JP2022121145A - Optical unit, branch unit and laser processing device - Google Patents

Abstract

To provide an optical unit that makes it possible to confirm an emitted state of a laser beam without using a workpiece for testing.SOLUTION: An optical unit comprises: a splitting unit that splits a first laser beam to form a plurality of second laser beams: and a split beam condensing lens that condenses the plurality of second laser beams at positions different in a direction perpendicular to an optical axis and in a direction parallel to the optical axis.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical unit and a branching unit for branching and condensing a laser beam, and a laser processing apparatus provided with the optical unit or the branching unit.

In the process of manufacturing device chips, a wafer is used in which devices are formed in a plurality of areas partitioned by a plurality of streets (dividing lines) arranged in a grid pattern. A plurality of device chips each having a device is obtained by dividing the wafer along the streets. Device chips are incorporated into various electronic devices such as mobile phones and personal computers.

A cutting device is mainly used for dividing the wafer. A cutting device includes a chuck table that holds a workpiece, and a cutting unit to which an annular cutting blade that cuts the workpiece is mounted. The wafer is cut and divided by holding the workpiece by a chuck table and rotating the cutting blade to cut into the workpiece.

On the other hand, in recent years, the development of a process for dividing wafers by laser processing is also underway. A laser processing apparatus is used for laser processing of the wafer. A laser processing apparatus includes a chuck table that holds a workpiece, and a laser beam irradiation unit that irradiates the workpiece with a laser beam (see Patent Documents 1 and 2).

For example, the wafer is ablated by a laser processing device. Specifically, the wafer is processed along the streets by scanning the laser beam along the streets while focusing the laser beam on or inside the wafer held by the chuck table. Then, the wafer is cut and divided by forming laser-processed grooves along the streets from the front surface to the back surface of the wafer. Further, by applying an external force to the wafer after irradiating the wafer with a laser beam along the streets, it is possible to break the wafer along the streets with the laser-processed region as the starting point of division.

JP 2007-275912 A JP 2020-196038 A

A laser beam irradiation unit installed in a laser processing apparatus includes a laser oscillator and an optical system for guiding a laser beam emitted from the laser oscillator to a workpiece. Then, the types of optical elements (lenses, mirrors, etc.) included in the optical system are selected, and the arrangement and angle of each optical element are adjusted so that the laser beam is applied to the workpiece under desired conditions.

Here, when a workpiece is processed by a laser processing apparatus, if the laser beam is not irradiated onto the workpiece under the intended conditions, problems occur in processing the workpiece. For example, if the laser beam is incident obliquely on the surface of the workpiece for some reason (incident angle ≠ 0°), the laser-processed groove formed by the irradiation of the laser beam will not be visible on the surface of the workpiece. , making it difficult to properly divide the workpiece in subsequent steps. In addition, debris generated by laser beam irradiation scatters and accumulates intensively on one side of the laser processing groove, making it difficult to remove the debris from the workpiece even when the workpiece is washed. Become.

Therefore, when processing a workpiece with a laser processing apparatus, the irradiation state of the laser beam is inspected in advance. Specifically, a test workpiece is actually processed by a laser beam emitted from a laser beam irradiation unit. Then, by observing the state (shape, size, angle, etc.) of the laser-processed groove formed in the test workpiece, it is determined whether the laser beam is being irradiated under the intended conditions. .

However, in order to perform the above inspection, it is necessary to prepare a test workpiece, which is a consumable item. In addition, when actually performing the inspection, after carrying, holding, processing, cleaning, etc. of the test workpiece in the laser processing device, the laser processing groove formed in the test workpiece It is necessary to observe the Therefore, the inspection of the irradiation state of the laser beam using the test workpiece is troublesome and costly.

The present invention has been made in view of such problems, and provides an optical unit, a branching unit, or a laser processing apparatus that makes it possible to check the irradiation state of a laser beam without using a test workpiece. With the goal.

According to one aspect of the present invention, a splitting unit that splits a first laser beam to form a plurality of second laser beams, and splits the plurality of second laser beams in directions perpendicular and parallel to the optical axis. and a diverging beam focusing lens for focusing at different positions.

Further, according to another aspect of the present invention, a first laser beam is branched to form a plurality of second laser beams, and the plurality of second laser beams are split in directions perpendicular to and parallel to the optical axis. A branching unit is provided to focus light at different positions in the .

According to another aspect of the present invention, there is provided a laser processing apparatus for processing a work piece, comprising: a chuck table holding the work piece; a laser beam irradiation unit that irradiates a beam, a movement unit that relatively moves the chuck table and a focus position of the laser beam irradiated from the laser beam irradiation unit, and a detection unit that detects the laser beam. , wherein the laser beam irradiation unit comprises a laser oscillator, the detection unit comprises a splitting unit for splitting a first laser beam emitted from the laser oscillator to form a plurality of second laser beams; a branch beam condensing lens that condenses the second laser beam at different positions in a direction perpendicular and parallel to the optical axis; and a plurality of the second laser beams condensed by the branch beam condensing lens. and an imaging unit that captures an image to generate a captured image.

According to another aspect of the present invention, there is provided a laser processing apparatus for processing a work piece, comprising: a chuck table holding the work piece; a laser beam irradiation unit that irradiates a beam, a movement unit that relatively moves the chuck table and a focus position of the laser beam irradiated from the laser beam irradiation unit, and a detection unit that detects the laser beam. , wherein the laser beam irradiation unit includes a laser oscillator, the detection unit splits a first laser beam emitted from the laser oscillator to form a plurality of second laser beams, and a plurality of the second laser beams. A branching unit that converges two laser beams at different positions in directions perpendicular to and parallel to the optical axis; A laser processing apparatus is provided comprising:

In addition, preferably, the laser processing apparatus further includes a determination unit that determines an irradiation state of the laser beam applied to the workpiece based on the captured image generated by the imaging unit. Also, preferably, the detection unit is provided adjacent to the chuck table.

The optical unit and the splitter unit according to one aspect of the present invention split a first laser beam to form a plurality of second laser beams, and split the plurality of second laser beams in a direction perpendicular to the optical axis of the optical unit and Focus the light at different positions in parallel directions. Then, the plurality of second laser beams condensed by the branched beam condensing lens are imaged by the imaging unit, and the pattern of the plurality of second laser beams is checked to determine whether the irradiation state of the first laser beam is appropriate. can.

The above determination can be made without subjecting the test workpiece to laser processing. As a result, it is possible to omit the process of procuring a test workpiece and processing the test workpiece using a laser processing apparatus, thereby reducing the labor and cost required for inspecting the irradiation state of the laser beam.

It is a perspective view which shows a laser processing apparatus. It is a perspective view which shows a to-be-processed object. FIG. 3A is a partial cross-sectional front view showing a laser processing apparatus for processing a workpiece, and FIG. 3B is a partial cross-sectional front view showing a laser processing apparatus for inspecting the irradiation state of a laser beam. be. FIG. 4 is a schematic diagram showing a laser beam irradiation unit and a detection unit; It is a perspective view showing an optical unit. FIG. 6A is an image diagram showing a first captured image generated when the arrangement of the optical system is appropriate, and FIG. 6B is an image diagram generated when the arrangement of the optical system is inappropriate. It is an image diagram showing a second captured image. FIG. 7A is an image diagram showing a first captured image and a first graphic, and FIG. 7B is an image diagram showing a second captured image and a second graphic. It is a schematic diagram which shows the laser beam irradiation unit and test|inspection unit which concern on a modification. FIG. 9A is a schematic diagram showing the laser beam irradiation unit and the inspection unit with the branching unit arranged at the retracted position, and FIG. It is a schematic diagram which shows an irradiation unit and an inspection unit.

An embodiment according to one aspect of the present invention will be described below with reference to the accompanying drawings. First, a configuration example of a laser processing apparatus capable of mounting an optical unit and an inspection unit according to this embodiment will be described. FIG. 1 is a perspective view showing a laser processing device 2. FIG. In FIG. 1, the X-axis direction (processing feed direction, first horizontal direction) and the Y-axis direction (indexing feed direction, second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, vertical direction, height direction) is a direction perpendicular to the X-axis direction and the Y-axis direction.

The laser processing device 2 includes a base 4 that supports each component constituting the laser processing device 2 . The upper surface of the base 4 is substantially parallel to the horizontal direction (XY plane direction), and a moving unit (moving mechanism) 6 is provided on the upper surface of the base 4 . The moving unit 6 includes a Y-axis moving unit (Y-axis moving mechanism) 8 , an X-axis moving unit (X-axis moving mechanism) 18 , and a Z-axis moving unit (Z-axis moving mechanism) 32 .

The Y-axis movement unit 8 includes a pair of Y-axis guide rails 10 arranged on the upper surface of the base 4 along the Y-axis direction. A flat Y-axis moving table 12 is attached to the pair of Y-axis guide rails 10 so as to be slidable along the Y-axis guide rails 10 .

A nut portion (not shown) is provided on the back surface (lower surface) side of the Y-axis moving table 12, and the nut portion is arranged between the pair of Y-axis guide rails 10 along the Y-axis direction. A Y-axis ball screw 14 is screwed thereon. A Y-axis pulse motor 16 for rotating the Y-axis ball screw 14 is connected to the end of the Y-axis ball screw 14 . When the Y-axis ball screw 14 is rotated by the Y-axis pulse motor 16, the Y-axis moving table 12 moves along the pair of Y-axis guide rails 10 in the Y-axis direction.

The X-axis movement unit 18 includes a pair of X-axis guide rails 20 arranged along the X-axis direction on the surface (upper surface) side of the Y-axis movement table 12 . A plate-shaped X-axis moving table 22 is attached to the pair of X-axis guide rails 20 so as to be slidable along the X-axis guide rails 20 .

A nut portion (not shown) is provided on the rear surface (lower surface) side of the X-axis moving table 22, and the nut portion is arranged between the pair of X-axis guide rails 20 along the X-axis direction. An X-axis ball screw 24 is screwed thereon. An X-axis pulse motor 26 for rotating the X-axis ball screw 24 is connected to the end of the X-axis ball screw 24 . When the X-axis ball screw 24 is rotated by the X-axis pulse motor 26, the X-axis moving table 22 moves along the pair of X-axis guide rails 20 in the X-axis direction.

A chuck table (holding table) 28 for holding a workpiece 11 (see FIG. 2) to be processed by the laser processing device 2 is provided on the surface (upper surface) of the X-axis moving table 22 . A plurality of clamps 30 are provided around the chuck table 28 for holding and fixing an annular frame 19 (see FIG. 2) that supports the workpiece 11 .

The upper surface of the chuck table 28 is a flat surface formed along the horizontal direction (XY plane direction), and constitutes a holding surface 28a that holds the workpiece 11 . The holding surface 28a is connected to a suction source (not shown) such as an ejector via a channel (not shown) formed inside the chuck table 28, a valve (not shown), and the like.

When the Y-axis moving table 12 is moved along the Y-axis direction, the chuck table 28 is moved along the Y-axis direction. Further, when the X-axis moving table 22 is moved along the X-axis direction, the chuck table 28 is moved along the X-axis direction. Further, a rotary drive source (not shown) such as a motor is connected to the chuck table 28, and this rotary drive source rotates the chuck table 28 around a rotary shaft substantially parallel to the Z-axis direction.

A Z-axis movement unit 32 is provided at the rear end of the base 4 (behind the Y-axis movement unit 8, X-axis movement unit 18, and chuck table 28). The Z-axis movement unit 32 comprises a support structure 34 arranged on the top surface of the base 4 . The support structure 34 includes a rectangular parallelepiped base portion 34a fixed to the base 4, and a columnar support portion 34b projecting upward from an end portion of the base portion 34a. The surface (side surface) of the support portion 34b is formed flat along the Z-axis direction.

A pair of Z-axis guide rails 36 are provided along the Z-axis direction on the surface of the support portion 34b. A flat Z-axis moving table 38 is attached to the pair of Z-axis guide rails 36 so as to be slidable along the Z-axis guide rails 36 .

A nut portion (not shown) is provided on the back side of the Z-axis moving table 38, and this nut portion has a Z-axis ball arranged between a pair of Z-axis guide rails 36 along the Z-axis direction. Screws (not shown) are screwed together. A Z-axis pulse motor 40 for rotating the Z-axis ball screw is connected to the end of the Z-axis ball screw. When the Z-axis pulse motor 40 rotates the Z-axis ball screw, the Z-axis moving table 38 moves along the pair of Z-axis guide rails 36 in the Z-axis direction.

A support member 42 is fixed to the surface side of the Z-axis moving table 38 . The support member 42 supports at least some components of the laser beam irradiation unit 44 . The laser beam irradiation unit 44 performs laser processing on the workpiece 11 by irradiating the workpiece 11 held by the chuck table 28 with a laser beam.

An imaging unit 46 for imaging the workpiece 11 and the like held by the chuck table 28 is provided at the tip of the laser beam irradiation unit 44 . As the imaging unit 46, a visible light camera having an imaging element that receives visible light and converts it into an electric signal, an infrared camera that has an imaging element that receives infrared light and converts it into an electric signal, or the like can be used. Alignment of the chuck table 28 and the laser beam irradiation unit 44 and the like are performed based on an image obtained by imaging the workpiece 11 with the imaging unit 46 .

When the Z-axis moving table 38 is moved along the Z-axis direction, the laser beam irradiation unit 44 and the imaging unit 46 are moved in the Z-axis direction. As a result, adjustment of the condensing position in the Z-axis direction of the laser beam emitted from the laser beam irradiation unit 44, focusing of the imaging unit 46, and the like are performed.

A moving unit 6 is composed of the Y-axis moving unit 8 , the X-axis moving unit 18 , and the Z-axis moving unit 32 . Then, the moving unit 6 relatively moves the chuck table 28 and the focus position of the laser beam emitted from the laser beam irradiation unit 44 . Further, the moving unit 6 relatively moves the chuck table 28 and the imaging unit 46 .

The laser processing apparatus 2 is equipped with a detection unit 48 that detects the laser beam emitted from the laser beam irradiation unit 44 . For example, the detection unit 48 is installed on the X-axis movement table 22 so as to be adjacent to the chuck table 28 . In this case, the position of the detection unit 48 in the X-axis direction and the Y-axis direction can be adjusted by the Y-axis movement unit 8 and the X-axis movement unit 18 . Details of the configuration and function of the detection unit 48 will be described later.

The laser processing device 2 also includes a display section (display unit, display device) 50 that displays various information about the laser processing device 2 . For example, a touch panel display is used as the display unit 50 . In this case, the operator of the laser processing device 2 can input information to the laser processing device 2 by touching the display unit 50 . That is, the display unit 50 also functions as an input unit (input unit, input device) for inputting various kinds of information to the laser processing apparatus 2, and is used as a user interface. However, the input unit may be a mouse, a keyboard, or the like provided independently from the display unit 50 .

Furthermore, the laser processing device 2 includes a control section (control unit, control device) 52 that controls the laser processing device 2 . The control unit 52 is connected to each component (moving unit 6, chuck table 28, clamp 30, laser beam irradiation unit 44, imaging unit 46, detection unit 48, display unit 50, etc.) constituting the laser processing apparatus 2. there is The control unit 52 generates control signals for controlling the operations of the constituent elements of the laser processing device 2 to operate the laser processing device 2 .

For example, the control unit 52 is configured by a computer, and stores a calculation unit that performs various calculations necessary for operating the laser processing device 2 and various information (data, programs, etc.) used for operating the laser processing device 2. and a storage unit. The calculation unit includes a processor such as a CPU (Central Processing Unit). Also, the storage unit includes various memories that constitute a main storage device, an auxiliary storage device, and the like.

A laser processing device 2 applies laser processing to a workpiece 11 . FIG. 2 is a perspective view showing the workpiece 11. FIG. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and has a front surface 11a and a back surface 11b that are substantially parallel to each other. The workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of streets (dividing lines) 13 arranged in a lattice so as to intersect each other.

Devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed on surfaces 11a of a plurality of areas partitioned by the streets 13, respectively. It is By dividing the workpiece 11 along the streets 13, a plurality of device chips each having a device 15 are obtained.

The type, material, shape, structure, size, etc. of the workpiece 11 are not limited. For example, the workpiece 11 may be a wafer of arbitrary shape and size made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, or the like. Moreover, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device 15 , and the device 15 may not be formed on the workpiece 11 .

A circular tape 17 having a diameter larger than that of the workpiece 11 is attached to the back surface 11b side of the workpiece 11 . For example, the tape 17 includes a circular film-like substrate and an adhesive layer (glue layer) provided on the substrate. The base material is made of resin such as polyolefin, polyvinyl chloride, polyethylene terephthalate. Also, the adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive or the like. In addition, an ultraviolet curable resin that is cured by irradiation with ultraviolet rays may be used for the adhesive layer.

The outer peripheral portion of the tape 17 is attached to an annular frame 19 made of metal such as SUS (stainless steel). A central portion of the frame 19 is provided with a circular opening 19 a having a diameter larger than that of the workpiece 11 . With the workpiece 11 placed inside the opening 19a, the central portion of the tape 17 is attached to the back surface 11b side of the workpiece 11, and the outer peripheral portion of the tape 17 is attached to the frame 19. Object 11 is supported by frame 19 via tape 17 .

FIG. 3A is a partially cross-sectional front view showing a laser processing device 2 for processing a workpiece 11. FIG. When the workpiece 11 is processed by the laser processing apparatus 2 , first, the workpiece 11 is held by the chuck table 28 . Specifically, the workpiece 11 is placed on the chuck table 28 so that the back surface 11b side (tape 17 side) faces the holding surface 28a. Also, the frame 19 is fixed by a plurality of clamps 30 . In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 28a, the workpiece 11 is suction-held by the chuck table 28 via the tape 17. As shown in FIG.

Next, a laser beam 60 is emitted from the laser beam irradiation unit 44 toward the workpiece 11, and the workpiece 11 is subjected to laser processing. For example, the irradiation conditions (wavelength, power, spot diameter, repetition frequency, etc.) of the laser beam 60 are set so that the region of the workpiece 11 irradiated with the laser beam 60 is ablated.

When the chuck table 28 is moved along the X-axis direction while the laser beam 60 is focused on the surface 11a of the workpiece 11 or inside, the laser beam 60 is scanned along the X-axis direction. As a result, the workpiece 11 is ablated to form linear grooves (laser-processed grooves).

For example, the workpiece 11 is divided along the streets 13 by forming grooves from the front surface 11 a to the back surface 11 b of the workpiece 11 along all the streets 13 . Further, after forming grooves having a depth less than the thickness of the workpiece 11 along all the streets 13 on the front surface 11a side of the workpiece 11, the rear surface 11b side of the workpiece 11 is ground to form the grooves. By exposing the back surface 11 b of the workpiece 11 , the workpiece 11 is divided along the streets 13 . Thereby, a plurality of device chips each having the device 15 are manufactured.

When the workpiece 11 is processed by the laser processing apparatus 2, the irradiation state of the laser beam 60 is inspected in advance, and the laser beam 60 from the laser beam irradiation unit 44 is applied under conditions suitable for processing the workpiece 11. It is confirmed whether or not irradiation is performed with In this embodiment, the irradiation state of the laser beam 60 is inspected using the detection unit 48 mounted on the laser processing apparatus 2 .

FIG. 3B is a partially cross-sectional front view showing the laser processing apparatus 2 for inspecting the irradiation state of the laser beam 60. FIG. When inspecting the irradiation state of the laser beam 60, first, the laser beam irradiation unit 44 and the detection unit 48 are arranged so as to overlap each other. Specifically, the X-axis moving table 22 is moved to position the detection unit 48 directly below the laser beam irradiation unit 44 . After that, the laser beam 60 is emitted from the laser beam irradiation unit 44 to the detection unit 48 , and the laser beam 60 is detected by the detection unit 48 .

FIG. 4 is a schematic diagram showing the laser beam irradiation unit 44 and the detection unit 48. As shown in FIG. The laser beam irradiation unit 44 includes a laser oscillator 70 such as a YAG laser or a YVO ₄ laser, and a laser beam (first laser beam) 62A emitted from the laser oscillator 70 onto the workpiece 11 (see FIG. 3) held by the chuck table 28. (A)) or an optical system 72 leading to the detection unit 48 . The optical system 72 includes a plurality of optical elements (lenses, mirrors, etc.) and controls the traveling direction, shape, etc. of the laser beam 62A.

Optical system 72 includes a collector 74 that collects laser beam 62A at a predetermined location. For example, a condenser lens such as a convex lens is used as the condenser 74 . A laser beam 62A emitted from a laser oscillator 70 is condensed at a predetermined position by a concentrator 74 . A laser beam 62A emitted from the condenser 74 corresponds to the laser beam 60 (see FIG. 3A) used for processing the workpiece 11. As shown in FIG.

The detection unit 48 includes an optical unit 80 that splits and condenses the laser beam 62A emitted from the laser beam irradiation unit 44 . For example, the optical unit 80 includes a collimating lens 82 , a branching unit 84 that branches the laser beam, and a branched beam condensing lens 86 that converges the laser beam branched by the branching unit 84 .

When the detection unit 48 is irradiated with the laser beam 62 A from the laser beam irradiation unit 44 , the laser beam 62 A is converted into collimated light by the collimating lens 82 and then enters the branching unit 84 . The laser beam 62A is branched by the branching unit 84 to form a plurality of laser beams (second laser beams) 62B.

In FIG. 4B, for convenience of explanation, a plurality of laser beams 62B formed by branching the laser beam 62A are schematically illustrated by independent straight lines (FIGS. 5, 8, and 6 described later). 9 (B) as well). Then, each of the plurality of laser beams 62B is incident on the branched beam condensing lens 86 and condensed at a predetermined position.

As the branching unit 84, for example, a diffractive optical element (DOE) is used. FIG. 5 is a perspective view showing the optical unit 80. FIG. FIG. 5 shows an example in which a diffractive optical element 90 is used as the branching unit 84 (see FIG. 4).

The diffractive optical element 90 includes a first surface 90a and a second surface 90b that are substantially parallel to each other, and the first surface 90a and the second surface 90b are perpendicular to the optical axis of the optical unit 80 (the optical axis of the diffractive optical element 90). are arranged so that Also, on the side of the first surface 90a of the diffractive optical element 90, a periodic concave-convex pattern (diffraction grating) 90c for branching the laser beam 62A is formed. The uneven pattern 90c can also be formed on the side of the second surface 90b of the diffractive optical element 90. FIG.

When the laser beam 62A is incident on the first surface 90a side of the diffractive optical element 90, the laser beam 62A is diffracted in the area where the concave-convex pattern 90c is formed, and the laser beam 62A is branched. As a result, multiple laser beams 62B are generated and emitted from the second surface 90b side of the diffractive optical element 90 . In addition, below, as an example, a case where the laser beam 62A is branched into nine laser beams 62B will be described.

A plurality of laser beams 62B emitted from the second surface 90b side of the diffractive optical element 90 are incident on the branched beam condenser lens 86. As shown in FIG. A plurality of laser beams 62B are respectively condensed by the branched beam condensing lens 86 .

Here, the diffractive optical element 90 and the branched beam condensing lens 86 are located at different positions in the direction perpendicular to the optical axis of the optical unit 80 (the XY plane direction) and in the direction parallel to the optical axis of the optical unit 80 (the Z-axis direction). designed and arranged to be focused at Specifically, the uneven pattern 90c of the diffractive optical element 90 is appropriately designed so that the laser beam 62A is split into a desired number of laser beams 62B. Also, the size, numerical aperture (NA), etc. of the branched beam condensing lens 86 are appropriately set so that the plurality of laser beams 62B are condensed within a predetermined range. Therefore, the condensing positions 64A to 64I of the plurality of laser beams 62B are positioned at different positions in the XY plane direction and at different positions in the Z-axis direction.

For example, the condensing positions 64A to 64I are arranged at predetermined intervals along the X-axis direction and the Y-axis direction. Further, if the position of the condensing position 64E in the Z-axis direction is the reference position (0 μm), the positions in the Z-axis direction of the condensing positions 64A to 64D and 64F to 64I are respectively 400 μm, 300 μm, 200 μm, 100 μm, and −100 μm. , -200 μm, -300 μm, and -400 μm.

Although the diffractive optical element 90 has been described above as an example of the branching unit 84 that branches the laser beam 62A, the type of the branching unit 84 is not limited. For example, as the branching unit 84, a spatial light modulator (SLM), a gradient index (GRIN) lens, or the like can be used. Also in this case, the branching unit 84 and the branching beam condensing lens 86 are designed and arranged so that the plurality of laser beams 62B are condensed at different positions in the directions perpendicular to and parallel to the optical axis of the optical unit 80. be done.

In addition to the function of branching the laser beam 62A to form a plurality of laser beams 62B, the branching unit 84 further divides the plurality of laser beams 62B into the optical axis of the optical unit 80 (optical axis of the branching unit 84, branching unit 84). It may have a function of condensing light at different positions in the direction perpendicular to and parallel to the optical axis of the beam condensing lens 86). For example, the uneven pattern 90c of the diffractive optical element 90 splits the laser beam 62A into a desired number of laser beams 62B, and splits the plurality of laser beams 62B in directions perpendicular and parallel to the optical axis of the diffractive optical element 90. is suitably designed to collect light at different positions in .

In the above case, the branched beam condensing lens 86 can be omitted, and the size and weight of the optical unit 80 can be reduced, and the cost can be reduced. Also, the plurality of laser beams 62B condensed within a predetermined range by the branching unit 84 may be further condensed by the branched beam condensing lens 86. FIG. This makes it possible to control the diameter (spot diameter) of the laser beam 62B at the condensing position to be smaller.

As shown in FIG. 4, the detection unit 48 also includes an imaging unit 88 that images the plurality of laser beams 62B formed by the optical unit 80 to generate a captured image. For example, as the imaging unit 88, a camera having an imaging element that receives the laser beam 62B and converts it into an electric signal is used. A plurality of laser beams 62B that have passed through the branched beam condensing lens 86 reach the light receiving surface of the imaging unit 88 and are imaged by the imaging unit 88 . Thereby, a captured image showing the pattern of the plurality of laser beams 62B on the light receiving surface of the imaging unit 88 is generated.

The pattern of the plurality of laser beams 62B reaching the imaging unit 88 depends on the arrangement of the optical system 72 of the laser beam irradiation unit 44. FIG. Specifically, the positions and shapes of the plurality of laser beams 62B on the light receiving surface of the imaging unit 88 change according to the positions and inclinations of optical elements (lenses, mirrors, etc.) included in the optical system 72 . Therefore, different captured images are acquired depending on whether the arrangement of the optical system 72 is appropriate or inappropriate.

FIG. 6A is an image diagram showing a captured image (first captured image) 100A generated when the arrangement of the optical system 72 is appropriate. Captured image 100A includes patterns 102A to 102I corresponding to the shapes of multiple laser beams 62B on the light receiving surface of imaging unit 88. FIG.

As described above, the condensing positions 64A to 64I (see FIG. 5) of the laser beam 62B in the direction (Z-axis direction) parallel to the optical axis of the optical unit 80 are different. Therefore, patterns 102A to 102I having different sizes are represented in the captured image 100A. For example, when various optical elements included in the optical system 72 (see FIG. 4) are correctly arranged, circular patterns 102A to 102I having different sizes and arranged at approximately equal intervals appear in the captured image 100A. be done.

FIG. 6B is an image diagram showing a captured image (second captured image) 100B generated when the arrangement of the optical system 72 is inappropriate. If the positions and angles of various optical elements included in the optical system 72 (see FIG. 4) are misaligned, the irradiation state of the laser beam 62A entering the detection unit 48 from the optical system 72 changes, and the light received by the imaging unit 88 changes. The irradiation state of the laser beam 62B incident on the surface also changes. For example, the incident angle of the laser beam 62B increases, or aberration of the laser beam 62B occurs.

As a result, the captured image 100B represents patterns 102A to 102I different from the captured image 100A. For example, as shown in FIG. 6B, patterns 102A to 102D and 102F to 102I whose center position is shifted and whose shape has changed to an elliptical shape are represented in a captured image 100B.

Here, the laser beam 60 (see FIG. 3A) irradiated to the workpiece 11 corresponds to the laser beam 62A irradiated from the optical system 72 of the laser beam irradiation unit 44 (see FIG. 4). The irradiation state of the laser beam 62A is reflected in the captured images 100A and 100B generated by capturing the plurality of laser beams 62B formed by branching the laser beam 62A with the imaging unit 88. FIG. Therefore, by irradiating the detection unit 48 with the laser beam 60 (see FIG. 3B) and checking the captured image generated by the imaging unit 88, the irradiation of the laser beam 60 used for processing the workpiece 11 can be confirmed. It is possible to grasp whether the state is appropriate or not.

Further, the imaging unit 88 simultaneously captures images of the plurality of laser beams 62B irradiated to the light receiving surface of the imaging unit 88, thereby generating a captured image including the patterns 102A to 102D corresponding to the plurality of laser beams 62B. Therefore, there is no deviation in the timing at which the plurality of laser beams 62B are imaged, and a captured image representing the irradiation state of the laser beam 62A at a certain point in time is obtained by the plurality of patterns 102A to 102D. As a result, for example, changes in the irradiation state of the laser beam 62A in a time period (transitional period) immediately after the laser oscillation by the laser oscillator 70 (see FIG. 4) starts can be monitored in real time by observing the captured image. You can check with

A captured image generated by the imaging unit 88 is input to the control section 52 shown in FIG. Further, the control unit 52 outputs a control signal to the display unit 50 and causes the display unit 50 to display the captured image. Then, the operator in charge of checking the irradiation state of the laser beam 60 visually checks the captured image displayed on the display unit 50 to determine whether the laser beam 60 is properly irradiated based on the pattern included in the captured image. judge.

However, the irradiation state of the laser beam 60 may be determined by the controller 52 . For example, the control unit 52 includes a determination unit 54 that determines the irradiation state of the laser beam 60 and a storage unit 56 that stores information (data) used for determination. For example, the storage unit 56 stores a captured image ( 6A) is stored in advance as a reference image.

When inspecting the laser beam 60, the laser beam 60 is irradiated from the laser beam irradiation unit 44 to the detection unit 48 (see FIG. 3B), and a captured image is generated by the imaging unit 88 (see FIG. 4). . Then, the captured image is output from the imaging unit 88 to the determination section 54 .

When the captured image is input to the determination unit 54, the determination unit 54 reads the reference image from the storage unit 56 and compares the captured image and the reference image. For example, the determination unit 54 performs image processing such as pattern matching using the captured image and the reference image, and calculates the degree of similarity between the captured image and the reference image.

Then, the determination unit 54 determines whether the irradiation state of the laser beam 60 is appropriate by comparing the calculated degree of similarity with a preset reference value. For example, the determination unit 54 determines that the irradiation state of the laser beam 60 is appropriate when the degree of similarity is equal to or greater than the reference value (or exceeds the reference value). On the other hand, if the degree of similarity is less than the reference value (or equal to or less than the reference value), the determination unit 54 determines that the irradiation state of the laser beam 60 is inappropriate.

As described above, the determination unit 54 determines the irradiation state of the laser beam 60 with which the workpiece 11 is irradiated based on the captured image generated by the imaging unit 88 . Then, a message or the like corresponding to the result of determination by the determination unit 54 is displayed on the display unit 50 and notified to the operator.

Note that there is no limitation on the method of comparing the captured image and the reference image. For example, the determination unit 54 may generate a figure reflecting the pattern arrangement by connecting a plurality of patterns represented in the captured image with straight lines. FIG. 7A is an image diagram showing a captured image (first captured image) 100A and a graphic (first graphic) 104A, and FIG. 7B is a captured image (second captured image) 100B and a graphic (second 104B is an image diagram showing a figure) 104B. FIG.

For example, the determination unit 54 identifies the center coordinates of the four patterns 102A, 102C, 102G, and 102I shown near the four corners of the captured images 100A and 100B by image processing. Next, the determination unit 54 generates straight lines connecting the centers of the patterns 102A, 102C, 102G, and 102I. As a result, quadrangular figures 104A and 104B corresponding to the array of patterns included in the captured images 100A and 100B are generated.

Further, in the storage unit 56 (see FIG. 1), a figure (reference figure) reflecting the arrangement of patterns included in the reference image is stored in advance. Then, the determination unit 54 compares the figures 104A and 104B extracted from the captured images 100A and 100B with the reference figure by image processing such as pattern matching, and calculates the similarity between the figures 104A and 104B and the reference figure. do. After that, the determination unit 54 determines whether the irradiation state of the laser beam 60 is appropriate by comparing the calculated degree of similarity with a preset reference value.

Further, for example, the determination unit 54 may compare the shape of the pattern included in the captured image with the shape of an ideal pattern (reference pattern) stored in advance in the storage unit 56 . In this case, a specific pattern included in the captured image may be compared with the reference pattern, or the shapes of a plurality of patterns included in the captured image may be compared with the corresponding reference pattern.

As described above, the optical unit 80 according to the present embodiment includes the branching unit 84 that branches the laser beam 62A to form a plurality of laser beams 62B, and the plurality of laser beams 62B that are perpendicular to the optical axis of the optical unit 80. and a diverging beam converging lens 86 for converging at different positions in the directional and parallel directions. Then, the plurality of laser beams 62B condensed by the branched beam condensing lens 86 are imaged by the image pickup unit 88, and the pattern of the plurality of laser beams 62B is confirmed to determine whether the irradiation state of the laser beam 62A is appropriate. .

The above determination can be made without subjecting the test workpiece to laser processing. As a result, the process of procuring a test workpiece and processing the test workpiece using the laser processing apparatus 2 can be omitted, and the labor and cost required for inspecting the irradiation state of the laser beam can be reduced. .

Note that the configurations of the laser beam irradiation unit 44 and the detection unit 48 described in this embodiment can be changed as appropriate within the range in which the laser beam 60 can be inspected (see FIG. 3B). FIG. 8 is a schematic diagram showing a laser beam irradiation unit 44 and a detection unit 48 according to the first modification.

Optical system 72 of laser beam irradiation unit 44 shown in FIG. A laser beam 62 A emitted from a laser oscillator 70 is sequentially reflected by mirrors 110 , 112 and 114 and guided to a condenser 74 . Then, the laser beam 62A condensed by the condenser 74 is irradiated onto the workpiece 11 held by the chuck table 28, and the workpiece 11 is processed.

A branching unit 84 of the detection unit 48, a branched beam condensing lens 86, and an imaging unit 88 are arranged on an extension of a straight line connecting the mirrors 112 and 114. FIG. A portion of the laser beam 62A reaching the mirror 114 is transmitted through the mirror 114 and reaches the detection unit 48 as leakage light.

A laser beam 62A incident on the detection unit 48 from the mirror 114 is converted by the branching unit 84 into a plurality of laser beams 62B. Then, the plurality of laser beams 62B are separated by the branched beam condenser lens 86 at different positions in the direction (YZ plane direction) and parallel direction (X-axis direction) to the optical axis of the detection unit 48 (optical unit 80). It is collected and imaged by imaging unit 88 .

The detection unit 48 can detect the laser beam 62A while the workpiece 11 is being processed by the laser beam 62A. As a result, it is possible to simultaneously process the workpiece 11 and inspect the laser beam 62A.

Also, the condenser 74 of the optical system 72 and the branched beam condenser lens 86 of the detection unit 48 can be used in common. 9A and 9B are schematic diagrams showing a laser beam irradiation unit 44 and a detection unit 48 according to a second modification.

9A and 9B, the branching unit 84 is arranged above the collector 74 and below the mirror 114. In FIGS. A moving mechanism (not shown) is connected to the branching unit 84 to move the branching unit 84 along the horizontal direction (XY plane direction). With this moving mechanism, the branching unit 84 is moved to a position where it does not overlap the collector 74 and the mirror 114 (retracted position, see FIG. 9A) and a position where it overlaps the collector 74 and the mirror 114 (branch position, FIG. 9A). (B) reference) and. Also, the imaging unit 88 is provided at a position adjacent to the chuck table 28 (for example, above the X-axis moving table 22 (see FIG. 1)).

FIG. 9A is a schematic diagram showing the laser beam irradiation unit 44 and the detection unit 48 with the branching unit 84 arranged at the retracted position. When applying laser processing to the workpiece 11, the branching unit 84 is arranged at the retracted position. Then, the laser beam 62A emitted from the laser oscillator 70 is reflected by the mirror 114, condensed by the condenser 74, and irradiated onto the workpiece 11. As shown in FIG.

FIG. 9B is a schematic diagram showing the laser beam irradiation unit 44 and the detection unit 48 with the branching unit 84 arranged at the branching position. When inspecting the irradiation state of the laser beam 62A, the branching unit 84 is inserted between the collector 74 and the mirror 114 and arranged at the branching position. In addition, the imaging unit 88 is arranged at a position overlapping the collector 74 and the branching unit 84 .

A laser beam 62A emitted from the laser oscillator 70 is reflected by the mirror 114, enters the branching unit 84, and is converted into a plurality of laser beams 62B. Then, the plurality of laser beams 62B are condensed by the concentrator 74 at different positions in the direction (XY plane direction) and parallel direction (Z-axis direction) to the optical axis of the detection unit 48 (optical unit 80). and captured by the imaging unit 88 . That is, the condenser 74 also functions as the branched beam condenser lens 86 of the detection unit 48 . By using the condenser 74 and the branched beam condenser lens 86 in this way, the number of optical elements included in the detection unit 48 can be reduced.

In the above description, the laser beam 62A emitted from the laser oscillator 70 is detected by the detection unit 48 (see FIGS. 4, 8, and 9B). It may be provided inside. In this case, the state of the laser oscillated by the laser oscillator 70 can be confirmed using the detection unit 48 .

In addition, the structures, methods, and the like according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention.

REFERENCE SIGNS LIST 11 workpiece 11a front surface 11b rear surface 13 street (planned division line)
REFERENCE SIGNS LIST 15 device 17 tape 19 frame 19a opening 2 laser processing device 4 base 6 moving unit (moving mechanism)
8 Y-axis movement unit (Y-axis movement mechanism)
10 Y-axis guide rail 12 Y-axis movement table 14 Y-axis ball screw 16 Y-axis pulse motor 18 X-axis movement unit (X-axis movement mechanism)
20 X-axis guide rail 22 X-axis moving table 24 X-axis ball screw 26 X-axis pulse motor 28 Chuck table (holding table)
28a holding surface 30 clamp 32 Z-axis movement unit (Z-axis movement mechanism)
34 support structure 34a base 34b support 36 Z-axis guide rail 38 Z-axis movement table 40 Z-axis pulse motor 42 support member 44 laser beam irradiation unit 46 imaging unit 48 detection unit 50 display (display unit, display device)
52 control unit (control unit, control device)
54 determination unit 56 storage unit 60 laser beam 62A laser beam (first laser beam)
62B laser beam (second laser beam)
64A to 64I Condensing position 70 Laser oscillator 72 Optical system 74 Concentrator 80 Optical unit 82 Collimating lens 84 Branching unit 86 Branching beam condensing lens 88 Imaging unit 90 Diffractive optical element 90a First surface 90b Second surface 90c Concavo-convex pattern ( Diffraction grating)
100A captured image (first captured image)
100B captured image (second captured image)
102A to 102I pattern 104A figure (first figure)
104B figure (second figure)
110, 112, 114 Mirror

Claims (6)

a branching unit for branching the first laser beam to form a plurality of second laser beams;
an optical unit, comprising: a branch beam condensing lens for condensing the plurality of second laser beams at different positions in directions perpendicular to and parallel to the optical axis. A splitting characterized by splitting a first laser beam to form a plurality of second laser beams and focusing the plurality of second laser beams at different positions in directions perpendicular to and parallel to an optical axis. unit. A laser processing device for processing a workpiece,
a chuck table that holds the workpiece;
a laser beam irradiation unit for irradiating the workpiece held by the chuck table with a laser beam;
a moving unit that relatively moves the chuck table and a focus position of the laser beam emitted from the laser beam irradiation unit;
a detection unit for detecting the laser beam;
The laser beam irradiation unit includes a laser oscillator,
The detection unit is
a branching unit that branches a first laser beam emitted from the laser oscillator to form a plurality of second laser beams;
a branching beam condensing lens for condensing the plurality of second laser beams at different positions in directions perpendicular to and parallel to the optical axis;
and an imaging unit that captures the plurality of second laser beams condensed by the branched beam condensing lens to generate a captured image. A laser processing device for processing a workpiece,
a chuck table that holds the workpiece;
a laser beam irradiation unit for irradiating the workpiece held by the chuck table with a laser beam;
a moving unit that relatively moves the chuck table and a focus position of the laser beam emitted from the laser beam irradiation unit;
a detection unit for detecting the laser beam;
The laser beam irradiation unit includes a laser oscillator,
The detection unit is
A first laser beam emitted from the laser oscillator is split to form a plurality of second laser beams, and the plurality of second laser beams are focused at different positions in directions perpendicular to and parallel to the optical axis. a branching unit;
and an imaging unit configured to generate an imaged image by imaging the plurality of second laser beams condensed by the branching unit. 5. The apparatus according to claim 3, further comprising a determination unit that determines an irradiation state of the laser beam applied to the workpiece based on the captured image generated by the imaging unit. Laser processing equipment. 6. The laser processing apparatus according to claim 3, wherein said detection unit is provided adjacent to said chuck table.

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