Wafer processing method

Abstract

To provide a wafer processing method capable of suppressing contamination attached to a device.SOLUTION: A wafer processing method includes a preparation step 1001 of preparing a wafer, a frame and a sheet formed of a thermoplastic resin, an integration step 1002 of making the wafer opposite to a surface side of the sheet and making the frame opposite to a rear face side of the sheet, heating the sheet and fixing the heated sheet to the wafer and the frame, and forming a frame unit in which the wafer is supported by the sheet in the opening of the frame, and a processing step 1003 of holding the wafer by a chuck table through the sheet of the frame unit, and processing the wafer while supplying a processing liquid to a surface to which the wafer is exposed, in which the processing step 1003 covers at least an inner peripheral edge of the frame with the sheet, and flows the processing liquid supplied to the wafer on the sheet covering the frame and discharges the processing liquid.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Semiconductor device chips are manufactured by forming devices on a semiconductor wafer such as silicon, grinding and thinning it, and dividing it with a cutting blade or a laser beam. During these processes, an adhesive tape is attached to the surface of the wafer as a protective member so that the semiconductor wafer is not damaged. In particular, during grinding, it is attached to the device surface of the semiconductor wafer, and during cutting, it is attached to the back surface of the semiconductor wafer in order to photograph the planned division line.

[0003] In order to facilitate the conveyance of the semiconductor wafer divided into device chips during cutting, during cutting, the semiconductor wafer is fixed to the opening of the frame via an adhesive tape (see, for example, Patent Document 1). For this reason, it is common to replace the adhesive tape on the front and back during grinding and cutting, but this requires replacement man-hours.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The adhesive tape is fixed to the semiconductor wafer by the adhesive force of the adhesive layer, but the adhesive layer is cut during processing and becomes fine contamination, which may adhere to the semiconductor wafer and adversely affect the device. Furthermore, the contamination attached to the adhesive layer around the semiconductor wafer may scatter during the manufacturing process and adhere to the semiconductor wafer or the device. For this reason, during grinding and cutting, in order to suppress the contamination adhering to the device, it is important to discharge the contamination generated by the crushing process without stagnation.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide a method for processing a wafer capable of suppressing contamination adhering to a device.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, a method for processing a wafer according to the present invention is a method for processing a wafer in which devices are formed in respective regions of a surface partitioned by a planned division line, the method including: a wafer; a frame having an opening for accommodating the wafer; Without a paste layer a preparation step of preparing a sheet formed of a thermoplastic resin and larger than the opening of the frame; an integration step of facing the wafer to the front surface side of the sheet and the frame to the back surface side of the sheet, heating the sheet, and thermocompression bonding and fixing the wafer and the frame to form a frame unit in which the wafer is supported by the sheet in the opening of the frame; and a processing step of holding the wafer via the sheet of the frame unit by a chuck table and processing the wafer while supplying a processing liquid to the exposed surface of the wafer. In the processing step, at least an inner peripheral edge of the frame is covered with the sheet, the processing liquid supplied to the wafer flows on the sheet covering the frame and is discharged, the frame is positioned below the exposed surface of the wafer, and the frame is clamped in a state inclined such that a space between an outer peripheral edge of the wafer and an inner peripheral edge of the frame of the sheet gradually descends toward the outer periphery.

[0008] In the method for processing a wafer, in the processing step, the wafer may be ground with a grinding wheel, cut with a cutting blade, or cleaned with a processing liquid.

[0009] In the method for processing the wafer, in the integration step, the surface of the wafer is fixed to the surface of the sheet. In the processing step, the surface of the wafer may be photographed with a camera through the sheet, the planned division line may be determined from the acquired image, and the wafer may be cut from the back surface along the determined planned division line with a cutting blade.

Advantages of the Invention

[0010] The method for processing a wafer according to the present invention has an effect of suppressing contamination adhering to the device.

Brief Description of the Drawings

[0011]

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[0012] Embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the content described in the following embodiments. Further, the constituent elements described below include those that can be easily assumed by those skilled in the art and substantially identical ones. Furthermore, the configurations described below can be combined as appropriate. Also, various omissions, substitutions, or changes in the configuration can be made without departing from the gist of the present invention.

[0013] **[Embodiment 1]** A wafer processing method according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a wafer to be processed in a wafer processing method according to Embodiment 1. FIG. 2 is a flowchart showing the flow of the wafer processing method according to Embodiment 1.

[0014] The wafer processing method according to Embodiment 1 is a method for processing the wafer 1 shown in FIG. 1. The wafer 1 to be processed in the wafer processing method according to Embodiment 1 is a disk-shaped semiconductor wafer having a substrate 2 made of silicon (Si), sapphire (Al 2 O 3 ), gallium arsenide (GaAs), silicon carbide (SiC), or the like, or a wafer such as an optical device wafer.

[0015] As shown in FIG. 1, on each region of the surface 4 of the substrate 2 partitioned by a plurality of division planned lines 3 intersecting each other, a device 5 is formed on the wafer 1. 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), an LED (Light Emitting Diode), or the like.

[0016] The wafer processing method according to Embodiment 1 includes a preparation step 1001, an integration step 1002, and a processing step 1003, as shown in FIG. 2.

[0017] (Preparation Step) FIG. 3 is a perspective view showing the preparation step of the wafer processing method shown in FIG. 2. The preparation step 1001 is a step of preparing the wafer 1, the frame 10, and the sheet 20, as shown in FIG. 3.

[0018] The frame 10 is formed in an annular shape with the inner diameter of the inner opening 11 being larger than the outer diameter of the wafer 1. The frame 10 has an opening 11 for accommodating the wafer 1 on the inside in a plan view. In Embodiment 1, the frame 10 is made of metal or a hard resin.

[0019] The sheet 20 is formed in a sheet shape from a thermoplastic resin, and the planar shape is larger than the opening 11 of the frame 10. In Embodiment 1, the sheet 20 is formed in a disk shape with a flat front surface 21 and a back surface 22 whose outer diameter is larger than the inner diameter of the opening 11. The sheet 20 has flexibility and non-stickiness, is composed of a thermoplastic resin, and does not include an adhesive layer composed of an adhesive resin. In Embodiment 1, the sheet 20 is composed of a resin that is transparent or translucent to visible light. In Embodiment 1, the sheet 20 is a sheet of a polymer synthesized using an alkene as a monomer, and is composed of, for example, polyethylene, polypropylene, polystyrene, or the like as the thermoplastic resin.

[0020] In Embodiment 1, in Preparation Step 1001, as shown in FIG. 3, the wafer 1, the frame 10, and the sheet 20 having the above-described configuration are prepared.

[0021] (Integration Step) FIG. 4 is a side view showing, in a partial cross section, a state in which a sheet is stacked on the back surface of the wafer in the integration step of the wafer processing method shown in FIG. 2. FIG. 5 is a side view showing, in a partial cross section, a state in which a frame is stacked on the sheet on the back surface of the wafer in the integration step of the wafer processing method shown in FIG. 2. FIG. 6 is a perspective view showing the frame unit formed in the integration step of the wafer processing method shown in FIG. 2.

[0022] Integration Step 1002 is a step of facing the wafer 1 to the front surface 21 side of the sheet 20 and the frame 10 to the back surface 22 side of the sheet 20, heating the sheet 20, and thermocompression bonding and fixing it to the wafer 1 and the frame 10 to form a frame unit 30 (shown in FIG. 6) in which the wafer 1 is supported by the sheet 20 in the opening 11 of the frame 10.

[0023] In Embodiment 1, in the integration step 1002, as shown in FIG. 4, the surface 4 side of the wafer 1 is placed at the center of the flat upper surface 41 of the support base 40, and the central portion on the surface 21 side, which is one surface of the sheet 20, is overlapped with the back surface 6 side of the substrate 2 on the back side of the surface 4 of the wafer 1. In Embodiment 1, in the integration step 1002, a roller 42 that is cylindrical and moves along the back surface 6 of the wafer 1 is used to sequentially overlap the upper surface 41 of the support base 40 and the back surface 6 of the wafer 1 from one end side to the other end side of the sheet 20. In Embodiment 1, in the integration step 1002, the outer edge portion of the surface 21 of the sheet 20 is placed on the upper surface 41 of the support base 40, and the central portion of the surface 21 of the sheet 20 is placed on the back surface 6 of the wafer 1.

[0024] In Embodiment 1, in the integration step 1002, in this way, the central portion of the surface 21 of the sheet 20 is placed on the back surface 6 of the wafer 1, and the wafer 1 is faced to the central portion on the surface 21 side of the sheet 20. Then, in Embodiment 1, in the integration step 1002, as shown in FIG. 5, the frame 10 is placed on the outer edge portion of the back surface 22, which is the other surface on the back side of the surface 21 of the sheet 20, and the frame 10 is faced to the outer edge portion on the back surface 22 side of the sheet 20. In Embodiment 1, in the integration step 1002, the sheet 20, the wafer 1, and the frame 10 are arranged at positions where they are coaxial with each other.

[0025] In the integration step 1002, the surface 21 of the sheet 20 and the wafer 1 are brought into close contact, the back surface 22 of the sheet 20 and the frame 10 are brought into close contact, and the temperature is raised to near the melting point of the sheet 20. In the integration step 1002, the sheet 20 is partially melted to bond the surface 21 of the sheet 20 and the wafer 1, and to bond the back surface 22 of the sheet 20 and the frame 10.

[0026] Specifically, in Embodiment 1, in the integration step 1002, while moving the roller 42 along the back surface 6 of the wafer 1, it is rolled on the 22 of the frame 10 and the sheet 20, the frame 10 is pressed toward the sheet 20 and the sheet 20 is pressed toward the wafer 1, so that the front surface 21 of the sheet 20 is brought into close contact with the wafer 1, and the back surface 22 of the sheet 20 is brought into close contact with the frame 10. In Embodiment 1, in the integration step 1002, while pressing the frame 10 toward the sheet 20 and pressing the sheet 20 toward the wafer 1, it is heated by a heater (not shown) installed in the support base 40 or the like to a temperature near the melting point of the sheet 20 for a predetermined time.

[0027] In Embodiment 1, in the integration step 1002, the front surface 21 of the sheet 20 is adhered to the wafer 1, and the back surface 22 of the sheet 20 is adhered to the frame 10, and the sheet 20 is thermocompression bonded and fixed to the wafer 1 and the frame 10 to form the frame unit 30 shown in FIG. 6. In the frame unit 30, in a plan view, the wafer 1 is supported by the sheet 20 on the inner peripheral side of the opening 11 of the frame 10. Further, in the frame unit 30, the frame 10 is adhered to the back surface 22 of the sheet 20, and the inner peripheral edge 12 of the frame 10 does not protrude (is non-protruding) from the sheet 20 in the thickness direction of the sheet 20 on the front surface 21 side of the sheet 20.

[0028] (Processing Step) FIG. 7 is a side view showing a part of the processing step of the wafer processing method shown in FIG. 2 in a partial cross section. The processing step 1003 is a step of holding the wafer 1 by the chuck table 51 through the sheet 20 of the frame unit 30 and cutting the wafer 1 (corresponding to processing) while supplying the processing liquid 100 to the exposed surface 4 of the wafer 1.

[0029] In Embodiment 1, in processing step 1003, a cutting device 50, which is a processing device, sucks and holds the back surface 6 of the wafer 1 via a sheet 20 on the holding surface 52 of a chuck table 51, and partially clamps a frame 10 with two or more clamp portions 53 provided around the chuck table 51. At this time, in processing step 1003, the clamp portion 53 fixes the outer edge portion of the sheet 20 below the central portion.

[0030] Further, in the frame unit 30, since the wafer 1 is adhered to the front surface 21 of the sheet 20 and the frame 10 is adhered to the back surface 22 of the sheet 20, at least the inner peripheral edge 12 of the frame 10 is covered with the sheet 20. In processing step 1003, a cutting device 50 photographs the front surface 4 of the wafer 1 with a camera (not shown), determines a division planned line 3 from an image acquired by the camera photographing, and performs alignment for aligning the division planned line 3 and a cutting blade 54.

[0031] In processing step 1003, the cutting device 50 rotates the cutting blade 54 by a spindle 56, and while supplying a processing liquid 100 from a processing liquid supply nozzle 55 to the front surface 4 side of the wafer 1, relatively moves the cutting blade 54 and the wafer 1 along the division planned line 3 to cut the cutting blade 54 into each division planned line 3. In processing step 1003, as shown in FIG. 7, the cutting device 50 cuts the cutting blade 54 along each division planned line 3 to the sheet 20, cuts the wafer 1 from the front surface 4, and divides the wafer 1 into individual devices 5. Thus, in Embodiment 1, in processing step 1003, the wafer 1 is cut by the cutting blade 54.

[0032] Also, in Embodiment 1, in the processing step 1003, pure water is used as the processing liquid 100. In the processing step 1003, the processing liquid 100 supplied to the surface 4 side of the wafer 1 flows on the surface 4 of the wafer 1 as shown by the arrow in FIG. 7, and then flows on the surface 21 of the sheet 20 covering the inner peripheral edge 12 of the frame 10, and is discharged to the outer peripheral side of the frame 10 without colliding with the inner peripheral edge 12 of the frame 10. In Embodiment 1, in the processing step 1003, when the cutting device 50 cuts all the division planned lines 3 of the wafer 1, the wafer processing method according to Embodiment 1 ends. Note that the divided devices 5 are picked up after the processing step 1003. At that time, in order to weaken the fixing force of the sheet 20, the sheet 20 is reheated and then picked up.

[0033] In the wafer processing method according to Embodiment 1 described above, in the integration step 1002, the wafer 1 is adhered to the surface 21 of the sheet 20 formed of a thermoplastic resin without an adhesive layer, and the frame 10 is adhered to the back surface 22 to form a so-called frame unit 30. For this reason, since the wafer processing method uses the sheet 20 without an adhesive layer, it is possible to prevent the adhesion of contaminants to the adhesive layer around the wafer 1 of the frame unit 30 caused by the adhesive layer of the conventional protective tape.

[0034] Also, conventionally, the processing liquid 100 containing contaminants generated during processing stayed in the step between the adhesive tape and the inner peripheral edge 12 of the frame 10, and the adhesive tape was likely to be contaminated. However, in the wafer processing method according to Embodiment 1, in the processing step 1003, since the sheet 20 covers and is fixed to at least the inner peripheral edge 12 of the frame 10, the step disappears, the retention of the processing liquid 100 is suppressed, it easily flows out to the outside, and the adhesion of contaminants to the sheet 20 can be suppressed.

[0035] Also, in the wafer processing method according to Embodiment 1, in the processing step 1003, since the sheet 20 covers and is fixed to at least the inner peripheral edge 12 of the frame 10, it is also possible to suppress the adhesion of contaminants to the frame 10.

[0036] As a result, the wafer processing method according to Embodiment 1 has the effect of suppressing contaminants adhering to the device 5.

[0037] 〔Embodiment 2〕 The wafer processing method according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 8 is a perspective view showing a frame unit formed in the integration step of the wafer processing method according to Embodiment 2. FIG. 9 is a side view showing a grinding apparatus for grinding a wafer in a processing step of the wafer processing method according to Embodiment 2 in a partial cross section. FIG. 10 is a side view showing a cleaning apparatus for cleaning a wafer in a processing step of the wafer processing method according to Embodiment 2 in a partial cross section. Note that the same reference numerals are given to the same parts as in Embodiment 1, and the description thereof is omitted.

[0038] The wafer processing method according to Embodiment 2 is the same as that of Embodiment 1, except that in the integration step 1002, as shown in FIG. 8, the surface 4 of the wafer 1 is adhered to the center of the surface 21 of the sheet 20, and the processing step 1003 is different.

[0039] In the integration step 1002 of the wafer processing method according to Embodiment 2, the surface 4 of the wafer 1 is adhered to the center of the surface 21 of the sheet 20, and the frame 10 is adhered to the outer edge portion of the back surface 22 of the sheet 20 to form the frame unit 30-2 shown in FIG. 8. Note that when the wafer 1 and the frame 10 are adhered to the sheet 20 in the integration step 1002 of Embodiment 2, thermocompression bonding is performed in the same manner as in Embodiment 1.

[0040] The wafer processing method according to Embodiment 2 is such that, in processing step 1003, the grinding device 60, which is a processing device, holds the wafer 1 on the chuck table 61 via the sheet 20 of the frame unit 30, and grinds (equivalent to processing) the wafer 1 while supplying the processing liquid 100 to the back surface 6, which is the exposed surface of the wafer 1. Then, the cleaning device 70, which is a processing device, holds the wafer 1 on the chuck table 71 via the sheet 20 of the frame unit 30, and cleans (equivalent to processing) the wafer 1 while supplying the processing liquid 100 to the back surface 6, which is the exposed surface of the wafer 1.

[0041] Specifically, in Embodiment 2, in processing step 1003, first, the grinding device 60 sucks and holds the front surface 4 of the wafer 1 on the holding surface 62 of the chuck table 61 via the sheet 20, and partially clamps the frame 10 with two or more clamp parts 63 provided around the chuck table 61. At this time, the clamp part 63 fixes the outer edge part of the sheet 20 below the central part. Also, similar to Embodiment 1, at least the inner peripheral edge 12 of the frame 10 is covered with the sheet 20. In processing step 1003, while supplying the processing liquid 100 from the processing liquid supply nozzle 65 to the back surface 6 of the wafer 1, the grinding wheel 67 is rotated around the axis by the spindle 66 and the chuck table 61 is rotated around the axis.

[0042] In Embodiment 2, in processing step 1003, the grinding device 60 makes the grinding stone 68 of the grinding wheel 67 contact the back surface 6 of the wafer 1, and approaches the grinding wheel 67 to the chuck table 61 at a predetermined grinding feed rate with a grinding feed unit (not shown), and grinds the back surface 6 of the wafer 1 sucked and held on the holding surface 62 of the chuck table 61 with the grinding stone 68 of the grinding wheel 67, thereby thinning the wafer 1 to a predetermined finish thickness.

[0043] In addition, in Embodiment 2, in processing step 1003, the grinding apparatus 60 uses pure water as the processing liquid 100. In processing step 1003, the processing liquid 100 supplied to the back surface 6 side of the wafer 1 flows on the back surface 6 of the wafer 1 as shown by the arrow in FIG. 9, and then flows on the surface 21 of the sheet 20 covering the inner peripheral edge 12 of the frame 10, and is discharged to the outer peripheral side of the frame 10 without colliding with the inner peripheral edge 12 of the frame 10. Thus, in Embodiment 2, in processing step 1003, the wafer 1 is ground with the grinding wheel 68.

[0044] Also, in Embodiment 2, in processing step 1003, after the wafer 1 is ground and thinned to the finish thickness, the cleaning apparatus 70 sucks and holds the front surface 4 of the wafer 1 on the holding surface 72 of the chuck table 71 via the sheet 20, and partially clamps the frame 10 with two or more clamp portions 73 provided around the chuck table 71. At this time, the clamp portion 73 fixes the outer edge portion of the sheet 20 below the central portion. Also, as in Embodiment 1, at least the inner peripheral edge 12 of the frame 10 is covered with the sheet 20. In processing step 1003, the processing liquid 100 is supplied from the processing liquid supply nozzle 75 to the back surface 6 of the wafer 1, and the chuck table 71 is rotated around the axis while moving the processing liquid supply nozzle 75 along the back surface 6 of the wafer 1 to wash the wafer 1 with the processing liquid 100.

[0045] Note that, in Embodiment 2, in processing step 1003, the cleaning apparatus 70 uses pure water as the processing liquid 100, but in the present invention, a chemical solution may be used. In processing step 1003, the processing liquid 100 supplied to the back surface 6 side of the wafer 1 flows on the back surface 6 of the wafer 1 as shown by the arrow in FIG. 10, and then flows on the surface 21 of the sheet 20 covering the inner peripheral edge 12 of the frame 10, and is discharged to the outer peripheral side of the frame 10 without colliding with the inner peripheral edge 12 of the frame 10. Thus, in Embodiment 2, in processing step 1003, the wafer 1 is washed with the processing liquid 100. In Embodiment 2, in processing step 1003, when the cleaning apparatus 70 washes the wafer 1 for a predetermined time, the wafer processing method according to Embodiment 2 ends.

[0046] In the wafer processing method according to Embodiment 2, in the integration step 1002, the wafer 1 is adhered to the front surface 21 of the sheet 20 formed of a thermoplastic resin without an adhesive layer, and the frame 10 is adhered to the back surface 22 to form a so-called frame unit 30-2. As a result, the wafer processing method can suppress the adhesion of contaminants to the adhesive layer around the wafer 1 of the frame unit 30, and has the effect of suppressing the contaminants adhering to the device 5 as in Embodiment 1.

[0047] In addition, in the wafer processing method according to Embodiment 2, in the processing step 1003, when the cleaning device 70 uses a chemical solution as the processing liquid 100 to clean the wafer 1, at least the inner peripheral edge 12 of the frame 10 is covered by the sheet 20, so that the frame 10 can be protected from the chemical solution. The wafer processing method according to Embodiment 2 is particularly effective when the frame 10 is made of resin.

[0048] In addition, in the wafer processing method according to Embodiment 2, since the wafer 1 is ground with the wafer 1 fixed by the frame 10, it is easy to fix the warped wafer 1 due to the formation of a metal film on the back surface 6 or the influence of each film constituting the device 5 on the front surface 4. Further, in the wafer processing method according to Embodiment 2, even if warping occurs due to grinding, since the wafer 1 is ground with the wafer 1 fixed by the frame 10, the fixation by the chuck table 61 is maintained.

[0049] Note that in Embodiment 2, in the processing step 1003, after the grinding device 60 grinds the wafer 1, the cleaning device 70 cleans the wafer 1. However, in the present invention, it is not limited to this, and in the processing step 1003, either one of the grinding by the grinding device 60 and the cleaning by the cleaning device 70 may be performed.

[0050] 〔Embodiment 3〕 A wafer processing method according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 11 is a perspective view showing a frame unit formed in the integration step of the wafer processing method according to Embodiment 3. FIG. 12 is a side view showing a processing step of the wafer processing method according to Embodiment 3 in a partial cross section. In FIGS. 11 and 12, the same parts as those in Embodiments 1 and 2 are denoted by the same reference numerals, and the description thereof will be omitted.

[0051] The wafer processing method according to Embodiment 3 is the same as that of Embodiment 1, except that in the integration step 1002, the surface 4 of the wafer 1 is adhered to the center of the surface 21 of the sheet 20 in the same manner as in Embodiment 2, and the processing step 1003 is different. In Embodiment 3, as shown in FIG. 11, the wafer 1 has silicon carbide (SiC) as the substrate 2, and a metal film 7 made of metal is formed on the back surface 6 of the substrate 2. In Embodiment 3, the metal film 7 is laminated on the entire back surface 6 of the substrate 2.

[0052] The wafer processing method according to Embodiment 3 is such that in the integration step 1002, in the same manner as in Embodiment 2, the surface 4 of the wafer 1 is adhered to the center of the surface 21 of the sheet 20, and the frame 10 is adhered to the outer edge portion of the back surface 22 of the sheet 20 to form the frame unit 30-3 shown in FIG. 11. Thus, in Embodiment 3, in the integration step 1002, the surface 4 of the wafer 1 is fixed (adhered) to the surface 21 of the sheet 20.

[0053] The wafer processing method according to Embodiment 3 is such that in the processing step 1003, the cutting device 50, which is a processing device, sucks and holds the surface 4 of the wafer 1 via the sheet 20 on the holding surface 52 of the chuck table 51, and partially clamps the frame 10 with two or more clamp portions 53 provided around the chuck table 51. At this time, the clamp portion 53 fixes the outer edge portion of the sheet 20 below the central portion. Also, in the same manner as in Embodiment 1, at least the inner peripheral edge 12 of the frame 10 is covered with the sheet 20. In Embodiment 3, at least the holding surface 52 of the chuck table 51 of the cutting device 50 is made of a transparent material such as glass.

[0054] In Embodiment 3, in processing step 1003, the cutting device 50 photographs the surface 4 of the wafer 1 via the sheet 20 and the chuck table 51 with a camera 57 disposed below the chuck table 51, determines the division planned line 3 from the image obtained by the camera 57, and performs alignment to align the division planned line 3 with the cutting blade 54. In Embodiment 3, in processing step 1003, the cutting device 50 rotates the cutting blade 54 by the spindle 56, and while supplying the processing liquid 100 to the side of the metal film 7 on the back surface 6 which is the exposed surface of the wafer 1 from the processing liquid supply nozzle 55, relatively moves the cutting blade 54 and the wafer 1 along the division planned line 3, and as in Embodiment 1, cuts the cutting blade 54 into each division planned line 3.

[0055] In Embodiment 3, in processing step 1003, as shown in FIG. 12, the cutting device 50 cuts the cutting blade 54 into the sheet 20 along each division planned line 3, and cuts the wafer 1 from the back surface 6 with the cutting blade 54 along the determined division planned line 3 to divide the wafer 1 into individual devices 5. Thus, in Embodiment 3, in processing step 1003, the wafer 1 is cut with the cutting blade 54.

[0056] Also, in Embodiment 3, in processing step 1003, pure water is used as the processing liquid 100. In processing step 1003, the processing liquid 100 supplied to the back surface 6 side of the wafer 1 flows on the metal film 7 on the back surface 6 side of the wafer 1 as shown by the arrow in FIG. 12, then flows on the surface 21 of the sheet 20 covering the inner peripheral edge 12 of the frame 10, and is discharged to the outer peripheral side of the frame 10 without colliding with the inner peripheral edge 12 of the frame 10. In Embodiment 3, in processing step 1003, when all the division planned lines 3 of the wafer 1 are cut, the wafer processing method according to Embodiment 3 is terminated.

[0057] In the wafer processing method according to Embodiment 3, in the integration step 1002, the wafer 1 is adhered to the surface 21 of the sheet 20 formed of a thermoplastic resin without an adhesive layer, and the frame 10 is adhered to the back surface 22 to form a so-called frame unit 30-3. As a result, the wafer processing method can suppress the adhesion of contaminants to the adhesive layer around the wafer 1 of the frame unit 30-3, and similar to Embodiment 1, can suppress the contaminants adhering to the device 5.

[0058] Further, in the wafer processing method according to Embodiment 3, since the sheet 20 that adheres the wafer 1 to the surface 21 does not have an adhesive layer, it is more transparent than the protective tape having an adhesive layer. As a result, in the wafer processing method according to Embodiment 3, the division planned line 3 can be accurately determined from the image of photographing the surface 4 of the wafer 1 through the sheet 20.

[0059] Note that the present invention is not limited to the above embodiments. That is, various modifications can be made and implemented without departing from the gist of the present invention. For example, before the integration step 1002, edge trimming may be performed to half-cut or full-cut the peripheral portion of the surface 4 of the wafer 1. Further, in the processing step 1003 of the embodiment, since the frame 10 is clamped and fixed, the sheet 20 is less likely to be peeled off from the frame 10. Further, in the processing step 1003 of the present invention, the sheet 20 side may be pulled and fixed by vacuum or magnetic force.

Explanation of Reference Numerals

[0060] 1 Wafer 3 Division planned line 4 Surface (exposed surface) 5 Device 6 Back surface (exposed surface) 10 Frame 11 Opening 12 Inner peripheral edge 20 Sheet 21 Surface 22 Back surface 30, 30-2, 30-3 Frame unit 51, 61, 71 Chuck table 54 Cutting blade 57 Camera 68 Grinding wheel 100 Processing fluid 1001 Preparation step 1002 Integration step 1003 Machining step

Claims

1. A method for processing a wafer in which devices are formed in each region of a surface partitioned by a planned division line, the method comprising: a preparation step of preparing a wafer, a frame having an opening for accommodating the wafer, and a sheet formed of a thermoplastic resin without an adhesive layer and larger than the opening of the frame; an integration step of facing the wafer on the front surface side of the sheet and the frame on the back surface side of the sheet, heating the sheet, and thermocompression bonding and fixing the wafer and the frame, thereby forming a frame unit in which the wafer is supported by the sheet in the opening of the frame; a processing step of holding the wafer via the sheet of the frame unit by a chuck table and processing the wafer while supplying a processing liquid to the exposed surface of the wafer; in the processing step, at least the inner peripheral edge of the frame is covered by the sheet, and the processing liquid supplied to the wafer flows over the sheet covering the frame and is discharged, and the frame is positioned below the wafer from the exposed surface of the wafer, and the frame is clamped in a state where the space between the outer peripheral edge of the wafer and the inner peripheral edge of the frame of the sheet gradually slopes downward toward the outer periphery. A method for processing a wafer, characterized in that.

2. The method for processing a wafer according to claim 1, wherein in the processing step, the wafer is ground with a grinding wheel, cut with a cutting blade, or cleaned with a processing liquid.

3. In the integration step, the surface of the wafer is fixed to the surface of the sheet. In the processing step, the surface of the wafer is photographed with a camera through the sheet, the planned division line is determined from the obtained image, and the wafer is cut from the back surface with a cutting blade along the determined planned division line. The method for processing a wafer according to claim 1 or claim 2.

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