JP2008023690A - Truing method for wafer chamfering grinding wheel and wafer chamfering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a truing method for a wafer chamfering grinding wheel capable of preventing the degradation of a truer and improving the efficiency of shape transfer to the chamfering grinding wheel, and to provide a wafer chamfering device. <P>SOLUTION: The truer 41 rotating at a low speed is moved at a position permitting cutting into a prescribed cutting depth relative to an outer peripheral precision grinding wheel 55 rotating at a low speed in the tangential direction of the outer peripheral precision grinding wheel 55, and a groove 55a for chamfering is formed relative to the outer peripheral precision grinding wheel 55, thereby suppressing the rotational speed of the truer 41 and improving the efficiency of the shape transferring to the outer peripheral precision grinding wheel 55. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wafer chamfering grindstone truing method for chamfering a wafer, which is a material for semiconductor devices and electronic components, and a wafer chamfering apparatus provided with the truing grindstone.

  A wafer such as silicon, which is a material for semiconductor devices and electronic components, is sliced from the ingot state with a slicing device such as an inner peripheral blade or a wire saw, and then the outer peripheral portion is prevented to prevent cracking or chipping of the peripheral edge. Chamfering is applied to The chamfering device used for chamfering is attached with a plurality of various grindstones such as a grindstone for grinding the outer circumference of the wafer and a notch grindstone for grinding a V-shaped notch serving as a reference position for the orientation, These grindstones are processed by rotating them at high speed with a spindle.

  At the time of processing, the wafer is sucked and mounted on a rotating wafer table, and the wafer and the grindstone are relatively moved by the guide shafts of the X guide, the Y guide, and the Z guide, and the chamfer formed on the grindstone is formed. Chamfering is performed by placing the outer periphery of the wafer against the groove for use.

  The chamfering grooves formed in these grindstones are formed after the grindstone is mounted on the chamfering device, and the chamfering device is provided with a truing grindstone for forming the grooves (see, for example, Patent Document 1). .

In such a chamfering apparatus, first, a low speed formed by green carbide abrasive grains (hereinafter referred to as GC abrasive grains) from a master groove of a master grindstone rotating at high speed formed by a metal bond grindstone containing diamond abrasive grains. The desired wafer outer peripheral shape is transferred to the outer peripheral portion of a truing grindstone (hereinafter referred to as "truer") that rotates at the same time. The outer peripheral shape transferred to the truer is transferred to a chamfering grindstone formed by a resin bond grindstone containing diamond abrasive grains. The groove shape is transferred to the chamfering grindstone when the high-speed rotating lure and the low-speed chamfering grindstone move on a straight line connecting the respective rotation centers, and the truer cuts into the chamfering grindstone. Transcribed.
JP-A-11-347901

  However, when truing is performed with a chamfering device such as that described in Patent Document 1, the truer is usually only about 1 mm to 2 mm thick and cannot withstand the grinding resistance of the chamfering grindstone during truing. May buckle. Further, the truing surface wears with each transfer, and the shape transferred from the master grindstone cannot be correctly transferred to the chamfering grindstone. Further, in order to improve the transfer efficiency, it is necessary to increase the number of movements and to spend truing over time, so that the downtime of the apparatus becomes long.

  Furthermore, although the truer is mounted on the same axis that rotates the wafer table, it is difficult to achieve high resolution during wafer chamfering, both low-speed rotation and high-speed rotation during truing with a single motor. Further, there is a problem that the rotational axis of the rotating shaft is thermally expanded due to heat generated by the high-speed rotation of 500 to 800 rpm, and the chamfering width accuracy of the wafer is significantly deviated.

  SUMMARY OF THE INVENTION The present invention has been made for such a problem, and a truing method for a wafer chamfering grindstone and a wafer that suppresses the rotation speed of the truer, prevents the deterioration of the truer, and improves the shape transfer efficiency to the grindstone for chamfering. The object is to provide a chamfering device.

  In order to achieve the above object, the present invention provides a wafer table that holds and rotates a wafer, a grindstone that chamfers the outer periphery of the wafer, and a moving means that moves the wafer table relative to the grindstone. And using a wafer chamfering device including a truing grindstone for forming a groove for chamfering the outer peripheral portion of the wafer with respect to the grindstone, and the truing grindstone can be cut into the grindstone with a predetermined cutting depth. The groove is formed in the grindstone by moving in a tangential direction of the grindstone at a position.

  The truing grindstone is a green carbide grindstone, and the grindstone is a resin bond grindstone.

  According to the present invention, the desired chamfering groove shape transferred from the master grindstone formed by the metal bond grindstone to the truer formed by the GC grindstone is transferred to the chamfering grindstone formed by the resin bond grindstone. Is done.

  When transferring from the truer to the chamfering grindstone, the truer moves to the vicinity of the chamfering grindstone to a position where it can be cut to a predetermined cut depth of 0 to 150 μm, and according to the truer diameter of 10 to 200 rpm. The groove shape is transferred to the chamfering grindstone by creep feed grinding by moving in the tangential direction of the chamfering grindstone while rotating at a rotational speed (for example, 140 rpm with a φ200 mm truer). When the truer moves in the tangential direction of the chamfering grindstone, the truer's moving speed is variable at the beginning of truing, during truing and at the end of truing, and the speed is changed so that the transfer efficiency is optimal. .

  Thereby, since the truer rotates at a low speed, the thermal expansion of the rotating shaft is suppressed, and the chamfering width accuracy of the wafer is improved. In addition, the biting of the abrasive grains of the truer is improved at low speed rotation, so that the cutting efficiency is increased, the deterioration of the truer is suppressed, and the shape transfer efficiency to the chamfering grindstone is improved. Further, since the shape transfer efficiency is improved, truing can be performed in a shorter time than the conventional method.

  As described above, according to the truing method and the wafer chamfering device for the wafer chamfering grindstone, the rotation speed of the truer is suppressed, the deterioration of the truer is prevented, the shape transfer efficiency to the grindstone for chamfering processing is improved, and in a short time. Enables truing with high accuracy.

  Hereinafter, preferred embodiments of a truing method for a wafer chamfering grindstone and a wafer chamfering apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  First, the configuration of the chamfering apparatus according to the present invention will be described. FIG. 1 is an overall front view of the chamfering apparatus.

  First, the configuration of the wafer chamfering apparatus according to the present invention will be described. FIG. 1 is a front view showing a main part of the chamfering apparatus. The chamfering apparatus 10 includes a wafer feeding unit 20, a grindstone rotating unit 50, a wafer supply / storage unit (not shown), a wafer cleaning / drying unit, a wafer transfer unit, and a controller that controls operations of each part of the chamfering device.

  The wafer feed unit 20 includes an X-axis base 21, two X-axis guide rails 22, 22, four X-axis linear guides 23, 23,. The X table 24 is moved in the X direction in the figure by an X axis driving means 25 comprising:

  In the X table 24, two Y-axis guide rails 26, 26, four Y-axis linear guides 27, 27,..., Y-axis driving means including a ball screw and an AC servo motor (not shown) are arranged in the Y direction in the figure. A Y table 28 to be moved is incorporated.

  The Y table 28 is guided by two Z-axis guide rails 29 and 29 and four Z-axis linear guides (not shown), and is moved in the Z direction in the figure by a Z-axis driving means 30 comprising a ball screw and an AC servo motor. Z table 31 is incorporated.

  The Z table 31 incorporates a θ-axis motor 32 and a θ spindle 33, and a wafer table 34 on which the wafer W is sucked and mounted is attached to the θ spindle 33. The wafer table 34 has a wafer table rotation axis CW. It is rotated in the θ direction in the figure as the center.

  A truing grindstone 41 (hereinafter referred to as a truer 41) used for truing a grindstone for chamfering the peripheral edge of the wafer W is attached to the lower portion of the wafer table 34 concentrically with the wafer table rotation axis CW.

  By the wafer feeding unit 20, the wafer W and the truer 41 are rotated in the θ direction in the figure and are moved in the X, Y, and Z directions.

  The grindstone rotating unit 50 is provided with an outer peripheral grindstone 52 and a built-in motor driven outer grindstone spindle 51 that uses a ball bearing that is rotationally driven around an axis CH by an outer grindstone motor (not shown).

  Further, in the grindstone rotating unit 50, a built-in motor-driven outer peripheral precision spindle 54 using an air bearing, an outer peripheral precision motor 56, an air bearing attached to a turntable 53 disposed above the outer peripheral processing grindstone 52. A notch roughing spindle 60 using air turbine, a notch roughing motor 62, a built-in motor driving notch fine spindle 57 using an air bearing, and a notch fine motor 59.

  The outer peripheral fine spindle 54 is inclined (8 degrees in this embodiment) with the rotation axis in the tangential direction of the wafer W (X-axis direction shown in FIG. 1).

  A peripheral grinding wheel 55 which is a chamfering grindstone for finish grinding the outer circumference of the wafer W is attached to the peripheral grinding spindle 54.

  A notch rough grinding wheel 61 is attached to the notch rough spindle 60, and a notch fine grinding wheel 58, which is a chamfering grind for grinding the notch portion, is attached to the notch fine spindle 57. The notch precision grinding wheel 58 is held so as to be inclined by a predetermined amount in an arbitrary direction.

  The outer peripheral fine grinding wheel 55, the notch fine grinding wheel 58, and the notch coarse grinding wheel 61 are positioned at the processing positions by the rotation of the turntable 53.

  FIG. 2 shows a truer 41 attached to the wafer table 34. As shown in FIG. 2, the truer 41 is attached to the lower part of the wafer table 34 concentrically with the wafer table rotation axis CW and is rotated θ by the θ-axis motor 32. Further, the upper surface of the wafer table 34 is a suction surface that communicates with a vacuum source (not shown), and a wafer W to be chamfered is placed and fixed by suction.

  FIG. 3 shows the configuration of the outer peripheral processing grindstone 52. The outer peripheral processing grindstone 52 has a two-stage configuration, the lower stage is a master grindstone 52A having a master groove 52a that forms the outer peripheral shape of the truer 41, and the upper stage is an outer peripheral rough grind groove 52b for forming a wafer W. It is a grinding wheel 52B.

  In order to simplify the description in FIG. 3, one grindstone is described for each grindstone. However, in order to cope with the deformation of the groove shape due to wear, a plurality of grindstones are provided for each grindstone. Grooves are formed.

  The truer 41 is formed by a disk-shaped green carbide grindstone (hereinafter referred to as a GC grindstone) having an outer diameter and thickness equal to or smaller than those of the wafer W to be processed.

  The master grindstone 52A is formed of a metal bond grindstone of diamond abrasive grains having an outer diameter equal to or smaller than that of the wafer W. The outer peripheral rough grinding stone 52B is a diamond-bonded metal bond grindstone having the same diameter as the master grindstone 52A, and has a coarser particle size than the master grindstone 52A.

  The peripheral grinding wheel 55 is formed of a resin bond grindstone made of diamond grains having a diameter of about 50 mm or less.

  Further, the notch rough grinding wheel 61 has a small diameter of 1.8 mm to 2.4 mm, and the diamond bond metal bond wheel 58 and the notch fine grinding wheel 58 have a small diameter of 1.8 mm to 2.4 mm. The resin bond grindstone is used.

  Since the other components of the chamfering device 10 are generally well-known mechanisms, a detailed description is omitted.

  Next, a truing method for a wafer chamfering grindstone according to the present invention will be described. 4 is a front view showing the chamfered shape transfer to the truer 41, FIG. 5 is a perspective view showing a state before the truing is started, FIG. 6 is a perspective view showing a state during the truing, and FIG. 7 is a diagram showing the movement of the truer. It is the top view shown.

  The chamfering device 10 first performs chamfering on the outer periphery of the truer 41 with the master grindstone 52 </ b> A, thereby transferring the shape of the master groove 52 a to the outer peripheral portion of the truer 41. In the shape transfer to the truer 41, the Z table 31 is moved by the Z-axis drive means 30, and as shown in FIG. 4A, the height of the truer 41 matches the master groove 52a of the master grindstone 52A. Positioned.

  Next, the Y table 28 is moved toward the master grindstone 52A. As shown in FIG. 4B, the outer periphery of the truer 41 is cut into the master groove 52a of the master grindstone 52A by the movement of the Y table 28 in the Y direction. The wafer table 34 is slowly rotated once by the θ-axis motor 32 to chamfer the outer peripheral portion of the truer 41, and the shape of the master groove 52 a is transferred to the outer peripheral portion of the truer 41.

  Next, as shown in FIG. 4C, the truer 41 is moved away from the master grindstone 52A, and the transfer from the cross-sectional shape of the master groove 52a of the master grindstone 52A to the cross-sectional shape of the outer peripheral portion of the truer 41 is completed. To do.

  Next, truing of the outer peripheral grinding wheel 55 shown in FIG. 5 whose rotational axis is inclined 8 degrees in the tangential direction of the wafer W is performed using the truer 41 in which the cross-sectional shape of the master groove 52a is transferred to the outer peripheral portion.

  In the truing of the outer peripheral grinding wheel 55, first, the Z table 31 is moved, so that the height of the truer 41 is adjusted to the same height as the outer peripheral groove forming position of the outer peripheral grinding wheel 55.

  As shown in FIG. 7 (S), the truer 41 adjusted to the same height moves the outer peripheral precision grinding wheel 55 by a depth k to be cut into the outer peripheral grinding wheel 55 as shown in FIG. It is positioned in the vicinity of the outer peripheral fine grinding wheel 55 that approaches.

  In this state, the truer 41 starts to rotate in the direction of arrow A or arrow B shown in FIG. Accordingly, the outer peripheral grinding wheel 55 starts to rotate at a low speed in the direction of arrow C (for example, in the case of the outer peripheral precision grinding wheel 55 of φ50 mm, the rotation speed is 3400 rpm and the speed is 8400 rpm) 41. Moves in the direction of arrow D. As a result, as shown in FIG. 6, a chamfering groove 55 a is formed on the outer peripheral grinding wheel 55.

  At this time, the rotation speed of the truer 41 is rotated at a low speed of about 10 to 200 rpm per minute. The outer peripheral grinding wheel 55 that has started to move in the direction of arrow D from the position of FIG. 7 (S) moves from FIG. 7 (S) to (M), and finally moves in parallel to the position of (E).

  When moving, the moving speed of the truer 41 at the (S) position, (M) position, and (E) position is variable, and the speed is changed so that the transfer efficiency is optimized. For example, the movement speed is changed at a high speed at the (S) position, the movement speed is changed to a low speed immediately before the contact with the outer peripheral grinding wheel 55, and the movement speed is changed again to a high speed at the (M) position and moved to the (E) position.

  Thereby, the shape of the chamfering groove 55a is transferred to the outer peripheral fine grinding wheel 55 by creep feed grinding with high transfer efficiency, and truing is completed.

  Truing is performed on the notch precision grinding wheel 58 in the same manner. After truing all the grindstones, the chamfering apparatus 10 places the wafer W on the wafer table 34 and starts chamfering.

  As described above, according to the wafer chamfering grindstone truing method and the wafer chamfering apparatus according to the present invention, the rotation speed of the truer is suppressed by the truing of the grindstone by creep feed grinding, and the heat generation of the rotating shaft for rotating the wafer table is achieved. And prevent thermal expansion of the rotating shaft. Thereby, it is possible to process a wafer with high accuracy. In addition, the bite of the truer formed by GC abrasive grains on the processing grindstone is improved, the wear of the truer is reduced, and the shape transfer efficiency to the chamfering grindstone is improved, so that the truing time is shortened and the truer is deteriorated. Will also prevent.

  In the present embodiment, the outer peripheral grinding wheel 55 is inclined by 8 degrees, but the present invention is not limited to this, and an outer peripheral precision grinding wheel that is not inclined can be suitably implemented.

  In this embodiment, truing with a chamfering device is described. However, the present invention is not limited to this, and the present invention can also be implemented in a truing dedicated device that attaches a grindstone and a truer and performs only truing.

The whole front view of the chamfering apparatus concerning this invention. The enlarged view around a wafer table. The side view which showed the outer periphery processing grindstone. The front view which showed the chamfering shape transcription | transfer to a truing grindstone. The perspective view which showed the state before truing start. The perspective view which showed the state during truing. The top view which showed the movement of the truer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Chamfering device, 24 ... X table, 28 ... Y table, 33 ... θ spindle, 34 ... Wafer table, 41 ... Truer (truing grindstone), 52 ... Peripheral processing grindstone, 54 ... Peripheral precision spindle, 55 ... Peripheral precision Grinding wheel (chamfering wheel), 58 ... Notch precision grinding wheel (chamfering wheel), W ... Wafer

Claims (4)

A wafer table that holds and rotates the wafer;
A grindstone for chamfering the outer periphery of the wafer;
Moving means for moving the wafer table relative to the grindstone;
Using a wafer chamfering device provided with a truing grindstone that forms a groove for chamfering the outer peripheral portion of the wafer with respect to the grindstone,
The truing grindstone forms the groove with respect to the grindstone by moving in the tangential direction of the grindstone at a position where the truing grindstone can be cut to a predetermined cutting depth. Truing method.   2. The truing method for a wafer chamfering grindstone according to claim 1, wherein the truing grindstone is a green carbide grindstone.   The truing method for a wafer chamfering grindstone according to claim 1 or 2, wherein the grindstone is a resin bond grindstone. A wafer table that holds and rotates the wafer;
A grindstone for chamfering the outer periphery of the wafer;
Moving means for moving the wafer table relative to the grindstone;
Wafer chamfering comprising a truing grindstone for forming a groove in the grindstone for chamfering the outer periphery of the wafer by moving in a tangential direction of the grindstone at a position where the grindstone can be cut to a predetermined depth of cut. apparatus.

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