JP2019138896A - Laser light source device and inspection apparatus - Google Patents

Abstract

To provide a laser light source device that accomplishes a reduction in speckle noise with a long service life while using high-power laser.SOLUTION: A laser light source device emitting a laser beam comprises: a luminous flux branching part that branches a luminous flux emitted from the laser light source into a first branched luminous flux and a second branched luminous flux; and a luminous flux synthesizing part that synthesizes the first branched luminous flux and the second branched luminous flux. A length of an optical path of the second branched luminous flux is set to be longer than a length of an optical path of the first branched luminous flux, and diffusion plates are provided on the optical paths of the first branched luminous flux and the second branched luminous flux.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser light source device that emits laser light and an inspection device including 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 light source means of small size, high output, and long life. Therefore, the laser light source is used for a light source of an inspection apparatus, a video display device such as a digital mirror device, a projection display, or the like instead of the lamp light source.

  In particular, in the form of observing the front surface, back surface, and the inside of the workpiece, it is easy to obtain a high light amount necessary for observation or the like by using a laser light source, and the number of processed sheets per unit time can be increased.

  However, due to the high coherence (so-called coherence characteristics) of the laser light source, the reflected or scattered light interferes with each other on the rough surface such as the work surface or projection screen irradiated with the laser light, and speckle noise. It contains unique interference noises (such as bright spots and dark spots, also simply speckles). For this reason, various methods for reducing speckles caused by a laser light source have been proposed (for example, Patent Documents 1 and 2).

JP 2006-133393 A JP 2010-224311 A JP 2011-107144 A

Opt-Science, Products >> Laser Speckle Reducer, [online], [Search January 30, 2018], Internet <URL: http://www.optoscience.com/maker/optotune/lineup/LSR/ LSR.html>

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

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

  Therefore, realization of a laser light source device that uses a high-power laser and has a long lifetime and low speckle noise has been demanded.

  Accordingly, the present invention has been made in view of the above problems, and has as its first object to provide a laser light source device that uses a high-power laser and has a long lifetime and reduced 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, and it is difficult to determine whether it is a minute foreign object, void, or noise. On the other hand, light sources other than lasers have weak coherence, and it has been difficult to detect minute voids.

  Accordingly, a second object of the present invention is to provide an inspection apparatus provided with a laser light source from which speckle noise is satisfactorily removed while using a highly coherent laser light source.

As described above, in order to solve the first problem, one aspect of the present invention is as follows.
A laser light source device for emitting laser light,
A light beam branching section for branching the light beam emitted from the laser light source into a first branched light beam and a second branched light beam;
A light beam combining unit that combines the first branched light beam and the second branched light beam,
The optical path length of the second branched light beam is set to be longer than the optical path length of the first branched light beam,
A diffusion plate is provided in the optical path of the first branched light beam and the second branched light beam.

On the other hand, in order to solve the second problem, one aspect of the present invention is:
A laser light source device according to any one of claims 1 to 6;
A holding unit for holding the laminate;
An imaging device for imaging light emitted from the laser light source device and passing or reflected through the inspection region set in the laminate;
The inspection apparatus includes 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 apparatus.

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

  According to the inspection apparatus for solving the second problem, since inspection is performed using a laser light source from which speckle noise is well removed, it is possible to detect minute foreign matters and voids.

It is the schematic which shows the whole structure of an example of the form which embodies this invention. It is the schematic which shows the whole structure of an example of another form which embodies this invention. It is the schematic which shows the whole structure of an example of another form which embodies this invention. It is the schematic which shows the whole structure of an example of another form which embodies this invention. It is the schematic which shows the whole structure of the modification of each form which embodies this invention. It is the schematic which shows the whole structure of an example of another aspect which embodies this invention.

  Hereinafter, modes for carrying out the present invention will be described with reference to the drawings.

<First aspect>
FIG. 1 is a schematic diagram showing an overall configuration of an example of a form embodying the present invention. FIG. 1 shows a schematic view 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 light beam branching unit 3, a diffuser plate unit 4, a light beam combining unit 5, and the like, and emits laser light 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 adjustment unit 21. The laser oscillator 20 is a light source that emits laser light, and examples thereof include a semiconductor laser (also called a laser diode or LD), a solid-state laser, and a gas laser. The beam adjusting unit 21 includes a collimating lens, a beam expander, and the like, and adjusts the laser light emitted from the laser oscillator 20 to a desired light flux L0 by making the laser light parallel or expanding to a predetermined beam diameter. is there.

The beam splitter 3 branches the beam L0 emitted from the laser light source unit 2 into a first branch beam L1 and a second branch 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 beam L2 is set longer than the optical path length of the first branched light beam L1.

  The beam splitter 31 divides the light that has entered from the incident surface (left side in the figure) inside and emits the light in two directions (right side and lower side in the figure). Specifically, the beam splitter 31 transmits a part (for example, 50%) of incident light and reflects a part (for example, 50%).

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

  More specifically, of the two light beams branched by the beam splitter 31, the one that travels straight (to the right in the drawing) and is emitted is called the first branched light beam L 1, and the angle is changed (downward in the drawing). ) The outgoing light is called a second branched light beam L2. The mirror 32 is disposed so as to be inclined by 45 degrees with respect to the optical axis of the second branched light beam L2 so that the second branched light beam L2 is substantially parallel to the first branched light beam L1.

  The diffusing plate portion 4 is disposed in the optical path of the first branched light beam L1 and the second branched light beam L2, and diffuses the first branched light beam L1 and the second branched light beam L2 incident as parallel light (that is, converted into scattered light). To do). Specifically, the diffusing plate portion 4 includes diffusing plates 41, 42, and 43.

  The diffusion plates 41 and 42 are arranged to face a first light receiving unit 51 and a second light receiving unit 52 which will be described later. The diffusing plate 43 is disposed so as to face the diffusing plates 41 and 42 at a position crossing the optical paths of the first branched light beam L1 and the second branched light beam L2.

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

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

The first light receiving unit 51 receives the first branched light beam L1 ′ diffused through the polarizing plates 43 and 41. The first light receiving part 51 includes a condenser lens 51a and a base part 51b.
The second light receiving unit 52 receives the second branched light beam L2 ′ diffused through the polarizing plates 43 and 42. The second light receiving part 52 includes a condenser lens 52a and a base part 52b.

  The condensing lenses 51a and 52a condense the first branched light beam L1 'and the second branched light beam L2' diffused through the diffusion plates 41, 42, and 43, and guide them to the base portions 51b and 52b. Note that the light receiving areas of the base part 51b of the first light receiving part 51 and the base part 52b of the second light receiving part 52 are substantially equal to the effective areas of the diffused first branched light flux L1 ′ and second branched light flux L2 ′. The condensing lenses 51a and 52a may be omitted as long as they are equal to or larger than.

  The fiber unit 53 combines the light beam L <b> 1 ′ received by the first light receiving unit 51 and the light beam L <b> 2 ′ received by the second light receiving unit 52 and guides them to the emission unit 54. Specifically, the fiber part 53 is a bundle of many optical fibers, and one end part is connected to the base part 51b of the first light receiving part 51 or the base part 52b of the second light receiving part 52. The opposite end is connected to the emitting portion 54.

  The emission unit 54 emits the combined laser beam Lm. The laser beam Lm has a predetermined divergence angle.

  Since the laser light source device 1 according to the present invention has such a configuration, when a plurality of speckle patterns overlap, the speckles are averaged, and the contrast of the pattern is lowered. Therefore, even a laser light source can be emitted as laser light Lm with reduced speckles.

  And since the diffusion plate part 4 is arrange | positioned in the optical path with which the light beam branch part 3 was provided and the power density became low, the damage to the diffusion plate part 4 can be reduced. Furthermore, since the optical path lengths of the branched light beams L1 and L2 are different in the light beam branching unit 3, the coherence of the laser light Lm emitted from the emitting unit 54 can be lowered and speckle can be reduced.

  Further, in the diffusing plate portion 4, the diffusing plates 41 and 42 are arranged to face the rotary diffusing plate 43, and the speckle reduction effect can be further enhanced by the plurality of diffusing plates. Further, the rotational movement of the diffusion plate 43 does not irradiate the same position with the laser beams L1 and L2, and the diffusion component (also referred to as the intensity distribution of scattered light) always changes. Therefore, a large number of speckle patterns can be overlapped per unit time that is imaged or projected. Further, the overlapping of the speckle patterns is increased in combination with the number of branches of the light flux, and a synergistic effect for further reducing the speckles is brought about.

  On the other hand, the rotational movement of the diffusion plate 43 is not continuously irradiated with the laser beam, and a cooling effect is generated by the convection due to the rotation. Together, these can further reduce damage to the diffusion plate 43 by the laser beam. . Further, since the first branched light beam L1 and the second branched light beam L2 irradiated to the rotary diffusion plate 43 are irradiated to different positions from the rotation center Cr, damage to the diffusion plate 43 due to laser light is further reduced. it can.

  That is, the laser light source device 1 according to the present invention can reduce speckle noise satisfactorily with a long life while using a high-power laser.

[Another form]
In the above description, a branched light guide in which a large number of optical fibers are bundled is illustrated as a specific form of the light beam combining unit 5 according to the present invention. Such a configuration is preferable because the light received by the first light receiving unit 51 and the first light receiving unit 51 can be efficiently guided to the emitting unit 53 and the emitting unit 53 can be freely handled. However, when the present invention is embodied, the present invention is not limited to the form including the light beam combining unit 5 as described above, and another form may be used.

[Another form]
In addition, in the above, the outstanding effect | action and effect of the laser light source device 1 provided with it were described, demonstrating the specific form of the diffusion plate part 4 which concerns on this invention. However, in embodying the present invention, the present invention is not limited to the form including the diffusing plate portion 4 as described above, and may be another form.

  2-4 is the schematic which shows the whole structure of an example of another form which embodies this invention. 2 to 4 show schematic views of the laser light source devices 1B to 1D according to the present invention.

  The laser light source devices 1B to 1D include diffusion plate portions 4B to 4D having a configuration different from that of the diffusion plate portion 4 described above. Since other components are the same, detailed description is omitted, and different parts will be described.

  In the above description, as a specific example of the diffusion plate portion 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 branched light beam L1 and the second branched light beam L2. The provided form was shown. With such a configuration, the diffusion effect is enhanced by the plurality of diffusion plates, and the speckle reduction effect when the branched light beams are superimposed (that is, synthesized) can be enhanced.

  However, when a desired diffusion effect can be obtained with one diffusion plate, it is sufficient that at least one diffusion plate 41 to 43 is disposed in each of the optical paths of the first branched light beam L1 and the second branched light beam L2 (FIG. 2-4). By doing so, the amount of light beams L1 'and L2' transmitted through the diffusing plate portion 4 is increased, which is preferable.

  In the above description, as a specific example of the diffusing plate portions 4 and 4B, a mode in which the first branched light beam L1 and the second branched light beam L2 are irradiated to different positions from the rotation center Cr with respect to the rotary diffusion plate 43, respectively. Indicated. Such a configuration is preferable because the irradiation position of the laser beam does not overlap on the concentric circle and damage to the diffusion plate 43 is difficult to accumulate.

  However, in realizing the present invention, the diffusing plate portions 4 and 4B are not limited to the above-described form, and the positions where the first branched light beam L1 and the second branched light beam L2 are irradiated 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 diffusing plate portions 4 and 4B, a form in which the rotary diffusing plate 43 is provided in the optical paths of the first branched light beam L1 and the second branched light beam L2 is shown. In such a form, the diffuser plate 43 rotates and moves in a direction orthogonal to the optical paths of the first branched light beam L1 and the second branched light beam L2, so that the surrounding air is convected and accumulated in the diffuser plate 43. It is preferable because heat can be dissipated in the air.

However, the form in which the diffusion plate 43 is rotated by the rotation mechanism 45 is not essential for realizing the present invention, and may be as described below.
Diffusion plate portion 4C: Diffusion plate 43 and / or diffusion plate 41 by vibration mechanisms 46a to 46c or a swing mechanism that reciprocate in a direction orthogonal to the optical path (up / down direction or near / back direction in the figure) 42 is reciprocated or swiveled (see FIG. 3).
Diffusion plate part 4D: Diffusion plate 43 and / or diffusion plates 41 and 42 are fixedly arranged (see FIG. 4).
If necessary, air or nitrogen at normal or low temperature 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 light beam branching unit 3 is exemplified by the configuration including the beam splitter 31 and the mirror 32. Such a configuration is easy to handle because there is little loss of light quantity and the laser beam is kept straight.

  However, when the present invention is embodied, the present invention is not limited to the light beam branching section 3 having the above-described form, and may be as described below.

  FIG. 5 is a schematic diagram showing the overall configuration of a modification of each embodiment 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 light beam branching unit 3E having a configuration different from that of the light beam branching unit 3 described above. In addition, since the other diffusing plate sections 4 and 4B to 4D and the light beam combining section 5 can be appropriately selected as other constituent elements, detailed description will be omitted, and different parts will be described.

  The light beam branching section 3E is constituted by a branching 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 splitting unit 3E includes a light receiving unit 35, a fiber unit 36, a first light projecting unit 37, and a second light projecting unit 38.

The light receiving unit 35 receives the light beam L0 emitted from the laser light source unit 2.
The fiber part 36 guides the light received by the light receiving part 35 while distributing it to the first light projecting part 37 and the second light projecting part 38. Specifically, the fiber portion 36 is a bundle of a large number of optical fibers, one end portion is connected to the light receiving portion 35, and the opposite end portion is the first light projecting portion 37 or the second light emitting portion 37. It is connected to the light projecting unit 38. Further, the distance from the light receiving unit 35 to the second light projecting unit 38 (that is, the optical path length) of the fiber unit 36 is set to be longer than the distance from the light receiving unit 35 to the first light projecting unit 37. .
The 1st light projection part 37 radiate | emits the branched 1st branched light beam L1.
The second light projecting unit 38 emits the branched second branched light beam L2.

[Modification]
In the above description, the laser light source devices 1, 1 </ b> B to 1 </ b> E are exemplified, and the configuration in which the light beam L <b> 0 emitted from the laser oscillator 2 is branched into two is shown. However, in embodying the present invention, it is not limited to two branches, and may be further branched, and the optical path lengths of the branched light beams are set to be different from each other in the optical paths of the branched light beams. The structure which arrange | positions the diffusion plates 4 and 4B-4D may be sufficient.

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

  The inspection device K inspects foreign matters and voids B hidden at the interface of the light transmissive laminate W. Specifically, the inspection device K includes the laser light source device 1, the holding unit H, the imaging device C, the inspection unit S, the relative movement unit M, the control unit CN, and the like described above. Here, as a specific example of the laminated body W, one in which two silicon wafers are bonded together is shown, and detailed description will be given.

  The laser light source device 1 emits laser light toward an inspection region set in the stacked body W. Specifically, the laser light source device 1 irradiates a predetermined area including the inspection area F of the stacked body W with illumination light Lf having a light quantity necessary for generating the observation light Lv. More specifically, the laser light source device 1 uses the above-described one as the first aspect, and uses the combined laser beam Lm of the luminous flux as the illumination light Lf. The laser light source device 1 can be exemplified by reflected illumination, transmitted illumination and the like in addition to the coaxial falling illumination as shown. In addition, examples of the illumination light Lf include infrared light including a wavelength of 1000 to 1100 nm that transmits the stacked body W.

  Therefore, if foreign matter or void B is lurking at the interface of the laminated body W, the laser beam is shielded by the foreign matter or optical interference occurs due to the void. The intensity of light appears differently (so-called background and surroundings).

  The holding part H holds the laminated body W. Specifically, the holding portion H is configured to hold an outer edge portion (also referred to as an outer peripheral edge) of the stacked body W and hold it in a predetermined posture. More specifically, the holding portion H includes a plurality of gripping members H1 (four examples are illustrated in FIG. 6) disposed so as to surround the outer edge of the multilayer body W. The part in contact with the outer edge has a substantially Σ shape or a shape recessed in an arc shape. Further, the holding portion H includes an opening / closing mechanism (an actuator, a solenoid, etc., not shown) that moves the gripping member H1 toward the outside / inside of the outer edge of the stacked body W. The opening / closing mechanism is attached to the holding base H2.

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

  The imaging camera C1 includes an imaging element C3 and captures an image of the inspection region F set on the stacked body W. Specifically, the imaging camera C1 converts the light received by the imaging device C3 into an electrical signal and outputs it as an image signal (analog signal) or image data (digital signal) to the outside.

  The lens barrel C2 fixes the imaging camera C1, the objective lens C2, and the emission unit 54 of the laser light source device 1 in a predetermined arrangement. Specifically, the lens barrel C2 includes a substantially T-shaped cylindrical frame, and the imaging camera C1, the objective lens C2, and the emission unit 54 of the laser light source device 1 are attached to each end. In addition, a half mirror or the like is disposed in the lens barrel C2. Further, the lens barrel C2 is attached to the apparatus frame Kf via a connecting member Kb.

  The objective lens C4 forms an image of the inspection region F set on the stacked body W on the image sensor C3 of the imaging camera C1, and is disposed so as to face the stacked body W held by the holding unit H. ing. The objective lens C4 may have a configuration in which lenses having different magnifications are switched by a revolver mechanism, or may have a configuration including a zoom lens or one lens having a fixed magnification.

  As described above, as a specific configuration of the imaging device C, the light Lm emitted from the emission unit 54 of the laser light source device 1 is reflected by the half mirror in the lens barrel C2, and is laminated as illumination light Lf from the objective lens C4. A configuration in which light (that is, observation light) Lv irradiated toward W and reflected by the inspection region F is taken in from the objective lens C4, passes through the half mirror, and enters the imaging camera C1 (a so-called coaxial falling method) ) Can be exemplified.

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

  The relative movement unit M moves the holding unit H and the imaging device C relative to each other. Specifically, the relative movement unit M relatively moves the holding unit H and the imaging device C in a direction parallel to the surface of the stacked body W (referred to as X direction / Y direction). More specifically, the relative movement unit 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 apparatus frame Kf, and includes a rail extending in the X direction and a movable portion that moves / stops on the rail.

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

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

  The movable parts of the X-axis stage M1 and the Y-axis stage M2 are controlled such as movement / stationary / positioning based on a control signal from the control unit CN by a linear motor, a rotary motor, a ball screw, or the like. In addition, the rotation unit of the rotation mechanism M3 is controlled such as rotation / stillness / angle change based on a control signal from the control unit CN by a DD motor or a rotation motor and a gear.

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

  Since the inspection apparatus K has such a configuration, the inspection apparatus K captures an image with the imaging apparatus C while sequentially changing the position of the inspection area F of the stacked body W, processes the image of each inspection area F, and stacks the W It is possible to inspect foreign matters and voids hidden in the interface.

  At this time, since the illumination light Lf irradiated toward the laminated body W uses laser light emitted from the laser light source device 1 according to the present invention, speckle noise is well removed. For this reason, it is possible to detect minute foreign matters and voids by using the strong coherence of the laser beam.

  The inspection apparatus K according to the present invention may be configured to include the above-described laser light source devices 1B to 1E instead of the above-described laser light source device 1. Regardless of which laser light source device 1, 1 </ b> B to 1 </ b> E is used, speckle noise is satisfactorily removed.

  In the above description, the coaxial falling method is exemplified as the specific configuration of the imaging device C that captures the light reflected by the inspection region F, but an oblique illumination method or the like may be used. Alternatively, the imaging device C is not limited to a configuration that captures light reflected from the inspection region F, and may be configured to capture light that has passed through the inspection region F (a so-called transmission illumination method). In the case of the transmitted illumination method, the light emitting unit 54 such as the laser light source device 1 is incorporated in the holding unit H, and the inspection region F is irradiated with the laser light Lf directly or via a mirror, and light that has passed through the inspection region F (that is, observation) The light (Lv) may be configured to be imaged by the imaging device C.

  In the above description, the configuration including the relative movement unit M is illustrated as the inspection apparatus K. However, when the inspection region F can be set wide, or when the inspection region F is a limited range of the stacked body W, the holding unit If it is not necessary to relatively move H and the imaging device C, a configuration in which the relative moving unit M is omitted may be used. Even when the relative movement unit M is provided, the rotation mechanism 3 may be omitted when it is not necessary to align the direction of the stacked body W or when the holding unit H can be used instead. Further, if the relative movement direction is sufficient in one of the XY directions, a configuration in which one of the X-axis stage M1 and the Y-axis stage M2 is omitted may be used. In addition, the relative movement unit M is not limited to the configuration in which the holding unit H side is moved / rotated in the XYθ direction, but may be configured to move / rotate the imaging device C in the XYθ direction, or may be a partially combined configuration. It may be.

  In the above description, the laminated body W is formed by bonding silicon wafers, and the wavelength of the illumination light Lf irradiated using the laser light Lm emitted from the laser light source device 1 includes 1000 to 1100 nm. The form which is light was illustrated. 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 more. If the infrared light has a wavelength of approximately 1000 nm or more, a sufficient amount of light for observing the inside (interface) of the silicon wafer can be obtained. On the other hand, when the wavelength is longer than 1100 nm, the sensitivity characteristic is deteriorated when the imaging device C3 of the imaging camera C1 is a CCD or a CMOS. Further, if the imaging device C3 of the imaging camera C1 uses a compound such as InGaAs, the sensitivity at the wavelength is high, but the operation speed (imaging rate) becomes slow. Therefore, if the laminated body W is obtained by bonding silicon wafers, the wavelength of the illumination light L1 emitted from the laser light source device 1 is preferably infrared light including 1000 to 1100 nm.

  However, in realizing the present invention, the illumination light Lf irradiated toward the stacked body W may be light having a wavelength other than this, and the wavelength characteristics (light transmittance, etc.) of the stacked body W to be inspected. ) Or the light receiving sensitivity characteristic of the image sensor C3.

DESCRIPTION OF SYMBOLS 1 Laser light source device 2 Laser light source part 3 Light beam branch part 4 Diffusing plate part 5 Light beam synthetic | combination part 20 Laser oscillator 21 Collimating lens 31 Beam splitter 32 Mirror 41 Diffusing plate (fixed type)
42 Diffuser (fixed type)
43 Diffusion plate (rotary type)
45 Rotating mechanism 46a to c Vibrating mechanism 51 First light receiving portion (first branched light beam)
52 2nd light-receiving part (2nd branched light beam)
53 Fiber part (a bundle of optical fibers)
54 Outgoing part (combined luminous flux)
L0 Light beam emitted from laser light source (laser light)
L1 First branch beam (before passing through polarizing plate)
L2 Second split beam (before passing through polarizing plate)
L1 'first branched light beam (after passing through polarizing plate)
L2 '2nd branch beam (after passing through polarizing plate)
Lm Light beam synthesized and emitted Cr Rotation center r1 Radius (first branch light beam)
r2 radius (second split light beam)
K inspection device W laminated body B foreign matter and void H holding part C imaging part S inspection part F inspection area Lf illumination light Lv observation light

Claims (7)

A laser light source device for emitting laser light,
A light beam branching unit that splits a light beam emitted from the laser light source unit into a first branched light beam and a second branched light beam;
A light beam combining unit that combines the first branched light beam and the second branched light beam,
The optical path length of the second branched light beam is set to be longer than the optical path length of the first branched light beam,
A laser light source device comprising a diffusion plate in an optical path of the first branched light beam and the second branched light beam. 2. The laser light source device according to claim 1, further comprising a diffusion plate moving mechanism that relatively moves the diffusion plate in a direction orthogonal to an optical path of the first branched light beam and the second branched light beam. The laser light source device according to claim 2, wherein the diffusion plate moving mechanism includes a rotation mechanism that rotates the diffusion plate. 4. The laser light source device according to claim 3, wherein the first branched light beam and the second branched light beam are arranged so as to be irradiated at different distances from a rotation center of the diffusion plate. 5. The optical path of the said 1st branched light beam and the said 2nd branched light beam was further equipped with the diffuser plate arrange | positioned facing the said diffuser plate, The Claim 1 characterized by the above-mentioned. Laser light source device. 6. The laser light source device according to claim 1, wherein the light beam combining unit includes a branch 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 6;
A holding unit for holding the laminate;
An imaging device for imaging light emitted from the laser light source device and passing or reflected through an inspection region set in the laminate;
An inspection apparatus 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 apparatus.

Images