JP2007229811A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad capable of preventing slurry leakage between a polishing area and a light-transmitting area when it is used for a long time, a manufacturing method thereof, and a semiconductor device using the polishing pad. <P>SOLUTION: This polishing pad includes a polishing layer 11 having a polishing area 9 and a light-transmitting area 8. In this pad, the polishing area is fused to the light-transmitting area via a laser processing part 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polishing pad used when planarizing unevenness on a wafer surface by chemical mechanical polishing (CMP), and more specifically, a window (light transmission region) for detecting a polishing state or the like by optical means. The present invention relates to a polishing pad having the same, a method for manufacturing the same, and a method for manufacturing a semiconductor device using the polishing pad.

  When manufacturing a semiconductor device, a process of forming a conductive layer on the wafer surface and forming a wiring layer by photolithography, etching, or the like, a process of forming an interlayer insulating film on the wiring layer, etc. These steps are performed, and irregularities made of a conductor such as metal or an insulator are generated on the wafer surface. In recent years, miniaturization of wiring and multilayer wiring have been advanced for the purpose of increasing the density of semiconductor integrated circuits, and along with this, technology for flattening the irregularities on the wafer surface has become important.

  As a method for flattening the irregularities on the wafer surface, a CMP method is generally employed. CMP is a technique of polishing using a slurry-like abrasive (hereinafter referred to as slurry) in which abrasive grains are dispersed in a state where the surface to be polished of a wafer is pressed against the polishing surface of a polishing pad.

  As shown in FIG. 1, for example, a polishing apparatus generally used in CMP includes a polishing surface plate 2 that supports a polishing pad 1 and a support base (polishing head) 5 that supports an object to be polished (wafer) 4. And a backing material for uniformly pressing the wafer, and an abrasive supply mechanism. The polishing pad 1 is attached to the polishing surface plate 2 by attaching it with a double-sided tape, for example. The polishing surface plate 2 and the support base 5 are disposed so that the polishing pad 1 and the object to be polished 4 supported on each of the polishing surface plate 2 and the support base 5 are opposed to each other, and are provided with rotating shafts 6 and 7 respectively. The support 5 is provided with a pressurizing mechanism for pressing the object 4 to be polished against the polishing pad 1.

  When performing such CMP, there is a problem of determining the flatness of the wafer surface. In other words, it is necessary to detect when the desired surface characteristics or planar state is reached. Conventionally, with regard to the thickness of the oxide film, the polishing rate, and the like, a test wafer is periodically processed, and after confirming the result, a product wafer is polished.

  However, in this method, the time and cost for processing the test wafer are wasted, and the polishing result differs between the test wafer and the product wafer that have not been processed in advance due to the loading effect peculiar to CMP. If it is not actually processed, it is difficult to accurately predict the processing result.

  Therefore, recently, in order to solve the above-mentioned problems, there is a demand for a method capable of detecting a point in time when desired surface characteristics and thickness are obtained in the CMP process. Various methods are used for such detection. From the viewpoint of measurement accuracy and spatial resolution in non-contact measurement, an optical detection method in which a film thickness monitoring mechanism using a laser beam is incorporated in a rotating surface plate ( Patent Documents 1 and 2) are becoming mainstream.

  Specifically, the optical detection means detects a polishing end point by irradiating a wafer with a light beam through a window (light transmission region) through a polishing pad and monitoring an interference signal generated by the reflection. Is the method.

  In such a method, the end point is determined by monitoring the change in the thickness of the surface layer of the wafer and knowing the approximate depth of the surface irregularities. When such a change in thickness becomes equal to the depth of the unevenness, the CMP process is terminated. Various methods have been proposed for the polishing end point detection method using such optical means and the polishing pad used in the method.

  For example, a polishing pad having at least a part of a transparent polymer sheet that transmits solid and homogeneous light having a wavelength of 190 nm to 3500 nm is disclosed (Patent Document 3). Further, a polishing pad in which a stepped transparent plug is inserted is disclosed (Patent Document 4). Also, a polishing pad having a transparent plug that is the same surface as the polishing surface is disclosed (Patent Document 5). However, the polishing pad in which the transparent plug is inserted has a problem that the polishing characteristics such as in-plane uniformity of the wafer are deteriorated as compared with the polishing pad in which the transparent plug is not provided.

  On the other hand, proposals (Patent Documents 6 and 7) have been made to prevent the slurry from leaking from the boundary (seam) between the polishing region and the light transmission region. However, even when these transparent leakage prevention sheets are provided, the slurry leaks from the boundary (seam) between the polishing region and the light transmission region to the lower part of the polishing layer, and the slurry accumulates on the leakage prevention sheet to cause an optical end point. Problems with detection.

  In the future, with high integration and ultra-miniaturization in semiconductor manufacturing, it is expected that the wiring width of integrated circuits will become smaller, and in that case, highly accurate optical end point detection will be required. The end point detection window cannot sufficiently solve the problem of slurry leakage.

US Pat. No. 5,069,002 US Pat. No. 5,081,421 Japanese National Patent Publication No. 11-512977 Japanese Patent Laid-Open No. 9-7985 Japanese Patent Laid-Open No. 10-83977 JP 2001-291686 A Japanese translation of PCT publication No. 2003-510826

  The present invention relates to a polishing pad capable of preventing slurry leakage from between a polishing region and a light transmission region even when used for a long period of time, a method for manufacturing the same, and manufacturing a semiconductor device using the polishing pad. It aims to provide a method.

  In light of the above-described present situation, the present inventor has found that the above-described problems can be solved by providing a water-impermeable elastic member in the gap between the polishing region and the light transmission region as a result of extensive research.

  The polishing pad of the present invention is characterized in that in the polishing pad including a polishing layer having a polishing region and a light transmission region, the polishing region and the light transmission region are welded via a laser processing portion.

  A conventional polishing pad in which a light transmission region is inserted is fitted so that a gap is not generated as much as possible in the opening of the polishing region in order to prevent slurry leakage. However, in CMP, a polishing pad and an object to be polished such as a wafer rotate and revolve together, and polishing is performed by friction under pressure. During polishing, various forces (particularly in the horizontal direction) are acting on the light transmission region and the polishing region, so that a peeling state always occurs at the boundary between both members. It is considered that the conventional polishing pad is easily peeled off at the boundary between the two members, and a gap is generated at the boundary to cause slurry leakage. This slurry leakage is considered to cause optical problems such as fogging in the light end point detection unit, thereby reducing or disabling the end point detection accuracy.

  On the other hand, in the polishing pad of the present invention, since the polishing region and the light transmission region are welded and integrated through the laser processing portion, a force to peel off the light transmission region and the polishing region is applied during polishing. But it has enough resistance to withstand it. Therefore, a gap or peeling hardly occurs at the interface between the polishing region and the light transmission region, and slurry leakage can be effectively prevented.

  The present invention includes a step of providing a light transmission region in the opening A of a polishing layer having a polishing region and an opening A, and irradiating the interface between the polishing region and the light transmission region with laser light to melt the polishing region. The present invention relates to a method for manufacturing a polishing pad, which includes a step of forming a laser processed portion and welding a polishing region and a light transmission region through the laser processing portion.

  In another aspect of the present invention, a polishing layer having a polishing region and a light transmission region, and a cushion layer having an opening B smaller than the light transmission region are laminated so that the light transmission region and the opening B overlap. In addition, the present invention relates to a polishing pad in which a peripheral end portion of the light transmission region and the cushion layer are welded via a laser processing portion.

  In another polishing pad of the present invention, since the peripheral end portion of the light transmission region and the cushion layer are integrated by welding through the laser processing portion, the slurry is removed from the gap between the light transmission region and the polishing region during polishing. Even if the liquid enters, slurry leakage can be effectively prevented at the welded portion.

  The present invention also includes a step of laminating a cushion layer on a polishing layer having a polishing region and an opening A, removing a part of the cushion layer in the opening A, and opening the cushion layer smaller than the light transmission region. A step of forming a portion B, a step of providing a light transmission region on the opening B and in the opening A, and a cushion layer or an adhesive member that is in contact with the peripheral end portion of the light transmission region by irradiation with laser light The present invention relates to a method of manufacturing a polishing pad, which includes a step of melting a layer to form a laser processing portion and welding a peripheral end portion of a light transmission region and a cushion layer through the laser processing portion.

  The present invention also includes a step of laminating a polishing layer having a polishing region and an opening A, and a cushion layer having an opening B smaller than the light transmission region so that the opening A and the opening B overlap. A step of providing a light transmitting region on the opening B and in the opening A, and a laser processing unit by irradiating a laser beam to melt a cushion layer or an adhesive member that is in contact with the peripheral end of the light transmitting region And a method of manufacturing a polishing pad including a step of welding a peripheral end portion of a light transmission region and a cushion layer through the laser processing portion.

  The present invention also relates to a method for manufacturing a semiconductor device including a step of polishing a surface of a semiconductor wafer using the polishing pad described above.

  The polishing pad of the present invention includes a polishing layer having a polishing region and a light transmission region, and the polishing region and the light transmission region are welded via a laser processing portion.

  In another polishing pad of the present invention, a polishing layer having a polishing region and a light transmission region, and a cushion layer having an opening B smaller than the light transmission region, the light transmission region and the opening B are It is laminated so that it may overlap, and the peripheral edge part of the above-mentioned light transmission field and the above-mentioned cushion layer are welded via a laser processing part.

  The material for forming the light transmission region is not particularly limited, but it is preferable to use a material having a light transmittance of 50% or more in the entire region having a wavelength of 400 to 700 nm for highly accurate optical end point detection. Moreover, it is preferable that it is a material which permeate | transmits the laser beam to be used sufficiently. Examples of such materials include polyurethane resins, polyester resins, polyamide resins, acrylic resins, polycarbonate resins, halogen resins (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resins (polyethylene). And polypropylene), and epoxy resins. These may be used alone or in combination of two or more. It is preferable to use a material similar to the forming material used for the polishing region and the physical properties of the polishing region. In particular, a highly abrasion-resistant polyurethane resin that can suppress light scattering in the light transmission region due to dressing marks during polishing is desirable.

  The polyurethane resin is composed of an isocyanate component, a polyol component (high molecular weight polyol, low molecular weight polyol, etc.), a chain extender and the like.

  As the isocyanate component, a known compound in the field of polyurethane can be used without particular limitation. As the isocyanate component, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate; ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, etc. Aliphatic diisocyanate; 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate Isocyanate, alicyclic diisocyanates such as norbornane diisocyanate. These may be used alone or in combination of two or more.

  As the isocyanate component, a trifunctional or higher polyfunctional polyisocyanate compound can be used in addition to the diisocyanate compound. As a polyfunctional isocyanate compound, a series of diisocyanate adduct compounds are commercially available as Desmodur-N (manufactured by Bayer) or trade name Duranate (manufactured by Asahi Kasei Kogyo Co., Ltd.).

  Examples of the high molecular weight polyol include polyether polyols typified by polytetramethylene ether glycol, polyester polyols typified by polybutylene adipate, polycaprolactone polyol, and a reaction product of a polyester glycol such as polycaprolactone and alkylene carbonate. Polyester polycarbonate polyol, polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the resulting reaction mixture with organic dicarboxylic acid, and polycarbonate polyol obtained by transesterification reaction between polyhydroxyl compound and aryl carbonate Etc. These may be used alone or in combination of two or more.

  In addition to the high molecular weight polyols described above as polyols, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1, Low molecular weight polyols such as 4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and 1,4-bis (2-hydroxyethoxy) benzene may be used in combination.

  Chain extenders include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3 -Low molecular weight polyols such as methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, 2,4-toluenediamine, 2,6-toluenediamine, 3 , 5-diethyl-2,4-toluenediamine, 4,4′-di-sec-butyl-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2, , 2 ′, 3,3′-tetrachloro-4,4′-diaminodi Phenylmethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, 4,4′-methylene-bis-methylanthrani 4,4′-methylene-bis-anthranilic acid, 4,4′-diaminodiphenylsulfone, N, N′-di-sec-butyl-p-phenylenediamine, 4,4′-methylene-bis (3 -Chloro-2,6-diethylamine), 3,3'-dichloro-4,4'-diamino-5,5'-diethyldiphenylmethane, 1,2-bis (2-aminophenylthio) ethane, trimethylene glycol di -Polyamines exemplified by p-aminobenzoate, 3,5-bis (methylthio) -2,4-toluenediamine be able to. These may be used alone or in combination of two or more.

  The ratio of the isocyanate component, the polyol component, and the chain extender in the polyurethane resin can be appropriately changed depending on the molecular weight of each and the desired physical properties of the light transmission region produced therefrom.

  The polyurethane resin can be manufactured by applying a known urethanization technique such as a melting method or a solution method, but it is preferable to manufacture the polyurethane resin by a melting method in consideration of cost, working environment, and the like.

  As the polymerization procedure of the polyurethane resin, either a prepolymer method or a one-shot method is possible, but from the viewpoint of stability and transparency of the polyurethane resin at the time of polishing, an isocyanate-terminated prepolymer is first prepared from an isocyanate component and a polyol component. A prepolymer method is preferred in which a polymer is synthesized and a chain extender is reacted therewith. Moreover, it is preferable that the NCO weight% of the said prepolymer is about 2 to 8 weight%, More preferably, it is about 3 to 7 weight%. If the NCO wt% is less than 2 wt%, the reaction curing tends to take too much time and the productivity tends to decrease. On the other hand, if the NCO wt% exceeds 8 wt%, the reaction rate becomes too fast. As a result, air entrainment or the like occurs, and physical properties such as transparency and light transmittance of the polyurethane resin tend to deteriorate.

  The method for producing the light transmission region is not particularly limited, and can be produced by a known method. For example, a polyurethane resin block produced by the above method can be made to have a predetermined thickness using a band saw type or canna type slicer, a method of pouring the resin into a mold having a cavity of a predetermined thickness, a coating technique, A method using a sheet forming technique is used.

  The shape of the light transmission region is not particularly limited, but is preferably the same shape and size as the opening A of the polishing region.

  The thickness of the light transmission region is not particularly limited, but is preferably equal to or less than the thickness of the polishing region. If the light transmission region is thicker than the polishing region, the wafer may be damaged by the protruding portion during polishing.

  The material for forming the polishing region can be used without particular limitation as long as it is normally used as the material for the polishing layer, but in the present invention, it is preferable to use a fine foam. For example, polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resin (polyethylene, polypropylene, etc.), epoxy resin And photosensitive resin. These may be used alone or in combination of two or more. The material for forming the polishing region may be the same composition as or different from the light transmission region.

  Polyurethane resin is particularly preferable as a material for forming a polishing region because it has excellent wear resistance and a polymer having desired physical properties can be easily obtained by variously changing the raw material composition. The polyurethane resin is composed of an isocyanate component, a polyol component, and a chain extender.

  The isocyanate component to be used is not particularly limited, and examples thereof include the above isocyanates.

  The polyol component to be used is not particularly limited, and examples thereof include the high molecular weight polyols described above. The number average molecular weight of the high molecular weight polyol is not particularly limited, but is preferably 500 to 2000 from the viewpoint of the elastic properties of the resulting polyurethane. If the number average molecular weight is less than 500, a polyurethane using the number average molecular weight does not have sufficient elastic properties and becomes a brittle polymer. Therefore, the polishing pad manufactured from this polyurethane becomes too hard and causes scratches on the polishing surface of the object to be polished. Moreover, since it becomes easy to wear, it is not preferable from the viewpoint of the pad life. On the other hand, when the number average molecular weight exceeds 2000, polyurethane using the same becomes soft, so that a polishing pad produced from this polyurethane tends to have poor planarization characteristics.

  Moreover, as a polyol component, in addition to the above-described high molecular weight polyol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene and other low molecular weight polyols can be used in combination.

  Further, the ratio of the high molecular weight polyol to the low molecular weight polyol in the polyol component is determined by the characteristics required for the polishing region produced therefrom.

  Examples of chain extenders include polyamines exemplified by 4,4′-methylenebis (o-chloroaniline), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline) and the like. Or the low molecular weight polyols mentioned above. These may be used alone or in combination of two or more.

  The ratio of the organic isocyanate, polyol, and chain extender in the polyurethane resin can be variously changed depending on the molecular weight of each and the desired physical properties of the polishing region produced therefrom. In order to obtain a polishing region having excellent polishing characteristics, the number of isocyanate groups of the organic isocyanate relative to the total number of functional groups (hydroxyl group + amino group) of the polyol and the chain extender is preferably 0.95 to 1.15, and more preferably Is 0.99 to 1.10.

  The polyurethane resin can be produced by the same method as described above. If necessary, stabilizers such as antioxidants, surfactants, lubricants, pigments, fillers, antistatic agents, and other additives may be added to the polyurethane resin.

  The method of finely foaming the polyurethane resin is not particularly limited, and examples thereof include a method of adding hollow beads, a method of foaming by a mechanical foaming method, a chemical foaming method, and the like. In addition, although each method may be used together, the mechanical foaming method using the silicone type surfactant which is a copolymer of polyalkylsiloxane and polyether and does not have an active hydrogen group is particularly preferable. Examples of the silicon-based surfactant include SH-192 (manufactured by Toray Dow Corning Silicone), L-5340 (manufactured by Nippon Unica), and the like.

An example of a method for producing a closed cell type polyurethane foam used in the polishing region will be described below. The manufacturing method of this polyurethane foam has the following processes.
1) Stirring step for producing a cell dispersion of isocyanate-terminated prepolymer A silicon-based surfactant is added to the isocyanate-terminated prepolymer and stirred with a non-reactive gas to disperse the non-reactive gas as fine bubbles, thereby dispersing the cell. Use liquid. When the isocyanate-terminated prepolymer is solid at room temperature, it is preheated to an appropriate temperature and melted before use.
2) Curing Agent (Chain Extender) Mixing Step A chain extender is added to the above cell dispersion and mixed and stirred.
3) Curing step An isocyanate-terminated prepolymer mixed with a chain extender is cast and cured by heating.

  As the non-reactive gas used to form the fine bubbles, non-flammable gases are preferable, and specific examples include nitrogen, oxygen, carbon dioxide, rare gases such as helium and argon, and mixed gases thereof. The use of air that has been dried to remove moisture is most preferable in terms of cost.

  As a stirring device for making non-reactive gas into fine bubbles and dispersing it in an isocyanate-terminated prepolymer containing a silicon-based surfactant, a known stirring device can be used without particular limitation. Specifically, a homogenizer, a dissolver, A two-axis planetary mixer (planetary mixer) is exemplified. The shape of the stirring blade of the stirring device is not particularly limited, but it is preferable to use a whipper-type stirring blade because fine bubbles can be obtained.

  In addition, it is also a preferable aspect to use a different stirring apparatus for the stirring which produces a bubble dispersion liquid in the stirring process, and the stirring which adds and mixes the chain extender in a mixing process. In particular, the stirring in the mixing step may not be stirring that forms bubbles, and it is preferable to use a stirring device that does not involve large bubbles. As such an agitator, a planetary mixer is suitable. There is no problem even if the same stirring device is used as the stirring device for the stirring step and the mixing step, and it is also preferable to adjust the stirring conditions such as adjusting the rotation speed of the stirring blade as necessary. .

  In the method for producing the polyurethane fine foam, heating and post-curing the foam that has reacted until the foam dispersion does not flow by pouring the cell dispersion into the mold has the effect of improving the physical properties of the foam, Very suitable. The bubble dispersion may be poured into the mold and immediately placed in a heating oven for post-cure. Under such conditions, heat is not immediately transferred to the reaction components, so the bubble diameter does not increase. . The curing reaction is preferably performed at normal pressure because the bubble shape is stable.

  In the production of the polyurethane resin, a catalyst that promotes a known polyurethane reaction such as tertiary amine or organotin may be used. The type and addition amount of the catalyst are selected in consideration of the flow time for pouring into a mold having a predetermined shape after the mixing step.

  The polyurethane foam can be produced in a batch system in which each component is weighed into a container and stirred. Alternatively, each component and a non-reactive gas are continuously supplied to a stirrer and stirred to produce bubbles. It may be a continuous production method in which a dispersion is sent out to produce a molded product.

  The polishing area to be the polishing layer is manufactured by cutting the polyurethane foam prepared as described above into a predetermined size.

  It is preferable that the polishing area | region which consists of a fine foam is provided with the groove | channel for hold | maintaining and renewing a slurry in the grinding | polishing side surface which contacts a to-be-polished object. Since the polishing region is formed of a fine foam, it has a large number of openings on the polishing surface and has a function of holding the slurry. However, in order to efficiently further maintain the slurry and renew the slurry. In order to prevent destruction of the object to be polished due to adsorption with the object to be polished, it is preferable to have a groove on the surface on the polishing side. The groove is not particularly limited as long as it is a surface shape that holds and renews the slurry. For example, XY lattice grooves, concentric circular grooves, through holes, non-through holes, polygonal columns, cylinders, spiral grooves, Examples include eccentric circular grooves, radial grooves, and combinations of these grooves. Further, the groove pitch, groove width, groove depth and the like are not particularly limited and are appropriately selected and formed. In addition, these grooves are generally regular, but the groove pitch, groove width, groove depth, etc. may be changed for each range to make the slurry retention and renewability desirable. Is possible.

  The method of forming the groove is not particularly limited. For example, a method of machine cutting using a jig such as a tool of a predetermined size, a method of pouring and curing a resin in a mold having a predetermined surface shape , A method of pressing a resin with a press plate having a predetermined surface shape, a method of forming using photolithography, a method of forming using a printing technique, and a laser beam using a carbon dioxide gas laser, etc. The method of doing is mentioned.

  Although the thickness of a grinding | polishing area | region is not specifically limited, It is about 0.8-2.0 mm. As a method of producing the polishing region of the thickness, a method of making the block of the fine foam a predetermined thickness using a band saw type or a canna type slicer, pouring resin into a mold having a cavity of a predetermined thickness, and curing And a method using a coating technique or a sheet forming technique.

  The manufacturing method of the polishing pad of the present invention is not particularly limited, and various methods can be considered. Specific examples will be described below.

  FIG. 2 is a schematic configuration diagram showing an example of the polishing pad of the present invention.

  First, the light transmission region 8 is fitted into the opening A of the polishing layer 11 having the polishing region 9 and the opening A (10). After that, the laser beam 12 is irradiated from the polishing surface side and / or the polishing back surface side to the interface between the polishing region and the light transmission region to melt the polishing region at the interface to form the laser processing part 13, The polishing region and the light transmission region are welded to each other.

  In the manufacturing method of the polishing pad, means for opening the polishing region is not particularly limited. For example, a method of pressing and opening a jig having a cutting ability, or cutting using a laser such as a carbonic acid laser. And a method of grinding with a jig such as a tool. The size and shape of the opening A are not particularly limited.

  The laser used for forming the laser processed portion is not particularly limited as long as it can melt the polishing region and can weld the polishing region and the light transmitting region through the laser processing portion. In addition, a laser that can be thermally processed by absorbing ultraviolet light and emitting ultraviolet light, a laser that can be thermally processed by absorbing infrared light and emitting infrared light, and the like can be given. Specific examples include a KrF excimer laser having an oscillation wavelength of 248 nm, a fourth harmonic of a YAG laser (wavelength 266 nm), and a fundamental wave of a YAG laser (wavelength 1064 nm).

  The irradiation conditions of the laser beam are not particularly limited, but it is preferable that the laser output is 0.1 to 50 W, the scanning speed is 10 to 200 mm / sec, and the spot diameter is 0.1 to 3 mm.

  The laser processing part needs to be provided around the entire light transmission region from the viewpoint of completely preventing slurry leakage. The laser processing portion may be provided on any of the polishing surface side, the polishing back surface side, or both surfaces, but it is preferable to provide the laser processing portion on the polishing back surface side so as not to affect the polishing.

  The obtained polishing layer may be used alone as a polishing pad, or a cushioning layer may be bonded to the polishing back surface side of the polishing layer to form a laminated type polishing pad. The cushion layer is provided with an opening in accordance with the position of the light transmission region. The means for opening the cushion layer is the same as described above.

  FIG. 3 is a schematic configuration diagram showing an example of another polishing pad of the present invention.

  As a first specific example, a cushion layer 14 is first bonded to a polishing layer 11 having a polishing region 9 and an opening A (10) for providing a light transmission region 8. Next, a part of the cushion layer in the opening A is removed, and an opening B (15) smaller than the light transmission region is formed in the cushion layer. Next, the light transmission region 8 is fitted on the opening B and in the opening A. Then, the laser beam 12 is irradiated from the polishing surface side to melt the cushion layer or the adhesive member that is in contact with the peripheral end portion of the light transmission region to form the laser processing portion 13, and light is transmitted through the laser processing portion. The peripheral edge part of a permeation | transmission area | region and a cushion layer are welded.

  As a second specific example, first, a polishing layer 11 having a polishing region 9 and an opening A (10) for providing a light transmission region 8, and an opening B (15) smaller than the light transmission region are provided. The cushion layer 14 is pasted so that the opening A and the opening B overlap. Next, a light transmission region is fitted on the opening B and in the opening A. Then, the laser beam 12 is irradiated from the polishing surface side to melt the cushion layer or the adhesive member that is in contact with the peripheral end portion of the light transmission region to form the laser processing portion 13, and light is transmitted through the laser processing portion. The peripheral edge part of a permeation | transmission area | region and a cushion layer are welded.

  The laser used to form the laser processed portion is not easily absorbed by the light transmitting region, can melt the cushion layer or the adhesive member (double-sided tape or adhesive layer), and the periphery of the light transmitting region through the laser processed portion. If it is a laser which can weld an edge part and a cushion layer, it will not restrict | limit in particular, For example, said laser is mentioned. In particular, it is preferable to use an infrared laser that is not easily absorbed by the light transmission region. The laser light irradiation conditions are the same as described above.

  From the viewpoint of completely preventing slurry leakage, the laser processing portion needs to be provided at the entire peripheral end portion of the light transmission region. Moreover, as shown in FIG. 3, you may irradiate a laser beam from the grinding | polishing back surface side toward the part which the back surface of a light transmissive area | region and the cross section of the opening part B contact. Moreover, you may irradiate a laser beam simultaneously from the grinding | polishing surface side and a grinding | polishing back surface side.

  In the method for creating the polishing pad, when the laser processing part is formed by melting the cushion layer, a method in which an adhesive member (double-sided tape or adhesive layer) is not provided in a portion where the light transmission region and the cushion layer are in contact with each other Can also be taken. In that case, it is preferable that the peripheral end portion of the light transmission region and the cushion layer are brought into close contact with each other at the time of laser light irradiation. Thereby, the laser processed part can be adhered to both the light transmission region and the cushion layer, and the peripheral end portion of the light transmission region and the cushion layer can be welded more firmly. Although the method of making it adhere | attach is not restrict | limited in particular, For example, the method of installing a member (glass plate etc.) which permeate | transmits a laser beam on a light transmissive area | region, and applying a pressure from the top is mentioned.

  The cushion layer supplements the characteristics of the polishing layer. The cushion layer is necessary in order to achieve both planarity and uniformity in a trade-off relationship in CMP. Planarity refers to the flatness of a pattern portion when an object to be polished having minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire object to be polished. The planarity is improved by the characteristics of the polishing layer, and the uniformity is improved by the characteristics of the cushion layer. In the polishing pad of the present invention, the cushion layer is preferably softer than the polishing layer.

  A material for forming the cushion layer is not particularly limited. For example, a fiber nonwoven fabric such as a polyester nonwoven fabric, a nylon nonwoven fabric, and an acrylic nonwoven fabric, a resin-impregnated nonwoven fabric such as a polyester nonwoven fabric impregnated with polyurethane, a polymer resin such as polyurethane foam and polyethylene foam Examples thereof include rubber resins such as foam, butadiene rubber and isoprene rubber, and photosensitive resins.

  As a means for bonding the polishing layer (polishing region) and the cushion layer, for example, a method of sandwiching and pressing the polishing layer and the cushion layer with a double-sided tape, or an adhesive such as a rubber adhesive or an acrylic adhesive is applied. A method is mentioned.

  The double-sided tape has a general configuration in which adhesive layers are provided on both sides of a substrate such as a nonwoven fabric or a film. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. Considering the content of metal ions, an acrylic adhesive is preferable because the metal ion content is low. In addition, since the composition of the polishing region and the cushion layer may be different, the composition of each adhesive layer of the double-sided tape can be made different so that the adhesive force of each layer can be optimized.

  On the other side of the cushion layer, a double-sided tape for bonding to the platen may be provided. Examples of means for attaching the cushion layer and the double-sided tape include a method of pressing and bonding the double-sided tape to the cushion layer.

  The double-sided tape has a general configuration in which an adhesive layer is provided on both surfaces of a base material such as a nonwoven fabric or a film as described above. In consideration of peeling from the platen after using the polishing pad, it is preferable to use a film as the base material because the tape residue and the like can be eliminated. The composition of the adhesive layer is the same as described above.

  The semiconductor device is manufactured through a step of polishing the surface of the semiconductor wafer using the polishing pad. A semiconductor wafer is generally a laminate of a wiring metal and an oxide film on a silicon wafer. The method and apparatus for polishing the semiconductor wafer are not particularly limited. For example, as shown in FIG. 1, a polishing surface plate 2 that supports the polishing pad 1, a support table (polishing head) 5 that supports the semiconductor wafer 4, and the wafer. This is performed using a backing material for performing uniform pressurization and a polishing apparatus equipped with a polishing agent 3 supply mechanism. The polishing pad 1 is attached to the polishing surface plate 2 by attaching it with a double-sided tape, for example. The polishing surface plate 2 and the support base 5 are disposed so that the polishing pad 1 and the semiconductor wafer 4 supported on each of the polishing surface plate 2 and the support table 5 face each other, and are provided with rotating shafts 6 and 7 respectively. Further, a pressurizing mechanism for pressing the semiconductor wafer 4 against the polishing pad 1 is provided on the support base 5 side. In polishing, the semiconductor wafer 4 is pressed against the polishing pad 1 while rotating the polishing surface plate 2 and the support base 5, and polishing is performed while supplying slurry. The flow rate of the slurry, the polishing load, the polishing platen rotation speed, and the wafer rotation speed are not particularly limited and are appropriately adjusted.

  As a result, the protruding portion of the surface of the semiconductor wafer 4 is removed and polished flat. Thereafter, a semiconductor device is manufactured by dicing, bonding, packaging, or the like. The semiconductor device is used for an arithmetic processing device, a memory, and the like.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. The evaluation items in Examples and the like were measured as follows.

(Water leakage evaluation)
SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and water leakage was evaluated using the prepared polishing pad. An 8-inch dummy wafer was continuously polished for 30 minutes, and then the inset portion of the light transmission region on the back surface side of the polishing pad was visually observed to confirm the presence or absence of water leakage. As polishing conditions, silica slurry (SS12, manufactured by Cabot Microelectronics) was added as an alkaline slurry at a flow rate of 150 ml / min during polishing, polishing load 350 g / cm ² , polishing platen rotation speed 35 rpm, and wafer rotation speed. 30 rpm. The wafer was polished while dressing the surface of the polishing pad using a # 100 dresser. The dressing conditions were a dress load of 80 g / cm ² and a dresser rotational speed of 35 rpm.

[Production of light transmission region]
A polyester polyol (number average molecular weight 2400) 128 parts by weight composed of adipic acid, hexanediol and ethylene glycol and 30 parts by weight of 1,4-butanediol were mixed, and the temperature was adjusted to 70 ° C. To this mixed solution, 100 parts by weight of 4,4′-diphenylmethane diisocyanate previously adjusted to 70 ° C. was added and stirred for about 1 minute. Then, the mixed solution was poured into a container kept at 100 ° C. and post-cured at 100 ° C. for 8 hours to produce a polyurethane resin. Using the produced polyurethane resin, a light transmission region (length 56 mm, width 20 mm, thickness 1.25 mm) was prepared by injection molding.

[Production of polishing area]
Production Example 1
In the reaction vessel, 100 parts by weight of a polyether-based prepolymer (Uniroy Corporation, Adiprene L-325, NCO concentration: 2.22 meq / g), and a silicone-based surfactant (Toray Dow Silicone, SH192) 3 parts by weight were mixed and the temperature was adjusted to 80 ° C. Using a stirring blade, the mixture was vigorously stirred for about 4 minutes so that bubbles were taken into the reaction system at 900 rpm. 26 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Ihara Chemical amine, manufactured by Ihara Chemical Co.) previously melted at 120 ° C. was added thereto. Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-shaped open mold. When the reaction solution lost its fluidity, it was put in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane resin foam block. This polyurethane resin foam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane resin foam sheet. Next, this sheet was subjected to surface buffing to a predetermined thickness using a buffing machine (manufactured by Amitech Co., Ltd.) to obtain a sheet with adjusted thickness accuracy (sheet thickness: 1.27 mm). This buffed sheet is punched into a predetermined diameter (61 cm), and a groove processing machine (manufactured by Toho Koki Co., Ltd.) is used to make a groove width of 0.25 mm, groove pitch of 1.50 mm, and groove depth of 0.40 mm. A polished region was prepared by performing concentric groove processing.

[Production of polishing pad]
Example 1
A double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) was attached to the surface opposite to the grooved surface of the produced polishing region using a laminator. Thereafter, an opening A (56 mm × 20 mm) for fitting the light transmission region into a predetermined position of the polishing region was punched out to prepare a polishing region with a double-sided tape.
A cushion layer made of polyethylene foam (Toray Industries Inc., TORAYPEF, thickness: 0.8 mm) buffed and corona-treated on the surface was bonded to the adhesive surface of the polishing area with double-sided tape using a laminator. Next, a double-sided tape was bonded to the cushion layer surface. And the cushion layer was punched out by the magnitude | size of 50 mm x 14 mm among the hole parts punched out in order to insert the light transmissive area | region, and the opening part B was formed. Then, the produced light transmission region was fitted in the opening A. Then, while placing a glass plate on the light transmission region and applying pressure, infrared laser light is output from the polishing surface side to the peripheral end (width: 3 mm) of the light transmission region with a laser output of 6 W, an average scanning speed of 50 mm / sec, And a spot diameter of 1 mm, and a laser processing part is formed by melting a cushion layer in contact with the peripheral end part on the back surface side of the light transmission region, and the peripheral end part of the light transmission region through the laser processing part And a cushion layer were welded to prepare a polishing pad. As a result of water leakage evaluation, no slurry leakage was found at the inset portion.

Example 2
An opening A (56 mm × 20 mm) for fitting the light transmission region into a predetermined position of the produced polishing region was punched out, and the produced light transmission region was fitted into the opening A. Thereafter, an infrared laser beam is irradiated on the interface between the polishing region and the light transmission region under conditions of a laser output of 6 W, an average scanning speed of 50 mm / sec, and a spot diameter of 1 mm, and the polishing region is melted to form a laser processing portion. A polishing region and a light transmission region were welded through the laser processing part to prepare a polishing pad. As a result of water leakage evaluation, no slurry leakage was found at the inset portion.

Comparative Example 1
An opening A (56 mm × 20 mm) for fitting the light transmission region into a predetermined position of the prepared polishing region was punched out to prepare a polishing region having the opening A. Also, a double-sided tape (Sekisui Chemical Co., Ltd., double tack tape) is bonded to one side of a cushion layer made of polyethylene foam (Toray Industries, Toraypef, thickness: 0.8 mm) buffed and corona-treated. It was. Next, a polishing region having an opening A was bonded to the adhesive surface of the cushion layer. And the cushion layer was punched out by the magnitude | size of 50 mm x 14 mm among the hole parts punched out in order to insert the light transmissive area | region, and the opening part B was formed. And the produced light transmission area | region was inserted in the opening part A, and the polishing pad was produced. When water leakage evaluation was performed, slurry leakage at the inset portion was observed.

Schematic configuration diagram showing an example of a conventional polishing apparatus used in CMP polishing Schematic sectional view showing an example of the polishing pad of the present invention Schematic sectional view showing an example of another polishing pad of the present invention Schematic configuration diagram showing an example of a CMP polishing apparatus having an end point detection apparatus of the present invention

Explanation of symbols

1: Polishing pad 2: Surface plate 3: Abrasive (slurry)
4: Object to be polished (wafer)
5: Object to be polished (wafer) support stand (polishing head)
6, 7: Rotating shaft 8: Light transmission region 9: Polishing region 10: Opening A
11: Polishing layer 12: Laser beam 13: Laser processing part 14: Cushion layer 15: Opening B
16: Laser interferometer 17: Laser beam

Claims (6)

A polishing pad comprising a polishing layer having a polishing region and a light transmission region, wherein the polishing region and the light transmission region are welded via a laser processing section. A step of providing a light transmission region in the opening A of a polishing layer having a polishing region and an opening A, laser irradiation is performed on the interface between the polishing region and the light transmission region, and the polishing region is melted to perform laser processing. A method for producing a polishing pad, comprising a step of forming a portion and welding a polishing region and a light transmission region through the laser processing portion. A polishing layer having a polishing region and a light transmission region, and a cushion layer having an opening B smaller than the light transmission region are laminated so that the light transmission region and the opening B overlap, and the light A polishing pad in which a peripheral end portion of a transmission region and the cushion layer are welded via a laser processing portion. A step of laminating a cushion layer on a polishing layer having a polishing region and an opening A, a step of removing a part of the cushion layer in the opening A, and forming an opening B smaller than the light transmission region in the cushion layer , A step of providing a light transmission region on the opening B and in the opening A, and laser processing by irradiating a laser beam to melt a cushion layer or an adhesive member that is in contact with a peripheral end portion of the light transmission region A polishing pad including a step of forming a portion and welding the peripheral end portion of the light transmission region and the cushion layer through the laser processing portion. A step of laminating a polishing layer having a polishing region and an opening A and a cushion layer having an opening B smaller than the light transmission region so that the opening A and the opening B overlap with each other; A step of providing a light transmitting region in the opening A, and a laser processing unit is formed by irradiating a laser beam to melt a cushion layer or an adhesive member in contact with a peripheral end portion of the light transmitting region; A method for manufacturing a polishing pad, comprising a step of welding a peripheral end portion of a light transmission region and a cushion layer through a processed portion. A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing pad according to claim 1.

Images