JP2880358B2 - Lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device incorporated in a bonding wire inspection device for inspecting and measuring the shape of a bonding wire.

[0002]

2. Description of the Related Art Conventionally, as a method of inspecting a bonding wire, a method of visually inspecting by a human or a two-dimensional, three-dimensional
A method for performing inspection by performing dimensional image processing is known. In these inspection methods, extremely common light sources such as halogen lamps and fluorescent lamps are used. Japanese Patent Application Laid-Open No. 63-275129 discloses an invention in which a light beam for illuminating a loop of a bonding wire is made into a wedge-shaped light beam. However, usually, as disclosed in Japanese Patent Application Laid-Open No. 1-116405, the bonding wire and the lamp house often face each other in a direction orthogonal to each other and are inclined.
Further, as shown in DE (Germany) Application No. 4003983, a method is known in which a camera is installed in a vertical direction, and a light source portion is formed in an arc shape (hemispherical shape) to irradiate the light.

As shown in FIG. 8, as an oblique illumination device, a light source 90 is configured independently of a distance to a sample surface 91 and an optical system of an objective lens 95 and a microscope 96. Japanese Patent Application Laid-Open No. Sho 50-461 discloses an arrangement having a degree of freedom in the distance directionality.
As shown in FIG. 51, a configuration is known in which a plurality of independent light sources are connected to the axis of an optical system using a fixture.

[0004]

In a bonding wire inspection apparatus, it is necessary to accurately determine the position and shape of a ball, a crescent, a wire, and the like in order to accurately inspect and manage the bonding state of the wire.

[0005] However, according to the above-mentioned conventional example, since no special measures have been taken for the illumination light source and the illumination method of the light source, it is difficult to observe the IC chip surface as seen by observing the IC chip surface with a TV camera or the like. Has become. Because the ball, crescent, and wire are all metal, and the shape is not a plane but a sphere,
Shadows cannot be removed with conventional lighting methods.
In addition, noise light due to scattered light and reflected light also exists, which causes a large error in measurement.

Therefore, when judging the position of a ball, a crescent, and a wire, which are the subject, and judging the shape, illumination conditions (bright field illumination, dark field illumination, critical illumination, It is desirable to perform this by changing the Koehler illumination. For example, a ball,
For an object having a three-dimensional shape such as a wire, to determine its position, the illumination mode of bright-field critical illumination is combined with an observation system with a small depth of focus, and the object and the observation system are relatively positioned. By displacing, the shape can be recognized from the image signal passed through the observation system and the amount of displacement. In addition, in order to inspect the relative displacement between the IC and the bonding pad position of the IC with the crescent, ball, etc., the illumination form of the dark field / Koehler illumination that emphasizes the edge of minute unevenness and the depth of focus and It is desirable to observe in combination with an observation system.

However, it is easy to appropriately set the depth of focus of the observation system by changing the aperture filter on the pupil plane of the observation system, selecting a combination of light source wavelengths, and the like, but the means for changing the illumination form has a completely different configuration. Since it is not easy, even if it can be done easily, it takes a long time to exchange it and it is not at a practical level.

Further, according to the conventional oblique lighting device,
When using the oblique illumination device, when replacing the oblique illumination, when displacement occurs in the height direction of the sample, when changing the mounting position of the oblique illumination system, and when using multiple light sources, However, there is a drawback in that it is necessary to correct all the light sources so that the irradiation direction is at an appropriate position by using an observation device of an optical system in which the oblique illumination device is used or a dedicated measuring device. Further, there is a disadvantage that compatibility between the devices is lacking because the mounting method of the illumination device differs depending on the microscope.

[0009] More specifically, in the example shown in FIG. 9, illumination by the illumination device 98 is performed from an oblique direction so as to be orthogonal to the bonding wire 94. In this case, the bonding wire 94 that does not intersect with the lighting device 98
In the case of, the XY stage 92
It must be measured after moving. Therefore, measurement is troublesome and extremely complicated IC
In the case of the element configuration, the direction and the number of wire bonding are enormous, and such an illumination method is extremely inconvenient.

In the example shown in FIG. 10, illumination from a hemispherical illumination device 97 is uniformly radiated on the chip 93 from above and from the side of the chip 93, but the position of the camera 99 is mainly shown in FIG. As shown, the vertical direction is advantageous, and if you try to measure at an oblique camera position,
A part of the hemisphere must be slit-shaped, and an opening must be provided to enable photographing with a camera. Such a configuration is not preferable because it is structurally complicated and the amount of illumination light is correspondingly lost. Furthermore, it is impossible to use both epi-illumination and ring illumination. Furthermore, it is impossible to use both epi-illumination and dark-field illumination.

SUMMARY OF THE INVENTION In view of the problems of the prior art, it is an object of the present invention to easily select or use various illumination methods in an illumination device, and to provide an illumination device for an observation optical system. The object is to eliminate the need for positional correction.

[0012]

In order to achieve the above object, an illuminating device according to the present invention comprises a light source, a convex mirror disposed between the light source and an object to be illuminated, and reflecting illumination light from the light source. A concave mirror that is arranged on the side opposite to the illumination object with respect to the convex mirror and irradiates the illumination object by condensing the illumination light reflected by the convex mirror, wherein the convex mirror is a translucent mirror, and It is arranged on a straight line connecting the light source and the illumination target.

[0013]

Further, another illuminating device of the present invention is an intermediate member mounted so that an objective lens of a microscope for observing an object to be illuminated is at a fixed position with respect to the microscope main body, and fixed to the intermediate member. A light source for illuminating the object to be illuminated, wherein the objective lens is configured such that when attached to the intermediate member, the positional relationship between the focal position of the objective lens and the intermediate member is constant. And the positional relationship between the light source and the intermediate member is constant.

Further, another illuminating device of the present invention is a convex mirror which is arranged on a straight line connecting an observation optical system and an object to be illuminated thereby and has a transparent central portion and a reflective side surface; Means for introducing external illumination light to the optical axis of the observation optical system in the direction of the convex mirror, and disposing between the convex mirror and the observation optical system so that the illumination light is not vignetted on the side surfaces of the convex mirror. An aspherical mirror that reflects the illumination light reflected by the convex mirror, means for moving the convex mirror along the optical axis of the observation optical system, and a cross-sectional shape of the illumination light having a ring shape and a circular shape. Means for changing between the two, and when this is a ring shape, illuminating the object to be illuminated by irradiating the illumination object via the side surface of the convex mirror and the aspherical mirror to perform dark field illumination. The convex Mira Illuminating bright field by the irradiation in the central portion the object to be illuminated by transmitting.

In any case, the illumination light from the light source is configured to be focused on the focal position of the objective lens, and the illumination light from the light source is configured to uniformly illuminate the focal position of the objective lens. There are cases.

The object to be illuminated is a ball, a crescent, a wire, or the like of an IC element, and is used in a wire bonding inspection apparatus that measures the shape, size, and position thereof.

[0018]

In this configuration, a large concave mirror and a small convex mirror are provided, and the small convex mirror is a translucent mirror, or the central portion thereof is transparent, and the sectional shape of the illumination light can be changed between a ring shape and a circular shape. Thus, one illumination device simultaneously or selectively performs epi-illumination by illumination light passing through the convex mirror and dark-field illumination by ring-shaped illumination light reflected by the convex mirror.

Further, a light source is fixedly attached to an intermediate member for attaching the objective lens to the microscope main body,
The objective lens is configured such that the positional relationship between the focal point of the objective lens and the intermediate member is constant when attached to the intermediate member, and the positional relationship between the light source and the intermediate member is also constant. The irradiation direction is uniquely defined with respect to the microscope objective mounting portion, so that it is not necessary to readjust the light source when attaching or detaching the objective lens. Specifically, for example, the outer diameter and pitch of the microscope objective lens mounting screw are standardized, and the distance from the microscope objective lens mounting surface to the microscope objective lens focal position is defined as a constant distance as the parfocal distance. I have. And, as described above, by sharing the objective lens mounting surface and the light source mounting reference surface and placing them in a fixed positional relationship, the positional relationship between the mounting position of the illumination device and the focal position of the objective lens is made constant, The light source is arranged at a fixed position with respect to the focal position of the objective lens.

Other operations of the present invention will be described in further detail below.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a schematic diagram showing a lighting device according to an embodiment of the present invention. This device is for illuminating a bonding wire on a semiconductor IC chip 1 and is arranged vertically above the semiconductor IC chip 1 mounted on an XY stage, and is composed of a halogen lamp, a laser, and the like. Light source 1
0, a small convex mirror 7 disposed between the semiconductor IC chip 1 and the illumination light source 10 and reflecting light from the illumination light source 10 in the opposite direction, and disposed between the illumination light source 10 and the convex mirror 7; A large concave mirror (6) for reflecting and condensing the light reflected by the convex mirror (7) and illuminating the conductive IC chip (1) is provided.
The convex mirror 7 is made translucent by a semi-permeable membrane.

As described above, the present apparatus is provided with a combination of the small convex mirror 7 and the large concave mirror 6, thereby converting the epi-illumination to ring-shaped illumination, and furthermore, converting the small convex mirror 7 into a translucent mirror, thereby reducing the epi-illumination. And ring lighting can be used together. Then, by appropriately changing the transmittance of the semi-permeable membrane of the small convex mirror 7, the incident illumination light from the vertical direction passing through the convex mirror 7,
It is possible to arbitrarily select the light amount ratio of the ring illumination light from the inclination direction reflected from the concave mirror 6. Further, the concave mirror 6 may be configured as a part of a spherical surface, but the entire hemisphere may be a concave mirror. Therefore, FIG. 9 and FIG.
There is no loss of light quantity as in the conventional example shown in FIG. Also,
Since the radius of curvature of the concave mirror 6 can be variously selected,
The distance between the lighting device and the chip 1 can be set arbitrarily. Therefore, as shown in FIG.
Can be set at any angle.

Furthermore, it is possible to obtain dark field illumination by masking a part of the concave mirror 6, and thereby it is possible to use both epi-illumination and dark field illumination.

In place of the illumination light source 10, a large number of LED elements are arranged inside the concave mirror 6,
The ED element and the diffusion plate may be used in combination to arrange the illuminating device. This also makes it possible to provide an illuminating device in which epi-illumination and ring-shaped illumination are provided side by side. In that case, the circular opening formed in the concave mirror 6 at the portion between the light source 10 and the convex mirror 7 becomes unnecessary. In this case, a large concave surface may be formed by simply arranging a large number of LED elements without using the concave mirror 6. This also basically enables the object of the present invention to be achieved.

Embodiment 2 FIG. 2 is a schematic view showing a lighting device according to a second embodiment of the present invention. In the figure, 21 is a sample surface observed by a microscope, 22 is a light source for emitting illumination light, and 23 is a light source 22.
24 for physically fixing the
Is a mount for fixing the holder 23 to the microscope main body 26 and further for mounting the microscope objective lens 25.

On the mount 24, a female-side objective mounting screw is formed at a position without eccentricity with respect to a male-side objective mounting screw 29 for mounting a microscope objective lens 25 as shown in FIG. By screwing up to the surface position 28, the screw microscope objective lens 25 can be fixed on the optical axis of the microscope with good reproducibility. The illumination optical axis of the light source 22 is arranged singly or plurally at a radial position from the focal position of the microscope objective lens 25, and is physically fixed to the surface of the holder 23. Further, the holder 23 is fixed or integrally formed with the mount 24, and the microscope objective lens 22 is fixed relatively to the microscope main body 26.

The outer diameter and pitch of the microscope objective lens mounting screw 29 are standardized.
The distance from the microscope objective lens mounting surface 28 to the microscope objective lens focal position 27 is defined as a constant distance as the parfocal length. The objective lens mounting surface 28 and the light source mounting reference surface are at the same level. Therefore, the positional relationship between the mounting position of the illumination device and the focal position of the objective lens is fixed, and the light source is arranged at a fixed position with respect to the focal position of the objective lens.

Further, by finishing the inner wall surface of the holder 23 as a diffuse reflection surface, the illumination light emitted from the light source 22 can be diffused and uniform illumination light can be obtained.

When a circular fluorescent tube is used as the light source 22, the holder 23 is composed of a plurality of hook-shaped hangers.

According to this, since the irradiation direction of the light source 22 is uniquely defined with respect to the objective mounting screw, it is not necessary to readjust the light source 22 by attaching and detaching the microscope objective lens 25. When attaching and detaching the microscope objective lens 25,
The use of standardized objective mounting screws eliminates the need for special tools and fixtures, and allows mounting to optical systems using the same standard objective mounting screws without being affected by the type of observation optical system. Compatible.

Embodiment 3 FIG. 4 is a schematic diagram showing a lighting device according to a third embodiment of the present invention. In the figure, 41 is a chip after wire bonding, which is an object to be inspected, 42 is an observation optical system, 43 is a convex mirror having a transparent parallel plane and having a side surface as a reflection surface, 4
4 is a parallel plane glass on which the convex mirror 43 is mounted, 45 is means for moving the parallel plane glass 44 along the optical axis of the observation optical system 42, 46 is a parabolic inner mirror, 47 is an imaging means,
48 is a half mirror, 49 is an illumination mode switching aperture, 50 is an illumination optical system, 51 is a light source, and 12 is an aperture stop located at a pupil position in the observation optical system.

The illumination optical system 50 and the observation optical system 42 form an optical system coupled via a half mirror 48, and a critical illumination optical system is formed for the optical positions of the object 41 and the light source 51. It is configured to: The illumination mode switching aperture 49 interposed between the illumination optical system 50 and the observation optical system 42 has a ring shape in order to make the illumination mode optimal for specifying the plane position of the ball and crescent after wire bonding. When the aperture is shaped, the ring illumination light enters the half mirror 48 along the optical axis, is reflected, passes through the observation optical system 42, and is collected in the direction of the test object 41 in a hollow conical state. .
Between the observation optical system 42 and the test object 41, a convex mirror 43 having the above-described transparent parallel plane having a side surface formed by a desired function curve and having a mirror surface is provided by the mirror-mounted parallel plane glass 4.
4 and the optical axis of the observation optical system 42 matches the center line of the convex mirror 43. Therefore, the ring illumination light in the hollow conical state that has passed through the above-described observation optical system 42 is reflected outside the optical axis by the mirror surface of the convex mirror 43, condensed on the ring in space, and then diffused while being parabolic. Inner mirror 46
Incident on.

The light reflected by the parabolic inner mirror 46 is moved from the dark field region on the test object 41 to the center with the optical axis of the observation optical system 42 without being vignetted by the side surface of the convex mirror 43. Light the area. Of the scattered light generated by various edges in the object 41 due to the dark-field illumination, the scattered light transmitted through the convex mirror 43 is condensed by the observation optical system 42, transmitted through the half mirror 48, and transmitted through the half mirror 48. It is incident on 47. Therefore, by setting the transmission area at the center of the convex mirror 43 to an appropriate size,
The depth of focus of the observation optical system 42 can be set as appropriate.

On the other hand, as shown in FIG. 5, the illumination mode switching aperture 49 is changed to a circular one and the mirror mounted parallel flat glass 44 is changed to a light type in order to make the illumination mode effective for wire loop shape inspection after wire bonding. In the case of moving toward the object 41 along the axis, the illumination light emitted from the illumination optical system 50 becomes circular when passing through the illumination mode switching aperture 49, passes through the same system as described above, and enters the observation optical system. After the light is emitted from the object 42, the light comes into a conical shape and enters the object 41 to be measured.

A characteristic difference from the above-mentioned illumination mode is that the illumination light is not parallel to the convex mirror 43 because the reflection surface of the convex mirror 43 is not adjusted to the position for reflecting a part of the conical illumination light. The point is that the light passes through the plane transparent part and enters the test object 41, and the reflected image is condensed by the observation optical system 42 as it is and transmitted to the imaging means 47. In this case, since the entire luminous flux passing through the observation optical system 42 is used, the numerical aperture is qualitatively increased as compared with the case of using the ring-shaped dark field illumination light, and the depth of focus is reduced by that amount. Is well known. In this state, the wire shape can be recognized by quantitatively moving and measuring the test object 41 up and down.

In this embodiment, since the light source 51 is whitened, the half mirror 48 is used. However, as shown in FIG. 7, a He-Ne laser 71 or the like is used as a light source to improve image illuminance. Instead of the mirror 48, it is necessary to use a beam splitter 72 adapted to the wavelength of the light source, and to set a λ / 4 plate 73 in the observation optical system or to change the material of the parallel plane glass 44 to a λ / 4 plate. There is.

Further, as shown in FIG. 6, when the convex mirror 43 is replaced with a convex mirror 61 having a diffuse reflection surface on the side, the dark field illumination light reflected by the parabolic inner mirror 46 enters a wider area. This is effective for obtaining illumination light having uniform illuminance and no unevenness.

[0038]

As described above, according to the present invention, 1
One illumination device can implement an epi-illumination and a ring-shaped illumination in combination, an epi-illumination and a dark-field illumination can be implemented in combination, and the illumination distance to an IC chip or the like by changing the radius of curvature of the concave mirror. Can be set arbitrarily. As a result, the measuring TV camera can be set at an obliquely upward angle. FIG.
There is no need to provide an opening for inserting a TV camera in a part of the illumination system as shown in FIG. 0, and the amount of illumination light source can be supplied to the chip without loss. Further, by using a semi-transparent mirror as the convex mirror, the ratio between the intensity of the incident illumination light and the intensity of the ring-shaped illumination light can be set arbitrarily, and a more accurate bonding wire inspection can be performed. Further, there is an effect that, by being incorporated in a bonding wire inspection device or the like, inspection and determination can be performed with an appropriate illumination form in a state where the object to be inspected is set at the observation position.

Further, the irradiation direction of the light source is uniquely defined with respect to the microscope objective mounting portion, so that it is not necessary to readjust the light source when attaching or detaching the objective lens. In addition, the use of standardized mounting screws eliminates the need for special tools and fixtures when attaching and detaching, and is not affected by the type of observation optical system. There is an effect that it has mounting compatibility.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a lighting device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a lighting device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining characteristics of a microscope objective lens used in the apparatus of FIG. 2;

FIG. 4 is a schematic diagram showing a lighting device according to a third embodiment of the present invention.

FIG. 5 is a schematic diagram showing the device of FIG. 4 in another illumination mode.

FIG. 6 is a schematic diagram showing a case where a convex mirror whose side surface is a diffuse reflection surface is used in the apparatus of FIG. 4;

FIG. 7 is a schematic diagram showing a case where laser light is used as a light source in the apparatus of FIG.

FIG. 8 is a schematic diagram showing a configuration of an oblique illumination device according to a conventional example.

FIG. 9 is an explanatory diagram illustrating an illumination method according to a conventional example.

FIG. 10 is an explanatory diagram illustrating another illumination method according to a conventional example.

[Explanation of symbols]

1, 41: chip, 95: inner lead, 94: bonding wire, 99: camera, 6: large concave mirror,
7: small convex mirror, 10: light source, 21: sample surface, 22:
Light source, 23: holder, 24: mount, 25: microscope objective lens, 26: microscope main body, 27: microscope objective lens focal position, 28: microscope objective lens mounting surface, 29: microscope objective lens mounting screw, 90: oblique illumination device , 42: observation optical system, 43, 61: convex mirror, 45: moving means,
46: parabolic inner mirror, 47: imaging means, 48: half mirror, 49: illumination mode switching aperture, 50: illumination optical system, 51: light source.

Continuing on the front page (72) Inventor Masaki Kobayashi 53, Imaiue-cho, Nakahara-ku, Kawasaki-shi, Kanagawa Canon Inc. (72) Inventor Kazuo Iizuka 53-Imaiuecho, Nakahara-ku, Kawasaki-shi, Kanagawa Canon Inc.Kosugi (72) Inventor Shinbu Kawahara 53, Imaiue-cho, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Canon Inc. (72) Inventor Toshiaki Takahashi 53, Imaiue-cho, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Canon Inc. (56) References JP-A-56-168501 (JP, A) JP-A-57-101709 (JP, A) JP-A-59-6535 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) G01B 11/00-11/30 102 G01N 21/84-21/91 H01L 21/60 321 H01L 21/64-21/66

Claims (6)

(57) [Claims] And 1. A light source, a convex mirror for reflecting the illumination light from the light source is disposed between the light source and the object to be illuminated, this is with the object to be illuminated with respect to the convex mirror is arranged on the opposite side of the convex mirror reflected condenses the illumination light and a concave mirror for irradiating the illumination object, the convex mirror is semitransparent mirror der
And arranged on a straight line connecting the light source and the illumination object.
A lighting device characterized by being placed . 2. A lighting and intermediate member microscope objective lens for observing the object to be illuminated is attached so that the fixed position relative to the microscope body, a fixedly mounted relative to the intermediate member and the object to be illuminated comprising a light source for, before
Serial objective lens is intended positional relationship between the intermediate member and the focal position of the objective lens when mounted to the intermediate member is configured to be constant, and a light source
A lighting device, wherein the positional relationship with the intermediate member is constant. Wherein the observation optical system and the convex mirror central portion disposed on a line connecting the object to be illuminated has a side to the reflective surface a transparent thereby observed from the outside to the optical axis of the observation optical system means for introducing illumination light to the convex mirror direction, is disposed between the observation optical system and the convex mirror
The illumination light is not vignetted on the side surfaces of the convex mirror.
A non-spherical mirror for reflecting the illumination light reflected by the convex mirror, and means for moving said convex mirror along the optical axis of the observation optical system, the sectional shape of the illumination light between the ring-shaped and circular and means for changing, which is dark-field illumination by irradiating the object to be illuminated with illumination light through the side surface and the aspherical Mi <br/> Ra of the convex mirror when the ring-shaped, circular lighting apparatus characterized by bright field illumination by irradiating the object to be illuminated by transmitting a central portion of the convex mirror when the. 4. A of claims 1 to 3, characterized in that the illumination light from the light source is focused at the focal position of the objective lens
The lighting device according to any one of the above. 5. A method according to claim illumination light from the light source is characterized in that uniformly illuminate the focal position of the objective lens 1
The lighting device according to any one of claims 1 to 3 . Wherein said illumination object balls of the IC element, crescent, and the like wires, their shapes, the claims 1-5, characterized in that used in the wire bonding inspecting apparatus for measuring the size and position The lighting device according to any one of the above.