JP7691817B2 - Wafer Processing Method - Google Patents

Description

The present invention relates to a wafer processing method.

Semiconductor device chips are manufactured by forming devices on semiconductor wafers such as silicon, grinding them to make them thinner, and then dividing them using a cutting blade or laser beam. During these processes, adhesive tape is applied to the front surface of the wafer as a protective material to prevent the semiconductor wafer from being damaged. In particular, adhesive tape is applied to the device surface of the semiconductor wafer during grinding, and to the back surface of the semiconductor wafer during cutting in order to photograph the planned division lines.

In order to facilitate the transportation of the semiconductor wafer divided into device chips during cutting, the semiconductor wafer is fixed to the opening of the frame via adhesive tape during cutting (see, for example, Patent Document 1). For this reason, it is common to switch the adhesive tape between the front and back when grinding and cutting, but this requires labor-intensive re-taping.

JP 2009-010150 A

Adhesive tape is fixed to semiconductor wafers by the adhesive power of the adhesive layer, but when the adhesive layer is cut off during processing, it turns into microscopic contaminants that adhere to the semiconductor wafer and can have a detrimental effect on the device. Furthermore, there is a risk that contaminants that adhere to the adhesive layer around the semiconductor wafer will scatter during the manufacturing process and adhere to the semiconductor wafer or device. For this reason, when grinding or cutting, it is important to remove contaminants generated during the crushing process without retention in order to prevent contaminants from adhering to devices.

The present invention was made in consideration of these problems, and its purpose is to provide a wafer processing method that can suppress contamination from adhering to devices.

In order to solve the above-mentioned problems and achieve the object, the wafer processing method of the present invention is a wafer processing method for processing a wafer having devices formed in each area of the surface partitioned by a planned division line, the method comprising the steps 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; placing the wafer on the front side of the sheet and the frame on the back side of the sheet, respectively, heating the sheet to thermocompress and fix the wafer and the frame to each other, and forming a frame unit in which the wafer is supported by the sheet at the opening of the frame; and a processing step of holding the wafer on a chuck table via the sheet of the frame unit and processing the wafer while supplying processing liquid to the exposed surface of the wafer, wherein in the processing step, at least the inner peripheral edge of the frame is covered with the sheet, the processing liquid supplied to the wafer flows over the sheet covering the frame and is discharged, and the frame is positioned below the exposed surface of the wafer and the frame is clamped in a state in which the space between the outer peripheral edge of the sheet of the wafer and the inner peripheral edge of the frame is gradually inclined downward toward the outer periphery.

In the wafer processing method, the wafer may be ground with a grinding wheel, cut with a cutting blade, or cleaned with a processing fluid in the processing step.

In the wafer processing method, the front surface of the wafer is fixed to the front surface of the sheet in the integration step, and in the processing step, the front surface of the wafer is photographed by a camera through the sheet, the planned division line is determined from the acquired image, and the wafer is cut from the rear surface along the determined planned division line with a cutting blade.

The wafer processing method of the present invention has the effect of suppressing contamination from adhering to devices.

FIG. 1 is a perspective view showing an example of a wafer to be processed by the wafer processing method according to the first embodiment. FIG. 2 is a flowchart showing a flow of the wafer processing method according to the first embodiment. FIG. 3 is a perspective view showing a preparatory step of the processing method of the wafer shown in FIG. FIG. 4 is a side view, partly in section, showing a state in which a sheet is laid on the back surface of the wafer in the integration step of the wafer processing method shown in FIG. FIG. 5 is a side view, partly in section, showing a state in which a frame is laid over a sheet on the rear surface of a wafer in the integration step of the wafer processing method shown in FIG. FIG. 6 is a perspective view showing a frame unit formed in the integration step of the wafer processing method shown in FIG. 7A to 7C are side views, partly in section, showing processing steps of the wafer processing method shown in FIG. FIG. 8 is a perspective view showing a frame unit formed in the integration step of the wafer processing method according to the second embodiment. FIG. 9 is a side view, partially in section, showing a grinding device that grinds a wafer in a processing step of a wafer processing method according to the second embodiment. FIG. 10 is a side view, partially in section, showing a cleaning device for cleaning a wafer in a processing step of the wafer processing method according to the second embodiment. FIG. 11 is a perspective view showing a frame unit formed in an integration step of the wafer processing method according to the third embodiment. FIG. 12 is a side view, partly in section, showing processing steps of the wafer processing method according to the third embodiment.

The following describes in detail the form (embodiment) for carrying out the present invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. 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 combined as appropriate. Various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

[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 showing an example of a wafer to be processed by the wafer processing method according to the first embodiment. Fig. 2 is a flow chart showing the flow of the wafer processing method according to the first embodiment.

The wafer 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 in the wafer processing method according to the first embodiment is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer having a substrate 2 made of silicon (Si), sapphire ( _Al2O3 ), gallium arsenide (GaAs), silicon carbide (SiC), or the _like .

As shown in FIG. 1, the wafer 1 has devices 5 formed in each region of the surface 4 of the substrate 2 that is partitioned by a plurality of mutually intersecting planned division lines 3. The devices 5 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integration), image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors), and LEDs (Light Emitting Diodes).

As shown in FIG. 2, the wafer processing method according to the first embodiment includes a preparation step 1001, an integration step 1002, and a processing step 1003.

(Preparation Step)
Fig. 3 is a perspective view showing a 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.

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. In a plan view, the frame 10 has an opening 11 on the inside that accommodates the wafer 1. In the first embodiment, the frame 10 is made of metal or hard resin.

The sheet 20 is formed in a sheet shape from a thermoplastic resin, and its planar shape is larger than the opening 11 of the frame 10. In the first embodiment, the sheet 20 is formed in a flat disk shape with a front surface 21 and a back surface 22 whose outer diameter is larger than the inner diameter of the opening 11. The sheet 20 is flexible and non-adhesive, is made of a thermoplastic resin, and does not have a glue layer made of an adhesive resin. In the first embodiment, the sheet 20 is made of a resin that is transparent or translucent to visible light. In the first embodiment, the sheet 20 is a sheet of a polymer synthesized using an alkene as a monomer, and is made of, for example, polyethylene, polypropylene, or polystyrene as a thermoplastic resin.

In embodiment 1, in preparation step 1001, the wafer 1, frame 10, and sheet 20 are prepared as shown in FIG. 3.

(Integration step)
Fig. 4 is a side view, partly in section, showing a state where a sheet is superimposed on the rear surface of a wafer in the integration step of the wafer processing method shown in Fig. 2. Fig. 5 is a side view, partly in section, showing a state where a frame is superimposed on the sheet on the rear surface of a wafer in the integration step of the wafer processing method shown in Fig. 2. Fig. 6 is a perspective view showing a frame unit formed in the integration step of the wafer processing method shown in Fig. 2.

In the integration step 1002, the wafer 1 is placed facing the front surface 21 of the sheet 20, and the frame 10 is placed facing the back surface 22 of the sheet 20, and the sheet 20 is heated to heat and press the wafer 1 to the frame 10, forming 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.

In the first embodiment, in the integration step 1002, as shown in FIG. 4, the front surface 4 side of the wafer 1 is placed in the center of the flat upper surface 41 of the support table 40, and the center of the front surface 21 side of the sheet 20 is placed on the back surface 6 side of the substrate 2 behind the front surface 4 of the wafer 1. In the first embodiment, in the integration step 1002, the sheet 20 is sequentially placed from one end side to the other end side on the upper surface 41 of the support table 40 and the back surface 6 of the wafer 1 by a cylindrical roller 42 that moves along the back surface 6 of the wafer 1. In the first embodiment, in the integration step 1002, the outer edge portion of the front surface 21 of the sheet 20 is placed on the upper surface 41 of the support table 40, and the center portion of the front surface 21 of the sheet 20 is placed on the back surface 6 of the wafer 1.

In the first embodiment, in the integration step 1002, the center of the front surface 21 of the sheet 20 is placed on the back surface 6 of the wafer 1, so that the wafer 1 faces the center of the front surface 21 side of the sheet 20. Then, in the first embodiment, in the integration step 1002, as shown in FIG. 5, the frame 10 is placed on the outer edge of the back surface 22, which is the other surface behind the front surface 21 of the sheet 20, so that the frame 10 faces the outer edge of the back surface 22 side of the sheet 20. In the first embodiment, in the integration step 1002, the sheet 20, the wafer 1, and the frame 10 are positioned so that they are coaxial with each other.

In the integration step 1002, 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, and the sheet 20 is heated to a temperature close to the melting point of the sheet 20. In the integration step 1002, the sheet 20 is partially melted to bond the front surface 21 of the sheet 20 to the wafer 1, and to bond the back surface 22 of the sheet 20 to the frame 10.

Specifically, in embodiment 1, in the integration step 1002, the roller 42 is moved along the back surface 6 of the wafer 1 and rolled on the frame 10 and the sheet 22 of the sheet 20, pressing the frame 10 against the sheet 20 and pressing the sheet 20 against the wafer 1 to bring the front surface 21 of the sheet 20 into close contact with the wafer 1 and the back surface 22 of the sheet 20 into close contact with the frame 10. In embodiment 1, in the integration step 1002, while pressing the frame 10 against the sheet 20 and pressing the sheet 20 against the wafer 1, the sheet 20 is heated to a temperature near the melting point of the sheet 20 for a predetermined time by a heater (not shown) installed in the support table 40 or the like.

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

(Processing step)
Fig. 7 is a side view partially in section showing the processing steps of the wafer processing method shown in Fig. 2. In the processing step 1003, the wafer 1 is held by the chuck table 51 via the sheet 20 of the frame unit 30, and the wafer 1 is cut (corresponding to processing) while the processing liquid 100 is supplied to the front surface 4, which is the exposed surface of the wafer 1.

In the first embodiment, in the processing step 1003, the cutting device 50, which is a processing device, suction-holds the back surface 6 of the wafer 1 on the holding surface 52 of the chuck table 51 via the sheet 20, and partially clamps the frame 10 with two or more clamp units 53 provided around the periphery of the chuck table 51. At this time, in the processing step 1003, the clamp units 53 fix the outer edge of the sheet 20 below the center.

In addition, in the frame unit 30, 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, so that at least the inner edge 12 of the frame 10 is covered with the sheet 20. In the processing step 1003, the cutting device 50 photographs the front surface 4 of the wafer 1 with a camera (not shown), determines the planned division line 3 from the image captured by the camera, and performs alignment to align the planned division line 3 with the cutting blade 54.

In processing step 1003, the cutting device 50 rotates the cutting blade 54 by the spindle 56, and while supplying processing fluid 100 from the processing fluid supply nozzle 55 to the front surface 4 side of the wafer 1, the cutting blade 54 and the wafer 1 are moved relatively along the planned division lines 3 to cause the cutting blade 54 to cut into each planned division line 3. In processing step 1003, as shown in FIG. 7, the cutting device 50 cuts the cutting blade 54 along each planned division line 3 up to the sheet 20, cutting the wafer 1 from the front surface 4 and dividing 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.

In the first embodiment, 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 front surface 4 side of the wafer 1 flows over the front surface 4 of the wafer 1 as shown by the arrow in FIG. 7, and then flows over the front 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 the first embodiment, in the processing step 1003, when the cutting device 50 cuts all the division lines 3 of the wafer 1, the processing method of the wafer according to the first embodiment is completed. The divided devices 5 are picked up after the processing step 1003, and at that time, the sheet 20 is reheated before being picked up in order to weaken the fixing force of the sheet 20.

In the wafer processing method according to the first embodiment described above, in the integration step 1002, the wafer 1 is bonded to the front surface 21 of the sheet 20 formed of a thermoplastic resin without an adhesive layer, and the frame 10 is bonded to the back surface 22 to form a so-called frame unit 30. Because 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, which is caused by the adhesive layer of the conventional protective tape.

In addition, conventionally, processing liquid 100 containing contaminants generated during processing would remain in the step between the adhesive tape and the inner peripheral edge 12 of the frame 10, making it easy for the contaminants to adhere to the adhesive tape. However, in the wafer processing method according to embodiment 1, in processing step 1003, the sheet 20 is fixed to cover at least the inner peripheral edge 12 of the frame 10, eliminating the step, suppressing the retention of processing liquid 100 and making it easier for it to flow outward, thereby making it possible to suppress the adhesion of contaminants to the sheet 20.

In addition, in the wafer processing method according to embodiment 1, in processing step 1003, the sheet 20 is fixed to cover at least the inner peripheral edge 12 of the frame 10, so that adhesion of contaminants to the frame 10 can be suppressed.

As a result, the wafer processing method according to embodiment 1 has the effect of suppressing contamination from adhering to device 5.

[Embodiment 2]
A wafer processing method according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 8 is a perspective view showing a frame unit formed in an integration step of the wafer processing method according to the second embodiment. Fig. 9 is a side view, partially in section, showing a grinding device that grinds a wafer in a processing step of the wafer processing method according to the second embodiment. Fig. 10 is a side view, partially in section, showing a cleaning device that cleans a wafer in a processing step of the wafer processing method according to the second embodiment. In Figs. 8, 9, and 10, the same parts as those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted.

The wafer processing method according to the second embodiment is the same as that according to the first embodiment, except that in the integration step 1002, the surface 4 of the wafer 1 is bonded to the center of the surface 21 of the sheet 20 as shown in FIG. 8, and the processing step 1003 is different.

In the wafer processing method according to the second embodiment, in the integration step 1002, the front surface 4 of the wafer 1 is adhered to the center of the front surface 21 of the sheet 20, and the frame 10 is adhered to the outer edge of the back surface 22 of the sheet 20 to form the frame unit 30-2 shown in FIG. 8. Note that in the integration step 1002 of the second embodiment, when the wafer 1 and the frame 10 are adhered to the sheet 20, they are thermocompression bonded in the same manner as in the first embodiment.

In the wafer processing method according to the second embodiment, in processing step 1003, a grinding device 60, which is a processing device, holds the wafer 1 on a chuck table 61 via the sheet 20 of the frame unit 30, and grinds the wafer 1 (corresponding to processing) while supplying a processing liquid 100 to the back surface 6, which is the exposed surface of the wafer 1, and a cleaning device 70, which is a processing device, holds the wafer 1 on a chuck table 71 via the sheet 20 of the frame unit 30, and cleans the wafer 1 (corresponding to processing) while supplying a processing liquid 100 to the back surface 6, which is the exposed surface of the wafer 1.

Specifically, in the second embodiment, in the processing step 1003, the grinding device 60 first suction-holds the front surface 4 of the wafer 1 on the holding surface 62 of the chuck table 61 via the sheet 20, and the frame 10 is partially clamped by two or more clamps 63 provided around the periphery of the chuck table 61. At this time, the clamps 63 fix the outer edge of the sheet 20 lower than the center. Also, as in the first embodiment, at least the inner edge 12 of the frame 10 is covered by the sheet 20. In the processing step 1003, the grinding wheel 67 is rotated around its axis by the spindle 66, and the chuck table 61 is rotated around its axis while the processing liquid 100 is supplied from the processing liquid supply nozzle 65 to the back surface 6 of the wafer 1.

In embodiment 2, in processing step 1003, the grinding device 60 brings the grinding stone 68 of the grinding wheel 67 into contact with the back surface 6 of the wafer 1, and moves the grinding wheel 67 toward the chuck table 61 at a predetermined grinding feed speed using a grinding feed unit (not shown), so that the grinding stone 68 of the grinding wheel 67 grinds the back surface 6 of the wafer 1 held by suction on the holding surface 62 of the chuck table 61, thereby thinning the wafer 1 to a predetermined finishing thickness.

In the second embodiment, in the processing step 1003, the grinding device 60 uses pure water as the processing liquid 100. In the processing step 1003, the processing liquid 100 supplied to the back surface 6 side of the wafer 1 flows over the back surface 6 of the wafer 1 as shown by the arrow in FIG. 9, and then flows over the front 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 the second embodiment, in the processing step 1003, the wafer 1 is ground by the grinding wheel 68.

In the second embodiment, in the processing step 1003, after the wafer 1 is ground to a finishing thickness, the cleaning device 70 suction-holds the front surface 4 of the wafer 1 on the holding surface 72 of the chuck table 71 via the sheet 20, and the frame 10 is partially clamped by two or more clamps 73 provided around the chuck table 71. At this time, the clamps 73 fix the outer edge of the sheet 20 below the center. As in the first embodiment, at least the inner edge 12 of the frame 10 is covered by the sheet 20. In the 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 its axis while the processing liquid supply nozzle 75 is moved along the back surface 6 of the wafer 1, to clean the wafer 1 with the processing liquid 100.

In the second embodiment, in the processing step 1003, the cleaning device 70 uses pure water as the processing liquid 100, but in the present invention, a chemical liquid may be used. In the processing step 1003, the processing liquid 100 supplied to the back surface 6 side of the wafer 1 flows over the back surface 6 of the wafer 1 as shown by the arrow in FIG. 10, and then flows over the front 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 the second embodiment, in the processing step 1003, the wafer 1 is cleaned with the processing liquid 100. In the second embodiment, in the processing step 1003, when the cleaning device 70 cleans the wafer 1 for a predetermined time, the wafer processing method according to the second embodiment is completed.

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

In addition, in the wafer processing method according to the second embodiment, when the cleaning device 70 uses a chemical liquid as the processing liquid 100 when cleaning the wafer 1 in the processing step 1003, 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 liquid. The wafer processing method according to the second embodiment is particularly effective when the frame 10 is made of resin.

In addition, the wafer processing method according to the second embodiment grinds the wafer 1 while it is fixed to the frame 10, so it is easy to fix the wafer 1 that has been warped due to the influence of the films that make up the device 5 on the front surface 4 or when a metal film is formed on the back surface 6. In addition, the wafer processing method according to the second embodiment grinds the wafer 1 while it is fixed to the frame 10, so that the wafer 1 remains fixed to the chuck table 61 even if warping occurs due to grinding.

In the second embodiment, the wafer processing method is such that in processing step 1003, the grinding device 60 grinds the wafer 1, and then the cleaning device 70 cleans the wafer 1. However, in the present invention, this is not limited to this, and in processing step 1003, it is sufficient to perform either grinding by the grinding device 60 or cleaning by the cleaning device 70.

[Embodiment 3]
A wafer processing method according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 11 is a perspective view showing a frame unit formed in an integration step of the wafer processing method according to the third embodiment. Fig. 12 is a side view showing a processing step of the wafer processing method according to the third embodiment, partially in cross section. In Figs. 11 and 12, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

The wafer processing method according to the third embodiment is the same as that of the first embodiment, except that in the integration step 1002, the front surface 4 of the wafer 1 is adhered to the center of the front surface 21 of the sheet 20 as in the second embodiment, and the processing step 1003 is different. In the third embodiment, as shown in FIG. 11, the wafer 1 has a silicon carbide (SiC) substrate 2, and a metal film 7 made of metal is formed on the rear surface 6 of the substrate 2. In the third embodiment, the metal film 7 is laminated over the entire rear surface 6 of the substrate 2.

In the wafer processing method according to the third embodiment, in the integration step 1002, similar to the second embodiment, the front surface 4 of the wafer 1 is adhered to the center of the front surface 21 of the sheet 20, and the frame 10 is adhered to the outer edge of the back surface 22 of the sheet 20 to form the frame unit 30-3 shown in FIG. 11. Thus, in the third embodiment, in the integration step 1002, the front surface 4 of the wafer 1 is fixed (adhered) to the front surface 21 of the sheet 20.

In the processing step 1003 of the wafer processing method according to the third embodiment, the cutting device 50, which is a processing device, suction-holds the front surface 4 of the wafer 1 on the holding surface 52 of the chuck table 51 via the sheet 20, and partially clamps the frame 10 with two or more clamps 53 provided around the periphery of the chuck table 51. At this time, the clamps 53 fix the outer edge of the sheet 20 below the center. Also, as in the first embodiment, at least the inner edge 12 of the frame 10 is covered with the sheet 20. In the third embodiment, 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.

In the third embodiment, in the processing step 1003, the cutting device 50 photographs the front surface 4 of the wafer 1 through the sheet 20 and the chuck table 51 with the camera 57 arranged below the chuck table 51, determines the planned division lines 3 from the image captured by the camera 57, and performs alignment to align the planned division lines 3 with the cutting blade 54. In the third embodiment, in the processing step 1003, the cutting device 50 rotates the cutting blade 54 with the spindle 56, and while supplying the processing fluid 100 from the processing fluid supply nozzle 55 to the metal film 7 side on the back surface 6, which is the exposed surface of the wafer 1, moves the cutting blade 54 and the wafer 1 relatively along the planned division lines 3, and cuts the cutting blade 54 into each planned division line 3, as in the first embodiment.

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 of the planned division lines 3, and cuts the wafer 1 from the back surface 6 with the cutting blade 54 along the determined planned division lines 3, dividing the wafer 1 into individual devices 5. Thus, in embodiment 3, in processing step 1003, the wafer 1 is cut by the cutting blade 54.

In the third embodiment, 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 back surface 6 side of the wafer 1 flows over the metal film 7 on the back surface 6 side of the wafer 1, as shown by the arrow in FIG. 12, and then flows over 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 the third embodiment, in the processing step 1003, when all the planned division lines 3 of the wafer 1 are cut, the processing method of the wafer according to the third embodiment is completed.

In the wafer processing method according to the third embodiment, in the integration step 1002, the wafer 1 is bonded to the front surface 21 of the sheet 20 formed of a thermoplastic resin without a glue layer, and the frame 10 is bonded to the back surface 22 to form a so-called frame unit 30-3. As a result, the wafer processing method can suppress adhesion of contaminants to the glue layer around the wafer 1 of the frame unit 30-3, and has the effect of suppressing contamination from adhering to the device 5, similar to the first embodiment.

In addition, in the wafer processing method according to the third embodiment, the sheet 20 that adheres the wafer 1 to the surface 21 does not have an adhesive layer, and is therefore more transparent than a protective tape that has an adhesive layer. As a result, in the wafer processing method according to the third embodiment, the planned division line 3 can be accurately determined from an image of the surface 4 of the wafer 1 photographed through the sheet 20.

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, the present invention may perform edge trimming to half-cut or fully-cut the peripheral portion of the surface 4 of the wafer 1 before the integration step 1002. In addition, in the embodiment, the frame 10 is clamped and fixed in the processing step 1003, so that the sheet 20 is less likely to peel off from the frame 10. In addition, the present invention may also perform the processing step 1003 by pulling and fixing the sheet 20 side with a vacuum or magnetic force.

1 Wafer 3 Planned division line 4 Surface (exposed surface)
5 Device 6 Back side (exposed surface)
REFERENCE SIGNS LIST 10 Frame 11 Opening 12 Inner periphery 20 Sheet 21 Front 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 Machining fluid 1001 Preparation step 1002 Integration step 1003 Machining step

Claims (3)

A wafer processing method for processing a wafer having devices formed in each area of a surface partitioned by dividing lines, comprising the steps of:
A preparation step of preparing a wafer, a frame having an opening for receiving the wafer, and a sheet made of a thermoplastic resin without a glue layer and larger than the opening of the frame;
an integration step of placing a wafer on the front side of the sheet and placing the frame on the back side of the sheet, heating the sheet to thermocompress and fix the wafer to the frame, and 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 on a chuck table via the sheet of the frame unit and processing the wafer while supplying a processing liquid to an exposed surface of the wafer,
In the processing step, at least the inner periphery of the frame is covered with the sheet, and the processing liquid supplied to the wafer flows over the sheet covering the frame and is discharged.
A method for processing a wafer, characterized in that the frame is positioned below the exposed surface of the wafer and the frame is clamped in a state in which the space between the outer peripheral edge of the wafer and the inner peripheral edge of the frame of the sheet is gradually inclined downward toward the outer periphery. The wafer processing method 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. The wafer processing method according to claim 1 or 2, in which in the integration step, the surface of the wafer is fixed to the surface of the sheet, and in the processing step, the surface of the wafer is photographed by a camera through the sheet, the planned division line is determined from the acquired image, and the wafer is cut from the back side along the determined planned division line with a cutting blade.

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