JP7704569B2 - Grinding method and support base - Google Patents

Description

The present invention relates to a grinding method for grinding a workpiece attached to a support base via an adhesive, and a support base that is attached to the support base via an adhesive and supports the workpiece during grinding.

Various electronic devices such as mobile phones are equipped with device chips. Device chips are manufactured by processing a wafer (workpiece) on whose surface devices such as ICs (Integrated Circuits) are formed.

For example, the back side of the workpiece is ground with a grinding device to thin it, and then the thinned workpiece is cut with a cutting device along each of the planned division lines set in a grid pattern on the surface of the workpiece, thereby dividing the workpiece into multiple device chips.

When grinding a workpiece, the front side of the workpiece is held by suction on a chuck table, and the back side of the workpiece is ground with a grinding wheel. However, grinding a workpiece to make it thinner can cause problems such as warping and cracking.

To solve this problem, a grinding method is known in which the front side of the workpiece is attached to a support base and then the back side of the workpiece is ground (see, for example, Patent Document 1). To attach the front side of the workpiece to the support base, an adhesive is placed between the workpiece and the support base, and then the workpiece is pressed against the support base (see, for example, Patent Document 2).

However, when the workpiece is pressed against the support base, the adhesive overflows from the outer edge of the workpiece and adheres to the outer edge of the workpiece. Moreover, the adhesive may overflow from the front surface to the back surface of the outer side of the workpiece.

When grinding a workpiece, if the adhesive is ground along with the workpiece, the grinding wheel becomes clogged, making it difficult to grind the workpiece stably. In response to this, a technique is known in which an annular groove of a specified width is formed in the support base by cutting the top side of the support base, and excess adhesive is captured in this annular groove (see, for example, Patent Document 2).

JP 2004-207606 A JP 2013-235875 A

However, cutting the support base to form the annular groove requires a lot of time and effort. In addition, the amount of adhesive that spills outward radially from the workpiece during application may be uneven around the circumference of the workpiece.

If the amount of adhesive that protrudes outward in the radial direction of the workpiece is non-uniform, the adhesive that protrudes will not fit properly into the uniform annular groove of the specified width, and will be ground away together with the workpiece when it is ground, which may hinder stable grinding of the workpiece.

The present invention was made in consideration of these problems, and aims to prevent the grinding of adhesive that protrudes from the outer edge of the workpiece when grinding the workpiece while it is attached to a support base with adhesive.

According to one aspect of the present invention, there is provided a grinding method for grinding a workpiece which is a disk-shaped wafer , the grinding method comprising: a support base having a disk-shaped support portion with an upper surface having an area equal to or greater than an area defined by the outline of the workpiece; and an annular outer peripheral portion provided on the outer periphery of the support portion and having an upper surface located at a position lower than the upper surface of the support portion, the lower surface of the support portion and the lower surface of the annular outer peripheral portion being flush with each other and constituting the lower surface of the support base, the support base being used to press the workpiece against the support base with an adhesive provided between the support portion and the workpiece, and a grinding step in which, after the attaching step, the support base is held by a holding surface of a chuck table and the workpiece is ground with a grinding wheel, and in the attaching step, the adhesive pushed out beyond the outer periphery of the workpiece by the pressure can be moved to the annular outer peripheral portion of the support base.

According to another aspect of the present invention, there is provided a support base that is attached to a workpiece , which is a disk-shaped wafer , via an adhesive and supports the workpiece when it is being ground, the support base comprising: a disk-shaped support portion having an upper surface with an area equal to or greater than the area defined by the outline of the workpiece; and an annular outer peripheral portion provided on the outer periphery of the support portion and having an upper surface located at a position lower than the upper surface of the support portion, the lower surface of the support portion and the lower surface of the annular outer peripheral portion being flush with each other, and constituting the lower surface of the support base .

In the attachment step of the grinding method according to one aspect of the present invention, a support base having a support portion with an area equal to or greater than the area defined by the outline of the workpiece and an annular outer peripheral portion provided on the outer periphery of the support portion and having an upper surface located at a position lower than the upper surface of the support portion is used, and the workpiece is attached to the support base by pressing the workpiece against the support base with adhesive provided between the support portion and the workpiece.

The adhesive that is pushed outward beyond the outer peripheral end of the workpiece in the radial direction of the workpiece by the pressure applied in the attachment step can move to the annular outer periphery of the support base, so the adhesive does not move above a predetermined height position where the grinding wheel passes in the grinding step after the attachment step. Therefore, grinding of the adhesive can be suppressed in the grinding step.

FIG. 1A is a cross-sectional view of a support base, and FIG. 1B is a top view of the support base. FIG. 1 is a flow diagram of a grinding method. FIG. FIG. 4A is a cross-sectional view of the workpiece unit after the attaching step, and FIG. 4B is a top view of the workpiece unit after the attaching step. 1 is a partially sectional side view of a workpiece unit and the like held on a holding surface. FIG. FIG. 4 is a partial cross-sectional side view showing a grinding step. FIG. 7A is a cross-sectional view of the vicinity of the step before the grinding step, and FIG. 7B is a cross-sectional view of the vicinity of the step after the grinding step. FIG. 8A is a diagram showing an attaching step according to a comparative example, and FIG. 8B is a cross-sectional view of the workpiece unit after the attaching step according to the comparative example. FIG. 9(A) is a cross-sectional view of the vicinity of the outer peripheral end portion of the workpiece before the grinding step in the comparative example, and FIG. 9(B) is a cross-sectional view of the vicinity of the outer peripheral end portion of the workpiece after the grinding step in the comparative example. FIG. 10A is a cross-sectional view of a support base in the second embodiment, and FIG. 10B is a cross-sectional view of a workpiece unit in the second embodiment. FIG. 11A is a cross-sectional view of a support base in the third embodiment, and FIG. 11B is a cross-sectional view of a workpiece unit in the third embodiment. FIG. 12A is a cross-sectional view of a support base in the fourth embodiment, and FIG. 12B is a top view of the support base in the fourth embodiment.

An embodiment of the present invention will be described with reference to the attached drawings. First, a support base 2 according to a first embodiment will be described. FIG. 1(A) is a cross-sectional view of the support base 2, and FIG. 1(B) is a top view of the support base 2.

The support base 2 is made of a material with a thermal expansion coefficient close to that of the workpiece 11 (see FIG. 3). For example, if the workpiece 11 is a compound semiconductor such as gallium arsenide (GaAs) or silicon carbide (SiC) or a wafer made of sapphire, a support base 2 made of glass such as borosilicate glass, silicon (Si), ceramics, or the like is used.

The support base 2 has a disk-shaped support portion 4. The circular upper surface 4a of the support portion 4 has an area equal to or greater than the area of the circle (outline) defined by the diameter of the workpiece 11. For example, the upper surface 4a has a diameter that is greater than the diameter of the disk-shaped workpiece 11 by a predetermined value that is 200 μm or more and 500 μm or less.

The thickness of the support part 4 is adjusted appropriately depending on the material of the support base 2. For example, if the support base 2 is made of glass, ceramics, etc., the thickness of the support part 4 is set to a predetermined value of 0.5 mm or more and 1.5 mm or less.

A ring-shaped outer peripheral portion 6 having a thickness thinner than that of the support portion 4 is provided around the entire circumference of the support portion 4 and is generally concentric with the support portion 4. For example, the thickness of the ring-shaped outer peripheral portion 6 is thinner than the thickness of the support portion 4 by a predetermined value between 0.1 mm and 1.0 mm. In addition, the outer diameter of the ring-shaped outer peripheral portion 6 is larger than the diameter of the support portion 4 by, for example, 20 mm.

The lower surface of the support portion 4 and the lower surface of the annular outer peripheral portion 6 are substantially flush with each other, forming the lower surface 2b of the support base 2. The upper surface 6a of the annular outer peripheral portion 6 is located lower than the upper surface 4a of the support portion 4, and an annular step portion 2a is formed at the boundary between the annular outer peripheral portion 6 and the support portion 4.

Next, a grinding method for grinding the workpiece 11 using the support base 2 will be described. FIG. 2 is a flow diagram of the grinding method. When grinding the workpiece 11, as shown in FIG. 3, the front surface 11a of the workpiece 11 is attached to the upper surface 4a of the support part 4 via adhesive 13 (attaching step S10).

In this embodiment, the workpiece 11 is a disk-shaped wafer made of a compound semiconductor. However, the workpiece 11 may be a wafer or substrate made of a semiconductor material such as silicon, glass, ceramics, resin, metal, or the like, as long as it is disk-shaped and has approximately the same diameter as the upper surface 4a.

The workpiece 11 has chamfered corners formed around the entire circumference on the front surface 11a side and the rear surface 11b side, respectively, to form chamfered portions _11dA , _11dB (also called bevel portions).

The workpiece 11 has a predetermined diameter and a predetermined thickness corresponding to the diameter. The diameter of the workpiece 11 is determined by the outer peripheral end 11c of the workpiece 11. The outer peripheral end 11c is located approximately in the middle of the distance between the front surface 11a and the back surface 11b (i.e., the thickness of the workpiece 11).

The surface 11a of the workpiece 11 is divided into a number of rectangular regions by a number of mutually intersecting division lines (not shown). Devices (not shown) such as LEDs (Light Emitting Diodes) and ICs (Integrated Circuits) are formed in each region.

When attaching the workpiece 11 to the support 4, for example, an adhesive 13 is used. In this embodiment, the adhesive 13 is wax. However, a thermoplastic resin that softens when heated may also be used as the adhesive 13.

In the attachment step S10, an alignment device (not shown) is used to approximately align the center of the upper surface 4a of the support 4 with the center of the surface 11a of the workpiece 11. The alignment device has a predetermined sensor (not shown) for measuring the coordinates of the outer periphery of the upper surface 4a.

The specified sensor is, for example, a laser displacement sensor. If the coordinates of three different points on the outer periphery of the upper surface 4a can be obtained using the laser displacement sensor, the coordinates of the center of the upper surface 4a can be calculated. However, instead of using a laser displacement sensor, the coordinates of the center of the upper surface 4a may be calculated based on an image obtained by capturing an image of the upper surface 4a with a camera.

The alignment device has a control unit (not shown) for controlling the operation of certain sensors and other components and for performing certain calculations. The control unit is configured, for example, by a computer including a processor (processing device) such as a CPU (Central Processing Unit) and a memory.

The alignment device has a chuck table (not shown) that suction-holds the workpiece 11. With the back surface 11b of the workpiece 11 held by the chuck table, the coordinates of three different points on the outer peripheral end 11c are measured using the above-mentioned specific sensor, and the coordinates of the center of the front surface 11a are calculated.

The alignment device includes an adhesive application unit (not shown) that applies adhesive 13 to the upper surface 4a of the support part 4. After a predetermined amount of adhesive 13 has been applied to the center of the upper surface 4a, the workpiece 11 is transported to the support base 2 by a transport unit (not shown) of the alignment device so that the center of the upper surface 4a and the center of the surface 11a are approximately aligned.

If the outer peripheral end 11c of the workpiece 11 is within the upper surface 4a of the support part 4 when viewed from above, a certain degree of misalignment between the centers of the upper surface 4a and the surface 11a is permissible. For example, a misalignment of about 100 μm between the centers of the upper surface 4a and the surface 11a is permissible.

In the attachment step S10, for example, a vacuum press (not shown) is used to press the workpiece 11 onto the support 4 via the adhesive 13. The vacuum press has a metal chamber (not shown) in which the support base 2 is placed.

A temperature control mechanism (not shown) for controlling the temperature inside the chamber is provided at the bottom of the chamber. The temperature control mechanism includes a heater and a water-cooling mechanism.

Inside the chamber, there is a ring-shaped restricting member (not shown) that restricts the lateral movement of the support base 2 when pressed. In addition, above the restricting member, there is an airbag (not shown) that can inflate downwards in a substantially uniform manner.

When performing the attachment step S10, first, using the above-mentioned alignment device, with adhesive 13 provided between the support part 4 and the workpiece 11, the upper surface 4a and the surface 11a are brought face to face so that the centers of the upper surface 4a and the surface 11a are approximately aligned.

Next, the support base 2 on which the workpiece 11 is placed via the adhesive 13 is placed radially inside the regulating member in the chamber of the vacuum press, and then the chamber is made into a vacuum state of a predetermined degree.

In this state, the airbag is inflated while the support base 2 is heated by the heater, and the workpiece 11 is pressed against the support base 2 with a predetermined pressure. The predetermined pressure is, for example, a value of 0.05 MPa or more and 0.3 MPa or less.

Figure 3 is a diagram showing the attachment step S10. In Figure 3, the arrows indicate how the workpiece 11 is pressed. Note that in the attachment step S10, other press machines may be used instead of the vacuum press machine described above.

The adhesive 13 softened by heating is pushed outward beyond the outer circumferential end 11c of the workpiece 11 in the radial direction of the workpiece 11, and can move to the annular outer circumferential portion 6. However, in this embodiment, the pushed-out adhesive 13 does not move above a predetermined height position.

Specifically, the extruded adhesive 13 rises slightly along the chamfered portion 11d _A on the front surface 11a side, but most of it moves to the annular outer peripheral portion 6 (see FIG. 7A). Therefore, the rising position of the adhesive 13 becomes lower than the height position corresponding to the finished thickness 11e of the workpiece 11 thinned by the grinding device 8 (see FIG. 5) (see FIG. 7B).

After pressing for a predetermined time, the support base 2 is cooled and the adhesive 13 is hardened. This forms a workpiece unit 15 in which the workpiece 11 is attached to the support base 2 via the adhesive 13. Figure 4 (A) is a cross-sectional view of the workpiece unit 15 after the attachment step S10.

Figure 4 (B) is a top view of the workpiece unit 15 after the attachment step S10. As shown in Figure 4 (B), the amount of adhesive 13 that protrudes radially outward from the workpiece 11 may be uneven in the circumferential direction of the workpiece 11.

In this embodiment, the entire upper surface 6a of the annular outer periphery 6 is located lower than the upper surface 4a of the support portion 4, so even if the adhesive 13 protrudes unevenly outward in the radial direction of the workpiece 11, the adhesive 13 can be guided to the annular outer periphery 6. Therefore, the rising position of the adhesive 13 can always be lower than the height position corresponding to the finishing thickness 11e.

After the attachment step S10, the grinding step S20 is performed. In the grinding step S20, the grinding device 8 shown in FIG. 5 is used. The grinding device 8 has a disk-shaped chuck table 10. The chuck table 10 has a disk-shaped frame body 12 made of ceramics.

A disk-shaped recess having a predetermined depth is formed in the center of the frame 12. A predetermined flow path (not shown) is formed in the frame 12. One end of this flow path is exposed in the recess, and the other end of this flow path is connected to a suction source (not shown) such as an ejector.

A circular porous plate 14 made of porous ceramics and having a diameter approximately the same as the inner diameter of the recess is fixed in the recess. When the suction source is operated, negative pressure is transmitted to the porous plate 14 through a specified flow path.

The upper surface of the frame 12 and the upper surface of the porous plate 14 form a holding surface 10a that is approximately flush with each other. The holding surface 10a has a conical shape with its center protruding slightly compared to its outer periphery. A first rotation drive source (not shown), such as a motor, is provided below the chuck table 10.

The chuck table 10 is rotated around a predetermined rotation axis by a first rotation drive source. The predetermined rotation axis is slightly tilted with respect to the Z-axis direction so that a part of the holding surface 10a is approximately parallel to a predetermined plane (e.g., a horizontal plane) perpendicular to the Z-axis direction (e.g., a vertical direction).

A grinding unit 16 is fixed above the holding surface 10a. A ball screw type grinding feed unit (not shown) that moves the grinding unit 16 along the Z-axis direction (e.g., the vertical direction) is connected to the grinding unit 16.

The grinding unit 16 has a cylindrical spindle housing 18 arranged along the Z-axis direction. A part of the cylindrical spindle 20 is rotatably housed in the spindle housing 18.

A second rotation drive source (not shown), such as a motor, is provided at the upper end of the spindle 20. The lower end of the spindle 20 protrudes downward below the bottom of the spindle housing 18.

The center of the upper surface of a disk-shaped mount 22 is fixed to the lower end of the spindle 20. An annular grinding wheel 24 is attached to the lower surface of the mount 22. The grinding wheel 24 has an annular wheel base 26 made of metal.

On the underside of the wheel base 26, multiple grinding wheels 28 are arranged in a ring shape at predetermined intervals along the circumferential direction of the wheel base 26. Each grinding wheel 28 has abrasive grains such as diamond or cBN (cubic boron nitride) and a binder such as ceramic or resin that fixes the abrasive grains.

In the grinding step S20, the workpiece unit 15 is first placed on the chuck table 10 so that the lower surface 2b is in contact with the holding surface 10a, and then the support base 2 is suction-held by the holding surface 10a. At this time, the workpiece unit 15 is deformed to follow the shape of the holding surface 10a. Figure 5 is a partial cross-sectional side view of the workpiece unit 15 etc. held by the holding surface 10a.

After suction holding, the chuck table 10 and spindle 20 are rotated in a predetermined direction, and the grinding unit 16 is fed at a predetermined grinding feed rate while grinding water such as pure water is supplied to the contact area between the grinding wheel 28 and the workpiece 11.

Figure 6 is a partial cross-sectional side view showing grinding step S20. As shown in Figure 6, the workpiece 11 is supported by the support base 2 and is ground and thinned by the grinding wheel 24 to a finishing thickness 11e (see Figure 7 (B)). Figure 7 (A) is a cross-sectional view of the workpiece unit 15 near the step portion 2a before grinding step S20.

7A, the adhesive 13 pushed out radially outward of the workpiece 11 rises slightly along the chamfered portion _11dA on the front surface 11a side, but most of it moves to the annular outer periphery 6. Therefore, the adhesive 13 does not move above a predetermined height position where the grinding wheel 28 passes.

Figure 7 (B) is a cross-sectional view of the workpiece unit 15 near the step portion 2a after the grinding step. As shown in Figure 7 (B), the rise position of the adhesive 13 pushed outward is lower than the height position corresponding to the finished thickness 11e of the workpiece 11 after thinning. Therefore, in the grinding step S20, grinding of the adhesive 13 can be suppressed.

Next, a comparative example will be described in which the workpiece 11 is attached to a substantially flat support base 32 that is different from the support base 2, and then the workpiece 11 is ground. Figure 8 (A) shows the attachment step S10 in the comparative example.

In the attachment step S10 of the comparative example, the front surface 11a of the workpiece 11 is attached to the upper surface 32a of a disk-shaped support base 32, both of which have substantially flat upper and lower surfaces 32a and 32b, via adhesive 13. When attaching the workpiece 11 to the support base 32, an alignment device and a vacuum press are used, as in the first embodiment.

In this manner, a workpiece unit 17 is formed in which the workpiece 11 is attached to the support base 32 via the adhesive 13. FIG. 8(B) is a cross-sectional view of the workpiece unit 17 after the attachment step S10 according to the comparative example.

However, in the comparative example, the extruded adhesive 13 rises along the chamfered portion 11d _A on the front surface 11a side, and the rising position becomes higher than the height position corresponding to the finished thickness 11e of the workpiece 11, for example (see FIG. 9B).

Figure 9 (A) is a cross-sectional view of the vicinity of the outer peripheral end 11c of the workpiece 11 before the grinding step S20 according to the comparative example. Also, Figure 9 (B) is a cross-sectional view of the vicinity of the outer peripheral end 11c of the workpiece 11 after the grinding step S20 according to the comparative example.

As shown in FIG. 9(B), in the comparative example, a portion 13a of the adhesive 13 that protrudes to a position higher than the height position corresponding to the finishing thickness 11e is ground away, causing the grinding wheel 28 to become clogged, making it difficult to stably grind the workpiece 11.

In contrast, in the first embodiment, the adhesive 13 pushed outward from the outer circumferential end 11c in the radial direction of the workpiece 11 can move to the annular outer circumferential portion 6 of the support base 2. Specifically, the adhesive 13 does not move above a predetermined height position through which the grinding wheel 28 passes. Therefore, in the grinding step S20, grinding of the adhesive 13 can be suppressed.

Next, the second embodiment will be described. FIG. 10(A) is a cross-sectional view of the support base 42 in the second embodiment. The shape of the support base 42 in the second embodiment is substantially the same as the support base 2 in the first embodiment.

However, the support base 42 has an annular protrusion 44 at the outer peripheral end of the annular outer peripheral portion 6 that protrudes above the upper surface 6a in the thickness direction of the support base 42. However, the height position of the upper surface 44a of the annular protrusion 44 is lower than the upper surface 4a of the support part 4. In other words, the height position of the upper surface 44a is between the height positions of the upper surfaces 4a and 6a.

Therefore, in the attachment step S10, when the workpiece 11 is pressed against the support base 42 via the adhesive 13, the adhesive 13 that is pushed outward beyond the outer peripheral end portion 11c of the workpiece 11 in the radial direction of the workpiece 11 can move to the annular outer peripheral portion 6.

Figure 10 (B) is a cross-sectional view of the workpiece unit 19 in the second embodiment. Even in the attachment step S10 of the second embodiment, the adhesive 13 does not move above a predetermined height position where the grinding wheel 28 passes, so that grinding of the adhesive 13 can be suppressed in the grinding step S20.

Next, the third embodiment will be described. FIG. 11(A) is a cross-sectional view of the support base 52 in the third embodiment. The support base 52 in the third embodiment is substantially the same as the support base 2 in the first embodiment.

The annular outer periphery 6 gradually becomes thicker as it moves radially outward from the support base 2. In other words, the thickness of the annular outer periphery 6 is smallest at the boundary between the support portion 4 and the annular outer periphery 6, and is greatest at the outer periphery end of the support base 2. However, the upper surface 6a of the annular outer periphery 6 is lower than the upper surface 4a of the support portion 4, even at the outer periphery end of the support base 2.

Therefore, in the attachment step S10, when the workpiece 11 is pressed against the support base 42 via the adhesive 13, the adhesive 13 that is pushed outward beyond the outer peripheral end portion 11c of the workpiece 11 in the radial direction of the workpiece 11 can move to the annular outer peripheral portion 6.

Figure 11 (B) is a cross-sectional view of the workpiece unit 21 in the third embodiment. Even in the attachment step S10 of the third embodiment, the adhesive 13 does not move above a predetermined height position where the grinding wheel 28 passes, so that grinding of the adhesive 13 can be suppressed in the grinding step S20.

Next, the fourth embodiment will be described. The support base 62 according to the fourth embodiment is rectangular rather than disk-shaped. FIG. 12(A) is a cross-sectional view of the support base 62 according to the fourth embodiment, and FIG. 12(B) is a top view of the support base 62 according to the fourth embodiment.

The support base 62 has a rectangular support portion 4. For example, a rectangular package substrate (workpiece) on which multiple device chips are sealed with molded resin is attached to the upper surface 4a of the support portion 4. The rectangular upper surface 4a has an area equal to or greater than the area of a rectangle defined by the outline of the package substrate (not shown).

For example, the length of the long side of the top surface 4a is greater than the length of the long side of the package substrate by a predetermined value of 200 μm to 500 μm, and the length of the short side of the top surface 4a is greater than the length of the short side of the package substrate by a predetermined value of 200 μm to 500 μm.

A rectangular annular outer peripheral portion 6 having a thickness thinner than that of the support portion 4 is provided around the entire circumference of the support portion 4. For example, the long side of the annular outer peripheral portion 6 is 20 mm larger than the long side of the support portion 4, and the short side of the annular outer peripheral portion 6 is 20 mm larger than the short side of the support portion 4.

The support base 2 is made of a resin with a thermal expansion coefficient close to that of the thermosetting resin of the package substrate. For example, if the support base 2 is made of a resin, the thickness of the support part 4 is set to a predetermined value of 0.5 mm or more and 1.5 mm or less.

The lower surface of the support portion 4 and the lower surface of the annular outer peripheral portion 6 are substantially flush with each other, constituting the lower surface 2b of the support base 2. In addition, the upper surface 6a of the annular outer peripheral portion 6 is located lower than the upper surface 4a of the support portion 4. Therefore, an annular step portion 2a is formed at the boundary between the annular outer peripheral portion 6 and the support portion 4.

In the attachment step S10 of the fourth embodiment, when the package substrate is pressed against the support base 62 via the adhesive 13, the adhesive 13 pushed outward beyond the outer peripheral end of the package substrate in the long side direction and short side direction of the package substrate can move to the annular outer peripheral portion 6.

Therefore, even in the attachment step S10 of the fourth embodiment, the adhesive 13 does not move above the predetermined height position through which the grinding wheel 28 passes, so that grinding of the adhesive 13 can be suppressed in the grinding step S20.

The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. The rectangular workpiece in the fourth embodiment is not limited to a package substrate, but may be a substrate made of glass, ceramics, metal, etc.

2: Support base, 2a: Step portion, 2b: Lower surface 4: Support portion, 4a: Upper surface, 6: Annular outer peripheral portion, 6a: Upper surface 8: Grinding device, 10: Chuck table, 10a: Holding surface 12: Frame, 14: Porous plate 11: Workpiece, 11a: Front surface, 11b: Back surface 11c: Outer peripheral end portion, 11d _A , 11d _B : Chamfered portion, 11e: Finishing thickness 13: Adhesive, 13a: Part, 15, 17, 19, 21: Workpiece unit 16: Grinding unit, 18: Spindle housing, 20: Spindle 22: Mount, 24: Grinding wheel, 26: Wheel base, 28: Grinding stone 32: Support base, 32a: Upper surface, 32b: Lower surface 42: Support base, 44: Annular convex portion, 44a: Upper surface 52, 62: Support base

Claims (2)

A grinding method for grinding a workpiece which is a disk-shaped wafer, comprising the steps of :
a bonding step of bonding the workpiece to the support base by pressing the workpiece against the support base with an adhesive provided between the support part and the workpiece, the support base having a disk-shaped support part with an upper surface having an area equal to or larger than the area defined by the outline of the workpiece, and an annular outer peripheral part provided on the outer periphery of the support part and having an upper surface located at a position lower than the upper surface of the support part, the lower surface of the support part and the lower surface of the annular outer peripheral part being flush with each other and constituting the lower surface of the support base;
and a grinding step of holding the support base on a holding surface of a chuck table and grinding the workpiece with a grinding wheel after the attaching step,
The grinding method is characterized in that in the attaching step, the adhesive pushed out beyond the outer circumferential end of the workpiece by pressure is movable to the annular outer circumferential portion of the support base. A support base is attached to a workpiece , which is a disk-shaped wafer , via an adhesive and supports the workpiece during grinding of the workpiece,
A support part having a disk shape and an upper surface with an area equal to or larger than an area defined by an outline of the workpiece;
an annular outer peripheral portion provided on an outer periphery of the support portion and having an upper surface located at a position lower than an upper surface of the support portion;
Equipped with
A support base characterized in that a lower surface of said support portion and a lower surface of said annular outer peripheral portion are flush with each other and form a lower surface of said support base .

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