JP2002001649A - Polishing pad, and polishing device and polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease dust adherence to surface of a polishing object, to reduce scratches, to simultaneously realize a flatting property, and to eliminate microscopic irregularity of a semiconductor wafer itself before uneven part machining, namely defects expressed as waviness or nanotopology, by a simple polishing method. SOLUTION: This polishing pad is blended with fiber substances that are hydrophilic and substantially insoluble in water and have aspect ratio of 5 and more, and/or particles formed by combined elements of the fiber substances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention presses a workpiece against a rotating elastic pad while supplying a polishing liquid containing working abrasive grains and / or supplying a polishing liquid containing no abrasive grains to perform relative motion. A polishing pad used for chemical mechanical polishing (CMP) or the like for polishing a workpiece surface to a mirror surface or for preferentially polishing convex portions of irregularities on the workpiece surface with an abrasive while polishing. The present invention relates to an apparatus and a polishing method.

[0002]

2. Description of the Related Art In order to realize a multi-layer wiring in manufacturing a semiconductor with a high degree of integration, it is necessary to completely flatten the surface of an insulating film. So far, SOG (Spin-On-Glass) has been used as a typical technique for this planarization method.
Method and etchback method (P. Elikins, K. Reinhardt, and R.
Layer, "A planarization process for double metalCMO
Susing Spin-on Glass as a sacrificial layer, "Proce
eding of 3rd International IEEE VMIC Conf., 100 (198
6)) and the lift-off method (K. Ehara, T. Morimoto, SM
uramoto, and S.Matsuo, "Planar Interconnection Techn
ology for LSI FabricationUtilizing Lift-off Proces
s ", J. Electrochem Soc., Vol. 131, No. 2, 419 (1984)) and the like.
Although this is a flattening method utilizing the fluidity of the G film, it is impossible to perform complete flattening by itself. The etch-back method is the most frequently used technique, but has a problem of dust generation due to simultaneous etching of the resist and the insulating film, and is not an easy technique in terms of dust management. Then, the lift-off method has a problem that the stencil material to be used cannot be lifted off because the stencil material is not completely dissolved at the time of lift-off, and the controllability and the yield are incomplete. Therefore, the CMP method has recently attracted attention. This is a method of pressing a workpiece against a rotating elastic pad and performing preferential polishing with a polishing pad on the surface of the workpiece with relative movement while performing relative movement. Widely used. Also, in recent years, fine irregularities of the semiconductor wafer itself before the irregularity processing itself, that is, waviness, and surface defects that had no conventional problems expressed as nanotopology have become a problem. Double-side polishing, polishing while flowing alkali. The method has been done.

[0003]

[0007] However, the C
In the MP method, there are problems such as scratches, adhesion of dust, and poor global flatness, which occur on the surface of the object to be polished. For example, when such dust adheres or scratches occur on a surface to be polished such as an interlayer insulating film, when a wiring made of Al or Cu-based metal is formed thereon in a later process, a step breakage or the like occurs, There is a possibility that a decrease in reliability such as deterioration of electromigration resistance may occur. In addition, when polishing non-magnetic substrates for HDDs (Hard Disk Drives) and the like, reproduced signals may be lost, such as dropouts. It is considered that the occurrence of scratches is caused by agglomerates due to poor dispersion of the abrasive particles. Particularly, a polishing slurry which employs alumina as polishing particles, which is used for CMP of a metal film, has poor dispersibility and does not completely prevent scratch damage. At present, the cause of dust adhesion is not well understood. It is common sense that a hard polishing pad is desirable to improve global flatness, but conversely, it is considered that both can not be compatible because dust tends to adhere and scratches are likely to occur. For example, Japanese Patent Application Laid-Open No. 8-500622,
Attempts have been made in 2000-34416 and the like, but they have not been able to achieve both dust adhesion and scratch damage and flattening characteristics. SUMMARY OF THE INVENTION It is an object of the present invention to reduce dust adhesion to the surface of an object to be polished, to reduce scratches, and to achieve flattening characteristics.

Another object of the present invention is to remove fine irregularities of the semiconductor wafer itself before the irregularity processing, that is, defects such as waviness and nanotopology by a simple polishing method.

[0005]

In order to solve the above-mentioned problems, the present invention has the following arrangement.

A polishing pad comprising a mixture of hydrophilic and substantially water-insoluble fibrous materials having an aspect ratio of 5 or more and / or particles formed of a composite thereof. The polishing pad according to claim 1, wherein the particles formed of the fibrous material and / or the composite thereof are substantially free of voids.
3. The polishing pad according to claim 1, wherein the official moisture regain of the particles formed of the fibrous material and / or the composite thereof is 3% or more. The polishing pad according to any one of claims 1 to 4, wherein the polishing pad further has voids apart from the particles formed of the fibrous material and / or the composite thereof. 7. The polishing pad according to claim 1, further comprising inorganic fine particles. The polishing pad according to any one of claims 1 to 5, wherein the D hardness exceeds 65. 7. The polishing pad according to claim 1, further comprising a water-soluble substance. The polishing pad according to claim 7, wherein the polishing pad contains 0.01 to 10% by weight of a water-soluble substance. A polishing apparatus, a polishing method, a semiconductor wafer, and a semiconductor chip using the polishing pad.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0008] By mixing particles formed of a fibrous material having a hydrophilic and substantially water-insoluble aspect ratio of 5 or more and / or a composite thereof, dust adhesion and dust adhesion, which have conventionally been in a trade-off relationship, are mixed. The polishing pad itself can be hardened without causing scratches, and the flexural modulus can be dramatically increased as compared with the polishing pad of the prior art, so that extremely good flattening characteristics can be realized.

By mixing a hydrophilic organic substance substantially insoluble in water, the wettability of the polishing pad surface is improved, and the adhesion of dust to the surface of the object to be polished is reduced although the detailed mechanism is unknown. In connection with that, it is thought that scratch damage can be reduced. At this time, since the particles and / or fibrous materials made of the hydrophilic organic substance are substantially insoluble in water, they may change the properties of the dispersion regardless of whether or not they include free abrasive grains used for polishing. Since there is no polishing, polishing can be performed well.

[0010] The term "substantially insoluble in water" means that the solubility in water at 25 ° C is 1% or less. Hydrophilicity is basically an expression of the property of absorbing water in a resin, and does not mean that water is held in voids between macroscopic resins. That is, when evaluating the hydrophilicity, a test piece taken out of water after being immersed in water for 24 hours was taken in a sealed container, centrifugal force of 1400 G to 1450 G was applied for 30 seconds, and moisture absorption was measured in a state where water was shaken off. The weight increase rate was determined according to the following equation 1. Weight increase rate (%) = (Hygroscopic weight−Dry weight) / Dry weight × 100 (Equation 1) Here, hydrophilicity means that the weight increase rate when immersed in 50 ° C. water for 24 hours is 2.0% or more. Refers to the characteristics of. In the present invention, about 5.0% is more preferable. If the temperature is too high, the polishing pad swells during polishing, and the flatness of the polishing pad surface is impaired. Further, when the volume swelling ratio is large, the strength of the polishing pad itself deteriorates greatly during polishing, which is not good. At most, 15% or less is preferable,
Usually, 10% or less is preferable.

Further, as a quantitative expression, it is expressed by an official moisture content. This represents the moisture content at a humidity of 65% and a temperature of 20 ° C., and is obtained by the following equation. Official moisture content (%) = (moisture absorption-dry weight) / dry weight × 100 (formula 2) The water absorption is defined as 1 when immersed in water at 25 ° C.
Moisture rate after 0 minutes, expressed as water absorption rate (%) = (moisture absorption weight−dry weight) / dry weight × 100 (formula 3). It is desirable that the rate of water absorption be high, and it is desirable that saturation be reached within 10 minutes. However, if the change occurs 90% in 24 hours, this resin can be applied.
However, if the water absorption exceeds 10,000%, the pad itself may be deformed, or the polished surface may become too large to be used. It is preferably within 6000%, more preferably within 3000%.

The official moisture regain can be used from about 1%, preferably 3% or more. In order to further suppress dust adhesion, the content is preferably 5% or more, and when the content is 7% or more, the mixing amount of particles and / or fibrous substances can be reduced, so that they can be more preferably used.

The mixing amount of the hydrophilic and substantially water-insoluble fibrous material having an aspect ratio of 5 or more and / or the particles formed of the composite thereof depends on the official moisture content and water absorption. Basically, when the official moisture regain and water absorption are large, it can be reduced, and when it is small, it is necessary to increase it. If it is less than 4%, the effect cannot be sufficiently exhibited, but if it is more than 4%, dust adhesion and scratch damage can be reduced.
When the mixing ratio is small, the effect is small, and when the mixing ratio is large, the effect is large, but the physical properties of the pad are often deteriorated.
That is, the hardness of the pad is reduced, the bending strength is weak, and the pad is easily brittle. For this reason, it is preferably used in an amount of 7 to 60% by weight, more preferably 20 to 50% by weight. The aspect ratio is represented by (long axis length of particles) / (short axis length of particles), and in the present invention, refers to a fibrous shape of 5 or more. The fiber composite is a composite formed by gathering these fibrous materials in a fibrillated state. For example, it refers to a shape like a microfiber precursor having a core-sheath structure. In the present invention, it refers to a state in which these are gathered to form particles. The aspect ratio defines the fine fibers in these particulate matter. By mixing the filler having such a shape, the polishing pad itself relaxes the stress at the time of polishing, and suppresses dust adhesion and generation of scratches.

The resin and the organic polymer matrix constituting the polishing pad include polyamide, polyacryl, polyolefin, polyvinyl, ionomer, polycarbonate, polyacetal, and polyurethane.
A thermoplastic resin such as a polyimide resin and a derivative thereof, a copolymer, a graft, or the like can be used. These mixtures may be used, but it is important to mix them so that hardness is obtained. For example, it is also effective to mix inorganic fine particles and to improve the hardness. The technology disclosed in nanocomposites can be applied and developed. Specifically, as the inorganic fine particles, silica, ceria, alumina, zirconia, titanium, tungsten, barium carbonate, barium sulfate, carbon black, clay such as montmorillonite, crystals of zeolite and the like can be used. Also, a mixture of these is also possible. It is also possible to modify the surface in advance to improve the compatibility with the matrix. As for the particle diameter, from about 3 nm to 5
Although those having a thickness of about 0 μm can be used, if they are too large, the risk of causing scratches increases. For this reason, more preferably, 2
It is preferably 0 μm or less, more preferably 5 μm or less.
Silica, ceria, alumina, zirconia, titanium, tungsten, barium carbonate, barium sulfate, carbon black, clay such as montmorillonite, fine particles such as crystals of zeolite, etc. are effective even at about 1%, and are effective at about 80%. Can mix up to. When mixed at a high concentration, not only the effect of increasing the hardness of the polishing pad, but also the effect as a so-called fixed abrasive polishing pad containing abrasive grains is effective. In this case, if the particle diameter is small, the effect is small, and the particle diameter is preferably 30 nm or more.
0 nm or more is more preferable. By changing the particle size and mixing amount of these fine particles, it is possible to manufacture a polishing pad that matches the characteristics of the object to be polished.

Other usable organic polymer matrices include thermosetting resins such as polyurethane-based, epoxy-based, phenol-based, melamine-based, urea-based, and polyimide-based resins. Mixtures of these resins (including alloying) and modification techniques such as copolymerization, grafting, and modified products can also be used. In the present invention, the resin constituting the polishing pad may be appropriately selected based on desired hardness, elastic modulus, and wear resistance. Also in this case, inorganic fine particles can be mixed in the same manner as when the above-mentioned thermoplastic resin is used.

Since the thermoplastic resin is softer than a general thermosetting resin, the official moisture regain of particles and / or fibrous materials substantially insoluble in water that are mixed may be low. %, But is preferably 3% or more in order to further reduce the adhesion of dust and scratches. For the same reason, it is desirable that the official moisture content of the thermosetting resin is higher. In particular, in this case, it is preferably at least 5%, more preferably at least 7%.

The D hardness after molding the polishing pad of the present invention is 65.
Is desirable. If it is less than 65, it becomes too soft and dishing and erosion are likely to occur, which is not preferable. In order to further increase the polishing rate, it is preferably at least 70, and more preferably at least 80. In the present invention, even if the hardness is further increased and the D hardness exceeds 90, problems such as scratches and dust adhesion do not occur, and the present invention can be used. For this reason, it is possible to exhibit good polishing and flattening characteristics that could not be achieved conventionally.

Used in the polishing pad of the present invention
For particles formed of a hydrophilic and substantially water-insoluble fibrous material having an aspect ratio of 5 or more and / or a complex thereof, for example, cellulose-based, starch-based, polysaccharides such as chitin, protein, and polyacrylic Acrylics such as acids and polymethacrylic acid, aramids, polyamides,
Resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polyvinyl polypyrrolidone, or crosslinked or copolymers containing the resin as a main component can be used. Natural fibers such as silk, wool, cotton, hemp, and polyvinylpyrrolidone / polyvinylimidazole copolymer,
Highly water-absorbing resins, pulp, rayon, paper, and various charged celluloses for cellulose ester-based ion exchange are also commercially available and can be effectively used. Further, a resin obtained by introducing a sulfone group, an amino group, a carboxy group, or a hydroxyl group into a resin which is originally hydrophobic can also be used. Hydrophobicity means that the weight gain obtained by the above formula 2 is less than 2%. It is preferable to use one in which mixing of sodium ions is suppressed to 400 ppm or less. More preferably 50 ppm
Or less, more preferably 10 ppm or less.

Further, the polishing pad of the present invention may further contain a water-soluble substance. Various commercially available polyalkylene glycol, polyvinyl vinylidone, polyvinyl alcohol, polyvinyl acetate, chitosan, polyvinyl pyrrolidone, polyvinyl imidazole,
There are water-soluble polysaccharides and the like, and these polymers can be used. In addition, low molecular substances such as various inorganic salts can be mixed. When molding a polishing pad,
In the present invention, since particles and / or fibrous materials, ie, hydrophilic polymers, composed of a hydrophilic organic substance substantially insoluble in water are used, they are used after being dried, but it is difficult to completely remove water. Steam is generated by heating during molding. Therefore, voids can be formed in portions other than the particles and / or fibrous materials. Further, in the case of thermosetting resin, since water is generated at the time of curing like a phenol resin, a void can be formed in a portion other than particles and / or fibrous materials by using this.
In order to control the size of the voids, for example, these water vapors can be successfully extracted and cured at the time of molding. However, when finer control is required, this can be achieved by mixing a small amount of a water-soluble substance. Furthermore, these water-soluble substances dissolve during polishing to form voids only on the polishing pad surface, and these voids increase the retention of free abrasive grains in the polishing slurry and are effective in removing polishing debris. As a result, it advantageously works to improve the polishing rate. In addition, since this water-soluble substance dissolves in the dispersion of the polishing liquid and can change its viscosity, for example, when xanthan gum, which is one of water-soluble polysaccharides, is mixed, the polishing liquid is dissolved by dissolving it. Bingham fluid-like properties are obtained, and the effect of improving flatness, particularly global flatness, when polishing is supposedly obtained because diffusion of abrasive particles is possibly suppressed in the concave portions of the semiconductor wafer having irregularities. In order to exhibit these effects, there is an effect even when a water-soluble substance is added in an amount of about 0.01 wt% per weight of the polishing pad, but preferably an addition amount of 0.5 wt% or more and 5 wt% or less is effectively used. Can be If it exceeds 10% by weight, the properties of the polishing dispersion are changed too much, which is not preferable. If a low-molecular substance having little effect on the viscosity of the dispersion is used, a larger amount can be mixed, but it is not practical from the viewpoint of cost. These judgments are easy for those skilled in the art.

The polishing pad may be formed by a method of forming a fibrous material having an aspect ratio of 5 or more, which is hydrophilic and substantially insoluble in water, and / or particles formed of a composite thereof, and in some cases, an organic polymer matrix and a hydrophilic material. The inorganic fine particles and / or the water-soluble substance can be compounded in advance and subjected to hot compression molding, or can be melt-extruded. A method such as an injection press is also possible. Since particles and / or fibrous materials are used, the mixing can be performed efficiently, and the variation in physical properties of the completed polishing pad can be reduced. In addition, the aspect ratio that makes the monomer molecules of the matrix hydrophilic and substantially insoluble in water is
It is also possible to polymerize after impregnating particles formed of five or more fibrous substances and / or composites thereof, and in some cases, inorganic fine particles and / or water-soluble substances. If the matrix is a two-part matrix such as polyurethane, it can be mixed with the main agent or the curing agent in advance, mixed with the curing agent or the main agent, poured into an appropriate mold after the defoaming operation, and molded. It is also possible to finish the polishing pad in the shape of a polishing pad. Specifically, it depends on the compatibility of each matrix with a hydrophilic and water-insoluble polymer and the individual heat resistance, polymerization properties, physical properties such as melt viscosity, etc. Easy. As for the polishing pad of the present invention, a combination of known techniques can be used for the manufacturing method.

The hydrophilic organic substance substantially insoluble in water preferably has the form of particles and / or fibrous substances. The term “particulate” basically refers to a sphere, but may be distorted or have irregularities. An intricately shaped shape such as so-called fumed silica can also be preferably used. The fibrous material refers to a long and thin shape in which the ratio of the major axis to the minor axis exceeds 3.

The diameter of the particle (meaning the maximum diameter other than a sphere)
Is preferably 500 μm or less, and more preferably 100 μm or less. If the diameter is large, detachment from the matrix increases, dust increases, and durability as a polishing pad tends to decrease, which is not preferable. Therefore, 1 to 50μ
m is most preferably used. The fibrous material may be a hollow fiber. The cross-sectional shape may be any shape proposed as a new synthetic fiber such as a circle, an ellipse, and a star.

The ratio of particles and / or fibrous materials occupying the surface of the polishing pad, that is, the surface density of the hydrophilic organic substance substantially insoluble in water, which varies depending on the matrix, is not limited to a polyamide resin or a polyamide resin having a high water absorption rate. It may be low for a polyurethane-based resin, but needs to be set high for a polyacryl-based resin such as polymethyl methacrylate or polyimide. Generally, the range of 5% to 80% is preferably used, but it is necessary to appropriately set an optimum value for each combination of resins. This operation can be easily performed by those skilled in the art. Also in this case, if the surface density increases, the physical properties of the polishing pad tend to be weak and brittle, and the polishing characteristics such as dishing and erosion tend to occur and deteriorate.

The bending elastic modulus of the polishing pad can be made larger than that of the conventional polishing pad as described above. In order to improve the flattening characteristics, it is preferably 0.5 GPa or more, more preferably 2 GPa or more. In the polishing pad of the present invention, since there is no problem of dust adhesion and scratch damage, a larger 5 GPa or more and 20 GPa or more.
a or less is more preferable. . However, if it is too large, it becomes difficult to mount the polishing pad.

It is preferable that grooves and holes are provided on the surface for the purpose of promoting supply to and removal from the polishing surface. The shape of the groove can be concentric, spiral, radiating,
Various shapes such as a grid pattern can be adopted. As the cross-sectional shape of the groove, a shape such as a square, a triangle, and a semicircle can be adopted. The groove depth ranges from 0.1 mm to the thickness of the polishing layer, the groove width ranges from 0.1 to 5 mm, and the groove pitch ranges from 2 to 100.
mm. The holes may or may not penetrate the polishing layer. The diameter of the holes can be selected in the range of 0.2-5 mm. The pitch of the holes can be selected in the range of 2 to 100 mm. These shapes may be sufficient to supply the polishing liquid to the polishing surface successfully, to enhance the holding ability of the polishing liquid, and to satisfactorily discharge and / or promote the polishing liquid from the polishing liquid. The shape of the polishing pad itself can be processed into various shapes such as a disk shape, a donut shape, and a belt shape.
Thicknesses of about 0.1 mm to about 50 mm or more can also be manufactured. As for the diameter when processed into a disc shape or a donut shape, the diameter is manufactured to about 1/5 to about 5 times based on the size of the object to be polished, but if it is too large, the processing efficiency decreases. Therefore, it is not preferable.

The polishing pad obtained by the present invention can be used as a composite polishing pad by laminating it with a cushion sheet having cushioning properties. A semiconductor substrate has slightly larger undulations apart from local irregularities, and a polishing sheet is often polished with a cushion sheet below a hard polishing pad (on the polishing platen side) as a layer for absorbing the undulations. As the cushion sheet, a combination of urethane foam type and rubber type can be used.

When the polishing pad of the present invention is used, for example, in the manufacture of semiconductor chips, first, it is employed for polishing a semiconductor wafer (bare wafer and / or wafer with an oxide film) before the surface is roughened. It is preferable to eliminate surface irregularities expressed as fine irregularities, that is, waviness, nanotopology, and the like. Thereafter, a surface pattern is processed by lithography or the like, and CMP polishing is performed. By performing this process using the polishing apparatus according to the present invention, processing with extremely high flatness becomes possible, and it is possible to easily meet the demands for multilayered semiconductor chips, high integration, and fine wiring. become. Further, it is preferable to use a polishing pad of the present invention in which mixing of sodium ions is suppressed to 400 ppm or less. More preferably 50 ppm
Or less, more preferably 10 ppm or less.

The evaluation of the flexural modulus, the D hardness, the amount of dust attached, the polishing rate of the oxide film, the evaluation of the flattening characteristic, and the evaluation of the dishing were performed as follows. (Measurement of flexural modulus) 1.0 mm thick from polishing pad
A rectangular test piece of 1 × 8.5 cm in the range of １．５1.5 mm was prepared. About this test piece, ORIENTEC
The flexural modulus was measured according to JIS-7203 using a material testing machine (Tensilon RTM-100) manufactured by the company. The flexural modulus was determined according to the following equation. (Each distance is in mm.) Flexural modulus = {(distance between fulcrums) ³ x (load (kgf) at an arbitrary point on the first straight line of the load-deflection curve)} / 4
(Width of test piece) × (thickness of test piece) ³ × (deflection under load F)｝ (measurement of D hardness) Samples in the range of thickness 1.0 mm to 1.5 mm (size is 1 cm square or more) ) With a D hardness of 90
Using a durometer type D (actually, “Asker D-type hardness meter” manufactured by Kobunshi Keiki Co., Ltd.) based on JIS standard (hardness test) K6253 and placed on a plane having the above surface hardness, Five points were measured and the average value was defined as D hardness. The measurement was performed at room temperature (25 ° C.). (Measurement of dust adhesion amount) Thickness 1.2mm, diameter 38cm
Create a circular polishing pad with a width of 2.0 mm on the surface,
So-called XY groove processing (grid-like groove processing) with a depth of 0.5 mm and a pitch of 15 mm was performed. This pad is used as a cushion layer on a surface plate of a polishing machine (Lap Master SFT Co., Ltd., "L / M-15E"), and is manufactured by Rodale Suba40.
0, and a double-sided adhesive tape (“44” manufactured by 3M)
2J "). Conditioner (" CMP-M ", diameter 14.2cm) of Asahi Diamond Industry Co., Ltd.
Using a pressing pressure of 0.04 MPa and a platen rotation speed of 25.
The polishing pad was rotated in the same direction at 25 rpm and a conditioner rotation number of 25 rpm, and the polishing pad was conditioned for 5 minutes while supplying pure water at 10 ml / min. While flowing 100 ml / min of pure water through the polishing machine, 2
After washing for one minute, a wafer with an oxide film (4-inch dummy wafer CZP type, Shin-Etsu Chemical Co., Ltd.) was set on a polishing machine, and a slurry dispersion (“SC-1” manufactured by Cabot Corporation) having the concentration described in the instruction manual was used. ) Is supplied onto the polishing pad at a rate of 100 ml / min, while the pressing pressure is 0.04 MPa, the rotation speed of the platen is 45 rpm, and the rotation speed of the conditioner is 45 rpm.
, And polished for 5 minutes. Make sure that the wafer surface does not dry,
Wash the wafer surface with polyvinyl alcohol sponge,
Dry compressed air was blown to dry. Thereafter, the number of surface dust having a diameter of 0.5 μm or more was measured using a wafer surface dust inspection device (“WM-3” manufactured by Topcon Corporation).
In this test method, if the number is 400 or less, the test passes without causing any problem in semiconductor production. The number of scratches on the surface of the polished wafer is determined by a digital microscope (VH630 manufactured by Keyence Corporation) equipped with an automatic XY stage.
0). 10 or less were defined as acceptable areas.

(Measurement of Oxide Film Polishing Rate) The thickness of the oxide film on the surface of a wafer (4-inch dummy wafer CZP type, Shin-Etsu Chemical Co., Ltd.) was previously determined by "Lambda Ace" (VM-2000) manufactured by Dainippon Screen Co., Ltd. 196 points determined by using are measured. Polishing machine (Lap Master SF
Polishing pad to be tested with double-sided adhesive tape (3M, "442J"), with Rodale's "Suba400" applied as a cushion layer to the surface plate of "L / M-15E", manufactured by T. Was stuck. Asahi Diamond Industry Co., Ltd.
Conditioner ("CMP-M", diameter 14.2c)
m), the polishing pad was rotated in the same direction at a pressing pressure of 0.04 MPa, a platen rotation speed of 25 rpm, and a conditioner rotation speed of 25 rpm, and the polishing pad was conditioned for 5 minutes while supplying pure water at 10 ml / min. The polishing pad was washed for 2 minutes while flowing 100 ml / min of pure water through the polishing machine. Then, the wafer with the oxide film whose oxide film thickness had been measured was set in the polishing machine, and the concentration described in the instruction manual was used by Cabot Corporation. Add the slurry dispersion (“SC-1”) to 1
While supplying onto the polishing pad at 00 ml / min, the plate was rotated in the same direction at a pressing pressure of 0.04 MPa, a platen rotation speed of 45 rpm, and a conditioner rotation speed of 45 rpm.
Polishing was performed for a minute. The surface of the wafer was not dried, and the surface of the wafer was washed with a polyvinyl alcohol sponge while being immediately sprayed with pure water, and dried by blowing dry compressed air. The thickness of the oxide film on the wafer surface after the polishing is determined by "Lambda Ace" (VM-20, manufactured by Dainippon Screen Co., Ltd.).
196 points determined by using (00), the polishing rate at each point was calculated, and the average value was taken as the oxide film polishing rate. (Evaluation of Flattening Characteristics) First, a test wafer for global level difference evaluation was prepared in the following procedure. Test wafer for global level difference evaluation: A 10 mm square die is arranged on a 4-inch silicon wafer with an oxide film (oxide film thickness: 2 μm).
Perform mask exposure using photoresist, and
E places a line of 20 μm width and height of 0.7 μm and a space of 230 μm in the left half in a 10 mm square die in a line and space, and places a line of 230 μm width and height of 0.7 μm right in a space of 20 μm. Place in half line and space.

A circular polishing layer having a diameter of 38 cm was prepared, and the surface was subjected to a so-called XY groove processing (lattice-shaped groove processing) having a width of 2.0 mm, a depth of 0.5 mm, and a pitch of 15 mm. This polishing pad is applied to a surface plate of a polishing machine (Lap Master SFT, L / M-15E) as a cushion layer, to which a “Suba400” manufactured by Rodale is applied, and a double-sided adhesive tape (“442J” manufactured by 3M) is applied thereon. ). Asahi Diamond Industrial Co., Ltd. Conditioner (“CMP
-M ", diameter 14.2 cm) and a pressure of 0.
04MPa, rotating in the same direction at a platen rotation speed of 25rpm and a conditioner rotation speed of 25rpm, 10ml of pure water
The polishing pad was conditioned for 5 minutes while supplying at a rate of / min. 100ml / min of pure water in polishing machine
The polishing pad was washed on the polishing pad for 2 minutes while flowing, and then a test wafer for global level difference evaluation was set on the polishing machine, and a slurry (“SC-1”) manufactured by Cabot Corporation with the concentration described in the instructions was used.
While supplying 100 ml / min onto the polishing pad.
Pressing pressure 0.04MPa, platen rotation speed 45rpm
(The linear velocity at the center of the wafer is 3000 (cm / min)),
The sample holder holding the semiconductor wafer was rotated in the same direction at a rotation speed of 45 rpm, and polishing was performed for a predetermined time. The surface of the semiconductor wafer was not dried, and the surface of the wafer was washed with a polyvinyl alcohol sponge while being immediately sprayed with pure water, and dried by blowing dry compressed air. The oxide film thickness of the 20 μm line and 230 μ line in the center 10 mm die of the test wafer for global level difference evaluation was measured using Lambda Ace (“VM-2000”) manufactured by Dainippon Screen Co., Ltd. Was evaluated. Regarding the processing form of the polishing layer, other shapes were processed in the same procedure as above. 20 μm wide wiring area and 23
The global step in the 0-μm-wide wiring region passed the test if the polishing time was 5 minutes and 45 nm or less. (Evaluation of dishing) Tungsten wiring dishing evaluation test wafer: A groove having a width of 100 μm and a depth of 0.7 μm is formed at intervals of 100 μm on a 4-inch silicon wafer with an oxide film (oxide film thickness: 2 μm). A tungsten film having a thickness of 2 μm was formed thereon by sputtering to prepare a test wafer for evaluating dishing of tungsten wiring.

A circular polishing layer having a diameter of 38 cm was prepared, and the surface was subjected to a so-called XY groove processing (grid-like groove processing) having a width of 2.0 mm, a depth of 0.5 mm, and a pitch of 15 mm. This polishing pad is applied to a surface plate of a polishing machine (Lap Master SFT, L / M-15E) as a cushion layer, to which a “Suba400” manufactured by Rodale is applied, and a double-sided adhesive tape (“442J” manufactured by 3M) is applied thereon. ). Asahi Diamond Industrial Co., Ltd. Conditioner (“CMP
-M ", diameter 14.2 cm) and a pressure of 0.
04MPa, rotating in the same direction at a platen rotation speed of 25rpm and a conditioner rotation speed of 25rpm, 10ml of pure water
The polishing pad was conditioned for 5 minutes while supplying at a rate of / min. 100ml / min of pure water in polishing machine
The polishing pad was washed for 2 minutes while flowing, and then a test wafer for evaluating tungsten wiring dishing was set on the polishing machine. A slurry manufactured by Cabot Corporation (“SEMI-SPERSE W-A400”) having a concentration described in the instruction manual and a Cabot Corporation were used. Oxidizing agent (“SEMI-SPERSE FE-
400 ") at a ratio of 1: 1
While supplying onto the polishing pad at 1 / min, the pressing pressure is 0.04 MPa, the platen rotation speed is 45 rpm (the linear velocity at the center of the wafer is 3000 (cm / min)), and the semiconductor wafer holding sample table is rotated at 45 rpm. Rotate in the same direction, 2
Polishing was performed for a minute. The surface of the semiconductor wafer was not dried, and the surface of the wafer was washed with a polyvinyl alcohol sponge while being immediately sprayed with pure water, and dried by blowing dry compressed air. The dishing state of the tungsten surface can be measured by using Keyence's ultra-depth shape measuring microscope “VK-85”.
The surface of the polishing layer was processed in the same manner as described above for other shapes. The center depth of the tungsten wiring was measured to be 0.04 μm.
If it was below, it was judged as pass. Hereinafter, the present invention will be described in more detail with reference to examples.

[0032]

The evaluation results (flexural modulus, D hardness, dust adhesion amount, oxide film polishing rate, evaluation of flattening characteristics, measurement of dishing) obtained in the examples and comparative examples are shown in Table 1.
It was shown to. The voids were confirmed using a 50 × optical microscope.

Example 1 Ultrafine core-sheath fiber having a polyvinyl alcohol core (diameter 3
35 parts by weight (aspect ratio 100) of 0 μm in which the sea portion is polystyrene, the official moisture content is 5%, and the length is 3 mm, and MMA (methyl methacrylate) / AIB
65 parts by weight of N (azoisobutyronitrile) = 999/1 were mixed and polymerized between the plates, and a polishing pad was prepared from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the fiber made of polyvinyl alcohol.

Example 2 A filter paper powder (official moisture content: 11%) manufactured by Tosco Corp.
% By weight of polypropylene (Mitsubishi Chemical Corporation)
And a uniaxial kneading compound at 160 ° C. Tosco's filter paper powder is obtained by cutting hemp into a length of about 25 μm, and has a fibril structure having a thickness of about 1 μm (aspect ratio: about 25). Using a pellet obtained by cutting the compound to a length of 3 mm, using a 40 cm square mold, 185
Hot press molding was performed at ℃. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the filter paper powder.

Example 3 A liquid phenol resin (manufactured by Sumitomo Durez, PR-55123) was added to a filter paper powder (manufactured by Tosco Corporation, 11% in official moisture ratio, about 25 in aspect ratio) to a dry weight ratio of 55 parts by weight. Impregnated, dried, 170MPa for 20 minutes 3.5MPa
It was molded to a thickness of 1.2 mm under pressure. A polishing pad was formed from the obtained resin plate. The cross section was observed with an optical microscope,
No void was found in the filter paper powder.

Example 4 "Art Farmer" (TA-1327, manufactured by Sanyo Chemical Industries, Ltd.) was added to a filter paper powder (manufactured by Tosco Corporation) having an official moisture content of 11% and an aspect ratio of about 25 at a predetermined mixing ratio. 45 parts by weight of the mixture was mixed and poured into a 40 cm square mold.
After defoaming at 0 ° C., the mixture was heated at 165 ° C. to form a resin plate. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the filter paper powder.

Example 5 Ultrafine core-sheath fiber having a core of nylon 66 (diameter: 30 μm)
The sea part is polystyrene, the official moisture content is 5%) and the length is 3
mm (aspect ratio about 100)
Parts by weight and "Art Farmer" (Sanyo Chemical Industries, Ltd.)
And TA-1327) were mixed at a predetermined mixing ratio, and 60 parts by weight were mixed, poured into a 40 cm square mold, degassed at 100 ° C, and heated at 165 ° C to form a resin plate. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the ultrafine sheath fiber with nylon 66 as the core.

Example 6 35 parts by weight of wool (official moisture content: 15%) cut to a length of 3 mm (aspect ratio: about 1000) were 51 parts by weight of a two-component polyurethane resin C-4421 (manufactured by Nippon Polyurethane Co., Ltd.). Parts and 49 parts by weight of N-4276 (manufactured by Nippon Polyurethane Co., Ltd.) were kneaded and mixed with 65 parts by weight, and after degassing in vacuo, poured into a 40 cm square mold, and
C. to form a resin plate. When the cross section was observed with an optical microscope, no void was found in the wool.

Example 7 18 parts by weight of filter paper powder (manufactured by Tosco Corporation, 11% in official moisture ratio, about 250 aspect ratio) made by dry weight of a liquid phenol resin (PR-53717, manufactured by Sumitomo Durez) was 82 parts by weight. The mixture was kneaded, dried, and molded at a temperature of 170 ° C. for 20 minutes under a pressure of 4 MPa to a thickness of 1.2 mm. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, voids were found in the filter paper powder.

Example 8 A filter paper powder (manufactured by Mitsubishi Chemical Co., Ltd.) was mixed with filter paper powder (manufactured by Mitsubishi Chemical Corporation) at a temperature of 2.5% by weight with filter paper powder (manufactured by Tosco Corporation) at a moisture content of 11% and an aspect ratio of about 250. Shaft kneading compound. Using a pellet obtained by cutting the compound into a length of 3 mm, hot press molding was performed at 185 ° C. using a 40 cm square mold. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the filter paper powder.

Example 9 In Example 3, 3 parts by weight of silica particles having a pore size of 1 μm were mixed in addition to the filter paper powder to form a resin plate, and a polishing pad was prepared from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the filter paper powder.

Examples 10 to 15 In each of Examples 1 to 3, 5 to 7, 0.8 parts by weight of xanthan gum was further added as a hydrophilic water-soluble resin to prepare abrasive resin plates.

Example 16 18 parts by weight of filter paper powder (manufactured by Tosco Corporation, 11% in official moisture content, aspect ratio of about 250) and 3 parts by weight of silica particles having a pore size of 1 μm were mixed, and a liquid phenol resin (manufactured by Sumitomo Durez; PR-53717) was impregnated and dried at a dry weight ratio of 79 parts by weight, and dried at 170 ° C. for 20 minutes at 3.5 MPa.
It was molded to a thickness of 1.2 mm under pressure. A polishing pad was formed from the obtained resin plate. The cross section was observed with an optical microscope,
No void was found in the filter paper powder.

Example 17 Ultrafine core-sheath fiber having a core of nylon 66 (diameter: 30 μm)
The sea part is polystyrene, the official moisture content is 5%) and the length is 3
mm (aspect ratio 100) was mixed with 30 parts by weight of silica particles having a pore size of 1 μm, and a liquid phenol resin (PR-55, manufactured by Sumitomo Durez) was mixed.
123) The mixture was mixed with 30 parts by weight on a dry basis, poured into a 40 cm square mold, dried at 70 ° C., and then heated at 165 ° C. to form a resin plate. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, voids were found in the ultrafine core sheath fiber with nylon 66 as the core.

Example 18 In Example 7, the pressure relief during the molding of the resin plate was adjusted to form voids both in the filter paper powder and in the phenol resin. A polishing pad was formed from the obtained resin plate.

Example 19 A resin plate was prepared by further adding 2 parts by weight of xanthan gum as a hydrophilic water-soluble resin in Example 7. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the powdered filter paper.

Comparative Example 1 A liquid phenol resin (PR-55123, manufactured by Sumitomo Durez) was mixed with polyethylene terephthalate fiber (manufactured by Toray, cut to 13 μm in pore diameter, 13 μm length, aspect ratio 1, official moisture content 0.4%). Mix and dry so that the dry weight ratio becomes 45 parts by weight, and 170MPa for 20 minutes 3.5MP
a Formed to a thickness of 1.2 mm under pressure. A polishing pad was formed from the obtained resin plate. When the cross section was observed with an optical microscope, no void was found in the filter paper powder. No voids were observed in the matrix.

Comparative Example 2 Polypropylene fiber (official moisture content 0%, diameter 13 μm,
97.5 parts by weight of MMA (methyl methacrylate) / AIBN (azoisobutyronitrile) = 999/1 was mixed with 100 μm length, aspect ratio 7.7) and polymerized between the plates to obtain a resin plate. To prepare a polishing pad. When the cross section was observed with an optical microscope, no void was found in the polypropylene fiber. Table 1 shows the results.

[0049]

[Table 1]

[0050]

According to the present invention, dust adhesion to the surface of the object to be polished can be reduced.

Claims (11)

[Claims] A polishing pad comprising a mixture of particles formed of a fibrous material having a hydrophilic and substantially water-insoluble aspect ratio of 5 or more and / or a composite thereof. 2. The polishing pad according to claim 1, wherein the particles formed of the fibrous material and / or the composite thereof are substantially free of voids. 3. The polishing pad according to claim 1, wherein the official moisture regain of the particles formed of the fibrous material and / or the composite thereof is 3% or more. 4. The polishing pad according to claim 1, wherein the polishing pad further has voids apart from the particles formed of the fibrous material and / or the composite thereof. 5. The polishing pad according to claim 1, further comprising inorganic fine particles. 6. The polishing pad according to claim 1, wherein the D hardness exceeds 65. 7. The polishing pad according to claim 1, further comprising a water-soluble substance. 8. The polishing pad according to claim 7, wherein the polishing pad contains 0.01 wt% to 10 wt% of a water-soluble substance. 9. A polishing apparatus using the polishing pad according to any one of claims 1 to 8. 10. A polishing method using the polishing pad according to claim 1. 11. A method for manufacturing a semiconductor wafer and a semiconductor chip, characterized by processing using the polishing pad according to claim 1.