JP5187504B2 - Grinding equipment - Google Patents

Description

  The present invention relates to a grinding apparatus for grinding the back side of a substrate such as a semiconductor wafer.

In recent years, as the miniaturization of semiconductors becomes difficult, so-called “3D IC” and multi-layer package technologies have attracted attention in order to maintain the large capacity, high speed, and small size of chips. In the multi-layer package technology, in order to reduce the size of the package by thinning the stacked chips, the back side of the wafer is ground using a grinding device (see, for example, Patent Document 1), and the thickness of the wafer is 30 μm. Grinding technology to make it as thin as possible is important. As a grinding apparatus for performing such grinding processing, for example, as shown in FIG. 4, a grindstone 123 for grinding a wafer 5 'or a contact portion between the grindstone 123 and the wafer 5' for cooling or the like. A ring-shaped grindstone 123 having a diameter larger than that of the wafer 5 ′ is brought into contact with the back surface of the wafer 5 ′ rotated and held by a chuck (not shown) while rotating. Thus, there is a configuration in which the back side of the wafer 5 'is ground.
JP 2007-335458 A

  However, in the grinding apparatus as described above, at the edge portion of the wafer 5 ', the grindstone is in a direction (in the direction of arrow B in FIG. 4) substantially perpendicular to the circumferential direction of the wafer 5' (in the direction of arrow A in FIG. 4). 123 passes. For this reason, the so-called chipping in which the grindstone 123 is caught by one edge portion that receives the force from the grindstone 123 toward the radially inward direction of the wafer 5 ′ among the two edge portions of the wafer 5 ′ in contact with the grindstone 123. It tends to occur at one edge.

  The present invention has been made in view of such a problem, and an object thereof is to provide a grinding apparatus that prevents the occurrence of edge chipping.

In order to achieve such an object, a grinding apparatus according to the present invention includes a holding mechanism that is rotatable while holding a disk-shaped substrate, a head member that is provided so as to face the holding mechanism, and is rotatable, said substrate is held on the head member and a grinding possible ring-shaped grinding wheel, said grinding wheel which rotates, is held by the holding mechanism wherein the rotation about the central axis of the grinding wheel is held in said head member It is to contact with the substrate to rotate the center axis of the substrate as a rotation center, in the produced grinding apparatus to perform the grinding of the substrate, supplying a grinding fluid to the contact portion between the substrate and the grindstone The grinding fluid supply mechanism is configured to supply the grinding fluid from the center of the grinding wheel, and the outer diameter of the grinding stone is smaller than the diameter of the substrate as D. The whetstone When the width in the radial direction is W, the radius of the substrate and R, the distance between the center axis of the center shaft and the grinding wheel of the substrate is L, the following equation
D = R + W
{(R−W) / 2} <L <{(R + W) / 2}
When the above-mentioned condition is satisfied and the grindstone is brought into contact with the substrate, the grindstone is configured to come into contact with the center of rotation of the substrate.

  According to the present invention, the occurrence of edge chipping can be prevented.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. A schematic configuration of a grinding apparatus 1 to which the present invention is applied is shown in FIG. The grinding apparatus 1 includes a holding mechanism 10 that can hold and rotate a semiconductor wafer 5, a grinding unit 20 that is provided above and above the holding mechanism 10, and raises and lowers the grinding unit 20 relative to the wafer 5. The operation of the grinding unit moving mechanism 30 to be moved, the grinding water supply mechanism 40 for supplying the grinding water to the wafer 5, the holding mechanism 10, the grinding unit 20, the grinding unit moving mechanism 30, the grinding water supply mechanism 40, and the like are controlled. The control device 50 is mainly configured.

  As shown in FIG. 3, the wafer 5 is formed in a disk shape having a thickness of about 800 μm before processing, and is thinned to a predetermined thickness of, for example, 30 μm or less by grinding the back surface 5 b of the wafer 5. . A plurality of chip regions (not shown) are partitioned on the surface 5a of the wafer 5, and a predetermined electronic circuit is formed in each chip region. A protective tape 6 is affixed to the front surface 5a side of the wafer 5 subjected to back grinding for the purpose of protecting the electronic circuit. As the protective tape 6, for example, one having a configuration in which an adhesive is applied to one side of a polyethylene or polyolefin sheet is used.

  As shown in FIG. 1, the holding mechanism 10 includes a disk-shaped chuck 11, a spindle 12 extending vertically downward from the lower portion of the chuck 11, and a rotational driving force transmitted to the spindle 12 to rotate the chuck 11 in a horizontal plane. It has a chuck drive motor 13 and the like. The chuck 11 is formed in a disk shape with high flatness using a high-rigidity material such as ceramic, and holds the wafer 5 by suction so that the central axis O1 of the wafer 5 and the rotation axis of the chuck 11 coincide on the upper surface side. . Inside the chuck 11, a vacuum chuck structure that vacuum-sucks the surface 5 a of the wafer 5 to which the protective tape 6 is attached is provided so that the wafer 5 can be attached and detached, and the wafer that is sucked and held by the chuck 11. 5 is held in an upward horizontal posture.

  A grinding unit moving mechanism 30 is provided in the vicinity of the holding mechanism 10, and the grinding unit 20 is provided at the tip of an arm member 32 constituting the grinding unit moving mechanism 30. The grinding unit 20 includes a grindstone unit 21, a head member 25 to which the grindstone unit 21 is attached, a spindle 26 extending vertically upward from the upper portion of the head member 25, and a rotational driving force transmitted to the spindle 26 to transmit the head member 25 and the grindstone. It has a grindstone drive motor 27 that rotates the unit 21 in a horizontal plane.

  The grindstone unit 21 is composed of a disc-shaped base plate 22 and a ring-shaped grindstone 23 coupled to the base plate 22, and is attached to the lower surface side of the head member 25 so that the ground surface is held in a downward horizontal posture. The base plate 22 is formed in a disk shape using a stainless material or the like, and a hole 22 a for supplying the grinding water supplied from the grinding water supply mechanism 40 to the center side of the grindstone 23 is formed in the center of the base plate 22. It is formed so as to penetrate vertically.

  The grindstone 23 to be coupled to the base plate 22 has a base material formed in a ring shape having an outer diameter equivalent to that of the base plate 22 using stainless steel or the like, and diamond abrasive grains for grinding are fixed to the lower surface side. Form a ground surface. Inside the grindstone 23, a plurality of water escape holes 23a through which grinding water accumulated on the inner peripheral side of the grindstone 23 escapes to the outside are formed so as to penetrate in the radial direction. The outer diameter of the grindstone 23 is as follows when the outer diameter of the grindstone 23 is D, the radial width of the grindstone 23 is W (see also FIG. 2), and the radius of the wafer 5 is R. It is designed to satisfy the conditions expressed by the formula.

  R <D <{R + (2 × W)} (1)

  The head member 25 is formed in a disk shape having a diameter equivalent to that of the base plate 22 using a stainless material or the like, and holds the grindstone unit 21 on the lower surface side of the head member 25. The grindstone unit 21 attached to the base plate 22 is configured to be rotatable about the central axis O2 of the grindstone unit 21 (grindstone 23) using the spindle 26 and the grindstone drive motor 27 as the rotation center axis. Further, a hole 25a for supplying the grinding water supplied from the grinding water supply mechanism 40 to the center side of the grindstone 23 is formed in the center of the head member 25 so as to penetrate vertically.

  The grinding unit moving mechanism 30 horizontally moves the arm member 32 around a base 31 protruding upward from the processing table 39, an arm member 32 extending horizontally from the base 31, and a swinging shaft extending vertically through the base 31. An arm swinging mechanism 35 that swings and an arm lifting / lowering mechanism (not shown) that vertically moves the entire arm member 32 and the like are configured. The above-described grinding unit 20 is provided at the tip of the arm member 32. Yes. The grinding unit moving mechanism 30 is configured such that the holding mechanism 10 is positioned on the rocking locus of the grinding unit 20 when the arm member 32 is horizontally rocked by the arm rocking mechanism 35. The entire arm member 32 is moved up and down while facing the wafer 5 held by the chuck 11, and the grindstone 23 can be brought into contact with the back surface 5 b of the wafer 5. At this time, as shown in FIG. 2, the grindstone 23 is brought into contact with both the outer peripheral portion of the wafer 5 and the rotation center (center axis O1).

  The grinding water supply mechanism 40 shown in FIG. 1 uses a grinding water 41 (see FIG. 2) for cooling and lubrication of the wafer 5 or discharging grinding debris to each hole formed in the base plate 22 and the head member 25. The material is supplied onto the wafer 5 from the central axis O2 of the grindstone unit 21 (grindstone 23) through 22a and 25a. The control device 50 also includes a holding mechanism 10, a grinding unit 20, a grinding unit moving mechanism 30, and a control program that is preset and stored in the grinding device 1 and a machining program that is read according to the grinding object. The operation of the grinding water supply mechanism 40 and the like is controlled.

  In the polishing apparatus 1 configured as described above, in order to grind the wafer 5, the arm unit 32 is swung by the grinding unit moving mechanism 30 so that the grinding unit 20 is positioned facing the holding mechanism 10. The grindstone unit 21 is lowered to the grinding position while rotating the grindstone unit 21 and the chuck 11 together, and the lower surface (grinding surface) of the grindstone 23 is held by the chuck 11 and brought into contact with the back surface 5b of the rotating wafer 5. . At this time, as shown in FIG. 2, the grinding stone 23 is brought into contact with both the outer peripheral portion of the wafer 5 and the rotation center (center axis O <b> 1), and the grinding water 41 is used by using the grinding water supply mechanism 40. Is supplied to the contact portion between the wafer 5 and the grindstone 23 from the central axis O2 of the grindstone unit 21 (grindstone 23). At this time, the wafer 5 and the grindstone 23 are rotated in the same direction, and the speed of the outer peripheral portion of the wafer 5 is made lower than the speed of the grindstone 23 passing through the outer peripheral portion of the wafer 5. Thereby, the grinding process of the wafer 5 can be performed without rocking the grindstone 23.

  As described above, in the grinding apparatus 1 of the present embodiment, the grindstone 23 is designed so that the outer diameter of the grindstone 23 satisfies the condition expressed by the formula (1), and when the grindstone 23 is brought into contact with the wafer 5, the grindstone 23 contacts the outer periphery of the wafer 5 and the center of rotation (center axis O1). Therefore, since the grindstone 23 passes in a direction (in the direction of arrow D in FIG. 2) that follows the circumferential direction of the wafer 5 (in the direction of arrow C in FIG. 2) at the edge portion of the wafer 5, occurrence of edge chipping occurs. Can be prevented.

  On the other hand, when the outer diameter of the grindstone 23 is smaller than the radius of the wafer 5, for example, when the grindstone 23 is arranged so that the grindstone 23 comes into contact with the rotation center of the wafer 5, the grindstone 23 contacts the outer peripheral portion of the wafer 5. Therefore, unevenness of polishing occurs on the wafer 5. Further, when the outer diameter D of the grindstone 23 is larger than {R + (2 × W)} in the equation (1), the conventional chipping tends to occur at the edge portion of the wafer 5.

  For example, when the outer diameter of the grindstone 23 is designed under the condition of the expression (2) that satisfies the condition represented by the expression (1), the distance between the central axis O1 of the wafer 5 and the central axis O2 of the grindstone 23 is set. When the distance L satisfies the condition expressed by the expression (3), the grindstone 23 comes into contact with the outer peripheral portion of the wafer 5 and the rotation center (center axis O1).

D = (R + W) (2)
{(R−W) / 2} <L <{(R + W) / 2} (3)

  Moreover, in the grinding apparatus 1 of this embodiment, since the outer diameter of the grindstone 23 is smaller than the outer diameter of the wafer 5, the small-diameter grindstone can easily achieve flatness and suppress surface runout. Chipping and damage to the wafer 5 can be reduced. Further, since the outer diameter of the grindstone 23 is smaller than the outer diameter of the wafer 5, even if the outer diameter of the wafer 5 is increased from, for example, 300 mm to 450 mm, the grindstone does not become larger than the wafer, thereby minimizing the size of the apparatus. To the limit.

  At this time, it is preferable to rotate the wafer 5 and the grindstone 23 in the same direction. In this way, at the edge portion of the wafer 5, the grindstone 23 moves in a direction that follows the rotation direction of the edge portion. Since it passes, the occurrence of edge chipping can be effectively prevented.

  At this time, the speed of the outer peripheral portion of the wafer 5 is preferably lower than the speed of the grindstone 23 passing through the outer peripheral portion of the wafer 5, and in this way, at the edge portion of the wafer 5, Since the grindstone 23 passes in a direction that follows the rotation direction of the edge portion, the occurrence of edge chipping can be effectively prevented.

  At this time, the grinding water supply mechanism 40 is preferably used to supply the grinding water 41 from the central axis O2 of the grindstone unit 21 (grindstone 23) to the contact portion between the wafer 5 and the grindstone 23. In this way, since the grinding water 41 gradually spreads toward the contact portion between the wafer 5 and the grindstone 23 by the rotational centrifugal force, it is possible to avoid the grinding water from colliding with the edge portion of the wafer 5. The occurrence of edge chipping can be effectively prevented.

  In the above-described embodiment, the grinding unit 20 (grinding stone 23) is provided facing the upper side of the holding mechanism 10. However, the present invention is not limited to this, and the grinding unit (grinding stone) is located below the holding mechanism. The holding mechanism may be provided to face each other or may be provided to face the holding mechanism in the left-right direction.

  In the above-described embodiment, the substrate to be ground is not limited to the wafer 5, and the present invention can be applied even when the substrate is, for example, a glass substrate.

1 is a schematic view of a grinding apparatus according to the present invention. It is a top view of a wafer and a grindstone. It is a perspective view of a wafer. It is a top view of the wafer and grindstone in the conventional grinding device.

Explanation of symbols

1 Grinding device 5 Wafer (5a front surface, 5b back surface)
DESCRIPTION OF SYMBOLS 10 Holding mechanism 11 Chuck 20 Grinding unit 21 Grinding wheel unit 22 Base plate (22a hole) 23 Grinding wheel (23a Water escape hole)
25 Head member 40 Grinding water supply mechanism (grinding fluid supply mechanism)
O1 Wafer center axis O2 Grindstone center axis

Claims (4)

A holding mechanism capable of holding and rotating a disk-shaped substrate, a rotatable head member provided to face the holding mechanism, and a ring-shaped grindstone which is held by the head member and can grind the substrate with the door, the grinding wheel which rotates as the rotation around the central axis of the grinding wheel is held in said head member, is brought into contact with the substrate to rotated about the central axis of the substrate held by the holding mechanism it is, in the produced grinding apparatus to perform the grinding of the substrate,
A grinding fluid supply mechanism for supplying a grinding fluid to a contact portion between the substrate and the grindstone;
The grinding fluid supply mechanism is configured to supply the grinding fluid from the center of the grindstone,
The outer diameter of the grindstone smaller than the diameter of the substrate is D, the width in the radial direction of the grindstone is W, the radius of the substrate is R , and the distance between the central axis of the substrate and the central axis of the grindstone When the distance is L , the following formula
D = R + W
{(R−W) / 2} <L <{(R + W) / 2}
Satisfy the conditions of
A grinding apparatus, wherein the grindstone is configured to come into contact with a rotation center of the substrate when the grindstone is brought into contact with the substrate. The grinding apparatus according to claim 1 , wherein a relief hole penetrating in the radial direction of the grindstone is formed in the grindstone.   The grinding apparatus according to claim 1, wherein the substrate and the grindstone rotate in the same direction.   The speed of the outer peripheral part of the rotating substrate is lower than the speed of the grindstone that rotates and passes through the outer peripheral part of the substrate. The grinding apparatus as described.

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