Laser processing apparatus

Abstract

To provide a laser processing device in which a reticle can be easily installed.SOLUTION: A laser processing device 1 comprises: a stage 2 which supports an object 20; a light source 31 which outputs laser light L; a laser light condensing lens 33 which condenses the laser light L on the object 20; a first reticle R2 which has a first pattern PA; an illumination light source R1 which irradiates the first reticle R2 with illumination light Li; a first projection optical system which projects the first pattern PA on the object 20 by forming a projection image of the first reticle R2 on the object 20 with the illumination light Li passing through the first reticle R2; and a camera 35 which acquires a first pattern image Im1 by capturing an image of the first pattern PA projected to the object 20. The first pattern PA has such a shape that does not have the dependence on the rotation angle of the first reticle R2 around an optical axis of the illumination light Li.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a laser processing apparatus.

Background Art

[0002] Patent Document 1 describes a laser dicing apparatus. This laser dicing apparatus includes a stage for moving a wafer, a laser head for irradiating the wafer with laser light, and a control unit for controlling each part. The laser head has a laser light source for emitting processing laser light for forming a modified region inside the wafer, a dichroic mirror and a condenser lens sequentially arranged on the optical path of the processing laser light, and an AF device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when performing laser processing by irradiating an object with laser light, height setting may be performed to align the condensing position of the laser light with one surface which is the incident surface of the laser light on the object. In one step of height setting, it is conceivable to project the pattern of the reticle onto the surface of the object by irradiating the reticle with illumination light, and detect the in-focus position of the pattern as one surface of the object.

[0005] Here, generally, as the pattern of the reticle, one including a cross shape extending in two directions intersecting the optical axis of the illumination light is used. In this case, if there is variation in the installation angle of the reticle around the optical axis of the illumination light, the posture of the pattern projected onto the surface of the object also varies. This variation in the posture of the pattern is also visually recognized by the user by imaging and displaying a pattern image including the image of the pattern. Further, this pattern image is also used for image processing during detection of the surface of the object or the like. As a result, even when the variation in the posture of the reticle pattern does not directly affect the laser processing, there is a possibility of giving the user a sense of discomfort or increasing the time required for detecting the reticle pattern by image processing. For this reason, precise and complex adjustment is required for the installation of the reticle so that such variation in the posture of the pattern does not occur.

[0006] An object of the present disclosure is to provide a laser processing apparatus capable of easily installing a reticle.

Means for Solving the Problems

[0007] A laser processing apparatus according to the present disclosure is a laser processing apparatus for forming a modified region on an object by irradiating the object with laser light, including a support unit for supporting the object, a laser light source for outputting laser light, a first condenser lens for condensing the laser light on the object supported by the support unit, a first reticle having a first pattern projected onto the object, an illumination light source for irradiating the first reticle with illumination light, and a first projection optical system for projecting the first pattern onto the object by forming an image of the projected image of the first reticle on the object with the illumination light that has passed through the first reticle, a first camera for imaging the image of the first pattern projected onto the object to obtain a first pattern image, and a display unit for displaying the first pattern image, wherein the first pattern has a shape that does not have a dependency on the rotation angle of the first reticle around the optical axis of the illumination light.

[0008] This laser processing apparatus includes an illumination light source that irradiates illumination light onto a first reticle, separately from a laser light source for performing laser processing. Therefore, when performing a high set, while irradiating the first reticle with illumination light, an image of the first reticle is formed on an object by the illumination light that has passed through the first reticle by a projection optical system, so that a first pattern can be projected onto the object. Thus, if the first pattern projected onto the object is imaged, it is possible to detect the laser light incident surface of the object using the first pattern image obtained by the imaging. Here, the first pattern does not have a dependency on the rotation angle of the first reticle around the optical axis of the illumination light. For this reason, regardless of the rotation angle of the first reticle around the optical axis, the posture of the first pattern projected onto the object (the posture within the first pattern image) does not change. For this reason, even if there is a variation in the installation angle of the first reticle around the optical axis of the illumination light, it does not give the user a sense of discomfort or increase the time required for pattern detection of the first reticle by image processing. Therefore, when installing the first reticle, adjustment of the rotation angle around the optical axis of the illumination light becomes unnecessary. As a result, in this laser processing apparatus, the installation of the first reticle is facilitated.

[0009] In the laser processing apparatus according to the present disclosure, the first projection optical system may include a first condenser lens for forming an image of the first pattern by the illumination light on the object, and the first camera may acquire the first pattern image by detecting the illumination light incident from the object through the first condenser lens. In this case, in the projection optical system for projecting the first pattern of the first reticle, the first condenser lens for condensing the laser light on the object is shared, and the number of components is reduced.

[0010] In the laser processing apparatus according to the present disclosure, the first reticle includes a transmissive portion that transmits illumination light and a first pattern that forms a shadow on the object by having a lower transmittance of the illumination light than the transmissive portion when viewed from the optical axis direction of the illumination light. The first pattern includes at least one circle centered on the optical axis. In the first reticle, a circular area including the pattern center is the transmissive portion when viewed from the optical axis direction, and the pattern center may be set to the center of the field angle of the first camera. As described above, when the first condenser lens is shared in the projection optical system, the reflected light of the laser light together with the illumination light enters the first camera through the first condenser lens. Therefore, a spot of the laser light appears in the first pattern image acquired by the first camera. Therefore, by making the pattern center of the first pattern the transmissive portion so that no shadow is formed and the center of the field angle of the first camera, it is possible to confirm the optical axis deviation of the laser light by comparing the position of the pattern center with the position of the spot of the laser light.

[0011] The laser processing apparatus according to the present disclosure includes at least a first condenser lens, a first reticle, an illumination light source, a first projection optical system, and a first Z-axis moving unit that moves a laser processing head including a first camera along the Z direction intersecting the laser light incident surface of the object, and a first control unit that controls the first Z-axis moving unit so that the image of the first pattern matches the laser light incident surface based on the image processing of the first pattern image. In this case, based on the image processing of the first pattern image, it is possible to adjust the position of the laser processing head in the Z direction. In particular, as described above, in this laser processing apparatus, the posture of the first pattern (the posture in the first pattern image) projected onto the object does not change regardless of the rotation angle around the optical axis of the first reticle. Therefore, it is possible to avoid the lengthening of the image processing time due to the variation in the posture of the first pattern.

[0012] The laser processing apparatus according to the present disclosure includes an observation device for observing an object. The observation device includes a transmission light source that outputs transmission light having transparency to the object, a second condenser lens for condensing the transmission light on the object, a second reticle that is disposed on the optical path of the transmission light between the transmission light source and the second condenser lens and has a second pattern projected onto the object, a second projection optical system that includes the second condenser lens and forms an image of the projection image of the second reticle on the object with the transmission light that has passed through the second reticle, thereby projecting the second pattern onto the object, and a second camera that acquires an observation image of the object by the transmission light and a second pattern image including an image of the second pattern by detecting the transmission light incident from the object through the second condenser lens. The second pattern may have a shape that does not depend on the rotation angle of the second reticle around the optical axis of the transmission light. In this case, the laser processing apparatus is provided with an observation device for observing the object, and for this observation device as well, a second reticle is provided on the optical path of the transmission light for observing the object. And the second pattern of the second reticle projected onto the object does not depend on the rotation angle of the second reticle around the optical axis of the transmission light. Therefore, the posture of the second pattern projected onto the object (the posture within the second pattern image) does not change regardless of the rotation angle of the second reticle around the said optical axis. Therefore, even if there is a variation in the installation angle of the second reticle around the optical axis of the transmission light, it will not give the user a sense of discomfort or increase the time required for pattern detection of the second reticle by image processing. Thus, when installing the second reticle, adjustment of the rotation angle around the optical axis of the transmission light becomes unnecessary. In this way, in this laser processing apparatus, the second reticle of the observation device can also be easily installed.

[0013] In the laser processing apparatus according to the present disclosure, the observation apparatus includes at least an observation unit including a transmission light source, a second condenser lens, a second reticle, a second projection optical system, and a second camera, a second Z-axis moving unit that moves the observation unit along the Z direction intersecting the transmission light incident surface of the object, and a second control unit that controls the second Z-axis moving unit based on the image processing of the second pattern image so that the image of the second pattern matches the transmission light incident surface and / or the surface on the opposite side of the transmission light incident surface of the object. In this case, based on the image processing of the second pattern image, the position adjustment in the Z direction of the observation unit can be performed. In particular, as described above, in this laser processing apparatus, regardless of the rotation angle around the optical axis of the second reticle, the posture of the second pattern projected onto the object (the posture in the second pattern image) does not change. Therefore, the lengthening of the image processing due to the variation in the posture of the second pattern can be avoided.

Effect of the Invention

[0014] According to the present disclosure, a laser processing apparatus in which a reticle can be easily installed can be provided.

Brief Description of the Drawings

[0015]

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DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments will be described in detail with reference to the drawings. In the description of each figure, the same or corresponding parts may be denoted by the same reference numerals, and redundant descriptions may be omitted. In addition, each figure may show an orthogonal coordinate system defined by the X-axis, Y-axis, and Z-axis. As an example, the X direction and the Y direction are the first horizontal direction and the second horizontal direction that intersect (are orthogonal) to each other, and the Z direction is the vertical direction that intersects (is orthogonal) to the X direction and the Y direction.

[0017] As shown in FIG. 1, the laser processing apparatus 1 according to the present embodiment includes a stage (support portion) 2, a laser processing head 3, alignment cameras 5 and 6, an internal observation unit 4, a first vertical movement mechanism 7A, a second vertical movement mechanism 7B, a first horizontal movement mechanism 8A, a second horizontal movement mechanism 8B, a control unit 9, and a GUI (Graphical User Interface) 10. The laser processing apparatus 1 is an apparatus that forms a modified region 12 (see FIG. 4) in the object 20 by irradiating the object 20 with the laser beam L. Further, the laser processing apparatus 1 also functions as an observation apparatus for observing the object 20. In the present embodiment, the laser processing apparatus 1 further includes an observation apparatus.

[0018] As shown in FIGS. 2 and 3, the object 20 is, for example, a wafer. The object 20 includes a semiconductor substrate 21 and a functional element layer 22. The semiconductor substrate 21 has a front surface 21a and a back surface 21b. The semiconductor substrate 21 is, for example, a silicon substrate. The functional element layer 22 is formed on the front surface 21a of the semiconductor substrate 21. The functional element layer 22 includes a plurality of functional elements 22a arranged two-dimensionally along the front surface 21a. The functional elements 22a are, for example, light receiving elements such as photodiodes, light emitting elements such as laser diodes, circuit elements such as memories, and the like. The functional elements 22a may be three-dimensionally configured with a plurality of layers stacked. Note that the object 20 may or may not have the functional element layer 22 and may be a bare wafer. A notch 21c indicating the crystal orientation is provided in the semiconductor substrate 21, but an orientation flat may be provided instead of the notch 21c.

[0019] The object 20 is cut for each functional element 22a along each of the plurality of lines 15. The plurality of lines 15 pass between each of the plurality of functional elements 22a when viewed from the thickness direction of the object 20. More specifically, the line 15 passes through the center (center in the width direction) of the street region 23 when viewed from the thickness direction of the object 20. The street region 23 extends through between adjacent functional elements 22a in the functional element layer 22. In the present embodiment, the plurality of functional elements 22a are arranged in a matrix along the surface 21a, and the plurality of lines 15 are set in a grid pattern. Note that the line 15 is a virtual line, but may be an actually drawn line.

[0020] As shown in FIG. 1, the object 20 is placed on the stage 2. The stage 2 supports the object 20, for example, by adsorbing the object 20. The stage 2 is movable along the X direction by the first horizontal movement mechanism 8A. The stage 2 is movable along the Y direction by the second horizontal movement mechanism 8B. The stage 2 is configured to be rotatable about a rotation axis along the Z direction. The stage 2 has a known rotation driving device (not shown) such as a motor, and is rotationally driven about the rotation axis by the driving force thereof. The rotation of the stage 2 (operation of the rotation driving device) is controlled by the control unit 9.

[0021] As shown in FIGS. 1 and 4, the laser processing head 3 irradiates the object 20 supported by the stage 2 with the laser beam L having transparency. The laser processing head 3 condenses the laser beam L inside the object 20. When the laser beam L is condensed inside the object 20 supported by the stage 2, the laser beam L is particularly absorbed in the portion corresponding to the condensing position (at least a part of the condensing region) of the laser beam L, and the modified region 12 is formed inside the object 20.

[0022] The modified region 12 is a region where the density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding unmodified regions. Examples of the modified region 12 include a melting treatment region, a crack region, a dielectric breakdown region, a refractive index change region, and the like. The modified region 12 has the property that cracks tend to extend from the modified region 12 to the incident side and the opposite side of the laser beam L. Such properties of the modified region 12 are utilized for cutting the object 20.

[0023] The laser processing head 3 has a laser beam condensing lens (first condensing lens) 33 and a camera (first camera) 35 in a housing H3. A laser beam L is incident into the housing H3 of the laser processing head 3 from an external light source 31. The light source (laser light source) 31 outputs the laser beam L, for example, by a pulse oscillation method. The laser beam condensing lens 33 condenses the laser beam L onto the object 20 supported on the stage 2. Further, the laser beam condensing lens 33 forms an image of a first pattern PA by illumination light Li described later on the object 20. In the laser processing head 3, the laser beam L incident from the light source 31 is incident on the laser beam condensing lens 33 through a dichroic mirror 32 in the housing H3, and is condensed onto the object 20 by the laser beam condensing lens 33. The laser beam condensing lens 33 may be a lens unit including a plurality of objective lenses. The housing H3 includes a mounting portion 39 provided on its side surface, and is connected and supported to a first vertical movement mechanism 7A described later through this mounting portion 39.

[0024] The laser processing head 3 has an AF unit 36 in the housing H3. The AF unit 36 is a unit for finely adjusting the distance between the laser beam condensing lens 33 and the back surface (laser beam incident surface) 21b of the object 20. The AF unit 36 acquires height (position in the Z direction) data of the back surface 21b of the object 20 by detecting the reflected light of the AF laser beam Lm irradiated onto the object 20 coaxially with the laser beam L. The control unit 9 can control the actuator 33a of the laser beam condensing lens 33 based on the height data acquired by the AF unit 36 so that, for example, the distance between the laser beam condensing lens 33 and the back surface 21b of the object 20 becomes constant.

[0025] The laser processing head 3 has an illumination light source R1 inside the housing H3. The illumination light source R1 outputs illumination light Li that is visible light. The illumination light Li output from the illumination light source R1 is reflected by a half mirror 37 coaxially with the AF laser light Lm via a mirror R4a and a dichroic mirror R4b and enters a laser light condensing lens 33. As a result, the illumination light Li irradiates the object 20 coaxially with the AF laser light Lm and the laser light L. The reflected light of the illumination light Li irradiated on the object 20 enters the camera 35 via the laser light condensing lens 33, the half mirror 37, and a lens 38. As a result, the camera 35 can image an image of the object 20 by the illumination light Li.

[0026] The laser processing head 3 has a first reticle R2 and a lens R3 that are sequentially arranged on the optical path of the illumination light Li inside the housing H3. The first reticle R2 is irradiated with the illumination light Li. In other words, the illumination light source R1 irradiates the first reticle R2 with the illumination light Li. The first reticle R2 has a pattern (details will be described later with reference to FIG. 6) that forms a shadow of the illumination light Li. The first reticle R2, the object 20, the lens R3, and the laser light condensing lens 33 constitute a 4f optical system, and by forming an image of the projection image of the first reticle R2 on the object 20 with the illumination light Li that has passed through the first reticle R2, the pattern of the first reticle R2 is projected onto the object 20 (constituting a first projection optical system).

[0027] As a result, the camera 35 can image an image of the reticle pattern projected on the object 20 and acquire a first pattern image. That is, the camera 35 acquires the first pattern image by detecting the illumination light Li that has entered via the laser light condensing lens 33. The first pattern image acquired by the camera 35 can be displayed on the GUI10. That is, the GUI10 is also a display unit that displays the first pattern image. Note that the camera 35 is not particularly limited, and various known cameras can be used as long as the required performance is satisfied.

[0028] The alignment cameras 5 and 6 acquire information used for aligning the condensing position of the laser beam L on the object 20 (hereinafter also simply referred to as "alignment"). The alignment cameras 5 and 6 irradiate the object 20 with light and detect the light returning from the object 20 to acquire an image as information used for alignment. The alignment cameras 5 and 6 image the object 20 supported on the stage 2 with light transmitted through the object 20.

[0029] For example, the alignment camera 5 irradiates the object 20 with light from the back surface 21b side, which is the laser beam incident surface, and images the functional element layer 22 by detecting the light returning from the front surface 21a (functional element layer 22). Also, for example, the alignment camera 5 similarly irradiates the object 20 with light from the back surface 21b side and acquires an image of the region including the modified region 12 by detecting the light returning from the formation position of the modified region 12 in the semiconductor substrate 21. These images are used for alignment. The alignment camera 6 has the same configuration as the alignment camera 5 except that its lens has a lower magnification. The alignment camera 6 is used for alignment in the same manner as the alignment camera 5.

[0030] The alignment cameras 5 and 6 are provided on the laser processing head 3 and move integrally with the laser processing head 3. In the illustrated example, the alignment cameras 5 and 6 are fixed to the mounting portion 39 of the laser processing head 3. The alignment cameras 5 and 6 are connected to the control unit 9. The alignment cameras 5 and 6 output the captured images to the control unit 9. The alignment cameras 5 and 6 are not particularly limited, and various known cameras can be used as long as they satisfy the required performance.

[0031] As shown in FIGS. 1 and 5, the internal observation unit 4 is for observing the inside of the object 20 with transmitted light that is transmissive to the object 20. The internal observation unit 4 irradiates the object 20 with transmitted light and observes the inside of the object 20 by detecting the transmitted light, reflected light, and scattered light returning from the object 20. For example, the internal observation unit 4 images the modified region 12 formed in the object 20 and the tip of the crack 14 extending from the modified region 12.

[0032] As shown in FIG. 5, the internal observation unit 4 includes a transmitted light source 41, a half mirror 42, a transmitted light condenser lens (second condenser lens) 43, and a camera (second camera) 44 in a housing H4. The transmitted light source 41 outputs transmitted light I1 that is transmissive to the object 20 (semiconductor substrate 21). The transmitted light source 41 is composed of, for example, a halogen lamp and a filter, an LED, etc., and outputs transmitted light I1 in the near-infrared region. The transmitted light I1 output from the transmitted light source 41 is reflected by the half mirror 42, passes through the transmitted light condenser lens 43, and is irradiated onto the object 20 from the back surface 21b side of the semiconductor substrate 21. The transmitted light condenser lens 43 is a lens that condenses the transmitted light I1 onto the semiconductor substrate 21. The transmitted light condenser lens 43 allows the transmitted light I1 reflected by the semiconductor substrate 21 to pass through.

[0033] The camera 44 detects the transmitted light I1 that has passed through the transmitted light condenser lens 43 and the half mirror 42. The camera 44 is composed of, for example, an InGaAs camera and has sensitivity to the transmitted light I1 in the near-infrared region. The housing H4 includes a mounting portion 49 provided on its side surface, and is connected and supported to a second vertical movement mechanism 7B described later via this mounting portion 49. The internal observation unit 4 is connected to the control unit 9. The internal observation unit 4 outputs the captured image (internal image) to the control unit 9. The image can be displayed on the GUI 10. The internal observation unit 4 is not particularly limited, and various known cameras can be used as long as the required performance is satisfied.

[0034] The internal observation unit 4 has, within the housing H4, a second reticle Q2 and a lens Q3 that are sequentially arranged on the optical path of the transmitted light l1 between the transmitted light source 41 and the transmitted light condenser lens 43. The second reticle Q2 is irradiated with the transmitted light l1. In other words, the transmitted light source 41 irradiates the second reticle Q2 with the transmitted light l1. The second reticle Q2 has a pattern (details will be described later with reference to FIG. 6) that forms a shadow of the transmitted light l1. The second reticle Q2, the object 20, the lens Q3, and the transmitted light condenser lens 43 constitute a 4f optical system, and by forming an image of the projection image of the second reticle Q2 on the object 20 with the transmitted light l1 that has passed through the second reticle Q2, the pattern of the second reticle Q2 is projected onto the object 20 (constituting a second projection optical system).

[0035] More specifically, the lens Q3 transfers the image of the second reticle Q2 and forms an image on the object 20 via the transmitted light condenser lens 43. The camera 44 can acquire an observation image of the object 20 by the transmitted light l1 and a second pattern image including an image of the pattern of the second reticle Q2 by detecting the transmitted light l1 that enters from the object 20 via the transmitted light condenser lens 43.

[0036] As shown in FIG. 1, the first vertical movement mechanism 7A is a mechanism that moves the laser processing head 3 along the Z direction together with the alignment cameras 5 and 6. That is, the first vertical movement mechanism 7A is a first Z-axis moving unit that moves the laser processing head 3 including at least the laser light condenser lens 33, the first reticle R2, the illumination light source R1, the first projection optical system (the lens R3 and the laser light condenser lens 33), and the camera 35 along the Z direction intersecting the laser light incident surface of the object 20.

[0037] The first vertical movement mechanism 7A has a first vertical axis 71 provided on a columnar base 75. The first vertical axis 71 is provided on one side of the base 75 in the X direction. The base 75 is fixed to, for example, an installation surface or the like. The first vertical axis 71 extends along the Z direction. An attachment portion 39 of the laser processing head 3 is movably attached to the first vertical axis 71 along the Z direction. Such a first vertical movement mechanism 7A moves the laser processing head 3 in the Z direction along the first vertical axis 71 by the driving force of a driving source (not shown). The first vertical movement mechanism 7A is not particularly limited, and various mechanisms can be used as long as the laser processing head 3 can be moved in the Z direction.

[0038] The second vertical movement mechanism 7B is a mechanism that moves the internal observation unit 4 along the Z direction. That is, the second vertical movement mechanism 7B is at least a second Z-axis moving part that moves an internal observation unit (observation unit) 4 including a transmitted light source 41, a transmitted light condenser lens 43, a second reticle Q2, a second projection optical system (lens Q3 and transmitted light condenser lens 43), and a camera 44 along the Z direction intersecting the transmitted light incident surface of the object 20.

[0039] The second vertical movement mechanism 7B has a second vertical axis 72 provided on the base 75. The second vertical axis 72 is provided on the other side of the base 75 in the X direction. That is, the first vertical axis 71 and the second vertical axis 72 are both provided on the base 75 and are arranged to face each other via the base 75. The second vertical axis 72 extends along the Z direction. An attachment portion 49 of the internal observation unit 4 is movably attached to the second vertical axis 72 along the Z direction. Such a second vertical movement mechanism 7B moves the internal observation unit 4 in the Z direction along the second vertical axis 72 by the driving force of a driving source (not shown). The second vertical movement mechanism 7B is not particularly limited, and various mechanisms can be used as long as the internal observation unit 4 can be moved in the Z direction.

[0040] The first horizontal movement mechanism 8A is a mechanism that moves the stage 2 along the X direction. The first horizontal movement mechanism 8A has, for example, a first horizontal axis 81 fixed to an installation surface or the like. The first horizontal axis 81 extends along the X direction. The stage 2 is movably attached to the first horizontal axis 81 via a second horizontal movement mechanism 8B. Such a first horizontal movement mechanism 8A moves the stage 2 and the second horizontal movement mechanism 8B along the first horizontal axis 81 in the X direction by the driving force of a driving source (not shown). The first horizontal movement mechanism 8A is not particularly limited, and various mechanisms can be used as long as the stage 2 can be moved in the X direction.

[0041] The second horizontal movement mechanism 8B is a mechanism that moves the stage 2 along the Y direction. The second horizontal movement mechanism 8B has, for example, a second horizontal axis 82 provided on the first horizontal movement mechanism 8A. The second horizontal axis 82 extends along the Y direction. The stage 2 is movably attached to the second horizontal axis 82 along the Y direction. The second horizontal axis 82 is movable along the first horizontal axis 81 together with the stage 2. Such a second horizontal movement mechanism 8B moves the stage 2 along the second horizontal axis 82 in the Y direction by the driving force of a driving source (not shown). The second horizontal movement mechanism 8B is not particularly limited, and various mechanisms can be used as long as the stage 2 can be moved in the Y direction.

[0042] The control unit 9 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like. In the control unit 9, the processor executes software (program) read into the memory or the like, and controls the reading and writing of data in the memory and the storage, as well as communication by the communication device. The control unit 9 controls various operations of the laser processing apparatus 1. The control unit 9 controls the rotation drive device of the stage 2, the laser processing head 3, the alignment cameras 5 and 6, the internal observation unit 4, the first vertical movement mechanism 7A, the second vertical movement mechanism 7B, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the GUI 10. That is, the control unit 9 is a first control unit that controls the first vertical movement mechanism 7A which is a first Z-axis movement unit, and is also a second control unit that controls the second vertical movement mechanism 7B which is a second Z-axis movement unit.

[0043] The control unit 9 executes alignment based on the information acquired by the alignment cameras 5 and 6, and executes a process of acquiring alignment information regarding the position information of the stage 2 at the time of alignment. The position information of the stage 2 is information regarding the position of the stage 2 in, for example, the X direction, the Y direction, and the θ direction (the rotation direction around the rotation axis of the stage 2).

[0044] When the control unit 9 observes the inside of the object 20 by the internal observation unit 4, it moves the stage 2 based on the alignment information and the XYθ correction information (position correction information), and executes a process of aligning the condensing position of the transmitted light I1 with the alignment position in the object 20 (the condensing position of the laser light L at the time of alignment). The XYθ correction information is information regarding the positional relationship between the internal observation unit 4 and the laser processing head 3. For example, the XYθ correction information corresponds to the difference in the X direction, Y direction, and θ direction positions of the stage 2 when the optical axis of the laser light condensing lens 33 of the laser processing head 3 is located at the center of the object 20, and the X direction, Y direction, and θ direction positions of the stage 2 when the optical axis of the transmitted light condensing lens 43 of the internal observation unit 4 is located at the center of the object 20.

[0045] The GUI 10 displays various types of information. The GUI 10 can display the first pattern image in the laser processing head 3, the second pattern image in the internal observation unit 4, the observation imaging of the internal observation unit 4, and the imaging results of the alignment cameras 5 and 6, etc. The GUI 10 includes, for example, a touch panel display. The GUI 10 receives an input from the user by an operation such as a touch by the user, and various settings regarding processing conditions and the like are inputted.

[0046] In the laser processing apparatus 1, as an example, the object 20 is irradiated with the laser beam L from the back surface 21b side of the semiconductor substrate 21, and the stage 2 is moved along the line 15, and the condensing position (condensing point) of the laser beam L with respect to the object 20 is relatively moved along the line 15, whereby a plurality of modified spots are formed so as to line up along the line 15. One modified spot is formed by the irradiation of one pulse of the laser beam L. One row of modified regions 12 is a collection of a plurality of modified spots lined up in one row. Adjacent modified spots may be connected to each other or separated from each other depending on the relative movement speed of the condensing position with respect to the object 20 and the repetition frequency of the laser beam L.

[0047] As an example, as shown in FIG. 4, two rows of modified regions 12a and 12b can be formed inside the semiconductor substrate 21 along the line 15. The two rows of modified regions 12a and 12b are adjacent to each other in the thickness direction (Z direction) of the object 20. The two rows of modified regions 12a and 12b are formed by relatively moving two condensing positions C along the line 15 with respect to the semiconductor substrate 21.

[0048] In the laser processing apparatus 1, as described above, the housing H3 of the laser processing head 3 is supported by the first vertical movement mechanism 7A so as to be movable in the Z direction. As a result, the laser processing head 3 and the alignment cameras 5 and 6 provided on the laser processing head 3 are configured to be movable in the Z direction and immovable in the X and Y directions. In the laser processing apparatus 1, as described above, the housing H4 of the internal observation unit 4 is supported by the second vertical movement mechanism 7B so as to be movable in the Z direction. As a result, the internal observation unit 4 is configured to be movable in the Z direction and immovable in the X and Y directions.

[0049] FIG. 6 is a diagram showing the reticle shown in FIGS. 4 and 5. As shown in FIG. 6, the first reticle R2 has a plate-shaped base portion B and a first pattern PA formed on the base portion B. The base portion B has at least transparency to the illumination light Li. The first pattern PA shields at least a part of the illumination light Li. That is, the first reticle R2 includes a transmission portion Pt that transmits the illumination light Li and a first pattern PA that forms a shadow on the object 20 by having a lower transmittance of the illumination light Li than the transmission portion Pt when viewed from the optical axis direction of the illumination light Li (in the illustrated state).

[0050] Thereby, by irradiating the first reticle R2 with the illumination light Li, the illumination light Li is shielded by the first pattern PA and transmitted through the transmission portion Pt, and a shadow of the shape of the first pattern PA is formed on the object 20. The relationship between the actual size of the first pattern PA and the size of the shadow of the first pattern PA on the object 20 can be arbitrarily set by the magnification of the 4f optical system (first projection optical system) constituted by the first reticle R2, the object 20, the lens R3, and the laser light condensing lens 33.

[0051] The first pattern PA has a shape that does not depend on the rotation angle of the first reticle R2 around the optical axis of the illumination light Li. That is, the first pattern PA has a shape that does not change even when the first reticle R2 is rotated around the optical axis of the illumination light Li. Here, the first pattern PA includes two concentric circles P1 and P2 with the optical axis of the illumination light Li as the pattern center Pc. A transmission part Pt is interposed between the circle P1 and the circle P2. Also, in the first reticle R2, a circular area (the area inside the circle P2) including the pattern center Pc is the transmission part Pt.

[0052] Furthermore, as shown in FIG. 7, in the first reticle R2, the pattern center Pc of the first pattern PA is set to be at the center Dc of the viewing angle of the camera 35. Note that FIG. 7 shows a state where the first pattern image Im1 captured by the camera 35 is displayed on the GUI10. On the image displayed on the GUI10, the electronic lines D1 and D2 of the camera 35 are displayed (they may not be displayed). In the camera 35, an image of the spot of the laser light L appears in the area corresponding to the transmission part Pt located at the center Dc of the viewing angle in the first pattern image Im1. Therefore, in the first pattern image Im1, it is possible to grasp the positional relationship between the image of the first pattern PA (circle P2) and the image of the spot of the laser light L.

[0053] The second reticle Q2 used in the internal observation unit 4 also has the same configuration as the first reticle R2 used in the laser processing head 3. That is, as shown in FIG. 6, the second reticle Q2 has a plate-shaped base part B and a second pattern PB formed on the base part B. The base part B has at least transparency to the transmitted light l1. The second pattern PB shields at least a part of the transmitted light l1. That is, when viewed from the optical axis direction of the transmitted light l1 (in the illustrated state), the second reticle Q2 includes a transmission part Pt that transmits the transmitted light l1 and a second pattern PB that forms a shadow on the object 20 by making the transmittance of the transmitted light l1 lower than that of the transmission part Pt.

[0054] Thus, by irradiating the transmitted light l1 onto the second reticle Q2, the transmitted light l1 is blocked in the second pattern PB, and the transmitted light l1 is transmitted through the transmission part Pt, and a shadow in the shape of the second pattern PB is formed on the object 20. The relationship between the actual size of the second pattern PB and the size of the shadow of the second pattern PB on the object 20 can be arbitrarily set by the magnification of the 4f optical system (second projection optical system) constituted by the second reticle Q2, the object 20, the lens Q3, and the transmitted light condenser lens 43.

[0055] The second pattern PB has a shape that does not depend on the rotation angle of the second reticle Q2 around the optical axis of the transmitted light l1. That is, the second pattern PB has a shape that does not change even when the second reticle Q2 is rotated around the optical axis of the transmitted light l1. Here, the second pattern PB includes two circles P1 and P2 that are concentric with each other and have the optical axis of the transmitted light l1 as the pattern center Pc. A transmission part Pt is interposed between the circle P1 and the circle P2. In the second reticle Q2, a circular area (the area inside the circle P2) including the pattern center Pc is the transmission part Pt.

[0056] Furthermore, as shown in FIG. 7, in the second reticle Q2, the pattern center Pc of the second pattern PB is set to be at the center Dc of the viewing angle of the camera 44. Note that FIG. 7 shows a state in which the second pattern image Im2 captured by the camera 44 is displayed on the GUI10. On the image displayed on the GUI10, the electronic lines D1 and D2 of the camera 44 are displayed (they may not be displayed).

[0057] Note that the first pattern PA and the second pattern PB are not limited to being composed of two concentric circles P1 and P2. For example, as shown in FIG. 8(a), the first pattern PA and the second pattern PB may be composed of a single circle P1, or as shown in FIG. 8(b), they may be composed of three concentric circles P1, P2, and P3. That is, the number of circles in the first pattern PA and the second pattern PB is arbitrary. Further, as shown in FIG. 8(c), the circle P1 may be composed of a plurality of separated regions. In this way, the first pattern PA and the second pattern PB are not limited to a continuous shape and may be a discontinuous shape. Note that the above example is an example where the first pattern PA and the second pattern PB are the same, but the first pattern PA and the second pattern PB do not have to be the same and may be different from each other.

[0058] Subsequently, an example of the operation of the laser processing apparatus 1 will be described with reference to the flowchart of FIG. 9. In the laser processing apparatus 1, first, after starting at least the apparatus on the laser processing head 3 side and performing warm-up and calibration of the apparatus, an object 20 is placed on the stage 2 using a transfer device such as a robot hand (not shown) and adsorbed on the stage 2 (step S1).

[0059] Subsequently, in the laser processing apparatus 1, the control unit 9 performs alignment (step S2). In step S2, based on the XY position information when the control unit 9 acquires an image (for example, an image of the functional element layer 22 of the object 20) acquired by the alignment camera 5 or the alignment camera 6, the control unit 9 controls the operations of the first horizontal movement mechanism 8A and the second horizontal movement mechanism 8B, and moves the stage 2 along the X direction and the Y direction so that the condensing position of the laser beam L matches the alignment position. For example, the alignment position is the processing start position (predetermined position) on the line 15 when viewed from the Z direction. Also, in step S2, the control unit 9 acquires the position information of the stage 2 at the time of alignment as alignment information.

[0060] Subsequently, the control unit 9 performs height setting on the laser processing head 3 side (step S3). In step S3, the control unit 9 controls the operation of the first vertical movement mechanism 7A based on the image of the laser light incident surface (rear surface 21b) of the object 20 by the illumination light Li acquired by the camera 35, and moves the laser processing head 3 (i.e., the laser light condensing lens 33) along the Z direction so that the condensing position of the laser light L is located on the rear surface 21b. The control unit 9 acquires the processing machine side height setting information indicating the position of the rear surface 21b in the Z direction at this time. Subsequently, the control unit 9 controls the operation of the first vertical movement mechanism 7A, and moves the laser processing head 3 along the Z direction so that the condensing position of the laser light L is located at a predetermined depth from the rear surface 21b with reference to the position at the time of height setting. Step S3 regarding this height setting will be described in detail later.

[0061] Subsequently, the control unit 9 appropriately controls the ON / OFF of the laser light L from the laser processing head 3, and the operations of the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the rotation drive device of the stage 2, and moves the stage 2 so that the condensing position of the laser light L relatively moves along the plurality of lines 15. Thereby, a modified region 12 is formed inside the object 20 along the plurality of lines 15 (step S4). After this, the control unit 9 determines whether or not the above processing has been performed for all the lines 15, and if the above processing has been performed for all the lines 15, it proceeds to internal observation.

[0062] That is, in the laser processing apparatus 1, subsequently, internal observation of the object 20 is performed. For this purpose, in the laser processing apparatus 1, after the device on the internal observation unit 4 side is started and warmed up, the control unit 9 controls the operations of the rotation drive device of the stage 2, the first horizontal movement mechanism 8A, and the second horizontal movement mechanism 8B, and moves the stage 2 so that the object 20 is positioned at the start position of internal observation by the internal observation unit 4 (step S5). In step S5, based on the alignment information acquired in step S2 above and the preset XYθ correction information, the position of the object 20 in the X direction, Y direction, and θ direction is controlled so that the optical axis of the transmitted light condensing lens 43 coincides with the alignment position of the object 20 (here, the processing start position on line 15).

[0063] Subsequently, the control unit 9 performs height setting on the internal observation unit 4 side based on the machine side height setting information acquired in step S3 (step S6). In step S6, the control unit 9 controls the operation of the second vertical movement mechanism 7B based on the image of the transmitted light incident surface (back surface 21b) of the object 20 by the transmitted light l1 acquired by the camera 44 and the machine side height setting information, and moves the internal observation unit 4 along the Z direction so that the condensing position of the transmitted light l1 is located on the back surface 21b. The control unit 9 acquires the first observation side height setting information indicating the Z direction position of the back surface 21b at this time.

[0064] Also, in step S6, the control unit 9 controls the operation of the second vertical movement mechanism 7B based on the image of the surface (front surface 21a) opposite to the transmitted light incident surface (back surface 21b) of the object 20 by the transmitted light l1 acquired by the camera 44, and moves the internal observation unit 4 along the Z direction so that the condensing position of the transmitted light l1 is located on the front surface 21a. The control unit 9 acquires the second observation side height setting information indicating the Z direction position of the front surface 21a at this time. Step S6 regarding these height settings will be described in detail later.

[0065] Subsequently, the control unit 9 performs internal observation of the object 20 by the internal observation unit 4 and acquires a plurality of internal images (step S7). In step S7, for example, at at least one location on each line 15, the following internal observation process is executed by the internal observation unit 4 under the control of the control unit 9. That is, the internal observation unit 4 is moved along the Z direction by the second vertical movement mechanism 7B, the condensing position of the transmitted light I1 is adjusted to a plurality of positions inside the object 20, and the object 20 is imaged to acquire a plurality of internal images. Information regarding the movement amount of the internal observation unit 4 is associated with each of the plurality of internal images, and this is acquired as imaging data. Acquisition of such imaging data is repeated by aligning the optical axis of the transmitted light condensing lens 43 at another location on the same line 15 or on a different line 15.

[0066] Subsequently, the control unit 9 determines the processing state based on the acquired imaging data (step S8). In step S8, as an example, the control unit 9 automatically determines (performs AI determination) which of the images of the cracks 14 in the internal images in the plurality of imaging data is relatively clear by image recognition. The control unit 9 calculates the crack position based on the movement amount when the determined internal image was taken. The crack position can be calculated, for example, by multiplying the movement amount by a preset correction coefficient. Further, the control unit 9 estimates the position of the reformed region 12 and the like based on the acquired crack position and the like. Subsequently, the control unit 9 stores the determination result determined in step S8 above in an arbitrary storage device. The control unit 9 causes the GUI 10 to display the determination result determined in step S8 above (step S9). Thus, the process ends.

[0067] Subsequently, the workpiece side height setting in step S3 above will be described. In the laser processing apparatus 1, in step S3, the control unit 9 controls the first vertical movement mechanism 7A based on the image processing of the first pattern image Im1 captured by the camera 35 so that the image of the first pattern PA matches the laser light incident surface (back surface 21b) of the object 20. First, an example in which the control unit 9 performs template matching as image processing will be described below.

[0068] As shown in FIG. 10, in this example, first, the control unit 9 sets the actuator 33a of the laser beam condensing lens 33 to be fixed at the center (step S31). Here, the actuator 33a is provided on the laser beam condensing lens 33 and is for driving the laser beam condensing lens 33 along the Z direction. The actuator 33a expands and contracts according to the magnitude of the applied drive voltage around the expansion amount when the reference voltage is applied, thereby driving the laser beam condensing lens 33 along the Z direction. In step S31, the control unit 9 fixes the expansion amount of the actuator 33a to the central value by adjusting the drive voltage applied to the actuator 33a.

[0069] Subsequently, the control unit 9 controls the operation of the first vertical movement mechanism 7A, and moves the laser processing head 3 (that is, the laser beam condensing lens 33) along the Z direction so as to reach the set Z-axis position according to the input content such as the wafer thickness (for example, the thickness of the semiconductor substrate 21) and the holding tape for holding the object 20 (step S32).

[0070] Subsequently, the control unit 9 roughly performs height adjustment using the AF unit 36 (step S33). More specifically, in step S33, based on the height data (Z-direction position data) of the back surface 21b of the object 20 obtained by the control unit 9 detecting the reflected light of the AF laser beam Lm by the AF unit 36, the control unit 9 controls the operation of the first vertical movement mechanism 7A to move the laser processing head 3 in the Z direction so that the condensing position of the laser beam L is located on the back surface 21b.

[0071] Subsequently, the control unit 9 determines whether or not the condensing position of the laser beam L can be made to substantially coincide with the back surface 21b as a result of step S33 (step S34). As a result of the determination in step S34, if the condensing position of the laser beam L cannot be made to substantially coincide with the back surface 21b (step S34: NO), the process proceeds to step S32 to move the laser processing head 3 in the Z direction to adjust the position.

[0072] As a result of the determination in step S34, when the condensing position of the laser beam L can be made to substantially coincide with the back surface 21b (step S34: YES), the control unit 9 performs template matching (step S35). In step S35, the control unit 9 outputs illumination light Li from the illumination light source R1 to project the first pattern PA of the first reticle R2 onto the object 20, and the camera 35 captures a first pattern image Im1 including an image of the first pattern PA. Subsequently, the control unit 9 uses the image of the first pattern PA as a template image and performs a full-surface scan within the first pattern image Im1 while shifting the template image. Then, the angular position in the first pattern image Im1 where the similarity to the template image is highest is set as the detection position (pixel value T(i,j)) of this first pattern image Im1.

[0073] Here, when the pattern of the reticle is a shape in which a posture change occurs when the reticle rotates around the optical axis of the illumination light Li, such as a rectangle or a cross, if a deviation occurs in the installation angle of the reticle around the optical axis of the illumination light Li, the template image also changes (becomes an inclined posture). For this reason, in a single scan within the pattern image, the template image may not be detected within the pattern image (for example, the similarity may not exceed the threshold value). In such a case, it is necessary to repeatedly perform the scan within the pattern image while gradually rotating the posture of the template image until the template image is detected.

[0074] On the other hand, the first pattern PA according to the present embodiment does not change its posture even when the first reticle R2 rotates around the optical axis of the illumination light Li. That is, even if a deviation occurs in the installation angle of the first reticle R2 around the optical axis of the illumination light Li, the template image remains unchanged. Therefore, the time related to the detection of the template image by scanning the first pattern image Im1 is constant regardless of the presence or absence and the amount of deviation of the installation angle of the first reticle R2 around the optical axis of the illumination light Li. Therefore, in the present embodiment, the process of repeatedly performing the scan while gradually rotating the posture of the template image does not intervene.

[0075] Subsequently, in step S35, this process is performed multiple times while changing the position in the Z direction, and the similarity between the template image and the detection position of each first pattern image Im1 in the Z direction is compared. Then, the control unit 9 moves the laser processing head 3 to the position where the position in the Z direction at which the first pattern image Im1 with the highest similarity is obtained coincides with the condensing position of the laser beam L on the back surface 21b (the position where the first pattern PA is in focus), and acquires the position in the Z direction at this time as the machine-side height setting information. In this way, the machine-side height setting is completed. At this time, the control unit 9 can notify the user that the height setting has been completed normally by displaying the first pattern image Im1 on the GUI.

[0076] Thereafter, the control unit 9 controls the operation of the first vertical movement mechanism 7A to move the laser processing head 3 along the Z direction so that the condensing position of the laser beam L coincides with the position (processing depth) in the Z direction where the object 20 is actually processed (step S36). Further, the control unit 9 acquires the detection value of the back surface 21b by the AF unit 36 when the condensing position of the laser beam L is adjusted to the desired processing depth (step S37), and ends the process.

[0077] Subsequently, as another example of the height setting on the processing machine side in step S3 above, the control unit 9 will explain an example where edge detection is used as image processing. As shown in FIG. 11, in this example, first, the control unit 9 receives the designation of the detection frame (step S41). As shown in FIG. 14, on the back surface 21b of the object 20, there are included a region where the functional element 22a is formed and a street region 23. Since the height is different (there is a step) between the region where the functional element 22a is formed and the street region 23, when the focus of the first pattern PA is adjusted to the street region 23, the first pattern PA becomes blurred in the region where the functional element 22a is formed. Therefore, it is desirable that the detection frame Gd be set in the street region 23. Here, the control unit 9 can receive the designation of the detection frame Gd by receiving the input from the user through the GUI 10. Alternatively, the control unit 9 may automatically set an appropriate detection frame Gd without receiving the user's input.

[0078] Subsequently, the control unit 9, in the same manner as in step S31, sets the actuator 33a of the laser light focusing lens 33 to be centered and fixed (step S42). Subsequently, the control unit 9, in the same manner as in step S32, controls the operation of the first vertical movement mechanism 7A, and moves the laser processing head 3 (that is, the laser light focusing lens 33) along the Z direction so as to reach the set Z-axis position according to the input content such as the wafer thickness (for example, the thickness of the semiconductor substrate 21) and the holding tape that holds the object 20 (step S43).

[0079] Subsequently, the control unit 9, in the same manner as in step S33, roughly adjusts the height using the AF unit 36 (step S44). Subsequently, the control unit 9 determines whether or not the focusing position of the laser beam L can be made to substantially coincide with the back surface 21b as a result of step S44 (step S45). As a result of the determination in step S45, if the focusing position of the laser beam L cannot be made to substantially coincide with the back surface 21b (step S45: NO), the process proceeds to step S43, and the laser processing head 3 is moved in the Z direction to adjust the position.

[0080] As a result of the determination in step S45, when the condensing position of the laser beam L could be made to substantially coincide with the back surface 21b (step S45: YES), the control unit 9 performs edge detection (step S46). In step S46, the control unit 9 causes the illumination light source R1 to output illumination light Li, projects the first pattern PA of the first reticle R2 onto the object 20, and acquires a first pattern image Im1 including an image of the first pattern PA by the camera 35. Subsequently, the control unit 9 detects the edge of the first pattern PA in an area corresponding to the detection frame Gd of the first pattern image Im1. For edge detection, for example, a Laplacian filter can be used as edge detection using second-order differentiation. Then, the control unit 9 scores the sharpness of the detected edge.

[0081] The control unit 9 performs the above processing on the first pattern images Im1 acquired at a plurality of positions in the Z direction and compares the scores between the first pattern images Im1. Thereby, the control unit 9 detects a position (a position where the first pattern PA is in focus) where the condensing position of the laser beam L coincides with the back surface 21b from a plurality of positions in the Z direction, and moves the laser processing head 3 to that position. Here, although the explanation has been made on the premise that the edge of the first pattern PA is detected in step S46, depending on the designation of the detection frame Gd, the edge may not be suitably detected.

[0082] Therefore, in the subsequent step, the control unit 9 determines whether or not the edge of the first pattern PA was detected in step S46 (step S47). As a result of the determination in step S47, when the edge of the first pattern PA was not detected (step S47: NO), the control unit 9 receives a re-designation of a different detection frame Gd or automatically re-designates a different detection frame Gd (step S50), and executes the edge detection in step S46 again. In addition, when the number of times of re-setting the detection frame Gd exceeds a certain number, the control unit 9 may perform an error display or the like on the GUI 10 to notify the user that edge detection is difficult.

[0083] On the other hand, if the edge of the first pattern PA is detected as a result of the determination in step S47 (step S47: YES), the control unit 9 controls the operation of the first vertical movement mechanism 7A in the same manner as in step S36, and moves the laser processing head 3 along the Z direction so that the condensing position of the laser beam L coincides with the position (processing depth) in the Z direction where the object 20 is actually processed (step S48). Further, the control unit 9 obtains the detection value of the back surface 21b by the AF unit 36 when the condensing position of the laser beam L is adjusted to the desired depth in the same manner as in step S37 (step S49), and ends the process.

[0084] As described above, in the laser processing apparatus 1, the machining machine side height setting is performed by the image processing by the control unit 9.

[0085] Subsequently, the observation side height setting in step S6 described above will be explained. In the laser processing apparatus 1, in step S6, the control unit 9 controls the second vertical movement mechanism 7B based on the image processing of the second pattern image Im2 captured by the camera 44 so that the image of the second pattern PB coincides with the laser beam incident surface (back surface 21b) of the object 20 and / or the opposite surface (front surface 21a) of the laser beam incident surface. Hereinafter, first, an example in which the control unit 9 performs template matching as image processing will be described.

[0086] As shown in FIG. 12, in this example, first, the control unit 9 acquires the front surface Z-axis information (step S61). The front surface Z-axis information is the machining machine side height setting information acquired in step S35 of the machining machine side height setting, and is information indicating the position in the Z direction (the movement amount of the first vertical movement mechanism 7A) where the condensing position of the laser beam L coincides with the back surface 21b which is the laser beam incident surface of the object 20.

[0087] Subsequently, the control unit 9 controls the operation of the second vertical movement mechanism 7B based on the front surface Z-axis information, and moves the internal observation unit 4 along the Z direction so that the condensing position of the transmitted light l1 is located on the back surface 21b which is the transmitted light incident surface of the object 20 (step S62).

[0088] Subsequently, the control unit 9 performs template matching (step S63). In step S63, the control unit 9 causes the transmission light source 41 to output transmission light l1, projects the second pattern PB of the second reticle Q2 onto the object 20, and acquires a second pattern image Im2 including an image of the second pattern PB by the camera 44. Subsequently, the control unit 9 performs template matching using the image of the second pattern PPB as a template image. The template matching is the same as in step S35. As a result, the control unit 9 determines that the position in the Z direction where the second pattern image Im2 with the highest similarity is obtained is the position where the condensing position of the transmission light l1 coincides with the back surface 21b (the position where the second pattern PB is in focus), and moves the internal observation unit 4 to that position. The control unit 9 acquires information indicating the position of the back surface 21b in the Z direction at this time as the first observation side height set information.

[0089] Subsequently, the control unit 9 acquires the thickness of the semiconductor substrate 21 (wafer) in the object 20 (step S64). Here, the control unit 9 can acquire the thickness of the semiconductor substrate 21 based on user input via the GUI 10.

[0090] Subsequently, the control unit 9 controls the operation of the second vertical movement mechanism 7B to move the internal observation unit 4 in the Z direction by an amount corresponding to the thickness of the semiconductor substrate 21 acquired in step S64 (step S65). As a result, the condensing position of the transmission light l1 is made to generally coincide with the opposite surface (front surface 21a) of the back surface 21b, which is the transmission light incident surface of the object 20.

[0091] Subsequently, the control unit 9 performs template matching (step S66). In step S66, the control unit 9 causes the transmission light source 41 to output transmission light l1, projects the second pattern PB of the second reticle Q2 onto the object 20, and acquires a second pattern image Im2 including an image of the second pattern PB by the camera 44. Subsequently, the control unit 9 performs template matching using the image of the second pattern PB as a template image. The template matching is the same as in step S35. As a result, it is assumed that the position in the Z direction where the second pattern image Im2 with the highest similarity is obtained is the position where the condensing position of the transmission light l1 coincides with the surface 21a (the position where the second pattern PB is in focus). The control unit 9 acquires information indicating the position in the Z direction of the surface 21a at this time as the second observation-side height set information.

[0092] Then, based on the first observation-side height set information indicating the position in the Z direction of the back surface 21b and the second observation-side height set information indicating the position in the Z direction of the front surface 21a, the control unit 9 controls the operation of the second vertical movement mechanism 7B so that the condensing position of the transmission light l1 becomes the desired observation position in the Z direction, and moves the internal observation unit 4 along the Z direction (step S67), and ends the process.

[0093] As described above, for the second pattern PB according to the present embodiment, even if the second reticle Q2 rotates around the optical axis of the transmission light l1, no posture change occurs. That is, even if there is a deviation in the installation angle of the second reticle Q2 around the optical axis of the transmission light l1, the template image remains unchanged. Therefore, the time related to the detection of the template image by scanning the second pattern image Im2 is constant regardless of the presence or absence and the amount of deviation of the installation angle of the second reticle Q2 around the optical axis of the transmission light l1. Here, since a total of two template matchings are performed for each of the back surface 21b and the front surface 21a, the effect of making the time related to the detection of the template image constant becomes greater.

[0094] Subsequently, as another example of the observation-side height set in step S6 described above, an example in which the control unit 9 uses edge detection as image processing will be described. As shown in FIG. 13, in this example, first, the control unit 9 receives the designation of the detection frame in the same manner as in step S41 (step S71).

[0095] Subsequently, the control unit 9 acquires the surface Z-axis information in the same manner as in step S61 (step S72). Subsequently, the control unit 9 controls the operation of the second vertical movement mechanism 7B based on the surface Z-axis information in the same manner as in step S62, and moves the internal observation unit 4 along the Z direction so that the condensing position of the transmitted light l1 is located on the back surface 21b, which is the transmitted light incident surface of the object 20 (step S73).

[0096] Subsequently, the control unit 9 performs edge detection (step S74). In step S74, the control unit 9 outputs the transmitted light l1 from the transmitted light source 41 to project the second pattern PB of the second reticle Q2 onto the object 20, and acquires a second pattern image Im2 including an image of the second pattern PB by the camera 44. Subsequently, the control unit 9 detects the edge of the second pattern PB in the detection frame Gd of the second pattern image Im2. For edge detection, for example, a Laplacian filter can be used as edge detection using second-order differentiation. Then, the control unit 9 scores the sharpness of the detected edge.

[0097] The control unit 9 performs the above processing on the second pattern images Im2 acquired at a plurality of positions in the Z direction and compares the scores between the second pattern images Im2. As a result, the control unit 9 detects a position (a position where the second pattern PB is in focus) where the condensing position of the transmitted light l1 coincides with the back surface 21b from a plurality of positions in the Z direction, and moves the internal observation unit 4 to that position. The control unit 9 acquires information indicating the Z-direction position of the back surface 21b at this time as the first observation-side height set information. Here, although the description has been made on the premise that the edge of the second pattern PB is detected in step S74, depending on the designation of the detection frame Gd, the edge may not be detected suitably.

[0098] Therefore, in the subsequent step, the control unit 9 determines whether or not an edge of the second pattern PB was detected in step S74 (step S75). As a result of the determination in step S75, if an edge of the second pattern PB was not detected (step S75: NO), the control unit 9 receives a re-designation of a different detection frame Gd or automatically re-designates a different detection frame Gd (step SS81), and again executes the edge detection in step S74. In addition, when the number of times of re-setting the detection frame Gd exceeds a certain number, the control unit 9 may perform an error display or the like on the GUI10 to notify the user that it is difficult to detect an edge.

[0099] On the other hand, as a result of the determination in step S75, if an edge of the second pattern PB was detected (step S75: YES), the control unit 9 obtains the thickness of the semiconductor substrate 21 (wafer) in the object 20 in the same manner as in step S64 (step S76).

[0100] Subsequently, the control unit 9 controls the operation of the second vertical movement mechanism 7B to move the internal observation unit 4 in the Z direction by an amount of movement corresponding to the thickness of the semiconductor substrate 21 obtained in step S76 (step S77). Thereby, the condensing position of the transmitted light l1 is made to generally coincide with the opposite surface (front surface 21a) of the back surface 21b which is the transmitted light incident surface of the object 20.

[0101] Subsequently, the control unit 9 performs edge detection (step S78). The edge detection is the same as in step S74. Thereby, it is assumed that the position in the Z direction at which the second pattern image Im2 with the highest similarity was obtained by the control unit 9 is the position at which the condensing position of the transmitted light l1 coincides with the front surface 21a (the position at which the second pattern PB is in focus). The control unit 9 obtains information indicating the position in the Z direction of the front surface 21a at this time as the second observation-side height set information.

[0102] In the subsequent step, the control unit 9 determines, in the same manner as in step S75, whether an edge of the second pattern PB is detected in step S78 (step S79). As a result of the determination in step S79, if the edge of the second pattern PB is not detected (step S79: NO), the control unit 9 receives a re-designation of a different detection frame Gd or automatically re-designates a different detection frame Gd (step SS82), and executes the edge detection in step S78 again. If the number of times of re-setting the detection frame Gd exceeds a certain number, the control unit 9 may display an error or the like on the GUI10 to notify the user that it is difficult to detect the edge.

[0103] Then, based on the first observation-side height set information indicating the Z-direction position of the back surface 21b and the second observation-side height set information indicating the Z-direction position of the front surface 21a, the control unit 9 controls the operation of the second vertical movement mechanism 7B so that the condensing position of the transmitted light l1 becomes the desired observation position in the Z direction, and moves the internal observation unit 4 along the Z direction (step S80), and ends the process.

[0104] As described above, the laser processing apparatus 1 according to the present embodiment includes an illumination light source R1 that irradiates the first reticle R2 with illumination light Li, separately from the light source 31 for performing laser processing. Therefore, at the time of height setting, while irradiating the first reticle R2 with the illumination light Li, by forming an image of the projection image of the first reticle R2 on the object 20 with the illumination light Li that has passed through the first reticle R2, the first pattern PA can be projected onto the object 20. Therefore, if the first pattern PA projected onto the object 20 is imaged, it is possible to detect the laser light incident surface of the object 20 using the first pattern image Im1 obtained by the imaging.

[0105] Here, the first pattern PA does not have a dependency on the rotation angle of the first reticle R2 around the optical axis of the illumination light Li. Therefore, regardless of the rotation angle of the first reticle R2 around the optical axis, the posture of the first pattern PA projected onto the object 20 (the posture within the first pattern image Im1) does not change. For this reason, even if there is a variation in the installation angle of the first reticle R2 around the optical axis of the illumination light Li, it will not give the user a sense of discomfort or increase the time required for detecting the first pattern PA by image processing. Thus, when installing the first reticle R2, it is not necessary to adjust the rotation angle around the optical axis of the illumination light Li. As a result, in the laser processing apparatus 1, the installation of the first reticle R2 is facilitated.

[0106] Also, in the laser processing apparatus 1 according to the present embodiment, the projection optical system for projecting the first pattern PA includes a laser light condensing lens 33 for forming an image of the first pattern PA by the illumination light Li on the object 20. And the camera 35 acquires the first pattern image Im1 by detecting the illumination light Li incident from the object 20 through the laser light condensing lens 33. For this reason, in the projection optical system for projecting the first pattern PA, the laser light condensing lens 33 for condensing the laser light L on the object 20 is shared, and the number of components is reduced.

[0107] Also, in the laser processing apparatus 1 according to the present embodiment, the first reticle R2 includes a transmission part Pt that transmits the illumination light Li and a first pattern PA that forms a shadow on the object 20 by having a lower transmittance of the illumination light Li than the transmission part Pt when viewed from the optical axis direction of the illumination light Li. The first pattern PA includes at least one circle P1, P2 with the optical axis of the illumination light Li as the pattern center Pc. And in the first reticle R2, a circular area including the pattern center Pc when viewed from the optical axis direction is the transmission part Pt, and the pattern center Pc is made to be at the center Dc of the angle of view of the camera 35.

[0108] As described above, when the laser light condensing lens 33 is shared in the projection optical system, the reflected light of the laser light L together with the illumination light Li enters the camera 35 through the laser light condensing lens 33. For this reason, a spot of the laser light L occurs in the first pattern image Im1 acquired by the camera 35. Therefore, by setting the pattern center Pc of the first pattern PA as the transmission portion Pt so that no shadow is formed and setting it as the center Dc of the angle of view of the camera 35, it is possible to confirm the deviation of the optical axis of the laser light L by comparing the position of the pattern center Pc and the spot of the laser light L.

[0109] Further, the laser processing apparatus 1 according to the present embodiment includes a first vertical movement mechanism 7A that moves the laser processing head 3 along the Z direction intersecting the laser light incident surface (the back surface 21b) of the object 20, and based on the image processing of the first pattern image Im1, a control unit 9 that controls the first vertical movement mechanism 7 so that the image of the first pattern PA coincides with the back surface 21b. For this reason, based on the image processing of the first pattern image Im1, it is possible to adjust the position of the laser processing head 3 in the Z direction. In particular, as described above, in the laser processing apparatus 1, regardless of the rotation angle around the optical axis of the first reticle R2, the posture of the first pattern PA projected onto the object 20 (the posture in the first pattern image Im1) does not change. Therefore, it is possible to avoid the lengthening of the image processing due to the variation in the posture of the first pattern PA.

[0110] In addition, the laser processing apparatus 1 according to the present embodiment includes an observation device for observing the object 20. The observation device includes a transmission light source 41 that outputs transmission light l1 having transparency with respect to the object 20, a transmission light condenser lens 43 for condensing the transmission light l1 onto the object 20, a second reticle Q2 that is disposed on the optical path of the transmission light l1 between the transmission light source 41 and the transmission light condenser lens 43 and has a second pattern PB projected onto the object 20, a lens Q3 and a transmission light condenser lens 43 (second projection optical system) that include the transmission light condenser lens 43 and form an image of the projection image of the second reticle Q2 on the object 20 with the transmission light l1 that has passed through the second reticle Q2, thereby projecting the second pattern PB onto the object 20, and a camera 44 that acquires an observation image of the object 20 by the transmission light l1 and a second pattern image Im2 including an image of the second pattern PB by detecting the transmission light l1 incident from the object 20 through the transmission light condenser lens 43. The transmission light condenser lens 43 forms an image of the second pattern PB by the transmission light l1 on the object 20. The second pattern PB has a shape that does not depend on the rotation angle of the second reticle Q2 around the optical axis of the transmission light l1.

[0111] As described above, the laser processing apparatus 1 is provided with an observation device for observing the object, and also for the observation device, a second reticle Q2 is provided on the optical path of the transmission light l1 for observing the object 20. And the second pattern PB of the second reticle Q2 projected onto the object 20 does not depend on the rotation angle of the second reticle Q2 around the optical axis of the transmission light l1.

[0112] Therefore, regardless of the rotation angle of the second reticle Q2 around the optical axis, the posture of the second pattern PB projected onto the object 20 (the posture in the second pattern image Im2) does not change. For this reason, even if there is a variation in the installation angle of the second reticle Q2 around the optical axis of the transmission light l1, it does not give the user a sense of discomfort or increase the time required for detecting the second pattern PB by image processing. Therefore, when installing the second reticle Q2, it is not necessary to adjust the rotation angle around the optical axis of the transmission light l1. Thus, in the laser processing apparatus 1, the second reticle Q2 of the observation device can also be easily installed.

[0113] In addition, in the laser processing apparatus 1 according to the present embodiment, the observation device includes at least an internal observation unit 4 including a transmission light source 41, a transmission light condenser lens 43, a second reticle Q2, a second projection optical system, and a camera 44, and a second vertical movement mechanism 7B that moves the internal observation unit 4 along the Z direction intersecting the transmission light incident surface (back surface 21b) of the object 20, and a control unit 9 that controls the second vertical movement mechanism 7B so that the image of the second pattern PB matches the back surface 21b and / or the front surface 21a on the opposite side of the transmission light incident surface of the object 20 based on the image processing of the second pattern image Im2. Therefore, based on the image processing of the second pattern image Im2, the position adjustment of the internal observation unit 4 in the Z direction becomes possible. In particular, as described above, in the laser processing apparatus 1, the posture of the second pattern PB projected onto the object 20 (the posture in the second pattern image) does not change regardless of the rotation angle around the optical axis of the second reticle Q2. Therefore, it is possible to avoid the lengthening of the image processing caused by the variation in the posture of the second pattern PB.

[0114] Here, when the control unit 9 performs edge processing on the height set during internal observation, a further effect is achieved. As shown in FIG. 14, during internal observation, a modified region 12 and cracks 14 extending from the modified region 12 are already formed in the street region 23 of the object 20. In the internal observation using the transmitted light l1, an image of the crack 14 (and the trace of the modified region 12) in the street region 23 is detected in the second pattern image Im2.

[0115] Therefore, if the shape of the pattern PD is a cross shape extending in two directions intersecting each other like a conventional reticle, a portion along one direction (the processing progress direction) of the pattern PD will overlap with the crack 14. Therefore, in a conventional reticle, only a part extending in another direction (a direction intersecting the processing progress direction) of the pattern PD is used for edge detection. On the other hand, in the second pattern PB of the second reticle Q2 according to the present embodiment, most of the arc-shaped portion located in the street region 23 can be used for edge detection. For this reason, the detection area is improved and the accuracy of edge detection is improved.

[0116] The above embodiments describe one aspect of the present disclosure. Therefore, the present disclosure can be modified without being limited to the above one aspect.

[0117] For example, as shown in FIG. 15, during internal observation, the second pattern PB of the second reticle Q2 can be arranged at a position different from the determination location Ed, which is the target of internal observation, in the street region 23. Thereby, when imaging the observation image of the object 20 by the transmitted light l1, the projection of the second pattern PB onto the determination location Ed is suppressed, and a decrease in observation accuracy is suppressed.

[0118] Further, in the above embodiment, an aspect in which the laser processing apparatus 1 includes an observation apparatus including the internal observation unit 4 has been described. That is, in the laser processing apparatus 1 according to the above embodiment, the processing machine is constituted by the stage 2, the laser processing head 3, the first vertical movement mechanism 7A, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the control unit 9, and the observation apparatus is constituted by the stage 2, the internal observation unit 4, the second vertical movement mechanism 7B, the first horizontal movement mechanism 8A, the second horizontal movement mechanism 8B, and the control unit 9. That is, in the above embodiment, the laser processing apparatus 1 is configured such that the processing machine and the observation apparatus share elements partially with each other. However, the processing machine and the observation apparatus may be configured separately.

[0119] In this case, the observation device is a separate device independent of the processing machine. The observation device in this case is: (a) a device for observing the object 20 by means of transmitted light l1 that passes through the object 20, (b) a transmitted light source 41 that outputs transmitted light l1 having permeability to the object 20, (c) a transmitted light condenser lens 43 for condensing the transmitted light l1 onto the object 20, (d) a second reticle Q2 that is disposed on the optical path of the transmitted light l1 between the transmitted light source 41 and the transmitted light condenser lens 43 and has a second pattern PB projected onto the object 20, (e) a second projection optical system that includes the transmitted light condenser lens 43 and forms an image of the second reticle Q2 on the object 20 with the transmitted light l1 that has passed through the second reticle Q2, thereby projecting the second pattern PB onto the object 20, and (f) a camera 44 that obtains an observation image of the object 20 by means of the transmitted light l1 and a second pattern image Im2 that includes an image of the second pattern PB by detecting the transmitted light l1 that enters from the object 20 via the transmitted light condenser lens 43. At this time, (g) the second pattern PB has a shape that does not have a dependency on the rotation angle of the second reticle Q2 around the optical axis of the transmitted light l1.

[0120] Further, the observation device includes: (h) a second vertical movement mechanism 7B that moves an internal observation unit 4 including at least the transmitted light source 41, the transmitted light condenser lens 43, the second reticle Q2, the second projection optical system, and the camera 44 along the Z direction intersecting the transmitted light incident surface of the object 20, and (i) a control unit 9 that controls the second vertical movement mechanism 7B based on image processing of the second pattern image Im2 so that the image of the second pattern PB aligns with the transmitted light incident surface and / or the surface on the opposite side of the transmitted light incident surface of the object 20.

[0121] Further, in the observation device, (j) the control unit 9 outputs transmitted light l1 from the transmitted light source 41, projects the second pattern PB of the second reticle Q2 onto the object 20, and acquires a second pattern image Im2 including an image of the second pattern PB by the camera 44. Also, (k) the control unit 9 performs template matching using the image of the second pattern PB as a template image as image processing of the second pattern image Im2. Thereby, (l) the control unit 9 controls the second Z-axis moving unit so that the image of the second pattern PB matches the transmitted light incident surface and / or the surface on the opposite side of the transmitted light incident surface of the object 20.

[0122] Alternatively, in the observation device, (j) the control unit 9 outputs transmitted light l1 from the transmitted light source 41, projects the second pattern PB of the second reticle Q2 onto the object 20, and acquires a second pattern image Im2 including an image of the second pattern PB by the camera 44. Also, (k) the control unit 9 performs edge detection of the second pattern PB in the detection frame Gd of the second pattern image Im2 as image processing of the second pattern image Im2. Thereby, (l) the control unit 9 compares scores indicating the sharpness of the detected edges between the second pattern images Im2 at a plurality of positions in the Z direction, and detects a position (a position where the second pattern PB is in focus) where the condensing position of the transmitted light l1 matches the transmitted light incident surface and / or the opposite surface. Then, (m) the control unit 9 controls the second vertical movement mechanism 7B to move the internal observation unit 4 so that the condensing position of the transmitted light l1 matches the detected position. Note that in the observation device, (n) the detection frame Gd and the second pattern PB can be arranged in the street area 23.

Explanation of Signs

[0123] 1…Laser processing apparatus, 2…Stage (support part), 3…Laser processing head, 4…Internal observation unit (observation unit), 7A…First vertical movement mechanism (first Z-axis movement part), 7B…Second vertical movement mechanism (second Z-axis movement part), 9…Control unit, 12…Modification area, 20…Object, 21a…Surface, 21b…Back surface (laser light incident surface, transmitted light incident surface), 33…Laser light condensing lens (first condensing lens), 35…Camera (first camera), 41…Transmitted light source, 43…Transmitted light condensing lens (second condensing lens), L…Laser light, Li…Illumination light, l1…Transmitted light, R1…Illumination light source, R2…First reticle, PA…First pattern, Q2…Second reticle, PB…Second pattern, Pt…Transmission part, P1, P2…Circles, Pc…Pattern center, Dc…Center of picture angle.

Claims

1. A laser processing apparatus for forming a modified region on an object by irradiating the object with a laser beam, comprising: a support unit for supporting the object; a laser light source for outputting the laser beam; a first condenser lens for condensing the laser beam on the object supported by the support unit; a first reticle having a first pattern projected onto the object; an illumination light source for irradiating the first reticle with illumination light; a first projection optical system for projecting the first pattern onto the object by forming an image of the first reticle on the object with the illumination light that has passed through the first reticle; a first camera for imaging an image of the first pattern projected onto the object to obtain a first pattern image; a display unit for displaying the first pattern image; wherein the first pattern has a shape that does not depend on the rotation angle of the first reticle around the optical axis of the illumination light. Laser processing apparatus.

2. The first projection optical system includes the first condenser lens for forming an image of the first pattern by the illumination light on the object, and the first camera obtains the first pattern image by detecting the illumination light incident from the object through the first condenser lens. The laser processing apparatus according to claim 1.

3. The first reticle includes a transmissive portion that transmits the illumination light and the first pattern that forms a shadow on the object by having a lower transmittance of the illumination light than the transmissive portion, when viewed from the direction of the optical axis of the illumination light. The first pattern includes at least one circle centered on the optical axis. In the first reticle, a circular area including the pattern center is the transmissive portion when viewed from the optical axis direction, and the pattern center is set to be at the center of the field angle of the first camera. The laser processing apparatus according to claim 2.

4. a first Z-axis moving unit for moving a laser processing head including at least the first condenser lens, the first reticle, the illumination light source, the first projection optical system, and the first camera along the Z direction intersecting the laser beam incident surface of the object; a first control unit for controlling the first Z-axis moving unit based on image processing of the first pattern image so that the image of the first pattern coincides with the laser beam incident surface; wherein The laser processing apparatus according to any one of claims 1 to 3.

5. comprises an observation device for observing the object, The observation device a transmission light source that outputs transmission light having permeability to the object, a second condenser lens for condensing the transmission light onto the object, a second reticle disposed on the optical path of the transmission light between the transmission light source and the second condenser lens and having a second pattern projected onto the object, a second projection optical system that includes the second condenser lens and projects the second pattern onto the object by forming an image of the projection image of the second reticle on the object with the transmission light that has passed through the second reticle, a second camera that acquires an observation image of the object by the transmission light and a second pattern image including an image of the second pattern by detecting the transmission light incident from the object through the second condenser lens, and has The second pattern has a shape that does not depend on the rotation angle of the second reticle around the optical axis of the transmission light. The laser processing apparatus according to any one of claims 1 to 4.

6. The observation device at least a second Z-axis moving unit that moves an observation unit including the transmission light source, the second condenser lens, the second reticle, the second projection optical system, and the second camera along the Z direction intersecting the transmission light incident surface of the object, a second control unit that controls the second Z-axis moving unit based on image processing of the second pattern image so that the image of the second pattern fits the transmission light incident surface and / or the surface of the object on the side opposite to the transmission light incident surface of the object, The laser processing apparatus according to claim 5, which has

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