JP5261095B2 - Illumination optical system for image sensor inspection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging element inspecting illumination optics capable of taking an optimum lighting area considering a mounting hole to amount an inspecting illumination device. <P>SOLUTION: In an imaging element inspecting device 20, the imaging element inspecting illumination optical system used for the inspecting illumination device 26 has a condenser lens 1 that applies illumination light emitted from a light source 41 approximately perpendicularly to an inspected surface 49 of an imaging element, and the condenser lens 1 to apply illumination light to an area 49a of the inspected surface 49 where illumination is necessary is determined while considering that a part of the condenser lens 1 is removed in accordance with the size of the mounting hole 25 formed in a circuit tester 24. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an illumination optical system for image sensor inspection.

  An image sensor inspection device used for inspecting an image sensor such as a CCD or a CMOS supplies a power by connecting a prober to the image sensor placed on the wafer stage, and images the light of the inspection condition by the inspection illumination device. In a state where the device is irradiated, a signal output from the image pickup device is received by a circuit tester via a prober and analyzed to determine pass / fail. This conventional image sensor inspection apparatus has a configuration in which an inspection illumination device is arranged on the upper portion of the prober and a circuit tester is separately provided. As such an illumination auxiliary device that illuminates from above is disclosed in Patent Document 1. Has been. However, high responsiveness of the electrical signal output from the image sensor becomes important due to miniaturization of the image sensor and high speed of inspection, and the distance between the image sensor and the circuit tester is shortened (in practice, the prober and the circuit tester). It is necessary to shorten the length of the cable connected between the two. In response to such demands, a circuit tester is arranged above the prober, and a mounting hole that opens downward is provided in the center of the circuit tester, and an inspection illumination device is attached to the mounting hole, thereby imaging. 2. Description of the Related Art An image sensor inspection apparatus that can inspect with a high frequency signal by shortening the distance between an element and a circuit tester has been developed.

In addition, since the screen size is reduced due to the miniaturization of the image sensor, the number of image sensors that can be taken from one wafer is dramatically increased. Therefore, in order to shorten the inspection time, multi-chip simultaneous inspection is performed in which an additional optical element is inserted into the above-described imaging element inspection apparatus and a plurality of imaging elements on the wafer are irradiated with light simultaneously to perform inspection in parallel. Is going. In such an inspection, the image pickup devices are arranged in a row in a diagonal direction with respect to the wafer stage, thereby securing a wiring space from the prober to the image pickup device. At this time, if the illumination area is increased in the direction in which the image sensors are arranged, the number of inspections can be increased at a time, and the inspection time can be further shortened.
Japanese Utility Model Publication No. 5-71732

  However, when trying to increase the illumination area, the area when light passes through the condenser lens of the imaging device inspection optical system provided in the inspection illumination device becomes wider, and it is necessary to increase the diameter of the condenser lens. Arise. However, the circuit tester stores an electric circuit with a standardized board shape, and in order to reduce the noise and the high-speed response, it is not possible to widen the mounting hole for placing the inspection illumination device. difficult. Therefore, in the configuration in which the inspection illumination device is incorporated in the circuit tester, there is a problem that the condenser lens diameter in the inspection illumination device cannot be made larger than the mounting hole. If a space (working distance) for inserting an additional optical element is secured, a condenser lens that is larger than the thickness of the light beam is required, and it becomes more difficult to widen the illumination area.

  The present invention has been made in view of such problems, and provides an illumination optical system for inspecting an image sensor that can obtain an optimal illumination area in consideration of an attachment hole for attaching an inspection illumination device. The purpose is to do.

In order to solve the above-described problem, an illumination optical system for imaging device inspection according to the present invention is based on an output signal obtained by irradiating illumination light to an imaging device that is an object to be examined (for example, the wafer 22 in the embodiment). It is used in an image sensor inspection apparatus that determines the quality of the image sensor, and the illumination light emitted from the light source is substantially perpendicular to the surface to be inspected of the image sensor (for example, the image sensor surface 49 in the embodiment). It has a condenser lens to irradiate. Then, when the length in the longitudinal direction or the short direction of the illumination area on the surface to be inspected (including the case where the lengths in the longitudinal direction and the short direction are equal) is L, the illumination light irradiated to this illumination area The distance of the longest part of the width of the passing region when passing through the condenser lens is b, the radius of the condenser lens is R, and the same direction as the longitudinal direction or the short side direction is selected as L. The distance from the optical axis of the optical system including this condenser lens to the position where the mounting hole forming the lens mounting space interferes with the condenser lens is represented by d ′ (for example, d / in the first example of the embodiment). 2), the numerical aperture of the condenser lens is NA, the working distance is WD, and the mounting hole has a circular condenser lens with a radius R so as to satisfy the following conditions. From the center distance Y apart chord and the condenser lens to remove the chordal portion surrounded by minor arc of the condenser lens is disposed from.
WD × NA + L / 2 <Y <d ′
However, b / 2 <R

  In such an imaging element inspection illumination optical system, it is preferable that the condenser lens includes, in order from the light source side, a front lens group having a positive refractive power and a rear lens group having a positive refractive power.

の条件を満足するように構成されることが好ましい。 At this time, the distance from the point intersecting the optical axis on the test surface to the outermost side of the illumination area is p, the distance to the main plane of the rear lens group is e ₀ , the numerical aperture is NA, and the effective of the rear lens group Defines the maximum diameter φ _0, and is the distance along the optical axis from the surface to be inspected, where h is the distance to the end of the mounting hole, up to the mounting hole that interferes with the light incident on the rear lens group Where ψ is the distance from the optical axis and f ₁ is the focal length of the rear lens group,

It is preferable to be configured to satisfy the above condition.

の条件を満足するように構成されることが好ましい。 Further, the distance from the surface to be inspected to the main plane of the rear lens group is e ₀ , the main plane distance between the rear lens group and the front lens group is e _1, and the distance from the main plane of the front lens group to the pupil is e _2, and the focal length of the rear lens group and f _1, the focal length of the front lens group and f _2, a focal length of the condenser lens is f, the following equation

It is preferable to be configured to satisfy the above condition.

  When the illumination optical system for image sensor inspection according to the present invention is configured as described above, it is calculated where the light necessary for illuminating the illumination area passes through the condenser lens, and the portion through which light does not pass is removed. It becomes possible to illuminate an area larger than the illumination area by the lens having a diameter equal to or smaller than the size of the mounting hole.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. First, the configuration of an image sensor inspection apparatus equipped with an inspection illumination device will be described with reference to FIG. The image sensor inspection apparatus 20 includes a wafer stage 21 on which a wafer 22 having an image sensor formed thereon is mounted, a prober 23 provided above the wafer stage 21, and a prober 23 provided above the prober 23. The circuit tester 24 is electrically connected to the prober 23 by the cable 27, and the inspection illumination device 26 is attached to the attachment hole 25 provided upward from the lower surface of the circuit tester 24. The prober 23 is provided with a probe needle 23a extending downward. The probe needle 23a is brought into contact with the electrode of the image sensor formed on the wafer 22, thereby supplying electric power to the image sensor and taking this image. A signal output from the element is transmitted to the circuit tester 24 via the cable 27.

  Next, the configuration of an imaging element inspection illumination optical system (hereinafter referred to as “illumination optical system”) used in the above-described inspection illumination device 26 will be described with reference to FIG. In the inspection illumination device 26, light emitted from the light source 41 such as a halogen lamp or a xenon lamp is guided to the illumination optical system via the collector lens 42. In this illumination optical system, the illumination light is transmitted through the filter 43a so as to have a predetermined spectral distribution. Further, a filter 43b (for example, red (Red), green (Green), blue (blue), etc.)) that creates a necessary spectral distribution according to the inspection conditions can be taken in and out. Further, the light quantity is adjusted to a predetermined light quantity via ND filters (Neutral Density Filters) 44a and 44b for adjusting the light quantity. The image sensor used in a general camera is used in a wide range of light conditions from hundreds of thousands of lux in daylight to several lux in the nighttime, so the light quantity setting accuracy is very important, but the influence of variations in the optical density of the filter In order to make fine adjustment of the amount of light, the switchable ND filter 44a for setting a large amount of light and the ND filter 44b for adjustment having a stepwise or concentration gradient in the rotation direction of the disk are rotated. Yes.

  The illumination light beam with the spectroscopic characteristics and the light quantity regulated is guided to the illuminance uniforming optical system by the input lens 45. Here, an example of an illuminance uniformizing optical system using a rod lens 46 is shown. The obliquely incident illumination light is reflected by the side surface of the rod lens 46, guided to the exit end of the rod lens 46, and the light beam spreading from the light source is superimposed at the exit end, and the light amount is made uniform at the exit end of the rod lens 46. . Since the aperture stop 48 is at the front focal position of the condenser lens 1, the light from the rod lens 46 is the principal ray of the light beam that illuminates an arbitrary point on the image sensor surface 49 via the relay lens 47 and the condenser lens 1. Irradiation is performed so as to be substantially perpendicular to the image sensor surface 49 (telecentric). That is, the place where the principal rays of the light beams that illuminate the image sensor surface 49 intersect is at a position at infinity from the image sensor surface 49.

  As shown in FIG. 3, a fly-eye lens 410 may be used in the illuminance uniformizing optical system instead of the rod lens 46 described above. The light flux from the input lens 45 is guided to the fly-eye lens 410 by the three relay lenses 47a, 47b, 47c. The reason for using three relay lenses is to prevent the light flux from spreading more than when only one relay lens is used, and to prevent the relay lens diameter from becoming larger than the mounting hole 25 formed in the circuit tester 24. The fly-eye lens 410 is composed of 10 × 10 single lenses, and the incident surface of the single lens and the imaging element surface 49 are conjugate. The light beams divided by the single lenses are overlapped on the image sensor surface 49 to make the light quantity uniform. The aperture stop 48 is at the front focal length of the condenser lens 1, and the light from the fly-eye lens 410 is applied to the image sensor surface 49 in a telecentric manner. In FIG. 3, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The mounting hole 25 formed in the circuit tester 24 for mounting such an inspection illumination device 26 is formed through the circuit tester 24 in the vertical direction, so that the above-described illuminance uniformizing optical system is disposed. The lower space in which the condenser lens 1 for irradiating the imaging element surface 49 with illumination light is secured by reducing the diameter of the upper space 25a to which the mounted portion is attached to secure a space for a circuit device or the like housed therein. The diameter of 25b is made larger than the upper space 25a, and the illumination light irradiation area for the image sensor surface 49 is secured. The inspection illumination device 26 is also formed in the mounting hole 25 according to the shape.

  In the multichip simultaneous inspection, an additional optical element is inserted between the condenser lens 1 and the imaging element surface 49. As shown in FIG. 4, the additional optical element has a structure in which the diffusion plate 51 and the diaphragm 52 are in close contact with each other, and is inserted so as to match the distance from the diaphragm 52 to the imaging element surface 49 to the pupil distance to be inspected. The aperture value F, which is an inspection condition, is equal to a value obtained by dividing the distance from the aperture 52 to the image sensor surface 49 by the diameter of the aperture 52.

  Then, in the mounting hole 25 having the shape as described above, a space for inserting an additional optical element for simultaneous inspection of multiple chips (working distance) is secured, and an illumination area for the imaging element surface 49 is increased. The conditions of the condenser lens 1 will be examined.

  As described above, the lower portion of the mounting hole 25 is composed of the upper space 25a and the lower space 25b having a diameter larger than that of the upper space 25a. Here, the focal length of the condenser lens 1 is f, and the lower space 25b to which the condenser lens 1 is attached is communicated with the upper space 25a at the position h along the optical axis from the imaging element surface 49 so as to become narrow. When formed, the relationship of f> h is assumed to hold. If the effective diameter of the condenser lens 1 is φ and the distance from the optical axis to the obstacle (for example, the wall portion of the mounting hole 25 that forms the lower space 25b) with respect to the condenser lens 1 is φ, the relationship φ> ψ Is assumed to hold.

  In order to make the illumination light emitted from the condenser lens 1 telecentric, it is necessary to make the distance from the rear principal point of the condenser lens 1 to the imaging element surface 49 coincide with the focal length f of the condenser lens 1. When the condenser lens 1 is composed of one group, the rear principal point of the condenser lens 1 is in the vicinity of the condenser lens 1, and when f> h, the condenser lens 1 is arranged in a narrow portion (upper space 25a). However, since the lens diameter becomes large, it cannot be arranged. Therefore, it is considered that the condenser lens 1 has a two-group structure (as shown in FIG. 2 and the like, the condenser lens 1 is composed of a front lens group 1a disposed on the light source side and a rear lens 1b disposed on the imaging element surface side. Suppose). The rear lens group 1b on the imaging element surface 49 side needs to have a positive power because the illumination light is spread from a narrow space (upper space 25a) to be telecentric. Also, the other front lens group 1a needs to have a positive power because the working distance is not increased more than necessary. Therefore, the condenser lens 1 has a positive two-group configuration. In particular, the rear lens group 1b has a concave surface on the light source side so as to spread light and illuminate a wide area. This corresponds to a portion (a boundary portion between the lower space 25b and the upper space 25a) where the mounting hole 25 formed in the circuit tester 24 widens.

In the condenser lens 1 having such a configuration, as shown in FIG. 5, the radius of the maximum range of the illumination area on the image sensor surface 49 is p, and the main lens group 1b of the rear lens group 1b of the condenser lens 1 from the image sensor surface 49 is used. When the distance to the plane is e _0, and the numerical aperture NA of the illumination light is approximated by a half angle θ of the maximum cone angle of the light beam emitted from the condenser lens 1 (NA = sin θ≈θ), the imaging element surface 49 In order to perform illumination without irradiating the illumination light beam at the position of the distance p from the point intersecting the optical axis in the upper illumination range to the outermost side, the illumination light beam component needs to be able to pass through the rear lens group 1b. The effective diameter φ of the group 1b satisfies the following conditional expression (1). If the lower limit value in this equation (1) is φ ₀ and the focal length of the rear lens group 1b is f ₁ , the light beam cannot be emitted from the image sensor surface 49 to the obstacle at the position h. The distance ψ from the axis to the obstacle satisfies the following conditional expression (2).

From this conditional expression (2), the focal length f ₁ of the rear lens group 1b satisfies the following conditional expression (3).

Rear lens group 1b from, above, since it has a positive power, a focal length f ₁ of the rear lens group 1b is configured so as to satisfy the following condition (4).

Next, for the rear lens group 1b that satisfies the above-mentioned conditional expression (4), the inter-lens distance in the condenser lens 1 and the focal length f ₂ of the front lens group 1a are obtained. As shown in FIG. 6, the focal length of the entire system of the condenser lens 1 is f, and the focal lengths of the rear and front lens groups 1b and 1a are f ₁ and f ₂ , respectively, from the irradiation surface (imaging device surface 49) to the rear. The distance to the main plane of the lens group 1b is e ₀ , the main plane distance between the rear lens group 1b and the front lens group 1a is e _1, and the distance from the main plane to the pupil of the front lens group 1a is e ₂ . A paraxial solution is obtained by considering a matrix that propagates the image height and inclination of a ray. The following equation (5) represents a matrix indicating the entire condenser lens 1 by sequentially taking a product of a matrix indicating that light propagates through space and a matrix indicating that light is refracted by the lens. Since it is telecentric, the right side can be expressed only by the composite focal length.

  From this determinant (5), the following equation (6) is obtained.

Then, by solving this equation (6), the focal length f ₂ of the front lens group 1a and the distances e ₁ and e ₂ between the lenses are derived as the relationship shown in the following equation (7).

Here, in the configuration using the rod lens 46 as shown in FIG. 2, the focal length f of the entire system of the condenser lens 1 is the area of the exit end of the rod lens 46, the focal length of the relay lens 47, and the surface to be inspected. The relationship with the area of the illumination area, that is, “the focal length of the relay lens 47 × (the area of the illumination area / the area of the exit end of the rod lens 46) ^1/2 ” is determined. As shown in FIG. In the case of the configuration using the above, the relationship between the area of the unit surface constituting the entrance surface of the fly-eye lens 410, the focal length of the fly-eye lens 410, and the area of the illumination area on the surface to be inspected, that is, “the focus of the fly-eye lens 410” Distance × (area of illumination area / area of unit surface constituting incident surface of fly-eye lens 410) ^1/2 ”. The distance e ₀ from the irradiation surface (imaging element surface 49) to the main plane of the rear lens group 1b is determined from the working distance. Therefore, if the focal length f ₁ of the rear lens group 1b is moved within the range determined by the conditional expression (1), the focal length f ₂ of the front lens group 1a and the distances e ₁ and e ₂ between the lenses are determined. Good. Depending on the value of the focal length f ₁ of the rear lens group 1b, there is a lens that satisfies f2 <0. However, since the condenser lens 1 has a positive two-group configuration, it is necessary to select a lens that satisfies f2> 0. .

  The lower opening 25c (the lower end of the lower space 25b) of the mounting hole 25 to which the inspection illumination device 26 is mounted is formed in a substantially rectangular shape (rectangular shape) as shown in FIG. Therefore, a method for enlarging the illumination area when the condenser lens 1 formed in a rotationally symmetrical manner is arranged with respect to the lower opening 25c having such a shape will be described.

  First, consider a case where the illumination area 49a is an L × L rectangular area as shown in FIG. At this time, as shown in FIG. 9, when the working distance from the imaging element surface 49 to the condenser lens 1 is WD and the numerical aperture of the illumination light is NA = sin θ, the illumination light incident on the L × L illumination area 49a is In the condenser lens 1, as shown in FIG. 10, the light passes through a region (passage region 50 indicated by a hatched portion) whose periphery is expanded by WD × NA from an L × L square. At this time, the length a of one side of the passing region 50 and the length b of the diagonal line are expressed by the following equation (8).

  In order to illuminate the illumination area 49 a, the above-described passing area 50 needs to be included in the condenser lens 1, and the diameter of the condenser lens 1 must be larger than the diagonal line b of the passing area 50. When the radius of the lens 1 is R, the following conditional expression (9) needs to be satisfied.

R> b / 2 (9)

  Consider the case where the size of the lower opening 25c provided at the center of the lower surface of the circuit tester 24 is a rectangular shape having a width w and a depth d (d ≦ w) as shown in FIG. The distances from the center of the condenser lens 1 to one side of the lower opening 25c in the depth direction are d1 and d2 (d = d1 + d2), respectively, and the distances from the center of the condenser lens 1 to one side of the lower opening 25c in the width direction are These are w1 and w2 (where w = w1 + w2), respectively. Further, the depth d of the lower opening 25c is longer than the length a of one side of the light transmitting region (passing region 50) and shorter than the longest portion (diagonal line) b (a <d <b). Here, when the center O of the condenser lens 1 coincides with the center of the rectangular lower opening 25c (diagonal intersection point O ′), considering a circular (rotationally symmetric) lens, the condenser lens 1 is formed in the lower opening 25c. In order to enter, the radius is R1, and R1 ≦ d1 = d2 = d / 2. At this time, the relationship between the lower opening 25c and the condenser lens 1 is expressed by the following equation (10), and the above-described conditional equation (9) cannot be satisfied. In other words, the lens does not become a lens that secures a region through which light rays necessary for illuminating the illumination region 49a having a size of L × L, and the illumination region 49a ′ lacking a square corner as shown in FIG. turn into.

R1 ≦ d / 2 <b / 2 (10)

Example 1
Here, as a first embodiment, a condenser lens satisfying the following formula (11) is considered with the radius of the condenser lens 1 as R2, as shown in FIG.

b / 2 <R2 ≦ w1 = w2 = w / 2 (11)

  When the condenser lens 1 satisfying this conditional expression is used, the above-described conditional expression (9) can be satisfied. Therefore, a passing area 50 through which a light ray necessary for obtaining the illumination area 49a having a size of L × L is formed. Can be secured. However, from the condition of d <b, d / 2 <b / 2 <R2, and the diameter of the condenser lens 1 is larger than the depth d of the lower opening 25c. Therefore, the portion (dotted line portion shown in FIG. 7) where the condenser lens 1 interferes with the lower surface of the circuit tester 24 is cut, and the inspection illumination device 26 can be incorporated into the circuit tester 24. At this time, with respect to the depth direction of the lower opening portion 25c, a bow chord portion (two portions at both ends across the optical axis) surrounded by a substring and a chord separated from the center of the condenser lens 1 by Y is cut. As for Y, it is necessary to satisfy the condition of the following conditional expression (12), that is, conditional expression (13). By configuring the condenser lens 1 in this manner, the L × L region 49a shown in FIG. 8 can be illuminated.

a / 2 <Y <d1 = d2 (12)
WD × NA + L / 2 <Y <d1 = d2 (13)

(Example 2)
As a second embodiment, as shown in FIG. 13, a case is considered in which the optical axis O and the center of the rectangular lower opening 25c (the intersection O ′ of diagonal lines) do not coincide. As in the first embodiment, it is assumed that the size of the lower opening 25c provided at the center of the lower surface of the circuit tester 24 is the width w and the depth d (d ≦ w, a <d <b). When the center O ′ of the rectangular lower opening 25c is shifted from the center O of the condenser lens 1 by x in the width direction of the lower opening 25c and y in the depth direction, the depth of the lower opening 25c from the center of the condenser lens 1 It is necessary to cut a bow chord portion surrounded by a subarc and a chord separated by Y1 in the direction, and Y1 is when the center O 'of the lower opening 25c and the center of the condenser lens 1 (optical axis O) coincide. Cutting is performed at a position less by y, and the following conditional expression (14) needs to be satisfied. On the other hand, on the opposite side of the optical axis from the above part, it is necessary to cut a bow chord part surrounded by a subarc and a chord separated by Y2 in the depth direction of the lower opening 25c. Cutting is performed at a position larger by y than when the center O ′ of the portion 25c coincides with the center of the condenser lens 1 (optical axis O), and it is necessary to satisfy the following conditional expression (15). In this case, it is not affected by the magnitude of x.

a / 2 <Y1 <d / 2-y = d1 (14)
a / 2 <Y2 <d / 2 + y = d2 (15)

(Example 3)
As a third embodiment, consider a case where the width direction of the lower opening 25c also interferes with the condenser lens 1 as shown in FIG. In this case, it is necessary to cut a bow chord portion surrounded by a subarc and a chord separated from the center of the condenser lens 1 by X1 in the width direction of the lower opening 25c, and X1 in the width direction is the center of the lower opening 25c. Cutting is performed at a position x more than when O ′ and the optical axis O coincide with each other, and it is necessary to satisfy the following conditional expression (16). On the other hand, on the opposite side of the optical axis from the above portion, it is necessary to cut a bow chord portion surrounded by a subarc and a chord separated by X2 in the width direction of the lower opening 25c. Cutting is performed at a position less by x than when the center O ′ of the portion 25c coincides with the center of the condenser lens 1 (optical axis O), and the following conditional expression (17) needs to be satisfied.

a / 2 <X1 <w / 2 + x = w1 (16)
a / 2 <X2 <w / 2-x = w2 (17)

  It should be noted that the following conditional expressions (18) and (19) must be satisfied for Y1 and Y2 in the depth direction as in the second embodiment.

a / 2 <Y1 <d / 2-y = d1 (18)
a / 2 <Y2 <d / 2 + y = d2 (19)

  As described above, by calculating where the light necessary for illuminating the illumination area 49a passes through the condenser lens 1 (calculating the passage area 50), and cutting the portion through which the light does not pass, the diameter becomes the circuit. It is possible to illuminate an area larger than an illumination area (for example, illumination area 49a ′ shown in FIG. 12) by a lens having a size equal to or smaller than the size of the lower opening 25c of the mounting hole 25 formed in the tester 24.

It is explanatory drawing which shows the structure of an image pick-up element test | inspection apparatus. It is explanatory drawing which shows a structure when a rod lens is used for the illumination intensity equalization optical system in the illumination device for a test | inspection. It is explanatory drawing which shows a structure when a fly-eye lens is used for the illumination intensity equalization optical system in the illumination device for a test | inspection. It is explanatory drawing for demonstrating the additional optical element used for the said image pick-up element test | inspection apparatus. It is explanatory drawing for demonstrating the focal distance of the back lens group which comprises a condenser lens. It is explanatory drawing for demonstrating the space | interval of an image pick-up element surface, a rear lens group, a front lens group, and a pupil. It is explanatory drawing for demonstrating the relationship between the lower opening part of a mounting hole, and a condenser lens. It is explanatory drawing which shows an illumination area | region. It is explanatory drawing which shows the relationship between the diameter of a condenser lens, and the magnitude | size of an illumination area. It is a conceptual diagram which shows the passage area | region of the light which passes along a condenser lens. It is explanatory drawing for demonstrating when a rotationally symmetrical condenser lens is arrange | positioned as it is in the lower opening part of an attachment hole. It is explanatory drawing which shows the illumination area | region in said case. It is explanatory drawing which shows the case where the center of an attachment hole and the center of a condenser lens do not correspond. It is explanatory drawing which shows the case where it interferes with a condenser lens in four sides of an attachment hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Condenser lens 1a Front lens group 1b Rear lens group 20 Image pick-up element inspection apparatus 22 Wafer (object to be examined) 26 Inspection illumination device 41 Light source 49 Image pick-up element surface (inspection surface) 49a Illumination area 50 Passing area

Claims (4)

An imaging element inspection illumination optical system used in an imaging element inspection apparatus that determines the quality of an imaging element from an output signal obtained by irradiating illumination light to an imaging element that is a test object,
A condenser lens that irradiates the illumination light emitted from a light source so as to be substantially perpendicular to a surface to be inspected of the image sensor;
When the length in the longitudinal direction or the lateral direction of the illumination area on the surface to be inspected (including the case where the length in the longitudinal direction and the lateral direction are equal) is L,
The distance of the longest part of the width of the passage area when the illumination light irradiated to the illumination area passes through the condenser lens is b, the radius of the condenser lens is R,
The light of the optical system including the condenser lens up to a position that is selected as L and is in the same direction as the longitudinal direction or the short side direction and in which a mounting hole that forms a space in which the condenser lens is mounted interferes with the condenser lens The distance from the axis is d ', the numerical aperture of the condenser lens is NA, the working distance is WD,
In the mounting hole, so as to satisfy the following conditions:
An illumination optical system for inspecting an image pickup element, wherein a condenser lens is disposed by removing a bowed chord portion surrounded by a chord and a subarc from a circular condenser lens having a radius R from the center of the condenser lens by a distance Y. system.
WD × NA + L / 2 <Y <d ′
However, b / 2 <R The condenser lens is sequentially from the light source side.
A front lens group having positive refractive power;
The illumination optical system for imaging device inspection according to claim 1, comprising a rear lens group having a positive refractive power. The distance from the point intersecting the optical axis on the test surface to the outermost side of the illumination area is p, the distance to the main plane of the rear lens group is e ₀ , the numerical aperture is NA, and the effective of the rear lens group Define the maximum diameter φ ₀
Further, the distance from the surface to be inspected along the optical axis, where h is the distance to the end of the mounting hole, and the distance from the optical axis to the mounting hole that interferes with the light incident on the rear lens group Is ψ, and the focal length of the rear lens group is f ₁ ,

The illumination optical system for imaging device inspection according to claim 2, wherein the illumination optical system is configured to satisfy the above condition. The distance from the surface to be inspected to the main plane of the rear lens group is e ₀ , the main plane distance between the rear lens group and the front lens group is e _1, and the distance from the main plane of the front lens group to the pupil is When the distance is e ₂ , the focal length of the rear lens group is f ₁ , the focal length of the front lens group is f _2, and the focal length of the condenser lens is f,

The illumination optical system for imaging device inspection according to claim 2, wherein the illumination optical system is configured to satisfy the above condition.

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