JP4977493B2 - Dressing method and dressing tool for grinding wheel - Google Patents

Description

  The present invention relates to a grinding wheel dressing method and a dressing tool equipped in a grinding apparatus for grinding a workpiece such as a semiconductor wafer.

  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 wheel in which diamond grains having a relatively large particle size are bonded by vitrified bond or metal bond, and the finish grinding unit uses diamond bond particles having a small particle diameter by resin bond. A bonded resin bond grindstone is used.

  Vitrified bond whetstones have a high abrasive holding power because they are bonded with a bond material mainly composed of silicon dioxide. 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 size of 2 to 4 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-generated blade action. (For example, see Patent Document 1)
JP 2003-136410 A

  However, a vitrified bond grindstone in which pores are formed in an abrasive layer in which abrasive grains are bonded by vitrified bond is superabrasive on a conventional dressing board formed by solidifying alumina abrasive grains or diamond abrasive grains by resin bond, or a metal plate. When dressing is performed using a conventional dressing board in which grains are fixed by plating, there is a problem in that although grinding ability is temporarily increased, the grinding ability is stabilized. In addition, it turned out that this problem is not an exception also in the vitrified bond grindstone which does not have a pore in the abrasive grain layer used conventionally.

In order to solve such problems, a dressing method and a dressing board for dressing a vitrified bond grindstone using a dressing board formed of a glass plate or a member bonded with a vitrified bond mainly composed of silicon dioxide are proposed. Has been. (For example, see Patent Document 2)
JP 2006-15423 A

According to the above dressing method, since the bond material holding the abrasive grains of the vitrified bond grindstone is polished with a dressing board made of a glass plate made of the same quality material, dressing without difficulty is performed. Since the board is sticky, the dressing effect is not always satisfactory.
For dressing a grinding wheel, a dressing board in which abrasive grains are hardened by a resin bond is generally used. For example, in order to dress a grinding wheel in which abrasive grains are bonded with a bonding agent, it is necessary to manufacture a dressing board using abrasive grains having a particle size smaller than the particle size of the abrasive grains forming the grinding wheel, In order to perform dressing effectively, it is necessary to make the grain size of the abrasive grains uniform. However, in order to prepare abrasive grains having a small particle size, the cost increases.

The present invention has been made in view of the above-mentioned facts, and the main technical problem thereof is to provide a dressing method and a dressing tool for a grinding wheel that can effectively dress a vitrified bond grinding wheel and can be manufactured at low cost. It is to provide.

In order to solve the main technical problem, according to the present invention, a chuck table for holding a workpiece and a grinding means for grinding the workpiece held on the chuck table are provided, and the grinding means is rotated. In a grinding apparatus having a grinding wheel equipped with a wheel mount capable of being attached and detachably attached to the wheel mount and grinding a workpiece , diamond abrasive grains having a grain size of 5 μm or less are mainly composed of silicon dioxide. A grinding wheel dressing method for dressing a vitrified bond grindstone formed by bonding with vitrified bonds as components and having independent pores in the abrasive grain layer ,
A dressing board having grooves formed on the surface of a silicon substrate is held on the chuck table, and the vitrified bond grindstone is attached to the silicon substrate while rotating the chuck table and rotating the wheel mount on which the grinding wheel is mounted. Dressing the ground surface of the vitrified bond wheel in contact with the surface;
A method for dressing a grinding wheel is provided.

Further, according to the present invention, there is provided a vitrified bond grindstone which is formed by bonding diamond abrasive grains having a particle size of 5 μm or less by vitrified bonds mainly composed of silicon dioxide and having independent pores in the abrasive grain layer. A dressing tool for a grinding wheel for dressing,
It consists of a dressing board in which grooves are formed on the surface of a silicon substrate, and a support plate to which the dressing board is fixed with a bonding agent.
A dressing tool for a grinding wheel is provided.

  The groove formed on the surface of the silicon substrate constituting the dressing board has a width of 2 to 6 mm and is composed of two grooves perpendicular to the center of the silicon substrate.

A dressing method for a vitrified bond grindstone formed by bonding diamond abrasive grains having a grain size of 5 μm or less according to the present invention with vitrified bonds mainly composed of silicon dioxide and having independent pores in the abrasive grain layer is a silicon substrate. Since the dressing board is formed with grooves on the surface, the dressing is more stable than the dressing board made of glass. That is, since the silicon substrate is not sticky and fragile as compared with the glass plate, the edge portion forming the groove appropriately grinds the grinding wheel, so that stable dressing is performed. In addition, a dressing board formed of a silicon substrate can be manufactured at low cost because it can be manufactured by forming a groove in a silicon wafer generally used as a semiconductor wafer.

Hereinafter, preferred embodiments of a dressing method and a dressing tool for a grinding wheel according to the present invention will be described in more detail with reference to the accompanying drawings.
FIG. 1 is a perspective view of a grinding apparatus for carrying out the dressing method for a grinding wheel according to the present invention. The grinding apparatus shown in FIG. 1 is provided with an apparatus housing generally indicated by numeral 2. This device housing 2 has a rectangular parallelepiped main portion 21 that extends long and an upright wall 22 that is provided at the rear end portion (upper right end in FIG. 1) of the main portion 21 and extends substantially vertically upward. ing. A pair of guide rails 221 and 221 extending in the vertical direction are provided on the front surface of the upright wall 22. A grinding unit 3 as grinding means is mounted on the pair of guide rails 221 and 221 so as to be movable in the vertical direction.

  The grinding unit 3 includes a moving base 31 and a spindle unit 4 mounted on the moving base 31. The movable base 31 is provided with a pair of legs 311 and 311 extending in the vertical direction on both sides of the rear surface. The pair of legs 311 and 311 is slidably engaged with the pair of guide rails 221 and 221. Guided grooves 312 and 312 are formed. As described above, a support portion 313 protruding forward is provided on the front surface of the movable base 31 slidably mounted on the pair of guide rails 221 and 221 provided on the upright wall 22. The spindle unit 4 is attached to the support portion 313.

  The spindle unit 4 includes a spindle housing 41 mounted on the support portion 313, a rotary spindle 42 rotatably disposed on the spindle housing 41, and a servo motor as a drive source for rotationally driving the rotary spindle 42. 43. One end (lower end in FIG. 1) of the rotary spindle 42 rotatably supported by the spindle housing 41 is disposed so as to protrude from the lower end of the spindle housing 41, and a wheel mount is mounted on one end (lower end in FIG. 1). 44 is provided. The grinding wheel 5 is attached to the lower surface of the wheel mount 44.

The grinding wheel 5 will be described with reference to FIG.
The grinding wheel 5 shown in FIG. 2 includes an annular grindstone base 51 and a plurality of segments including a grinding grindstone 52 mounted on the lower surface of the grindstone base 51. A female screw hole 511 is formed in the grindstone base 51, and the wheel mount 44 is inserted into the female screw hole 511 by screwing a fastening screw 6 (see FIG. 1) disposed through the wheel mount 44. It is attached to. In the illustrated embodiment, the grinding wheel 52 is formed by bonding diamond abrasive grains having a grain size of 5 μm or less with vitrified bonds mainly composed of silicon dioxide, and has an independent pore in the abrasive grain layer. It consists of a vitrified bond whetstone.

  Referring back to FIG. 1, the grinding apparatus in the illustrated embodiment moves the grinding unit 3 up and down along the pair of guide rails 221 and 221 (perpendicular to a holding surface of a chuck table described later). A grinding unit feed mechanism 7 that is moved in the direction). The grinding unit feed mechanism 7 includes a male screw rod 71 disposed on the front side of the upright wall 22 and extending substantially vertically. The male screw rod 71 is rotatably supported by bearing members 72 and 73 whose upper end and lower end are attached to the upright wall 22. The upper bearing member 72 is provided with a pulse motor 74 as a drive source for rotationally driving the male screw rod 71, and an output shaft of the pulse motor 74 is transmission-coupled to the male screw rod 71. A connecting portion (not shown) that protrudes rearward from the center portion in the width direction is also formed on the rear surface of the movable base 31, and a through female screw hole (not shown) that extends in the vertical direction is formed in this connecting portion. The male screw rod 71 is screwed into the female screw hole. Accordingly, when the pulse motor 74 is rotated forward, the moving base 31, that is, the polishing unit 3 is lowered or advanced, and when the pulse motor 74 is reversed, the movable base 31, that is, the grinding unit 3 is raised or moved backward.

  Continuing the description with reference to FIG. 1, the chuck table mechanism 8 is disposed in the main portion 21 of the housing 2. The chuck table mechanism 8 includes a chuck table 81, a cover member 82 that covers the periphery of the chuck table 81, and bellows means 83 and 84 that are disposed before and after the cover member 82. The chuck table 81 is configured to be rotated by a rotation driving unit (not shown), and is configured to suck and hold a wafer as a workpiece on its upper surface by operating a suction unit (not shown). Also, the chuck table 81 is moved between a workpiece placement area 80a shown in FIG. 1 and a grinding area 80b facing the grinding wheel 5 constituting the spindle unit 4 by a chuck table moving means (not shown). The bellows means 83 and 84 can be formed from any suitable material such as campus cloth. The front end of the bellows means 83 is fixed to the front wall of the main portion 21, and the rear end is fixed to the front end surface of the cover member 82. The front end of the bellows means 84 is fixed to the rear end surface of the cover member 82, and the rear end is fixed to the front surface of the upright wall 22 of the apparatus housing 2. When the chuck table 81 is moved in the direction indicated by the arrow 81a, the bellows means 83 is expanded and the bellows means 84 is contracted. When the chuck table 81 is moved in the direction indicated by the arrow 81b, the bellows means 83 is By contracting, the bellows means 84 is extended.

The grinding apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
As shown in FIG. 1, a semiconductor wafer W as a workpiece is placed on a chuck table 81 positioned in a workpiece placement area 80a of the polishing apparatus. A protective tape T is attached to the surface on which the device of the semiconductor wafer W is formed, and the protective tape T side is placed on the chuck table 81. The semiconductor wafer W placed on the chuck table 81 in this way is sucked and held on the chuck table 81 by suction means (not shown). If the semiconductor wafer W is sucked and held on the chuck table 81, the chuck table moving means (not shown) is operated to move the chuck table 81 in the direction indicated by the arrow 81a and position it in the grinding zone 80b. Then, the outer peripheral edges of the plurality of grinding wheels 52 of the grinding wheel 5 are positioned so as to pass through the rotation center of the chuck table 81, that is, the center of the semiconductor wafer W.

  When the semiconductor wafer W held on the grinding wheel 5 and the chuck table 81 is set in a predetermined positional relationship in this way, the chuck table 81 is rotated in a predetermined direction at a rotational speed of, for example, 300 rpm, and the grinding wheel 5 Is rotated in a predetermined direction at a rotation speed of, for example, 6000 rpm. Then, the grinding wheel 5 is lowered to press the plurality of grinding wheels 52 against the back surface (surface to be ground), which is the top surface of the semiconductor wafer W, with a predetermined pressure. As a result, the surface to be polished of the semiconductor wafer W is ground over the entire surface.

  By performing the grinding operation described above, the grinding ability of the grinding wheel 52 is reduced due to wear, clogging, and the like. Therefore, if the grinding operation is performed for a predetermined time, the grinding wheel 52 is dressed (sharpened). Hereinafter, a dressing tool for dressing a grinding wheel will be described.

  FIG. 3 shows a perspective view of one embodiment of a dressing tool according to the present invention. A dressing tool 10 shown in FIG. 3 includes a dressing board 11 made of a silicon substrate and a support plate 12 that supports the dressing board 11. In the illustrated embodiment, the dressing board 11 made of a silicon substrate is formed in a circular shape having a thickness of 1 mm and having a diameter (for example, 100 mm) that is a half of the outer diameter of the grinding wheel 5. On the surface 11 a of the dressing board 11, two grooves 111 that pass through the center and are orthogonal to each other are formed. In the illustrated embodiment, the two grooves 111 have a width of 2 to 6 mm and a depth of 0.6 to 0.7 mm.

  The support plate 12 is formed in a circular shape from a synthetic resin such as vinyl chloride, and has a diameter equal to the diameter of the holding surface of the chuck table 81 (for example, 200 mm). The thickness of the support plate 12 may be about 2 mm. The back surface of the dressing board 11 is fixed to the center of the front surface of the support plate 12 thus configured with an appropriate bonding agent.

In order to dress the grinding wheel 52 using the dressing tool 10 described above, the support plate 12 of the dressing tool 10 is sucked and held on the chuck table 81 of the grinding apparatus shown in FIG. If the dressing tool 10 is held on the chuck table 81, the chuck table moving means (not shown) is operated to move the chuck table 81 in the direction indicated by the arrow 81a and position it in the grinding zone 80b. Then, the outer peripheral edges of the plurality of grinding wheels 52 of the grinding wheel 5 are positioned so as to pass through the rotation center of the chuck table 81, that is, the center of the dressing tool 10. And the dressing operation | work of the grinding wheel 52 is implemented.

The dressing operation will be described with reference to FIGS. 4 and 5.
When the dressing board 11 is positioned in the grinding area 80b as described above, the plurality of grinding wheels 52 of the grinding wheel 5 constitute the rotation center P of the chuck table 81, that is, the dressing tool 10, as shown in FIGS. The positional relationship passes through the center of the dressing board 11. Next, the chuck table 81 is rotated at a rotational speed of, for example, 300 rpm in the direction indicated by the arrow 81c. Then, the dressing tool held on the chuck table 81, that is, the direction indicated by the arrow Z, that is, the wheel mount 44 to which the grinding wheel 5 to which the grinding wheel 52 is attached is rotated in the direction indicated by the arrow 44a at a rotational speed of 4500 rpm, for example. For example, it cuts and feeds toward 10 dressing boards 11 at a speed of 0.3 μm / second. As a result, the dressing board 11 and the grinding wheel 52 are ground together and the dressing is completed. According to the experiments by the present inventors, when the cutting feed amount of the dressing tool 10 is set to 150 μm, the dressing board 11 is ground by 15 μm, the grinding wheel 52 is ground by 117 μm, and the grinding stone 52 has moderately exposed abrasive grains. The vitrified bond grindstone has a stable grinding ability.

  In the dressing described above, since the dressing board 11 is formed of a silicon substrate, the dressing is more stable than the above-described dressing board made of a glass plate. That is, since the silicon substrate is not sticky and fragile as compared with the glass plate, the edge portion that forms the groove 111 appropriately grinds the grinding wheel 52, so that stable dressing is performed. The above-described dressing method is effective in a grindstone in which diamond abrasive grains having a particle diameter of 5 μm or less, particularly 1 μm, are bonded with a bonding agent, and the particle diameter is larger than 5 μm. A remarkable effect could not be confirmed in a grindstone composed of abrasive grains. Further, since the above-described dressing board 11 is formed of a silicon substrate, it can be manufactured by forming a groove in a silicon wafer generally used as a semiconductor wafer, so that it can be manufactured at low cost.

  In the embodiment described above, an example in which a vitrified bond grindstone is dressed as a grinding grindstone has been shown. However, the present invention can provide the same effect in dressing a resin bond grindstone or a metal bond grindstone. In the embodiment described above, the dressing board uses a circular silicon substrate, but the silicon substrate may have a shape other than a circle such as a square.

The perspective view of the grinding device for enforcing the dressing method of the grinding stone by the present invention. The perspective view of the grinding wheel with which the grinding apparatus shown in FIG. 1 is equipped. 1 is a perspective view of a dressing tool constructed in accordance with the present invention. The side view which shows the state which is implementing the dressing method of the grinding stone by this invention. The top view which shows the state which is implementing the dressing method of the grinding stone by this invention.

Explanation of symbols

2: Device housing 3: Grinding unit 31: Moving base 4: Spindle unit 41: Spindle housing 42: Rotating spindle 43: Servo motor 44: Wheel mount 5: Grinding wheel 51: Grinding wheel base 52: Grinding wheel 7: Grinding unit Feed mechanism 8: Chuck table mechanism 81: Chuck table 10: Dressing tool 11: Lessing board 111: Groove 12: Support plate

Claims (3)

A chuck table for holding a workpiece and a grinding means for grinding the workpiece held on the chuck table, the grinding means being rotatable and detachably attached to the wheel mount. In a grinding apparatus having a grinding wheel equipped with a grinding wheel for grinding a workpiece , diamond abrasive grains having a grain size of 5 μm or less are formed by bonding with vitrified bonds containing silicon dioxide as a main component and grinding. A grinding wheel dressing method for dressing a vitrified bond wheel having independent pores in a particle layer ,
A dressing board having grooves formed on the surface of a silicon substrate is held on the chuck table, and the vitrified bond grindstone is attached to the silicon substrate while rotating the chuck table and rotating the wheel mount on which the grinding wheel is mounted. Dressing the ground surface of the vitrified bond wheel in contact with the surface;
A grinding wheel dressing method characterized by the above. A grinding wheel dressing tool for dressing a vitrified bond grindstone which is formed by bonding diamond abrasive grains having a particle size of 5 μm or less with vitrified bond mainly composed of silicon dioxide and having independent pores in the abrasive grain layer. There,
It consists of a dressing board in which grooves are formed on the surface of a silicon substrate, and a support plate to which the dressing board is fixed with a bonding agent.
This is a grinding wheel dressing tool. The grinding wheel according to claim 2 , wherein the groove formed on the surface of the silicon substrate constituting the dressing board is composed of two grooves which are set to a width of 2 to 6 mm and are orthogonal to each other through the center of the silicon substrate. Dressing tools.

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