JP2002036129A - Polishing pad and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of obtaining stable grinding performance. SOLUTION: A sheet including one and more kinds of abrasive grains is spirally wound in a cylindrical shape, and a cutting surface thereof is used as a grinding surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing pad for precision polishing of semiconductor wafers, liquid crystal glass, hard disks and the like, and more particularly, to a polishing pad for chemical mechanical polishing mainly used in a semiconductor device manufacturing process. About.

[0002]

2. Description of the Related Art As semiconductor integrated circuits become more highly integrated and miniaturized, wiring layers are being stacked. That is, a process is employed in which a wiring material is pattern-formed on the surface of a semiconductor wafer, the upper surface thereof is covered with an insulating film such as silicon oxide, the next wiring material is formed in a pattern, and this process is sequentially repeated.

When the number of wiring layers increases, a step is formed in an insulating film such as silicon oxide. Therefore, it is necessary to eliminate the step and flatten the pattern before forming the next wiring material. Polishing has been performed.

In the chemical mechanical polishing, a semiconductor wafer is flatly polished using a polishing pad while supplying a polishing liquid (hereinafter referred to as slurry). Performance is required.

With respect to polishing accuracy, in particular, it is necessary to satisfy both flatness of the entire semiconductor wafer (hereinafter referred to as global flatness) and flatness of a fine pattern of the semiconductor wafer (hereinafter referred to as local flatness). These are said to be in a trade-off relationship in that increasing the accuracy of one reduces the accuracy of the other.

Further, it is necessary to minimize the occurrence of large polishing flaws (hereinafter referred to as killer scratches) which affect device performance.

As described below, the polishing rate, polishing accuracy, and occurrence of killer scratches greatly depend on the physical properties of the polishing pad more than the performance of the polishing apparatus. (A) Polishing rate: Good holding performance of slurry and large area of polished part having microscopic surface roughness. (B) Polishing accuracy: a large amount of compressive elastic deformation is required for global flatness, and a pad hardness is large for local flatness. (C) A pad that does not generate scratches: the surface has a porous structure, and polishing debris and the like are accumulated in the porous portion and do not exist in the polished portion.

(Conventional Pads) Conventional polishing pads have a porous surface (polishing surface) in terms of slurry holding performance and prevention of killer scratching. A sheet-like pad made of a polyurethane foam has been used in many cases because a foam having a density and a cell diameter can be produced and the abrasion resistance is high.

However, when a conventional pad made of polyurethane foam is polished for a long period of time, abrasives and polishing debris may clog the holes of the closed cells on the pad surface, or the holes may be deformed by compression. There has been a problem that polishing performance is reduced, such as generation of polishing and a reduction in polishing rate.

[0010] For this reason, it is necessary to carry out dressing for scraping the pad surface with a diamond cutting machine or the like every time it is used several times, and the polishing performance must be verified each time, which is extremely inconvenient. .

[0011] Further, there is a problem that the bubble diameter and the density of the foam vary among the production lots, and the slice portion also varies within the same lot, so that stable polishing performance cannot be obtained.

[0012] A pad that does not require dressing by adjusting abrasive resistance by dispersing and supporting abrasive particles made of inorganic fine particles on a pad material (a self-conditioning pad) and a pad that reduces the amount of slurry used have been proposed. I have.

However, since the pad material is composed of a closed cell, it is difficult to uniformly and stably produce cell diameters and densities of the foam over the entire pad and between production lots. Since it is difficult to obtain a uniformly dispersed molded body, there has been a problem that stable polishing performance cannot be similarly obtained.

[0014]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a polishing method which eliminates the drawback of a conventional polishing pad made of foamed polyurethane which cannot provide stable polishing performance. It is intended to provide a pad.

It is another object of the present invention to provide a polishing pad in which the dispersion pattern of abrasive grains is made the same, the amount of slurry used is reduced, and stable polishing performance is obtained. I do.

The invention according to claim 9 is the first invention.
An object of the present invention is to provide a method for industrially easily producing the polishing pad described in (1).

[0017]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and found that if the cut surface of the sheet is the polishing surface of the polishing pad, the fine structure of the polishing surface is substantially the same. As a result, the present inventors have found that stable polishing performance can be obtained, and have reached the present invention. Conventionally, the cut surface of the sheet is not used as the polishing surface of the polishing pad at all, and such an idea is not known at all.

That is, the invention according to claim 1 is characterized in that the cut surfaces of one or more types of sheets are spirally arranged on the polishing surface of the polishing pad.

If the cut surface of the sheet is a polished surface, the same polished surface can be obtained from the same sheet, and even if the polished surface is cut, the inside is the same polished surface, so that stable polishing performance can be obtained. It is.

When the surface of the sheet is a polished surface, the fibers are rubbed in the length direction of the fibers, so that the fibers are easily removed.
When the cut surface is a polished surface, the end surface of the fiber is rubbed, and the fiber does not come off even if it is rubbed, so that it is considered that stable and excellent polishing performance can be obtained.

In the polishing pad of the present invention, the cut surface of the sheet is arranged in a spiral shape. By doing so, even if the cut surface is polished, delamination can be reduced. On the contrary, if the laminated cut surface is simply used as the polishing surface, delamination easily occurs due to polishing resistance or the like, and cannot be used industrially as a polishing pad.

Further, the invention according to claim 3 is characterized in that at least one of the sheets is an abrasive sheet.

If the abrasive grain-containing liquid is applied to the sheet substantially uniformly, even if the abrasive grain content is different between the surface and the inside, the abrasive grain-containing pattern on the sheet cut surface and the sheet surface and the inside is substantially the same. Therefore, even if the surface of the pad is shaved, a substantially constant abrasive grain pattern can always be used as the polished surface, so that stable polishing performance can be obtained.

The invention according to claim 9 is characterized in that the sheet is wound and formed into a spiral shape.

According to the present invention, by selecting the thickness dimension of each sheet to be used, the fine structure of the polishing function part due to the physical properties of each sheet cut surface can be controlled to be constant, so that the polishing ability varies. It is possible to provide a stable polishing pad without any problem.

Next, an embodiment of the present invention will be described.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The sheet used in the present invention is not particularly limited as long as it has mechanical properties capable of being wound in a spiral shape. The thickness of the sheet to be used is about 0.05 to 10 mm, preferably 0.1 to 3 m
m. If the sheet thickness is less than 0.05mm,
Since the adhesive between the sheets relatively increases, the polishing function of the cut surface of the sheet cannot be sufficiently performed.
If it exceeds m, the effect of the polishing function on the cut surface of the sheet becomes too large, and the polishing performance is governed by the physical properties of the cut surface of the sheet. In addition, the material cannot be wound in a spiral shape, becomes soft, and cannot function as a polishing pad.

The sheet used in the present invention includes woven fabric,
Non-woven fabrics, felts and papers that are processed into sheets in the form of synthetic fibers and inorganic fibers, elastic polymer sheets, and sheets containing inorganic fine particles can be used.
Those having a relatively large porosity and being hydrophilic are preferred.

The type of sheet used in the present invention may be one, but it is preferable to use a combination of two or more types in order to meet the above-mentioned required characteristics (A) to (C). In particular, it is preferable to use a sheet containing inorganic fine particles in combination with a fibrous sheet.

As the abrasive grain sheet of the present invention, a sheet in which abrasive grains are dispersed and filled in a synthetic polymer or a sheet in which abrasive grains are dispersed in a binder material and impregnated and filled in a fibrous sheet may be used. After applying the abrasive liquid, for example, by passing the abrasive liquid through a roll, the content of the abrasive particles in the sheet can be made more uniform.

As the abrasive used in the present invention, silicon oxide, cerium oxide, aluminum oxide, manganese dioxide, iron oxide, zinc oxide, silicon carbide, boron carbide, synthetic diamond, tourmaline powder and the like, or two or more kinds thereof can be used. Is mentioned. The abrasive grains used may be conventional ones used for this purpose, and are not particularly limited, but are preferably the same type as the abrasive grains used in the slurry at the time of polishing.

The particle size of the abrasive used is 0.01 to 10
It is preferably μm. Within this range, high-density and uniform dispersion can be achieved, but the particle diameter is 10 μm.
If m is exceeded, killer scratches may be caused.

As a binder for dispersing the abrasive grains, a polymer obtained by diluting a high molecular polymer such as polyacrylic, epoxy or polyurethane with water or an organic solvent such as DMF or DEF can be suitably used. The content of the abrasive grains in the abrasive liquid is preferably 50 to 90% by weight.

The above-mentioned polishing pad of the present invention can be manufactured by winding it into a spiral shape and forming it into a cylindrical shape, preferably while coating or impregnating a sheet with a binder. The binder may be used only on the wound end. In addition, if it is made to fit tightly on the cylindrical elastic body after winding, it does not matter if a binder is not used at all.

The cylindrical molded product is cut in a direction perpendicular to or crossing the winding axis, and the cut surface is used as the polishing surface of the polishing pad of the present invention, or the sheet is slit into the thickness of the polishing pad. While winding around the shaft,
The polishing pad of the present invention may be used as it is.

If the sheet is an abrasive sheet alone or an abrasive sheet and a fibrous sheet, a polishing pad that does not use slurry or reduces the amount of slurry can be used. In addition, the polishing pad does not require dressing since the pad surface is slightly scraped off.

With such a polishing pad, the polishing performance is given by the abrasive grains filled in the pad base material, and the pad base material has an appropriate abrasion. Therefore, the surface of the pad is successively changed according to the number of polished wafers. It can be sharpened little by little and can be polished on a new surface.

The reason for using the polishing pad to obtain a polished surface of stable quality is that if the abrasive-gear-containing liquid is applied to the sheet almost uniformly, even if the abrasive-grain content is different between the surface and the inside, Since the abrasive grain-containing patterns on the cut surface, the sheet surface, and the inside are substantially the same, it is considered that the polishing can always be performed under constant polishing conditions.

Conventionally, neither the inclusion of abrasive grains in a thin sheet, the winding of the same in a roll, nor the use of a cut surface as a polished surface has been known at all.

In the polishing pad formed by the above method, a hole through which a shaft is formed is formed at the center. Depending on the purpose of use, the polishing pad can be used as it is, but it is preferable to fill the hole with a synthetic resin or the like to form the polishing pad.

In order to strengthen the binding between the sheets, it is preferable to wind the sheets while applying the synthetic polymer liquid as a binder when winding the sheets. As the synthetic polymer liquid as the binder, a solvent solution or an aqueous emulsion of a thermosetting resin such as an acrylic, epoxy, polyester, or urethane resin can be used. Alternatively, a thermoplastic resin may be used and bound by heat sealing.
In short, in the present invention, the binder is used in a concept including an adhesive, and is not particularly limited as long as a sheet can be attached.

In addition to the function of binding between the sheets, the above-mentioned binder can be provided with a function as a polishing region by controlling the coating thickness to a constant value, and also can adjust the elastic compressibility of the pad. It can also have a function as a material.

[0043]

Next, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

Example 1 In an aqueous solution of methyl methacrylate, the average particle size was 1 μm as abrasive grains.
m of cerium oxide was uniformly dispersed to prepare an abrasive liquid.

The above abrasive liquid is 200 mm wide and weighs 20 g /
and roll forming while applying between two spans of m ² bond PET nonwoven fabric and dried by heating to cure the methyl methacrylate to prepare a sheet (A) including a 0.3mm-thick inorganic fine particles. The weight of the obtained sheet (A) is 6
At 00 g / m ² , the content of cerium oxide with respect to the sheet was 79% by weight.

The sheet (A) containing the inorganic fine particles is coated with the aqueous solution of methyl methacrylate with a transfer roll, wound up to a diameter of 200 mm while pressing with a touch roll, cured by heating and drying, and then sliced. Thus, a polishing pad of the present invention was prepared.

The surface (polishing surface) hardness of the polishing pad thus prepared was 96 degrees with an ASKER C type hardness meter, and the density was 2.12 g / cm ³ .

When a silicon wafer with an oxide film was polished using the obtained polishing pad while supplying a slurry mixed with cerium oxide fine powder, the polishing rate was 5%.
000 ° / min, and no micro-scratch was observed on the wafer.

When the obtained polishing pad was used to polish a silicon wafer with an oxide film while supplying pure water, the polishing rate was 1500 ° / min, and no micro-scratch was observed on the wafer. Was.

Example 2 The above-mentioned sheet (A) containing the inorganic fine particles and a spunbond PET nonwoven fabric having a width of 200 mm and a weighing of 80 g / m ² were applied with the above-mentioned aqueous solution of methyl methacrylate using a transfer roll, and pressed with a touch roll. After winding to a diameter of 200 mm, drying by heating and curing, the slice was sliced to prepare a polishing pad of the present invention.

The surface (polishing surface) hardness of the prepared polishing pad was 90 degrees by an ASKER C type hardness meter, and the density was 2.85 g / cm ³ .

When a silicon wafer with an oxide film was polished using the obtained polishing pad while supplying a slurry in which cerium oxide fine powder was mixed, the polishing rate was 3%.
000 ° / min, and no micro-scratch was observed on the wafer.

Example 3 Spunbond PET with a width of 200 mm and a weighing of 20 g / m ²
The nonwoven fabric was roll-formed while applying an aqueous solution of methyl methacrylate, and dried by heating to harden the methyl methacrylate to prepare a sheet (B) having a thickness of 0.1 mm.

The above sheet (B), width 200 mm, weighing 8
The sponge bond nonwoven fabric of 0 g / m ² is coated with the above-mentioned aqueous solution of methyl methacrylate by a transfer roll, wound up to a diameter of 200 mm while pressing with a touch roll, cured by heating and drying, and then sliced. Polishing pad was prepared.

The surface (polishing surface) hardness of the prepared polishing pad was 85 degrees with an ASKER C type hardness meter, and the density was 1.5 g / cm ³ .

When a silicon wafer having an oxide film was polished using the obtained polishing pad while supplying a slurry in which cerium oxide fine powder was mixed, the polishing rate was 2.
At 500 ° / min, no microscratch was observed on the wafer.

Example 4 Cerium oxide having an average particle diameter of 1 μm as abrasive grains was uniformly dispersed in a water-soluble polyurethane emulsion to prepare an abrasive liquid.

The above abrasive liquid was 100 mm wide and weighed 20 g /
m²Between two spunbond PET non-woven fabrics
Roll-formed, heat-dried, inorganic 0.4mm thick
An obtained sheet in which a sheet (C) containing fine particles is prepared
The weight of (C) is 800 g / m. ²And oxidation to the sheet
The cerium content was 82% by weight.

The sheet (C) containing the inorganic fine particles and the width 1
After applying the water-soluble polyurethane emulsion to a spunbond PET nonwoven fabric of 00 mm and weighing 80 g / m ² , applying pressure with a touch roll, winding to a shaft of 60 mm in diameter to a diameter of 610 mm, heating and drying and curing. Then, a 2.5 mm thick sheet was sliced with a slicer, and a urethane sheet having a diameter of 60 mm and a thickness of 2.5 mm was adhered to a central hole from which the shaft had come off to prepare a polishing pad of the present invention.

The surface (polishing surface) hardness of the prepared polishing pad was 96 degrees with an ASKER C hardness meter, and was 1 kgf.
The compressibility of the load was 5%.

The polishing pad of the present invention can control the fine structure of the polishing function part depending on the physical properties of the cut surface of the sheet, so that a stable polishing pad having no variation in polishing ability can be obtained.

Further, in the polishing pad of the present invention, since the cut surface of the sheet is used as the polishing surface, the same polishing surface can be obtained from the sheets having the same polishing function. Therefore, stable polishing performance can be obtained. In addition, if the surface of the sheet is a polished surface, the fibers will be rubbed in the length direction of the fibers, so the fibers will be easily removed,
Since the cut surface is a polished surface, the end face of the fiber is rubbed, and the fiber does not come off even if worn down, so that stable and excellent polishing performance can be obtained.

In the polishing pad of the present invention, the cut surface of the sheet is arranged in a spiral shape. By doing so, even if the cut surface is violently polished, the sheet is hardly delaminated. Become.

[0064]

According to the first aspect of the present invention, the drawbacks of the conventional sheet-shaped polishing pad made of foamed polyurethane are eliminated, stable polishing performance is obtained, and the surface of the pad is slightly reduced. The advantage is that dressing is not required.

According to the third aspect of the present invention, in addition to the effect of the first aspect, polishing can be performed with no or little addition of abrasive grains, and the dispersion pattern of the abrasive grains is the same. In this way, the amount of slurry used is reduced,
Moreover, stable polishing performance can be obtained.

According to the ninth aspect, the polishing pad according to the first aspect can be industrially easily manufactured.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C058 AA07 AA09 CA06 DA17 3C063 AA02 AB05 BA15 BA33 BB02 BB03 BB04 BB07 BC03 BF09 CC22 CC30 EE10 FF30

Claims (12)

[Claims] 1. A polishing pad, wherein cut surfaces of one or more sheets are spirally arranged on a polishing surface of the polishing pad. 2. The polishing pad according to claim 1, wherein the contact portion of the sheet is bound via a binder. 3. The sheet of claim 2, wherein the sheet comprises an abrasive sheet.
A polishing pad according to item 1. 4. The polishing pad according to claim 3, wherein the sheets are an abrasive sheet and a fibrous sheet. 5. The method according to claim 1, wherein the abrasive sheet has a particle size of from 0.01 to 10.
The polishing pad according to claim 3, which is a fibrous sheet having a thickness of 0.05 to 10 mm containing μm abrasive grains. 6. The method according to claim 1, wherein the abrasive grains are silicon oxide, cerium oxide,
4. A single or two or more of aluminum oxide, manganese dioxide, iron oxide, zinc oxide, silicon carbide, boron carbide, synthetic diamond, and tourmaline powder.
The polishing pad according to any one of claims 1 to 5. 7. The polishing pad according to claim 4, wherein the fibrous sheet is a woven fabric, a nonwoven fabric or a felt-like fibrous sheet. 8. The polishing pad according to claim 1, wherein the polishing pad is for chemical mechanical polishing. 9. The method for manufacturing a polishing pad according to claim 1, wherein the sheet is wound and formed into a spiral shape. 10. The method for producing a polishing pad according to claim 9, wherein the sheet is spirally wound and formed into a cylindrical shape while applying or impregnating an adhesive on the sheet. 11. The method for producing a polishing pad according to claim 9, wherein the cylindrical molded product is cut in a direction perpendicular to or crossing the winding axis, and the cut surface is used as a polishing surface. 12. The method according to claim 9, wherein the sheet is an abrasive sheet alone or an abrasive sheet and a fibrous sheet.