JP2020123666A - Processing method of workpiece - Google Patents

Abstract

To provide a processing method of a workpiece capable of being corresponded to a semiconductor wafer of which a shape of a device region is different, and having a high general purpose.SOLUTION: A processing method is for a workpiece, comprises: a device region where a device comprising an electrode bump in a plurality of regions segmented by a plurality of crossed-division scheduled lines is formed, respectively; and an outer peripheral surplus region which is provided so as to surround the device region and where the electrode bump is not formed on a front face side. The processing method includes: a step of forming a step resolving member, in which a difference from a height position of an end part of a height direction of the electrode bump is within an acceptable range in the outer surplus region; a step of adhering a protective member, in which the protective member is adhered onto the front face side of the workpiece so as to cover the front face side of the workpiece; and a grinding step of holding the protective member side with a chuck table and grinding a back face side of the workpiece.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method of processing a work piece having an electrode bump.

Conventionally, a wire bonding type semiconductor device chip is known in which a metal wire is connected to an electrode pad formed on the front surface side of the semiconductor device chip. On the other hand, in recent years, a flip-chip type semiconductor device chip in which electrode bumps are formed on the front surface side of the semiconductor device chip has also been put into practical use.

When manufacturing a flip-chip type semiconductor device chip, usually, after forming electrode bumps, the back side of the semiconductor wafer is ground using a grinding machine. However, at the time of grinding, the height difference between the step on the front surface side of the semiconductor wafer (that is, the height of the device region in which the electrode bumps are formed and the outer peripheral region provided so as to surround the device region and in which the electrode bumps are not formed) ), there is a problem that the semiconductor wafer is likely to be cracked.

In order to eliminate this step, there is a case where a soft protective tape into which the electrode bump can be inserted is provided on the front surface side of the semiconductor wafer and then the back surface side is ground. However, the electrode bumps include, for example, a relatively low type having a height of about 50 μm and a so-called high bump type having a height of more than 300 μm. When a high bump type electrode bump is used, it is difficult to completely insert the electrode bump into the protective tape, and even if the protective tape is used, the step cannot be eliminated.

Therefore, in order to eliminate the step on the front surface side, a relatively thick protective tape having no adhesive layer in the area corresponding to the device area and having an adhesive layer (that is, a step eliminating member) in the area corresponding to the outer peripheral excess area has been developed. (See Patent Document 1).

JP, 2009-188010, A

However, since the shape of the outer peripheral surplus area is different depending on the shape of the device area, the protective tape having no adhesive layer in the area corresponding to the device area cannot be applied to the semiconductor wafer having the different shape of the device area.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly versatile method for processing a workpiece which can be applied to semiconductor wafers having different device regions.

According to one aspect of the present invention, a device region in which a device including an electrode bump is formed in each of a plurality of regions defined by a plurality of planned dividing lines that intersect with each other, and the device region is provided so as to surround the device region, and A method for processing a work piece, the outer peripheral area of which electrode bumps are not formed and a front surface side, wherein a difference from a height position of an end portion in the height direction of the electrode bump is within an allowable range. A step for eliminating a step of forming a canceling member in the outer peripheral excess area in accordance with the shape of the outer peripheral excessive area, and after the step for eliminating the step differentiating step, the workpiece is covered so as to cover the front surface side of the workpiece. Protective member attaching step of attaching a protective member to the surface side of the workpiece, and after the protective member attaching step, the protective member side is held by a chuck table, and the workpiece to be processed is located on the opposite side of the surface. A method of processing a work piece is provided, which comprises a grinding step of grinding the back side of the work piece.

Preferably, in the step eliminating member forming step, a liquid resin is applied to the outer peripheral excess area using a jet dispenser.

Further, preferably, in the step of eliminating the step, the curable liquid resin is applied to the outer peripheral surplus region, and then the curable liquid resin is cured to form the step eliminating member in the outer peripheral surplus region.

In the step eliminating member forming step of the method for processing a workpiece according to an aspect of the present invention, the step eliminating member having a difference from the height position of the end portion in the height direction of the electrode bump is within an allowable range is used as an outer peripheral surplus. It is formed in the outer peripheral surplus region according to the shape of the region. Therefore, an appropriate step eliminating member can be formed according to the outer peripheral surplus region of any shape.

It is a perspective view of a work piece. FIG. 2(A) is a partial cross-sectional side view showing the resin coating step, and FIG. 2(B) is a perspective view of the workpiece after the resin curing step. FIG. 3A is a diagram showing a case where the height position of the end portion in the height direction of the resin layer is higher than the height position of the end portion in the height direction of the electrode bump, and FIG. FIG. 6 is a diagram showing a case where the height position of the end portion of the resin layer in the height direction is lower than the height position of the end portion of the electrode bump in the height direction. FIG. 4(A) is a partial cross-sectional side view showing the protective member pressing step, and FIG. 4(B) is a sectional view of the workpiece or the like after the protective member cutting step. It is a partial cross-sectional side view which shows a grinding step. It is a flowchart which shows the processing method of a to-be-processed object.

An embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the workpiece 11. The workpiece 11 of this embodiment has a wafer which is mainly made of silicon (Si) and has a disk shape with a thickness of about 500 μm to 1000 μm.

The material, shape, structure and size of the semiconductor substrate are not limited. For example, the wafer may be formed of a semiconductor material other than silicon such as gallium arsenide (GaAs) or silicon carbide (SiC).

The workpiece 11 further includes a wiring layer (not shown) formed so as to be in contact with the wafer and having a thickness smaller than that of the wafer. In this embodiment, one surface of the wiring layer located on the side opposite to the surface in contact with the wafer is referred to as the surface 11a of the workpiece 11, and the other surface of the workpiece 11 located on the side opposite to the surface 11a is processed. It is referred to as the back surface 11b of the object 11.

The wiring layer has a plurality of laminated electrode layers (not shown), and the plurality of electrode layers are formed so as to be electrically connected to the active region located on the front surface 11a side of the wafer. The wiring layer further has a low dielectric constant insulating layer (so-called Low-k material layer) (not shown) that functions as an interlayer insulating layer, and the low dielectric constant insulating layer is arranged between the electrode layers. .. The wiring layer and the active region of the wafer form a device 17a such as an IC (Integrated Circuit) or an LSI (Large Scale Integration).

A device region 15a including a plurality of devices 17a is formed on the surface 11a side of the workpiece 11. The device region 15a is partitioned into a plurality of regions by a plurality of planned dividing lines (streets) 13 arranged so as to intersect with each other (for example, in a grid pattern), and is partitioned by the plurality of planned dividing lines 13. The device 17a is formed in each region.

On the surface 11a side of the device 17a, a plurality of electrode bumps 17b formed of a metal material such as solder and having a substantially spherical shape are provided. Each of the plurality of electrode bumps 17b is, for example, a so-called high bump type electrode bump having a height of about 300 μm.

Each of the plurality of electrode bumps 17b is in contact with the above-mentioned electrode layer located on the uppermost side and exposed from the low dielectric constant insulator layer, and electrically connected to the above-mentioned active region through the plurality of electrode layers. Connected. There is no limitation on the type, quantity, shape, structure, size, arrangement, etc. of the electrode bumps 17b.

An outer peripheral surplus region 15b, which is a substantially annular region surrounding the device region 15a, exists outside the outer edge of the device region 15a. Since the electrode bumps 17b are not formed in the outer peripheral surplus region 15b, the height difference (that is, the step difference) between the height of the device region 15a on the surface 11a side and the height of the outer peripheral surplus region 15b on the surface 11a side. ) Has been formed.

A notch 11c indicating the crystal orientation of the semiconductor substrate is provided in a part of the outer peripheral end of the outer peripheral surplus region 15b. Instead of the notch 11c, another mark such as an orientation flat may be provided.

Next, a method of processing the workpiece 11 will be described with reference to FIGS. 2 to 6. FIG. 2A is a partial cross-sectional side view showing the resin coating step (S10). Note that FIG. 6 is a flow chart showing the processing method of the workpiece 11.

In the resin applying step (S10), the liquid resin 22a is applied to the outer peripheral surplus region 15b of the workpiece 11 by using the resin layer forming device 18. The resin layer forming apparatus 18 includes a suction table 20 that sucks and holds the back surface 11b side of the workpiece 11. A plurality of suction holes (not shown) are provided on the suction table 20.

One end of each suction hole is connected to a suction source (not shown) such as an ejector, and the other end of each suction hole is exposed on the surface of the suction table 20. When the suction source is operated, a negative pressure is generated on the surface of the suction table 20, and this surface functions as a holding surface 20a that sucks and holds the workpiece 11.

A ball screw type X-axis moving mechanism (not shown) is provided below the suction table 20, and the suction table 20 is moved along the X-axis direction by the X-axis moving mechanism. A jet dispenser 24 capable of ejecting the liquid resin 22a is provided above the suction table 20.

The jet dispenser 24 is provided with a ball screw type Y-axis moving mechanism (not shown), and the jet dispenser 24 is moved along the Y-axis direction by the Y-axis moving mechanism. The jet dispenser 24 has a nozzle 24 a for ejecting the liquid resin 22 a, and the ejection port of the nozzle 24 a is arranged so as to face the suction table 20.

The jet dispenser 24 of this embodiment is a piezo jet dispenser that uses a piezo element to open and close a valve at high speed. The jet dispenser 24 may be a mechanical jet dispenser that discharges the liquid resin 22a by mechanically reciprocating the rod by utilizing the restoring force of a spring or the like.

In the present embodiment, a UV (that is, ultraviolet) curable liquid resin is used as the liquid resin 22a. However, the liquid resin 22a may be a photo-curable liquid resin that is cured by light in a wavelength band other than UV, a thermosetting liquid resin that is cured by heat, or a naturally curable liquid resin that is cured in a normal temperature environment. ..

In the resin coating step (S10), first, the workpiece 11 is placed on the suction table 20 so that the back surface 11b side of the workpiece 11 contacts the holding surface 20a. Then, the suction source is operated to suck and hold the back surface 11b side of the workpiece 11 by the holding surface 20a.

After that, the liquid resin 22a is discharged from the nozzle 24a to the surface 11a side of the workpiece 11 while moving the nozzle 24a and the suction table 20 relatively using the X-axis moving mechanism and the Y-axis moving mechanism.

For example, the liquid resin 22a is discharged along the edge of the outer peripheral surplus region 15b on the device region 15a side (that is, the inner side), and then the liquid resin 22a is discharged along the outer edge of the discharged region of the discharged liquid resin 22a. Discharge.

The liquid resin 22a has a predetermined viscosity, and the height of the discharged liquid resin 22a from the surface 11a can be adjusted by adjusting the discharge amount per unit time. For example, the discharge amount of the liquid resin 22a is adjusted such that the difference between the height position and the position of the end of the electrode bump 17b in the height direction (for example, the direction from the back surface 11b to the front surface 11a) is within the allowable range. To be done.

The liquid resin 22a is applied to the entire outer peripheral surplus region 15b, but in the present embodiment, the liquid resin 22a is also discharged to the notches 11c. As a result, the notch 11c is filled with the liquid resin 22a.

Thus, in the present embodiment, the liquid resin 22a is applied using the jet dispenser 24 so as to correspond to the shape of the outer peripheral surplus region 15b. Therefore, the application area of the liquid resin 22a can be adjusted to an arbitrary shape.

In the resin layer forming apparatus 18, it is sufficient that the nozzle 24a and the suction table 20 can move relative to each other, and only one of the suction table 20 and the nozzle 24a can move in the X-axis and Y-axis directions. The forming device 18 may be configured.

After the resin application step (S10), the resin curing step (S20) is performed to cure the liquid resin 22a. Since the liquid resin 22a of the present embodiment is a UV curable liquid resin, a UV irradiation device (not shown) is used in the resin curing step (S20). The UV irradiation device is arranged on the suction table 20, for example, so as to irradiate the holding surface 20 a of the suction table 20 with UV.

The UV irradiator has, for example, a plurality of UV light sources (not shown) arranged in series along the Y-axis direction, and irradiates UV onto a linear region substantially equivalent to the diameter of the workpiece 11. When the liquid resin 22a is a thermosetting liquid resin, a heating device (not shown) may be provided below the adsorption table 20 instead of the UV irradiation device.

In the resin curing step (S20), the suction table 20 is moved along the X-axis direction by using the X-axis moving mechanism while irradiating the suction table 20 with UV from the UV irradiation device. By irradiating UV from one end to the other end of the workpiece 11 along the X-axis direction, the entire outer peripheral surplus region 15b is irradiated with UV. The UV irradiation device may be provided with an X-axis moving mechanism to move the UV irradiation device in the X-axis direction.

The liquid resin 22a applied to the entire outer peripheral surplus region 15b by UV irradiation is cured to form a resin layer 22b. When the liquid resin 22a is a UV curable liquid resin, the liquid resin 22a can be cured only by irradiating the liquid resin 22a with UV for several seconds, and therefore, as compared with the case of curing a naturally curable liquid resin or the like, The working time required for the resin curing step (S20) can be shortened.

FIG. 2B is a perspective view of the workpiece 11 after the resin curing step (S20). In the present embodiment, the resin applying step (S10) and the resin curing step (S20) are collectively referred to as a step eliminating member forming step. The cured resin layer 22b is an example of a step eliminating member formed in the outer peripheral surplus region 15b.

In the step eliminating member forming step of the present embodiment, the resin layer 22b (that is, the step eliminating member) whose height difference from the electrode bumps 17b is within the allowable range is formed in the outer peripheral excess area according to the shape of the outer peripheral extra area 15b. 15b can be formed. Therefore, the step difference eliminating member can be formed according to the outer peripheral surplus region 15b having an arbitrary shape.

By the way, in a grinding step (S50) described later, the back surface 11b side is ground with the front surface 11a side of the workpiece 11 provided with the electrode bumps 17b and the resin layer 22b facing downward and the back surface 11b side facing upward. ..

However, when the height of the resin layer 22b is too higher than the height of the electrode bump 17b, the back surface 11b side is ground in a state where the device region 15a is recessed as compared with the outer peripheral surplus region 15b. Therefore, it is difficult to thin the workpiece 11 to a uniform thickness.

Further, when the height of the resin layer 22b is too lower than the height of the electrode bump 17b, the back surface 11b side is ground in a state in which the device region 15a projects as compared with the outer peripheral surplus region 15b, so that the workpiece 11 is made uniform. It is difficult to reduce the thickness.

In addition, if the back surface 11b side is ground in a state where the device region 15a is recessed or protruded as compared with the outer peripheral surplus region 15b, there is a problem that the workpiece 11 is likely to crack. Further, when the back surface 11b side is ground in such a state, there is a problem that the protection member 25 is easily peeled off when the sheet-shaped protection member 25 is attached to the front surface 11a side.

Therefore, the difference between the height position of the end portion in the height direction of the resin layer 22b and the height position of the end portion in the height direction of the electrode bump 17b is a predetermined value that does not cause a problem in the grinding step (S50). It is desirable to be within the allowable range of. For example, the allowable range of height difference is within 100 μm.

FIG. 3A is a diagram showing a case where the height position of the end portion of the resin layer 22b in the height direction is higher than the height position of the end portion of the electrode bump 17b in the height direction. In this case, the height difference L1 between the height position of the end of the resin layer 22b in the height direction and the height position of the end of the electrode bump 17b in the height direction is within an allowable range (for example, 100 μm or less is preferable. , 50 μm or less is more preferable, and 10 μm or less is further preferable).

FIG. 3B is a diagram showing a case where the height position of the end portion of the resin layer 22b in the height direction is lower than the height position of the end portion of the electrode bump 17b in the height direction. In this case, the height difference L2 between the height position of the end of the electrode bump 17b in the height direction and the height position of the end of the resin layer 22b in the height direction is within an allowable range (for example, 100 μm or less is preferable. , 50 μm or less is more preferable, and 10 μm or less is further preferable).

After the resin curing step (S20), the protective member 25 is attached to the surface 11a side of the workpiece 11 so as to cover the surface 11a side of the workpiece 11 (protective member pressing step (S30)). FIG. 4A is a partial cross-sectional side view showing the protective member pressing step (S30).

The protection member 25 is a resin-made rectangular film, and has, for example, a laminated structure of an adhesive layer having adhesive properties (not shown) and a base material layer having no adhesive property (not shown). The protective member 25 may not have the adhesive layer and may have only the base material layer.

In the protective member pressing step (S30), the protective member attaching device 26 is used. The protection member attaching device 26 includes a chuck table 28 that sucks and holds the back surface 11b side of the workpiece 11. A disc-shaped porous plate (not shown) made of a porous material is provided on the chuck table 28.

The porous plate has a suction passage (not shown) whose one end is connected to a suction source (not shown) such as an ejector. The other end of the suction path is exposed on the surface of the porous plate. When the suction source is operated, a negative pressure is generated on the surface of the porous plate, and this surface functions as a holding surface 28a that sucks and holds the workpiece 11.

A tape body (not shown) is provided above the chuck table 28. A roller-shaped pressing member 28b that presses the rectangular protection member 25 sent out from the tape body against the workpiece 11 is arranged near the tape body. The pressing member 28b is configured to be movable in a predetermined direction (for example, the X-axis direction) while rotating.

In the protective member pressing step (S30), first, the workpiece 11 is placed on the chuck table 28 so that the back surface 11b side of the workpiece 11 contacts the holding surface 28a. Then, the suction source is operated to suck and hold the back surface 11b side of the workpiece 11 by the holding surface 28a.

Then, the protection member 25 is disposed between the pressing member 28b and the surface 11a of the workpiece 11, and the pressing member 28b is moved while being rotated along the X-axis direction in a state where the pressing member 28b is pressed against the surface 11a. Let As a result, the rectangular protection member 25 is attached so as to cover the entire surface 11a of the workpiece 11.

In addition, when the protective member 25 does not have an adhesive layer, the protective member 25 is softened and deformed by heating the protective member 25, and the protective member 25 is moved to the surface 11a side of the workpiece 11 by the pressing member 28b. May be closely attached. Alternatively, by applying warm air or the like to the protective member 25, the protective member 25 may be softened and deformed by heating, and the protective member 25 may be brought into close contact with the surface 11a side of the workpiece 11 by wind pressure. The heating temperature may be appropriately adjusted according to the softening point of the material of the protective member 25.

After the protective member pressing step (S30), the protective member 25 is cut along the outer peripheral edge of the workpiece 11 (protective member cutting step (S40)). In the protective member cutting step (S40), the rectangular protective member 25 is formed into a circular shape along the outer periphery of the workpiece 11 by the cutter (not shown) arranged near the tape body and the pressing member 28b. Cut off.

FIG. 4B is a cross-sectional view of the workpiece 11 and the like after the protective member cutting step (S40). Through the protective member pressing step (S30) and the protective member cutting step (S40), the workpiece 11 having the protective member 25 attached to the front surface 11a side is formed. In this embodiment, the protective member pressing step (S30) and the protective member cutting step (S40) are collectively referred to as a protective member attaching step.

After the protective member cutting step (S40), the back surface 11b side of the workpiece 11 is ground (grinding step (S50)). FIG. 5 is a partial cross-sectional side view showing the grinding step (S50). In the polishing step (S50), the grinding device 30 is used.

The grinding device 30 includes a chuck table 32 for holding the workpiece 11 on the side of the protective member 25. The chuck table 32 is connected to a rotary drive source (not shown) such as a motor, and rotates about a straight line substantially parallel to the vertical direction as a rotation axis.

A disc-shaped porous plate (not shown) made of a porous material is provided on the upper surface side of the chuck table 32. The porous plate has a suction passage (not shown) whose one end is connected to a suction source (not shown) such as an ejector. The other end of the suction path is exposed on the surface of the porous plate. When the suction source is operated, a negative pressure is generated on the surface of the porous plate, and this surface functions as a holding surface 32a that sucks and holds the protection member 25 side of the workpiece 11.

A grinding unit 34 is provided above the chuck table 32. The grinding unit 34 includes a cylindrical spindle housing (not shown) supported by a lifting mechanism (not shown). A spindle 36 is rotatably accommodated in the spindle housing, and a disc-shaped wheel mount 38 is fixed to the lower end of the spindle 36 exposed from the spindle housing.

A grinding wheel 40 having substantially the same diameter as that of the wheel mount 38 is mounted on the lower surface side of the wheel mount 38. The grinding wheel 40 has an annular wheel base 40a made of a metal material such as stainless steel or aluminum. Further, on the lower surface side of the wheel base 40a, a plurality of rectangular parallelepiped grinding wheels (grinding stone chips) 40b are arranged in an annular shape along the outer periphery of the wheel base 40a.

The grinding wheel 40b is formed, for example, by mixing a bonding material such as metal, ceramics, or resin with abrasive grains such as diamond or cBN (cubic boron nitride). However, the types of the binder and the abrasive grains are not limited, and can be appropriately selected according to the specifications of the grinding wheel 40b.

A rotary drive source (not shown) such as a motor is connected to the upper end side of the spindle 36, and the grinding wheel 40 is rotated about the spindle 36 by the force generated by the rotary drive source. Further, the grinding unit 34 is provided with a nozzle (not shown) for supplying a grinding liquid such as pure water to the grinding wheel 40b and the workpiece 11.

In the grinding step (S50), first, the workpiece 11 is placed on the holding surface 32a of the chuck table 32 so that the back surface 11b side is exposed upward. In this state, the suction source is operated to apply a negative pressure to the holding surface 32a. As a result, the surface 11 a side of the workpiece 11 is sucked and held by the holding surface 32 a via the protective member 25.

Next, the chuck table 32 and the grinding wheel 40 are respectively rotated in predetermined directions, and the spindle 36 is lowered while supplying a grinding liquid such as pure water to the grinding wheel 40b and the back surface 11b side of the workpiece 11.

The descending speed of the spindle 36 is adjusted so that the grinding wheel 40b is pressed against the back surface 11b side of the workpiece 11 with an appropriate force. The workpiece 11 is ground on the back surface 11b side and thinned to a predetermined thickness.

In the method of processing the workpiece 11 according to the present embodiment, the resin layer 22b (that is, the step eliminating member) having a height difference with the electrode bump 17b within the allowable range is provided in the outer peripheral surplus region 15b. As compared with the case where there is no step eliminating member, the workpiece 11 can have a more uniform thickness. In addition, cracking of the workpiece 11 can be reduced and peeling of the protective member 25 can be suppressed as compared with the case where there is no step eliminating member.

In this embodiment, since the notch 11c is filled with the resin layer 22b, cracks of the workpiece 11 in the grinding step (S50) can be reduced as compared with the case where the notch 11c is not filled with the resin layer 22b.

In addition, the structures, methods, and the like according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the object of the invention. For example, a resin package substrate in which a plurality of device chips are sealed with a mold resin and a plurality of electrode bumps 17b are provided on one surface may be used as the workpiece 11.

Further, for example, a wafer level chip size package (WL-CSP: Wafer Level Chip Size Package) in which the surface 11a side is molded with a sealing resin and the electrode bumps 17b are arranged to project from the sealing resin is a workpiece 11 May be used as.

11 Workpiece 11a Front surface 11b Back surface 11c Notch 13 Planned division line 15a Device area 15b Perimeter surplus area 17a Device 17b Electrode bump 18 Resin layer forming device 20 Adsorption table 20a Holding surface 22a Liquid resin 22b Resin layer 24 Jet dispenser 24a Nozzle 25 Protection Member 26 Protective member pasting device 28 Chuck table 28a Holding surface 28b Pressing member 30 Grinding device 32 Chuck table 32a Holding surface 34 Grinding unit 36 Spindle 38 Wheel mount 40 Grinding wheel 40a Wheel base 40b Grinding wheel L1 Height difference L2 High Difference

Claims (3)

A device region in which devices each having an electrode bump are formed in a plurality of regions defined by a plurality of planned dividing lines intersecting with each other, and an outer peripheral surplus that is provided so as to surround the device region and is not formed with the electrode bump. A method of processing a workpiece, which comprises a region and a surface side,
A step eliminating member forming step of forming a step eliminating member whose difference from the height position of the end portion in the height direction of the electrode bump is within an allowable range in the outer peripheral extra region in accordance with the shape of the outer peripheral extra region. When,
A protective member attaching step of attaching a protective member to the surface side of the workpiece so as to cover the surface side of the workpiece after the step of eliminating the step difference;
After the step of attaching the protective member, the step of holding the protective member side by a chuck table and grinding the back surface side of the workpiece located on the side opposite to the front surface is provided. How to process a work piece. The method for processing a work piece according to claim 1, wherein in the step of eliminating the step difference, a liquid resin is applied to the outer peripheral surplus region by using a jet dispenser. The step difference eliminating member forming step comprises applying a curable liquid resin to the outer peripheral excess area and then curing the curable liquid resin to form the step difference eliminating member in the outer peripheral excessive area. The method for processing a workpiece according to 1 or 2.

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