JP2002090633A - Microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize rapid inspection by eliminating troublesome works of aligning a sample in observation field by correcting the position of the sample in the observation field, at switching of observation magnification. SOLUTION: A command for performing the correcting operation of a motor- driven stage 21 according to a correction value, corresponding to the deviation of the mutual attaching positions of respective objective lenses 3 and a revolver 2, is issued to a stage controller 51, and the deviation of the observation field from the sample 29 at switching of the objective lenses 3 is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope having a function of correcting a shift of an observation visual field with respect to a specimen.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, for example, defects such as scratches, dirt, dust and unevenness on a semiconductor wafer surface are inspected. In this inspection, the observation magnification was changed from low magnification to high magnification, for example, from 5 to 250
The surface of the semiconductor wafer is observed at twice the magnification. The switching of the objective lens is performed by rotating a revolver on which the objective lens is mounted.

[0003]

However, the optical eccentricity (optical axis deviation) error inherent to each objective lens, the lowering of the mounting screw of each objective lens and the mounting screw of each objective lens in the revolver. There is mechanical eccentricity error due to accuracy. Due to these eccentric errors, when the revolver is rotated and the objective lens is switched to change the observation magnification, the position of the sample image in the observation field of view of the microscope shifts.

[0004] For this reason, the position of the sample image is shifted in the observation visual field each time the objective lens is switched, and the observer moves the stage on which the sample is mounted in the XY directions each time to change the sample image in the observation visual field. Need to be aligned.
In this case, the stage is changed to X each time the objective lens is switched.
The operation of moving the sample in the observation visual field by moving in the Y direction is cumbersome, and even if the specimen is positioned in the observation visual field at a low magnification, the position of the sample in the observation visual field is changed when switching to high magnification. It shifts. As the magnification increases, the displacement of the sample image due to the eccentricity becomes more conspicuous, and in severe cases, the sample comes out of the observation field of view, and the operation of aligning the sample image within the observation field becomes very troublesome.

Therefore, the present invention is troublesome in that the position of the sample image in the observation visual field when the observation magnification is changed is automatically corrected so as to always be the same position, and the sample image is positioned in the observation visual field. It is an object of the present invention to provide a microscope which can eliminate a task and realize a quick inspection.

[0006]

According to a first aspect of the present invention, there is provided a microscope for changing an observation magnification of a specimen mounted on a stage by switching the objective lens by a revolver equipped with a plurality of objective lenses. An observation field of view that corrects the stage according to a correction value for an optical axis shift amount when the plurality of objective lenses are mounted on the revolver, and corrects a shift of an observation field with respect to the sample when the objective lens is switched. A microscope comprising a correction unit.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a microscope. A revolver 2 is arranged on the microscope main body 1 so as to correspond to the electric stage 21. This revolver 2 is equipped with five objective lenses 3 as shown in FIG. These objective lenses 3
(# 1 to # 5) are for visible light. The objective lens 3 (# 1) has a 10 × observation magnification and the objective lens 3
(# 2) is a 20 × observation magnification, the objective lens 3 (# 3) is a 50 × observation magnification, the objective lens 3 (# 4) is a 100 × observation magnification, and the objective lens 3 (# 5) is a 250 × observation magnification. The observation magnification is used.

Further, revolver 2, it becomes rotatable, by rotation of the motor M ₁ so that is switched selectively the desired objective lens 3 on the optical axis 4. further,
In the vicinity of the revolver 2, the sensor S ₁ is arranged, so as to recognize the objective type from each hole position for mounting each objective lens of the revolver 2.

The electric stage 21 mounts the sample 29 and is horizontally movable in the X and Y directions so that the observation center position of the sample 29 can be adjusted with respect to the optical axis of the objective lens 3. . The electric stage 21, by the motor M ₂ have enabled vertically driven, and is also to be able to adjust the focus position of the specimen 29 on the motorized stage 21.

The motors M ₁ and M ₂ are connected to a control circuit 23
Is driven by a driving circuit 22 which command is given of, also, the signal corresponding to the recognition result of the sensor S _1, the control circuit 2
3 is fed back.

An operation unit 24 is connected to the control circuit 23. The operation unit 24 controls each of the objective lenses 3 (# 1 to #
5) an objective selection switch 31-35 corresponding to 5), an encoder dial 36 for outputting a pulse for moving the electric stage 21 up and down in accordance with a rotation operation, and a stage operation trackball for moving the electric stage 21 in the XY directions. 101.

The visible light optical system in the microscope body 1 reflects light from the illumination light source 5 for visible observation on the half mirror 25 via the illumination system lens 6 and irradiates the sample 29 via the objective lens 3. The reflected light from the sample 29 is enlarged by the objective lens 3, transmitted through the half mirror 25, and formed into an enlarged image at the image position 9 via the dichroic mirror 26 and the imaging lens 7. It is configured so that it can be visually observed. In this case, a light shielding member 10 is disposed on the front surface of the illumination light source 5.
And so as to open when the visible observing light from the illumination light source 5 is driven by a motor M ₃ are. The motor _{M 3} is,
It is driven by a drive circuit 22 to which a command from a control circuit 23 is given. The supply voltage of the illumination light source 5 is adjusted via the control circuit 23 by operating the light control dial 101 of the operation unit 24, and the light is controlled.

The control circuit 23 includes, for example, a focus position by the objective lens 3 of 250 ×, which is the highest observation magnification, and 100
The storage means 23a has a storage means 23a for setting the difference between the in-focus positions of the × objective lenses 3 as a parallax correction value, and is stored in the storage means 23a when switching from the 100 × visible light objective lens 3 to the 250 × objective lens 3. It has a focus correction function for correcting the focus position by the objective lens 3 based on the set focus correction value.

On the other hand, a computer 53 is provided for controlling the microscope main body 1. The computer 53 is connected to a monitor 54 and a stage controller 51. The stage controller 51 has a function to drive the motor M ₂ of the motorized stage 21 receives a command outputted from the computer 53 to control the movement of the motorized stage 21.

The computer 53 has a cable 5
The control circuit 23 is connected to the control circuit 23 via the control circuit 5. in this case,
The control circuit 23 has a built-in interface circuit for the computer 53. This interface circuit is a general one, such as RS232C or GPIB. When the control circuit 23 receives a “log-in” signal from the computer 53 via the cable 55, the control circuit 23 does not accept an input from the operation unit 24 (mask processing). 23 are controlled, and the motors M _{1 to} M ₄
Is operated. At this time, switching and interlocking of various optical elements by the control circuit 23 are equivalent to signals from the operation unit 24.

FIG. 3 is a diagram showing the structure of the software 56 in the computer 53. This computer 53
Has a correction value setting file 61, and has functions of a resource management unit 62, a correction value control unit 63, and a microscope control unit 64 by executing software 56.

The resource management unit 62 includes an image input by an instruction from the microscope control unit 64, that is, an imaging device (television camera, CCD camera, or the like) (not shown) connected to the imaging lens 7 of the visible light optical system. ) To determine whether to display the image from
It has a function of displaying the image on the monitor 54 in accordance with the result of this determination.

The control circuit 23 and the control panel 66 of the monitor 54 are connected to the microscope control unit 64. The control panel 66 displays an operation image or the like for operating the microscope on the monitor 54 in accordance with an instruction from the microscope control unit 64, and sends an operation command to the microscope control unit 64 by clicking a button on the display screen with a mouse. It has a function of outputting to the control circuit 23 via the control circuit 23.

The correction value control unit 63 and the correction value setting file 61 store the electric stage 21 in accordance with the correction value corresponding to each objective lens 3 due to optical eccentricity or mechanical eccentricity of each objective lens 3 and revolver 2. Is issued to the stage controller 51 to correct the shift of the observation visual field from the sample image when the objective lens 3 is switched.

This correction value is a correction amount corresponding to each objective lens based on the processing accuracy of the mounting hole of the revolver 2 and the mounting screw of each objective lens 3 and the eccentric amount of the objective lens 3 at the click position of the revolver. .

The correction value control unit 63 displays a correction value input screen 65 for inputting a correction value on the monitor 54, and an inspector or a service person of a shipping inspection switches each objective lens, and, for example, switches the maximum magnification. Using the center of the field of view of the high-magnification objective lens having a large reference point as a reference point, a correction value is obtained from this reference point based on the amount of displacement of the center of the field of view of each objective lens. Has a function of inputting a correction value and storing it in the correction value setting file 61.

Accordingly, in the correction value setting file 61, each correction amount corresponding to each objective lens 3 attached to the mounting hole position of the revolver 2 is stored in the computer 53, and the correction value control unit 63 Value setting file 61
, A correction value corresponding to the objective lens 3 selectively inserted into the optical path is read out, and the motorized stage 21 is read in accordance with the correction value.
Is issued to the stage controller 51.

Next, the operation of the microscope configured as described above will be described.

When setting a correction value, the correction value control unit 63
Display a correction value input screen 65 for inputting a correction value on the monitor 54. In this state, an inspector (serviceman) inputs a correction value by clicking a button on the correction value input screen 65 with a mouse or operating a keyboard, and stores the input correction value in the correction value setting file 61.

At the time of inputting the correction value, first, the examiner operates the objective selection switch 35 of the operation unit 24 to operate the objective lens 3 having the highest magnification (for example, 250 ×).
Are located on the optical axis 4. Then, in this state, sample 2
9 to adjust the focusing position, and further operate the stage operation trackball 101 of the operation unit 24 to operate the electric stage 2.
1 is moved in the X and Y directions to determine the observation position (reference point) on the specimen 29.

At this time, the light from the illumination light source 5 is reflected by the half mirror 25 via the illumination system lens 6 and irradiates the sample 29 via the high magnification objective lens (250 ×) 3.
The reflected light from the sample 29 is enlarged by the objective lens 3,
The dichroic mirror 2 is transmitted through the half mirror 25
6. An enlarged image is formed at the image position 9 via the imaging lens 7 and is visually observed by the binocular unit 8 of the lens barrel. Sample 2 at this time
The electric stage 21 is moved in the X and Y directions by operating the trackball 101 so that the center of the image serving as the reference point on 9 is positioned substantially at the center (index) of the observation field.

Thereafter, the other objective selection switches 34, 3
3, 32, 31 are operated to selectively switch the objective lens 3 from high magnification to low magnification. For example, the center of the field of view of the 100 × objective lens (# 4) 3 and the reference point on the specimen 29 Is calculated. As a method of obtaining the shift amount, the shift amount is obtained from the coordinate data obtained by clicking the center of the visual field on the screen displayed on the monitor 54 and the reference point with the mouse. As another method, the electric stage 21 is moved so that the reference point is set at the center of the visual field, and the shift amount is obtained from the moving amount of the electric stage at this time.

As described above, the amount of deviation obtained by switching each objective lens 3 is interpolated according to the magnification, and this is displayed as a correction value on a correction value input screen 65 as a correction value, and is stored in the correction value setting file 61.

Next, a case where the user observes with a microscope will be described. First, in order to observe the specimen to be inspected at a low magnification, the objective selection switch 31 of the operation unit 24 is operated.
When the 10 × objective lens 3 (# 1) is selected, the motor M
1 is driven and automatically switched to the objective lens 3 (# 1). Observation is performed by aligning the center of the sample image with the center of the visual field of the objective lens 3 (# 1). In order to further magnify and observe this observation image, for example, a 50 × objective lens 3 (#
When switching to 3), the objective lens 3 selected immediately before
The objective lens 3 (#) switched with the correction value of (# 1)
The correction value of 3) is read from the correction value setting file 61 by the correction value control unit 63, and the shift amount (correction value) of the center of the visual field between the two objective lenses is obtained from the difference between the two correction values. A command to correct the electric stage 21 is issued to the stage controller 51.

[0031] The stage controller 51 drives the motor _{M 2} of the electric stage 21 in response to a command generated from the correction value controller 63 (computer 53), controls to move the electric stage 21. The movement of the electric stage 21 corrects the mutual field center shift amount between the objective lens 3 selected immediately before and the objective lens 3 selected this time. Similarly, the other objective lenses 3 (# 2, # 3, # 4, #
When 5) is switched, the correction value corresponding to the selected objective lens 3 is read out from the correction value setting file 61, and the shift amount between the center of the visual field is obtained from both correction values.
The electric stage 21 is moved, and the visual field is corrected.

For example, FIG. 4A shows an image of the sample 29 in the observation field of view by the objective lens 3 having an observation magnification of 10 ×. When switching from the 10 × objective lens 3 to the observation magnification of 50 × objective lens 3, the position of the image of the sample 29 shown by the dotted line is shifted as shown in FIG. In operation, the image of the specimen 29 comes to be located substantially at the center in the observation visual field.

As described above, in one embodiment,
A command to correct the electric stage 21 is issued to the stage controller 51 in accordance with a correction value corresponding to the mutual shift amount of each objective lens 3 so as to correct the shift of the observation visual field with respect to the sample 29 when the objective lens 3 is switched. Therefore, even if the revolver 2 is rotated and the objective lens 3 is switched to change the observation magnification, the specimen 29 in the observation field of view of the microscope is changed.
The position of the image is not shifted. For example, even if the sample 29 is positioned in the observation visual field at a low magnification and the magnification is switched to a high magnification, the center of the visual field is located at the center of the specimen image first observed by moving the stage. The motorized stage 21 can be automatically moved so that
An image of the specimen 29 does not appear in the observation field of view at a high magnification, and it is not necessary to perform an operation of aligning the image of the specimen 29 in the observation field of view, and a quick inspection can be realized.

It should be noted that the present invention is not limited to the above-described embodiment, and that various modifications can be made in the implementation stage without departing from the scope of the invention.

Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some components are deleted from all the components shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the problem described in the column of the effect of the invention can be solved. In the case where a certain effect can be obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.

For example, in the above embodiment, the specimen 29
Has been described when applied to a microscope that observes
The present invention is not limited to this, and may be applied to a microscope used for a substrate inspection apparatus that inspects a substrate such as a semiconductor wafer or a liquid crystal display.

[0037]

As described above in detail, according to the present invention, the troublesome work of correcting the position of the sample in the observation field when the observation magnification is switched is eliminated, A microscope capable of realizing a quick inspection can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a microscope according to the present invention.

FIG. 2 is a diagram showing an arrangement of an objective lens mounted on a revolver in one embodiment of the microscope according to the present invention.

FIG. 3 is a diagram showing a software structure of a computer in the embodiment of the microscope according to the present invention.

FIG. 4 is a diagram showing a correction operation by a motorized stage in one embodiment of the microscope according to the present invention.

[Explanation of symbols]

1: microscope main body 2: revolver 3: objective lens 5: illumination light source 6: illumination system lens 7: imaging lens 8: lens barrel binocular unit 10: light shielding member 21: electric stage 22: drive circuit 23: control circuit 24: operation Unit 25: Half mirror 26: Dichroic mirror 29: Sample 31-35: Objective selection switch 36: Encoder dial 51: Stage controller 53: Computer 54: Monitor 55: Cable 61: Correction value setting file 62: Resource management unit 63: Correction value control unit 64: the microscope control unit 65: correction value input screen 66: control panel _{M 1, M 2, M 3} : motor S _1: sensor

Claims (1)

[Claims] 1. A microscope in which the objective lens is switched by a revolver equipped with a plurality of objective lenses to change an observation magnification of a specimen mounted on a stage, wherein the plurality of objective lenses are mounted on the revolver, respectively. A microscope that corrects the stage in accordance with a correction value for the optical axis shift amount at that time, and corrects a shift of an observation field with respect to the sample when the objective lens is switched.