JP2006224201A - Grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel provided with a plurality of grinding wheel segments composed of a vitrified bond grinding wheel capable of preventing the occurrence of chipping even if the grinding wheel has high porosity. <P>SOLUTION: The grinding wheel is provided with a grinding wheel base 431 and a plurality of the grinding wheel segments 432 arranged on a prescribed circumference centering around the rotational axial center of the grinding wheel base on the grinding wheel mounting face of the grinding wheel base. The grinding wheel segment is composed of the vitrified bond grinding wheel formed by bonding super-abrasive grains with a vitrified bond and provided with innumerable pores. The front end face 432e, which specifies the front face in the rotational direction of the grinding wheel base, of the grinding wheel segment is formed into a convex curved face. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a grinding wheel including a plurality of grindstone segments made of a vitrified bond grindstone in which superabrasive grains are bonded by vitrified bond.

  As is well known to those skilled in the art, in a semiconductor device manufacturing process, a semiconductor wafer in which a plurality of circuits such as ICs and LSIs are formed is ground by a grinding device on the back surface before being divided into individual chips. It is formed in the thickness. In order to efficiently grind the back surface of a semiconductor wafer, a grinding apparatus having a rough grinding unit and a finish grinding unit is generally used. The rough grinding unit uses a vitrified bond or metal bond grindstone in which diamond grains with a relatively large particle diameter are bonded by vitrified bond or metal bond, and the finish grinding unit uses diamond bond grains with a small particle diameter by resin bond. A bonded resin bond grindstone is used.

  Vitrified bond grindstones are bonded with a silicon dioxide or other bond material, and the abrasive grains are bonded together, so the abrasive holding power is strong. There is a characteristic that the blade action is insufficient. On the other hand, the resin-bonded grindstone is soft against the workpiece because it is bonded with a soft resin-bonding material, and has a good abrasive action because of its weak abrasive holding power. Due to such characteristics of the grindstone, the vitrified bond grindstone is mainly used as a rough grinding grindstone, and the resin bond grindstone is mainly used as a finish grinding grindstone.

  However, as described above, the resin bond grindstone is flexible in the resin bond material, and when the grain size of the abrasive grains is 2 μm or less, the abrasive grains are pushed into the resin bond during grinding, and the grinding ability is reduced. Grinding burn occurs. Therefore, the resin bond grindstone must use abrasive grains having a particle diameter of 4 to 6 μm (# 2000) or more, and fine finish grinding becomes difficult.

  Since the vitrified bond grindstone has a strong abrasive grain holding force as described above, even if the abrasive grain is 0.5 μm (# 8000) or less, the abrasive is not pushed into the vitrified bond during grinding. Is maintained. However, the vitrified bond grindstone has a problem in that the vitrified bond firmly holds the abrasive grains as described above, so that the self-generated blade action is insufficient, and a streak-like scratch is generated on the ground surface.

In order to solve such a problem, a vitrified bond grindstone has been proposed in which pores are formed in an abrasive grain layer in which abrasive grains are bonded by vitrified bond to improve the self-sharpening action. (For example, see Patent Document 1)
JP 2003-136410 A

  In the vitrified bond grindstone disclosed in the above publication, pores formed in an abrasive layer in which abrasive grains are bonded by vitrified bonds are continuous pores. Therefore, when the porosity is increased, the strength of the grindstone is lowered and a predetermined grinding pressure cannot be obtained. In fact, the vitrified bond grindstone disclosed in the above publication has a porosity of 25 to 45% by volume, and the spontaneous blade action is not necessarily good.

  Therefore, the present applicant has proposed a vitrified bond grindstone having a porosity of 75 to 95% by volume as Japanese Patent Application No. 2004-150003 in order to ensure strength, increase the porosity, and improve the self-generated blade action. did.

  Thus, since the vitrified bond grindstone described above has a porosity of 75 to 95% by volume, chipping occurred partially due to the influence of external force such as grinding water and grinding resistance over time. In particular, in the case of a grinding wheel provided with a plurality of grindstone segments made of vitrified bond grindstones, the occurrence of the above-described chipping appears remarkably at the connecting portion between the front end surface in the rotational direction and the inner and outer surfaces. The chipped grindstone pulverized powder is sandwiched between the wafer, which is a workpiece, and the grindstone, causing scratches on the polished surface of the wafer and increasing the consumption of the grindstone.

  The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof includes a plurality of grindstone segments made of a vitrified bond grindstone capable of preventing the occurrence of chipping even with a grindstone having a high porosity. It is to provide a grinding wheel.

In order to solve the above-mentioned main technical problem, according to the present invention, a grindstone base and a grindstone mounting surface of the grindstone base are arranged on a predetermined circumference centering on a rotation axis of the grindstone base. A plurality of grindstone segments, the grindstone segments are combined with superabrasive grains by vitrified bonds, and have countless pores, and the porosity of the pores is 75 to 95% by volume. In grinding wheel,
The grindstone segment defines a mounted surface that defines a surface on the grindstone mounting surface side of the grindstone base, a grinding action surface that defines a surface opposite to the mounted surface, and an inner peripheral surface. An inner surface, an outer surface that defines an outer peripheral surface, a front end surface that defines a front surface in the rotational direction of the grindstone base, and a rear end surface that defines a surface opposite to the front end surface; At least the front end surface is formed in a convex curved surface;
A grinding wheel is provided.

  As for the above-mentioned grindstone segment, it is desirable for the above-mentioned rear end surface to be formed in the convex curved surface. The convex curved surface is preferably an arc surface. Furthermore, the pores are preferably independent pores.

  In the grinding wheel according to the present invention, since the front end surfaces of a plurality of grindstone segments made of vitrified bond grindstones are formed on convex curved surfaces, the grinding resistance is relaxed by the curved surfaces, so that chipping hardly occurs.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a grinding wheel constructed according to the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 shows a perspective view of a grinding apparatus equipped with a grinding wheel constructed in accordance with the present invention.
The grinding device in the illustrated embodiment includes a device housing 2 having a substantially rectangular parallelepiped shape. A stationary support plate 21 is erected on the upper right end of the device housing 2 in FIG. Two pairs of guide rails 22, 22 and 23, 23 extending in the vertical direction are provided on the inner surface of the stationary support plate 21. A rough grinding unit 3 as rough grinding means is mounted on one guide rail 22, 22 so as to be movable in the vertical direction, and a finish grinding unit 4 as finish grinding means is vertically installed on the other guide rail 23, 23. It is mounted to move in the direction.

  The rough grinding unit 3 includes a unit housing 31, a grinding wheel 33 attached to a wheel mount 32 rotatably attached to the lower end of the unit housing 31, and a wheel mount 32 attached to the upper end of the unit housing 31 with an arrow. An electric motor 34 that rotates in the direction indicated by 32a and a moving base 35 on which the unit housing 31 is mounted are provided. As shown in FIG. 2, the grinding wheel 33 includes an annular grindstone base 331 and a plurality of grindstone segments 332 made of a vitrified bond grindstone mounted on the lower surface of the grindstone base 331. A female screw hole 331a is formed in the grindstone base 331, and a wheel mount 32 is inserted by screwing a fastening screw 333 (see FIG. 1) disposed through the wheel mount 32 into the female screw hole 331a. It is attached to. The grindstone segment 332 is formed in a rectangular parallelepiped shape by combining diamond abrasive grains having a particle size of approximately 10 μm with vitrified bonds mainly composed of silicon dioxide. The plurality of grindstone segments 332 are disposed on a predetermined circumference around the rotation axis of the grindstone base 331 on the grindstone mounting surface (lower surface) of the grindstone base 331.

  Guided rails 351 and 351 are provided on the moving base 35, and the guided rails 351 and 351 are movably fitted to the guide rails 22 and 22 provided on the stationary support plate 21. The rough grinding unit 3 is supported so as to be movable in the vertical direction. The rough grinding unit 3 in the form shown in the figure includes a grinding feed mechanism 36 that moves the moving base 35 along the guide rails 22 and 22 and feeds the grinding wheel 33 by grinding. The grinding feed mechanism 36 includes a male screw rod 361 that is disposed on the stationary support plate 21 in a vertical direction parallel to the guide rails 22 and 22 and is rotatably supported, and a pulse motor 362 for rotationally driving the male screw rod 361. And a female screw block (not shown) that is mounted on the moving base 35 and is screwed with the male screw rod 361. By driving the male screw rod 361 forward and reverse by a pulse motor 362, the rough grinding unit 3 is moved up and down. It is moved in the direction (direction perpendicular to the holding surface of the chuck table described later).

  The finish grinding unit 4 is also configured in the same manner as the rough grinding unit 3, and includes a unit housing 41, a grinding wheel 43 attached to a wheel mount 42 rotatably attached to a lower end of the unit housing 41, and the unit. An electric motor 44 that is mounted on the upper end of the housing 41 and rotates the wheel mount 42 in the direction indicated by the arrow 42a, and a moving base 45 on which the unit housing 41 is mounted are provided. As shown in FIG. 3, the grinding wheel 43 includes an annular grindstone base 431 and a plurality of grindstone segments 432 made of a vitrified bond grindstone mounted on the grindstone mounting surface (lower surface) of the grindstone base 431. Yes. A female screw hole 431a is formed in the grindstone base 431, and by fastening a fastening screw 433 (see FIG. 1) disposed by inserting the wheel mount 42 into the female screw hole 431a, a wheel mount is obtained. 42 is attached. The plurality of grindstone segments 432 are arranged on a predetermined circumference around the rotation axis of the grindstone base 431 on the grindstone mounting surface (lower surface) of the grindstone base 431.

  Here, the segment 432 made of the vitrified bond grindstone will be described. The grindstone segment 432 is formed by bonding diamond abrasive grains having a grain size of 1 μm or less with vitrified bonds containing silicon dioxide as a main component, and has independent pores in the abrasive grain layer. In order to obtain a vitrified bond grindstone with independent pores, the abrasive grains, vitrified bond material, foaming agent and organic particles are kneaded and granulated to form granules, which are filled in a mold for molding. Then, a vitrified bond grindstone having independent pores can be obtained by press-molding into a predetermined shape and firing the molded product in a firing furnace. That is, the organic particles are burned out in the process of firing the molded product, and the honeycomb structure is formed in a space where the organic particles are burned out by vitrified bonds, diamond abrasive grains, and the foaming agent surrounding the organic particles. Form. The porosity of the independent pores is preferably 70 to 95% by volume. Thus, by comprising a vitrified bond grindstone having independent pores with a porosity of 70 to 95% by volume, the self-generated blade action is good, the grindability is excellent, and the strength can be ensured.

  The grindstone segment 432 includes a mounted surface 432a that defines a surface on the grindstone mounting surface (lower surface) side of the grindstone base 431, a grinding action surface 432b that defines a surface opposite to the mounted surface 432a, and an inner circumference. An inner side surface 432c that defines the side surface, an outer side surface 432d that defines the outer side surface, a front end surface 432e that defines the front side surface relative to the rotational direction 430 of the grindstone base 431, and the front end surface 432e, And a rear end surface 432f that defines an opposite surface (a surface on the rear side with respect to the rotation direction 430). In the illustrated embodiment, the front end surface 432e and the rear end surface 432f are formed as convex curved surfaces, more specifically, arcuate surfaces. The front end surface 432e and the rear end surface 432f of the grindstone segment 432 are formed into convex curved surfaces by chamfering 432g, 432g, 432h, and 432h at portions that intersect the inner side surface 432c and the outer side surface 432d as shown in FIG. May be.

  The plurality of grindstone segments 432 made of the vitrified bond grindstone configured as described above rotate the grindstone base 431 on the grindstone mounting surface (lower surface) of the grindstone base 431 as shown in FIG. It fits into an annular recess 431b provided on a predetermined circumference centered on the shaft core. At this time, the grindstone segment 432 is fixed to the grindstone mounting surface (lower surface) of the grindstone base 431 by interposing an adhesive between the fixed surface 432a and the recess 431b.

  Returning to FIG. 1, the description will be continued. Guided rails 451, 451 are provided on the moving base 45, and the guided rails 451, 451 are provided on the guide rails 23, provided on the stationary support plate 21, The finish grinding unit 4 is supported so as to be movable in the vertical direction. The finish grinding unit 4 in the illustrated form includes a feed mechanism 46 that moves the moving base 45 along the guide rails 23 and 23 and feeds the grinding wheel 43 by grinding. The feed mechanism 46 includes a male screw rod 461 that is disposed on the stationary support plate 21 in parallel with the guide rails 23 and 23 in a vertical direction and is rotatably supported, and a pulse motor 462 for rotationally driving the male screw rod 461. , A female screw block (not shown) mounted on the moving base 45 and screwed with the male screw rod 461 is provided, and the male screw rod 461 is driven forward and reverse by a pulse motor 462 to move the finish grinding unit 4 in the vertical direction. It is moved in a direction (perpendicular to the holding surface of the chuck table described later).

  The grinding apparatus in the illustrated embodiment includes a turntable 5 disposed so as to be substantially flush with the upper surface of the apparatus housing 2 on the front side of the stationary support plate 21. The turntable 5 is formed in a relatively large-diameter disk shape, and is appropriately rotated in a direction indicated by an arrow 5a by a rotation driving mechanism (not shown). In the illustrated embodiment, three chuck tables 6 are arranged on the turntable 5 so as to be rotatable in a horizontal plane with a phase angle of 120 degrees. The chuck table 6 includes a disk-shaped base 61 and a suction holding chuck 62 formed in a disk shape by a porous ceramic material, and a workpiece placed on the suction holding chuck 62 (holding surface). Suction is held by operating a suction means (not shown). The chuck table 6 configured as described above is rotated in a direction indicated by an arrow 6a by a rotation driving mechanism (not shown) as shown in FIG. The three chuck tables 6 arranged on the turntable 5 have a workpiece loading / unloading zone A, a rough grinding zone B, a finish grinding zone C, and a workpiece by appropriately rotating the turntable 5. It is sequentially moved to the loading / unloading area A.

  The illustrated grinding apparatus includes a first cassette 7 that is disposed on one side with respect to a workpiece loading / unloading area A and stocks a semiconductor wafer that is a workpiece before grinding, and a workpiece loading / unloading. Between the second cassette 8 which is disposed on the other side with respect to the area A and stocks the semiconductor wafer which is the workpiece after grinding, and between the first cassette 7 and the workpiece loading / unloading area A Centering means 9 for centering the workpiece to be disposed, a spinner cleaning means 11 disposed between the workpiece loading / unloading area A and the second cassette 8, and a first cassette 7 Workpiece transporting means 12 for transporting the semiconductor wafer, which is a work piece contained in the semiconductor wafer, to the centering means 9 and transporting the semiconductor wafer cleaned by the spinner cleaning means 11 to the second cassette 8, and centering Placed on means 9 Workpiece loading means 13 for transporting the aligned semiconductor wafer onto the chuck table 6 positioned in the workpiece loading / unloading area A, and on the chuck table 6 positioned in the workpiece loading / unloading area A A workpiece unloading means 14 for conveying the ground semiconductor wafer placed on the cleaning means 11 to the cleaning means 11 is provided. Note that a plurality of semiconductor wafers 15 are accommodated in the first cassette 7 with the protective tape 16 attached to the surface. At this time, the semiconductor wafer 15 is accommodated with the back surface 15b facing upward.

The grinding apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
A semiconductor wafer 15 which is a workpiece before grinding, which is accommodated in the first cassette 7, is conveyed by the vertical movement and advancing / retreating operation of the workpiece conveyance means 12, placed on the centering means 9 and six pins. Centered by radial movement toward the center of 91. The semiconductor wafer 15 placed and centered on the centering means 9 is placed on the suction holding chuck 62 of the chuck table 6 positioned in the workpiece loading / unloading area A by the turning operation of the workpiece loading means 14. Placed. Then, a suction means (not shown) is operated to suck and hold the semiconductor wafer 15 on the suction holding chuck 62. Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a by a rotation drive mechanism (not shown), and the chuck table 6 on which the semiconductor wafer is placed is positioned in the rough grinding area B.

  When the chuck table 6 holding the semiconductor wafer 15 is positioned in the rough grinding region B, the chuck table 6 is rotated in a direction indicated by an arrow 6a by a rotation driving mechanism (not shown). On the other hand, the grinding wheel 33 of the rough grinding unit 3 is lowered by a predetermined amount by the grinding feed mechanism 36 while being rotated in the direction indicated by the arrow 32a. As a result, rough grinding is performed on the back surface 15 b of the semiconductor wafer 15 on the chuck table 6. During this time, the semiconductor wafer 15 before grinding is placed on the next chuck table 6 positioned in the work carry-in / out area A as described above. Then, the semiconductor wafer 15 is sucked and held on the chuck table 6 by operating a suction means (not shown). Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a, the chuck table 6 holding the semiconductor wafer 15 subjected to rough grinding is positioned in the finish grinding region C, and the semiconductor before grinding is processed. The chuck table 6 holding the wafer 15 is positioned in the rough grinding area B.

  In this manner, the rough grinding unit 3 performs the rough grinding on the back surface 15b of the semiconductor wafer 15 before the rough grinding, which is held on the chuck table 6 positioned in the rough grinding region B, and finish grinding. The back surface 15b of the semiconductor wafer 15 placed on the chuck table 6 positioned in the region C and subjected to rough grinding is subjected to finish grinding by the finish grinding unit 4. During rough grinding and finish grinding, grinding water is supplied to the grindstone segment 332 of the grinding wheel 33 and the grindstone segment 432 of the grinding wheel 43. Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a, and the chuck table 6 holding the semiconductor wafer 15 subjected to finish grinding is positioned in the workpiece loading / unloading area A. The chuck table 6 holding the semiconductor wafer 15 subjected to rough grinding in the rough grinding region B is held in the finish grinding region C, and the chuck holding the semiconductor wafer 15 before grinding in the workpiece loading / unloading region A. The table 6 is moved to the rough grinding area B, respectively.

  The chuck table 6 that has returned to the workpiece loading / unloading zone A via the rough grinding zone B and the finish grinding zone C releases the suction holding of the semiconductor wafer 15 that has been ground here. Then, the finish-ground semiconductor wafer 15 on the chuck table 6 positioned in the workpiece carry-in / carry-out area A is carried out to the spinner cleaning means 11 by the workpiece carry-out means 14. The semiconductor wafer 15 transported to the spinner cleaning means 11 is spin-dried while the grinding debris adhering to the back surface 15a (grinding surface) and the side surface is cleaned and removed. The semiconductor wafer 15 thus cleaned and spin-dried is transported and stored in the second cassette 8 by the workpiece transport means 12.

  At the time of the above-described finish grinding, as shown in FIG. 5, the cutting water is supplied to the grindstone segment 432 through the cutting water supply passage 431c provided in the grindstone base 431 of the grinding wheel 43 as indicated by the arrow. Is made of vitrified bond grindstone and has a very high porosity of 70 to 95% by volume. Therefore, chipping is likely to occur partially due to the influence of cutting water and external forces such as grinding resistance. However, the grindstone segment 432 made of the vitrified bond grindstone in the illustrated embodiment has a front end face 432e and a rear end face 432f formed in an arcuate surface as shown in FIG. 3, and a front end face 432e and a rear end face as shown in FIG. Since portions 432f intersect with the inner side surface 432c and the outer side surface 432d are chamfered 432g, 432g, 432h, and 432h to form a convex curved surface, the cutting resistance is alleviated, so that chipping is unlikely to occur. At the time of cutting, since the cutting resistance acting on the front end surface 432e of the grindstone segment 432 is large, at least the front end surface 432e needs to be formed in a convex curved surface.

1 is a perspective view of a grinding apparatus equipped with a grinding wheel constructed according to the present invention. The perspective view of the grinding wheel which comprises the rough grinding unit with which the grinding apparatus shown in FIG. 1 is equipped. 1 is a perspective view showing one embodiment of a grinding wheel constructed according to the present invention. The perspective view which shows other embodiment of the grindstone segment which comprises the grinding wheel comprised according to this invention. Sectional drawing which expands and shows the principal part of the grinding wheel shown in FIG.

Explanation of symbols

2: Equipment housing 3: Rough grinding unit 33: Grinding wheel 332: Whetstone segment
4: Finish grinding unit 43: Grinding wheel 432: Grinding wheel segment 5: Turntable 6: Chuck table 7: First cassette 8: Second cassette 9: Centering means 11: Spinner cleaning means 12: Workpiece conveying means 13: Workpiece carry-in means 14: Workpiece carry-out means 15: Semiconductor wafer

Claims (4)

A grindstone base and a plurality of grindstone segments arranged on a predetermined circumference centering on a rotation axis of the grindstone base on a grindstone mounting surface of the grindstone base, the grindstone segment being super In a grinding wheel composed of a vitrified bond grindstone in which abrasive grains are bonded with vitrified bonds and provided with innumerable pores, and the porosity of the pores is 75 to 95 vol%.
The grindstone segment defines a mounted surface that defines a surface on the grindstone mounting surface side of the grindstone base, a grinding action surface that defines a surface opposite to the mounted surface, and an inner peripheral surface. An inner surface, an outer surface that defines an outer peripheral surface, a front end surface that defines a front surface in the rotational direction of the grindstone base, and a rear end surface that defines a surface opposite to the front end surface; At least the front end surface is formed in a convex curved surface;
A grinding wheel characterized by that.   The grinding wheel according to claim 1, wherein the rear end surface of the grindstone segment is formed into a convex curved surface.   The grinding wheel according to claim 1, wherein the convex curved surface is an arc surface.   The vitrified bond grindstone according to any one of claims 1 to 3, wherein the pores are independent pores.

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