JPH09250905A - Image measuring optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the detectability condition of fluxes contributing to the imaging out of the reflected lights from the surface of an object in an image measuring optical system even when an illumination light is emitted on an inclined object by using only a single illumination system by an adequate arrangement structure. SOLUTION: A half mirror 10 that divides a rear side focus of an objective lens 11 into an illumination optical path and an imaging optical path is provided and a face of an object is irradiated with a Koehler illumination by a differ 9 provided to the rear side focus FB' on the illumination optical path. An image of the diffuser 9, i.e., the size of an illumination pupil is adjusted by means of a diaphragm 13 provided at the rear side focus FB on the imaging optical path. As a result, it is possible to readily optimize detectability condition of fluxes served as imaging in reflection lights reflected by the object even when the illumination light is incident on the inclined object by using a single illumination system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image measuring optical system in an image measuring apparatus used in an IC manufacturing process such as an automatic wire bonder.

[0002]

2. Description of the Related Art In the manufacture of integrated circuits such as ICs and LSIs, a bonding process or the like for connecting a chip having integrated circuits to a package component such as a lead frame is necessary. Before carrying out this bonding step, the IC chip is mounted on the die pad of the lead frame. Then, the positional relationship between the IC chip side and the lead frame determined by this mount is measured by an image measuring device, and the position of wire bonding is adjusted using the measurement result.

The state at this time will be described with reference to FIGS. 14 and 15. FIG. 14 is an explanatory diagram showing a state of image measurement in the lead frame. In the figure, the broken line portion is
It is the reference position 41 of the lead frame, and the solid line shows the lead frame actually copied on the detection screen 42.
The lead frame is provided with a lead portion 43 and a bonding portion 44, and the bonding portion 44 is wire-bonded.

First, as shown in FIGS. 14 (a) and 14 (b), the position of one or a plurality of lead portions 43 to be used as a reference in the lead frame is measured by an image measuring means such as pattern matching. The rotation angle, x,
The deviation from the reference position 41 such as the y coordinate is stored.

Next, image measurement of the bonding position on the chip side is performed. FIG. 15 is an explanatory diagram showing a state of image measurement on the chip side. In the figure, the broken line portion is the reference position 46 of the chip 45 including pads and the like,
The solid line indicates the IC chip 45 actually copied on the detection screen 47.
Is shown. The IC chip 45 is provided with a bonding pad 50 at the tip of a lead portion 49 connected from the wiring portion 48, and wire bonding is performed between the pad 50 and the bonding portion 44 of the lead frame.

Here, as shown in FIGS. 15 (a) and 15 (b), one or more pads 50 having a characteristic lead portion 49 are selected from the bonding pads 50 on the chip to select the pads 50. Similar to the case of the lead frame, the deviation from the reference state 46 is measured and stored.

Thereafter, the relative positional relationship between the lead frame and the bonding pad 50 on the chip is calculated from the measured values of the measured lead frame displacement and pad displacement. Then, by accurately controlling the amount of movement of the stage on which the chip is mounted at the time of bonding, the lead wire is stretched between the pad 50 of the IC chip 45 and the bonding portion 44 of the lead frame based on the calculation result.

[0008]

By the way, the positioning accuracy for mounting the IC chip 45 on the die pad of the lead frame is not always accurate. The positional deviation and the rotational angle deviation are corrected by the image measuring means described above.

However, another problem that occurs when the chip is mounted on the die pad is that the IC chip 45 tilts with respect to the optical axis. Specifically, I
The C-chip is not mounted perfectly perpendicular to the optical axis,
The problem is that it has a slight inclination with respect to this vertical plane.

This is due to non-uniformity of the adhesive layer at the time of chip mounting and tilt deformation of the die pad itself. Here, when the IC chip 45 has a too large inclination with respect to the optical axis, the reflected light on the surface of the IC chip, that is, the object plane, exceeds the aperture of the objective lens only by the coaxial illumination with respect to the optical axis. Will be dark and will hinder measurement.

Therefore, conventionally, the measures as shown in FIG. 16 have been taken. FIG. 16 is a diagram showing a state in which a ring-shaped fiber illumination system 52 is attached around the objective lens 51 as a second illumination system in addition to the coaxial illumination system in the objective lens.

In the conventional image measuring apparatus, such a fiber illumination system 52 or LED is directly connected to the objective lens 51.
In addition, the reflected light from the tilted IC chip can be detected by adding it to the periphery of the device and making the angle of the illumination light sufficiently large.

However, if two illumination systems are provided in this way, the structure becomes complicated. In addition, for example, when a film is formed on the surface of the object to be measured such as an IC chip covered with a protective film, if the film thickness is uneven, the intensity of the reflected light changes due to the influence, and the image measurement can be performed correctly. It may disappear. In this case, the illumination light is changed to near infrared light (for example, wavelength 900
(About 980 nm), the applicant of the present application previously proposed in Japanese Patent Application No. 7-289946, in which the influence of the film thickness unevenness is reduced.
However, there is a problem in that the irradiation wavelength cannot be easily changed when applied to the above.

That is, in this case, it is necessary to change the filter or the light source itself for each of the two illumination light systems. Further, such an image measuring device has a configuration in which the reflected light from the IC chip is separately guided to an observation optical system so that an operator can observe the subject. For this observation, for example, in the technique of controlling the wavelength of the illumination light as described above to deal with the film thickness unevenness of the protective film of the IC chip, when the wavelength of the irradiation light is outside the visible range, Observation becomes difficult, and separate illumination for visual observation is required.

On the other hand, in addition to the above-mentioned problems, the number of bonding pads 502 arranged around the IC chip 501 as shown in FIG. As the size increases, the shape becomes smaller and the array becomes denser.

FIG. 17 is a diagram showing the shape of the peripheral portion of an IC chip which does not have a pad having a characteristic shape. As the pad shape becomes smaller and denser as shown in the same figure, ICs without the bonding pad having the characteristic shape as shown in FIG. 15 are increasing.

Therefore, when selecting the reference position in the IC chip, the wiring pattern 50 is selected from the circuit portion 503 in FIG.
It has become necessary to recognize a relatively characteristic wiring pattern such as No. 4 as a recognition target.

However, when both or one of the bonding pad 502 and the wiring pattern 504 is to be recognized, there are the following difficulties. In general, since the bonding pad 502 is relatively close to a mirror surface, it looks bright by bright field illumination, while the wiring pattern 5
In the case of 04, many satin-like objects appear to be bright by dark-field illumination.

Therefore, when it is desired to include both the bonding pad 502 and the wiring pattern 504 as a reference pattern, it is necessary to illuminate with both bright-field illumination and dark-field illumination at the same time, and either one is used as a reference pattern. If you need to choose one of the lighting.

Further, when both patterns are selected as in the former case, depending on the satin finish of the wiring pattern 504, in order to be able to observe both patterns with the same brightness,
In many cases, it is necessary to appropriately adjust the balance between the intensity of bright field illumination and the intensity of dark field illumination.

In order to solve such a problem, it is conceivable to combine the ring-shaped fiber illumination system 52 shown in FIG. 16 with the coaxial illumination by an LED (not shown). Even with this method, the balance adjustment of the intensities of the bright field illumination and the dark field illumination can be realized to some extent. However, in this case, the illumination system has two systems of the LED light source for coaxial illumination and the ring fiber illumination system, which complicates the configuration of the device.

Further, in this case, the device diameter of the objective lens portion becomes large, and the stage movement amount at the time of wire bonding also becomes large. This causes a problem in manufacturing efficiency that the so-called tact time becomes long.

In addition, since it is difficult to adjust the angular distribution of the illumination light with the illumination by the ring fiber and the bright field illumination and the dark field illumination cannot be clearly separated, there are many difficulties in completely solving the above problems. Accompany it.

The present invention has been made in consideration of such a situation, and the first object thereof is when the illumination light is incident on the inclined object surface and when only a single illumination system is used. However, it is still another object of the present invention to provide an image measurement optical system that can easily optimize the detectable condition of the light flux that contributes to image formation among the light reflected by the object surface.

A second object is to eliminate the influence of the inclination of the object on the illumination condition even when the illumination light is incident on the inclined object surface and only a single illumination system is used. It is to provide an image measurement optical system capable of performing the above.

A third object is to provide an image measuring optical system capable of easily realizing direct visual observation of the measured object regardless of the wavelength of light to be used for imaging the measured object. It is in.

A fourth object is to freely change the brightness of the image of each pattern for a sample in which a pattern having a mirror surface or a surface close thereto and a pattern having a satin surface coexist. Another object of the present invention is to provide an image measurement optical system capable of image measurement using the best pattern according to the purpose.

[0028]

In order to solve the above problems, the invention according to claim 1 provides an image measuring optical system of an image measuring apparatus for recognizing the shape of an object to be measured. Light splitting means for splitting light into an illumination light path and an imaging light path, lens means including at least one lens provided between the object to be measured and the light splitting means, and the lens existing on the imaging light path A stop provided near the rear focal plane of the means, and a light source means for arranging a light source or a light source image near the conjugate position of the rear focal plane existing on the illumination optical path branched by the light branching means. It is an image measurement optical system equipped with.

According to a second aspect of the invention, in the invention according to the first aspect, the illumination light emitted from a certain point of the light source means passes through the lens means, and then the object to be measured is made substantially parallel. The angle formed by the illuminating light and the optical axis is larger than the angle formed by the light and the optical axis, which corresponds to the light emitted from a certain point on the object to be measured and which is limited by the diaphragm and contributes to image formation. Therefore, the image measuring optical system is such that at least one of the lens means, the diaphragm, and the light source means is adjusted.

Furthermore, the invention corresponding to claim 3 is
In the invention according to claim 2, in the light source means, the light source or the light source image is divided into a plurality of groups, and the light amount of the light source or the light source image of each group can be independently adjusted for each group. It is an image measuring optical system provided with an adjusting means.

On the other hand, the invention according to claim 4 is the invention according to claim 3, wherein at least one group among the plurality of groups is arranged in a region corresponding to the inside of the aperture of the diaphragm, and At least one group is
The image measuring optical system is arranged in a region corresponding to the outside of the aperture of the diaphragm.

Therefore, first, in the image measuring optical system of the invention according to claim 1, the illumination light emitted by the optical means is branched by the optical branching means, and then passes through the lens means to be measured. Illuminate. Here, since the light source or the light source image is arranged in the optical means in the vicinity of the conjugate position of the rear focal plane of the lens means existing on the illumination optical path, the object to be measured is substantially Koehler illuminated. Here, the vicinity of the rear focal plane includes the rear focal plane, and the substantially Koehler illumination means the Koehler illumination or almost the Koehler illumination.

A lens generally has a function of converging or diverging a light beam from an object by utilizing a refraction effect. Next, a part of the light emitted from the object to be measured and passing through the lens means is guided to the imaging optical path by the light branching means.

Then, only the light limited by the diaphragm provided in the vicinity of the rear focal plane of the lens means contributes to the image formation to form an optical image. Here, the vicinity of the rear focal plane includes the rear focal plane.

As described above, when the illuminating light to be radiated is substantially Koehler illuminating with good illuminating conditions and the light that contributes to image formation is limited by the diaphragm, the illuminating light is incident on the inclined object plane. In addition, even if only a single illumination system is used, the optical system is adjusted so that the detectable condition of the light flux that contributes to the image formation among the reflected light on the object plane can be easily optimized. It becomes possible.

Next, in the image measuring device of the invention according to claim 2, the same operation as in the invention according to claim 1 is performed, and the lens means is included in the illumination light emitted from a certain point of the light source means. After passing, the angle formed by the light illuminating the object to be measured substantially parallel to the optical axis corresponds to the light emitted from a certain point of the object to be measured, which is limited by the diaphragm and contributes to image formation. At least one of the lens means, the diaphragm, and the light source means is adjusted so as to be larger than the angle formed by the light and the optical axis.

In the light output from the optical system set under such conditions, the reflected light directly contributes to the image formation, so that the illumination light is specularly reflected (specular reflection) on the object to be detected. However, it is possible to capture an image of the object to be detected without a change in brightness with respect to a certain inclination.

Therefore, even when the illumination light is incident on the inclined object surface and only a single illumination system is used, the influence of the inclination of the object on the illumination conditions can be eliminated.

Furthermore, in the image measuring device of the invention according to claim 3, the light source or the light source image is divided into a plurality of groups in the light source means in addition to the same function as the invention according to claim 2. There is.

Further, the light quantity adjusting means adjusts the brightness of the light sources or the light source images of each group independently for each group. Therefore, according to the image measuring optical system corresponding to the present invention, since it is possible to realize bright field illumination and dark field illumination by each group, the intensity ratio of bright field illumination light and dark field illumination light can be freely changed. As a result, it is possible to obtain an image with illumination light that is optimum for the object to be measured having various reflecting surfaces.

On the other hand, in the image measuring device of the invention according to claim 4, the same operation as in the invention according to claim 3 is achieved, and at least one of the plurality of groups is located inside the aperture of the diaphragm. Placed in the area corresponding to
The other at least one group is arranged in a region corresponding to the outside of the aperture of the diaphragm.

By arranging each group in this way, the light source or the light source image distributed in the area corresponding to the inside of the aperture of the diaphragm realizes bright field illumination, and is distributed in the area corresponding to the outside of the aperture of the diaphragm. Since the light source or the image of the light source realizes the dark field illumination, the optimum illumination can be obtained more easily and surely.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. (First Embodiment of the Invention) FIG. 1 is a block diagram showing an example of a wire bonder to which an image measuring apparatus having an image measuring optical system according to a first embodiment of the present invention is applied.

In the present embodiment, as shown in FIG.
Although the image recognition of the pad, the bonding portion position, etc. is performed by the pattern matching described in the prior art with reference to FIG. 15, this process itself is the same as that described with reference to FIGS. The description is omitted.

This wire bonder comprises a bonder head 2 for stretching a wire 1 between an IC chip and a lead frame, and a wire bonding portion composed of peripheral elements (not shown) and I.
An image measurement device including an optical system for capturing an image of the C chip 3 and the lead frame 4 and an image processing position calculation unit 5, and I
It is composed of an XY stage 6 on which the C chip 3 and the lead frame 4 are mounted, and an XY stage unit including an XY stage control drive unit 7 for controlling and driving the XY stage 6.

As shown in FIG. 1, in this image measuring optical system, the light emitted from the light source 8 using the LED is
The objective lens 1 as a lens means is reflected by the half mirror 10 as a light splitting means via the diffuser 9.
1 through the IC chip 3 or lead frame 4
(Hereinafter, also referred to as the object plane) is irradiated and is illuminated with a Koehler. Here, the rear focus of the objective lens 11 is branched by the half mirror 10 into a rear focus FB on the imaging optical path and a rear focus FB 'on the illumination optical path.

The diffuser 9 is provided on the focal plane of the rear focal point FB 'on the illumination optical path, is a scattering plate or a diffusing plate for diffusing the light emitted from the light source 8, and is made of frosted glass. The size of the diffuser 9 is a predetermined size determined by the relationship with the size of the objective lens, as will be described in detail later.

Here, the IC chip 3 provided on the object surface
Are bonded on the die pad on the lead frame 4. Further, the IC chip 3 generated by the irradiation light
Alternatively, the image of the lead frame 4 passes through the objective lens 11 and the half mirror 10, and further, the rear focus FB on the imaging optical path.
An image is formed on the light receiving device of the CCD camera 12 after passing through the diaphragm 13 provided on the focal plane of the image plane, and the image is sent to the image processing position calculation unit 5.

The size of the aperture of the diaphragm 13 is narrowed to a predetermined size determined by the relationship with the illumination system, as will be described in detail later. Further, the diaphragm 13 can change the size of the aperture for adjusting the optical system and the like.

The image processing position calculating section 5 uses the pattern matching method shown in FIGS. 14 and 15 described in the prior art for the lead section / bonding section of the lead frame 4 and the lead section / pad of the IC chip 3, respectively. The rotation from the reference position and the deviation of the XY coordinates are calculated, and the relative position between the two is calculated. The calculation result is sent to the XY stage control drive unit 7.

In this case, in order to obtain an image for pattern matching, image processing is performed using a predetermined threshold value for the intensity of each pixel of the captured image, and further various image processing is performed to capture the image. The shape etc. in the screen are detected.

The XY stage control drive unit 7 is based on the position information about the IC chip 3 and the lead frame 4 such as the relative position information received from the image processing position calculation unit 5 and the XY stage control drive unit 7.
The stage 6 is moved appropriately.

The bonder head 2 stretches the wire 1 between the bonding portion of the lead frame 4 and the pad of the IC chip 3 according to the movement of the XY stage 6 by a bonder head control means (not shown).

Next, the operation of the image measuring apparatus having the image measuring optical system according to the embodiment of the present invention configured as described above will be described. First, this image measurement optical system will be described with reference to FIG.

FIG. 2 is a diagram showing an image measuring optical system according to this embodiment. In this optical system, the light emitted from the light source 8 is uniformly diffused by the diffuser 9, that is, the light uniformly emitted from the entire surface of the diffuser 9 is applied to the object surface 21.

Further, since the diffuser 9 is provided on the rear focal plane of the objective lens (corresponding to the rear focal point FB '),
After passing through the objective lens 11, each light beam emitted from each point of the diffuser 9 becomes a parallel light beam and is applied to the object surface 21.

In the optical system according to the present invention, for example, the light is emitted from the end point 9a of the diffuser 9 and the objective lens 1
The light ray a passing through the effective end point 11a of No. 1 is irradiated to the outermost peripheral point 21a of the illumination field on the object plane 21. A light ray b passing through the effective end point 11a of the objective lens 11 opposite to the effective end point 11a becomes a light ray parallel to the light ray a and is applied to a point 21b on the object plane.

Further, for example, each light beam emitted from the center point of the diffuser 9 passes through the objective lens 11 and then becomes a light beam parallel to the optical axis and is applied to the object surface 21. The illumination system in which the light flux emitted from one point of the light source becomes a parallel light flux after passing through the objective lens and illuminates the object plane is generally called Koehler illumination. The Koehler illumination satisfies the ideal illumination condition for an optical system such as a microscope because bright and uniform illumination is possible.

In the optical system of this embodiment, first, as described above, the light is emitted from the end point 9a of the diffuser 9, and
The size of the diffuser 9 and the size of the objective lens 11 are determined so that the light ray a passing through the effective end point 11a of the objective lens 11 is irradiated to the outermost peripheral point 21a of the illumination field on the object plane 21. At this time, the outermost peripheral point 21a of the illumination field is Koehler-illuminated at the maximum irradiation angle ± θil. Hereinafter, the angle of the irradiation light to the object surface 21 including the maximum irradiation angle θil or the reflected light from the object surface 21 means the angle with respect to the optical axis cc.

On the other hand, of the reflected light on the object plane 21, ±
Although only light rays having an angle within θap pass through the diaphragm 13, the size of the diaphragm 13 is set so that θil> θap. The luminous flux c that has passed through this diaphragm
As a result, an image is formed on the image plane 22 on the CCD camera 12, and an optical image is formed.

When the above conditions are satisfied, the object surface 21 is completely specular, and the irradiation light is specularly reflected (regular reflection).
Even if the object surface 21 is tilted (θil
If it is −θap) / 2 or less, there is no change in the light amount of the light beam c generated by the reflection of the irradiation light.

This means that in FIG. 2, when the inclination of the object plane 21 is (θil−θap) / 2, the reflected light beam c
It can be easily understood from the fact that the light ray c2 of the light rays c1 and c2 located on the outer periphery of the light ray becomes the specular reflection light of the light ray a. Also,
It is clear from the same figure that the irradiation ray for obtaining the ray c1 is obtained from the opposite side.

When the object plane 21 includes a scatterer, the allowable tilt angle becomes larger. From the above, it can be seen that the larger the maximum irradiation angle θil of the light ray a, the larger the object plane allowable tilt angle.
One of the optimal conditions for maximizing the maximum irradiation angle θil and achieving optimal illumination is the condition set in this embodiment. That is, the diffuser 9 is provided on the focal plane corresponding to the rear focal point FB ', and the optical system is configured so that the light from the end point 9a of the diffuser 9 passes through the effective end point 11a of the objective lens 11 and is irradiated to the outermost peripheral point 21a of the illumination field. Is to adjust. The contents will be described with reference to FIGS. 3 and 4.

FIG. 3 is a schematic diagram showing a state when the optical position of the diffuser is changed in the present embodiment.
In the same figure, the size of the diffuser 9 is fixed, and the state of illumination is shown when the diffuser 9 is moved back and forth. For convenience of description, the half mirror 10 is omitted from the figure.

First, it is clear that the maximum irradiation angle θil of the light beam irradiating the outermost peripheral point 21a of the illumination field becomes the largest when it passes through the effective end point 11a of the objective lens.

Here, the diffuser 9 causes the rear focal point FB '.
As described above, the light ray a is incident on the outermost peripheral point 21a of the illumination field with the largest maximum irradiation angle θil. On the other hand, the light beam b is incident on the point 21b, and the light beams a and b are parallel Koehler illumination.

When the diffuser 9 is located in front of the rear focal point FB ', the light ray a passing through the objective lens 11
′ And b ′ are not parallel and illuminate the object surface 21 with divergent light. Similarly, when the diffuser 9 is located behind the rear focal point FB ', the light rays a "and b" are not parallel,
This time, the object plane 21 is illuminated with the convergent light. Therefore, in any case, Kehler illumination cannot be obtained. Therefore, it was confirmed that the first condition for obtaining the maximum maximum irradiation angle θil and for obtaining the Koehler illumination is to dispose the diffuser 9 on the rear focal point FB ′ (for the illumination system, First condition).

Next, the case of changing the size of the diffuser 9 will be described. FIG. 4 is a schematic diagram showing a state when the size of the diffuser is changed in the present embodiment.

In the figure, the state of the illumination is shown when the position of the diffuser 9 is fixed and the size thereof is changed. For convenience of description, the half mirror 10 is omitted from the figure.

First, the light ray a which is incident on the object plane 21 from the end point 9a of the diffuser 9 having the diameter R2 is as described above, and therefore its explanation is omitted. Next, the diffuser 9
Rays a1 and b1 emitted from the center point of are parallel to the optical axis cc, and the irradiation angle is 0 degree.

The light emitted from the point 9a2 having the diameter R1 is incident on the object surface as light rays a2 and b2 having a small incident angle. Here, the ray a2 illuminates the outermost peripheral point 21a of the illumination field, but its incident angle is smaller than the maximum irradiation angle θil obtained by the ray a.

Further, assuming that the diameter of the diffuser is larger, the light emitted from the point 9a3 having the diameter R3 will be considered. This light is a ray a3 having a large incident angle.
It is incident on the object plane 21 as b3. The incident angle at this time is larger than the maximum irradiation angle θil obtained by the light ray a. However, as can be seen from the figure, the ray a3 and its parallel rays cannot illuminate the outermost peripheral point 21a of the illumination field. This is because the effective diameter of the objective lens 11 is insufficient, and the periphery of the visual field becomes dark depending on the tilt of the subject.

Therefore, the size of the diffuser 9 is
It can be seen that the diameter R2 shown in FIG. 4 is sufficient. From the above, the second condition that the maximum maximum irradiation angle θil is obtained and the Koehler illumination is obtained is that the diameter of the diffuser 9 is set so that the light ray passing through the effective end point 11a of the objective lens 11 is the outermost peripheral point 21a of the illumination field. It has been confirmed that the diameter should be the same as or larger than the diameter when illuminating (a second condition for the illumination system).

On the contrary, this condition may be that the size of the objective lens 21 for the diffuser 9 having a constant diameter is equal to or larger than the diameter when the above condition is also satisfied. The condition for realizing the embodiment of the present invention is to adjust the diaphragm 13 so that θil> θap as described above (reflected light detection condition).

Next, regarding the image measuring device shown in FIG.
The specific operation will be described. First, in this image measuring device, the light emitted from the light source 8 is applied to the IC chip 3 that is the object surface 21, is reflected by the IC chip surface, and an image formed by the reflected light that has passed through the half mirror 10 and the diaphragm 13 is CC.
The image is taken by the D camera 12.

At this time, even if the IC chip 3 is tilted, the magnitude of the tilt with respect to the horizontal plane is (θil-θa
If it is p) / 2 or less, the brightness of the image formed on the CCD camera 12 does not change at all even if the reflection on the IC chip 3 is regular reflection.
Therefore, the same imaging result can be obtained as when there is no inclination.

Therefore, after that, the imaged lead portion and pad images are subjected to pattern matching by comparison with the reference position in the image processing position calculation unit 5, and the rotation angle, X
The amount of deviation from the reference position such as the Y coordinate is calculated and stored.

This measurement and calculation are carried out at several points on the IC chip 3. Similarly, the lead frame 4 is similarly irradiated with the light source light, imaged, and pattern matching with the reference position is performed, and the deviation amount from the reference position such as the rotation angle and the XY coordinate is calculated and stored. Also in this case, the image pickup result is not affected by the inclination below the certain level.

Further, from the above both calculation results, the IC chip 3
The relative position with respect to the lead frame 4 is calculated, the information is sent to the XY stage control drive unit 7, and the XY stage 6 is moved by the XY stage control drive unit 7.

Then, the bonder head 2 stretches the wire 1 between the bonding portion of the lead frame 4 and the pad of the IC chip 3 according to the movement of the XY stage 6, and the bonding process is carried out.

As described above, according to the image measuring optical system according to the embodiment of the present invention, the half mirror 10 for branching the rear focus of the objective lens 11 into the illumination light path and the imaging light path is provided, and the illumination light The object surface 21 is Koehler-illuminated by the diffuser 9 provided at the rear focal point FB ′ on the road, and the image of the diffuser 9, that is, the exit pupil of the diffuser 9 is made by the diaphragm 13 provided at the rear focal point FB on the imaging optical path. Since the size can be adjusted, even if the illumination light is incident on the tilted object plane and only a single illumination system is used, the reflected light on the object plane will form an image. The detectable condition of the contributing luminous flux can be easily optimized.

Further, according to the image measuring optical system according to the embodiment of the present invention, since the aperture size of the diaphragm 13 is variable, the above optimization can be appropriately performed. Further, according to the image measuring optical system according to the embodiment of the present invention, the diffuser 9 is satisfied so that the reflected light detection condition is satisfied.
Among the illumination light emitted from a certain point of, among the light emitted from a certain point of the measured object, the angle formed by the light and the optical axis which have passed through the objective lens and are incident substantially parallel to the measured object,
Since the size of the diaphragm is adjusted to be larger than the angle formed by the light axis and the light corresponding to the light limited by the diaphragm and contributing to the image formation, in other words, the diffuser 9
The aperture angle corresponding to the entrance pupil of which image is larger than the aperture angle corresponding to the exit pupil is used. Therefore, when the illumination light is incident on the tilted object plane and only a single illumination system is used. Even in such a case, it is possible to eliminate the influence of the inclination of the object on the illumination condition.

Therefore, it is possible to prevent the decrease in brightness due to the tilt of the subject only by the coaxial illumination, and it is possible to cope with the change in the surface film structure of the subject by changing only one illumination light source. it can.

That is, in the present embodiment, the light source 8
Although an LED is used as the above and a diffuser is used corresponding to this, the present invention is not limited to this combination. For example, this combination
Various combinations of LEDs and diffusers, infrared LEDs and diffusers, fiber bundles and various color filters can be used. Further, the optical system may be configured so that this combination can be freely selected.

As described above, even in the technique using the illumination light source having the optimum wavelength for reducing the influence of the protection film of the IC chip as described above, the necessary illumination light source can be freely provided. . In other words, there is a combined effect that the optimum observation light of near infrared light can be obtained on the image plane with only a single coaxial light source.

Further, as described above, since the size of the diaphragm 13 can be made variable, if the resolution is important, the aperture of the diaphragm 13 should be large, while the inclination of the IC chip should be large. When it is desired to place importance on the tolerance to the and the depth of focus with respect to the surface irregularities, the optical performance can be controlled according to the purpose, for example, by making the aperture of the diaphragm 13 small. This makes it possible to obtain an optimal optical image for various image measurements.

Further, according to the image measuring optical system according to the embodiment of the present invention, the maximum aperture angle is obtained so as to satisfy the first and second illumination conditions, that is, at the outermost peripheral point 21a of the illumination field. So that the diffuser 9 and the objective lens 1
By adjusting the diameter of 1, the object surface 21 can be illuminated most efficiently. That is, in the image measurement optical system of the present embodiment, the value of the tilt of the object that can eliminate the influence on the illumination condition can be maximized.

Therefore, by reliably detecting the IC chip image by the image measuring optical system of the present embodiment, the bonding pad including the bonding pad A is detected in the bonding process.
The relative position between the chip and the lead frame cannot be detected by pattern matching based on the shape of the 1 wiring, and the bonding process can be reliably performed.

Further, in the present embodiment, the diffuser 9 is arranged as the light source means on the focal plane of the rear focal point FB 'on the illumination optical path, and the irradiation light from the diffuser 9 is incident on the object surface 21 as parallel light. Thus, the Koehler illumination is performed, but the present invention is not limited to this, and various light source means can be considered.

That is, the means for obtaining the Koehler illumination is
This is because there are various methods not limited to using the diffuser 9. For example, the focal plane of the rear focus FB 'and the light source 8
Koehler illumination can also be obtained by providing an optical system between and to form an image of the light source on the focal plane of the rear focal point FB '. Further, in some cases, the light source means may be the light source itself. However, in order to obtain the same effect as that of the present embodiment, the size of the light source or the light source image needs to be adapted to the above conditions.

From the above, for example, in the case of the diffuser 9, as the object surface for further diffusing the light from the light source 8,
It can be considered that a surface corresponding to a light source is newly provided on the focal plane of the rear focal point FB '.

As described above, as the light source means, the rear focus F
It will be understood that the focal plane of B ′ may be provided with a light source or an object plane corresponding to the light source or a light source image provided without emitting light by itself.

The image measuring optical system in the present embodiment is premised on the use of Koehler illumination, but if the light source means such as the diffuser 9 is not strictly located at the rear focal point FB ', the present invention can be used. It's not that it can't be effective. That is, even if the position of the light source means such as the diffuser 9 is slightly deviated from the rear focal point FB ′, the same effect as in the case of the present embodiment can be sufficiently obtained.

The illumination in which the position of the light source means such as the diffuser 9 is slightly deviated from the rear focal point FB 'is substantially Koehler illumination as described above. It should be noted that in the case of substantially Koehler illumination (here, except for the case where substantially Koehler illumination is Koehler illumination), the first and second conditions for the illumination system will also be slightly different. (Second Embodiment of the Invention) The image measuring optical system described in the first embodiment is a case where the so-called objective lens has a finite optical system as shown in FIG.

FIG. 5 is a diagram showing an optical system when a finite system is used in the image measuring device. In general, the rear focal point is defined as the point at which a ray incident parallel to the optical axis crosses the optical axis after passing through the optical system. Therefore, in the case shown in the figure,
Assuming that the optical system is the objective lens 11, the rear focal points for the objective lens 11 are FB and FB ′ as described in the first embodiment. The optical system according to the first embodiment of the present invention is realized by providing the diaphragm 13 and the diffuser 9 corresponding to the light source image and the like at the rear focal points FB and FB ′, respectively.

However, the optical system to which the present invention can be applied is not limited to such a finite system. Less than,
A case where the objective lens is an infinite system and a case where the objective lens is a general system will be described in the second embodiment of the invention and the third embodiment of the invention.

FIG. 6 is a diagram showing an image measuring optical system according to a second embodiment of the present invention. The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals and detailed description thereof will be omitted. An infinite system is used as the optical system.

Further, the image measuring apparatus to which the present embodiment is applied, except that the optical system of the objective lens 11 is an infinite system and the image forming lens 23 is provided in front of the image plane 22 corresponding thereto. The device has the same configuration as the device of the first embodiment.

In FIG. 6, the diffuser 9 is provided on the focal plane of the rear focal point FB ', and the illumination system by this is the first condition and the second condition for the illumination system shown in the first embodiment. It is arranged to satisfy the condition of. It should be noted that these conditions may be conditions that result in substantially Koehler illumination.

Further, the diaphragm 13 is provided on the focal plane of the rear focal point FB. By adjusting this diaphragm, the reflected light detection conditions shown in the first embodiment are satisfied. The apparatus to which the image measuring optical system according to the present embodiment configured as described above operates similarly to the case of the first embodiment. (Third Embodiment of the Invention) FIG. 7 is a diagram showing an image measuring optical system according to a third embodiment of the present invention. The same parts as those in FIGS. Detailed description is omitted. A general system is used as the optical system.

In this embodiment, the objective lens is divided into a plurality of groups, and the half mirror for splitting the light is arranged between these groups. That is, the objective lens includes the first group lens 24 and the second group lens 25.

The half mirror 10 is arranged so that the rear focal point of the first group lens 24 is branched into a rear focal point FB1 on the image forming optical path and a rear focal point FB1 'on the illumination optical path.
It should be noted that the rear focal points FB1 and FB1 ′ are merely rear focal points of the first group lens 24, and are the rear focal points of the objective lens including the first group lens 24 and the second group lens 25. Is different. That is, the lens means described in the claims is constituted by the first lens group 24.

Further, the diaphragm 13 is provided on the focal plane of the rear focal point FB1 of the first lens group 24. This diaphragm 13
The reflected light detection condition shown in the first embodiment is satisfied by the adjustment.

On the other hand, the diffuser 9 is the first lens group 2
4 is provided on the focal plane of the rear focal point FB1 '. The illumination conditions including the diffuser 9 and the first group lens 24 are arranged so as to satisfy the first condition and the second condition for the illumination system shown in the first embodiment. It should be noted that these conditions may be conditions that result in substantially Koehler illumination.

The other configuration of the image measuring device to which this embodiment is applied is the same as that of the first embodiment. The apparatus to which the image measuring optical system according to the present embodiment configured as described above operates similarly to the case of the first embodiment.

As described above, the image measuring optical system according to the present embodiment has the same configuration as the image measuring optical system according to the first embodiment, and instead of the rear focus of the objective lens. The rear focus FB1, FB1 'of the first lens group 24
Since the diaphragm 13 and the diffuser 9 are provided in the first embodiment, the same effects as those of the image measuring optical system according to the first embodiment can be obtained in the relationship between the first group lens 24, the diaphragm 13 and the diffuser 9. (Fourth Embodiment of the Invention) FIG. 8 is a diagram showing a main part of an image measuring apparatus using an image measuring optical system according to a fourth embodiment of the present invention, and is the same as FIG. 1 and FIG. The same reference numerals are given to the parts and detailed description thereof will be omitted.

In this image measuring device, a fiber bundle 30 is used as the light source means instead of the light source 8 and the diffuser 9, and an optical filter 31 is provided on the image plane 22 side of the diaphragm 13. The optical filter 30 transmits only near infrared light, for example, and is detachably provided.

Further, an observation objective lens 33 and an eyepiece lens 34 are provided for forming an image of the light reflected by the subject 32 at a position different from the image plane 22. The other configuration of the image measuring device is the same as that of the first embodiment.

Next, the operation of the image measuring apparatus having the image measuring optical system according to the embodiment of the present invention configured as described above will be described. First, the fiber handle 30
The subject 32 such as an IC chip is illuminated with a visible light source including near-infrared light. Here, the effects described in each of the above-described embodiments are achieved due to the relationship between the fiber bundle 30 serving as the light source means, the objective lens 11, and the diaphragm 13.

In addition to this, the half mirror 10 causes the image plane 2
By providing the optical filter 31 provided on the image forming optical path side on the second side, only near-infrared light is extracted from visible light, and reflected light from the subject 32 is supplied to the image plane 22 side. .

The optical filter 31 changes the wavelength range to be transmitted so that the IC chip 3 as the object shown in FIG.
Light having an optimum wavelength can be supplied to the CCD camera 12 in accordance with the state of the upper protective film.

Therefore, it becomes possible to measure the image of the IC chip 3 by extracting the light that minimizes the change in the reflection intensity due to the change in the film thickness. That is, here, there is a combined effect that the optimum observation light of near-infrared light can be obtained on the image plane only by the visible light source containing a single coaxial near-infrared light.

On the other hand, when it is necessary to visually observe the state during the measurement, after the measurement, or after the wire bonding operation, the observation objective lens 33 and the eyepiece lens 34 are used.
The external observation optical system (which is provided as, for example, a binocular stereomicroscope as an actual device) of the object 32 and the IC chip without the need for any other illumination light source. The state of 3 can be observed in an extremely natural state.

The luminous flux illuminating the subject 32 is visible light and has a sufficiently large numerical aperture NA, and the observer can observe the subject 32 under visible light. As described above, the image measurement optical system according to the present embodiment has the same configuration as that of the image measurement optical system according to the first embodiment, and in addition, the visible light including near infrared light can be detected. Since the optical filter 31 that is incident on 32 and extracts the light of a specific wavelength from the reflected light from the subject is provided, only the wavelength light required for imaging can be guided to the image plane side.

Further, according to the image measuring optical system of the present embodiment, an external observation optical system including the observation objective lens 33 and the eyepiece lens 34 is further provided, and the reflected light from the subject, which is visible light, is emitted. Since the observation is conducted by guiding to the external observation optical system, the optimum observation light of near-infrared light can be obtained on the image plane only by the visible light source containing a single coaxial near-infrared light, and The subject can be simultaneously observed with only the same light source.

As a result, handling of the illumination system of the image measuring device becomes extremely easy. In the present embodiment, the fiber bundle 30 is used as the light source means, but the present invention is not limited to this. That is, as described in the first embodiment, for example, a combination of an LED and a diffuser, a halogen lamp as a visible light source, or any other light source including visible light may be used.

Further, in the above description, it was explained that visible light includes near-infrared light, only near-infrared light is made incident on the image plane side, and visible light is used for observation. It is not limited to the case where only near infrared light is included. That is, when it is desired to use light having a specific wavelength in visible light or light having a specific wavelength other than visible light as light for imaging, only the light for imaging is extracted to the image plane side by the action of the optical filter 31, On the other hand, the observation light can be guided to the external observation optical system regardless of this.

Further, the diaphragm 13 is replaceable,
At this time, the optical filter 31 is also replaced at the same time if necessary, so that the image pickup light guided to the image plane 22 side can be adjusted freely. Further, the optical filter 31 may be switchable by mounting various optical filters on a disc to which a plurality of filters can be mounted. (Fifth Embodiment of the Invention) In the present embodiment, an image measuring optical system will be described in the case of simultaneously measuring the image of a rough textured portion and a portion close to a mirror surface.

Originally, a non-mirror surface portion looks bright by dark-field illumination, and a mirror surface portion looks bright by bright-field illumination. Therefore, in the present embodiment, a light source mainly contributing to each illumination is provided, and the light amount of each of these light sources is adjusted to eliminate the contrast between the rough portion and the portion close to the mirror surface. It makes it possible to observe.

FIG. 9 is a diagram showing an image measuring optical system according to the fifth embodiment of the present invention. This image measurement optical system
It is applied to the wire bonder shown in FIG. 1, and the same portions as those in FIGS. 1 and 2 are denoted by the same reference numerals and the description thereof will be omitted. Here, only different portions will be described.

In this image measuring device, the light source device has a light source circuit composed of a plurality of LEDs 107, 108a to 108h, an adjusting unit 100 for adjusting the light amount of the LEDs, and a DC power supply 109, and variable resistors 110 and 111 of the adjusting unit 100. The illumination control device 101 controls the resistance value of 1 to adjust the bright and dark field illumination, and has the same configuration as that of the first embodiment.

The LED 107 is arranged on the rear optical axis of the diffuser 9 as shown in FIG. 9, and mainly contributes to bright field illumination. The variable load resistor 111 is also connected to the DC power source 109. This LE is near the mirror surface
It is brightly observed by D107.

The LEDs 108a to 108h are arranged on the outer periphery of the back surface of the diffuser 9 as shown in FIGS. 9 and 10, and mainly contribute to dark field illumination. Further, the variable load resistor 110 is connected to the DC power source 109.
The rough portion is brightly observed by these LEDs 108a to 108h even in the case of bright field illumination.

FIG. 10 is a view of each LED in this embodiment as viewed from the diffuser 9 side. The LED 10
7, 108a to 108h are adjusted in size and number of LEDs, as well as arrangement, shape and mounting direction so that the bright and dark field illumination can be freely adjusted.

The illumination control apparatus 101 sets the resistance values of the variable resistors 110 and 111, respectively, so that the LED 107 that contributes to the bright field illumination and the LE that contributes to the dark field illumination.
The light amount of D108a to 108h is adjusted. Since this light amount balance varies depending on the LSI or the like as the measurement target, the illumination control device 101 uses the variable resistor 11 for each measurement target.
The adjustment values of 0 and 111 are stored, and when a measurement target management unit (not shown) receives a measurement target instruction, the resistance values of the variable resistors 110 and 111 are set corresponding to the measurement target.

Next, an image measuring optical system having such a light source device will be described with reference to FIG. First, the rear focus of the objective lens 11 is branched by the half mirror 10 into FB ′ on the illumination light path side and FB on the imaging light path side. The diffuser 9 is placed on the back focal plane FB ′ on the side of the illumination optical path, and the LED 107 and the LEDs 107
108a-LED108h are arrange | positioned.

Regarding the size of the diffuser 106, the outermost peripheral point 21a of the illumination field is the maximum illumination angle ± in consideration of the focal length of the objective lens 11, the working distance WD, and the effective diameter.
Limited to Kehler illumination at θ _il . This ensures that the brightness in the illumination field is uniform.

On the other hand, the diaphragm 13 is provided on the rear focal plane FB of the image-side optical path, and only the light rays having an angle within ± θ _ap among the reflected light from the object plane 21 pass therethrough to form an image. Surface 2
Image to 2.

Here, bright-field illumination is to illuminate the object to be measured with light within an angle corresponding to the numerical aperture NA of the portion of the objective lens involved in image formation, and if θ _il > θ _ap Then, an angle θ within θ _ap (that is, θ _il > θ _ap and θ
Illumination light with _ap ≧ θ) acts as brightfield illumination. The same applies to the case where-? _Il <-? _Ap and-? _Ap ≤ ?.

On the other hand, if the dark-field illumination is to illuminate the object to be measured with light having an angle wider than the angle corresponding to the numerical aperture NA of the portion of the objective lens involved in image formation,
Illumination light having an angle θ larger than θ _ap (that is, θ _ap <θ) will act as dark field illumination. Also,-
The same applies when θ _ap > θ.

Therefore, as can be seen from FIG. 9, the bright field illumination light is mainly formed by the luminous flux from the LED 107, and the dark field illumination light is mainly the LEDs arranged in a ring shape.
It is formed by the light flux from 108.

Furthermore, the LED 107 and the LED 108 are
The brightness is independently controlled by the illumination control circuit 101 and the variable resistors 110 and 111, and the light amount balance is set so as to correspond to the measurement target.

As a result, the brightness of the bright field illumination and the brightness of the dark field illumination are independently adjusted, and the contrast between the rough portion and the portion close to the mirror surface is adjusted. Therefore, specifically, for example, the appearance of the pad 501 and the wiring pattern 504 in FIG. 17 can be freely set. Then, an optimum standard pattern (setting pattern) stored in the illumination control circuit 101 is automatically selected for various types of ICs.

As described above, according to the image measuring optical system of the embodiment of the present invention, in addition to the same structure as that of the first embodiment, two light sources capable of independently adjusting the brightness are provided. Since the bright field illumination and the dark field illumination can be realized simultaneously and independently, an image of each pattern can be obtained for a sample in which a pattern with a mirror surface or a surface close to it and a pattern with a satin surface coexist. The brightness of can be changed freely. Therefore, the image can be measured using the best pattern according to the purpose.

Further, according to the present embodiment, since the above-mentioned bright and dark field simultaneous illumination can be realized by the conventional illumination through the objective lens, when the dark field illumination is realized, the illumination from the outside of the objective lens is performed. It is not necessary to provide a system, and the size of the illumination system, particularly the device diameter of the objective lens portion, can be made sufficiently smaller than the case where a ring illumination is used externally.

Therefore, the amount of stage movement during wire bonding can be reduced. As a result, the tact time can be shortened and the IC manufacturing efficiency can be improved.

In the present embodiment, the variable load resistor 110 is common to the LEDs 108a to 108h, but the present invention is not limited to this, and each of them has its own variable load resistor and has independent brightness. May be adjustable. Of course, the power source 109 may be an individual variable power source.

Further, in the present embodiment, the LEDs are arranged on the back surface of the diffuser 9. However, for example, without using the diffuser 9, each LED is arranged on the rear focal plane FB ′ on the illumination optical path side. May be. At this time, the measurement target may be made clearer depending on the illumination conditions. (Sixth Embodiment of the Invention) In the above fifth embodiment, the case where the LED is used as the light source has been described, but in the present embodiment, the case where the fiber bundle is used will be described.

FIG. 11 is a diagram showing a light source section in the image measuring optical system according to the sixth embodiment of the present invention. The present embodiment is configured similarly to the fifth embodiment except for this light source.

As shown in FIG. 11, a light source surface 116 is formed at the tips of the fiber bundles 112 and 113.
This light source surface 116 is arranged instead of or immediately after the diffuser 9.

Here, the central bundle 113 and the peripheral bundle 112 are led to individual light sources 114 and 115, respectively. Then, by adjusting the brightness of each of the light sources 114 and 115 by a circuit similar to that of FIG. 9, it is possible to independently control the light amount from the light source surface by both bundles.

Bright-field illumination light at an angle smaller than the aperture angle θ _ap in FIG. 9 is supplied by the bundle 113, and dark-field illumination light larger than the aperture angle θ _ap is
Supplied by bundle 112. The bundles 112 and 113 do not have to be spaced, but it is desirable to have a slight spacing in order to more clearly distinguish and control the effects of the bright field and the dark field.

As described above, according to the image measuring optical system of the embodiment of the present invention, the same structure as that of the fifth embodiment is provided and, in addition to the LED, the fiber bundle is used for simultaneous bright and dark field illumination. Since it is realized, the same operational effect as that of the fifth embodiment can be obtained.

Further, since the light source surface is constituted by the fiber bundle, it is possible to realize a more precise light source arrangement. (Seventh Embodiment of the Invention) In the above fifth embodiment, the case where nine LEDs are used as the light source has been described, but in the present embodiment, a case where a larger number of LEDs are used will be described.

FIG. 12 is a diagram showing a light source surface in the image measuring optical system according to the seventh embodiment of the present invention. The present embodiment is configured similarly to the fifth embodiment except for this light source.

In FIG. 12, a large number of LEDs 117a-d and 118a-d are arranged on the light source surface 116 which should be arranged instead of or immediately after the diffuser 9. Four LEDs are provided on each of the LED section 117 on the optical axis and the six LED sections 118 on the periphery,
The brightness can be adjusted for each LED.

As described above, according to the image measuring optical system according to the embodiment of the present invention, in addition to the configuration similar to that of the fifth embodiment, the number of LEDs is increased and the light quantity is adjusted for each. Since it is possible to do so, in addition to the same effect as the fifth embodiment, more precise illumination adjustment can be performed. (Eighth Embodiment of the Invention) In this embodiment, a case will be described in which a larger number of LEDs are used than in the seventh embodiment.

FIG. 13 is a diagram showing a light source surface in the image measuring optical system according to the eighth embodiment of the present invention. The present embodiment is configured similarly to the fifth embodiment except for this light source.

In FIG. 13, a large number of LEDs 119a to 119g, 120a to 120l, are arranged on the light source surface 116 to be arranged instead of or immediately after the diffuser 9.
121a to 121p and 122a to 122x are arranged.

These LEDs are arranged in a ring shape on the light source circle 119 and the light source wheels 120 to 122. Each LE
Regarding D, the brightness can be adjusted for each ring or for each LED.

As described above, according to the image measuring optical system according to the embodiment of the present invention, in addition to the structure similar to that of the fifth embodiment, a large number of LEDs are arranged in a ring shape and the light amount of each LED is set. Since the adjustment can be performed, the same operational effect as that of the fifth embodiment can be obtained, and more precise illumination adjustment can be performed.

In the present embodiment, an example using LEDs has been described, but instead of each LED shown in FIG. 13, each LED is configured with an optical fiber to form a fiber bundle, and the brightness can be adjusted independently for each fiber. You may

In the case of FIGS. 12 and 13, the number of LEDs and the number of fibers may be further increased. The present invention is not limited to the above embodiments, and can be variously modified without departing from the gist thereof.

Although the present invention has been described above based on the embodiments, the present invention also includes the following inventions. (1) In an image measuring optical system of an image measuring device for recognizing the shape of an object to be measured, an optical branching unit for branching light from the object to be measured into an illumination optical path and an image forming optical path; and the object to be measured. Lens means including at least one lens provided between the light branching means, an aperture provided near the rear focal plane of the lens means existing on the imaging optical path, and the light branching means. An aperture corresponding to an entrance pupil having the light source means as an image, the light source means comprising a light source or a light source image near the rear focal plane of the lens means existing on the illumination optical path branched by An image measurement optical system characterized in that an angle is made larger than an opening angle corresponding to an exit pupil. (2) In the image measuring optical system of the image measuring device for recognizing the shape of the object to be measured, an optical branching unit for branching the light from the object to be measured into an illumination optical path and an imaging optical path, and the object to be measured. Lens means including at least one lens provided between the light branching means, an aperture provided near the rear focal plane of the lens means existing on the imaging optical path, and the light branching means. Light source means formed by arranging a light source or a light source image in the vicinity of the rear focal plane of the lens means existing on the illumination light path branched by After passing through the lens means, the angle formed by the light illuminating the object to be measured substantially in parallel and the optical axis is limited by the diaphragm among the light emitted from a certain point of the object to be measured. Corresponds to the light that contributes to the image At least one of the lens means, the diaphragm, and the light source means is adjusted so that the angle formed by the light and the optical axis is larger than the angle formed and the entire illumination field is illuminated by the illumination light. Image measurement optical system characterized by. (3) In the image measuring optical system of the image measuring device for recognizing the shape of the object to be measured, an optical branching unit that branches the light from the object to be measured into an illumination optical path and an imaging optical path, and the object to be measured. A lens means including at least one lens provided between the light branching means and a rear focal plane of the lens means existing on the imaging optical path is provided, and the aperture size is variable. An image comprising a stop and a light source means for arranging a light source or a light source image near a rear focal plane of the lens means existing on the illumination optical path branched by the light branching means. Measurement optics. (4) Of illumination light emitted from a certain point of the light source means, an angle formed by the light illuminating the object to be measured substantially parallel after passing through the lens means and the optical axis is the object to be measured. Of the light emitted from a certain point, the angle of the lens means, the diaphragm, and the light source means is made larger than the angle formed by the light axis and the light corresponding to the light that contributes to image formation by being restricted by the diaphragm. The image measuring optical system according to (3), characterized in that at least one of them is adjusted. (5) In the image measurement optical system of the image measuring device for recognizing the shape of the object to be measured, an optical branching unit that branches the light from the object to be measured into an illumination optical path and an imaging optical path, and the object to be measured. Lens means including at least one lens provided between the light branching means, an aperture provided near the rear focal plane of the lens means existing on the imaging optical path, and the light branching means. On the imaging optical path, a light source means including a light source or a light source image containing at least visible light and near-infrared light near the rear focal plane of the lens means existing on the illumination optical path branched by And an optical filter provided on the image measuring optical system. (6) The image measuring optical system according to (5), wherein the optical filter is freely inserted into and removed from the imaging optical path. (7) The image measurement optical system according to (5), further comprising an observation optical system capable of visually observing the object to be measured. (8) In the image measurement optical system of the image measurement device, which captures the shape of the measured object by guiding the reflected light from the measured object with respect to the irradiated light to the imaging optical path, the irradiated light is An optical filter including at least visible light, and an observation optical system that enables visual observation by guiding a part of the reflected light from the object to be measured to an observation optical path, and an optical filter provided on the imaging optical path. An image measurement optical system characterized by being provided. (9) The light amount adjusting means adjusts the brightness of the light source or the light source image of each group according to a predetermined setting pattern selected according to the type of the object to be measured. The image measurement optical system described. (10) The image measuring optical system according to claim 1 or 2, wherein the light source means is a light source or a light source image containing at least visible light, and has an optical filter on the imaging optical path.

The effects of the above (1) to (10) will be described. First, in the image measurement optical system of the invention of (1),
The illumination light emitted by the light source means is branched by the light branching means, and then passes through the lens means to illuminate the object to be measured. Here, since the light source means is arranged with the light source or the light source image in the vicinity of the rear focal plane of the lens means existing on the illumination optical path, the object to be measured is substantially Koehler illuminated.

Next, a part of the light emitted from the object to be measured and having passed through the lens means is guided to the image forming optical path by the light branching means. Then, only the light limited by the diaphragm provided in the vicinity of the rear focal plane of the lens means contributes to the image formation and forms an optical image.

As described above, the illuminating light to be emitted is substantially Koehler illumination with good illumination conditions, and the aperture angle corresponding to the entrance pupil whose image is the light source means corresponds to the exit pupil by adjusting the diaphragm, for example. Since the aperture angle is larger than the aperture angle, the influence of the tilt of the object on the lighting conditions is affected even when the illumination light is incident on the tilted object surface and only a single illumination system is used. Can be eliminated.

In the image measuring optical system of the invention (2), the illumination light emitted by the light source means is branched by the light branching means, and then passes through the lens means to illuminate the object to be measured. Here, since the light source means is arranged with the light source or the light source image in the vicinity of the rear focal plane of the lens means existing on the illumination optical path, the object to be measured is substantially Koehler illuminated.

Next, a part of the light emitted from the object to be measured and having passed through the lens means is guided to the image forming optical path by the light branching means. Then, only the light limited by the diaphragm provided in the vicinity of the rear focal plane of the lens means contributes to the image formation and forms an optical image.

Of the illumination light emitted from a certain point of the light source means, after passing through the lens means, the angle between the light that illuminates the object to be measured substantially parallel and the optical axis is the light emitted from a certain point. Among them, so that it is larger than the angle formed by the light and the optical axis corresponding to the light that is limited by the diaphragm and contributes to image formation, and the entire illumination field is illuminated by the illumination light,
At least one of the lens means, the diaphragm, and the light source means is adjusted.

In the light output from the optical system set under such conditions, the reflected light directly contributes to the image formation, so that the allowable inclination of the object to be detected can be maximized. Further, the illuminating light to be emitted is a substantially Koehler illumination with good illumination conditions.

Therefore, even when the illumination light is incident on the inclined object surface and only a single illumination system is used, the influence of the inclination of the object on the illumination conditions can be eliminated.

Next, in the image measuring optical system of the invention corresponding to (3), the illumination light emitted by the light source means is branched by the light branching means, and then passes through the lens means to move the object to be measured. Illuminate almost Kera.

Next, a part of the light emitted from the object to be measured and passing through the lens means is guided to the image forming optical path by the light branching means. Then, only the light limited by the diaphragm having an adjustable aperture size provided near the rear focal plane of the lens means contributes to the image formation and forms an optical image.

As described above, when the illuminating light to be radiated is substantially Koehler illuminating under good illuminating conditions, and the light contributing to image formation is limited by the diaphragm, the illuminating light is incident on the inclined object plane. In addition, even if only a single illumination system is used, the optical system is adjusted so that the detectable condition of the light flux that contributes to the image formation among the reflected light on the object plane can be easily optimized. It becomes possible.

Further, since the aperture size of the diaphragm is variable, it becomes easier to optimize the detectable condition. further,
In the image measuring device of the invention corresponding to (4),
Besides operating similarly to the invention corresponding to (3), since the aperture size of the diaphragm is made variable, the conditions in the optical system can be adjusted appropriately.

Further, in the image measuring optical system of the invention corresponding to (5), the illumination light emitted by the light source means including visible light and near infrared light is branched by the light branching means, and then the lens means. The object to be measured is passed through the illuminator and is illuminated with a substantially Kehler.

Next, a part of the light emitted from the object to be measured and passing through the lens means is guided to the image forming optical path by the light branching means, and further only the near infrared light is taken out by the optical filter.

On the other hand, since it is possible to guide a part of the visible light reflected by the object to be measured to another optical system, for example, when it is desired to visually observe the object to be measured, the realization thereof is extremely easy.

Furthermore, in the image measuring optical system of the invention corresponding to (6), not only the same operation as in the invention corresponding to (5) but also the optical filter can be freely taken in and out from the image forming optical path. It becomes easy to adjust the wavelength of the light that contributes to the imaging of the object to be measured.

On the other hand, in the image measuring optical system of the invention corresponding to (7), the same operation as in the invention corresponding to (6) is provided, and since the observation optical system capable of visual observation is provided, the visible light is actually used. The object to be measured can be visually observed.

Further, the image measuring optical system of the invention corresponding to (8) images the shape of the object to be measured by recognizing the image by guiding the reflected light from the object to be measured with respect to the irradiation light to the imaging optical path. Used in image measurement devices.

At this time, the irradiation light contains at least visible light. Further, the optical filter extracts only the wavelength light that contributes to the imaging of the object to be measured on the imaging optical path.

Further, since a part of the reflected light from the object to be measured is guided to the observation optical path of the observation optical system, the object to be measured can be visually observed. Furthermore, in the image measuring optical system of the invention corresponding to (9), the same operation as the invention corresponding to claim 3 or 4 described in the means for solving the problem is achieved,
The light amount adjusting means adjusts the brightness of the light source or the light source image of each group according to a predetermined setting pattern selected according to the type of the object to be measured.

Therefore, for simultaneous illumination of the bright and dark fields, it is possible to automatically set the illumination system according to the object to be measured. Furthermore, in the image measuring device of the invention corresponding to (10), the light source means includes at least visible light in addition to the same function as the invention according to claim 1 or 2.

Therefore, for example, when it is desired to visually observe the object to be measured separately, the realization thereof is extremely easy. Further, the wavelength light necessary for image recognition of the object to be measured may be included in the irradiation light in advance, and may be guided to the imaging optical path when passing through the optical filter.

By doing so, the influence of the tilt of the object on the illumination condition is eliminated by the only coaxial light source, and only the wavelength light necessary for recognizing the image of the object to be measured is guided to the imaging optical path. It becomes possible to directly visually observe the object to be measured.

That is, it is possible to provide an image measuring optical system capable of easily realizing direct visual observation of the object to be measured regardless of the wavelength of light to be used for imaging the object to be measured.

[0179]

As described above in detail, according to the present invention, even when the illumination light is incident on the tilted object plane and only a single illumination system is used, the object plane on the object plane is not changed. It is possible to provide an image measurement optical system that can easily optimize the detectable condition of the light flux that contributes to image formation in the reflected light.

Further, according to the present invention, even when the illumination light is incident on the inclined object plane and only a single illumination system is used, the influence of the inclination of the object on the illumination condition is eliminated. It is possible to provide an image measuring optical system capable of performing the above.

Furthermore, according to the present invention, for a sample in which a pattern having a mirror surface or a surface close thereto and a pattern having a satin surface coexist, the image brightness of each pattern can be freely changed. Further, it is possible to provide an image measuring optical system capable of performing image measurement using the best pattern according to the purpose.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a wire bonder to which an image measuring device according to a first embodiment of the present invention is applied.

FIG. 2 is a diagram showing an image measurement optical system according to the same embodiment.

FIG. 3 is a schematic diagram showing a state when the optical position of the diffuser is changed in the same embodiment.

FIG. 4 is a schematic diagram showing a state in which the size of the diffuser is changed in the same embodiment.

FIG. 5 is a diagram showing an optical system when a finite system is used in the image measuring device.

FIG. 6 is a diagram showing an image measurement optical system according to a second embodiment of the present invention.

FIG. 7 is a diagram showing an image measurement optical system according to a third embodiment of the invention.

FIG. 8 is a diagram showing an image measurement optical system according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing an image measurement optical system according to a fifth embodiment of the present invention.

FIG. 10 is a view of each LED in the same embodiment as viewed from the diffuser side.

FIG. 11 is a diagram showing a light source unit in an image measuring optical system according to a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a light source surface in an image measuring optical system according to a seventh embodiment of the present invention.

FIG. 13 is a diagram showing a light source surface in an image measuring optical system according to an eighth embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a state of image measurement in a lead frame.

FIG. 15 is an explanatory diagram showing a state of image measurement on the chip side.

FIG. 16 is a diagram showing a state in which an illumination system different from the coaxial illumination system is added to the objective lens.

FIG. 17 is a view showing a shape of an IC chip peripheral portion which does not have a pad having a characteristic shape.

[Explanation of symbols]

1 ... Wire, 2 ... Bonder head, 3 ... IC chip, 4 ...
Lead frame, 5 ... Image processing position calculation unit, 6 ... XY stage, 7 ... XY stage control drive unit, 8 ... Infrared LE
D, 9 ... Diffuser, 9a ... Diffuser end point, 1
0 ... Half mirror, 11 ... Objective lens, 11a, 11b
... Effective end point of objective lens, 12 ... CCD camera, 13 ...
Aperture, 21 ... Object plane, 21a ... Outermost point of illumination field, 22 ... Image plane, 23 ... Imaging lens, 24 ... First group lens, 25 ... Second group lens, 30 ... Fiber bundle, 31 ... Optical filter, 107, 108 ... LED, 110, 111 ... Variable resistance, 112, 113 ... Fiber bundle, FB ...
Rear focal point of objective lens on imaging optical path, FB '... Rear focal point of objective lens on illumination optical path, FB1 ... First on imaging optical path
Rear focal point of the group lens, FB '... Rear focal point of the first group lens on the illumination optical path.

Claims (4)

[Claims] 1. An image measuring optical system of an image measuring device for recognizing the shape of an object to be measured, the optical branching means for branching light from the object to be measured into an illumination optical path and an image forming optical path. A lens unit including at least one lens provided between the object and the light splitting unit, an aperture provided near the rear focal plane of the lens unit existing on the image forming optical path, and the light An image measuring optical system, comprising: a light source or a light source means for arranging a light source image near a conjugate position of the rear focal plane existing on the illumination optical path branched by the branching means. 2. An angle formed by an optical axis of the illumination light emitted from a certain point of the light source means and passing through the lens means and then illuminating the object to be measured substantially in parallel is the object to be measured. Of the light emitted from a certain point of an object, the lens means, the diaphragm, and the light source are set to be larger than the angle formed by the optical axis and the light corresponding to the light that is limited by the diaphragm and contributes to image formation. The image measuring optical system according to claim 1, wherein at least one of the means is adjusted. 3. In the light source means, the light source or the light source image is divided into a plurality of groups, and the brightness of the light source or the light source image of each group can be adjusted independently for each group. The image measuring optical system according to claim 2, further comprising means. 4. At least one of the plurality of groups
One group is arranged in a region corresponding to the inside of the aperture of the diaphragm, and another at least one group is arranged in a region corresponding to the outside of the aperture of the diaphragm. 3. The image measurement optical system described in 3.