JP2017177314A - Adsorption film and abrasive pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorption film capable of properly maintaining an amount of sinking against stress in polishing although reducing it, and an abrasive pad comprising the adsorption film.SOLUTION: An adsorption film F is composed of a soft plastic sheet where a skin layer Shaving fine pores on a surface, and a fine foam layer Shaving foams larger than the fine pores of the skin layer Sinside are formed. Then the adsorption film F has a thickness of 50-200 μm and resin used for the adsorption film has a 100% modulus of 20-50 MPa.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an adsorption film and a polishing pad, and more particularly to an adsorption film for fixing an object to be held such as a polishing pad, a holding pad and a holder to a surface plate, and a polishing pad provided with the adsorption film.

Conventionally, a polishing apparatus for polishing an object to be polished such as a glass plate or a semiconductor substrate includes a pair of opposing holding surface plates and a polishing surface plate, holds the object to be polished on the holding surface plate side during polishing, and polishes A polishing pad is fixed on the surface plate side.
Here, the holding surface plate may include a holding pad for sucking and holding the object to be polished and a holding tool provided with a frame member having at least one through hole on the outer periphery of the holding pad. .
Conventionally, when a held object such as a polishing pad, a holding pad, or a holding tool is fixed to the holding surface plate or the polishing surface plate, it is fixed using a double-sided tape. However, when replacing the object to be held from the surface plate, there is a problem that the adhesive of the double-sided tape remains on the surface plate, and the replacement work becomes complicated.
For this reason, in order to prevent the adhesive from remaining on the holding surface plate, it is constituted by a soft plastic sheet having a surface layer, and the surface layer is held in close contact with the holding surface plate using the surface tension of water. A pad is disclosed (Patent Documents 1 and 2).

Japanese Patent No. 4034320 Japanese Patent No. 4889507

In the holding pads described in Patent Documents 1 and 2, since the surface layer of the soft plastic sheet is adsorbed by water on the holding surface plate side, the problem of adhesive residue of the adhesive layer on the holding surface plate is solved.
However, Patent Documents 1 and 2 do not specifically disclose the thickness of the holding pad, but if the thickness exceeds 0.3 mm, the holding pad holds the holding pad during polishing. The holding pad sinks excessively when the object to be polished is pressed against it. As a result, the shape of the end of the object to be polished is deteriorated, and it cannot cope with the recent increase in demand for flatness. On the other hand, for example, when the soft plastic sheet of the holding pad described in Patent Documents 1 and 2 is used as an alternative to the double-sided tape for attaching the polishing pad to the polishing surface plate, the adhesive is applied to the polishing surface plate. Although the problem of residual glue residue is solved, when the thickness is large, the polishing pad is excessively deformed by pressing the workpiece against the polishing pad during polishing, and the shape of the end of the workpiece The problem of worsening occurred.
Furthermore, when the soft plastic sheet of the holding pad described in Patent Documents 1 and 2 is used for holding the holder, the problem of adhesive residue is solved, but the soft plastic sheet is thick. The portion of the soft plastic sheet where the frame material of the holder is fixed is excessively compressed, and the compression characteristics change over time, resulting in a problem that the end shape of the workpiece deteriorates over time. .

In order to solve the above-mentioned problem of sinking, it is conceivable to reduce the thickness of the soft plastic sheet. However, in Patent Document 1, the thickness of the film formed when the soft plastic sheet is produced in order to reduce the thickness. When the thickness was lowered, the size of the foam having a substantially triangular cross section was reduced, and the film formability was deteriorated.
Further, when the film thickness is reduced in order to reduce the thickness of the soft plastic sheet described in Patent Document 2, the foam size is uniform, but the modulus of the resin used is 20 MPa or less, so it is too soft. The processability was poor and a thin sheet could not be obtained.
In addition, after the production of a soft plastic sheet with a certain film thickness, it is possible to reduce the thickness by grinding such as buffing, but it is difficult to perform buffing due to the softness, so the flatness of the sheet was maintained. It was difficult to reduce the thickness to 0.3 mm or less.
In view of such a problem, it is an object of the present invention to provide an adsorption film that can be appropriately held on a surface plate while reducing the sinking amount with respect to stress during polishing, and a polishing pad provided with the adsorption film.

That is, the adsorption film according to the invention of claim 1 is an adsorption film composed of a soft plastic sheet in which a skin layer having micropores on the surface and a microfoaming layer having bubbles larger than the micropores of the skin layer are formed inside. A film,
The thickness is 50 to 200 μm, and the 100% modulus of the resin used for the adsorption film is 20 to 50 MPa.

The polishing pad according to the invention of claim 4 is a polishing pad for polishing an object to be polished.
The adsorption film according to claim 1 is provided on a surface of the polishing pad on the side of the polishing platen fixed.

  According to the first aspect of the present invention, by setting the thickness of the adsorption film to 50 to 200 μm and the 100% modulus of the resin to be used to 20 to 50 MPa, sinking during polishing can be suppressed. An appropriate polishing pressure can be applied to the object to be polished. Further, even if the thickness is relatively small, it is possible to ensure the adsorption performance, and it is difficult to cause peeling from the surface plate.

  According to the invention of claim 5, by setting the thickness of the adsorption film to 50 to 200 μm and the 100% modulus of the resin to be used to 20 to 50 MPa, sinking during polishing can be suppressed, An appropriate polishing pressure can be applied to the object to be polished. Further, even if the thickness is relatively thin, it is possible to ensure the adsorption performance, and it is possible to make it difficult to peel off from the polishing surface plate.

Schematic diagram of the polishing apparatus according to this example Enlarged sectional view of the polishing surface plate and holding surface plate

1 is a schematic view of a polishing apparatus 2 for polishing an object to be polished 1. The polishing apparatus 2 is positioned above and a holding tool 3 for holding the object to be polished 1 is fixed. A holding surface plate 4, a polishing surface plate 6 that fixes a polishing pad 5 that is positioned below and to be held, and a slurry supply means 7 that supplies slurry between the polishing object 1 and the polishing pad 5. And.
The object to be polished 1 may be a silicon wafer, an optical lens, a compound semiconductor such as SiC or sapphire, and may be an object to be polished 1 made of metal, plastic, or ceramic.
The holding surface plate 4 and the polishing surface plate 6 each have a substantially disk shape, and are rotated in opposite directions by driving means (not shown), and the holding surface plate 4 can be moved up and down. Is provided.
When the polishing process is performed, the holding surface plate 4 rotates relatively while pressing the object to be polished 1 against the polishing pad 5 on the upper surface of the polishing surface plate 6, and the slurry supply means 7 removes the slurry from the surface to be polished. It supplies between the thing 1 and the polishing pad 5. FIG.
As the slurry supplied by the slurry supply means 7, a conventionally known material can be used according to the object to be polished 1 and the required processing accuracy.

FIG. 2 is an enlarged cross-sectional view of the holding surface plate 4 and the polishing surface plate 6, and the holder 3 that holds the object to be polished 1 on the holding surface plate 4 adsorbs the object to be polished 1. A holding sheet 11 to be held, a frame member 12 provided so as to surround the holding sheet 11, and a double-faced tape T on the opposite side to the surface of the frame member 12 and the holding sheet 11 that holds the workpiece 1. It is comprised from the adsorption | suction film F adhere | attached and fixed via.
As the holding sheet 11, a soft plastic sheet or a polyurethane foam can be used. Specifically, a soft urethane sheet or a polyurethane foam molded by a molding method can be used, and the thickness thereof is 0.5. About 2.0 mm can be used.
The inside of the soft plastic sheet constituting the holding sheet 11 has innumerable air bubbles are formed, a skin layer S ₂ having a thickness of several μm to microporous not shown on the surface of the workpiece 1 side is formed , located inside the said skin layer S ₂ and a the microporous nap large elongated bubbles b1 is formed from layers N, Vertical bubble b ₁ and vertically elongated bubbles adjacent but not shown in the nap layer N b ₁ communicates with each other to form a three-dimensional network structure.
Next, the polishing pad 5 fixed to the polishing surface plate 6 is composed of a polishing sheet 13 for polishing the workpiece 1 and an adsorption film F bonded and fixed by the polishing sheet 13 and a double-sided tape T. ing.
As the polishing sheet 13, a conventionally known one can be used. For example, a polyurethane resin-impregnated nonwoven fabric or a polyurethane foam is used, and a thickness of about 0.5 to 2.0 mm is used. it can. Further, a groove may be formed on the polishing surface of the polishing pad 5 on the object to be polished 1 side as necessary.
And as the double-sided tape T which adhere | attaches the said holding | maintenance sheet | seat 11 and the polishing sheet 13 to the said adsorption | suction film, what apply | coated the adhesive to the both surfaces of the base material made from PET can be used, for example. The total thickness is about 50 μm.

Hereinafter, the adsorption film F constituting the holder 3 and the polishing pad 5 will be described. As the adsorption film F, a soft urethane sheet having a thickness of about 50 to 200 μm can be used.
The soft urethane sheet constituting the adsorbing film F is composed of a skin layer S ₂ having a thickness of several μm with micropores (not shown) formed on the surface thereof, and bubbles b larger than the micropores located inside the skin layer S _{2. 2} and a fine foam layer S ₁ formed thereon.
In the fine foam layer S ₁ , although not shown, adjacent bubbles b ₂ and bubbles b ₂ communicate with each other to form a three-dimensional network structure.
The skin layer S ₂ adsorption film F that constitute the retainer 3 is oriented to the retaining plate 4 side, the double-sided tape T is adhered to the surface opposite to the skin layer S in the adsorption film F It is like that.
Similarly, in the polishing pad 13, the skin layer S ₂ of the adsorbent film F is provided so as to face the polishing platen 6 side, the side opposite to the skin layer S ₂ in the adsorption film F above The double-sided tape T is adhered to the polishing sheet 13.

By using the adsorption film F having the above configuration, the holder 3 and the polishing pad 5 can be attached to the holding surface plate 4 and the polishing surface plate 6 as follows, and these can be easily replaced. Can do.
First, when the holder 3 is mounted on the holding surface plate 4, water is contained in the skin layer S ₂ of the adsorption film F constituting the holder 3, and this is brought into close contact with the holding surface plate 4. Then, the holder 3 can be fixed to the holding surface plate 4 by the surface tension of the water that has entered the micropores.
Thereafter, moistened with water in the skin layer S ₂ of the holding sheet 11, by pressing in the object to be polished 1 which can hold a holding sheet 11 and the workpiece 1 by the surface tension, the The polished article 1 is held by the holding surface plate 4.
When the polishing of the workpiece 1 is completed, the workpiece 1 can be removed from the holding sheet 11, and only the water is interposed between the holding sheet 11 and the workpiece 1 at that time. The pressure-sensitive adhesive does not remain on the surface of the holding pad 11 or the object to be polished 1 and the object to be polished 1 can be replaced quickly.
Further, when the holder 3 is replaced after the plurality of objects to be polished 1 are polished, the holder 3 is detached from the holding surface plate 4 by peeling the adsorption film F from the holding surface plate 4. Can be withdrawn. At this time, since only the water is interposed between the adsorption film F and the holding surface plate 4, the holder 3 can be replaced quickly.

On the other hand, when the polishing pad 5 is mounted on the polishing surface plate 6, the polishing pad 5 can be handled with the adsorbing film F adhered to the polishing sheet 13, and the skin layer S of the adsorbing film F can be handled. The polishing pad 5 can be attached to the polishing surface plate 6 by adding water to ₂ and pressing it against the polishing surface plate 6.
Further, when the polishing pad 5 is replaced, the polishing pad 5 can be detached from the polishing surface plate 6 by peeling the adsorption film F from the polishing surface plate 6. At this time, since only the water is interposed between the adsorption film F and the polishing surface plate 6, the polishing pad 5 can be replaced quickly.

The flexible urethane sheet as the flexible plastic sheet constituting the adsorption film F can be manufactured through the following steps.
First, in the preparation step, polyurethane resin, N, N-dimethylformamide (hereinafter abbreviated as DMF), which is a water-miscible organic solvent capable of dissolving polyurethane resin, and an additive are mixed to dissolve the polyurethane resin.
The polyurethane resin is selected from resins such as polyester, polyether, and polycarbonate resins having a 100% modulus (tension when pulled twice) of 20 to 50 MPa, preferably 20 to 40 MPa, more preferably 20 to 30 MPa. For example, the polyurethane resin is dissolved in DMF so as to be 20 to 25%.
Additives, hydrophobic active agent for stabilizing pigments such as carbon black to control the size and amount of bubbles b ₂ (number), hydrophilic active agents to promote the bubble b ₂ and the coagulation regeneration of a polyurethane resin, formed A thickener or the like for adjusting the viscosity of the resin viscous body at the time of filming can be used.

After removing aggregates and the like by filtering the solution obtained in the above preparation step, a polyurethane resin solution can be obtained by defoaming under vacuum, and the polyurethane resin solution is continuously applied to the film-forming substrate. The polyurethane resin is coagulated and regenerated by immersing it in an aqueous coagulating liquid.
Specifically, the film-forming substrate coated with the polyurethane resin solution is introduced into the coagulation liquid, whereby in the coagulation liquid, the DMF and coagulation liquid of the polyurethane resin solution are formed on the surface of the applied polyurethane resin solution. substitution was progress, dense microporous are formed, the skin layer S ₂ of several thicknesses μm is formed.
Then, between the skin layer S ₂ and the deposition substrate, further progress is replaced with the DMF and the coagulation liquid of the polyurethane resin solution, the polyurethane resin is solidified reproduced on one surface of the film forming substrate, the skin layer S _2, the bubbles b ₂ and communication holes that connect these bubbles b ₂ to form a three-dimensional network are formed to constitute the fine foam layer S ₁ .
Here, since the thickness of the skin layer S ₂ is about several [mu] m, will be finely foamed layer S ₁ in most of the coating thickness of the polyurethane resin solution is formed, fine foam layer S ₁ thickness is greater than the thickness of the skin layer S _2.
Thereafter, the soft polyurethane sheet is obtained by further drying the washed polyurethane resin taken out from the coagulating liquid, and buffed if necessary the surface opposite to the above-mentioned skin layer S ₂ in the flexible urethane sheet Thus, the adsorption film F can be obtained.

And as for the adsorption film F manufactured in this way, as for the thickness, it is desirable to set it as 50-200 micrometers as mentioned above.
In particular, when the adsorption film F is used on the surface opposite to the polishing surface of the polishing pad 5, if the thickness is less than 50 μm, minute unevenness formed on the surface of the polishing surface plate 6 cannot be absorbed. The peeling from the polishing surface plate 6 tends to occur. On the other hand, when the thickness exceeds 200 μm, the amount of deformation of the soft urethane sheet is increased, and when the polishing pad 5 is pressed against the workpiece 1 during polishing, the adsorption film F is deformed and an appropriate polishing pressure is applied. It becomes impossible to act on the workpiece 1.
Further, even when the adsorption film F is used to fix the holder 3 to the holding surface plate 4, if the thickness is less than 50 μm, peeling from the holding surface plate 4 is likely to occur. On the other hand, when it exceeds 200 μm, the soft urethane sheet at the position in contact with the frame member 12 is excessively compressed.
Next, the adsorption film F has a 100% modulus of 20 to 50 MPa. If the pressure is less than 20 MPa, the film is too soft and peeling from the film for film formation or buffing is difficult to perform, making it difficult to obtain the adsorption film F. On the other hand, if it exceeds 50 MPa, the film formability deteriorates and the film shrinks, making it impossible to obtain an adsorbent film excellent in adsorbability.
Further, for the adsorption film F, the amount of compressive deformation, which is the difference between the thickness of the adsorption film F when a load of 100 g / cm ² is applied and the thickness of the adsorption film F when a load of 1120 g / cm ² is applied. Is preferably 1.5 to 7.0 μm. If the thickness is less than 1.5 μm, minute irregularities on the surface of the polishing platen 6 cannot be absorbed, and peeling from the platen tends to occur. On the other hand, when the thickness exceeds 7.0 μm, the deformation becomes excessively large and an appropriate polishing pressure cannot be applied to the workpiece 1 via the polishing pad 5. Further, when used in the holder 3, there is a problem that the frame member 12 is excessively compressed and the end shape of the object to be polished deteriorates with time.

Hereinafter, the experimental result performed about the Example concerning the adsorption film F manufactured according to the said Example and the comparative example manufactured for the comparison is demonstrated. The present invention is not limited to the following examples.
In the experiment, the thickness, the amount of compressive deformation, the adsorption force, and the polishing uniformity were evaluated for the adsorption films F according to Examples and Comparative Examples using the following methods.
<Thickness>
The thickness of the adsorption film F was measured according to the thickness measurement method described in Japanese Industrial Standard (JIS K6550).
That is, the thickness of the adsorption film F when a load of 100 g per 1 cm ² was applied as an initial load in the thickness direction to the adsorption film F was measured. The adsorption film F is cut into three pieces of 10 cm in length and 10 cm in width, and the thicknesses of the four corners and the center of each piece are measured using a shopper type thickness measuring instrument (pressing surface: a circle having a diameter of 1 cm) (minimum scale). 001 mm) was read and measured, and the average value of 5 points was defined as the thickness of one piece. And the average thickness of the adsorption film F was made into the average value of the thickness measured about 3 pieces, respectively.
<Compression deformation amount>
For the amount of compressive deformation, a different load was applied to the surface of the adsorption film, and the difference in the thickness of the adsorption film due to the change in the load was defined as the amount of compressive deformation. Specifically, the difference (T1−T2) between the film thickness (T1) when a load of 100 g / cm ² is applied to the surface of the film and the film thickness (T2) when a load of 1120 g / cm ² is applied. ). The measurement was performed three times, and the average value was taken as the amount of compressive deformation of the present invention.

<Polishing test>
About the polishing pad of each Example and the comparative example, it grind | polished on the following grinding | polishing conditions, and evaluated adsorption | suction power and polishing uniformity. Here, 4-inch SiC was used as the object to be polished, and a diamond abrasive (abrasive particle size: 3 μm) dispersion was used as the slurry.
Polishing device used: Single-side polishing device Polishing speed (rotation speed of platen): 80 rpm
Processing stress: 330 gf / cm ²
Slurry supply amount: 3 mL / min Polishing time per sheet: 60 minutes

<Adsorption power>
Judgment was made based on whether or not the adsorbed film F after the 25 objects to be polished 1 were detached from the polishing surface plate 6. The case where peeling was not recognized was evaluated as ◯, and the case where peeling was observed was evaluated as x.
<Polishing uniformity>
The polishing uniformity of the object to be polished was evaluated by the thickness variation (standard deviation ÷ average value) (%) obtained from the thickness measurement results at 49 points for the object to be polished before and after the polishing process. The case where the thickness variation was less than 3% was evaluated as “◯”, and the case where 3% or more was confirmed was evaluated as “x”.

Example 1
For the adsorption film F according to Example 1, a polyester MDI (diphenylmethane diisocyanate) polyurethane resin having a 100% modulus of 24 MPa was used as the polyurethane resin.
100 parts DMF solution containing 30% polyurethane resin, 31 parts DMF for viscosity adjustment, 8 parts DMF dispersion containing 30% pigment carbon black, and 2 parts cellulose thickener are mixed to make polyurethane A resin solution was prepared. The obtained resin solution was cast on a polyester film (thickness: 250 μm). Thereafter, the polyester film cast with the resin-containing solution is immersed in a coagulation bath (the coagulation bath is water) to coagulate the resin-containing solution, and then washed and dried to form a 150 μm thick resin sheet on the polyester film. Obtained. Thereafter, the above skin layer S ₂ in the resulting resin sheet was buffed to a surface opposite with sandpaper, and a thickness of 50 [mu] m.
Such sticking a double-sided tape T on the side opposite to the above-mentioned skin layer S ₂ in the adsorption film F thus obtained, this nonwoven pad was mounted (Fujibo Ehime Co., Ltd., trade name "FPK7000C2").
The experimental results for the adsorption film F according to Example 1 showed that the amount of compressive deformation was within the specified range, and the adsorption force was not peeled off after the end of the experiment. Good results were also obtained with respect to polishing uniformity.

(Example 2)
The adsorption film F according to Example 2 has the same configuration as the adsorption film F according to Example 1 except that the buff treatment is not performed and the thickness is 150 μm.
Also in the experimental results for the adsorption film F according to Example 2, the amount of compressive deformation was within the specified range, and the adsorption force was not recognized after the experiment was completed. Good results were also obtained with respect to polishing uniformity.

(Comparative Example 1)
The adsorption film F according to Comparative Example 1 has the same configuration except that the adsorption film F according to Example 1 is buffed to have a thickness of 39 μm.
However, the adsorption film F according to Comparative Example 1 had a low adsorption force, and the polishing pad could not be attached to the polishing surface plate, so that the polishing test could not be performed. For this reason, polishing uniformity could not be evaluated.

(Comparative Example 2)
The adsorption film F according to Comparative Example 2 has the same configuration as the adsorption film F according to Example 1 except that the coating thickness is increased and the thickness is set to 300 μm.
The experimental results for the adsorption film F according to Comparative Example 2 indicated that the amount of compressive deformation was higher than the upper limit of the specified range. In addition, there was a problem with polishing uniformity. On the other hand, good results were obtained for the adsorption power.

  In the above embodiment, the case where the suction film F is applied to the polishing pad 5 and the holder 3 is illustrated. However, the same size of the suction film F may be directly attached to the frame member 15 for use.

DESCRIPTION OF SYMBOLS 1 To-be-polished object 2 Polishing apparatus 3 Holder 4 Holding surface plate 5 Polishing pad 6 Polishing surface plate 11 Holding sheet 13 Polishing sheet 15 Frame material b ₁ Vertically long bubble b ₂ bubble F Adsorption film N Nap layer S ₁ Fine foam layer S ₂ Skin layer T Double-sided tape

Claims (4)

An adsorbing film comprising a soft plastic sheet having a skin layer having micropores on the surface and a microfoaming layer having air bubbles larger than the micropores of the skin layer inside,
An adsorptive film having a thickness of 50 to 200 μm and a resin 100% modulus of 20 to 50 MPa. The amount of compressive deformation, which is the difference between the thickness of the adsorption film when a load of 100 g / cm ² is applied and the thickness of the adsorption film when a load of 1120 g / cm ² is applied, is 1.5 to 7.0 μm. The adsorption film according to claim 1.   The adsorptive film according to claim 1, wherein the soft plastic sheet is a soft urethane sheet. In a polishing pad for polishing an object to be polished,
A polishing pad comprising the adsorption film according to claim 1 on a surface of the polishing pad on the side of the polishing platen fixed.

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