SURFACE PLATE FOR POLISHING DEVICE, AND POLISHING DEVICE AND POLISHING METHOD

Abstract

The present invention relates to improvement of a surface plate to be used in a polishing apparatus, with a polishing pad to be attached on the surface plate. The surface plate of the present invention includes: a surface plate body; and a release layer including a release film or release paper formed on a surface of the surface plate body on which the polishing pad is to be attached. The release layer has a peel force of a surface thereof of 0.08 N/50 mm or more and 5.0 N/50 mm or less. The present invention can be suitably used in a polishing apparatus utilizing a general polishing pad including a pressure-sensitive adhesive. The present invention allows polishing pad fixing work and replacement work to be performed more easily than in a conventional technique.

Claims

1. A surface plate for a polishing apparatus, to be used in a polishing apparatus, with a polishing pad attached on the surface plate, comprising: a surface plate body; and a release layer including a release film or release paper formed on a surface of the surface plate body on which the polishing pad is to be attached, wherein the release layer has a peel force of a surface thereof of 0.08 N/50 mm or more and 5.0 N/50 mm or less.

2. The surface plate for a polishing apparatus according to claim 1, wherein the surface of the release layer includes a silicone-based resin, a fluorine-based resin, a long-chain alkyl-based resin, a paraffin-based resin, or an olefin-based resin.

3. The surface plate for a polishing apparatus according to claim 1, wherein the surface plate body includes stainless steel, cast iron, or ceramics.

4. The surface plate for a polishing apparatus according to claim 1, wherein the surface of the surface plate body on which the release layer is formed has a surface roughness, in terms of arithmetic average roughness (Ra), of 0.1 μm or more and 2.0 μm or less.

5. A polishing apparatus, comprising the surface plate defined in claim 1.

6. A polishing method for polishing a work with a polishing pad attached to a surface plate body, comprising: forming a release layer by fixing, to the surface plate body, a release film or release paper having a peel force of a surface thereof of 0.08 N/50 mm or more and 5.0 N/50 mm or less before attaching the polishing pad; and then polishing the work with the polishing pad attached to the release layer.

7. The polishing method according to claim 6, wherein the surface of the release film or the release paper includes a silicone-based resin, a fluorine-based resin, a long-chain alkyl-based resin, a paraffin-based resin, or an olefin-based resin.

8. The polishing method according to claim 6, wherein the polishing pad is constituted by applying a pressure-sensitive adhesive or an adhesive agent to a polishing layer.

9. The polishing method according to claim 6, wherein the polishing pad is constituted by stacking an adsorbent on a polishing layer, and the adsorbent includes a silicone composition obtained by crosslinking at least one silicone selected from a silicone including linear polyorganosiloxane having vinyl groups only at both ends, a silicone including linear polyorganosiloxane having vinyl groups at both ends and side chains, a silicone including branched polyorganosiloxane having vinyl groups only at ends, and a silicone including branched polyorganosiloxane having vinyl groups at ends and side chains.

10. The surface plate for a polishing apparatus according to claim 2, wherein the surface plate body includes stainless steel, cast iron, or ceramics.

11. The surface plate for a polishing apparatus according to claim 2, wherein the surface of the surface plate body on which the release layer is formed has a surface roughness, in terms of arithmetic average roughness (Ra), of 0.1 μm or more and 2.0 μm or less.

12. The surface plate for a polishing apparatus according to claim 3, wherein the surface of the surface plate body on which the release layer is formed has a surface roughness, in terms of arithmetic average roughness (Ra), of 0.1 μm or more and 2.0 μm or less.

13. A polishing apparatus, comprising the surface plate defined in claim 2.

14. A polishing apparatus, comprising the surface plate defined in claim 3.

15. A polishing apparatus, comprising the surface plate defined in claim 4.

16. The polishing method according to claim 7, wherein the polishing pad is constituted by applying a pressure-sensitive adhesive or an adhesive agent to a polishing layer.

17. The polishing method according to claim 7, wherein the polishing pad is constituted by stacking an adsorbent on a polishing layer, and the adsorbent includes a silicone composition obtained by crosslinking at least one silicone selected from a silicone including linear polyorganosiloxane having vinyl groups only at both ends, a silicone including linear polyorganosiloxane having vinyl groups at both ends and side chains, a silicone including branched polyorganosiloxane having vinyl groups only at ends, and a silicone including branched polyorganosiloxane having vinyl groups at ends and side chains.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 is a diagram roughly illustrating a polishing apparatus and a polishing step performed with a polishing pad.

[0041] FIG. 2 is a diagram illustrating an exemplified configuration of a surface plate included in a polishing apparatus (one-surface polishing apparatus) of First Embodiment.

[0042] FIG. 3 is a diagram roughly illustrating a configuration of a polishing apparatus (both-surface polishing apparatus) of Second Embodiment.

DESCRIPTION OF EMBODIMENTS

[0043] First Embodiment: Hereinafter a preferred embodiment of the present invention will be described. In the present embodiment, a surface plate to which a release film is bonded was produced, a commercially available polishing pad equipped with a pressure-sensitive adhesive was fixed on the surface plate in a one-surface polishing apparatus to perform polishing work, and thus, workability in replacement was examined and polish quality was evaluated.

[0044] The polishing pad used in the present embodiment was a commercially available circular polishing pad including a general-purpose suede type polishing cloth (model: 7355-000F, nap length: 450 μm, thickness: 1.37 mm). In the polishing pad, a pressure-sensitive adhesive tape was attached to the back surface.

[0045] Then, in a one-surface polishing apparatus similar to the apparatus illustrated in FIG. 1, a release film was bonded to a main body portion of a surface plate as illustrated in FIG. 2 to produce a surface plate according to the present embodiment. In the present embodiment, a plurality of types of commercially available silicone-based release films (manufactured by Fujico Co., Ltd.: product name: PET-75x1 (thickness: 75 μm)) having different peel forces were prepared to produce a plurality of surface plates, and properties of the release layers were evaluated. In the present embodiment, release films respectively having a peel force of 0.05 N/50 mm, 0.08 N/50 mm, 0.2 N150 mm, 0.95 N/50 mm, 5.0 N/50 mm, and 7.0 N/50 mm were prepared. Each of these release films was cut into the same size (ϕ800 mm) as that of the surface plate, and the resultant was adhesively bonded with an acryl-based adhesive.

[0046] The polishing apparatus and the polishing pads prepared as described above were used to conduct a polishing test with a silicon wafer (ϕ8 inches) used as a work (member to be polished). In this polishing test, the release film was adhesively fixed on the surface plate with a pressure-sensitive adhesive, and then the polishing pad was adhesively fixed on the release film to polish the silicon wafer. In this polishing test, while a polishing slurry is being supplied dropwise to the polishing pad, the polishing pad (surface plate) and the silicon wafer (head) were rotated to polish the silicon wafer. Polishing conditions employed here were as follows: [0047] Polishing slurry: slurry obtained by diluting Glanzox (manufactured by Fujimi Inc.) with pure water by 30 times [0048] Dripping speed of polishing slurry: 150 ml/min [0049] Polishing pressure: 0.163 kgf/cm.sup.2 [0050] Rotation speed of polishing pad: 45 rpm [0051] Rotation speed of head: 47 rpm [0052] Oscillation speed of head: 250 mm/min [0053] Polishing time: 3 min (per wafer)

[0054] In the polishing test of the present embodiment, after twenty-five silicon wafers were continuously polished under the above-described conditions, the polishing pad was separated by pulling from the surface plate (release film), a new polishing pad was adhesively fixed, and then, twenty-five silicon wafers were similarly continuously polished. In the present embodiment, two hundred silicon wafers in total were polished, and the polishing pad replacement work (separating work) was performed seven times. Each silicon wafer obtained after the polishing work was washed with pure water and dried, and the weight was measured with a micro-electronic balance to evaluate a polishing rate based on a weight difference caused by the polishing.

[0055] As an evaluation method employed in the polishing test, the fixed state (adhesion state) between a polishing pad and a surface plate was visually and tactilely checked in all the polishing work performed with the respective release films to examine whether or not the polishing pad was shifted or peeled. When a shift or the like of the polishing pad was found, the corresponding release film was determined to fail, and the test was abandoned.

[0056] In addition, working efficiency in the polishing pad replacement work performed seven times was also evaluated. In the present embodiment, a spring balance was used, in the replacement work, to pull an end portion of the polishing pad upward at 90 degrees, and a load applied when the polishing pad was peeled was thus measured. When the load value was 500 g or less, the working efficiency was determined as good “O”, and when the load value was over 500 g, the working efficiency was determined as poor “x”. For the evaluation of the load value, an average of measured values obtained in the replacement work performed seven times was used.

[0057] The aforementioned polishing test and evaluation were conducted on the surface plates on which the prepared seven types of release films having different peel forces were respectively fixed. Further, in the present embodiment, two types, that is, acryl-based and rubber-based, pressure-sensitive adhesives were prepared, and the polishing test was conducted with a release film fixed on the surface plate with each of the pressure-sensitive adhesives. In addition, in the present embodiment, the polishing test was conducted with a polishing pad directly adhesively fixed on a surface plate as a conventional example. Evaluation results obtained in the polishing test described above are shown in Table 1.

TABLE-US-00001 TABLE 1 Release Surface Occurrence of Evaluation of Film Plate Shift/Peel in Replacement Polishing Peel Force Fixing Polishing Efficiency Rate (N/50 mm) Method Work (Peel Load) (μm/min) 0.05 Rubber- Shifted — 0.04 based (13th pad) Acryl- Shifted — based (7th pad) 0.08 Rubber- Not ∘ 0.1 based shifted/peeled (93 g) Acryl- Not ∘ based shifted/peeled (40 g) 0.2 Rubber- Not ∘ 0.09 based shifted/peeled (175 g) Acryl- Not ∘ based shifted/peeled (86 g) 0.95 Rubber- Not ∘ 0.1 based shifted/peeled (359 g) Acryl- Not ∘ based shifted/peeled (297 g) 5.0 Rubber- Not ∘ 0.1 based shifted/peeled (483 g) Acryl- Not ∘ based shifted/peeled (457 g) 7.0 Rubber- Not x 0.09 based shifted/peeled (over 500 g) Acryl- Not x based shifted/peeled (over 500 g) — (directly Rubber- Not x 0.09 fixed) based shifted/peeled (over 500 g)

[0058] Table 1 shows that the polishing pad was neither shifted nor peeled during the polishing work and a good polishing state was obtained when the peel force of the release layer (release film) of the surface plate was 0.08 N/50 mm or more and 5.00 N/50 mm or less. Further, the peel load in the polishing pad replacement was 500 g or less in such a surface plate, and it was thus confirmed that such a surface plate is also excellent in efficiency in the replacement. It was also confirmed that the polishing work with a polishing rate equivalent to that of the conventional example can be performed in using such a surface plate.

[0059] On the other hand, when the peel force of the release layer of the surface plate was over 5.0 N/50 mm (7.0 N/50 mm), the peel load in the polishing pad replacement was over 500 g, and it was thus confirmed that such a surface plate is poor in efficiency in the replacement. In this comparative example, the polishing pad was not shifted, and the polishing rate was good, which can be the same as those in the conventional example in which the polishing pad was directly fixed on the surface plate.

[0060] When the peel force of the release layer of the surface plate was less than 0.08 N/50 mm (0.05 N/50 mm), the polishing pad was shifted during the polishing work. This problem occurred during the polishing of the first twenty-five silicon wafers, and hence the test was abandoned without performing the first replacement work. In this surface plate, the polishing rate was lower by 0.05 μm/min than that of the conventional example. It is presumed that this failure of the polishing rate was caused because the polishing pad was in an unpreferable fixed state. It is thus understood that reduction of the peel force of the surface of a surface plate also affects the polish quality.

[0061] Second Embodiment: In the present embodiment, a release layer was formed on both an upper surface plate and a lower surface plate of a both-surface polishing apparatus to perform polishing work, and thus, stability of polishing pad fixation was evaluated.

[0062] FIG. 2 is a diagram roughly illustrating the configuration of the both-surface polishing apparatus used in the present embodiment. The both-surface polishing apparatus of FIG. 2 includes an upper surface plate, a lower surface plate, a rotating shaft for rotatively driving these surface plates. In polishing work with the both-surface polishing apparatus, a polishing pad is attached and fixed on each of the surface plates, and a work (member to be polished) fixed with a carrier is inserted between the surface plates to perform polishing. Gears are formed on outer peripheries of the carrier and the rotating shaft, so that the carrier can be also rotatively driven by driving the rotating shaft.

[0063] In the present embodiment, a release film used as a release layer was attached to a main body portion of each of the upper surface plate and the lower surface plate to produce a surface plate of the present embodiment. The release film was a silicone-based release film (manufactured by Fujico Co., Ltd.: product name: PET-75x1 (thickness: 75 μm)), and had a peel force of 0.2 /50 mm. A polishing pad was fixed to the surface of the release layer. The polishing pad used in the present embodiment was a general-purpose urethane type (CeO.sub.2) circular (donut-shaped) polishing pad, and an acryl-based pressure-sensitive adhesive tape was attached to the back surface. As the size of the surface plates, both the upper and lower surface plates had a fixing surface of ϕ680 mm, and the polishing pad had an outer diameter of the same size.

[0064] Then, the polishing apparatus and the polishing pad described above were used to conduct a polishing test with a glass wafer (ϕ8 inches) used as a work. In this polishing test, the polishing pads were adhesively fixed on the surface plates having the release films adhesively fixed thereon to polish the silicon wafer. In the polishing step, the silicon wafer was polished by rotating the upper and lower polishing pads and the silicon wafer while a polishing slurry was being supplied through a large number of supply ports (not shown) provided on the upper surface plate. Polishing conditions employed here were as follows: [0065] Polishing slurry: SHOREX FL-2 (manufactured by Showa Denko K.K.) [0066] Amount of polishing slurry supplied: 5 l/min [0067] Polishing pressure: 0.48 Kgf/cm.sup.2 [0068] Rotation speed of surface plates: 40 rpm for upper and lower plates

[0069] In the polishing test of the present embodiment, the polishing was performed for 80 hours under the above-described conditions, and the polishing work was stopped after the polishing of 5 hours, 10 hours, 20 hours, and 40 hours to measure peel forces of the polishing pads against the upper and lower surface plates. In the present embodiment, a tension load cell equipped with a hook was hooked on an end portion of the polishing pad to pull it upward at 90 degrees, and a load applied when the polishing pad was peeled was defined as the peel force. For this measurement, a loop to be hooked was attached to a part of the outer periphery of the polishing pad. After measuring the peel force, the polishing pads were attached to the surface plates again to continue the polishing work. The measurement of the peel force and the polishing work were thus repeated, and the polishing was performed until 80 hours elapsed. Measurement results obtained in this evaluation test are shown in Table 2.

TABLE-US-00002 TABLE 2 Polishing Pad Peel Force (kg) 5 hours 10 hours 20 hours 40 hours 80 hours Upper Surface 3.3 3.2 3.5 4.3 4.2 Plate Lower Surface 3.1 3.5 3.8 4.1 4.3 Plate

[0070] It can be confirmed, based on Table 2, that the peel forces of the polishing pads measured after elapse of the respective times are stable in the surface plate including the peel layer of the present embodiment. According to the surface plate of the present embodiment, a work can be polished without peeling or shifting a polishing pad during the polishing work performed for 80 hours. In this polishing test, it is probably because of accumulation of pressing time that the peel force of the polishing pad increased as the polishing time was increased. When the polishing pad was separated from the surface plate after the polishing test, however, the polishing pad could be detached/attached without special difficulty, and no adhesive remained on the surface of the surface plate.

[0071] As described so far, it was confirmed that when a peel layer of a surface plate is provided with a proper peel force, stable polishing can be performed during polishing work, and that a polishing pad can be easily detached/attached after the work. When the surface of the work was observed after the polishing test, a good polished surface having neither a polishing scratch nor waviness/distortion was obtained.

INDUSTRIAL APPLICABILITY

[0072] As described above, since a surface plate for a polishing apparatus according to the present invention includes a release layer including a release film or the like, workability for fixing/replacing a polishing pad to be fixed with a pressure-sensitive adhesive is improved. The present invention is useful in a polishing step for a semiconductor wafer, a glass substrate for a display or a substrate for a hard disc.