Wafer processing method

Abstract

To provide a wafer processing method with which it is possible to increase the number of devices per sheet of wafer.SOLUTION: There is provided, a method for processing a wafer in which devices are formed in respective regions partitioned by a plurality of scheduled intersecting surface divide lines. The wafer processing method includes: a laser machined groove formation step 1002 for irradiating the surface of a wafer with a laser beam in a wavelength having absorbency to the wafer and forming laser machined grooves along the scheduled divide lines; and a dicing step 1005 for cutting from a reverse side of the wafer into a depth to reach the laser machined grooves with a cutting blade and cutting the wafer with the cutting blade along the scheduled divide lines for dividing up the wafer, after performing the laser machined groove formation step 1002.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for processing a wafer having devices formed in each of areas partitioned by a plurality of intersecting planned dividing lines on the surface. [Background technology]

[0002] To improve the characteristics of semiconductor devices, semiconductor devices that use low-k dielectric films (Low-k films) made of inorganic films such as SiOF and BSG (SiOB) or organic films such as polymer films of polyimide and parylene as interlayer insulating films are widely distributed on the market. Also widely used are semiconductor wafers on which metal patterns called TEGs (test element groups) are formed along the planned dividing lines of the wafer for device inspection.

[0003] Individual semiconductor devices are formed by cutting a semiconductor wafer along the planned dividing lines with a cutting blade. However, cutting these low-k films or TEG with a cutting blade can cause problems such as the low-k film peeling off or the TEG clogging or glazing of the cutting blade, resulting in a deterioration in processing quality.

[0004] Therefore, a processing method has been widely adopted in which a laser beam is irradiated to cut the low-k film or TEG, and the semiconductor wafer is cut with a cutting blade (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-64231 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the processing method disclosed in Patent Document 1, it is necessary to form a laser-processed groove wider than the groove formed by the cutting blade, that is, it is necessary to form the width of the planned dividing line of the semiconductor wafer wider than the width of the cutting groove. As a result, the processing method disclosed in Patent Document 1 has a problem in that the number of semiconductor devices that can be formed from one semiconductor wafer is reduced, and improvement is strongly desired.

[0007] An object of the present invention is to provide a wafer processing method that can increase the number of devices per wafer. [Means for solving the problem]

[0008] 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 formed in each of areas partitioned by a plurality of intersecting planned dividing lines on the surface, and includes a laser-machined groove forming step of irradiating the surface of the wafer with a laser beam having a wavelength absorbable by the wafer to form laser-machined grooves along the planned dividing lines, and a dicing step of, after the laser-machined groove forming step, cutting the wafer along the planned dividing lines with a cutting blade while cutting from the back surface of the wafer to a depth reaching the laser-machined grooves, thereby dividing the wafer. and a sheet disposing step, which is carried out after the laser-processed groove forming step and before the dicing step, of adhering a sheet having a thickness greater than the depth of the laser-processed groove to the surface of the wafer and filling the laser-processed groove with the sheet. In the sheet disposing step, the sheet is filled in the laser-processed groove, and in the dicing step, the cutting blade is caused to cut into the wafer to a depth that does not reach the sheet. It is characterized by:

[0009] In the wafer processing method , applicable In the dicing step, the wafer may be cut with the cutting blade while a cutting fluid is supplied to a processing point where the cutting blade comes into contact with the wafer.

[0010] The wafer processing method may further include a protective film forming step of forming a protective film on the front surface of the wafer before performing the laser-processed groove forming step, and in the sheet disposing step, the sheet is attached to the protective film, and after performing the dicing step, a transfer step of attaching tape to the back surface of the wafer and removing the sheet from the front surface of the wafer, and a protective film removal step of removing the protective film after performing the transfer step.

[0011] In the wafer processing method, in the dicing step, the cutting blade may be caused to cut into the sheet to a depth that does not completely cut through the sheet.

[0012] In the wafer processing method, the sheet may not have an adhesive layer, and in the sheet disposing step, the sheet may be heated to adhere to the surface of the wafer. [Effects of the Invention]

[0013] The present invention has the advantage that the number of devices per wafer can be increased. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of a wafer to be processed by the wafer processing method according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of the wafer processing method according to the first embodiment. [Figure 3] FIG. 3 is a side view, partly in section, schematically showing the protective film forming step of the wafer processing method shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view schematically showing a main part of the wafer after the protective film forming step in the wafer processing method shown in FIG. [Figure 5] FIG. 5 is a side view, partly in section, schematically showing the laser groove forming step of the wafer processing method shown in FIG. [Figure 6]FIG. 6 is a cross-sectional view schematically showing a main part of the wafer after the laser groove forming step of the wafer processing method shown in FIG. [Figure 7] FIG. 7 is a side view, partly in section, schematically showing the protective film removing step of the wafer processing method shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view that schematically shows a main part of a protective tape, which is a sheet that is attached to the surface of a wafer in the sheet disposing step of the wafer processing method shown in FIG. [Figure 9] FIG. 9 is a perspective view schematically showing the wafer after the sheet disposing step of the wafer processing method shown in FIG. [Figure 10] FIG. 10 is a side view, partially in section, schematically showing the dicing step of the wafer processing method shown in FIG. [Figure 11] FIG. 11 is a cross-sectional view schematically showing a main part of the wafer after the dicing step of the wafer processing method shown in FIG. [Figure 12] FIG. 12 is a flowchart showing the flow of the wafer processing method according to the second embodiment. [Figure 13] FIG. 13 is a perspective view schematically showing the wafer after the sheet disposing step of the wafer processing method shown in FIG. [Figure 14] FIG. 14 is a cross-sectional view schematically showing a main part of the wafer shown in FIG. [Figure 15] FIG. 15 is a cross-sectional view schematically showing a main part of the wafer after the dicing step of the wafer processing method shown in FIG. [Figure 16] FIG. 16 is a side view, partly in section, schematically showing the wafer back surface cleaning step of the wafer processing method shown in FIG. [Figure 17] FIG. 17 is a perspective view schematically showing the wafer after the transfer step of the wafer processing method shown in FIG. [Figure 18] FIG. 18 is a side view, partially in section, schematically showing the protective film removing step of the wafer processing method shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Modes (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 a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0016] [Embodiment 1] A wafer processing method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view of a wafer to be processed by the wafer processing method according to the first embodiment. Fig. 2 is a flowchart showing the flow of the wafer processing method according to the first embodiment.

[0017] The processing method according to the first embodiment is a method for processing a wafer 1 shown in Fig. 1. The wafer 1 to be processed by the processing method according to the first embodiment is a disk-shaped semiconductor wafer, an optical device wafer, or the like, with a substrate 2 made of silicon, sapphire, gallium arsenide, SiC (silicon carbide), or the like. The wafer 1 has a plurality of planned division lines 4 that intersect on a surface 3, and devices 5 are formed in each of the areas on the surface 3 that are partitioned in a grid pattern by the planned division lines 4.

[0018] The device 5 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), or a memory (semiconductor storage device).

[0019] 1, the wafer 1 has a device layer 6, which is an organic film, on a substrate 2. The device layer 6 includes a low-dielectric-constant insulator coating (hereinafter referred to as a low-k film) made of an inorganic film such as SiOF or BSG (SiOB), an organic film such as a polymer film of a polyimide or parylene, or carbon-containing silicon dioxide (SiOCH), and a circuit layer including a conductive metal pattern or metal film.

[0020] The low-k film is laminated with a circuit layer to form the device 5. The circuit layer constitutes the circuit of the device 5. For this purpose, the device 5 is composed of low-k films laminated on each other in the device layer 6 laminated on the substrate 2 and the circuit layer laminated between the low-k films. In the planned division line 4, the device layer 6 is composed of low-k films laminated on the substrate 2, except for the TEG (Test Elementary Group).

[0021] In the first embodiment, the wafer 1 has a TEG (not shown) formed on the planned dividing lines 4. The TEG is an evaluation element for detecting design or manufacturing problems that may occur in the device 5. The device layer 6, such as a low-k film, and the TEG are likely to peel off from the substrate 2 when the wafer 1 is cut from the front surface 3 side with a cutting blade.

[0022] The wafer processing method according to the first embodiment is a method of dividing the wafer 1 having the above-described configuration into individual devices 5 along the planned dividing lines 4. As shown in Fig. 2, the wafer processing method according to the first embodiment includes a protective film forming step 1001, a laser processed groove forming step 1002, a protective film removing step 1003, a sheet providing step 1004, and a dicing step 1005.

[0023] (Protective film formation step) Fig. 3 is a side view, partially in cross section, schematically showing a protective film forming step in the wafer processing method shown in Fig. 2. Fig. 4 is a cross-sectional view schematically showing a main part of the wafer after the protective film forming step in the wafer processing method shown in Fig. 2.

[0024] 3 forms a protective film 25 (shown in FIG. 4) on the front surface 3 of the wafer 1 before performing the laser-processed groove forming step 1002. In the first embodiment, in the protective film forming step 1001, an adhesive tape 10 having a diameter larger than the wafer 1 is adhered to the back surface 7 behind the front surface 3 of the wafer 1, and an annular frame 11 is adhered to the outer periphery of the adhesive tape 10, and the wafer 1 is supported by the annular frame 11.

[0025] In the first embodiment, in the protective film forming step 1001, the protective film coating device 20 suction-holds the back surface 7 of the wafer 1 to the holding surface of the spinner table 21 via the adhesive tape 10, and clamps the annular frame 11 with the clamps 22 provided around the periphery of the spinner table 21. In the protective film forming step 1001, the protective film coating device 20 rotates the spinner table 21 about its axis and drops the water-soluble resin 24 from the water-soluble resin supply nozzle 23 onto the center of the front surface 3 of the wafer 1, as shown in FIG.

[0026] The dropped water-soluble resin 24 flows from the center to the outer periphery on the surface 3 of the wafer 1 due to the centrifugal force generated by the rotation of the spinner table 21, and is applied to the entire surface 3 of the wafer 1.

[0027] The water-soluble resin 24 is, for example, a water-soluble resin such as polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP). In the protective film forming step 1001, the water-soluble resin 24 applied to the entire surface 3 of the wafer 1 is cured to form a water-soluble protective film 25 that covers the entire surface 3 of the wafer 1, as shown in Figure 4. Note that the device layer 6 is omitted from Figure 3.

[0028] (Laser processing groove formation step) Fig. 5 is a side view, partially in cross section, schematically showing the laser groove forming step of the wafer processing method shown in Fig. 2. Fig. 6 is a cross-sectional view schematically showing the main part of the wafer after the laser groove forming step of the wafer processing method shown in Fig. 2.

[0029] 5 irradiates the front surface 3 of the wafer 1 with a laser beam 33 having a wavelength that is absorbed by the wafer 1 to form laser grooves 35 (shown in FIG. 6) along the planned dividing lines 4. In the first embodiment, in the laser groove forming step 1002, the laser processing device 30 suction-holds the back surface 7 of the wafer 1 to the holding surface of the chuck table 31 via the adhesive tape 10, and clamps the annular frame 11 with clamps (not shown) provided around the chuck table 31.

[0030] In the laser groove forming step 1002, the laser processing device 30 moves the chuck table 31 and the laser beam application unit 32 relatively along the division lines 4, and irradiates the division lines 4 from the laser beam application unit 32 with a laser beam 33 having a wavelength that is absorbed by the substrate 2 of the wafer 1 from the front surface 3 side through the protective film 25, as shown in Fig. 5. Note that in the first embodiment, in the laser groove forming step 1002, the laser processing device 30 sets a focal point at the center of the front surface 3 of each of the division lines 4 in the width direction, which is a predetermined position, and irradiates the laser beam 33.

[0031] In the laser groove forming step 1002, since the laser beam 33 has a wavelength that is absorbed by the wafer 1, ablation processing is performed on the device layer 6 and substrate 2 on the dividing lines 4, dividing the device layer 6 on the dividing lines 4 and forming laser grooves 35 that reach the substrate 2 along the dividing lines 4, as shown in Fig. 6. In the laser groove forming step 1002, laser grooves 35 are formed on all of the dividing lines 4.

[0032] In the first embodiment, the laser groove 35 is formed at the center in the width direction, which is a predetermined position on the dividing line 4. In the laser groove forming step 1002, debris is generated when the laser beam 33 is irradiated onto the wafer 1 to form the laser groove 35. The generated debris adheres to the protective film 25.

[0033] (Protection film removal step) Fig. 7 is a side view, partially in cross section, schematically showing the protective film removing step of the wafer processing method shown in Fig. 2. The protective film removing step 1003 is a step of removing the protective film 25 from the front surface 3 of the wafer 1.

[0034] In the protective film removal step 1003, the cleaning device 40 suction-holds the backside 7 of the wafer 1 to the holding surface of the spinner table 41 via the adhesive tape 10, and clamps the annular frame 11 with the clamps 42 provided around the spinner table 41. In the protective film removal step 1003, the cleaning device 40 supplies a cleaning liquid 44 made of pure water from a cleaning liquid supply nozzle 43 to the center of the front side 3 of the wafer 1 while rotating the spinner table 41 around its axis, as shown in FIG. 7 . The cleaning liquid 44 supplied to the front side 3 of the wafer 1 flows from the center toward the outer periphery over the front side 3 of the wafer 1 due to centrifugal force generated by the rotation of the spinner table 41, cleaning the front side 3 of the wafer 1 and removing the protective film 25 from the front side 3 of the wafer 1 together with debris. Note that the device layer 6 is omitted from FIG. 7 .

[0035] (Sheet placement step) Fig. 8 is a cross-sectional view schematically showing a main part of a protective tape, which is a sheet adhered to the surface of a wafer in the sheet disposing step of the wafer processing method shown in Fig. 2. Fig. 9 is a perspective view schematically showing a wafer after the sheet disposing step of the wafer processing method shown in Fig. 2.

[0036] The sheet providing step 1004 is a step performed after the laser groove forming step 1002 and before the dicing step 1005, in which the protective tape 12 shown in Fig. 8 is attached as a sheet to the front surface 3 of the wafer 1 to fill part of the laser grooves 35. In the first embodiment, in the sheet providing step 1004, as shown in Fig. 8, the protective tape 12 having a base layer 121 and an adhesive layer 122 laminated on the base layer 121 is attached as a sheet to the front surface 3 of the wafer 1.

[0037] The base layer 121 is made of a flexible, non-adhesive resin. The glue layer 122 is made of a flexible, adhesive resin. In the first embodiment, the thickness 123 (shown in FIG. 8) of the glue layer 122 is greater than the depth 36 (shown in FIG. 6) of the laser-processed groove 35 from the surface 3.

[0038] 9, in the sheet providing step 1004, an adhesive layer 122 of a disk-shaped protective tape 12 having a diameter larger than that of the wafer 1 is adhered to the front surface 3 of the wafer 1, and an annular frame 13 is adhered to the outer edge of the protective tape 12 to support the wafer 1 with the annular frame 13, and the adhesive tape 10 is peeled off from the back surface 7. In the first embodiment, in the sheet providing step 1004, the protective tape 12 is pressed against the front surface 3 of the wafer 1, and the adhesive layer 122, which is part of the protective tape 12, is filled into the laser-processed grooves 35.

[0039] (dicing step) Fig. 10 is a side view, partially in cross section, schematically showing a dicing step in the wafer processing method shown in Fig. 2. Fig. 11 is a cross-sectional view schematically showing a main part of the wafer after the dicing step in the wafer processing method shown in Fig. 2.

[0040] 10 cuts the wafer 1 along the division lines 4 with the cutting blade 54 while cutting from the back surface 7 of the wafer 1 to a depth reaching the laser grooves 35, thereby dividing the wafer 1. In the dicing step 1005, the cutting device 50 suction-holds the front surface 3 side of the wafer 1 to the holding surface of the chuck table 51 via the protective tape 12, and clamps the annular frame 13 with the clamps 52 provided around the chuck table 51.

[0041] In the dicing step 1005, the cutting device 50 takes an image of the back surface 7 side of the wafer 1 with an infrared camera or takes an image of the front surface 3 side of the wafer 1 through the protective tape 12 and the chuck table 51, and performs alignment to align the cutting blade 54 of the cutting unit 53 with the division line 4. In the dicing step 1005, as shown in Fig. 10 , the cutting device 50 moves the chuck table 51 and the cutting blade 54 relatively along the division line 4, while supplying cutting fluid (not shown) to the processing point where the cutting blade 54 and the wafer 1 come into contact, and causes the cutting blade 54 to cut into the center of the width direction of the wafer 1, which is a predetermined position along the division line 4, to a depth that reaches the laser-processed groove 35 but does not reach the holding surface of the chuck table 51, and cuts the wafer 1 with the cutting blade 54.

[0042] In the first embodiment, in the dicing step 1005, the cutting device 50 causes the cutting blade 54 to cut into the wafer 1 to a depth shallower than the thickness of the substrate 2 of the wafer 1 and not reaching the protective tape 12. In this way, in the dicing step 1005, the cutting blade 54 is caused to cut into the protective tape 12 to a depth that does not completely cut through the protective tape 12.

[0043] Then, in the dicing step 1005, the cutting blade 54 is caused to cut into the center of the width of the dividing lines 4 to the aforementioned depth, so that, as shown in FIG. 11 , the laser-processed grooves 35 are exposed at the bottom of the cut grooves 55 formed by the cutting of the cutting blade 54, and the dividing lines 4 are divided by the cut grooves 55 and the laser-processed grooves 35. In the dicing step 1005, all of the dividing lines 4 are cut with the cutting blade 54 to form the cut grooves 55 at all of the dividing lines 4, dividing the wafer 1 into individual devices 5 and completing the wafer processing method. Note that FIG. 10 does not show the adhesive layer 122. The individually divided devices 5 are picked up from the adhesive layer 122 of the protective tape 12.

[0044] The wafer processing method according to the first embodiment described above involves irradiating the front surface 3 of the wafer 1 with a laser beam 33 to form a laser groove 35, and cutting the planned dividing lines 4 from the back surface 7 of the wafer 1 with a cutting blade 54, so that the width of the planned dividing lines 4 of the wafer 1 can be made equal to the width of the cutting groove 55.

[0045] For this reason, the wafer processing method according to the first embodiment can reduce the width of the dividing lines 4 compared to the conventional processing method in which a laser beam 33 is irradiated onto the surface 3 to form laser grooves 35, and then cutting is performed between the laser grooves 35, even for a wafer 1 on which a TEG or a device layer 6 is formed. As a result, the wafer processing method according to the first embodiment has the effect of being able to increase the number of devices 5 per wafer 1, even for a wafer 1 on which a TEG or a device layer 6 is formed.

[0046] In a typical processing method, after irradiating the front surface 3 of the wafer 1 with a laser beam 33 in the laser groove forming step 1002, cutting is performed from the back surface 7 with a cutting blade 54. This cutting fluid containing cutting debris from the cutting process can seep into the front surface 3 side of the wafer 1 through the laser groove 35 and contaminate the front surface 3 of the wafer 1. This contamination on the front surface 3 side of the wafer 1 cannot be removed by cleaning the back surface 7 side of the wafer 1 that is exposed after cutting. Furthermore, even if an attempt is made to transfer the contamination on the front surface 3 side of the wafer 1 after cutting and clean the front surface 3, the cutting fluid evaporates after cutting, causing the contamination to adhere to the front surface 3 of the wafer 1, and cleaning the contamination is therefore not possible.

[0047] However, in the wafer processing method according to embodiment 1, in the sheet placement step 1004, the adhesive layer 122 of the protective tape 12 is filled into the laser-processed groove 35, so that in the dicing step 1005, the cutting fluid containing cutting chips can be prevented from flowing around to the surface 3 of the wafer 1 and adhering to the surface 3.

[0048] Furthermore, in the wafer processing method according to embodiment 1, a protective film 25 is formed on the surface 3 of the wafer 1 in the protective film formation step 1001 before the laser groove formation step 1002, so that debris generated when the laser beam 33 is irradiated can be prevented from adhering to the surface 3 of the wafer 1.

[0049] [Embodiment 2] A wafer processing method according to a second embodiment will be described with reference to the drawings. FIG. 12 is a flowchart showing the flow of the wafer processing method according to the second embodiment. FIG. 13 is a perspective view schematically showing a wafer after a sheet disposing step in the wafer processing method shown in FIG. 12. FIG. 14 is a cross-sectional view schematically showing a main part of the wafer shown in FIG. 13. FIG. 15 is a cross-sectional view schematically showing a main part of the wafer after a dicing step in the wafer processing method shown in FIG. 12. FIG. 16 is a side view, partially in cross section, schematically showing a wafer back surface cleaning step in the wafer processing method shown in FIG. 12. FIG. 17 is a perspective view schematically showing a wafer after a transfer step in the wafer processing method shown in FIG. 12. FIG. 18 is a side view, partially in cross section, schematically showing a protective film removing step in the wafer processing method shown in FIG. 12.

[0050] 12, 13, 14, 15, 16, 17, and 18, the same parts as those in embodiment 1 are denoted by the same reference numerals, and description thereof will be omitted. As shown in Fig. 12, the wafer processing method according to embodiment 2 includes a protective film forming step 1001, a laser-processed groove forming step 1002, a sheet providing step 1004, a dicing step 1005, a wafer back surface cleaning step 1010, a transfer step 1011, and a protective film removing step 1003. In the wafer processing method according to embodiment 2, the protective film forming step 1001 and the laser-processed groove forming step 1002 are the same as those in embodiment 1.

[0051] Similar to embodiment 1, sheet disposing step 1004 of the wafer processing method according to embodiment 2 is a step of adhering a resin sheet 14 shown in Fig. 13 to the front surface 3 of the wafer 1 after performing laser groove forming step 1002 and before performing dicing step 1005, and filling part of the resin sheet 14 in the laser grooves 35. Also, in embodiment 2, in sheet disposing step 1004, as shown in Fig. 14, a resin sheet 14 having only a base layer 141 and no adhesive glue layer is adhered as a sheet to the front surface 3 of the wafer 1 via a protective film 25.

[0052] The base layer 141 is made of a flexible, non-adhesive thermoplastic resin. The thermoplastic resin that makes up the base layer 141, i.e., the resin sheet 14, is made of a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, or a polyolefin-based resin such as polyethylene, polypropylene, or polystyrene.

[0053] In the second embodiment, in the sheet providing step 1004, the back surface 7 of the wafer 1 and the annular frame 15 are placed on a heated holding table having a diameter larger than that of the wafer 1, and a disk-shaped resin sheet 14 having a diameter larger than that of the wafer 1 is placed on the front surface 3 of the wafer 1 and the annular frame 15. In the second embodiment, in the sheet providing step 1004, the resin sheet 14 is softened while being heated through the wafer 1 and pressed against the wafer 1 with a roller, and the resin sheet 14 is thermocompression-bonded to the front surface 3 of the wafer 1 via the protective film 25, and the annular frame 15 is thermocompression-bonded to the outer edge of the resin sheet 14, as shown in FIG. 13 . In the second embodiment, in the sheet providing step 1004, the adhesive tape 10 is peeled off from the back surface 7 of the wafer 1.

[0054] In the second embodiment, in the sheet providing step 1004, the resin sheet 14 is heated while being pressed against the wafer 1, so that a portion of the resin sheet 14 fills the laser-processed grooves 35, as shown in Fig. 14. Thus, in the second embodiment, in the sheet providing step 1004, the resin sheet 14 is heated and adhered to the protective film 25, thereby adhering the resin sheet 14 to the front surface 3 of the wafer 1.

[0055] In the second embodiment, in the sheet disposing step 1004, it is desirable to heat the resin sheet 14 to a temperature equal to or higher than the softening point and equal to or lower than the melting point, since the shape of the resin sheet 14 may not be maintained if the heating temperature of the resin sheet 14 exceeds the melting point of the resin sheet 14. Note that, during heating, the heat source may be set to a temperature higher than the melting point of the resin sheet 14.

[0056] In embodiment 2, it is desirable to heat the resin sheet 14 to a temperature that is at least 20° C. lower than the melting point and at most the melting point in sheet-laying step 1004. For example, in embodiment 2, in sheet-laying step 1004, if the resin sheet 14 is made of polyethylene terephthalate, it is desirable to heat the resin sheet 14 to a temperature of 240° C. or higher and 260° C. or lower, if the resin sheet 14 is made of polyethylene naphthalate, it is desirable to heat the resin sheet 14 to a temperature of 245° C. or higher and 265° C. or lower, if the resin sheet 14 is made of polypropylene, it is desirable to heat the resin sheet 14 to a temperature of 145° C. or higher and 165° C. or lower, if the resin sheet 14 is made of polystyrene, it is desirable to heat the resin sheet 14 to a temperature of 220° C. or higher and 240° C. or lower.

[0057] Also, in the present invention, in the sheet providing step 1004, the back surface 7 of the wafer 1 and the annular frame 15 may be placed on a holding table at room temperature, a disk-shaped resin sheet 14 having a diameter larger than that of the wafer 1 may be placed on the front surface 3 of the wafer 1 and the annular frame 15, and the resin sheet 14 may be pressed with a heater roller heated to a predetermined temperature while the heater roller rolls on the resin sheet 14 to perform thermocompression bonding. Also, in the present invention, in the sheet providing step 1004, the resin sheet 14 may be brought into close contact with the wafer 1, and then the resin sheet 14 may be thermocompression bonded to the wafer 1 by spraying hot air from a heat gun or heating with a lamp or the like.

[0058] In the present invention, in the sheet disposing step 1004, similarly to the first embodiment, a protective tape 12 may be attached to the front surface 3 of the wafer 1 as the sheet.

[0059] As in the first embodiment, the dicing step 1005 of the wafer processing method according to the second embodiment is a step in which, after the laser groove forming step 1002 is performed, the cutting blade 54 is inserted from the back surface 7 of the wafer 1 to a depth reaching the laser groove 35 at the center in the width direction, which is a predetermined position of the dividing line 4, while cutting the wafer 1 along the dividing line 4 with the cutting blade 54, thereby dividing the wafer 1. Also, in the dicing step 1005 of the wafer processing method according to the second embodiment, as in the first embodiment, the wafer 1 is cut with the cutting blade 54 while supplying cutting fluid to the processing point where the cutting blade 54 and the wafer 1 come into contact.

[0060] In the second embodiment, in the dicing step 1005, the cutting device 50 causes the cutting blade 54 to reach the laser-processed groove 35 and cut into the wafer 1 to a depth that is shallower than the thickness of the substrate 2 and does not reach the resin sheet 14. Thus, in the second embodiment, in the dicing step 1005, the cutting blade 54 cuts into the resin sheet 14 to a depth that does not completely cut through it.

[0061] Then, in the dicing step 1005, the cutting blade 54 is caused to cut into the center of the width direction of the dividing lines 4 to the aforementioned depth, so that the laser processed grooves 35 are exposed at the bottom of the cut grooves 55 formed by cutting with the cutting blade 54, and the dividing lines 4 are divided by the cut grooves 55 and the laser processed grooves 35, as shown in Fig. 15. In the dicing step 1005, all of the dividing lines 4 are cut with the cutting blade 54 to form the cut grooves 55 on all of the dividing lines 4, and the wafer 1 is divided into individual devices 5.

[0062] Wafer backside cleaning step 1010 is a step of cleaning the backside 7 of wafer 1 after dicing step 1005. In wafer backside cleaning step 1010, cleaning device 60 suction-holds the front side 3 of wafer 1 on the holding surface of spinner table 61 via resin sheet 14, and clamps annular frame 15 with clamps 62 provided around spinner table 61. In wafer backside cleaning step 1010, cleaning device 60 supplies cleaning liquid 64 made of pure water from cleaning liquid supply nozzle 63 to the center of backside 7 of wafer 1 while rotating spinner table 61 around its axis, as shown in FIG. 16 . Cleaning liquid 64 supplied to backside 7 of wafer 1 flows from the center toward the outer periphery over backside 7 of wafer 1 due to centrifugal force generated by the rotation of spinner table 61, cleaning backside 7 of wafer 1 and removing cutting debris and the like from backside 7 of wafer 1. It should be noted that the device layer 6 is omitted from FIG.

[0063] 17 is attached to the back surface 7 of the wafer 1 and the resin sheet 14 is removed from the front surface 3 of the wafer 1 after the dicing step 1005 is performed. In the transfer step 1011, similar to the protective tape 12, the tape 16 having a base layer and an adhesive layer laminated on the base layer is attached to the back surface 7 of the wafer 1.

[0064] 17, in the transfer step 1011, an adhesive layer of a disk-shaped tape 17 having a diameter larger than that of the wafer 1 is adhered to the back surface 7 of the wafer 1, and an annular frame 18 is adhered to the outer edge of the tape 17, the wafer 1 is supported by the annular frame 18, and the resin sheet 14 is peeled off from the front surface 3. In the present invention, the tape 17 may have only a base layer, like the resin sheet 14, and may not have an adhesive layer.

[0065] The protective film removing step 1003 in the wafer processing method according to the second embodiment is a step of removing the protective film 25 from the front surface 3 of the wafer 1 after the transferring step 1011 is performed. In the protective film removing step 1003, the cleaning device 40 suction-holds the back surface 7 of the wafer 1 on the holding surface of the spinner table 41 via the tape 17, clamps the annular frame 18 with the clamping unit 42, and removes the protective film 25 together with debris from the front surface 3 of the wafer 1, as in the first embodiment, as shown in Fig. 18. Note that the device layer 6 is omitted from Fig. 18.

[0066] The wafer processing method of embodiment 2 irradiates a laser beam 33 onto the front surface 3 of the wafer 1 to form a laser processed groove 35, and cuts the intended dividing lines 4 from the back surface 7 of the wafer 1 with a cutting blade 54, thereby achieving the effect of increasing the number of devices 5 per wafer 1, as in embodiment 1.

[0067] Furthermore, in the wafer processing method according to embodiment 2, in the sheet placement step 1004, a portion of the resin sheet 14 is filled in the laser-processed groove 35, so that in the dicing step 1005, the cutting fluid containing cutting chips can be prevented from flowing around to the surface 3 of the wafer 1 and adhering to the surface 3.

[0068] Furthermore, in the wafer processing method according to embodiment 2, a protective film 25 is formed on the surface 3 of the wafer 1 in the protective film formation step 1001 before the laser groove formation step 1002, thereby preventing debris from adhering to the surface 3 of the wafer 1.

[0069] Furthermore, in the wafer processing method according to embodiment 2, the protective film 25 is left in place during the dicing step 1005, which further reduces the risk of dirt adhering to the surface 3 of the wafer 1 during cutting, and also suppresses the risk of dirt adhering to the surface 3 of the wafer 1 during the transfer step 1011.

[0070] Furthermore, in the wafer processing method of embodiment 2, when the protective tape 12 is adhered to the surface 3 of the wafer 1 in the sheet placement step 1004 as in embodiment 1, the protective tape 12 is adhered to the surface 3 via the protective film 25, thereby reducing the risk that a portion of the adhesive layer 122 of the protective tape 12 will adhere to the surface 3 of the wafer 1 and remain.

[0071] The present invention is not limited to the above-described embodiment. That is, various modifications can be made without departing from the gist of the present invention. In the present invention, in the sheet disposing step 1004 of the wafer processing method according to the first embodiment, the resin sheet 14 shown in the second embodiment may be attached to the surface 3 of the wafer 1. [Explanation of symbols]

[0072] 1 wafer 3 surface 4 Planned division line 5 Devices 7 Back side 12 Protective tape (sheet) 14 Resin sheet (sheet) 17 Tape 25 Protective film 35 Laser-machined grooves 54 Cutting blade 1001 Protective film formation step 1002 Laser processing groove forming step 1003 Protective film removal step 1004 Sheet placement step 1005 Dicing Step 1011 Transcription step

Claims

1. A method for processing a wafer having devices formed in areas partitioned by a plurality of intersecting planned dividing lines on a surface, comprising the steps of: a laser groove forming step of irradiating the surface of the wafer with a laser beam having a wavelength that is absorbed by the wafer to form laser grooves along the intended dividing lines; a dicing step in which, after the laser-processed groove forming step, a cutting blade is inserted from the back surface of the wafer to a depth reaching the laser-processed groove, and the wafer is cut along the planned dividing lines with the cutting blade to divide the wafer; a sheet disposing step of adhering a sheet having a thickness greater than the depth of the laser-processed grooves to the surface of the wafer after the laser-processed groove forming step and before the dicing step, and filling the laser-processed grooves with the sheet; In the sheet disposing step, the sheet is filled into the laser processed groove, and In the dicing step, the cutting blade is caused to cut into the wafer to a depth that does not reach the sheet.

2. A wafer processing method as described in claim 1, wherein in the dicing step, the wafer is cut with the cutting blade while supplying cutting fluid to the processing point where the cutting blade and the wafer come into contact.

3. a protective film forming step of forming a protective film on the surface of the wafer before performing the laser processing groove forming step; In the sheet disposing step, the sheet is attached onto the protective film; a transfer step of attaching a tape to the back surface of the wafer and removing the sheet from the front surface of the wafer after the dicing step is performed; 3. The wafer processing method according to claim 2, further comprising a protective film removing step of removing the protective film after the transferring step is performed.

4. 4. The wafer processing method according to claim 2, wherein in the dicing step, the cutting blade is caused to cut into the sheet to a depth that does not completely cut through the sheet.

5. The sheet does not have an adhesive layer, 5. The wafer processing method according to claim 1, wherein the sheet is heated in the sheet disposing step to adhere the sheet to the surface of the wafer.

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