Method for dividing a disc-shaped wafer
The method enhances the division of wafers with back-surface films by using alignment marks and controlled machining grooves to address detection and warpage issues, improving splitting quality and chip integrity.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- DISCO CORP
- Filing Date
- 2021-11-22
- Publication Date
- 2026-05-29
Smart Images
Figure 0007867332000001 
Figure 0007867332000002 
Figure 0007867332000003
Abstract
Description
Technical Field
[0001] The present invention relates to a method for dividing a disc-shaped wafer on which a film is formed on the back surface. disc-shaped wafer into which a film is formed on the back surface.
Background Art
[0002] There is known a method of improving the dividing quality of a workpiece by dividing a workpiece having a film made of a material different from the base material layer of the workpiece formed on the back surface from both the front surface and the back surface (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, when the film formed on the back surface is a material that does not transmit infrared rays, there is a problem that the division planned line formed on the front surface cannot be detected by an infrared camera from the back surface, and thus a processing groove cannot be formed from the back surface. In addition, when different materials are laminated, warpage occurs in the workpiece, and there is a problem that chipping may occur during division due to the warpage.
[0005] The present invention has been made in view of such problems, and an object thereof is to improve the division quality of a workpiece (wafer) on which a film made of a material different from the base material layer of the workpiece is formed (wafer) more than before. disc-shaped wafer is to provide a division method.
Means for Solving the Problems
[0006] In order to solve the above-described problems and achieve the object, the disc-shaped waferThe division method has a plurality of division lines formed on the surface in a first direction and a second direction intersecting the first direction, and on the back surface wafer A film made of a different material from the base layer is formed. disc-shaped wafer Divide it along the planned division line. disc-shaped wafer A method of division, The wafer From the surface, outside the outermost dividing line, there is a predetermined positional relationship with the dividing line, The wafer An alignment mark formation step is performed, in which a first machined groove extending to the back surface is formed as an alignment mark for detecting the position of the planned division line from the back surface, and after the alignment mark formation step is performed, The wafer From the back side, the planned division line is detected based on the alignment mark, and at least the film is removed along the planned division line, and, The wafer A film removal step to form a second processing groove of a depth that does not completely divide the film, and after the film removal step has been performed, The wafer A third machining groove is formed from the surface side along the planned division line to a depth reaching the second machining groove. The wafer A division step for dividing the, The alignment mark forming step involves forming the alignment mark outside the outermost dividing line by the distance between adjacent dividing lines. The splitting step involves forming a third machining groove along any planned splitting line. The wafer Dividing it into major parts, The wafer The method is characterized by reducing the warping and then forming a third machining groove along the remaining planned division line.
[0007] The film may be a metal film.
[0008] Applicable The alignment mark forming step may involve forming two first machining grooves extending along the first direction and the second direction, respectively, as the alignment marks. [Effects of the Invention]
[0009] This invention can improve the splitting quality of workpieces in which a film of a different material from the base layer of the workpiece is formed on the back surface, compared to conventional methods. [Brief explanation of the drawing]
[0010] [Figure 1] FIG. 1 is a top view showing a configuration example of a workpiece dividing system that implements a workpiece dividing method according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing a configuration example of a workpiece to be divided by the workpiece dividing method according to an embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing a main part of the tape replacement device in FIG. 1. [Figure 4] FIG. 4 is a cross-sectional view showing a main part of the tape replacement device in FIG. 1. [Figure 5] FIG. 5 is a perspective view showing a configuration example of the dividing processing device in FIG. 1. [Figure 6] FIG. 6 is a perspective view showing another configuration example of the dividing processing device in FIG. 1. [Figure 7] FIG. 7 is a flowchart showing the processing procedure of the workpiece dividing method according to an embodiment. [Figure 8] FIG. 8 is a cross-sectional view for explaining an example of the alignment mark forming step in FIG. 7. [Figure 9] FIG. 9 is a top view for explaining an example of the alignment mark forming step in FIG. 7. [Figure 10] FIG. 10 is a cross-sectional view for explaining an example of the film removing step in FIG. 7. [Figure 11] FIG. 11 is a top view for explaining an example of the film removing step in FIG. 7. [Figure 12] FIG. 12 is a cross-sectional view for explaining an example of the dividing step in FIG. 7. [Figure 13] FIG. 13 is a top view for explaining an example of the dividing step in FIG. 7. [Figure 14] FIG. 14 is a top view for explaining another example of the dividing step in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION
[0011] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by those skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the present invention.
[0012] [Embodiment] A method for dividing a workpiece according to an embodiment of the present invention will be described based on the drawings. Figure 1 is a top view showing an example of the configuration of a workpiece dividing system 1 that implements the workpiece dividing method according to the embodiment. Figure 2 is a perspective view showing an example of the configuration of a workpiece 100 that is to be divided by the workpiece dividing method according to the embodiment. Figures 3 and 4 are cross-sectional views showing the main parts of the tape replacement device 10 of Figure 1. Figure 5 is a perspective view showing an example of the configuration of the dividing processing device 20 of Figure 1. Figure 6 is a perspective view showing another example of the configuration of the dividing processing device 20 of Figure 1. Note that the film 120 is not shown in Figures 3 to 6. The workpiece dividing system 1 that implements the workpiece dividing method according to the embodiment includes, as shown in Figure 1, a tape replacement device 10, three dividing processing devices 20, a transport device 30, and a control unit 40. In the workpiece splitting system 1, the tape replacement device 10 and the three splitting devices 20 are arranged in one horizontal direction (the Y-axis direction in Figure 1) in this embodiment, and the transport device 30 is provided adjacent to the tape replacement device 10 and the three splitting devices 20 in a direction perpendicular to this arrangement direction (the X-axis direction in Figure 2). However, the arrangement of the tape replacement device 10, the three splitting devices 20 and the transport device 30 is not limited to this in the present invention.
[0013] In this embodiment, the workpiece 100, which is the object to be divided by the workpiece division method, is, for example, a disc-shaped semiconductor wafer or optical device wafer with a base material, i.e., a substrate layer 110, such as silicon, sapphire, silicon carbide (SiC), gallium arsenide, or glass. As shown in Figure 2, the workpiece 100 has a flat surface 101, and devices 103 (device chips) are formed in regions demarcated by a plurality of division lines 102 formed along a first direction 201 and a second direction 202 intersecting the first direction 201. In this embodiment, the workpiece 100 is further formed with a grid of division lines 102, where the first direction 201 and the second direction 202 are orthogonal to each other, but the present invention is not limited to this. The workpiece 100 has a device region 105, which is the region where the device 103 is formed, and an outer peripheral excess region 106, which surrounds the device region 105 and is the region where the device 103 is not formed. In this invention, the workpiece 100 may be a rectangular package substrate, a ceramic plate, or a glass plate, etc., having a plurality of devices sealed with resin.
[0014] The workpiece 100 has a pattern layer formed on its surface 101, which includes circuits and electrodes that form the device 103, and a film 120 formed on its back surface 104 that is thinner than the base layer 110 and made of a different material from the pattern layer and base layer 110. Here, the difference in materials between the pattern layer and base layer 110 and the film 120 means, in this invention, that due to the properties of the materials, at least one of the processing conditions and processing load when the pattern layer and base layer 110 and the film 120 are processed by cutting or laser processing will be different. Because the pattern layer and base layer 110 and the film 120 are made of different materials, their coefficients of thermal expansion and the like are different, so the workpiece 100 has warping. The film 120 is, for example, a heat sink for heat dissipation in the device 103, and can be a laminated structure of titanium and copper, a laminated structure of nickel, platinum and gold, a laminated structure of nickel and gold, or a single layer structure of silver.
[0015] As shown in Figure 2, the workpiece 100 has adhesive tape 107 attached to it, and an annular frame 108 is attached to the outer edge of the adhesive tape 107. In the example shown in Figure 2, the adhesive tape 107 is attached to the back surface 104 side of the workpiece 100, but in the workpiece division method according to the embodiment, the adhesive tape 107 may be attached to the front surface 101 side by the tape replacement device 10. Alternatively, instead of adhesive tape 107, a thermoplastic resin may be heated and softened before being attached to the workpiece 100.
[0016] As shown in Figures 3 and 4, the tape replacement device 10 includes a holding table 11, a roller 12 that rotates and moves with the rotation around an axis parallel to the horizontal direction, a cutting blade 13 that rotates and moves around an axis parallel to the vertical direction, a peeling unit 14, a control unit 15, and an ultraviolet irradiator (not shown). The tape replacement device 10 replaces the adhesive tape 107 attached to one side of the workpiece 100 and the annular frame 108 with the other side.
[0017] Specifically, the tape replacement device 10 first irradiates the adhesive tape 107 of the workpiece 100 and annular frame 108, which have adhesive tape 107 attached to one side, with ultraviolet light using an ultraviolet irradiator (not shown) to reduce the adhesive strength of the adhesive layer of the adhesive tape 107. Next, as shown in Figure 3, the tape replacement device 10 supports the side of the workpiece 100 and annular frame 108 to which the adhesive tape 107 is attached with the holding table 11, exposing the other side to which the adhesive tape 107 is not attached. The tape replacement device 10 then rotates the roller 12 from one end to the other end of the other side of the workpiece 100 and annular frame 108 via the adhesive tape 107 with the adhesive layer side facing the workpiece 100 and annular frame 108, thereby attaching the adhesive tape 107 sequentially from one end of the other side of the workpiece 100 and annular frame 108. The tape replacement device 10 cuts the portion of the adhesive tape 107 that extends radially beyond the annular frame 108 by using a cutting blade 13 to cut into the workpiece 100 and the adhesive tape 107 attached to the other side of the annular frame 108 on the annular frame 108 and rotating it. After removing the excess portion of the adhesive tape 107, the tape replacement device 10 flips the workpiece 100 and the annular frame 108, which have adhesive tape 107 attached to both sides, on the holding table 11, as shown in Figure 4, and peels off the adhesive tape 107 that has been attached to the upward-facing side and has lost its adhesive strength using the peeling unit 14. In this way, the tape replacement device 10 can replace the adhesive tape 107 from one side to the other without changing the positional relationship between the workpiece 100 and the annular frame 108 by temporarily sandwiching the workpiece 100 with adhesive tape 107 attached to both sides.
[0018] Furthermore, the tape replacement device 10 can also apply adhesive tape 107 to one side of a workpiece 100 that does not have adhesive tape 107 applied to either side, together with the annular frame 108, using the roller 12. In addition, the tape replacement device 10 can also peel off the adhesive tape 107 applied to one side of a workpiece 100 and annular frame 108 that has adhesive tape 107 applied to one side, using the peeling unit 14, without applying adhesive tape 107 to the other side.
[0019] The control unit 15 controls the operation of each component of the tape replacement device 10, causing the tape replacement device 10 to perform the application and removal processes of adhesive tape 107. In this embodiment, the control unit 15 includes a computer system. The computer system included in the control unit 15 includes an arithmetic processing unit having a microprocessor such as a CPU (Central Processing Unit), a storage device having memory such as ROM (Read Only Memory) or RAM (Random Access Memory), and an input / output interface device. The function of the control unit 15 is realized by the arithmetic processing unit of the computer system performing arithmetic processing according to a computer program stored in the storage device of the computer system, and outputting control signals for controlling the tape replacement device 10 to each component of the tape replacement device 10 via the input / output interface device of the tape replacement device 10.
[0020] The splitting device 20 forms processing grooves 131, 132, and 133 (see Figures 8 to 14) in the workpiece 100. In this embodiment, each splitting device 20 is either splitting device 20-1, which is a cutting device as shown in Figure 5, or splitting device 20-2, which is a laser processing device as shown in Figure 6. As shown in Figures 5 and 6, the splitting device 20 comprises a chuck table 21, a processing unit 22, a shooting unit 23, a moving unit 24, and a control unit 25.
[0021] Hereinafter, when distinguishing between the different splitting devices 20, they will be referred to as the first splitting device 20, the second splitting device 20, and the third splitting device 20. The processing unit 22 of the first splitting device 20 will be referred to as the first processing unit 22, the processing unit 22 of the second splitting device 20 as the second processing unit 22, and the processing unit 22 of the third splitting device 20 as the third processing unit 22. The first, second, and third processing units 22 each have different processing conditions and processing loads for the workpiece 100. The first processing unit 22 preferably forms a first processing groove 131 that penetrates the base layer 110, the pattern layer formed on the surface of the base layer 110, and the film 120 of the workpiece 100 in the thickness direction. The second processing unit 22 forms a high-quality second processing groove 132 in the film 120. The third processing unit 22 forms high-quality third processing grooves 133 in the base layer 110 and the pattern layer formed on the surface of the base layer 110. In this embodiment, the workpiece splitting system 1 has the first splitting device 20, the second splitting device 20, and the third splitting device 20 arranged in this order. Note that the first, second, and third processing units 22 are not each provided in an independent splitting device 20, and two or more may be provided in a single splitting device 20.
[0022] In this embodiment, the chuck table 21 is a so-called chuck table having, for example, a disc-shaped frame with a recess formed therein, and a disc-shaped suction part fitted into the recess. The suction part of the chuck table 21 is formed from a porous ceramic or the like and is connected to a vacuum suction source (not shown) via a vacuum suction path (not shown). The upper surface of the suction part of the chuck table 21 is a holding surface on which the workpiece 100 is placed and which holds the placed workpiece 100 by suction. In this embodiment, the workpiece 100 is placed with the side not to which the adhesive tape 107 is not attached facing upward, and the placed workpiece 100 is held by suction via the adhesive tape 107. The holding surface and the upper surface of the frame of the chuck table 21 are arranged on the same plane and are formed parallel to the horizontal plane (the XY plane in Figures 5 and 6).
[0023] In the splitting processing device 20-1, the processing unit 22 is a processing unit 22-1 (cutting unit) equipped with a spindle to which a cutting blade is mounted at its tip, as shown in Figure 5. In the processing unit 22-1, the cutting blade mounted at the tip of the spindle is subjected to rotational motion around an axis parallel to one horizontal direction (the Y-axis direction in Figure 5) by the rotational motion of the spindle, cutting the workpiece 100 held in the chuck table 21 to form processing grooves 131, 132, 133 (cutting grooves). The annular cutting edge of the cutting blade that cuts the workpiece 100 is made up of abrasive grains such as diamond or CBN (Cubic Boron Nitride) and a bonding material (binder) such as metal or resin, and is formed to a predetermined thickness.
[0024] In the processing unit 22-1, the processing conditions and processing load for high-quality cutting of the base layer 110 and the pattern layer formed on the surface of the base layer 110, the processing conditions and processing load for high-quality cutting of the film 120, and the processing conditions and processing load for suitably cutting through the base layer 110, pattern layer, and film 120 of the workpiece 100 in the thickness direction are all different from each other. Here, the processing conditions and processing load of the processing unit 22-1 also include those due to each component of the processing unit 22-1, such as the material and rotational speed of the cutting blade. For example, the cutting blade that forms the third processing groove 133 by high-quality cutting of the base layer 110 and the pattern layer has a cutting edge composed of relatively fine abrasive grains. The cutting blade that forms the second processing groove 132 by high-quality cutting of the film 120 has a cutting edge composed of relatively large abrasive grains.
[0025] Furthermore, the cutting blade that forms the first machining groove 131, which preferably cuts through the base layer 110, pattern layer, and film 120 of the workpiece 100 in the thickness direction, has, for example, a cutting edge composed of abrasive grains of an intermediate size between the two mentioned above. Alternatively, if the cutting blade that forms the first machining groove 131 cuts at a position that does not become the end face of the chipped device 103, it does not affect the quality of the device 103, so the cutting blade that forms the second machining groove 132 or the third machining groove 133 may also be used. Note that when forming the first machining groove 131, different materials are machined simultaneously, which increases the machining load. This may adversely affect the cutting blade that cuts the second machining groove 132 or the third machining groove 133, and the high machining load may worsen the quality of the end face of the first machining groove 131, potentially affecting the accuracy of the alignment. Therefore, if quality such as chipping and alignment is important, it is preferable to select a cutting blade suitable for forming the first machining groove 131.
[0026] In this embodiment, the cutting blades that form the first machining groove 131, the second machining groove 132, and the third machining groove 133 are each supported on the spindles of the first, second, and third splitting devices 20-1. However, the present invention is not limited to this, and any one of the splitting devices 20-1 may have two or more spindles, and any two or more of the cutting blades that form the first machining groove 131, the second machining groove 132, and the third machining groove 133 may be supported on the spindles.
[0027] In the splitting processing device 20-2, as shown in Figure 6, processing unit 22-2 (laser processing unit) irradiates a workpiece 100 held on the chuck table 21 with a laser beam and laser processes the workpiece 100 with the laser beam. Processing unit 22-2 irradiates the workpiece 100 with a laser beam of a wavelength that absorbs it, and performs so-called ablation processing, which ablates (sublimates or evaporates) the workpiece 100 with this laser beam, to form processing grooves 131, 132, and 133 (laser processing grooves). The third processing groove 133 may be formed not by ablation processing, but by focusing a laser beam of a wavelength that penetrates the workpiece 100 into the interior of the workpiece 100 and irradiating it with this laser beam, thereby forming a modified layer and cracks extending from the modified layer to the front and back surfaces inside the workpiece 100, and the modified layer or cracks may be considered as the third processing groove 133.
[0028] In processing unit 22-2, the processing conditions and processing load for high-quality laser processing of the base layer 110 and the pattern layer formed on the surface of the base layer 110, the processing conditions and processing load for high-quality laser processing of the film 120, and the processing conditions and processing load for suitably laser processing and penetrating the base layer 110, pattern layer, and film 120 of the workpiece 100 in the thickness direction are all different from each other. Here, the processing conditions and processing load of processing unit 22-2 also include those due to each component of processing unit 22-2, such as the wavelength and intensity of the laser beam.
[0029] The processing conditions and load for forming a first processing groove 131 that penetrates the base layer 110, pattern layer, and film 120 of the workpiece 100 by laser processing them in the thickness direction are, for example, intermediate between the processing conditions and load for forming a third processing groove 133 by high-quality cutting of the base layer 110 and pattern layer, and the processing conditions and load for forming a second processing groove 132 by high-quality cutting of the film 120. Alternatively, if the processing conditions and load for forming the first processing groove 131 are cut at a location that does not become the end face of the chipped device 103, the quality of the device 103 will not be affected, so the processing conditions and load for forming the second processing groove 132 or the third processing groove 133 may also be used. Furthermore, since different materials are processed simultaneously when forming the first machining groove 131, the machining load becomes high, which may affect the alignment accuracy due to poor quality of the end face of the first machining groove 131. Therefore, when quality such as chipping and alignment is important, it is preferable to select machining conditions and a machining load suitable for forming the first machining groove 131.
[0030] Furthermore, the first machining groove 131, the second machining groove 132, and the third machining groove 133 may be machined using either the machining unit 22-1 or the machining unit 22-2 in each step, and the first machining groove 131 and the third machining groove 133 may be formed using the machining unit 22-1, and the second machining groove 132 may be formed using the machining unit 22-2, and so on, and can be combined as appropriate.
[0031] The imaging unit 23 is equipped with an image sensor that images the planned division lines 102 of the workpiece 100 held on the chuck table 21, as well as the machining grooves 131, 132, 133, etc., formed on the workpiece 100 by the machining unit 22. The image sensor is, for example, a CCD (Charge-Coupled Device) image sensor or a CMOS (Complementary MOS) image sensor. In both the division processing apparatus 20-1 and 20-2, the imaging unit 23 is fixed to the machining unit 22 and moves together with the machining unit 22 relative to the chuck table 21.
[0032] The imaging unit 23 photographs the workpiece 100 and machining groove 131 held on the chuck table 21 to obtain images for purposes such as alignment, which involves positioning the workpiece 100 with the machining unit 22, and outputs the obtained images to the control unit 25. The imaging unit 23 also photographs the machined workpiece 100 held on the chuck table 21 to obtain images for purposes such as performing a so-called kerf check, which automatically verifies whether the machining grooves 132 and 133 are within the planned division lines 102 and whether any large chips or other defects have occurred, and outputs the obtained images to the control unit 25. The imaging unit 23 may be, for example, an infrared camera or a visible light camera.
[0033] The moving unit 24 moves the chuck table 21 and the processing unit 22 relative to each other. In the splitting processing device 20-1, the moving unit 24 moves the chuck table 21 along the X-axis relative to the processing unit 22, and moves the processing unit 22 along the Y-axis and Z-axis relative to the chuck table 21. In the splitting processing device 20-2, the moving unit 24 moves the chuck table 21 along the X-axis and Y-axis relative to the processing unit 22. The moving unit 24 detects the relative positions of the processing unit 22 and the imaging unit 23 with respect to the chuck table 21 and outputs the detected position information to the control unit 25.
[0034] The moving unit 24 retracts the processing unit 22 from the chuck table 21, making it possible to load and unload the workpiece 100 onto the chuck table 21. The moving unit 24 aligns the chuck table 21 and the processing unit 22 before processing. The moving unit 24 moves the driving processing unit 22 relative to the workpiece 100 on the chuck table 21 to perform processing on the workpiece 100 by the processing unit 22. In the splitting processing device 20 of this embodiment, the first direction 201 or the second direction 202 is aligned with the X-axis direction of the splitting processing device 20, and the moving unit 24 moves the driving processing unit 22 relative to the workpiece 100 on the chuck table 21 along the X-axis direction to perform processing along the first direction 201 or the second direction 202.
[0035] The control unit 25 controls the operation of each component of the splitting device 20, causing the splitting device 20 to perform the processing by the processing unit 22. In this embodiment, the control unit 25 includes a computer system similar to the control unit 15 of the tape replacement device 10. The function of the control unit 25 is realized by the arithmetic processing unit of the computer system included in the control unit 25 performing calculations according to a computer program stored in the computer system's storage device, and outputting control signals for controlling the splitting device 20 to each component of the splitting device 20 via the input / output interface device of the splitting device 20.
[0036] As shown in Figure 1, the transport device 30 comprises a rail 31, a transport unit 32, and a control unit 35. The rail 31 is arranged to extend along the direction of arrangement of the tape replacement device 10 and the three division processing devices 20. The transport unit 32 holds the workpiece 100 and transports the workpiece 100 by moving along the rail 31. In this embodiment, the rail 31, which is the transport path by the transport unit 32, is provided along the Y-axis direction in Figure 1, but the present invention is not limited to this and can be appropriately changed depending on the arrangement of the tape replacement device 10, the three division processing devices 20, and the transport device 30. In this embodiment, the transport unit 32 is, for example, a robot pick equipped with a circular hand, which uses the circular hand to suction and hold the workpiece 100 and transport the workpiece 100 between the tape replacement device 10 and the three division processing devices 20. The transport unit 32 is not limited to this in the present invention, and may be a non-contact type that generates negative pressure on the lower surface by Bernoulli's principle by spraying a predetermined amount of air along the lower surface, and uses this negative pressure to suction and hold the workpiece 100 using the lower surface as a holding surface to transport the workpiece 100.
[0037] The control unit 35 controls the operation of each component of the transport device 30, causing the transport device 30 to perform the transport process by the transport unit 32. In this embodiment, the control unit 35 includes a computer system similar to the control unit 15 of the tape replacement device 10 and the control unit 25 of the splitting processing device 20. The function of the control unit 35 is realized by the arithmetic processing unit of the computer system included in the control unit 35 performing calculations according to a computer program stored in the computer system's storage device, and outputting control signals for controlling the transport device 30 to each component of the transport device 30 via the input / output interface device of the transport device 30.
[0038] The control unit 40 controls the operation of the workpiece splitting system 1 and causes the workpiece splitting system 1 to implement the workpiece splitting method according to the embodiment. The control unit 40 comprehensively controls the tape replacement device 10, the three splitting devices 20, and the transport device 30 that constitute the workpiece splitting system 1 via the control units 15, 25, and 35. In this embodiment, the control unit 40 includes a computer system similar to the control units 15, 25, and 35. The function of the control unit 40 is realized by the arithmetic processing unit of the computer system included in the control unit 40 performing calculations according to a computer program stored in the storage device of the computer system and outputting control signals for controlling the workpiece splitting system 1 to each component (each device) of the workpiece splitting system 1 via the input / output interface device of the workpiece splitting system 1.
[0039] In this embodiment, the workpiece splitting system 1 includes a tape replacement device 10, a first splitting device 20, a second splitting device 20, and a third splitting device 20, all of which are connectable by a transport device 30. However, the present invention is not limited to this, and it is not necessary for all of the tape replacement device 10, the first splitting device 20, the second splitting device 20, and the third splitting device 20 to be connectable by the transport device 30. Any of the devices may be independently provided in a position not transported by the transport device 30.
[0040] Next, this specification will describe the operation of the workpiece division method according to the embodiment with reference to the drawings. Figure 7 is a flowchart showing the processing procedure of the workpiece division method according to the embodiment. Figures 8 and 9 are a cross-sectional view and a top view illustrating an example of the alignment mark formation step 1001 of Figure 7, respectively. Figures 10 and 11 are a cross-sectional view and a top view illustrating an example of the film removal step 1002 of Figure 7, respectively. Figures 12 and 13 are a cross-sectional view and a top view illustrating an example of the division step 1003 of Figure 7. Figure 14 is a top view illustrating another example of the division step 1003 of Figure 7. Note that in Figures 8, 9, and 11 to 14, the components of the division processing apparatus 20 are not shown, and in Figure 10, the components of the division processing apparatus 20 other than the imaging unit 23 are not shown. Furthermore, in Figures 9, 11, 13, and 14, the adhesive tape 107 and the annular frame 108 are also not shown. The workpiece division method according to the embodiment is an example of the operation process performed by the workpiece division system 1, and as shown in Figure 7, comprises an alignment mark formation step 1001, a film removal step 1002, and a division step 1003.
[0041] In the workpiece division method according to this embodiment, the control unit 40 transports the workpiece 100, before the first machining groove 131 is formed, to the tape replacement device 10 by the transport device 30 before performing the alignment mark formation step 1001. The tape replacement device 10 then attaches adhesive tape 107 to the back surface 104 of the workpiece 100 and attaches an annular frame 108 to the outer edge of the adhesive tape 107.
[0042] The alignment mark formation step 1001 is a step in which a first machining groove 131, which is a through groove extending from the surface 101 of the workpiece 100 to the back surface 104 of the workpiece 100 and having a predetermined positional relationship with the division line 102, is formed as an alignment mark for detecting the position of the division line 102 from the back surface 104, as shown in Figures 8 and 9. Here, the statement that the first machining groove 131 has a predetermined positional relationship with the division line 102 means that the control unit 40 can detect the extending direction and position of each division line 102 based on the information of the extending direction and position of the first machining groove 131 formed in the alignment mark formation step 1001. Specifically in this embodiment, the predetermined positional relationship is determined by the angle information between each division line 102 and the extending direction of the first machining groove 131 and the distance information between each division line 102 and the first machining groove 131.
[0043] In alignment mark formation step 1001, the control unit 40 first transports the workpiece 100, which has adhesive tape 107 attached to its back surface 104 and an annular frame 108 mounted on it, to the first splitting processing device 20 using the transport device 30. As shown in Figure 8, the workpiece 100 is held by suction on the chuck table 21 of the first splitting processing device 20 with the front surface 101 side exposed upwards. Next, in alignment mark formation step 1001, the control unit 40 uses the first processing unit 22 of the first splitting processing device 20 to perform a full cut on the workpiece 100 on the chuck table 21 from the front surface 101 side, forming a first processing groove 131 that penetrates both the base material layer 110 and the film 120 of the workpiece 100 in the thickness direction.
[0044] The alignment mark formation step 1001 forms the first processing groove 131 in this manner. Therefore, even if the film 120 is made of a material that does not transmit light received by the imaging unit 23 during imaging, detecting the first processing groove 131 makes it possible to detect the division line 102 formed on the front surface 101 side from the back surface 104 side and perform alignment. Here, the light received by the imaging unit 23 during imaging is, for example, infrared light if the imaging unit 23 is an infrared camera, and visible light if the imaging unit 23 is a visible light camera.
[0045] Since the processing conditions for forming high-quality processing grooves 133 and 132 on the base layer 110 and the film 120, on which the pattern layers of the workpiece 100 are laminated, are different, if the first processing groove 131 is formed by the first processing unit 22 of the first division processing device 20 with a single processing condition, there is a risk of large chipping occurring on the surface 101 side or the back surface 104 side. For this reason, in the alignment mark formation step 1001, as shown in Figures 8 and 9 of this embodiment, it is preferable for the control unit 40 to form the alignment mark (first processing groove 131) outside the outermost division planned line 102, which is the end face of the device 103 (device chip) formed at the boundary between the device area 105 and the outer peripheral excess area 106, i.e., in the outer peripheral excess area 106. This makes it possible to form the first processing groove 131 without affecting the quality of the device 103.
[0046] In the alignment mark formation step 1001, the control unit 40, in this embodiment as shown in Figure 9, forms two first machining grooves 131 extending along the first direction 201 and the second direction 202, respectively, outside the outermost division line 102 by a distance (1 index) between adjacent division lines 102, and stores information (distance information) of the distance between the first machining groove 131 along the first direction 201 and each division line 102 along the first direction 201, and the distance between the first machining groove 131 along the second direction 202 and each division line 102 along the second direction 202, as a predetermined positional relationship. In the alignment mark formation step 1001, it is preferable to form the first machining groove 131 parallel to the division line 102, thereby eliminating the need to store and adjust the angle between the first machining groove 131 and the division line 102 during the alignment in the film removal step 1002. However, the present invention is not limited to this, and the first machining groove 131 does not have to be formed parallel to the division line 102 during the alignment mark formation step 1001. In this case, the control unit 40 stores information (angle information) about the angle between the direction in which the first machining groove 131 extends and the division line 102, which is further required for the alignment in the film removal step 1002. Furthermore, in the alignment mark formation step 1001, the first machining groove 131 along the first direction 201 and the first machining groove 131 along the second direction 202 may be intersected and formed in one place like a cross mark.
[0047] In the workpiece division method according to the embodiment, after the alignment mark formation step 1001 and before the film removal step 1002, the control unit 40 transports the workpiece 100, which has had the first processing groove 131 formed but has not yet had the second processing groove 132 formed, to the tape replacement device 10 using the transport device 30. The tape replacement device 10 then replaces the adhesive tape 107 from the back surface 104 to the front surface 101 of the workpiece 100 and the annular frame 108. Fragments that do not include the device 103, which were divided when the first processing groove 131 was formed, may be removed when the adhesive tape 107 is replaced. If the fragments are removed, the end face portion that constitutes the first processing groove 131 remaining on the workpiece 100 functions as an alignment mark in the film removal step 1002.
[0048] As shown in Figures 10 and 11, the film removal step 1002 is a step in which, after the alignment mark formation step 1001 is performed, the division line 102 is detected from the back surface 104 side of the workpiece 100 based on the alignment mark (first machining groove 131), and a second machining groove 132 is formed along the division line 102 to a depth that removes at least the film 120 and does not completely divide the workpiece 100.
[0049] In the film removal step 1002, the control unit 40 first transports the workpiece 100, which has a first processing groove 131 formed on it and an annular frame 108 attached to its surface 101 by the transport device 30, to the second dividing processing device 20. The chuck table 21 of the second dividing processing device 20 then holds the workpiece 100 by suction with the film 120 on the back surface 104 side exposed upwards. In the film removal step 1002, the control unit 40 then, as shown in Figure 10, uses the imaging unit 23 of the second splitting device 20 to photograph and detect the first machining groove 131 (end face portion) from the back surface 104 side of the workpiece 100. Based on the detected position information of the first machining groove 131 (end face portion) and the distance information (and angle information) between the first machining groove 131 (end face portion) and each planned splitting line 102, the control unit 40 detects each planned splitting line 102. In the film removal step 1002, the control unit 40 then performs alignment to align each detected planned splitting line 102 with the second machining unit 22 of the second splitting device 20.
[0050] In the film removal step 1002, after performing alignment, the control unit 40 uses the second processing unit 22 of the second splitting device 20 to process and remove at least the film 120 along the previously detected splitting line 102 from the back surface 104 side of the workpiece 100, and to form a second processing groove 132 of a depth that does not completely split the workpiece 100. That is, in the film removal step 1002, a half-cut process is performed along the splitting line 102 to form a second processing groove 132 that is at least as deep as the thickness of the film 120 and less than the combined thickness of the base layer 110 and the film 120 of the workpiece 100. In the film removal step 1002, as shown in Figure 11, the control unit 40 forms the second processing groove 132 from the back surface 104 side of the workpiece 100 along all the splitting lines 102. It is preferable that the second processing groove 132 is shallower than the third processing groove 133, which will be described later.
[0051] In the film removal step 1002, since the second processing unit 22 of the second splitting apparatus 20 is used, the film 120 can be processed with high quality to form the second processing groove 132, but the processing quality of the base layer 110 is a concern. For this reason, in the film removal step 1002, it is preferable that the depth to which the base layer 110 is processed when forming the second processing groove 132 is shallower, that is, it is preferable that the difference between the depth of the second processing groove 132 to be formed and the thickness of the film 120 is small. Also, in the workpiece splitting method according to the embodiment, since the film 120 is thinner than the base layer 110, it is preferable to process the film 120 before the base layer 110 in the film removal step 1002. Furthermore, in the workpiece splitting method according to the embodiment, it is preferable that the second processing groove 132 formed by processing the film 120 in the film removal step 1002 is formed shallower than the third processing groove 133 formed by processing the base layer 110 in the splitting step 1003 described later. These measures reduce and suppress the risk of cracks occurring in the workpiece 100, starting from the second processing groove 132, when transporting the workpiece 100 after the film removal step 1002 or when replacing the adhesive tape 107.
[0052] In the workpiece division method according to the embodiment, after the film removal step 1002 and before the division step 1003, the control unit 40 transports the workpiece 100, which has had the second processing groove 132 formed but has not yet had the third processing groove 133 formed, to the tape replacement device 10 by the transport device 30, and the tape replacement device 10 replaces the adhesive tape 107 from the front surface 101 to the back surface 104 of the workpiece 100 and the annular frame 108.
[0053] The splitting step 1003 is a step in which, after the film removal step 1002 has been performed, a half-cut is made from the surface 101 side of the workpiece 100 along the planned splitting line 102 to form a third processing groove 133 to a depth that reaches the second processing groove 132, thereby splitting the workpiece 100. Here, forming a third processing groove 133 to a depth that reaches the second processing groove 132 means forming the third processing groove 133 to a depth that reaches the bottom of the second processing groove 132, and connecting the bottom of the second processing groove 132 formed from the back surface 104 side and the bottom of the third processing groove 133 formed from the surface surface 101 side to form a single through groove.
[0054] In the splitting step 1003, for example, if a second processing groove 132 with a depth equivalent to the thickness of the film 120 was formed in the previous film removal step 1002, a third processing groove 133 with a depth equivalent to the thickness of the base layer 110 and the pattern layer is formed. In this case, the film 120 is processed from the back surface 104 side with processing conditions and processing load that allow for high-quality processing of the film 120 in the film removal step 1002, and the base layer 110 and the pattern layer are processed from the front surface 101 side with processing conditions and processing load that allow for high-quality processing of the base layer 110 and the pattern layer in the splitting step 1003, thus achieving the most desirable splitting quality of the workpiece 100.
[0055] In the splitting step 1003, the control unit 40 first transports the workpiece 100, which has a second processing groove 132 formed on it and an annular frame 108 attached to its back surface 104 by the transport device 30, to the third splitting device 20. The chuck table 21 of the third splitting device 20 then holds the workpiece 100 by suction with the front surface 101 side exposed upwards. In the splitting step 1003, the control unit 40 then uses the imaging unit 23 of the third splitting device 20 to photograph and detect the planned splitting line 102 and perform alignment.
[0056] In the splitting step 1003, after performing alignment, the control unit 40 forms a third machining groove 133 along an arbitrary portion of the planned splitting lines 102 to divide the workpiece 100 into larger sections and reduce the warping of the workpiece 100, and then forms a third machining groove 133 along the remaining planned splitting lines 102. Here, dividing the workpiece 100 into larger sections means dividing the workpiece 100 into aggregates containing multiple devices 103 that are larger than each individual device 103. Furthermore, it is preferable that the arbitrary portion of the planned splitting lines 102 do not include adjacent planned splitting lines 102 that are aligned in the same direction. In this case, the aggregates containing multiple devices 103 formed by the large division along the arbitrary portion of the planned splitting lines 102, and the aggregates of multiple devices 103, will both be longer than the device 103 in both the first direction 201 and the second direction 202.
[0057] In the splitting step 1003, after performing alignment, the control unit 40 first sets some of the planned splitting lines 102 to be processed first in order to divide the workpiece 100 into larger sections. In the splitting step 1003, the control unit 40 sets some of the planned splitting lines 102 for larger sections, skipping one line in the example shown in Figures 12 and 13, and setting a central planned splitting line 102 in the first direction 201 and a central planned splitting line 102 in the second direction 202 in the example shown in Figure 14. However, the present invention is not limited to this, and can be set as appropriate depending on the curvature properties of the workpiece 100.
[0058] In the splitting step 1003, the control unit 40 uses the third processing unit 22 of the third splitting device 20 to process the workpiece 100 from the surface 101 side, along a previously set portion of the planned splitting line 102 to be processed for large-scale splitting, to a depth reaching the second processing groove 132, thereby forming a third processing groove 133. In the splitting step 1003, the workpiece 100 is divided into large sections by connecting the bottom of the second processing groove 132 and the bottom of the third processing groove 133 along the portion of the planned splitting line 102 to form a through groove. In the division step 1003, in the examples shown in Figures 12 and 13, a large division is performed to divide the workpiece into an assembly having the length of two devices 103 along the second direction 202 and containing multiple devices 103 in two rows along the first direction 201. In the example shown in Figure 14, a large division is performed to divide the workpiece into an assembly having half the length of the entire workpiece 100 in both the first direction 201 and the second direction 202 and containing 1 / 4 of the devices 103 of the entire workpiece 100.
[0059] If the workpiece 100 is immediately divided into individual devices 103 along the planned division line 102, there is a risk that the height to be processed may shift due to the warping of the workpiece 100, or that the individual devices 103 may shift on the adhesive tape 107 due to the sudden and large release of the warping of the workpiece 100. Therefore, in the division step 1003, the workpiece 100 is divided into large aggregates containing multiple devices 103 with a mass greater than that of the individual devices 103, thereby partially releasing the warping of the workpiece 100 beforehand. This reduces the risk of these aggregates shifting on the adhesive tape 107 while effectively releasing the warping of the workpiece 100.
[0060] In the splitting step 1003, if the warping of the workpiece 100 is suitably mitigated by a large split along the first direction 201, it is preferable to set a portion of the planned splitting lines 102 for the large split, as shown in Figures 12 and 13. In this case, after processing the planned splitting lines 102 for the large split, the remaining planned splitting lines 102 along the first direction 201 and the planned splitting lines 102 along the second direction 202 can be processed sequentially in one go within the same flow. This allows for partial release and mitigation of the warping, while minimizing the distance that the chuck table 21 and the third processing unit 22 of the third splitting device 20 must move throughout the splitting step 1003, thus enabling faster completion of the processing. Furthermore, in the splitting step 1003, if the warping of the workpiece 100 is suitably mitigated by a large split along both the first direction 201 and the second direction 202, it is preferable to set a portion of the planned splitting lines 102 for the large split, as shown in Figure 14. In this case, the warping in both directions can be released and mitigated in a balanced manner.
[0061] In the splitting step 1003, the control unit 40, after dividing the workpiece 100 into large sections, forms a third machining groove 133 along the remaining planned splitting line 102 that was not machined during the large division, thereby dividing the workpiece 100 into individual pieces for each device 103.
[0062] In the workpiece division method according to the embodiment having the above configuration, first, a first processing groove 131 is formed on the surface 101 side, which serves as an alignment mark for detecting the planned division line 102 that can be detected from the back surface 104 side. Therefore, the planned division line 102 can be detected from the back surface 104 side based on this alignment mark. For this reason, the workpiece division method according to the embodiment makes it possible to divide the workpiece 100 by processing the base material layer 110, on which the film 120 and pattern layer are laminated, from the back surface 104 and the surface 101, respectively, and then half-cutting it. As a result, the workpiece division method according to the embodiment can form a second processing groove 132 on the back surface 104 side under processing conditions suitable for removing the film 120, and a third processing groove 133 on the surface 101 side under processing conditions suitable for processing the base material layer 110 and the pattern layer, thereby improving processing quality. Furthermore, in the workpiece division method according to the embodiment, when dividing the workpiece 100 by forming a third processing groove 133 from the surface 101, the large division is performed first, which partially releases and reduces the warping of the workpiece 100, allowing it to be divided into finer individual pieces, thereby further improving the processing quality. Thus, the workpiece division method according to the embodiment has the effect of improving the division quality of a workpiece 100 having a film 120 made of a different material from the base material layer 110 and the pattern layer formed on the back surface 104 compared to conventional methods.
[0063] Furthermore, in the workpiece division method according to the embodiment, since the film 120 of the workpiece 100 is a metal film, the processing conditions for high-quality processing of the base layer 110 and pattern layer and the film 120 are significantly different from each other. For this reason, the workpiece division method according to the embodiment can significantly improve processing quality compared to conventional methods by forming a second processing groove 132 from the back surface 104 side with processing conditions suitable for removing the film 120, and forming a third processing groove 133 from the front surface 101 side with processing conditions suitable for processing the base layer 110 and pattern layer.
[0064] Furthermore, in the workpiece division method according to the embodiment, in the alignment mark formation step 1001, a first machining groove 131 that will serve as an alignment mark is formed outside the outermost division line 102. Therefore, the workpiece division method according to the embodiment can suppress the risk that large chipping that may occur when forming the first machining groove 131 that will serve as an alignment mark may affect the quality of the device 103.
[0065] It should be noted that the present invention is not limited to the embodiments described above. That is, it can be implemented with various modifications without departing from the core principles of the present invention. [Explanation of symbols]
[0066] 1. Workpiece splitting system 10 Tape replacement device 20 division processing equipment 23 Filming Unit 30 Conveying device 40 Control Units 100 Workpiece 101 Surface 102 planned division lines 104 Back side 110 Base material layer 120 membrane 131 First machined groove 132 Second machining groove 133 Third machining groove 201 First Direction 202 Second Direction
Claims
1. A method for dividing a disc-shaped wafer, which has a plurality of division lines formed on its surface in a first direction and a second direction intersecting the first direction, and a film of a material different from the substrate layer of the wafer formed on its back surface, along the division lines, Alignment mark formation step: Forming a first processing groove on the surface of the wafer, outside the outermost dividing line, having a predetermined positional relationship with the dividing line, and extending to the back surface of the wafer, as an alignment mark for detecting the position of the dividing line from the back surface; After performing the alignment mark formation step, a film removal step is performed in which the planned division line is detected from the back side of the wafer based on the alignment mark, and a second processing groove is formed along the planned division line to a depth that removes at least the film and does not completely divide the wafer. The process includes, after performing the film removal step, a splitting step of forming a third processing groove from the surface side of the wafer along the planned splitting line to a depth reaching the second processing groove, and splitting the wafer, The alignment mark forming step involves forming the alignment mark outside the outermost dividing line by the distance between adjacent dividing lines. A method for dividing a disc-shaped wafer, characterized in that the dividing step involves forming a third processing groove along an arbitrary dividing line to divide the wafer into large sections to reduce the warping of the wafer, and then forming a third processing groove along the remaining dividing line.
2. The method for dividing a disc-shaped wafer according to claim 1, characterized in that the film is a metal film.
3. The method for dividing a disc-shaped wafer according to claim 1 or 2, characterized in that the alignment mark forming step involves forming two first processing grooves extending along the first direction and the second direction, respectively, as the alignment marks.