JP2000042910A - Workpiece holder for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a workpiece holder for polishing which obtains a workpiece having smaller peripheral sags or a so-called center-recessed condition than former holder has. SOLUTION: In this, workpiece holder for, a template 1 for openedly providing a recessed hole 1a fittedly engaged by a workpiece, and a packing material 2 composed of an elastic body for holding the workpiece are fixed with each other. At that time, the recessed hole peripheral edge vicinities of the timplate 1 and the packing material 2 are formed, so that the unsteaby deformation of the packing material 2 in nearby the recessed hole periphery at the time of abrasion can be absorbed with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a workpiece holder for polishing, such as a semiconductor wafer, an interlayer insulating film of a semiconductor device, a metal wiring, a memory disk, and an LCD glass, which requires precise planar polishing.

[0002]

2. Description of the Related Art A semiconductor wafer, an interlayer insulating film and a metal wiring of a semiconductor device, a memory disk, an LCD glass, and the like are polished by a polishing machine.

The polishing machine has an upper surface plate and a lower surface plate, each of which has a mechanism for rotating and rotating and revolving. A polishing pad is adhered to the lower surface plate, and a workpiece is held on the upper surface plate by a workpiece holder for polishing. Then, the work is pressed against the polishing pad, a polishing liquid containing abrasive grains is supplied between the two, and the work is performed by sliding the work and the polishing pad mutually.

As shown in FIGS. 5 to 7, a conventional workpiece holder for polishing has a circular (or square) template 31 provided with a recess hole 31a into which a workpiece is fitted. . A backing material 33 is attached via an adhesive 32 to the entire surface of the template 31 attached to the upper surface plate.

[0005] As the backing material 33, a polymer elastic foam suitable for holding the workpiece fitted into the recess hole 31a of the template is used. The backing material
Numeral 33 fixes the workpiece by being strongly pressed through the liquid such as water and adsorbed on the workpiece. This backing material 33 is reinforced by a support material 35 via an adhesive 34. Further, on the back surface of the support material 35, an adhesive layer is provided.
36 and release paper 37 are sequentially laminated.

The workpiece holder for polishing is used by peeling off the release paper 37 and affixing it to the upper surface plate with an adhesive layer 36. At this time, the backing material 33 is impregnated with a liquid such as water, and the workpiece is fitted into the recess hole 31a of the template 31 and held by the backing material 33. In this state, a polishing pad (not shown) such as a cloth or a foam body capable of holding a polishing liquid is adhered to the lower surface plate, and a predetermined polishing pad is brought into contact with a surface of the workpiece to be polished. Then, by rotating the upper surface plate and the lower surface plate, respectively, the polishing liquid is held by the polishing pad and the surface of the workpiece is polished.

A workpiece holder for holding a workpiece is used by being attached to an upper surface plate. At this time, the workpiece held by the polishing workpiece holder is rotated by the rotation of the upper surface plate, and the workpiece is rotated in the rotation direction of the upper surface plate in the recess hole 31a of the template 31. Try to move. Therefore, the backing material 33 near the peripheral edge of the recess hole 31a is subjected to a rotational force acting near the peripheral edge of the workpiece to apply a force to escape to the outer peripheral portion.

However, since the backing material 33 is adhered to the entire surface of the template 31 via the adhesive 32,
As shown in FIGS. 8 and 9, an unsteady deformation portion 39 is formed in the backing material 33 near the periphery of the recess hole 31a due to the concentration of stress on the outer peripheral portion of the workpiece.

That is, local unsteady deformation occurs in the backing material 33 near the peripheral edge of the recess hole 31a as compared with a portion other than the vicinity of the peripheral edge.
The polishing pressure applied to the vicinity of the peripheral portion varies more than the polishing pressure applied to the workpiece 38 in a portion other than the vicinity of the peripheral portion. That is, an uneven pressure distribution is formed on the fitting surface of the recess hole 31a into which the workpiece is fitted, and the unsteady deformed portion 39 is generated.

For example, as shown in FIG.
The vicinity of the periphery of the workpiece rises and is deformed unsteadily in comparison with the backing material other than the vicinity of the periphery, whereby the polishing pressure applied to the vicinity of the periphery of the workpiece causes the processing of parts other than the vicinity of the periphery to be processed. The polishing pressure may be increased as compared with the polishing pressure applied to the object. Since such a phenomenon occurs, polishing is promoted in the vicinity of the peripheral portion of the workpiece after polishing, whereby the vicinity of the peripheral portion of the surface of the workpiece may be sagged.

As shown in FIG. 9, the backing material 33 near the periphery is depressed as compared with the backing material other than the vicinity of the periphery, and the backing material 33 originally allows deformation to hold the workpiece. Unsteady deformation may occur beyond the range. Since such a phenomenon occurs, the peripheral edge of the surface of the workpiece may be in a so-called center concave state (a state in which the center is recessed and the end is raised), in which the removal amount of polishing is smaller than that in the center.

Even if the sagging or the so-called center concave state is removed by re-polishing, there is a problem that the uneven undulation over the entire surface of the workpiece is not eliminated and the polishing accuracy of the workpiece is reduced.

Further, a recess hole due to stress concentration of the workpiece 38.
The unsteady deformation part 39 is formed on the backing material 33 near the periphery of 31a.
Is generated, the elasticity is reduced, the original holding force of the backing material is lost, and the workpiece is recessed 31a during polishing.
There is also a problem that the workpiece may be damaged and the workpiece may be damaged or the surface plate of the polishing machine may be damaged.

To address the above problem, the following method is conceivable. One method is to make the outer diameter of the recess hole larger than that of the workpiece. If the outer diameter of the recess hole is larger than the workpiece, the backing material in contact with the periphery of the workpiece has a distance between the recessed hole and the bonded portion of the backing material, so the vicinity of the peripheral edge of the workpiece Good polishing accuracy can be maintained without causing unsteady deformation of the backing material facing this portion due to the stress concentration. However, in this case, since the outer diameter size of the recess hole is larger than the workpiece, the workpiece is not sufficiently held during polishing and is shifted, and the workpiece drops from the recess hole 31a and the workpiece is damaged. There is a disadvantage in that damage such as dripping or damaging the surface plate of the polishing machine occurs.

Another method is to reduce the compressive elasticity of the backing material to cope with an unsteady deformation state of the backing material facing this part due to stress concentration near the peripheral edge of the workpiece. If the compression elasticity of the backing material is low, the unsteady deformation portion of the backing material facing the above-mentioned portion due to stress concentration of the workpiece near the peripheral edge of the recess hole becomes small, and good polishing accuracy can be maintained. But,
In this case, the absorbability of the backing material to the work to be essentially possessed is impaired, and the ability of the backing material to hold the work becomes insufficient, so that the work falls off from the recess hole 31a, There is a defect that the workpiece is damaged, and the backing material cannot absorb the vibration of the polishing machine, and the surface of the workpiece is damaged such as scratches and haze.

[0016]

SUMMARY OF THE INVENTION Therefore, the present invention
An object of the present invention is to provide a workpiece holder for polishing which can obtain a workpiece having less peripheral sag and a so-called center concave state than before.

[0017]

In order to solve the above-mentioned problems, the present invention employs the following technical means. A workpiece holder for polishing according to the present invention is a polishing tool in which a template having a recess hole into which a workpiece is fitted, and a backing material made of an elastic body for holding the workpiece are fixed to each other. In the workpiece holder for use, the gap between the template and the backing material near the periphery of the recess hole is unsteady deformation of the backing material near the periphery of the recess hole at the time of polishing (for example, the backing material is raised or depressed. ) Can be absorbed.

The workpiece holder for polishing is formed so that the gap between the template and the backing material near the peripheral edge of the recess hole can absorb the unsteady deformation of the backing material near the peripheral edge of the recess hole during polishing. Therefore, it is possible to suppress unevenness in the polishing pressure distribution applied to the vicinity of the peripheral edge of the workpiece due to the unsteady deformation of the backing material. By adhering the template and the backing material together with other portions except for an annular portion having a predetermined width near the periphery of the recess hole, a gap between the template and the backing material near the periphery of the recess hole during polishing is reduced. The unsteady deformation of the backing material in the vicinity of the periphery of the recess hole may be absorbed.

As described above, the template and the backing material are integrally bonded to each other except for an annular portion having a predetermined width near the peripheral edge of the recess hole, so that the stress near the peripheral edge of the recess hole due to stress concentration of the workpiece. The unsteady deformation state of the backing material can be reduced, and the unsteady deformation of the backing material near the periphery of the recess hole during polishing can be absorbed.

If the outer diameter of the recess hole is set to be equal to or slightly larger than that of the workpiece, it is possible to prevent the workpiece from being damaged due to falling off. The template and the backing material may be point-adhered to an annular portion having a predetermined width near the periphery of the recess hole. Even with such a configuration, it is possible to absorb the unsteady deformation of the backing material near the periphery of the recess hole due to the stress concentration of the workpiece during polishing.

A plurality of recess holes may be formed in the template. This method of polishing a workpiece is a method of polishing a workpiece to bring a processing surface of the workpiece into sliding contact with a polishing pad provided on a polishing platen, and a holder for polishing the workpiece. Then, the above-mentioned workpiece holder for polishing is used.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

The workpiece holder for polishing according to this embodiment comprises:
This is a workpiece holder for polishing, which slides a processing surface of a workpiece on a polishing pad provided on a polishing platen. And it is used, for example, when polishing a disk-shaped workpiece.

As shown in FIGS. 1 and 2, the workpiece holder for polishing has a template 1 having a circular recess hole 1a. The template 1 is made of a material having excellent toughness and abrasion resistance.
Except for an annular portion X having a predetermined width near the periphery of the recess hole 1a of the template 1, other portions are integrally bonded.
It is adhered by the adhesive layer 3.

A support material 5 is adhered to the back surface of the backing material 2 via an adhesive layer 4, and a release paper 7 is adhered to the back surface of the support material 5 via an adhesive layer 6. . The backing material 2 is made of a macroporous foamed polymer having fine voids inside.

The template 1 is made of an engineering plastic having excellent toughness and abrasion resistance. In addition to a semi-rigid material such as polycarbonate, hard polyurethane, hard vinyl chloride, hard polyethylene, etc., a hardened filled resin composite material is sorted. Etc. can also be used.

Recess hole 1a opened in template 1
Is not limited to one and may be plural. Recess hole
1a is generally circular and is determined according to the size of a workpiece having a diameter of, for example, 200 mm or 300 mm. Further, it may be a quadrangle of a triangle, a rectangle, or a square, a polygon of five or more, or a star.

The predetermined width in the vicinity of the periphery of the recessed hole 1a of the template 1, which is the non-adhesive portion, is 0.1 to less than the recessed hole width.
It is preferable to configure so as to be about 2.5%. 0.1
%, The backing material 2 in the vicinity of the peripheral edge of the recess hole is subjected to stress concentration of the workpiece, causing unsteady deformation, and the surface shape of the workpiece after polishing tends to be in a sagging state. is there. On the other hand, if it is more than 2.5%, the adhesion between the template 1 and the backing material 2 may be broken due to the impact due to the collision of the workpiece near the periphery of the recess hole 1a of the template during the polishing, and the template may be damaged. There is.

The sheet material comprising the adhesive layer 4, the support material 5, the adhesive layer 6, and the release paper 7 is a double-sided adhesive tape in which an adhesive is impregnated into a nonwoven fabric, or a sheet material comprising an adhesive layer and an adhesive layer. It may be.

The template 1 is made of a material having excellent toughness and wear resistance. For example, fibrous fillers and high-toughness engineering plastics, highly functional inorganic fibers such as thermosetting resins and carbon fibers, and highly wear-resistant fibers such as Kevlar (trademark of DuPont) fibers and plastics, resins, or synthetic rubbers There are composites, these matrix substances alone and calendered ones. The recess hole is provided by, for example, end milling.

As the material of the template, a material having appropriate physical properties is selected in consideration of the material of the work and the surface dimensions, thickness, and shape. However, when the work is a semiconductor wafer, the bending strength is 40.0 to 400.0. Kgf / mm ² range, tensile strength
The range of 20.0 to 200.0 kgf / mm ² is desirable, and heat resistance and abrasion resistance, that is, resistance to so-called microtremor repeated impact wear is important. As for this resistance, a material having a large cumulative impact energy until breaking was given a good result by repeatedly performing a falling ball impact test at a small energy level using a falling ball impact tester.

The backing material 2 may be any material capable of adsorbing and holding the workpiece when the workpiece is strongly pressed by interposing a liquid such as water on the surface. The backing material 2 comprises a support material 5 and an adhesive layer 4.
However, a predetermined foamed composition may be directly provided on the support member 5 and integrally formed by a wet coagulation method.

Next, a method of manufacturing the workpiece holder for polishing according to this embodiment will be described. In the holder for a workpiece to be polished shown in FIGS. 1 and 2, first, a backing material 2 is laminated on a support material 5 via an adhesive layer 4, and a template 1 is placed on the laminate.
Can be formed by integrally bonding the template 1 and the backing material 2 via the adhesive layer 3 except for an annular portion X having a predetermined width near the peripheral edge of the recess hole 1a. .

The holder for workpieces for polishing shown in FIGS. 3 and 4 has a backing material 2 on a support 5 via an adhesive layer 4.
And the template 1 and the template 1 and the backing material 2 are removed from the laminate except for an annular portion X having a predetermined width near the peripheral edge of the recessed hole 1a (the small holes H, H,... Excluding, that is, the small holes H, H, ... are point-like bonded),
The other parts can be formed by integrally bonding through the adhesive layer 3.

[0035]

Next, the configuration of the present invention will be described more specifically.

A workpiece holder for polishing was manufactured and evaluated as follows. Example 1 A circular plate made of glass epoxy (thickness 65)
0 μm, diameter 570 mm, manufactured by Shinko Chemical Co., Ltd., trade name S
L-EC (H)), recess hole (200mm in diameter)
The circular portions (202 mm in diameter) having the same central point as each of the recess holes were masked with a mold release material at three predetermined portions where should be provided.

After a double-sided adhesive tape (manufactured by Nippon Matai Co., Ltd., L-Fan) was attached to the glass epoxy circular plate-like material with a heat roller, a recess hole was formed by end milling. A template to which a double-sided adhesive tape was attached was obtained.

A backing material (trade name: NF-200, manufactured by Rodale Nitta Co., Ltd.) having a fine foam structure on the side for receiving a workpiece into the recess hole is cut out to a diameter of 572 mm, and a polyester sheet is used as a core material. An adhesive tape (manufactured by Sumitomo 3M Ltd., trade name # 442) was bonded to the support material side of the backing material by a heat roller.

The template with the double-sided adhesive tape adhered thereto and the backing material are bonded together by using a hot press.
A workpiece holder for polishing as shown in FIGS. 1 and 2 was obtained.

Using this workpiece holder for polishing, a single-side polishing machine (trade name: SPM-23, manufactured by Fujikoshi Machinery Co., Ltd., carrier plate: 560 mm diameter processing) was used for polishing. The workpiece is a silicon single crystal P (100) wafer 8
The polishing conditions were as follows (1) to (4). (1) Holder mounting method: The holder was adhered to the carrier plate with a double-sided adhesive tape on the holder support surface. (2) Primary polishing: polishing cloth (SUBA800), polishing slurry (NALCO235O, 20-fold dilution), processing pressure (300 g / cm ² ), slurry flow rate (500 ml / m)
in), processing time (30 min). (3) Secondary polishing: polishing cloth (MHS15A), polishing slurry (LS10, 13-fold dilution), processing pressure (150 g /
cm ² ), slurry flow rate (500 ml / min), processing time (5 min). (4) Tertiary polishing: polishing cloth (UR100), polishing slurry (LS11, 13-fold dilution), processing pressure (100 g / c)
m ² ), slurry flow rate (500 ml / min), processing time (5 min).

The shape accuracy of the polished wafer was evaluated using a capacitance type wafer flatness inspection machine (ADE9500 wafer flatness inspection meter).

Then, the TTV which is the difference between the maximum value and the minimum value of the thickness in the flatness adaptation region of the wafer is 0.30 μm, 1
The flatness (STIR) of the site within 5 mm square is 0.
It was as good as 20 μm. Further polishing,
1548 sheets could be processed without lowering the polishing accuracy to the end. For the first time after 1548 sheets, damage (template cracking) occurred at the periphery of the recess hole. (Example 2) In the same manner as in Example 1, a circular portion having a diameter of 204 mm and having the same center point as the recess hole was masked with a release material, and a double-sided adhesive tape was placed on a glass epoxy circular plate from above with a hot roller. Then, a workpiece holder for polishing as shown in FIGS. 1 and 2 was prepared using a template in which a recess hole was formed by end milling.

When the wafer was polished under the same polishing conditions as in Example 1, the TTV was 0.30 μm and the STTV within a 15 mm square was
The IR was as good as 0.30 μm. When the polishing was further performed, 1500 sheets could be processed without lowering the polishing accuracy to the end. For the first time after polishing 1500 sheets, damage (crack of the template) occurred at the periphery of the recess hole. (Embodiment 3) As in the above embodiment, a circular portion having a diameter of 202 mm and the same center point as the recess hole is formed at a pitch of 0.6 m.
mask with a mold release material with a hole of 0.2 mm in diameter,
After bonding a double-sided adhesive tape to a glass epoxy circular plate from above using a hot roller, using a template with a recess hole by end milling,
A workpiece holder for polishing as shown in FIGS. 3 and 4 was produced.

When the wafer was polished under the same polishing conditions as in Example 1, the TTV was 0.25 μm and the STTV within a 15 mm square was
The IR was as good as 0.20 μm. Further polishing was performed, and 1608 wafers could be processed without lowering the polishing accuracy to the end. For the first time after polishing of 1608 wafers, damage (warp of the template) occurred at the periphery of the recess hole, and the wafer dropped off. (Comparative Example 1) A circular plate made of glass epoxy similar to that of the above example was prepared, and a double-sided adhesive tape was attached to the entire surface of the circular plate made of glass epoxy using a heat roller, and then end milled. 5 and 6, a workpiece holder for polishing was manufactured as shown in FIGS. 5 and 6. It should be noted that, unlike the above embodiment, no masking with a release material is performed. Accordingly, there is no non-contact area of a predetermined annular width around the periphery of the recess hole between the template and the backing material.

When the wafer was polished under the same polishing conditions as in Example 1, the TTV was 0.43 μm and the STTV within a 15 mm square was
When the IR was 0.55 μm, the desired wafer processing accuracy in the main polishing could not be achieved. When the polishing is further performed sequentially, the polishing accuracy can be reduced to one without lowering to the end.
260 sheets could be processed. For the first time after polishing 1260 wafers, damage (edge shaving) occurred at the peripheral edge of the recess, and the wafer dropped off. (Comparative Example 2) Diameter 206 having the same center point as the recess hole
mm circular part is masked with a release material, a double-sided adhesive tape is bonded to a glass epoxy circular plate using a heat roller, and then used for polishing using a template with recessed holes formed by end milling. A workpiece holder was produced. In this comparative example, the area of the peripheral edge of the recess hole between the template and the backing material, which is not in contact with a predetermined annular width, is set to be considerably larger than in the first embodiment.

When the wafer was polished under the same polishing conditions as in Example 1, the TTV was 0.41 μm and the ST
When the IR was 0.40 μm, the desired wafer processing accuracy in the main polishing could not be achieved. When the polishing is further performed sequentially, the polishing accuracy can be reduced to one without lowering to the end.
164 sheets could be processed. For the first time after polishing 1164 wafers, damage (edge cracking) occurred at the peripheral edge of the recess, and the wafer dropped off.

As described above, the workpiece holder for polishing of this embodiment can absorb the unsteady deformation of the backing material near the peripheral edge of the recess hole due to the stress concentration of the workpiece during polishing. Is uniformly formed over the entire surface to be processed, the flatness after polishing is greatly improved compared to the past, and the workpiece with good polishing accuracy with less peripheral sagging and so-called center concave state can be stably produced. It has the advantage that it can be polished. Therefore, it is suitable for manufacturing an ultra-precision flattened and polished workpiece, and it is possible to supply a highly flat workpiece having a TTV value of 0.3 μm or less.

Also, the short life due to the breakage of the template of the workpiece holder for polishing can be overcome, the usable life can be extended and the frequency of replacement can be reduced, and the polishing operation efficiency is improved and the economy is excellent. There is.

[0049]

The present invention is configured as described above and has the following effects.

The unevenness of the polishing pressure distribution in the vicinity of the peripheral edge of the workpiece due to the unsteady deformation of the backing material can be suppressed, so that the workpiece having less peripheral sagging and a so-called concave state than before can be obtained. Thus, a workpiece holder for polishing can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating an embodiment of a workpiece holder for polishing according to the present invention.

FIG. 2 is a view of the polishing work holder of FIG. 1 as seen from the direction of arrows II-II.

FIG. 3 is a plan view illustrating another embodiment of the workpiece holder for polishing according to the present invention.

4 is a view of the workpiece holder for polishing shown in FIG.

FIG. 5 is a plan view illustrating a conventional workpiece holder for polishing.

6 is a view taken along line VI-VI of the workpiece holder for polishing shown in FIG. 5;

7 is a perspective view illustrating a structure of a template and a backing material of the workpiece holder for polishing shown in FIG. 5;

8 is a view taken along the line VI-VI for explaining unsteady deformation (raising) of the backing material generated in the workpiece holder for polishing shown in FIG. 5;

9 is a view taken along the line VI-VI for explaining unsteady deformation (recession) of the backing material generated in the workpiece holder for polishing shown in FIG. 5;

[Explanation of symbols]

 1 Template 1a Recessed hole 2 Backing material X Annular part

Claims (5)

[Claims] 1. A polishing work holder, in which a template having a recess hole into which a work is fitted and a backing material made of an elastic body for holding the work are fixed to each other. A polishing cover formed between the template and the backing material so as to absorb unsteady deformation of the backing material near the periphery of the recess during polishing. Workpiece holder. 2. The method according to claim 1, wherein the template and the backing material are integrally bonded to each other except for an annular portion having a predetermined width near the periphery of the recess. 2. The workpiece holder for polishing according to claim 1, wherein the gap can absorb unsteady deformation of the backing material near the periphery of the recess hole during polishing. 3. The polishing workpiece holder according to claim 2, wherein the template and the backing material are point-adhered to an annular portion having a predetermined width in the vicinity of the periphery of the recess hole. 4. The workpiece holder for polishing according to claim 1, wherein a plurality of recess holes are formed in the template. 5. A method for polishing a workpiece to bring a processing surface of the workpiece into sliding contact with a polishing pad provided on a polishing platen, the method comprising: Item 5. A method for polishing a workpiece, comprising using the workpiece holder for polishing according to any one of Items 1 to 4.