JP7477325B2 - Processing method - Google Patents

Description

The present invention relates to a method for processing a workpiece having multiple bumps on its surface.

The upper ends of the bumps, which are the protruding power of the device, of the workpiece are cut by a cutting tool to make the bumps uniform in height (see, for example, Patent Document 1).

JP 2011-18858 A

However, when the upper end of the bump is cut using a cutting tool as in Patent Document 1, the bump is stretched by the cutting, causing burrs, and cutting chips fall between the bumps.

The processing method shown in Patent Document 1 has been proposed as a processing method to reduce burrs, but there is a risk of burrs being generated during cutting on the return path. In addition, it is difficult to prevent cutting debris from falling between the bumps using the processing method shown in Patent Document 1. Because the spaces between the bumps are very narrow, if cutting debris gets in, it is very difficult to completely remove it even with subsequent cleaning. Furthermore, if burrs remain on the bumps or cutting debris gets in between the bumps, it may cause problems such as short circuits when the devices separated from the workpiece are mounted.

The object of the present invention is to provide a processing method that can reduce defects during mounting of devices that have been singulated from a workpiece.

In order to solve the above-mentioned problems and achieve the object, the processing method of the present invention is a method for processing a workpiece having a plurality of bumps on its surface, and is characterized by comprising a sheet adhering step of covering the upper surface of the workpiece with a resin sheet having a thickness greater than the height of the bumps, reducing the pressure between the resin sheet and the workpiece, and inserting the resin sheet between adjacent bumps to adhere the resin sheet to the surface of the workpiece, a holding step after the sheet adhering step is performed, holding the workpiece on a holding table to expose the resin sheet, a cutting step after the holding step is performed, cutting the resin sheet covering the surface of the workpiece held on the holding table together with the bumps with a cutting bit to align the heights of the bumps, a surface protective tape adhering step of adhering a surface protective tape to the upper surface of the resin sheet and the upper surfaces of the bumps that have been subjected to the cutting step, and a peeling step of peeling the resin sheet together with the surface protective tape from the surface of the workpiece .

In the above processing method, the resin sheet may have an adhesive layer formed in the area corresponding to the workpiece.

In the above processing method, the workpiece has a central region in which multiple bumps are formed and a peripheral excess region surrounding the central region, and the resin sheet may have no adhesive layer formed in the region corresponding to the central region of the workpiece, and may have an adhesive layer formed in the region corresponding to the peripheral excess region of the workpiece.

The present invention has the effect of suppressing defects during mounting of devices separated from a workpiece.

FIG. 1 is a perspective view showing a workpiece to be processed by the processing method according to the first embodiment. FIG. 2 is an enlarged plan view of a portion II in FIG. FIG. 3 is a cross-sectional view of a main portion of the workpiece shown in FIG. FIG. 4 is a flowchart showing the flow of the processing method according to the first embodiment. FIG. 5 is a perspective view showing a resin sheet and a workpiece that are brought into close contact with each other in the sheet contacting step of the processing method shown in FIG. FIG. 6 is a cross-sectional view showing a state in which a resin sheet is placed on the surface of a workpiece on a support table of a contacting device in the sheet contacting step of the processing method shown in FIG. FIG. 7 is a cross-sectional view showing a state where both the first and second chambers of the chamber of the contact device shown in FIG. 6 are depressurized. FIG. 8 is a cross-sectional view showing a state in which a resin sheet is adhered to the surface of a workpiece with the first chamber of the adhesion device shown in FIG. 7 open to the atmosphere. FIG. 9 is a cross-sectional view of a main portion of the resin sheet and the workpiece shown in FIG. FIG. 10 is a perspective view showing an example of the configuration of a tool cutting device that performs the holding step and the cutting step of the processing method according to the first embodiment. FIG. 11 is a side view showing a holding step of the processing method shown in FIG. FIG. 12 is a side view showing the cutting step of the processing method shown in FIG. FIG. 13 is a cross-sectional view of a main portion of the workpiece after the cutting step of the processing method shown in FIG. FIG. 14 is a cross-sectional view showing a surface protection tape attaching step in the processing method shown in FIG. FIG. 15 is a side view showing the back grinding step of the processing method shown in FIG. FIG. 16 is a cross-sectional view showing a peeling step of the processing method shown in FIG. FIG. 17 is a cross-sectional view of a resin sheet that is brought into close contact with the surface of a workpiece in the sheet contacting step of a processing method according to a modified example of the first 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 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 a workpiece to be processed by the processing method according to the first embodiment. Fig. 2 is a plan view showing an enlarged view of part II in Fig. 1. Fig. 3 is a cross-sectional view of a main part of the workpiece shown in Fig. 2. Fig. 4 is a flow chart showing the flow of the processing method according to the first embodiment.

The processing method according to the first embodiment is a method for processing a workpiece 1 shown in Fig. 1. The workpiece 1 to be processed by the processing method according to the first embodiment is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, with silicon ( _Si ), sapphire ( _Al2O3 ), gallium arsenide (GaAs), silicon carbide (SiC) or the like as a substrate 2. As shown in Fig. 1, the workpiece 1 has a central region 3 and a peripheral excess region 4 on a surface 5, which is an upper surface.

In the central region 3, a plurality of division lines 6 are set on the surface 5, which intersect with each other, and devices 7 are formed in each region partitioned by the division lines 6. Each device 7 has a plurality of bumps 8 shown in FIG. 2 that are connected to the electrodes of the device 7 and protrude from the surface 5. In the central region 3, since the device 7 has a bump 8 protruding from the surface 5, a plurality of bumps 8 are formed on the surface 5, forming unevenness on the surface 5. In addition, since the device 7 has a bump 8 protruding from the surface 5, the workpiece 1 has a plurality of bumps 8 on the surface 5. The bumps 8 are made of a conductive metal. As shown in FIG. 3, the bumps 8 of the workpiece 1 before the processing method according to the first embodiment are often different in height 10 from the surface 5 of the upper surface 9 for each bump 8. The height 10 of the upper surface 9 of the bump 8 from the surface 5 will be referred to as the height of the bump 8 below. The upper surface 9 is the location furthest from the surface 5 of the bump 8 in the thickness direction of the workpiece 1.

The device 7 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). The peripheral excess area 4 is an area that completely surrounds the central area 3 and in which the device 7 is not formed.

In embodiment 1, the workpiece 1 is thinned to a finishing thickness by grinding the back surface 11 side behind the front surface 5, and the heights 10 (shown in FIG. 8) of the multiple bumps 8 from the front surface 5 are made uniform, and then the workpiece is divided into individual devices 7 along the planned division lines 6.

The processing method according to the first embodiment is a method for processing one workpiece 1, and includes a sheet adhesion step 1001, a holding step 1002, a cutting step 1003, a surface protection tape application step 1004, a back surface grinding step 1005, and a peeling step 1006, as shown in FIG. 4.

(Sheet adhesion step)
Fig. 5 is a perspective view showing a resin sheet and a workpiece that are adhered to each other in the sheet adhering step of the processing method shown in Fig. 4. Fig. 6 is a cross-sectional view showing a state in which a resin sheet is placed on the surface of a workpiece on a support table of the adhering device in the sheet adhering step of the processing method shown in Fig. 4. Fig. 7 is a cross-sectional view showing a state in which both the first and second chambers of the chamber of the adhering device shown in Fig. 6 are depressurized. Fig. 8 is a cross-sectional view showing a state in which the first chamber of the chamber of the adhering device shown in Fig. 7 is opened to the atmosphere and a resin sheet is adhered to the surface of the workpiece. Fig. 9 is a cross-sectional view of the main parts of the resin sheet and the workpiece shown in Fig. 8.

The sheet adhesion step 1001 is a step in which the surface 5 of the workpiece 1 is covered with a resin sheet 20 shown in FIG. 5 having a thickness 21 greater than the height 10 of the bumps 8, the pressure between the resin sheet 20 and the workpiece 1 is reduced, and the resin sheet 20 is inserted between adjacent bumps 8 to adhere the resin sheet 20 to the surface 5 of the workpiece 1.

In the first embodiment, the resin sheet 20 that is in close contact with the surface 5 of the workpiece 1 is composed only of a base sheet 22 that is made of a synthetic resin that is thermocompression bondable, non- adhesive, and non-breathable. In the first embodiment, the base sheet 22 that constitutes the resin sheet 20 is composed of, for example, a polyolefin-based synthetic resin. The resin sheet 20 is formed to have a planar shape larger than the planar shape of the workpiece 1, and in the first embodiment, is formed in a rectangular shape. The thickness 21 of the resin sheet 20 is thicker than the height 10 of the highest bump 8. The resin sheet 20 used in the processing method of the first embodiment is composed only of a base sheet 22 that is thermocompression bondable, non- adhesive, and non-breathable, and therefore does not have an adhesive glue layer formed in the area corresponding to the workpiece 1. The area corresponding to the workpiece 1 is the area of the surface of the resin sheet 20 that is superimposed on the surface 5 of the workpiece 1.

In the first embodiment, in the sheet adhesion step 1001, as shown in FIG. 6, the first case body 33 and the second case body 34 constituting the chamber 32 having the space 31 inside the adhesion device 30 are separated from each other, and the space 31 is connected to the outside of the chamber 32. Then, the workpiece 1 is inserted into the chamber 32 through the case bodies 33 and 34, and the back surface 11 of the workpiece 1 is placed on the support table 35 in the second case body 34. In the sheet adhesion step 1001, the resin sheet 20 is inserted between the case bodies 33 and 34, and the resin sheet 20 is placed on the front surface 5 of the workpiece 1 on the support table 35, and the outer edge of the resin sheet 20 is placed on the outer edge of the second case body 34 over the entire circumference.

When the resin sheet 20 is inserted between the case bodies 33, 34 as shown in FIG. 6, the on-off valves 38, 39 are opened to open the cylindrical release pipes 40, 41 connected to the case bodies 33, 34 and the on-off valves 38, 39 to the atmosphere, and the on-off valves 42, 43 are closed to shut off the cylindrical communication pipes 46, 47 connected to the case bodies 33, 34 and the suction sources 44, 45.

The release pipe 40 and the communication pipe 46 are connected to the first case body 33, the release pipe 40 is connected to the on-off valve 38, and the communication pipe 46 is connected to the suction source 44 via the on-off valve 42. The release pipe 41 and the communication pipe 47 are connected to the second case body 34, the release pipe 41 is connected to the on-off valve 39, and the communication pipe 47 is connected to the suction source 45 via the on-off valve 43.

In the sheet contact step 1001, the case bodies 33 and 34 are brought close to each other to seal the space 31, and the outer edge of the resin sheet 20 is sandwiched between the outer edges of the case bodies 33 and 34 as shown in FIG. 7. Then, since the resin sheet 20 is composed only of the base sheet 22 made of non-breathable synthetic resin, the resin sheet 20 divides the space 31 in the chamber 32 into the first chamber 36 in the first case body 33 and the second chamber 37 in the second case body 34. In the sheet contact step 1001, the opening and closing valves 38 and 39 are closed to isolate the release pipes 40 and 41 from the outside of the chamber 32. In the sheet contact step 1001, the opening and closing valves 42 and 43 are opened to communicate the space 31 in the chamber 32 with the suction sources 44 and 45 via the communication pipes 46 and 47. The release pipe 40 and the communication pipe 46 are connected to the first chamber 36, and the release pipe 41 and the communication pipe 47 are connected to the second chamber 37. Each communication pipe 46, 47 is provided with a barometer 48 that detects the air pressure inside the communication pipes 46, 47, i.e., inside each chamber 36, 37.

In the sheet contact step 1001, both the first chamber 36 and the second chamber 37 of the space 31 in the chamber 32 are depressurized by the suction sources 44, 45, and the planar heater 49 in the support table 35 is driven to heat the workpiece 1 and the resin sheet 20 on the support table 35. In the sheet contact step 1001, when the air pressure in each chamber 36, 37 is reduced to a predetermined air pressure based on the detection result of the barometer 48, as shown in FIG. 8, the on-off valve 42 is closed while the second chamber 37 is kept depressurized, the on-off valve 38 is opened, the depressurization in the first chamber 36 is stopped, and the first chamber 36 is opened to the atmosphere.

Then, the workpiece 1 and the resin sheet 20 are heated by the planar heater 49, and the second chamber 37 is decompressed and the first chamber 36 is opened to the atmosphere, so that the air pressure in the first chamber 36 becomes higher than the air pressure in the second chamber 37, and the resin sheet 20 is pressed toward the surface 5 of the workpiece 1 due to the air pressure difference between the first chamber 36 and the second chamber 37. Then, as shown in FIG. 9, the resin sheet 20 penetrates between the adjacent bumps 8 and adheres closely to the surface 5 of the workpiece 1 and the surface of the bumps 8 without any gaps. As shown in FIG. 9, when the resin sheet 20 adheres closely to the surface 5 of the workpiece 1 and the surface of the bumps 8 without any gaps, the processing method proceeds to the holding step 1002 by carrying out the workpiece 1 with the resin sheet 20 adhered closely to the surface 5 of the bumps 8 outside the chamber 32. Note that the upper surface 23 of the resin sheet 20 adhered closely to the surface 5 of the workpiece 1 and the surface of the bumps 8 without any gaps is uneven because the heights 10 of the bumps 8 are often different, as shown in FIG. 9.

(Cutting tool)
Next, a description will be given of a bit cutting device 60 (shown in FIG. 10) which performs the holding step 1002 and the cutting step 1003. FIG. 10 is a perspective view showing an example of the configuration of a bit cutting device which performs the holding step and the cutting step of the processing method according to the first embodiment.

The cutting tool 60 according to the first embodiment is a tool that performs flat turning and cutting on the surface 5 of the workpiece 1 and the upper layer of the resin sheet 20 that is in contact with the surface of the bumps 8, and also performs flat turning and cutting on the upper ends of the bumps 8 to make the heights 10 of the bumps 8 uniform (to make the heights 10 of the bumps 8 equal).

As shown in FIG. 10, the bit cutting device 60 includes a device base 61, a holding table 70, a cutting unit 80, a processing feed unit 90, a cutting feed unit 91, and a control unit 92.

The holding table 70 holds the back surface 11 of the workpiece 1 with a holding surface 71. The holding table 70 is made of a metal material such as stainless steel, and includes a disk-shaped base 72 and an outer peripheral annular holding portion 73 formed on the outer periphery of the base 72, and a suction recess 74 is formed inside the outer peripheral annular holding portion 73. The holding table 70 also includes a plurality of cylindrical support pins (not shown) provided in the suction recess 74. The plurality of support pins provided in the suction recess 74 are arranged at equal intervals. The outer peripheral annular holding portion 73 and the plurality of support pins of the holding table 70 configured in this manner are made of stainless steel as a base material, and a plating layer made of nickel is formed on the upper surface of the outer peripheral annular holding portion 73 and the upper surface of the support pin. The upper surface of the outer peripheral annular holding portion 73 and the upper surface of the support pin form a holding surface 71 parallel to the horizontal direction that holds the workpiece 1.

The suction recess 74 formed in the holding table 70 is connected to a suction source (not shown), and the workpiece 1 placed on the holding surface 71 is suction-held by the suction source. The holding table 70 is supported on a support base (not shown) that is rotatable about an axis parallel to the Z-axis direction. The Z-axis direction is parallel to the vertical direction and perpendicular to the holding surface 71. In the first embodiment, the holding table 70 is a so-called pin holding table in which the holding surface 71 is formed by the upper surfaces of the support pins.

The cutting unit 80 uses a cutting tool wheel 82, which includes a cutting tool 81 that is a cutting tool attached to the lower end of a spindle 83, to turn and cut the upper end of the resin sheet 20 and bumps 8 on the surface 5 side of the workpiece 1 held on the holding table 70. The cutting unit 80 is supported by a column 62 that stands on the device base 61 via a cutting feed unit 91, and is equipped with a motor 84 that rotates the spindle 83 around its axis. The axis of the spindle 83 of the cutting unit 80 is aligned along the Z-axis direction.

The processing feed unit 90 is installed on the device base 61 and moves the holding table 70 relative to the cutting unit 80 in the X-axis direction, which is the processing feed direction parallel to the holding surface 71. The processing feed unit 90 moves the support base that supports the holding table 70 in the X-axis direction, thereby moving the holding table 70 away from the cutting unit 80 between a loading/unloading position where the workpiece 1 is loaded/unloaded to/from the holding table 70 and a processing position below the cutting unit 80 where the workpiece 1 is turned and cut by the cutting unit 80.

The cutting feed unit 91 is fixed to a column 62 that stands on the device base 61, and moves the cutting unit 80 in the Z-axis direction, which is the cutting feed direction perpendicular to the holding surface 71. The cutting feed unit 91 lowers the cutting unit 80 to bring the cutting tool 81 closer to the workpiece 1 held on the holding table 70 at the processing position, and raises the cutting unit 80 to move the cutting tool 81 away from the workpiece 1 held on the holding table 70 at the processing position.

The machining feed unit 90 and the cutting feed unit 91 are equipped with a well-known ball screw that is rotatable about its axis, a well-known pulse motor that rotates the ball screw about its axis, and a well-known guide rail that supports the holding table or cutting unit so that it can move freely in the Y-axis or Z-axis direction.

The byte cutting device 60 has cassettes 63 and 64 mounted on a device base 61. The byte cutting device 60 also includes an alignment unit 65, a transport unit 93 that is a transport means for transporting the workpiece 1 between the cassettes 63 and 64 and the holding table 70, and a cleaning unit 66 that cleans the workpiece 1 after turning and cutting.

Cassettes 63 and 64 are containers that hold multiple workpieces 1 and are installed at the end of the device base 61 near the loading/unloading position. One cassette 63 holds the workpiece 1 before turning and cutting, and the other cassette 64 holds the workpiece 1 after turning and cutting. The alignment unit 65 is a table on which the workpiece 1 removed from the cassette 63 is temporarily placed and its center is aligned.

The transport unit 93 includes a carry-in/out unit 94, a carry-in unit 95, and a carry-out unit 96. The carry-in/out unit 94 is, for example, a robot pick equipped with a U-shaped hand, and the U-shaped hand is used to suction-hold and transport the workpiece 1. Specifically, the carry-in/out unit 94 carries the workpiece 1 before turning and cutting from the cassette 63 to the alignment unit 65, and carries the workpiece 1 after turning and cutting from the cleaning unit 66 to the cassette 64.

The carry-in unit 95 carries the workpiece 1 before turning and cutting, which has been aligned by the carry-in/out alignment unit 65, from the cassette 63 onto the holding table 70 located at the carry-in/out position. The carry-out unit 96 carries the workpiece 1 after turning and cutting, which is held on the holding table 70 located at the carry-in/out position, from the holding table 70 and carries it into the cleaning unit 66.

The control unit 92 controls each of the above-mentioned components constituting the bit cutting device 60. In other words, the control unit 92 causes the bit cutting device 60 to execute a machining operation on the workpiece 1. The control unit 92 is a computer that has an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or RAM (random access memory), and an input/output interface device, and is capable of executing computer programs.

The arithmetic processing device of the control unit 92 executes a computer program stored in the ROM on the RAM to generate a control signal for controlling the byte cutting device 60. The arithmetic processing device of the control unit 92 outputs the generated control signal to each component of the byte cutting device 60 via the input/output interface device. The control unit 92 is also connected to a display means (not shown) configured with a liquid crystal display device or the like that displays the status and images of the machining operation, and an input means used by the operator to register machining content information, etc. The input means is configured with at least one of a touch panel provided on the display means and a keyboard, etc.

In the above-mentioned byte cutting device 60, a cassette 63 containing the workpiece 1 before turning cutting by an operator or the like and a cassette 64 containing no workpiece 1 are placed on the device base 61, and the control unit 92 receives the processing content information input by the operator or the like. When the control unit 92 receives an instruction to start the processing operation input by the operator, the byte cutting device 60 starts the processing operation, drives the motor 84 to start rotating the spindle 83 and the byte wheel 82 around their axes, and performs the holding step 1002.

(holding step)
Fig. 11 is a side view showing the holding step of the processing method shown in Fig. 4. The holding step 1002 is a step of holding the workpiece 1 by the holding table 70 to expose the resin sheet 20 after the sheet adhesion step 1001 is performed.

In the first embodiment, in the holding step 1002, the control unit 92 of the byte cutting device 60 controls the carry-in/out unit 94 to take out one workpiece 1 from the cassette 63 and carry it out to the alignment unit 65. In the holding step 1002, the control unit 92 of the byte cutting device 60 controls the alignment unit 65 to align the center of the workpiece 1, and controls the carry-in unit 95 to carry the workpiece 1 aligned by the alignment unit 65 onto the holding table 70 located at the carry-in/out position. In the holding step 1002, the control unit 92 of the byte cutting device 60 operates the suction source to hold the back surface 11 of the workpiece 1 by suction on the holding surface 71 of the holding table 70, exposing the resin sheet 20 in contact with the front surface 5 upward, and proceeds to the cutting step 1003.

(Cutting step)
Fig. 12 is a side view showing the cutting step of the processing method shown in Fig. 4. Fig. 13 is a cross-sectional view of a main part of the workpiece after the cutting step of the processing method shown in Fig. 4. In the cutting step 1003, after the holding step 1002 is performed, the resin sheet 20 covering the surface 5 of the workpiece 1 held by the holding table 70 is cut together with the bumps 8 by the cutting tool 81 to make the heights 10 of the bumps 8 uniform.

In the first embodiment, in the cutting step 1003, the control unit 92 of the bit cutting device 60 controls the cutting feed unit 90 to position the tip of the bit tool 81 at a position where the distance from the holding surface 71 is a predetermined height of the height 10 of the bump 8, and as shown in FIG. 12, the processing feed unit 91 is controlled to rotate the holding table 70 that suction-holds the workpiece 1 around its axis while transporting it to the processing position. The predetermined height is equal to or less than the height 10 of all bumps 8 before the turning cutting process. In the cutting step 1003, the bit cutting device 60 rotates the holding table 70 around its axis while cutting the bit tool 81 into the upper end of the resin sheet 20 and bumps 8 that are in close contact with the surface 5 of the workpiece 1 at the processing position, and performs turning cutting on the upper ends of the resin sheet 20 and all bumps 8. In the cutting step 1003, the cutting tool 60 flattens the upper surface 23 of the resin sheet 20 that is in contact with the surface 5 of the workpiece 1 and the upper surfaces 9 of all the bumps 8, as shown in FIG. 13, and aligns the heights 10 of the multiple bumps 8 to a predetermined height.

In the cutting step 1003, the control unit 92 of the byte cutting device 60 controls the processing feed unit 91 to transport the holding table 70, which holds the workpiece 1 subjected to the turning cutting processing, to the carry-in/out position, stops the rotation of the holding table 70 around its axis, and stops the suction holding of the holding table 70 at the carry-in/out position. In the cutting step 1003, the control unit 92 of the byte cutting device 60 controls the carry-out unit 96 to transport the workpiece 1 to the cleaning unit 66, and after cleaning it in the cleaning unit 66, controls the carry-in/out unit 94 to store the workpiece 1 in the cassette 64, and proceeds to the surface protection tape application step 1004. The byte cutting device 60 performs the holding step 1002 and the cutting step 1003 on the workpieces 1 in the cassette 63 in sequence, and when the holding step 1002 and the cutting step 1003 are performed on all the workpieces 1 in the cassette 63, the processing operation is completed.

In the cutting step 1003, when the cutting tool 81 cuts into the upper end of the bump 8, it tries to stretch a part of the bump 8 along the surface 5 of the workpiece 1. However, in the first embodiment, the resin sheet 20 is in close contact with the surface 5 of the bump 8, so that the resin sheet 20 supports the part of the bump 8 that is about to be stretched along the surface 5 of the workpiece 1, and the resin sheet 20 prevents the part of the bump 8 from being stretched along the surface 5 of the workpiece 1. In addition, after the cutting step 1003, the resin sheet 20 has an opening 24 through which the bump 8 penetrates and exposes the bump 8 on the upper surface 23.

(Surface protection tape application step)
Fig. 14 is a cross-sectional view showing the surface protection tape application step of the processing method shown in Fig. 4. The surface protection tape application step 1004 is a step of applying a surface protection tape 50 to the surface 5 side of the workpiece 1 that has been subjected to the cutting step 1003, i.e., the flattened upper surface 23 of the resin sheet 20 and the upper surfaces 9 of the bumps 8.

In the first embodiment, the surface protection tape 50 is formed in a disk shape having the same diameter as the workpiece 1, and includes a base layer 51 made of a flexible, non-adhesive synthetic resin, and a glue layer 52 made of a flexible, adhesive synthetic resin laminated on the base layer 51. In the first embodiment, in the surface protection tape application step 1004, as shown in FIG. 14, a known mounter or the like applies the glue layer 52 of the surface protection tape 50 to the surface 5 side of the workpiece 1, i.e., the top surface 23 of the planarized resin sheet 20 and the top surfaces 9 of the bumps 8, and the process proceeds to the back grinding step 1005.

(Back grinding step)
Fig. 15 is a side view showing the back grinding step of the processing method shown in Fig. 4. The back grinding step 1005 is a step of grinding the back surface 11 side of the workpiece 1 after the surface protection tape attachment step 1004 is performed, to thin the workpiece 1 to a predetermined finishing thickness.

In the back grinding step 1005, as shown in FIG. 15, the grinding device 100 sucks and holds the front surface 5 side of the workpiece 1 to the chuck table 101 via the surface protection tape 50, and while rotating the chuck table 101 about its axis, rotates the grinding wheel 103 of the grinding unit 102 about its axis to contact the back surface 11 of the workpiece 1 and grind the back surface 11. In the back grinding step 1005, the grinding device 100 grinds and thins the workpiece 1 to the finishing thickness, and then the process proceeds to the peeling step 1006.

In the first embodiment, the upper surface 23 of the resin sheet 20 and the upper surface 9 of the bump 8 are flattened in the cutting step 1003. For this reason, in the first embodiment, in the back surface grinding step 1005, the front surface 5 side of the workpiece 1 flattened in the cutting step 1003 is held by suction on the chuck table 101 and the back surface 11 is ground, so that the roughness accuracy of the back surface 11 of the workpiece 1 after grinding can be improved.

(Peeling step)
16 is a cross-sectional view showing a peeling step of the processing method shown in FIG. 4. The peeling step 1006 is a step of peeling the surface protection tape 50 from the surface 5 side of the workpiece 1 after the back grinding step 1005 is performed. In the first embodiment, the surface protection tape 50 is peeled off from the surface 5 side of the workpiece 1 in the peeling step 1006. Then, the adhesive layer 52 is attached to the resin sheet 20, and the opening 24 is formed in the resin sheet 20, but the resin sheet 20 is integrated except for the opening 24, so that the resin sheet 20 is peeled off from the surface 5 side of the workpiece 1 together with the surface protection tape 50 as shown in FIG. 16. In the first embodiment, when the surface protection tape 50 is peeled off from the surface 5 side of the workpiece 1 together with the resin sheet 20 in the peeling step 1006, the processing method is completed.

As described above, in the processing method according to the first embodiment, in the sheet adhesion step 1001, the surface 5 of the workpiece 1 is covered with the resin sheet 20, the resin sheet 20 is adhered to the surface 5 of the workpiece 1 and the surface of the bumps 8, and in the cutting step 1003, the resin sheet 20 on the surface 5 side of the workpiece 1 and the upper end of the bumps 8 are rotary cut. For this reason, in the processing method, since the resin sheet 20 is adhered to the surface 5 of the workpiece 1 and the surface of the bumps 8 in the cutting step 1003, cutting chips generated by rotary cutting the upper end of the bumps 8 can be prevented from falling between the bumps.

In addition, in this processing method, the resin sheet 20 supports a portion of the bump 8 that is about to be stretched along the surface 5 of the workpiece 1, and the resin sheet 20 prevents the portion of the bump 8 from being stretched along the surface 5 of the workpiece 1, thereby preventing burrs from being formed on the upper surface 9 of the bump 8.

In addition, in the processing method, in the surface protection tape application step 1004, the surface protection tape 50 is applied to the upper surface 23 of the resin sheet 20 and the upper surface 9 of the bump 8, so that any burrs that may have occurred on the upper surface 9 of the bump 8 are sandwiched between the surface protection tape 50 and the resin sheet 20. As a result, in the processing method, in the peeling step 1006, the surface protection tape 50 applied to the upper surface 23 of the resin sheet 20 is peeled off from the surface 5 of the workpiece 1 together with the resin sheet 20, so that any burrs that may have occurred on the upper surface 9 of the bump 8 can be removed from the workpiece 1 together with the surface protection tape 50 and the resin sheet 20.

Therefore, the processing method can suppress the generation of burrs on the bumps 8 and can suppress the intrusion of cutting debris between the bumps 8, thereby achieving the effect of suppressing defects during mounting of the device 7 separated from the workpiece 1.

[Modifications]
A processing method according to a modified example of the first embodiment of the present invention will be described with reference to the drawings. Fig. 17 is a cross-sectional view of a resin sheet that is adhered to the surface of a workpiece in the sheet adhering step of the processing method according to the modified example of the first embodiment. In the modified example, the same parts as those in the first embodiment are described with the same reference numerals.

The processing method according to the modified example is the same as that of the first embodiment, except that the configuration of the resin sheet 20-1 adhered to the surface 5 of the workpiece 1 in the sheet adhesion step 1001 is different from that of the first embodiment. The resin sheet 20-1 adhered to the surface 5 of the workpiece 1 in the sheet adhesion step 1001 of the processing method according to the modified example includes a base sheet 25 made of a synthetic resin having thermocompression bonding properties, non- adhesive properties, and non-breathable properties, and a glue layer 26 laminated in an area corresponding to the peripheral excess area 4 of the workpiece 1 on the surface of the base sheet 25, as shown in FIG. 17. In the modified example, the base sheet 25 has a thickness and size equivalent to those of the base sheet 22 of the resin sheet 20 of the first embodiment. The glue layer 26 is made of a synthetic resin having adhesive properties. Thus, in the resin sheet 20 used in the processing method according to the modified example, the glue layer 26 is not formed in an area corresponding to the central area 3 of the workpiece 1 on the surface of the base sheet 25, and the glue layer 26 is formed in an area corresponding to the peripheral excess area 4 of the workpiece 1.

The area on the surface of the base sheet 25 that corresponds to the central region 3 of the workpiece 1 refers to the area that overlaps with the central region 3 of the workpiece 1 when the resin sheet 20-1 covers the surface 5 of the workpiece 1, and the area that corresponds to the peripheral excess region 4 of the workpiece 1 refers to the area that overlaps with the peripheral excess region 4 of the workpiece 1 when the resin sheet 20-1 covers the surface 5 of the workpiece 1.

In the processing method according to the modified example, in the sheet adhesion step 1001, the resin sheet 20-1 is adhered to the surface 5 of the workpiece 1 and the surfaces of the bumps 8, and in the cutting step 1003, the upper ends of the resin sheet 20 and the bumps 8 are turned and cut. As in the first embodiment, this prevents burrs from being generated on the bumps 8 and prevents cutting debris from getting between the bumps 8, thereby preventing problems when mounting the devices 7 separated from the workpiece 1.

The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. For example, in the present invention, the surface protection tape application step 1004, the back grinding step 1005, and the peeling step 1006 are performed in order to thin the workpiece 1 to the finishing thickness, and then the sheet adhesion step 1001, the holding step 1002, and the cutting step 1003 are performed in order to make the height 10 of the bumps 8 uniform. In this case, in the surface protection tape application step 1004, the surface protection tape 50 is directly applied to the surface 5 of the workpiece 1, and after the cutting step 1003, the resin sheet 20 is peeled off from the workpiece 1.

1 Workpiece 3 Central region 4 Peripheral excess region 5 Surface (upper surface)
8 Bump 10 Height 20, 20-1 Resin sheet 21 Thickness 26 Glue layer 70 Holding table 81 Bit tool (cutting bit)
1001 Sheet adhesion step 1002 Holding step 1003 Cutting step

Claims (3)

A method for processing a workpiece having a plurality of bumps on a surface thereof, comprising the steps of:
a sheet adhesion step of covering the upper surface of the workpiece with a resin sheet having a thickness greater than the height of the bumps, reducing the pressure between the resin sheet and the workpiece, and inserting the resin sheet between adjacent bumps to adhere the resin sheet to the surface of the workpiece;
a holding step of holding the workpiece on a holding table to expose the resin sheet after the sheet contact step is performed;
a cutting step of cutting the resin sheet covering the surface of the workpiece held by the holding table together with the bumps by a cutting tool after the holding step is performed to make the height of the bumps uniform;
a surface protection tape application step of applying a surface protection tape to the upper surface of the resin sheet that has been subjected to the cutting step and to the upper surfaces of the bumps;
a peeling step of peeling the resin sheet together with the surface protection tape from the surface of the workpiece;
The processing method includes: The processing method according to claim 1, wherein the resin sheet does not have a glue layer formed in the area corresponding to the workpiece. The workpiece has a central region in which a plurality of bumps are formed, and a peripheral excess region surrounding the central region,
The processing method described in claim 1, wherein the resin sheet does not have an adhesive layer formed in an area corresponding to the central area of the workpiece, and an adhesive layer is formed in an area corresponding to the peripheral excess area of the workpiece.

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