Wafer Processing Method

Abstract

To provide a wafer processing method capable of surely breaking a DAF (Die Attach Film) even if a chip size is small.SOLUTION: A wafer processing method comprises a film sticking step 102, an adhesive film cutting step 103, a modified layer forming step 104, and a dividing step 106. The adhesive film sticking step sticks an adhesive film to a rear surface side of a wafer. The adhesive film cutting step cuts at least the adhesive film stuck to a rear surface side of the wafer from the rear surface side of the wafer along division schedule lines. The modified layer forming step forms a modified layer along the division schedule lines by condensing a laser beam of wavelength having permeability at an inside of the wafer and irradiating the wafer with the laser beam. The dividing step divides the wafer with the modifier layer as a starting point by applying external force to the wafer after the adhesive film cutting step 103 and the modified layer forming step 104 are performed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a wafer processing method. [Background technology]

[0002] A widely adopted method is to divide a semiconductor wafer, which has a sheet-like adhesive film called DAF (Die Attach Film) previously attached to its backside, into individual devices to form semiconductor chips with the DAF attached to their backside, and then die-bond the semiconductor chips onto a substrate via the DAF on the backside (see Patent Document 1).

[0003] A known method for dividing a wafer involves attaching a DAF and an expand sheet to the back surface of the wafer, forming a modified layer with a laser beam having a wavelength that is transparent to the wafer, and then breaking the DAF by expanding the expand sheet (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-182995 A [Patent Document 2] JP 2003-338467 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the chip size is small, the amount of stretching when the expand sheet is expanded also becomes small, and there is a possibility that an area will be generated in which the DAF cannot be reliably broken.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a wafer processing method capable of reliably breaking the DAF even when the chip size is small. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the wafer processing method of the present invention is a method for processing a wafer having devices in each of areas partitioned by a plurality of intersecting planned division lines on the surface, and includes an adhesive film adhering step of adhering an adhesive film to the back side of the wafer, an adhesive film cutting step of cutting at least the adhesive film adhered to the back side of the wafer from the back side of the wafer along the planned division lines, and a modified layer forming step of irradiating a laser beam having a wavelength that is transparent to the wafer with a focus inside the wafer to form a modified layer along the planned division lines. After performing the adhesive film cutting step, a back side tape attaching step of attaching a stretchable back side tape to the back side of the wafer via the adhesive film; After the adhesive film cutting step and the modified layer forming step are performed, a dividing step is performed in which an external force is applied to the wafer to divide the wafer from the modified layer as a starting point. The dividing step includes an expanding step of dividing the wafer into device chips starting from the modified layer by expanding a backside tape of the wafer. It is characterized by:

[0008] The wafer processing method of the present invention may further include a front-side tape adhering step of adhering a front-side tape to the front side of the wafer before or after the adhesive film adhering step.

[0009] In the wafer processing method of the present invention, in the modified layer forming step, a laser beam having a wavelength that is transparent to the front surface tape and the wafer may be irradiated from the front surface side of the wafer through the front surface tape.

[0014] In addition, in the wafer processing method of the present invention, the dividing step may include a breaking step in which a breaking roller is rotated while pressing the wafer via the back surface tape of the wafer with a breaking roller, and the wafer is divided starting from the modified layer. Effect of the Invention

[0016] The present invention can reliably break the DAF even when the chip size is small. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view showing an example of a wafer to be processed by a wafer processing method according to an embodiment. [Diagram 2] FIG. 2 is a flowchart showing a flow of the wafer processing method according to the embodiment. [Diagram 3] FIG. 3 is a perspective view showing an example of the front-side tape attaching step shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the wafer shown in FIG. [Diagram 5] FIG. 5 is a cross-sectional view showing the wafer after the adhesive film attaching step shown in FIG. [Figure 6] FIG. 6 is a side view, partially in cross section, showing one state of an example of the adhesive film cutting step shown in FIG. [Figure 7] FIG. 7 is a side view, partially in cross section, showing one state of another example of the adhesive film cutting step shown in FIG. [Figure 8] FIG. 8 is a side view, partly in section, showing one state of the modified layer forming step shown in FIG. [Figure 9] FIG. 9 is a side view, partially in section, showing one state of the dividing step shown in FIG. [Figure 10] FIG. 10 is a flowchart showing the flow of the wafer processing method according to the first modified example. [Figure 11] FIG. 11 is a side view, partially in section, showing one state of the dividing step shown in FIG. [Figure 12] 12 is a side view, partly in section, showing a state subsequent to FIG. 11 of the dividing step shown in FIG. [Figure 13] FIG. 13 is a side view, partially in section, showing one state of the mounting step shown in FIG. [Figure 14] FIG. 14 is a flowchart showing the flow of the wafer processing method according to the second modified example. [Figure 15] FIG. 15 is a cross-sectional view showing one state of the back surface tape attaching step shown in FIG. [Figure 16] 16 is a cross-sectional view showing a state after FIG. 15 in the back surface tape attaching step shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The form (embodiment) 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 embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0019] [Embodiment] A method for processing a wafer 10 according to an embodiment of the present invention will be described with reference to the drawings. First, the configuration of the wafer 10 that is the object of processing in the embodiment will be described. Fig. 1 is a perspective view showing an example of a wafer 10 that is the object of processing in the method for processing a wafer 10 according to the embodiment.

[0020] 1, the wafer 10 is a disk-shaped semiconductor wafer, an optical device wafer, or the like, with silicon (Si), sapphire (Al2O3), gallium arsenide (GaAs), silicon carbide (SiC), or the like as the substrate 11. The wafer 10 has a plurality of planned dividing lines 13 set in a lattice pattern on the surface 12 of the substrate 11, and devices 14 formed in areas partitioned by the planned dividing lines 13.

[0021] The device 14 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), or an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The surface of the wafer 10 opposite to the front surface 12 on which the device 14 is formed is referred to as the back surface 15.

[0022] The wafer 10 is divided along the planned division lines 13 into individual devices 14 to be manufactured into device chips 19 (see FIG. 12). In the embodiment, the device chips 19 are square in shape, but may be rectangular in shape. In the embodiment, the wafer 10 has a silicon substrate 11 with a diameter of 8 inches and a thickness of 150 μm, and is diced into device chips 19 with sides of 0.15 mm square.

[0023] Next, a method for processing the wafer 10 according to the embodiment will be described. Fig. 2 is a flow chart showing the flow of the method for processing the wafer 10 according to the embodiment. As shown in Fig. 2, the method for processing the wafer 10 according to the embodiment includes a front side tape attachment step 101, an adhesive film attachment step 102, an adhesive film cutting step 103, a modified layer formation step 104, and a division step 106.

[0024] (Step 101: Applying tape to the front side) 3 is a perspective view showing an example of the surface side tape application step 101 shown in FIG. 2. FIG. 4 is a cross-sectional view showing the wafer 10 shown in FIG. 3. Note that in the cross-sectional view of the wafer 10 shown in FIG. 4 and the following similar cross-sectional views, the number of planned division lines 13 and devices 14 are reduced and depicted larger. The surface side tape application step 101 is a step of applying the surface side tape 20 to the surface 12 side of the wafer 10. Note that, in the embodiment, the surface side tape application step 101 is performed before the adhesive film application step 102 is performed, but in the present invention, it may be performed after the adhesive film application step 102 is performed, or may be omitted.

[0025] The front surface tape 20 is an adhesive tape, such as a dicing tape, for fixing the wafer 10 to an annular frame 21. The front surface tape 20 includes, for example, a base layer made of a synthetic resin, and a glue layer made of an adhesive synthetic resin laminated on the base layer. The frame 21 has an opening larger than the outer diameter of the wafer 10, and is made of a material such as metal or resin.

[0026] In the front side tape application step 101, first, the wafer 10 is positioned at a predetermined position in the opening of the frame 21. Next, the front side tape 20 is applied to one side of the frame 21 and the front side 12 of the wafer 10. At this time, the front side tape 20 is brought into close contact with the front side 12 of the wafer 10 using a roller 25 or the like as shown in FIG. 3, thereby allowing the front side tape 20 to absorb the unevenness between the planned division lines 13 and the devices 14 as shown in FIG. 4. In this way, the wafer 10 is fixed to the front side tape 20 and the frame 21.

[0027] (Adhesive film attachment step 102) Fig. 5 is a cross-sectional view showing the wafer 10 after adhesive film application step 102 shown in Fig. 2. Adhesive film application step 102 is a step of applying an adhesive film 30 to the back surface 15 side of the wafer 10. Note that, although adhesive film application step 102 is performed after performing front surface side tape application step 101 in the embodiment, in the present invention it may be performed before performing front surface side tape application step 101.

[0028] The adhesive film 30 is an insulating adhesive member made of a resin having adhesive properties. The adhesive film 30 is used to fix device chips 19 (see FIG. 12) that are separated and diced into individual devices 14 from the wafer 10 to a mounting substrate (e.g., a mounting substrate 40 shown in FIG. 13) or the like. The outer diameter of the adhesive film 30 is approximately equal to the outer diameter of the wafer 10.

[0029] In the adhesive film application step 102, as shown in FIG. 5, an adhesive film 30 is applied to the back surface 15 side of the wafer 10 fixed to the front surface tape 20 and the frame 21, and is brought into close contact with the back surface 15 of the wafer 10 while covering almost the entire back surface 15 of the wafer 10.

[0030] (Adhesive film cutting step 103) Fig. 6 is a side view, partially in cross section, showing one state of an example of the adhesive film cutting step 103 shown in Fig. 2. The adhesive film cutting step 103 is a step of cutting the adhesive film 30 attached to the back surface 15 side of the wafer 10 along the planned division line 13 from the back surface 15 side of the wafer 10. Note that, although the adhesive film cutting step 103 is performed before the modified layer forming step 104 is performed in the embodiment, it may be performed after the modified layer forming step 104 is performed in the present invention.

[0031] 6, in adhesive film cutting step 103, the adhesive film 30 is cut by a cutting device 200. The cutting device 200 includes a chuck table 210 formed from a transparent body, a cutting unit 220, a moving unit (not shown) that moves the chuck table 210 and the cutting unit 220 relatively, and an imaging unit (not shown).

[0032] The cutting unit 220 includes a disk-shaped cutting blade 221, a spindle 222 that serves as a rotation axis of the cutting blade 221, and a mount flange 223 that is attached to the spindle 222 and to which the cutting blade 221 is fixed. The cutting blade 221 and the spindle 222 include a rotation axis that is parallel to a holding surface 211 of a chuck table 210 that holds a wafer 10 to be cut. The cutting blade 221 is attached to the tip of the spindle 222.

[0033] 6, first, the front surface 12 side of the wafer 10 is suction-held on the holding surface 211 of the chuck table 210 via the front surface tape 20. At this time, the frame 21 is pressed down below the front surface 12 of the wafer 10 and fixed with a clamp member (not shown) or the like, so that the front surface 12 of the wafer 10 is fixed to the holding surface 211 of the chuck table 210.

[0034] In the adhesive film cutting step 103 shown in FIG. 6, the cutting unit 220 and the wafer 10 are then aligned. Specifically, a moving unit (not shown) moves the chuck table 210 to a processing area below the cutting unit 220, and an imaging unit (not shown) photographs and aligns the wafer 10, thereby aligning the processing point of the cutting blade 221 with the division line 13 of the wafer 10. At this time, since the front surface 12 side of the wafer 10 having the division line 13 is held by the holding surface 211 of the chuck table 210, the imaging unit images the wafer 10 through the chuck table 210 formed from a transparent body. Note that if the imaging unit includes an infrared camera and the division line 13 can be confirmed by the infrared camera from the chuck table 210 side through the adhesive film 30, the chuck table 210 does not need to be a transparent body.

[0035] 6, next, the supply of cutting water is started toward the back surface 15 of the wafer 10. Next, while the chuck table 210 and the cutting blade 221 of the cutting unit 220 are relatively moved along the planned division line 13 by a moving unit (not shown), the cutting blade 221 is caused to cut until it reaches the back surface 15 of the wafer 10 or until a groove of a predetermined cutting depth is formed in the wafer 10, thereby cutting the adhesive film 30.

[0036] In the adhesive film cutting step 103, it is sufficient to cut at least the adhesive film 30, but it is also possible to process the entire wafer 10. In this case, it is preferable to set the remaining length from the front surface 12 side of the wafer 10 to 50 μm or more.

[0037] In the adhesive film cutting step 103, the adhesive film 30 may be cut by a laser beam 321. Fig. 7 is a side view, partly in cross section, showing one state of another example of the adhesive film cutting step 103 shown in Fig. 2 .

[0038] 7, the adhesive film 30 is cut by a laser processing device 300. The laser processing device 300 includes a chuck table 310 formed from a transparent body, a laser beam irradiation unit 320, a moving unit (not shown) that moves the chuck table 310 and the laser beam irradiation unit 320 relatively, and an imaging unit (not shown).

[0039] 7, first, the front surface 12 side of the wafer 10 is suction-held on the holding surface 311 of the chuck table 310 via the front surface tape 20. At this time, the frame 21 is pressed down below the front surface 12 of the wafer 10 and fixed with a clamp member (not shown) or the like, so that the front surface 12 of the wafer 10 is fixed to the holding surface 311 of the chuck table 310.

[0040] In the adhesive film cutting step 103 shown in FIG. 7, the laser beam irradiation unit 320 and the wafer 10 are then aligned. Specifically, a moving unit (not shown) moves the chuck table 310 to a processing position, and an imaging unit (not shown) images and aligns the wafer 10, thereby aligning the irradiation portion of the laser beam irradiation unit 320 with the division lines 13 of the wafer 10. At this time, since the front surface 12 side of the wafer 10 having the division lines 13 is held by the holding surface 311 of the chuck table 310, the imaging unit images the wafer 10 through the chuck table 310 formed from a transparent body. Note that if the imaging unit includes an infrared camera and the division lines 13 can be confirmed by the infrared camera from the chuck table 310 side through the adhesive film 30, the chuck table 310 does not need to be a transparent body.

[0041] 7, a pulsed laser beam 321 is irradiated from the back surface 15 side of the wafer 10 to the adhesive film 30 attached to the wafer 10 with a focal point 322 positioned on the surface or near the surface of the adhesive film 30. In the adhesive film cutting step 103, the adhesive film 30 is cut along the planned division lines 13 by irradiating the adhesive film 30 along the planned division lines 13 with the laser beam 321 with a focal point 322 positioned on the surface or near the surface of the adhesive film 30.

[0042] (Modified layer forming step 104) Fig. 8 is a side view, partially in cross section, showing one state of the modified layer forming step 104 shown in Fig. 2. The modified layer forming step 104 is a step of forming a modified layer 16 inside the wafer 10 along the planned division lines 13. Note that, although the modified layer forming step 104 is performed after the adhesive film cutting step 103 is performed in the embodiment, it may be performed before the adhesive film cutting step 103 is performed in the present invention.

[0043] The modified layer 16 refers to a region in which the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area. The modified layer 16 is, for example, a melt-processed region, a crack region, a dielectric breakdown region, a refractive index change region, or a region in which these regions are mixed. The modified layer 16 has a lower mechanical strength, etc. than other parts of the wafer 10.

[0044] 8, in the modified layer forming step 104, the modified layer 16 is formed by performing stealth dicing processing using a laser beam 321. The laser beam 321 is a laser beam with a wavelength that is transparent to the wafer 10. In the embodiment, the surface side tape 20 is attached to the surface 12 side of the wafer 10 in the surface side tape attaching step 101. Therefore, the laser beam 321 is a laser beam with a wavelength that is transparent to the surface side tape 20 and the wafer 10.

[0045] In the modified layer forming step 104, first, the back surface 15 side of the wafer 10 is sucked and held on the chuck table 310 via the adhesive film 30. Next, the chuck table 310 is moved to a processing position by a moving unit (not shown). Next, the wafer 10 is imaged by an imaging unit (not shown) to detect the dividing lines 13. Once the dividing lines 13 have been detected, alignment is performed to align the dividing lines 13 of the wafer 10 with the irradiation portion of the laser beam irradiation unit 320.

[0046] In the modified layer forming step 104, next, while the chuck table 310 is moved relative to the laser beam irradiation unit 320, a pulsed laser beam 321 is irradiated from the front surface 12 side of the wafer 10 through the front surface tape 20 with a focus point 322 positioned inside the wafer 10. In the modified layer forming step 104, the laser beam 321 with the focus point 322 positioned inside the wafer 10 is irradiated along the planned division lines 13, thereby forming a modified layer 16 along the planned division lines 13 inside the substrate 11, as shown in Fig. 8. That is, the modified layer 16 is formed along the cutting line of the adhesive film 30 cut in the adhesive film cutting step 103.

[0047] (Division step 106) Fig. 9 is a side view, partially in cross section, showing one state of the dividing step 106 shown in Fig. 2. The dividing step 106 is performed after the adhesive film cutting step 103 and the modified layer forming step 104. The dividing step 106 is a step of dividing the wafer 10 starting from the modified layer 16 by applying an external force to the wafer 10.

[0048] 9, in the dividing step 106 of the embodiment, an external force is applied to the wafer 10 by a breaking device 400. That is, the dividing step 106 of the embodiment includes a breaking step in which the breaking roller 420 is rotated while pressing the wafer 10 via the front side tape 20 of the wafer 10 with the breaking roller 420, thereby dividing the wafer 10 starting from the modified layer 16. The breaking device 400 includes a resin pad 410 on which the wafer 10 is placed, and a breaking roller 420.

[0049] In the dividing step 106, first, the back surface 15 side of the wafer 10 is placed on the resin pad 410 via the adhesive film 30. Next, the breaking roller 420 is rotated while pressing the wafer 10 via the front surface tape 20 of the wafer 10 with the breaking roller 420. That is, the breaking roller 420 is rolled on the front surface tape 20 of the wafer 10 while being pressed against the wafer 10 side.

[0050] As a result, an external force is applied to the wafer 10, so that cracks extend from the modified layer 16, and the modified layer 16 and the cracks are connected to each other, dividing the wafer 10 starting from the modified layer 16. Here, since the adhesive film 30 has already been cut along the intended division lines 13 in the adhesive film cutting step 103, the wafer 10 is divided into individual device chips each having the adhesive film 30 attached to its rear surface 15.

[0051] [First Modification] Next, a method for processing the wafer 10 according to the first modified example will be described. FIG. 10 is a flow chart showing the flow of the method for processing the wafer 10 according to the first modified example. As shown in FIG. 10, the method for processing the wafer 10 according to the first modified example includes a front side tape attachment step 101-1, an adhesive film attachment step 102, an adhesive film cutting step 103, a modified layer formation step 104, a division step 106-1, and a mounting step 107. Note that the procedures of the adhesive film attachment step 102, the adhesive film cutting step 103, and the modified layer formation step 104 according to the first modified example are the same as those in the embodiment, and therefore will not be described.

[0052] (Step 101-1: Applying tape to the front side) The front side tape 20-1 adhered to the front surface 12 side of the wafer 10 in front side tape application step 101-1 of the first modified example is different from the front side tape 20 of the embodiment in that it has elasticity. The procedure of front side tape application step 101-1 of the first modified example is similar to that of front side tape application step 101 of the embodiment, and therefore a description thereof will be omitted.

[0053] (Split step 106-1) Fig. 11 is a side view, partially in cross section, showing one state of the dividing step 106-1 shown in Fig. 10. Fig. 12 is a side view, partially in cross section, showing one state of the dividing step 106-1 shown in Fig. 10 after Fig. 11. The dividing step 106-1 of the first modified example includes an expanding step in which the front side tape 20-1 of the wafer 10 is expanded to divide the wafer 10 into device chips 19 starting from the modified layer 16.

[0054] 11 and 12, in the division step 106-1 of the first modified example, an external force in the planar and radial directions is applied to the front surface side tape 20-1 by the expansion device 500. The expansion device 500 includes a chuck table 501, a clamp unit 502, and a lifting unit 503.

[0055] In the dividing step 106-1, first, as shown in Fig. 11, the front surface 12 side of the wafer 10 is placed on the holding surface of the chuck table 501 via the front surface side tape 20-1, and the outer periphery of the frame 21 is fixed by the clamp section 502. Next, as shown in Fig. 12, the chuck table 501 is raised by the lifting unit 503. At this time, since the outer periphery of the front surface side tape 20-1 is fixed by the clamp section 502 via the frame 21, the portion between the inner edge of the frame 21 and the outer edge of the wafer 10 is expanded in the planar direction.

[0056] In the division step 106-1, as a result of the expansion of the front surface side tape 20-1, a radial tensile force acts on the front surface side tape 20-1. When the radial tensile force acts on the front surface side tape 20-1, the wafer 10 to which the front surface side tape 20-1 is attached is divided into individual devices 14 starting from the modified layer 16 along the planned division lines 13, as shown in FIG. 12, and is divided into individual device chips 19.

[0057] (Implementation Step 107) Fig. 13 is a side view, partially in cross section, showing one state of the mounting step 107 shown in Fig. 10. The mounting step 107 is a step of mounting the device chip 19 on the mounting substrate 40 with the adhesive film 30 disposed on the back surface 15 side of the device chip 19.

[0058] In the mounting step 107 of the first modified example, the device chip 19 is not picked up from the front surface tape 20-1, but a mounting substrate 40 is first prepared on which the device chip 19 is mounted in a position facing the device chip 19 supported by the front surface tape 20-1. Next, the device chip 19 is pressed toward the mounting substrate 40 via the front surface tape 20-1. As a result, the device chip 19 is mounted on the mounting substrate 40 by the adhesive film 30 disposed on the back surface 15 side of the device chip 19.

[0059] [Second Modification] Next, a method for processing the wafer 10 according to the second modified example will be described. FIG. 14 is a flow chart showing the flow of the method for processing the wafer 10 according to the second modified example. The method for processing the wafer 10 according to the second modified example includes a front side tape application step 101, an adhesive film application step 102, an adhesive film cutting step 103, a modified layer formation step 104, a back side tape application step 105, and a division step 106-2, as shown in FIG. 14. Note that the procedures of the front side tape application step 101, the adhesive film application step 102, the adhesive film cutting step 103, and the modified layer formation step 104 of the second modified example are the same as those of the embodiment, and therefore will not be described.

[0060] (Step 105: Apply tape to the back side) Fig. 15 is a cross-sectional view showing one state of the back side tape application step 105 shown in Fig. 14. Fig. 16 is a cross-sectional view showing one state of the back side tape application step 105 shown in Fig. 14 after Fig. 15. The back side tape application step 105 is performed at least after the adhesive film cutting step 103 is performed. In the second modified example, the back side tape application step 105 is performed after the modified layer formation step 104 is performed. The back side tape application step 105 is a step of applying the back side tape 50 to the back side 15 side of the wafer 10 via the adhesive film 30.

[0061] In the processing method of the wafer 10 according to the second modified example, a front side tape 20 is attached to the front surface 12 side of the wafer 10 in a front side tape attachment step 101 prior to a back side tape attachment step 105. Therefore, in a back side tape attachment step 105 of the second modified example, a back side tape 50 is attached to the back surface 15 side of the wafer 10 via an adhesive film 30, and the front side tape 20 is removed from the wafer 10.

[0062] The back side tape 50 is an adhesive tape for dividing the wafer 10 by expanding in the surface direction in the division step 106-2 described later. The back side tape 50 has elasticity. The back side tape 50 includes, for example, a base layer made of a synthetic resin, and a glue layer made of an adhesive synthetic resin laminated on the base layer.

[0063] In the back side tape attachment step 105, first, as shown in Fig. 15, the front side tape 20 is cut off at the outer periphery of the wafer 10. At this time, for example, a cutter 26 or the like is placed along the front side tape 20 at the outer periphery of the wafer 10, and the wafer 10 is rotated about its axis. As a result, the outer periphery of the front side tape 20 (the portion radially outward from the cutting line 27 shown in Fig. 15) including the portion attached to the frame 21 and the frame 21 are cut off from the portion of the front side tape 20 attached to the front surface 12 of the wafer 10.

[0064] In the back side tape attachment step 105, next, as shown in FIG. 16, a back side tape 50 and a frame 51 are prepared at a position facing the back side 15 of the wafer 10. The frame 51 has an opening larger than the outer diameter of the wafer 10, and is made of a material such as metal or resin. Next, the back side tape 50 is attached to the surface of the frame 51 opposite to the surface facing the wafer 10, and to the back side 15 of the wafer 10 via the adhesive film 30. At this time, the back side tape 50 is brought into close contact with the back side 15 of the wafer 10 via the adhesive film 30 using a roller 55 or the like as shown in FIG. 16. Next, the front side tape 20 is peeled off from the front side 12 of the wafer 10.

[0065] (Split step 106-2) The dividing step 106-2 of the second modified example includes an expanding step of dividing the wafer 10 into device chips 19 starting from the modified layer 16 by expanding the back side tape 50 of the wafer 10. The dividing step 106-2 of the second modified example differs from the dividing step 106-1 of the first modified example in that the back side tape 50 is expanded instead of the front side tape 20-1 to divide the wafer 10 into device chips 19.

[0066] 11 and 12, the back surface 15 side of the wafer 10 is fixed to the expansion apparatus 500 via the back surface tape 50. In the dividing step 106-2 of the second modified example, the other procedures are the same as those in the dividing step 106-1 of the first modified example, and therefore the description thereof will be omitted.

[0067] In the processing method of the wafer 10 of the second modified example, in the dividing step 106-2, an external force may be applied to the wafer 10 by a breaking device 400, as in the dividing step 106 of the embodiment shown in Fig. 9. That is, the dividing step 106-2 may include a breaking step in which the breaking roller 420 is rotated while pressing the wafer 10 via the back side tape 50 of the wafer 10 with the breaking roller 420, and the wafer 10 is divided starting from the modified layer 16. In this case, the back side tape 50 applied in the back side tape application step 105 may not have elasticity.

[0068] As described above, in the processing method of the wafer 10 of the embodiment and each modified example, a so-called 2-in-1 type adhesive film in which the DAF, which is an adhesive film for die bonding, and an expand sheet are integrated is not used, but an adhesive film for die bonding is attached to one surface (back surface 15) of the wafer 10, and a dicing tape is attached to the other surface (front surface 12) of the wafer 10. This makes it possible to process the adhesive film from one surface and perform stealth dicing processing on the wafer 10 from the other surface, so that the DAF can be reliably broken regardless of the size of the device 14, unlike the conventional method in which the DAF is broken as the expand sheet expands.

[0069] The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, in the modified layer forming step 104, the laser beam 321 is irradiated from the front surface 12 side of the wafer 10 to the inside of the wafer 10 in the embodiment, but the laser beam 321 may be irradiated from the back surface 15 side of the wafer 10 to the inside of the wafer 10 in the modified layer forming step 104.

[0070] When the modified layer 16 is formed from the back surface 15 side of the wafer 10, for example, the modified layer 16 may be formed and then the adhesive film 30 may be attached to the back surface 15 of the wafer 10, or the adhesive film 30 may be attached to the back surface 15 of the wafer 10 and then the laser beam 321 may be irradiated through the adhesive film 30. In addition, after the modified layer 16 is formed from the back surface 15 side, the back surface 15 of the wafer 10 may be ground before the adhesive film 30 is attached to the back surface 15 of the wafer 10. Furthermore, after the adhesive film cutting step 103 in which the adhesive film 30 is cut, it is preferable to attach the back surface tape 50 for division as in the second modified example. In these cases, since the wafer 10 is processed from the back surface 15 side in both the adhesive film cutting step 103 and the modified layer forming step 104, the effect of reducing the effort required to turn the wafer 10 over is achieved.

[0071] In addition, the dividing steps 106, 106-1, and 106-2 in the embodiment and each modified example include either the breaking step or the expanding step, but may include either step. In particular, by performing the expanding step after performing the breaking step to widen the chip interval, even small chips can be suitably picked up. [Explanation of symbols]

[0072] 10 wafers 11 Substrate 12 Surface 13 Division line 14 Devices 15 Back side 16 Modification layer 19 Device Chips 20, 20-1 Surface tape 21, 51 frames 30 Adhesive Film 40 Mounting Board 50 Back side tape 321 Laser Beam 420 Braking Roller

Claims

1. A method for processing a wafer having devices in each of areas defined by a plurality of intersecting dividing lines on a surface thereof, comprising the steps of: an adhesive film attaching step of attaching an adhesive film to the back side of the wafer; an adhesive film cutting step of cutting the adhesive film attached to at least the back side of the wafer from the back side of the wafer along the intended division line; a modified layer forming step of irradiating the inside of the wafer with a laser beam having a wavelength that is transparent to the wafer, to form a modified layer along the intended dividing line; After performing the adhesive film cutting step, a back side tape attaching step of attaching a stretchable back side tape to the back side of the wafer via the adhesive film; a dividing step of dividing the wafer starting from the modified layer by applying an external force to the wafer after the adhesive film cutting step and the modified layer forming step are performed; having The dividing step includes an expanding step of dividing the wafer into device chips starting from the modified layer by expanding a backside tape of the wafer. Wafer processing method.

2. A surface side tape adhering step of adhering a surface side tape to the surface side of the wafer before or after the adhesive film adhering step is included. The wafer processing method according to claim 1 .

3. In the modified layer forming step, a laser beam having a wavelength that is transparent to the front surface side tape and the wafer is irradiated from the front surface side of the wafer through the front surface side tape. The wafer processing method according to claim 2 .

4. The dividing step includes a breaking step of rotating and moving the breaking roller while pressing the wafer via the back surface tape of the wafer with a breaking roller to divide the wafer starting from the modified layer. The wafer processing method according to any one of claims 1 to 3.

Images