JP2009148876A - Polishing pad and polishing method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a conventional polishing pad and polishing method using it are inadequate in respect of the stability of a polishing characteristic and shortening of a rising time during use. <P>SOLUTION: (1) The polishing pad having at least a polishing layer is sealed in a state moistened by water. (2) The polishing method includes fixing an object to be polished on a polishing head, and rotating the polishing head and/or polishing platen in a state that the polishing pad described in (1) fixed to the polishing platen is brought into contact with the object to be polished. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing pad that can be used in the process of planarizing a semiconductor substrate, the surface of an insulating layer formed on the semiconductor substrate, and the surface of a metal wiring, and a polishing method using the same.

  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 substrate caused by stacking, which has not been a problem in the past, has become a problem. For this reason, chemical mechanical polishing (CMP) technology is used to compensate for insufficient depth of focus at the time of exposure due to unevenness caused by lamination or to improve wiring density by flattening the through-hole portion. Planarization of the used semiconductor substrate has been studied (for example, Non-Patent Document 1).

  In general, a CMP apparatus includes a polishing head that holds a semiconductor substrate that is an object to be polished, a polishing pad that performs polishing of the object to be polished, and a polishing surface plate that holds the polishing pad. Then, the polishing process of the semiconductor substrate is performed by using a polishing slurry composed of an abrasive (abrasive grains) and a chemical solution to move the semiconductor substrate and the polishing pad relative to each other, thereby removing the protruding portion of the semiconductor substrate surface layer. The layer on the substrate surface is smoothed.

  As a typical polishing pad currently used in CMP, a polyurethane-impregnated nonwoven fabric, a soft foamed polyurethane, etc., which is a cushion layer, are bonded to a hard polyurethane having a fine foam structure (bubble diameter: about 30-50 μm), which is a polishing layer. Examples thereof include a combined two-layer polishing pad (for example, Patent Document 1 and Non-Patent Document 2) and a polishing pad using a non-foamed elastomer for the cushion layer (for example, Patent Document 2).

  The polishing pad manufactured in this way is used by being fixed to the polishing surface plate with an adhesive tape on the back surface during use. However, the characteristics of the polishing layer and the cushion layer (for example, water absorption rate, hardness, elastic modulus, etc.) change from moment to moment depending on the water and polishing slurry used during polishing until they become stable at a certain level. There was a problem that it was not stable or the time until the polishing characteristics were stabilized, that is, the time required for startup was long.

That is, the conventional polishing pad and the polishing method using the same are insufficient in terms of the stability of the polishing characteristics and the shortening of the startup time during use.
Nikkei Microdevices July 1994, pages 50-57 JP-A-6-21028 CMP Technology Group, Global Net Co., Ltd. (2006), pp. 478-481 Japanese Patent No. 3685066

Therefore, as a result of intensive studies to solve these problems, the present inventors sealed the package after manufacturing the polishing pad in a state where the polishing pad is wet in water or in a state where the polishing pad is immersed in water. As a result, the polishing pad characteristics (eg, water absorption, hardness, elastic modulus, etc.) are stabilized before use, that is, before being affixed to the polishing surface plate, so that the polishing characteristics can be stabilized and the start-up time during use can be shortened. This was confirmed and the present invention was completed.

  An object of the present invention is to provide a polishing pad that can be used in a process of planarizing a semiconductor substrate, a surface of an insulating layer formed on the semiconductor substrate, or a surface of a metal wiring, and a polishing method using the same. It is an object of the present invention to provide a polishing pad that is highly stable and can shorten the startup time during use, and a polishing method using the same.

In order to solve the above problems, the present invention has the following configuration.
“(1) A polishing pad, wherein a polishing pad having at least a polishing layer is sealed in a wet state with water.
(2) An object to be polished is fixed to a polishing head, and the polishing head and / or the polishing platen is rotated with the polishing pad according to (1) in contact with the object to be polished being fixed to a polishing surface plate. Polishing method characterized by performing polishing. "

  According to the present invention, a polishing pad that can be used in a process of planarizing a semiconductor substrate, a surface of an insulating layer formed on the semiconductor substrate or a surface of a metal wiring, and a polishing method using the same can be stabilized. It is possible to provide a polishing pad that has high performance and can shorten the start-up time during use, and a polishing method using the same.

  The polishing pad of the present invention is sealed in a state where at least the polishing pad having the polishing layer is wetted with water in order to obtain a polishing pad having high polishing characteristics and capable of shortening the startup time during use. It is essential that If the polishing pad having at least the polishing layer is not wetted with water, the characteristics of the polishing layer and the cushion layer (for example, water absorption, hardness, elastic modulus, etc.) due to the water and polishing slurry used during polishing. Etc.) change from moment to moment until they are stabilized at a certain level, which is not preferable because there is a problem that the polishing characteristics are not stable or the time until the polishing characteristics are stabilized, that is, the time required for start-up is long.

  Here, the state wetted with water means that the amount of water retained is larger than when a polishing pad having at least a polishing layer is left in a normal indoor environment. The amount of water held is determined by the following formula from the difference between the weight of the polishing pad immediately after unpacking and the weight of the polishing pad after air drying until there is no change in weight at a temperature of 23 ° C. and humidity: 50%. It can be expressed by the water absorption rate.

Water absorption rate = (weight of polishing pad immediately after unpacking−weight of polishing pad after air drying) / (weight of polishing pad after air drying) × 100
The moisture adhering to the polishing pad surface immediately after unpacking was wiped off and then air-dried. Although it cannot be generally described because it depends on the material and configuration of the polishing pad, the water absorption is preferably 5% or more, more preferably 10% or more, and further preferably 30% or more.

  The polishing pad having at least the polishing layer is in a wet state, that is, the polishing pad holds, in that the time required for stabilizing the characteristics of the polishing pad is short and the fluctuation of the characteristics of the polishing pad after unpacking is small. It is preferable that the amount of water is large, and it is more preferable that the polishing pad having at least the polishing layer is sealed in a state of being immersed in water.

  Although the water in this invention is not specifically limited, The pure water from which the foreign material, metal ion, etc. in water were removed and ion-exchange water are preferable. In addition, a bactericidal agent such as sodium hypochlorite or an abrasive slurry component such as an alkali, acid, or abrasive may be added to the water.

  In the present invention, the method of wetting or immersing at least a polishing pad having a polishing layer in water is not particularly limited. Specifically, a method of immersing the polishing pad in a container containing water for a certain period of time, a method of standing in a constant temperature and humidity chamber in a humid state, and the like can be mentioned. At that time, it is also preferable to perform treatments such as heating, pressurization, decompression, and shaking as necessary.

  In the present invention, the method for sealing the polishing pad is not particularly limited. Specific examples include a method of putting in a sealed container with packing or the like, a method of heat sealing in a plastic bag, and the like. Among these, the method of heat sealing in a plastic bag is preferable from the viewpoint of cost and productivity. In that case, the plastic bag material is preferably laminated with inorganic components such as silicon dioxide and aluminum oxide in order to improve gas barrier properties and reduce moisture permeability.

  In the polishing pad of the present invention, a cushion layer may be further laminated in addition to the polishing layer. The method for laminating the polishing layer and the cushion layer is not particularly limited. Specifically, an adhesive layer is formed between the polishing layer and the cushion layer by a method such as laminating a double-sided adhesive tape to the polishing layer or applying various adhesives to the polishing layer. The method of pressurizing with a press, a flat plate press, etc. is mentioned. In this case, it is also preferable to heat the laminator and the press itself within a range that does not adversely affect the polishing layer and the cushion layer.

  Among these, pressurization by a roll press is preferable from the viewpoint of productivity. The applied pressure is not particularly limited, but the linear pressure is preferably 0.5 to 15 kg / cm. When the linear pressure is less than 0.5 kg / cm, there is a tendency that minute air remains at the interface between the polishing layer and the cushion layer and the adhesive (air engagement), and the adhesive force between the polishing layer and the cushion layer decreases. Yes, if it exceeds 15 kg / cm, the resulting polishing pad tends to be deformed such as warpage. More preferably, it is 1-10 kg / cm.

  The material of the adhesive is not particularly limited. Specific examples include various adhesives such as urethane, epoxy, acrylic and rubber, and various double-sided adhesive tapes produced by applying these adhesives to both surfaces of a substrate such as a film or nonwoven fabric. .

  Among various adhesives, as a specific product name of urethane-based adhesives, “Rubilon (registered trademark) 602”, “Rubilon (registered trademark) 603”, “Rubicoat (registered trademark)” manufactured by Toyo Polymer Co., Ltd. are registered as one-pack type. Trademark) F-7 "," Rubilac (Registered Trademark) 603 "," Rubilac (Registered Trademark) 645E "," Rubilon (Registered Trademark) 101 "," Rubilon Ace (Registered Trademark) "," Rubilon (Registered Trademark) 202 " "Rubilon (registered trademark) AAA", "Rubilon (registered trademark) R", "Rubilon (registered trademark) 101SP", "Rubilon (registered trademark) Floor 503", "Lubilon (registered trademark) 302", "Lubilon ( (Registered trademark) 155 ”, manufactured by Toagosei Co., Ltd.“ PU-3030D ”,“ PU-7000D ”, manufactured by Cemedine Co., Ltd.“ UM700 ”,“ UM700S ”, “UM750”, “UM100”, “UM300HK”, “UM550”, “UM600”, “UM600V”, “UM600VL”, “Takelac (registered trademark) A367H”, “Takelac (registered trademark) A369” manufactured by Mitsui Chemicals Polyurethanes, Inc. "Takenate (registered trademark) A7", "Takenate (registered trademark) A19" and the like, and in the two-pack type, "Rubilon (registered trademark) KA-28, KB-28" manufactured by Toyo Polymer Co., Ltd., “RUBILON (registered trademark) KA-38, KB48”, “RUBILON (registered trademark) KA-42, KB-33”, “RUBILON (registered trademark) KA-10, KB-33ME”, “NA-21, NB-” 29 ”, manufactured by Toagosei Co., Ltd.“ PU-62 A agent, PU-62 B agent ”,“ PU-9000, PU-171 ”, etc. It is not limited to that.

  Specific product names of epoxy adhesives include "Aronmighty (registered trademark) AP-0786", "Alonmighty (registered trademark) AP-3510", "Aronmighty (registered)" manufactured by Toagosei Co., Ltd. Trademark) AP-3513 ", Cemedine Co., Ltd." EP-138 "," EP-170 "," EP-160NL "Two-pack type" Aronmighty (registered trademark) AP-205 "manufactured by Toagosei Co., Ltd. ”,“ Aronmighty (registered trademark) AP-209 ”,“ Aronmighty (registered trademark) AP-317 ”,“ EP-001 ”,“ EP-007 ”,“ EP-330 ”manufactured by Cemedine Co., Ltd., solution Examples of the dilution type include “Aronmighty (registered trademark) AS-60” and “Aronmighty (registered trademark) AS-310” manufactured by Toagosei Co., Ltd., but are not limited thereto. There. Specific names of acrylic adhesives include “Aronmite (registered trademark) X-2100T” manufactured by Toagosei Co., Ltd., “Y-610”, “Y-620” manufactured by Cemedine Co., Ltd. and the like. However, it is not limited to these. Examples of the rubber-based adhesive include “521” and “575” manufactured by Cemedine Co., Ltd. and “Hybon (registered trademark) 1420” manufactured by Hitachi Chemical Co., Ltd., but are not limited thereto.

  In addition to the above-described ordinary adhesives, solvent-free heat-melt adhesives are also preferably used as the adhesive from the viewpoint of environment and workability. Depending on the type of heat-melt adhesive, the adhesive is melted at a temperature of about 70 to 130 ° C., applied to one or both of the adherends with a roll coater, etc., and bonded and pressed while sticky. After the treatment or the like, the adhesive is bonded by cooling and solidifying. In some cases, after bonding, the resin is cured by crosslinking reaction in the air or by moisture or moisture of the adherend, thereby increasing the adhesive strength. Specific examples of heat-melt-type adhesives include polyester-based, modified olefin-based, urethane-based adhesives, etc., as described above, types that are cooled and cured after melt bonding, and after melt-bonding / cooling-curing, and further in the air There are two types that crosslink by reacting with moisture.

  Specific product names of polyester-based heat-melt adhesives include “Aronmelt (registered trademark) PES series” manufactured by Toagosei Co., Ltd., and specific product names of modified olefin-based heat-melt adhesives include Toagosei ( Specific product names of “Aronmelt (registered trademark) PPET series” manufactured by Co., Ltd. and urethane-based heat-melt adhesives are “Aronmelt (registered trademark) R series” manufactured by Toagosei Co., Ltd., and “QR4663” manufactured by Henkel. , “QR4635”, “ARX-1288C2”, “ARX-1288H”, “ARX-1311D”, “ARX-1270”, “ARX1255C1”, “ARX-1308A” manufactured by Nitta Gelatin Co., Ltd., Hitachi Chemical ( "Hibon (registered trademark) 4812", "Hibon (registered trademark) 4820", "Hibon (registered trademark)" 830 "," Hibon (registered trademark) 4832 "," Hibon (registered trademark) YR713-1W "," Hibon (registered trademark) 4820 "," Hibon (registered trademark) YR346-1 ", manufactured by Mitsui Chemicals Polyurethanes, Inc. “MA-1102W”, “MA-1102S”, “MA-3002T”, “MA-3229”, “MA-1001”, “MA-0110S”, “MA-4008”, “MA-4013”, “MA -4100 "," MA-4014 "," MA-4015 "," MA-5002 "," MA-5203 "," MA-5214 "," MA-5215 "," MA-5310 ", Konishi Co., Ltd. Examples thereof include “KUM3150”, “KUM3150S”, “KUM3200” and the like, but are not limited thereto.

  Specific product names of the double-sided adhesive tape include “442JS” manufactured by Sumitomo 3M Limited, “535A” manufactured by Nitto Denko Corporation, “5782W”, “5604TDM” manufactured by Sekisui Chemical Co., Ltd., and Teraoka Co., Ltd. “751”, “758”, “777”, “782”, “761”, “7021”, and the like manufactured by Seisakusho are listed, but not limited thereto.

  In addition, after laminating the polishing layer single layer or the polishing layer and the cushion layer, it is preferable to attach a double-sided adhesive tape for fixing the polishing surface plate to the surface opposite to the polishing layer or the cushion layer. The material and bonding method of the double-sided adhesive tape are as described above and are not particularly limited.

  The cushion layer in the present invention is not particularly limited. The structure of the cushion layer may be either foamed or non-foamed, and the foamed structure may be either independent foamed or continuous foamed. In particular, the present invention can be particularly preferably used for a cushioning layer having a foam structure in which polishing characteristics change easily due to moisture.

  The material of the cushion layer includes nonwoven fabric impregnated polyurethane, natural rubber, nitrile rubber, neoprene (registered trademark) rubber, polybutadiene rubber, chloroprene rubber, thermoplastic polyurethane rubber, thermosetting polyurethane rubber, silicone rubber, fluorine rubber, etc. It is not limited to these. These cushion layer materials may contain various additives such as antistatic agents, lubricants, stabilizers, dyes, and other resins in order to obtain necessary properties.

  The hardness of the cushion layer is not particularly limited, but a micro rubber A hardness of 50 to 80 is preferable because of excellent in-plane uniformity of polishing. When the micro rubber A hardness is less than 50, the planarization property tends to deteriorate during polishing, and when it exceeds 80, the in-plane uniformity deteriorates during polishing. In addition, the micro rubber A hardness in the present invention refers to a value measured with a micro rubber hardness meter MD-1 manufactured by Kobunshi Keiki Co., Ltd. The micro rubber hardness tester MD-1 is capable of measuring the hardness of thin and small samples, which are difficult to measure with a conventional hardness tester, and is approximately 1 / of the spring type rubber hardness tester (durometer) A type. Since it is designed and manufactured as a reduced model of 5, the measured value can be considered to be the same as the measured value in the spring type rubber hardness tester A type. In addition, since the thickness of a normal polishing pad or a hard layer is too thin with 5.0 mm or less, a spring-type rubber hardness meter cannot be evaluated, but it can be evaluated with the micro rubber hardness meter MD-1.

  The thickness of the cushion layer is not particularly limited, but is preferably 0.1 to 5.0 mm. Since the cushioning property of the polishing pad obtained is less than 0.1 mm, the in-plane uniformity during polishing tends to deteriorate, and the cushioning layer exceeding 5.0 mm tends to deteriorate flattening characteristics. . More preferably, it is 0.5 to 3.0 mm. More preferably, it is 0.5 to 1.0 mm.

The strain constant of the cushion layer is not particularly limited, but is preferably 0.001 to 0.17 μm / (gf / cm ² ) (0.07 to 11.95 μm / psi). If it is smaller than 0.001 μm / (gf / cm ² ) (0.07 μm / psi), the in-plane uniformity tends to deteriorate, and if it is larger than 0.17 μm / (gf / cm ² ) (11.95 μm / psi), the flattening characteristics are deteriorated. It tends to get worse. More preferably, it is 0.004 to 0.09 μm / (gf / cm ² ) (0.28 to 6.33 μm / psi). More preferably, it is 0.01 to 0.08 μm / (gf / cm ² ) (0.70 to 5.62 μm / psi). According to JIS-L1096, the strain constant in the present invention is T1 when a first load of 300 gf / cm ² (4.3 psi) is applied, and a second load of 1000 gf / cm ² (14.3 psi). When the thickness of T2 is T2,
Strain constant = (T1-T2) / (1000-300) (Unit: μm / (gf / cm ² ))
Is defined.

  The polishing layer in the present invention is not particularly limited. Specific examples of the material include polyethylene, polypropylene, polyester, polyurethane, polyurea, polystyrene, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, polycarbonate, polyamide, polyacetal, polyimide, epoxy resin, unsaturated polyester resin, melamine resin, Various laminates such as phenol resin, ABS resin, bakelite, epoxy resin / paper, epoxy resin / fiber, FRP, natural rubber, neoprene (registered trademark) rubber, chloroprene rubber, butadiene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, ethylene Various rubbers such as propylene rubber, silicone rubber, and fluorine rubber can be used.

  The structure of the polishing layer of the present invention may be either foamed or non-foamed, but is preferably a foamed structure in terms of good polishing characteristics such as polishing speed and in-plane uniformity, and few defects such as dust and scratches. .

  A known method can be used as a method for forming the foam structure on the polishing layer. For example, various foaming agents are blended in the monomer or polymer, followed by foaming by heating or the like, hollow microbeads are dispersed and cured in the monomer or polymer, and the microbead portion is closed cell A method in which a molten polymer is mechanically stirred and foamed, and then cooled and cured, and a solution in which the polymer is dissolved in a solvent is formed into a sheet, and then in a poor solvent for the polymer. Examples include a method of immersing and extracting only a solvent, a method of impregnating a monomer into a sheet-like polymer having a foamed structure, and then curing by polymerization. Among these, the formation of the foam structure of the polishing layer and the control of the bubble diameter are relatively simple, and the monomer is impregnated into the sheet-like polymer having the foam structure in that the preparation of the polishing layer is also simple. Thereafter, a polymerization and curing method is preferred.

  The material of the sheet-like polymer having a foam structure is not particularly limited as long as it can be impregnated with a monomer. Specifically, various rubbers such as polyurethane, polyurea, soft vinyl chloride, natural rubber, neoprene (registered trademark) rubber, chloroprene rubber, butadiene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, ethylene propylene rubber, silicone rubber, fluorine rubber, etc. Resin sheet, cloth, non-woven fabric, paper and the like mainly composed of In addition, these sheet-like polymers may contain various additives such as abrasives, lubricants, antistatic agents, antioxidants, stabilizers and the like for the purpose of improving the characteristics of the polishing pads to be produced. good. Among these, a material mainly composed of polyurethane is preferable in that the bubble diameter can be controlled relatively easily.

  The monomer is not particularly limited as long as it undergoes a polymerization reaction such as addition polymerization, polycondensation, polyaddition, addition condensation, and ring-opening polymerization. Specific examples include vinyl compounds, epoxy compounds, isocyanate compounds, dicarboxylic acids and the like. Among these, a vinyl compound is preferable because it is easy to impregnate and polymerize a sheet-like polymer. The vinyl compound in the present invention is not particularly limited, but a vinyl compound is preferable from the viewpoint of easy impregnation and polymerization in polyurethane.

  Specifically, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl Methacrylate, 2-hydroxybutyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, acrylic acid, methacrylic acid, fumaric acid, dimethyl fumarate, diethyl fumarate, dipropyl fumarate, maleic acid, maleic Dimethyl acid, diethyl maleate, dipropyl maleate, phenylmaleimide, Hexyl maleimide, isopropyl maleimide, acrylonitrile, acrylamide, vinyl chloride, vinylidene chloride, styrene, alpha-methyl styrene, divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and the like. These monomers can be used alone or in combination of two or more.

  Among the vinyl compounds mentioned above, methyl methacrylate has good impregnation into polyurethane, is easy to polymerize and cure, polymer polymerized from polymer-cured polyurethane and vinyl compound has high hardness and flatness during polishing It is preferable in terms of good crystallization characteristics.

  The average cell diameter of the polishing layer is not particularly limited, but is preferably 20 to 300 μm. If it is less than 20 μm, the polishing rate during polishing tends to be reduced, or scratches and dust tend to be generated on the surface of the semiconductor substrate after polishing. If it exceeds 300 μm, the rigidity of the polishing layer decreases, resulting in flattening characteristics. This is not preferable because the polishing characteristics such as the above deteriorate or the life of the polishing pad using the polishing layer tends to be shortened. The average cell diameter is more preferably 30 to 250 μm. The average bubble diameter refers to a value measured by observing the cross section of the polishing layer with a SEM at a magnification of 200 times, then measuring the bubble diameter of the recorded SEM photograph with an image processing apparatus, and taking the average value.

The density of the polishing layer is not particularly limited, but is preferably 0.5 to 1.0 g / cm ³ . If it is lower than 0.5 g / cm ^3, the flattening characteristics at the time of polishing will tend to deteriorate, and if it is higher than 1.0 g / cm ³ , the in-plane uniformity at the time of polishing will be deteriorated or polished. Since there is a tendency that scratches and dust are likely to be generated on the surface of the subsequent semiconductor substrate, it is not so preferable. More preferably, it is 0.6 to 0.9 g / cm ³ . The density means a value measured by the method described in Japanese Industrial Standard (JIS) K7222.

  The thickness of the polishing layer is not particularly limited, but is preferably 0.1 to 10 mm. When the thickness is less than 0.1 mm, the mechanical properties of the cushion layer preferably used as the underlayer of the polishing layer or the polishing surface plate located under the cushion layer are more significantly reflected in the polishing properties than the mechanical properties of the polishing layer itself. On the other hand, if it is thicker than 10 mm, the mechanical characteristics of the cushion layer are not reflected, the followability to the undulation of the semiconductor substrate is lowered, and the flatness over the entire semiconductor substrate cannot be performed uniformly. More preferably, it is 0.2 to 5.0 mm, and more preferably 0.5 to 2.0 mm.

  The surface of the polishing layer in the present invention is preferably subjected to processing such as grooves and holes for the purpose of improving the retention and fluidity of the polishing slurry and improving the removal efficiency of polishing debris from the polishing layer surface. The method for forming grooves and holes on the surface of the polishing layer is not particularly limited. Specifically, the method of forming grooves by cutting the surface of the polishing layer using a device such as a router, the heated layer surface is contacted with a heated mold, heat rays, etc., and the contact portion is dissolved. The method of forming a groove | channel by the method, The method of forming the grinding | polishing layer which formed the groove | channel from the beginning using the metal mold | die etc. in which the groove | channel was formed, the method of forming a hole with a drill, a Thomson blade, etc. are mentioned. Further, the shape and diameter of the groove and hole are not particularly limited. Specific examples include a grid shape, a dimple shape, a spiral shape, and a concentric shape.

  Next, a polishing method using the polishing pad of the present invention will be described.

  The polishing apparatus is not particularly limited, but when used for polishing a semiconductor substrate, the polishing head, the polishing surface plate for fixing the polishing pad of the present invention, and the polishing head, the polishing surface plate or both. It is preferable to have a means for rotating.

  As a polishing method, first, the polishing pad of the present invention is fixed to a polishing surface plate of a polishing apparatus so that the polishing layer faces the polishing head. The semiconductor substrate is fixed to the polishing head by a method such as water adsorption or vacuum adsorption. The polishing surface plate is rotated, the polishing head is rotated in the same direction as the rotation direction of the polishing surface plate, and pressed against the polishing pad. At this time, the polishing slurry is supplied from a position where the polishing slurry enters between the polishing pad and the semiconductor substrate. The pressing pressure is usually performed by controlling the force applied to the polishing head.

  In the method for polishing a semiconductor substrate using the polishing pad of the present invention, dressing for roughening the surface of the polishing layer using a diamond disk is preferably performed to obtain good polishing characteristics before polishing the semiconductor substrate. The The dressing can be preferably carried out for either batch dressing in which a conditioner is used to condition a polishing pad after the completion of one or more polishings, and in situ dressing in which dressing is performed simultaneously with polishing. . In the present invention, the time until the polishing characteristics are stabilized, that is, the start-up time can be shortened, and the initial dressing can be shortened, so that the usable time of the polishing pad can be extended.

  The polishing object of the polishing pad in the present invention is not particularly limited. Specific examples include semiconductor substrates, optical glass, optical lenses, magnetic heads, hard disks, color filters for liquid crystal displays, optical members such as a back plate for plasma displays, ceramics, sapphire, and the like. Among these, application to a semiconductor substrate is particularly preferable. Furthermore, the surface of the wiring made of an insulating layer, metal and / or metal compound provided on a semiconductor wafer, which requires very precise polishing characteristics, is also preferable as the object to be polished.

  Specifically, the insulating layer includes an interlayer insulating film or lower insulating film of metal wiring, shallow trench isolation (STI) used for element isolation, and the metal wiring includes aluminum, tungsten, copper, and the like. Structurally, there are damascene, dual damascene, plug, etc. Currently, silicon dioxide is mainly used as the insulating film, but due to the problem of delay time, the use of a low dielectric constant insulating film is being studied, and any of them can be polished in the polishing method of the present invention. In addition, when copper is used for the metal wiring, a barrier metal such as silicon nitride is also subject to polishing. Among these, it can apply preferably, when a to-be-polished object is the metal and / or metal compound which were provided on the semiconductor substrate.

  According to the present invention, a polishing pad that can be used in a process of planarizing a semiconductor substrate, a surface of an insulating layer formed on the semiconductor substrate or a surface of a metal wiring, and a polishing method using the same can be stabilized. It is possible to provide a polishing pad that has high performance and can shorten the start-up time during use, and a polishing method using the same.

  Hereinafter, the details of the present invention will be described with reference to examples. Various evaluations of the polishing pad were performed as follows.

  The micro rubber A hardness of the polishing layer and the cushion layer was measured with a micro rubber A hardness meter “MD-1” (manufactured by Kobunshi Keiki Co., Ltd.).

  The density of the polishing layer was measured by the method described in JIS K7222.

  The average bubble diameter of the polishing layer was determined by analyzing a photograph obtained by observing the pad cross section at a magnification of 200 times with an image processing apparatus using a scanning electron microscope “SEM2400” (manufactured by Hitachi, Ltd.). All the bubble diameters present were measured, and the average value was taken as the average bubble diameter.

  The water absorption rate of the polishing pad was determined from the difference between the weight of the polishing pad immediately after unpacking and the weight of the polishing pad after air drying until there was no change in weight at a temperature of 23 ° C. and a humidity of 50%. .

Water absorption rate = (weight of polishing pad immediately after unpacking−weight of polishing pad after air drying) / (weight of polishing pad after air drying) × 100
The moisture adhering to the polishing pad surface immediately after unpacking was wiped off and then air-dried.

  Polishing evaluation was performed as follows. The prepared polishing pad is attached to a polishing machine ("MIRRA (registered trademark)" manufactured by Applied Materials), and a wafer with an oxide film while polishing slurry "SS-25" (manufactured by Cabot Co., Ltd.) diluted to 2 times flows at 150 mm / min. The time until the polishing rate and in-plane uniformity were stabilized was defined as the polishing start-up time. Next, 300 wafers with oxide films were polished continuously. The polishing results of the monitor wafers (the rest are dummy wafers) placed every 50 wafers were used as the evaluation results of the polishing characteristics, and the average values for the polishing rate and the in-plane uniformity were obtained.

  The polishing rate and in-plane uniformity of the polished wafer were determined as follows. 198 points determined using “Lambda Ace (registered trademark)” VM-2000 (Dainippon Screen Mfg. Co., Ltd.) were measured, and the polishing rate at each point was calculated by the following equation (1). Moreover, the in-plane uniformity was calculated by the following equation (2).

  Polishing rate = (thickness of oxide film before polishing−thickness of oxide film after polishing) / polishing time (1).

  In-plane uniformity (%) = (maximum polishing rate−minimum polishing rate) / (maximum polishing rate + minimum polishing rate) × 100 (2).

The flattening property is the accuracy that shows how close the surface is to the flatness by reducing the unevenness (initial step) present in the device pattern on the substrate surface by polishing the step. That is, when the step after the planarization polishing is the residual step,
Flattening characteristic = (initial step−residual step) / initial step can be defined.

Example 1
Polyether polyol maintained at a liquid temperature of 40 ° C .: “Sanix (registered trademark) FA-909” (manufactured by Sanyo Chemical Industries, Ltd.) 100 parts by weight, chain extender: 8 parts by weight of ethylene glycol, amine catalyst: 1 part by weight of “Dabco (registered trademark) 33LV” (produced by Air Products Japan), amine catalyst: 0.1 part by weight of “Toyocat (registered trademark) ET” (produced by Tosoh Corporation), silicone foam stabilizer: "TEGOSTAB (registered trademark) B8462" (manufactured by Th. Goldschmidt AG) 0.5 part by weight, foaming agent: A liquid obtained by mixing 0.2 part by weight of water, and isocyanate maintaining the liquid temperature at 40 ° C: "Sunform (registered trademark) NC-703" 95 parts by weight of B liquid was collided with a RIM molding machine at a discharge pressure of 15 MPa, and then kept at 60 ° C. Discharging a discharge rate 500 g / sec within, by standing for 10 minutes, size 700 × 700 mm, foamed polyurethane block thickness 10 mm (micro rubber A hardness: 47 degrees, a density: 0.77 g / cm ^3, average cell Diameter: 37 μm). Thereafter, the foamed polyurethane block was sliced with a slicer to a thickness of 3 mm.

Next, the foamed polyurethane sheet was immersed in methyl methacrylate to which 0.1 part by weight of azobisisobutyronitrile was added for 45 minutes. Next, the foamed polyurethane sheet impregnated with methyl methacrylate was sandwiched between two glass plates via a vinyl chloride gasket, and polymerized and cured by heating at 60 ° C. for 10 hours and at 120 ° C. for 3 hours. After releasing from between the glass plates, vacuum drying was performed at 50 ° C. A polishing layer was prepared by grinding both surfaces of the hard foam sheet thus obtained to a thickness of 2.0 mm. The obtained polishing layer had a micro rubber A hardness of 91 degrees, a density of 0.76 g / cm ³ , an average cell diameter of 48 μm, and a polymethyl methacrylate content of 55% by weight in the polishing layer. The polishing layer was cut into a circle having a diameter of 508 mm, and a lattice-shaped groove with a width of 1 mm, a depth of 0.8 mm, and a pitch width of 25 mm was formed on the surface.

  Next, a double-sided adhesive tape “442JS” (manufactured by Sumitomo 3M Co., Ltd.) was bonded to the polishing layer at a linear pressure of 1 kg / cm using a laminator, and then the release paper was peeled off, and the thermoplastic urethane rubber having a thickness of 1 mm was removed. A laminator was used on a cushion layer made of a sheet (micro rubber A hardness: 69 degrees) and bonded at a linear pressure of 1 kg / cm. Furthermore, double-sided adhesive tape “442JS” (manufactured by Sumitomo 3M Co., Ltd.) was bonded under the cushion layer at a linear pressure of 1 kg / cm using a laminator.

  The two polishing pads produced in this manner were put together with a sufficient amount of water into which the polishing pad can be immersed, one by one (material (thickness): from the outer layer, aluminum oxide-deposited polyethylene terephthalate (12 μm) / polyamide (15 μm). ) / Polyethylene (60 μm)), sealed with a heat sealer, and allowed to stand in a room at 23 ° C. for 1 week.

  Thereafter, the water absorption of one of the polishing pads was measured and found to be 9%.

  Next, another polishing pad was taken out and mounted on a polishing apparatus, and then polishing evaluation was performed at a polishing pressure of 4 psi. The time required for starting up the polishing pad was 10 minutes. The polishing rate was 2280 angstroms / minute, and the in-plane uniformity was 10.7%.

Example 2
Two polishing pads produced in the same manner as in Example 1 were allowed to stand in a thermo-hygrostat set to a temperature of 40 ° C. and a relative humidity of 100% for one week, and then the polishing pads were taken out one by one. (Thickness): The outer layer was put into aluminum oxide-deposited polyethylene terephthalate (12 μm) / polyamide (15 μm) / polyethylene (60 μm)), vacuum-sealed with a vacuum heat sealer, and allowed to stand in a room at 23 ° C. for 1 week.

  Thereafter, the water absorption of one of the polishing pads was measured and found to be 7%.

  Next, another polishing pad was taken out and mounted on a polishing apparatus, and then polishing evaluation was performed at a polishing pressure of 4 psi. The time required for starting up the polishing pad was 15 minutes. The polishing rate was 2290 angstroms / minute, and the in-plane uniformity was 11.0%.

Example 3
Two polishing pads prepared in the same manner as in Example 1 together with a polishing slurry “SS-25” (manufactured by Cabot Corp.) diluted with water in an amount sufficient to allow the polishing pad to be immersed one by one. Bag (material (thickness): put into aluminum oxide-deposited polyethylene terephthalate (12 μm) / polyamide (15 μm) / polyethylene (60 μm)) from the outer layer, sealed with a heat sealer, and left in a room at 23 ° C. for 1 week.

    Thereafter, the water absorption of one of the polishing pads was measured and found to be 10%.

  Next, another polishing pad was taken out and mounted on a polishing apparatus, and then polishing evaluation was performed at a polishing pressure of 4 psi. The time required for starting up the polishing pad was 10 minutes. The polishing rate was 2310 angstrom / min, and the in-plane uniformity was 10.3%.

Comparative Example 1
A polishing pad was prepared and polished for evaluation in the same manner as in Example 1 except that the polishing pad was not sealed with water. The time required for starting up the polishing pad was 40 minutes. The polishing rate was 2270 angstroms / minute, and the in-plane uniformity was 10.9%.

Comparative Example 2
A polishing pad was prepared and polished for evaluation in the same manner as in Example 2 except that the polishing pad was not sealed with water. The time required for starting up the polishing pad was 40 minutes. The polishing rate was 2310 angstrom / min, and the in-plane uniformity was 11.1%.

Comparative Example 3
A polishing pad was prepared and polished for evaluation in the same manner as in Example 3 except that the polishing pad was not sealed with water. The time required for starting up the polishing pad was 40 minutes. The polishing rate was 2290 angstroms / minute, and the in-plane uniformity was 11.3%.

Claims (8)

A polishing pad, wherein a polishing pad having at least a polishing layer is sealed in a wet state with water. The polishing pad according to claim 1, wherein the polishing pad having at least a polishing layer is sealed in a state immersed in water. The polishing pad according to claim 1, wherein a polishing slurry component is added to water. Furthermore, the polishing pad in any one of Claims 1-3 in which the cushion layer is laminated | stacked. The polishing pad according to claim 1, wherein the cushion layer has a foam structure. The polishing pad according to any one of claims 1 to 5, wherein the polishing layer contains a polymer polymerized from polyurethane and a vinyl compound. The polishing pad according to claim 1, wherein the polishing pad is for polishing a semiconductor substrate. An object to be polished is fixed to a polishing head, and the polishing head and / or the polishing surface plate is rotated in a state where the polishing pad according to claim 1 is in contact with the object to be polished. A polishing method comprising polishing at least.