JP2020098827A - Wafer processing method - Google Patents

Abstract

To provide a wafer processing method that can be effectively divided into individual devices by performing cutting from the back surface of a wafer without degrading the quality of the device.SOLUTION: A wafer processing method according to the present invention in which a plurality of devices 12 are divided by planned dividing lines 14 and a wafer 10 formed on a surface 10a is divided into individual device chips includes at least a protective tape arranging step of arranging a protective tape 20 on the surface 10a of the wafer 10, a protective tape flattening step of flattening an upper surface 20a of the protective tape 20 by cutting with a cutting tool 62, and a dividing step of dividing an area corresponding to the planned dividing line 14 from a back surface 10b of the wafer 10 into individual device chips by cutting with a cutting blade 142.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for processing a wafer in which a plurality of devices are divided by dividing lines and a wafer formed on the surface is divided into individual device chips.

A wafer formed by dividing a plurality of devices such as ICs and LSIs by a planned dividing and enclosing line on the surface is divided into individual device chips by a dicing device and a laser processing device, and is used for electric devices such as mobile phones and personal computers. It

Generally, a wafer is positioned in the opening of a frame having an opening for accommodating the wafer, and a dicing process is performed with a protective tape provided on the back surface of the wafer together with the frame, and the wafer is divided into individual device chips. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 10-242083

By the way, as a method of cutting a wafer formed on the surface by dividing a device such as CCD, which dislikes contamination such as cutting chips, by a dividing line, a protective tape is provided on the front side of the wafer to divide from the back side of the wafer. It is conceivable to cut the area corresponding to the line with a cutting blade. According to such a processing method, it is possible to prevent contamination from adhering to the device, but irregularities corresponding to the device are formed on the protective tape provided on the front surface side of the wafer. Then, when performing cutting from the back surface of the wafer while holding the front surface of the wafer, a load originating from the unevenness is applied, and an unexpected crack is generated on the front surface side of the wafer, which deteriorates the quality of the device. The problem occurs.

In addition, the back surface of the wafer may be coated with a metal film in order to improve the electrical characteristics of the wafer and the heat dissipation. In that case, if cutting is performed from the front surface side of the wafer along the planned dividing line, there is a problem that cracks are generated from the interface between the metal film and the wafer and the quality of the device is deteriorated. Even as a method of cutting a wafer coated with a metal film on such a back surface, it is possible to dispose a protective tape on the front surface side of the wafer and cut the area corresponding to the planned dividing line from the back surface of the wafer with a cutting blade. It is valid. According to such a processing method, it is possible to prevent the occurrence of cracks from the interface between the metal film and the wafer, however, as described above, the protective tape provided on the front surface side of the wafer is suitable for the device. When unevenness is formed and a cutting process is performed from the back surface of the wafer, an unexpected crack occurs on the front surface side of the wafer, which causes a problem that the quality of the device deteriorates.

The present invention has been made in view of the above facts, and its main technical problem is a method of processing a wafer that can be effectively divided into individual devices even when cutting from the back surface of the wafer without degrading the quality of the device. To provide.

In order to solve the main technical problems described above, according to the present invention, there is provided a wafer processing method for dividing a wafer formed on a surface by dividing a plurality of devices by dividing lines into individual device chips, the surface of the wafer being divided. Protective tape disposing process to dispose protective tape on the surface, protective tape flattening process to cut the upper surface of the protective tape with a cutting tool to flatten it, and cut the area corresponding to the planned dividing line from the back surface of the wafer with a cutting blade. Then, there is provided a wafer processing method including at least a dividing step of dividing into individual device chips.

The wafer processing method of the present invention further comprises a metal film removal step of removing the metal film in a ring shape along the outer periphery of the wafer, in which the back surface of the wafer is covered with a metal film, and an imaging means for transmitting the wafer. And a planned dividing line detecting step of detecting a planned dividing line formed on the front surface of the wafer from the back surface of the wafer from which the metal film has been removed in a ring shape.

As the protective tape, it is possible to select either an adhesive tape having an adhesive layer or a thermocompression-bonding tape which exerts an adhesive force by heating. Further, in the protective tape disposing step, the wafer is accommodated in the opening of the frame having an opening for accommodating the wafer, and the protective tape is disposed on the surface of the wafer together with the frame so that the wafer is supported by the frame. May be.

The wafer processing method of the present invention comprises a protective tape disposing step of disposing a protective tape on the front surface of the wafer, a protective tape flattening step of flattening the upper surface of the protective tape by cutting with a cutting tool, and from the back surface of the wafer. By dividing the area corresponding to the planned dividing line with a cutting blade to divide into individual device chips, and by at least consisting of the unevenness of the device formed on the surface of the wafer to the wafer side The problem of cracking and degrading device quality is eliminated. Further, even when a metal film is formed on the back surface side of the wafer, an infrared imaging means that transmits the wafer by performing a metal film removing step of annularly removing the metal film along the outer periphery of the wafer Thus, the dividing lines formed on the front surface of the wafer can be detected from the back surface side of the wafer, and the dividing step can be efficiently performed.

(A), (b) It is a perspective view showing an embodiment of a protective tape arranging process concerning this embodiment, and is a sectional view taken on the line AA shown in (c) and (b). It is a whole perspective view of a cutting tool. It is a side view which shows the state which mounts the wafer currently hold|maintained at the frame on the chuck table of the cutting tool shown in FIG. (A) It is a top view which shows the embodiment of a protective tape flattening process, (b) It is BB sectional drawing of (a). It is a perspective view which shows the embodiment of a metal film removal process. It is the whole perspective view showing a cutting device. FIG. 7A is a perspective view showing an embodiment of a planned division line detection step carried out by the cutting device shown in FIG. 6, and FIG. 7B is a plan view showing a state of a planned division line detected by the planned division line detection step. It is a perspective view showing an embodiment of a division process.

Hereinafter, an embodiment of a wafer processing method configured according to the present invention will be described in detail with reference to the accompanying drawings.

The processing method of the wafer in the present embodiment includes a protective tape disposing step of disposing a protective tape on the front surface of the wafer, a protective tape flattening step of flattening the upper surface of the protective tape by cutting with a cutting tool, and a back surface of the wafer. And a dividing step of cutting an area corresponding to the planned dividing line with a cutting blade to divide into individual device chips. Each step will be described below in order.

(Providing protective tape)
In carrying out the protective tape arranging step, first, as shown in FIG. 1A, a wafer 10 to be a workpiece in the present embodiment, a frame 16 having an opening 16a capable of accommodating the wafer 10, and a wafer A protective tape 20 is prepared which is attached to and integrated with the frame 10 and the frame 16. The wafer 10 is formed by dividing a plurality of devices 12 on a silicon substrate by dividing lines 14 and forming them on the surface 10a. The protective tape 20 is, for example, a PET (polyethylene terephthalate) adhesive surface coated with a sizing agent.

After the wafer 10, the frame 16 and the protective tape 20 described above are prepared, as shown in FIG. 1A, the front surface 10a of the wafer 10 is placed on the center of the upper surface Ta of the tape sticking table T with the surface 10a facing upward. Then, the frame 16 is placed with the wafer 10 accommodated in the opening 16 a of the frame 16. When the wafer 10 and the frame 16 are placed on the tape application table T, the adhesive tape-attached surface of the protective tape 20 faces downward, and the outer peripheral area of the protective tape 20 is placed on the frame 16 in the center. The area is located on the surface 10a of the wafer 10.

When the wafer 10 and the frame 16 are placed on the tape sticking table T and the protective tape 20 is further positioned, as shown in FIG. 1B, the roller 30 indicated by the chain double-dashed line is moved in the direction indicated by the arrow. The wafer 10 and the frame 16 are pressed against the entire upper surfaces of the wafer 10 and the frame 16 while being rotated, and the wafer 10 and the frame 16 are integrated with the protective tape 20 (see the lower stage of FIG. 1B). With the above, the protective tape disposing process is completed.

A cross section taken along the line AA of FIG. 1B is shown in FIG. As can be seen from FIG. 1C, minute irregularities are formed on the surface 10 a of the wafer 10 by the plurality of devices 12 and the planned dividing line 14. When the protective tape 20 is attached and adhered to the surface 10a, irregularities are formed on the protective tape 20 along the minute irregularities, and more specifically, concave portions along the planned dividing line 14 are formed. 22 is formed. The depth of the recess 22 is, for example, 15 to 20 μm. In this state, when the front surface 10a side of the wafer 10 to which the protective tape 20 is attached is faced down and cutting is performed from the back surface of the wafer 10 along the planned dividing line 14, the above-described recesses 22 cause Unexpected cracks occur in the wafer 10 and deteriorate the quality of the individually divided device chips. In order to solve this problem, the following protective tape flattening step is performed.

(Protection tape flattening process)
With reference to FIG. 2, a bite cutting device 40 suitable for a protective tape flattening step of flattening the upper surface of the protective tape 20 by cutting with a cutting tool will be described.

As shown in FIG. 2, the cutting tool 40 according to the present embodiment includes a device base 41, a cutting tool 50 arranged on the device base 41, and a chuck table 70. The bite cutting device 40 further includes a chuck table moving means (not shown) for moving the chuck table 70 in the X-axis direction and a bite cutting means moving means 80 for moving the bite cutting means 50 back and forth in the Z-axis direction. Prepare The cutting tool 40 can relatively move the cutting tool 50 and the chuck table 70 to cut and flatten the upper surface of the workpiece held by the chuck table 70.

The chuck table 70 includes a circular breathable holding member 72 that forms a holding surface of the chuck table 70, and a frame portion 74 that surrounds the holding member 72 and supports the holding member 72. In the frame portion 74, a plurality of communication holes 76 communicating with a space (not shown) on the lower surface side of the holding member 72 are formed at equal intervals in the circumferential direction. A suction unit (not shown) is connected to the space on the lower surface side of the holding member 72 to apply a negative pressure to the holding member 72 of the chuck table 70 and the frame portion 74.

When there is an instruction to start the machining operation, the chuck table 70 is moved in the direction indicated by the arrow X1 from the machining standby area in which the chuck table 70 is positioned in FIG. 2, and the machining area below the cutting tool 50. Enter. Then, when there is an instruction to end the machining operation, the machining area below the cutting tool 50 is retracted to the machining standby area.

As shown in FIG. 2, the device base 41 includes a main body 42 and a wall 43. The main body 42 is formed into a substantially rectangular parallelepiped shape, and the wall 43 is provided upright from the rear end of the main body 42. A pair of guide rails 46 is arranged on the front surface side of the wall portion 43 along the Z-axis direction. The guide rail 46 guides the movement of the cutting tool 50 in the Z-axis direction.

The cutting tool 50 includes a spindle 51, a cutting wheel 52, a spindle housing 53, and a cutting drive unit 56. The spindle 51 is rotatably supported by the spindle housing 53. The spindle housing 53 is supported by a support portion 54 formed on a moving base 57 of the cutting tool 50. The spindle 51 is connected to the output shaft of the bite driving unit 56, positioned in a direction orthogonal to the holding surface of the holding member 72 of the chuck table 70, and rotationally driven. The bite wheel 52 is attached to the tip of the spindle 51 and holds a bite 62 for cutting a workpiece. The cutting edge forming the tip of the cutting tool 62 is formed of diamond. The protruding amount of the cutting blade of the cutting tool 62 from the cutting tool wheel 52 to the lower side is adjusted by a screw 64 that fixes and opens the cutting tool 62.

The cutting tool moving means 80 includes a pulse motor 82 and a male screw rod 84, and moves the moving base 57. The male screw rod 84 is disposed on the front surface of the wall portion 43, the upper end portion and the lower end portion thereof are rotatably supported by bearing members 86 and 87 attached to the wall portion 43, and extend in the Z-axis direction. The male screw rod 84 is transmission-coupled to the output shaft of the pulse motor 82 and is rotationally driven. The movable base 57 is formed with a guided groove slidably engaged with the pair of guide rails 46 and an engaging member (not shown) arranged on the back surface side. When the mating member engages with the male screw rod 84, it is moved in the Z-axis direction along the pair of guide rails 46. Based on such a configuration, the bite cutting means moving means 80 moves the bite cutting means 50 in the Z-axis direction along the pair of guide rails 46.

The cutting tool 40 includes a control means (not shown). The control means controls each of the above-described components constituting the cutting tool 40, and causes the cutting tool 40 to perform a cutting operation on the workpiece held on the chuck table 70. The control means is composed of a computer (not shown).

The bite cutting device 40 used in the present embodiment has a configuration roughly as described above, and the protective tape flattening step is carried out as follows.

As shown in FIG. 2, the wafer 10 and the frame 16 integrated through the protective tape 20 through the protective tape arranging step described above are chuck table 70 with the protective tape 20 side facing upward and the wafer 10 side facing downward. Place on top. The frame portion 74 of the chuck table 70 is formed according to the size of the frame 16, and the frame 16 is positioned on the frame portion 74. As shown in FIG. 3, the central region 72a of the holding member 72 of the chuck table 70 is located at a high position as viewed from the side so as to rise upward in a region corresponding to the size of the wafer 10. After the wafer 10 and the frame 16 are placed on the chuck table 70, a suction means (not shown) is operated to apply a negative pressure to the upper surface of the holding member 72 and the communication hole 76 of the frame portion 74, As shown in FIG. 3, the wafer 10 and the frame 16 are suction-held. By holding in this way, the upper surface 20a of the protective tape 20 to which the surface 10a of the wafer 10 is adhered is located at a position higher than the outer periphery adhered to the frame 16, and cutting by a cutting tool described later is effective. It becomes a state to be done.

As described above, when the wafer 10 is suction-held on the chuck table 70 with the protective tape 20 side facing upward, the bite cutting means 50 is operated to move the bite wheel 52 in the direction indicated by R1 in the drawing. Rotate at a predetermined speed, for example, 6000 rpm. When the cutting tool 62 is rotated along with the rotation of the cutting tool wheel 52, the cutting tool moving means 80 is operated to lower the cutting tool means 50. At this time, in the present embodiment, as shown in FIG. 1C, since the recess 22 is formed in a region 15 to 20 μm from the upper surface 20 a of the protective tape 20, the protective tape 20 holding the wafer 10 is The tip of the cutting tool 62 is lowered so as to flatten the upper surface 20a in the central region by cutting 20 to 25 μm.

As described above, when the bite 62 is rotated and lowered to a predetermined height position as the bite wheel 52 rotates, the chuck table 70 is moved to move the wafer as shown in FIG. The protective tape 20 holding 10 is moved from the processing standby area on the left side in the direction indicated by the arrow X1 toward the processing area below the bite wheel 52. By moving the protective tape 20 to the processing area at the center of FIG. 4A, the cutting blade at the tip of the cutting tool 62 cuts and removes the upper surface 20a of the protective tape 20 by 20 to 25 μm. The feed rate of the table 70 is set so that the cutting marks are connected in the direction indicated by X1. More specifically, for example, when the cutting width of the cutting tool 62 is 50 μm, the rotation speed of the cutting tool wheel 52 is 6000 rpm as described above, and therefore, 100 rotations per second give 50 μm×100 times=5000 μm. Therefore, the feeding speed of the chuck table 70 is set to 4000 to 4500 μm/sec. In this way, by moving the protective tape 20 to the right side, the upper surface 20a of the protective tape 20 is removed, and the protective tape 20' having the flat surface 20'a in the region corresponding to the wafer 10 is formed. (See also FIG. 4B showing the BB cross section in FIG. 4A). In FIG. 4A, the device 12 is actually visible through the protective tape 20 in the state before the protective tape flattening step (on the left side), but for convenience of explanation. Omitted. Further, in the state on the right side after the protective tape flattening step, the cutting marks formed on the flat surface 20'a are exaggerated compared to the actual state, and the actual state of the cutting marks is visually recognized. Not in line. In particular, the cutting marks formed on the flat surface 20'a are actually only slightly visible. With the above, the protective tape flattening step of the present embodiment is completed.

After the flattening step of the protective tape described above, then, a dividing step of dividing the region corresponding to the planned dividing line 14 from the back surface 10b of the wafer 10 with a cutting blade to divide into individual device chips is performed. Here, depending on the application of the device in which the wafer 10 is used, the back surface 10b side of the wafer 10 is coated with a metal film and a part of the metal film is made to function as an electrode of the device 12, or the back surface 10b side of the wafer 10 is covered. It may improve heat dissipation. Such a metal film is, for example, a film made of one or more metals of titanium, nickel, and gold and having a thickness of several μm to 10 μm. In that case, when carrying out the dividing step of cutting the wafer 10 from the back surface 10b side, the device 12 formed on the front surface 10a side and the planned dividing line 14 can be separated from the back surface 10b side even by using an infrared imaging means or the like. Can not be detected from. In order to deal with this, in the present embodiment, as described below, a metal film removing step of annularly removing the metal film along the outer periphery of the back surface 10b of the wafer 10 is performed.

(Metal film removal process)
When carrying out the metal film removing step, the wafer 10 held on the frame 16 by the protective tape 20′ subjected to the protective tape flattening step is held by the holding table (not shown in the figure) of the outer peripheral grinding device 90 shown in FIG. ), and the wafer 10 is placed and held with the back surface 10b side facing upward. As shown in FIG. 5, a metal film 11 is formed on the entire back surface 10b of the wafer 10. The thickness of the metal film 11 is about several μm to 10 μm. The holding table is provided with rotating means (not shown) for rotating the wafer 10 in the direction indicated by the arrow R3. When the wafer 10 is placed on the holding table, the holding table rotates. The center of the wafer 10 is positioned at the center. The outer peripheral grinding device 90 includes a grinding unit 91 that grinds an outer peripheral region 10c (shown by a chain line) of the back surface 10b of the wafer 10 held on the holding table. The grinding means 91 includes a rotary spindle 92, a disk-shaped grinding wheel 93 fixed to the tip of the rotary spindle 92, and a spindle housing 94 that rotatably supports the rotary spindle 92. The rotary spindle 92 is rotationally driven by a spindle motor arranged on the rear end side (not shown) of the spindle housing 94. Further, the grinding means 91 is orthogonal to the X-axis direction indicated by the arrow X in the drawing and constitutes a horizontal plane with the X-axis direction by the moving means (not shown), and the Y-axis direction indicated by the arrow Y and the X-axis indicated by the arrow Z. Direction and the Z-axis direction orthogonal to the Y-axis direction. The grinding wheel 93 is a grinding wheel in which diamond abrasive grains are fixed by nickel plating, has a diameter of 60 mm and a thickness of 2 mm, and the outer peripheral end of the grinding wheel 93 is formed of a substantially flat surface.

As described above, when the wafer 10 is suction-held on the holding table and the grinding means 91 is prepared, the wafer is picked up by using an appropriate imaging means (not shown) provided in the outer circumference grinding device 90. Alignment for detecting the outer peripheral end position of 10 is performed. After the alignment is performed, the grinding wheel 93 is rotated in the direction indicated by the arrow R2, positioned on the outer peripheral region 10c of the back surface 10b of the wafer 10 which is the processing position, and the wafer 10 is rotated in the direction indicated by R3. When the wafer 10 is rotated, the grinding wheel 93 is lowered at a speed of 1 μm/sec to a position where it reaches 10 μm from the surface of the back surface 10b, and the outer peripheral region 10c of the back surface 10b is cut with a width of 2 mm to remove the metal film. 11 is completely removed to expose the outer peripheral region 10c' of the silicon substrate covered with the metal film 11. With the above, the metal film removing step is completed.

In the present embodiment, the metal film removing step is performed after the protective tape flattening step, but it is not necessarily required to be performed after the protective tape flattening step. For example, it is performed before the protective tape flattening step. It may be performed at any timing as long as it is before performing the dividing step described below.

When the above-described metal film removing step is completed, the cassette is placed in an appropriate cassette, and the cassette is divided into individual device chips by cutting a region corresponding to the planned dividing line 14 from the back surface 10b of the wafer 10 with a cutting blade. It is conveyed to the cutting device 100 (see FIG. 6) that carries out the dividing step. A cutting device 100 suitable for the dividing step will be described with reference to FIG. 6.

The cutting device 100 shown in FIG. 6 cuts the wafer 10 and divides it into individual device chips, and includes a device housing 102 and a holder mounted on the device housing 102 so as to be movable in the X-axis direction indicated by arrow X. Means 104 and machining feed means (not shown) for feeding the holding means 104 in the X-axis direction are provided. The holding means 104 is provided with a breathable holding surface 106 for suction-holding via the protective tape 20'. A plurality of clamps 108 for fixing the frame 16 for holding the wafer 10 are arranged on the peripheral edge of the holding means 104 at intervals in the circumferential direction. As shown in the figure, an image pickup unit 110 for picking up an image of the wafer 10 held by the holding unit 104 and detecting a region to be cut is provided above the moving path of the holding unit 104. .. The above-mentioned processing feeding means may be composed of, for example, a ball screw connected to the holding means 104 and extending in the X-axis direction, and a motor for rotating the ball screw (not shown).

In the device housing 102 of the cutting device 100, a cassette 120 containing a plurality of wafers 10 that have been subjected to the above-described protective tape flattening process and metal film removal process and held on the frame 16 is mounted on a cassette mounting table 122 that can be raised and lowered. Placed. The cassette mounting table 122 is moved up and down by an elevating means (not shown). In addition, the cutting device 100 pulls out the wafer 10 before cutting from the cassette 120, carries it out to the temporary placement table 130, and carries in the carried-out wafer 10 positioned on the temporary placement table 130 into the cassette 120. A first transport means 134 for transporting the uncut wafer 10 unloaded from the cassette 120 to the temporary placement table 130 to the holding means 104; a cleaning means 136 for cleaning the cut wafer 10; and a cut wafer. The second transporting means 138 for transporting 10 from the holding means 104 to the cleaning means 136 is provided.

The cutting device 100 is provided with a cutting means 140 rotatably equipped with a cutting blade 142 for cutting the wafer 10 held by the holding means 104. The cutting means 140 is configured to be movable in the Y-axis direction parallel to the holding surface 106 of the holding means 104 and orthogonal to the X-axis direction and movable (elevating) in the Z-axis direction perpendicular to the holding surface 106. It is provided with indexing feed means (not shown) for indexing and feeding the means 140 in the Y-axis direction, and cutting feed means (not shown) for feeding the cutting means 140 by cutting in the Z-axis direction. The indexing feed means and the notch feed means include a ball screw extending in the Y-axis direction connected to the cutting means 140 and a ball screw extending in the Z-axis direction connected to the cutting means 140, similarly to the above-described machining feed means. , A motor for rotating each ball screw (not shown).

The above-mentioned image pickup means 110 includes an infrared ray radiating means for radiating infrared rays that pass through silicon (Si) forming the wafer 10, an optical system for trapping the infrared rays radiated by the infrared ray irradiating means, and an infrared ray captured by the optical system. And an infrared imaging device (infrared CCD) that outputs a corresponding electric signal. In addition to the image capturing unit 110, an illuminating unit that emits visible light and a normal image sensor (CCD) that captures an image with visible light may be further provided.

The cutting device 100 has a configuration as described above, and performs the dividing step as described below. When performing the dividing step, first, the dividing line detection step is performed.

(Planned division line detection process)
The wafer 10 accommodated in the cassette 120 is carried to the holding means 104 by the action of the carry-in/out means 132 and the first carrying means 134, and is placed on the holding surface 106 with the back surface 10b side of the wafer 10 facing upward. Then, it is suction-held and fixed by the clamp 108. Here, as shown in FIG. 7A, in a state where the wafer 10 is suction-held by the holding means 104, the holding means 104 is moved to position the outer peripheral area 10c′ of the wafer 10 immediately below the imaging means 110. The imaging means 110 is provided with the infrared irradiation means and the infrared imaging means as described above, and is configured to be able to detect the device 12 and the planned dividing line 14 on the front surface 10a side through the silicon substrate from the rear surface 10b side. Has been done. However, in the wafer 10 of the present embodiment, as described above, the back surface 10b side is covered with the metal film 11, and in the region covered with the metal film 11, even if the image pickup means 110 is used, the back surface 10b side The surface 10a side cannot be detected. On the other hand, in the present embodiment, since the metal film 11 is removed in the area of the outer peripheral area 10c′ by performing the above-described outer peripheral film removing step, the device 12 on the front surface 10a side is detected. It is possible to do.

If the outer peripheral area 10c′ of the wafer 10 is positioned immediately below the image pickup means 110, the wafer 10 is appropriately rotated in the direction indicated by the arrow R4 to detect the device 12 on the front surface 10a side along the outer peripheral area 10c′. The width (2 mm) of the region 10c' removed by the above-described metal film removing step is set so that the end portion of the device 12 can be slightly detected when the front surface 10a side is detected by the imaging unit 110 from the back surface 10b side. It suffices if it is set, and as shown in FIG. 7B, the position of the planned division line 14 is detected from the interval between the devices 12 formed adjacent to each other.

When the planned dividing line 14 is detected as described above, the position of the planned dividing line 14 which is the processing start position of the wafer 10 and the cutting blade 142 of the cutting means 140 are aligned. You can With the above, the dividing line detection step is completed.

(Division process)
After the alignment is performed as described above, the wafer 10 is moved to position the predetermined processing start position of the wafer 10 just below the cutting blade 142 of the cutting means 140. As shown in FIG. 8, the cutting means 140 is rotatably mounted on the spindle housing 141 and the spindle housing 141 which is moved and adjusted in the direction indicated by the arrow Y which is the indexing direction and the direction indicated by the arrow Z which is the cutting direction. A spindle 143 which is supported and has the cutting blade 142 mounted on the tip thereof, a blade cover 144 which covers the cutting blade 142, and a cutting which is disposed on the blade cover 144 and supplies cutting water to a cutting position by the cutting blade 142. And a water supply means 145. A motor (not shown) is connected to the rear end of the spindle housing 141 so that the spindle 143 can be rotated at an arbitrary rotation speed.

When the cutting blade 142 is positioned on the processing start position of the wafer 10, the cutting blade 142 is rotated in the direction indicated by the arrow R4 in the drawing to start the operation. The rotation speed at this time is 30,000 rpm, for example. When the rotation of the cutting blade 142 is started, the cutting blade 142 is lowered. At this time, in the present embodiment, the cutting depth of the cutting blade 142 is set so that the cutting depth is such that the wafer 10 is completely cut and the protective tape 20 is slightly cut.

When the cutting blade 142 is lowered to the above-mentioned cutting depth, the holding means 104 holding the wafer 10 is cut and fed in the direction indicated by an arrow X2 in the drawing at a speed of, for example, 50 mm/sec. The cutting process is performed while supplying the cutting water, and the region corresponding to the planned dividing line 14 is cut from the back surface 10b by the cutting blade 142 to form the cutting groove 200.

When the cutting groove 200 is formed on the silicon substrate 10 from the processing start position to the end position in a predetermined direction, the cutting means 140 is moved up in the Z-axis direction, and adjacent planned dividing lines in the direction indicated by the arrow Y. The cutting means 140 is index-fed by an index feed amount having an interval of 14 to form a cutting groove 200 similar to the above at a position adjacent to the previously-formed cutting groove 200 in the Y-axis direction. By repeating such processing, the cutting groove 200 is formed in the predetermined direction in the entire area of the wafer 10.

When the cutting groove 200 is formed in the area corresponding to the planned dividing line 14 in the predetermined direction in the entire area of the wafer 10 from the back surface 10b of the wafer 10, the holding means 104 for holding the wafer 10 is rotated by 90 degrees, and the above-described operation is performed. The direction in which the cutting groove 200 is formed is positioned along the Y-axis direction, that is, the direction (orthogonal direction) orthogonal to the predetermined direction is positioned along the X-axis direction. In this way, when the orthogonal direction is positioned in the X-axis direction, the holding means 104 and the cutting means 50 are moved to form a cutting groove 200 similar to the cutting groove 200 described above. As described above, the region corresponding to the planned dividing line 14 from the back surface 10b of the wafer 10 is cut by the cutting blade 142 to form the cutting groove 200, and the device 12 is divided into individual device chips. With the above, the dividing step is completed.

When the above-described dividing step is completed, the cut wafer 10 is transferred from the holding means 104 to the cleaning means 136 by the second transfer means 138 to transfer the wafer 10 to the cleaning means 136 for cleaning, and the wafer after cleaning is cleaned. 10 is accommodated in the cassette 120 using the first transfer means 134 and the carry-in/out means 132, and a series of processing is completed.

According to the present embodiment, when performing the dividing step of cutting the region corresponding to the planned dividing line 14 from the back surface of the wafer 10 with the cutting blade 142 to divide into individual device chips, the front surface 10a side of the wafer 10 is previously prepared. Since the upper surface of the protective tape 20 attached to the substrate is cut by a cutting tool to be flattened, the problem that the wafer 10 side is cracked due to the unevenness of the device 12 and the device quality is deteriorated is solved. To do. Further, even when the metal film 11 is formed on the back surface 10b side of the wafer 10, the metal film 11 is annularly removed to the extent that the device 12 on the front surface 10a side can be detected along the outer peripheral region 10c of the wafer 10. By performing the metal film removing step described above, the planned dividing line 14 formed on the front surface 10a of the wafer 10 can be detected from the back surface 10b side of the wafer 10 by the infrared imaging means that transmits the wafer 10, and the dividing step can be performed. It can be implemented efficiently.

According to the present invention, various modifications are provided without being limited to the above embodiments. In the above-described embodiment, the protective tape 20 is PET, which has a sticking surface coated with a sizing agent to give adhesive strength, but the present invention is not limited to this. For example, as the protective tape 20, a thermocompression bonding tape that exerts an adhesive force by heating can be used. Such a thermocompression bonding tape can be selected from a polyolefin sheet or a polyester sheet. When a polyolefin-based sheet is selected, for example, it is selected from a polyethylene sheet, a polypropylene sheet, and a polystyrene sheet. When the polyester sheet is selected, it is selected from a polyethylene terephthalate sheet or a polyethylene naphthalate sheet. When the above-mentioned thermocompression bonding tape is used as the protection tape 20, the roller 30 shown in FIG. 1B is used as a heating roller having a heating means such as an electric heater built therein, and the thermocompression bonding sheet exerts an adhesive force. The wafer 10 and the frame 16 can be bonded and integrated by pressing while heating to a temperature near the melting temperature.

In the above-described embodiment, the wafer 10 having the metal film 11 formed on the back surface 10b side is used as an object to be processed, but the present invention is not limited to this. It is also effective when the film 11 is not formed. In that case, it is not necessary to perform the metal film removing step described above, and the positions of the device 12 and the planned dividing line 14 can be detected from any of the back surface 10b of the wafer 10 in the dividing planned line detecting step. Therefore, the alignment can be easily performed.

Further, in the above-described embodiment, the protective tape disposing step is performed so that the wafer 10 is integrated with the annular frame 16 via the protective tape 20, and the wafer 10 is protected while being held by the frame 16. Although an example in which the tape flattening step is performed is shown, the present invention is not limited to this, and a protective tape formed in substantially the same shape as the wafer 10 is attached to the back surface 10b of the wafer 10 to perform the dividing step. It is also effective when you do.

10: Wafer 12: Device 14: Planned dividing line 16: Frame 16a: Opening 20: Protective tape 40: Bit cutting device 41: Device base 42: Main body 50: Bit cutting means 52: Bit wheel 62: Bit 70: Chuck Table 72: Holding member 74: Frame part 76: Communication hole 80: Tool cutting means moving means 90: Outer peripheral grinding device 91: Grinding means 93: Grinding wheel 100: Cutting device 104: Holding means 106: Holding surface 110: Imaging means 140 : Cutting means 142: Cutting blade T: Tape application table Ta: Top surface

Claims (4)

A method for processing a wafer, in which a plurality of devices are divided by dividing lines to divide the wafer formed on the surface into individual device chips,
A protective tape disposing step of disposing a protective tape on the surface of the wafer;
A protective tape flattening process of flattening by cutting the upper surface of the protective tape with a cutting tool,
A dividing step of cutting the area corresponding to the planned dividing line from the back surface of the wafer with a cutting blade to divide into individual device chips,
A method of processing a wafer that is composed of at least. A metal film is coated on the back surface of the wafer, and a metal film removing step of annularly removing the metal film along the outer periphery of the wafer,
A planned division line detecting step of detecting a planned division line formed on the front surface of the wafer from the back surface of the wafer in which the metal film has been removed in an annular shape by the imaging means that transmits the wafer,
The method for processing a wafer according to claim 1, further comprising: The method for processing a wafer according to claim 1, wherein the protective tape is either an adhesive tape having an adhesive layer or a thermocompression-bonding tape that exhibits an adhesive force by heating. 2. The wafer is supported by the frame by accommodating the wafer in the opening of a frame having an opening for accommodating the wafer and disposing the protective tape on the surface of the wafer together with the frame in the step of disposing the protective tape. The method for processing a wafer according to any one of 3 above.