JPH10217082A - Holding plate for double-sided work of wafer and double-sided work method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily fit a wafer in a through-hole by arranging the through-hole having an inner peripheral surface fittable to an outer peripheral surface of this wafer in a plate material thinner than the wafer, and freely deflectively deforming this peripheral edge part in the plate thickness direction by forming a notch in a radial shape from the peripheral edge part of this through-hole. SOLUTION: A holding plate 36 is formed in a plate shape thinner than a wafer W being a work object, and a through-hole having an inner peripheral surface 36a of a shape fittable to an outer peripheral surface of this wafer W is provided. Plural slits 38 extending in a radial shape from a peripheral edge part of this through-hole are formed, and the peripheral edge part of the through-hole is formed by the formation of these slits 38 so as to be deflectively deformable in the plate thickness direction. The through-hole is temporarily and diametrically expanded by this deflective deformation. The wafer W can be easily fitted in this through-hole in this diametrically expanded condition.

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. Also, since grinding is performed with a relatively high stress generated on the wafer by suction of the wafer, after stopping the suction and removing the stress after the grinding, a pattern is generated on the surface of the wafer and high flatness is obtained. There is also a disadvantage that it cannot be obtained.

Further, when a wafer is cut out with a thickness gradient in a previous step (step of cutting out from an ingot), the wafer is sucked and ground as it is to finish the wafer with a target plane set along a predetermined crystal orientation. There is also a drawback that good parallelism with the plane cannot be obtained. For example, as shown in FIG. 8A, when the shape of the wafer W cut out by the wire saw becomes a shape that becomes thicker toward the lower side in FIG. If the upper surface of the wafer W is ground horizontally by suction as described above, the parallelism between the ground surface 70 and a target plane CC set in advance along a predetermined crystal orientation may be shifted by an angle θ. become.

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide an apparatus and the like capable of processing both sides of a wafer efficiently and with high precision.

[0007]

As a means for solving the above-mentioned problems, the present invention provides a holding plate for holding a wafer whose edges have been chamfered when simultaneously grinding both surfaces of the wafer. Then, a through hole having an inner peripheral surface capable of fitting with the outer peripheral surface of the wafer is provided in a plate material thinner than the wafer, and a cut is made radially from the peripheral portion of the through hole so that the peripheral portion extends in the plate thickness direction. The through-hole is configured so as to be able to be flexibly deformed, and the diameter of the through hole is enlarged by the flexure.

According to this holding plate, the peripheral edge is forcibly bent to temporarily expand the diameter of the through-hole, and in this state, a wafer to be processed is set inside the through-hole, and then the peripheral edge is removed. The wafer can be fitted into the through-hole by releasing the forced bending of the portion and returning the holding plate to the original shape.

In this manner, while holding the wafer on the wafer holding plate, a pair of rotary grinding stones are arranged with a gap smaller than the thickness of the wafer in a state where their rotation axes are parallel to each other. While rotating and driving, the wafer and the wafer double-sided processing holding plate are passed through the wafer in the gap between the two grindstones, and both sides of the wafer are simultaneously brought into contact with the outer peripheral surfaces of the two grindstones, so that both sides of the wafer can be simultaneously ground,
As a result, the processing time can be significantly reduced.
Further, unlike the method of holding the wafer by suction, grinding is not performed while generating a large stress on the wafer, so that a suitable processed surface can be maintained even after the wafer is processed and released. Further, even if the wafer is cut out with a thickness gradient, as long as it is clamped and passed between the two grindstones, both surfaces of the wafer can be properly corrected, and a finished surface along a predetermined crystal orientation can be formed. Can be obtained exactly.

Further, since the inner peripheral surface of the through hole of the holding plate has a shape that matches the outer peripheral surface of the wafer whose edge is chamfered, the inner peripheral surface and the outer peripheral surface of the wafer are fitted together. The movement of the wafer in the thickness direction is restricted, and the wafer is prevented from falling off the wafer holding plate.

Further, if the peripheral portion of the through hole of the holding plate for double-sided processing of the wafer is made of an elastic material such as rubber, the wafer can be held without inconvenience even if the outer diameter of the wafer is slightly varied. Further, since the coefficient of friction between the inner peripheral surface of the holding plate and the outer peripheral surface of the wafer becomes large, the rotation of the held wafer in the through hole is restricted, thereby further improving the processing accuracy of the wafer. Becomes

Further, the present invention is an apparatus for simultaneously grinding both surfaces of a wafer whose edges are chamfered, wherein the rotating shafts are arranged in parallel with a gap smaller than the thickness of the wafer. 3. A pair of rotary grindstones, a grindstone driving unit for rotating and driving these rotary grindstones, the holding plate for double-sided wafer processing, a grindstone driving unit for rotatingly driving these rotary grindstones, and the wafer double-side processing according to claim 1 or 2. The wafer holding plate and the rotating grindstone pair are relatively moved in a direction parallel to the wafer double-sided processing holding plate, and the wafer held by the wafer double-sided processing holding plate is passed through the gap between the rotary grinding wheels. Means.

In this apparatus, if there is provided a grindstone feeding means for moving the rotating grindstones in opposite directions to change the gap size between the rotating grindstones, the wafer thickness dimension after processing can be freely set by the change in the gap dimension. Can be adjusted.

[0014]

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 has a bed 10. A grindstone table 12 is disposed on both left and right wings of the bed 10, and a wafer holding table 14 is disposed in the center of the back of both grindstone tables 12.

Each grindstone table 12 includes a fixed table 16 and a movable table 1.
8 is provided. The fixed base 16 extends in the left-right direction (the X-axis direction in FIGS. 2 and 4; hereinafter, simply referred to as “X-axis direction”) of the entire processing apparatus, and is fixed on the bed 10. The movable table 18 is supported on the fixed table 16 so as to be slidable in the X-axis direction, and is slid in the X-axis direction by a grinding wheel feed motor 28 and a feed screw mechanism (not shown).

A grindstone holding section 20 is formed at the front end (end from the center of the processing apparatus) of each moving table 18. A grinding wheel rotating shaft 22 extending vertically is rotatably held by the grinding wheel holding unit 20, and a grinding wheel (rotary grinding wheel) 24 is fixed around the grinding wheel rotating shaft 22. When the two carriages 18 are slid in the opposite directions by the operation of the grinding wheel feed motor 28, the grinding wheels 24 come into contact with and separate from each other, so that the gap between the grinding wheels 24 can be arbitrarily adjusted. Has become. A rotation drive motor (grinding wheel driving means) 26 is connected to each of the grinding wheel rotation shafts 22, and the operation of the rotation drive motor 26 causes the grinding wheel 24 to rotate in a predetermined direction about the grinding wheel rotation shaft 22 (FIG. 1B). (In the direction of the arrow).

The wafer holding table 14 also includes a fixed table 30 and a moving table 32. The fixed base 30 extends in the front-rear direction (the Y-axis direction in FIGS. 2 and 4; hereinafter, simply referred to as “Y-axis direction”) of the entire processing apparatus, and is fixed on the bed 10. The movable table 32 is slidably supported on the fixed table 30 in the Y-axis direction, and is slid in the Y-axis direction by a wafer feed motor (wafer sending means) 33 and a feed screw mechanism (not shown). I have.

A pair of upper and lower support arms 34 extending in the Y-axis direction are fixed to the movable table 32. The front ends of these support arms 34 are provided with slits 3 opened forward.
4a are formed, and holding plates for wafer double-sided processing (hereinafter simply referred to as “holding plates”) 36 are formed in these slits 34a.
The upper and lower ends are inserted and fixed by bolts or the like (not shown). That is, the holding plate 3 is
6 is detachably attached.

As shown in FIGS. 1A and 1B, the holding plate 36 has a plate shape thinner than the wafer W to be processed, and has a shape that can be fitted to the outer peripheral surface of the wafer W. A through hole having an inner peripheral surface 36a is provided. More specifically, since the wafer W is chamfered on both front and back edges to form a tapered surface tf, the tapered surface tf
The inner peripheral surface 36a is processed into a V-groove shape so that the inner peripheral surface 36a of the holding plate 36 substantially matches the inner peripheral surface 36a.

Further, as a feature of the holding plate 36, a plurality of slits 3 extending radially from the peripheral edge of the through hole are provided.
8 are formed (that is, cuts are made radially), and by forming these slits 38, the peripheral portion of the through-hole can be bent and deformed in the plate thickness direction (vertical direction in FIG. 1A). Have been. In addition, a circular through hole 40 for reducing stress concentration is provided at the tip of the slit 38.

In the present invention, regardless of the specific material of the wafer W, the present invention can be applied to wafers of various materials that can be ground, such as silicon. Further, the material of the holding plate 36 may be any material having a strength capable of holding the wafer W without inconvenience during wafer processing described later, and a metal material such as stainless steel can be applied.

2 to 4, the mounting position of the holding plate 36 on the moving table 32 in the X-axis direction is set to a position that coincides with the intermediate position between the two grinding wheels 24. The axial dimension (the vertical dimension in the illustrated example) of the two grinding wheels 24 is set to be equal to or larger than the diameter of the wafer W, and the entire area of both sides of the wafer W is covered by the two grinding wheels 24.
The mounting height position of the holding plate 36 is set so that the holding plate 36 can come into contact with the holding plate 36.

A support column 48 is erected at an appropriate position on the bed 10, and a dressing device 50 is supported on an upper end of the support column 48. The dressing device 50 includes a fixed table 52 and a lifting table 54. The fixed table 52 is fixed to the support column 48. The lifting table 54 slides on the fixed table 52 in the vertical direction (the Z-axis direction in FIG. 4). It is supported so that it can move up and down.

The grindstone holding rod 56 extends downward from the lifting table 54.
The dressing grindstone 58 is fixed to the lower end of the grindstone holding rod 56. The dressing grindstone 58 has both ends in the X-axis direction protruding from both side surfaces of the grindstone holding rod 56.
The supporting position of the entire dressing device 50 is set so that the side surfaces of the dressing device 4 can be simultaneously contacted (see FIG. 2). Also,
A dress feed motor 60 is provided on the top of the fixed base 52, and the lift table 54, the grindstone holding rod 56, and the dressing grindstone 58 are vertically reciprocated by the dress feed motor 60 and a feed screw mechanism (not shown). It is designed to be driven.

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

As an initial state, the moving table 18 of the grindstone table 12 and the moving table 32 of the wafer holding table 14 are retracted. The dressing grindstone 58 of the dressing device 50 is retracted to a position above the grinding grindstones 24.

The wafer W cut out by a slicing device (not shown) is transported and attached to the holding plate 36. In order to perform this attachment, it is convenient to use, for example, an operation table 62 as shown in FIG. The operating table 62 has a flat upper surface formed with a circular step 64 higher by one step than this, and the diameter of the step 64 is
6 is set slightly larger than the diameter of the through hole. When the outer peripheral portion of the holding plate 36 is pressed against the upper surface of the operation table 62 while the peripheral edge of the holding plate 36 is in contact with the edge of the step portion 64 (see the arrow P), the peripheral portion of the through hole faces upward by the step portion 64. To bend in that direction, and the diameter of the through-hole of the holding plate 36 is expanded by this bending deformation.
Therefore, in this state, the wafer W can be placed on the step 64 (ie, the wafer W can be set in the through hole), and then the load on the holding plate 36 is released to change the shape of the holding plate 36. By returning to the original flat shape, the holding plate 3
The wafer W can be easily fitted into the through hole 6.

The holding plate 36 is inserted from the front into the slits 34 a of both support arms 34 and fixed with bolts or the like.
As a result, the wafer W is held together with the holding plate 36 in a vertical state.

The operation of each rotation drive motor 26 drives the grinding wheel 24 to rotate.
Is moved forward so that the grinding wheels 24 approach each other, and the gap between the two grinding wheels 24 matches the size corresponding to the target thickness dimension of the wafer W (<current thickness dimension).

In the state described above, the moving table 32 of the wafer holding table 14 is further advanced. Here, since the holding plate 36 is thinner than the wafer W, the holding plate 36 passes between the grinding wheels 24 without contacting the two grinding wheels 24, and only the front and back surfaces of the wafer W (FIG. 6). Thereby, both surfaces of the wafer W are simultaneously ground. After the processing, the holding plate 36 is removed from the support arm 34, the wafer W is removed from the holding plate 36 by using the operation table 62, and the wafer W is collected. If the sharpness of the grinding wheel 24 becomes dull, the dressing device 5
The two grindstones 24 are appropriately dressed using the 0 dressing grindstone 58.

As described above, in this method and apparatus, the wafer W is held by the holding plate 36 having a smaller thickness, and the holding plate 36 is passed between the grinding wheels 24 approaching each other. In addition, both surfaces of the wafer W can be ground at once while holding the wafer W stably, whereby the processing time can be greatly reduced.

Further, the holding of the wafer W only needs to be fitted into the through hole of the holding plate 36, and a large stress is applied to the wafer W during processing as in the method of grinding while holding one surface of the wafer W by suction. Since there is no inconvenience, there is no inconvenience that defects occur on the surface of the wafer W after processing.

Even when the wafer W is cut out with a thickness gradient (that is, when both surfaces of the wafer W are mutually inclined), it is preferable to pass the wafer W between the two grinding wheels 24. Shape correction can be performed, and a finished surface along a predetermined crystal orientation can be accurately and easily obtained.

Further, since the inner peripheral surface 36a of the holding plate 36 is formed in a V-groove shape which matches the angled tapered surface tf formed by chamfering the edge of the wafer W, the wafer W is held in the X-axis in the holding state. It can also be regulated from both outer sides in the direction (upper and lower sides in FIG. 1A). For this reason, even when an external force acts on the wafer W from the X-axis direction during processing, if the external force is a value within an appropriate range, the wafer W is moved from the holding plate 36 by the external force due to the external force. It can be prevented from dropping off in the axial direction.

Further, in the holding plate 36, a radial slit 38 is formed in the peripheral portion of the through hole so that the peripheral portion can be bent and deformed in the plate thickness direction, and the through hole is temporarily expanded by the bending deformation. Since the diameter is set, the wafer W can be easily fitted in this expanded state.

In the present invention, the number of cuts (FIG. 1)
In the above example, the cut width and the cut length may be appropriately set regardless of the number of slits 38).

In the above embodiment, the wafer W is moved to perform the double-sided processing. For example, both grinding wheels 24 are mounted on a table movable in a direction parallel to both surfaces of the wafer W. However, it is also possible to process both surfaces of the wafer W by moving these grinding wheels 24.

A second embodiment will be described with reference to FIGS. 7 (a) and 7 (b).

In the second embodiment, the periphery of the through hole in the holding plate 36 is formed of an elastic body 42 such as rubber. In this structure, if the diameter of the through hole of the holding plate 36 is set slightly smaller, even if there is some variation in the diameter of the wafer W, this can be absorbed by the elastic deformation of the elastic body 42, The wafer W can be held without any inconvenience. In addition, since the coefficient of friction between the inner peripheral surface 36a and the wafer W is larger than when the inner peripheral surface 36a is made of a metal material, it is possible to restrict the circumferential slip of the wafer W during processing, and the slip ( That is, it is possible to prevent the processing accuracy from lowering due to the rotation of the wafer W).

[0041]

As described above, the present invention is a holding plate having a through-hole which is thinner than a wafer and can be fitted with a wafer, and drives a pair of rotary grindstones to rotate the wafer together with the holding plate. Since both surfaces of the wafer are simultaneously ground through the gaps between the above-mentioned rotating whetstones, the processing time can be greatly reduced compared to the conventional method, and the effect of obtaining a highly flat wafer surface with high accuracy can be obtained. is there.

Further, since the inner peripheral surface of the through hole of the holding plate has a shape that can be fitted to the outer peripheral surface of the wafer whose edge has been chamfered in advance, the movement of the wafer in the thickness direction of the wafer is also achieved by this fitting. An effect is obtained in that the wafer can be regulated and the wafer can be more reliably prevented from dropping from the clamp member. In addition, a cut is made radially from the peripheral edge of the through-hole so that the peripheral edge can be bent and deformed in the plate thickness direction, and the diameter of the through-hole is increased by the bent deformation. Therefore, the work of fitting the wafer into the through hole can be easily performed.

Further, according to the above-described wafer double-sided holding plate in which the peripheral portion of the through hole is made of an elastic material such as rubber, even if there is some variation in the outer diameter of the wafer, the wafer can be held without inconvenience. In addition, the effect that the held wafer is prevented from rotating in the through-hole and the processing accuracy of the wafer can be further improved is obtained.

Also, a pair of rotating grindstones arranged with a gap smaller than the thickness of the wafer while the rotating shafts are parallel to each other, a grindstone driving means for rotating these rotating grindstones, In a processing apparatus including a holding plate and a wafer feeding unit that relatively moves the holding plate and the pair of rotating grindstones to pass a wafer through a gap between the rotating grindstones, the rotating grindstones are moved in opposite directions to each other. According to the apparatus provided with the whetstone feeding means for changing the gap size between the rotary whetstones, the effect of freely adjusting the thickness of the wafer after processing can be obtained by the change in the gap size.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view taken along line AA of FIG. 1B, and FIG. 1B is a front view of a holding plate for double-sided processing of a wafer according to the first embodiment of the present invention.

FIG. 2 is an overall plan view of the wafer processing apparatus according to the first embodiment of the present invention.

FIG. 3 is an overall front view of the wafer processing apparatus according to the first embodiment of the present invention.

FIG. 4 is an overall perspective view of the wafer processing apparatus according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional front view showing an operation table for setting the wafer on a holding plate for double-sided wafer processing.

FIG. 6 is a cross-sectional plan view showing a state where both surfaces of the wafer are simultaneously ground by the wafer processing apparatus.

7A is a cross-sectional view taken along line BB of FIG. 7B, and FIG. 7B is a front view of a holding plate for double-sided wafer processing according to the second embodiment of the present invention.

FIG. 8A is a diagram showing a shape of a wafer cut by a wire saw, and FIG. 8B is a diagram showing a wafer shape obtained by a conventional grinding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Grinding wheel stand 14 Wafer holding table 24 Grinding grindstone (rotary grindstone) 26 Rotation drive motor (grindstone drive means) 28 Grindstone feed motor (grindstone feed means) 33 Wafer feed motor (wafer feed means) 36 Wafer double-side processing holding plate 36a Inner peripheral surface of wafer holding plate for double-sided processing 38 Slit (cut) 42 Elastic body W Wafer tf Wafer outer peripheral taper surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Fumihiko Hasegawa Inventor, Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture 150, Shirakawa Plant, Shin-Etsu Semiconductor Co., Ltd. 150 Shin-Etsu Semiconductor Shirakawa Plant

Claims (5)

[Claims] 1. A holding plate for holding a wafer whose edges are chamfered when simultaneously grinding both surfaces of the wafer, wherein the outer peripheral surface of the wafer can be fitted to a plate material thinner than the wafer. A through-hole having an inner peripheral surface is provided, and a cut is made radially from the peripheral portion of the through-hole so that the peripheral portion can be bent and deformed in the plate thickness direction. A holding plate for double-sided processing of a wafer, wherein the hole diameter is increased. 2. The holding plate for double-sided processing of a wafer according to claim 1, wherein a peripheral portion of the through hole is formed of an elastic body. 3. A method for simultaneously grinding both surfaces of a wafer whose edges are chamfered, wherein a pair of rotary whetstones are formed with a gap smaller than the thickness of the wafer in a state where their rotation axes are parallel to each other. 3. The rotating whetstone is driven to rotate while the wafer is held by the wafer double-side processing holding plate according to claim 1 or 2. The wafer double-side processing holding plate is held in the gap between the rotary whetstones in this holding state. A double-sided processing method for a wafer, wherein both sides of the wafer are simultaneously brought into contact with the outer peripheral surfaces of both rotating whetstones through the wafer. 4. An apparatus for simultaneously grinding both surfaces of a wafer whose edges are chamfered, wherein a pair of rotating shafts are arranged in parallel with a gap smaller than the thickness of the wafer. 3. A rotary grindstone, a grindstone driving means for rotating and driving these rotary grindstones, and a relative movement of the holding plate for double-sided wafer processing and the pair of rotating grindstones according to claim 1 or 2 in a direction parallel to the holding plate for double-sided wafer processing. A wafer feed means for passing the wafer held by the holding plate for double-sided wafer processing through the gap between the rotary whetstones. 5. The wafer double-side processing apparatus according to claim 4, further comprising: a grinding wheel feeding unit configured to move the rotating grinding wheels in opposite directions to change a gap size between the rotating grinding wheels. Double-sided processing equipment.