JP6457231B2 - Wafer division method - Google Patents

Description

  The present invention relates to a wafer dividing method for dividing a wafer into individual chips.

  A linear sensor called a line sensor is configured such that adjacent short sides of a rectangular chip are in contact with each other. Each chip is formed in a size such that the short side is 0.4 mm and the long side is 10 mm, for example. Such a chip is cut out, for example, by cutting a cutting blade along a planned division line of the wafer (see, for example, Patent Document 1 and Patent Document 2 below). The short sides of the plurality of chips divided from the wafer in this way are brought into contact with each other to form a straight line sensor.

JP 2010-073821 A JP 2008-258496 A

  However, when the wafer is divided by cutting from the front side of the wafer using a cutting blade, fine irregularities may occur on the cut surface on the front side, so the short sides of each chip that is singulated contact each other. Therefore, there is a problem that a desired linear line sensor cannot be formed. Even when individual chips are not for line sensors, if there are fine irregularities on the cut surface on the surface side, the quality of the chip will deteriorate.

  The present invention has been made in view of the above circumstances, and an object thereof is to allow a wafer to be divided without causing fine irregularities on a cut surface on the surface side.

According to a first aspect of the present invention, a wafer on which a device is formed by dividing a surface by dividing lines is formed along a dividing line to form a rectangular chip, and a line sensor is formed by contacting the short sides of the chip with each other. A method of dividing a wafer to form, a protective tape attaching step of attaching a protective tape to the surface of the wafer, and a wavelength having transparency to the wafer from the back surface of the wafer after the protective tape attaching step And a modified layer forming step of forming a modified layer having an upper end located at a position closer to the front surface side than the back surface inside the wafer along the planned dividing line. after quality layer forming step, from the rear surface of the wafer by cut the cutting blade to a predetermined depth to leave a modified layer is brought into contact with the reforming layer, along the dividing lines to form a cut groove cut groove Comprising a forming step, and to divide starting from the modified layer by the formation of the cut groove.

According to a second aspect of the present invention, a wafer on which a device is formed by dividing a surface on a surface by dividing a line is divided along the scheduled dividing line to form a rectangular chip, and a line sensor is formed by contacting the short sides of the chip with each other. A method of dividing a wafer to form, having a protective tape attaching step for attaching a protective tape to the surface of the wafer, and having transparency to the wafer from the back side of the wafer after the protective tape attaching step. A modified layer forming step of irradiating a laser beam of a wavelength and condensing the laser beam inside , forming a modified layer having an upper end located at a position closer to the front surface side than the back surface inside the wafer along the planned dividing line; after the reforming layer forming step, from the rear surface of the wafer by cut the cutting blade to a predetermined depth to leave a modified layer is brought into contact with the reforming layer, switching to form the cutting groove along the dividing lines A groove forming step, after the cutting groove forming step includes a dividing step of dividing the starting point said modified layer by applying an external force to the wafer, the.

In the wafer dividing method according to the first aspect of the invention, after a protective tape is attached to the front surface of the wafer, a laser beam having a wavelength that is transparent to the wafer is irradiated from the back side of the wafer to modify the inside of the wafer. The cutting blade is cut from the back surface side of the wafer to a predetermined depth where the modified layer remains, so that a cutting groove is formed, so that the cutting blade does not have to be cut from the front surface side of the wafer. By forming the cutting groove, the wafer can be divided into individual chips starting from the modified layer.
Since the cut surface near the surface side of the chip divided in this way is not easily uneven, the quality of the chip is improved. Further, when the cut surfaces of a plurality of chips are brought into contact with each other to form a line sensor, the surfaces of the chips can be connected to each other. Further, since a cutting allowance by a cutting groove is formed on the cut surface near the back surface side of the chip, it is possible to prevent the back surfaces of adjacent chips from contacting each other, and a desired line sensor can be formed. .

  In the wafer dividing method according to the second invention, a protective tape is applied to the front surface of the wafer, and then a laser beam having a wavelength that is transparent to the wafer is irradiated from the back side of the wafer to modify the inside of the wafer. A cutting blade is cut from the back side of the wafer to a predetermined depth where the modified layer remains, and a cutting groove is formed. Then, external force is applied to the modified layer to start the modified layer. Since the wafer is divided, the wafer can be reliably divided by applying an external force to the modified layer even for a wafer that cannot be divided by forming the cutting groove.

It is a perspective view which shows an example of a wafer. It is a perspective view which shows a tape sticking process. It is sectional drawing which shows a holding process and a modified layer formation process. It is sectional drawing which shows the state in which the modified layer was formed in the inside of a wafer. It is sectional drawing which shows a cutting groove formation process. It is sectional drawing which shows the state which cut the cutting blade to the predetermined depth which leaves a modified layer. It is sectional drawing which shows a division | segmentation process.

  Below, the division | segmentation method which divides | segments the wafer W shown in FIG. 1 into each chip | tip is demonstrated. The wafer W is an example of a workpiece, and includes a disk-shaped substrate 1. On the surface 1 a of the substrate 1, devices 3 are formed in the respective regions partitioned by the grid-like division lines 2. On the other hand, the device 3 is not formed on the back surface 1 b of the substrate 1. In addition, although the device 3 shown in FIG. 1 is formed in a substantially square shape, the size and shape of the device are not particularly limited. For example, the long shape has a short side of 0.4 mm and a long side of 10 mm. Some are formed.

(1) Protection tape sticking process First, as shown in FIG. 2, the protection tape 5 is stuck on the surface 1a side of the substrate 1. Specifically, the protective tape 5 is attached to the lower surface of the ring-shaped frame 6 having an open central portion, and the surface 1a side of the substrate 1 is attached to the protective tape 5 exposed from the central portion. In this way, the frame 6 and the substrate 1 are integrally formed via the protective tape 5. The protective tape 5 should just have adhesiveness, and the kind is not specifically limited. In addition, you may affix the protective tape of the substantially same diameter as the board | substrate 1 directly on the surface 1a, without using the flame | frame 6. FIG.

(2) Holding Step As shown in FIG. 3, the wafer W integrated with the frame 6 is loaded into the chuck table 10 having the holding surface 11 for holding the wafer W, and is disposed on the periphery of the chuck table 10. The wafer W is held using the clamping means 12. The clamping means 12 is connected to a support portion 13 protruding from the outer peripheral side of the chuck table 10, a frame placement portion 14 disposed on the support portion 13 and on which the frame 6 is placed, and one end of the frame placement portion 14. The rotating part 15 having the shaft part 16 and the clamp part 17 that rotates around the shaft part 16 and presses the upper surface of the frame 6 placed on the frame placing part 14 are provided.

  The protective tape 5 attached to the front surface 1a of the wafer W is placed on the holding surface 11 with the protective tape 5 side down, and the frame 6 is placed on the frame placing portion 14. Subsequently, the clamp portion 17 rotates with the shaft portion 16 as a fulcrum, and the wafer W is held on the chuck table 10 by pressing the upper surface of the frame 6 with the clamp portion 17.

(3) Modified layer forming step After performing the protective tape attaching step and the holding step, the modified layer is formed inside the substrate 1 using the laser irradiation means 20 disposed on the upper side of the chuck table 10. . The laser irradiation means 20 positions a condensing point of a laser beam having a wavelength that is transmissive to the substrate 1 at a position inside the substrate 1, for example, close to the surface 1 a side of the substrate 1.

  Next, the laser irradiation means 20 irradiates the laser beam 21 toward the back surface 1b side of the substrate 1 along the planned division line 2 shown in FIG. 1, and inside the substrate 1 as shown in FIG. The modified layer 7 is formed at a position closer to the surface 1a side than 1b. By forming the modified layer 7, the strength on the surface 1a side of the substrate 1 can be weakened. In this way, the modified layer 7 is formed inside the substrate 1 by repeatedly irradiating the laser beam 21 along all the division lines 2.

(4) Cutting groove forming step After performing the modified layer forming step, the substrate 1 is cut from the back surface 1b side of the wafer W along the division line 2 shown in FIG. A cutting groove is formed on the surface. As shown in FIG. 5A, the cutting means 30 includes at least a rotatable spindle 31 and a cutting blade 32 attached to the tip of the spindle 31.

  The cutting means 30 performs cutting to a predetermined depth at which the modified layer 7 remains from the back surface 1b side of the substrate 1 while rotating the cutting blade 32 at a predetermined rotational speed, for example, in the direction of arrow A by rotating the spindle 31. The blade 32 is cut.

  Here, the predetermined depth for leaving the modified layer means an arbitrary cutting depth that does not remove all of the modified layer 7 with the cutting blade 32. For example, as shown in FIG. 6A, the depth at which the cutting edge of the cutting blade 32 slightly contacts the modified layer 7 may be set as a predetermined depth at which the modified layer 7 remains. Further, as shown in FIG. 6B, the cutting blade 32 is cut into the modified layer 7 inside the substrate 1 so that the modified layer 7 remains slightly deep so that the modified layer 7 remains. The predetermined depth may be set.

  When the cutting blade 32 is cut to a predetermined depth where the modified layer 7 remains, as shown in FIGS. 6A and 6B, cracks 9 from the modified layer 7 to the surface 1 a are formed on the substrate 1. Occurs inside. Due to the crack 9, the division planned line 2 is broken.

  In this way, the predetermined depth at which the modified layer 7 remains is set, and the cutting means 30 is moved, for example, in the direction indicated by the arrow Y each time one division planned line 2 is cut with the cutting blade 32 shown in FIG. The above-mentioned cutting operation is repeated while feeding the index to, and cutting is performed along all the division planned lines 2. Then, as shown in FIG. 5 (b), cutting grooves 8 that do not reach the surface 1 b are formed along all the division lines 2 on the substrate 1, and the above-described crack 9 is generated inside the substrate 1. The wafer W is divided into chips for each device using the crack 9 as a starting point.

  On the other hand, as shown in FIG. 6 (c), when the cutting blade 32 is cut to a depth that does not cut to the modified layer 7, the crack 9 described above does not occur inside the substrate 1, so that it will be described later. A division process is performed.

(5) Dividing Step As shown in FIG. 7, the substrate 1 is divided by applying an external force to the inside of the substrate 1 by the tape expansion means 40 disposed below the chuck table 10. The tape expanding means 40 shown in FIG. 7A includes at least a ring-shaped expansion ring 42 disposed around the chuck table 10 and an expansion cylinder 41 that moves the expansion ring 42 up and down.

  When the substrate 1 is divided, the expansion ring 42 is raised by the expansion cylinder 41, and the tape 5 is pushed up from below by the expansion ring 42 as shown in FIG. 7B. As a result, the tape 5 expands radially, an external force is applied to the modified layer 7 inside the substrate 1, and the wafer W is divided into chips C with individual devices using the modified layer 7 as a starting point.

  Here, when the wafer W is divided, when the adjacent chips C are separated from each other with the modified layer 7 shown in FIG. 7A as a boundary, as shown in the partially enlarged view of FIG. A cutting margin L1 is formed between the cut surfaces 1c near the surface 1a side of C. On the other hand, since the cutting groove 8 shown in FIG. 7A is formed on the back surface 1b side of the chip C, a cutting margin L2 wider than the cutting margin L1 is formed between the cut surfaces 1d near the back surface 1b side. It is formed. As described above, since the cutting margin L1 on the surface 1a side of the chip C can be set narrower than the cutting margin L2, it is possible to increase a region where a device can be formed on the surface 1a of the substrate 1. The same applies when the wafer W is divided in the cutting groove forming step.

  The dividing step is not limited to the case where the tape 5 is expanded and divided into chips C. For example, the chips may be divided into individual chips C by pressing along the planned division line 2 using a pressing blade whose tip is formed in a line along the planned division line 2.

In the wafer dividing method of the present invention, the modified layer forming step is performed to form the modified layer 7 at a position close to the surface 1a inside the substrate 1, and then the cutting groove forming step is performed to perform cutting. Since the cutting groove 8 is formed at a predetermined depth at which the modified layer remains from the back surface 1b side of the substrate 1 using the blade 32, the cutting blade 32 can be cut without being cut into the front surface 1a side of the substrate 1. By forming the grooves 8, cracks 9 from the modified layer 7 to the surface 1a can be generated to easily divide the wafer W into individual chips.
After dividing the wafer W into the individual chips C in this way, for example, when forming a linear line sensor by bringing the cut surfaces 1c of the plurality of chips C into contact with each other, the surface 1a side of each chip C Since the cut surface 1c is a surface that is cleaved from the modified layer 7 and has less unevenness, the surfaces of adjacent chips can be connected to each other. Further, although the cut surface 1d on the back surface 1b side of each chip C is uneven, there is a wide cutting margin L2 between the cut surfaces 1d of the adjacent chips C, and the back surface 1b of the adjacent chip C is in contact with it. Therefore, it is possible to form a desired line sensor without forming the side surface of the chip into a tapered shape.

  Furthermore, even for a wafer that cannot be divided by the formation of a cutting groove, the wafer can be reliably divided by applying an external force to the modified layer.

1: Substrate 1a: Front surface 1b: Back surface 1c: Cut surface 2: Line to be divided 3: Device 5: Tape 6: Frame 7: Modified layer 8: Cutting groove 9: Crack 10: Chuck table 11: Holding surface 12: Clamp Means 13: Supporting part 14: Frame placing part 15: Rotating part 16: Shaft part 17: Clamping part 20: Laser irradiation means 21: Laser beam 30: Cutting means 31: Spindle 32: Cutting blade 40: Tape expanding means 41: Expansion Cylinder 42: Expansion ring

Claims (2)

A wafer that is partitioned on a surface by a predetermined division line to form a device is divided along the predetermined division line to form a rectangular chip , and the short sides of the chip are brought into contact with each other to form a line sensor. A method of dividing a wafer,
A protective tape attaching process for attaching a protective tape to the wafer surface;
After the step of attaching the protective tape, a laser beam having a wavelength that is transparent to the wafer is irradiated from the back surface of the wafer to be condensed inside, and the inside of the wafer along the planned dividing line and beyond the back surface. A modified layer forming step of forming a modified layer having an upper end located at a position close to the surface side ;
After the modified layer forming step, a cutting blade is cut from the back surface of the wafer to a predetermined depth where the modified layer remains, and is brought into contact with the modified layer , and a cutting groove is formed along the planned dividing line. A cutting groove forming step to be formed,
A wafer dividing method in which the modified layer is divided from a starting point by forming the cutting groove. The wafer devices are partitioned are formed by dividing lines on the surface is divided along the dividing lines to form a rectangular chip, the division of the wafer to form a line sensor by contacting the short sides together A method,
A protective tape attaching process for attaching a protective tape to the wafer surface;
After the step of attaching the protective tape, a laser beam having a wavelength that is transparent to the wafer is irradiated from the back surface of the wafer to be condensed inside, and the inside of the wafer along the planned dividing line and beyond the back surface. A modified layer forming step of forming a modified layer having an upper end located at a position close to the surface side ;
After the modified layer forming step, a cutting blade is cut from the back surface of the wafer to a predetermined depth where the modified layer remains, and is brought into contact with the modified layer , and a cutting groove is formed along the planned dividing line. A cutting groove forming step to be formed;
After the cutting groove forming step, a dividing step of applying an external force to the wafer to divide the modified layer from the starting point;
Method of dividing a wafer including

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