JP2005038982A - Outer periphery polishing device for flat surface of semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an outer periphery polishing device that polishes the outer periphery of the flat surface of a semiconductor wafer provided with an orientation flat to accurately polish the whole circumference of outer periphery of the flat surface of the wafer including the portion of the orientation flat, to eliminate the need of complicated control to reduce the price of the device, and to easily maintain accuracy. <P>SOLUTION: The outer periphery polishing device 1 is provided with a wafer table unit 2, an X-axis transfer device 6X, and a Y-axis transfer device 6Y. The liner portion of the outer periphery of the flat surface of the orientation flat is only polished by the linear motion of the X-axis transfer device 6X and the outer periphery of the flat surface of an arcuate section is only polished by the revolving motion of the wafer table unit 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus for polishing an outer peripheral portion of a flat surface of a semiconductor wafer.
[0002]
[Prior art]
The semiconductor wafer has a thin circular shape, and in order to show the crystal orientation, a part of the contour is notched and a linear notch called an orientation flat or a V (U) -shaped notch called a notch is formed. Furthermore, an inclined surface (bevel surface) is provided along the contour from the front and back surfaces. In each process of manufacturing a semiconductor device, the outer peripheral end surface (contour end surface), inclined surface, orientation flat or notch of the wafer, and the outer peripheral portion of the flat surface on the front side (pattern forming surface side) are polished to a mirror surface over the entire periphery. .
[0003]
In recent years, in order to manufacture a semiconductor device at a lower cost, it has been required to reduce the area of the outer peripheral portion of the flat surface that does not become a semiconductor chip.
[0004]
The outer peripheral portion of the flat surface is polished not only at the portion adjacent to the arcuate contour but also at the outer peripheral portion of the flat surface adjacent to the orientation flat or notch. As described above, in order to reduce the area of the outer peripheral portion of the flat surface, it is necessary to accurately polish the inner side by a certain distance from the contour. However, with conventional apparatuses, the portion corresponding to the orientation flat is accurately polished. In the manufacture of semiconductors, the polishing extends to the inside of the boundary line (offset line) with the pattern forming portion, or the polishing to the offset line cannot be performed and a polishing residue is generated. Was the cause of lowering the yield.
[0005]
[Patent Document 1]
JP 2001-308039 A [Patent Document 2]
JP 2002-329687 A [Patent Document 3]
JP-A-2002-367939 [0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and in a flat surface outer peripheral portion polishing apparatus for a semiconductor wafer provided with an orientation flat, the entire outer periphery of the flat surface including the orientation flat portion is polished accurately. It is an object of the present invention to provide a flat surface outer periphery polishing apparatus capable of performing the above-mentioned. It is another object of the present invention to provide an apparatus for polishing the outer peripheral portion of a flat surface of a semiconductor wafer, which does not require complicated control, and therefore can reduce the cost of the apparatus and easily maintain accuracy.
[0007]
[Means for Solving the Problems]
The above problem is solved by the following means. That is, the solving means of the first invention comprises a wafer table for supporting a semiconductor wafer having an orientation flat, a table support shaft capable of rotating while supporting the wafer table, and the table support shaft. A wafer table unit having a table drive source for rotationally driving, a tool support shaft capable of supporting and rotating a polishing tool, and a tool drive source for rotationally driving the tool support shaft A polishing tool head provided, a pressure device for applying a polishing pressure between the polishing tool and a flat surface of a semiconductor wafer supported by the wafer table, and slurry at a contact portion between the polishing tool and the semiconductor wafer. A slurry supply device for supplying, along the flat surface of the semiconductor wafer between the wafer table unit and the polishing tool head. An X-axis feeding device for giving a relative feed in a first direction, a direction along the flat surface of the semiconductor wafer between the wafer table unit and the polishing tool head, and perpendicular to the first direction. A Y-axis feed device for providing a relative feed in a second direction, and so that the polishing tool polishes outside the inner offset line offset inward by a predetermined distance from the contour of the semiconductor wafer, An apparatus for polishing an outer peripheral portion of a flat surface of a semiconductor wafer, comprising a feed control device for controlling the table drive source, the X-axis feed device, and the Y-axis feed device.
[0008]
According to a second aspect of the present invention, there is provided the semiconductor wafer flat surface outer peripheral portion polishing apparatus according to the first aspect, wherein the feed control device is arranged at an angular position where the orientation flat is parallel to the first direction. After the Y-axis feed device is operated so that the end of the polishing tool is in contact with the straight line formed by the inner offset line of the orientation flat, the X-axis feed device is operated to polish the straight portion of the outer peripheral portion of the flat surface. One or both of the X-axis feeding device and the Y-axis feeding device are operated so that the end of the polishing tool comes to a position in contact with the circle formed by the inner offset line of the circular contour of the semiconductor wafer. And a control device capable of operating the table drive source to polish the arc portion of the outer peripheral portion of the flat surface. It is a flat surface peripheral portion polishing apparatus of the wafer.
[0009]
According to a third aspect of the invention, there is provided a flat surface outer peripheral portion polishing apparatus for a semiconductor wafer according to the first or second aspect of the invention, wherein the wafer table unit includes a positioning body, and the positioning body is oriented flat on the semiconductor wafer. A pressing device for pressing toward the surface, and a clutch interposed between the table support shaft and the table drive source, and capable of interrupting the dynamic coupling between the table support shaft and the table drive source, The semiconductor, wherein the clutch is engaged after the semiconductor wafer is directed in a predetermined direction by pressing the positioning body toward the orientation flat when the clutch is disengaged. It is the flat surface outer peripheral part polishing apparatus of a wafer.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of a flat surface outer periphery polishing apparatus 1 for a semiconductor wafer according to a first embodiment. The semiconductor wafer flat surface outer periphery polishing apparatus 1 includes a wafer table unit 2, a polishing tool head 3, a pressurizing apparatus 4, a slurry supply apparatus 5, a feeding apparatus 6, and a feeding control apparatus 9.
[0011]
The wafer table unit 2 includes a wafer table 21 for supporting the semiconductor wafer W, a table support shaft 22 capable of rotating while supporting the wafer table 21, and a table driving source for rotationally driving the table support shaft 22. And an angle positioning device 24 for positioning the semiconductor wafer W supported on the wafer table 21 at a predetermined angular position.
[0012]
The polishing tool head 3 includes a tool support shaft 32 that can support and rotate the polishing tool 31, and a tool drive source 33 for rotationally driving the tool support shaft 32. A polishing pad made of a non-woven fabric or the like is affixed to the disk-shaped polishing tool 31 in a flat shape, and this is polished at the contact portion with the semiconductor wafer by the presence of slurry. In this example, a flat tool is shown, but a type in which a polishing pad is attached to a cylindrical outer surface can also be used. In that case, the tool support shaft 32 is provided so as to be orthogonal to the table support shaft 22, and the cylindrical outer surface of the polishing pad becomes the polishing surface.
[0013]
An example of the pressurizing device 4 having a piston cylinder mechanism 41 is shown, and pressurizes the polishing tool head 3 parallel to the table support shaft 22 and downward in the drawing. The slider 34 supports the polishing tool head 3 and slides on the vertical guide way 42. The load cell 43 is a sensor for detecting the force applied to the slider 34 by the piston cylinder mechanism 41. The polishing pressure applied to the polishing portion can be obtained from the gravity applied to the slider 34 and the polishing tool head 3 and the detected value of the load cell 43. The polishing pressure controls the pressure of the air (or hydraulic pressure) fed to the piston cylinder mechanism 41. Can be adjusted. Control is performed in the feed control device 9.
[0014]
The slurry supply device 5 has a nozzle N and is attached to an appropriate portion of the main body of the flat surface outer periphery polishing device 1 so that the slurry can be supplied to the contact portion between the polishing tool 31 and the semiconductor wafer W. Slurry is supplied to the nozzle N from a slurry pump (both not shown) through a pipe.
[0015]
The feeding device 6 has two orthogonal feeding devices for providing relative feeding in the direction along the flat surface of the semiconductor wafer W between the wafer table unit 2 and the polishing tool head 3, that is, the X-axis feeding device 6X and the Y-axis. It consists of a feeding device 6Y. In this example, the relative feed is realized by moving the polishing tool head 3 side, but a part or all of these mechanisms can be assigned to the wafer table unit 2 side as described later. . These feed devices 6X and 6Y are respectively composed of feed screws 61X and 61Y, female screw portions 62X and 62Y screwed to the feed screws 61X and 61Y, and servomotors 63X and 63Y for driving the feed screws 61X and 61Y. , Which is integral with the vertical guide way 42, and the female screw portion 62X supports the feeding device 6Y. The vertical guide way 42 is slidably supported on a horizontal guide way 64 fixed to the X-axis feeding device 6X.
[0016]
The feed control device 9 controls the servo motor 23 and the servo motors 63X and 63Y. The control is to control the rotation of the wafer table 21 and the feeding device 6 so that the polishing tool 31 polishes the outer side of the inner offset line offset inward from the contour of the semiconductor wafer W by a predetermined distance. ing. Details will be described later.
[0017]
The servo motor 23 of the wafer table unit 2 has an encoder 25, and the feeding device 6 controls the rotation of the wafer table 21 based on an output signal obtained from the encoder 25.
[0018]
When the unillustrated transfer device places the semiconductor wafer W on the wafer table 21, the orientation flat is forcibly directed in a predetermined direction as follows by pressing the positioning body toward the orientation flat.
[0019]
Between the table support shaft 22 and the servomotor 23 of the wafer table unit 2, a clutch 26 capable of interrupting the power coupling between the table support shaft 22 and the servomotor 23 is interposed. As shown in FIG. 2, a pressing device 27 including a piston cylinder mechanism is fixed to the main body of the wafer table unit 2, and a positioning body 28 having two parallel pins 281 is directed toward the orientation flat by the pressing device 27. Can be pressed.
[0020]
The operation of the flat surface outer periphery polishing apparatus 1 is as follows. First, the feed control device 9 controls the Y-axis feed device 6Y and the pressurizing device 4 to retract the polishing tool head 3 in the upper right direction in FIG. 1, and also controls the pressing device 27 to position it. The body 28 is retracted leftward in FIG. The X-axis feeder 6X retracts the polishing tool head 3 at the position indicated by the solid line a in FIG. The wafer table 21 and the polishing tool 31 stop rotating, and the nozzle N stops the slurry supply. The semiconductor wafer W that has been polished before that has already been carried out of the wafer table 21. Further, the clutch 26 maintains the joint state and remains coupled to the stopped servo motor 23. For this reason, the wafer table 21 does not rotate from its angular position only by receiving some force from the outside.
[0021]
A transfer device (not shown) loads and places the semiconductor wafer W on the wafer table 21. The semiconductor wafer W is sucked and held on the wafer table 21 by vacuum suction from a vacuum pump (not shown).
[0022]
After sucking and gripping, the feed control device 9 disengages the clutch 26 and places the wafer table 21 in a freely rotatable state. Next, the two pins 281 of the positioning body 28 are pressed against the orientation flat at a low speed (FIG. 2). Then, the semiconductor wafer W placed with a deviation from a predetermined angular position due to an error during conveyance is rotated integrally with the wafer table 21 that can be freely rotated, and is directed in a direction determined by the two pins 281. . By this operation, the direction of the semiconductor wafer W before the polishing operation is determined. That is, the angular relationship between the wafer table 21 and the semiconductor wafer W is determined. Note that when the semiconductor wafer W is loaded, attracted, and held at an accurate angular position, the configuration of the angle positioning device 24 such as the clutch 26 and the positioning body 28 becomes unnecessary.
[0023]
The feed control device 9 puts the clutch 26 in the engaged state and retracts the positioning body 28, and then drives the servo motor 23 to start the rotation of the wafer table 21. At this time, the information on the rotational position of the wafer table 21, that is, the semiconductor wafer W, is always grasped by the output of the encoder 25, and the orientation straight line of the orientation flat faces the first direction, that is, the feeding direction of the X-axis feeding device 6X. The wafer table 21 is rotated to an angular position and stopped. The feed control device 9 drives the Y-axis feed device 6Y to feed the polishing tool 31 to a position where it contacts the extended line of the linear portion of the inner offset line OL.
[0024]
Here, the inner offset line OL is a line in which the polishing tool 31 is offset inward by a predetermined distance D from the contour C of the semiconductor wafer W as shown in FIG. The outer region P (flat surface outer peripheral portion, cross-hatched portion) is a polishing target. In addition, B in the figure has shown the inclined surface.
[0025]
The feed control device 9 starts the supply of slurry and the rotation of the polishing tool 31, and operates the X-axis feed device 6X. The polishing tool 31 moves along the flat part of the outer peripheral portion of the flat surface corresponding to the orientation flat (FIG. 3, b) and polishes this. When the polishing tool 31 passes through the linear portion (FIG. 3, c), the Y-axis feeding device 6Y is operated to retract the polishing tool 31 along the Y-axis direction. Simultaneously or sequentially, the X-axis feeding device 6X is driven to move and stop the polishing tool 31 to the center position (FIG. 3, d). As a result, the polishing tool 31 is brought into a position in contact with the arc portion of the inner offset line OL. Next, since the wafer table unit 2 is driven and the semiconductor wafer rotates, the arc portion of the outer peripheral portion of the flat surface is polished. When the polishing of the arc portion of the outer peripheral portion of the flat surface is completed, the feed control device 9 controls the feed device 6 (6X, 6Y) and the pressurizing device 4 to retract the polishing tool head 3 in the upper right direction in FIG. . After the retreat, the rotation of the wafer table 21 and the polishing tool 31 is stopped, and the slurry supply from the nozzle N is stopped. At this time, the clutch 26 maintains a joint state, remains coupled to the stopped servo motor 23, and the wafer table 21 is stopped at a predetermined angular position. The semiconductor wafer W that has been polished is released from the vacuum suction, is unloaded from the wafer table 21, and is loaded with the next new semiconductor wafer W.
[0026]
FIG. 3 shows the relative relationship between the rotation of the semiconductor wafer W and the position of the polishing tool 31. What is important here is that the X axis feeding device 6X and the axis feeding device 6Y stop the translational motion during polishing. Only the semiconductor wafer W (wafer table 21) rotates and rotates, and when the semiconductor wafer W stops rotating, only the X-axis feeder 6X goes straight in parallel with the orientation flat, It is. Accordingly, the relative motion between the polishing tool 31 and the semiconductor wafer W at other times may be an arbitrary locus as long as no interference occurs between the members. As a result, the flat surface outer peripheral portion of the orientation flat is polished only by the linear motion by the X-axis feeder, and the flat surface outer peripheral portion of the arc portion is polished only by the rotational motion of the wafer table unit 2, so Since there is no need for multi-axis control, there are merits that the control is simple, the apparatus is inexpensive, and the accuracy can be maintained easily.
[0027]
When the transfer device places the semiconductor wafer W on the wafer table 21, the positioning body is pressed toward the orientation flat and is forced to face in a predetermined direction. Therefore, even if the orientation of the semiconductor wafer W is uneven to some extent, the outer peripheral portion of the flat surface Can be polished accurately.
[0028]
Second Embodiment FIG. 4 is a cross-sectional view of an essential part of a flat surface outer peripheral portion polishing apparatus 1 for a semiconductor wafer according to a second embodiment. In this example, a feeding device 6 (6X, 6Y) for giving a relative feed in the direction along the flat surface of the semiconductor wafer W between the wafer table unit 2 and the polishing tool head 3 is provided on the wafer table unit 2 side. Relative feed is realized by moving it. Instead of the vertical guide way 42 being fixed to the machine body, the X-axis feeding device 6X and the Y-axis feeding device 6Y move the wafer table unit 2 in the respective axial directions. Since only the rotational operation, the X-axis direction feed operation, and the Y-axis direction feed operation are different from those of the first embodiment, this is used for the operations and the like. Note that the meaning of the relative positional relationship shown in FIG. 3 does not change in this embodiment.
[0029]
Since the flat part of the flat surface of the orientation flat is polished only by the linear motion by the X-axis feeding device, and the flat part of the flat surface of the circular arc part is polished only by the rotational movement of the wafer table unit 2, complicated simultaneous multi-axis control is performed. Is the same as in the first embodiment in that the control is simple, the apparatus is inexpensive, and there is a merit that it can be easily maintained with high accuracy.
[0030]
Third Embodiment FIG. 5 is a cross-sectional view of an essential part of a flat surface outer peripheral portion polishing apparatus 1 for a semiconductor wafer according to a third embodiment. In this example, a feeding device 6 (6X, 6Y) for giving a relative feed in a direction along the flat surface of the semiconductor wafer W between the wafer table unit 2 and the polishing tool head 3 is provided on the wafer table unit 2 side. The Y-axis feeding device 6Y is an example in which the X-axis feeding device 6X is provided on the polishing tool head 3 side, thereby realizing relative feeding. The X-axis feeding device 6X may be provided on the wafer table unit 2 side, and the Y-axis feeding device 6Y may be provided on the polishing tool head 3 side. Since the meaning of the relative movement and the positional relationship is the same as that in FIG. 3, the description relating to the first embodiment is cited.
[0031]
Since the flat part of the flat surface of the orientation flat is polished only by the linear motion by the X-axis feeding device, and the flat part of the flat surface of the circular arc part is polished only by the rotational movement of the wafer table unit 2, complicated simultaneous multi-axis control is performed. Is the same as in the first and second embodiments in that the control is simple, the apparatus is inexpensive, and there is a merit that it can be easily maintained with high accuracy.
[0032]
As is clear from the above description of the first to third embodiments, only one of the operation of the X-axis feeding device and the operation of the wafer table unit 2 needs to be performed during actual polishing. The trajectory and the order of the polishing tool 31 with respect to the semiconductor wafer W (the order of polishing the orientation flat linear portion and the other arc portion on the outer peripheral portion of the flat surface) are not limited to those shown above.
[0033]
Further, since the linear portion of the orientation flat outer peripheral portion of the orientation flat is polished only by the linear motion by the X-axis feeding device, and the flat portion outer peripheral portion of the arc portion is polished only by the rotational motion of the wafer table unit 2, it is complicated. Since simultaneous multi-axis control is not necessary, the control is simple, and therefore the apparatus is inexpensive, and high accuracy can be easily maintained. In addition, the area of the outer peripheral portion of the flat surface that does not become a semiconductor chip can be further reduced, and the yield in semiconductor manufacturing can be improved.
[0034]
【The invention's effect】
According to the semiconductor wafer flat surface outer peripheral portion polishing apparatus of the present invention, the linear portion of the orientation flat flat surface outer peripheral portion is polished only by the linear motion by the X-axis feeding device, and the flat surface outer peripheral portion of the arc portion is the wafer table. Since the polishing is performed only by the rotational movement of the unit, there is no need for complicated simultaneous multi-axis control, so that the control is simple, the apparatus is inexpensive, and high accuracy and easy maintenance can be achieved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a flat surface outer periphery polishing apparatus 1 for a semiconductor wafer according to a first embodiment.
FIG. 2 is an explanatory diagram for explaining the principle of determining the orientation flat orientation.
FIG. 3 is an explanatory view showing a change in the relative position of a semiconductor wafer W and a polishing tool 31. FIG.
FIG. 4 is a cross-sectional view of a main part of a flat surface outer periphery polishing apparatus 1 for a semiconductor wafer according to a second embodiment.
FIG. 5 is a cross-sectional view of a main part of a flat surface outer periphery polishing apparatus 1 for a semiconductor wafer according to a third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flat surface outer periphery grinding | polishing apparatus 2 Wafer table unit 21 Wafer table 22 Table support shaft 23 Servo motor 24 Angle positioning device 25 Encoder 26 Clutch 27 Pressing device 28 Positioning body 281 Pin 3 Polishing tool head 31 Polishing tool 32 Tool support shaft 33 Tool Drive source 34 Slider 4 Pressurization device 41 Piston cylinder mechanism 42 Vertical guide way 43 Load cell 5 Slurry supply device 6 Feed device 6X X-axis feed device 6Y Y-axis feed device 61X, 61Y Feed screw 62X, Y Female thread portion 63X, Y Servo motor 64 Lateral guideway 9 Feed control device B Inclined surface C Contour D Distance N Nozzle OL Inner offset line P region (region of flat surface outer peripheral portion)
W Semiconductor wafer

Claims (3)

A wafer table for supporting a semiconductor wafer having an orientation flat;
A table support shaft capable of rotating while supporting the wafer table; and
A table drive source for rotationally driving the table support shaft;
A wafer table unit,
A tool support shaft capable of supporting and rotating the polishing tool; and
A polishing tool head comprising a tool drive source for rotationally driving the tool support shaft;
A pressure device for applying a polishing pressure between the polishing tool and a flat surface of the semiconductor wafer supported by the wafer table;
A slurry supply device for supplying slurry to a contact portion between the polishing tool and the semiconductor wafer;
An X-axis feed device for giving a relative feed in a first direction along the flat surface of the semiconductor wafer between the wafer table unit and the polishing tool head;
A Y-axis feeding device for giving a relative feed between the wafer table unit and the polishing tool head in a direction along the flat surface of the semiconductor wafer and in a second direction perpendicular to the first direction; as well as,
The table driving source, the X-axis feeding device, and the Y-axis feeding device are controlled so that the polishing tool polishes the outer side of the inner offset line offset inward by a predetermined distance from the outline of the semiconductor wafer. An apparatus for polishing an outer peripheral portion of a flat surface of a semiconductor wafer, comprising a feed control device for performing the operation. In the flat surface outer periphery polishing apparatus for a semiconductor wafer according to claim 1,
The feed control device moves the Y-axis feed device so that the end of the polishing tool is at a position in contact with a straight line formed by an inner offset line of the orientation flat at an angular position where the orientation flat is parallel to the first direction. After the operation, the X-axis feeding device can be operated to polish the linear portion of the outer periphery of the flat surface,
After operating one or both of the X-axis feeding device and the Y-axis feeding device so that the end of the polishing tool is in contact with the circle formed by the inner offset line of the circular contour of the semiconductor wafer, the outer periphery of the flat surface An apparatus for polishing an outer peripheral portion of a flat surface of a semiconductor wafer, which is a control device capable of operating the table driving source to polish an arc portion of a portion. In the flat surface outer periphery polishing apparatus for a semiconductor wafer according to claim 1 or 2,
The wafer table unit is
Positioning body,
A pressing device for pressing the positioning body toward the orientation flat of the semiconductor wafer; and
The clutch is interposed between the table support shaft and the table drive source, and includes a clutch capable of interrupting the power coupling between the table support shaft and the table drive source,
The semiconductor, wherein the clutch is engaged after the semiconductor wafer is directed in a predetermined direction by pressing the positioning body toward the orientation flat when the clutch is disengaged. Wafer flat surface outer peripheral polishing apparatus.

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