JP7154985B2 - Laser light source device and inspection device - Google Patents

Description

The present invention relates to a laser light source device that emits laser light and an inspection device that includes the light source.

Laser light is excellent in monochromaticity and directivity, and when laser light is used as a light source, it can be used as a compact, high-output, and long-life light source means. Therefore, laser light sources are used in light sources of inspection apparatuses, digital mirror devices, and image display devices such as projection displays, etc., instead of lamp light sources.

In particular, when observing the front surface, back surface, or inside of a workpiece, the use of a laser light source makes it easier to obtain a high amount of light necessary for observation, etc., and the number of workpieces processed per unit time can be increased.

However, due to the high coherence (so-called coherence characteristics) of the laser light source, the reflected and scattered light interferes with each other on rough surfaces such as the workpiece surface and projection screen irradiated with the laser light, resulting in speckle noise. A characteristic interference noise (such as bright spots and dark spots, also simply called speckle) is included. Therefore, various methods have been proposed to reduce speckle caused by a laser light source (for example, Patent Documents 1 and 2).

JP 2016-133393 A JP 2010-224311 A JP 2011-107144 A

Optoscience, Products >> Laser speckle reducer, [online], [searched on January 30, 2018], Internet <URL: http://www.optoscience.com/maker/optotune/lineup/LSR/ LSR.html>

First,
As a specific example of speckle reduction, a form in which an optical element as shown in Non-Patent Document 1 is arranged in the optical path of a laser beam is known. However, the optical element disclosed in Non-Patent Document 1 generally has a structure in which a resin material is used as a base material. Therefore, if the power density of the laser light (that is, the energy intensity per unit area) is high, the resin material may be damaged and the life of the light source device may be shortened.

On the other hand, as disclosed in Patent Literatures 1 and 2, there is a problem that the speckle cannot be sufficiently reduced in the method of branching the laser light and recombining the laser light after changing the optical path length of each laser light. .

Therefore, there has been a demand for a laser light source device that uses a high-output laser, has a long life, and has little speckle noise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to provide a laser light source device that uses a high-output laser, has a long life and reduces speckle noise.

Second,
In the case of an inspection apparatus using a laser light source as disclosed in Patent Document 3, speckle noise is included in the laser light, making it difficult to determine whether it is minute foreign matter, voids, or noise. On the other hand, light sources other than lasers have weak coherence, making it difficult to detect minute voids.

Therefore, it is a second object of the present invention to provide an inspection apparatus equipped with a laser light source from which speckle noise is satisfactorily removed while using a laser light source with strong coherence.

As described above, in order to solve the first problem, one aspect of the present invention is
A laser light source device that emits laser light,
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a light beam synthesizing unit for synthesizing the first branched light beam and the second branched light beam,
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical paths of the first branched light beam and the second branched light beam ,
a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction orthogonal to the optical paths of the first branched light beam and the second branched light beam;
The diffusion plate moving mechanism includes a rotation mechanism that rotates the diffusion plate,
The first branched light beam and the second branched light beam are arranged so as to be irradiated at different distances from the center of rotation of the diffusion plate .
or
A laser light source device that emits laser light,
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a light beam synthesizing unit for synthesizing the first branched light beam and the second branched light beam,
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical paths of the first branched light beam and the second branched light beam,
a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction orthogonal to the optical paths of the first branched light beam and the second branched light beam;
The optical path of the first branched light flux and the second branched light flux is further provided with a diffusion plate facing the diffusion plate.
or
A laser light source device that emits laser light,
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a light beam synthesizing unit for synthesizing the first branched light beam and the second branched light beam,
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical paths of the first branched light beam and the second branched light beam,
a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction orthogonal to the optical paths of the first branched light beam and the second branched light beam;
The light beam synthesizing unit is characterized by comprising a branched light guide in which a large number of optical fibers are bundled.

On the other hand, in order to solve the second problem, one aspect of the present invention is
a laser light source device that emits laser light;
a holding part that holds the laminate;
an imaging device for capturing an image of light emitted from the laser light source device and passing through or reflected from an inspection area set in the laminate;
An inspection device comprising an inspection unit that inspects foreign matter and voids hidden in the interface of the laminate based on luminance information of an image captured by the imaging device ,
The laser light source device
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a light beam synthesizing unit for synthesizing the first branched light beam and the second branched light beam,
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical paths of the first branched light beam and the second branched light beam,
A diffusion plate moving mechanism is provided for relatively moving the diffusion plate in a direction orthogonal to the optical paths of the first branched light flux and the second branched light flux .

According to the above-described laser light source device for solving the first problem, speckle noise can be satisfactorily reduced with a long life while using a high-output laser.

According to the inspection apparatus for solving the second problem, the inspection is performed using a laser light source from which speckle noise has been satisfactorily removed, so minute foreign matters and voids can be detected.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows the whole structure of an example of the form which embodies this invention. It is a schematic diagram showing the whole composition of an example of another form embodying the present invention. It is a schematic diagram showing the whole composition of an example of another form embodying the present invention. It is a schematic diagram showing the whole composition of an example of another form embodying the present invention. It is the schematic which shows the whole structure of the modification of each form which embodies this invention. It is a schematic diagram showing the whole composition of an example of another mode embodying the present invention.

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, using a figure.

<First Aspect>
FIG. 1 is a schematic diagram showing the overall configuration of an example of a mode embodying the present invention. FIG. 1 shows a schematic diagram of a laser light source device 1 according to the present invention.

The laser light source device 1 includes a laser light source unit 2, a beam branching unit 3, a diffusion plate unit 4, a beam combining unit 5, and the like, and emits a laser beam Lm to the outside.

The laser light source unit 2 emits laser light. Specifically, the laser light source unit 2 includes a laser oscillator 20 and a beam adjusting unit 21 . The laser oscillator 20 is a light source that emits laser light, and can be exemplified by a semiconductor laser (also called a laser diode or LD), a solid-state laser, a gas laser, or the like. The beam adjustment unit 21 includes a collimating lens, a beam expander, and the like, and adjusts the laser beam emitted from the laser oscillator 20 to a desired beam L0 by collimating it or expanding it to a predetermined beam diameter. be.

The beam branching unit 3 branches the beam L0 emitted from the laser light source unit 2 into a first branched beam L1 and a second branched beam L2.
Specifically, the beam splitter 3 includes a beam splitter 31 and a mirror 32 . The optical path length of the second branched light flux L2 is set longer than the optical path length of the first branched light flux L1.

The beam splitter 31 internally splits the light entering from the incident surface (left side in the figure) and emits the light in two directions (right side and downward side in the figure). Specifically, the beam splitter 31 allows a portion (eg, 50%) of the incident light to pass through and reflects a portion (eg, 50%) of the incident light.

Specifically, the beam splitter 31 may be one that splits the light beam into two directions without changing the polarization direction, or an optical element called a polarization beam splitter (one that splits and emits vertically polarized laser light and horizontally polarized laser light respectively). ) can be exemplified. Alternatively, instead of the beam splitter 31, a half mirror may be arranged.
The mirror 32 reflects one of the beams emitted from the beam splitter 31 and changes the emission direction (from downward to right in the drawing).

More specifically, of the two light beams split by the beam splitter 31, the one that goes straight (to the right in the drawing) and is emitted is called a first branched light beam L1. ) is called a second split beam L2. The mirror 32 is arranged at an angle of 45 degrees with respect to the optical axis of the second branched beam L2 so that the second branched beam L2 is substantially parallel to the first branched beam L1.

The diffusion plate portion 4 is arranged in the optical path of the first split beam L1 and the second split beam L2, and diffuses the first split beam L1 and the second split beam L2 incident as parallel light (that is, converts them into scattered light). to do). Specifically, the diffusion plate section 4 includes diffusion plates 41 , 42 and 43 .

The diffusion plates 41 and 42 are arranged to face a first light receiving section 51 and a second light receiving section 52, which will be described later. Diffusion plate 43 is arranged to face diffusion plates 41 and 42 at such a position as to cross the optical paths of first split beam L1 and second split beam L2.

The diffuser plate 43 is attached to a rotating mechanism 45 and rotates around a rotation center Cr.
In the diffuser plate 43, the positions (that is, the radii r1 and r2) where the first branched beam L1 and the second branched beam L2 cross the optical paths with respect to the rotation center Cr of the diffuser plate 43 are set at different distances.

The beam combiner 5 combines the first split beam L1' and the second split beam L2'. Specifically, the beam synthesizing section 5 includes a first light receiving section 51, a second light receiving section 52, a fiber section 53, and an emission section 54, and is also called a branch light guide.

The first light receiving section 51 receives the first branched light flux L1′ that has passed through the polarizing plates 43 and 41 and diffused. The first light receiving section 51 includes a condensing lens 51a and a base section 51b.
The second light receiving section 52 receives the second branched light flux L2' that has passed through the polarizing plates 43 and 42 and diffused. The second light receiving section 52 includes a condensing lens 52a and a base section 52b.

The condensing lenses 51a and 52a converge the first branched light flux L1' and the second branched light flux L2' that have diffused through the diffusion plates 41, 42 and 43, and guide them to the caps 51b and 52b. Note that the light receiving areas of the base portion 51b of the first light receiving portion 51 and the base portion 52b of the second light receiving portion 52 are substantially equal to the effective areas of the diffused first split beam L1′ and the second split beam L2′. , the condensing lenses 51a and 52a may be omitted.

The fiber portion 53 synthesizes the light flux L<b>1 ′ received by the first light receiving section 51 and the light flux L<b>2 ′ received by the second light receiving section 52 and guides them to the emission section 54 . Specifically, the fiber portion 53 is formed by bundling a large number of optical fibers, and one end thereof is connected to the base portion 51b of the first light receiving portion 51 or the base portion 52b of the second light receiving portion 52. , and the opposite end thereof is connected to the output portion 54 .

The emitting section 54 emits the combined laser beam Lm. Note that the laser light Lm has a predetermined divergence angle.

Since the laser light source device 1 according to the present invention has such a configuration, a plurality of speckle patterns overlap to average the speckles and reduce the pattern contrast. Therefore, even a laser light source can emit laser light Lm with reduced speckles.

Further, since the light beam branching section 3 is provided and the diffusion plate section 4 is arranged in the optical path where the power density is low, damage to the diffusion plate section 4 can be reduced. Furthermore, since the beam branching unit 3 has different optical path lengths for the branched beams L1 and L2, the coherence of the laser beam Lm emitted from the emitting unit 54 can be lowered, and speckles can be reduced.

Further, in the diffuser plate section 4, the diffuser plates 41 and 42 are arranged opposite to the rotary diffuser plate 43, and the speckle reduction effect can be further enhanced by the plurality of diffuser plates. Further, since the diffuser plate 43 rotates, the same position is not irradiated with the laser beams L1 and L2, and the diffusion component (also referred to as the intensity distribution of the scattered light) always changes. Therefore, a large number of speckle patterns can be superimposed on each other per unit time of imaging or projection. Furthermore, the number of overlapping speckle patterns increases in combination with the number of branches of the light flux, and a synergistic effect of further reducing speckle is brought about.

On the other hand, the rotational movement of the diffusion plate 43 prevents the laser light from continuously irradiating the same spot, and convection caused by the rotation produces a cooling effect. . Furthermore, since the first split beam L1 and the second split beam L2 applied to the rotary diffusion plate 43 are applied to different positions from the rotation center Cr, damage to the diffusion plate 43 due to laser light is further reduced. can.

In other words, the laser light source device 1 according to the present invention can satisfactorily reduce speckle noise with a long life while using a high-output laser.

[Another form]
In the above description, a branched light guide in which a large number of optical fibers are bundled is exemplified as a specific form of the light beam synthesizing unit 5 according to the present invention. Such a configuration is preferable because the first light receiving portion 51 and the light received by the first light receiving portion 51 can be efficiently guided to the output portion 53, and the output portion 53 can be freely handled. However, in embodying the present invention, the present invention is not limited to the form provided with the beam synthesizing section 5 as described above, and another form may be employed.

[Another form]
In the above description, while exemplifying the specific form of the diffuser plate portion 4 according to the present invention, the excellent action and effect of the laser light source device 1 including the diffuser plate portion 4 have been described. However, in embodying the present invention, it is not limited to the form provided with the diffusion plate portion 4 as described above, and another form may be used.

2 to 4 are schematic diagrams showing the overall configuration of an example of another form embodying the present invention. 2 to 4 show schematic diagrams of laser light source devices 1B to 1D according to the present invention.

The laser light source devices 1B to 1D are provided with diffusion plate portions 4B to 4D having different configurations from the diffusion plate portion 4 described above. Since the other components are the same, detailed descriptions are omitted, and different parts are described.

In the above description, as a specific example of the diffusion plate section 4, a plurality of diffusion plates (specifically, the diffusion plates 41 and 42 and the diffusion plate 43) are provided in the optical paths of the first split beam L1 and the second split beam L2. The provided form is shown. With such a configuration, the diffusion effect is enhanced by the plurality of diffusion plates, and the speckle reduction effect can be enhanced when the diverged light beams are superimposed (that is, synthesized).

However, if a desired diffusion effect can be obtained with one diffuser plate, at least one diffuser plate 41 to 43 should be arranged in each of the optical paths of the first split beam L1 and the second split beam L2 (Fig. 2-4). By doing so, the light amount of the light beams L1' and L2' transmitted through the diffuser plate portion 4 increases, which is preferable.

In the above description, as a specific example of the diffusion plate portions 4 and 4B, the first branched beam L1 and the second branched beam L2 are applied to the rotary diffusion plate 43 at different positions from the rotation center Cr. Indicated. Such a form is preferable because the irradiation positions of the laser light do not overlap on concentric circles, and damage to the diffuser plate 43 is less likely to accumulate.

However, in embodying the present invention, the diffuser plate portions 4 and 4B are not limited to the form as described above, and the positions irradiated with the first branched beam L1 and the second branched beam L2 are shifted from the rotation center Cr. The same distance (that is, r1=r2) may be set (see FIGS. 1 and 2).

In the above description, as a specific example of the diffusion plate portions 4 and 4B, a configuration in which the rotary diffusion plate 43 is provided in the optical paths of the first split beam L1 and the second split beam L2 is shown. With such a configuration, the diffuser plate 43 rotates in a direction orthogonal to the optical paths of the first branched beam L1 and the second branched beam L2, so that the surrounding air convects and accumulates in the diffuser plate 43. This is preferable because heat can be radiated into the air.

However, the form in which the diffusion plate 43 is rotated by the rotation mechanism 45 is not essential for embodying the present invention, and may be as described below.
・Diffusion plate portion 4C: The diffusion plate 43 and/or the diffusion plate 41, 43 and/or the diffusion plate 41, 43, 41, 41, 41, 43, 43, 43, 43, 43, 43, 43, 43, 46, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, 46C, and 46C, 42 is reciprocated or pivoted (see FIG. 3).
Diffusion plate section 4D: Diffusion plate 43 and/or diffusion plates 41 and 42 are fixedly arranged (see FIG. 4).
- If necessary, normal temperature to low temperature air, nitrogen, or the like is blown (air blow) toward the diffusion plate 43 and/or the diffusion plates 41 and 42 (not shown).

[Modification]
In the above description, the configuration in which the beam splitter 3 includes the beam splitter 31 and the mirror 32 is exemplified. With such a configuration, there is little loss in the amount of light, and straightness of the laser light is maintained, so that it is easy to handle.

However, in embodying the present invention, the light beam splitter 3 is not limited to the form described above, and may be as described below.

FIG. 5 is a schematic diagram showing the overall configuration of a modification of each form embodying the present invention. FIG. 5 shows a schematic diagram of a laser light source device 1E according to the present invention.

The laser light source device 1E includes a beam branching section 3E having a configuration different from that of the beam branching section 3 described above. As for the other components, the diffuser plate portions 4, 4B to 4D and the light beam synthesizing portion 5 similar to those described above can be selected as appropriate, so detailed description will be omitted and different portions will be described.

The beam splitter 3E is composed of a branched light guide in which a large number of optical fibers are bundled, and the respective optical path lengths are set to different lengths. Specifically, the beam branching section 3E includes a light receiving section 35, a fiber section 36, a first light projecting section 37, and a second light projecting section .

The light receiving section 35 receives the light flux L0 emitted from the laser light source section 2 .
The fiber portion 36 distributes and guides the light received by the light receiving portion 35 to the first light projecting portion 37 and the second light projecting portion 38 . Specifically, the fiber portion 36 is a bundle of many optical fibers, one end of which is connected to the light receiving portion 35, and the opposite end of which is the first light projecting portion 37 or the second light emitting portion. It is connected to the light projecting section 38 . In the fiber portion 36, the distance from the light receiving portion 35 to the second light projecting portion 38 (that is, the optical path length) is set longer than the distance from the light receiving portion 35 to the first light projecting portion 37. .
The first light projecting section 37 emits a first branched beam L1.
The second light projecting section 38 emits a second branched beam L2.

[Modification]
In the above description, the laser light source devices 1, 1B to 1E have been exemplified, and the configuration for splitting the light flux L0 emitted from the laser oscillator 2 into two has been shown. However, in embodying the present invention, it is not limited to two branches, and may be branched into more than two. A configuration in which diffusion plates 4, 4B to 4D are arranged may be used.

<Second Aspect>
FIG. 6 is a schematic diagram showing the overall configuration of an example of another aspect embodying the present invention. FIG. 6 shows a schematic diagram of an inspection device K according to the invention.

The inspection device K inspects foreign matter and voids B hidden in the interface of the laminate W having optical transparency. Specifically, the inspection apparatus K includes the above-described laser light source device 1, holding section H, imaging device C, inspection section S, relative movement section M, control section CN, and the like. Here, as a specific example of the laminate W, a laminate of two silicon wafers is shown and detailed description will be given.

The laser light source device 1 emits laser light toward an inspection area set in the laminate W. As shown in FIG. Specifically, the laser light source device 1 irradiates a predetermined area including the inspection area F of the laminate W with illumination light Lf of a light amount necessary to generate the observation light Lv. More specifically, the laser light source device 1 uses the laser light source device 1 described above as the first mode, and uses the combined laser light Lm as the illumination light Lf. Incidentally, the laser light source device 1 can be exemplified by reflected illumination, transmitted illumination, etc., in addition to coaxial epi-illumination as shown. Further, as the illumination light Lf, infrared light including a wavelength of 1000 to 1100 nm, which is transmitted through the laminate W, can be exemplified.

Therefore, if foreign matter or voids B are lurking at the interface of the laminate W, the laser light may be blocked by the foreign matter or optical interference may occur in the voids. The intensity of light appears different between and without it (so-called background and surroundings).

The holding part H holds the laminate W. As shown in FIG. Specifically, the holding portion H is configured to grip the outer edge portion (also referred to as the outer peripheral edge) of the laminate W and hold it in a predetermined posture. More specifically, the holding part H includes a plurality of gripping members H1 (four locations are illustrated in FIG. 6) so as to surround the outer edge of the laminate W. The part that contacts the outer edge has a substantially Σ shape or a recessed shape like an arc. Further, the holding portion H includes an opening/closing mechanism (an actuator, a solenoid, etc., not shown) that moves the gripping members H1 outward/inward from the outer edge of the stack W. As shown in FIG. The opening/closing mechanism is attached to the holding table H2.

The imaging device C captures an image of light that has passed through the inspection area F or light that has been reflected by the inspection area F. FIG. Specifically, the imaging device C includes an imaging camera C1, a lens barrel C2, an objective lens C4, and the like.

The imaging camera C1 has an imaging device C3 and captures an image of an inspection area F set in the laminate W. As shown in FIG. Specifically, the imaging camera C1 converts light received by the imaging element C3 into an electric signal and outputs the electric signal to the outside as a video signal (analog signal) or image data (digital signal).

The lens barrel C2 fixes the imaging camera C1, the objective lens C2, and the emission section 54 of the laser light source device 1 in a predetermined arrangement. Specifically, the lens barrel C2 has a substantially T-shaped cylindrical frame, and the imaging camera C1, the objective lens C2, and the emission section 54 of the laser light source device 1 are attached to each end. A half mirror or the like is arranged in the lens barrel C2. Also, the lens barrel C2 is attached to the device frame Kf via a connecting member Kb.

The objective lens C4 forms an image of the inspection area F set on the stack W on the imaging device C3 of the imaging camera C1, and is arranged to face the stack W held by the holding unit H. ing. The objective lens C4 may have a configuration in which different magnifications are switched by a revolver mechanism, or may have a configuration including a zoom lens or a lens with a fixed magnification.

As described above, as a specific configuration of the imaging device C, the light Lm emitted from the emission part 54 of the laser light source device 1 is reflected by the half mirror in the lens barrel C2, and passes through the objective lens C4 as the illumination light Lf. The light (i.e., observation light) Lv that is irradiated toward W and reflected by the inspection area F is taken in from the objective lens C4, passes through the half mirror, and is incident on the imaging camera C1 (so-called coaxial oblique method). ) can be exemplified.

The inspection unit S inspects foreign substances and voids B hidden in the interface of the laminate W based on the luminance information of the image captured by the imaging device C. FIG. Specifically, the inspection unit S includes an image processing unit, a determination unit, etc., processes an image obtained by imaging the inspection region F, and based on the luminance information of the image, a background image (an image indicating a normal site) is displayed. In addition, it is configured to determine whether or not there is a portion showing the characteristics of the foreign matter or void B, record the location, number, size, etc. of the foreign matter or void B, or output it to the outside. More specifically, the inspection unit S is composed of a computer, an image processing device, etc. (that is, hardware) and its execution program, etc. (that is, software).

The relative movement part M moves the holding part H and the imaging device C relative to each other. Specifically, the relative movement part M relatively moves the holding part H and the imaging device C in directions parallel to the surface of the laminate W (referred to as X direction/Y direction). More specifically, the relative movement section M includes an X-axis stage M1, a Y-axis stage M2, and a rotation mechanism M3.

The X-axis stage M1 is attached to the device frame Kf and has a rail extending in the X direction and a movable portion that moves/stands still on the rail.

The Y-axis stage M2 is attached to the movable portion of the X-axis stage M1, and includes a rail extending in the Y direction and a movable portion that moves/stands still on the rail.

The rotating mechanism M3 is attached to the movable portion of the Y-axis stage M2, and includes a rotating portion that rotates/stands still about the Z-axis orthogonal to the XY plane. The holding portion H is attached to the rotating portion of the rotating mechanism M3.

The movable parts of the X-axis stage M1 and the Y-axis stage M2 are controlled to move/stop/position based on a control signal from the controller CN by a linear motor, a rotary motor, a ball screw, or the like. Further, the rotating part of the rotating mechanism M3 is controlled to rotate/standstill/change the angle based on a control signal from the control part CN by a DD motor, a rotating motor, gears, or the like.

The control unit CN controls each device of the inspection apparatus K. FIG. Specifically, based on pre-registered procedure data (so-called inspection recipe), the control unit CN controls the relative movement unit M, outputs a trigger signal for starting imaging to the imaging camera C1 of the imaging device C, It performs signal output for opening/closing operation to the opening/closing mechanism of the holding part H, signal output for causing the laser oscillator of the laser light source device 1 to emit laser light, switching control of the revolver mechanism of the imaging device C, and the like. be. More specifically, the control unit CN is composed of a programmable logic controller, a computer, etc. (that is, hardware) and its execution program, etc. (that is, software).

With such a configuration, the inspection apparatus K captures an image with the imaging device C while sequentially changing the position of the inspection area F of the laminate W, processes the image of each inspection area F, and processes the image of the laminate W. It is possible to inspect foreign substances and voids hidden in the interface between

At this time, since the illumination light Lf emitted toward the laminate W uses the laser light emitted from the laser light source device 1 according to the present invention, the speckle noise is satisfactorily removed. Therefore, it is possible to detect minute foreign matter and voids by utilizing the strong coherence of laser light.

Note that the inspection apparatus K according to the present invention may be configured to include the laser light source devices 1B to 1E described above instead of the laser light source device 1 described above. Speckle noise can be satisfactorily removed using any of the laser light source devices 1, 1B to 1E.

In the above description, as a specific configuration of the imaging device C that captures the light reflected by the inspection area F, the coaxial epi-oblique system was exemplified, but an oblique illumination system or the like may be used. Alternatively, the imaging device C is not limited to the configuration for imaging the light reflected by the inspection area F, and may be configured for imaging the light that has passed through the inspection area F (so-called transmissive illumination method). In the case of the transmissive illumination method, the emitting part 54 such as the laser light source device 1 is incorporated in the holding part H, the inspection area F is irradiated with the laser light Lf directly or via a mirror, and the light passing through the inspection area F (that is, the observation Light) Lv may be imaged by the imaging device C. FIG.

In the above description, the inspection apparatus K is exemplified with a configuration including the relative movement unit M. If there is no need to move H and imaging device C relative to each other, a configuration in which relative movement unit M is omitted may be used. Further, even when the relative movement portion M is provided, the rotating mechanism 3 may be omitted if there is no need to align the direction of the laminate W or if the holding portion H can be substituted. Further, if one of the XY directions is sufficient for relative movement, one of the X-axis stage M1 and the Y-axis stage M2 may be omitted. Further, the relative moving unit M is not limited to a configuration in which the holding unit H side is moved/rotated in the XYθ direction, and may be configured to move/rotate the imaging device C in the XYθ direction, or a partially combined configuration. can be

In the above description, the laminated body W is formed by bonding together silicon wafers, and the wavelength of the illumination light Lf irradiated using the laser light Lm emitted from the laser light source device 1 is infrared light including 1000 to 1100 nm. A form that is light is exemplified. A silicon wafer does not transmit visible light having a wavelength shorter than 900 nm, and the transmittance gradually increases from a wavelength of 900 nm or longer. Infrared light having a wavelength of approximately 1000 nm or more provides a sufficient amount of light for observing the inside (interface) of the silicon wafer. On the other hand, when the wavelength is longer than 1100 nm, the sensitivity characteristic is lowered when the imaging device C3 of the imaging camera C1 is a CCD or CMOS. Further, if the imaging element C3 of the imaging camera C1 uses a compound such as InGaAs, the sensitivity at the wavelength is high, but the operating speed (imaging rate) is slow. Therefore, if the laminated body W is a laminate of silicon wafers, it is preferable that the wavelength of the illumination light L1 emitted from the laser light source device 1 is infrared light including 1000 to 1100 nm.

However, in embodying the present invention, the illumination light Lf irradiated toward the laminate W may be light of a wavelength other than this, and the wavelength characteristics of the laminate W to be inspected (light transmittance, etc.) ) or the light-receiving sensitivity characteristics of the image sensor C3.

REFERENCE SIGNS LIST 1 laser light source device 2 laser light source unit 3 beam branching unit 4 diffusion plate unit 5 beam combining unit 20 laser oscillator 21 collimating lens 31 beam splitter 32 mirror 41 diffusion plate (fixed type)
42 Diffusion plate (fixed type)
43 Diffusion plate (rotary type)
45 rotation mechanism 46a-c vibration mechanism 51 first light receiving section (first branched light flux)
52 second light receiving portion (second branched beam)
53 fiber section (bundle of optical fibers)
54 output part (combined luminous flux)
Luminous flux (laser light) emitted from L0 laser light source
L1 First branched light flux (before passing through the polarizing plate)
L2 Second branched light flux (before passing through the polarizing plate)
L1' first branched light flux (after passing through the polarizing plate)
L2' second branched beam (after passing through the polarizing plate)
Lm Combined and emitted luminous flux Cr Center of rotation r1 Radius (first branched luminous flux)
r2 radius (second split beam)
K Inspection device W Laminated body B Foreign matter or void H Holding unit C Imaging unit S Inspection unit F Inspection area Lf Illumination light Lv Observation light

Claims (9)

A laser light source device that emits laser light,
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a beam synthesizing unit for synthesizing the first branched beam and the second branched beam;
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical path of the first branched light beam and the second branched light beam ,
a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction perpendicular to the optical paths of the first branched light beam and the second branched light beam;
The diffusion plate moving mechanism includes a rotation mechanism that rotates the diffusion plate,
The first branched light flux and the second branched light flux are arranged so as to be irradiated at different distances from the center of rotation of the diffusion plate.
A laser light source device characterized by: 2. The laser light source device according to claim 1 , further comprising a diffusing plate arranged opposite to said diffusing plate in the optical paths of said first branched beam and said second branched beam. 3. The laser light source device according to claim 1, wherein said beam synthesizing section comprises a branched light guide in which a large number of optical fibers are bundled. a laser light source device according to any one of claims 1 to 3 ;
a holding part that holds the laminate;
an imaging device for capturing an image of light emitted from the laser light source device and passing through or reflected from an inspection area set in the laminate;
and an inspection unit that inspects foreign matter and voids hidden in the interface of the laminate based on luminance information of an image captured by the imaging device. A laser light source device that emits laser light,
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a beam synthesizing unit for synthesizing the first branched beam and the second branched beam;
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical path of the first branched light beam and the second branched light beam,
a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction perpendicular to the optical paths of the first branched light beam and the second branched light beam;
A laser light source device, further comprising a diffuser plate arranged opposite to the diffuser plate in the optical paths of the first branched beam and the second branched beam. A laser light source device that emits laser light,
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a beam synthesizing unit for synthesizing the first branched beam and the second branched beam;
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical path of the first branched light beam and the second branched light beam,
a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction perpendicular to the optical paths of the first branched light beam and the second branched light beam;
A laser light source device, wherein the light beam synthesizing unit comprises a branched light guide in which a large number of optical fibers are bundled. 7. The laser light source device according to claim 5 , wherein said diffusion plate moving mechanism comprises a rotation mechanism for rotating said diffusion plate. a laser light source device that emits laser light;
a holding part that holds the laminate;
an imaging device for capturing an image of light emitted from the laser light source device and passing through or reflected from an inspection area set in the laminate;
An inspection device comprising an inspection unit that inspects foreign matter and voids hidden in the interface of the laminate based on luminance information of an image captured by the imaging device ,
The laser light source device
a beam splitter that splits a beam emitted from the laser light source into a first split beam and a second split beam;
a beam synthesizing unit for synthesizing the first branched beam and the second branched beam;
The optical path length of the second branched light flux is set longer than the optical path length of the first branched light flux,
A diffusion plate is provided in the optical path of the first branched light beam and the second branched light beam,
a diffusion plate moving mechanism for relatively moving the diffusion plate in a direction perpendicular to the optical paths of the first branched light flux and the second branched light flux
An inspection device characterized by: The diffusion plate moving mechanism includes a rotation mechanism that rotates the diffusion plate.
The inspection apparatus according to claim 8, characterized by:

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