JP3584058B2 - Wafer notch mirror polishing method and apparatus - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method and an apparatus for mirror polishing a notch portion of a semiconductor wafer.
[0002]
[Prior art]
In processing a semiconductor chip of a semiconductor wafer such as silicon, it is necessary to clarify the direction of the crystal axis.
In order to indicate the direction of the crystal axis, an orientation flat (a so-called orientation flat) is formed by cutting a part of the circular wafer in the direction of the crystal axis, or a notch is formed by simply cutting the periphery of the wafer into a small V-shape. I do
In recent years, wafers have increased in diameter, and wafers having a diameter of 8 inches have appeared. In such a large-diameter wafer, the provision of the orientation flat increases the useless portion to be discarded, and thus tends to provide the notch.
[0003]
[Problems to be solved by the invention]
Silicon wafers require high-precision surface processing, and even in the case of polishing, even the generation of fine dust greatly affects the processing quality. Therefore, the equipment itself is installed in equipment such as a dust-free room. And various dustproof measures are taken.
Lapping is performed on the wafer surface before polishing.However, if the outer peripheral portion of the wafer is ground, dust and the like easily adhere to the wafer. The rough surface may be chipped, resulting in poor processing quality.
Therefore, it is required that the outer peripheral portion of the wafer be mirror-polished.
With respect to mirror polishing of the orientation flat, a technique disclosed in Japanese Patent Application Laid-Open No. 5-102111 is known.
In the case where the notch portion is provided, the notch portion is small as described above, so that the notch portion is not greatly affected by dust generation and used without polishing. It also depends on the difficulty in polishing small notches.
However, since semiconductor chips are becoming more and more highly integrated, even small dust particles have a greater effect, and the notch portion must be mirror-polished.
[0004]
SUMMARY OF THE INVENTION The present invention has been made to meet the above-mentioned demands, and an object of the present invention is to provide a method and an apparatus capable of effectively mirror-polishing a notch portion.
[0005]
[Means for Solving the Problems]
The present invention has the following configuration to achieve the above object.
That is, a cylindrical buff having a protruding peripheral portion provided on the inner peripheral surface is used, and a semiconductor wafer having a notch formed on the peripheral edge is applied to the buff inner peripheral surface at a substantially right angle with the notch directed toward the protruding peripheral portion. In this case, the protruding peripheral portion enters and contacts the notch portion, and the inner end surface of the notch portion is polished to a mirror surface by rotating the buff about an axis. Move the wafer in parallel along the arc on the inner peripheral surface of the buff, or rotate the wafer around the notch while keeping the notch in contact with the protruding peripheral surface in a plane parallel to the buff rotation surface It is preferable to make it.
In the device of the present invention, a protruding peripheral portion is provided on the inner peripheral surface, and a cylindrical buff provided rotatably about an axis, a driving unit for rotating the buff about the axis, and a notch on the periphery. A holding portion for holding a semiconductor wafer having formed thereon, the buff and the holding portion are relatively moved toward and away from each other, and a notch portion of the wafer is applied to the protruding peripheral portion at a substantially right angle to an inner peripheral surface of the buff. , A moving device for causing the projecting peripheral portion to enter and contact the notch portion.
The moving device has a pivot arm in which the holding portion is disposed on a distal end side, and the holding portion is rotatably supported on a support portion such that the holding portion is rotatable toward and away from the buff inner peripheral surface about a rotation axis. And a cylinder device for rotating the rotating arm to press the wafer held by the holding portion against the inner peripheral surface of the buff with a predetermined pressing force.
Further, it is preferable to provide a translation device that moves the support portion and translates the wafer held by the holding portion disposed on the distal end side of the rotating arm along an arc on the inner peripheral surface of the buff. It is.
Alternatively, the wafer held by the holding portion disposed on the tip side of the rotating arm by rotating the support portion may be buffed around the notch portion while keeping the notch portion in contact with the projecting peripheral portion. It is preferable to provide a rotation device for rotating in a plane parallel to the rotation surface.
Further, it is preferable that the holding section is provided with a rotating mechanism for rotating the wafer to be held around an axis within a range of the width of the notch.
Alternatively, it is preferable to provide the buff so as to be movable in the axial direction substantially by the width of the notch portion of the wafer.
Further, in addition to the moving device, the buff and the holding portion are relatively moved toward and away from each other in a direction substantially perpendicular to the inner peripheral surface of the buff, and the protruding peripheral portion approaches or enters the notch portion of the wafer. By providing the contacting / separating device, the change in the inner diameter of the protruding peripheral portion due to wear or the like can be suitably dealt with.
[0006]
[Action]
According to the method and the apparatus of the present invention, a cylindrical buff is used, and a protruding peripheral portion provided on the inner peripheral surface of the buff is made to enter the notch portion to polish the notch portion. The contact length becomes longer, and the inner end face of the notch can be efficiently mirror-polished.
In addition, by moving the wafer in parallel or rotating it around the notch, the protruding part can be effectively brought into contact with the chamfer on the inner end face of the notch, and the chamfer can also be efficiently mirror-polished. The result is that the entire surface is polished.
Furthermore, by rotating the wafer by a small angle according to the width of the notch, the entire inner end face can be mirror-polished even with a wide notch.
[0007]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Since the method of the present invention is the same as the device of the present invention, the embodiment of the method invention will be described together with the embodiment of the device invention.
[First embodiment]
1 and 2 are a front view and a side view showing a first embodiment.
Reference numeral 10 denotes a cylindrical buff, which is made of, for example, hard urethane foam mixed with abrasive grains such as silica. In the case where polishing is performed while supplying an abrasive, the polishing can be effectively performed even when a normal buff containing no abrasive grains is used.
The buff 10 is fixed to the rotating plate 12 and is provided to be rotatable about an axis. Reference numeral 13 denotes a rotating shaft, 14 denotes a bearing, 15 denotes a coupling, and 16 denotes a drive motor (drive unit).
As shown in FIG. 2, the bearing 14 and the drive motor 16 are mounted on a movable block 19 supported on a machine base 18 by a suitable mechanism so as to be vertically movable. Therefore, when the movable block 19 moves up and down, the buff 10 also moves up and down in the axial direction with a predetermined stroke. By providing the movable block 19 so as to be movable in the left-right direction in FIG. 1, it is possible to suitably cope with a change in the inner diameter of the cylindrical buff due to wear of the buff 10 or the like.
On the inner peripheral surface of the buff 10, a protruding peripheral portion 20 having a substantially triangular cross section is provided.
[0008]
Reference numeral 22 denotes a holding unit, which is attached to the tip end of the rotating arm 24.
The holding unit 22 sucks the wafer 25 and holds the wafer 25 so that the peripheral edge of the wafer 25 is exposed. Reference numeral 26 denotes a notch formed on the periphery of the wafer 25.
As shown in FIG. 3, the notch portion 26 has chamfered portions 26a formed at both edges, and a central flat portion 26b is formed between the two chamfered portions 26a.
Reference numeral 27 denotes a forward / reverse motor, which is disposed on the rotation arm 24, and rotates the holding unit 22 forward / reverse while sucking the wafer 25.
FIG. 4 shows an example of a specific example of the holding unit 22 and its rotating mechanism.
That is, the rotating shaft 30 is connected to the output shaft 28 of the forward / reverse motor 27 via the belt 29, and the suction plate 31 is fixed to the tip of the rotating shaft 30. A ring-shaped seal 32 is attached to the surface of the suction plate 31. In addition, a suction hole 33 is opened at the center of the suction plate 31, and the suction hole 33 is connected to a suction device (not shown) via a communication hole 34, a joint 35, and a hose 36.
Therefore, the wafer 25 can be suction-held by the suction plate 31, and the suction plate 31 is rotated forward and reverse by the forward / reverse motor 27 while holding the wafer 25 by suction. 26 (in the direction of arrow Z in FIG. 1).
An example of a rotating device is constituted by the forward / reverse motor 27, the rotating shaft 30, and the like.
[0009]
The rotating arm 24 is provided on a support base (supporting portion) 40 at a halfway portion thereof so as to be rotatable in the left-right direction in FIG.
A rotation shaft 41 is rotatably supported on a bearing 42 of the support base 40. Reference numeral 43 denotes a cylinder device which is an example of a pressing unit, which is disposed on the support base 40, the rod end of which is connected to the upper end side of the rotating arm 24, and the holding unit 22 which is disposed on the rotating arm 24. The wafer 25 is rotated to the left and right in FIG. 1 to contact and separate the inner peripheral surface of the buff 10, and when rotated to the left, the wafer 25 held by the holder 22 is buffed with a predetermined pressing force. 10 can be pressed against the inner peripheral surface. As the pressing means, a spring, a weight, or the like can be employed in addition to the cylinder device.
An example of the moving device is constituted by the rotating arm 24, the cylinder device 43, and the like.
The support base 40 is guided by four guide poles 44 erected on the machine base 18 so as to be movable in a direction perpendicular to the upper surface of FIG. 1 and in a horizontal direction in FIG. Reference numeral 45 denotes a motor for moving the support table 40 by rotating a screw rod 46 screwed to the support table via a belt 47.
The support base 40, the guide pole 44, the motor 45, the screw rod 46, and the like constitute an example of a translation device.
In addition, although not shown, a known abrasive supply unit for supplying an abrasive (a liquid abrasive mixed with a slurry or the like) to the vicinity of the protruding peripheral portion 20 of the buff 10 is provided. It is a matter of course that mere water can be supplied from the abrasive supply section. When the wafer is polished by the buff into which the abrasive grains are mixed as in this embodiment, by supplying water, heat generated by friction between the buff and the wafer can be cooled.
[0010]
This embodiment is configured as described above.
FIG. 5 shows an operation principle diagram.
In this embodiment, first, as described above, the wafer 25 is positioned and held by the holding unit 22 so that the notch portion 26 faces a predetermined direction.
Next, the movable block 19 is raised by a motor (not shown) or the like, and the holding unit 22 and the wafer 25 are positioned at predetermined positions in the buff 10.
Here, the cylinder device 43 is driven to rotate the movable arm 24, and the wafer 25 is pressed against the inner peripheral surface of the buff 10 at a substantially right angle with a predetermined pressing force. At this time, the positions of the respective portions are set so that the projecting peripheral portion 20 on the inner peripheral surface of the buff 10 enters the notch portion 26 and comes into contact with the inner end surface of the notch portion 26.
Next, the buff 10 is rotated about the axis, and the abrasive is continuously or intermittently supplied from the abrasive supply mechanism so that the inner end surface of the notch 26 can be polished to a mirror surface.
In this embodiment, the notch 26 is polished by the protrusion 20 provided on the inner peripheral surface of the buff 10, so that the contact length of the protrusion 20 to the inner end surface of the notch 26 becomes longer, and the efficiency is accordingly increased. Polishing can be done well.
Further, by using a material which is elastically deformed by a predetermined pressing force such as hard urethane foam as a material of the buff 10, even when the ridgeline of the inner end face of the notch portion 26 is chamfered, the chamfering is performed. The projecting peripheral portion 20 can be brought into contact with the portion 26a, and the entire inner end surface of the notch portion 26 can be mirror-polished.
In order to further uniformly polish the entire inner end surface of the notch portion 26, the moving motor 45 is driven to reciprocate the support table 40 by a predetermined distance. As a result, the wafer 25 moves in parallel from the position B in FIG.
At the positions A and C, the projecting peripheral portion 20 abuts on the wafer 25 obliquely, so that the projecting peripheral portion 20 abuts on the chamfered portion 26a of the notch portion 26, and the chamfered portion 26a can be polished efficiently.
In this case, the rotation direction of the buff 10 can be appropriately selected. Preferably, when the wafer 25 is at the position A, the buff 10 is moved in the X direction of FIG. It is preferable to change the rotation direction in the Y direction. By setting the rotation direction of the buff 10 in this manner, the force applied to the wafer 25 from the projecting peripheral portion 20 of the buff 10 acts in the direction in which the force escapes, and no excessive force is applied to the wafer 25, and the wafer 25 is damaged. Can be prevented.
When the width of the notch 26 is wide, the forward / reverse motor 27 is driven to rotate the suction plate 31 of the holding unit 22 in the direction of the arrow Z in a small angle range. The entire inner end surface can be polished.
Alternatively, the buff 10 may be slightly moved up and down by about the width of the notch 26.
[0011]
[Second embodiment]
6 and 7 are a front view and a side view showing the second embodiment. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
In the present embodiment, the support base 40 is rotated about a rotation shaft 50 supported by a bearing 51. In this case, the center of rotation of the rotation shaft 50 passes through the notch 26 of the wafer 25 held by the holder 22. Thus, the wafer 25 is rotated about the notch 26 in a plane parallel to the rotation plane of the buff 10.
52 is a coupling, and 53 is a motor for rotating the support 40. The bearing 51 and the motor 53 are supported by the machine base 18, whereby members such as the support base 40 and the rotating arm 24 are supported by the machine base 18.
An example of a rotation device is configured by the support table 40, the rotation shaft 50, and the like.
[0012]
FIG. 8 shows an operation principle diagram of the second embodiment.
In this embodiment, the motor 53 is driven to reciprocate the support table 40 when mirror polishing is performed uniformly to the chamfered portion 26a on the inner end surface of the notch portion 26. As a result, as shown in FIG. 8, the wafer 25 is rotated around the notch 26 in a plane parallel to the rotation plane of the buff 10 between the positions A, B and C in FIG. You.
As a result, at the positions A and C, the projecting peripheral portion 20 abuts the wafer 25 at an angle, and therefore the projecting peripheral portion 20 effectively abuts the chamfered portion 26a of the notch portion 26, and the chamfered portion 26a is efficiently polished. it can.
In this case, the rotation direction of the buff 10 can be appropriately selected, but preferably, as in the first embodiment, when the wafer 25 is in the A position, the buff 10 is moved in the X direction in FIG. It is preferable to change the rotation direction in the Y direction in FIG. By setting the rotation direction of the buff 10 in this manner, the force applied to the wafer 25 from the projecting peripheral portion 20 of the buff 10 acts in the direction in which the force escapes, and damage to the wafer 25 can be prevented.
Similarly, when the width of the notch portion 26 is large, the forward / reverse motor 27 is driven to rotate the suction plate 31 of the holding portion 22 within a minute angle range, thereby rotating the wafer 25 in the arrow Z direction in FIG. Accordingly, the entire inner end face of the notch 26 can be polished even if the width of the notch 26 is wide.
[0013]
Next, a vertical moving device and a horizontal moving device that are moving devices of the buff 10 will be described with reference to FIG.
Numeral 54 denotes a horizontal motion block, on which the bearing 14 and the drive motor 16 are fixed on the front surface, and the horizontal moving body 55 is fixed on the rear surface. It is guided so as to be able to reciprocate in a direction (horizontal direction) perpendicular to the direction. That is, the horizontal moving body 55 is slidably fitted on the linear guide 56 disposed in the horizontal direction, and the horizontal moving block 54 reciprocates in the horizontal direction along the linear guide 56 via the horizontal moving body 55. Can move.
Reference numeral 58 denotes a vertical movement block, in which a linear guide 56 is fixed on the front surface and a vertical moving body 59 is fixed on the back surface, and is guided by a linear guide 60 arranged in the vertical direction so as to be reciprocally movable in the vertical direction. Have been.
The drive devices of the horizontal movement block 54 and the vertical movement block 58 each include a ball screw 62 and a drive motor 64 as constituent elements. Taking a driving device of the vertical movement block 58 as an example, as shown in FIG. 7, a ball screw 62 is rotatably disposed on the machine base 18 along a linear guide 60, and is screwed into the ball screw 62. The part 66 is fixed to the vertical movement block 58. A coupling 68 connects the output shaft of the drive motor 64 and the ball screw 62.
[0014]
In this manner, the horizontal moving device is constituted by the structure for guiding the horizontal moving block 54 so as to be movable in the horizontal direction and the driving device. The structure for guiding the vertically moving block 58 so as to be movable in the vertical direction and the driving device. A vertical movement device is configured.
Then, the horizontal movement device moves the buff 10 toward and away from the holding portion 22 in a direction substantially perpendicular to the buff inner peripheral surface, and moves the protruding peripheral portion 20 closer to or into the notch portion 26 of the wafer. Acts as a moving device. For this reason, according to the horizontal motion device, the protruding peripheral portion 20 can be appropriately brought close to the notch portion 26 when the inner diameter of the protruding peripheral portion 20 is increased due to wear. That is, according to the horizontal movement device, the wafer 10 can be moved to a suitable state immediately before the movable arm 24 is rotated to press the notch portion 26 against the protruding peripheral portion 20. The inner diameter of the protruding peripheral portion 20 also changes when the shape of the protruding peripheral portion 20 is adjusted by cutting with a cutting tool in order to regenerate the worn protruding peripheral portion 20. The horizontal movement device can cope with such a change in the inner diameter of the protruding peripheral portion 20.
The vertical moving device and the horizontal moving device which are the moving devices of the buff 10 described above can also be applied to the embodiment of FIG. Further, since the moving device only needs to be able to relatively move the buff 10 and the holding portion 22 relatively to each other, the moving device is not limited to the device that moves the buff 10 side as in the above-described embodiment. Conversely, a moving device that moves the holding unit 22 side may be used.
[0015]
Although the preferred embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the above-described embodiment. For example, the vertical arrangement of the buff 10 and the rotating arm 24 is not limited to the above.
Further, it is preferable that a plurality of protruding peripheral portions are provided in advance on the inner peripheral surface of the buff, and polishing is performed using another protruding peripheral portion where one protruding peripheral portion is worn.
Further, the cylindrical buff 10 in the drawing has the entire cylindrical body integrally formed of a buff material such as hard foam urethane, but the shape of the buff 10 is not limited to this, and at least the protruding portion 20 What is necessary is just to form in the shape of a cylinder with a buff material centering on the part in which is formed.
[0016]
【The invention's effect】
According to the method and the apparatus of the present invention, a cylindrical buff is used, and a protruding peripheral portion provided on the inner peripheral surface of the buff is made to enter the notch portion to polish the notch portion. The contact length becomes longer, and the inner end face of the notch can be efficiently mirror-polished.
In addition, by moving the wafer in parallel or rotating it around the notch, the protruding part can be effectively brought into contact with the chamfer on the inner end face of the notch, and the chamfer can also be efficiently mirror-polished. The result is that the entire surface is polished.
Furthermore, by rotating the wafer by a small angle according to the width of the notch, the entire inner end face can be mirror-polished even with a wide notch.
[Brief description of the drawings]
FIG. 1 is a front view showing a first embodiment.
FIG. 2 is a side view of the first embodiment.
FIG. 3 is an explanatory sectional view of a notch portion.
FIG. 4 is an explanatory sectional view showing an embodiment of a wafer holding unit.
FIG. 5 is an explanatory diagram showing an operation principle of the first embodiment.
FIG. 6 is a front view showing a second embodiment.
FIG. 7 is a side view of the second embodiment.
FIG. 8 is an explanatory diagram showing the operation principle of the second embodiment.
[Explanation of symbols]
10 Buff 16 Drive motor (drive unit)
Reference Signs List 20 Projecting peripheral portion 22 Holding portion 24 Rotating arm 25 Wafer 26 Notch portion 27 Forward / reverse motor 40 Support base 41 Rotating shaft 43 Cylinder device 45 Motor 50 Rotating shaft

Claims (10)

Using a cylindrical buff provided with a protruding portion on the inner peripheral surface, a semiconductor wafer having a notch formed on the peripheral edge is applied substantially perpendicular to the buff inner peripheral surface with the notch facing the protruding peripheral portion, A mirror polishing method for a wafer notch portion, wherein the protruding peripheral portion enters and contacts the notch portion, and the buff is rotated about an axis to polish the inner end surface of the notch portion to a mirror surface. 2. The method of claim 1, wherein the wafer is moved in parallel along an arc on the inner peripheral surface of the buff. 2. A mirror polishing method for a wafer notch according to claim 1, wherein the wafer is rotated around the notch in a plane parallel to the rotation surface of the buff while keeping the notch in contact with the projecting peripheral portion. . A cylindrical buff provided with a protruding peripheral portion on the inner peripheral surface and rotatably provided about an axis;
A drive unit for rotating the buff about an axis,
A holding portion for holding a semiconductor wafer having a notch formed on the periphery,
The buff and the holding part are relatively moved toward and away from each other, and the notch part of the wafer is applied to the protruding part at a substantially right angle to the inner peripheral surface of the buff, and the protruding part enters the notch part, and A mirror device for polishing a wafer notch portion, comprising: The moving device has a pivot arm in which the holding portion is disposed on a distal end side, and the holding portion is rotatably supported on a support portion such that the holding portion is rotatable toward and away from the buff inner peripheral surface about a rotation axis. 5. The wafer according to claim 4, further comprising: pressing means for rotating the rotating arm to press the wafer held by the holding portion against the inner peripheral surface of the buff with a predetermined pressing force. Mirror polishing equipment at the notch. A translation device is provided that moves the support portion and translates the wafer held by the holding portion disposed on the distal end side of the rotating arm along an arc on the inner peripheral surface of the buff. 6. The mirror polishing apparatus according to claim 5, wherein: By rotating the supporting portion, the wafer held by the holding portion disposed on the tip side of the rotating arm is rotated around the notch portion while keeping the notch portion in contact with the projecting peripheral portion. 6. The mirror polishing apparatus for a wafer notch according to claim 5, further comprising a turning device for turning in a plane parallel to the wafer. 8. The wafer notch portion according to claim 4, wherein the holding portion includes a rotating mechanism for rotating the held wafer around an axis within a range of a width of the notch portion. Mirror polishing equipment. 8. The apparatus according to claim 4, wherein the buff is provided so as to be movable in the axial direction substantially by the width of the notch of the wafer. In addition to the moving device, in a direction substantially perpendicular to the inner peripheral surface of the buff, the buff and the holding portion are relatively moved toward and away from each other, and the protruding peripheral portion approaches or enters the notch portion of the wafer. 10. The mirror polishing apparatus according to claim 5, further comprising a separating device.

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