point is measured.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a scanning probe microscope apparatus, a probe with a sharp tip (atomic force microscope, cantilever in scanning force microscope, the same applies hereinafter) is applied to a nanometer (n
m) A device that measures the shape of the sample surface, electrical characteristics, magnetic characteristics, etc. by approaching to the order (contacting with a scanning force microscope) and measuring the physical quantity generated between the probe and the sample at that time is there. Such a device will be described with reference to FIG.

FIG. 4 is a perspective view of a scanning probe microscope apparatus. In the figure, X, Y, and Z indicate coordinate axes. Reference numeral 1 is a base provided with vibration preventing means, and 2 is an XY stage mounted on the base 1. XY stage 2 has X axis and Y
Displace in the axial direction. Numeral 3 is a fine movement mechanism fixed to the XY stage 2 and displaced on the order of submicron, and X,
At least the translational displacement in the Y and Z axis directions and the rotational displacement around the X, Y, and Z axes are possible. Reference numeral 4 is a sample table fixed to the fine movement mechanism 3, and 5 is an L-shaped mirror fixed to the sample table 4. D indicates a sample (for example, an optical disk) placed on the sample table 4.

Reference numeral 7 is a gate type structure provided on the base 1. Reference numeral 8 denotes a laser displacement meter which is attached to the gate structure 7 and faces the surface of the L-shaped mirror 5 along the Y-axis, and measures the amount of displacement of the sample table 4 in the X-axis direction. The displacement of the sample table 4 in the Y-axis direction is measured by another laser displacement meter (not shown). Reference numeral 9 is an optical microscope fixed to the portal structure 7. Reference numeral 10 is a probe microscope probe, 11 is a Z-axis coarse movement mechanism for largely moving the probe 10 in the Z-axis direction, 1
Reference numeral 2 denotes a probe fine movement mechanism for finely moving the probe 10 in the X, Y, and Z axis directions.

Here, the above-mentioned optical disk is taken as a sample, and the contents of measurement of the optical disk by the scanning probe microscope apparatus will be described with reference to FIGS. 5 and 6. FIG. 5 is a plan view of the optical disc, and FIG. 6 is a partially enlarged plan view of an address portion of the optical disc shown in FIG. In FIG. 5, D indicates an optical disc. The optical disc D is formed in a disc shape,
A number of tracks T ₁ , T ₂ , ... along the circumference
And a large number of sectors S ₁ , S ₂ , ... Are radially formed from the center. In the area defined by one track and one sector, the address parts A ₁₁ , A ₁₂ , ..., A ₂₁ , which specify the area,
A ₂₂ , ............ are configured. The area other than the address part of the area is a recording part for recording various information.
Taking an example of a 12-inch optical disk, the number of tracks is 41428 and the number of sectors is 63. In this case, the number of areas and hence the number of address parts is 2609.
It becomes 964.

The address portion is composed of track information indicating the track to which it belongs and sector information indicating the sector to which it belongs. These track information and sector information are
It is configured by the presence or absence of pits formed on the surface of the optical disc. "Yes" and "No" in the pit are 1 for each binary signal
Equivalent to a bit. In FIG. 6, each pit which is a part of the address portion is indicated by a symbol P. G ₁ and G ₂ are tracks T ₁ ,
The guide groove formed at T ₂ is shown.

FIG. 6 shows an example of the dimensions of each part. That is, the interval between the guide grooves G is about 1.6 μm, the width of the guide groove G is about 0.5 μm, and the interval between the pits is about 1.
6 μm, the diameter of each pit is about 1.2 μm, and the depth of each pit is about 0.03 μm. Further, in the case of the optical disc having the above numerical example, 17 bits or more are used for the track information and 7 bits or more are used for the sector information. For example, 30 bits are used for the track information and the sector information.

The above-mentioned optical disc is constructed with an address portion at the same time when it is manufactured. Then, if there is a defect in this address portion, the optical disc becomes unusable, so a well-known electrical characteristic test for judging the quality of the address portion is carried out for each optical disc after the optical disc is manufactured. If there is a defect in the address part, that is, if the shape of the pit is defective, an electrical signal corresponding to the shape of the defect appears in the electrical characteristic test. Therefore, if a defect occurs, the shape of the pit (abnormal pit) It is important to measure and investigate, for example, by the shape of the abnormal pit, it is possible to judge whether there is a defect in the manufacturing equipment, there is a problem with the material of the disk, or there is a defect in the original plate. , Can be dealt with appropriately.

A scanning probe microscope is used for measuring the shape of the pit because the dimension of the pit is extremely small as seen in the above numerical example. That is, when the probe 10 shown in FIG. 4 is scanned with the pit of the optical disc D and the surface around the pit being brought close to (or in contact with) the pit and its periphery at a minute interval, the physical quantities such as tunnel current and atomic force generated between the two are obtained. Based on this, an image of the surface shape of the pit can be obtained.

[0010]

As described above, since the measurement result of the shape measurement of the abnormal pit has a great influence on the judgment as to whether or not basic things such as the optical disc manufacturing apparatus, material and original plate are used, the shape measurement is performed. Is usually performed repeatedly for the same pit, which makes it possible to obtain extremely accurate and reliable data.

When the measurement operation is started, heat is generated in the probe fine movement mechanism 12 and in various places of the scanning probe microscope apparatus, and the heat is transferred to the sample (optical disk) and expanded. For example, if the temperature of the optical disc changes by ± 1 ° C, it is ±
A deviation of 1 μm occurs. Therefore, if no measures are taken, in repeated measurement of the same pit, thermal expansion occurs in the sample during the second and subsequent measurements with respect to the coordinate position of the pit at the beginning of measurement, and this thermal expansion causes the pit position to change. Since they are deviated, even if the XY stage is moved with the same coordinate value, the probe cannot be made to face the pit, and it is difficult to measure the same pit. Furthermore, in recent years
Since the pit diameter and the interval between tracks are made even smaller than the numerical values illustrated in FIG. 6, the difficulty of measuring the same pit due to thermal expansion increases more and more. In order to avoid the thermal expansion of the sample as described above, a constant temperature bath may be used, but the constant temperature bath is extremely expensive and requires a large space, which poses a serious problem in practical use.

An object of the present invention is to solve the above-mentioned problems in the prior art and to perform measurement of a scanning probe microscope apparatus capable of accurately performing repeated measurement at the same position on a sample even if thermal expansion occurs in the sample. To provide a method.

[0013]

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-axis for this probe. A fine movement mechanism for moving in the directions of the axis, Y axis, and Z axis,
In a scanning probe microscope apparatus including a measuring unit that obtains information on the surface of the sample based on the movement of the fine movement mechanism in the Z-axis direction, a straight line between two marks at opposing positions on the sample and the line When the coordinate value of the measurement target position whose origin is the intersection point with the perpendicular drawn from the other mark attached to the sample to the straight line, when the input of this coordinate value is the first input, the straight line And the distance of the perpendicular is measured and the measured values are stored, the movement command of the XY stage is output based on the coordinate value to measure the measurement target position, and the input coordinate value is the first. If not input, measure the distance between the straight line and the perpendicular,
The coordinate value is calculated by multiplying the coordinate value by the ratio of the measured value and the previously stored measured value, and the movement command value of the XY stage is output based on the corrected coordinate value to measure the measurement target position. It is characterized by

[0014]

When the coordinate value of the measurement target point for repeated measurement is input and the input is the first input, the linear distance (X ₀ ), and further, the perpendicular distance (Y ₀ ) drawn from the other mark attached to the sample to the straight line is measured. Then, these values (X ₀ , Y ₀ ) and the input coordinate values (x ₀ , y ₀ ) are stored in the storage means, and the XY stage is moved according to the coordinate values to measure the measurement target point. I do.

If the coordinate value is not input first, the straight line distance (X ₁ ) and the normal distance (Y ₁ ) are measured, and the ratio of these distances to the distances stored in the storage means ( (X ₁ / X ₀ ), (Y ₁ / Y ₀ )) are calculated, and the ratio of these is calculated as the coordinate value (x ₀ , y) stored in the storage means.
₀ ) multiplied by the corrected coordinate value (x ₁ = x ₀ · X ₁ /
X ₀ , y ₁ = y ₀ · Y ₁ / Y ₀ ) is calculated, the XY stage is moved according to the corrected coordinate value, and the measurement target point is measured.

[0016]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram of a control mechanism of a scanning probe microscope apparatus according to an embodiment of the present invention. In the figure, the same parts as those shown in FIG. 4 are designated by the same reference numerals. Reference numeral 15 is an image processing device for processing a microscope image of a CCD camera provided in the optical microscope 9, 16 is a display device for displaying the image obtained by the image processing device 15, and 17 is control of a laser oscillator of the laser displacement meter 8. A laser displacement gauge controller that receives measured values, 18 is a probe microscope controller that controls the drive of the Z-axis coarse movement mechanism 11 and the probe fine movement mechanism 12 of the probe microscope, and 19 is an X that controls the drive of the XY stage 2.
A Y stage controller, 20 is a fine movement mechanism controller that drives and controls the fine movement mechanism 3, 21 is a control unit that performs various predetermined calculations and controls, and 22 is a display device that displays the processing results of the control unit 21.

Next, the operation of this embodiment will be described with reference to FIGS. 2 is a plan view of the optical disc D in which an abnormal pit is found in the electrical characteristic test, and FIG. 3 is a control unit 2
3 is a flowchart illustrating the operation of No. 1. In FIG. 2, P
₀ indicates an abnormal pit existing on this optical disc D, and its coordinates are indicated by (x ₀ , y ₀ ). This coordinate is
It is represented by coordinates with the center O of the optical disc D as the origin. M
Reference numerals ₁ , M ₂ and M ₃ denote reference marks attached to the optical disc D.

The control unit 21 controls the coordinate value x of the abnormal pit P _0.
It is determined whether ₀ , y ₀ (origin is O) is input (step S ₁ shown in FIG. 3). When there is an input, it is determined whether or not the coordinate value is the first input (step S
₂ ) If it is the first input, the linear distance (X ₀ ) between the reference marks M ₁ and M ₂ and the reference mark M with respect to the straight line between them.
_It waits for the input of the distance of the perpendicular drawn from ₃ (the linear distance Y ₀ between the reference mark M ₃ and the origin O) (step S ₃ ). These distances X ₀ and Y ₀ are measured as follows.

With the optical disk D placed on the sample table 4, the measurer first manually moves the XY stage 2 to bring the center of the reference mark M _{1 into} the center of the visual field of the optical microscope 9. If the reference mark is square, edge detection is performed by a known means. Then, XY stage 2 again
To move the center of the reference mark M _{2 into} the center of the visual field of the optical microscope 9. By this operation, the control unit 21 receives the reference mark M by the signal from the XY stage controller 19.
_The straight line distance (X ₀ ) connecting ₁ and M ₂ is obtained. Further, the measurer puts the reference mark M ₃ in the center of the visual field of the optical microscope 9. Since the position of the reference mark M ₃ is determined by this operation, the control unit 21 draws a perpendicular from the position to the straight line connecting the reference marks M ₁ and M _2, and the distance (Y
₀ ) is calculated. By such processing, the optical disc D
X-axis, Y-axis, and origin O are determined. In this case, since the measurement is started, thermal expansion does not occur in the optical disc D, and therefore these coincide with the predetermined coordinate axes of the optical disc.

When the measured values X ₀ and Y ₀ are obtained in this way, the control unit 21 controls the coordinate values x ₀ and y ₀ and the measured value X ₀ ,
Store Y ₀ in a storage unit (not shown) (step S
₄ ) and then outputs a movement command based on the coordinate values x ₀ and y ₀ to the XY stage controller 19 (step S).
₅ ). In this case, it is natural that the coordinate values x ₀ and y ₀ are converted into the coordinate values of the XY stage 2. As a result, the XY stage 2 first moves the abnormal pit P ₀ to the center of the visual field of the optical microscope 9, and then moves a known distance between the center of the visual field of the optical microscope 9 and the probe 10 to move the probe. 10 and the abnormal pit P ₀ are made to face each other. Then, the probe microscope controller 18 is driven to measure the shape of the abnormal pit P ₀ (step S ₆ ). Next, it is judged whether or not all the repeated measurements have been completed (procedure S ₇ ). In this case, since it is the first measurement, the process is returned to step S ₁ .

If the measurement is the second time or later, the process is step S ₂
The transition from to step S _8. In this case, since the optical disk D has already undergone thermal expansion, the measurer measures the straight line distance connecting the reference marks M ₁ and M ₂ and the distance from the reference mark M _{3 by} the same means as described above. The measured values at this time are X ₁ and Y ₁ . When the control unit 21 the measurement value is obtained in step S _8, the ratio between the measured value X _0, Y ₀ stored previously and these measurements in step S _{4, i.e., (X 1 / X 0)} ,
(Y ₁ / Y ₀ ) is calculated (step S ₉ ). Then, the coordinate value x ₀ , y ₀ is multiplied by these ratios to obtain the corrected coordinate value x
₁ , y ₁ , that is, (x ₁ = x ₀ · X ₁ / X ₀ ), (y ₁
= Y ₀ · Y ₁ / Y ₀ ) is calculated (step S ₁₀ ). Then, the movement command based on the corrected coordinate values x ₁ and y ₁ is output (step S ₁₁ ). In this case, of course, the coordinate value x ₀ ,
y ₀ is converted into the coordinate value of the XY stage 2, and the movement similar to the above is performed. As a result, the XY stage 2 moves the abnormal pit P ₀ to the position facing the probe 10, despite the thermal expansion of the optical disc D.
Next, the controller 21 controls the probe microscope controller 18
The shape of the abnormal pit P ₀ is measured by driving (step S ₆ ).

[0022] Since in this embodiment using such a method, in repeated measurements of abnormal pit P _0, the probe 10 can be surely face the abnormal pit P ₀ for each measurement, an accurate measurement It can be carried out.

In the description of the above embodiments, an optical disk was used as an example for explanation, but it is needless to say that it can be applied to any other specimen having a thermal expansion property. or,
If Invar having a low coefficient of thermal expansion is used for the sample table 4 and the gate structure 7, positioning can be performed with higher accuracy. In this case, the thermal expansions of the optical microscope 9 and the probe 10 are extremely small as compared with the thermal expansions of the sample table 4 and the gate structure 7, and therefore their influence on accuracy can be ignored.

[0024]

As described above, in the present invention, in the repeated measurement of the measurement target portion, the linear distance between the reference marks and the perpendicular distance between the other reference marks are measured for each measurement. Since the coordinate value of the measurement target point is multiplied by the ratio of the measured distance and the first measurement distance to correct the coordinate value, it is possible to ensure that the probe faces the measurement target point for each measurement. It is possible and accurate measurement can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus used for a measuring method of a scanning probe microscope apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of an optical disc.

FIG. 3 is a flowchart illustrating an operation of the device shown in FIG.

FIG. 4 is a perspective view of a scanning probe microscope apparatus.

FIG. 5 is a plan view of an optical disc.

FIG. 6 is an enlarged plan view of the optical disc within the field of view of the optical microscope.

[Explanation of symbols]

 2 XY stage 3 Fine movement mechanism 9 Optical microscope 10 Probe 18 Probe microscope controller 19 XY stage controller 21 Control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Morimoto 650 Jinrachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory

Claims (1)

[Claims] 1. 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.
In a scanning probe microscope apparatus including a measuring unit that obtains information on the surface of the sample based on the movement of the fine movement mechanism in the Z-axis direction, a straight line between two marks at opposing positions on the sample and the line When the coordinate value of the measurement target position whose origin is the intersection point with the perpendicular drawn from the other mark attached to the sample to the straight line, when the input of this coordinate value is the first input, the straight line And the distance of the perpendicular is measured and the measured values are stored, the movement command of the XY stage is output based on the coordinate value to measure the measurement target position, and the input coordinate value is the first. If not input, measure the distance between the straight line and the perpendicular,
The coordinate value is calculated by multiplying the coordinate value by the ratio of the measured value and the previously stored measured value, and the movement command value of the XY stage is output based on the corrected coordinate value to measure the measurement target position. A method for measuring a scanning probe microscope apparatus, which is characterized in that