JP5394172B2 - Processing method - Google Patents

Description

  The present invention relates to a processing method for processing a workpiece such as a semiconductor wafer.

  As a method of dividing a workpiece such as a semiconductor wafer or an optical device wafer along a planned dividing line, a pulsed laser beam for processing (pulse laser beam) having transparency to the workpiece is used. Attempts have been made to use a laser processing method in which a laser beam is irradiated to the inside of a workpiece with a converging point (see, for example, Patent Document 1). In the dividing method using this laser processing method, for example, the above-mentioned pulse laser beam is irradiated by the laser irradiation means in a state where the focusing point is aligned from the surface side of the workpiece to the inside of the workpiece, The reforming region along the line to be divided is continuously formed inside. Then, by applying an external force to the work piece, the work piece is divided along the division planned line whose strength is reduced by forming the modified region. Here, in Patent Document 1, the modified region is formed at a predetermined position inside the workpiece. However, the modified region of a plurality of layers may be formed by changing the position in the depth direction from the surface. .

Japanese Patent No. 3408805

  In the laser processing method described above, prior to the formation of the modified region, alignment between the planned division line and the laser irradiation means is performed. This alignment is based on the positional relationship between the laser irradiation means and the camera by detecting the planned division line by imaging the surface of the workpiece using a camera whose positional relationship with the laser irradiation means is fixed. This is done by positioning the laser irradiation means on the division line. However, the positional relationship between the laser irradiating means and the camera may change during the laser processing depending on the temperature that fluctuates in the process of applying the laser processing to the workpiece. In order to solve this problem, it is necessary to detect the position (processing position) where the modified region is actually formed with a camera or the like as needed to check whether it is along the planned division line.

  By the way, when a plurality of modified regions are formed inside the workpiece, cracks based on the modified region formed on the surface side may occur on the surface of the workpiece. It does not always occur directly above the area. For this reason, if the machining position is simply imaged with a camera, there is a problem that the machining position cannot be detected correctly due to a crack.

  The present invention has been made in view of the above, and provides a machining method capable of performing high-precision laser machining along a planned division line on a workpiece while properly detecting a machining position. For the purpose.

  In order to solve the above-described problems and achieve the object, the processing method according to the present invention has a surface on XY coordinates, and a plurality of division lines determined on the surface are along the X-coordinate direction. The pulsed laser irradiation means is sequentially indexed and sent in the Y coordinate direction to the arranged plate-like workpiece, positioned on the division target line to be processed, and the pulse laser irradiation means is processed and sent in the X coordinate direction. By irradiating the inside of the workpiece with a pulse laser beam having a wavelength that passes through the workpiece with a converging point aligned, a plurality of modified regions having different Z-coordinate positions orthogonal to the surface are applied to the workpiece. A processing method in which a plurality of modified regions are formed along a predetermined division line to be processed, and the position on the Z coordinate is the most modified on the front surface side. Prior to forming the region, the modified region that has been formed is imaged along the planned division line using the imaging means that passes through the workpiece and images the inside, and the formed modification is performed. A shift amount calculating step for detecting a position on the Y coordinate of the region and calculating a shift amount from the position on the Y coordinate of the division target line to be processed; and indexing and feeding the pulse laser irradiation means in the Y coordinate direction A positioning step of indexing and feeding the pulse laser irradiation means by shifting the index feed position determined by the distance between the scheduled division lines by the shift amount when positioning on the scheduled division line to be processed next. It is characterized by.

  According to the present invention, in the process of sequentially stacking a plurality of modified regions from the back surface side of the workpiece along the planned division line to be processed, before forming the most modified region on the front surface side, the processing is performed. It is possible to detect the position on the Y coordinate by imaging the modified region that has been formed along the target division line and calculate the amount of deviation from the position on the Y coordinate of the division line to be processed. it can. According to this, it is possible to calculate the amount of deviation by properly detecting the processing position without being affected by the cracks generated on the surface of the workpiece with the modified region as a base point. Then, when the pulse laser irradiation means is indexed and fed in the Y-coordinate direction and positioned on the next division line to be processed, the index feed position determined by the distance between the division division lines is most modified as described above. The position can be shifted by the amount of displacement calculated before forming the region. According to this, the positional deviation between the position on the Y-coordinate of the division target line to be processed and the processing position where the modified region is actually formed is corrected, and the pulse laser irradiation means is changed to the next division target line to be processed. Can be positioned. Therefore, it is possible to perform highly accurate laser processing along the planned division line on the workpiece while properly detecting the processing position.

FIG. 1 is a schematic diagram illustrating the configuration of a processing apparatus and the configuration of a workpiece to which the processing apparatus performs laser processing. FIG. 2 is a plan view showing the surface of the workpiece. FIG. 3 is a schematic view showing a modified region formed inside the workpiece. Figure 4 is a cross-sectional view illustrating a cracks. FIG. 5 is a flowchart for explaining the operation procedure of the machining apparatus that performs the machining method. FIG. 6 is an explanatory diagram for explaining the steps of the processing method. FIG. 7 is an explanatory diagram for explaining another process of the processing method. FIG. 8 is an explanatory diagram illustrating another process of the processing method. FIG. 9 is an explanatory diagram illustrating another process of the processing method.

  Hereinafter, the processing method which is a form for carrying out the present invention is explained with reference to drawings. In this embodiment mode, an example of application to a processing apparatus that performs laser processing on a workpiece is shown. FIG. 1 is a schematic diagram for explaining the configuration of a processing apparatus 2 and the configuration of a workpiece 1 to which the processing apparatus 2 performs laser processing.

As shown in FIG. 1, the workpiece 1 has a disk shape, and a first scheduled division line 11 and a second scheduled division line 13 are arranged in a lattice shape on the surface side, and these first divisions are arranged. The device 15 is formed in a plurality of rectangular areas partitioned by the scheduled division line 11 and the second scheduled line 13. Specific examples of the workpiece 1 are not particularly limited, but various processing materials that require micron-order processing position accuracy, such as semiconductor wafers such as silicon wafers, sapphire (Al ₂ O ₃ ) -based inorganic material substrates, and the like. Is mentioned.

  The processing apparatus 2 that performs laser processing on the workpiece 1 includes a holding unit 21, an X driving unit 23, a Y driving unit 24, a laser processing unit 25, a Z driving unit 27, and a control unit 29. .

  The holding means 21 is mainly a chuck table having a size corresponding to the workpiece 1 and has a holding surface 211 parallel to the XY coordinate plane. As described above, the workpiece 1 is carried into the holding means 21 with the surface on which the device 15 is formed by arranging the first scheduled dividing lines 11 and the second scheduled dividing lines 13 in a lattice shape. , Held on the holding surface 211. More specifically, the workpiece 1 is held on the holding surface 211 at the time of carry-in with the first division line 11 in the X coordinate direction and the second division line 13 in the Y coordinate direction. The

  Thus, the holding means 21 that holds the workpiece 1 on the holding surface 211 is configured to be movable in the X coordinate direction and the Y coordinate direction by the X driving means 23 and the Y driving means 24. The X driving means 23 detects a motor (drive position) for driving the holding means 21 in the X coordinate direction to process and feed the holding means 21 and a position (X position) of the holding means 21 in the X coordinate direction. An X position detecting means (not shown) is provided, and the holding means 21 is moved to a predetermined X position under the control of the control means 29. Similarly, the Y drive means 24 is a motor that is a driving source for moving and driving the holding means 21 in the Y coordinate direction to index and feed the holding means 21, and the position (Y position) of the holding means 21 in the Y coordinate direction. And a Y position detecting means (not shown) for detecting the movement, and the holding means 21 is driven to move to a predetermined Y position under the control of the control means 29. Further, the holding means 21 is configured to be rotatable about a vertical axis passing through the center of the holding surface 211 by an unillustrated rotation driving means.

  The laser processing means 25 is for laser processing the workpiece 1 held on the holding surface 211, and the positional relationship between the support member 251 and the support member 251 is fixed. A laser irradiation unit 253 as an attached pulse laser irradiation unit and an imaging unit 255 as an imaging unit are provided.

  The laser irradiation unit 253 is for irradiating the workpiece 1 on the holding surface 211 with a pulsed laser beam to form a modified region inside the workpiece 1, and has a holding surface at the lower end thereof. A condenser 254 is provided so as to face the surface of the workpiece 1 on 211. On the other hand, a laser beam oscillating means, a transmission optical system, etc. (not shown) are disposed inside the support member 251, and the laser irradiation unit 253 cooperates with these laser beam oscillating means and the transmission optical system. A pulse laser beam is irradiated from the surface side of the workpiece 1 positioned vertically below the condenser 254.

  The condenser 254 collects the pulse laser beam oscillated by the laser beam oscillating means toward the workpiece 1 on the holding surface 211 and the pulse laser beam from the laser beam oscillating means. An optical system such as a mirror for reflecting toward the workpiece 1 on the holding surface 211 is disposed inside. The laser beam oscillating means is for oscillating a pulse laser beam having a predetermined wavelength (for example, 1064 nm) that is transmitted through the workpiece 1 on the holding surface 211, and includes, for example, a YAG laser oscillator, a YVO4 laser oscillator, or the like. It consists of a laser beam oscillator.

  The imaging unit 255 performs alignment for positioning the position of the workpiece 1 to be laser-processed (the center position of the first scheduled division line 11 and the second scheduled division line 13) vertically below the condenser 254. At the same time, the position (processing position) where the laser processing is actually performed by irradiating the pulse laser beam is detected to correct the position to be laser processed. The imaging unit 255 includes, for example, a microscope structure (not shown) including an objective lens disposed so as to face the workpiece 1 on the holding surface 211, and the workpiece 1 by the microscope structure. It consists of a camera (not shown) that captures an enlarged observation image, images the workpiece 1 on the holding surface 211, and outputs the obtained image data to the control means 29. The camera that constitutes the imaging unit 255 is, for example, an infrared camera. In the present embodiment, a silicon wafer is assumed as the workpiece 1, infrared light is detected by this camera, and the inside of the workpiece 1 is imaged through the surface of the workpiece 1. However, the camera of the imaging unit 255 only needs to capture the inside of the workpiece 1.

  Thus, the support member 251 to which the laser irradiation unit 253 and the imaging unit 255 are attached is configured to be movable in the Z coordinate direction orthogonal to the XY coordinate plane by the Z driving means 27. The Z drive means 27 is a motor that is a drive source for moving and driving the support member 251 in the Z coordinate direction, a Z position detection means for detecting the position (Z position) of the support member 251 in the Z coordinate direction (not shown), and the like. The support member 251 is driven to move to a predetermined Z position under the control of the control means 29. With this configuration, the condensing lens built in the condenser 254 can be moved perpendicularly to the holding surface 211, and the laser processing means 25 can collect the condensing point of the pulsed laser beam collected by the condensing lens. The position (Z position) can be adjusted.

  The control means 29 is constituted by a microcomputer or the like with a built-in memory for holding various data necessary for the operation of the processing apparatus 2, and controls the processing apparatus 2 by controlling the operation of each part constituting the processing apparatus 2. To do.

  In this processing apparatus 2, the holding means 21 is moved in the X coordinate direction and the Y coordinate direction by the X drive means 23 and the Y drive means 24, and the support member 251 is moved in the Z coordinate direction by the Z drive means 27. However, another configuration may be used as long as the holding unit 21 and the support member 251 can move relative to each other in the X, Y, and Z coordinate directions. For example, the support member 251 may be fixed and the holding means 21 may be moved in the X, Y, and Z coordinate directions, or the holding means 21 may be fixed and the support member 251 may be set in the X, Y, and Z coordinates. It is good also as a structure moved to a direction. Alternatively, both the holding means 21 and the support member 251 can be moved relative to each other along the X, Y, and Z coordinate directions so as to be relatively moved. Which of the holding means 21 and the support member 251 is moved along each of the X, Y, and Z coordinate directions and whether both the holding means 21 and the support member 251 are moved can be appropriately set.

  Next, the flow of laser processing performed on the workpiece 1 by the processing apparatus 2 configured as described above will be described. FIG. 2 is a plan view showing the surface of the workpiece 1. In laser processing on the workpiece 1, first, the imaging unit 255 detects the center position (Y position) of the first divisional line 11 to be processed first by imaging the surface of the workpiece 1, and detects it. The center position of the first scheduled division line 11 is positioned vertically below the condenser 254, and the center position of the first scheduled division line 11 and the condenser lens are aligned. For example, if the first division planned line 11-1 at the lowest stage shown in FIG. 2 is to be processed first, the center position of the first division planned line 11-1 (first division planned line 11-1). 11-1 (Y position on the center line C11 indicated by a broken line), the holding means 21 is moved in the Y coordinate direction based on the known positional relationship (distance) between the laser irradiation unit 253 and the imaging unit 255. Align by shifting. Note that the distance between the laser irradiation unit 253 and the imaging unit 255 is defined in advance as a set value and stored in the memory of the control unit 29.

  After such alignment, laser processing is performed on the first scheduled division line 11-1. Specifically, the laser irradiation unit 253 sequentially irradiates a pulse laser beam while processing and feeding the holding unit 21 in the X coordinate direction, thereby forming a modified region along the first scheduled division line 11-1. . Thereafter, the modified region is formed along each of the first planned division lines 11 while the center position of the adjacent first division planned lines 11 is positioned vertically below the condenser 254 and the object to be processed is moved. . Here, the position of the center position of the first scheduled division line 11 with respect to the vertically lower side of the condenser 254 is determined using the distance L11 between the center positions of the first scheduled division lines 11 adjacent to each other with the device 15 in between. . For example, if the formation of the modified region for the first scheduled division line 11-1 is finished, the position where the holding means 21 is shifted in the Y coordinate direction by the distance L11 is indexed and sent. Thus, the center position of the first scheduled division line 11-2 (Y position on the center line C13 indicated by the broken line of the first division planned line 11-2) is positioned vertically below the condenser 254.

  When the reformed regions are formed for all the first planned division lines 11, the holding means 21 is rotated 90 degrees so that the second divided division line 13 is aligned along the X coordinate direction. The posture of the workpiece 1 is changed. Then, after alignment is performed in the same manner as the operation for the first scheduled division line 11, the center position of the second scheduled division line 13 is sequentially positioned vertically below the condenser 254, and the second target is moved while moving the processing target. A modified region is formed along each of the division lines 13. For the positioning of the center position of the second scheduled division line 13 with respect to the vertically lower side of the condenser 254, the distance L13 between the central positions of the second scheduled division line 13 is used. This is done by indexing and feeding the position shifted in the direction as the index feed position. This distance L13 is defined in advance as a set value together with the distance L11 between the center positions of the first planned division lines 11 described above, and is stored in the memory of the control means 29.

  FIG. 3 shows one first scheduled division line in which the modified region formed inside the workpiece 1 along each of the first scheduled division line 11 and the second scheduled division line 13 as described above. FIG. 3 is a schematic diagram showing attention paid to 11, and in FIG. 3, modified regions 17 a and 17 b formed inside by cutting out a part of the workpiece 1 along the first planned division line 11. , 17c, and the pulse laser beam irradiated by the laser irradiation unit 253 is indicated by a two-dot chain line. In the present embodiment, a plurality of layers having different positions (Z positions) in the depth direction from the surface inside the workpiece 1 for each of the first scheduled division lines 11 and each second scheduled division line 13 (see FIG. 3 is a three-layered modified region 17a, 17b, 17c.

  For example, these three layers of modified regions 17a, 17b, and 17c overlapping in the depth direction are irradiated with a pulsed laser beam while sequentially adjusting the focal point to the depth position sequentially from the lowermost modified region 17a. By forming. That is, first, the support member 251 is placed at a preset Z position so that the focal point position of the pulse laser beam coincides with the depth position of the lowermost modified region (hereinafter referred to as “lowermost layer position”). Move. Then, the pulse laser beam is irradiated in such a state that the focal point is aligned with the lowermost layer position, and the modified region 17a along the first scheduled division line 11 is formed at the lowermost layer position.

  Subsequently, the support member 251 is placed at a preset Z position so that the focal point position of the pulse laser beam coincides with the depth position of the modified region of the central layer (hereinafter referred to as “central layer position”). Move. In this way, the pulsed laser beam is irradiated in a state where the condensing point is aligned with the central layer position, thereby forming the modified region 17b along the first planned division line 11 at the central layer position. Further, the support member 251 is moved to a preset Z position so that the focal point position of the pulse laser beam coincides with the depth position of the uppermost modified region (hereinafter referred to as “uppermost layer position”). Let Then, as shown by a one-dot chain line in FIG. 3, a pulse laser beam is irradiated from the surface side of the workpiece 1 in such a state that the focal point is aligned with the uppermost layer position, and the first layer position is the first layer position. The modified region 17c is formed along the scheduled dividing line 11. In addition, although the three-layer modified region is illustrated here, a predetermined number of modified regions of two or more layers may be appropriately formed.

  Here, the modified region refers to a region in which the density, refractive index, mechanical strength, or other physical characteristics are different from those before processing. For example, a melt treatment region, a crack region, a dielectric breakdown region, a refractive index change region, and the like are included, and a region where these are mixed is included.

  By the way, as described above, the distance between the laser irradiation unit 253 and the imaging unit 255 may change during the laser processing due to a temperature that varies in the process of laser processing. For this reason, when alignment is performed and the central position of the first division planned line 11 or the second division planned line 13 is aligned with the condenser lens, a positional deviation may occur between them. Deviation occurs between the center positions of the scheduled division line 11 and the second scheduled division line 13 and the machining positions with respect to the first scheduled division line 11 and the second scheduled division line 13. Therefore, it has been necessary to detect the machining position at any time, such as by actually capturing the machining position with a camera, and to correct this positional deviation.

On the other hand, when a modified region is formed by irradiating the surface side of the workpiece 1 with a pulse laser beam, a crack based on the formed modified region may occur on the surface of the workpiece 1. FIG. 4 is a sectional view for explaining this crack. In FIG. 4, the inside of the workpiece 1 in which the three-layer modified regions 17a, 17b, and 17c are formed is shown from the X- coordinate direction, and the uppermost modified region 17c on the most surface side is a base point. The cracks 191 and 193 generated on the surface side of the workpiece 1 are shown.

  Here, the crack 191 generated by the uppermost modified region 17c on the left side in FIG. 4 is formed substantially vertically above the modified region 17c along the Z coordinate direction. On the other hand, the crack 193 generated by the uppermost modified region 17c on the right side in FIG. 4 is formed in an obliquely rightward direction from the modified region 17c toward the surface side of the workpiece 1. Thus, the crack generated on the surface side of the workpiece 1 by the uppermost modified region 17c is not necessarily formed vertically above the uppermost modified region 17c. For this reason, if the machining position is imaged after the uppermost modified region 17c is formed, the machining position may not be detected correctly due to this crack.

  Therefore, in the present embodiment, when the lower-layer modified regions 17a and 17b other than the uppermost modified region 17c are formed, the inside of the workpiece 1 is imaged and the first division schedule to be processed is made. The center position of the line 11 or the second scheduled division line 13 and the processing position of the modified region of the lower layer (the modified region of the uppermost layer of the lower layers (modified region 17b of the central layer in the present embodiment)) Processing position), and these positional shifts are determined when the center position of the first scheduled division line 11 or the second scheduled division line 13 to be processed next is positioned below the light collector 254 vertically. Used for correction.

Next, the operation of the processing apparatus 2 configured as described above and forming a plurality of modified regions in the workpiece 1 will be described with reference to FIGS. Here, FIG. 5 is a flowchart for explaining the operation procedure of the machining apparatus 2 for carrying out the machining method of the present embodiment. The processing apparatus 2 performs a processing method by operating according to each process of FIG. In addition, operation | movement of the processing apparatus 2 demonstrated below is implement | achieved when the control means 29 controls each part of an apparatus. 6-9 is explanatory drawing explaining each process of a processing method, and has shown the mode inside the to-be-processed object 1 in each process from the X coordinate direction.

  As shown in FIG. 5, the processing apparatus 2 first performs alignment (alignment) between the center position of the first scheduled division line 11 arranged on the surface of the workpiece 1 and the condenser lens (step S <b> 1). . Here, prior to the alignment, the workpiece 1 is carried into the holding means 21 with the carrying means (not shown) facing up, and then the holding means 21 drives the suction means (not shown) on the holding surface 211. The workpiece 1 is held by suction.

  In step S <b> 1, the control unit 29 first drives the X driving unit 23 and the Y driving unit 24 to position the workpiece 1 on the holding surface 211 vertically below the imaging unit 255. Subsequently, the imaging unit 255 is driven to image the workpiece 1, and image processing such as pattern matching is performed on the obtained image data. Then, based on the result of this image processing, the holding means 21 is rotated so that the first division line 11 is along the X coordinate direction and the second division line 13 is along the Y coordinate direction. And the center position of the first scheduled division line 11 that divides the device 15 (for example, the first division schedule at the lowest stage shown in FIG. 2 to be processed first) The position of the line 11-1 on the center line C11) is detected, and the X driving unit 23 and the Y driving unit 24 are driven to be positioned vertically below the imaging unit 255. Thereafter, by shifting the holding means 21 in the Y coordinate direction by the distance between the laser irradiation unit 253 and the imaging unit 255, the center position of the first scheduled division line 11 to be processed first is set to the vertical position of the condenser 254. Positioned below, the first division line 11 is the processing target.

  Subsequently, a modified region of a plurality of layers (three layers in the present embodiment) as described above is formed inside the workpiece 1 along the first division line 11 to be processed. First, as shown in FIG. 5, the processing apparatus 2 according to the embodiment forms the modified regions of the lower layers excluding the uppermost layer sequentially from the back side (step S <b> 3).

  In this step S3, the control means 29 first drives the Z drive means 27 to move the support member 251 in the Z coordinate direction, so that the condensing point of the condensing lens is aligned with the lowest layer position inside the workpiece 1. Then, the X driving means 23 is driven to process and feed the holding means 21 in the X coordinate direction, and at the same time, the laser irradiation unit 253 is driven to irradiate a pulse laser beam from the surface side of the workpiece 1. . As a result, the pulse laser beam is focused on the lowest layer position, and as shown in FIG. 6, a modified region 17a is formed inside the workpiece 1 along the first scheduled division line 11 to be processed. . Further, the Z driving means 27 is driven to move the support member 251 in the Z coordinate direction, and as shown by a one-dot chain line in FIG. 6, the condensing lens condenses on the center layer position above the modified region 17a. Match the points. Then, the X driving means 23 is driven to process and feed the holding means 21 in the X coordinate direction, and at the same time, the laser irradiation unit 253 is driven to irradiate a pulse laser beam from the surface side of the workpiece 1. . As a result, the pulse laser beam is focused on the center layer position, and the modified region 17b is formed above the modified region 17a along the first division planned line 11 to be processed.

  Subsequently, as shown in FIG. 5, the processing apparatus 2 detects the processing position of the modified region of the lower layer formed in step S <b> 3 as a shift amount calculation step, and the center position of the first scheduled division line 11 is detected. A deviation amount from the detected machining position is calculated (step S5).

  Specifically, the control unit 29 first drives the Y drive unit 24 and shifts the holding unit 21 in the Y coordinate direction by the distance between the laser irradiation unit 253 and the imaging unit 255 to thereby modify the lower layer modified region. The processing position where 17a and 17b are formed is positioned vertically below the imaging unit 255. Then, the imaging unit 255 is driven to image the workpiece 1 as indicated by a two-dot chain line in FIG. 7, and the obtained image data is subjected to image processing, whereby the first division line 11 to be processed is processed. The shift position L21 is calculated by detecting the center position and the processing position of the modified region in the lower layer (the processing position of the uppermost modified region 17b in the lower layer). After calculating the displacement L21 in this way, the lower layer modified regions 17a and 17b are moved by shifting the holding means 21 in the Y-coordinate direction by the distance between the laser irradiation unit 253 and the imaging unit 255. Is positioned below the light collector 254 vertically.

  Subsequently, as shown in FIG. 5, the processing apparatus 2 forms the uppermost modified region above the lower modified region formed in step S3 (step S7). In this step S7, the control means 29 first drives the Z drive means 27 to move the support member 251 in the Z coordinate direction, and as shown by the alternate long and short dash line in FIG. 8, the lower layer modified regions 17a, 17b. The condensing point of the condensing lens is aligned with the uppermost layer position above. Thereafter, the X driving means 23 is driven to process and feed the holding means 21 in the X coordinate direction, and at the same time, the laser irradiation unit 253 is driven to irradiate a pulse laser beam from the surface side of the workpiece 1. . As a result, the pulsed laser beam is focused on the uppermost layer position, and the modified region 17c is formed above the modified regions 17a and 17b formed in the previous step along the first division line 11. .

  Then, as shown in FIG. 5, it is determined whether or not the current machining target is the last line in the first division planned line 11. If it is not the final line (step S9: No), the processing apparatus 2 processes the center position of the first scheduled division line 11 and the actual modified region based on the shift amount calculated in step S5 as the positioning step. The positional deviation from the position is corrected, and the processing target is moved to the next first division planned line 11 (step S11).

  In this step S11, first, as shown in FIG. 9, the control means 29 sets the distance L11 between the center positions of the first scheduled division lines 11 defined as the preset values as shown in FIG. The movement amount L31 is determined based on the deviation amount L21 calculated in step S5. Then, the holding means 21 is indexed and fed in the Y-coordinate direction according to the determined movement amount L31, thereby shifting the next index feed position determined by the distance L11 by the shift amount L21, and the next processing target adjacent to the device 15 with the device 15 interposed therebetween. The center position of one division line 11 is positioned vertically below the condenser 254. As a result, the amount of deviation between the center position of the first division line 11 to be machined this time and the machining position where the modified regions 17a, 17b, and 17c are actually formed is corrected, and the next first division. The center position of the planned line 11 is positioned vertically below the condenser 254.

  After that, as shown in FIG. 5, the processing apparatus 1 returns to step S <b> 3 and modifies the lower layer except the uppermost layer inside the workpiece 1 along the first scheduled division line 11 to be processed next. Forming a quality region. That is, as shown by a one-dot chain line in FIG. 9, the pulsed laser beam is condensed at the lowest layer position, and the modified region is formed inside the workpiece 1 along the first division planned line 11 to be processed next. 17c is formed. And the processing apparatus 1 repeats operation | movement after step S5 similarly.

  On the other hand, as shown in FIG. 5, when the processing target line is determined to be the final line in step S <b> 9 (step S <b> 9: Yes), by rotating the holding unit 21 by 90 degrees, The workpiece 1 is displaced in a direction along the X coordinate direction (step S13). And the process similar to step S1-step S11 is performed with respect to the 2nd division | segmentation line 13, and the modification area | region of multiple layers is formed in each of the 2nd division | segmentation line 13. As shown in FIG. That is, the processing apparatus 2 aligns the center position of the second scheduled division line 13 and the condenser lens (step S15), and then forms the uppermost layer along the second scheduled division line 13 to be processed. A modified region in the lower layer is formed (step S17). Subsequently, the processing apparatus 2 detects the processing position of the reformed region of the formed lower layer, and calculates the amount of deviation between the center position of the second scheduled division line 13 and the detected processing position (step S19). After that, the processing apparatus 2 forms the uppermost modified region above the lower modified region formed in step S17 (step S21). While the second scheduled division line 13 to be processed is not the final line (step S23: No), the center position of the second scheduled division line 13 and the actual position are calculated based on the shift amount calculated in step S19. The misalignment with the processing position of the reformed region is corrected and the processing object is moved to the next second division planned line 13 (step S25), and the process returns to step S17 to form a plurality of layers on each of the second planned division lines 13. The modified regions are sequentially formed. And if it determines with the last line (step S23: Yes), this processing method will be complete | finished.

  Note that the workpiece 1 in which a plurality of modified regions are formed inside the workpiece 1 by the present processing method is unloaded from the holding means 21 and mounted on a dividing device (not shown). Divided into chips. Specifically, the dividing device applies the external force to the workpiece 1, and follows the first division planned line 11 and the second division planned line 13 whose strength is reduced by forming the modified region. Then, the workpiece 1 is divided.

  As described above, according to the present embodiment, when the modified region in the lower layer excluding the uppermost layer is formed, the line to be processed (the first division planned line 11 or the second division planned line 13). ) And the processing position of the modified region of the lower layer actually formed can be calculated. According to this, it is possible to appropriately detect the actual processing position with respect to the line to be processed without being affected by cracks generated on the surface of the workpiece with the modified region as a base point, and calculate the amount of deviation. Then, after forming the uppermost modified region above the modified region in the lower layer at the processing position where the modified region in the lower layer is formed, the line is changed based on the amount of deviation calculated as described above. The positional deviation between the center position and the actual processing position can be corrected, and the center position of the line to be processed next can be positioned vertically below the condenser 254. Therefore, the workpiece 1 can be subjected to high-precision laser processing along the first scheduled division line 11 and the second scheduled division line 13.

  In addition, after calculating the amount of deviation between the line to be processed and the processing position where the modified region of the lower layer is formed, the modified region of the uppermost layer is formed above the modified region of the lower layer that has been formed. The calculated shift amount is used for correction when the center position of the next processing target line is positioned vertically below the condenser 254. Therefore, all the modified regions of the plurality of layers formed for the same processing target line can be formed at the same position on the Y coordinate, and the division quality is not deteriorated.

  In the above-described embodiment, every time laser processing is performed on all the first scheduled division lines 11 and second scheduled division lines 13, the machining positions are detected to calculate the deviation amounts, and the positional deviations are calculated. I decided to correct it. On the other hand, instead of performing the correction every time, a configuration may be adopted in which the processing position is detected for each predetermined number of lines, the amount of deviation is calculated, and the position deviation is corrected. Alternatively, a configuration may be adopted in which when the laser processing is performed on a predetermined line set in advance as the correction, the processing position is detected and the amount of shift is calculated to correct the position shift. The number of lines to be corrected and which line is to be corrected when laser processing may be configured so that the setting can be appropriately changed according to a user operation, for example. According to this, it is possible to periodically calculate the amount of deviation between the processing target line and the actual machining position, and to correct the position deviation.

  As described above, the processing method of the present invention is suitable for performing high-precision laser processing along a planned division line on a workpiece while properly detecting the processing position.

DESCRIPTION OF SYMBOLS 1 Workpiece 11 1st division plan line 13 2nd division plan line 15 Device 2 Processing apparatus 21 Holding means 23 X drive means 24 Y drive means 25 Laser processing means 253 Laser irradiation unit 255 Imaging unit 27 Z drive means 29 Control means

Claims (1)

For a plate-like workpiece having a surface on the XY coordinates and a plurality of division lines determined on the surface being arranged along the X coordinate direction, pulse laser irradiation means are sequentially applied in the Y coordinate direction. Indexed and positioned to be a division line to be processed, a pulsed laser beam having a wavelength that passes through the workpiece while the pulse laser irradiation means is processed and fed in the X-coordinate direction is a condensing point inside the workpiece. A plurality of modified regions having different positions on the Z-coordinate orthogonal to the front surface are sequentially stacked from the back side of the workpiece,
In the process of forming the plurality of modified regions along the division line to be processed, the work piece is allowed to penetrate through the workpiece before forming the modified region on the most Z-coordinate position. The modified region that has been formed is imaged along the planned division line of the processing object using an imaging unit that captures the image, and the position of the formed modified region on the Y coordinate is detected to divide the processing target A deviation amount calculating step for calculating a deviation amount from a position on the Y coordinate of the planned line;
When the pulse laser irradiating means is indexed and fed in the Y-coordinate direction and positioned next on the planned division line to be processed, the pulse laser is shifted by an amount corresponding to the deviation amount, and the index feed position determined by the distance between the planned division lines is shifted. A positioning step of indexing and feeding the irradiation means;
The processing method characterized by including.

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