JP3388285B2 - Inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
It relates to inspection equipment for dimensional observation, such as
Suitable for detecting indices formed on the sample surface.
It relates to an inspection device. [0002] 2. Description of the Related Art A mirror surface used for manufacturing a semiconductor integrated circuit.
Surface condition of wafer, etc. (undulation, dimple, protrusion, wash
Inspection equipment to detect poor cleaning or buff damage)
Conventionally, inspection devices using schlieren optical systems have been known.
Have been. [0003] Schlieren light used in this inspection device
In the scientific system, changes in the refractive index and reflectivity due to irregularities on the sample surface
Is one of the typical optical systems that expresses the difference between light and dark. This
Optical system parallels the irradiation light from a point light source with a lens.
Into a light beam, and the parallel light beam is applied to the sample surface from its normal direction.
Illuminate, focus the reflected light with a lens, and then
Scattered light by the knife edge installed in the spatial focal plane
Some parts are cut off, and behind it
And observe the reflected image with the naked eye or a camera.
It is a thing. According to this optical system, the sample surface has irregularities.
When this occurs, light is scattered in that area.
The part hitting the if edge is cut off and reaches the observation area.
Absent. As a result, behind the knife edge, the knife
The part corresponding to the scattered light blocked by the edge is darkened,
Other parts become relatively bright. This light and dark pattern
Corresponds to the surface condition of the sample.
The surface condition of the sample can be observed from the sample. Incidentally, by the way, this Schlieren
In the optical system, all scattered light components are
If the light intensity is large, the whole
To reduce the amount of light to create a light and dark pattern
To make observations.
Light and darkness
There is a problem that turns are extremely difficult to see. On the other hand, in the Schlieren optical system,
Slightly shift the focus without setting the knife edge.
And (by focusing on the schlieren light
It is the same as when no knife edge is provided in the academic system. ),
Observe the surface condition of the sample in a place with relatively high contrast
There is also known an inspection apparatus for performing the inspection. [0007] However, these conventional techniques
The inspection apparatus has the following problems. That is, the former schlieren optical system is used.
Inspection equipment used to inspect the surface of the sample behind the knife edge
Although it is possible to create a light and dark pattern according to the condition, this light and dark pattern
Light that was not blocked by the knife edge
Contrast is still low because of many components. Ma
The area that can be observed behind the knife edge is
Part and not the entire sample surface.
In order to observe the state of the body, the sample should be taken once around the optical axis.
Must be turned over. On the other hand, as in the latter inspection device, the observation point is
When moving in the axial direction, almost no scattered light is blocked.
The contrast is extremely low, and
Although it is possible to roughly determine the area where
How much depth and height they have
There was a problem that can not be. The present invention has been made in view of the above points.
The state of the sample surface in real timeAccurate observations and equipment distribution
High degree of freedomFor the purpose of providing inspection equipment
I have. [0011] Means for Solving the Problems In order to achieve the above object,
The inspection apparatus of the inventionThe irradiation light from the point light source is converted into a parallel light flux.
To the sample surface and return from the sample surface.
Mirror that focuses reflected light, and the back of the concave mirror
Located at or near the position corresponding to the image space focal plane
To observe the surface condition of the sample
Inspection apparatus, wherein the point light source and the concave reflecting mirror
A convex sub-reflector is provided in the optical path between
The light is reflected at an angle by the reflector and guided to the concave reflector.
Optical path of the irradiation light incident on the sub-reflector,
Irradiation light emitted from the concave reflecting mirror and incident on the sample surface
Characterized in that the optical path is almost parallel to.[0012] According to the above means, the reflected light from the sample surface
Of the return light reflected in the direction opposite to the incident direction,
The position corresponding to the rear image space focal plane of the concave reflecting mirror or its position
After passing through the aperture stop located in the vicinity, in the other direction
Most of the reflected scattered light is
Throat is cut off. Therefore, behind the aperture stop,
Two-dimensional by the above-mentioned return light of the reflected light from the material surface
A bright and dark pattern is formed. This light and dark pattern
It reflects the state of sample surface irregularities, reflectance, etc.
Measure the two-dimensional state of the sample surface by measuring the light and dark patterns.
Sometimes it can be observed. In this case, focus on the sample
In addition to being able to observe along with the aperture stop, almost
Since most of them can be removed, the sharpness of the resulting light and dark patterns
Will be significantly improved. In addition, illumination from a point light source
Light that guides the emitted light to the sample surface and focuses the reflected light from here
Since a concave reflecting mirror is used as the
Compared to using torens, a relatively large radius
The area can be easily observed with low aberration and the inspection equipment
The arrangement can be inexpensive.[0013] Also,A sub-reflector is provided, and the irradiation light is
The light is reflected at an angle by the sub-reflector and guided to the concave reflector.
BecauseHalf the distance between the concave reflector and the sample surface
There is no need to place obstacles for light path deflection such as
Good light / dark pattern corresponding to the two-dimensional state of the sample surface
Can be obtained. Moreover, for concave reflectors
Light path of illumination light on the light source side and illumination of the sample side on the concave reflecting mirror
A structure in which the optical path of the emitted light is folded relatively close to each other
The inspection equipment is small, and
Distance between concave reflector and sample surface (work distance
Simply increase the distance to about the focal length of the concave reflector.
be able to.[0014] further,The irradiation incident on the sub-reflector
The optical path of light, and the surface of the sample emitted from the concave reflecting mirror
Since the optical path of the irradiation light incident on thesample
Aperture on the concave reflector side, not on the stage side where
And light sources can be arranged, making inspection equipment relatively
The stage for mounting the sample and the aperture stop
Thus, the degree of freedom in arranging devices such as light sources can be increased.[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an inspection apparatus according to the present invention will be described.Reference exampleAbout
Will be explained.[0016] Figure 1Reference exampleThe inspection equipment is shown
You. Briefly describing this device, the light below the drawing
Irradiation light emitted from the source unit 2 is reflected by a concave reflecting mirror 3 above the drawing.
After being reflected by and once converted to a parallel light flux,
The normal direction is applied to the surface 4a of the sample 4 (hereinafter referred to as the sample surface).
Irradiated from direction. The reflected light from the sample surface 4a is
The light travels in the opposite direction to the irradiation light and is reflected again by the concave reflecting mirror 3.
And the optical path on the irradiation light side by the pellicle half mirror 5
After reflecting (reflecting to the left in the drawing)
An aperture stop 6 is set inside the mirror 3 at a position corresponding to the rear image space focal plane.
The image is detected as an image by the detection device 7 which stores the data.[0017] Brief description of the operation of this device
And the presence of the aperture stop 6 in the detection device 7, the sample table
Most of the scattered light not reflected in the normal direction on the surface 4a
The sample surface is blocked behind the aperture stop 6
4a, the return light (specular reflection light) reflected in the normal direction
A clear image is formed. The light and shade of this image
The turn reflects the state of the irregularities on the sample surface 4a.
Observe the image output of the detection device 7
With this, the two-dimensional change of the minute change of the state of the sample surface 4a
The distribution can be observed. In this case, the parallel
The concave reflector 3 is used for focusing and focusing the reflected light.
So if you are using a collimating lens instead
By comparison, even if the sample surface 4a is relatively large
The whole can be easily observed with low aberration, and
The cost of the optical system portion of the inspection device can be reduced.[0018] Then, in FIG.Reference exampleInspection equipment
This will be described in detail.[0019] The light source unit 2 has a 100 W or 150 W
A log lamp 21 is used as a light source. halogen
The output of the lamp 21 is controlled by a DC power supply 22.
Have been. Light emitted from the front of the halogen lamp 21
Is a pinhole having a diameter of 2 mm by the condenser lens 24.
The light is condensed on a rule 25. From behind the halogen lamp 21
Outgoing light is also a dichroic mirror that is an elliptical reflector
After passing through the condenser lens 24,
Projected onto the pinhole 25. This pinhole 25
Is a point light source for illuminating light to illuminate the sample surface 4a.
You. Each of the pinholes 25 is located at
Turret-shaped wavelength selective filter with seed interference filter
A light source 27 for illuminating the sample surface 4a.
It is possible to appropriately change the wavelength of light. This wavelength selection
Filter 27 is used to adjust the sensitivity of the optical system of the inspection device.
The peak-to-valley of the irregularities on the sample surface 4a is small.
In this case, a region having a short wavelength is selected.[0020] Irradiation emitted behind the halogen lamp 21
Component of light that has passed through dichroic mirror 26
Is detected by the photodiode 28. Photodio
The photocurrent detected by the driver 29 of the
Is fed back as a control signal of the
It is used to keep the brightness of the lamp 21 constant.[0021] Of the irradiation light from the halogen lamp 21,
What is condensed on the pinhole 25 and passes through it is light
Pellicle with a diameter of 50 mm inclined 45 ° to the axis
After passing through the aperture mirror 5 and passing through the aperture 31,
The light enters the concave reflecting mirror 3. The concave reflecting mirror 3 includes a light source unit
2 from the pinhole 25 into a parallel light beam
The light is incident on the sample surface 4a. That is, this concave reflecting mirror
Reference numeral 3 denotes a pin light source which is a point light source at the position of the focal plane in the front image space.
It is installed so that the opening of the ruler 25 is located. Concave
The reflecting mirror 3 is a coaxial parabolic mirror having an effective diameter φ of about 1
00 mm and the focal length f is 1000 mm. Ma
The optical axis of the concave reflecting mirror 3 is slightly inclined with respect to the vertical axis.
And the light of the irradiation light incident on the concave reflecting mirror 3 from the light source unit 2
The axis forms an angle θ / 2 with respect to the optical axis of the concave reflecting mirror 3,
Irradiation light emitted from the concave reflecting mirror 3 and incident on the sample surface 4a
Also forms an angle θ / 2 with the optical axis of the concave reflecting mirror 3.
You. Therefore, the optical axis of the irradiation light incident on the concave reflecting mirror 3
And the optical axis of the irradiation light emitted from the concave reflecting mirror 3 has an angle θ
Make Note that this angle θ causes aberration, and
In some cases, the layout of the inspection equipment becomes difficult as the size increases
Therefore, it is necessary to set it in the range of 0 ° to 20 °.
In the embodiment, θ = 5 °.[0022] The plane on which the parallel light beam from the concave reflecting mirror 3 is incident
The plate-shaped sample 4 is placed on the tilt stage 33.
You. The tilt stage 33 tests the parallel light flux of the irradiation light.
The inclination of the sample 4 so that it is perpendicularly incident on the sample surface 4a.
adjust. The reflected light reflected on the sample surface 4a becomes concave again.
The beam diameter is reduced by entering the surface reflecting mirror 3. At this time,
Large scattering from the sample surface 4a by the aperture 32
The reflected light at the corner is cut. The sample 4 on which the sample 4 was placed
Between the tilt stage 33 and the light source unit 2 and the detection device 7
Is provided with a shielding plate 8 for preventing stray light.[0023] The beam diameter is reduced by being reflected by the concave reflecting mirror 3.
The reflected light enters the pellicle half mirror 5 and is directly reflected.
The light is deflected in the angular direction and is branched from the optical path of the incident light. this
In this case, the pellicle half mirror 5 is made of an extremely thin film.
Thus, the effect of the ghost light is almost negligible.[0024] Reflection deflected by pellicle half mirror 5
Light enters a camera lens 72 provided in the detection device 7.
You. This camera lens 72 is a zoom lens.
And a focal length of 10 to 100 mm (F / 1.
4) and 9.5-152mm (F / 1.8)
Can be used. Collection inside camera lens 72
An aperture stop 6 is arranged at the light position. That is,
The aperture stop 6 corresponds to the rear image space focal plane of the concave reflecting mirror 3.
It will be located at the position. Therefore, the sample table
Most of the scattered light scattered by the surface 4a
Is shut off by This aperture stop 6 has an aperture composed of 10 blades.
By moving the movable adjustment unit with the iris diaphragm, its circular shape
The diameter of the opening can be changed continuously. This
By changing the diameter of the circular opening of the
(Swell inspection, dimple inspection, scratch inspection, etc.)
A suitable light image is obtained.[0025] Light from the camera lens 72 is twice as large
Of 512 × 512 pixels through the extender lens 73
The image is projected on the CCD 74. Image signal from CCD 74
Is once converted to an electrical signal and processed by a suitable signal processor.
After processing, the monitor (shown
Are displayed one after another. Image projected on CCD 74
Is a two-dimensional light / dark pattern corresponding to the state of the sample surface 4a.
It has become.[0026] More specifically, the image projected on the CCD 74 is
The light and dark pattern of the image to be obtained is the reflected light from the sample surface 4a.
Out of the aperture stop 6
It is. That is, the light is reflected on the sample surface 4a in the normal direction.
Most of the unscattered light is blocked by the aperture stop 6.
Is returned and is reflected on the sample surface 4a in the normal direction.
Light passes through the aperture stop 6. Moreover, such a return
Projected at each position in the light-dark pattern composed of light.
The light to be emitted corresponds to each position of the sample surface 4a on a one-to-one basis.
It has become. Therefore, it is projected on the CCD 74
The light and dark pattern of the image is very small, such as irregularities on the sample surface 4a.
It reflects the change, and the image
By observing the force, a minute
Observing the two-dimensional distribution of change accurately in real time
Wear.[0027] In this case, collimation of the irradiation light and focusing of the reflected light
Use a concave reflector 3 instead of a collimator lens
Chromatic aberration like a collimator lens
Does not occur at all. Also, as in the case of a collimator lens,
Since there are no multiple refraction surfaces or unnecessary reflection surfaces in
Aberration is reduced. In addition, the collimator lens is
Processing is complicated due to the large number of elements, and generally expensive
However, reflecting mirrors are relatively inexpensive, especially for large-diameter
The cost of the optics part of the material inspection equipment effectively
be able to.[0028] FIG. 2 shows the first embodiment. Inspection equipment shown
I have. This device isReference example devicePellicle Half Mira
Sub-reflector 435, which is a hyperbolic convex mirror,
And the arrangement of the light source unit 2 and the detection device 7 is changed.
You.[0029] The sub-reflector 435 is slightly inclined from horizontal
Of the irradiation light entering the sub-reflecting mirror 435 from the light source unit 2
The optical axis forms an angle θ / 2 with the optical axis of the sub-reflector 435.
Then, the light exits the sub-reflecting mirror 435 and enters the concave reflecting mirror 3.
The optical axis of the irradiation light also has an angle θ with respect to the optical axis of the sub-reflection mirror 435.
/ 2. Therefore, the sub-reflector 435 from the light source 2
The optical axis of the irradiation light incident on the surface and the concave mirror 3
4a are parallel to the optical axis of the incident light
I have. By providing the sub-reflecting mirror 435 in this way, the concave surface
Since the light source unit 2 and the detection device 7 can be arranged on the reflecting mirror 3 side,
While keeping the optical system of the inspection device relatively small,
Not only the source unit 2 and the detection device 7, but also the tilt stage 33, etc.
The degree of freedom of arrangement can be increased. The effect of stray light
In order to prevent the occurrence of light, a shield 431 having an aperture is
2 and the detection device 7.[0030] FIG. 3 shows a second embodiment. Inspection equipment shown
I have. This device isApparatus of the first embodimentConcave reflector 3
The sub-reflector 435 is modified.[0031] Irradiation light from the light source unit 2 is a pellicle half
Sub-reflector 5 which is deflected by mirror 5 and is a hyperbolic convex mirror
It was incident on the periphery of 35 (right end in the drawing) and was reflected here
After that, it is incident on the concave reflecting mirror 503 of the off-axis parabolic mirror, and
Here, the light beam is converted into a parallel light beam and enters the sample surface 4a. This
In this case, the optical axes of the sub-reflecting mirror 535 and the concave reflecting mirror 503 are mutually
The secondary reflecting mirror 535 and the concave reflecting mirror 5
Since the aperture stop 6 is arranged on the optical axis 03,
Above, the irradiation light incident on the sample surface 4a is a perfect parallel light beam.
And the irradiation light emitted from the sample surface 4a is
It is perfectly focused at one point at the center of the aperture of the aperture stop 6. Was
However, the optical axis of the irradiation light incident on the sample surface 4a and the light source unit 2
And the optical axis of the detection device 7 is no longer strictly parallel,
Adjustment becomes difficult.[0032] FIG. For your reference,Inspection device of FIG.Light of
This shows a model of the academic system. Let the focal length of the concave reflecting mirror 503 be f
1 and the focal length of the sub-reflector 435 is f2.
Assuming that the distance between the reflecting mirrors is d, the composite focal length as a whole
f is f = f1 · f2 / (f1 + f2−d). What
The image distances of the sub-reflector 435 on the left and right in the drawing are p and p '.
In this case, the focal length f2 of this sub-reflector 435 = p.p '
/ (P-p ') and its eccentricity e = p + p' / (p-
p '), and its major radius a = (p-p') / 2
You.[0033] Here, for approximation,
Think. The radius of curvature of the concave reflecting mirror 503 is represented by r1 (-).
When the radius of curvature of the sub-reflector 435 is r2 (-),
Considering the relation f1 = r1 / 2, f2 = -r2 / 2,
The condition for obtaining a real image is (r1 -2d) .r2 / 2 (r
1−r2−2d)> 0. Here, considering r2 <0
Then,-(r1) / 2> -d>-(r1 / 2) + (r2
/ 2)-(2 / r1)> (1 / f)> 0.[0034] The present invention has been described with reference to specific examples.
However, the present invention is not limited to such an embodiment.
And various modifications are possible without changing the gist.
Needless to say, there is.[0035] In the inspection device of the above embodiment, , Pellicle her
Mirror 5 is arranged between the light source unit 2 and the concave reflecting mirror 3
As described above, the pellicle half mirror 5 is recessed.
It can be arranged between the surface reflecting mirror 3 and the sample 4. This
, The diameter of the pellicle half mirror 5 is
2, that is, if it is not larger than the diameter of sample 4,
Quality images cannot be obtained.[0036] Further, in the inspection apparatus of the above embodiment, the light source
When using the halogen lamp 21 as the light source of the unit 2
As described above, a xenon lamp was used as a light source.
It can also be used. What to use as the light source
It is determined by the properties of the inspection object (sample 4). example
If the reflectance is relatively high, such as a semiconductor wafer,
If you are testing a halogen lamp or xenon
Any of the lamps may be used,
When inspecting objects with relatively low reflectance, such as plates
Use a high-brightness xenon lamp.
No. Therefore, depending on the nature of the inspection object,
You may make it the structure which can be changed suitably.[0037] Also In the inspection apparatus of the above embodiment, the light source unit
2 when condenser lens 24 is incorporated
As described above, the configuration excluding the condenser lens 24 is adopted.
Can also be. In this case, one focus of the elliptical reflector 26 is
Halogen lamp 21 is installed at the point and focuses on the other side
A pinhole 25 is provided. As a result, the elliptical mirror
Due to the nature, the light reflected by the elliptical reflector 26 is
And a point light source is placed at this focusing point.
It becomes the same state as. The elliptical reflector 26 is replaced with
Alternatively, a parabolic reflector may be used. In this case
The light exiting the parabolic reflector travels parallel to its optical axis.
Therefore, a separate collimating lens is
The lens should focus on the pinhole 25.
Just do it.[0038] further The light source unit 2 other than the above
Do not use glass 228a, 228b
Directly from the exit end side of the fiber 229 to the concave reflecting mirror 3.
A type that emits light can also be used.[0039] Also In the inspection apparatus of the above embodiment, a point light source
The pinhole 25 was used for formation, but this was slipped.
Can also be. In this case, the irradiation light from the light source
The emission angle can be widened.[0040] Further, in the inspection apparatus of the above embodiment, the wavelength
When an interference filter is used as the selection filter 27,
As described above, the wavelength selection filter 27 is, for example, a color filter.
A glass filter can also be used. Also, wavelength selection
The filter 27 is not an essential element,
Between the pellicle half mirror 5 and the concave reflecting mirror 3
Is also good.[0041] Also In the inspection apparatus of the above embodiment, the wavelength selection
Although the case where only the selection filter 27 is used has been described,
Together with the wavelength selection filter 27 or the wavelength selection filter
Instead of the filter 27, an ND filter may be provided. N
D filter dims without changing spectral characteristics of incident light
It is used for the purpose. The dimming in this case is
This is necessary for detecting undulations on the sample surface 4a.
You. In the case of smooth surface changes such as undulations,
Since the specular reflection component of light becomes extremely large, the sample surface 4a
If the brightness of the image is too high and the light is not
This is because observation becomes too difficult. In this case, c
The logen lamp 21 may be replaced with a lamp with low luminance.
However, the work is simpler with the ND filter.[0042] Further, in the inspection apparatus of the above embodiment, the
The half mirror 5 is used.
Edge type flat beam splitter can be used.
Wear. In this case, the position between the two planes of the plate beam splitter is
A certain minute angle α is provided. This allows the flat beam split
Ghost light generated by reflection from the transmission surface of the
From the optical path of the necessary reflected light reflected by the reflective surface of
Can be prevented from being detected in the detecting device 7.
You.[0043] Also In the inspection apparatus of the above embodiment,
The diameter and the focal length of the projection mirror 3 are set to 100 mm and 100 mm.
0 mm, but is not limited to this.
Concave reflectors of various diameters and focal lengths depending on the application of the device
3 can be used. For example, large diameter (~ 1000
mm) for liquid crystal devices etc.
By correspondingly increasing the diameter of the concave reflecting mirror 3
Thus, the entire sample can be observed at once. Also concave
The focal length of the surface reflecting mirror 3 can be set arbitrarily, but in principle,
The detection performance increases as the focal length increases. In addition,
In order to maintain the inspection accuracy, the accuracy of the polished surface of the concave reflecting mirror 3 is limited.
It is desirable that the threshold is better than λ / 4. In addition,
When using a parabolic mirror with an axis,
And astigmatism, coma, etc. caused by
The aberration increases extremely when the F-number is set to 10 or more.
Need to be prevented.[0044] Further, the distance between the concave reflecting mirror 3 and the sample surface 4a is
The interval can also be set arbitrarily. However, a concave reflecting mirror
When the distance is considerably shortened within the focal length range of 3,
It is necessary to increase the angle of incidence from an oblique angle, and aberration
Causes increase. Note that, in principle, the focal point of the concave reflecting mirror 3
The longer the distance between the concave concave reflecting mirror 3 and the sample surface 4a, the more light
Although the detection performance (sensitivity) of the scientific system is improved, the optical system
There is a problem that the portion becomes large.[0045] Further, the first and second embodiments Vice used in
The focal lengths of the reflecting mirrors 435 and 535 are also arbitrary. However
The longer the combined focal length with the concave reflecting mirror 3 is,
Its detection performance (feeling
Degree) can be increased. Because this synthetic focal length
The ability to detect irregularities on the sample surface 4a increases in proportion to the size of the separation.
Because it increases. Also, from the sub-reflectors 435 and 535
It is better to collect light at a distant position.
Installation and shading are simplified.[0046] Further, a concave reflecting mirror used in the fifth embodiment
Reference numeral 503 denotes an off-axis parabolic mirror.
It can also be a coaxial parabolic mirror. At this time,
What is the optical axis of the nut-shaped parabolic mirror and the optical axis of the sub-reflector 535?
Match.[0047] Also , Pellicle half mirror 5 and aperture stop
6, a lattice filter can be provided. this
The lattice filter has a stripe lattice groove formed.
Work to diffract light. This lattice filter
Light scattered with a relatively large scattering angle
6 will be led to the opening. Achieve similar objectives
Therefore, the aperture stop 6 and the aperture stop 6
If necessary, make the CCD 74 eccentric to the optical axis.
May be.[0048] Further, in the inspection apparatus of the above embodiment, CC
It was assumed to be observed at D74.
Alternatively, an optical system for observing with the naked eye may be used. Further
Use a phototube such as a photomultiplier instead of the CCD74
May be.[0049] Also Video signal input from the CCD 74
Of the video signal (original video signal) contained in
Add the differentiated signal and the original video signal to create a new video signal
A small contrast difference by differential processing such as
Image can be displayed. In addition,
Brightness adjustment circuit that can arbitrarily set the brightness of a new video signal
Can also be provided. With this brightness adjustment, for example,
Observe the state inside the contour part such as a convex part and the contour part itself.
The video can be viewed at an easy-to-view brightness
Becomes[0050] Furthermore, in the inspection apparatus of the above embodiment,
Although an iris diaphragm or the like is used as the diaphragm 6, a fixed circular shape is used.
An aperture stop provided with an aperture is provided, and the aperture stop is
It may be used by moving it in the axial direction.
No.[0051] Also In the inspection apparatus of the above embodiment,
An aperture stop 6 is provided at a position corresponding to the focal plane.
However, its installation position is near the position corresponding to the back image space focal plane.
It may be beside.[0052] Further, in the inspection apparatus of the above embodiment, one set
Using the light source unit 2, the concave reflecting mirror 3 and the detecting device 7
A light source that constitutes the
Section, concave reflecting mirror, and detecting device
Can be achieved. Further, the local of the sample surface 4a is observed.
Measurement, etc., use a new concave reflector instead of
Small diameter and high precision collimation for collimating light and focusing reflected light
A lens can also be used. In this case, concave reflection
The position where the light from the mirror 3 is projected and the collimation
Tilt between the position where the illumination light from the lens is projected
It becomes necessary to move the stage 33. Or one set
Light source unit 2, concave reflecting mirror 3, and detecting device 7
Pair of light source, concave collimating lens and detector
It is necessary to face the tilt stage 33 as necessary.
You. [0053] According to the present invention,Providing a sub-reflector,
The irradiation light is reflected at an angle by the sub-reflecting mirror, and
Since the light is guided to the surface reflecting mirror, the concave reflecting mirror and the sample surface
An obstacle for optical path deflection such as a half mirror must be
Eliminates necessity, good for two-dimensional state of sample surface
A bright and dark pattern can be obtained. Moreover, concave reflection
Light path on the light source side for the mirror and for the concave reflecting mirror
Folds when the optical path of the irradiation light on the sample side is relatively close
The inspection system has a small size.
The distance between the concave reflecting mirror and the sample surface
Distance) to about the focal length of a concave reflector.
It can be easily lengthened. [0054] Further, the irradiation incident on the sub-reflector
The optical path of light, and the surface of the sample emitted from the concave reflecting mirror
Since the optical path of the irradiation light entering the
Aperture on the concave reflector side, not on the stage side where
And light sources can be arranged, making inspection equipment relatively
The stage for mounting the sample and the aperture stop
Thus, the degree of freedom in arranging devices such as light sources can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of an inspection apparatus of a reference example . FIG. 2 is a schematic configuration diagram of the inspection device of the first embodiment . FIG. 3 is a schematic configuration diagram of an inspection device according to a second embodiment . FIG. 4 is a diagram showing a model of an optical system of the inspection device of FIG . 3 ; [Description of Signs] 2 light source 3 concave reflecting mirror 4a sample surface 5 pellicle half mirror 6 aperture stop 7 detector

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 21/84-21/958 G02B 27/54 H01L 21/64-21/66 G01B 11/00-11 / 30

Claims (1)

(1) A concave reflector for guiding irradiation light from a point light source to a sample surface as a parallel light flux, and converging reflected light returning from the sample surface, and the concave surface thereof. An inspection device for observing a surface state of a sample, comprising: an aperture stop disposed at or near a position corresponding to a rear image space focal plane of a reflecting mirror, wherein the point light source and the concave reflecting mirror are provided. Providing a convex sub-reflector in the optical path between, and the irradiation light is reflected at an angle by the sub-reflection mirror and guided to the concave reflection mirror, and the optical path of the irradiation light incident on the sub-reflection mirror An inspection apparatus, wherein an optical path of irradiation light emitted from the concave reflecting mirror and incident on the sample surface is substantially parallel.