JP2002066907A - Polishing pad, polishing device, and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease dust adherence on a polished article surface and scratches while keeping flattening performance, and simply remove microscopic unevenness of a semiconductor wafer itself before uneven part machining namely defects represented as waviness or nanotopology. SOLUTION: This polishing pad has a thickness of not more than 1.6 mm and an absorption rate of not more than 4.0%, and made from a plate laminating paper impregnated with matrix resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a workpiece is pressed against a rotating elastic pad while supplying a polishing liquid containing processing abrasive grains and / or while supplying a polishing liquid containing no abrasive grains. A polishing pad used for chemical mechanical polishing (CMP) or the like for finishing the surface of the workpiece to a mirror surface while performing the polishing, or for preferentially polishing the convex portion of the unevenness on the surface of the workpiece with an abrasive. And 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 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).

[0003] With respect to the SOG method, this is a flattening method utilizing the fluidity of an SOG film, but it is impossible to perform perfect 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.

In recent years, fine unevenness of a semiconductor wafer itself before unevenness processing, that is, waviness
A surface defect, which has no problem in the prior art, such as s or nanotopology, has become a problem, and a double-side polishing method, a method of polishing while flowing an alkali, and the like have been performed.

[0006]

However, in such a CMP method, there are problems such as scratches, adhesion of dust, poor global flatness, etc., 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, in polishing of a non-magnetic substrate or the like for an HDD (Hard Disk Drive), a dropout of a reproduction signal such as a dropout may occur. It is considered that the occurrence of scratches is caused by agglomerates due to poor dispersion of the abrasive particles. In particular, a polishing slurry that employs alumina as polishing particles, which is used for CMP of a metal film, has poor dispersibility,
Scratch scratches have not been completely prevented. 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. Hei 8-500622 and Japanese Patent Application Laid-Open No. 2000-34416 have attempted to do so, but have not yet achieved both dust adhesion and scratch damage and flattening characteristics.

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 a flattening characteristic.

Further, fine irregularities of the semiconductor wafer itself before the irregularities are processed, that is, wafers and n
An object of the present invention is to provide a polishing pad capable of removing a defect expressed as an anatology or the like by a simple polishing method, a polishing apparatus using the polishing pad, and a polishing method.

[0010]

In order to solve the above-mentioned problems, the present invention has the following arrangement. That is, (1)
A polishing pad comprising a laminated plate of paper impregnated with a matrix resin and having a water absorption of 4.0% or less at a thickness of 1.6 mm or less.

(2) The matrix resin is a phenol resin, an epoxy resin, a polyimide resin, a urea resin, a melamine resin, a polyamide resin, a polyacryl resin, a polyolefin, an ionomer resin, a polyvinyl resin, a polycarbonate resin, a polyacetal resin, and a polyurethane resin. The polishing pad according to the above (1), wherein the polishing pad comprises at least one selected from the group consisting of:

(3) The polishing pad according to the above (1) or (2), wherein the paper is mixed with substantially no void.

(4) The polishing pad according to any one of (1) to (3), wherein the matrix resin layer further has voids.

(5) The polishing pad according to any one of the above (1) to (4), comprising inorganic fine particles.

(6) The polishing pad according to any one of the above (1) to (5), further comprising a water-soluble substance.

(7) From 0.01 wt% of water-soluble substance to 1
The polishing pad according to (6), wherein the polishing pad contains 0 wt%.

(8) A polishing apparatus using the polishing pad according to any one of (1) to (7).

(9) A polishing method using the polishing pad according to any one of (1) to (7).

(10) A method for manufacturing a semiconductor wafer or a semiconductor chip, wherein the method is performed by using the polishing pad according to any one of the above (1) to (7).

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

According to the present invention, by laminating the paper impregnated with the matrix resin, the polishing pad itself can be hardened without causing the adhesion of dust and scratches, which were conventionally in a trade-off relationship, and the flexural modulus can be reduced. Since the size of the polishing pad can be dramatically increased as compared with a polishing pad made of a conventional technique, extremely excellent flattening characteristics can be realized. The polishing pad of the present invention has been intensively studied in order to impart a higher polishing rate and flattening characteristics. As a result, the polishing pad of the present invention can satisfy the requirement that the water absorption is 4.0% or less at a thickness of 1.6 mm or less. It was found that the improvement of the polishing rate and the improvement of the flattening characteristics, which could not be realized, can also be realized.

Although the detailed mechanism is unknown, laminating paper improves the wettability of the polishing pad surface and reduces dust adhesion to the surface of the object to be polished. with this,
We believe that scratches can be reduced. If the water absorption is too small, the effect is small, and the water absorption is desirably 0.5% or more. However, if the water absorption is too high, the wettability on the polishing pad surface will improve too much, forming an excessively thick hydrophilic layer, which will impair the mechanical polishing properties, reduce the polishing rate and flatten We believe that the characteristics also tended to plateau. Here, the water absorption refers to a weight increase rate obtained by the following (Equation 1) after immersing in 50 ° C. water for 24 hours and further immersing in 23 ° C. water for 24 hours. A 5 cm square one was used for the measurement.

As the paper to be used, it is convenient to use cellulose naturally produced by plants such as cotton, wood, hemp and flax. Various kinds of paper such as linter paper, kraft paper, bleached paper are manufactured and sold, and from these, the bulk density and thickness can be changed to improve the affinity with the matrix resin. . Also 400pp
It is preferable to use a material in which mixing of sodium ions is suppressed to m or less. More preferably, it is 50 ppm or less, more preferably 10 ppm or less.

"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 hydrophilicity, a test piece taken out of water after immersion in water for 24 hours was placed in a sealed container, and 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 is determined according to the following equation 1.

Weight increase rate (%) = {(moisture absorption weight−dry weight) / dry weight} × 100 (Equation 1) Here, the hydrophilicity means the weight increase rate when immersed in 50 ° C. water for 24 hours. Refers to characteristics of 2.0% or more.

The mixing amount of the paper is preferably at least 3% by weight. If the amount is less than 3% by weight, the effect cannot be sufficiently exhibited, but if it is more than 3% by weight, 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 decreases, the bending strength is weak, and the pad is easily brittle. For this reason, 5 to 60% by weight is preferably used, and 20 to 55% by weight is more preferably used. Although it depends on the specific gravity of the resin used as the organic polymer matrix, this compounding ratio can be appropriately adjusted. In the present invention,
The matrix resin is also impregnated in the paper, and it can be confirmed by optical microscope observation that there is substantially no void. For this reason, variation in polishing characteristics hardly occurs. This gap is 5
This is based on observation with an optical microscope of 0 magnification. When there is a void, the paper surface has a color unique to the paper, and no coloring derived from the matrix resin is observed.

The paper may be not only a non-woven fabric but also at least one of a woven fabric and a knitted fabric.
The nonwoven fabric refers to a papermaking in which fibers are entangled, but may be distorted or have irregularities. Non-woven fabrics, woven fabrics and knitted ones can also be obtained from fibrous materials. What is fibrous material?
It refers to a long and thin shape in which the ratio of the major axis to the minor axis exceeds 10. The porous film or sponge shape means a film in a broad sense that has a large porosity and is two-dimensionally and / or three-dimensionally opened.

The organic polymer matrix, which is a resin constituting the polishing pad, includes thermoplastic resins such as polyamide, polyacryl, polyolefin, polyvinyl, ionomer, polycarbonate, polyacetal, polyurethane and polyimide. Resins and derivatives thereof, copolymers, grafts, and 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 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.

The particle size is from about 3 nm to 50 μm.
m can be used, but if it is too large, the risk of scratching increases. For this reason, more preferably, 20
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 matrix resins 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. That is, specifically, as 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 the particle diameter when using a thermosetting resin, a particle diameter of about 3 nm to about 50 μm can be used.
If it is too large, the risk of scratching increases. For this reason, it is more preferably 20 μm or less, more preferably 5 μm or less.
Those having a size of μm or less are preferred. 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, the effect is small when the particle diameter is small, and the particle diameter is preferably 30 nm or more,
It is 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.

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 70 or more, and more preferably 80 or more. In the present invention, even if the D hardness exceeds 90, the problem of scratches and dust adhesion does not occur,
Available. For this reason, it is possible to exhibit good polishing and flattening characteristics which could not be obtained conventionally.

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 paper, that is, a hydrophilic polymer is contained, these are used after being dried, but it is difficult to completely remove water, and steam is generated by heating during molding. Therefore, voids can be formed in portions other than the paper. In addition, in the case of thermosetting resins, some of them generate water during curing, such as phenolic resins, so use this to form more voids in parts other than paper, that is, in the matrix resin layer. Can be. In order to control the size of the voids, for example, these water vapors can be successfully removed at the time of molding and cured. However, when finer control is required, it is possible by mixing a small amount of a water-soluble substance.
Furthermore, when these water-soluble substances dissolve during polishing, voids can be formed only on the polishing pad surface. The voids in the matrix resin layer are effective in increasing the retention of free abrasive grains in the polishing slurry and in removing polishing debris, and as a result, are advantageous in improving 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. It has a Bingham fluid-like property, and it is possible to obtain an effect of improving flatness when polishing, particularly global flatness, because the diffusion of abrasive particles is suppressed in the concave portions of the semiconductor wafer with unevenness.

In order to exhibit these effects, a water-soluble substance is added in an amount of 0.01 wt% to 10 wt% per weight of the polishing pad.
% Is preferably added. 0.01wt of water-soluble substance
% Is effective, but preferably 0.5%
An addition amount of not less than wt% and not more than 5 wt% is effectively used. 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.

As a method for forming a polishing pad, paper may be pre-compounded with an organic polymer matrix and, if necessary, inorganic fine particles and / or a water-soluble substance, impregnated with the paper, dried and then hot-pressed.
In this case, it is also possible to impregnate after adjusting the viscosity by using a solvent, and to perform hot compression molding after drying. After using a sheet-like material, the matrix resin alone is impregnated under pressure, and inorganic fine particles are uniformly dispersed thereon, and / or a layer formed by uniformly winding a water-soluble substance, and then laminated. Heat compression molding can be performed. Variations in the physical properties of the resulting polishing pad can be reduced by increasing the number of layers.

Further, a matrix monomer molecule on paper,
In some cases, it is also possible to carry out polymerization after impregnation with a mixture of inorganic fine particles and / or a water-soluble substance.
In the case of a two-liquid type matrix such as polyurethane, a base material or a curing agent is mixed in advance, and then the paper can be impregnated with pressure and molded. Thereafter, it is also possible to perform a grinding process to finish the shape of the polishing pad. Specifically, it depends on physical properties such as compatibility of each matrix and paper, individual heat resistance, polymerization characteristics, melt viscosity and the like, but it is easy for those skilled in the art to select the combination. As for the polishing pad of the present invention, a combination of known techniques can be used for the manufacturing method.

As described above, the bending elastic modulus of the polishing pad can be made larger than that of the conventional polishing pad. 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 scratches, a larger value of 5 GPa or more is more preferable. However, if it is too large, it becomes difficult to mount the polishing pad.

It is preferable that grooves or 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 ensure that the polishing liquid is successfully supplied to the polishing surface, to enhance the retention of the polishing liquid, and to satisfactorily discharge and / or promote polishing chips therefrom. . 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. By increasing the number of repetitions of the laminated structure, a long-life polishing pad can be manufactured. As for the diameter when processed into a disk shape or a donut shape, the diameter is manufactured from 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 is reduced. Therefore, it is not preferable.

The polishing pad obtained in the present invention can be used as a composite polishing pad by laminating 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 urethane foam-based or rubber-based one can be used in combination. Of course, it is not necessary to use it. In addition, it is preferable to use a polishing pad of the present invention in which the mixing of sodium ions is suppressed to 400 ppm or less. More preferably 50
ppm or less, more preferably 10 ppm or less.

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. Has fine irregularities, ie, waviness and nanotop
It is preferable to eliminate surface defects expressed as “ology” or the like. Thereafter, a surface pattern is processed by lithography or the like, and CMP polishing is performed. By applying the present invention to one of these, a wafer with extremely high flatness can be processed. By performing both of these steps using the polishing apparatus according to the present invention, processing with even higher flatness can be performed. Therefore, it is possible to easily satisfy the demands for multilayered semiconductor chips, higher integration, and finer wiring.

The polishing pad of the present invention has a polishing pad content of 400 ppm.
In the following, it is preferable to use one in which mixing of sodium ions is suppressed. More preferably, it is 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 flattening characteristics, and the dishing were performed as follows.

(Measurement of Flexural Elastic Modulus) A rectangular test piece having a thickness of 1.0 mm to 1.5 mm and a size of 1 × 8.5 cm was prepared from a polishing pad. For this test piece, the ORI
ENTEC's material testing machine (Tensilon RTM-10
The flexural modulus was measured in accordance with JIS-7203 using (0). The flexural modulus was determined according to the following equation.

Bending elastic modulus = ｛(distance between supporting points)^Three × (Load
The load at an arbitrarily chosen point on the first straight part of the deflection curve
(Kgf))｝ / ｛4 × (width of test piece) × (thickness of test piece)
Sa) ^Three X Deflection under load F (Measurement of D hardness) Thickness in the range of 1.0 mm to 1.5 mm
Enter a sample (size of 1 cm square or more) with a D hardness of 90.
Place it on a flat surface having the above surface hardness, and
Test) Durometer tie based on K6253
D (actually, manufactured by Kobunshi Keiki Co., Ltd. “Asker D-type hard
And measure the average at 5 points using D
Was. The measurement was performed at room temperature (25 ° C.).

(Measurement of Dust Adhesion Amount) Thickness: 1.2 mm
A circular polishing pad having a diameter of 38 cm was prepared, and the surface was subjected to 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 pad is polished with a polishing machine (Lap Master SFT, "L / M-
15E ″) as a cushion layer, a Suba400 manufactured by Rodale, and a double-sided adhesive tape (3M
"442J"). Conditioner (“CMP-M”, diameter 1) of Asahi Diamond Industry Co., Ltd.
4.2cm), pressing pressure 0.04MPa, platen rotation speed 25rpm, conditioner rotation speed 25rpm
m, 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 pure water at 100 ml / min through the polishing machine, and then the 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 liquid (“SC-1”) manufactured by Cabot Corporation with a concentration described in the instruction manual was 100 ml / min.
Pressing pressure 0.04 while supplying on the polishing pad with
Polishing was carried out for 5 minutes by rotating in the same direction at a rotation speed of 45 rpm and a platen rotation speed of 45 rpm. 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. After that, wafer surface dust inspection equipment (Topcon Co., Ltd., "WM-
3 ″) was used to measure the number of surface dusts having a diameter of 0.5 μm or more. In this test method, if the number was 400 or less, it passed without causing any problem in semiconductor production. The number of scratches on the surface was counted using a digital microscope (VH6300, manufactured by KEYENCE CORPORATION) equipped with an automatic XY stage.

(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. 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 a mask exposure using a photoresist, and apply 20 μm into a 10 mm square die by RIE.
A line with a width of 0.7 μm and a height of 0.7 μm and a space of 230 μm are arranged on the left half in a line-and-space manner.
A line having a width and a height of 0.7 μm is arranged in a line and space on the right half in a space of 20 μ. A circular polishing layer having a diameter of 38 cm was prepared, and the surface was 2.0 mm wide and 0.1 mm deep.
A so-called XY groove processing (grid-like groove processing) of 5 mm and a pitch of 15 mm was performed. This polishing pad is used as a cushion layer on a surface plate of a polishing machine (Lap Master SFT, L / M-15E) as "Suba40" manufactured by Rodale.
0 ”, and a double-sided adhesive tape (3M,“ 4
42J "). Conditioner (" CMP-M ", diameter 14.2c, manufactured by Asahi Diamond Industry Co., Ltd.)
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 on the polishing pad for 2 minutes while flowing 100 ml / min of pure water through the polishing machine. Then, a test wafer for evaluating a global level difference was set on the polishing machine, and a slurry (“SC-1” manufactured by Cabot Corporation) having the concentration described in the instruction manual was used. )) On the polishing pad at a rate of 100 ml / min while applying a pressing pressure of 0.04M.
Pa, the platen rotation speed was 45 rpm (linear velocity at the center of the wafer was 3000 (cm / min)), and the semiconductor wafer holding sample table was rotated in the same direction at a rotation speed of 45 rpm to perform polishing 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. Test wafer center 1 for global step evaluation
The thickness of the oxide film of the 20 μm line and the 230 μ line in the 0 mm die was determined by using Lambda Ace (“VM-
2000 "), and the difference between the thicknesses was evaluated as a global step. Regarding the processing form of the polishing layer, those having other shapes were also subjected to the same procedure as described above.
The global step between the 20 μm-wide wiring region and the 230 μm-wide wiring region was judged to be acceptable if the polishing time was 5 minutes and 45 nm or less.

(Evaluation of dishing) Tungsten wiring dishing test wafer: 100 μm on 4-inch silicon wafer with oxide film (oxide film thickness: 2 μm)
Grooves having a width and a depth of 0.7 μm are formed at intervals of 100 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 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. ). Using a conditioner (“CMP-M”, diameter 14.2 cm) of Asahi Diamond Industrial Co., Ltd., rotate 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 pure water of 10 ml. The polishing pad was conditioned for 5 minutes while supplying at a rate of / min. 100 pure water in polishing machine
The polishing pad was washed for 2 minutes while flowing at a flow rate of ml / min. Then, a test wafer for evaluating tungsten wiring dishing was set on a polishing machine, and a slurry manufactured by Cabot Corporation (“SEMI-SPERSE W-A40”) having a concentration described in the instruction manual was used.
0 ”) and an oxidizing agent manufactured by Cabot (“ SEMI-SPER
SEFE-400 ") at a pressure of 0.04 MPa and a platen rotation speed of 45 rpm while supplying a slurry solution mixed at 1: 1 onto the polishing pad at 100 ml / min.
m (linear velocity at the center of the wafer is 3000 (cm /
Min)), the semiconductor wafer holding sample stage was rotated in the same direction at a rotation speed of 45 rpm, and polishing was performed for 2 minutes. 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 was measured with an ultra-depth shape measuring microscope “VK-8500” manufactured by Keyence Corporation. In addition, about the surface processing form of a polishing layer, the thing of another shape was performed in the same procedure as the above. The center depth of the tungsten wiring was measured.

Hereinafter, the present invention will be described in more detail with reference to examples.

[0049]

The evaluation results obtained in Examples and Comparative Examples are shown in Table 1.

Example 1 On linter paper having a thickness of 0.2 mm (official moisture content: 11%),
A liquid phenolic resin (PR-55123, manufactured by Sumitomo Durez) was impregnated and dried at a dry weight ratio of 60 wt%, and dried at 170 ° C. for 20 minutes at 3.5 MPa at 6 layers.
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 linter paper.

Example 2 A 0.2 mm thick kraft paper (official moisture content: 11%)
A liquid phenolic resin (PR-53717, manufactured by Sumitomo Durez) was impregnated and dried at a dry weight ratio of 60 wt%, and six of these were superposed at 170 ° C. for 20 minutes at 3.5 MPa.
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 kraft paper.

Example 3 On linter paper having a thickness of 0.2 mm (official moisture content: 11%),
A liquid phenolic resin (PR-55123, manufactured by Sumitomo Durez) was impregnated and dried so as to have a dry weight ratio of 55 wt%.
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 linter paper.

Example 4 Kraft paper having a thickness of 0.2 mm (official moisture content: 11%)
A liquid phenol resin (manufactured by Sumitomo Durez, PR-53717) is impregnated and dried so as to have a dry weight ratio of 52 wt%, and six of them are superimposed on each other and are 170 ° C. 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 kraft paper.

Example 5 Kraft paper having a thickness of 0.24 mm (official moisture content: 11%)
"Art Farmer" (TA, manufactured by Sanyo Chemical Industries, Ltd.)
-1327) is impregnated at 60 parts with a predetermined mixing ratio, and five of these are superimposed, placed in a 40 cm square mold, degassed at 100 ° C, heated at 165 ° C, and heated at 165 ° C. Was formed. 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 kraft paper.

Example 6 A solution obtained by mixing MMA (methyl methacrylate) / AIBN (azobisisobutyronitrile) = 999/1 with six 0.2 mm-thick kraft paper (official moisture content: 11%) was used for 60 times. And the mixture was sandwiched between glass plates and polymerized between plates in a 65 ° C. warm bath for 5 hours. Thereafter, the mixture was left in a dryer at 100 ° C. for 3 hours to complete the polymerization. A 1.2 mm 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 kraft paper.

Example 7 3.1 mol of formalin (37%) per mol of melamine
Aqueous solution) and reacted at 75 ° C. under alkaline conditions. This solution is impregnated into 0.2 mm thick kraft paper (official moisture content: 11%) so that the resin becomes 60 wt% in dry weight ratio.
It was molded to a thickness of 1.2 mm under a pressure of MPa. 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 kraft paper.

Example 8 1.5 mol of formalin (37% aqueous solution) was added to 1 mol of urea and reacted at 80 ° C. at pH 5.3. This solution was applied to a 0.2 mm thick kraft paper (official moisture content 11
%), The resin was impregnated so as to have a dry weight ratio of 60 wt%, and after drying, six sheets were laminated and molded to a thickness of 1.2 mm under a pressure of 5 MPa at 160 ° C. for 20 minutes. 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 kraft paper.

Example 9 In Example 1, the pressure was released during the molding of the resin plate, and a void was formed in the phenol resin. A polishing pad was formed from the obtained resin plate.

Example 10 A polishing pad was prepared in the same manner as in Example 1 except that a liquid phenol resin (PR-55123, manufactured by Sumitomo Durez) mixed with 3% by weight of silica particles having a pore size of 1 μm was used as a matrix resin. When the cross section was observed with an optical microscope, no void was found in the kraft paper.

Example 11 A polishing pad was prepared by mixing 15% by weight of silica particles having a pore diameter of 1 μm with the matrix resin in Example 5. When the cross section was observed with an optical microscope, no void was found in the kraft paper.

Example 12 In Example 10, 0.8% by weight of partially saponified polyvinyl alcohol was added as a hydrophilic water-soluble resin to the matrix resin, and a polishing pad was prepared using this resin. When the cross section was observed with an optical microscope, no void was found in the kraft paper.

Example 13 In Example 11, 8% by weight of partially saponified polyvinyl alcohol was added as a hydrophilic water-soluble resin to the matrix resin, and a polishing pad was prepared using this resin. When the cross section was observed with an optical microscope, no void was found in the kraft paper.

Example 14 In Example 10, the pressure relief at the time of molding the resin plate was adjusted.
Voids were formed in the phenolic resin. A polishing pad was formed from the obtained resin plate.

Example 15 In Example 11, the pressure relief at the time of molding the resin plate was adjusted.
Voids were formed in both kraft paper and phenolic resin.
A polishing pad was formed from the obtained resin plate.

Comparative Example 1 A liquid phenol resin (PR-55123, manufactured by Sumitomo Durez) was impregnated with 0.2 mm thick kraft paper (official moisture content: 11%) so that the weight ratio became 50% by weight, and dried. The six sheets were combined and molded at a temperature of 170 ° C. for 20 minutes under a pressure of 3.5 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 kraft paper.

COMPARATIVE EXAMPLE 2 An "Art Farmer" was prepared so that the kraft paper having a thickness of 0.2 mm (official moisture content: 11%) was 50% by weight.
(TA-1327, manufactured by Sanyo Kasei Kogyo Co., Ltd.) was impregnated with a mixture obtained at a predetermined mixing ratio, and the six sheets were combined and molded at 170 ° C. for 20 minutes under a pressure of 3.5 MPa to form a 1.2 mm thick sheet. 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 kraft paper.

Example 16 A solution obtained by mixing MMA (methyl methacrylate) / AIBN (azobisisobutyronitrile) = 999/1 on 6 pieces of 0.2 mm thick kraft paper (official moisture content: 11%) was used. And the mixture was sandwiched between glass plates and polymerized between plates in a 65 ° C. warm bath for 5 hours. Thereafter, the mixture was left in a dryer at 100 ° C. for 3 hours to complete the polymerization. A 1.2 mm 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 kraft paper.

[0068]

[Table 1]

[0069]

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

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Claims (10)

[Claims] 1. A polishing pad comprising a laminate of papers impregnated with a matrix resin and having a water absorption of 4.0% or less at a thickness of 1.6 mm or less. 2. A matrix resin comprising a phenol resin, an epoxy resin, a polyimide resin, a urea resin, a melamine resin, a polyamide resin, a polyacryl resin, a polyolefin, an ionomer resin, a polyvinyl resin, a polycarbonate resin, a polyacetal resin, and a polyurethane resin. 2. The polishing pad according to claim 1, wherein the polishing pad comprises at least one selected from the group consisting of: 3. The polishing pad according to claim 1, wherein the paper is mixed with substantially no voids. 4. The polishing pad according to claim 1, further comprising a void in the matrix resin layer. 5. The polishing pad according to claim 1, further comprising inorganic fine particles. 6. The polishing pad according to claim 1, further comprising a water-soluble substance. 7. The water-soluble substance is contained in an amount of 0.01 wt% to 10 wt%.
The polishing pad according to claim 6, wherein the polishing pad contains%. 8. A polishing apparatus using the polishing pad according to any one of claims 1 to 7. 9. A polishing method using the polishing pad according to any one of claims 1 to 7. 10. A method of manufacturing a semiconductor wafer or a semiconductor chip, wherein the method is performed by using the polishing pad according to claim 1.