JP2005331371A - Illumination auxiliary device, and inspection device using the illumination auxiliary device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination auxiliary device using efficiently a light beam emitted from a lighting system, irrespective of a size of an effective diameter in an opening diaphragm, and to provide an inspection device using the illumination auxiliary device. <P>SOLUTION: This imaging element inspecting device 1 concerned in the present invention is constituted of the lighting system 2 for telecentric illumination, the illumination auxiliary device 3 for irradiating a solid imaging element 4 with the light beam emitted from the lighting system 2, and a signal processor 16 for detecting a signal output from the solid imaging element 4. The illumination auxiliary device 3 has a lens 31 for converging the beam emitted from the lighting system 2, a diffusion plate 32 arranged in the vicinity of a focal point of the lens 31 to diffuse the beam converged by the lens 31, the opening diaphragm 33 arranged in the vicinity of the diffusion plate 32, in this order, starting from a lighting system 2 side, and is constituted to be integrally inserted removably into the lighting system 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination auxiliary device that efficiently collects and irradiates illumination light in an inspection of a test object such as a solid-state imaging device, and an inspection device using the illumination auxiliary device.

  Conventionally, a solid-state imaging device such as a CCD or a CMOS is manufactured by stacking a semiconductor integrated circuit on the surface of a semiconductor wafer. The formed solid-state imaging device is a pixel in which pixels such as photodiodes that are photoelectric conversion elements are arranged in a grid or a straight line. These photodiodes generate charges according to the intensity of light applied. At this time, the light response characteristics of each pixel of the image sensor vary due to variations in the manufacturing process. For this reason, in a normal manufacturing process, only those having a variation in the light response characteristics within a predetermined range are identified by inspection and shipped as non-defective products.

  The inspection of the optical response characteristics of the solid-state imaging device is performed by illuminating with a predetermined illumination device and measuring an electrical signal from the solid-state imaging device. This inspection is actually performed by the target solid-state imaging device. Inspection is performed under substantially the same illumination as the conditions used. Specifically, the distance between the exit pupil of an imaging lens such as a camera in which the solid-state imaging device is used and the imaging device (hereinafter referred to as “pupil distance”) And inspection with a light source that satisfies an illumination condition equal to the aperture ratio of the imaging lens.

  Therefore, in such an inspection device for an image sensor, an illumination auxiliary device having a diffusing plate and an aperture stop is used to diffuse the light beam from the light source with the diffusing plate and to obtain the aperture ratio and pupil distance of the imaging lens. An aperture stop is provided to illuminate the solid-state image sensor with illumination light (see, for example, Patent Document 1). At this time, the effective diameter Φ of the aperture stop in the illumination assisting device, which has substantially the same conditions as when the aperture ratio of the imaging lens is A and the pupil distance is L, is expressed by the relationship expressed by the following equation (1).

                            Φ = L / A (1)

  Solid-state image sensors used in recent compact digital cameras and camera-equipped mobile phones have been downsized with the miniaturization of these devices, and the pupil distance L has also become shorter depending on the size of the imaging lens and solid-state image sensor. . Therefore, as is clear from the equation (1), the effective diameter Φ of the aperture stop used in the illumination assist device needs to be reduced in proportion to the pupil distance.

Utility Model Registration No. 2583733

  However, when the effective diameter Φ of the aperture stop of the illumination assisting device is reduced, much of the illumination light from the illumination device is blocked by the aperture stop, and only some of the light rays are used for the inspection of the solid-state imaging device. For this reason, when an inspection is performed by irradiating the solid-state imaging device with a strong light beam, an illumination device having a stronger light source is required, which is not efficient.

  The present invention has been made in view of such a problem, and the light beam emitted from the illumination device is efficiently used regardless of the size of the effective diameter of the aperture stop, and a predetermined aperture ratio and pupil distance are obtained. It is an object of the present invention to provide an illumination auxiliary device that illuminates a solid-state imaging device under the above conditions, and an inspection device using the illumination auxiliary device.

  In order to solve the above-described problems, the illumination auxiliary device according to the present invention is disposed on an optical path between an illumination device that performs telecentric illumination and a test object having a photoelectric conversion element (for example, the solid-state imaging device 4 in the embodiment). In order to irradiate the test object with light rays emitted from the illumination device, a lens that collects the light rays emitted from the illumination device in order from the illumination device side, and a lens disposed near the focal point of the lens. A diffusing plate for diffusing the condensed light beam and a diaphragm (for example, the aperture diaphragm 33 in the embodiment) disposed in the vicinity of the diffusing plate, and configured to be integrally inserted into and removed from the lighting device. Is done.

At this time, the effective diameter of the aperture and [Phi, when the numerical aperture of the illumination system and NA, the focal length of the lens was f _a, the following equation
Φ / (2 · NA) < f a <2 · Φ / NA
It is preferable to be configured to satisfy

  The lens is preferably composed of an aspheric lens or a Fresnel lens.

  On the other hand, the inspection device according to the first aspect of the present invention (for example, the image sensor inspection device 1 in the embodiment) includes an illumination device that performs telecentric illumination, a lens that collects light emitted from the illumination device, and a focal point of the lens. A diffusing plate for diffusing the light beam collected near the lens disposed in the vicinity, a diaphragm disposed in the vicinity of the diffusing plate, and a test object having a photoelectric conversion element irradiated with the light beam emitted from the diaphragm And a detecting means for detecting a signal output from the test object.

  An inspection apparatus according to the second aspect of the present invention (for example, the image sensor inspection apparatus 100 in the embodiment) includes an illumination apparatus that performs telecentric illumination, a lens that collects light rays emitted from the illumination apparatus, and the vicinity of the focal point of the lens. And at least two or more sets of illumination auxiliary devices each including a diffuser plate that diffuses the light beam collected by the lens and a diaphragm disposed in the vicinity of the diffuser plate, and each of the light beams emitted from the diaphragm It is comprised from the detection means which irradiates the photoelectric conversion area | region (for example, imaging surface 104a in embodiment) formed in at least 2 places or more of to-be-tested objects, and detects each signal output from a photoelectric conversion area | region.

In the inspection apparatus according to the first and second aspects of the present invention, when the aperture ratio of the light beam emitted from the diaphragm is A and the distance on the optical axis from the diaphragm to the test object is L, the effective diameter of the diaphragm Φ is the following formula
Φ = L / A
It is preferable to be configured to satisfy

Further, in the inspection apparatus according to the first and second aspects of the present invention, when the numerical aperture of the illumination system and NA, the focal length of the lens was f _a, the following equation
Φ / (2 · NA) < f a <2 · Φ / NA
It is preferable to be configured to satisfy

  Furthermore, it is preferable that the lens constituting the inspection apparatus according to the first and second aspects of the present invention is composed of an aspheric lens or a Fresnel lens.

  When the illumination auxiliary device according to the present invention is configured as described above, the illumination light from the illumination device is collected by the lens regardless of the effective diameter of the diaphragm, and is passed through the diffusion plate and the diaphragm. Therefore, the illumination light from the illumination device can be used efficiently. At this time, by using a lens having a predetermined focal length, it is possible to irradiate the object with illumination light from the illumination device more efficiently. Further, by using an aspherical lens or a Fresnel lens as the lens, it is possible to suppress the generation of aberrations in the lens and to irradiate the object with uniform illumination light.

  When the inspection apparatus according to the first and second aspects of the present invention is configured as described above, the illumination light from the illumination apparatus is collected by the lens and passes through the diffusion plate and the diaphragm regardless of the effective diameter of the diaphragm. Therefore, the illumination light of the illuminating device can be efficiently used. Moreover, by having two or more sets of illumination auxiliary devices as in the inspection device according to the second aspect of the present invention, a plurality of test objects (photoelectric conversion regions) are irradiated with illumination light at a time for inspection. Therefore, the throughput of the inspection apparatus can be improved.

  In the inspection apparatus according to the first and second aspects of the present invention, by determining the effective diameter of the diaphragm from the aperture ratio emitted from the diaphragm and the distance (pupil distance) on the optical axis from the diaphragm to the test object. The test object can be inspected by irradiating illumination light under the same conditions as the optical instrument in which the test object is actually used.

  Furthermore, similarly to the above-described illumination assist device according to the present invention, by using a lens having a predetermined focal length, it is possible to efficiently irradiate the object with illumination light from the illumination device, and to remove the lens. By using a spherical lens or a Fresnel lens, it is possible to suppress the generation of aberration in this lens and to irradiate the object with uniform illumination light.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the image sensor inspection apparatus 1 in which the illumination assisting apparatus according to the present invention is used will be described with reference to FIG. The image sensor inspection device 1 includes an illumination device 2, an illumination auxiliary device 3, and a test object (solid-state image sensor) 4 to be inspected. The illumination device 2 includes a light source 5, a collector lens 6, a density filter 7, a filter group 8, an input lens 9, an integrator rod 10, a fly-eye lens 11, and a light amount monitor 12 in order on the optical axis. Composed.

  Among the illuminating device 2, components related to setting of illumination conditions when inspecting the image sensor 4 are a density filter 7 and a filter group 8. The density filter 7 has a disk shape, and includes an adjustment filter disk 7a having a stepwise or density gradient in the rotation direction thereof, and a motor 7b for rotating the filter disk 7a. Side) is arranged so as to be orthogonal to the optical axis of the illumination device 2. Therefore, the amount of light (illuminance) on the irradiated surface 4 a of the solid-state imaging device 4 can be adjusted by the rotation of the density filter 7.

  The filter group 8 includes a color filter, a color temperature conversion filter, and the like, and can be switched according to inspection contents by a mechanism (not shown). By switching the filter group 8, the spectral spectrum on the irradiated surface 4a can be adjusted. In addition, a half mirror 13 is formed inside the integrator rod 10 to reflect a part of the light to the side and transmit the remaining light. The light reflected by the half mirror 13 is reflected by the photoelectric detector 14. It is configured to detect and monitor the amount of light.

  A light beam emitted from a light source 5 such as a halogen lamp or a xenon lamp is collected by a collector lens 6, becomes almost parallel light, passes through a density filter 7 and a filter group 8, and is input to an integrator rod 10 by an input lens 9. The light is condensed on the incident surface 10a, and an image of the light source 5 is formed on the light incident surface 10a. The integrator rod 10 is made of a rod-shaped glass material (whose cross section is rectangular), and is also called a rod lens or a lot-type optical integrator. The light exit surface 10b of the integrator rod 10 is disposed on a surface conjugate with the irradiated surface 4a of the image sensor inspection apparatus 1 (that is, the image pickup surface of the solid-state image sensor 4 placed on the image sensor inspection apparatus 1). .

  Inside the integrator rod 10, the light beam incident from the light incident surface 10a repeats internal reflection at the number of times corresponding to the incident angle, and propagates toward the light emitting surface 10b. Then, on the light exit surface 10b, light having different reflection times overlaps, and the light quantity distribution is made uniform. That is, the light source 5, the collector lens 6, the input lens 9, and the integrator rod 10 generate a structure in which the light amount distribution is uniform in the light emitting surface 10 b (that is, a surface conjugated to the irradiated surface 4 a). Can do.

  The luminous flux emitted from the integrator dot 10 is divided into a plurality of luminous fluxes by the fly-eye lens 11 and emitted to enter the illumination auxiliary device 3 as telecentric light (the configuration of the illumination auxiliary device 3 will be described later). The light beam emitted from the illumination assisting device 3 is applied to the imaging surface (irradiated surface 4a) of the solid-state imaging device 4. Note that a probe 15 extending from the signal processing device 16 is electrically connected to an output terminal of the solid-state imaging device 4, and the solid-state imaging device 4 is output by illumination light emitted by the illumination device 2 and the illumination auxiliary device 3. Inspection is performed by detecting a signal to be detected.

  Then, the structure of the illumination auxiliary device 3 which concerns on a present Example is demonstrated using FIG. The illumination auxiliary device 3 includes a lens 31, a diffuser plate 32 and an aperture stop 33 disposed in the vicinity of the focal point of the lens 31, and condenses telecentric light emitted from the illumination device 2 by the lens 31. Then, the diffusion plate 32 is irradiated, and the light beam diffused by the diffusion plate 32 is irradiated to the imaging surface 4 a of the solid-state imaging device 4 through the aperture stop 33. The diffusing plate 32 and the aperture stop 33 may be configured to be in close contact with each other, or may be configured to have a gap.

  Here, the distance L between the aperture stop 33 and the solid-state imaging device 4 is equal to the pupil distance of an optical apparatus (such as the above-described compact digital camera or camera-equipped mobile phone) in which the solid-state imaging device 4 to be inspected is used. In addition, the effective diameter Φ of the aperture stop 33 is calculated from the aperture ratio A and pupil distance L so that the aperture ratio A is equivalent to that of the imaging lens of the optical device to be used. ). For this reason, the emission range of the light beam diffused by the aperture stop 33 at the diffusion plate 32 is limited. As a result, the distance L from the aperture stop 33 to the solid-state imaging device 4 is the pupil distance, and the pupil distance and the effective diameter Φ of the aperture stop 33 It functions as a secondary light source having an aperture ratio A determined by: irradiates the imaging surface 4 a of the solid-state imaging device 4.

  For example, in this embodiment, when the illumination device 2 does not use the auxiliary illumination device 3, the solid-state imaging device 4 is illuminated in a telecentric manner with a light beam having a numerical aperture of 0.05 (aperture ratio A is equivalent to F / 10). When configured, the illumination assisting device 3 illuminates the test object (solid-state imaging device) 4 under the same conditions as when imaging with a camera lens having an aperture ratio A of F / 8 and a pupil distance L of 16 mm. Therefore, the effective diameter Φ of the aperture stop 33 is 2 mm from Equation (1).

As described above, the telecentric illumination light from the illumination device 2 is condensed on the diffusion plate 32 by the lens 31. At this time, since the diffusing plate 32 is disposed in the vicinity of the focal point of the lens 31, the diameter Φ _{2 of the} condensing spot of the illumination light formed on the diffusing plate 32 is NA of the numerical aperture of the illuminating device 2. When the focal length of the lens 31 is f _a , it is expressed by the following equation (2).

_{Φ 2 = 2 · NA · f} a (2)

In order for the aperture ratio A of the light that illuminates the solid-state imaging device 4 (imaging surface 4 a) to be limited by the effective diameter Φ of the aperture stop 33, the diameter Φ _{2 of the} focused spot is larger than the effective diameter Φ of the aperture stop 33. There must be. On the other hand, when the diameter Φ _{2 of the} condensing spot is remarkably larger than the effective diameter Φ of the aperture stop 33, the condensing effect by the lens 31 is small, and more rays are blocked by the aperture stop 33, and the use efficiency of illumination light is increased. Decreases. Therefore, it is desirable that the diameter Φ _{2 of the} focused spot is not more than about four times the effective diameter Φ of the aperture stop 33. This relationship is expressed by the following equation (3).

_{Φ <Φ 2 <4 · Φ} (3)

As described above, from the expressions (2) and (3), the illumination assisting apparatus 3 according to the present embodiment uses the lens 31 having the focal length f _a that satisfies the condition represented by the following expression (4). Thus, the solid-state imaging device 4 can be efficiently illuminated with a predetermined aperture ratio A and pupil distance L.

Φ / (2 · NA) < f a <2 · Φ / NA (4)

For example, in the case of the illuminating device 2 and the camera lens having the above-described conditions, the diameter Φ _{2 of the} focused spot is about twice the effective diameter Φ of the aperture stop 33, that is, the focal length f _a of the lens 31 is calculated from Equation (2). By setting the thickness to about 40 mm, the solid-state imaging device 4 can be efficiently illuminated.

In such an illumination assisting device 3, the larger the effective diameter of the lens 31, the larger the light beam condensed at the condensing spot on the diffusion plate 32 and the more efficient the illumination. However, as the effective diameter increases, the spherical surface becomes spherical. As the aberration increases, the condensing spot on the diffuser plate 32 is blurred and the spot diameter is widened. Therefore, a deviation occurs with respect to the value of the condensing spot diameter Φ ₂ estimated by the equation (2). Will lower the lighting efficiency than. In order to suppress this spherical aberration, it is preferable to use an aspheric lens in which the lens surface of the lens 31 is formed in an aspheric shape. For the same reason, the lens 31 may be a Fresnel lens.

  The illumination auxiliary device 3 may be integrated with the illumination device 2, but in that case, in order to inspect another solid-state imaging device having different specifications such as pupil distance, another design that is designed in accordance with this specification is performed. Image sensor inspection apparatus. In this embodiment, since the illumination auxiliary device 3 is configured to be detachable with respect to the illumination device 2, the illumination auxiliary device 3 designed according to the pupil distance and the illumination area of the solid-state imaging device is prepared. Accordingly, it is possible to inspect a wide variety of solid-state imaging elements while sharing the illumination device 2. In this case, if the illumination assisting device 3 is removed, the inspection by telecentric illumination can be performed.

Further, as described above, when the lens 31 is a spherical lens and the amount of spherical aberration is large, it is larger than the diameter Φ _{2 of the} focused spot estimated by the equation (2). Even in this case, the illumination spot efficiency Φ ₂ considering the spherical aberration is designed to satisfy the expression (3) with respect to the value of the effective diameter Φ that satisfies the expression (1). Can be designed without dropping.

As described above, the distance between the solid-state imaging lens 4 and the illumination auxiliary device 3 (aperture stop 33) is set so that the pupil distance L of the optical equipment in which the solid-state imaging lens 4 to be inspected is used. The effective diameter Φ of the aperture stop 33 is determined from the aperture ratio A and the pupil distance L using the equation (1), and the focal length f _a is obtained from the numerical aperture NA of the illumination device 2 using the equation (4). By determining the lens 31, it is possible to obtain a preferable configuration of each element of the image sensor inspection apparatus 1.

In the above embodiment, the case where the solid-state imaging device 4 is inspected one by one has been described. However, as shown in FIG. 3, two chips are formed in one sequence, and illumination is performed simultaneously. Inspection can be performed by irradiating light, and the throughput of the image sensor inspection apparatus 100 can be improved. In this case, the illumination assisting device 103 is provided with a lens 131, a diffusion plate 132, and an aperture stop 133 for a plurality of imaging surfaces (element forming regions) 104a and 104a on the test object (solid-state imaging device) 104, respectively. The illumination can be performed under predetermined illumination conditions. At this time, and the effective diameter Φ of the aperture stop corresponding to the imaging plane 104a, the focal length f _a of the lens 131 corresponding to each can be calculated by the aforementioned formula (1) and (4). Further, as shown in FIG. 3, the diffusion plate 132 and the aperture stop 133 can be configured by integral members, or can be configured as individual members. In FIG. 3, the configuration for inspecting two chips at a time has been described. However, the illumination assisting device 103 is configured to have three or more combinations of the lens 131, the diffusion plate 132, and the aperture stop 133, It is also possible to configure to inspect three or more chips at a time. Although not shown in FIG. 3, the probe 15 shown in FIG. 2 is connected to each chip 104a of the solid-state image pickup device 104, and the output signal is processed by the signal processing device 16 to check the image pickup device. Inspected with device 100.

It is a lens block diagram which shows the illumination auxiliary device which concerns on this invention. It is a lens block diagram which shows the image pick-up element inspection apparatus which concerns on 1st this invention. It is a lens block diagram which shows the image pick-up element inspection apparatus which concerns on 2nd this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image pick-up element inspection apparatus 2 Illumination apparatus 3 Illumination auxiliary | assistance apparatus 4,104 Solid-state image sensor (test object)
104a Imaging surface 16 Signal processing device 31 Lens 32 Diffusion plate 33 Aperture stop (aperture)

Claims (10)

An illumination auxiliary device that is disposed on an optical path between an illumination device that performs telecentric illumination and a test object having a photoelectric conversion element, and that irradiates the test object with a light beam emitted from the illumination device,
In order from the lighting device side, a lens that collects the light emitted from the lighting device;
A diffusing plate disposed near the focal point of the lens and diffusing the light collected by the lens;
An illumination auxiliary device having a diaphragm disposed in the vicinity of the diffusion plate and configured to be integrally inserted into and removed from the illumination device. When the effective diameter of the diaphragm and [Phi, the numerical aperture of the illumination device and NA, a focal length of the lens was f _a, the following equation
Φ / (2 · NA) < f a <2 · Φ / NA
The illumination auxiliary device according to claim 1, wherein the illumination auxiliary device is configured to satisfy the following.   The illumination auxiliary device according to claim 1, wherein the lens is an aspheric lens.   The illumination auxiliary device according to claim 1, wherein the lens is configured by a Fresnel lens. A lighting device for telecentric illumination;
A lens that collects the light emitted from the illumination device;
A diffusing plate disposed near the focal point of the lens and diffusing the light collected by the lens;
A diaphragm disposed in the vicinity of the diffusion plate;
An inspection apparatus comprising: a detection unit configured to irradiate a test object having a photoelectric conversion element with a light beam emitted from the diaphragm and detect a signal output from the test object. A lighting device for telecentric illumination;
A lens for condensing the light emitted from the illumination device, a diffuser disposed near the focal point of the lens and diffusing the light collected by the lens, and a diaphragm disposed near the diffuser And at least two or more sets of lighting auxiliary devices consisting of:
And a detection means for detecting each signal output from the photoelectric conversion region by irradiating each of the light beams emitted from the diaphragm to the photoelectric conversion region formed in at least two places of the test object. Inspection device characterized by When the aperture ratio of the light beam emitted from the diaphragm is A and the distance on the optical axis from the diaphragm to the test object is L, the effective diameter Φ of the diaphragm is
Φ = L / A
The inspection apparatus according to claim 5, wherein the inspection apparatus is configured to satisfy the following. The numerical aperture of the illumination device and NA, the focal length of the lens was f _a, the following equation
Φ / (2 · NA) < f a <2 · Φ / NA
The inspection apparatus according to claim 5, wherein the inspection apparatus is configured to satisfy the above.   The inspection apparatus according to claim 5, wherein the lens is an aspheric lens.   The inspection apparatus according to claim 5, wherein the lens is a Fresnel lens.

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