JP2001059712A - Method and apparatus for detecting stereoscopic shape as well as confocal detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting a stereoscopic shape capable of accurately detecting the shape of a ruggedness of a surface of an object to be detected formed with a transparent surface or a height of a protrusion or the like as well as a confocal detector. SOLUTION: The apparatus for detecting a stereoscopic shape comprises a zonal illumination infinitesimal spot irradiating optical system 2 for irradiating a detecting position on an object 3 to be detected with one or more spot illumination lights formed of a zonal or pseudo-zonal illumination light through an objective 27, a confocal detecting optical system 4 having a photoelectric conversion means 44 for detecting a confocal by passing a reflected light of the spot light emitted to a detecting position by the system 2 through the objective 27, and a signal processing circuit 5 for detecting the shape at the detecting position on the object 3 based on an intensity of the signal obtained by the means 44 of the confocal detecting optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object to be detected having irregularities or projections on its surface, and more particularly, to a three-dimensional shape which is the height of irregularities or projections on the surface of an object to be detected having a transparent surface. TECHNICAL FIELD The present invention relates to a three-dimensional shape detection method and device capable of detecting an object with high accuracy and a confocal detection device.

[0002]

2. Description of the Related Art As a method of detecting the surface shape of an object having an uneven surface, confocal microscopy has been conventionally known. This conventional method is as follows. That is, a minute spot is irradiated on the surface of the object by the microscope objective lens. When the projected spot becomes smallest on the object, the reflected light is detected again at a position where the smallest spot is imaged by the microscope objective lens through a small aperture having substantially the same diameter as the imaged spot image. With such a configuration, when the projection spot spreads on the object surface instead of being minimized, that is, when defocused, the amount of light passing through the minute aperture decreases. Therefore, when the light amount is detected by the detector placed behind the minute aperture, the detection value becomes maximum when the minimum spot is formed on the object, so that the surface height can be detected.

[0003]

When detecting the height of the surface of a transparent object and the object having a multilayer structure of a transparent substance by the above-mentioned conventional confocal detection method, particularly, the uppermost surface of the object is transparent. If the reflectivity of the lower layer surface is higher than the reflection from the uppermost surface, the amount of reflected light from the lower layer surface becomes large, making it difficult to accurately detect the surface, and the detection accuracy is deteriorated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art by detecting, with high accuracy, a three-dimensional shape which is the height of irregularities or protrusions on the surface of an object to be detected having a transparent surface. And a confocal detection device. Further, another object of the present invention is to provide a three-dimensional shape capable of detecting a three-dimensional shape, which is the height of irregularities or protrusions on the surface of a detection target having a transparent surface, with high accuracy and high speed. An object of the present invention is to provide a detection method, a device therefor, and a confocal detection device.

Still another object of the present invention is to provide a method for forming a pattern formed on a film transparent to light formed on the surface of an object to be detected, a foreign matter or a flaw formed on the transparent film, or the like. An object of the present invention is to provide a confocal detection device capable of inspecting a defect with high accuracy.

[0006]

In order to achieve the above-mentioned object, the present invention provides a method for detecting a spot on a detected object by using at least one spot illumination formed by illumination light of a ring or a pseudo-ring. Irradiating light, and detecting the three-dimensional shape of the object to be detected based on the intensity of a signal obtained by confocal detection of reflected light of the spot illumination light applied to the detection point. It is a detection method. In addition, the present invention irradiates each of a plurality of detection locations on an object to be detected with a plurality of spot illumination lights formed by illumination light of an annular zone or a pseudo annular zone, and irradiates each of the detection locations. A three-dimensional shape detection method characterized by detecting three-dimensional shapes of a plurality of detection points of an object to be detected based on signal intensities obtained by confocal detection of reflected light of each spot illumination light. . Further, the present invention is characterized in that the ratio of the inner ring diameter to the outer ring diameter of the ring in the illumination light of the ring in the three-dimensional shape detection method is 0.1 or more and 0.9 or less.

Further, according to the present invention, in the three-dimensional shape detection method, the object to be detected or the spot illumination light is relatively moved in an optical axis direction of the spot illumination light, and the reflected light corresponding to the movement is reflected. Is detected by confocal detection. Further, in the three-dimensional shape detection method, the three-dimensional shape may be detected by interpolating and obtaining a maximum position data using the intensities of a plurality of confocal detection signals obtained according to the motion. Features.

The present invention also provides the method for detecting a three-dimensional shape, wherein the focus position at which the diameter of the spot illumination light is minimized as the movement is changed in a vertical direction above and below the surface of the detection target. Is selected as the three-dimensional shape candidate of the surface of the object to be detected, from among those whose intensities of the confocal detection signals corresponding to the above are equal to or greater than a desired threshold value. Further, in the present invention, in the three-dimensional shape detection method, the detection target or the spot irradiation light may be moved in a direction substantially perpendicular to an irradiation optical axis to detect a wide range of three-dimensional shape from the detection target. It is characterized by. Further, in the three-dimensional shape detection method according to the present invention, a plurality of the spot illumination light may be at least one.
The three-dimensional shape of the detection target object is formed by dimensionally arranging the plurality of spot illumination lights and the detection target object relative to each other in a direction intersecting the arrangement direction of the spot illumination light. It is characterized in that a two-dimensional distribution is obtained.

Further, the present invention provides an orbicular illumination minute spot for irradiating, through an objective lens, at least one spot illumination light formed by an orbicular or pseudo-arbicular illumination light to a detection point on an object to be detected. An irradiating optical system, and a confocal detection optical system having photoelectric conversion means for performing confocal detection of reflected light of the spot illumination light applied to the detection location by the orbicular zone illumination minute spot irradiating optical system through the objective lens. And a signal processing circuit for processing a signal obtained by a photoelectric conversion unit of the confocal detection optical system. Further, the present invention provides an annular illumination microscopic device that irradiates each of a plurality of spots formed by illumination light of an annular zone or a pseudo annular zone to each of a plurality of detection locations on an object to be detected through an objective lens. Confocal detection having a spot irradiation optical system and a plurality of photoelectric conversion means for performing confocal detection of reflected light of each spot illumination light applied to each of the detection points by the annular illumination minute spot irradiation optical system through the objective lens. A confocal detection device comprising: an optical system; and a signal processing circuit that processes a signal obtained by each of a plurality of photoelectric conversion units of the confocal detection optical system.

Further, according to the present invention, in the confocal detection optical system of the confocal detection device, an optical system for limiting only light within the minimum spot diameter to a position where an image of a minimum diameter spot formed by an objective lens or the like is formed. It is characterized by installing and configuring elements. Further, the present invention is characterized in that, in the orbicular zone illumination minute spot irradiating optical system in the confocal detection device, the ratio of the inner ring diameter to the outer ring diameter of the orb is set to 0.1 or more and 0.9 or less. . Further, the present invention provides an orbicular illumination minute spot irradiating optical system for irradiating, through an objective lens, one or more spot illumination lights formed by illumination light of an orbicular zone or a pseudo-orbicular zone to a detection location on an object to be detected. A confocal detection optical system having photoelectric conversion means for performing confocal detection of reflected light of spot illumination light applied to the detection location by the orbicular zone illumination minute spot irradiation optical system through the objective lens; A signal processing circuit for detecting a three-dimensional shape at a detection position on the detection target based on the intensity of a signal obtained by a photoelectric conversion unit of an optical system.

Further, according to the present invention, there is provided a wheel for irradiating each of a plurality of spots on a detection target object with a plurality of spot illuminating lights formed by illuminating light of an annular zone or a pseudo annular zone through an objective lens. Band illumination micro spot irradiation optical system,
A confocal detection optical system having a plurality of photoelectric conversion means for performing confocal detection of reflected light of each spot illumination light applied to each of the detection points by the annular illumination minute spot irradiation optical system through the objective lens; A signal processing circuit for detecting a three-dimensional shape at each of a plurality of detection points on the detection target object based on signal intensities obtained by each of the plurality of photoelectric conversion units of the focus detection optical system. Is a three-dimensional shape detection device. Further, according to the present invention, in the three-dimensional shape detecting device, the object to be detected or the spot illumination light is relatively moved in an optical axis direction of the spot illumination light, and a plurality of common light sources corresponding to the amount of movement are provided. A movement control unit for detecting a focus detection signal from a photoelectric conversion unit of the confocal detection optical system is provided. Further, the present invention is characterized in that the three-dimensional shape detection device further comprises an objective lens moving means for moving an objective lens so as to move the spot illumination light in the optical axis direction of the spot illumination light. . Further, in the signal processing circuit of the three-dimensional shape detection device, the present invention interpolates the maximum position data using the intensities of a plurality of confocal detection signals obtained from the confocal detection optical system according to the amount of movement. The three-dimensional shape is detected by calculating the three-dimensional shape.

Further, the present invention provides the three-dimensional shape detecting apparatus, further comprising: changing the focus position where the diameter of the spot illumination light is minimized in a vertical direction on the surface of the detection target object. Movement control for relatively moving an object or the spot illumination light in the optical axis direction of the spot illumination light and detecting a plurality of confocal detection signals corresponding to the amount of movement from photoelectric conversion means of the confocal detection optical system. Means, wherein the signal processing circuit is configured to obtain a candidate for a desired height of the detection surface from among those in which the intensity of the confocal detection signal is equal to or more than a desired threshold value. Further, the present invention is characterized in that the three-dimensional shape detecting device further comprises a moving means for moving the object to be detected or the spot irradiation light in a direction substantially perpendicular to an irradiation optical axis. Further, the present invention is characterized in that in the three-dimensional shape detecting device, the annular illumination minute spot irradiation optical system is configured by arranging a plurality of spot illumination lights at least one-dimensionally. Further, according to the present invention, in the three-dimensional shape detecting apparatus, further, an auxiliary detecting means for detecting a relative displacement in the optical axis direction between the confocal detection optical system and the object to be detected; And a movement control unit that controls the object to be detected or the spot illumination light to relatively move in the optical axis direction of the spot illumination light based on the relative displacement.

As described above, since the spot to be detected on the surface of the object to be detected is irradiated with the spot illumination light composed of the annular illumination light, the spot illumination light has an annular intensity distribution on the pupil of the objective lens. (There is a ring-shaped portion with high intensity, and the intensity near the optical axis inside the ring-shaped portion is almost zero or sufficiently smaller than the portion with strong ring-shaped intensity.)
And can project a minute spot, and even if there is a high reflective surface under the transparent surface layer, reduce the confocal detection signal from it and detect the object surface with sufficient accuracy It becomes possible. Furthermore, when compared with an objective lens having the same numerical aperture, because of the annular illumination, the depth of focus becomes shallower, the height detection sensitivity can be increased by that amount, and the angle of incidence on a transparent surface becomes larger, and the reflection occurs. The rate can be increased, and the surface can be detected accurately. Further, according to the above configuration, high-speed detection is possible by configuring a plurality of spot illumination lights composed of the annular illumination light so as to be able to simultaneously detect the reflected lights by the plurality of spot illumination lights.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method and apparatus for detecting a three-dimensional shape and a confocal detection apparatus according to the present invention will be described with reference to the drawings. As the three-dimensional shape to be detected with respect to the detection target object according to the present invention, the height of irregularities or columnar projections formed on the surface of the transparent object or a layer on the surface of the object having a multilayer structure of a transparent substance There is a thickness (height) and the like. As described above, the present invention is to detect a three-dimensional shape such as the height of irregularities and protrusions on the surface of a detection target object having a transparent surface with high accuracy. First, a first embodiment of a three-dimensional shape detection device and a confocal detection device according to the present invention will be described. FIG. 1 shows a first embodiment of a three-dimensional shape detection device and a confocal detection device according to the present invention.
FIG. 2 is a configuration diagram showing an embodiment. As the light source 1, Y
A laser light source having a wavelength of 532 nm, which is the second harmonic of AG, was used. The reason why the second harmonic of YAG is used as the light source 1 is that the laser power is high, and a relatively short wavelength of visible light of green can be obtained. Although the laser light is used as the light source 1, any light source that can obtain a certain amount of detected light may be used. For example, a light source such as a light emitting diode or a mercury lamp that is relatively close to a point light source may be used. Further, although the amount of detected light is small and is not suitable for high-speed detection, the present invention can be implemented by using a halogen lamp or the like.

That is, the laser beam emitted from the laser light source 1 is incident on the orbicular zone illumination minute spot irradiation optical system 2 shown by the dotted line. The incident laser light is shaped into a desired flat shape (at least a one-dimensionally elongated slit-like light beam) by a beam expander composed of cylindrical lenses 201 and 202 arranged orthogonally to each other. The shaped laser beam is converted into a beam spot array at least one-dimensionally arranged in size of about 10μm~ several tens μm on sigma ₀ plane by passing through the lens array 21, which is at least one-dimensionally arranged Is done. Note that reference numeral 210 denotes a pinhole provided at the emission end of the lens array 21. However, this pinhole 210 is not always required. In short the secondary light source of a beam spot array which is at least one-dimensionally arranged by the lens array 21 on the sigma ₀ surface may be made of. The spot array laser light passed through the sigma ₀ surface as is spread again made incident on the lens 22 is reflected by the example mirror 211. At this time, the principal rays of each spot light constituting the spread light are parallel to each other. Then, the lens 22, the sigma ₀ plane in front focus, and the sigma ₁ side to the rear side focal point.面 On _one surface, there is a transparent glass filter 25 on which the pattern shown in FIG. 2 is drawn, and a black circle pattern (light shielding pattern) 251 having a radius R1 is drawn at the center thereof. Large part 252 is black (so as to shield light)
Is drawn. Thus, the complex amplitude of each spot light on the sigma ₀ plane is Furye converted on sigma ₁ surface by the lens 22, is filtered by the pattern 251 in this Furye conversion surface. That is, the filter 2 shown in FIG.
5, all the spot lights are simultaneously converted into the annular illumination light.

The light transmitted through the filter 25 is again Fourier-transformed on the Σ ₂ plane by the lens 23 having the focal length f 3, and at least one-dimensionally arranged annular illumination spot array on the Σ ₂ plane 260 are obtained.ス ポ ッ ト The spot array 260 on the _two surfaces has a focal length f4
Is Fourier transformed on the pupil 271 of the objective lens 27 by the lens system 24. That is, on the pupil 271, the light intensity distribution immediately after passing through the sigma ₁ surface is imaged at a magnification of f4 / f3. That is, assuming that the radius of the pupil 271 is Rp, there is no light in a region of a radius of Rd (Rd = R1 · (f4 / f3)) from the center of the pupil, and the outside of the region has a radius R2 · (f4 / f3)
Illumination light having light up to R2 or the smaller Re of the pupil radius Rp passes through the pupil 271 of the objective lens 27.
As a result, the surface of the object 3 that is the detection target is illuminated by the light transmitted through the objective lens 27 with the annular illumination spot array. By the way, the objective lens 27
Is attached to a lens drive mechanism 272 that drives the lens 27 at a high speed in the optical axis direction by a desired amount. Since the magnification of the objective lens 27 is as large as 40 to 100 times, the driving amount is equal to the moving amount in the optical axis direction of each beam waist of the orbicular illumination minute spot array with high accuracy. The orbicular zone illumination minute spot array light projected on the object (detected object) 3 is reflected on the object surface, re-enters the objective lens 27, is guided to the confocal detection optical system 4 shown by a dashed line, and is detected. You. The confocal detection system 4 forms an image of the irradiation spot on each of the pinholes 430 arranged at least one-dimensionally on the pinhole array 43 by the beam splitter 41 and the lens 42. At this time, for example, the n-th spot of the annular illumination minute spot array 260 (FIG. 3)
If the spot at the position on the optical axis where the spot diameter becomes the minimum as shown in FIG. 7) is focused on the object plane 310, the light intensity passing through the n-th pinhole 430n increases, and conversely, the m-th When the spot is not focused on the object plane 310 (in a defocused state), the light intensity passing through the m-th pinhole 430m through which the m-th spot image passes becomes small. The intensity of light transmitted through each pinhole 430 is individually detected by the photodetector array 44.

Next, an embodiment of the relationship between the numerical aperture NA of the objective lens 27 and the ratio r of the inner ring diameter Rd to the outer ring diameter Re of the annular zone in annular illumination will be described. In this embodiment,
The numerical aperture NA of the objective lens 27 is set to about 0.7, and the ratio r of the inner ring diameter Rd to the outer ring diameter Re of the annular zone in annular illumination is r.
= Rd / Re is about 0.1 or more and about 0.9 or less. The outer diameter Re of the annular illumination is made to correspond to the numerical aperture NA of the objective lens 27 because it is better to take the incident angle to the object as large as possible in consideration of the effects of the present invention. That is, R
If e = Rp ≦ R2, the maximum incident angle θx of the annular illumination
In contrast, the minimum incident angle θi is given by the following (Equation 1). sin θx = NA sin θi = r · NA (Equation 1) By the way, if the value of r exceeds the above range and is 0.1 or less, the effect of annular illumination cannot be sufficiently exhibited, and the annular zone used in confocal detection is used. It is not much different from the case of no illumination (r = 0). On the other hand, when r> 0.9, the ring-shaped light around the irradiation spot becomes strong, and the light use efficiency becomes insufficient.

Next, the fact that the S / N ratio of the signal obtained from the surface of the measurement point can be increased by the annular illumination even when the object to be detected is transparent will be described with reference to FIG. FIG. 3 shows a comparison between the case of annular illumination (r = 0.5) and the case of no annular illumination (r = 0) when the NA (numerical aperture) of the objective lens 27 is 0.7. 4 shows the spot distribution on the object plane when focusing (Δf = 0) and defocusing (Δf ≠ 0). At the focus position indicating the object plane to be measured, the annular illumination (r =
In the case of 0.5), the spot diameter at the center becomes smaller to some extent than in the case of non-zonal illumination (r = 0). However, conversely, since the side lobes on the peripheral ring become large, if r is too large in the annular illumination, the ratio of the side lobe portion to the light energy becomes large as compared with the central portion, and disadvantageously. Becomes In a defocus position indicating a plane other than the object plane, annular illumination (r = 0.5)
In the case of, the intensity near the measurement point decreases,
When the illumination is not annular illumination (r = 0), the intensity at the center of the measurement point is maximum in a wide defocus range. Even in the case of defocusing, if the value of r is too large to be 0.9 or more in the annular illumination, the light intensity distribution at the center of the measurement point in a wide defocusing range is not reduced as compared with the peripheral portion, and the detection sensitivity is reduced. . Therefore, r in annular illumination is
An optimum choice may be made according to the layer structure of the object.

As described above, as is apparent from FIG. 3, when the annular illumination is used, the spot intensity obtained from the defocus position indicating the surface other than the object surface is significantly reduced, and the measurement at the measurement point is performed. S of the spot intensity obtained from the focus position indicating the object plane to be obtained
The / N ratio can be significantly increased, and the detection sensitivity of the object surface to be measured can be significantly increased.
That is, the point (measurement point) on the surface of the object to be detected to be detected
The spot illumination light composed of the annular illumination light irradiated on the pupil 271 of the objective lens 27 has an annular intensity distribution (intensities at a portion where the annular intensity is strong and a portion near the optical axis inside the annular intensity portion). And a portion having a sufficiently small strength as compared with a portion having a strong or substantially annular shape.), The following remarkable effects can be obtained.

That is, the first effect is that the illumination light is annular spot illumination light on the pupil 271 of the objective lens 27.
It is possible to project minute spot illumination light on a portion to be detected. The second effect is that when the object plane 310 deviates from the minimum spot position because the distribution at the position deviated in the optical axis direction from the position narrowed to the minimum as shown in FIG. In the defocused state, almost no light hits the object plane that intersects the optical axis, so that the confocal detection signal is much smaller. As a result, even if there is a high reflective surface 320 under the transparent surface layer 31, The surface 310 can be detected with sufficient accuracy. The third effect is that, when compared with an objective lens having the same numerical aperture, because of annular illumination, the depth of focus becomes shallow, and the height detection sensitivity can be increased accordingly.

The fourth effect is that, because of annular illumination, there is no light having a small reflectance and an incident angle near 0 °, and the surface 310 is illuminated with a large incident angle and reflected by the transparent surface 310. The ratio increases as shown in FIG. 3, and the detection of the surface 310 can be performed accurately.

Next, the outer ring diameter Re of the annular zone in the annular illumination.
The ring condition control mechanism 255 for controlling the ratio r of the inner ring diameter Rd to the inner ring diameter Rd will be described. Ring condition control mechanism 25
Reference numeral 5 denotes a plurality of annular filters 25a to 25a having different r or different transmittances of the light shielding pattern 251 as shown in FIG.
5d is prepared, and is configured to be automatically switched to the optical path and mounted. That is, the input means 5 such as a keyboard, a recording medium, a network, etc.
When information such as the type of the detection target 3 is input and stored using the information processing device 1, the overall control unit 50 determines what ring filter based on the input information such as the type of the detection target 3. Is determined, and the determined selection data is provided to the orbicular zone condition control mechanism 255, whereby the orbicular zone filter suitable for the detection target is selected. In addition, as the annular filter 25, the central pattern 2
Although the case where the light-shielding pattern 51 is formed has been described, the central pattern 251 is configured to transmit a small amount of light, and the pseudo-ring illumination light (when the intensity of the pseudo-zonal illumination light weakens when the portion 251 passes slightly). Illumination light).

Next, based on the intensity signals Ik (hz) (k = 1 to n) individually detected by the photodetector array 44, the detection target 3 at each spot position (measurement point) k is determined. A method for calculating the surface height in the signal processing circuit 5 will be described. That is, the intensity signals Ik (hz) individually detected by the photodetector array 44 are sent to the signal processing circuit 5, where they are A / D converted, and the intensity signals Ik (hz) at the addresses k of the respective arrays are stored in the memory ( (Not shown). Here, hz is a signal by which the overall control unit 50 controls the lens driving mechanism 272, that is, the optical axis (measurement point k) of the spot array.
The above is the minimum aperture position information (the relative position hz in the Z direction between the objective lens 27 and the object 3 at the measurement point k), and is the minimum aperture position information given to the lens driving mechanism 272 from the overall control unit 50. That is, the overall control unit 50
Transmits the driving information hz to the lens driving mechanism 272 and also to the signal processing circuit 5, and based on this information, the signal processing circuit 5 moves the objective lens 27 in the optical axis direction by hz finely, and the light detection element array 44. The sampling of the intensity signal Ik (hz) at the points k (k = 1 to n) is repeatedly stored in the memory, and when the driving in the desired range is completed,
From the obtained information Ik (hz), the surface height at each spot position k is obtained by the following method. In the description of the above embodiment, the objective lens 27 is finely moved (finely moved) in the optical axis direction by the lens driving mechanism 272. However, a Z stage is provided on the stage on which the detection target 3 is mounted, and the Z stage is provided. May be finely moved hz in the optical axis direction of the objective lens 27 to finely move the object surface of the detection target 3 in the hz direction.
However, since the objective lens 27 is lighter in weight than the Z stage and the entire detection system, fine movement of the objective lens 27 in the optical axis direction can drive at a higher speed and realize high-speed detection.

Next, in the signal processing circuit 5, k (k = 1)
To n) intensity signal Ik (hz) at point 3
An embodiment for obtaining the three-dimensional shape of the object plane with high accuracy will be described. That is, since the signal processing circuit 5 can obtain the height at each spot position k independently from the information Ik (hz) obtained at each spot position, the embodiment at k = n points is shown in FIG. Is shown. The horizontal axis in FIG. 5 is the relative position hz between the objective lens and the object at point n, and the vertical axis is the detection intensity In (hz). Since the data In (hz) obtained from the photodetector array 44 is discrete, the signal processing circuit 5 obtains the true surface height hr indicated by the peak value at each spot position k = n by interpolation. Since annular illumination is performed for each spot position k = n, as shown in FIG. 3, the larger the obtained signal, the closer to the true surface (focus position). In addition, in the case where In (hz) is equal to or higher than a certain level IT, the larger the hz, that is, the higher the surface, the more the true surface. The height of the uppermost surface can be determined based on such a determination. That is, the detection target object 3 or the spot irradiation light is relatively moved in the optical axis direction z of the irradiation light, and the reflected light from the point n is confocal detected according to the movement hz to detect the detection intensity signal In (hz ), The three-dimensional shape can be detected based on the data indicating the peak position (for example, hM). By making the above determination, it is possible to narrow down the candidates for the surface to be detected. Therefore, depending on the application, not only the top surface but also the surface below the transparent layer can be determined.

That is, since the surface of the detection target object 3 is transparent, when the detection target object 3 is irradiated with a minute spot of annular illumination, the minute spot of the annular illumination is reflected on the target object shown in FIG. By being reflected on the uppermost surface 310 of the detection target 3 and a plurality of boundary surfaces 320 having different refractive indices, a detection intensity signal In (hz) having peaks at points A, B, and C as shown in FIG. 5 is obtained. This indicates that the surface is a candidate to be detected. Since point A is the uppermost surface, it can be seen that this is a candidate for the detected position data (hM). Therefore, the signal processing circuit 5 determines that In (h
z), based on the hM that gives the maximum value of
From the three data of In (hM−) and In (hM +) and In (hM) for − and hM +, hr that gives the true maximum at n points is obtained by interpolation. The method of interpolation uses quadratic approximation or the like. That is, the detection target 3 or the spot irradiation light is relatively moved in the optical axis direction z of the irradiation light, and this movement (based on hM, hM− and hM−
+), The intensities of a plurality of confocal detection signals (for example, In (hM−), In (hM +), and In (h
M)) to obtain the maximum position data (hr) by interpolation, thereby obtaining a highly accurate three-dimensional shape (hr).

Further, the focus position where the diameter of the spot illumination light becomes minimum is changed from above to below the surface 310 of the detection target 3 or from above to below. By setting the uppermost height position (hM) as a detection position data candidate as indicated by point A among those having a corresponding confocal detection signal intensity In (hz) equal to or greater than a desired threshold value IT, Even if there is a reflection, the uppermost surface 310 can be accurately detected without mistake. Reference numeral 31 denotes a transparent layer on the surface of the detection target object 3, and reference numeral 32 denotes a transparent layer thereunder. Therefore,
Reference numeral 310 denotes the uppermost surface (object surface) of the detected object 3;
Reference numeral 20 denotes a boundary surface having a different refractive index thereunder.

As described above, the signal processing circuit 5 operates at each point k = 1 to k of the spot array obtained from the photodetector array 44.
For n, the position (height) hr of the uppermost surface by the above method
And moves the detected object 3 and the detection system relatively in a direction (for example, a direction perpendicular to) that intersects with the direction of the one-dimensional array by a command from the overall control unit 50 (moving mechanism (not shown)).
For example, a stage on which the detected object 3 is mounted may be used, or a stage supporting a detection system may be used. In the same manner, the height of each point k = 1 to n of the spot array obtained from the photodetector array 44 is sequentially obtained to measure the unevenness and the three-dimensional shape of the uppermost surface of the detection target 3. be able to. In particular, from the photodetector element array 44, the detection intensity signals Ik
Since (hz) can be detected, the three-dimensional shape of the entire object to be detected 3 can be measured by reducing the number of times that the object to be detected 3 and the detection system are relatively moved, and the detection speed is increased. be able to.

That is, a plurality of spot illumination lights composed of annular illumination light are arranged in a one-dimensional manner, and the object 3 to be detected or the spot irradiation light is slightly moved in the optical axis direction z of the irradiation light while the light detection element is being moved. The position (height) hz (x) of the uppermost surface is determined for each point x of the spot array obtained from the array 44, and a plurality of arrayed spot illumination lights and detected objects are detected in a direction intersecting the array x direction (for example, the y direction orthogonal to the array). Object 3 and
For example, by driving a Y stage (not shown) to relatively move and change the position, the three-dimensional shape two-dimensional distribution hz (x, y) of the detection target can be obtained. The laser beam is two-dimensionally expanded by a beam expander and passed through a two-dimensionally arranged lens array 21 to output a two-dimensionally arranged beam spot array from a pinhole 210, and Hole array 43 and photodetector array 44
Are two-dimensionally arranged, it is possible to measure the two-dimensional uneven shape and the three-dimensional shape of the uppermost surface of the detected object 3 at one time.

Next, a second embodiment of the three-dimensional shape detection device and the confocal detection device according to the present invention will be described. FIG. 6 is a diagram illustrating a second embodiment of the three-dimensional shape detection device and the confocal detection device according to the present invention. As described in the first embodiment, since the objective lens 27 has a large magnification, the object plane is several μm from the focal position of the objective lens.
If the distance is longer than the above, it is difficult to determine whether the focal position is above or below the object. Therefore, only the optical system described in the first embodiment measures the object 3 having a large step or the direction of the focal point with respect to the object surface when the measurement of the object 3 is started. I lose sight of it. Therefore, in the second embodiment, an auxiliary height detection system 6 having an accuracy of about several μm is fixedly attached to the detection system. The auxiliary detection system 6 shown in FIG. 6 is an oblique irradiation projection system 6 that obliquely enters the spot light 61 on the object plane.
1 and the spot light reflected by the object is used as the position sensor 6
An optical lever type detection system including a lens 62 for forming an image on the optical system 3.

As described above, by providing the auxiliary detection system 6 integrally with the above-mentioned detection system, the height of the spot on the object, that is, the height of the object surface can be several μm from the signal of the position sensor 63.
It can be detected with a degree of accuracy. Therefore, by sending the height information of the object surface with an accuracy of about several μm detected by the auxiliary detection system 6 to the overall control unit 50,
In the case of 0, the objective lens 27 or the detected object 3 is driven based on this signal, and the position of the detected object surface (uppermost surface) of the detected object 3 is adjusted to the position of the minute spot of the annular illumination from the objective lens 27. It can be almost adjusted to the focal position. That is, the overall control unit 50 controls the lens drive mechanism 272 or the Z stage from the position where the focal position of the objective lens 27 detected by the auxiliary detection system 6 matches the detected object plane, for example, by plus (up) Δh It is positioned in the height direction in a short time at the offset position, and then Δh ~ 0
The measurement is performed by the method described in the first embodiment while the positions of the objective lens 27 and the detected object 3 are relatively changed toward -Δh and downward. Thus, the auxiliary detection system 6
, The detection can be performed at high speed without error.

That is, when obtaining the three-dimensional shape two-dimensional distribution hz (x, y) of the detection target 3, the distance between the detection system and the detection target 3 due to a relative position change (movement) in the y direction is determined. Is detected by the auxiliary detection system 6 and the correction control is performed as described above, so that a three-dimensional shape of a sample having a two-dimensional spread (object to be detected) can be precisely formed over a wide area. It becomes possible to detect. The auxiliary detection system 6 is not limited to the embodiment of FIG. 6 described above, and any auxiliary detection system may be used as long as it has a wide detection area with almost the same accuracy in the dead zone of the detection system shown in FIG. May be.

Next, a third embodiment of the three-dimensional shape detecting device and the confocal detecting device according to the present invention will be described. The first and second embodiments described above are embodiments in which the present invention is applied to surface height measurement or surface shape measurement, but more generally, a confocal detection system is used for focusing. It is also possible to carry out. That is, if the confocal detection by the annular illumination according to the present invention is performed, the focus detection accuracy is particularly advantageous for detecting an object having a transparent surface and a large base reflectance. At this time, the number of spots by the annular illumination may be one or plural. For example, when a relatively flat object is detected, only one annular illumination spot may be used, or when there is unevenness in the detection field of view, a plurality of annular illumination spots may be simultaneously illuminated. The desired position can be focused. As described above, when the annular illumination confocal detection system according to the present invention is used for pattern detection on the surface of an object, the third embodiment in which the present detection system is mounted in the pattern detection optical system is required.

FIG. 7 is a diagram showing a third embodiment in which this mounting is performed. 7 and 1 have the same thing or the same function. That is, reference numeral 1 denotes an illumination light source for annular illumination confocal detection, which has a single wavelength λ ₀ . Reference numeral 2 denotes an annular illumination optical system. 41 'is a polarization beam splitter of the confocal detection system 4, and 27 is an objective lens. 7 is a pattern detection optical system, 71 is its illumination system, and 72 is a detector such as an image sensor. Reference numeral 73 denotes a polarization beam splitter, which allows only P-polarized light in the illumination light to pass therethrough and is used as detection illumination light. The light transmitted through the polarization beam splitter 73 is
The light passes through the imaging lens (tube lens) 74, passes through the 通 り wavelength plate 75, becomes circularly polarized light, is reflected by the wavelength selection beam splitter 8, and enters the objective lens 27. The wavelength selection beam splitter 8 transmits only light in a narrow range of wavelength λ ₀ ± Δλ, and reflects most of the wavelength of white illumination light of the pattern detection system. Therefore, the pattern can be detected with almost white light. The white light that is reflected back from the object 3 is reflected by the wavelength selection beam splitter 8 and is returned to the 波長 wavelength plate 75.
, And becomes S-polarized light, is reflected by the polarization beam splitter 73, and is detected by a detector 72 such as an image sensor. Therefore, the detector 72 can detect an image signal based on white light for a pattern, a defect, or the like formed on the detection target 3, and the image signal processing circuit 76 inspects the pattern for defects based on the image signal. Etc. can be performed.

As the light source 1 of the annular illumination detection system, 532
It is composed of a solid-state laser that emits P-polarized laser light with a wavelength λ ₀ of nm and parallel to the plane of the drawing. The annular illumination optical system 2 is basically the same as that of the first embodiment described with reference to FIG. 1, but in the third embodiment, the minute spot of the annular illumination is two-dimensional. Are arranged. After passing through the polarizing beam splitter 41, the two-dimensional spot array of this annular illumination passes through the lens 24 (42) and
The light is converted into circularly polarized light by passing through the wave plate 48.
The two-dimensional spot array of the annular illumination converted into the circularly polarized light transmits through the wavelength selection beam splitter 8 that transmits light of wavelength λ ₀ (532 nm) at a transmittance of 90% or more, and transmits through the objective lens 27. The surface of the detection target 3 is irradiated. The light reflected by the detection target 3 is reflected by the objective lens 2
7 and the wavelength selective beam splitter 8,
After being converted from circularly polarized light to S-polarized light by the four-wavelength plate 48 and transmitted through the imaging lens 24 (42), the polarization beam splitter 4
The light is reflected by 1 ′, enters the two-dimensional pinhole array 43 ′, and is two-dimensionally confocal detected by the two-dimensional sensor array 44 ′. Since the focal position of the annular illumination confocal detection system and the focal position of the pattern detection system are adjusted in advance so that they can be focused by the above-described method using the annular illumination confocal detection system, the pattern detection optical system can be used. The focal point is also detected in the system.

Accordingly, in the annular illumination confocal detection system, the light formed on the surface of the detection target 3 is focused on the surface of a film (for example, an insulating film such as an oxide film) which is transparent to the pattern detection optical system. A system such as a pattern such as a through hole formed in a film transparent to light (for example, an insulating film of an oxide film) and a defect such as a foreign substance or a scratch formed on a transparent film (for example, an insulating film of an oxide film). Inspection can be performed from an image signal based on white light. In particular, the reason why white illumination is performed to inspect a pattern, a defect, or the like formed in the transparent film is to eliminate light interference generated in the transparent film.

[0036]

According to the present invention, by using annular illumination light as the irradiation spot light for confocal detection, it is particularly possible to detect the position (height) of the surface of a transparent object (three-dimensional shape detection).
There is an effect that it is hard to be affected by the reflection surface below the surface, and it is possible to detect the position accurately. Further, according to the present invention, the height of the transparent member having a height of several μm used for the spacer of the liquid crystal display device can be accurately detected by using the annular illumination light as the irradiation spot light for the confocal detection. It works.

Further, according to the present invention, the three-dimensional shape of a plurality of points on the object to be detected can be measured simultaneously by arranging minute spots of annular illumination for confocal detection in an array. This has the effect that the detection speed can be improved. Further, according to the present invention, a pattern formed on a film transparent to light formed on the surface of an object to be detected or a defect such as a foreign substance or a scratch formed on the transparent film is based on white light. There is an effect that inspection can be performed with high accuracy from an image signal.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a three-dimensional shape detection device and a confocal detection device according to the present invention.

FIG. 2 is a diagram showing one embodiment of a filter for realizing annular illumination according to the present invention.

FIG. 3 is a diagram showing a spot intensity distribution for explaining the effect of the present invention.

FIG. 4 is a view showing an embodiment of a zone condition control mechanism according to the present invention.

FIG. 5 is a diagram illustrating a relationship between a relative position hz between an objective lens and an object at a measurement point n and a detection intensity In (hz).

FIG. 6 is a schematic configuration diagram showing a second embodiment of the three-dimensional shape detection device and the confocal detection device according to the present invention, which includes an auxiliary detection system.

FIG. 7 is a schematic configuration diagram showing a third embodiment in which the annular illumination confocal detection device according to the present invention is applied to pattern detection.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Ring illumination micro spot irradiation optical system (ring illumination optical system), 201, 202 ... Cylindrical lens, 21 ... Lens array, 210 ... Pinhole, 22 ...
Lens, 24 (42): lens system, 25: annular illumination filter, 251: light-shielding pattern, 260: annular illumination spot array, 27: objective lens, 271: pupil, 3: object to be detected, 31: surface Transparent layer of 310, object surface (top surface), 32: transparent layer of lower layer, 320: boundary surface (reflection surface), 4: confocal detection system, 41: beam splitter, 4
1 ': polarizing beam splitter; 42: lens; 43: pinhole array; 43': two-dimensional pinhole array;
30 ... pinhole, 44 ... photodetector array, 44 '...
Two-dimensional sensor array, 5 ... signal processing circuit, 50 ... overall control unit, 6 ... auxiliary optical system, 7 ... pattern detection optical system, 8 ...
Wavelength selection beam splitter, 71: pattern detection illumination system, 72: detector, 73: polarization beam splitter, 74
... Lens, 48, 75 ... 1/4 wavelength plate, 76 ... Image signal processing circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mineo Nomoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside Hitachi, Ltd.Production Technology Research Institute (72) Inventor Hideo Ishimori 3--16, Higashi 3-chome, Shibuya-ku, Tokyo No. 3 F-term in Hitachi Electronics Engineering Co., Ltd. (reference) 2F065 AA24 AA49 AA54 BB22 DD04 DD06 EE00 FF09 FF10 FF42 FF67 GG04 GG22 HH01 HH04 HH08 HH12 HH13 JJ01 JJ02 JJ03 JJ05 JJ08 LL09 LL37 LL47 MM01 NN20 PP02 PP03 PP12 QQ17 QQ23 QQ28 UU07

Claims (19)

[Claims] 1. A method according to claim 1, further comprising: irradiating a detection location on the detection target object with one or more spot illumination lights formed by illumination light of an annular zone or a pseudo annular zone; A three-dimensional shape detection method, comprising: detecting a three-dimensional shape of an object to be detected based on the intensity of a signal obtained by confocal detection of reflected light. 2. A method according to claim 1, further comprising: irradiating each of the plurality of detection locations on the detection target object with a plurality of spot illumination lights formed by illumination light of a ring or a pseudo-orbicular zone; A three-dimensional shape at a plurality of detection points of the object to be detected based on signal intensities obtained by performing confocal detection of reflected light of each spot illumination light. 3. The three-dimensional shape detection according to claim 1, wherein the ratio of the inner ring diameter to the outer ring diameter of the annular zone is 0.1 or more and 0.9 or less in the illumination light of the annular zone. Method. 4. The apparatus according to claim 1, wherein the object to be detected or the spot illumination light is relatively moved in an optical axis direction of the spot illumination light, and the reflected light corresponding to the movement is subjected to confocal detection. Item 3. The method for detecting a three-dimensional shape according to Item 1 or 2. 5. A three-dimensional shape is detected by interpolating and obtaining maximum position data using the intensities of a plurality of confocal detection signals obtained according to the movement. 3D shape detection method. 6. A focus position where the diameter of the spot illumination light is minimized in the vertical direction of the surface of the detection target object as the movement, and the intensity of a confocal detection signal corresponding to the spot illumination light is set to a desired value. 5. The three-dimensional shape detection method according to claim 4, wherein the position data at the top of the three or more threshold values is set as a three-dimensional shape candidate of the surface of the detection target. 7. The object to be detected or the spot irradiation light is moved in a direction substantially perpendicular to an irradiation optical axis, and a wide range of three-dimensional shapes is detected from the object to be detected. 3. The method for detecting a three-dimensional shape according to 2. 8. A method according to claim 1, wherein the plurality of spot illumination lights are at least one.
The three-dimensional shape of the detection target object is formed by dimensionally arranging the plurality of spot illumination lights and the detection target object relative to each other in a direction intersecting the arrangement direction of the spot illumination light. The three-dimensional shape detection method according to claim 1, wherein a two-dimensional distribution is obtained. 9. An orbicular illuminating minute spot irradiating optical system for irradiating, through an objective lens, one or more spot illuminating lights formed by illuminating light of an orbicular zone or a pseudo-orbicular zone to a detection point on an object to be detected. A confocal detection optical system having photoelectric conversion means for performing confocal detection of reflected light of spot illumination light applied to the detection location by the orbicular zone illumination minute spot irradiation optical system through the objective lens; A signal processing circuit for processing a signal obtained by the photoelectric conversion means of the system. 10. An annular illumination minute spot for irradiating each of a plurality of spots formed by annular or pseudo annular illumination light through an objective lens to each of a plurality of detection locations on an object to be detected. A confocal detection optical system comprising: an irradiation optical system; and a plurality of photoelectric conversion means for performing confocal detection of reflected light of each spot illumination light applied to each of the detection points by the annular illumination minute spot irradiation optical system through the objective lens. A confocal detection device, comprising: a system; and a signal processing circuit that processes signals obtained by each of the plurality of photoelectric conversion units of the confocal detection optical system. 11. The optical system according to claim 9, wherein a ratio of an inner ring diameter to an outer ring diameter of the orbicular zone is 0.1 or more and 0.9 or less in the orbicular zone illumination minute spot irradiating optical system. Confocal detection device. 12. An optical system for illuminating minute spots, which irradiates one or more spot illuminating lights formed by illuminating light of an annular zone or a quasi-annular zone through an objective lens onto a detection point on an object to be detected. A confocal detection optical system having photoelectric conversion means for performing confocal detection of reflected light of spot illumination light applied to the detection location by the orbicular zone illumination minute spot irradiation optical system through the objective lens; A signal processing circuit for detecting a three-dimensional shape at a detection point on the detection target based on the intensity of a signal obtained by a photoelectric conversion means of the system. 13. A zonal illumination minute spot for irradiating each of a plurality of spots formed by illuminating light of an annular zone or a quasi-annular zone through an objective lens to each of a plurality of detection locations on an object to be detected. A confocal detection optical system comprising: an irradiation optical system; and a plurality of photoelectric conversion means for performing confocal detection of reflected light of each spot illumination light applied to each of the detection points by the annular illumination minute spot irradiation optical system through the objective lens. A signal processing circuit for detecting a three-dimensional shape at each of a plurality of detection points on the detection target object based on signal intensities obtained by each of the plurality of photoelectric conversion units of the confocal detection optical system. A three-dimensional shape detection device, comprising: 14. The method according to claim 1, further comprising: moving the object to be detected or the spot illumination light relatively in an optical axis direction of the spot illumination light; 14. The three-dimensional shape detection device according to claim 12, further comprising a movement control unit that detects the light from the photoelectric conversion unit of the optical system. 15. The three-dimensional shape by interpolating and obtaining the maximum position data using the intensities of a plurality of confocal detection signals obtained from the confocal detection optical system in accordance with the amount of movement in the signal processing circuit. The three-dimensional shape detection device according to claim 14, wherein the three-dimensional shape detection device is configured to detect the three-dimensional shape. 16. The object to be detected or the spot illumination light is changed so that the focus position where the diameter of the spot illumination light becomes minimum is changed in the vertical direction of the surface of the object to be detected. Moving control means for relatively moving in the optical axis direction, and detecting a plurality of confocal detection signals corresponding to the amount of movement from the photoelectric conversion means of the confocal detection optical system; 14. The three-dimensional shape detection device according to claim 12, wherein a candidate for a height of a desired detection surface is obtained from among those whose intensity of a focus detection signal is equal to or more than a desired threshold. 17. A moving means for moving said object to be detected or said spot irradiation light in a direction substantially perpendicular to an irradiation optical axis.
3. The three-dimensional shape detection device according to 3. 18. The three-dimensional shape detecting device according to claim 12, wherein said annular illumination minute spot irradiating optical system is configured by arranging a plurality of spot illumination lights at least one-dimensionally. 19. An auxiliary detecting means for detecting a relative displacement in the optical axis direction between the confocal detection optical system and the object to be detected, and the detecting means detects the relative displacement based on the relative displacement detected by the auxiliary detecting means. 14. The three-dimensional shape detection device according to claim 12, further comprising a movement control unit that controls the object to be detected or the spot illumination light to relatively move in the optical axis direction of the spot illumination light. .