JPH0768461A - Method and device for mirror finishing of wafer notch part - Google Patents

Abstract

PURPOSE:To realize the efficient mirror finishing of the inner end surface of a notch part by using a cylindrical buff, advancing a projecting circumferential part provided on the inner circumferential surface into the notch part to realize the buffing of the notch part and increase the contact length of the projecting circumferential part. CONSTITUTION:A holding part 22 and a wafer 25 are positioned at the prescribed positions in a buff 10 by elevating a movable block by a motor or the like. A movable arm 24 is turned by driving a cylinder device 43, and the wafer 25 is pressed against the inner circumferential surface of the buff 10 in an approximately perpendicular direction with the prescribed pressing force. A projecting circumferential part 20 of the inner circumferential surface of the buff 10 is advanced into a notch part 26 of the wafer 25, and positioning of each part is realized so that the projecting circumferential part may be abutted on the inner end surface in the notch part 26. Then, the buff 10 is rotated around the axial line, and the inner end surface of the notch part 26 is mirror finished by continuously or intermittently supplying the abrasive material from an abrasive material supplying mechanism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for mirror-polishing a notch portion of a semiconductor wafer.

[0002]

2. Description of the Related Art In the case of semiconductor wafers such as silicon, it is necessary to clarify the direction of the crystal axis in processing semiconductor chips. In order to indicate the direction of the crystal axis, an orientation flat (so-called orientation flat) is formed by cutting out a part of a circular wafer in the direction of the crystal axis, or a notch portion is formed by simply cutting out the peripheral edge of the wafer in a small V shape. I'm wondering. In recent years, the diameter of wafers has increased, and wafers having a diameter of 8 inches have appeared. In such a large-diameter wafer, the notch portion tends to be provided because the use of the orientation flat causes a large amount of wasteful portions to be discarded.

[0003]

The silicon wafer is
High-precision surface processing is required, and especially in the polishing process, even the generation of fine dust can greatly affect the processing quality.Therefore, the device itself is installed in equipment such as a dust-free room, Dustproof measures are taken. The wafer surface is lapped before polishing, but if the outer peripheral portion of the wafer is ground, dust and other substances are likely to adhere.If processed in this state, the attached dust may fall off, If the rough surface of is cut off, the processing quality will deteriorate. Therefore, it is required that the outer peripheral portion of the wafer be mirror-polished. Regarding the mirror polishing of the orientation flat portion, the technique disclosed in Japanese Patent Laid-Open No. 5-102111 is known. In the case where the notch portion is provided, since the notch portion is small as described above, there is not much influence of dust generation, and the notch portion was used without polishing. It also depends on the difficulty of polishing the small notch. However, since the semiconductor chips are becoming more highly integrated, even a small amount of dust has a great influence on the semiconductor chips, and the notch portion is also required to be mirror-polished.

The present invention has been made in order to meet the above-mentioned demand, and an object of the present invention is to provide a method and an apparatus capable of effectively mirror-polishing a notch portion.

[0005]

The present invention has the following constitution in order to achieve the above object. That is, using a cylindrical buff having an inner peripheral surface provided with a protruding peripheral portion, a semiconductor wafer having a notch portion formed on the peripheral edge is applied to the inner peripheral surface of the buff substantially at a right angle with the notched portion facing the protruding peripheral portion. In this case, the notch portion is brought into contact with the protruding portion, and the buff is rotated about the axis to polish the inner end surface of the notch portion to a mirror surface. The wafer is moved in parallel along the arc of the inner surface of the buff, or the wafer is rotated in the plane parallel to the rotating surface of the buff around the notch part while keeping the notch part in contact with the protruding part. It is preferable to do so. In the device of the present invention, the cylindrical peripheral buff is provided on the inner peripheral surface and is provided so as to be rotatable about the axis, the drive part for rotating the buff about the axis, and the notch part on the peripheral edge. The holding part for holding the semiconductor wafer formed with the buff and the holding part are relatively contacted and separated from each other, and the notch part of the wafer is applied to the inner peripheral surface of the buff substantially at a right angle. And a moving device for bringing the projecting peripheral portion into and abutting the notch portion. The moving device is
A rotation arm having the holding portion disposed on the distal end side, the rotation arm being rotatably supported by the support portion such that the holding portion is moved toward and away from the buff inner peripheral surface around the rotation axis, and the rotation arm. It is preferable that it is configured by a cylinder device that rotates the 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 parallel movement device that moves the support portion and translates the wafer held by the holding portion provided on the tip side of the rotating arm in parallel along the arc of the inner peripheral surface of the buff. Is. Alternatively, by rotating the support portion, the wafer held in the holding portion arranged on the tip side of the rotating arm is held in the buff around the notch portion while keeping the notch portion in contact with the protruding peripheral portion. It is preferable to provide a turning device for turning in a plane parallel to the plane of rotation. Further, it is preferable that the holding unit is provided with a turning mechanism for turning the wafer to be held about the axis within a range of the width of the notch. Alternatively, it is preferable that the buff is provided so as to be movable substantially in the direction of the width axis of the notch portion of the wafer. In addition to the moving device, the buff and the holding portion are relatively contacted and separated from each other in a direction substantially perpendicular to the inner peripheral surface of the buff, and the projecting peripheral portion is brought close to or in the notch portion of the wafer. By providing the contacting / separating device for changing the inner diameter of the projecting peripheral portion due to wear or the like, it is possible to suitably cope with the change.

[0006]

According to the method and apparatus of the present invention, a cylindrical buff is used, and the notch portion is ground by inserting the protruding peripheral portion provided around the inner peripheral surface thereof into the notch portion. The contact length of the protruding portion is increased, and the inner end surface of the notch portion can be efficiently mirror-polished. In addition, by moving the wafer in parallel or rotating it around the notch, the chamfered part of the inner end face of the notch can effectively abut the projecting peripheral part, and the chamfered part is also efficiently mirror-polished. As a result, the entire mirror surface can be surely polished. Further, by rotating the wafer by a small angle according to the width of the notch portion, the entire inner end surface can be mirror-polished even if the notch portion has a wide width.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Since the method of the present invention is in line with the apparatus of the present invention, an embodiment of the method invention will be described together with an embodiment of the apparatus invention. [First Embodiment] FIGS. 1 and 2 are a front view and a side view showing a first embodiment. 10 is a cylindrical buff,
For example, it is made of hard urethane foam mixed with abrasive grains such as silica. In addition, when polishing is performed while supplying the polishing material, the polishing can be effectively performed even by using a normal buff containing no abrasive grains. The buff 10 is fixed to the rotating plate 12 and is provided so as to be rotatable about its axis. Reference numeral 13 is a rotary shaft, 14 is a bearing, 15 is a coupling, and 16 is 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 which is supported on a machine base 18 so as to be vertically movable by an appropriate mechanism. 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. The movable block 19
Is provided 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 tubular buff due to wear of the buff 10. On the inner peripheral surface of the buff 10, a projecting peripheral portion 20 having a substantially triangular cross section is provided.

Reference numeral 22 denotes a holding portion, which is attached to the tip end side of the rotating arm 24. The holder 22 is a wafer 25
Is sucked and held so that the peripheral portion of the wafer 25 is exposed. Reference numeral 26 is a notch portion formed on the peripheral edge of the wafer 25. As shown in FIG. 3, the notch portion 26 has chamfered portions 26a formed on both edges thereof, and a central flat portion 2 is provided between the chamfered portions 26a.
It is 6b. A forward / reverse motor 27 is disposed on the rotating arm 24 and rotates the holding portion 22 in the forward / reverse direction 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. Further, the suction hole 33 is provided at the center of the suction plate 31.
Is opened, and the suction hole 33 is connected to the communication hole 34 and the joint 3
5, connected to a suction device (not shown) via a hose 36. Therefore, the wafer 25 can be suction-held by the suction plate 31, and the suction plate 31 can be normally and reversely rotated by the forward / reverse motor 27 while the wafer 25 is suction-held.
Therefore, the wafer 25 can be rotated in the normal and reverse directions within a very small angle range (approximately the width of the notch 26, the arrow Z direction in FIG. 1). The forward / reverse motor 27, the rotating shaft 30 and the like constitute an example of a turning device.

The rotating arm 24 is a support base (support portion) 4
No. 0 is provided so as to be rotatable in the left-right direction in FIG. Reference numeral 41 denotes its rotating shaft, which is rotatably supported by the bearing 42 of the support base 40. Reference numeral 43 denotes a cylinder device which is an example of pressing means, and is arranged on the support base 40.
The rod end is connected to the upper end side of the rotating arm 24, and the holding portion 22 arranged on the rotating arm 24 is rotated in the left-right direction in FIG. 1 to bring the wafer 25 into contact with the inner peripheral surface of the buff 10. When separated and rotated to the left, the wafer 25 held by the holder 22 can be pressed against the inner peripheral surface of the buff 10 with a predetermined pressing force. As the pressing means, a spring, a weight, or the like can be adopted in addition to the cylinder device. The rotating arm 24, the cylinder device 43, and the like constitute an example of a moving device. The support base 40 is guided by four guide poles 44 provided upright on the machine base 18, and is movable in a direction perpendicular to the plane of FIG. Four
Reference numeral 5 denotes a motor for the movement, which moves the support base 40 by rotating a threaded rod 46 screwed on the support base 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 parallel moving device. Further, 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 projecting portion 20 of the buff 10 is provided. Of course, simple water can also be supplied from this abrasive material supply section. When the wafer is polished by the buff containing the abrasive grains as in the present embodiment, by supplying water, the heat generated by the friction between the buff and the wafer can be cooled.

The present embodiment is constructed as described above.
FIG. 5 shows the principle of operation. In this embodiment, first, the holding unit 2
As described above, the wafer 25 is positioned and held by the step 2 so that the notch portion 26 faces a predetermined direction. Then, the movable block 19 is raised by a motor or the like (not shown) to move the movable block 19 to a predetermined position in the buff 10 and the holding portion 22 and the wafer 2.
Position 5. Here, the cylinder device 43 is driven to rotate the movable arm 24 to press the wafer 25 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 parts are set so that the protruding peripheral portion 20 on the inner peripheral surface of the buff 10 enters the notch portion 26 and contacts the inner end surface of the notch portion 26. Next, the buff 10 can be rotated about the axis, and the abrasive material can be continuously or intermittently supplied from the abrasive material supply mechanism to polish the inner end surface of the notch portion 26 to a mirror surface. In the present embodiment, the protruding peripheral portion 20 provided on the inner peripheral surface of the buff 10
Since the notch portion 26 is polished by the above, the contact length of the projecting peripheral portion 20 with the inner end surface of the notch portion 26 becomes long,
You can polish as efficiently as that. Further, even when the ridge line of the inner end face of the notch portion 26 is chamfered by using a material that elastically bends by a predetermined pressing force such as hard urethane foam as the material of the buff 10, the chamfering is performed. The protruding 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 move the support base 40 back and forth by a predetermined distance. As a result, the wafer 25 moves in parallel from the position B in FIG. 5 to the positions A and C on the left and right sides thereof. A,
At the C position, the protruding portion 20 obliquely abuts on the wafer 25,
Therefore, the projecting peripheral portion 20 effectively contacts 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 in position A, the buff 10
It is preferable to change the rotation direction to the X direction in FIG. 5 and to the Y direction in FIG. 5 when the wafer 25 is at the C position. By setting the rotation direction of the buff 10 in this way, 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, the wafer 25 is not subjected to an excessive force, and the wafer 25 is damaged. Can be prevented. Notch 2
When the width of 6 is wide, the forward / reverse motor 27 is driven to rotate the suction plate 31 of the holding portion 22 in the direction of the arrow Z in the minute angle range, so that the entire inner end surface of the notch portion 26 is wide even if the width of the notch portion 26 is wide. Can be polished. Alternatively, the buff 10 may be moved up and down slightly by about the width of the notch portion 26.

[Second Embodiment] FIGS. 6 and 7 are a front view and a side view showing a second embodiment. The same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the support base 40 is rotated around a rotation shaft 50 supported by a bearing 51. Rotating shaft 5 in this case
The rotation center of 0 is the wafer 25 held by the holding unit 22.
Through the notch 26 of the. As a result, the wafer 25 is rotated about the notch portion 26 in a plane parallel to the rotation surface of the buff 10. Reference numeral 52 is a coupling, and 53 is a motor for rotating the support base 40. The bearing 51 and the motor 53 are supported by the machine base 18, whereby the support base 40,
Members such as the rotating arm 24 are supported by the machine base 18. An example of a turning device is configured by the support base 40, the turning shaft 50, and the like.

FIG. 8 shows the principle of operation of the second embodiment.
In this embodiment, the motor 53 is driven to reciprocally rotate the support base 40 for uniform mirror polishing 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 about the notch portion 26 in the plane parallel to the rotation surface of the buff 10 between the positions A, B and C in FIG. It As a result, at the A and C positions, the projecting peripheral portion 20 obliquely contacts the wafer 25, and therefore the projecting peripheral portion 20 effectively contacts 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, like the first embodiment, when the wafer 25 is in the A position, the buff 10 is in the X direction of FIG. 5 and the wafer 25 is in the C position. It is preferable to change the rotation direction to the Y direction in FIG.
By setting the rotation direction of the buff 10 in this way,
The force applied to the wafer 25 from the protruding 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 wide, 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 of FIG. Thereby, even if the width of the notch portion 26 is wide, the entire inner end surface of the notch portion 26 can be ground.

Next, referring to FIG. 7, a vertical moving device and a horizontal moving device which are moving devices for the buff 10 will be described.
Reference numeral 54 denotes a horizontal moving block, on the front surface of which the bearing 14 and the drive motor 16 are fixed, and on the back surface thereof, a horizontal moving body 55.
Is fixed, and is guided by a linear guide 56 arranged in the horizontal direction so as to be reciprocally movable in a direction (horizontal direction) orthogonal to the paper surface of FIG. That is, the horizontal moving body 55 is slidably fitted to the linear guide 56 arranged 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. Also, 58 is a vertical movement block,
A linear guide 56 is fixed to the front surface, and a vertical moving body 59 is fixed to the rear surface, and is guided by a linear guide 60 arranged in the vertical direction so as to be reciprocally movable in the vertical direction. The drive devices for the horizontal movement block 54 and the vertical movement block 58 each have a ball screw 62 and a drive motor 64 as constituent elements. Taking the drive device for the up-and-down moving block 58 as an example, as shown in FIG. 7, a ball screw 62 is rotatably arranged on the machine base 18 along a linear guide 60, and is screwed into the ball screw 62. The portion 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.

In this way, the horizontal moving block 54 is guided movably in the horizontal direction, and the driving device constitutes the horizontal moving device, and the vertical moving block 58 is guided movably in the vertical direction. The drive unit constitutes a vertical movement unit. Then, the horizontal movement device holds the buff 10 in a direction substantially perpendicular to the inner peripheral surface of the buff.
The contact / separation device operates so as to bring the projecting peripheral portion 20 closer to or into the notch portion 26 of the wafer. Therefore, according to the horizontal motion device, the protruding portion 20 can be appropriately brought close to the notch portion 26 when the protruding portion 20 is worn and the inner diameter thereof is increased. That is, according to the horizontal movement device, the movable arm 24 is rotated to a suitable state immediately before the notch portion 26 is pressed against the projecting peripheral portion 20,
The wafer 10 can be moved. In addition, the inner diameter of the projecting portion 20 is set in order to reproduce the worn projecting portion 20.
It also changes when the shape is adjusted by cutting with a cutting tool. Such a change in the inner diameter of the protruding portion 20 can be dealt with by the horizontal moving device. Buff 1 explained above
The vertical moving device and the horizontal moving device, which are the moving devices of 0, can be applied to the embodiment of FIG. Also, the moving device is a buff 10.
It suffices that the holding part 22 and the holding part 22 can be relatively brought into contact with and separated from each other. Therefore, the holding part 2 is not limited to the one that moves the buff 10 side as in the above-mentioned embodiment, and the holding part 2 is opposite to the above-mentioned embodiment.
It may be a moving device that moves the second side.

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 embodiment, and for example, the vertical arrangement relationship of the buff 10 and the rotating arm 24 is not limited to the above. Further, it is preferable that a plurality of protrusions are provided in advance on the inner peripheral surface of the buff, and polishing is performed by using another protrusion having one protrusion worn. In the tubular buff 10 in the drawings, the entire tubular body is 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 projecting portion 20. It suffices if the buff material is formed in a tubular shape around the portion where is formed.

[0016]

According to the method and apparatus of the present invention, a cylindrical buff is used, and the notch portion is ground by inserting the protruding peripheral portion provided on the inner peripheral surface thereof into the notch portion. Therefore, the contact length of the projecting peripheral portion becomes long, and the inner end surface of the notch portion can be efficiently mirror-polished. Also, by translating the wafer or rotating the wafer around the notch, the projecting peripheral portion can be effectively brought into contact with the chamfered portion of the inner end surface of the notch,
The chamfered portion can also be efficiently mirror-polished, and the entire mirror-polished can be reliably performed. Further, by rotating the wafer by a small angle according to the width of the notch portion, the entire inner end surface can be mirror-polished even if the notch portion has a wide width.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment.

FIG. 2 is a side view of the first embodiment.

FIG. 3 is a cross-sectional explanatory view of a notch portion.

FIG. 4 is a cross-sectional explanatory view showing an example of a wafer holder.

FIG. 5 is an explanatory diagram showing the operating 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 operating principle of the second embodiment.

[Explanation of symbols]

 10 buff 16 drive motor (driving part) 20 projecting part 22 holding part 24 rotating arm 25 wafer 26 notch part 27 forward / reverse motor 40 support base 41 rotating shaft 43 cylinder device 45 motor 50 rotating shaft

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yuuo Nakamura 1650 Kiyono, Matsushiro-cho, Nagano City, Nagano Prefecture Fujikoshi Machine Industry Co., Ltd. Within

Claims (10)

[Claims] 1. A cylindrical buff having an inner peripheral surface around which a protruding peripheral portion is provided, and a semiconductor wafer having a notch portion formed on the peripheral edge is formed on the inner peripheral surface of the buff with the notch portion facing the protruding peripheral portion. A mirror-polishing method for a wafer notch part, which comprises applying a right angle, entering the abutting part into the notch part, and bringing the abutting part into contact with the notch part, and rotating the buff about an axis to polish the inner end face of the notch part to a mirror surface. . 2. The method for mirror-polishing a notch of a wafer according to claim 1, wherein the wafer is moved in parallel along the arc of the inner peripheral surface of the buff. 3. The wafer notch according to claim 1, wherein the wafer is rotated in a plane parallel to the rotation surface of the buff about the notch portion while keeping the notch portion in contact with the protruding peripheral portion. Method of mirror polishing of parts. 4. A cylindrical buff having an inner peripheral surface around which a projecting peripheral portion is provided so as to be rotatable about an axis, a drive unit for rotating the buff about the axis, and a notch portion on the peripheral edge. And a holding portion for holding the semiconductor wafer having the formed buff, the buff and the holding portion are relatively contacted and separated from each other, and the notch portion of the wafer is applied to the inner peripheral surface of the buff substantially at a right angle. A mirror polishing device for a notch portion of a wafer, comprising: a moving device that moves the projecting peripheral portion into and comes into contact with the notch portion. 5. The moving device is provided with the holding portion at a tip side thereof, and is supported by a supporting portion so as to be rotatable about a rotation shaft so that the holding portion comes in contact with and separates from a buff inner peripheral surface. And a 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. Item 4. A mirror polishing device for a wafer notch according to item 4. 6. A translation device for moving the support portion to translate a wafer held by a holding portion arranged on the tip side of the rotating arm along an arc of an inner peripheral surface of the buff. The mirror-polishing device for a wafer notch according to claim 5, which is provided. 7. The wafer is held by a holding portion arranged on the tip side of the turning arm by rotating the supporting portion, and the wafer is centered on the notch portion while keeping the notch portion in contact with the protruding peripheral portion. 6. The mirror polishing device for a wafer notch portion according to claim 5, further comprising a rotating device for rotating the buff in a plane parallel to a rotation surface of the buff. 8. The holding unit includes a rotating mechanism for rotating the wafer to be held about an axis within a width of the notch portion. A mirror-polishing device for the wafer notch portion described. 9. The mirror-polishing device for a wafer notch portion according to claim 4, wherein the buff is provided so as to be movable substantially in the axial direction of the width direction of the notch portion of the wafer. 10. In addition to the moving device, the buff and the holding portion are relatively contacted and separated from each other in a direction substantially perpendicular to the inner peripheral surface of the buff, and the protruding peripheral portion is formed in the notch portion of the wafer. 10. The mirror polishing device for a wafer notch portion according to claim 5, 6, 7, 8 or 9, further comprising a contacting / separating device for approaching or advancing.