JPH1190801A - Double-face machining method and device for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sharply shorten machining time by pinching a wafer between grinding wheels, pressing the outer peripheries of three or more rollers to the outer periphery of the wafer from the outside in its radial direction, and concurrently grinding both faces of the wafer with both grinding wheels while rotating the wafer. SOLUTION: Multiple rollers 16, 26 are pressed to the outer periphery of a wafer W from the outside in its axial direction, and the wafer W is pinched by the upper and lower grinding wheels 30. The driving roller 16 is rotatively driven to rotate the wafer W. Both faces of the wafer W can be simultaneously ground while it is satisfactorily held, thereby the machining time can be sharply shortened. The wafer W is held when the rollers 16, 26 are merely pressed to it lightly, no large stress is applied to the wafer W during machining, thus no defect is generated on the surface of the wafer W after it is machined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for processing both surfaces of a wafer made of a semiconductor or the like.

[0002]

2. Description of the Related Art Generally, the surface of a wafer made of a semiconductor such as silicon needs to be finished to a smooth surface having high flatness. Conventionally, as a means for performing such finishing processing, first, the wafer surface is lapped to obtain high flatness, and the crushed layer generated on the wafer surface due to the lapping and the surface layer contaminated with abrasive grains are chemically etched. A method of removing the surface and then smoothing the surface by mirror polishing is generally used.

[0003]

Since the lapping process is carried out in a complete batch system, the time required for wafer setting and wafer reset is long, and the processing margin tends to vary from batch to batch. . Furthermore, the use of a wrapping agent has the disadvantage that workability and work environment deteriorate.

As a means for solving such a defect, it is conceivable to perform surface grinding on the surface of the wafer instead of lapping. For example, there is a method for grinding one surface of the wafer while holding the other surface by suction. If this is done, both sides of the wafer cannot be processed simultaneously, and a significant reduction in processing time cannot be expected. In addition, since grinding is performed in a state where the wafer is elastically deformed according to the suction side shape by suction of the wafer, after the grinding, if suction is stopped and stress is eliminated, a pattern is generated on the surface of the wafer, There is also a disadvantage that high flatness cannot be obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method and an apparatus capable of efficiently processing both sides of a wafer with high accuracy.

[0006]

As a means for solving the above problems, the present invention provides a method in which a pair of grinding wheels are simultaneously brought into contact with both surfaces of a wafer, and the wafer is sandwiched between these grinding wheels. 3 on the outer surface of this wafer
At least one of the rollers is pressed from the outside in the radial direction, and at least one of the rollers is driven as a driving roller to rotate the wafer, thereby simultaneously grinding both surfaces of the wafer with the grinding wheels. A pair of grinding wheels that sandwich the wafer in a state where the pair of grinding wheels are simultaneously in contact with both surfaces of the wafer, and a method that is pressed against the outer peripheral surface of the wafer from outside in the radial direction. One or more rollers, and driving means for rotating the wafer by rotationally driving at least one of the rollers as a driving roller. During the rotation of the wafer, both sides of the wafer are rotated by the grinding wheels. This is a wafer double-side processing apparatus configured to be simultaneously ground.

According to these methods and apparatuses, it is possible to greatly reduce the processing time by simultaneously grinding both surfaces of the wafer. Also, unlike the method of grinding while holding the wafer by suction, it does not perform grinding while generating large stress on the wafer.
Even after processing and releasing the wafer, a suitable processed surface can be maintained.

Further, the outer peripheral surfaces of four or more rollers are pressed against the outer peripheral surface of the wafer from the outside in the radial direction, and at least two of these rollers are simultaneously driven to rotate at the same peripheral speed in the same direction as driving rollers. That is, if the drive roller is 2
Even if a non-circular portion such as a flat surface or a notch exists in a part of the wafer in the circumferential direction, the non-circular portion and one driving roller are in a non-contact state. Occasionally, the rotation drive of the wafer can be satisfactorily continued by another driving roller, and the wafer can also be favorably held.

In the above apparatus, if a peripheral groove is formed on the outer peripheral surface of each roller so that the edge of the wafer fits therein, the movement of the wafer in the thickness direction of the wafer can be regulated, and each roller can be moved to the wafer. , The falling of the wafer from the clamp member in the wafer thickness direction can be more reliably prevented.

[0010]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIG.

The wafer processing apparatus shown in FIGS. 2 to 4 includes a bed 10 on which a pair of left and right drive motors 12 are installed. Output shaft 14 of each drive motor 12
The drive roller 16 is fixed to the upper end of the output shaft 14. When both drive motors 12 operate simultaneously, both drive rollers 16 are simultaneously rotated in the same direction at the same peripheral speed.

When the two drive rollers 16 are simultaneously driven, the drive motors 12 do not necessarily have to be provided with the same number of drive motors as the drive rollers 16, and by using a gear mechanism, a winding transmission mechanism, or the like, It is also possible to rotationally drive a plurality of drive rollers 16 with a single drive source.

On the bed 10, a moving table 22 is provided at a position facing the two drive motors 12.
The moving table 22 is installed on the bed 10 so as to be movable in a direction of coming and going with respect to the driving motor 12, and is driven by the feed driving motor 20 and a feed mechanism (not shown) in the above direction. (See the solid line and the two-dot chain line in FIGS. 2 and 3).

The moving table 22 has a pair of left and right rotating shafts 2.
4 is rotatably held in an upright state. Each rotating shaft 2
A driven roller 26 is fixed to an upper end of the driven roller 4, and the position of the driven roller 26 is a position facing each of the driving rollers 16 and is set at the same height as the driving rollers 16. Then, in a state where the movable table 22 has reached a predetermined position (the solid line position in FIGS. 1 to 3), the four rollers 16 and 26 can be simultaneously contacted with the outer peripheral surface of the wafer W to be processed (that is, 4 rollers). (So that the two rollers 16 and 26 are arranged on the same circumference), the arrangement positions of the rollers 16 and 26 are set.

A circumferential groove 1 having a substantially V-shaped cross section as shown in FIG.
8 (28) are formed over the entire circumference. Although the specific material of the rollers 16 and 26 can be freely set, a material that is soft and hard to damage the wafer W and has a high coefficient of friction with the wafer W, such as rubber, is preferable.

On the other hand, an orientation flat surface 2 which is a reference of the crystal orientation is formed in a part of the outer periphery of the wafer W in the circumferential direction.
By performing chamfering on the outer peripheral portion of the wafer W, the tapered surface 4 as shown in FIG. The outer peripheral portion of the wafer W having such a tapered surface 4 fits into the peripheral groove 18 (28), so that the wafer W is held at the height position (processing position). The cross-sectional shape of 18 (28) is set.

A pair of upper and lower grinding wheels 30 are disposed between the drive motors 12 and the moving table 22. These grinding wheels 30 have a cylindrical shape and are fixed around a rotary shaft 32 parallel to the direction in which the two drive motors 12 are arranged. Both ends of each rotating shaft 32 are supported by a grindstone feeder (not shown) so as to be able to move up and down. As shown in FIG. 3, the positions where the peripheral surfaces of the grinding wheels 30 contact the front and back surfaces of the wafer W in the above-described processing positions ( It can be moved up and down between a position (solid line position in the figure) and a position vertically separated from the front and back surfaces of the wafer W (a position indicated by a two-dot chain line in the figure). Also, a grindstone drive motor (not shown) is connected to each of the rotating shafts 32, and the respective rotating shafts 32 and the grindstone 30 for grinding are rotationally driven in a predetermined direction (the direction of the arrow in FIG. 3) by these grindstone drive motors. ing.

According to this apparatus, both sides of the wafer W can be processed by, for example, the following method.

As an initial state, as shown by a two-dot chain line in FIGS. 2 and 3, the moving table 22 is retracted to the rearmost position, and the grinding wheels 30 are largely separated vertically. That is, the moving table 22 and both grinding wheels 30
Is retracted from the processing position of the wafer W.

The wafer W cut out by the slicing device and having its outer peripheral portion chamfered is held in a horizontal state by holding it with a clamper (not shown), and one side of the edge (outer peripheral portion) is inserted into the peripheral groove 18 of both drive rollers 16. Fit simultaneously from the side (set to the processing position).

The movable table 22 is moved closer to the drive motor 12 by operating the feed motor 20, and when the driven rollers 26 abut on the outer peripheral surface of the wafer W, more specifically, around the driven rollers 26. When the outer peripheral portion of the wafer W fits into the groove 28, the feeding of the moving table 22 is stopped. Thereby, four rollers 1 are placed on the outer peripheral surface of the wafer W.
6, 26 are simultaneously pressed from the outside in the wafer radial direction.

With both grinding wheels 30 approaching each other, the wafer W
At the same time, the gripping of the wafer W by the clamper is released.

The two grinding wheels 30 are driven to rotate by an unillustrated grinding wheel drive motor, and the two drive motors 12
At the same time to drive the two drive rollers 16 in the same direction at the same peripheral speed. Accordingly, the wafer W rotates around its center point while the driven roller 26 rotates.
By performing the rotation of the wafer W and the rotation of the grinding wheel 24 at the same time, the double-side grinding of the wafer W is advanced. After the processing, the operation reverse to the above is performed, and the wafer W is taken out from the processing position by the clamper.

As described above, in this method and apparatus, a plurality of rollers 1 are arranged on the outer peripheral surface of the wafer W from the radial outside.
6 and 26, the drive roller 16 is rotated to rotate the wafer W while the wafer W is sandwiched between the upper and lower grinding wheels 30.
Can be ground at the same time while maintaining good, and the processing time can be greatly reduced. In addition, the wafer W is held by the roller 1
It is only necessary to lightly press the wafers 6 and 26, and unlike the method of grinding while holding one surface of the wafer W by suction, a large stress is not generated in the wafer W being processed.
There is no inconvenience that defects occur on the surface of the wafer W after processing.

Particularly, in this embodiment, the rollers 16,
26, a circumferential groove is formed, and the wafer W is held in a state where the outer peripheral portion of the wafer W is fitted therein. Since the wafer W can be restrained also in the thickness direction, the circumferential groove 1 is formed.
8 and 28, the rollers 16 and
It is possible to reliably prevent the wafer W from falling off while further reducing the pressing force of the wafer 26.

If the outer peripheral shape of the wafer W is a perfect circle, it is possible to rotate the wafer W by providing at least three rollers and rotating at least one of them. In the above embodiment, four rollers 16 and 26 are provided to hold the wafer W, and two of the driving rollers 16 are driven to rotate. Even when there is a non-circular portion such as the orientation flat surface 2 or the small notch, when the non-circular portion and one of the driving rollers 16 are in a non-contact state, the other driving roller 16 can provide a good wafer W. Rotational drive can be continued, and the wafer W
Can be maintained satisfactorily. Needless to say, the same effect can be obtained when five or more rollers are provided or when three or more rollers are driven to rotate.

Regarding the shape of the rollers, it is not necessary that all the rollers have the same shape, and the diameters of the rollers may be different. Further, even when a plurality of drive rollers 16 are simultaneously driven as described above, the drive rollers 16 may not all have the same diameter, and the larger the roller diameter, the smaller the rotational drive speed and the peripheral speed of all drive rollers. Should be the same.

FIGS. 5 and 6 show a second embodiment.
In this embodiment, a pair of upper and lower grinding wheels 40 are arranged between both drive motors 12. Each grinding wheel 40 has a disk shape and is fixed to an inner surface of a disk 44 rotating around a vertical axis 42 (a lower surface of the upper disk 44 and an upper surface of the lower disk 44). Then, in a state where both grinding wheels 40 are in contact with the front and back surfaces of the wafer W, the grinding wheels 40 are rotated in the circumferential direction integrally with the disk 44 so that the grinding process on both surfaces of the wafer W is advanced. It has become.

As described above, according to the present invention, regardless of the specific shape of the grinding whetstone 40, it is possible to simultaneously contact both the front and back surfaces of the wafer W and perform grinding in the contact state. It can be widely applied.

In the case where the driving force for rotating the wafer W is not sufficient only by driving the driving roller 16, for example, as shown in FIG.
A pair of auxiliary drive rollers 50 that sandwich the wafer W from both sides in the thickness direction may be added, and the rotational drive of the auxiliary rollers 50 may assist the rotational drive of the wafer W. In this case, the material of the auxiliary roller 50 is also different for each roller 1.
Like the materials 6 and 26, it is more preferable to use a rubber or the like that is soft and has a high coefficient of friction with the wafer W.

[0031]

As described above, according to the present invention, a pair of grinding wheels are simultaneously brought into contact with both surfaces of the wafer to sandwich the wafer between the grinding wheels, and three or more grinding wheels are provided on the outer peripheral surface of the wafer. The outer peripheral surface of the roller is pressed from the outside in the radial direction, and at least one of these rollers is driven to rotate as a drive roller, thereby simultaneously grinding both surfaces of the wafer with the grinding wheels while rotating the wafer. As a result, there is an effect that the processing time can be greatly reduced as compared with the related art, and that both surfaces of the wafer can be processed into surfaces having high flatness.

Further, the outer peripheral surfaces of four or more rollers are pressed against the outer peripheral surface of the wafer from the outside in the radial direction, and at least two of these rollers are simultaneously driven to rotate at the same peripheral speed in the same direction as driving rollers. According to the method described above, there is an effect that excellent holding and rotation driving of the wafer can be performed even when a non-arc portion exists in a part of the wafer in the circumferential direction.

In the above apparatus, when the peripheral groove of the shape in which the edge of the wafer fits is formed on the outer peripheral surface of each roller, the pressing force of each roller against the wafer can be reduced while the clamping member is removed from the clamp member. The effect of more reliably preventing the wafer from falling off in the wafer thickness direction can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a wafer processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view of the wafer processing apparatus shown in FIG.

FIG. 3 is a front view of the wafer processing apparatus shown in FIG.

FIG. 4 is a cross-sectional front view showing a state where an outer peripheral portion of a wafer is fitted into a peripheral groove of each roller in the wafer processing apparatus.

FIG. 5 is a perspective view of a wafer processing apparatus according to a second embodiment of the present invention.

6 is a plan view of the wafer processing apparatus shown in FIG.

FIG. 7 is a perspective view of a wafer processing apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 12 drive motor (drive means) 16 drive roller 18, 28 circumferential groove 26 driven roller 30 grinding wheel

Claims (5)

[Claims] 1. A method for simultaneously grinding both surfaces of a wafer, wherein a pair of grinding wheels are simultaneously brought into contact with both surfaces of the wafer to sandwich the wafer between the grinding wheels, and The outer peripheral surfaces of three or more rollers are pressed against the outer peripheral surface from outside in the radial direction, and at least one of these rollers is rotationally driven as a driving roller to rotate the wafer while rotating the wafer by the grinding wheels. A method for processing both sides of a wafer, characterized in that both sides are simultaneously ground. 2. The double-sided wafer processing method according to claim 1, wherein the outer peripheral surface of four or more rollers is pressed against the outer peripheral surface of the wafer from the radial outside, and at least two of these rollers are driven by a driving roller. A double-sided processing method for a wafer, wherein the wafers are simultaneously rotated in the same direction at the same peripheral speed. 3. An apparatus for simultaneously grinding both surfaces of a wafer, comprising: a pair of grinding wheels for sandwiching the wafer while the pair of grinding wheels are simultaneously in contact with both surfaces of the wafer; and an outer peripheral surface of the wafer. And three or more rollers pressed against the outside in the radial direction, and driving means for rotating the wafer by rotationally driving at least one of the rollers as a driving roller. A double-sided wafer processing apparatus characterized in that both sides of the wafer are simultaneously ground by both grinding wheels. 4. The double-sided wafer processing apparatus according to claim 3, further comprising four or more rollers pressed against the outer peripheral surface of the wafer from the outside in the radial direction, at least two of the rollers being the same as the drive rollers. A double-sided wafer processing apparatus, wherein the driving means is configured to be simultaneously driven to rotate at the same peripheral speed in the directions. 5. The double-sided wafer processing apparatus according to claim 3, wherein a peripheral groove having a shape into which an edge of the wafer is fitted is formed on an outer peripheral surface of each of the rollers. apparatus.