JP3095855B2 - Light inspection device for visual inspection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light projecting device for inspecting the appearance on a substrate such as a wafer or a liquid crystal glass substrate.

[0002]

2. Description of the Related Art Conventionally, in order to inspect the appearance on a substrate,
For example, a light projecting device as shown in FIGS. 4 to 8 is used.

The light projecting device shown in FIG. 4 illuminates a diffused light emitted from a light source 2 onto a substrate, for example, a wafer 4, and scatters light from a foreign matter 6 such as dust and scratches on the surface of the wafer 4. An appearance inspection of the surface of the wafer 4 is performed based on a difference in intensity from light directly reflected from the surface of the wafer 4.

However, in such a light projecting device, since the scattered light and the directly reflected light simultaneously enter the observer's eyes 8 and are dazzling, it is difficult to determine the foreign matters 6 such as dust and scratches on the wafer surface. Problem. Therefore, in the apparatus shown in FIG. 5, the reflected light does not directly enter the eyes 8 of the observer.
A light shielding plate 10 is provided.

Further, the light projecting device shown in FIG. 6 is configured to illuminate the surface of the wafer 4 with a convergent light beam via a lens 12 to perform an appearance inspection. In addition, the light projecting device shown in FIG.
It is configured to perform an appearance inspection by illuminating the surface of the device.

Although the irradiation range of the light beam illuminated on the wafer surface via the light projecting devices of FIGS. 6 and 7 is relatively narrow,
Since it is possible to irradiate with strong light and the observer's eyes 8 can be brought close to the observation optical axis, it is easy to observe the scattered light from the foreign matter 6 such as dust and scratches. Further, as shown in FIG. 8, a method of illuminating the entire wafer surface using a plurality of optical fibers 16 is also known.

[0007]

However, in the apparatus shown in FIG. 5, the observing field of view is blocked by the light-shielding plate 10, and in order to observe the entire wafer 4, the light-shielding plate 10 is moved or the wafer is moved. The angle between the light source 4 and the light source 2 needs to be changed, and a complicated operation is required.

Further, the apparatus shown in FIGS. 6 and 7 cannot illuminate the entire wafer without unevenness. Therefore, when inspecting the appearance of a large wafer, a plurality of such apparatuses are required, and the cost is reduced. There is also a problem that it is disadvantageous. In addition, the apparatus shown in FIG. 8 has a problem that it is difficult to determine the foreign matter 6 such as dust and scratches on the wafer surface because the light is a collection of scattered light.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a simple and inexpensive configuration which can illuminate the entire large substrate without unevenness, and has a high foreign matter detection capability on the substrate. Another object of the present invention is to provide a light emitting device for visual inspection that can efficiently perform visual inspection of a substrate.

[0010]

In order to achieve the above object, a light emitting device for visual inspection according to the present invention is applied to a visual inspection device for irradiating the surface of a large-sized substrate to inspect for defects and the like. A light projecting device used, wherein a light source arranged so that a perpendicular to the surface of the large substrate and an illumination optical axis intersect, and an illumination optical axis arranged in an illumination optical path of the light source on the surface of the large substrate A reflecting means for deflecting the incident light at a predetermined incident angle, a light-collecting Fresnel lens disposed in an illumination optical path deflected by the light-reflecting means to restrict incident light to a parallel light beam, and The light-guided flat
A light emitting Fresnel lens that regulates the row light beam to a convergent light beam,
It is characterized by having.

[0011] In the above-described as configured light projection device for a visual inspection in accordance with the present invention, wherein the a is the light projecting Fresnel lens side, is guided through the Fresnel lens for projection Scattering means for imparting predetermined optical characteristics to the convergent light and uniformly irradiating the surface of the large-sized substrate can be provided , and the light-collecting Fresnel lens and the light-projecting lens can be provided.
It is possible to arrange the lens lens in close proximity,
The Fresnel lens for projection can be inserted into and removed from the illumination optical path.
The scattering means may be configured to
It can be configured to be insertable into and removable from the clear light path.
Angle of incidence of the reflection optical axis of the reflection means on the surface of the mold substrate
The reflected illumination light from the large substrate
Can be set at an angle that deviates from the
Come .

[0012]

In the light-emitting device for visual inspection according to the present invention, which is configured as described above, the illumination of the light source arranged so that the perpendicular to the surface of the large-sized substrate intersects the illumination optical axis. Reflecting means for deflecting the illumination optical axis at a predetermined incident angle with respect to the surface of the large substrate in the optical path is arranged, and a condensing Fresnel lens arranged in the illumination optical path deflected by the reflecting means is provided. The incident light is regulated to a parallel light flux , and the light is guided through the focusing Fresnel lens.
The collimated light beam converged by the Fresnel lens for projection
Since the light beam is regulated, a large-diameter illumination optical system can be configured at low cost and small size as the size of the substrate increases, and the surface of the large size substrate can be collectively illuminated and the appearance inspection can be performed efficiently. Further , by providing scattering means for providing predetermined optical characteristics to the convergent light guided through the light-emitting Fresnel lens on the side of the light-emitting Fresnel lens and uniformly irradiating the surface of the large-sized substrate, Illumination light having the above optical characteristics collectively illuminates the surface of a large-sized substrate, and a predetermined appearance inspection can be efficiently performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a light projecting device for visual inspection according to an embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the light projecting device for visual inspection according to the present embodiment includes a converging Fresnel lens 18 (5 mm thick) which is arranged in an illumination optical path and regulates incident light into a parallel light beam.
A light projecting Fresnel lens 20 (thickness: 5 mm) configured to be insertable into and removable from the parallel light flux guided through the light-collecting Fresnel lens 18 and to restrict the guided parallel light flux to a convergent light flux. The convergent light beam guided through the light projecting Fresnel lens 20 is configured to be able to be inserted into and removed from the convergent light beam, and the guided convergent light beam is given an optical characteristic to provide an observation sample, for example,
A scattering plate 24 for illuminating a large substrate 22 having a diagonal of 500 mm or more.

The condensing Fresnel lens 18, the light projecting Fresnel lens 20 and the scattering plate 24 have a larger diameter (about 500 to 600 mm) than the large substrate 22. For this reason, the large-sized substrate 22 is illuminated without unevenness over the whole.

The scattering plate 24 used in the apparatus of this embodiment is connected to a power supply 26 via a transparent electrode (not shown), and is capable of applying a voltage to a transmission type liquid crystal plate (hereinafter, this liquid crystal plate is referred to as a liquid crystal plate). (Indicated by reference numeral 24). In the light control liquid crystal sheet (not shown) applied to the transmission type liquid crystal plate 24, since the liquid crystal (not shown) is usually random in the droplet, the incident light is scattered at the interface or inside. Although it is in an opaque state, when a voltage is applied, the liquid crystal aligns in the direction of the electric field, does not scatter incident light, and has a function of changing to transparent.

As shown in FIGS. 1 to 3, a metal halide lamp (150 to 250 W) is applied to the light source 28 used in the light projecting device of this embodiment. In such a light source 28, the light emitting point is positioned at the first focal point of the elliptical rotating mirror 30, and the second focal point of the elliptical rotating mirror 30 is located at the gate 3 provided with the scattering plate.
It is configured to be 2. Further, the distance between the gate 32 and the light-collecting Fresnel lens 18 is equal to the focal length (f) of the light-collecting Fresnel lens 18.

Note that between the light source 28 and the gate 32,
A heat ray absorption filter 34 is provided. The scattering plate provided on the gate 32 has a size of 20 to 30 mm, and has a function of emitting uniform illumination light from the gate 32. Hereinafter, the operation of the light-emitting device for visual inspection according to the present embodiment having such a configuration will be described with reference to FIGS.

Illumination light emitted from the light source 28 passes through an elliptical rotating mirror 30, a heat ray absorbing filter 34, and a gate 32 to form a filter (green, yellow, polarizing plate, etc.) 36
Is transmitted to the mirror 38. The illumination light applied to the mirror 38 is reflected by the mirror 38, applied to the Fresnel lens 18 for condensing, and regulated to a parallel light flux.

In the apparatus shown in FIG. 1, since a convergent light beam is used as illumination light, a Fresnel lens 20 for projecting light and a transmissive liquid crystal plate 24 which is transparent when a voltage is applied are provided in the illumination light path. Has been inserted. For this reason, the convergent light beam from the light emitting Fresnel lens 20 passes through the transmissive liquid crystal plate 24 as it is and is illuminated without unevenness on the entire surface of the large-sized substrate 22.

The reflected illumination light reflected from the large substrate 22 is:
An image is formed at a position S near the eye 40 of the observer. At this time,
When a foreign substance 42 such as dust or a scratch is present on the surface of the large-sized substrate 22, scattered light is generated from the foreign substance 42, and no image is formed at the nearby position S. As a result, the observer can confirm the presence of the foreign matter 42 on the surface of the large-sized substrate 22 by visually observing the minute scattered light from outside the optical axis. Note that the near position S
It is also preferable to arrange a light shielding plate (not shown) so that light reflected directly from the surface of the substrate does not enter the eyes 40.

Such a convergent light beam is particularly suitable for inspecting disturbances or spots on a pattern printed on a substrate, dust or scratches on the substrate surface, and the illuminance on the surface of the large substrate 22 is extremely bright. Therefore, not only is it easy to confirm the foreign matter 42, but also because the light source image does not enter the eye 40, it does not become dazzling and does not hinder observation.

Next, when a surface light source is selected as the illumination light, as shown in FIG. 2, the voltage applied from the power supply 26 is cut off to make the transmission type liquid crystal plate 24 opaque.
The convergent light beam formed by passing through the light projecting Fresnel lens 20 becomes sharksten illumination light by the transmission type liquid crystal plate 24, and is illuminated uniformly on the entire surface of the large-sized substrate 22.

Such a surface light source is particularly suitable for inspecting unevenness in the thickness of a resist or the like on a substrate, pinholes on a transparent conductive film (ITO), dust under the film, and the like. And the interference pattern formed by the foreign substances 42 present on the substrate surface can be seen well.

In the light projecting device of the present embodiment, a transmission type liquid crystal plate 24 is applied as a scattering plate, and a convergent light beam or a surface light source can be appropriately selected only by applying or blocking a voltage to the transmission type liquid crystal plate 24. In addition, there is no need to insert and remove the scattering plate in the illumination light path, and the observation work efficiency can be improved.

When a parallel light beam is selected as the illumination light, as shown in FIG. 3, the Fresnel lens 20 and the transmissive liquid crystal plate 24 are prevented from being outside the illumination optical path, so that the condensing Fresnel lens 18 is used. Are illuminated on the large substrate 22 without unevenness.

Such a parallel light beam is particularly suitable for collective inspection of a large-sized substrate and inspection of dust and scratches on the surface of the substrate. Inspection efficiency can be improved.

As described above, the light projecting device for visual inspection according to the present embodiment employs the transmission type liquid crystal plate 24 as the scattering plate, and the voltage is applied while the transmission type liquid crystal plate 24 is arranged in the illumination optical path. , The desired convergent light flux or surface light source can be easily selected. As a result, the efficiency of the board appearance inspection work can be improved. Furthermore, since the light projecting device of the present embodiment is configured to illuminate the entire surface of the large substrate without unevenness, it is excellent in foreign substance detection capability over the entire surface of the substrate, and it is possible to efficiently inspect the appearance of the substrate. it can.

The present invention is not limited to the configuration of the embodiment described above.
It is needless to say that a desired convergent light flux or a surface light source can be appropriately selected by inserting and removing the 0 and the transmissive liquid crystal plate 24 into and from the illumination optical path.

Further, by disposing a glass plate on which a film-shaped polarizing film is formed as an analyzer at a position where the illumination light guided from the filter 36 in which the polarizing plate is inserted can be received, the polarization of the large-sized substrate 22 is improved. Observations can also be made. The polarized light observation can also be performed by the observer wearing glasses or the like provided with a polarizing plate and placing the eye 40 at the light source image position. Further, in the above-described embodiment, the visual inspection by the observer has been described, but the visual inspection of the substrate may be performed via the image processing apparatus.

[0031]

According to the appearance inspection light emitting device of the present invention,
A light projection device used for an appearance inspection device that irradiates a surface of a large substrate to inspect for defects and the like, and a light source arranged so that a perpendicular to the surface of the large substrate and an illumination optical axis intersect, and A reflecting means arranged in the illumination light path of the light source and deflecting the illumination optical axis at a predetermined incident angle with respect to the surface of the large-sized substrate; and an incident light arranged in the illumination light path deflected by the reflection means into a parallel light beam. A focusing Fresnel lens to regulate and before being guided through the focusing Fresnel lens
Fresnel lens for projection that restricts the parallel light beam to a convergent light beam
And, it is characterized by having . A result of this, the board
Large-diameter illumination optics can be made inexpensive and small due to the large size.
As a result, the surface of the large substrate can be illuminated at once without unevenness, so that the foreign matter detection capability of the large substrate is excellent and the appearance inspection of the large substrate can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of a light projecting device for appearance inspection according to one embodiment of the present invention, showing a state in which the entire surface of a substrate is observed using a convergent light beam.

FIG. 2 is a view showing a state in which the entire surface of the substrate is observed by a surface light source using the apparatus shown in FIG. 1;

FIG. 3 is a diagram showing a state in which the entire surface of the substrate is observed with a parallel light beam using the apparatus shown in FIG. 1;

FIG. 4 is a schematic view of a conventional light projecting device, showing a state in which a substrate surface is observed with diffused light.

FIG. 5 is a diagram showing a state in which a light-shielding plate is provided in the device shown in FIG. 4 to observe the substrate surface.

FIG. 6 is a schematic view of a conventional light projecting device, showing a state in which a substrate surface is observed with a convergent light beam.

FIG. 7 is a schematic view of a conventional light projecting device, showing a state in which a substrate surface is observed with a parallel light beam.

FIG. 8 is a schematic view of a conventional light projecting device, showing a state in which a substrate surface is observed using a plurality of optical fibers.

[Explanation of symbols]

18 Fresnel lens for condensing, 20 Fresnel lens for projecting light, 22 large substrate, 24 transmissive liquid crystal plate (scattering hand)
Stage), 28 ... light source, 36 ... filter (color filter,
Polarizer)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 21/84 G01N 21/956 H01L 21/66

Claims (6)

(57) [Claims] 1. A light projecting device used for a visual inspection device for irradiating a surface of a large substrate to inspect for defects or the like, wherein the illumination optical axis is arranged so that a perpendicular to the surface of the large substrate intersects. A light source, a reflecting means arranged in the illumination light path of the light source to deflect an illumination optical axis at a predetermined incident angle with respect to the surface of the large-sized substrate, and a light source arranged in the illumination light path deflected by the reflection means. A converging Fresnel lens that regulates light into a parallel light beam, and the parallel light guided through the converging Fresnel lens
A light projecting device for visual inspection, comprising: a light projecting Fresnel lens that regulates a light beam to a convergent light beam. 2. The light-projecting Fresnel lens side
The convergent light guided through the Fresnel lens for light
A dispersion which gives optical characteristics and uniformly irradiates the surface of the large substrate.
The light projection device for visual inspection according to claim 1, further comprising a disturbing means . 3. The light-collecting Fresnel lens and the light-projecting lens.
2. The light projecting device for visual inspection according to claim 1, wherein the Fresnel lenses are arranged close to each other. 4. A Fresnel lens the projection light, inspection light projecting device appearance according to claim 1, characterized in that the detachably configured with respect to the illumination optical path. 5. The illuminating device according to claim 1 , wherein
The light projection device for visual inspection according to claim 2, wherein the light projection device is configured to be insertable and removable . 6. The reflection hand on the surface of the large substrate.
The incident angle of the reflected optical axis of the step is adjusted by the reflected light from the large substrate.
The corner where bright light deviates from the observer's observation position or image processing device
The light projection device for visual inspection according to claim 1, wherein the light projection device is set to a degree .