JP2001179608A - Polishing pad, and polishing device and polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deposit less dust on the surface of a polished material. SOLUTION: A polishing pad comprises a volume swelling percentage of 2.0% or more and a D-hardness of 60 or more. This polishing device and polishing method is characterized by using the above polishing pad.

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. Chemical-mechanical polishing (CM) that preferentially grinds the convex part of the irregularities on the surface of the workpiece
The present invention relates to a polishing pad used in P), 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)) 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 used cannot be lifted off because it 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.

[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, if such dust adheres or scratches occur on the surface to be polished such as an interlayer insulating film, when a wiring made of an Al-based metal or the like is formed thereon in a later step, a step breakage or the like occurs, resulting in electromigration. There is a possibility that a decrease in reliability such as deterioration of resistance may occur. Also HD
When polishing a non-magnetic substrate for D (Hard Disk Drive) or the like, a dropout or the like may cause a loss of a reproduced signal.
It is considered that the occurrence of scratches is caused by agglomerates due to poor dispersion of the abrasive particles. In particular, C of the metal film
Polishing slurries used for MP and employing alumina as the polishing particles have poor dispersibility and have not yet completely prevented scratches. 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.

[0004] It is an object of the present invention to reduce dust adhesion to the surface of an object to be polished, among the above-mentioned problems.

[0005]

In order to solve the above-mentioned problems, the present invention has the following arrangement. 1. Volume swelling ratio is 2.
A polishing pad characterized by being at least 0%. The polishing pad according to claim 1, wherein the D hardness is 60 or more. A polishing apparatus and a polishing method using the polishing pad.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The high volume swelling ratio
Dust adhesion is suppressed. The volume expansion coefficient represents a change in volume when immersed in water, and is as described in detail in (Measurement of volume expansion coefficient). This value is 2.0%
If lower, the wettability of the polishing pad surface will be poor,
Although the detailed mechanism is unknown, dust adheres to the surface of the workpiece. 2.0% or more is preferred, and 5.0%
The degree is more preferred. 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, and usually 10%
The following is preferred.

In order to set the volume swelling ratio in this range, for example, the following method can be used, but it is not limited to this method.

[0008] The resin constituting the polishing pad (hereinafter referred to as a matrix) includes thermoplastic resins such as polyamide, polyacryl, polyolefin, polyvinyl, ionomer, polycarbonate, and polyacetal, polyurethane, and epoxy. And a phenol-based thermosetting resin can be used. 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.

In the polishing pad of the present invention, a hydrophilic polymer is used if necessary. As the hydrophilic polymer, for example, a cellulose-based, acrylic-based, aramid-based, polyamide-based, or starch-based resin, or a crosslinked product or copolymer containing the resin as a main component can be used. Commercially available products include water-soluble polymers such as various polyalkylene glycols, polyvinyl vinylidone, polyvinyl alcohol, and polyvinyl acetate, and water-insoluble chitosan, polyvinyl polyvinylidone, and polyvinyl polyvinyl. There are a lidone / vinyl imidazole copolymer, a superabsorbent resin, pulp, paper, and various charged celluloses for cellulose ester ion exchange, and these can be used. It is also possible to modify the surface in advance to improve the compatibility with the matrix.

The shape of the hydrophilic polymer is preferably in the form of particles, a nonwoven fabric or a woven fabric because it is easy to handle. The diameter of the particles is preferably 500 μm or less, and more preferably 100 μm or less. If the diameter is large, separation from the matrix increases, which is not preferable. When the fibers forming the nonwoven fabric or the woven fabric are in the form of a hollow fiber, it is difficult to control the invasion of the matrix into the hollow portion, but the fiber may be in the form of a hollow fiber.

The proportion of the aggregate of the domain structure occupying the polishing pad surface, that is, the surface density varies depending on the matrix. A small amount may be used for a polyamide resin or a polyurethane resin having a high water absorption rate. In the case of polyacrylic resin such as methacrylate, polyimide, etc., it is necessary to set a higher value. Generally, 5% to 5%
Although 0% is a region that is preferably used, 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.

As a method for forming a polishing pad, a matrix and a hydrophilic and water-insoluble polymer can be compounded in advance and then subjected to hot compression molding or melt extrusion molding. A method such as an injection press is also possible. It is also possible to polymerize after impregnating the monomer molecules of the matrix with a hydrophilic and water-insoluble polymer. In the case of a two-liquid matrix such as polyurethane, a hydrophilic and water-insoluble polymer is mixed in advance with a main agent or a curing agent, then the curing agent or the main agent is mixed, and after defoaming operation, poured into an appropriate mold. It can be formed, and then it is also possible to perform a grinding process to finish the shape of the 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 volume swelling ratio can be increased to 2.0% or more by mixing the hydrophilic polymer at a mixing ratio of 1 to 70% by weight based on the weight of the polishing pad, but the effect is small and large when the mixing ratio is small. And its effect is increased, but the physical properties of the matrix often deteriorate. That is, the hardness of the matrix decreases, the bending strength is weak, and the matrix is easily broken. For this reason, 10 to 60% by weight is preferably used, and 20 to 50% by weight is more preferably used.

The D hardness of the polishing pad of the present invention is 60.
The above is preferred. If it is less than 60, it becomes too soft and dishing and erosion are likely to occur. 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, the problem of scratches and dust adhesion hardly occurs, so that it can be used. Grooves or holes are preferably provided on the surface for the purpose of promoting supply to and removal from the polished surface. As the shape of the groove,
Various shapes such as concentric circles, spirals, radiation, and grids 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 depth of the groove ranges from 0.1 mm to the thickness of the polishing layer, the width of the groove ranges from 0.1 to 5 mm,
The pitch of the grooves can be selected in the range of 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.

The volume swelling ratio, D hardness, dust adhesion amount, and oxide film polishing rate were evaluated as follows. (Measurement of Volume Swelling Ratio) A circular polishing pad having a thickness of 1.0 mm to 1.5 mm and a diameter of 38 cm was prepared. (Surface groove processing and dimple processing are optional and may be omitted. For example, width 2.0 mm, depth 0.5 mm, pitch 1
5mm so-called XY groove processing) This pad is polished with a polishing machine (L / M-15E, manufactured by Lapmaster SFT).
"Suba" manufactured by Rodale Co., Ltd.
400 "and a double-sided adhesive tape (3M,
"442J"). Here, another double-sided adhesive tape may be used. Using a conditioner (“CMP-M”, diameter 14.2 cm) of Asahi Diamond Industrial Co., Ltd., pressing pressure 0.04 MPa, platen rotation speed 25 r
The polishing pad was rotated in the same direction at 25 rpm with 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 to form a dressing surface on one side. Thickness 0.
A test piece within a range of 7 mm to 1.5 mm was cut out (5.
(cm × 8 cm) After peeling off the double-sided tape, the sample was dried for 24 hours using a 50 ° C. drier to obtain a sample. An electronic hydrometer (Mirage Trading, SD-120)
L ″) was used to measure the volume (dry volume) at room temperature of 28 ° C. (measurement was performed according to the instruction manual for the device). Then, each sample was transferred into water and dried at 50 ° C. for 20 hours. The samples were incubated at room temperature (28
° C), each sample was centrifuged at 1000 G and dehydrated for 5 seconds, and an electronic hydrometer (made by Mirage Trading,
The volume (swelling volume) was measured at room temperature 28 ° C. using “SD-120L”), the rate of change was determined according to the following equation, and the average value was taken as the volume swelling rate of the sample.

Volume swelling ratio = (swelling volume / dry volume) × 100-100 (Measurement of D hardness) A sample (having a size of 1 cm square or more) having a thickness in the range of 1.0 mm to 1.5 mm was subjected to D hardness. 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 1.2 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 set on a polishing machine, and a slurry dispersion liquid (“SC-1”) manufactured by Cabot Co., Ltd. with the concentration described in the instruction manual was 100 ml / min.
Pressing pressure 0.04 while supplying on the polishing pad with
Polishing was performed for 5 minutes by rotating in the same direction at a rotational speed of 45 rpm for the platen and a rotational speed of 45 rpm for the conditioner. 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.

(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 using "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 a rate of 00 ml / min, the plate was pressed and rotated in the same direction at a desired pressure, platen rotation speed and conditioner rotation speed, and polished for 5 minutes. Do not dry the wafer surface.
Clean the wafer surface with a polyvinyl alcohol sponge,
Dry compressed air was blown to dry. The point 19 in which the thickness of the oxide film on the wafer surface after polishing was determined using "Lambda Ace" (VM-2000) manufactured by Dainippon Screen Co., Ltd.
Six points were measured, the polishing rate at each point was calculated, and the average value was taken as the oxide film polishing rate. Hereinafter, the present invention will be described in more detail with reference to examples.

[0019]

EXAMPLES Example 1 25 parts of polyvinylpyrrolidone (molecular weight 10,000), M
75 parts of MA (methyl methacrylate) / AIBN (azoisobutyronitrile) = 999/1 are mixed and polymerized between plates, and the obtained resin plate is used for volume swelling ratio, D hardness, dust adhesion amount, oxide film polishing. Speed measurements were taken. As a result, a volume swelling ratio of 5.23% and 313 dust particles were observed. Also D
The hardness was 89 degrees. Oxide film polishing rate is 179nm
/ Min. It was possible to reduce dust adhesion to the surface of the object to be polished.

Example 2 Filter paper powder (E type) manufactured by Advantech Co., Ltd. was uniaxially kneaded and compounded at 165 ° C. with “Surlyn” (1705, manufactured by Du Pont-Mitsui Polychemicals Co., Ltd.) to a concentration of 35% by weight. Using the pellets cut to a length of 3 mm, hot press molding was performed at 185 ° C. using a 40 cm square mold.
Volume swelling ratio, D hardness, dust adhesion amount,
The oxide film polishing rate was measured. As a result, a volume swelling ratio of 2.23% and 254 dust particles were observed. The Shore D hardness was 63 degrees. Oxide film polishing rate is 32nm
/ Min, the dust adhesion to the surface of the object to be polished could be reduced.

Comparative Example 1 "Axter" of 40 cm square (a non-woven fabric made of polyethylene terephthalate fiber, manufactured by Toray Co., Ltd., weight: 280 g / m ² )
Liquid phenolic resin (Sumitomo Durez, PR-531)
23) was impregnated and dried at a dry weight ratio of 50 wt%, and dried at 170 ° C. for 20 minutes under a pressure of 3.5 MPa to form a 1.2 m
m thickness. The volume swelling ratio, D hardness, dust adhesion amount, and oxide film polishing rate were measured on the obtained resin plate. As a result, a volume swelling ratio of 1.23% and 3,234 dust particles were observed. The Shore D hardness was 90 degrees. The oxide film polishing rate was 111 nm / min. Dust adhesion to the surface of the object to be polished could not be reduced.

Example 3 Two 17 chr filter papers manufactured by Whatman Co. were stacked, and a solution prepared by mixing 20 parts of polyvinylpyrrolidone (molecular weight 10,000) and 80 parts of MMA (methyl methacrylate) / AIBN (azoisobutyronitrile) = 999/1 was used. , And sandwiched between glass plates, and polymerized between plates in a 65 ° C. warm bath for 5 hours. Thereafter, the mixture was allowed to stand in a dryer at 100 ° C. for 3 hours to complete the polymerization. The volume swelling ratio, D hardness, dust adhesion amount, and oxide film polishing rate were measured on the obtained resin plate. As a result, the volume swelling ratio was 3.23%, the D hardness was 83 degrees, and 151 dust particles were recognized. The oxide film polishing rate was 132 nm / min. It was possible to reduce dust adhesion to the surface of the object to be polished.

Example 4 Nylon 6 pellets were injection molded at 200 ° C.
A resin plate having a thickness of mm was formed. The volume swelling ratio, D hardness, dust adhesion amount, and oxide film polishing rate were measured on the obtained resin plate. As a result, the volume swelling ratio was 7.53% and the D hardness was 7
Three times, 389 dusts were observed. The oxide film polishing rate was 85 nm / min. It was possible to reduce dust adhesion to the surface of the object to be polished.

Comparative Example 2 In Example 2, hot press molding was carried out at 185 ° C. using a “40 cm square” mold using “Surlyn” pellets without using filter paper powder. The volume swelling ratio, D hardness, dust adhesion amount, and oxide film polishing rate were measured on the obtained resin plate. As a result, a volume swelling ratio of 1.58% and 3,443 dust particles were observed. The D hardness was 64 degrees. The oxide film polishing rate was 35 nm / min. Dust adhesion to the surface of the object to be polished could not be reduced.

Example 4 Two 17 chr filter papers made by Whatman Co. were piled up, impregnated with a liquid phenol resin (PR-53123, manufactured by Sumitomo Durez) to a dry weight ratio of 50 wt%, and dried.
It was molded to a thickness of 1.8 mm under a pressure of 3.5 MPa at 0 ° C. for 20 minutes. The obtained resin plate was processed into an XY groove groove having a thickness of 1.2 mm, and the volume swelling ratio, D hardness, dust adhesion amount, and oxide film polishing rate were measured on the obtained resin plate. As a result,
Volumetric swelling rate 6.13%, 287 dust adhered,
The D hardness was 88 degrees. Oxide film polishing rate is 62nm
/ Min, the dust adhesion to the surface of the object to be polished could be reduced.

[0026]

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

Claims (4)

[Claims] 1. A polishing pad having a volume swelling ratio of 2.0% or more. 2. The polishing pad according to claim 1, wherein the D hardness is 60 or more. 3. A polishing apparatus using the polishing pad according to claim 1. 4. A polishing method using the polishing pad according to claim 1.