JP7050601B2 - Lighting method, imaging method, lighting device and imaging device - Google Patents

Description

The present invention relates to a lighting method, an imaging method, a lighting device, and an imaging device. For example, the present invention relates to a lighting method, an imaging method, a lighting device, and an imaging device for imaging a semiconductor wafer in order to inspect a pattern of a semiconductor wafer. Regarding.

The image pickup apparatus used for inspecting the semiconductor wafer on which the pattern is formed includes, for example, an imaging optical system and an illumination optical system. A line-type LED lighting unit may be used as a light source in the illumination optical system. The line-type LED lighting unit includes a plurality of LED light sources arranged in a line, and a cylindrical lens that collects the illumination light generated by the LED light sources.

Japanese Unexamined Patent Publication No. 2015-127653

The illumination optical system using the line-type LED lighting unit has room for improvement in increasing the amount of light received by the image pickup target and improving the throughput for acquiring the image to be imaged.

An object of the present invention is to solve such a problem, and to increase the amount of light received by an image pickup target and improve the throughput for acquiring an image to be imaged to be imaged. It is to provide a lighting device and an image pickup device.

In the illumination method according to the present invention, a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens for condensing illumination light generated from the plurality of light sources is arranged. An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, which is condensed by the illumination system condensing lens and incident on the upper end surface. Includes a step of arranging the optical waveguide emitted from the lower end surface and a step of illuminating the image pickup target with the illumination light emitted from the optical waveguide. With such a configuration, the amount of light received by the image pickup target can be increased.

Further, the imaging method according to the present invention is a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources. An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, which is condensed by the illumination system condensing lens and incident on the upper end surface. The step of arranging the optical waveguide in which the illumination light is emitted from the lower end surface, the step of illuminating the image pickup target with the illumination light emitted from the optical waveguide, and the light from the image pickup target illuminated by the illumination light. The present invention comprises a step of condensing, detecting the condensed light, and acquiring an image to be imaged. With such a configuration, it is possible to improve the throughput for acquiring the image to be imaged.

The illuminating device according to the present invention includes a line-shaped illuminating unit having a plurality of light sources arranged in a line in one direction and an illuminating system condensing lens that condenses the illuminating light generated from the plurality of light sources. An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The optical waveguide emitted from the optical waveguide is provided, and the image pickup target is illuminated with the illumination light emitted from the optical waveguide. With such a configuration, the amount of light received by the image pickup target can be increased.

Further, the image pickup apparatus according to the present invention is a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens for condensing illumination light generated from the plurality of light sources. An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condensing lens and incident on the upper end surface is said. The optical waveguide emitted from the lower end surface and the light from the imaging target illuminated by the illumination light emitted from the optical waveguide are condensed, and the condensed light is detected to capture the image of the imaging target. The imaging optical system to be acquired is provided. With such a configuration, it is possible to improve the throughput for acquiring the image to be imaged.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a lighting method, an image pickup method, a lighting device, and an image pickup device capable of increasing the amount of light received by an image pickup target and improving the throughput for acquiring an image of the image pickup target.

It is a schematic diagram which illustrates the structure of the image pickup apparatus which concerns on embodiment. It is a perspective view which illustrates the structure of the image pickup apparatus which concerns on embodiment. It is a figure exemplifying the light source and the illumination system condensing lens in the line-shaped illumination part of the image pickup apparatus which concerns on embodiment, (a) is a schematic view seen from the side, (b) is seen from above. It is a schematic diagram. It is a figure exemplifying the illumination system condensing lens in the line-shaped illumination part of the image pickup apparatus which concerns on embodiment, and (a) is the perspective view of the state before a plurality of lenses constituting a line-shaped fly-eye lens are arranged. (B) shows a perspective view of a state in which a plurality of lenses constituting the line-shaped fly-eye lens are arranged, and (c) shows a state of the line-shaped fly-eye lens viewed from the optical axis direction. .. It is a perspective view which illustrates the optical waveguide in the illumination optical system of the image pickup apparatus which concerns on embodiment. It is a figure which illustrated the revolver type bandpass filter switching mechanism in the image pickup apparatus which concerns on embodiment. It is a figure which illustrates the illumination optical system and the imaging optical system along the optical axis of the illumination light and the light from the image pickup object illuminated by the illumination light in the image pickup apparatus which concerns on embodiment. It is a flowchart which illustrates the image pickup method using the image pickup apparatus which concerns on embodiment. It is a figure which illustrates the illumination light and the light from the image pickup object in the image pickup apparatus which concerns on embodiment. It is a figure which illustrates the illumination light and the light from the image pickup target in the image pickup apparatus which does not use an optical waveguide. It is a figure which illustrates the light-receiving amount of the image pickup object in the image pickup apparatus which concerns on embodiment. It is a figure which exemplifies the throughput which acquires the image to be imaged in the image pickup apparatus which concerns on embodiment.

Hereinafter, a specific configuration of the present embodiment will be described with reference to the drawings. The following description shows preferred embodiments of the present invention, and the scope of the present invention is not limited to the following embodiments. In the following description, those with the same reference numerals indicate substantially the same contents.

(Embodiment)
The image pickup apparatus according to the embodiment will be described. FIG. 1 is a schematic diagram illustrating the configuration of the image pickup apparatus according to the embodiment. FIG. 2 is a perspective view illustrating the configuration of the image pickup apparatus according to the embodiment. As shown in FIGS. 1 and 2, the image pickup apparatus 1 includes an illumination optical system 10, an imaging optical system 20, and a stage 30. The image pickup apparatus 1 takes an image of the image pickup target 40 arranged on the stage 30. The image pickup target 40 is, for example, a semiconductor wafer having a pattern formed on the upper surface.

For the convenience of the description of the image pickup apparatus 1, the plane parallel to the upper surface of the stage 30 into which the XYZ orthogonal coordinate axes are introduced is defined as the XY plane, and the direction orthogonal to the upper surface of the stage 30 is defined as the Z axis direction. The upper side is the + Z axis direction.

First, as the configuration of the image pickup apparatus 1, the <illumination optical system>, the <imaging optical system>, and the <stage> will be described in order. After that, the <imaging method> using the imaging device 1 will be described, and finally the effects will be summarized.

<Illumination optical system>
First, the illumination optical system 10 will be described. The illumination optical system 10 includes a line-shaped illumination unit 11 and an optical waveguide 12. The line-shaped illumination unit 11 generates the illumination light L10.

FIG. 3 is a diagram illustrating the light source 13 and the illumination system condensing lens 14 in the line-shaped illumination unit 11 of the image pickup apparatus 1 according to the embodiment, and FIG. 3A is a schematic view viewed from the side. b) is a schematic view seen from above. As shown in FIGS. 3A and 3B, the line-shaped illumination unit 11 includes a plurality of light sources 13 and an illumination system condensing lens 14. The light source 13 is, for example, an LED (Light Emitting Diode). In the line-shaped illumination unit 11, the plurality of light sources 13 generate light having the same center wavelength. The plurality of light sources 13 are arranged side by side in a line in one direction. For example, the plurality of light sources 13 are arranged in a line in the X-axis direction. The illumination system condensing lens 14 condenses the illumination light L10 generated from the plurality of light sources 13. The illumination system condenser lens 14 includes, for example, a cylindrical lens extending in one direction. The illumination system condenser lens 14 may include a line-shaped fly-eye lens.

FIG. 4 is a diagram illustrating an illumination system condensing lens 14 in the line-shaped illumination unit 11 of the image pickup apparatus 1 according to the embodiment, and FIG. 4A shows a plurality of lenses 15 constituting the line-shaped fly-eye lens 14a. A perspective view of a state before being arranged is shown, (b) shows a perspective view of a state in which a plurality of lenses 15 constituting the line-shaped fly-eye lens 14a are arranged, and (c) is a line-shaped fly-eye. The state where the lens 14a is seen from the optical axis direction is shown.

As shown in FIG. 4, the illumination system condensing lens 14 may include, for example, a line-shaped fly-eye lens 14a. The line-shaped fly-eye lens 14a is a condenser lens in which a plurality of lenses 15 are arranged in a line shape. In the line-shaped fly-eye lens 14a, a plurality of lenses 15 are arranged in a line shape at a predetermined pitch. The predetermined pitch of the line-shaped flyeye lens 14a is the same pitch as the pitch in which the plurality of light sources 13 are lined up in a line shape. Therefore, each light source 13 is arranged on the optical axis of each lens 15. A diffuser plate may be arranged on the illumination system condenser lens 14.

As shown in FIGS. 1 and 2, the illumination optical system 10 may have a plurality of line-shaped illumination units 11. Each line-shaped illumination unit 11 includes a plurality of light sources 13 that generate illumination light L10 having a center wavelength different from that of the other line-shaped illumination units 11. Therefore, the illumination optical system 10 provided with the plurality of line-shaped illumination units 11 has a wavelength switching mechanism for the illumination light L10. Therefore, the illumination optical system 10 can switch the wavelength of the illumination light L10 that illuminates the image pickup target 40.

For example, the illumination optical system 10 has an illumination light L10 having a plurality of central wavelengths from ultraviolet light (Ultraviolet: UV) to infrared light (Infrared: IR), and each line-shaped illumination light L10 for white light. It may have an illumination unit 11. By switching the line-shaped illumination unit 11, the illumination optical system 10 can illuminate the image pickup target 40 with the illumination light L10 having a wavelength corresponding to each line-shaped illumination unit 11.

For example, the illumination optical system 10 includes a rotating shaft 16 that rotates about a central axis C extending in one direction, and a plurality of line-shaped lighting units 11 provided on the outer peripheral surface of the rotating shaft 16. .. The line-shaped illumination units 11 are arranged on the outer peripheral surface of the rotating shaft 16 that rotates about the central axis C extending in one direction at intervals in the outer peripheral direction. The outer peripheral direction is a direction of rotation about the central axis C. For example, the four line-shaped illumination units 11 are UV light sources that generate illumination light L10 having a plurality of central wavelengths on the ultraviolet light side. The four line-shaped illumination units 11 are arranged on the outer peripheral surface of the rotating shaft 16 at intervals of 45 [°].

Of the eight line-shaped illumination units 11, the remaining four line-shaped illumination units 11 are light sources of visible light that generate illumination light L10 having a plurality of center wavelengths on the infrared light side and illumination light L10 of white light. It has become. The four line-shaped illumination units 11 are arranged on the outer peripheral surface of the rotating shaft 16 at intervals of 45 [°]. Therefore, when the eight line-shaped illumination units 11 are viewed from the X-axis direction, the line-shaped illumination units 11 are arranged side by side on the outer peripheral surface of the rotating shaft 16 with an interval of 45 [°]. ..

FIG. 5 is a perspective view illustrating the optical waveguide 12 in the illumination optical system 10 of the image pickup apparatus 1 according to the embodiment. As shown in FIG. 5, the optical waveguide 12 is a transparent plate-shaped member. For example, the optical waveguide 12 contains quartz as a material. The optical waveguide 12 may contain a material other than quartz as long as it transmits light such as ultraviolet light and visible light.

The optical waveguide 12 has facing plate faces, facing side surfaces, and facing end faces. The facing plate surfaces are the upper surface 12a and the lower surface 12b. The upper surface 12a and the lower surface 12b have a larger area than the side surface and the end surface. The facing end faces are the upper end surface 12c and the lower end surface 12d. The lower end surface 12d faces the upper end surface 12c. The upper end surface 12c and the lower end surface 12d extend in one direction. For example, the upper end surface 12c and the lower end surface 12d extend in the X-axis direction. When the optical waveguide 12 is arranged, the thickness of the optical waveguide 12, that is, the length between the facing plate surfaces is the most efficient for the conditions such as NA in the imaging optical system 20. , And the position where the optical waveguide 12 is arranged is calculated by using a simulation or the like, and is arranged based on the calculation result.

The illumination light L10 emitted from the line-shaped illumination unit 11 is incident on the upper end surface 12c of the optical waveguide 12. The illumination light L10 incident on the upper end surface 12c of the optical waveguide 12 passes through the inside of the optical waveguide 12 and is emitted from the lower end surface 12d. The light transmission direction is a direction from the upper end surface 12c to the lower end surface 12d. In this way, the illumination light L10 condensed by the illumination system condenser lens 14 and incident on the upper end surface 12c is emitted from the lower end surface 12d. Then, the illumination optical system 10 illuminates the image pickup target 40 with the illumination light L10 emitted from the optical waveguide 12. From this point of view, the illumination optical system 10 can be said to be an illumination device that illuminates the image pickup target 40.

<Imaging optical system>
Next, the imaging optical system 20 will be described. The imaging optical system 20 collects the light from the image pickup target 40 illuminated by the illumination light L10, detects the focused light, and acquires an image of the image pickup target 40. As shown in FIGS. 1 and 2, the imaging optical system 20 includes an imaging system condensing lens 21 and a light receiving sensor 22. The imaging optical system 20 may include optical elements such as a bandpass filter 23 and a polarizer 24 in addition to the imaging system condensing lens 21 and the light receiving sensor 22. For example, when the line-shaped illumination unit 11 includes a white LED that generates white light as a light source 13, a bandpass filter 23 is combined to take an image. This makes it possible to take images in a large number of wavelength bands.

FIG. 6 is a diagram illustrating the revolver type bandpass filter switching mechanism 25 in the image pickup apparatus 1 according to the embodiment. As shown in FIG. 6, the imaging optical system 20 may have a revolver type bandpass filter switching mechanism 25. The bandpass filter switching mechanism 25 includes a plurality of bandpass filters 23. The bandpass filter switching mechanism 25 can be switched to each bandpass filter 23. As described above, the image pickup apparatus 1 uses the bandpass filters 23 having a plurality of different wavelength bands and the revolver type bandpass filter switching mechanism 25 to perform imaging with a wavelength band larger than the number of the linear illumination units 11. Can be made possible. For example, as shown in FIG. 6, when the bandpass filters 23 having four different wavelength bands are switched with respect to the light source 13 of one white LED, the bandpass filters 23 are matched with the seven line-shaped illumination units 11 of the monochromatic LED. Therefore, it is possible to perform imaging in a total of 11 wavelength bands.

FIG. 7 shows the illumination optical system 10 and the imaging optical system 20 along the optical axis K of the light L20 from the image pickup target 40 illuminated by the illumination light L10 and the illumination light L10 in the image pickup apparatus 1 according to the embodiment. It is an exemplary figure. As shown in FIG. 7, the illumination light L10 generated by the light source 13 in the line-shaped illumination unit 11 and condensed by the illumination system condenser lens 14 passes through the optical waveguide 12 and is emitted from the lower end surface 12d. The illumination light L10 emitted from the lower end surface 12d of the optical waveguide 12 illuminates the image pickup target 40.

The imaging system condensing lens 21 condenses the light L20 from the image pickup target 40 illuminated by the illumination light L10. The light L20 from the image pickup target 40 illuminated by the illumination light L10 includes the reflected light reflected by the illumination light L10 on the image pickup target 40. Further, the light L20 from the image pickup target 40 may include diffracted light or the like in the image pickup target 40.

The light receiving sensor 22 detects the light L20 from the image pickup target 40 condensed by the imaging system condenser lens 21 and acquires the image of the image pickup target 40. It is preferable that the imaging optical system 20 detects light L20 in the wavelength range from ultraviolet light to infrared light by using one imaging system condensing lens 21 and one light receiving sensor 22. However, if it is not possible to detect the light L20 in the wavelength range from ultraviolet light to infrared light using one imaging system condenser lens 21 and one light receiving sensor 22, a plurality of imaging system collections. The optical lens 21 and the plurality of light receiving sensors 22 may be combined to detect the light L20 in the wavelength range from the ultraviolet light to the infrared light. For example, the light receiving sensor 22 may be divided into a light receiving sensor that detects light having a central wavelength of ultraviolet light, a light receiving sensor that detects light having a central wavelength of visible light, and a light receiving sensor that detects light having a central wavelength of infrared light. good. In this case, the imaging optical system 20 of the image pickup apparatus 1 can be switched depending on the wavelength.

<Stage>
Next, the stage 30 will be described. As shown in FIGS. 1 and 2, the stage 30 is provided below the illumination optical system 10 and the imaging optical system 20. An image pickup target 40 is arranged on the stage 30. The illumination optical system 10 illuminates the image pickup target 40 arranged on the stage 30 with the illumination light L10 emitted from the line-shaped illumination unit 11 via the optical waveguide 12. For example, the illumination light L10 emitted from the optical waveguide 12 is illuminated so as to be incident on the upper surface of the image pickup target 40 at a predetermined incident angle. The light from the image pickup target 40 illuminated by the illumination light L10 is focused on the imaging optical system 20 at the same emission angle as the incident angle. The incident angle and the exit angle do not have to be the same. Further, the incident angle and the emitted angle can be set independently.

The stage 30 can slide and move in the Y-axis direction. For example, the illumination light L10 is illuminated on the image pickup target 40 while the stage 30 on which the image pickup target 40 is arranged is slid and moved in the Y-axis direction, and the image pickup target 40 is imaged by the imaging optical system 20.

<Imaging method>
Next, as an operation of the image pickup device 1, an image pickup method using the image pickup device 1 will be described. FIG. 8 is a flowchart illustrating an image pickup method using the image pickup apparatus 1 according to the embodiment. As shown in step S11 of FIG. 8, first, the line-shaped illumination unit 11 is arranged. Specifically, the line-shaped illumination unit 11 having a plurality of light sources 13 arranged in a line in one direction and an illumination system condensing lens 14 for condensing the illumination light L10 generated from the plurality of light sources 13. Place it.

When arranging the line-shaped illumination unit 11, a plurality of line-shaped illumination units 11 may be prepared. Each line-shaped illumination unit 11 may include a plurality of light sources 13 that generate illumination light L10 having a center wavelength different from that of the other line-shaped illumination units 11. Further, each line-shaped illumination unit 11 may be arranged on the outer peripheral surface of the rotating shaft 16 rotating around the central axis C extending in one direction at intervals in the outer peripheral direction.

Next, as shown in step S12, the optical waveguide 12 is arranged. Specifically, it is an optical waveguide 12 having an upper end surface 12c extending in one direction and a lower end surface 12d facing the upper end surface 12c, and is focused by an illumination system condensing lens 14 and incident on the upper end surface 12c. An optical waveguide 12 in which the light L10 emits from the lower end surface 12d is arranged.

Next, as shown in step S13, the image pickup target 40 is illuminated with the illumination light L10. Specifically, the image pickup target 40 is illuminated with the illumination light L10 emitted from the optical waveguide 12. The illumination light L10 may be white light generated from the white LED.

Next, as shown in step S14, the image of the image pickup target 40 is acquired. Specifically, the light from the image pickup target 40 illuminated by the illumination light L10 is condensed, and the condensed light is detected to acquire the image of the image pickup target 40. The image may be acquired by detecting the light transmitted through the bandpass filter.

Next, as shown in step S15, it is determined whether or not to acquire the image of the image pickup target 40 even with the illumination light L10 having another wavelength. In the case of Yes, which acquires an image of the image pickup target 40 even with illumination light L10 having another wavelength, another line-shaped illumination unit 11 is arranged as shown in step S16. Specifically, the rotation shaft 16 is rotated around the central axis C. Then, the illumination light L10 emitted from the other line-shaped illumination unit 11 is made to enter the upper end surface 12c of the optical waveguide 12. Then, steps S13 to S15 are repeated.

On the other hand, in step S15, if No, the image of the image pickup target 40 is not acquired by the illumination light L10 having another wavelength, the process ends. In steps S11 to S13, the image pickup target 40 is illuminated with the illumination light L10. From this point of view, steps S11 to S13 can be referred to as an illumination method for the image pickup target 40.

Next, the effect of the image pickup apparatus 1 of the present embodiment will be described.
The image pickup apparatus 1 of the present embodiment has an optical waveguide 12. The optical waveguide 12 can guide the illumination light L10 to the image pickup target 40 by the reflection of the illumination light L10 inside the optical waveguide 12, and can increase the amount of light received by the image pickup target 40.

FIG. 9 is a diagram illustrating the illumination light L10 and the light L20 from the image pickup target 40 in the image pickup apparatus 1 according to the embodiment. FIG. 10 is a diagram illustrating the illumination light L110 and the light L120 from the image pickup target 40 in an image pickup device that does not use the optical waveguide 12. As shown in FIG. 9, the optical waveguide 12 of the image pickup apparatus 1 of the present embodiment suppresses the illumination light L10 incident inside the optical waveguide 12 from diffusing to the outside, and increases the amount of light received by the image pickup target 40. be able to. Then, the light L20 from the image pickup target 40 received by the light receiving sensor 22 can be increased.

On the other hand, as shown in FIG. 10, in the image pickup apparatus that does not use the optical waveguide 12, the illumination light L110 is diffused and the light receiving amount of the image pickup target 40 cannot be increased. Then, the light L120 from the image pickup target 40 received by the light receiving sensor 22 cannot be increased.

As shown in FIG. 10, in the image pickup apparatus that does not use the optical waveguide 12, the light receiving sensor 22 receives all of the light L120 from the image pickup target 40 illuminated by the illumination light L110 of the predetermined luminous flux emitted from the linear illumination unit 11. Cannot receive light. The light receiving sensor 22 receives only a part of the light L120 from the image pickup target.

On the other hand, as shown in FIG. 9, in the image pickup apparatus 1 of the present embodiment, the light receiving sensor 22 receives all the light L20 from the image pickup target 40 illuminated by the illumination light L10 of the predetermined luminous flux emitted from the line-shaped illumination unit 11. It can receive light. That is, in the present embodiment, the light L120, which should have deviated from the NA of the imaging system condenser lens 21 shown in FIG. 10, is transmitted through the optical waveguide 12 as shown in FIG. 9, so that the light receiving sensor 22 is transmitted. It is possible to put the light L20 within the light receiving range of. Therefore, the amount of light detected by the light receiving sensor 22 can be increased.

FIG. 11 is a diagram illustrating the amount of light received by the image pickup target 40 in the image pickup apparatus 1 according to the embodiment. In FIG. 11, conditions 3 and 4 show the case of the present embodiment, and conditions 1 and 2 show the case of a comparative example in which the optical waveguide 12 is not used.

Condition 1 is the result of simulating the amount of light received by the image pickup target 40 in the image pickup device of the comparative example in which the illumination system condenser lens 14 is a cylindrical lens and the optical waveguide 12 is not used. The light receiving amount in the case of condition 1 is (1.01E-04), and this value is set to 1.

Condition 2 is a result of simulating the amount of light received by the image pickup target 40 in the image pickup device of the comparative example in which the illumination system condenser lens 14 is a line-shaped flyeye lens 14a and the optical waveguide 12 is not used. The light receiving amount in the case of the condition 2 is (8.11E-05), and the relative intensity ratio with respect to the case of the condition 1 is 0.8.

Condition 3 is a result of simulating the amount of light received by the image pickup target 40 in the image pickup apparatus 1 of the embodiment in which the illumination system condenser lens 14 is a cylindrical lens and the optical waveguide 12 is used. The light receiving amount in the case of the condition 3 is (1.99E-04), and the relative intensity ratio with respect to the case of the condition 1 is 2.

Condition 4 is a result of simulating the amount of light received by the image pickup target 40 in the image pickup apparatus of the embodiment in which the illumination system condenser lens 14 is a line-shaped flyeye lens 14a and the optical waveguide 12 is used. The light receiving amount in the case of the condition 4 is (4.06E-04), and the relative intensity ratio with respect to the case of the condition 1 is 4.

As described above, the amount of light received can be doubled by using the optical waveguide 12 as compared with the case of condition 1 in which the illumination system condenser lens 14 is used as a cylindrical lens and the optical waveguide 12 is not used. Further, with respect to the case of condition 1, the light receiving amount can be quadrupled by using the illumination system condensing lens 14 as the line-shaped flyeye lens 14a and using the optical waveguide 12.

FIG. 12 is a diagram illustrating the throughput for acquiring an image of the image pickup target 40 in the image pickup apparatus 1 according to the embodiment. For example, the throughput in the case of imaging with the illumination light L10 having a short wavelength of 285 [nm] is shown. By increasing the amount of light received by the image pickup target 40, the time required for image pickup can be shortened and the throughput can be improved. The throughput is, for example, the number of wafers per hour. The throughput of imaging the image pickup target 40 having different reflectances in the case of no polarization and the case of with polarization by the polarizer 24 is shown.

As shown in FIG. 12, in the image pickup apparatus of the comparative example of the condition 1 in which the illumination system condenser lens 14 is a cylindrical lens and the optical waveguide 12 is not used, the reflectance is 10%, 25% and the reflectance is 10% and 25%. The 50% throughput is 1.5, 4 and 7, respectively. With polarization, the reflectances of 10%, 25% and 50% are 0.7, 1.5 and 3, respectively.

In the image pickup apparatus 1 of the embodiment of the condition 3 in which the illumination system condenser lens 14 is a cylindrical lens and the optical waveguide 12 is used, the throughputs of 10%, 25%, and 50% are unpolarized and the reflectances are 10%, 25%, and 50%. 3, 8 and 14, respectively. With polarization, the reflectances of 10%, 25% and 50% are 1.5, 3 and 7, respectively.

In the image pickup apparatus 1 of the embodiment of the condition 4 in which the illumination system condensing lens 14 is a line-shaped fly-eye lens 14a and the optical waveguide 12 is used, the reflectance is 10%, 25%, and 50% without polarization. The throughputs of are 6, 16 and 29, respectively. With polarization, the reflectances of 10%, 25% and 50% are 3, 7 and 14, respectively. As described above, in the image pickup apparatus 1 according to the embodiment, the throughput can be significantly improved.

The image pickup apparatus 1 of the present embodiment has a plurality of line-shaped illumination units 11, and each line-shaped illumination unit 11 generates illumination light L10 having a different center wavelength. Therefore, the image pickup target 40 can be imaged with the illumination light L10 having a different wavelength. As a result, the relationship between the film thickness, line width, depth, etc. constituting the pattern and the reflectance according to the wavelength of the illumination light L10 can be obtained, and the image pickup target can be imaged at the optimized wavelength. Can be done.

Further, by using the illumination light L10 as white light and detecting the light transmitted through the plurality of bandpass filters 23 to acquire an image, it is possible to take an image in a large number of wavelength bands. For example, when eight line-shaped lighting units 11 are prepared, the seven line-shaped lighting units 11 include a single-color LED light source 13, and one line-shaped lighting unit 11 includes a white LED light source 13. To do so. If all eight line-shaped illumination units 11 include a light source 13 of a monochromatic LED, only eight types of wavelength bands can be imaged. However, by including the light source 13 of one white LED and using a plurality of bandpass filters 23 having different wavelength bands and a switching mechanism thereof, for example, a revolver type bandpass filter switching mechanism 25, the result is increased. It is possible to take images in many wavelength bands. For example, it is possible to perform imaging in 11 wavelength bands.

Although the embodiments of the present invention have been described above, the present invention includes appropriate modifications that do not impair the purpose and advantages thereof, and is not limited by the above embodiments.

1 Imaging device 10 Illumination optical system 11 Line-shaped illumination unit 12 Optical waveguide 12a Upper surface 12b Lower surface 12c Upper end surface 12d Lower end surface 13 Light source 14 Illumination system Condensing lens 14a Line-shaped fly-eye lens 15 Lens 16 Rotating axis 20 Imaging optical system 21 Imaging system Condensing lens 22, 22a, 22b, 22c Light receiving sensor 23 Bandpass filter 24 Polarizer 25 Revolver type bandpass filter switching mechanism 30 Stage 40 Imaging target C Central axis K Optical axis L10, L110 Illumination light L20, L120 Light

Claims (12)

A step of arranging a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The step of arranging the optical waveguide emitted from
A step of illuminating an image pickup target with the illumination light emitted from the optical waveguide,
Equipped with
The illumination system condenser lens includes a line-shaped fly-eye lens in which a plurality of lenses are arranged in a line at the same pitch as the pitch in which the plurality of light sources are arranged in a line.
An illumination method in which each light source is arranged on the optical axis of each lens . A step of arranging a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The step of arranging the optical waveguide emitted from
A step of illuminating an image pickup target with the illumination light emitted from the optical waveguide,
Equipped with
The illumination system condenser lens is an illumination method including a cylindrical lens extending in one direction . A step of arranging a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The step of arranging the optical waveguide emitted from
A step of illuminating an image pickup target with the illumination light emitted from the optical waveguide,
Equipped with
In the step of arranging the line-shaped lighting unit,
Prepare a plurality of the line-shaped lighting units and prepare them.
Each of the line-shaped illumination units includes the plurality of light sources that generate the illumination light having a center wavelength different from that of the other line-shaped illumination units.
A lighting method in which the line-shaped lighting units are arranged at intervals in the outer peripheral direction on the outer peripheral surface of a rotating shaft that rotates around a central axis extending in one direction . In the step of arranging the line-shaped lighting unit,
Prepare a plurality of the line-shaped lighting units and prepare them.
Each of the line-shaped illumination units includes the plurality of light sources that generate the illumination light having a center wavelength different from that of the other line-shaped illumination units.
The line-shaped illumination units are arranged at intervals in the outer peripheral direction on the outer peripheral surface of the rotating shaft that rotates around the central axis extending in one direction.
The lighting method according to claim 1 or 2 . A step of arranging a line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The step of arranging the optical waveguide emitted from
A step of illuminating an image pickup target with the illumination light emitted from the optical waveguide,
A step of condensing the light from the image pickup target illuminated by the illumination light, detecting the focused light, and acquiring an image of the image pickup target.
Imaging method with. In the step of illuminating the image pickup target with the illumination light, the illumination light is set to white light.
In the step of acquiring the image to be imaged, the light transmitted through the bandpass filter is detected to acquire the image.
The imaging method according to claim 5. A line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The optical waveguide emitted from
Equipped with
The illumination system condenser lens includes a line-shaped fly-eye lens in which a plurality of lenses are arranged in a line at the same pitch as the pitch in which the plurality of light sources are arranged in a line.
Each light source is arranged on the optical axis of each lens.
A lighting device that illuminates an image pickup target with the illumination light emitted from the optical waveguide. A line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The optical waveguide emitted from
Equipped with
The illumination system condenser lens includes the cylindrical lens extending in one direction.
A lighting device that illuminates an image pickup target with the illumination light emitted from the optical waveguide. A line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The optical waveguide emitted from
Equipped with
It has a plurality of line-shaped illumination units.
Each of the line-shaped illumination units includes the plurality of light sources that generate the illumination light having a center wavelength different from that of the other line-shaped illumination units.
Each of the line-shaped illumination units is arranged on the outer peripheral surface of the rotating shaft extending around the central axis extending in one direction at intervals in the outer peripheral direction.
A lighting device that illuminates an image pickup target with the illumination light emitted from the optical waveguide. It has a plurality of line-shaped illumination units.
Each of the line-shaped illumination units includes the plurality of light sources that generate the illumination light having a center wavelength different from that of the other line-shaped illumination units.
Each of the line-shaped illumination units is arranged on the outer peripheral surface of the rotating shaft extending around the central axis extending in one direction at intervals in the outer peripheral direction.
The lighting device according to claim 7 . A line-shaped illumination unit having a plurality of light sources arranged in a line in one direction and an illumination system condensing lens that condenses the illumination light generated from the plurality of light sources.
An optical waveguide having an upper end surface extending in one direction and a lower end surface facing the upper end surface, and the illumination light collected by the illumination system condenser lens and incident on the upper end surface is the lower end surface. The optical waveguide emitted from
An imaging optical system that collects light from an image pickup target illuminated by the illumination light emitted from the optical waveguide, detects the focused light, and acquires an image of the image pickup target.
An image pickup device equipped with. The plurality of light sources include a light source that produces white light.
The imaging optical system includes a bandpass filter that transmits the light.
The imaging device according to claim 11.

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