JP2007033381A - Optical inspection apparatus and its lighting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical inspection apparatus capable of balancing both a confocal optical system and a normal bright-field optical system and reducing reductions in light intensity which occurs when the normal bright-field optical system is changed over to the confocal optical system. <P>SOLUTION: In the optical inspection apparatus 1, a first pinhole plate 30 for reducing illumination light illuminating a sample 15 from a light source 11 and a second pinhole plate 32 for reducing reflected light acquired by the reflection of the illumination light at a sample 15 are provided for positions conjugate to each other. The pinhole plates 30 and 32 are attached and removed to changed over between the confocal optical system and the normal bright-field optical system. A light condensing optical element 31 for condensing illumination light incident onto pinholes P1-P5 on the first pinhole plate 30 is simultaneously attached and removed with the first pinhole plate 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical inspection apparatus used for inspecting a semiconductor such as a wafer or a mask, and an illumination method therefor, and more particularly, an optical inspection apparatus configured to be able to switch between a confocal optical system and a normal bright field optical system. And an illumination method thereof.

A predetermined pattern is repeatedly formed on a semiconductor wafer, a semiconductor memory photomask, a liquid crystal display panel, or the like. In view of this, an optical image of this pattern is captured and a pattern defect is detected by comparing adjacent patterns. As a result of the comparison, if there is no difference between the two patterns, the pattern has no defect, and if there is a difference, it is determined that a defect exists in one of the patterns.
In such a semiconductor wafer appearance inspection apparatus, an optical microscope is generally used to capture an optical image of a pattern.

A pattern formed on the semiconductor wafer or the like is very fine, and in order to find a minute defect existing in the fine pattern, a very high resolution is required. For this reason, a confocal microscope is often used for a semiconductor wafer appearance inspection apparatus (for example, Patent Document 1 and Patent Document 2 below). In addition, resolution is improved by shortening the wavelength.
In the following description, a semiconductor wafer appearance inspection apparatus for inspecting a defect of a pattern formed on a semiconductor wafer will be described as an example. However, the present invention is not limited to this, and can be applied to various optical inspection apparatuses such as an optical microscope.

JP 2000-92398 A JP 2002-328099 A

Since the confocal microscope has a shallow depth of focus, it is difficult to examine a sample having a multiple structure in the optical axis direction by a single inspection. Therefore, an inspection apparatus capable of switching both the confocal optical system and the normal bright field optical system at the same time is preferable.
The confocal optical system includes a first pinhole plate that narrows down the illumination light that illuminates the sample from the light source, and a second pinhole plate that narrows the reflected light reflected by the sample from the illumination light at a conjugate position to each other. Realized.
However, when the inspection apparatus is configured so that the confocal optical system and the normal bright field optical system can be switched by attaching and detaching these pinhole plates, most of the illumination light is generated by the first pinhole plate that narrows the illumination light. Since the light is blocked, there is a problem that the amount of light is greatly attenuated as compared with the bright field observation and the throughput of the inspection apparatus is lowered.

  In view of the above problems, the present invention makes the confocal optical system compatible with the normal bright field optical system, and reduces the light amount reduction that occurs when switching from the normal bright field optical system to the confocal optical system. The object is to reduce the throughput drop.

To achieve the above object, in the optical inspection apparatus according to the present invention, a first pinhole plate that narrows down the illumination light that illuminates the sample from the light source, and a second pinhole plate that narrows the reflected light reflected by the sample from the illumination light. And illuminating light incident on the pinhole on the first pinhole plate by switching between the confocal optical system and the normal bright field optical system by attaching and detaching these pinhole plates. The condensing optical element that condenses light is attached and detached simultaneously with the first pinhole plate.
By attaching and detaching such a condensing optical element at the same time as the first pinhole plate, it is possible to reduce a reduction in the amount of light that occurs when switching from a normal bright field optical system to a confocal optical system.

  If the condensing optical element is inserted between the first pinhole plate and the light source, the solid angle of the incident light beam seen from the pinhole changes, so that the illumination NA changes. When Koehler illumination is used in the illumination optical system, the coherence changes when the illumination NA changes, thereby affecting the resolution, depth of focus, and contrast. On the other hand, the optimal illumination NA varies depending on the observation target, and the inspection apparatus is preferably configured to be able to change the aperture NA.

  Therefore, an optical inspection apparatus according to the present invention is a condenser lens provided between a first pinhole plate and a light source, and the first pinhole plate is located at a rear focal position or a conjugate position thereof. A condenser lens, a variable magnification optical system that projects a light source image of the light source at a variable focal magnification at the front focal position of the condenser lens, and an illumination aperture that changes the illumination numerical aperture by changing the projection magnification of the variable magnification optical system And a numerical aperture changing means, and fluctuations in aperture illumination due to attachment / detachment of the condensing optical element may be offset by the illumination numerical aperture changing means.

  Furthermore, in the optical inspection apparatus, it is preferable if the observation magnification of the optical microscope can be changed according to the type of observation object. As a method for switching the observation magnification, there are a method for switching the magnification of the objective lens of the optical microscope and a method for switching the magnification of the imaging lens for forming the image of the inspection object projected by the objective lens. . Among these, the method of switching the imaging lens does not require the preparation of an objective lens for each magnification, and it is not necessary to move the objective lens, so that the optical axis can be easily reproduced.

Accordingly, the optical inspection apparatus according to the present invention includes an imaging system magnification changing unit that changes the magnification of the imaging optical system that forms an image of the reflected light reflected by the sample on the observation surface.
At this time, if the observation magnification is increased with the imaging optical system, only the observation field is narrowed, and the illumination range of the illumination light that irradiates the sample does not change. There is a problem of illuminating a difficult area.
Therefore, the optical inspection apparatus according to the present invention changes the projection magnification for projecting the illumination light on the first pinhole plate according to the magnification of the imaging optical system, and changes the luminous flux of the illumination light at the position of the first pinhole plate. You may comprise and comprise illumination intensity change means to change the intensity | strength of the illumination light irradiated to a sample by changing a cross-sectional dimension and changing the illumination intensity of the illumination light which passes a pinhole.

In order to change the projection magnification at which the illumination light is projected onto the first pinhole plate, the above variable magnification optical system is configured by including a plurality of fly eye lenses having different magnifications, and the illumination intensity changing means includes a plurality of fly eye lenses. It is good also as changing the intensity | strength of the illumination light irradiated to a sample by switching a lens.
Alternatively, the illumination intensity changing means may change the intensity of the illumination light applied to the sample by changing the magnification of the condenser lens.

  According to the present invention, both the confocal optical system and the normal bright field optical system are compatible, and the light amount reduction that occurs when the normal bright field optical system is switched to the confocal optical system is reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an optical inspection apparatus according to a first embodiment of the present invention. As shown in the figure, a stage 16 that holds the sample 15, a light source 11 for illuminating the sample 15, an objective lens 14 that projects an optical image of the surface of the sample 15, and illumination light generated from the light source 11 as an objective lens The illumination optical system 12 that irradiates the sample 15 via 14, the imaging optical system 18 that forms an image of the sample 15 projected by the objective lens 14, and the illumination light incident from the illumination optical system 12 is the objective lens 14. A beam splitter 13 that reflects the projection light of the image of the sample 15 by the objective lens 14 to the imaging optical system 18 and an optical image of the surface of the semiconductor wafer 2 projected by the imaging optical system 18. And an imaging device 19 for converting into an electrical image signal. The light source 11 may be a lamp light source or a laser light source. In particular, when a laser light source having a wavelength of 270 nm or less is used, the resolution is improved by the wavelength, which is even more effective.

The illumination optical system 12 condenses the light from the light source 11 and creates a light source image with uniform brightness at the rear focal position, and the rear focal position of the variable magnification optical system 20. And a relay lens 81 for projecting the light source image connected to the rear focal position of the condenser lens 40 at infinity. The light source image projected at infinity by the relay lens 81 is reflected by the beam splitter 13 to the objective lens 14 and then condensed by the objective lens 14 onto the sample 15. As a result, the surface of the sample 15 which is conjugate with the rear focal position of the condenser lens 40 is illuminated with illumination light of uniform brightness.
On the other hand, the imaging optical system 18 forms an image of the sample 15 projected by the objective lens 14 and an image of the sample 15 connected by the imaging lens 50 on the image sensor 19. A relay lens 82 for imaging.

Further, the illumination optical system 12 includes a first pinhole plate 30 having a number of minute pinholes that allow the illumination light from the light source 11 to pass therethrough at the rear focal position of the condenser lens 40. On the other hand, the imaging optical system 18 is provided with a second pinhole plate 32 having a number of minute pinholes on the focal plane of the imaging lens 50 which is a conjugate position with the position where the first pinhole plate 30 is provided.
Each minute pinhole provided in the second pinhole plate 32 has each illumination light passing through each minute pinhole provided in the first pinhole plate 30 via the relay lens 81, the beam splitter 13 and the objective lens 14. The primary reflected light passes through the beam splitter 13 and the imaging lens 50 again, and is provided at a position where an image is formed on the focal plane of the imaging lens 50. In this way, the second pinhole plate 32 allows only the light focused on the focal plane of the imaging lens 50 to pass therethrough, so that the light from other than the focused part appears to overlap. Prevent image blur.

  The first pinhole plate 30 and the second pinhole plate 32 are detachably provided on the illumination optical system 12 and the imaging optical system 18, respectively. The optical inspection apparatus 1 switches the optical system of the optical inspection apparatus 1 to either a confocal optical system or a normal bright-field optical system by simultaneously inserting and extracting these pinhole plates into the respective optical systems. In accordance with an optical system switching control unit 91 and a command signal from the optical system switching control unit 91, the first pinhole plate 30 and the second pinhole plate 32 are detachably inserted into the illumination optical system 12 and the imaging optical system 18. A pinhole attaching / detaching mechanism 92 is provided.

2A shows a two-dimensional arrangement of minute pinholes P1 to P5... In the first pinhole plate 30. FIG. The arrangement of minute pinholes in the confocal optical system is known from various documents, and detailed description thereof is omitted here. In this embodiment, the arrangement interval Ps between the minute pinholes P1 to P5... Is 100 μm, for example, and the diameter Pd of each minute pinhole is 25 μm.
Here, when the magnification of the relay lens 81 and the objective lens 14 is set to 100, the light beam that has passed through the minute pinhole irradiates the sample 15 as spot light having a diameter of 250 nm.
On the other hand, in this embodiment, the magnification of the objective lens 14 and the imaging lens 50 is set to be the same as that of the relay lens 81 and the objective lens 14 (100 times). Therefore, the second pinhole plate 32 is provided with minute pinholes in the same arrangement as the arrangement of minute pinholes P1 to P5... On the first pinhole plate 30.

The light that has passed through the second pinhole plate 32 is imaged on the light receiving surface of the imaging device 19 via the relay lens 82. Here, if the magnification of the relay lens 82 is 0.8, the image passing through the minute pinhole having a diameter of 25 μm on the second pinhole plate 32 has a size of 30 μm on the light receiving surface of the imaging device 19. Projected on.
In this embodiment, a TDI sensor is used as the imaging device 19. Then, by moving the stage 16 and relatively scanning the second pinhole plate 32 and the sample 15, a captured image of the entire surface of the sample 15 is obtained. If the size of one pixel of the TDI sensor is 10 μm square, an image that has passed through one second pinhole plate 32 is projected onto 3 × 3 pixels.

The illumination optical system 12 is a collection of a microlens array or the like that condenses the illumination light irradiated to the first pinhole plate 30 through the condenser lens 40 into the minute pinholes provided in the first pinhole plate 30. An optical optical element 31 is provided. FIG. 3 is a perspective view of the first pinhole plate 30 and the condensing optical element 31 shown in FIG. In FIG. 3, a microlens array is used for the condensing optical element 31.
The condensing optical element 31 includes microlenses (microlenses) L1 to L5 arranged at the same intervals as the micropinholes P1 to P5 provided in the first pinhole plate 30, and each microlens L1. ˜L5... Are aligned so that their optical axes pass through the centers of the corresponding pinholes P1 to P5.

  When such a condensing optical element 31 is inserted in front of the first pinhole plate 30 when viewed from the condenser lens 40, the light is irradiated around the minute pinholes P1 to P5. Thus, even the illumination light that cannot pass through the first pinhole plate 30 is condensed in the minute pinholes P1 to P5 and can pass through the first pinhole plate 30. With this function, the amount of illumination light shielded by the first pinhole plate 30 is reduced, and a reduction in the amount of light in the confocal optical system in which the first pinhole plate 30 and the second pinhole plate 32 are inserted is reduced.

  Here, the condensing optical element 31 is inserted and extracted simultaneously with the first pinhole plate 30 by the pinhole attaching / detaching mechanism 92. For this reason, the condensing optical element 31 may be formed integrally with the first pinhole plate 30. As such a condensing optical element 31, the multi-lens array or the transmission diffraction grating can be used. Further, for example, the multi-lens array can be formed by a lens molding technique or etching.

  When the first pinhole plate 30 and the second pinhole plate 31 are inserted and removed to switch between the confocal optical system and the normal bright field optical system, when the condensing optical element 31 is inserted and removed together with the first pinhole plate 30, a minute amount is obtained. The illumination numerical aperture (illumination NA) varies because the solid angle of the incident light beam expected from the pinhole varies. Specifically, in the normal bright-field optical system in which the condensing optical element 31 is removed from the optical path, the illumination numerical aperture is lower than in the confocal optical system in which the condensing optical element 31 is inserted, and coherence is achieved. σ (= illumination NA / imaging NA) becomes small. The optimum coherence σ for observation differs depending on the observation target, and it is preferable that it can be adjusted regardless of the change in the optical system.

  Therefore, in the optical inspection apparatus 1, the illumination numerical aperture is changed by changing the projection magnification of the variable magnification optical system 20 to change the size of the light source image of the light source projected on the front focal position of the condenser lens 40. To do. When the optical system switching control unit 91 switches the optical system, the optical inspection apparatus 1 has a variable magnification optical system depending on whether the current optical system is a confocal optical system or a normal bright field optical system. An illumination numerical aperture changing unit 93 that changes the projection magnification of 20 and cancels fluctuations in aperture illumination due to the attachment / detachment of the condensing optical element 31 is provided.

For example, when the current optical system is a confocal optical system, the illumination numerical aperture changing unit 93 reduces the projection magnification of the variable magnification optical system 20 and projects the light source of the light source projected onto the front focal position of the condenser lens 40. On the contrary, in the case of a normal bright field optical system, the size of the image is reduced, and the projection magnification of the variable magnification optical system 20 is increased to reduce the size of the light source image of the light source projected on the front focal position of the condenser lens 40. By making it large, it is good also as offsetting the fluctuation | variation of the illumination numerical aperture produced by the presence or absence of the condensing optical element 31. FIG.
Alternatively, the illumination numerical aperture changing unit 93 may determine whether the current optical system is a confocal optical system or a normal bright field optical system (that is, regardless of the presence or absence of the condensing optical element 31). The number may be used to set freely according to the observation object.

  The variable magnification optical system 20 may be configured as a zoom optical system capable of continuously changing the diameter φ of the emitted light beam by moving two or more lens groups. Alternatively, a plurality of beam expanders having different projection magnifications are provided, and the dimensions of the light source image of the light source projected on the front focal position of the condenser lens 40 are changed stepwise by switching between them. It is good.

  For this purpose, as shown in FIG. 4, a beam expander mechanism 20 that switches the projection magnification of the beam expander according to the control of the illumination aperture changing unit 93 may be provided. The beam expander mechanism 20 includes a disk 22 provided with a plurality of beam expanders 21a to 21c having different projection magnifications. Then, by rotating the motor 23 according to the control from the illumination aperture changing unit 93 and rotating the disk 22 around the axis 24 as a rotation axis, the beam expanders 21a to 21c positioned on the optical axis a2 of the illumination light are switched, thereby projecting. Switch the magnification.

FIG. 5 shows a schematic configuration diagram of an optical inspection apparatus according to the second embodiment of the present invention. The optical inspection apparatus 1 of the present embodiment changes the magnification of the imaging optical system 18 so that the observation magnification of the optical microscope can be changed according to the type of observation object. For example, in this embodiment, the magnification of the imaging optical system 18 is changed by changing the focal length of the relay lens 82 that forms an image of the sample 15 connected by the imaging lens 50 on the image sensor 19.
For this reason, the relay lens mechanism 82 of this embodiment has a turret structure in which a plurality of relay lenses 83a to 83c having different focal lengths are provided on a disk 84 that can be rotated about an axis 85 as shown in FIG. ing. By rotating the motor 86, the rotational position of the disk 84 is controlled. Accordingly, the focal length of the relay lens 82 can be switched by positioning a lens having a desired focal length among the lenses 83a to 83c on the optical axis a1 of the objective lens 14.

  Returning to FIG. 5, the optical inspection apparatus 1 changes the magnification of the imaging optical system 18 to change the observation magnification, and the focus of the relay lens 82 according to the control by the observation magnification change unit 94. An imaging optical system magnification changing unit 95 that switches the distance (magnification) is provided. The imaging optical system magnification changing unit 95 switches the focal length of the relay lens 82 by driving the motor 86 shown in FIG. 6 according to the control by the observation magnification changing unit 94.

As described above, as a method of switching the observation magnification, there are a method of switching the magnification of the objective lens of the optical microscope and a method of switching the magnification of the imaging lens for forming an image of the inspection object projected by the objective lens. However, if the observation magnification is increased with the imaging optical system, only the observation field is narrowed, and the illumination range of the illumination light that irradiates the sample does not change. There is a problem of illuminating a useless area.
Therefore, the optical inspection apparatus 1 of this embodiment changes the magnification of the condenser lens 40 in accordance with the focal length (magnification) of the imaging optical system 18 and projects the illumination light on the position of the first pinhole plate 30. Illumination intensity changing means 95 is provided for changing the intensity of illumination light applied to the sample 15 by changing the magnification.

FIG. 7 shows a schematic configuration of the condenser lens mechanism 40 that switches the magnification according to the illumination intensity changing unit 95. The condenser lens mechanism 40 includes a turret structure in which lenses 41a to 41c having a plurality of focal lengths are provided on a disk 42 that can be rotated about an axis 44 as a rotation axis. By rotating the motor 43, the rotational position of the disk 42 is controlled. As a result, of the lenses 41a to 41c, any lens corresponding to the magnification of the imaging optical system 18 can be positioned on the optical axis a2 of the illumination light, and the magnification of the condenser lens 40 can be switched.
The condenser lens mechanism 40 also includes a housing 45 that pivotally fixes the shaft 44 and fixes the motor 43, a linear motion guide 46 that guides the housing 45 along the optical axis a2, and a linear motion of the housing 45. And a motor 47 driven along the guide 46.

The illumination intensity changing unit 95 controls the motors 43 and 47 to control the focal length and the position of the condenser lens 40 corresponding to the magnification of the imaging optical system 18, thereby changing the observation magnification changing unit 94. The magnification of the condenser lens 40 is changed according to the magnification of the imaging optical system 18.
In this embodiment, the relay lens mechanism 82 and the condenser lens mechanism 40 are constituted by a plurality of switchable focal length lenses, but these two or more lens groups are moved to keep their focal positions. Alternatively, the zoom lens may be configured as a known zoom optical system that continuously changes the focal length.

FIG. 8 shows a schematic configuration diagram of an optical inspection apparatus according to a third embodiment of the present invention. In this embodiment, the illumination optical system 12 includes a variable magnification optical system 20, a condenser lens 40, and a relay lens 81 in order from the light source 11, as in the optical inspection apparatus shown in FIG. A fly-eye lens 60 is provided between the system 20. In this embodiment, a laser light source of deep ultraviolet (DUV) light using a solid laser having a wavelength of about 210 nm is used as the light source 11.
In the imaging optical system 18, the same components as those in the optical inspection apparatus described with reference to FIG.

The illumination light from the light source 11 is condensed at the position of the first pinhole plate 30 through the variable magnification optical system 20, the fly-eye lens 60, and the condenser lens 40. The variable magnification optical system 20 enlarges the size (diameter) of the light beam of the illumination light (laser beam) of the light source 11, converts it into a beam parallel to the optical axis, and enters the fly-eye lens 60.
The fly-eye lens 60 is a regular array of several small unit lenses, such as several to several tens, which are bundled so that their vertices are on the same plane. Each unit lens has the same radius of curvature r on both sides. And the vertices at both ends are the focal points when parallel light enters from the opposite side. Therefore, the focal length f _f is given by the following equation (1).
f _f = l = (n−1) × r / n (1)
Here, l is the lens thickness (length) of the fly-eye lens 60, r is the radius of curvature of each unit lens, and n is the refractive index. In this embodiment, calcium fluoride is used for the glass material, and the refractive index n is about 1.5.

The fly-eye lens 60 is disposed such that the rear apex thereof is substantially equal to the aperture stop position (front focal position) of the condenser lens 40. Then, the front vertex surface becomes conjugate with the position of the first pinhole plate 30, and the imaging magnification β is given by the following equation (2).
β = f _c / f _f (2)
f _c is the focal length of the condenser lens 40.
When the illumination light from the light source 11 is converted into parallel light by the variable magnification optical system 20 and is incident on the fly-eye lens 60, a light flux having a diameter L given by the following equation (3) is placed at the position of the first pinhole plate 30. An image of illumination light of uniform brightness having
L = βd = f _c / f _f × d (3)
Here, d is the diameter of the opening on the front apex surface of each unit lens of the fly-eye lens 60.

As is clear from the above equation (3), by changing the focal length f _f of the fly-eye lens 60, the diameter of the luminous flux of the illumination light at the position of the first pinhole plate 30 varies and passes through the minute pinhole. The illuminance changes, and the intensity of the illumination light applied to the sample 15 is changed.
Therefore, the illumination intensity changing unit 95 changes the magnification of the fly-eye lens 60 according to the magnification of the imaging optical system 18 changed by the observation magnification changing unit 94.

FIG. 9 shows a schematic configuration of a fly-eye lens mechanism 60 that switches the magnification according to the control of the illumination intensity changing unit 95. The fly eye lens mechanism 60 includes a plurality of fly eye lenses 61a to 61c having different magnifications and dimensions. These fly eye lenses 61 a to 61 c are provided on the disk 62. By rotating the motor 63 and rotating the disk 62 about the axis 64 as a rotation axis and controlling the rotation position of the disk 62, a desired lens among the fly-eye lenses 61a to 61c is optical axis a2 of the variable magnification optical system 20. Positioned above, the magnification of the fly-eye lens 60 is switched.
The illumination intensity changing unit 95 controls the motor 63 to control the magnification of the fly-eye lens 60 corresponding to the magnification of the imaging optical system 18.

  On the other hand, the cross-sectional dimension of the light beam emitted from the fly-eye lens 60 and incident on the condenser lens 40 is the same as the cross-sectional dimension of the parallel light beam emitted from the variable magnification optical system 20. Therefore, the illumination numerical aperture changing unit 93 can change the illumination numerical aperture by changing the cross-sectional dimension of the parallel light incident on the fly-eye lens 60 by changing the projection magnification of the variable magnification optical system 20.

Therefore, also in the present embodiment, when the optical system switching control unit 91 switches the optical system, the illumination numerical aperture changing unit 93 determines whether the current optical system is a confocal optical system or a normal bright field optical system. Accordingly, it is possible to cancel the fluctuation of the aperture illumination due to the attachment / detachment of the condensing optical element 31 by changing the illumination numerical aperture according to the above. Further, the illumination numerical aperture changing unit 93 does not depend on whether the current optical system is a confocal optical system or a normal bright field optical system (that is, regardless of the presence or absence of the condensing optical element 31). The number can be freely set according to the observation target.
In the embodiment shown in FIG. 8, the variable magnification optical system 20 is configured as a zoom optical system, but instead of this, the beam expander mechanism 20 described above with reference to FIG. 4 may be used.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical inspection apparatus used for inspecting a semiconductor such as a wafer or a mask and an illumination method thereof, and is particularly configured to be able to switch between a confocal optical system and a normal bright field optical system. It can be used for an optical inspection apparatus and its illumination method.

It is a schematic block diagram of the optical inspection apparatus by 1st Example of this invention. It is a figure which shows the two-dimensional arrangement | positioning of the pinhole in the 1st pinhole board shown in FIG. It is a perspective view of the 1st pinhole plate and condensing optical element which are shown in FIG. It is a schematic block diagram of the other Example of the variable magnification optical system shown in FIG. It is a schematic block diagram of the optical inspection apparatus by 2nd Example of this invention. It is a schematic block diagram of the imaging lens part shown in FIG. It is a schematic block diagram of the condenser lens mechanism shown in FIG. It is a schematic block diagram of the optical inspection apparatus by 3rd Example of this invention. It is a schematic block diagram of the fly eye lens mechanism shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 12 Illumination optical system 13 Beam splitter 14 Objective lens 15 Sample 16 Stage 18 Imaging optical system 19 Imaging device 20 Variable magnification optical system 30 1st pinhole plate 31 Micro lens array 32 2nd pinhole plate 40 Condenser lens 50 Connection Image lens 81, 82 Relay lens

Claims (12)

An optical type in which a detachable first pinhole plate for narrowing illumination light for illuminating a sample from a light source and a second pinhole plate for narrowing reflected light reflected from the sample by the illumination light are provided at conjugate positions. In inspection equipment,
An optical inspection apparatus comprising: a condensing optical element that condenses the illumination light incident on a pinhole on the first pinhole plate, which is attached and detached simultaneously with the first pinhole plate. A condenser lens provided between the first pinhole plate and the light source, the condenser lens disposed so that the first pinhole plate is located at a rear focal position or a conjugate position thereof;
A variable magnification optical system that projects a light source image of the light source at a variable focal magnification on the front focal position of the condenser lens;
An illumination numerical aperture changing means for changing an illumination numerical aperture by changing a projection magnification of the variable magnification optical system;
The optical inspection apparatus according to claim 1, further comprising: The variable magnification optical system includes a plurality of fly-eye lenses having different magnifications,
The optical inspection apparatus according to claim 2, wherein the optical inspection apparatus includes an illumination intensity changing unit that changes the intensity of illumination light irradiated on the sample by switching the plurality of fly-eye lenses. Inspection device. A condenser lens provided between the first pinhole plate and the light source, the condenser lens disposed so that the first pinhole plate is located at a rear focal position or a conjugate position thereof;
Illumination intensity changing means for changing the intensity of illumination light applied to the sample by changing the magnification of the condenser lens;
The optical inspection apparatus according to claim 1, further comprising: A variable magnification optical system that projects a light source image of the light source at a variable focal magnification on the front focal position of the condenser lens;
An illumination numerical aperture changing means for changing an illumination numerical aperture by changing a projection magnification of the variable magnification optical system;
The optical inspection apparatus according to claim 4, further comprising: An imaging optical system that forms an image on the observation surface of the reflected light reflected by the sample with the illumination light, and an imaging system magnification changing unit that changes the magnification of the imaging optical system,
The illumination intensity changing means changes an irradiation range of illumination light applied to the first pinhole plate according to a magnification of the imaging optical system. The optical inspection apparatus according to one item. A first pinhole plate that narrows the illumination light that illuminates the sample from the light source and a second pinhole plate that narrows the reflected light reflected by the sample, which are provided at conjugate positions with each other, are attached and detached. By the illumination method of the optical inspection apparatus that switches between the confocal optical system and the normal bright field optical system,
The illumination method characterized by attaching and detaching the condensing optical element which condenses the said illumination light which injects into the pinhole on the said 1st pinhole board with the said 1st and 2nd pinhole.   A condenser lens provided between the first pinhole plate and the light source, wherein a condenser lens is provided so that the first pinhole plate is located at a rear focal position or a conjugate position thereof; The illumination method according to claim 7, wherein the illumination numerical aperture is changed by changing a projection magnification of a light source image of the light source projected onto a front focal position of the condenser lens.   A plurality of fly-eye lenses with different magnifications are provided to project a light source image of the light source at the front focal position of the condenser lens, and the intensity of illumination light irradiated on the sample is changed by switching the plurality of fly-eye lenses The illumination method according to claim 8, wherein:   The optical inspection apparatus is a condenser lens provided between the first pinhole plate and the light source, and is arranged so that the first pinhole plate is positioned at a rear focal position or a conjugate position thereof. The illumination method according to claim 7, further comprising: changing a magnification of the condenser lens by changing a magnification of the condenser lens.   The illumination method according to claim 10, wherein the illumination numerical aperture is changed by changing a projection magnification of a light source image of the light source projected on a front focal position of the condenser lens.   In order to change the intensity of the illumination light applied to the sample, the illumination range of the illumination light applied to the first pinhole plate is changed according to the magnification of the imaging optical system of the optical inspection apparatus. The illumination method according to any one of claims 9 to 11, wherein

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