JPH0843040A - Measuring method by confocal scanning optical microscope - Google Patents

Abstract

PURPOSE:To provide a measuring method by a confocal scanning optical microscope whereby samples of various surface shapes can be measured in a simple constitution in a wide range with a high resolution without changing a microscope system. CONSTITUTION:The method is applied to a confocal scanning optical microscope 16 which is equipped with an objective lens 32 casting a collective light at a sample 36, a two-dimensional scanning mechanism 24 scanning the collective light on the surface of the sample, and a Z-directional moving/controlling circuit 44 moving position of focus of the objective lens 32 and position of the sample 36 relatively. The moving number of times is set based on a measuring range and a moving amount of the moving/controlling circuit. When the number of moving times exceeds a permissible range, the measuring range is divided thereby to set a plurality of divided measuring ranges. The moving amount and the number of moving times are set for every divided measuring range, based on which the sample is measured. The method comprises the above processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a confocal scanning optical microscope measuring method for measuring surface information of a sample by scanning the sample with light.

[0002]

2. Description of the Related Art In such a confocal scanning optical microscope, transmitted light or reflected light generated from a sample point-illuminated by a point light source is focused on a pinhole, and then light passing through the pinhole is collected. Is detected by a photodetector, the surface information of the sample is measured.

FIG. 3A schematically shows the structure of a general confocal scanning optical microscope. That is, the point-like light emitted from the point light source 2 passes through the half mirror 4 and then is imaged point-like on the sample surface 8 by the aberration-corrected objective lens 6. The reflected light reflected from the sample surface 8 illuminated pointwise in this manner is guided again from the objective lens 6 to the half mirror 4, and then reflected by the half mirror 4 and condensed. A pinhole 10 is provided at the condensing position, and the light condensed on the pinhole 10 by the half mirror 4 passes through the pinhole 10 and is detected by the photodetector 12.

Such light detection is to be performed over the entire sample surface 8. At this time, the reflected light from the sample surface 8 is two-dimensionally scanned in the same manner as the raster scanning of the television, so that the sample surface 8 can be detected. It is possible to obtain a two-dimensional image of.

By the way, the sample surface 8 is not a uniform surface over the entire surface, and there is also a surface deviated from the condensing position of the objective lens 6 as shown by a symbol A, for example. The reflected light reflected from the surface A is not condensed on the pinhole 10. Therefore, the reflected light is reflected by the pinhole 1
Since it cannot pass 0, it will not be detected by the photodetector 12.

That is, the confocal scanning optical microscope can measure only the optical image of the sample surface 8 existing at the focusing position of the objective lens 6, that is, the focusing position.
Next, as shown in FIG. 3B, assuming that the sample 14 having three sample surfaces A, B, and C having different heights is observed with a normal optical microscope, for example, the sample surface A is focused. When this is done, the optical images of the sample surfaces B and C will be blurred. Therefore, it is impossible to observe the focused images for all the sample surfaces A, B, and C (that is, the optical images obtained when the sample surfaces A, B, and C are in focus). .

However, according to the confocal scanning optical microscope, after the focused image on the sample surface A (hereinafter, referred to as the A focused image) is stored, the A focused image and the sample surfaces B and C are stored.
It is possible to obtain focused images for all sample surfaces A, B, and C by optically adding the focused images for A to B. Actually, each sample surface A, B, C
The maximum values of the brightness of the optical images generated by the above can be added together.

For the method of measuring the surface information of the sample as described above, for example, "THEORY AND PRACTICE OF S
CANNING OPTICAL MICROSCOPY "(P126-130).

In this disclosure, the focused light is applied to one point on the sample surface, the focused light is Z-scanned in the optical axis direction (Z direction), and the position where the brightness becomes highest during the scanning ( Z position) is detected and saved. Next, by moving the focused light in the X direction to irradiate the next point on the sample surface with the focused light, the Z scanning similar to the above is performed in this state, and the position where the brightness becomes the highest during the scanning. Detect (Z position) and save. While repeating such Z scanning, the focused light is moved in the XY directions on the sample surface.
As a result, the surface information of the sample based on the change in brightness is measured.

In such a measuring method, the Z position information and the brightness information are simultaneously stored in different image memories. Note that, as a general image memory specification, for example, 512 pixels × 512 pixels × 8 bits (256 gradations)
Etc. are known.

[0011]

However, in such an image memory, the Z position information is only expressed within the range of 256 gradations. For example, when Z scanning is performed by 0.1 μm, the movement in the Z direction is 0.1 μm × 25.
There is a problem that the range is limited to 6 = 25.6 μm, making it impossible to measure a wide range.

Therefore, for example, the gradation is 8 bits (256
It is also possible to increase the image memory by enlarging from (gradation) to 10 bits (1024 gradation). However, when such an improvement is performed, the entire microscope system is inevitably reconfigured, which not only increases the manufacturing cost but also complicates the signal processing in the microscope system.

The present invention has been made to solve such a problem, and its object is to improve a wide range of samples having various surface shapes with a simple structure without changing the microscope system. It is an object of the present invention to provide a measuring method using a confocal scanning optical microscope capable of measuring resolution.

[0014]

In order to achieve such an object, the present invention provides an objective lens for irradiating a sample with focused light, and relatively scanning the focused light along the surface of the sample. It is applied to a confocal scanning optical microscope equipped with a scanning mechanism for controlling and a control means for relatively moving the focal position of the objective lens and the position of the sample along the optical axis direction of the focused light. A step of setting a measurement range for the sample; a step of setting a movement amount when the focus position of the objective lens and a position of the sample are relatively moved; A step of determining the number of movements when moving the focus position of the objective lens and the position of the sample relatively, and measuring the surface information of the sample when the number of movements is within an allowable range. Confocal with In the method using a scanning optical microscope, if the number of times of movement exceeds the allowable range,
A first step of dividing the measurement range to set a plurality of divided measurement ranges, a second step of setting the movement amount and the number of movements for each of the divided measurement ranges, and setting by the second step Based on the amount of movement and the number of movements performed,
Measuring the surface information of the sample.

[0015]

When the number of movements exceeds the allowable range, the measurement range of the sample is divided and a plurality of divided measurement ranges are set. Next, the amount of movement and the number of movements are set for each divided measurement range.
Then, the surface information of the sample is measured based on the amount of movement and the number of movements.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A measuring method by a confocal scanning optical microscope according to a first embodiment of the present invention will be described below with reference to FIG. FIG. 1A schematically shows the configuration of the microscope system of the confocal scanning optical microscope 16 applied to this embodiment.

According to such a configuration, the laser light source 18
The scanning laser light emitted from the two-dimensional scanning mechanism 2 is reflected by the mirror 20 and then passes through the half mirror 22.
It is incident on 4.

The two-dimensional scanning mechanism 24 is connected to a computer 28 via a scanning control unit 26, and is driven and controlled based on a scanning control signal P1 output from the scanning control unit 26 according to a command from the computer 28.

As a result, the scanning laser light output from the two-dimensional scanning mechanism 24 is focused on the sample 36 on the stage 34 via the objective lens 32 set in the revolver 30 in a fine spot state. 36 is scanned in the XY directions similarly to the raster scanning of the television.

At this time, the reflected light reflected from the sample 36 is guided to the half mirror 22 via the objective lens 32 and the two-dimensional scanning mechanism 24, and is reflected by the half mirror 22.

The reflected light reflected from the half mirror 22 is
After passing through the pinhole 38, the light enters the photodetector 40. The reflected light that has entered the photodetector 40 is converted into an electric signal corresponding to the amount of light, and the electric signal is output to the image processing unit 42.

The image processing unit 42 includes, for example, 512
The first and second image memories 42a and 42b each having a structure of pixels × 512 pixels × 8 bits (256 gradations) are incorporated.

The first image memory 42a includes a photodetector 4
0 is connected, and the electric signal output from the photodetector 40 is stored. The second image memory 42b includes a Z-direction movement control circuit 44 that controls the movement of the stage 34 in the Z direction (that is, the optical axis direction of the scanning laser light) to scan the scanning laser light in the Z direction. Connected,
The number of movements of the stage 34 is counted based on the signal output from the Z-direction movement control circuit 44, and the count value is stored.

The stage 34 includes a computer 28.
Based on the Z control signal P2 output from the Z-direction movement control circuit 44 in response to the command, the movement is controlled in the Z direction by a predetermined amount. At this time, the movement amount of the stage 34 per movement is controlled by the computer 28.

The setting of the measurement range, the amount of movement of the stage 34 within each measurement range, the control of the image display and the microscope system, etc. are set by the observer via the monitor 46 connected to the computer 28. It

In such a microscope system, an observer places the sample 36 on the stage 34 and then causes the computer 28 to scan a minute spot focused on the sample 36 in the XY directions. At the same time, the stage 34 is controlled to move in the Z direction to control the focus on the sample 36. At this time, the determination as to whether or not the sample 36 is in focus is made while looking at the image displayed on the monitor 46.

Next, the observer sets each parameter related to the measuring operation. That is, as shown in FIG. 1B, first, the computer 28 sets the measurement range L of the entire sample 36 (S1), and then sets the movement amount Δ of the stage 34 per movement (S2). This movement amount Δ is
In this embodiment, it is the movement amount when the position of the sample 36 is moved with respect to the focal position of the objective lens 32. It should be noted that the smaller the value of the movement amount Δ, the higher the resolution of the sample measurement that corresponds to the surface shape of the sample 36.

After setting the measurement range L and the movement amount Δ, the number of movements N of the stage 34 is determined. The number of movements N is determined according to the relationship of L / Δ ≦ N (S3). . For example, when L = 20 μm and Δ = 0.1 μm, N = 200.

By the way, the value of the number of movements of the stage 34 is counted up to the gradation of the image memory as described above, that is, up to 256 times. However, in the above example, the number of movements N is 200, which is 256 or less, so that the measurement for the sample 36 is started (S7).

Next, for example, L = 40 μm and Δ = 0.1
In μm, N = 400, and the number of movements is equal to or higher than the gradation of the image memory, so high-resolution measurement cannot be performed. In this case, the observer divides the entire measurement range L into a plurality of pieces and sets several measurement ranges (divided measurement ranges) L1 to LM (S4), and the measurement range L1 to LM of the stage 34 is set for each measurement range. Set the amount of movement Δ1 to ΔM per movement (S
5). For example, as shown in Table 1 below,

[0031]

[Table 1]

L1 = 10 mμ over the entire measuring range L = 40 μm
m, L2 = 20 .mu.m, L3 = 10 .mu.m, and the amount of movement of the stage 34 for each measuring range (divided measuring range) L1, L2, L3 is .DELTA.1 = 0.5 .mu.m, .DELTA.2 =
0.1 μm and Δ3 = 0.5 μm. Here, it is assumed that the Δ2 region is measured in detail (with high resolution) and the entire region is measured in a wide range. As a result,
Since the number of movements in the measurement range L1 is 20, the number of movements in the measurement range L2 is 200, and the number of movements in the measurement range L3 is 20, the total number of movements N is 240 (S6).

Therefore, the number of movements N of the stage 34 is equal to or less than the gradation of the image memory, that is, 256 times or less, and the sample measurement is performed (S7). That is, each divided measurement range L1
, L2, L3, the movement amounts Δ1, Δ2,
Δ3 and the number of movements are set, and based on this set value,
While scanning the sample 36 with the scanning laser light in the Z direction, the XY scanning is performed on the sample 36.

As described above, according to this embodiment, the measurement range is divided into a plurality of parts, and the movement amount and the number of movements of the stage 34 are individually set for each measurement range, without changing the microscope system. It becomes possible to measure the sample 36 having various surface shapes over a wide range with high resolution.

Next, a measuring method by the confocal scanning optical microscope according to the second embodiment of the present invention will be described with reference to FIG. In the description of this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 1 (a) and 1 (b), when setting the measurement range L (S1), the observer uses the computer 2
It is necessary to detect the highest position (highest position) and the lowest position (lowest position) of the height differences of the surface shape of the sample 36 via the monitor 46 connected to the No. 8 monitor.

Because, in the confocal scanning optical microscope,
This is because when the sample 36 is out of the in-focus position, the level of the image signal becomes zero, which makes it impossible to measure that portion.
Therefore, as shown in FIG. 2, in the confocal scanning optical microscope 16 applied to the present embodiment, an electric signal output from the photodetector 40 when scanning one screen in the image processing unit 42. A zero level detection circuit 42c for determining whether or not the level is zero is added.

The zero level detection circuit 42c automatically detects the highest position and the lowest position on the surface of the sample 36 based on the electric signal output from the photodetector 40, and the detected data is stored in the first image memory. It has a function of inputting to 42a.

Therefore, when setting the entire measuring range L of the sample 36, at the same time, the highest position and the lowest position of the surface of the sample 36 are automatically saved. In this embodiment, instead of moving the stage 34 in the Z direction, the revolver 30 is controlled to move in the Z direction (that is, the optical axis direction of the scanning laser light) to scan the scanning laser light in the Z direction. So that the Z-direction movement control circuit 44 causes the revolver 3 to move.
Connected to 0.

In this case, in the second image memory 42b,
The number of movements of the revolver 30 is counted based on the signal output from the Z-direction movement control circuit 44, and the count value is stored. Further, the revolver 30 is controlled to move in the Z direction by a predetermined amount based on the Z control signal P2 output from the Z direction movement control circuit 44 in accordance with a command from the computer 28. At this time, the amount of movement of the revolver 30 per movement is determined by the computer 28 for each movement. It should be noted that in the present embodiment, the movement amount refers to the sample 3
It is the movement amount when the focal position of the objective lens 32 is moved with respect to the position of 6.

With such a configuration, the flow and effect of the operation of the present embodiment is the same as that of the flowchart of FIG. 1B except that the stage 34 is replaced by the revolver 30, and therefore the description thereof will be made. Omit it.

The present invention is not limited to the configuration of the above-mentioned embodiment. For example, it is also preferable to add a zero level detection circuit 42c as shown in FIG. 2 to the image processing unit 42 of the microscope system as shown in FIG.

[0043]

According to the present invention, a general confocal scanning optical microscope is constructed by dividing the measurement range into a plurality of parts and individually setting the amount of movement and the number of movements of the stage for each measurement range. It becomes possible to measure samples having various surface shapes with high resolution over a wide range without changing the value.

[Brief description of drawings]

FIG. 1A is a block diagram schematically showing a configuration of a microscope system of a confocal scanning optical microscope applied to a first embodiment of the present invention, and FIG. 1B is a confocal scanning optical system. The flowchart of measurement operation by a microscope.

FIG. 2 is a block diagram schematically showing a configuration of a microscope system of a confocal scanning optical microscope applied to a second embodiment of the present invention.

3A is a diagram schematically showing a configuration of a general confocal scanning optical microscope, and FIG. 3B is a perspective view of a sample having three sample surfaces A, B, and C having different heights. Fig.

[Explanation of symbols]

16 ... Confocal scanning optical microscope, 24 ... Two-dimensional scanning mechanism, 32 ... Objective lens, 36 ... Sample, 44 ... Z direction movement control circuit, L ... Measuring range, Δ ... Movement amount, N ... Movement frequency.

Claims (1)

[Claims] 1. An objective lens for irradiating a sample with focused light, a scanning mechanism for relatively scanning the focused light along the surface of the sample, and the objective lens along the optical axis direction of the focused light. Is applied to a confocal scanning optical microscope having a control means for relatively moving the focal position of the sample and the position of the sample, the step of setting a measurement range for the sample, and the focal position of the objective lens. And a step of setting a movement amount when the position of the sample is relatively moved, based on the measurement range and the movement amount, the focus position of the objective lens and the position of the sample are relatively In the measuring method by a confocal scanning optical microscope, which comprises a step of determining the number of movements when moving, and a step of measuring the surface information of the sample when the number of movements is within an allowable range, A first step of dividing the measurement range to set a plurality of divided measurement ranges when the allowable range is exceeded, and a second step of setting the movement amount and the number of movements for each of the divided measurement ranges. And a step of measuring the surface information of the sample based on the movement amount and the number of movements set in the second step, the measuring method using a confocal scanning optical microscope.