JP2000295639A - Illumination device for inspecting solid-state imaging device and adjustment tool used therefor - Google Patents

Abstract

(57) [Summary] [Problem] To surely remove dust attached to the cover glass.
Provided is a lighting device for inspecting a solid-state imaging device that can detect front and back. SOLUTION: One vertical illumination optical system and a plurality of oblique illumination optical systems are provided, and in each illumination optical system, a light source 10 is provided.
From the lens as Koehler illumination by the lens system 11,
The surface of the solid-state imaging device to be inspected, which is located at the rear focal position of the lens system 11, is irradiated. The illumination angle of the oblique illumination optical system is variable. If there is a defect in the solid-state imaging device, even if the irradiation angle of the oblique illumination optical system is changed, the device whose output is abnormal does not change, but the shadow of dust attached to the cover glass is
When the irradiation angle of the oblique illumination optical system is changed, the position changes, and the element whose output is abnormal changes. Therefore, the solid-state image pickup element and the dust adhering to the cover glass can be distinguished and detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an illumination device for inspecting a solid-state imaging device and an adjustment tool used for the same.

[0002]

2. Description of the Related Art Solid-state imaging devices have been used in a wide range of fields as two-dimensional optical sensors. In recent years, with the spread of electronic cameras, those having a large number of pixels have been put into practical use, and have exceeded two million pixels. Things are also being used. Also, in order to maximize the amount of light received by the element of the unit pixel or to set the light receiving direction to a specific direction,
Those with a microlens on the front are also in practical use.

In such a solid-state imaging device manufacturing line, it is necessary to inspect all the elements of the unit pixel for defects. This inspection has been performed by illuminating the solid-state imaging device from the vertical direction with uniform illumination light and checking whether the output from each device is a specified value. FIG. 9 shows an example of the lighting device.

The light emitted from the light source 10 is incident on a fly-eye integrator 15 using a collector lens 14. At the exit of the fly-eye integrator 15, the number of fly-eye lenses whose light source images are effective is formed. By locating this light source image at the front focal position of the condenser lens 16, the illumination surface (solid-state imaging device surface) 17 is illuminated as Koehler illumination by the condenser lens 16. The irradiation surface 17 is disposed so as to be located at the rear focal position of the condenser lens 16, thereby making the illumination light telecentric. That is, the Koehler illumination method and the fly-eye integrator 15 are used to improve illumination uniformity.

[0005] The inspection of the solid-state imaging device alone is performed by the method described above. After the solid-state imaging device is packaged, a cover glass is provided in front of the light receiving surface. If dust adheres to this cover glass, it adversely affects the imaging, so the inspection is performed again after the cover glass is attached. This inspection is also performed by irradiating the solid-state imaging device with vertical illumination light and measuring the output.

At this time, the inspection is performed while changing the F value of the illumination optical system in order to distinguish the dust from the defect of the solid-state imaging device. When the F value is made brighter (smaller), the depth of focus of the optical system becomes shallower, so that an image of dust not present on the light receiving surface is blurred. On the other hand, if the defect is a defect of the solid-state image sensor, no blur occurs. Therefore, whether or not the blur occurs or not is determined as dust adhering to the cover glass or a defect of the solid-state image sensor.

[0007]

However, in order to obtain a small F value required for this inspection, it is necessary to increase the number of lenses of the optical system, so that the cost is increased and the outer diameter of the lens is increased. There was a problem that it became large. Furthermore, this dust inspection method has a problem in that it is not possible to determine whether dust attached to the cover glass is attached to the front surface or the back surface of the cover glass.

Further, in recent solid-state imaging devices,
In some cases, the incident direction is restricted to an oblique direction by a microlens provided on the surface. In order to make the irradiation light incident on such a solid-state imaging device, an illumination optical system having a very small F value is required, and it is virtually impossible to design such an optical system. There was also a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to reliably detect dust adhering to a cover glass by distinguishing the front and back sides without reducing the F value of the illumination optical system. The object of the present invention is to provide a lighting device for solid-state imaging device inspection capable of inspecting a solid-state imaging device capable of inspecting a solid-state imaging device in which the incident direction is restricted to an oblique direction by a microlens provided on the surface. An object of the present invention is to provide a lighting device for lighting. It is another object of the present invention to provide an adjustment tool used for adjusting such a lighting device for inspecting a solid-state imaging device.

[0010]

A first means for solving the above problems is an illumination (vertical illumination) optical system in which the optical axis is perpendicular to the solid-state imaging device to be inspected, An illumination (oblique illumination) optical system inclined with respect to the element, wherein an illumination angle (incident angle) of the oblique illumination optical system is variable. An apparatus (claim 1).

In this means, in addition to the vertical illumination optical system similar to the conventional one, an oblique illumination optical system having a variable illumination angle is provided. When the solid-state imaging device is illuminated by changing the illumination angle of the oblique illumination optical system, the dust shadow adhering to the cover glass moves. Therefore, if there is an element with a small output (dark), even if the illumination angle of the oblique illumination optical system is changed, if the element with a small output (dark) does not change, it is a defect of the solid-state imaging device and the output is small ( If the (dark) element changes, it can be seen that the influence is due to the shadow of dust attached to the cover glass. Further, it is possible to determine whether dust adheres to the front surface or the rear surface of the cover glass based on the amount of movement of the dust shadow when the illumination angle is changed by a predetermined angle.

Further, since the illumination angle (incident angle) of the oblique illumination optical system can be greatly changed, the solid-state image pickup device in which the incident direction is obliquely limited by a microlens provided on the surface is also applicable. Light can be emitted from an oblique direction, and the inspection of the solid-state imaging device itself can be reliably performed.

In the present means (claim 1), the variable illumination angle of the oblique illumination optical system means only the configuration in which the illumination angle is variable by moving one unit of the illumination device. However, the present invention also includes a configuration in which a plurality of units of lighting devices having different lighting angles are switched to change the lighting angle. This means (claim 1) includes changing the illumination angle and rotating the oblique illumination optical system about an axis perpendicular to the solid-state imaging device to be inspected. In the case where the projection light is projected onto the light source, there is included one that emits irradiation light from a 360 ° irradiation direction.

[0014] A second means for solving the above-mentioned problems is as follows.
The first means, wherein the oblique illumination optical system projects approximately 90% when projected onto a plane parallel to the imaging surface of the solid-state imaging device to be tested.
The present invention is characterized in that it has four illumination optical systems arranged every ° (claim 2).

As described above, the oblique illumination optical system is rotated about an axis perpendicular to the solid-state image sensor to be inspected, and the oblique illumination light is irradiated from a direction of 360 ° to inspect the solid-state image sensor. The device can be complete,
There is a problem that the inspection is time-consuming because the mechanism is complicated and it is necessary to rotate while changing the illumination angle.

In this means, since the oblique illumination optical system has four illumination optical systems arranged at approximately 90 ° intervals, the inspection cannot be performed as strictly as the above-mentioned apparatus. Since the light is incident from four directions that are substantially perpendicular to each other, the light can be incident on all the unit elements of the solid-state imaging device.

Further, as will be described later in the description of the embodiments of the present invention, since irradiation is performed from four directions, when the illumination angle is changed, the shadow of dust may come off the image sensor surface. Moreover, since the dust of the dust attached to the back surface of the cover glass appears to increase with an increase in the illumination angle even if the movement is small, the dust can be reliably detected. .

The term "almost 90 degrees" does not need to be exactly 90 degrees, but means that it is sufficient to irradiate from approximately four directions of front, rear, left and right. Depending on the structure and the accuracy required for inspection,
The permissible range can be easily determined by those skilled in the art.

The scope of the present invention (claim 2) includes those having another oblique illumination optical system in addition to the four oblique illumination optical systems. Increasing the number of oblique illumination optics allows more costly but more rigorous inspection.

A third means for solving the above-mentioned problem is as follows.
The first means or the second means, wherein at least one of the vertical illumination optical system and the oblique illumination optical system includes an illumination lens, and an optical fiber having an exit at one focal position of the illumination lens. Wherein the test solid-state imaging device is arranged at the other focal position of the illumination lens (Claim 3).
It is.

In this means, one or a plurality of optical fibers are used instead of the conventionally used fly-eye integrator, whereby light is guided from the light source and the end face is used as a pseudo light source. I have. Then, the exit of the optical fiber is positioned at one focal position of the illumination lens, and the test solid-state imaging device is positioned at the other focal position of the illumination lens, thereby realizing Koehler illumination having telecentricity.

In particular, when the oblique illumination optical system has such a configuration, it is not necessary to move the light source when the illumination angle is changed, so that the configuration of the apparatus is simplified. In addition, by using an optical fiber with a small bundle diameter, the F value of the illumination light increases, so that the uniformity of illumination during oblique irradiation can be improved. Further, if light is incident on a plurality of optical fibers by one light source, the light source can be shared by a plurality of illumination optical systems.

Note that "at least one of the vertical illumination optical system and the oblique illumination optical system" means that when the oblique illumination optical system is composed of a plurality of illumination devices, at least one of the plurality of optical devices is the optical fiber. Is sufficient, and it does not necessarily mean that all the illuminating devices of the oblique illumination optical system need to have such a configuration.

A fourth means for solving the above-mentioned problem is:
An adjustment tool for adjusting the oblique illumination optical system in any one of the first to third means, comprising: a pinhole; a lens for receiving light passing through the pinhole; An adjustment tool comprising a screen or a light receiving element for receiving light passing through the adjustment tool.

When this means is used, the pinhole is positioned at a position corresponding to the surface of the solid-state imaging device to be inspected, and irradiation light passing through the pinhole is received by a lens and guided onto a screen. Ideally, the front focus of the lens is matched to the pinhole position, and the parallel light through the lens is directed to the screen or light receiving element. The position of the illumination optical system can be easily adjusted by adjusting the position of the illumination optical system while viewing the image of the irradiation light projected on the screen or the output of the light receiving element.

Further, the position of the pinhole is moved to a position corresponding to each part of the solid-state imaging device to be inspected, and it is confirmed whether the telecentricity is sufficient by observing a change in the image of the irradiation light. You can also.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is a figure showing an example. In FIG. 1, reference numeral 10 denotes a light source, 11 denotes a lens system, 12 denotes a solid-state image sensor to be inspected, and 13 denotes an angle corresponding to an F value of one pseudo light source in the lens system. In the following drawings, the same components are denoted by the same reference numerals, and overlapping description is omitted.

The lens system 11 in FIG. 1 has the same configuration as the lens system shown in FIG. That is, referring to FIG. 9 again, the light emitted from the light source 10 is reflected by the fly-eye integrator 1 using the collector lens 14.
5 At the exit of the fly-eye integrator 15, the number of fly-eye lenses whose light source images are effective is formed. By locating this light source image at the front focal position of the condenser lens 16, the illumination surface (solid-state imaging device surface) 17 is used as Koehler illumination by the condenser lens 16.
To illuminate. The irradiation surface 17 is arranged so as to be located at the rear focal position of the condenser lens 16, thereby ensuring the telecentricity of the illumination light. That is, the Koehler illumination method and the fly-eye integrator 15 are used to improve illumination uniformity.

FIG. 1 shows one vertical illumination optical system and two oblique illumination optical systems. A cross-sectional view of the vertical illumination optical system cut in a direction perpendicular to the paper about the optical axis is also the same as FIG. That is, four oblique illumination optical systems are provided at intervals of 90 ° in the plan view. The vertical illumination optical system and the oblique illumination optical system
Although the optical system itself is the same, in each oblique illumination optical system, the angle ω that the optical axis forms with the optical axis of the vertical illumination optical system is variable, so that the illumination angle of oblique illumination is variable. Have been. The optical axis of each oblique illumination optical system and the optical axis of the vertical illumination optical system intersect at one point, and that point is located at the center of the surface of the solid-state image sensor 12 to be inspected.

In the case of oblique illumination, the illumination area expands in the illumination direction by 1 / cosω, but the illumination light is telecentric,
In addition, when the angle 13 corresponding to the F value of one pseudo light source is small (the depth of focus is large), only the irradiation intensity is reduced as compared with the vertical illumination, and it hardly contributes to the deterioration of the illumination uniformity.

FIG. 2 is a diagram for explaining that dust attached to the cover glass can be detected by changing the illumination angle of the oblique illumination optical system. In FIG.
Numeral 30 is a cover glass, 31 is dust attached to the surface of the cover glass 30, and 32 is dust attached to the back surface of the cover glass 30.

The shadow of the dust 32 on the back surface has a moving distance x2 in accordance with the inclination angle (illumination angle) ω of the oblique illumination optical system and the gap d2 between the cover glass 30 and the solid-state image sensor 12.
Is changed, and the shadow distance of the dust on the surface changes the moving distance x1 according to the illumination angle ω of the oblique illumination optical system, the thickness d1 of the cover glass 30, and the d2. That is, assuming that the refractive index of the cover glass 30 is n, x1 = d1 * tan {sin ^-1 (sin ω / n)} + x2 x2 = d2 * tan ω.

Table 1 shows the illumination angle ω and the thickness d of the cover glass.
1 (the refractive index is constant and n = 1.5) and the distance d2
Are moved distances x1 and x2 when the value of is changed.

When one pixel on the non-detection solid-state image pickup device 12 is broken, a defect on the picked-up image corresponding to this pixel appears, but this is indistinguishable from dust. However, the position of the defect on the captured image does not change even if the illumination angle ω is changed, whereas the position of the shadow moves in the case of dust, so that the present invention enables the determination.

[0035]

[Table 1]

FIG. 3 shows how dust shadows appear on an image picked up by the non-detection solid-state image sensor 12 with respect to vertical illumination and oblique illumination. In the case of a single oblique illumination optical system, only one direction of movement occurs, and the shadow of the dust 31 on the front surface is easy to discriminate because the movement amount is large. It becomes difficult. Further, when there is dust at the end of the non-detection solid-state imaging device 12, the dust may not be imaged due to the movement.

In order to improve this, in the embodiment shown in FIG. 1, oblique illumination from four directions is used.
In the case of oblique illumination from four directions, as shown in FIG. 3, it is determined that the shadow of the dust 32 on the back surface has become larger due to the movement. Further, since the image of the dust at the end of the non-detection solid-state imaging device 12 does not disappear from the imaging range, it is possible to determine the dust in the entire imaging range of the non-detection solid-state imaging device 12.

Further, in the embodiment shown in FIG. 1, since the illumination angle ω is variable, a special microlens is used, and even in a solid-state image pickup device in which “shaking” of light occurs in vertical illumination, Light can be made incident from a direction in which “blur” does not occur, and inspection of all elements can be performed. Further, by attaching a color filter, a light amount adjustment filter, a shutter, and the like to the light source, it is possible to simultaneously control the color, the light amount, and the like.

As described above, in the embodiment shown in FIG. 1, the fly-eye integrator 15 shown in FIG. The fly-eye integrator 15 is formed by bundling a number of rod-shaped transparent bodies such as glass. Each of the rod-shaped transparent bodies has a convex cross-section on an entrance side and an exit side. The formed light is formed into a point-like image on the exit cross section by a lens action. Further, as described in Japanese Patent Application Laid-Open No. 1-295215, etc., it has a plurality of side surfaces capable of internal reflection,
A rod integrator that forms a plurality of light sources by this internal reflection may be used instead of the fly-eye integrator.

In this way, the uniformity of illumination is increased by producing a large number of point light sources. However, when uniformity of illumination is not so required, one point light source is formed by using one rod lens. May be created, and furthermore,
The end surface of the rod may be a flat surface, and a planar light source having an extension of the end surface of the rod may be used.

If a certain degree of uniformity is sufficient, the lens system 11 can further be constituted by using an optical fiber as shown in FIG. In FIG. 4, 18
Is an optical fiber. That is, the light from the light source 10 is guided by the optical fiber 18, and the exit of the optical fiber 18 is arranged at the front focal position of the condenser lens 16. Thus, Koehler illumination having telecentricity can be realized by using the exit of the optical fiber 18 as a pseudo light source. With this configuration, the light source 10, the collector lens 14, and the fly's eye integrator 15 shown in FIG. 4 are replaced with an optical fiber 18 and a lamp house that enters the optical fiber.

In the illumination optical system shown in FIG. 1, the light source 10 and the lens system 11 rotate integrally. However, if the illumination optical system uses the optical fiber 18, the light source 10 does not need to move. There is an advantage that only the optical fiber 16 and the condenser lens 16 need to be rotated instead of the large lens system 11.

In the illumination optical system shown in FIG. 4, the F value of the illumination light is determined by the exit diameter φFiber of the optical fiber 18,
Since φFiber cannot be made too large, the F value cannot be made small. However, in the present invention, when the oblique illumination is performed, the illumination uniformity improves as the F-number increases. Therefore, when the brightness does not matter, it is preferable to use an illumination optical system as shown in FIG. .

Although one optical fiber is used in FIG. 4, a plurality of optical fibers are used in a bundle, thereby providing the same
It is also possible to use a pseudo multiple light source.

FIG. 5 is a sectional view showing what kind of light flux enters one point on the solid-state image sensor 12 when oblique illumination is actually arranged. In FIG. 5, 19
Denotes a hollow part of the illumination light, and 20 denotes an angle corresponding to the pseudo F value. In FIG. 5, since the oblique illumination is illuminated to the right and left from the angle of ω, the pseudo F value becomes very small as F = 1 / (2 sin ω). However, since the diameter of each illumination optical system is small, the area indicated by 19 is a hollow light beam that is hollow. When the diameter on the exit side of the fly-eye integrator 15, that is, the pupil diameter of the condenser lens 16 is φFlyeye and the focal length of the condenser lens 16 is f when considering the illumination optical system of FIG. 9, the F value of the illumination light is F ′ = f / φFlyeye. The outer diameter φlens of the condenser lens 16 depends on the illumination range. If the required uniform illumination range is Φ, φlens = Φ + 2f * tan [sin ^-1 {(1 / (2F ′)}] ≒ Φ + 2f / F However, since the light emitted from the light source usually has a light distribution characteristic, the amount of light in the periphery is smaller than that in the center of the illumination. As a countermeasure, it is preferable to make the distortion uniformity of the lens a negative value from the beginning to improve the uniformity of the illuminance.

In the case of the optical fiber illumination system shown in FIG. 4, in order to determine the outer diameter of the condenser lens, assuming that the exit diameter of the optical fiber is represented by φFiber, φFlyeye in the above equation may be replaced with φFiber.

FIG. 6 is a diagram showing a pseudo F-number obtained when four oblique illumination optical systems are arranged and the illumination angle ω is made variable, and the state of a hollow portion of a condensed light beam. In FIG. 6, 40
Is a circle representing a solid angle corresponding to the F-number of one lens,
41 is a circle representing a solid angle corresponding to the maximum variable pseudo F-number, 4
2 is a circle representing a solid angle corresponding to the minimum variable pseudo F value, 43
Denotes a circle corresponding to the outer diameter of the lens, and 44 denotes a variable range of the pseudo F value.

This figure is a diagram in which the angle at which a light beam condensed on a point on an arbitrary non-detection solid-state imaging device is developed in a plane around a direction perpendicular to the surface of the non-detection imaging device. Is a solid angle. This is a diagram showing how the screen is illuminated when a spherical screen covering the line (three-dimensionally spherical) 20 indicating the angle corresponding to the pseudo F value in FIG. 5 is placed. Corresponding.

The actual illumination is performed at an aperture angle corresponding to the small circle 40. Then, by changing the illumination angle ω (by changing the pseudo F value), this small circle moves on the line 44 indicated by the arrow. The broken line 43 indicates the outer diameter of the lens of the illumination optical system, and the lens cannot be arranged at a position where the broken line overlaps. Therefore, the minimum value of ω (and the maximum pseudo F value) is determined corresponding to the circle indicated by 42.

If the optical fiber illumination optical system shown in FIG. 4 is used as the illumination optical system, the light sources can be integrated into one. That is, by splitting the fiber emitted from the optical fiber light source into four, light can be simultaneously input to four optical systems.

FIG. 7 is a schematic diagram showing another embodiment of the present invention, and the drawing is the same as that of FIG. FIG.
, 45 represents a circle representing a solid angle corresponding to the F value of vertical illumination, 46 represents a circle representing a solid angle corresponding to the F value of the first oblique illumination, and 47 represents an F value of the second oblique illumination. A circle representing a solid angle, a circle 48 representing a solid angle corresponding to the pseudo F-value of the first oblique illumination, and a circle 49 representing a solid angle corresponding to the pseudo F-value of the second oblique illumination. The broken line is a circle corresponding to the lens of each illumination optical system.

This embodiment has one vertical illumination optical system and eight oblique illumination optical systems, and each illumination optical system is fixed. Then, of the eight oblique illumination optical systems, 4
Each of them is a first oblique illumination optical system, is arranged at a position having a pseudo F value corresponding to the circle 48, and performs irradiation at a large illumination angle. The other four are used as a second oblique illumination optical system, are arranged at positions having a pseudo F value corresponding to the circle 49, and perform irradiation at a small illumination angle.

In order to perform the inspection in this apparatus, for example, first, the solid-state imaging device to be inspected is illuminated by a vertical illumination optical system to check the output, and then the solid-state imaging device to be inspected by a first oblique illumination optical system Then, the output is examined by irradiating the solid-state imaging device under test with the second oblique illumination optical system. In this way, by switching the illumination angle of the illumination light to three stages including the vertical illumination, the inspection of the solid-state imaging device to be inspected and the inspection of the presence or absence of dust can be performed.
In this case, since the dust inspection is performed at two fixed illumination angles, there is a feature that errors hardly occur. Further, in addition to this, if illumination is performed by the all illumination optical system, a result equivalent to inspection performed with illumination having a small F value can be obtained.

In this embodiment, it is not necessary to move the oblique light optical system to switch the illumination angle of the oblique light illumination optical system, so that a complicated mechanism is not required and quick switching is possible. It has the feature of. Also,
When the intensity of the light source is the same, the illuminance decreases in proportion to cos ω when the illumination angle is ω, but the illumination angle is fixed for both the first oblique illumination optical system and the second oblique illumination optical system. Therefore, if you adjust the intensity of the light source accordingly,
The illuminance can be made constant regardless of which light source is used.

FIG. 8 is a diagram showing an outline of a tool for adjusting the illumination angle ω of the oblique illumination system. In FIG. 8, 50
Is a collimating lens, 51 is a pinhole, 52 is a screen, 53 is a parallel light beam, 54 is a light spot of vertical illumination light, 55
Is a light spot of oblique illumination light.

As shown in FIG. 5A, the light condensed on the irradiation surface 17 is taken out through a pinhole 51, and is collimated by a collimating lens 50.
To be a parallel light beam 53. That is, the pinhole 51 is provided at the focal position of the collimator lens 50. The parallel light beam 53 is projected on a screen 52.

The projected parallel light beam 53 is applied to a screen 52.
The light spot 55 of the oblique illumination light appears to be divided as shown in FIG. The illumination angle ω of the oblique illumination system can be adjusted while measuring the position of the light spot 55 on the screen. At this time, the lens has distortion so that the illumination angle ω is proportional to the position r of the light spot 55 on the screen (the distance between the center of the light spot 54 of the vertical illumination light and the center of the light spot 55 of the oblique illumination light). Ideally, if these are not proportional, if the distortion of the lens is known, r and ω
There is no problem because the relationship can be determined.

The adjustment is based on the center position of the light spot. In the case of white light, the light spot expands unless the color is achromatized by the collimating lens 50. Therefore, a filter is inserted after the collimating lens 50 to adjust the wavelength range. Is more accurate. Further, when the illumination angle ω of the oblique illumination optical system is large, the angle of the light beam passing through the pinhole 51 also becomes large, and accordingly, it is necessary to reduce the F value of the collimating lens 52 accordingly. When a collector lens using an aspherical surface is used, a single lens can be formed. In this case, the position of the light spot is not proportional to the illumination angle ω because the distortion of the lens is large. Particularly, in the case of four-direction oblique illumination, it is useful to balance the oblique light angles in four directions.

Also, in FIG. 8, the adjustment is performed by looking at the light spot projected on the screen 52. However, a two-dimensional light receiving element (CCD, PSD, etc.) is placed instead of the screen 52, and the adjustment is made by looking at the output. Can also be performed.

Further, the telecentricity of the illumination light can be confirmed by using this device. That is, the measurement is performed with the pinholes 17 positioned at various positions on the irradiation surface 17, and it can be confirmed that telecentricity is good if the position of the light spot 55 does not change at that time. Conversely, if the position of the light spot 55 changes, the telecentricity is poor, so it is determined that adjustment of the light source and the lens system is necessary.

[0061]

As described above, according to the first aspect of the present invention, in addition to a vertical illumination optical system similar to the conventional one, an oblique illumination optical system having a variable illumination angle is provided. Defects of the image sensor itself can be distinguished from dust adhering to the cover glass, and inspection can also be performed on a solid-state image sensor whose incident direction is obliquely limited by a microlens provided on the surface.

According to the second aspect of the present invention, since the irradiation is performed from four directions, when the illumination angle is changed, the shadow of the dust does not come off the image pickup element surface, and the cover glass is not damaged. The garbage on the back is
Even if the movement is small, it seems that the movement becomes large with an increase in the illumination angle, so that it is possible to reliably detect dust.

According to the third aspect of the present invention, since the light from the light source is guided to the focal position of the illumination lens using the optical fiber, it is not necessary to move the light source when changing the illumination angle. Therefore, the configuration of the device is simplified. Further, a light source can be shared by a plurality of illumination optical systems.

In the invention according to claim 4, the position of the illumination optical system can be easily adjusted by adjusting the position of the illumination optical system while watching the image of the irradiation light projected on the screen or the output of the light receiving element. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of detecting dust attached to a cover glass by changing an illumination angle of an oblique illumination optical system.

FIG. 3 is a diagram illustrating how dust shadows appear on an image captured by a non-detection solid-state imaging device with respect to vertical illumination and oblique illumination.

FIG. 4 is a schematic diagram showing an illumination optical system using an optical fiber.

FIG. 5 is a cross-sectional view showing a light beam entering a solid-state imaging device under test when oblique illumination is actually arranged.

FIG. 6 is a diagram showing a pseudo F-number obtained when four oblique illumination optical systems are arranged and the illumination angle ω is made variable, and the state of a hollow portion of a condensed light beam.

FIG. 7 is a schematic diagram showing another embodiment of the present invention.

FIG. 8 is a diagram showing an outline of a tool for adjusting the illumination angle ω of the oblique illumination system.

FIG. 9 is a diagram showing an outline of a lighting device conventionally used for vertical lighting and a lighting device used in an example of an embodiment of the present invention.

[Explanation of symbols]

Reference numeral 10 denotes a light source, 11 denotes a lens system, 12 denotes a solid-state imaging device to be tested, 13 denotes an angle corresponding to the F value of one pseudo light source in the lens system, 14 denotes a collector lens, 15 denotes a fly-eye integrator, 16 denotes a condenser lens, 17 ...
Irradiation surface (solid-state imaging device surface), 18 ... optical fiber, 19
... the hollow part of the illumination light, 20 ... the angle corresponding to the pseudo F-number,
30: cover glass, 31: dust attached to the surface of the cover glass, 32: dust attached to the back of the cover glass,
40: a circle representing a solid angle corresponding to the F-number of one lens, 41 ... a circle representing an angle corresponding to the maximum variable pseudo F-number,
42... A circle representing an angle corresponding to the minimum variable pseudo F-number, 43
... A circle corresponding to the outer diameter of one lens, 44... A variable range of pseudo F value, 45... A circle representing a solid angle corresponding to the F value of vertical illumination, 46. Circle representing solid angle, 47: Circle representing solid angle corresponding to F value of second oblique illumination, 48 ... Circle representing solid angle corresponding to pseudo F value of first oblique illumination, 49 ... Second A circle representing a solid angle corresponding to a pseudo F-number of oblique illumination, 50... A collimating lens, 51
... Pinhole, 52 ... Screen, 53 ... Parallel beam, 5
4: Light spot of vertical illumination light 55: Light spot of oblique illumination light

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G051 AA61 AA90 AB01 AB02 BA01 BB07 BB17 BC07 CA03 CA20 4M118 AA09 AA10 AB01 BA03 FA06 FB09 GD02 5C024 AA01 BA00 CA31 DA00 EA00 FA01 FA11 FA17 GA00 HA00 JA00 5C061 BB01 BB01

Claims (4)

[Claims] 1. An illumination (vertical illumination) optical system having an optical axis perpendicular to a solid-state imaging device to be inspected, and an illumination (oblique illumination) optical system having an optical axis inclined with respect to the solid-state imaging device to be inspected. An illumination device for inspecting a solid-state imaging device, wherein an illumination angle (incident angle) of the oblique illumination optical system is variable. 2. The illuminating device for inspecting a solid-state image sensor according to claim 1, wherein the oblique illumination optical system projects approximately 90 ° when projected onto a plane parallel to the imaging surface of the solid-state image sensor to be inspected. An illumination device for inspecting a solid-state imaging device, comprising: four illumination optical systems arranged in a plurality of illumination optical systems. 3. The illumination device for inspecting a solid-state imaging device according to claim 1, wherein at least one of the vertical illumination optical system and the oblique illumination optical system includes an illumination lens and the illumination lens. An optical fiber having an exit at one focal position of the lens, and the test solid-state imaging device is arranged at the other focal position of the illumination lens. Lighting device for element inspection. 4. One of claims 1 to 3
An adjustment tool used for adjusting the oblique illumination optical system in the solid-state imaging device inspection illumination device according to the item, comprising a pinhole, a lens that receives light passing through the pinhole, and a lens that passes through the lens. An adjustment tool comprising a screen or a light receiving element for receiving light.