JP2886700B2 - Focus position detection method and device, pattern inspection device, imaging method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a focal position for detecting the amount of deviation of a sample from a focal plane of an image detection system when detecting an image of the sample. The present invention relates to a pattern inspection apparatus and the like including a focus position detection apparatus, and particularly to a focus position detection method and apparatus suitable for detecting an image of a sample having a step or a rough surface on the surface, and a pattern inspection apparatus , An imaging method and an apparatus thereof.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. Sho 62-318 discloses a method for detecting a focus position in a pattern projection system.
No. 15 is known. In this case, the focus detection pattern is projected to form an image on the focal plane of the image detection optical system, while the two image sensors are respectively located at the front position and the rear position with respect to the focal plane of the image detection optical system. It has been arranged in. When the sample surface is displaced to any one of the positions, the contrast value of the projection pattern (focus detection pattern) at that position is obtained as the maximum, so that the focus value detected by each of the two image sensors is obtained. The deviation of the measured object from the in-focus position is quantitatively detected based on the magnitude relationship between the contrast values of the detection patterns.

FIG. 12 shows the basic configuration of the focus position detecting device disclosed in the above publication. In this case,
When the glass plate 2 is illuminated by the illumination light from the light source 1, the focus detection pattern printed in advance on the glass plate 2 passes through the half mirror 3 and the objective lens 4 through the sample 5.
The sample 5 is projected upward and the sample 5 is illuminated by epi-illumination. At this time, the image plane of the focus detection pattern is formed by converting the image of the sample 5 into the objective lens 4, the half mirrors 3 and 6.
And the in-focus plane of the image detecting image sensor 13 detected through the camera. Now, the image sensors 8 and 9 for detecting the focus detection pattern projected on the sample 5 via the objective lens 4 and the half mirrors 3, 6, and 7 sandwich the image plane of the focus detection pattern. It is arranged so that the focal plane comes to a position shifted back and forth along the optical axis. That is, as shown in FIG. 13, the image sensor 8 is placed on the surface position 14 above the surface position 14 which is the focus plane of the image sensor 13 at the same time as the image formation plane of the focus detection pattern. Is arranged such that the focal plane of the image sensor 9 coincides with the surface position 16 below the focal plane. The focus detection patterns projected on the sample 5 are simultaneously detected by the image sensors 8 and 9 arranged as described above. The pattern detection output from each of the image sensors 8 and 9 is processed by the contrast calculators 81 and 91, whereby the contrast value for the focus detection pattern detected by each of the image sensors 8 and 9 is obtained. . When the sample 5 is located at the surface position 15, the output from the contrast calculator 81 becomes maximum, and as the distance from the surface position 15 increases, the contrast value gradually decreases. Similarly, when the sample 5 is located at the surface position 16, the output from the contrast calculator 91 becomes maximum, and the more the position deviates from this, the more the contrast value gradually decreases. Therefore, if the difference between these contrast values is obtained by the focus determiner 100, it is possible to know how much the sample 5 deviates from the surface position 14 based on the relative difference. The stage controller 101 only has to control the height of the stage (not shown) in the Z-axis direction (height direction) so that the sample 5 is positioned at the surface position 14 based on the amount. More specifically, FIG. 14 shows output characteristic graphs of the contrast calculators 81 and 91 (the horizontal axis represents the sample 5).
, And the vertical axis represents the outputs 811 and 911 of the contrast calculators 81 and 91). As is clear from this, the amount of deviation from the in-focus position is also apparent. Is 0, contrast calculators 81 and 91
Is zero, and when the output difference is shifted to the plus side, the output of the contrast calculator 81 is larger than the output of the contrast calculator 91 and, conversely, is shifted to the minus side. In this case, the output of the contrast calculator 81 is smaller than the output of the contrast calculator 91. Therefore, the automatic focusing can be performed by automatically controlling the height of the sample 5 so that the outputs of the contrast calculators 81 and 91 become equal.

In addition to the above publication, when the sample surface needs to be illuminated from an oblique direction, a part of the reflected light due to the oblique illumination is detected by an image sensor for focus detection. As a method for preventing the focus detection pattern from deteriorating in contrast and making autofocusing difficult, an example of an apparatus configured to use light having a wavelength different from the detection wavelength range of the image sensor for oblique illumination. Japanese Patent Application Laid-Open No. 58-120106 is known.

[0005]

However, in the case of JP-A-62-31815, no consideration is given to the case where the sample surface needs to be illuminated from an oblique direction due to a step in the sample. In the case of oblique illumination, a part of the reflected light is detected by the focus detection image sensor, which reduces the contrast of the detected focus detection pattern and makes automatic focusing difficult. There is something wrong. In addition, Japanese Unexamined Patent Publication No.
In the case of Japanese Patent Application Laid-Open No. 8-120106, a method of obliquely illuminating with light having a wavelength range different from the detection wavelength range of the focus detection image sensor has been proposed as a method for solving the above-mentioned problem. If the sample has a transmittance characteristic that transmits and absorbs light other than light in the wavelength range,
Applicable in cases where the detection wavelength range of the image sensor and the wavelength range of oblique illumination must be the same, or when the loss of light amount due to separation of wavelength ranges cannot be tolerated due to limitations on detector sensitivity etc. In such a case, such problems as not being able to be performed are caused. In such a case, every time automatic focusing is performed, oblique illumination must be cut, and much time is required for focusing.

A first object of the present invention is to provide an image detecting system focusing surface of a sample in parallel with image detection of the sample even when the sample is in an illuminated state without losing the illumination light amount. An object of the present invention is to provide a focus position detection method capable of reliably and promptly detecting the amount of deviation from the position, and positioning the sample on the focal plane of the image detection system. A second object of the present invention is to provide a focus position detecting device suitable for carrying out the focus position detecting method. A third object of the present invention is to
Even when the sample is in an illuminated state without losing the amount of illumination, the amount of deviation of the sample from the image detection system in-focus plane is reliably and promptly detected, and the sample is detected by the image detection system. And a pattern inspection apparatus that can automatically detect an image of the sample in parallel with being positioned on the focal plane, and inspect a pattern formed on the sample based on the detected image. . A fourth object of the present invention is to reliably and promptly detect the amount of deviation of a sample from an in-focus plane of the image detection system even while capturing an image of the sample, and to detect the image of the sample. An object of the present invention is to provide an imaging method and an apparatus capable of imaging an image of a sample while being positioned on a focal plane of a system.

[0007]

The first object of the present invention is basically to simultaneously project a contrast detection pattern and a light-shielding pattern on a sample and simultaneously irradiate the sample with illumination light. In parallel with the detection as an image, the images of both patterns projected on the sample are respectively detected as detection image signals, and the detection image signal by the light shielding pattern is subtracted from the detection image signal by the contrast detection pattern. As a result, a detection image signal corresponding to a contrast detection pattern that does not include the reflected light component of the sample due to the illumination light is obtained, and the shift amount from the focal point on the sample surface is detected based on the detection image signal. Is done. The second object is basically a projection means for simultaneously projecting a contrast detection pattern and a light-shielding pattern on a sample, a means for irradiating the sample with illumination light for image detection, and Detecting means for detecting the projected images of both patterns as detected image signals, and subtracting the detected image signal by the light-shielding pattern from the detected image signal by the contrast detection pattern detected by the detecting means, thereby providing illumination. Detection image signal extraction means for obtaining a detection image signal corresponding to a contrast detection pattern that does not include a reflected light component of the sample due to light; and a focal point position on the sample surface based on the detection image signal obtained from the detection image signal extraction means. A focal point detecting means for detecting a shift amount from the image, and detecting the sample as an image by the illumination light in parallel with the detection of the shift amount. It is accomplished by constructing and means. The third object is to provide a projecting means for simultaneously projecting a contrast detection pattern and a light-shielding pattern on a sample, a means for simultaneously irradiating the sample with illumination light for image detection, and both of the patterns projected on the sample. Detecting means for detecting each image of the sample as a detected image signal, and subtracting the detected image signal by the light-shielding pattern from the detected image signal by the contrast detecting pattern detected by the detecting means to reflect the sample by the illumination light. Detection image signal extraction means for obtaining a detection image signal corresponding to a contrast detection pattern containing no light component; and a shift amount from a focal point position of the sample surface based on the detection image signal obtained from the detection image signal extraction means. Focusing control means for controlling the movement of the sample surface to the focusing position after the detection, and the illumination light An image detection system for detecting an image of a circuit pattern formed on the surface of the sample, and determination means for determining a defect by comparing an image signal of the circuit pattern detected from the image detection system with a reference circuit pattern. It is achieved by doing. The fourth object is irradiated with illumination light to the sample, the sample that is the illumination and imaging through an optical system, for detecting a focus position deviation on said sample while imaging, contrast Striped putter for detection
That projecting a light pattern consisting ting the light-shielding pattern, it detects a light pattern the projection, to eliminate the influence of the illumination light from the detection signal of the optical pattern of the detected, the fringe
Detection signal of the light-shielding pattern from the detection signal of the
From the detection signal from which the influence of the illumination light has been removed to determine the amount of deviation of the surface of the sample from the focal point of the optical system, and the focal position of the sample based on the determined amount of deviation. Is achieved by compensating for the deviation from the imaging device, and as an apparatus configuration, an irradiating unit that irradiates the sample with illumination light, and an imaging unit that captures the sample irradiated with the illumination light by the irradiating unit through an optical system. means, for the illumination light to detect a focal position shift on sample irradiated, controller
Pattern projection means for projecting a light pattern consisting of a striped pattern for last detection and a light-shielding pattern , pattern detection means for detecting the light pattern projected from the pattern projection means from above the sample, and detection by the pattern detection means removing all the effects of the illumination light from the detection signal of the optical pattern
The light shielding pattern is obtained from the detection signal of the stripe pattern.
On which minus the detection signal, detection removing the influence of the illumination light
A shift amount calculating means for calculating a shift amount of the sample surface from the in-focus position of the optical system from the output signal , and a shift amount from the focus position of the sample surface based on the shift amount calculated by the shift amount calculating means. This is achieved by comprising a correcting means for correcting the deviation.

[0008]

When only a contrast detection pattern is projected on a sample in an illuminated state, an image sensor that detects the pattern uses reflected light from the contrast detection pattern projected on the sample and illumination light from the sample. The reflected light is detected at the same time. On the other hand, if the projection light is blocked by projecting the light-shielding pattern on the sample in the illuminated state, the image sensor detects only the reflected light by the illumination light from the sample. Therefore, if the detection output corresponding to the light-shielding pattern is subtracted from the detection output corresponding to the detected pattern for contrast detection, the influence of the illumination light from the sample is removed, and the contrast value is more reliably obtained than the detection output using only the contrast detection pattern. Is required. If the thus obtained contrast value is processed in the same manner as in the past, the amount of deviation of the sample from the in-focus plane of the image detection system can be reliably detected. Based on the amount of deviation from the focal plane of the image detection system, it is possible not only to make the sample coincide with the focal plane of the image detection system, but also to make the specimen coincide with the focal plane of the image detection system. The image is formed on the sample by automatically detecting the image, and further comparing the detected image with a theoretical image pattern stored in advance or an image pattern detected immediately before. The pattern can be inspected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 6. Prior to that, the principle of the present invention will be briefly described with reference to FIGS. 7 to 11, as follows. That is, FIG. 7 schematically illustrates a state in which a focus detection pattern including a stripe pattern (an example of a contrast detection pattern) 210 and a light-shielding pattern 220 is projected on the sample surface. is there. As shown in the figure, the surface condition of the sample is not uniform, and the left portion thereof is a rough surface portion 51 and the right portion thereof is a smooth surface portion 52. In the case of such a surface state, there is almost no difference in reflectance between the rough surface portion 51 and the smooth surface portion 52 with respect to the epi-illumination (projection light). The reflectance at the portion 51 is larger than that at the smooth surface portion 52.

FIG. 10 shows an image sensor output waveform b corresponding to line b shown in FIG.
Since the light-shielding pattern is projected from the position 59 to the position 61 and the projection light is blocked, only the reflected light due to the oblique illumination is detected at that portion, and the rough surface portion 5 is detected.
It can be seen that the image sensor output at the positions 59 to 60 is larger than that at the positions 60 to 61 due to the difference between the reflectance at 1 and the smooth surface portion 52 due to the oblique illumination. FIG. 9 shows the output waveform a of the image sensor corresponding to the line a shown in FIG. 7. It is apparent that reflected light due to oblique illumination and reflected light due to stripe pattern projection light are simultaneously detected. .

FIG. 8 shows the output waveform of the image sensor corresponding to the stripe pattern. From this output waveform, the contrast value C is obtained by the following equation.

That is, the contrast value C is C = (V _H −
Has become a thing obtained as the V _L) / V _H. However, a minimum value at the maximum value V _L = fringe pattern waveform at V _H = fringe pattern waveform.

If this definition is applied to the image sensor output waveform a shown in FIG. 9, the contrast value for the three stripe patterns projected on the rough surface portion 51 will be the three contrast values projected on the smooth surface portion 52. This is lower than the contrast value for the stripe pattern. That is, in the focus position detection of the pattern projection method in which the height of the sample is estimated from the contrast value, as long as the image sensor output waveform a shown in FIG. 9 is used, the height of the rough surface portion 51 and the smooth surface portion 52 is high. Although the heights are the same, the result is that the heights are different. In other words, if a focus detection pattern such as a stripe pattern is projected on the sample in a state where the sample is obliquely illuminated, the sample cannot be correctly positioned at the focal position.

However, the result obtained by subtracting the image sensor output waveform b from the image sensor output waveform a is shown in FIG. 11 as an image sensor output waveform ab. As can be seen from this, when oblique illumination is performed, However, an image sensor output waveform equivalent to that in the case where it is not performed is obtained, and the contrast value is almost uniform. Therefore, when the contrast value is obtained, by performing preprocessing such as subtracting the image sensor output corresponding to the light-shielding pattern from the image sensor output corresponding to the contrast detection pattern, the contrast value can be obtained correctly. As a result, the sample can be positioned at the correct focal position.

Now, the present invention will be described in detail with reference to FIG.
Is an automatic image detecting apparatus according to the present invention (a focus detecting apparatus according to the present invention) in which an image is continuously detected in a state where the focus is aligned when a sample is moved at a constant speed in a predetermined direction. (Including a position detecting device) in the first example. In this case, the light source 1, the half mirrors 3, 6, 7, the objective lens 4, the focus determination unit 100,
The stage control unit 101 has functions similar to those shown in FIG. The sample 50 requires oblique illumination for its image to be detected.
Is performed by a light source for oblique illumination 10 and parabolic mirrors 11 and 12. Sample 5
The image is continuously detected by the linear image sensor 130 in a state where 0 is continuously transmitted by the stage at a constant speed v (or -v) in the direction of the arrow.

More specifically, a light-shielding pattern 22 is previously formed on a glass plate 20 in addition to a contrast detection pattern 21. When light from a light source 1 is illuminated on the light-shielding pattern 22, both of them are illuminated. The pattern is projected on the sample 50 as a focus detection pattern, and the sample 50 is illuminated obliquely by the light source 10. In this example, the contrast detection pattern is a stripe pattern in which light-shielding portions and transmission portions are alternately arranged, and the light-shielding pattern is shown as a rectangular pattern. However, when these two patterns are projected on the sample 50, The projection is performed while avoiding the detection field of view of the linear image sensor 130.

The image planes of the contrast detection pattern 21 and the light shielding pattern 22 are aligned with the focal plane of the linear image sensor 130 for detecting the image of the sample 50.
A contrast detection pattern projected on the sample 50,
Each of the projection pattern detectors 80 and 90 for detecting the light-shielding pattern together has a focal plane at a position shifted forward and backward along the optical axis with the imaging plane of the focus detecting pattern interposed therebetween. It is arranged to be. In this example, the projection pattern detector 80 includes two linear image sensors 801 and 802 arranged in parallel with each other.
The projection pattern detector 90 is also constituted by linear image sensors 901 and 902 arranged similarly. The light-shielding pattern on the sample 50 is applied to the linear image sensors 801 and 901, and the contrast detection pattern on the sample 50 is applied to the linear image sensors 802 and 90.
2 are respectively formed.

Here, the projection pattern detector 8 shown in FIG.
0 and the operation of the contrast calculator 82 will be described. The linear image sensor 802 detects both the reflected light due to the projected light and the reflected light due to the oblique illumination, and the linear image sensor 801 detects the reflected light due to the oblique illumination. Only those that are detected. Therefore,
D / v or-by the delay circuits 821a and 821b.
If the output of the linear image sensor 801 is subtracted from the output of the linear image sensor 802 by the subtracter 822 with the timing shifted by d / v, the reflected light due to the oblique illumination can be offset as a result of the subtraction. . Here, d is the distance between the contrast detection pattern and the light shielding pattern on the surface of the sample 50, and d / v is the distance of the sample 5 on which the contrast detection pattern 21 was projected.
This is the time required until the light-shielding pattern 22 is projected on the same position on 0. The result of the subtraction from the subtractor 822 is processed by the contrast calculator 823 to obtain the contrast value at the position of the projection pattern detector 80. Such an operation is performed by the projection pattern detector 90.
The same applies to the contrast calculator 92.

Referring back to FIG. 1, the difference between the contrast values from the respective contrast calculators 82 and 92 can be obtained by the focus determiner 100.
From the relative difference, it is known how much the sample 50 deviates from the in-focus plane, and the amount of the deviation is known. Therefore, the stage control unit 101 moves the stage ( What is necessary is to automatically detect an image from the sample 50 while controlling the height in the Z-axis direction (height direction) (not shown). in this way,
Since the image can be continuously detected by the linear sensor while performing the automatic focusing, the image detection can be performed significantly more than in the conventional case where the oblique illumination is turned off each time and the focusing is performed in advance. It will be faster.

Next, although deviating from the content of the present invention,
Simultaneous projection of contrast detection pattern and light shielding pattern
Automatic image detection device that is not concerned, that is, relates to sequential projection
An example (including the focus position detecting device) will be described. FIG.
Every time the sample is moved stepwise in a certain direction, the image is in the case where the to be continuously detected in a state of being combined focal position, showing the configuration of the automatic image detection equipment . In this case, the light source 1, the half mirror 3,
6, 7, the objective lens 4, the focus determiner 100, and the stage controller 101 have the same functions as those shown in FIG. The sample 50 requires oblique illumination for its image to be detected. The oblique illumination for the sample 50 is the same as in the case of FIG. , 12.
The sample 50 is step-moved in a certain direction.
The image is continuously detected by the TV camera 131 every time is stopped.

More specifically, in this example, the focus detecting pattern is a display pattern, which is a transmission type liquid crystal display 2.
00, it is determined whether the contrast detection pattern or the light-shielding pattern is generated, depending on the switching state of the switch 201 by the switching circuit 202. Light from a light source 1 is transmitted through a liquid crystal display 2
When illuminated at 00, the display pattern is projected onto the sample 50, and the sample 50 is obliquely illuminated by the light source 10. When the display pattern is projected on the sample 50 while avoiding the detection field of view of the TV camera 131, it is the same as in the case of FIG. 1, and the display pattern projected on the sample 50 is detected. The positional relationship between the linear image sensors 8 and 9 is the same as that of the projection pattern detectors 80 and 90 shown in FIG.

Now, referring to FIG.
The operation of the contrast calculation unit 83 will be described. Each time the movement of the sample 50 is stopped, the switching circuit 202
The switches 201 and 830 are sequentially controlled in a predetermined manner under the control of. First, a contrast detection pattern is generated as a display pattern in the transmissive liquid crystal display 200, and the switch 830 is switched to the memory 831 side. Has become. In this state, the linear image sensor 8 detects the contrast detection pattern projected on the sample 50, and the detection output is saved in the memory 831. Next, switch 20
The display pattern on the transmissive liquid crystal display 200 is updated to a light-shielding pattern by switching 1,830 in reverse. In this state, a detection output for the light-shielding pattern projected onto the sample 50 is obtained from the linear image sensor 8, but the detection output for the contrast detection pattern is read out from the memory 831 in synchronization with this detection output. , The reflected light due to oblique illumination can be canceled as a result of the subtraction. The result of the subtraction from the subtractor 832 is the one for which the contrast value is obtained by the contrast calculator 833. Such an operation is the same for the linear image sensor 9 and the contrast calculator 93. As described above, the present embodiment is effective when a sample is sent in a stepwise manner and an image is detected by a TV camera, and a total of two linear image sensors (linear image sensors 8 and 9) are used for detecting a projection pattern. ).

In the above example, the oblique illumination is performed by a parabolic mirror, but may be performed by a ring light guide 120 as shown in FIG. 5, and in the example shown in FIG. Although the projection pattern is detected by the two linear image sensors arranged side by side, as shown in FIG. 6, the projection pattern is imaged by the TV cameras 840 and 940, and the contrast value is calculated by image processing in the contrast calculation units 84 and 94. It is also possible to ask for. Furthermore, in the above example, there is no reference to the processing on the image detected from the sample, but generally, the image detected as described above, the theoretical image pattern stored in advance, Alternatively, the pattern formed on the sample can be inspected by comparing it with the image pattern of a non-defective product actually detected. That is, the focus position detection device according to the present invention can be used not only for an automatic image detection device but also for image detection with a pattern inspection device.

[0024]

As described above, according to the first to fourth aspects, even if the sample is in an illuminated state without losing the illumination light amount, the image is detected in parallel with the image detection on the sample. A focus position detection method for reliably and promptly detecting the amount of deviation of the sample from the image detection system focal plane, and positioning the sample on the image detection system focal plane,
Further, in the case according to claims 5 to 8, a focal position detecting device suitable for carrying out the focal position detecting method further comprises:
According to the ninth and tenth aspects, even when the sample is in the illuminated state without losing the illumination light amount, the shift amount of the sample from the image detection system focal plane is reliably and promptly detected. In addition, in parallel with positioning the sample on the focal plane of the image detection system, the image of the sample is automatically detected, and the pattern formed on the sample is inspected based on the detected image. Further, in the case of the pattern inspection apparatus according to claims 11 to 12 , even if an image of the sample is being taken, the amount of deviation of the sample from the image detection system in-focus plane can be reliably and promptly determined. In addition, an imaging method and an apparatus capable of imaging an image of the sample in a state where the sample is positioned on the focal plane of the image detection system after detecting the sample are obtained.

[Brief description of the drawings]

FIG. 1 is a first embodiment of an automatic image detection device according to the present invention.
FIG. 4 is a diagram showing a configuration in the example of FIG.

FIG. 2 is a diagram for explaining an operation of a projection pattern detector and a contrast calculator shown in FIG. 1;

FIG. 3 shows contrast detection different from the present invention.
FIG. 2 is a diagram illustrating a configuration of an example of an automatic image detection device related to sequential projection of a use pattern and a light-shielding pattern .

FIG. 4 is a diagram for explaining the operation of the image sensor and the contrast calculator shown in FIG. 3;

Figure 5 shows a second automatic image detection apparatus according to the present invention
FIG. 4 is a diagram showing a configuration in the example of FIG.

FIG. 6 is a third embodiment of the automatic image detection device according to the present invention.
FIG. 4 is a diagram showing a configuration in the example of FIG.

FIG. 7 is a diagram illustrating a focus detection pattern projected on a sample as a plane, for explaining the principle of the present invention.

FIG. 8 is a diagram for explaining the definition of a contrast value.

FIG. 9 is a diagram illustrating an output waveform of an image sensor with respect to a contrast detection pattern including an oblique illumination light reflection component.

FIG. 10 is a diagram illustrating an output waveform of an image sensor with respect to a light-shielding pattern including a reflection component of oblique illumination light.

11 is a diagram illustrating an image sensor output waveform when the image sensor output illustrated in FIG. 10 is subtracted from the image sensor output illustrated in FIG. 9;

FIG. 12 is a diagram illustrating a basic configuration of a focus position detecting device according to the related art.

FIG. 13 is a diagram for explaining the principle of automatic focusing according to the related art.

FIG. 14 is a diagram for explaining the principle of automatic focusing according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 3, 6, 7 ... Half mirror, 4 ... Objective lens, 20 ... Glass plate, 8, 9, 130, 801, 8
02,901,902 ... linear image sensor, 10
..Light sources for oblique illumination, 11, 12: parabolic mirrors, 21: contrast detection patterns, 22: light shielding patterns, 5
0: sample, 80, 90: projection pattern detector, 100
... Focusing determiner 101, Stage controller 82, 9
2, 83, 93, 84, 94 ... contrast calculator,
200: transmissive liquid crystal display, 202: switching circuit, 20
1,830 ... switch, 131,840,940 ... T
V camera, 120… Ring light guide

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-100304 (JP, A) JP-A-63-100311 (JP, A) JP-A-2-293606 (JP, A) JP-A-62-100 31815 (JP, A) JP-A-1-169344 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30

Claims (12)

(57) [Claims] 1. A method for simultaneously projecting a contrast detection pattern and a light-shielding pattern onto a sample and simultaneously irradiating the sample with illumination light. By detecting the image of the pattern as a detection image signal and subtracting the detection image signal by the light-shielding pattern from the detection image signal by the contrast detection pattern, a contrast detection signal that does not include the reflected light component of the sample due to the illumination light. A focus position detection method, wherein a detection image signal corresponding to a pattern is obtained, and a shift amount from a focus position on a sample surface is detected based on the detection image signal. 2. A method for simultaneously projecting a contrast detection pattern and a light-shielding pattern onto a relatively moving sample and simultaneously irradiating the sample with illumination light. By detecting the images of both patterns projected on the respective detection image signals, and subtracting the detection image signal by the light-shielding pattern from the detection image signal by the contrast detection pattern, the reflected light component of the sample due to the illumination light is subtracted. A focus position detecting method, wherein a detected image signal corresponding to a contrast detection pattern not included is obtained, and a shift amount from a focused position on a sample surface is detected based on the detected image signal. 3. A method for simultaneously projecting a contrast detection pattern and a light-shielding pattern onto the same position on a relatively moving sample and simultaneously irradiating illumination light with the contrast detection pattern and detecting the sample as an image of the sample using the illumination light. , The images of both patterns projected on the sample are respectively detected as detection image signals,
From the detection image signal by the contrast detection pattern, by subtracting the detection image signal by the light-shielding pattern, to obtain a detection image signal corresponding to the contrast detection pattern that does not include the reflected light component of the sample by the illumination light,
A focus position detecting method, wherein a shift amount from a focal point position on a sample surface is detected based on the detected image signal. 4. The focus position detecting method according to claim 1, wherein at least dark field illumination is performed on the sample. 5. A projection means for simultaneously projecting a contrast detection pattern and a light shielding pattern on a sample, a means for simultaneously irradiating the sample with illumination light for image detection, and an image of both patterns projected on the sample. And a detection light signal of the sample due to the illumination light by subtracting the detection image signal of the light shielding pattern from the detection image signal of the contrast detection pattern detected by the detection means. Detection image signal extraction means for obtaining a detection image signal corresponding to a contrast detection pattern which does not include a pattern, and detecting a shift amount of the sample surface from the focal point based on the detection image signal obtained from the detection image signal extraction means. Focus detection means and means for detecting the sample as an image using illumination light in parallel with the detection of the above-mentioned shift amount are provided. And a focus position detecting device. 6. A moving means for relatively moving a sample,
Projecting means for simultaneously projecting a contrast detection pattern and a light-shielding pattern on a sample moved by the moving means, means for simultaneously irradiating the sample with illumination light for image detection, and a method for projecting the two patterns projected on the sample. Detecting means for detecting each image as a detected image signal, and subtracting the detected image signal by the light-shielding pattern from the detected image signal by the contrast detection pattern detected by the detecting means, so that the reflected light of the sample by the illumination light is obtained. Detection image signal extraction means for obtaining a detection image signal corresponding to a contrast detection pattern containing no component, and detecting a shift amount of the sample surface from the in-focus position based on the detection image signal obtained from the detection image signal extraction means A means for detecting a sample as an image with illumination light in parallel with the detection of the amount of deviation. Focal position detecting device characterized by comprising and. 7. A moving means for relatively moving a sample,
Projection means for simultaneously projecting a contrast detection pattern and a light-shielding pattern on the same position on the sample moved by the movement means, means for simultaneously irradiating the sample with illumination light for image detection, and projection on the sample. Detecting means for detecting the images of both patterns as detected image signals, and subtracting the detected image signal by the light-shielding pattern from the detected image signal by the contrast detection pattern detected by the detecting means, thereby obtaining a sample by illumination light. Detection image signal extraction means for obtaining a detection image signal corresponding to a contrast detection pattern which does not include the reflected light component, and a deviation of the sample surface from the in-focus position based on the detection image signal obtained from the detection image signal extraction means Focus point detection means for detecting the amount, and in parallel with the detection of the above-mentioned shift amount, the sample is imaged by the illumination light. Focal position detecting device characterized by comprising a means for output. 8. The focus position detecting device according to claim 5, further comprising an illumination unit for performing at least dark field illumination on the sample. 9. A projection means for simultaneously projecting a contrast detection pattern and a light-shielding pattern on a sample, a means for simultaneously irradiating the sample with illumination light for image detection, and images of both patterns projected on the sample. And a detection light signal of the sample due to the illumination light by subtracting the detection image signal of the light shielding pattern from the detection image signal of the contrast detection pattern detected by the detection means. Detection image signal extraction means for obtaining a detection image signal corresponding to a contrast detection pattern that does not include the detection image signal, and a shift amount of the sample surface from the in-focus position is detected based on the detection image signal obtained from the detection image signal extraction means. In addition, focusing control means for controlling the movement of the sample surface to the focusing position, and a test using illumination light in parallel with the detection of the above-mentioned shift amount. An image detection system that detects an image of a circuit pattern formed on the surface of the material, and a determination unit that determines a defect by comparing an image signal of the circuit pattern detected from the image detection system with a reference circuit pattern. A pattern inspection apparatus, characterized in that: 10. The pattern inspection apparatus according to claim 9, further comprising an illumination unit for performing at least dark field illumination on the sample. 11. A method for imaging a sample while correcting a focal position shift on the surface of the sample, the method comprising: irradiating the sample with illumination light; imaging the illuminated sample via an optical system; A contrast detection stripe pattern and a light shielding pattern for detecting a focal position shift on the sample when performing
Projecting a light pattern consisting of the light and light, detecting the projected light pattern, and removing the influence of the illumination light from a detection signal of the detected light pattern.
Subtracting the detection signal of the light shielding pattern from the detection signal
The amount of deviation from the in-focus position of the optical system on the sample surface is determined from the detection signal from which the influence of the illumination light has been removed, and the amount of deviation from the in-focus position of the sample is determined based on the obtained amount of deviation. An imaging method characterized by correcting. 12. An apparatus for capturing an image of a sample while correcting a focal position shift on the surface of the sample, comprising: irradiating means for irradiating the sample with illumination light; and optically irradiating the sample irradiated with the illumination light by the irradiation means. Imaging means for imaging through a system; and a contrast detection stripe pattern and a light shielding pattern for detecting a focal position shift on the sample irradiated with the illumination light.
A pattern projecting means for projecting a light pattern consisting of the pattern and the pattern detecting means for the light pattern projected from the projection means for detecting from the sample, the illumination light from the detection signal of the detected light pattern by said pattern detecting means In order to remove the effect of the above, the shielding signal is used to detect
After subtracting the light pattern detection signal, the effect of the illumination light
A shift amount calculating means for calculating a shift amount of the sample surface from the in-focus position of the optical system from the removed detection signal ; and a focus position of the sample surface based on the shift amount calculated by the shift amount calculating means. An image pickup apparatus comprising: a correction unit configured to correct a deviation from the position.