Laser processing device and laser processing method

Abstract

A laser processing apparatus irradiates an object having a substrate and a functional element layer with a processing laser beam, the substrate including a first principal surface and a second principal surface, the functional element layer being provided on the first principal surface side of the substrate and including a metal layer, thereby forming a modified region along an imaginary plane within the functional element layer. The laser processing apparatus includes: a processing irradiation unit for irradiating the object with the processing laser beam from the second principal surface side; an observation irradiation unit for irradiating the object with observation light transmitted through the substrate from the second principal surface side; a moving mechanism; a focus position acquisition unit for acquiring the position of the observation irradiation unit and / or the support unit in the thickness direction when the observation light is focused on the metal layer as a focal position of the metal layer; and a processing position setting unit for setting the position of the processing irradiation unit and / or the support unit in the thickness direction when the modified region is formed as a laser processing position, based on the focal position of the metal layer acquired by the focus position acquisition unit.

Description

Technical Field

[0001] The present invention relates to a laser processing device and a laser processing method. Background Art

[0002] As an example of a conventional laser processing device, Japanese Patent No. 5025876 describes a device for forming a modified region within an object to be processed. The laser processing device described in Japanese Patent No. 5025876 includes: a stage on which the object to be processed is mounted; an observation light source that emits illumination light; a laser light source that emits laser light; a focusing lens that focuses the illumination light on the surface of the object to be processed and the laser light on the interior of the object to be processed; and an imaging unit that captures the reflected light of the illumination light focused on the surface of the object to obtain imaging data. In the laser processing device described in Japanese Patent No. 5025876, after moving at least one of the stage and the focusing lens based on the imaging data so that the focal point of the illumination light is located on the surface of the object to be processed, the stage and the focusing lens are then moved in the thickness direction of the object to be processed with reference to the surface so that the focal point of the laser light is located within the object to be processed. Summary of the Invention

[0003] In recent years, laser processing devices have sometimes irradiated an object, including a substrate having a second principal surface that includes a first principal surface and a second principal surface opposite to the first principal surface, and a functional element layer including a metal layer disposed on the first principal surface side of the substrate, with a processing laser from the second principal surface side, thereby forming a modified region within the functional element layer along an imaginary surface. In this case, when forming the modified region using the aforementioned conventional technology, at least one of the mounting table and the focusing lens is moved in the thickness direction relative to the laser incident surface (the second principal surface) of the substrate. Consequently, if the substrate thickness varies, the position of the laser light focal point in the thickness direction (the position where the modified region is formed) may vary due to this influence, potentially deteriorating the processing quality.

[0004] Therefore, an object of the present invention is to provide a laser processing apparatus and a laser processing method capable of performing laser processing while suppressing the influence of variations in substrate thickness.

[0005] A laser processing device according to one aspect of the present invention irradiates an object having a substrate and a functional element layer with a processing laser, wherein the substrate includes a first main surface and a second main surface on the opposite side of the first main surface, the functional element layer is arranged on the first main surface side of the substrate and includes a metal layer, and a modified region is formed along an imaginary surface inside the functional element layer. The laser processing device includes: a supporting portion supporting the object; a processing irradiation portion irradiating the object with a processing laser from the second main surface side; an observation irradiation portion irradiating the object with observation transmitted light through the substrate from the second main surface side; a moving mechanism for moving at least any one of the supporting portion, the processing irradiation portion and the observation irradiation portion in the thickness direction of the object; a focus position acquisition portion for obtaining the position of the observation irradiation portion and / or the supporting portion in the thickness direction when the focus of the observation transmitted light is aligned with the metal layer as the focal position of the metal layer; and a processing position setting portion for setting the position of the processing irradiation portion and / or the supporting portion in the thickness direction when the modified region is formed as the laser processing position based on the focal position of the metal layer obtained by the focus position acquisition portion.

[0006] In this laser processing device, the focal position of the metal layer is determined when the transmitted observation light is focused on the metal layer rather than the laser incident surface of the object. The laser processing position is set based on this focal position. This allows the laser processing position to be set without being affected by variations in substrate thickness. In other words, laser processing can be performed while minimizing the effects of variations in substrate thickness.

[0007] The laser processing apparatus of the present invention may also include a first imaging element sensitive to the observation transmitted light and receiving reflected light in response to illumination with the observation transmitted light from the observation illumination unit. In this case, the imaging results of the first imaging element can be used to move the observation illumination unit and / or the support unit in the thickness direction so that the focus of the observation transmitted light is aligned with the metal layer.

[0008] In the laser processing apparatus of the present invention, the first imaging element may also be sensitive to the processing laser light and receive reflected light in response to irradiation with the processing laser light from the processing irradiation unit. In this case, the image capture results of the first imaging element can be used to determine, for example, the beam shape of the processing laser light.

[0009] The laser processing apparatus of the present invention may also include a position alignment unit that controls the movement mechanism based on the image pickup results of the first imaging element to move the observation illumination unit and / or the support unit in the thickness direction so that the focus of the observation transmitted light is aligned with the metal layer. In this case, the observation illumination unit and / or the support unit can be automatically moved in the thickness direction so that the focus of the observation transmitted light is aligned with the metal layer.

[0010] In the laser processing apparatus of the present invention, the focal position of the metal layer may be expressed using the coordinates of the observation irradiation unit on the support portion with the thickness direction as the coordinate axis, and the laser processing position may be expressed using the coordinates of the processing irradiation unit on the support portion with the thickness direction as the coordinate axis. This allows for simple handling of the focal position of the metal layer and the laser processing position.

[0011] The laser processing apparatus of the present invention may also include a storage unit that stores a predetermined reference focal position serving as a reference value for the focal position of the metal layer and a predetermined reference processing position serving as a reference value for the laser processing position. The processing position setting unit calculates the difference between the focal position of the metal layer obtained by the focal position obtaining unit and the reference focal position, and sets the laser processing position based on the difference and the reference processing position. In this case, the laser processing position can be easily set.

[0012] In the laser processing apparatus of the present invention, the processing position setting unit may set the laser processing position by adding or subtracting the reference processing position according to the difference or a correction value of the difference. In this case, the laser processing position can be set simply and accurately.

[0013] In the laser processing apparatus of the present invention, the reference processing position may be the center value of a processing margin range. The processing margin range is defined as the range of movement within which processing quality is maintained above a certain level when the processing irradiation unit and / or support unit are moved so that the focal point of the processing laser light moves in the thickness direction around the periphery of the imaginary surface. In this case, using a focusing unit with a low numerical aperture (NA) as the focusing unit for the processing laser light can provide a wider processing margin range.

[0014] The laser processing apparatus of the present invention may also include a laser processing execution unit that uses a moving mechanism to position a processing irradiation unit at a laser processing position set by a processing position setting unit, and irradiates an object with a processing laser from the processing irradiation unit, thereby forming a modified region within the functional element layer. In this case, formation of the modified region within the functional element layer can be specifically achieved.

[0015] In the laser processing apparatus of the present invention, the modified region may be formed so as to extend over a portion or the entire region of the functional element layer when viewed in the thickness direction. In this case, the modified region formed over a portion or the entire region of the functional element layer when viewed in the thickness direction can be used to remove the object.

[0016] The laser processing apparatus of the present invention may also include a laser processing head comprising a processing irradiation unit and an observation irradiation unit, wherein the laser processing head coaxially emits a processing laser beam and transmitted light for observation. In this case, the processing irradiation unit and the observation irradiation unit can be integrally formed into a laser processing head, and the processing laser beam and transmitted light for observation can be coaxially emitted from the laser processing head.

[0017] The laser processing apparatus of the present invention may also include a laser processing head comprising a processing irradiation unit and an observation irradiation unit, wherein the laser processing head emits the processing laser light and the observation transmitted light coaxially. In this case, the processing irradiation unit and the observation irradiation unit can be integrally formed into the laser processing head, and the processing laser light and the observation transmitted light can be emitted coaxially from the laser processing head.

[0018] The laser processing apparatus of the present invention may also include: a laser processing head constituting a processing irradiation unit; and an observation head constituting an observation irradiation unit and being separate from the laser processing head. In this case, the processing irradiation unit and the observation irradiation unit can be configured as separate laser processing heads and observation heads, respectively, with the processing laser light and observation transmitted light emitted from the laser processing head and the observation head, respectively, on different axes.

[0019] The laser processing apparatus of the present invention may also include a second imaging element sensitive to the processing laser light and receiving reflected light in response to irradiation with the processing laser light from the processing irradiation unit. In this case, the imaging results of the second imaging element can be used to determine, for example, the beam shape of the processing laser light.

[0020] The laser processing method of the present invention irradiates a processing laser on an object having a substrate and a functional element layer, wherein the substrate includes a first main surface and a second main surface on the opposite side of the first main surface, the functional element layer is arranged on the first main surface side of the substrate and includes a metal layer, and a modified area is formed along an imaginary surface inside the functional element layer. The laser processing method includes: a step of supporting the object using a support part; a step of irradiating the object with a processing laser from the second main surface side using a processing irradiation part; a step of irradiating the object with observation transmitted light through the substrate from the second main surface side using an observation irradiation part, and receiving reflected light reflected corresponding to the irradiation of the observation transmitted light using a first camera element; a step of moving the observation irradiation part and / or the support part in the thickness direction of the object based on the shooting result of the first camera element, and obtaining the position of the observation irradiation part and / or the support part in the thickness direction when the focus of the observation transmitted light is aligned with the metal layer as the focal position of the metal layer; and a step of setting the position of the processing irradiation part and / or the support part in the thickness direction when the modified area is formed as the laser processing position based on the obtained focal position of the metal layer.

[0021] In this laser processing method, the focal position of the metal layer is determined when the transmitted observation light is focused on the metal layer rather than the laser incident surface of the object. This metal layer focal position is used as a reference to set the laser processing position. This allows the laser processing position to be set without being affected by variations in substrate thickness. In other words, laser processing can be performed while minimizing the effects of variations in substrate thickness.

[0022] The laser processing method of the present invention may also include a reference value obtaining step for obtaining a reference focal position serving as a reference value of the focal position of the metal layer and a reference value obtaining step for obtaining a reference processing position serving as a reference value of the laser processing position, wherein the reference value obtaining step includes: a step for supporting an object for reference setting by using a supporting portion; a step for irradiating the object for reference setting with observation transmitted light from the second main surface side, receiving reflected light reflected corresponding to the irradiation of the observation transmitted light by using a first imaging element, moving the observation irradiation portion and / or the supporting portion in the thickness direction based on the shooting result of the first imaging element, and obtaining the position of the observation irradiation portion and / or the supporting portion in the thickness direction when the focus of the observation transmitted light is aligned with the metal layer as the reference focal position; and a step for irradiating the object for reference setting with a processing laser from the second main surface side by changing the position of the processing irradiation portion and / or the supporting portion in the thickness direction, and obtaining the reference processing position based on its processing quality and the position of the processing irradiation portion and / or the supporting portion, and in the step for setting the laser processing position, obtaining the difference between the obtained metal layer focal position and the reference focal position, and setting the laser processing position based on the difference and the reference processing position. In this case, the laser processing position can be easily set using the reference focus position and the reference processing position. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram showing a laser processing apparatus according to the first embodiment.

[0024] Figure 2 These are top views and cross-sectional views of an object.

[0025] Figure 3 This is a cross-sectional view showing a part of the object in an enlarged manner.

[0026] Figure 4 This is a flowchart showing the steps for obtaining a reference value.

[0027] Figure 5 This is a flowchart showing the interlayer peeling process.

[0028] Figure 6 (a) is a schematic cross-sectional view of an object for explaining a reference value acquisition step. Figure 6 (b) means Figure 6 A subsequent diagram of (a).

[0029] Figure 7 (a) means Figure 6 (b) A subsequent diagram. Figure 7 (b) means Figure 7 A subsequent diagram of (a).

[0030] Figure 8 (a) is a schematic cross-sectional view of an object for explaining delamination processing. Figure 8 (b) means Figure 8 A subsequent diagram of (a).

[0031] Figure 9 (a) is a schematic cross-sectional view for explaining a general object to be laser-processed. Figure 9 (b) is a schematic cross-sectional view for explaining a general object to be laser-processed.

[0032] Figure 10 It is a structural diagram showing a laser processing apparatus according to a second embodiment.

[0033] Figure 11 It is a structural diagram showing a laser processing apparatus according to a third embodiment.

[0034] Figure 12 It is a structural diagram showing an observation head according to a modified example of the third embodiment.

[0035] Figure 13 It is a structural diagram showing a laser processing apparatus according to a fourth embodiment.

[0036] Figure 14 This is an enlarged cross-sectional view showing a portion of an object according to a modified example.

[0037] Figure 15 (a) is a plan view and a cross-sectional view of an object for explaining a first example of forming a modified region in a partial region of a functional element layer. Figure 15 (b) is a plan view and a cross-sectional view of an object for explaining a second example of forming a modified region in a partial region of a functional element layer.

[0038] Figure 16 (a) is a top view and a cross-sectional view of an object for explaining a third example of forming a modified region in a partial region of a functional element layer. Figure 16 (b) is a plan view and a cross-sectional view of an object for explaining a fourth example of forming a modified region in a partial region of a functional element layer. DETAILED DESCRIPTION

[0039] Hereinafter, the embodiment will be described in detail with reference to the accompanying drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and repeated descriptions are omitted.

[0040] [First embodiment]

[0041] The first embodiment will be described. Figure 1 The laser processing apparatus 1 shown is an apparatus for forming a modified region on an object 10 by irradiating the object 10 with a laser beam (processing laser beam) L. In the following description, three mutually orthogonal directions are referred to as the X, Y, and Z directions. In this embodiment, the X direction is a first horizontal direction, the Y direction is a second horizontal direction perpendicular to the first horizontal direction, and the Z direction is a vertical direction. The Z direction corresponds to the thickness direction of the object 10.

[0042] like Figure 2 and Figure 3 As shown, the object 10 includes a first substrate 11, a functional element layer 12, and a second substrate 13. The first substrate 11, the functional element layer 12, and the second substrate 13 are arranged so as to be stacked in this order in the Z direction.

[0043] The first substrate 11 and the second substrate 13 are wafers formed into a circular plate shape. The first substrate 11 and the second substrate 13 are, for example, semiconductor substrates such as silicon substrates, piezoelectric material substrates formed of piezoelectric materials, and glass substrates formed of glass. Notches or orientation planes indicating crystal orientation may also be provided on the first substrate 11 and the second substrate 13. The first substrate 11 includes a surface (first main surface) 11a and a back surface (second main surface) 11b on the opposite side of the surface 11a. The second substrate 13 includes a surface 13a and a back surface 13b on the opposite side of the surface 13a. Here, the first substrate 11 and the second substrate 13 are arranged in a direction in which the surfaces 11a and 13a are opposite to each other.

[0044] The functional element layer 12 is provided on the surface 11a side of the first substrate 11. The functional element layer 12 is provided on the surface 13a side of the second substrate 13. The functional element layer 12 includes a plurality of functional elements. Each functional element may be, for example, a wiring element, a light-receiving element such as a photodiode, a light-emitting element such as a laser diode, a circuit element such as a memory, or the like. Each functional element may be three-dimensionally stacked with multiple layers, or arranged in a matrix. The functional element layer 12 here includes a plurality of metal layers 12a and a plurality of non-metal layers 12b, which are stacked in the Z direction.

[0045] The metal layer 12a includes a Ti (titanium) layer and a Sn (tin) layer, for example. The non-metal layer 12b includes, for example, an oxide film layer and a nitride film layer. The non-metal layer 12b includes, for example, a SiO (silicon monoxide) layer and a SiCN (silicon carbonitride) layer. The metal layer 12a and the non-metal layer 12b are formed on the surfaces 11a and 13a by, for example, film formation (sputtering, vapor deposition, or CVD), etching (dry etching or wet etching), and polishing.

[0046] A virtual surface M1 is set on the object 10 as a predetermined peeling surface. The virtual surface M1 is a surface where a modified area is predetermined to be formed. The virtual surface M1 is a surface opposite to the back surface 11b of the object 10, which is the laser incident surface. The virtual surface M1 is a surface parallel to the back surface 11b, for example, in a circular shape. The virtual surface M1 is a virtual area and is not limited to a plane. It can also be a curved surface or a three-dimensional surface. The setting of the virtual surface M1 can be performed by the user via an operation input unit (not shown). The virtual surface M1 can also be a surface with specified coordinates.

[0047] like Figure 1 As shown, the laser processing apparatus 1 of this embodiment aligns the focusing point (at least a part of the focusing area) with the object 10 and irradiates the object 10 with the laser light L, thereby forming a laser beam along the imaginary plane M1 (refer to FIG. Figure 2 ) forms a modified region. The laser processing device 1 performs laser processing including lift-off processing on the object 10. The lift-off processing is a process for lifting off a portion of the object 10. The laser processing device 1 has a function as a laser lift-off device. The position of the imaginary surface M1 (i.e., the position where the modified region is formed) is a position in the functional element layer 12 that does not include the metal layer 12a (i.e., includes only the non-metal layer 12b) on the laser incident side.

[0048] The laser processing device 1 includes a support unit 2, a laser processing head 3, a moving mechanism 4, a control unit 5, and a display unit 6. The support unit 2 supports an object 10, for example, by suction. The support unit 2 is movable in the X, Y, and Z directions. In this embodiment, the object 10 is placed on the support unit 2 with the back surface 11b positioned upward, serving as the laser incident surface. The support unit 2 has a rotation axis extending in the Z direction and is rotatable about this rotation axis.

[0049] The laser processing head 3 includes a processing light source 31, an observation light source 32, a focusing unit 33, and a first imaging element 34. The processing light source 31 emits processing laser light L, for example, by pulse oscillation. The laser light L is a laser light having a wavelength region that is absorptive to the functional element layer 12. For example, a solid-state pulse laser device is used as the processing light source 31, and the wavelength of the laser light L is 355 nm. The observation light source 32 emits observation transmission light L0 that is transmitted through the first substrate 11. The observation transmission light L0 is light having a wavelength region that is transparent to the first substrate 11. The observation light source 32 is not particularly limited, and various light sources can be used as long as they can emit the observation transmission light L0.

[0050] The focusing section 33 focuses the laser light L and the observation transmitted light L0 on the object 10 supported by the support section 2. In this embodiment, the laser light L emitted from the processing light source 31 is reflected by the dichroic mirror H1 and enters the focusing section 33. In addition, the observation transmitted light L0 emitted from the observation light source 32 is reflected by the dichroic mirror H2 and passes through the dichroic mirror H1 and enters the focusing section 33. The focusing section 33 focuses the laser light L and the observation transmitted light L0 thus incident on the object 10. The focusing section 33 is configured to include, for example, a lens unit composed of a plurality of focusing lenses. As the lens unit of the focusing section 33, a lens unit with a low NA (numeric aperture) can be used. In addition, the focusing section 33 may have a driving mechanism such as a piezoelectric element that drives the lens unit in the Z direction, or it may not have it. As examples of low NA, 0.1 to 0.4 can be cited.

[0051] The first imaging element 34 is sensitive to the observation transmitted light L0. The first imaging element 34 receives reflected light in response to the irradiation of the observation transmitted light L0 (the condensation of the observation transmitted light L0 by the condensing unit 33 onto the object 10). In this embodiment, the reflected light of the observation transmitted light L0 that irradiates the object 10 and is reflected by the metal layer 12a of the functional element layer 12 is detected by the first imaging element 34 via the condensing unit 33 and the dichroic mirrors H1 and H2. For example, the first imaging element 34 captures an image of the metal layer 12a formed by the observation transmitted light L0 as an image.

[0052] The first imaging element 34 is also sensitive to the laser light L. It also receives reflected light in response to the irradiation of the laser light L (the focusing of the laser light L by the focusing unit 33 on the object 10). In this embodiment, the reflected light of the laser light L that is irradiated and reflected by the object 10 is detected by the first imaging element 34 via the focusing unit 33 and the dichroic mirrors H1 and H2. For example, the first imaging element 34 captures an image related to the beam shape of the laser light L as an image. The first imaging element 34 outputs the imaged result to the control unit 5.

[0053] The laser processing head 3 coaxially emits laser light L and observation light L0. The laser processing head 3 comprises a processing irradiation unit that irradiates the object 10 with laser light L from the back surface 11b, and an observation irradiation unit that irradiates the object 10 with observation light L0 from the back surface 11b. The laser processing head 3 may or may not include a spatial light modulator for modulating the laser light L.

[0054] The moving mechanism 4 includes a mechanism that moves at least one of the support portion 2 and the laser processing head 3 in the X direction, the Y direction, and the Z direction. The moving mechanism 4 drives at least one of the support portion 2 and the laser processing head 3 by the driving force of a known driving device such as a motor, so that the focal point of the laser light L moves in the X direction, the Y direction, and the Z direction. The moving mechanism 4 drives at least one of the support portion 2 and the laser processing head 3 by the driving force of a known driving device such as a motor, so that the focus of the observation transmitted light L0 moves in the Z direction. In addition, the moving mechanism 4 includes a mechanism that rotates the support portion 2 around the rotation axis. The moving mechanism 4 rotationally drives the support portion 2 by the driving force of a known driving device such as a motor, so that the focal point of the laser light L moves in the θ direction around the rotation axis. There is no particular limitation as the moving mechanism 4, and various known mechanisms can be used.

[0055] The control unit 5 controls the operation of each component of the laser processing apparatus 1. The control unit 5 is configured as a computer device including a processor, memory, storage, and communication equipment. In the control unit 5, the processor executes software (programs) loaded into the memory, etc., controlling the reading and writing of data from the memory and storage devices, as well as communication via the communication equipment. The control unit 5 includes a focus position acquisition unit 51, a processing position setting unit 52, a storage unit 53, and a laser processing execution unit 54.

[0056] The focus position acquisition unit 51 acquires the position of the laser processing head 3 in the Z direction when the observation transmitted light L0 is focused on the metal layer 12a as the metal layer focus position (hereinafter referred to as the "metal layer focus position"). The metal layer focus position is represented by the Z coordinate (the coordinate of the coordinate axis in the Z direction) of the laser processing head 3 on the support unit 2. For example, in the image of the metal layer 12a based on the observation transmitted light L0 displayed on the display unit 6, when the metal layer 12a is in focus, the focus position acquisition unit 51 acquires the Z direction position of the laser processing head 3 at that time as the metal layer focus position.

[0057] The processing position setting unit 52 sets the position of the laser processing head 3 in the Z direction when the modified region is formed by focusing the laser light L as a laser processing position (hereinafter referred to as the "laser processing position"), based on the focal position of the metal layer obtained by the focal position obtaining unit 51. The laser processing position is represented by the Z coordinate of the laser processing head 3 on the support unit 2. Specifically, the processing position setting unit 52 calculates the difference between the focal position of the metal layer obtained by the focal position obtaining unit 51 and the reference focal position stored in the storage unit 53. Then, the processing position setting unit 52 sets the laser processing position based on the calculated difference and the reference processing position stored in the storage unit 53. As an example, the processing position setting unit 52 sets the Z coordinate obtained by adding or subtracting the reference processing position according to the correction value of the difference as the laser processing position.

[0058] The storage unit 53 is, for example, a hard disk, and stores various data. The storage unit 53 stores a reference focal position, which is preset as a reference value for the focal position of the metal layer, and a reference processing position, which is preset as a reference value for the laser processing position. The reference processing position is the center of the processing margin, which is the central value of the processing margin range. The processing margin range is the range of movement when the laser processing head 3 and / or the support unit 2 is moved so that the focal point of the laser L moves in the Z direction around the imaginary surface M1, and the processing quality reaches a certain level or above (details will be described later). The processing margin range is also called the processing process window.

[0059] The laser processing execution unit 54 uses the moving mechanism 4 to position the laser processing head 3 at the laser processing position set by the processing position setting unit 52, and then irradiates the object 10 with laser light L from the laser processing head 3 in a manner that focuses on the functional element layer 12. When the laser light L focuses inside the functional element layer 12, the laser light L is absorbed in the portion corresponding to the focal point of the laser light L, forming a modified region. The modified region is an area whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding non-modified area. Examples of the modified region include a melt-processed region, a crack region, a dielectric breakdown region, and a refractive index change region. The modified region includes multiple modified points and cracks extending from the multiple modified points.

[0060] The laser processing execution unit 54 uses the movement mechanism 4 to move at least one of the support unit 2 and the laser processing head 3 while irradiating the laser light L from the laser processing head 3 so that the focal point of the laser light L moves along the imaginary plane M1. For example, the laser processing execution unit 54 controls the movement of the laser processing head 3 in the X and / or Y directions while rotating the support unit 2.

[0061] The display unit 6 is, for example, a monitor. The display unit 6 is controlled by the control unit 5 and displays the image capture results of the first imaging element 34. The display unit 6 displays an image of the metal layer 12a based on the observation transmitted light L0. By confirming whether the metal layer 12a displayed on the display unit 6 is in focus, it is possible to confirm whether the focus of the observation transmitted light L0 is on the metal layer 12a. The display unit 6 displays an image of the beam shape of the laser light L. By confirming whether the beam shape displayed on the display unit 6 is minimized, the position of the focal point of the laser light L can be confirmed. The display unit 6 is not particularly limited, and various known display devices can be used.

[0062] Next, a description will be given of a laser processing method using the laser processing apparatus 1. Here, an example of interlayer delamination processing in which the object 10 is delaminated at the functional element layer 12 using the laser processing apparatus 1 will be described.

[0063] The laser processing method of this embodiment irradiates an object 10 with laser light L to form a modified region along an imaginary plane M1 within a functional element layer 12. In the laser processing method of this embodiment, a reference value acquisition step is first performed as a pre-processing step to acquire a reference focal position and a reference processing position before performing interlayer delamination processing on a production object 10B.

[0064] In the benchmark value acquisition step, if Figure 4 As shown, the object 10 for reference setting is mounted on the support 2, and the object 10A for reference setting is supported on the support 2 (step S1). In step S1, the object 10A is placed on the support 2 with the back surface 11b of the first substrate 11 facing the laser incident surface.

[0065] Obtain the reference focus position (step S2). In step S2, the laser processing head 3 irradiates the object 10A with the observation transmission light L0 from the back side 11b, and the first imaging element 34 receives the reflected light corresponding to the irradiation of the observation transmission light L0 (refer to FIG. Figure 6 (a)). The image (image result) of the metal layer 12a captured by the first imaging element 34 is displayed on the display unit 6. The laser processing head 3 is moved in the Z direction by the moving mechanism 4. The in-focus position of the metal layer 12a displayed on the display unit 6, i.e., the Z coordinate of the laser processing head 3 when the observation transmitted light L0 is in focus on the metal layer 12a, is obtained as the reference focal position. The obtained reference focal position is stored in the storage unit 53.

[0066] Obtain the machining margin range (step S3). In step S3, first, the laser machining head 3 is moved in the Z direction (see FIG. 1 ) by the moving mechanism 4 so that the focal point of the laser L is located on the imaginary surface M1. Figure 6 (b)). After that, the Z coordinate of the laser processing head 3 is changed and the laser L is irradiated on the object 10A from the back side 11b, and this is repeated multiple times. Based on the processing quality at this time and the Z coordinate of the laser processing head 3, a processing margin range is obtained. For example, in the laser processing performed by gradually increasing and decreasing the Z coordinate of the laser processing head 3 from the position of the imaginary surface M1, a set of Z coordinates of the laser processing head 3 when the processing quality is above a certain level is obtained as a processing margin range KM (refer to Figure 7 (a) and Figure 7 (b) The processing quality being above a certain level is synonymous with the situation where there is no influence on the processing quality. By displaying the image of the functional element layer 12 captured by the first imaging element 34 during or after laser processing on the display unit 6, the processing quality can be grasped from the image.

[0067] The margin center, which is the central value of the machining margin range KM, is acquired as a reference machining position and stored in the storage unit 53 (step S4). The object 10A is removed from the support unit 2, and the reference value acquisition step is completed (step S5).

[0068] Incidentally, in step S3, the positional relationship between the Z coordinate of the laser processing head 3 and the focal point of the laser light L may be pre-stored in the storage unit 53, and the laser processing head 3 may be moved in the Z direction based on this positional relationship. The positional relationship between the Z coordinate of the laser processing head 3 and the focal point of the laser light L may be pre-stored in the storage unit 53, for example, as follows. Specifically, an image of the beam shape of the laser light L on the back surface 11b is captured by the first imaging element 34 and displayed on the display unit 6. The laser processing head 3 is moved in the Z direction by the moving mechanism 4 so as to minimize the beam shape (minimize the beam diameter). The positional relationship between the Z coordinate of the laser processing head 3 and the back surface 11b at this time may be pre-stored in the storage unit 53 as the positional relationship between the Z coordinate of the laser processing head 3 and the focal point of the laser light L.

[0069] Next, proceed Figure 5 In the interlayer delamination process, the object 10B for production is mounted on the support 2, and the object 10B is supported by the support 2 (step S11). In step S11, the object 10B is placed on the support 2 with the back surface 11b of the first substrate 11 facing the laser incident surface.

[0070] The focus position of the metal layer is obtained (step S12). In step S12, the laser processing head 3 irradiates the object 10B with the observation light L0 from the back side 11b, and the first imaging element 34 receives the reflected light corresponding to the irradiation of the observation light L0 (refer to FIG. Figure 8 (a)). The display unit 6 displays an image (image result) of the metal layer 12a captured by the first imaging element 34. The moving mechanism 4 moves the laser processing head 3 in the Z direction, and the in-focus position of the metal layer 12a displayed on the display unit 6, i.e., the Z coordinate of the laser processing head 3 when the observation transmitted light L0 is in focus on the metal layer 12a, is obtained as the metal layer focal position. The obtained metal layer focal position is stored in the storage unit 53.

[0071] The laser processing position is set based on the obtained focal position of the metal layer. That is, for example, according to the following formula (1), the difference between the focal position of the metal layer obtained in step S12 and the reference focal position stored in the storage unit is calculated (step S13). Then, for example, according to the following formula (2), the laser processing position is set based on the difference and the reference processing position (step S14). α and β are correction coefficients when correction is required. When correction is not required, α=1 and β=0. α and β can be predetermined based on known technology from at least any one of experimental, empirical and theoretical viewpoints.

[0072] Difference = metal layer focal position - reference focal position (1)

[0073] Laser processing position = reference processing position + (α × difference + β) (2)

[0074] Laser processing is performed (step S15). In step S15, the laser processing head 3 irradiates the object 10B with laser light L from the back surface 11b side of the first substrate 11 (see Figure 8 (b)). The laser processing head 3 is moved in the Z direction by the moving mechanism 4 so that the laser processing head 3 is located at the set laser processing position. In this state, the laser processing head 3 irradiates the object 10B with laser light L from the back surface 11b of the first substrate 11, so that the laser light L is focused on the functional element layer 12. While the laser processing head 3 is irradiating with laser light L, the support portion 2 is rotated while controlling the movement of the laser processing head 3 in the X direction and / or Y direction so that the focal point of the laser light L moves along the imaginary plane M1. As a result, a modified region is formed inside the functional element layer 12 along the imaginary plane M1. Here, the modified region is formed so as to extend over the entire area of ​​the functional element layer 12 when viewed from the Z direction.

[0075] Thereafter, the object 10B is removed from the support 2 (step S16 ). Thereafter, the delamination process is performed on the second and subsequent objects 10B in the same manner as in the above-described steps S11 to S16 , or the delamination process is terminated.

[0076] However, in general laser processing, e.g. Figure 9 As shown in (a), when forming a modified region on the object 10, the laser processing head 3 (light-converging portion 33) is moved in the Z direction by a predetermined amount H, based on the Z coordinate of the laser processing head 3 (light-converging portion 33) when the focus of the illumination light L1 is located at the back surface 11b of the first substrate 11, which is the laser incident surface. Figure 9 As shown in (b), when the thickness of the first substrate 11 varies (thicker in the figure), the position of the focal point of the laser L in the Z direction and even the formation position of the modified region vary, which may deteriorate the processing quality.

[0077] In this regard, in the laser processing apparatus 1 and the laser processing method of the present embodiment, the focal position of the metal layer is obtained when the focus of the observation transmitted light L0 is not on the back surface 11b of the first substrate 11 but on the metal layer 12a, and the laser processing position is set based on this metal layer focal position. As a result, even if the first substrate 11 becomes thicker or thinner, the laser processing position can be set without being affected. In addition, even if the second substrate 13 becomes thicker or thinner, the laser processing position can be set without being affected. There is no need to know the thickness of the first and second substrates 11 and 13. In other words, laser processing can be performed while suppressing the influence of variations in the substrate thickness of the first and second substrates 11 and 13.

[0078] This embodiment includes a first imaging element 34. The first imaging element 34 is sensitive to the observation transmitted light L0 and receives reflected light from the observation transmitted light L0. In this case, the image captured by the first imaging element 34 can be used to move the laser processing head 3 in the Z direction so that the observation transmitted light L0 is focused on the metal layer 12a.

[0079] In this embodiment, the first imaging element 34 is also sensitive to the laser light L and receives the reflected light of the laser light L. In this case, the beam shape of the laser light L can be grasped as described above using the imaging result of the first imaging element 34 .

[0080] In this embodiment, the metal layer focal position and the laser processing position are expressed as Z coordinates, thereby making it possible to easily handle the metal layer focal position and the laser processing position.

[0081] In this embodiment, a reference focal position and a reference processing position are stored, the difference between the metal layer focal position and the reference focal position is calculated, and the laser processing position is set based on this difference and the reference processing position. This method makes it possible to easily set the laser processing position. This method is made possible by using a low-NA focusing unit 33 for focusing the observation transmitted light L0 and the laser light L, thereby reducing the influence of aberrations caused by transmission through the first substrate 11 and the non-metallic layer 12b.

[0082] In this embodiment, the value obtained by adding or subtracting the correction value of the difference between the metal layer focal position and the reference focal position from the reference processing position is set as the laser processing position. In this case, the laser processing position can be set simply and accurately.

[0083] In this embodiment, the reference processing position is the center value of the processing margin range KM. In this case, by using the low NA focusing portion 33 as the focusing portion of the laser light L, the focal spot size becomes larger at a low NA, so a wider processing margin range KM can be obtained.

[0084] In this embodiment, the laser processing head 3 is positioned at the laser processing position set by the processing position setting unit 52 using the moving mechanism 4, and the laser processing head 3 irradiates the object 10 with laser light L, thereby forming a modified region within the functional element layer 12. This specifically enables formation of a modified region along the imaginary plane M1 within the functional element layer 12.

[0085] In this embodiment, the modified region is formed so as to extend over the entire functional element layer 12 as viewed from the Z direction. In this case, the modified region formed over a portion or the entire functional element layer 12 can be used to delaminate the object 10.

[0086] The laser processing device 1 of this embodiment includes a laser processing head 3, from which laser light L and observation transmitted light L0 are coaxially emitted. In this case, the processing irradiation unit and the observation irradiation unit can be integrally formed as the laser processing head 3, and the laser light L and the observation transmitted light L0 can be coaxially emitted. This simplifies the device structure.

[0087] The laser processing method of this embodiment includes a reference value acquisition step for acquiring a reference focal position and a reference processing position. In the reference value acquisition step, an object 10A for reference setting is supported, and observation transmitted light L0 is irradiated toward the object 10A from the back surface 11b. The reflected light is received by the first imaging element 34. Based on the image captured by the first imaging element 34, the laser processing head 3 is moved in the Z direction to acquire the reference focal position. The position of the laser processing head 3 in the Z direction is changed, and laser light L is irradiated toward the object 10A from the back surface 11b. The reference processing position is acquired based on the processing quality and the Z coordinate of the laser processing head 3. Subsequently, when setting the laser processing position, the difference between the metal layer focal position and the reference focal position is calculated, and the laser processing position is set based on this difference and the reference processing position. This allows for simple setting of the laser processing position using the reference focal position and the reference processing position.

[0088] [Second embodiment]

[0089] The second embodiment will be described. In the description of the second embodiment, points different from the first embodiment will be described, and duplicate descriptions will be omitted.

[0090] like Figure 10As shown, the laser processing device 101 of the second embodiment differs from the first embodiment in that the laser processing head 3 further includes a second imaging element 35. The second imaging element 35 is also sensitive to the laser light L and receives reflected light corresponding to the irradiation of the laser light L. In this embodiment, the reflected light of the laser light L irradiated and reflected by the object 10 is detected by the second imaging element 35 via the focusing unit 33 and the dichroic mirrors H1, H2, and H3. For example, the second imaging element 35 captures an image of the beam shape of the laser light L as an image. The second imaging element 35 outputs the imaged result to the control unit 5. In addition, the first imaging element 34 of this embodiment does not need to be sensitive to the laser light L. The display unit 6 can also display the imaged result of the second imaging element 35.

[0091] As described above, the laser processing apparatus 101 and the laser processing method of this embodiment can also perform laser processing while suppressing the influence of variations in the thickness of the first and second substrates 11 and 13. Furthermore, since the laser processing apparatus 101 includes the second imaging element 35, the beam shape of the laser light L and the like can be grasped using the image pickup results of the second imaging element 35.

[0092] [Third embodiment]

[0093] The third embodiment will be described. In the description of the third embodiment, points different from the first embodiment will be described, and duplicate descriptions will be omitted.

[0094] like Figure 11 As shown, the laser processing device 201 of the third embodiment replaces the laser processing head 3 (see Figure 1 ) is different from the first embodiment in that it includes a laser processing head 3A and an observation head 3B.

[0095] The laser processing head 3A includes a processing light source 31, a focusing unit 33A, and a second imaging element 35. The focusing unit 33A focuses the laser light L on the object 10 supported by the support unit 2. In this embodiment, the laser light L emitted from the processing light source 31 is reflected by the dichroic mirror H1 and enters the focusing unit 33A. The focusing unit 33A focuses the laser light L thus entered on the object 10. The focusing unit 33A is configured to include, for example, a lens unit composed of a plurality of focusing lenses. As the lens unit of the focusing unit 33A, a low NA lens unit can be used. The second imaging element 35 is also sensitive to the laser light L and also receives reflected light reflected in response to the irradiation of the laser light L. For example, the second imaging element 35 obtains an image of the beam shape of the laser light L as an image. The second imaging element 35 outputs the shooting result to the control unit 5.

[0096] The observation head 3B includes an observation light source 32, a focusing unit 33B, and a first imaging element 34. The focusing unit 33B focuses the observation transmitted light L0 onto the object 10 supported by the support unit 2. In this embodiment, the observation transmitted light L0 emitted from the observation light source 32 is reflected by the dichroic mirror H2 and enters the focusing unit 33B. The focusing unit 33B focuses the thus-entered observation transmitted light L0 onto the object 10. Similar to the focusing unit 33A, the focusing unit 33B is configured to include a lens unit composed of, for example, a plurality of focusing lenses.

[0097] As described above, the laser processing head 3A and the observation head 3B are constructed as separate components, emitting laser light L and observation transmitted light L0, respectively. The laser processing head 3A constitutes a processing irradiation unit that irradiates the object 10 with laser light L from the back surface 11b, while the observation head 3B constitutes an observation irradiation unit that irradiates the object 10 with observation transmitted light L0 from the back surface 11b. The laser processing head 3A may or may not include a spatial light modulator for modulating the laser light L.

[0098] The moving mechanism 4 of this embodiment may enable the laser processing head 3A and the observation head 3B to move independently in the Z direction, or may enable the laser processing head 3A and the observation head 3B to move integrally in the Z direction.

[0099] As described above, the laser processing apparatus 201 and the laser processing method of this embodiment can also perform laser processing while suppressing the influence of variations in the thickness of the first and second substrates 11 and 13. Furthermore, the processing irradiation unit and the observation irradiation unit can be configured as separate components, namely the laser processing head 3A and the observation head 3B, respectively, and the laser light L and the observation transmitted light L0 can be emitted from the laser processing head 3A and the observation head 3B, respectively, on different axes.

[0100] Figure 12 3B is a structural diagram showing a modified example of the third embodiment. Figure 12 As shown, the observation head 3B may include multiple light-collecting sections 33B and multiple first imaging elements 34. The magnifications of the lens units included in the multiple light-collecting sections 33B may be different from each other. In this case, the light-collecting section 33B including the lens unit with the highest magnification among the multiple light-collecting sections 33B may be used to collect the observation transmitted light L0 on the object 10.

[0101] [Fourth embodiment]

[0102] The fourth embodiment will be described. In the description of the fourth embodiment, points different from the first embodiment will be described, and duplicate descriptions will be omitted.

[0103] like Figure 13As shown, the laser processing device 301 of the fourth embodiment replaces the laser processing head 3 (see Figure 1 ) is different from the first embodiment in that it includes a laser processing head 303.

[0104] The laser processing head 303 includes a processing light source 31, a focusing unit 333A, a first imaging element 34, an observation light source 32, a focusing unit 333B, and a second imaging element 35. The focusing unit 333A focuses laser light L onto the object 10 supported by the support unit 2. In this embodiment, the laser light L emitted from the processing light source 31 is reflected by the dichroic mirror H1 and enters the focusing unit 333A. The focusing unit 333A focuses the incident laser light L onto the object 10. The focusing unit 333A is configured to include, for example, a lens unit composed of a plurality of focusing lenses. A low NA lens unit can be used as the lens unit of the focusing unit 333A.

[0105] The focusing section 333B focuses the observation transmitted light L0 on the object 10 supported by the support section 2. In the present embodiment, the observation transmitted light L0 emitted from the observation light source 32 is reflected by the dichroic mirror H2 and enters the focusing section 333B. The focusing section 333B focuses the observation transmitted light L0 thus incident on the object 10. The focusing section 33B is configured similarly to the focusing section 333A to include a lens unit including, for example, a plurality of focusing lenses. The second imaging element 35 is also sensitive to the laser light L and receives reflected light corresponding to the irradiation of the laser light L. For example, the second imaging element 35 obtains an image of the beam shape of the laser light L as an image. The second imaging element 35 outputs the captured image result to the control section 5.

[0106] The laser processing head 303 emits laser light L and observation light L0 on different axes. The laser processing head 303 comprises a processing irradiation unit that irradiates the object 10 with laser light L from the back surface 11b, and an observation irradiation unit that irradiates the object 10 with observation light L0 from the back surface 11b. The laser processing head 303 may or may not include a spatial light modulator for modulating the laser light L.

[0107] As described above, the laser processing apparatus 301 and the laser processing method of this embodiment can also perform laser processing while suppressing the influence of variations in the thickness of the first and second substrates 11 and 13. Furthermore, the processing irradiation unit and the observation irradiation unit can be integrally configured as the laser processing head 303, and the laser light L and the observation transmitted light L0 can be emitted from the laser processing head 303 on different axes.

[0108] [Modification]

[0109] One embodiment of the present invention is not limited to the above-mentioned embodiment.

[0110] In the above embodiment, the object 10 includes the first substrate 11 and the second substrate 13, but the present invention is not limited thereto. Figure 14 As shown, the object 10 may not have the second substrate 13. In the above embodiment, the correction coefficients α and β are used to correct the laser processing position, but this correction does not have to be performed. In the above embodiment, the linear function shown in the above formula (2) is used to correct the laser processing position, but an n-order function (n is an integer greater than 2) may be used to correct the laser processing position. The first imaging element 34 of the above embodiment may not have sensitivity to the laser light L.

[0111] In the above embodiment, the control unit 5 may also include a position alignment unit that controls the moving mechanism 4 based on the image capture results of the first imaging element 34 to move the laser processing head 3, 3A, 303 and the observation head 3B in the Z direction so that the focus of the observation transmitted light L0 is aligned with the metal layer 12a. In this case, the laser processing head 3, 3A, 303 and the observation head 3B can be automatically moved in the Z direction so that the focus of the observation transmitted light L0 is aligned with the metal layer 12a.

[0112] In the above embodiment, the laser processing head 3, 3A, 303 and the observation head 3B are moved in the Z direction by the moving mechanism 4. However, instead of or in addition to this, the support unit 2 may be moved in the Z direction by the moving mechanism 4. In the above embodiment, the focusing units 33, 33A, 33B, 333A, 333B may be configured to include, for example, a single lens instead of a lens unit.

[0113] In the above embodiment, an imaginary plane M1 extending over the entire area of ​​the functional element layer 12 when viewed from the Z direction is set, and a modified region is formed so as to extend over the entire area of ​​the functional element layer 12 (whole-surface interlayer delamination processing). However, this is not limiting. An imaginary plane extending over a portion of the functional element layer 12 when viewed from the Z direction may also be set, and a modified region may be formed so as to extend over a portion of the functional element layer 12. In this case, interlayer delamination of the object 10 can be performed using the modified region formed in a portion of the functional element layer 12.

[0114] For example, Figure 15 As shown in (a), it is also possible to set an imaginary surface M2 extending at the periphery of the functional element layer 12 when viewed from the Z direction, so as to form a modified region (peripheral interlayer peeling processing) in a manner extending at the periphery of the functional element layer 12. Figure 15 As shown in (b), a virtual plane M3 extending in the inner peripheral portion of the functional element layer 12 is set when viewed from the Z direction, and a modified region is formed so as to extend in the inner peripheral portion of the functional element layer 12 (inner peripheral layer delamination processing).

[0115] In addition, it is also possible, for example, Figure 16 As shown in (a), a virtual plane M4 of an arcuate shape is set when viewed from the Z direction, and a modified region is formed in such a way that a part of the arcuate shape in the functional element layer 12 is expanded (local interlayer peeling processing). Figure 16 As shown in (b), a virtual plane M5 is set as a partially expanded virtual plane sandwiched by a pair of arches in a circle when viewed from the Z direction, and a modified region is formed so that the partially expanded virtual plane M5 in the functional element layer 12 is expanded (partial delamination processing).

[0116] In the above embodiment, the type of object 10, the shape of the object 10, the size of the object 10, the number and direction of the crystal orientation of the object 10, and the plane orientation of the main surface of the object 10 are not particularly limited. In the above embodiment, the object 10 can be formed by including a crystalline material having a crystalline structure, or can be formed by including an amorphous material having an amorphous structure (amorphous structure) instead of or in addition to it. The crystalline material can be either an anisotropic crystal or an isotropic crystal. For example, the object 10 can also include a substrate formed of at least any one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), LiTaO3, diamond, GaOx, sapphire (Al2O3), gallium arsenide, indium phosphide, glass, and alkali-free glass.

[0117] In the above-described embodiment, the modified region may be, for example, a crystallized region, a recrystallized region, or a gettering region formed within the object 10. The crystallized region is a region that maintains the structure of the object 10 before processing. The recrystallized region is a region that solidifies as a single crystal or polycrystalline when temporarily evaporated, plasma-formed, or melted and then resolidified. The gettering region is a region that exerts a gettering effect by collecting and capturing impurities such as heavy metals and can be formed continuously or intermittently. The above-described embodiment can also be applied to processes such as ablation.

[0118] The structures in the above-mentioned embodiments and modified examples are not limited to the above-mentioned materials and shapes, and various materials and shapes can be applied. In addition, the structures in the above-mentioned embodiments or modified examples can be arbitrarily applied to the structures in other embodiments or modified examples.

[0119] According to the present invention, it is possible to provide a laser processing apparatus and a laser processing method capable of suppressing the influence of variations in substrate thickness.

Claims

1. A laser processing device, characterized in that: Irradiating an object having a substrate and a functional element layer with a processing laser, the substrate including a first main surface and a second main surface opposite to the first main surface, the functional element layer being provided on the first main surface side of the substrate and including a metal layer, and forming a modified region along an imaginary surface within the functional element layer. The laser processing device comprises: a support portion for supporting the object; a processing irradiation unit for irradiating the object with the processing laser light from the second main surface side; an observation irradiation section for irradiating the object with observation transmission light transmitted through the substrate from the second main surface side; a moving mechanism for moving at least any one of the support portion, the processing irradiation portion, and the observation irradiation portion in the thickness direction of the object; a focus position acquiring unit that acquires the position of the observation irradiation unit and / or the support unit in the thickness direction when the focus of the observation transmitted light is aligned with the metal layer as a focus position of the metal layer; and The processing position setting unit sets the position of the processing irradiation unit and / or the support unit in the thickness direction when forming the modified region as a laser processing position based on the focal position of the metal layer obtained by the focal position obtaining unit.

2. The laser processing device according to claim 1, wherein: The first imaging element is provided, which has sensitivity to the observation transmitted light and receives reflected light reflected in response to irradiation of the observation transmitted light from the observation irradiation unit.

3. The laser processing device according to claim 2, wherein: The first imaging element is also sensitive to the processing laser light, and receives reflected light reflected in response to irradiation with the processing laser light from the processing irradiation section.

4. The laser processing device according to claim 2 or 3, wherein: A position aligning unit is included that controls the moving mechanism based on the imaging result of the first imaging element to move the observation illumination unit and / or the support unit in the thickness direction so that the focus of the observation transmitted light is aligned with the metal layer.

5. The laser processing device according to any one of claims 1 to 4, wherein: The focal position of the metal layer is represented by the coordinates of the observation irradiation portion on the support portion with the thickness direction as the coordinate axis. The laser processing position is expressed by the coordinates of the processing irradiation portion on the support portion with the thickness direction being a coordinate axis.

6. The laser processing device according to any one of claims 1 to 5, wherein: A storage unit is provided for storing a predetermined reference focal position as a reference value of the focal position of the metal layer and a predetermined reference processing position as a reference value of the laser processing position. The processing position setting unit obtains a difference between the metal layer focal position acquired by the focal position acquisition unit and the reference focal position, and sets the laser processing position based on the difference and the reference processing position.

7. The laser processing device according to claim 6, wherein: The processing position setting unit sets a value obtained by adding or subtracting the reference processing position according to the difference or a correction value of the difference as the laser processing position.

8. The laser processing device according to claim 6 or 7, wherein: The reference machining position is the center value of the machining allowance range. The processing margin range is a range of movement in which the processing quality becomes greater than a certain level when the processing irradiation unit and / or the support unit are moved so that the focal point of the processing laser light moves in the thickness direction around the virtual surface.

9. The laser processing device according to any one of claims 1 to 8, wherein: It includes a laser processing execution unit, which uses the moving mechanism to position the processing irradiation unit at the laser processing position set by the processing position setting unit, and irradiates the object with the processing laser from the processing irradiation unit, thereby forming the modified area inside the functional element layer.

10. The laser processing device according to any one of claims 1 to 9, wherein: The modified region is formed so as to extend over a portion or the entire region of the functional element layer when viewed in the thickness direction.

11. The laser processing device according to any one of claims 1 to 10, characterized in that: including a laser processing head constituting the processing irradiation section and the observation irradiation section, The laser processing head coaxially emits the processing laser light and the observation transmitted light.

12. The laser processing device according to any one of claims 1 to 10, wherein: including a laser processing head constituting the processing irradiation section and the observation irradiation section, The laser processing head emits the processing laser light and the observation transmitted light in a coaxial manner.

13. The laser processing device according to any one of claims 1 to 10, wherein: include: a laser processing head constituting the processing irradiation section; and An observation head constitutes the observation irradiation section and is separate from the laser processing head.

14. The laser processing device according to any one of claims 1 to 13, wherein: A second imaging element is provided that is sensitive to the processing laser light and receives reflected light reflected in response to irradiation with the processing laser light from the processing irradiation portion.

15. A laser processing method, characterized in that: Irradiating an object having a substrate and a functional element layer with a processing laser, the substrate including a first main surface and a second main surface opposite to the first main surface, the functional element layer being provided on the first main surface side of the substrate and including a metal layer, and forming a modified region along an imaginary surface within the functional element layer. The laser processing method comprises: a step of supporting the object by using a supporting portion; irradiating the object with the processing laser beam from the second main surface side using a processing irradiation unit; a step of irradiating the object with observation transmission light transmitted through the substrate from the second main surface side by an observation irradiation unit, and receiving reflected light reflected in response to the irradiation with the observation transmission light by a first imaging element; a step of moving the observation illumination unit and / or the support unit in the thickness direction of the object based on the imaging result of the first imaging element, and obtaining the positions of the observation illumination unit and / or the support unit in the thickness direction when the focus of the observation transmitted light is aligned with the metal layer as the focal position of the metal layer; and The step of setting the position of the processing irradiation portion and / or the support portion in the thickness direction when forming the modified region as a laser processing position based on the obtained focal position of the metal layer.

16. The laser processing method according to claim 15, wherein: The method comprises the steps of obtaining a reference focus position as a reference value of the focus position of the metal layer and a reference processing position as a reference value of the laser processing position, The reference value acquisition step includes: a step of supporting the object for reference setting by the supporting portion; a step of irradiating the object for reference setting with the observation transmitted light from the second main surface side, receiving reflected light reflected in response to the irradiation with the observation transmitted light using a first imaging element, moving the observation irradiation portion and / or the supporting portion in the thickness direction based on a result of imaging by the first imaging element, and obtaining the position of the observation irradiation portion and / or the supporting portion in the thickness direction when the focus of the observation transmitted light is aligned with the metal layer as the reference focal position; and The step of irradiating the object for reference setting with the processing laser from the second main surface side by changing the position of the processing irradiation portion and / or the support portion in the thickness direction, and obtaining the reference processing position based on the processing quality and the position of the processing irradiation portion and / or the support portion, In the step of setting the laser processing position, a difference between the acquired focal position of the metal layer and the reference focal position is obtained, and the laser processing position is set based on the difference and the reference processing position.

Images