TWI763861B - Grinding device - Google Patents

Abstract

[Problem] To provide a grinding device that can easily discharge grinding water to the outside of an annularly arranged grindstone. [Solution] The grinding device includes a grinding water supply mechanism, the grinding water supply mechanism includes a through passage that penetrates through the spindle and the mount, and the grinding water nozzle is arranged on the mount The center of the mounting surface side is connected to the through passage to discharge grinding water, and the grinding water nozzle includes a cylindrical body suspended from the mounting seat, a water discharge portion formed on the free end of the cylindrical body, and a through passage flowing down. Grinding water is induced to flow along the inner wall of the cylindrical body, and the water discharge portion has a chamfered portion that discharges grinding water gradually, so it can be directed toward the entire circumference of the annularly arranged grindstone. The tip portion is uniformly supplied with grinding water, and it becomes easy to discharge the grinding water to the outside of the grindstone from the fine gap between the surface to be ground of the wafer and the grindstone.

Description

Grinding device

Field of Invention

The present invention relates to a grinding device for grinding wafers.

Background of the Invention

When the wafer is thinned by grinding, there is a problem that the rigidity of the wafer decreases and the handling of the wafer becomes difficult in the subsequent steps. Therefore, for example, the following grinding methods have been proposed: Using a grinding wheel whose diameter is smaller than the diameter of the wafer and in which the grinding stones are arranged annularly, in the back surface of the wafer, a concave portion is formed in a region corresponding to an element region where a plurality of elements are formed, and a concave portion is formed in an area corresponding to the element An annular convex portion is formed in the region of the outer peripheral remaining region on the outer peripheral side of the region (for example, refer to the following Patent Document 1).

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2013-165287

Summary of Invention

However, in the above-mentioned grinding method, the grinding wheel is arranged on the surface of the wafer, and grinding water is supplied to the wafer and the grindstone, and the ring-shaped A half-circumference of the grindstone arranged at the lower part of the grinding wheel is brought into contact with the back surface of the wafer to perform grinding. At this time, since the gap between the grinding surface of the grindstone and the back surface of the wafer for the remaining half-circle is small, the grinding water supplied to the inside of the grindstone is difficult to discharge to the outside of the grindstone. Therefore, there is a problem that the grinding water remains inside the grinding stone, and the cooling of the grinding stone cannot be sufficiently performed, and there is a problem that the grinding surface is damaged or accelerated by the grinding chips contained in the accumulated grinding water. The problem of the consumption of the grindstone. In addition, when the grinding stone is used for grinding, there is a problem in that the outermost periphery of the wafer cannot be adjusted because the corner portions of the concave portions formed in the wafer are rounded instead of right angles. Part of the wafer is planarized.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a grinding stone that can easily discharge grinding water to the outside of a grindstone disposed annularly at a lower portion of a grinding wheel.

The present invention is a grinding apparatus comprising: a holding table: holding a wafer; and a grinding mechanism that is rotatably mounted with a grinding wheel and leaves the outer peripheral portion of the wafer held on the holding table. For grinding the central part, the grinding wheel has a diameter smaller than the diameter of the wafer and a grindstone is arranged in an annular shape; and a grinding water supply mechanism supplies grinding water to the grindstone and the wafer, and the grinding The grinding mechanism is provided with: a mounting seat having a mounting surface on which the grinding wheel is mounted; a main shaft, one end of which is connected so that the center of the mounting seat is aligned with the axis; a supporting mechanism, which rotatably supports the main shaft; The main shaft rotates, and the grinding water supply mechanism includes: a through passage that penetrates through the main shaft and the mounting seat connected to the main shaft; and a grinding water nozzle arranged on the mounting surface side of the mounting seat The grinding water nozzle is provided with a cylindrical body suspended from the mounting seat, a water discharge portion formed on a free end portion of the cylindrical body, and an induction portion provided with Between the through passage and the water discharge portion, and the grinding water that will flow down the through passage is induced to flow along the inner wall of the cylinder, the water discharge portion is provided with a mechanism for gradually expanding the grinding water. way to release the chamfered part.

The grinding apparatus of the present invention includes a grinding water supply mechanism for supplying grinding water to the grindstone and the wafer, and the grinding water supply mechanism includes a through passage penetrating through the main shaft and the mounting seat connected to the main shaft, and is arranged in the mounting base. The center of the mounting surface side of the base communicates with the through passage to discharge grinding water. and a guide portion arranged between the through passage and the water discharge portion to induce the grinding water flowing down the through passage to flow along the inner wall of the cylinder, and the water discharge portion is provided with a way to gradually expand the grinding water Since the chamfered portion is released, the grinding water can be uniformly supplied to the front end portion of the entire circumference of the grindstone arranged annularly, and it becomes easy to remove the grinding water from the fine particles between the surface to be ground of the wafer and the grindstone. The gap is discharged to the outside of the grindstone. Since the grinding chips or the detached abrasive grains can be discharged to the outside of the grinding stone together with the grinding water, it is possible to prevent damage to the ground surface of the wafer. In addition, since the grinding water can be sufficiently supplied to the tip portion of the entire circumference of the annularly arranged grindstone, the cooling effect of the grindstone can be improved and the consumption of the grindstone can be reduced.

1: Grinding device

2: Device base

2a: upper surface

3: Pillar

4: Mobile abutment

5: Hold Desk

5a: Keep Faces

6: Snake Belly

7: Screws

10: Grinding mechanism

11: Grinding wheel

11a: Lower surface

12: Grinding Stone

12a: Grinding surface

13: Mounting seat

13a: Installation surface

14: Spindle

15: Supporting mechanism

150: Shell

151: Supply Road

152: Air outlet

153: Gap

16, 22: Motor

17: Supporter

18: Grinding water supply source

19: Air supply source

20: Grinding feed mechanism

21: Ball screw

23: Rails

24: Lifting plate

30: Grinding water supply mechanism

31: Through passage

32, 32A: grinding water nozzle

33: Cylinder

33a, 38: Free end

33b: inner wall

34, 34A: Water discharge department

34a, 39: chamfered part

35: Induction Department

350: Connecting Road

351: Induction Road

352: Division of Divergence

36: Flange

37: Screw through hole

A: Arrow

B: Centerline

GW: grinding water

L: the height of the grindstone

P1: The half-circle area of the rotation track of the grindstone

P2: The semicircular area of the remaining grindstone

T1: Thickness of the convex part

T2: Thickness of the recess

W: Wafer

Wa: front

Wb: Back

Wc: convex part

Wd: Recess

Wo: The rotation center of the wafer

X, Y, Z: direction

FIG. 1 is a perspective view showing the structure of a grinding apparatus.

2 is a cross-sectional view showing the configuration of a grinding mechanism and a grinding water supply mechanism.

Fig. 3 is an enlarged cross-sectional view showing the main parts of the grinding mechanism and the grinding water supply mechanism.

Fig. 4(a) is a plan view of the grinding water nozzle viewed from above. (b) is a bottom view of the grinding water nozzle viewed from below.

FIG. 5 is a cross-sectional view showing a state in which a wafer is ground by a grinding wheel.

FIG. 6 is a perspective view showing a state in which a wafer is ground by a grinding wheel.

7 is a plan view illustrating a state in which the wafer is ground while supplying grinding water to the wafer and the grindstone.

FIG. 8( a ) is a cross-sectional view showing a modification of the grinding water nozzle. (b) is a plan view of a modification of the grinding water nozzle viewed from above. (c) is a bottom view of a modification of the grinding water nozzle viewed from below.

Form for carrying out the invention

The grinding apparatus 1 shown in FIG. 1 has an apparatus base 2 extending in the Y-axis direction, and a support column 3 erected on the rear side in the Y-axis direction of the apparatus base 2 . The upper surface 2a of the apparatus base 2 is provided with a holding table 5 having a holding surface 5a for holding the wafer. The holding table 5 is connected to the suction source. The periphery of the holding table 5 is covered by a movable base 4 that can move in the Y-axis direction. A not-shown moving mechanism covered by the accordion 6 is arranged below the holding table 5, and the holding table 5 and the moving base 4 are moved in the Y-axis direction by the moving mechanism.

A grinding mechanism 10 , a grinding feed mechanism 20 , and a grinding water supply mechanism 30 are provided in front of the support column 3 . The grinding mechanism 10 is rotatably mounted with a grinding wheel 11 and is held on the holding table 5 . The outer peripheral part of the wafer is left and the central part is ground, wherein the grinding wheel has a diameter smaller than the diameter of the wafer, and the grinding stone 12 is annularly arranged. The grinding feeding mechanism 20 is a grinding mechanism 10 This grinding water supply mechanism 30 supplies grinding water to the grindstone 12 and the wafer for grinding and feeding in the direction of approaching and separating from the holding table 5 (Z-axis direction).

The grinding feed mechanism 20 includes a ball screw 21 extending in the Z-axis direction, a motor 22 connected to one end of the ball screw 21, a pair of guide rails 23 extending parallel to the ball screw 21, and one surface of which is fixed to the grinding wheel. Lifting plate 24 of mechanism 10 . The other side of the lift plate 24 can be in sliding contact with the pair of guide rails 23 , and a ball screw 21 is screwed into a nut formed inside the lift plate 24 . By rotating the ball screw 21 with the motor 22 , the grinding mechanism 10 can be moved in the Z-axis direction together with the lift plate 24 .

The grinding mechanism 10 includes a grinding wheel 11 in which a grindstone 12 for grinding a wafer is fixed annularly, a mounting seat 13 having a mounting surface 13 a on which the grinding wheel 11 is mounted, and a The main shaft 14 whose center is aligned with the axis, and one end is connected, a support mechanism 15 that rotatably supports the main shaft 14 , and a motor 16 shown in FIG. 2 that rotates the main shaft 14 . Although the grindstone 12 shown in this embodiment is comprised with a grindstone (segment) grindstone, it is not limited to this structure. The mounting surface 13a of the mounting seat 13 is a flat surface parallel to the horizontal direction orthogonal to the vertical direction.

The support mechanism 15 is provided with a housing 150 rotatably surrounding the main shaft 14 . The housing 150 is supported by the holder 17 fixed on the lift plate 24 and kept. As shown in FIG. 2 , the casing 150 is provided with an air supply passage 151 connected to the air supply source 19 and an air outlet 152 for discharging high-pressure air into a gap 153 between the casing 150 and the main shaft 14 . The main shaft 14 accommodated in the housing 150 is rotatably supported in a non-contact state by the high-pressure air ejected from the air ejection port 152 to the gap 153 .

The grinding water supply mechanism 30 includes a through passage 31 penetrating the main shaft 14 and a mounting seat 13 connected to the main shaft 14 and a grinding water nozzle 32 , and the grinding water nozzle 32 is arranged on the mounting seat 13 . The center on the side of the installation surface 13a is communicated with the through passage 31 to discharge grinding water. The grinding water supply source 18 is connected to the upper end of the through passage 31 .

As shown in FIG. 3 , the grinding water nozzle 32 includes a cylindrical body 33 suspended from a through passage 31 formed in the center of the main shaft 14 and the mounting seat 13 , and a water discharge portion formed on a free end portion 33 a of the cylindrical body 33 . 34 , and an induction portion 35 arranged between the through passage 31 and the water discharge portion 34 and guiding the grinding water flowing down the through passage 31 to flow along the inner wall 33 b of the cylindrical body 33 .

A flange portion 36 is disposed on the upper end portion of the cylindrical body 33 . On the flange portion 36, as shown in FIG. 4(a), a plurality of (four in the illustrated example) screw penetration holes 37 are formed at equal intervals in the circumferential direction. In the mounting surface 13 a of the mounting seat 13 shown in FIG. 3 , the female screw to which the screw 7 is screwed is also formed corresponding to the position of the screw through hole 37 . When the grinding water nozzle 32 is attached to the mounting base 13 , the grinding water nozzle 32 can be fixed by inserting the screw 7 into the screw through hole 37 of the flange portion 36 from below and screwing it to the female screw. to the mounting surface 13 a of the mounting seat 13 .

The guide portion 35 includes a communication passage that communicates with the through passage 31 350 , and a guide path 351 that is branched by the branching portion 352 provided inside the cylinder 33 . The guide path 351 is a hollow provided at a position near the inner wall 33 b of the cylindrical body 33 . In the present embodiment, as shown in FIG. 4( b ), a plurality of (three in the illustrated example) induction paths 351 are formed at equal intervals in the circumferential direction. In the guide portion 35 configured in this way, when grinding water flows from the communication passage 350 into the guide passage 351 during grinding, the grinding water is radially outward due to centrifugal force caused by the rotation of the main shaft 14 . Therefore, the grinding water can be induced to flow down along the inner wall 33b. The number of the induction paths 351 is not particularly limited to the configuration shown in this embodiment.

The water discharge part 34 shown in FIG. 3 is the structure which expands so that it may expand gradually (umbrella shape), and is provided with the chamfered part 34a of the push-pull shape. In the water discharge part 34, the grinding water flowing down the inner wall 33b by the guiding part 35 is further guided by the centrifugal force formed by the rotation of the grinding wheel 11 and the self-weight of the grinding water. Since it flows out at the chamfered portion 34a, the grinding water can be released gradually (in an umbrella shape). Thereby, the grinding water can be uniformly supplied toward the tip portion of the entire circumference of the annularly arranged grindstone 12 . That is, the grinding water can be sufficiently supplied not only to the contact portion of the grindstone 12 and the wafer, but also to the fine gap where the grindstone 12 and the wafer are not in contact.

Here, the lower end (free end 33a of the cylindrical body 33) of the grinding water nozzle 32 shown in FIG. Since it is arranged above the lower surface 11a of the grinding wheel 11, the grinding water cannot be efficiently supplied to the front end portion of the grinding stone 12. The lower end of the grinding water nozzle 32 is preferably positioned below the lower surface 11a of the grinding wheel 11 so that the water discharge portion 34 is positioned close to the wafer to be processed.

Next, an example of grinding will be described using the grinding apparatus 1 in which the central portion of the wafer W shown in FIG. 2 is ground to form the concave portion Wd, the outer peripheral portion is left, and the annular convex portion Wc is formed on the outer peripheral portion. . In the wafer W, the surface on which the element is formed is the front surface Wa, and a protective tape, for example, is attached to the front surface Wa. On the other hand, the back surface Wb on the opposite side to the front surface Wa is a to-be-ground surface ground by the grindstone 12 .

Here, the height L of the grindstone 12 used for grinding as shown in the present embodiment must be larger than the thickness T1 of the convex portion Wc formed on the outer peripheral portion of the wafer W (the thickness of the wafer W before grinding ) is larger. When the thickness T1 of the convex portion Wc is, for example, 750 μm, in order to reduce the thickness T2 of the concave portion Wd to, for example, 100 μm, the height L of the grindstone 12 at the time of maximum wear must be larger than 650 μm. Moreover, it is preferable to arrange the lower end of the grinding water nozzle 32 at a position higher than the grinding surface 12a of the grindstone 12 at the time of maximum grinding.

As shown in FIG. 5 , the front surface Wa side of the wafer W is placed on the holding surface 5a of the holding table 5 so that the back surface Wb side is exposed. Next, after the wafer W is sucked and held on the holding surface 5 a by the suction force of a suction source not shown, the holding table 5 can be moved to the lower side of the grinding mechanism 10 . After that, the grinding mechanism 10 is lowered in the direction approaching the holding table 5 by the grinding feed mechanism 20 shown in FIG. 1 . In addition, although the holding surface 5a of the holding table 5 is formed to be an inclined surface that is inclined from the center to the outer peripheral edge, it is not actually formed. Inclined planes that are so subtle that they can be discerned with the naked eye.

Next, as shown in FIG. 6 , the holding table 5 is rotated, for example, in the direction of arrow A, and the grinding mechanism 10 rotates the grinding wheel 11 in the direction of arrow A by the rotating spindle 14 , while grinding the grinding stone 12 . The ground surface 12a is ground in contact with the back surface Wb of the wafer W. As shown in FIG.

As shown in FIG. 7 , the grinding apparatus 10 rotates the grindstone 12 so as to pass through the rotation center Wo of the wafer W at all times. Specifically, the half-circumferential region P1 (the left part with the center line B as the axis) that is the rotation locus of the grindstone 12 is always in contact with the rotation center Wo of the wafer W, and only the center part of the wafer W is ground. The concave portion Wd is formed by sharpening, and the annular convex portion Wc is formed on the outer peripheral portion of the wafer W. As shown in FIG. At this time, the remaining half-circumferential region P2 of the grindstone 12 (the right part with the center line B as the axis) does not come into contact with the crystal pattern W, but a fine gap appears between the concave portion Wd and the grindstone 12 .

During the grinding of the wafer W, the grinding water GW is always supplied from the water discharge unit 34 to the inside of the rotating grindstone 12 . Specifically, from the grinding water supply source 18 shown in FIG. 3 , the grinding water GW of a predetermined flow rate is caused to flow into the through passage 31 . The grinding water GW flowing down the through passage 31 flows down the inner wall 33b of the cylindrical body 33 along with the centrifugal force formed by the rotation of the main shaft 14 through the guide portion 35, and also flows from the inner wall 33b. It flows out along the chamfered portion 34a, and is discharged from the water discharge portion 34 in an umbrella shape.

As shown in FIG. 7 , the grinding water GW discharged from the water discharge part 34 in an umbrella shape flows out radially toward the entire circumference of the grindstone 12 . Therefore, it becomes easy to discharge the grinding water GW to the outside of the grindstone 12 from the fine gap between the grindstone 12 and the concave portion Wd in the above-mentioned half-circumference region P2 side. The grinding water GW accumulated in the concave portion Wd formed on the inner side of the grindstone 12 contains the grinding debris or the dropped abrasive grains of the wafer W, and the grinding debris or the dropped abrasive grains are discharged together with the grinding water GW to the outside of the grindstone 12 .

As described above, the grinding apparatus 1 of the present invention includes the grinding water supply mechanism 30 for supplying the grinding water GW to the grindstone 12 and the wafer W, and the grinding water supply mechanism 30 includes the grinding water supply mechanism 30 which penetrates through the main shaft 14 and is connected to the main shaft 14 . The through passage 31 of the mounting seat 13 and the grinding water nozzle 32 which is arranged in the center of the mounting surface 13a side of the mounting seat 13 and communicates with the through passage 31 to discharge the grinding water GW, the grinding water nozzle 32 is provided with The cylindrical body 33 suspended from the mounting base 13 , the water discharge portion 34 formed at the free end portion 33 a of the cylindrical body 33 , and the grinding water GW disposed between the through passage 31 and the water discharge portion 34 and flowing down the through passage 31 Since the guide part 35 is guided to flow along the inner wall 33b of the cylindrical body 33, and the water discharge part 34 is provided with the chamfer part 34a that discharges the grinding water GW gradually, it can be directed toward the grinding The tip portion of the entire circumference of the stone 12 is uniformly supplied with the grinding water GW, and the grinding water GW can be easily discharged from the fine gap between the ground surface (recess Wd) of the wafer W and the grinding stone 12 to the grinding wheel. Outside of stone 12. Since the grinding debris or the detached abrasive grains can be discharged to the outside of the grindstone 12 together with the grinding water GW, the grinding debris or the detached abrasive grains can be effectively removed from the surface to be ground of the wafer W to prevent damage to the wafer. The case where the ground surface of W is damaged. In addition, according to the present invention, since the grinding water GW is sufficiently supplied to the tip portion of the entire circumference of the grindstone 12 arranged annularly, the cooling effect of the grindstone 12 can be improved and the consumption of the grindstone 12 can be reduced.

The grinding water nozzle 32A shown in FIG. 8 is a modification of the grinding water nozzle 32 described above. The grinding water nozzle 32A is as shown in FIG. 8( a ), and is provided with There is a cylindrical body 33, a water discharge portion 34A formed on a free end portion 38 of the cylindrical body 33, and a water discharge portion 34A arranged between the through passage (not shown) and the water discharge portion 34A, and the grinding water flowing down the through passage 31 is induced into a The induction portion 35 flows along the inner wall 33 b of the cylindrical body 33 . A flange portion 36 is arranged on the upper end of the grinding water nozzle 32A, and as shown in FIG. 8( b ), a plurality of flange portions 36 are formed at equal intervals in the circumferential direction (in the figure In the example shown, there are four screw through holes 37 . The inner wall 33b of the cylindrical body 33 is linearly formed to the free end part 38 shown in FIG.8(c), and the chamfer part 39 is formed in the lowermost part. Even in the grinding water nozzle 32A thus constituted, the centrifugal force formed by the rotation of the main shaft 14 and the self-weight of the grinding water GW can make the grinding water GW reach the inner wall 33b and the chamfered portion of the cylindrical body 33 . 39 flows down along the edge, and discharges the grinding water GW in the form of an umbrella from the water discharge part 34A.

10‧‧‧Grinding mechanism

11‧‧‧grinding wheel

11a‧‧‧Lower surface

12‧‧‧Wheelstone

12a‧‧‧Grinding surface

13‧‧‧Mount

13a‧‧‧Installation surface

14‧‧‧Spindle

15‧‧‧Supporting mechanism

150‧‧‧Case

151‧‧‧Supply Road

152‧‧‧Air outlet

153‧‧‧clearance

16‧‧‧Motor

18‧‧‧Supply source of grinding water

19‧‧‧Air supply source

30‧‧‧Grinding water supply mechanism

31‧‧‧Through Road

32‧‧‧Grinding water nozzle

33‧‧‧Cylinder

33a‧‧‧Free end

33b‧‧‧Inner Wall

34‧‧‧Water discharge department

35‧‧‧Induction Department

36‧‧‧Flange

GW‧‧‧grinding water

L‧‧‧The height of the grindstone

T1‧‧‧Thickness of convex part

T2‧‧‧Thickness of recess

W‧‧‧Wafer

Wa‧‧‧Front

Wb‧‧‧Back

Wc‧‧‧Protrusion

Wd‧‧‧Recess

Claims (1)

A grinding apparatus comprising: a holding table holding a wafer; a grinding mechanism rotatably equipped with a grinding wheel and grinding a central part while leaving the outer peripheral part of the wafer held on the holding table, the The grinding wheel is provided with a grinding stone having a diameter smaller than the diameter of the wafer, and a grinding stone is arranged annularly; The installation surface on which the grinding wheel is installed; the main shaft, which makes the center of the mounting seat coincide with the shaft center to connect one end; the supporting mechanism, which rotatably supports the main shaft; and the motor, which rotates the main shaft, and supplies the grinding water The mechanism includes: a through passage that penetrates through the main shaft and the mounting seat connected to the main shaft; and a grinding water nozzle, which is arranged in the center of the mounting surface side of the mounting seat and communicates with the through passage to discharge the Grinding water, the grinding water nozzle includes: a cylindrical body suspended from the mounting seat; a water discharge part formed at a free end of the cylindrical body; and a guide part disposed between the through passage and the water discharge part, And the grinding water flowing down the through passage is induced to flow along the inner wall of the cylindrical body, and the water discharge part is provided with a chamfered part that discharges the grinding water in an umbrella shape.

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