JP4686912B2 - Polishing pad - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing pad, and further relates to a polishing pad used in a step of mechanically flattening the surface of an insulating layer such as silicon formed on a semiconductor substrate or the surface of a metal wiring.
[0002]
[Prior art]
Large scale integrated circuits (LSIs) typified by semiconductor memories have been integrated year by year, and accordingly, the manufacturing technology of large scale integrated circuits has also been increased in density. Furthermore, with this increase in density, the number of stacked semiconductor device manufacturing locations has also increased. Due to the increase in the number of stacked layers, unevenness of the main surface of the semiconductor wafer caused by stacking that has not been a problem in the past has become a problem. As a result, for example, as described in pages 50 to 57 of the Nikkei Microdevice, July 1994, for the purpose of making up for insufficient depth of focus at the time of exposure due to unevenness caused by stacking, or wiring by flattening the through hole portion In order to improve the density, planarization of a semiconductor wafer using a chemical mechanical polishing technique has been studied.
[0003]
In general, a chemical mechanical polishing apparatus includes a polishing head that holds a semiconductor wafer that is an object to be processed, a polishing pad that performs polishing of the object to be processed, and a polishing surface plate that holds the polishing pad. Then, the polishing process of the semiconductor wafer uses a slurry made of an abrasive and a chemical solution to move the semiconductor wafer and the polishing pad relative to each other, thereby removing the protruding portion of the layer on the surface of the semiconductor wafer and smoothing the layer on the wafer surface. It is to make. It is approximately proportional to the relative speed and load between the semiconductor wafer and the polishing pad. Therefore, in order to polish each part of the semiconductor wafer uniformly, it is necessary to make the load applied to the semiconductor wafer uniform.
[0004]
When polishing an insulating layer or the like formed on the main surface of a semiconductor wafer, if the polishing pad is soft, local flatness is deteriorated. For this reason, polyurethane foam sheets having a Shore A hardness of 90 degrees or more are currently used. However, the high hardness polyurethane foam pad has a problem in that the level of flatness is different at portions where the unevenness density of the insulating layer or the like is different, and a global level difference is generated. There is a problem that the height of the portion is lower than that of the edge) and a problem that there are many dusts and scratches.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to provide a polishing pad for mechanically flattening the surface of an insulating layer or metal wiring formed on a silicon substrate. The object is to provide a polishing pad with less scratches.
[0006]
[Means for Solving the Problems]
As means for solving the problems, the present invention has the following configuration.
(1) The contact angle of water 75 degrees or more Below 80 degrees Including polymers polymerized from hydrophilic vinyl compounds A polishing pad made of a material and having a micro rubber A hardness of 80 degrees or more.
(2) The polishing pad according to (1), which has closed cells.
(3) Density is 0.6-0.95 (g / cm ^Three The polishing pad according to (2), which is in the range of
(4) The polishing pad according to (1), comprising a polymer polymerized from polyurethane and a vinyl compound.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the invention will be described.
[0008]
First, the micro rubber A hardness referred to in the present invention will be described. This hardness refers to a value evaluated with a micro rubber hardness meter MD-1 manufactured by Kobunshi Keiki Co., Ltd. The micro rubber hardness meter MD-1 realizes the hardness measurement of thin and small samples, which is difficult to measure with a conventional hardness meter, and is about 1/5 of a spring type rubber hardness meter (durometer) A type. Since the model is designed and manufactured as a reduced model, the measured value is consistent with the hardness of the spring type rubber hardness tester A type. The micro rubber hardness tester MD-1 has a cylindrical size with a push needle size of 0.16 mm and a height of 0.5 mm. The load system is a cantilever leaf spring, and the spring load is 2.24 mN at 0 point and 33.85 mN at 100 point. The needle lowering speed is measured by controlling the range of 10 to 30 mm / sec with a stepping motor. Since the thickness of the polishing layer or hard layer of a normal polishing pad is less than 5 mm, the spring type rubber hardness tester A type is too thin to be evaluated, and therefore can be evaluated with the micro rubber hardness tester MD-1.
[0009]
The polishing pad of the present invention requires a micro rubber A hardness of 80 degrees or more, preferably 85 degrees or more. When the micro rubber A hardness is less than 80 degrees, the flatness of the local unevenness of the semiconductor substrate becomes poor, which is not preferable.
[0010]
The material of the polishing pad of the present invention has a water contact angle of 75 degrees or more Must be 80 degrees or less is necessary . The water contact angle of the polishing pad material is greatly affected by the roughness of the surface, so the polishing pad material is sandwiched in a metal plate with a finished surface and pressed at a high temperature to obtain an average roughness on the surface of the material specimen. It is necessary to measure with Ra of 2 μm or less. The measuring method uses a contact meter made by Kyowa Interface Science Co., Ltd., and a water drop with a diameter of 2 mm or less formed on the needle tip is approached on a horizontally placed material test piece and brought into contact with the material test piece. Adhere water drops. The contact angle of the water droplet is observed with an attached microscope. When the water contact angle of the material of the polishing pad exceeds 80 degrees, dust scratches increase, resulting in poor global flatness or metal dishing. The water contact angle of the material is preferably 78 degrees or less.
[0011]
Such a polishing pad preferably has closed cells because dust scratches can be reduced, global flatness can be improved, and metal dishing can be suppressed. The closed cell diameter is preferably 200 μm or less in terms of average cell diameter because the flatness of local irregularities of the semiconductor substrate is good. A more preferable average bubble diameter of the closed cell diameter is 100 μm or less, and a more preferable average bubble diameter is 50 μm or less.
The polishing pad of the present invention has a density of 0.6 to 0.95 (g / cm ^Three ) Is preferable. Density is 0.6 (g / cm ^Three ) Is not preferable because the flatness of the local unevenness becomes poor and the global level difference becomes large. Density is 0.95 (g / cm ^Three If it exceeds), scratches are likely to occur, which is not preferable. Further preferred density is 0.65 to 0.9 (g / cm ^Three ). Further, a more preferable density is 0.7 to 0.85 (g / cm ^Three ).
[0012]
As a specific example of the polishing pad of the present invention, a polishing pad having a micro rubber A hardness of 80 degrees or more, containing a polymer polymerized from polyurethane, a vinyl compound and a hydrophilic vinyl compound, and having closed cells. Can be mentioned. The polishing pad of the present invention needs to contain a polymer polymerized from a hydrophilic vinyl compound. The polyurethane is a polymer synthesized based on polyisocyanate polyaddition reaction or polymerization reaction. The compound used as the symmetry of the polyisocyanate is an active hydrogen-containing compound, that is, two or more polyhydroxy or amino group-containing compounds. Examples of the polyisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate, but are not limited thereto. The polyhydroxy is typically a polyol, and examples of the polyol include polyether polyol, polypropylene glycol, polytetramethylene ether glycol, epoxy resin-modified polyol, polyester polyol, acrylic polyol, polybutadiene polyol, and silicone polyol. Of these, polyurethane obtained by combining tolylene diisocyanate, diphenylmethane diisocyanate as the polyisocyanate, and polypropylene glycol and polytetramethylene ether glycol as the polyol is preferable because it has excellent moldability and is widely used.
[0013]
This vinyl compound is a compound having a vinyl group having a carbon-carbon double bond. Specifically, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methyl (α-ethyl) acrylate, ethyl (α-ethyl) acrylate, propyl (α-ethyl) acrylate, butyl (α-ethyl) ) Acrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, acrylonitrile, acrylamide, vinyl chloride, styrene, α-methylstyrene, N -Methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-phenylmaleimide, etc. It is done. Among them, preferred vinyl compounds are methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methyl (α-ethyl) acrylate, ethyl (α-ethyl) acrylate, propyl (α-ethyl) acrylate, butyl. (Α-ethyl) acrylate. This hydrophilic vinyl compound is a compound having a vinyl bond of a carbon-carbon double bond and a hydrophilic group. Specifically, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl methacrylate, methacrylic acid, fumaric acid, dimethyl fumarate, diethyl fumarate, fumaric acid Examples include dipropyl, maleic acid, dimethyl maleate, diethyl maleate, and dipropyl maleate. The polymer polymerized from the vinyl compound and the hydrophilic vinyl compound herein is a polymer obtained by polymerizing the vinyl compound and the hydrophilic vinyl compound, specifically, polymethyl methacrylate, polyethyl methacrylate, Polypropyl methacrylate, poly (n-butyl methacrylate), polyisobutyl methacrylate, polymethyl (α-ethyl) acrylate, polyethyl (α-ethyl) acrylate, polypropyl (α-ethyl) acrylate, polybutyl (α-ethyl) acrylate, poly (2-ethylhexyl methacrylate), polyisodecyl methacrylate, poly (n-lauryl methacrylate), poly (2-hydroxyethyl methacrylate), poly (2-hydroxypropyl methacrylate), poly (2-hydroxy Chill acrylate), poly (2-hydroxypropyl acrylate), poly (2-hydroxybutyl methacrylate), polydimethylaminoethyl methacrylate, polydiethylaminoethyl methacrylate, polymethacrylic acid, polyglycidyl methacrylate, polyethylene glycol dimethacrylate, polyfumaric acid, polyfumarate Dimethyl acid, diethyl polyfumarate, dipropyl polyfumarate, polymaleic acid, dimethyl polymaleate, diethyl polymaleate, dipropyl polymaleate, polyacrylonitrile, polyacrylamide, polyvinyl chloride, polystyrene, poly (α-methylstyrene), poly (N- Methyl maleimide), poly (N-ethylmaleimide), poly (N-isopropylmaleimide), poly (N-phenylmale) Bromide), and the like. Here, the content of the polymer polymerized from the vinyl compound is preferably 30% by weight or more and 90% by weight or less. When the content is less than 30% by weight, the hardness of the polishing pad is lowered, which is not preferable. When the content exceeds 90% by weight, the elasticity of the pad is impaired, which is not preferable. The content of the polymer polymerized from the polyurethane or vinyl compound and the hydrophilic vinyl compound in the polishing pad can be measured by a pyrolysis gas chromatography / mass spectrometry technique. The apparatus that can be used in this method is a double shot pyrolyzer “PY-2010D” (manufactured by Frontier Laboratories) as a thermal decomposition apparatus, and “TRIO-1” (manufactured by VG) as a gas chromatograph / mass spectrometer. Can do.
[0014]
Here, the polymer polymerized from polyurethane, a vinyl compound and a hydrophilic vinyl compound is contained in an integrated manner, and the phase of polyurethane and the polymer polymerized from the vinyl compound and hydrophilic vinyl compound are separated. However, when expressed quantitatively, various places of the layer having essentially the polishing function in the pad can be expressed by a micro infrared spectroscope having a spot size of 50 μm. The observed infrared spectrum has an infrared absorption peak of polyurethane and an infrared absorption peak of a polymer polymerized from a vinyl compound and a hydrophilic vinyl compound, and the infrared spectra at various places are almost the same. It is. As a micro infrared spectrometer used here, “IR μs” manufactured by SPECTRA-TECH can be mentioned.
[0015]
As a method for producing such a polishing pad, a preferable method is to have closed cells having an average cell diameter of 200 μm or less in advance and a density of 0.5 to 0.95 (g / cm ^Three The method of polymerizing the vinyl compound and the hydrophilic vinyl compound in the foamed polyurethane sheet after swelling the vinyl compound and the hydrophilic vinyl compound in the foamed polyurethane sheet in the range of) is a structure having closed cells with polyurethane and vinyl. A polishing pad in which a polymer polymerized from a compound and a hydrophilic vinyl compound is integrated can be prepared, and the obtained polishing pad is preferable because local unevenness flatness and global steps can be reduced. A more preferable method has closed cells having an average cell diameter of 100 μm or less in advance and a density of 0.6 to 0.9 (g / cm ^Three The method of polymerizing the vinyl compound and the hydrophilic vinyl compound in the foamed polyurethane sheet after swelling the vinyl compound and the hydrophilic vinyl compound in the foamed polyurethane sheet in the range of) is a structure having closed cells with polyurethane and vinyl. A polishing pad in which a polymer polymerized from a compound and a hydrophilic vinyl compound is integrated can be prepared, and the obtained polishing pad is preferable because local unevenness flatness and global steps can be reduced. The foamed polyurethane sheet here needs to determine the combination and optimum amount of polyisocyanate, polyol, catalyst, foam stabilizer, and foaming agent according to the hardness, the cell diameter and the foaming ratio. As the foamed polyurethane sheet, those obtained by foaming the aforementioned polyurethane are preferably used.
[0016]
As a method of polymerizing a vinyl compound and a hydrophilic vinyl compound in a foamed polyurethane sheet after swelling the vinyl compound and the hydrophilic vinyl compound in the foamed polyurethane sheet, a vinyl compound and a hydrophilic vinyl compound are combined with a photodegradable radical initiator. Method of polymerizing by exposing to light after swelling, method of polymerizing by applying heat after swelling vinyl compound and hydrophilic vinyl compound together with thermally decomposable radical initiator, vinyl compound and hydrophilic vinyl An example is a method in which a compound is swollen and then polymerized by emitting an electron beam or radiation.
[0017]
The polishing pad here may contain abrasive grains. Examples of the abrasive grains include silica-based abrasives, aluminum oxide-based abrasives, cerium oxide-based abrasives, and the like. The method for preparing the polishing pad of the present invention containing abrasive grains is obtained by previously containing abrasive grains in the above-mentioned foamed polyurethane sheet, and then swelling the vinyl compound and the hydrophilic vinyl compound in the abrasive grain-containing foamed polyurethane sheet by the above method. Then, as a method of polymerizing the vinyl compound and the hydrophilic vinyl compound in the abrasive foamed polyurethane sheet, the vinyl compound and the hydrophilic vinyl compound are swollen together with the photodegradable radical initiator, and then exposed to light to polymerize. After swelling the vinyl compound and hydrophilic vinyl compound together with the thermal decomposable radical initiator, polymerizing by applying heat, or swelling the vinyl compound and hydrophilic vinyl compound, The method of irradiating and polymerizing is mentioned.
[0018]
The polishing pad obtained in the present invention can be laminated with a cushion sheet having cushioning properties and used as a composite polishing pad. A semiconductor substrate has a slightly larger undulation apart from local unevenness and is often polished by placing a cushion sheet under a hard polishing pad (on the polishing surface plate side) as a layer that absorbs this undulation.
[0019]
Using the polishing pad of the present invention, the unevenness of the insulating film and the unevenness of the metal wiring on the semiconductor wafer are locally planarized using silica-based slurry, aluminum oxide-based slurry, cerium oxide-based slurry, etc. as the slurry. Can be reduced, global steps can be reduced, and dishing can be suppressed. Specific examples of the slurry include CAB-O-SPERSE SC-1 for CMP, CAB-O-SPERSE SC-112 for CMP, SEMI-SPERSE AM100 for CMP, SEMI-SPERSE AM100C for CMP, and SEMI- for CMP. Examples include, but are not limited to, SPERSE 12, SEMI-SPERSE 25 for CMP, SEMI-SPERSE W2000 for CMP, SEMI-SPERSE W-A400 for CMP, and the like.
[0020]
The object of the polishing pad of the present invention is the surface of an insulating layer or metal wiring formed on a semiconductor wafer. As the insulating layer, an interlayer insulating film of metal wiring, a lower insulating film of metal wiring or element isolation is used. Examples of the shallow trench isolation used include aluminum, tungsten, and copper, and damascene, dual damascene, and plug are structurally used. When copper is used as the metal wiring, a barrier metal such as silicon nitride is also subject to polishing. As the insulating film, silicon oxide is mainly used at present, but a low dielectric constant insulating film is used due to the problem of delay time. Although the low dielectric constant insulating film is softer and more brittle than silicon oxide, the polishing pad of the present invention can be polished in a state where scratches are relatively difficult to enter. In addition to semiconductor wafers, it can also be used for polishing magnetic heads, hard disks, sapphire, and the like.
[0021]
In order to suppress the hydroplane phenomenon, the surface shape of the polishing pad of the present invention is used in a shape that can be taken by a normal polishing pad, such as a grooving shape, a dimple shape, a spiral shape, or a concentric circular shape. The polishing pad is used in the form of a disk, but depending on the polishing machine, it may be used as a belt.
[0022]
The polishing pad of the present invention is fixed to a polishing platen (platen) of a polishing machine. The wafer is fixed to a wafer holding sample stage (carrier) by a vacuum chuck method. Rotate the polishing platen, rotate the wafer holding sample stage in the same direction, and press it against the polishing pad. At this time, the slurry is supplied from a position where the slurry enters between the polishing pad and the semiconductor wafer. The optimum supply amount of the slurry is 0.005 to 0.15 (cc / min) per 1 cm 2 area of the polishing pad. When the supply amount of the slurry is less than 0.005 (cc / min), since the lubrication effect of the slurry cannot be sufficiently obtained, scratches are generated on the surface of the semiconductor wafer or the semiconductor wafer is smoothly rotated on the polishing pad. Since it does not occur easily, in-plane uniformity is impaired. When the supply amount of the slurry exceeds 0.15 (cc / min), a liquid film of the slurry is likely to be generated between the semiconductor wafer and the surface of the polishing pad, and the planarization characteristics are deteriorated. The rotational speed of the polishing platen is preferably such that the linear velocity of the polishing platen at the center position of the semiconductor wafer is in the range of 2000 to 5000 (cm / min). When the linear velocity of the polishing platen is less than 2000 (cm / min), the flattening rate becomes slow, which is not preferable. When the linear velocity of the polishing platen exceeds 5000 (cm / min), scratches are likely to occur, which is not preferable. The pressing pressure is performed by controlling the force applied to the wafer holding sample stage. Since high global flatness is obtained by reducing the pressing pressure, 0.01 to 0.04 MPa is preferable. However, depending on the polishing machine, a high-speed and low-pressure surface plate method has been developed, and it cannot be used except for the above polishing conditions.
[0023]
The polishing pad of the present invention is usually dressed with a conditioner having diamond abrasive grains attached by electrodeposition on the surface before polishing. As the dressing method, either batch dressing performed before polishing or in-situ dressing performed simultaneously with polishing can be performed.
[0024]
The object of the present invention is to provide a polishing pad for mechanically flattening the surface of an insulating layer or metal wiring formed on a silicon substrate. A polishing pad with less scratches is provided.
[0025]
【Example】
Hereinafter, the details of the present invention will be described with reference to examples. In this example, each characteristic was measured by the following method.
1. Micro rubber A hardness: Measured with a micro rubber hardness meter “MD-1” of Kobunshi Keiki Co., Ltd.
[0026]
The configuration of the micro rubber hardness tester “MD-1” is as follows.
1.1 Sensor unit
(1) Load method: Cantilevered leaf spring
(2) Spring load: 0 point / 2.24 gf. 100 points / 33.85 gf
(3) Spring load error: ± 0.32 gf
(4) Needle size: Diameter: 0.16 mm cylindrical shape. 0.5mm height
(5) Displacement detection method: Strain gauge method
(6) Pressure leg dimensions: Outer diameter 4mm Inner diameter 1.5mm
1.2 Sensor drive unit
(1) Driving method: vertical driving by a stepping motor. Descent speed control by air damper
(2) Vertical movement stroke: 12mm
(3) Descent speed: 10-30mm / sec
(4) Height adjustment range: 0 to 67 mm (distance between sample table and sensor pressing surface)
1.3 Sample stage
(1) Sample stage dimensions: Diameter 80mm
(2) Fine movement mechanism: Fine movement by an XY table and a micrometer head. Stroke: 15mm for both X and Y axes
(3) Level adjuster: Level adjustment body legs and round level
2. Dynamic tensile storage elastic modulus: Measured with a dynamic viscoelasticity measuring device “Rheogel E-4000” of UBM Co., Ltd. (location :).
[0027]
The configuration of the dynamic viscoelasticity measuring apparatus “Rheogel E-4000” is as follows.
2.1 Main body mechanism
(1) Exciter: A compact electric exciter that can be vibrated efficiently by attaching a large number of powerful cylindrical magnets to the outside and inside of a moving coil that is electromagnetically conductive.
(2) Dynamometer: A sensor that uses the piezoelectric effect of a crystal piezoelectric element. The measuring range is wide, the rigidity is large, and the sensor itself hardly distorts against the measuring stress. For this reason, as in the case of a general load cell, the phase shift that occurs when the strain of the sensor itself is large and the error in measuring the strain of the sample during high elasticity are small.
(3) Displacement meter: An eddy current non-contact displacement meter. There is a resolution of 0.1 μm or less.
2.2 Control measurement unit
It communicates with a personal computer and controls the drive of the main unit mechanism.
2.3 Computer system (PC, CRT, printer)
Calculation and recording of the read data, generation of control signals and data processing are performed. Commercially available spreadsheet / graphics software can be used for the data.
2.4 Measuring jig
A tensioning jig was used.
3. Dust / scratch evaluation test wafer: 4 inch silicon wafer with oxide film (oxide film thickness: 1 μm) is used.
4). Test wafer for global level difference: A 10 mm square die is placed on a 4-inch silicon wafer with oxide film (oxide film thickness: 2 μm). Mask exposure using photoresist, 20μm width, 0.7μm height and 230μm space in a 10mm square die by RIE, line and space on the left half, 230μm width, height A 0.7 μm line is arranged on the right half in a line and space with a space of 20 μm. In this way, a test wafer for global level difference evaluation was prepared.
5. Test wafer for evaluating tungsten wiring dishing: Grooves having a width of 100 μm and a depth of 0.7 μm are formed at intervals of 100 μm on a 4-inch silicon wafer with an oxide film (oxide film thickness: 2 μm). A tungsten wafer having a thickness of 2 μm was formed thereon by sputtering to produce a test wafer for evaluating tungsten wiring dishing.
6). Polishing pad and polishing machine: A circular polishing layer having a thickness of 1.2 mm and a diameter of 38 cm is produced, and a so-called XY groove processing (lattice groove processing) having a width of 2.0 mm, a depth of 0.5 mm, and a pitch of 15 mm on the surface Was given. As a cushion layer, the polishing pad (Lupmaster SFT, manufactured by L / M-15E) is used as a cushion layer, and Rodale's “Suba400” is applied to the polishing pad. Double-sided adhesive tape (3M, manufactured by “442J”) ) Using Asahi Diamond Industrial Co., Ltd. conditioner (CMP-M, diameter 14.2 cm), rotating 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, 10 cc of pure water The polishing pad was conditioned for 5 minutes while being fed at / min. The polishing pad was washed for 2 minutes while flowing pure water at 100 cc / min into the polishing machine. Next, a test wafer for global step evaluation was installed in the polishing machine, and a slurry ("SC-1 ") Is supplied onto the polishing pad at a predetermined supply amount, the pressing pressure is set to a predetermined pressure of 0.01 MPa to 0.04 MPa, the platen rotation speed is 45 rpm (the 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 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 applying pure water immediately, and dried by blowing dry compressed air. The oxide film thickness of the 20μm line and 230μ line in the center 10mm die of the test wafer for global level difference measurement is measured using Lambda Ace (“VM-2000”) manufactured by Dainippon Screen Co., Ltd. As evaluated.
In addition, the same conditioning as described above was performed, a test wafer for evaluating tungsten wiring dishing was set in a polishing machine, and a cabot slurry (“SEMI-SPERSE W-A400”) having a use concentration described in the instruction manual and an oxidizing agent manufactured by Cabot. (SEMI-SPERSE FE-400) mixed at 1: 1 while supplying a predetermined amount of slurry solution onto the polishing pad, the pressing pressure is set to a predetermined pressure of 0.01 MPa to 0.04 MPa, and a surface plate The semiconductor wafer holding sample stage was rotated in the same direction at a rotation speed of 45 rpm (linear velocity at the center of the wafer was 3000 (cm / min)) and the rotation speed was 45 rpm, and polishing was performed for a predetermined time. The surface of the semiconductor wafer was not dried, and the surface of the wafer was washed with a polyvinyl alcohol sponge while applying pure water immediately, and dried by blowing dry compressed air. The dishing state of the tungsten surface was measured with an ultra-deep shape measuring microscope “VK-8500” manufactured by Keyence Corporation. In addition, the same conditioning as described above is performed, a test wafer for dust / scratch evaluation is placed in a polishing machine, and a slurry ("SC-1") having a concentration of use described in the manual is applied onto the polishing pad at a predetermined supply amount. While supplying, the pressing pressure is set to a predetermined pressure of 0.01 MPa to 0.04 MPa, the rotation speed of the platen is 45 rpm (the linear velocity at the center of the wafer is 3000 (cm / min)), and the semiconductor wafer holding sample stage is rotated. It was rotated in the same direction at 45 rpm and polished for a predetermined time. Do not dry the surface of the semiconductor wafer, clean the wafer surface with polyvinyl alcohol sponge while applying pure water immediately, leave it in a natural state, and dry it. The above dust was inspected, and then the scratch was inspected with a microscope.
[0028]
Example 1
100 parts by weight of polypropylene glycol, 80 parts by weight of diphenylmethane diisocyanate, 0.6 parts by weight of water, 1.4 parts by weight of an amine catalyst and 1.0 part by weight of a silicone foam stabilizer are mixed in a RIM molding machine and discharged into a mold. Then, pressure molding is performed and a foamed polyurethane sheet having a thickness of 4.2 mm (micro rubber A hardness = 49 degrees, density: 0.83 (g / cm ^Three ), Closed cell average diameter: 29 μm). The foamed polyurethane sheet is immersed in 90 parts by weight of methyl methacrylate and 10 parts by weight of methacrylic acid to which 0.1 parts by weight of azobisisobutylnitrile has been added for 65 minutes. A polyurethane foam sheet swelled with methyl methacrylate / methacrylic acid is sandwiched between glass plates, heated at 65 ° C. for 6 hours, and then heated at 100 ° C. for 3 hours. Remove from the glass plate after heating and vacuum dry at 50 ° C. The obtained hard foam sheet is ground on both sides to prepare a polishing pad having a thickness of 1.2 mm. The resulting polishing pad has a micro rubber A hardness of 90 degrees and a density of 0.81 (g / cm ^Three ), Closed cell average diameter: 39 μm, water contact angle of the material: 77 degrees. The polymethyl methacrylate / polymethacrylic acid content in the polishing pad was 51% by weight. A cushion layer “Suba400” was bonded to the polishing pad to form a composite polishing pad. A test wafer for global level difference evaluation is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the polishing head. 1 "35cc / min (Polishing pad 1cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The polishing time when the global step between the 20 μm wide wiring region and the 230 μm wide wiring region of the test wafer for global step evaluation was 0.2 μm was 4.5 minutes. Further, a tungsten wafer dishing evaluation test wafer is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the rotation direction of the polishing head. 35cc / min of tungsten slurry (1cm polishing pad) ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The dishing depth at the center of the tungsten wiring (100 μm width) when the oxide film surface was exposed was 0.03 μm. The test wafer for dust / scratch evaluation is attached to the polishing head of the polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to the platen of the polishing machine and rotated in the same direction as the rotation direction of the polishing head at 45 rpm. -1 "35 cc / min (polishing pad 1 cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The number of dust was 6 and scratches were 0.
[0029]
Example 2
100 parts by weight of polypropylene glycol, 8 parts by weight of ethylene glycol, 95 parts by weight of diphenylmethane diisocyanate, 0.3 parts by weight of water, 1.0 part by weight of an amine-based catalyst and 1.0 part by weight of a silicon foam stabilizer are mixed with a RIM molding machine. The foamed polyurethane sheet (micro rubber A hardness = 43 degrees, density: 0.75, closed cell average diameter: 29 μm) having a thickness of 5.0 mm was prepared by discharging into a mold and performing pressure molding. The foamed polyurethane sheet is immersed for 70 minutes in 95 parts by weight of methyl methacrylate and 5 parts by weight of 2-hydroxyethyl methacrylate to which 0.1 part by weight of azobisisobutylnitrile has been added. A foamed polyurethane sheet swelled with methyl methacrylate / 2-hydroxyethyl methacrylate is sandwiched between glass plates, heated at 65 ° C. for 6 hours, and then heated at 100 ° C. for 3 hours. Remove from the glass plate after heating and vacuum dry at 50 ° C. The obtained hard foam sheet is ground on both sides to prepare a polishing pad having a thickness of 1.2 mm. The resulting polishing pad has a micro rubber A hardness of 91 degrees and a density of 0.75 (g / cm ^Three ), Closed cell average diameter: 39 μm, water contact angle of material: 75 degrees. The polymethyl methacrylate / 2-hydroxyethyl methacrylate content in the polishing pad was 65% by weight. A cushion layer “Suba400” was bonded to the polishing pad to form a composite polishing pad. A test wafer for global level difference evaluation is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the polishing head. 1 "35cc / min (Polishing pad 1cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The global step difference between the 20 μm wide wiring region and the 230 μm wide wiring region of the test wafer for global step evaluation was 0.2 μm, and the polishing time was 3.5 minutes. Further, a tungsten wafer dishing evaluation test wafer is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the rotation direction of the polishing head. Polishing was performed at a polishing pressure of 0.04 MPa while supplying a tungsten slurry manufactured by the company at 35 cc / min (0.031 cc / min per 1 cm 2 area of the polishing pad). The dishing depth at the center of the tungsten wiring (100 μm width) when the oxide film surface was exposed was 0.03 μm. The test wafer for dust / scratch evaluation is attached to the polishing head of the polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to the platen of the polishing machine and rotated in the same direction as the rotation direction of the polishing head at 45 rpm. -1 "35 cc / min (polishing pad 1 cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The number of dust was 7 and the number of scratches was 0.
[0030]
Comparative Example 1
78 parts by weight of a polyether-based urethane polymer (Adiprene L-325 manufactured by Uniroyal) and 20 parts by weight of 4,4′-methylene-bis2-chloroaniline were mixed with a RIM molding machine, and hollow polymer microspheres (Expercel 551) were mixed. DE) 1.8 parts by weight are mixed and discharged into a mold and subjected to pressure molding, and a foamed polyurethane sheet having a thickness of 2.2 mm (micro rubber A hardness = 95 degrees, density = 0.75 (g / cm ^Three ), Closed cell average diameter = 30 μm, water contact angle of material: 81 degrees). A cushion layer “Suba400” was bonded to the polishing pad to form a composite polishing pad. A test wafer for global level difference evaluation is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the polishing head. 1 "35cc / min (Polishing pad 1cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The polishing time when the global step between the 20 μm wide wiring region and the 230 μm wide wiring region of the test wafer for global step evaluation was 0.2 μm was 7 minutes. Further, a tungsten wafer dishing evaluation test wafer is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the rotation direction of the polishing head. Polishing was performed at a polishing pressure of 0.04 MPa while supplying a tungsten slurry manufactured by the company at 35 cc / min (0.031 cc / min per 1 cm 2 area of the polishing pad). The dishing depth at the center of the tungsten wiring (100 μm width) when the oxide film surface was exposed was 0.13 μm. The test wafer for dust / scratch evaluation is attached to the polishing head of the polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to the platen of the polishing machine and rotated in the same direction as the rotation direction of the polishing head at 45 rpm. -1 "35 cc / min (polishing pad 1 cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The number of dust was 20 and the number of scratches was 1.
[0031]
Comparative Example 2
78 parts by weight of a polyether-based urethane polymer (Adiprene L-325 manufactured by Uniroyal), 20 parts by weight of 4,4′-methylene-bis-2-chloroaniline and 0.3 parts by weight of water are mixed with a RIM molding machine. 5mm thick foamed polyurethane sheet (micro rubber A hardness = 95 degrees, density = 0.75 (g / cm ^Three ), Average closed cell diameter = 140 μm, water contact angle of material: 81 degrees). A cushion layer “Suba400” was bonded to the polishing pad to form a composite polishing pad. A test wafer for global level difference evaluation is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the polishing head. 1 "35cc / min (Polishing pad 1cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The global level difference between the 20 μm wide wiring region and the 230 μm wide wiring region of the test wafer for global step evaluation was 0.25 μm, and the polishing time was 7 minutes. Further, a tungsten wafer dishing evaluation test wafer is attached to a polishing head of a polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to a platen of the polishing machine and rotated at 45 rpm in the same direction as the rotation direction of the polishing head. Polishing was performed at a polishing pressure of 0.04 MPa while supplying a tungsten slurry manufactured by the company at 35 cc / min (0.031 cc / min per 1 cm 2 area of the polishing pad). The dishing depth of the central portion of the tungsten wiring (100 μm width) when the oxide film surface was exposed was 0.15 μm. The test wafer for dust / scratch evaluation is attached to the polishing head of the polishing machine and rotated at 45 rpm. The composite polishing pad is fixed to the platen of the polishing machine and rotated in the same direction as the rotation direction of the polishing head at 45 rpm. -1 "35 cc / min (polishing pad 1 cm ² Polishing was performed at a polishing pressure of 0.04 MPa while supplying at a rate of 0.031 cc / min per area. The number of dust was 60 and the number of scratches was 10.
[0032]
【The invention's effect】
In the present invention, in the polishing pad for mechanically flattening the surface of the insulating layer or metal wiring formed on the silicon substrate, the global step is small, and dishing in the metal wiring is unlikely to occur. It was possible to provide a polishing pad with less generation.

Claims (4)

80 ° der less contact angle of 75 degrees or more of water is, is formed of a material comprising a polymer polymerized from a hydrophilic vinyl compounds, and the polishing pad is micro rubber A hardness of 80 degrees or more.  The polishing pad according to claim 1, wherein the polishing pad has closed cells. The polishing pad according to claim 2, wherein the density is in the range of 0.6 to 0.95 (g / cm ³ ).  The polishing pad according to claim 1, further comprising a polymer polymerized from polyurethane and a vinyl compound.