JP2003075118A - Scanning laser microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning laser microscope capable of taking a three- dimensional image of a sample at high speed, and measuring the height of the sample highly accurately. SOLUTION: This microscope has a laser beam source 1, a light deflector 5 for scanning a laser beam on a sample 8, an objective lens 7 for condensing light onto the sample 8, a detector 11 for detecting the intensity of light from the sample 8, image acquisition means 13, 14 for acquiring an image based on the output of the detector 11, an image display means (not shown in Fig.), a stage 12 capable of adjusting the relative position between the sample 8 and the objective lens 7, a threshold setting part 15 for dividing an output value detectable by the detector 11 into plural regions, a determination part 16 for determining whether the output detected by the detector 11 exceeds the threshold or not, and a moving quantity setting driving part 17 for setting the moving quantity of the moving mechanism 12 corresponding to the result acquired by the determination part 16 and driving the moving mechanism 12 as much as the set moving quantity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a scanning laser microscope capable of observing and measuring the height of a sample.

[0002]

2. Description of the Related Art Conventionally, a scanning laser microscope has been used as an apparatus for observing the height of a sample.

FIG. 5 is a schematic configuration diagram of a conventional general scanning laser microscope. The conventional general scanning laser microscope includes a laser light source 1 and an optical deflector 5 which is a scanning means for scanning the laser light emitted from the laser light source 1 onto a sample 8.
And a laser beam directed to the sample 8 via the optical deflector 5
A / D as an image forming means for forming an image on the basis of the output detected by the detector 11 and the detector 11 for detecting the intensity of the light reflected by the sample 8
The converter 13 and the maximum output calculator 14 are provided. In the figure, ₁ 1, 1 ₂ lens system, 6 pupil relay lens system, an imaging lens 9, the pinhole 10, 12
Is the stage.

In the conventional scanning laser microscope, the laser light emitted from the laser light source 1, which is considered to be equivalent to a point light source, has its beam diameter changed through the lens systems 1 ₁ and 1 ₂ and the beam splitter. 4 and is reflected by the beam splitter 4 to enter the optical deflector 5 and is deflected by the optical deflector 5 so as to be directed to a predetermined scanning position on the sample 8. The laser beam deflected by the optical deflector 5 enters the pupil position of the objective lens 7 through the pupil relay lens system 6, is further condensed through the objective lens 7, and is mounted on the stage 12 on the sample 8 Irradiate. The light reflected by the sample 8 follows a path opposite to the path from the beam splitter 4 toward the sample 8, then passes through the beam splitter 4, and is further imaged at the position of the pinhole 10 via the imaging lens 9. To do.

This image plane is a plane on which an image is observed with a normal optical microscope. Unnecessary light that does not form an image of the sample 8 is removed by the pinhole 10 provided at the position of the image plane, and it is possible to obtain a high-resolution image without flare as compared with an ordinary optical microscope. Become. The light passing through the pinhole 10 is detected by a detector 11 provided behind it. The output detected by the detector 11 is converted into a computable signal via the A / D converter 13. The maximum output calculation unit 14 performs a process of storing predetermined information when the output detected by the detector 11 is the maximum output value.
This process will be described later. Then, by changing the angle of the light beam emitted from the light deflector 5, the sample 8 is moved to 1
An image obtained by scanning in the dimension (horizontal direction in the drawing) is obtained. The formed image is output to a display device such as a monitor (not shown).

Although FIG. 5 shows a structure capable of one-dimensional scanning, in addition to the structure shown in FIG. 5, an optical deflector having the same structure as the optical deflector 5 and the pupil relay lens system 6 is provided. A two-dimensional image of the sample 8 can be obtained by arranging the pupil relay lens system in the direction orthogonal to the paper surface.

Now, the process of forming an image of the sample 8 will be described. In the laser scanning microscope, the output value from the detector 11 becomes the maximum value when the sample 8 is in focus. Therefore, the relative position between the sample 8 and the objective lens 7 is
By moving the stage 12 up and down, it is moved in the Z direction (arrow direction) by a predetermined amount. Then, the reflected light from the sample 8 is detected by the detector 11 every movement. The output detected by the detector 11 is input to the maximum output calculator via the A / D converter 13. The maximum output calculation unit 14 includes a plurality of storage units. Among them, the first storage unit temporarily stores the output from the detector 11 at each position on the sample in synchronization with the scanning of the optical deflector. Stored in. The data stored in the first storage unit is compared with the data stored in the second storage unit, and the larger data is stored in the second storage unit. This process is performed every time the stage 12 is moved. Therefore, the data in the first storage unit is updated every time the stage is moved, and the data having the largest value is stored in the second storage unit. Further, the third storage unit stores the amount of movement of the stage until the data in the second storage unit reaches the maximum value. As a result, the data of the image when the sample is focused at each point is stored in the second storage section, and the height data of each sample point is stored in the third storage section. The height can be measured by using the data in the third storage unit.

However, in order to measure the sample 8 with high accuracy and to observe the details of the sample 8, the sample 8 should be used.
It is necessary to slightly change the relative position of the objective lens 7 and the objective lens 7, and therefore the stage 12 must be moved in minute steps. For this reason, it takes a considerable amount of time to obtain a clear image, especially for a sample having a large surface step. Also, changes in the microscope device over time,
For example, the misalignment of parts due to thermal expansion may affect the measurement reproducibility.

[0009]

Therefore, the present invention has been made in view of the above problems, and it is possible to capture a three-dimensional image of a sample at a high speed and to accurately measure the height of the sample. Provided is a scanning laser microscope capable of measuring.

[0010]

To achieve the above object, the scanning laser microscope according to the first aspect of the present invention comprises a laser light source and a scanning means for scanning a sample with the laser light emitted from the laser light source. An objective lens that collects laser light directed to the sample through the scanning means onto the sample; and a detector that detects the intensity of light reflected by the sample.
Image forming means for forming an image of the sample based on height information of the sample when the output detected by the detector reaches the maximum output value, and an image formed by the image forming means are displayed. A display device, a moving mechanism capable of adjusting the relative position of the sample and the objective lens, and a moving amount of the moving mechanism is set based on an output detected by the detector, and the moving amount is set by the set moving amount. And a movement amount setting drive means for driving the movement mechanism.

In the first aspect of the invention, the movement amount setting drive means sets a threshold value for setting a threshold value for dividing the output value detectable by the detector into a plurality of areas. A determination unit that determines whether an output when detected by the detector exceeds a threshold value set by the threshold value setting unit, and a determination result obtained by the determination unit. And a moving amount setting drive unit that drives the moving mechanism with the set moving amount.

The scanning laser microscope according to the second aspect of the present invention includes a laser light source, a scanning means for scanning the sample with the laser light emitted from the laser light source, and a laser light directed to the sample via the scanning means. An objective lens that collects light on the sample, an objective lens magnification detection unit that detects the magnification of the objective lens, a detector that detects the intensity of light reflected by the sample, and an output detected by the detector. The image forming means for forming an image of the sample based on the height information of the sample when the maximum output value, a display device for displaying the image formed by the image forming means, the sample and the A moving mechanism that can adjust the relative position with the objective lens,
A movement amount setting drive unit that sets the movement amount of the movement mechanism based on the output detected by the detector and the magnification detected by the objective lens magnification detection unit, and drives the movement mechanism with the set movement amount. And having.

In the second aspect of the present invention, the movement amount setting drive means sets a threshold value for setting a threshold value for dividing the output value detectable by the detector into a plurality of areas. A determination unit that determines whether or not the output when detected by the detector exceeds a threshold value set by the threshold value, a result obtained by the determination unit, and the objective lens magnification determination unit The moving amount of the moving mechanism is preferably set on the basis of the magnification obtained in step 1, and the moving amount setting drive unit drives the moving mechanism with the set moving amount.

According to the first and second aspects of the invention thus constituted, the movement amount (step) for changing the relative position between the objective lens and the sample is set according to the output from the detector. Since the relative position between the objective lens and the sample is adjusted in association with the movement amount, high-speed three-dimensional imaging becomes possible. According to the second aspect of the present invention, since the magnification of the objective lens is taken into consideration when setting the movement amount (step), it is possible to adjust the relative position more efficiently.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment FIG. 1 is a schematic configuration diagram showing a first embodiment of a scanning laser microscope of the present invention. The scanning laser microscope of this embodiment is
The present invention corresponds to the first aspect of the present invention, and is configured to include a comparator 16, a threshold value setting unit 15, and a Z driving unit 17 in addition to the configuration of the conventional scanning laser microscope shown in FIG. There is. Other basic configurations are the same as those of the conventional scanning laser microscope shown in FIG.

The threshold value setting unit 15 is configured to set a threshold value for dividing the output value detectable by the detector 11 into a plurality of areas. The comparator 16 is configured to determine whether the output when detected by the detector 11 exceeds the threshold value set by the threshold value setting unit 15. The Z drive unit 17 is configured to set the movement amount of the stage 12 according to the determination result obtained by the comparator 16 and drive the stage 12 with the set movement amount. As shown in the figure, the Z drive unit 17 and the maximum output calculation unit 14 are connected to each other, and the movement amount of the stage 12 is output to the maximum output calculation unit 14.

In the scanning laser microscope of this embodiment, the laser light emitted from the laser light source 1, which is considered to be equivalent to a point light source, has its beam diameter changed through the lens systems 1 ₁ and 1 _2. The light enters the splitter 4, is reflected by the beam splitter 4, enters the optical deflector 5, and is deflected by the optical deflector 5 so as to be directed to a predetermined scanning position on the sample 8. The laser beam deflected by the optical deflector 5 enters the pupil position of the objective lens 7 through the pupil relay lens system 6, is further condensed through the objective lens 7, and is mounted on the stage 12 on the sample 8 Irradiate. The light reflected by the sample 8 follows a path opposite to the path from the beam splitter 4 toward the sample 8, then passes through the beam splitter 4, and is further imaged at the position of the pinhole 10 via the imaging lens 9. Then, the intensity is detected via the detector 11 provided behind it.

The output detected by the detector 11 is converted into a signal that can be calculated by the A / D converter 13 and converted into image information by the maximum output calculator 14, which is displayed on a monitor (not shown). It is output to the device as an image. Then, by changing the angle of the light beam emitted from the optical deflector 5, an image obtained by one-dimensionally scanning (horizontal direction in the drawing) on the sample 8 can be obtained. Although the present embodiment has been described as a one-dimensional scanning microscope, an optical deflector and a pupil relay lens system having the same configuration as the optical deflector 5 and the pupil relay lens system 6 may be arranged in a direction orthogonal to the plane of the drawing. Thus, a two-dimensional image of the sample 8 can be obtained.

Here, the relationship between the relative position of the objective lens 7 and the sample 8 and the output detected by the detector 11 is shown in the graph of FIG. The horizontal axis of FIG. 2 is the relative distance between the sample 8 and the objective lens 7. Although the sharpness of the peak is different between the high-magnification waveform and the low-magnification waveform of the objective lens, the output V becomes maximum at any magnification in a very narrow range. As described above, the principle of acquiring the height data of the sample utilizes that the output V becomes maximum. Therefore, it is not necessary to move the stage finely until the output V becomes maximum. Therefore, in the present embodiment, the threshold value setting unit 15 sets the threshold value Vth in advance. As a result, the output value detectable by the detector 11 is divided into a plurality of areas. Then, the output from the detector 11 is converted into a signal that can be calculated via the A / D converter 13, and the comparator 16 compares it with the threshold value set by the threshold value setting unit 15. When the output value from the detector 11 is equal to or less than the threshold value, the unit amount (step) for moving the stage 12 in the Z direction via the Z drive unit 17 is set to the coarse movement amount to control the coarse movement of the stage 12. When the threshold value is exceeded, the amount of movement (step) in the Z direction via the Z drive unit 17 is changed to the fine movement amount, and the stage 12 is moved.
To control the fine movement.

The determination of the driving amount of the stage 12 based on the output of the detector 11 is made at each scanning position on the sample 8 via the deflector 5. That is, the signal output from the detector 11 (the output signal from the A / D converter 13) and the threshold value V from the start of scanning to the end of scanning by the optical deflector 5.
If the output signal is always lower than the threshold value Vth, the moving amount of the next stage is increased to increase the threshold value Vth.
When an output signal exceeding th is generated, the moving amount of the next stage is reduced. As a result, when the sample 8 having a step as shown in FIG. 3 is scanned by the microscope of this embodiment, the amount of fine movement is only in a predetermined range near the height position of the portions A and B having relatively flat surfaces. The stage 12 moves in the Z direction by the step driving of the above, and the stage 12 moves in the Z direction by the step driving of the coarse movement amount in the range of the height that does not contribute to the image formation of other images. Therefore, the Z coordinate at the time of maximum output can be detected (acquired) efficiently and quickly. As a result, a three-dimensional image can be obtained at high speed and with high accuracy. If a plurality of threshold values Vth are provided and the amount of coarse movement when the threshold value is less than or equal to the threshold value and the amount of fine movement when the threshold value is exceeded are set to the Z drive unit 17 differently for each threshold value, higher speed is achieved. In addition, it becomes possible to obtain a three-dimensional image with high accuracy.

As a method of setting the threshold value,
It may be changeable depending on the type of the sample 8. Further, a certain threshold value may be set for the dark part, and various methods are possible.

In the process of comparing the output signal at each scanning position with the threshold value Vth on a one-to-one basis, when noise exceeding the threshold value Vth occurs at an arbitrary scanning position, originally, Although the amount of movement of the next stage must be increased, an instruction to reduce the amount of movement of the next stage is output to the Z drive unit 17. To avoid this, the threshold value Vth may be set to a large value, but there is also a method described below. It is a method of providing a process of calculating an average of signals output from the detector 11 from the start of scanning by the optical deflector 5 to the end of scanning, and comparing the average value with a threshold value Vth. As a result, even if noise that exceeds the threshold value Vth occurs at any scanning position, the average value will fall below the threshold value Vth, so an instruction to reduce the movement amount of the next stage is not output. However, when measuring the sample as shown in FIG. 3 by the method of comparing the average value and the threshold value Vth, the following points must be noted. That is, when the surface A is approaching the in-focus position, the output signal due to the reflected light from the surface A exceeds the threshold value Vth. However, since the surface B is far from the in-focus position, the output signal due to the reflected light from the surface B is far below the threshold value Vth. Therefore, the average of the output signal of the reflected light from the A surface and the output signal of the reflected light from the B surface is the threshold value Vth.
May fall below. Therefore, although the movement amount of the next stage should be reduced originally,
The Z drive unit 17 gives an instruction to increase the movement amount of the next stage.
Will be output to. Therefore, in such a case, it is necessary to take measures such as setting the threshold value Vth slightly lower.

Second Embodiment FIG. 4 is a schematic configuration diagram showing a second embodiment of the scanning laser microscope of the present invention. The scanning laser microscope of this embodiment is
This corresponds to the second aspect of the present invention, and corresponds to the first aspect shown in FIG.
In addition to the configuration of the scanning laser microscope of the embodiment, a magnification sensor 19 for detecting the magnification of the objective lens is provided near the position of the objective lens 7, and the information obtained by the magnification sensor 19 is sent to the Z drive unit 17. The drive control method for the stage 12 in the Z drive unit 17 is different from that in the first embodiment. The other basic structure is almost the same as that of the scanning laser microscope of the first embodiment shown in FIG.

In the structure of this embodiment, the laser light emitted from the laser light source 1, which is considered to be equivalent to a point light source, has its beam diameter changed through the lens systems 1 ₁ and 1 ₂ and is directed to the beam splitter 4. The light enters, is reflected by the beam splitter 4, enters the light deflector 5, and is deflected by the light deflector 5 so as to be directed to a predetermined scanning position on the sample 8. The laser light deflected by the optical deflector 5 enters the pupil position of the objective lens 7 through the pupil relay lens system 6.

In the microscope of this embodiment, a plurality of objective lenses 7 having different magnifications are set on a revolver (not shown), and a magnification changing mechanism (not shown), such as rotation or slide, can switch the magnification of the objective lens 7. You can do it. Then, when the magnification of the objective lens 7 is switched by a magnification changing mechanism (not shown), the sensor 19 detects the magnification of the switched objective lens.

The laser light passed through the objective lens 7 is the stage 1
The sample 8 placed on the surface 2 is irradiated. The light reflected by the sample 8 follows a path opposite to the path from the beam splitter 4 toward the sample 8, then passes through the beam splitter 4, and is further imaged at the position of the pinhole 10 via the imaging lens 9. Then, the intensity is detected via the detector 11 provided behind it.

The output detected by the detector 11 is converted into a signal that can be calculated by the A / D converter 13, converted into image information by the maximum output calculator 14, and displayed on a monitor (not shown). It is output to the device as an image. Then, by changing the angle of the light beam emitted from the optical deflector 5, an image obtained by one-dimensionally scanning (horizontal direction in the drawing) on the sample 8 can be obtained. Although the present embodiment has been described as a one-dimensional scanning microscope, an optical deflector and a pupil relay lens system having the same configuration as the optical deflector 5 and the pupil relay lens system 6 may be arranged in a direction orthogonal to the plane of the drawing. Thus, a two-dimensional image of the sample 8 can be obtained.

Then, in this embodiment, as in the first embodiment, the threshold value Vth is set in advance in the threshold value setting section 15.
Is set. As a result, the output value detectable by the detector 11 is divided into a plurality of areas. And the detector 11
The output at 1 is converted into a signal that can be calculated through the A / D converter 13, and the comparator 16 compares it with the threshold value set by the threshold value setting unit 15. When the output value from the detector 11 is less than or equal to the threshold value, the unit amount (step) for moving the stage 12 in the Z direction via the Z drive unit 17 is set to the coarse movement amount to control the coarse movement of the stage 12. When the threshold value is exceeded, the amount of movement (step) in the Z direction via the Z drive unit 17 is changed to the fine movement amount, and the stage 12 is moved.
To control the fine movement. Furthermore, in this embodiment, in addition to the comparison between the output value via the detector 11 and the threshold value,
The drive amount of the Z drive unit 17 is set in consideration of the coarse movement amount and the fine movement amount according to the magnification obtained from the magnification sensor 19.

The waveform of the dotted line shown in FIG.
Shows the waveform when the magnification is low, and the solid line waveform shows the waveform when the magnification is high. As shown in FIG. 2, the waveform becomes steeper as the magnification becomes higher, and becomes gentler as the magnification becomes lower. That is, it can be seen that the higher the magnification of the objective lens, the finer the movement is required, and the lower the magnification of the objective lens is, the more the coarse movement is required. Therefore, in the present embodiment, as described above, the drive amount of the Z drive unit 17 is adjusted in consideration of the movement amount (step) suitable for the magnification.

The determination of the drive amount of the stage 12 based on the output of the detector 11 is performed at each scanning position on the sample 8 via the deflector 5. As a result, when the sample 8 having a step as shown in FIG. 3 is scanned by the microscope of the present embodiment, the objective lens 7 can be moved only in the regions near the height positions of the portions A and B having relatively flat surfaces. The stage 12 moves in the Z direction by the step movement of the fine movement amount suitable for the magnification, and the stage 12 is moved by the step drive of the coarse movement amount suitable for the magnification of the objective lens 7 in the region of the height position which does not contribute to the image formation of other images. Moves in the Z direction, and the moving amount corresponding to the magnification of the objective lens is also taken into consideration in the moving amount, so that the Z coordinate at the maximum output is stored more efficiently and quickly in the maximum output calculating unit 14. It is possible to obtain a three-dimensional image at higher speed and with higher accuracy. Note that, also in this embodiment,
A plurality of threshold values Vth are provided, and the coarse movement amount when the threshold value is less than or equal to the threshold value and the fine movement amount when the threshold value is exceeded are set to be different for each threshold value. Z taking into account the amount of coarse movement and the amount of fine movement according to the magnification
By setting the drive amount of the drive unit 17, it becomes possible to obtain a three-dimensional image at higher speed and with higher accuracy.

As described above, the scanning laser microscope of the present invention has the following features in addition to the features described in the claims.

(1) The movement amount setting drive means sets a threshold value for dividing the output value detectable by the detector into a plurality of regions, and the detector detects the threshold value. And a determination unit that determines whether or not the output when the output exceeds the threshold value set by the threshold value, and the result obtained by the determination unit and the magnification obtained by the objective lens magnification determination unit. 4. The scanning laser microscope according to claim 3, further comprising: a movement amount setting drive unit that sets the movement amount of the movement mechanism based on the above, and drives the movement mechanism with the set movement amount.

[0033]

As described above, according to the scanning laser microscope of the present invention, only the height portion required for image display is finely driven and the other portions are coarsely driven. It is possible to capture the data, and it is possible to perform highly accurate measurement.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a scanning laser microscope of the present invention.

FIG. 2 is a graph showing the relationship between the relative position of the objective lens and the sample and the output detected by the detector.

FIG. 3 is an explanatory diagram showing a coarse movement range and a fine movement range when scanning a sample having a step in each example of the present invention.

FIG. 4 is a schematic configuration diagram showing a second embodiment of the scanning laser microscope of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional general scanning laser microscope.

[Explanation of symbols]

1 Laser Light Source 4 Beam Splitter 5 Optical Deflector 6 Pupil Relay Lens System 7 Objective Lens 8 Sample 9 Imaging Lens 10 Pinhole 11 Detector 12 Stage 13 A / D Converter 14 Maximum Output Calculation Section 15 Threshold Setting Section 16 Comparator 17 Z drive unit 19 Magnification sensor 1 ₁ , 1 ₂ lens

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F065 AA24 AA51 AA53 DD06 FF04                       GG04 HH04 LL10 LL30 LL32                       LL46 MM02 MM03 MM11 PP12                       PP24 QQ03 QQ08 QQ24 QQ25                       QQ29 QQ31 SS02                 2H052 AA08 AB05 AC04 AC15 AC34                       AD19 AD20 AD33 AF03 AF06                       AF13 AF14 AF25

Claims (3)

[Claims] 1. A laser light source, a scanning means for scanning a sample with laser light emitted from the laser light source, and an objective lens for condensing laser light directed to the sample via the scanning means onto the sample. A detector that detects the intensity of light reflected by the sample, and image formation that forms an image of the sample based on height information of the sample when the output detected by the detector reaches a maximum output value. Means, a display device for displaying the image formed by the image forming means, a moving mechanism capable of adjusting the relative position of the sample and the objective lens, and the moving device based on the output detected by the detector. A scanning laser microscope, comprising: a moving amount setting drive means for setting a moving amount of the moving mechanism and driving the moving mechanism with the set moving amount. 2. A threshold value setting unit for setting the threshold value for dividing the output value detectable by the detector into a plurality of areas by the movement amount setting drive means, and the detector. A determination unit that determines whether the output when detected exceeds the threshold value set by the threshold value setting unit, and the movement amount of the moving mechanism according to the determination result obtained by the determination unit. 2. The scanning laser microscope according to claim 1, further comprising: a movement amount setting drive unit configured to set the movement amount and drive the movement mechanism with the set movement amount. 3. A laser light source, a scanning means for scanning the sample with the laser light emitted from the laser light source, and an objective lens for condensing the laser light directed to the sample via the scanning means onto the sample. An objective lens magnification detection unit that detects the magnification of the objective lens, a detector that detects the intensity of the light reflected by the sample, and an output of the sample when the output detected by the detector reaches the maximum output value. An image forming unit that forms an image of the sample based on height information, a display device that displays the image formed by the image forming unit, and a movable unit that can adjust the relative position of the sample and the objective lens. Mechanism, the amount of movement of the moving mechanism based on the output detected by the detector and the magnification detected by the objective lens magnification detector, and the amount of movement that drives the moving mechanism at the set amount of movement. Setting Scanning laser microscope characterized by having a drive means.