JP2003039308A - Polishing pad and polishing device and method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of improving flatness during polishing and suppressing adhesion of dust and generation of a scratch flaw. SOLUTION: This polishing pad to be used for polishing an object to be polished is characterized by containing resin and/or filler having an official moisture ratice >=3% and a percentage of water absorption <=15% when impregnated in water for one hour.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention presses an object to be polished against a rotating elastic pad while supplying a polishing liquid containing working abrasive grains and performs relative movement to finish the surface of the object to be polished to a mirror surface. Alternatively, chemical mechanical polishing (CMP) for preferentially polishing the convex and concave portions of the surface of the object to be polished with an abrasive
The present invention relates to a polishing pad used for, for example, a polishing apparatus and a polishing method using the same.

[0002]

2. Description of the Related Art In order to realize a multi-layer wiring in manufacturing a semiconductor having a high degree of integration, it is necessary to completely flatten the surface of an insulating film. So far, as a typical technique of this flattening method, SOG (Spin-On-Glass) method and etch back method (Elikins, K. Reinhardt, and R. La.
yer, "A Planarization process for double metal CMOS
using Spin-on Glass as a sacrificial layer, "Procee
ding of 3rd International IEEE VMIC Conf., 100 (198
6)) and the lift-off method (K. Ehara, T. Morimoto, S. Mu
ramoto, and S.Matsuo, "Planar Interconnection Techno
logy for LSI FabricationUtilizing Lift-off Proces
s ", J. Electrochem Soc., Vol. 131, No. 2, 419 (1984).) have been studied.

Regarding the SOG method, this is a planarization method utilizing the fluidity of the SOG film, but it is impossible to carry out complete planarization by itself. Further, the etch back method is the most widely used technique, but it has a problem of dust generation due to simultaneous etching of a resist and an insulating film, and is not an easy technique from the viewpoint of dust management. The lift-off method has not been put to practical use because the stencil material to be used is not completely melted during lift-off and thus cannot be lifted off, and the controllability and the yield are incomplete.

Therefore, the CMP method has been attracting attention in recent years. This is a method of pressing the work piece against a rotating elastic pad and performing relative movement while preferentially polishing the convex and concave parts of the work piece surface with a polishing pad. Widely used. Further, in recent years, the fine irregularities of the semiconductor wafer itself before the irregularity processing, that is,
Surface defects such as waviness and nanotopology, which have not been problematic in the past, have become a problem, and double-sided polishing and polishing while flowing alkali are being used.

[0005]

However, in the CMP method, there are problems such as scratches on the surface of the object to be polished, dust adhesion, and poor global flatness. For example, when such dust adheres or scratches occur on the surface to be polished such as an interlayer insulating film, step breakage or the like occurs when a wiring made of Al, Cu-based metal, or the like is formed thereon in a later step, There is a possibility that reliability may deteriorate such as deterioration of electromigration resistance.
Also, in polishing non-magnetic substrates for HDDs (Hard Disk Drives), dropouts and the like may cause reproduction signal loss. The generation of scratches is considered to be caused by agglomerates due to poor dispersion of abrasive particles. In particular, the polishing slurry that uses alumina as the polishing particles, which is used for CMP of a metal film, has poor dispersibility, and scratch scratches have not been completely prevented. At present, the cause of the adhesion of foreign matter such as dust is not well understood. It is common sense that a hard polishing pad is desirable to improve the global flatness, but conversely, it is considered that dust adhesion and scratch scratches are likely to occur, and thus both cannot be compatible.

For example, Japanese Patent Laid-Open No. 8-500622 and Japanese Patent Laid-Open No. 2000-344.
Although attempts have been made to do so in 16 etc., it has not reached the point where dust adhesion / scratch scratches and flattening characteristics are compatible.

An object of the present invention is to provide a polishing pad which can significantly reduce the adhesion of foreign matter such as dust to the surface of an object to be polished and the occurrence of scratches, and can also improve the flattening property of the surface of the object to be polished. Another object of the present invention is to provide a polishing device and a polishing method.

[0008]

In order to solve the above-mentioned problems, the polishing pad of the present invention is a polishing pad used for chemical mechanical polishing of an object to be polished, wherein the resin has an official moisture content of 3% or more. And / or containing a filler and having a water absorption rate of 15% or less when immersed in water for 1 hour.

The polishing pad may contain a water-insoluble hydrophilic substance. The inclusion of a water-insoluble hydrophilic substance improves the wettability of the surface of the polishing pad and prevents the adhesion of foreign matter such as dust. Further, the polishing pad may contain inorganic particles and / or a water-soluble substance. When the inorganic particles are contained, the polishing effect of the object to be polished such as the substrate can be improved by the synergistic action of the inorganic particles and the abrasive particles in the polishing slurry, and the hardness of the polishing pad can be increased to make the surface flat. The characteristics will be better. Further, if the polishing pad contains a water-soluble substance, the amount of water retained in the polishing pad can be improved. That is,
Usually, since the polishing pad is made of a resin, the water-soluble substance is held by the resin and the elution is suppressed, but the swelling of the water-soluble substance can improve the water retention amount of the polishing pad, and The wettability can be improved. Further, when the water-soluble substance is eluted in the polishing slurry, the viscosity of the polishing slurry increases, so that the polishing effect can be particularly improved on the concave portion, and the global flatness (flatness of the entire object to be polished) is improved. Can contribute to.

The content of the water-soluble substance is preferably within the range of 0.01 wt% to 10 wt% based on the weight of the polishing pad. If it is less than 0.01% by weight, the improvement of the polishing effect due to the improvement of the wettability of the pad surface cannot be expected. On the other hand, if it exceeds 10 wt%, the swelling rate of the polishing pad becomes too large, which is not preferable.

The polishing pad of the present invention is preferably made of resin and has a plurality of holes on its surface. Shavings during polishing are accumulated in the holes as described above, the polishing interface is kept clean, and the polishing rate can be increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a polishing apparatus according to an embodiment of the present invention. In the figure,
Reference numeral 1 denotes a polishing device. The polishing apparatus 1 has a polishing surface plate 3 on which the polishing pad 2 can be mounted.
Can be rotated in the direction of the arrow by the drive mechanism 4.

Above the polishing pad 2, the polishing pad 2 is provided.
There is provided a dressing mechanism 5 for dressing.
The dressing mechanism 5 rotates in the direction of the arrow while contacting the polishing pad 2 to dress the polishing pad 2.

A pipe 7 for supplying the polishing slurry 6 to the polishing pad 2 is provided above the polishing pad 2. The polishing slurry 6 in the polishing slurry reservoir (not shown) is supplied onto the polishing pad 2 through the pipe 7.

A semiconductor wafer 8 as an object to be polished is mounted on a polishing head mechanism 9. The polishing head mechanism 9 is provided with a sticking plate 10 to which the wafer 8 is fixed. The sticking plate 10 is rotatable in the arrow direction of FIG. Further, the polishing head mechanism 9 is configured to be movable in the vertical direction of FIG. Therefore, the wafer 8 fixed to the attachment plate 10 can be pressed against the polishing pad 2 with an arbitrary pressure.

In this embodiment, the polishing pad 2 is mounted on the polishing platen 3, the polishing slurry 6 is rotated while being supplied onto the polishing pad 2, and the wafer 8 is pressed against the polishing pad 2 while rotating. As a result, the uneven portion on the surface of the wafer 8 is polished.

In the present invention, by using the polishing pad 2 containing a resin and / or a filler having an official moisture regain of 3% or more and having a water absorption rate of 15% or less when immersed in water for 1 hour, The adhesion of dust and scratches are prevented, and the flatness of the surface of the wafer 8 is improved. That is, from the viewpoint of preventing dust from adhering and scratches from occurring, it is preferable that the polishing pad 2 has a swelling layer having a high water absorption and a soft surface. However, if the polishing pad becomes too soft, for example, the polishing rate is likely to be reduced and variations are likely to occur, and the polishing characteristics are degraded. On the other hand, when the water absorption of the polishing pad 2 is kept low and the surface is hardened, the polishing characteristics can be improved, but the adhesion of dust and the generation of scratches cannot be effectively prevented.

The official moisture regain as used in the present invention is the dry weight of polymer fine particles dried in a nitrogen atmosphere at 50 ° C. for 24 hours and the moisture absorption weight after 24 hours in an atmosphere of 65% relative humidity and 20 ° C. , (Moisture absorption weight-dry weight) / dry weight x
It is the moisture content obtained by the formula of 100. Official moisture content is 3%
By containing the above resin and / or filler, scratches and dust adhesion that occur on the semiconductor wafer 8 can be suppressed. Scratch scratches are scratches on the wafer surface due to polishing dust and aggregates of abrasive grains in the slurry 6. The adhesion of the dust includes the adhesion of the floating dust and the adhesion of the abrasive grains in the slurry 6 to the semiconductor wafer.

It is preferable that the resin having the official moisture regain of 3% or more is water-insoluble in order to further suppress scratches and dust adhesion. Water-insoluble means 100 high polymer particles.
Disperse in twice the weight of water, stir and mix at 50 ° C. for 6 hours,
The obtained aqueous solution is filtered through a membrane filter having a pore size of 0.45 μm, the weight of the water-soluble component contained in the filtered water is measured, and the dry weight of the water-soluble component is 30 wt.
% Or less. Specific examples of the resin material having an official moisture content of 3% or more include cellulosic polymers, acrylic polymers, vinyl polymers, aramid polymers, amide polymers, starch polymers and the like. Yes, but not limited to.

The filler having an official moisture regain of 3% or more is preferably hydrophilic and water-insoluble. The filler is preferably selected from at least one of non-woven fabric, woven fabric, knitted fabric, felt, porous film, sponge, film, particles and fibrous form.
The non-woven fabric refers to a cloth in a broad sense in which fibers are entangled, but it may be distorted or may have irregularities. Non-woven fabric, woven fabric,
Knitted and felt-like materials are also obtained from fibrous materials. The porous film shape and the sponge shape mean a membrane in a broad sense in which two-dimensionally and / or three-dimensionally open pores have a large porosity, and the film shape means one having substantially no open pores. The term "particulate" basically means a spherical shape, but it may be distorted or uneven. A distorted shape such as so-called fumed silica can also be preferably used. Further, the long fibers may be cut into short pieces. 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 fibers constituting these (in the case of other than spheres, the maximum diameter) is preferably 100 μm or less, 50
The thickness of less than μm is more preferably used, and the thickness of about 2 to 20 μm is preferably used. Some ultrafine fibers have a diameter of less than 2 μm, and it is convenient to use these. When the diameter is large, the number of separations from the polishing pad increases, and the durability of the polishing pad decreases, which is not preferable. The fibrous material may be a hollow fiber. The cross-sectional shape may be a synthetic fiber such as a circle, an ellipse, or a star, or any shape proposed as a new synthetic fiber. Porous membrane,
The sponge-like material has pores connected to each other by a thin column, and the diameter thereof is usually about 10 nm to 1 mm, but the size is not limited. By occupying the ratio of voids in the total volume, that is, using a high percentage of voids exceeding 25%, by compressing in the thickness direction and molding,
It is preferably used because it can suppress variations in the thickness direction. Further, the film-like material is preferably used for forming a layer (separation layer) for separating the individual layers of the laminate.
In particular, an ultrathin film having a thickness of less than 1 μm can be used in the same manner as a non-woven fabric, woven fabric, knitted fabric, felt fabric, porous film fabric, and sponge fabric.

A plurality of sheet-like layers prepared by mixing these fillers are laminated to form one polishing pad 2. Therefore, the polishing pad 2 according to the present invention using a sheet-like material for the filler has extremely high bending strength,
Very few cracks. It is of course possible to form the polishing pad with one sheet by using a sheet-shaped material having a large thickness. In addition to these, it can be combined with a sheet-like layer in which a filler is not mixed. By forming a layer having a thickness of about 1 μm or more per sheet and stacking a plurality of layers, the stability of the polishing characteristics is higher, and it becomes easier to form a polishing pad capable of finely controlling the state of the polished surface. Usually, 5 μm or more is used, and optimally 100 to 300 μm is used. The thickness and material of each layer do not have to be the same, and by changing the resin content and / or type of the matrix resin for each layer, or by changing the thickness and / or type of the sheet material for each layer, the polishing pad Can be designed precisely.

For example, a cushion layer made of polyurethane foam or a rubber sheet is set as a set of a polishing layer portion, a cushion layer portion, and a separation layer portion, and a plurality of layers are laminated to form a polishing pad on a polishing platen. If you paste it once,
It is possible to provide a long-life polishing pad that does not need to be replaced for a long time, which is many times longer than the conventional one. By providing a separation layer, the polishing layer part does not come into contact with the polishing liquid or the polishing dispersion that has infiltrated from the polishing surface, and the virgin surface formed by dressing can be used for polishing, so extremely high polishing stability Can be obtained. Also, when the interlayer insulating film and metal polishing are required alternately, it is best suited for the purpose. For example, a very hard layer is used for interlayer insulating film polishing, and a soft layer is used for metal polishing. You can also do it. As described above, according to the present invention, it is possible to improve the throughput for manufacturing and reduce the total cost.

The resin constituting the polishing pad 2 and the organic polymer matrix include polyamide type, polyacrylic type,
A thermoplastic resin such as a polyolefin-based resin, a polyvinyl-based resin, an ionomer-based resin, a polycarbonate-based resin, a polyacetal-based resin, a polyurethane-based resin, a polyimide-based resin, a derivative thereof, a copolymer, or a graft body can be used.
Mixtures of these may be used, but it is important to mix them so that hardness can be obtained. For example, by mixing inorganic fine particles,
It is also effective to devise ways to improve the hardness. The technology disclosed in nanocomposite 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 such as zeolite, and the like can be used. It is also possible to mix them. It is also possible to modify the surface in advance in order to improve the compatibility with the matrix. A particle size of about 3 nm to about 50 μm can be used, but if it is too large, the risk of scratching increases. Therefore, the thickness is more preferably 20 μm or less, further 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. can be effective even at about 1%, about 80% You can mix up to. When mixed at a high concentration, not only is the effect of increasing the hardness of the polishing pad effective, but also effective as a so-called fixed abrasive polishing pad containing abrasive grains. In this case, if the particle size is small, the effect is small, and the particle size is preferably 30 nm or more, and more preferably 100 nm or more from the viewpoint of improving the polishing rate. 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, epoxy, phenol, melamine, urea and polyimide. 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 forming the polishing pad may be appropriately selected based on desired hardness, elastic modulus and wear resistance.
Also in this case, the inorganic fine particles can be mixed as in the case of using the thermoplastic resin. Since a thermoplastic resin is generally softer than a thermosetting resin, the official moisture regain of a sheet-like material made of a hydrophilic organic substance which is substantially insoluble in water to be mixed may be low and is used from about 1%. ,
It is preferably 3% or more in order to reduce dust adhesion and scratches. Since the thermosetting urethane often has a higher weight gain than the thermoplastic urethane, the thermosetting resin preferably has an official moisture regain of 1 or more. Particularly in this case, 3% or more is preferable, and 5% or more is further preferable.

As another method, for example, it is also effective to mix inorganic fine particles and make an effort to improve the hardness of the polishing pad 2. The technology disclosed in nanocomposite can also be applied and developed. Specifically, as inorganic fine particles, silica, ceria, alumina, zirconia, titanium,
Tungsten, barium carbonate, barium sulfate, carbon black, clay such as montmorillonite, crystals such as zeolite and the like can be used. It is also possible to mix them. It is also possible to modify the surface in advance in order to improve the compatibility with the resin. A particle size of about 3 nm to about 50 μm can be used, but if it is too large, the risk of scratching increases.
Therefore, the thickness is more preferably 20 μm or less, and further 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 zeolite crystals are effective even if about 0.1%, 80% %
Can be mixed to a degree. When mixed at a high concentration, not only the effect of increasing the hardness of the polishing pad 2 but also a so-called fixed abrasive polishing pad containing abrasive grains is effective. In this case, if the particle size is small, the effect is small, and the particle size is preferably 30 nm or more, more preferably 100 nm or more from the viewpoint of improving the polishing rate. By changing the particle size and the mixing amount of these fine particles, it is possible to manufacture the polishing pad 2 that matches the characteristics of the object to be polished.

Examples of the polishing slurry 6 used in polishing using the polishing pad 2 of the present invention include silica type slurry, aluminum oxide type slurry, cerium oxide type slurry and the like. These can be used to locally flatten the unevenness of the insulating film and the unevenness of the metal wiring on the semiconductor wafer, reduce the global step difference, and suppress dishing. As a specific example of the slurry, "CAB-O-SP" for CMP manufactured by CABO Co., Ltd.
ERASE SC-1 ", CMP" CAB-O-SP "
ERSE SC-112 ", CMP" SEMI-SP "
ERSE AM100 "," SEMI-SPE for CMP "
RSE AM100C ", CMP" SEMI-SPE "
RSE 12 "," SEMI-SPERSE "for CMP
25 ", CMP" SEMI-SPERSE W200 "
0 ", CMP" SEMI-SPERSE W-A40 "
0 ″ and the like can be given, but the present invention is not limited thereto.

The hydrophilic and water-insoluble substance used in the polishing pad 2 of the present invention is, for example, cellulose or starch, polysaccharides such as chitin, proteins, acrylics such as polyacrylic acid and polymethacrylic acid, A resin such as aramid-based, polyamide-based, polyvinyl alcohol-based, ethylene-vinyl alcohol copolymer-based, polyvinyl polypyrrolidone or the like, or a cross-linked product or a copolymer containing the resin as a main component can be used. Natural fibers such as silk, wool, cotton, hemp, polyvinylpyrrolidone / polyvinylimidazole copolymer, super absorbent resin, pulp, rayon,
Paper and various charged celluloses for cellulose ester ion exchange are commercially available and can be effectively used. Further, a resin having a hydrophilic group such as a sulfone group, an amino group, a carboxyl group or a hydroxyl group introduced into a resin which is originally hydrophobic can be used. The term “hydrophobic” means that the weight increase rate when immersed in water at 50 ° C. for 24 hours is less than 2%. Further, it is preferable to use a material in which sodium ions are suppressed to 400 ppm or less because of the problem of permeation into the wafer 8. It is more preferably 50 ppm or less, and even more preferably 10 ppm or less.

The polishing pad 2 of the present invention may further contain a water-soluble substance. There are various polyalkylene glycols, polyvinyl vinylidone, polyvinyl alcohol, polyvinyl acetate, chitosan, polyvinyl pyrrolidone, polyvinyl imidazole, water-soluble polysaccharides, etc., which are commercially available, and these polymers can be used. . In addition to this, low molecular weight substances such as various inorganic salts may be mixed. In the present invention, when the polishing pad 2 is molded, since a substantially water-insoluble hydrophilic filler is included, the risk of excessive foaming increases when urethane is used, but rather than reactivity with water, This can be avoided by utilizing the high reactivity of the polyol component and the amine component. Of course, the filler is used after being dried, but it is difficult to completely remove the moisture, and therefore, voids can be formed in a portion other than the filler by foaming due to the moisture during molding. In order to control the size of the voids, for example, pressure may be applied during molding, a defoaming agent may be used, or a functional group having high reactivity with isocyanate may be introduced.

Further, when these water-soluble substances are dissolved during polishing, voids are formed only on the surface of the polishing pad, and these voids enhance the retention of loose abrasive grains in the polishing slurry and generate polishing debris. It is effective for removal, and as a result, works favorably for improving the polishing rate. Also, since this water-soluble substance can change its viscosity when it is dissolved in the dispersion liquid of the polishing liquid, for example, when xanthan gum, which is one of the water-soluble polysaccharides, is mixed, the polishing liquid dissolves in Bingham when it is dissolved. Since it has a fluid-like property and probably suppresses the diffusion of polishing particles in the recesses of the uneven semiconductor wafer, it has an effect of improving the flatness when polishing, especially the global flatness. In order to exert these effects, it is preferable to add a water-soluble substance in an amount of 0.01 wt% or more and 10 wt% or less based on the weight of the polishing pad. The effect is obtained even if a water-soluble substance is added in an amount of about 0.01 wt%, but preferably 0.1 wt% or more and 5 wt
% Or less is effectively used. If it exceeds 10 wt%, the properties of the polishing dispersion change too much, which is not preferable. Larger amounts can be mixed by using a low molecular weight substance that has little influence on the viscosity of the dispersion liquid, but it is not practical from the viewpoint of cost.

As a method for molding the polishing pad 2, a resin or a filler having an official moisture content of 3% or more, further inorganic fine particles and / or a water-soluble substance are mixed in advance, and then mixed with polyurethane before curing and defoamed. rear,
It can be placed in a mold and subjected to heat compression molding, or extrusion molding. Techniques such as injection press are also possible. Since the particles and / or fibrous substances are used, they can be mixed efficiently, so that variations in the physical properties of the resulting polishing pad 2 can be reduced. Further, if the filler is not mixed, the moldability is further improved. As for the polishing pad 2 of the present invention, it is possible to use a combination of known techniques for the manufacturing method.

It is preferable that the surface of the polishing pad 2 is provided with grooves or holes for the purpose of, for example, promoting the supply of the polishing slurry 6 to the surface of the polishing pad 2 and the discharge from the surface. As the shape of the groove, various shapes such as concentric circles, spirals, radiation, and grids can be adopted. The cross-sectional shape of the groove may be square, triangular, semicircular, or the like. The depth of the groove is in the range from 0.1 mm to the thickness of the polishing layer, the width of the groove is in the range of 0.1 to 5 mm, and the pitch of the groove is 0.1 to 100.
It can be selected in the range of mm. The holes may or may not penetrate the polishing layer. The diameter of the holes can be selected in the range of 0.1 to 5 mm. The pitch of the holes can be selected in the range of 0.1 to 100 mm. These shapes allow the polishing liquid (polishing slurry 6) to be well supplied to the polishing surface, enhance the retention of the polishing liquid, and satisfactorily discharge and / or promote polishing dust from the polishing liquid. Should be satisfied. The polishing pad itself can be processed into various shapes such as a disk shape, a donut shape, and a belt shape. The thickness is about 0.1mm to 5
It is possible to manufacture a product having a thickness of about 0 mm or more. Regarding the diameter when processed into a disk shape or a donut shape, the diameter is about 1/5 to 5 times as large as the size of the object to be polished, but if it is too large, the processing efficiency will decrease. Therefore, it is not preferable. The polishing pad 2 obtained in the present invention can be laminated with a cushion sheet having a cushioning property to be used as a composite polishing pad. In addition to local unevenness, the semiconductor substrate has slightly larger undulations. In many cases, a cushion sheet is placed under a hard polishing pad (on the side of the polishing surface plate 3) as a layer for absorbing the undulations for polishing. As the cushion sheet, urethane foam type and rubber type can be used in combination.

[0032]

EXAMPLES The present invention will be described below with reference to examples. The methods for evaluating and measuring the physical properties used in the examples are according to the following methods.

(Water content when immersed in water for 1 hour) A test piece (size: 25 × 60 mm, regardless of thickness) obtained by cutting out a polishing pad was vacuum dried at 80 ° C. for 10 hours, and then in pure water at room temperature. After 60 minutes, the test piece was placed in a centrifuge tube and subjected to a centrifugal force of 1400 G to 1450 G for 30 seconds to measure the moisture absorption weight in a state where water was shaken off. At this time, the moisture absorption rate was obtained according to the following formula. Water absorption rate (%) = {(moisture absorption weight at time 1)-(dry weight)} / (dry weight) x 100

(Measurement of dust adhesion amount), (Measurement of scratches) A circular polishing pad having a thickness of 1.2 mm and a diameter of 38 cm was prepared, and the surface had a width of 2.0 mm, a depth of 0.5 mm and a pitch of 15 mm. The so-called XY groove processing (grid-shaped groove processing) was applied. This pad is a polishing machine (lap master S
As a cushion layer, Suba400 manufactured by Rodel Co. was attached to a surface plate of “L / M-15E” manufactured by FT Co., Ltd., and a double-sided adhesive tape (“442J” manufactured by 3M Co., Ltd.) was attached thereon. Using a conditioner (“CMP-M”, diameter 14.2 cm) of Asahi Diamond Industrial Co., Ltd., pressing pressure 0.04 MPa, rotation speed of platen 25 rpm, rotation speed of conditioner 25 rpm, were rotated in the same direction, and 10 ml of pure water was used. The polishing pad was conditioned for 5 minutes while being supplied at a flow rate of / min. 100m pure water to the polishing machine
The polishing pad was washed for 2 minutes while flowing 1 / min, and then a wafer with an oxide film (4 inch dummy wafer CZP
Type, Shin-Etsu Chemical Co., Ltd. was installed in a polishing machine, and a slurry dispersion (“SC-
1 ") is supplied onto the polishing pad at 100 ml / min, the pressing pressure is 0.04 MPa, and the platen rotation speed is 45 r.
pm, the conditioner was rotated at 45 rpm in the same direction, and polishing was performed for 5 minutes. While keeping the surface of the wafer from being dried, the surface of the wafer was washed with a polyvinyl alcohol sponge while being immediately poured with pure water, and dried by blowing dry compressed air. After that, the number of surface dusts having a diameter of 0.5 μm or more was measured using a wafer surface dust inspection device (“WM-3” manufactured by Topcon). In the present test method, if the number is 400 or less, no problem occurs in semiconductor production and the test is passed. The number of scratches on the surface of the wafer after polishing was counted by a digital microscope (VH6300) manufactured by KEYENCE CORPORATION equipped with an automatic XY stage. Ten or less were set as the pass area.

(Uniformity) Wafer (4-inch dummy wafer CZP type, Shin-Etsu Chemical Co., Ltd.) The thickness of the oxide film on the surface was previously determined using "Lambda Ace" (VM-2000) manufactured by Dainippon Screen. 19 points given
6 points were measured. "Suba400" manufactured by Rodel, Inc. was used as a cushion layer on the surface plate of a polishing machine ("L / M-15E" manufactured by Lapmaster SFT), and double-sided adhesive tape ("442J" manufactured by 3M) was applied on it. The polishing pad to be tested was attached.
Conditioner ("CMP-M", diameter 14.2c
m), the pressing pressure was 0.04 MPa, the platen rotation speed was 25 rpm, and the conditioner rotation speed was 25 rpm, and the polishing pad was conditioned for 5 minutes while supplying pure water at 10 ml / min. Wash the polishing pad for 2 minutes while flowing pure water at 100 ml / min into the polishing machine, and then place the wafer with the oxide film whose oxide film thickness has been measured on the polishing machine, and use the Cabot Co., Ltd. of the concentration specified in the instruction manual. Slurry dispersion (“SC-1”) 10
While being supplied onto the polishing pad at 0 ml / min, the pressing pressure was 0.04 MPa, the rotation speed of the platen was 45 rpm, and the rotation speed of the conditioner was 45 rpm to rotate in the same direction to perform polishing for 5 minutes. Do not let the wafer surface dry,
Immediately while applying pure water, the surface of the wafer was washed with polyvinyl alcohol sponge and dried by blowing dry compressed air. The thickness of the oxide film on the surface of the wafer after this polishing is "Lambda Ace" (VM-200) manufactured by Dainippon Screen Co., Ltd.
0) was used to measure 196 points determined, the polishing rate at each point was calculated, and the average value was used as the oxide film polishing rate. Then, the uniformity was calculated by the following formula. Uniformity (%) = (maximum polishing rate−minimum polishing rate) / (maximum polishing rate + minimum polishing rate) × 100 Conditioning of the polishing pad every time polishing of the first wafer (first polishing) is completed. The subsequent operations were repeated to polish 20 wafers.

Example 1 Nylon woven fabric (thickness: 350 μm, official moisture content: 4.5%)
60 parts by weight and liquid phenolic resin (Sumitomo Durez,
PR-53717) is impregnated to a dry weight of 40 parts by weight, dried, four layers are piled up, and 170 ° C. for 20 minutes.
It was molded under a pressure of 5 MPa to a thickness of 1.2 mm. A polishing pad was prepared from the obtained resin plate.

Example 2 58 parts by weight of a cotton fabric (thickness: 350 μm, official moisture content: 10%) and a liquid phenol resin (manufactured by Sumitomo Durez, PR-5)
3717) to a dry weight of 42 parts by weight,
Dry and stack 4 sheets at 170 ℃ for 20 minutes 3.5MPa
It was molded under pressure to a thickness of 1.2 mm. A polishing pad was prepared from the obtained resin plate.

Example 3 Kraft paper with a thickness of 0.25 mm (official moisture content 10%)
Epoxy resin, Epicoat 180S65 (made by Yuka Shell Epoxy Co., Ltd.) / SR-GLG (made by Sakamoto Yakuhin) = 95
100 parts mixed with / 5 and curing agent Epicure EM
4 parts of I-24 (produced by Yuka Shell Epoxy Co., Ltd.) was dissolved in methyl ethyl ketone to prepare a varnish, which was then impregnated into a filter paper so that the dry resin weight ratio was 45 wt% and dried.
1.2 sheets under 1MPa pressure for 20 minutes at 170 ℃
It was molded to a thickness of mm. A polishing pad was prepared from the obtained resin plate.

Example 4 10 parts of silica particles having a particle size of 1 micron or less were further mixed with the varnish of Example 3 to form a resin plate in the same manner. A polishing pad was prepared from the obtained resin plate.

Example 5 In addition to the varnish of Example 3, polyvinylpyrrolidone (K3
No. 0, manufactured by Wako Pure Chemical Industries, Ltd.) was mixed, and a resin plate was molded in the same manner. A polishing pad was prepared from the obtained resin plate.

Example 6 70 wt% of two-component polyurethane resin KC-380 (manufactured by Nippon Polyurethane Co., Ltd.) and 30 wt% of KN-585 (manufactured by Nippon Polyurethane Co., Ltd.) were kneaded, and powdered filter paper (KC manufactured by Nippon Paper Industries Co., Ltd.) was kneaded. -Flock, 400 mesh, official moisture regain 1
1%) is kneaded and defoamed to a weight ratio of 25% by weight, cured in a mold, and after grinding, thickness 1.2 mm
A polyurethane sheet was prepared. A polishing pad was prepared from the obtained resin plate.

Example 7 A resin plate was prepared in the same manner as in Example 6 except that the powder filter paper was 28 wt%. It foamed with a little water content and formed independent pores of about 40 microns. A polishing pad was prepared from the obtained resin plate.

Comparative Example 1 Kraft paper with a thickness of 0.25 mm (official moisture content 10%)
Epoxy resin, Epicoat 180S65 (made by Yuka Shell Epoxy Co., Ltd.) / SR-GLG (made by Sakamoto Yakuhin) = 95
100 parts mixed with / 5 and curing agent Epicure EM
4 parts of I-24 (manufactured by Yuka Shell Epoxy Co., Ltd.) was dissolved in methyl ethyl ketone, impregnated into a filter paper so that the dry resin weight ratio became 35 wt%, and dried.
It was molded into a 1.2 mm thick layer at 0 ° C. for 20 minutes under a pressure of 1 MPa. A polishing pad was prepared from the obtained resin plate.

Comparative Example 2 A solution in which MMA (methyl methacrylate) / AIBN (azobisisobutyronitrile) = 999/1 was mixed was sandwiched between glass plates to carry out plate-to-plate polymerization in a 65 ° C. hot bath for 5 hours. Then, the mixture was left in a dryer at 100 ° C. for 3 hours to complete the polymerization. A 1.2 mm thick polishing pad was prepared from the obtained resin plate.

Comparative Example 3 Two-part polyurethane resin KC-362 (manufactured by Nippon Polyurethane Co., Ltd.) 51% by weight and N-4276 (manufactured by Nippon Polyurethane Co., Ltd.) 49% by weight were kneaded to form a 40 cm square mold. After putting in and defoaming in vacuum, it was molded to a thickness of 1.2 mm to prepare a polishing pad.

The results of Examples 1 to 7 and Comparative Examples 1 to 3 are shown in Table 1.

[0047]

[Table 1]

As shown in Table 1, in Examples 1 to 7, the adhesion of dust and the generation of scratches were effectively suppressed, the uniformity was stable, and the polishing pad was polished even after repeated polishing. It can be seen that the characteristics are stable. On the other hand, in Comparative Example 1 in which the water absorption rate of the polishing pad was set to exceed 15%, the adhesion of dust and the generation of scratches were suppressed, but when polishing was repeated, the uniformity changed greatly and stable polishing was achieved. Becomes difficult. Further, in Comparative Examples 2 and 3 in which the resin or the like having the official moisture content of 3% or more was not added, it was found that the uniformity was stable, but the adhesion of dust and the generation of scratches were not suppressed.

[0049]

As described above, according to the polishing pad of the present invention, the surface hardness of the polishing pad can be adjusted to the optimum range which can improve the flatness and prevent dust adhesion. The polishing characteristics can be improved, and stable polishing can be performed for a long time.

[Brief description of drawings]

FIG. 1 is a side view of a polishing apparatus using a polishing pad according to an embodiment of the present invention.

[Explanation of symbols]

1 Polishing device 2 polishing pad 3 polishing surface plate 4 drive mechanism 5 Dressing mechanism 6 Polishing slurry 7 piping 8 wafers 9 Polishing head mechanism 10 Attached plate

Claims (8)

[Claims] 1. A polishing pad used for polishing an object to be polished contains a resin and / or a filler having an official moisture content of 3% or more, and has a water absorption rate of 15% or less when immersed in water for 1 hour. A polishing pad characterized by: 2. The polishing pad according to claim 1, which contains a water-insoluble hydrophilic substance. 3. The polishing pad according to claim 1, which contains inorganic particles and / or a water-soluble substance. 4. The polishing pad according to claim 3, wherein the water-soluble substance is contained in an amount of 0.01 wt% to 10 wt% based on the weight of the polishing pad. 5. The polishing pad according to claim 1, wherein the surface has a plurality of holes. 6. A polishing apparatus using the polishing pad according to any one of claims 1 to 5. 7. A polishing method using the polishing pad according to any one of claims 1 to 5. 8. A method of manufacturing a semiconductor wafer and a semiconductor chip, which comprises using the polishing pad according to claim 1.