JP2016066781A - Abrasive pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abrasive pad capable of optically detecting an endpoint with high precision even when having a structure in which a rear surface of a window is bonded to an adhesive member.SOLUTION: The abrasive pad is formed by laminating a polishing layer having a polishing region and a light transmission region, and a support layer having an opening part through an adhesive member so that the light transmission region and the opening part overlap. Arithmetic average roughness Ra of a rear surface of the adhesive member at the opening part is less than or equal to 1 μm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a polishing pad for use in planarizing unevenness on a surface of an object to be polished such as a semiconductor wafer by chemical mechanical polishing (CMP), and more specifically, a window for detecting a polishing state or the like by optical means. The present invention relates to a polishing pad having (light transmission region) and a method for manufacturing a semiconductor device using the polishing pad.

  When manufacturing a semiconductor device, a conductive film is formed on the surface of a semiconductor wafer (hereinafter also referred to as a wafer), and a wiring layer is formed by photolithography, etching, or the like. Processes for forming an insulating film and the like are performed, and unevenness made of a conductor such as metal or an insulator is generated on the wafer surface by these processes. 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.

  In performing such CMP, there is a problem in determining the wafer surface flatness. 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, but optical detection means are becoming mainstream in terms of measurement accuracy and spatial resolution in non-contact measurement.

  Specifically, the optical detection means is a method of detecting an end point of polishing 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. It is.

  Various types of polishing pads have been proposed for use in such a polishing end point detection method using optical means. In the future, as integrated wiring and ultra-miniaturization in semiconductor manufacturing are expected, the wiring width of integrated circuits is expected to become even smaller. Therefore, a polishing pad capable of highly accurate optical end point detection is required. .

For example, Patent Document 1 discloses a polishing pad for performing chemical mechanical planarization of a semiconductor substrate,
A polishing pad body having an opening formed therein;
A window fixed in the opening for performing in-situ optical measurement of the substrate, the window having a lower surface capable of receiving light incident thereon, and the lower surface is A polishing pad that has been processed by laser ablation to remove a rough surface portion present on the lower surface has been proposed.

  Further, in Patent Document 2, a polishing surface and a non-polishing surface opposite to the polishing surface are provided, and there is a light-transmitting region that optically communicates from the polishing surface to the non-polishing surface. A chemical mechanical polishing pad is proposed in which the surface roughness (Ra) of the polishing surface is 10 μm or less, and the transmittance of the light-transmitting region with respect to light having a wavelength of 633 nm is 12 to 70%.

Further, in Patent Document 3, a chemical mechanical polishing pad having a polishing surface and a non-polishing surface opposite to the polishing surface,
A light-transmitting region that optically communicates from the polished surface to the non-polished surface;
A chemical mechanical polishing pad is proposed in which the surface roughness (Ra) of the non-polishing surface in the light-transmitting region is smaller than the surface roughness (Ra) of the polishing surface.

JP 2007-049163 A JP 2008-073845 A JP 2008-226911 A

  An object of the present invention is to provide a polishing pad capable of detecting an optical end point with high accuracy despite having a structure in which the back surface of a window is bonded to an adhesive member.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the polishing pad described below, and have completed the present invention.

  That is, the present invention provides a polishing pad in which a polishing layer having a polishing region and a light transmission region and a support layer having an opening are laminated via an adhesive member so that the light transmission region and the opening overlap each other. The polishing pad according to claim 1, wherein an arithmetic average roughness Ra of the back surface of the adhesive member in the opening is 1 μm or less.

  The adhesive member is preferably an adhesive layer or a double-sided tape having adhesive layers on both sides of the substrate.

  Further, in the present invention, the polishing region, the adhesive member, the support layer, and the double-sided adhesive sheet are laminated in this order, and light is transmitted through the polishing region, the adhesive member, and the support layer, and on the double-sided adhesive sheet. In the polishing pad provided with the area | region, it is related with the polishing pad characterized by arithmetic mean roughness Ra of the back surface of the said double-sided adhesive sheet in the said opening part being 1 micrometer or less.

  A polishing pad having a structure in which the back surface of the light transmission region is bonded to an adhesive member or a double-sided adhesive sheet has a problem that the optical end point detection accuracy is very low compared to a polishing pad in which the back surface of the light transmission region is exposed. there were. The inventor has the reason that the light beam is absorbed or scattered by the adhesive member or the double-sided adhesive sheet provided on the back surface of the light transmission region before the light beam enters the light transmission region. Thought. Then, as a result of intensive studies, the present inventor reduced the light scattering of the light beam by setting the arithmetic average roughness Ra of the back surface of the adhesive member or the double-sided adhesive sheet in the opening to 1 μm or less as described above. It was found that the optical end point detection can be performed with high accuracy.

  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.

  The polishing pad of the present invention does not expose the back surface of the light transmission region, and can detect an optical end point with high accuracy despite having a structure bonded to an adhesive member or a double-sided adhesive sheet.

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

  The polishing pad of the present invention has a structure in which a polishing layer having a polishing region and a light transmission region and a support layer having an opening are laminated via an adhesive member so that the light transmission region and the opening overlap each other. Have

  In another polishing pad of the present invention, a polishing region, an adhesive member, a support layer, and a double-sided adhesive sheet are laminated in this order, and within the opening passing through the polishing region, the adhesive member, and the support layer and on the double-sided adhesive sheet Has a structure in which a light transmission region is provided.

  The polishing region is not particularly limited as long as it is a foam having fine bubbles. 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 1 type, or 2 or more types of mixtures, such as a photosensitive resin, is mentioned. 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. Hereinafter, the polyurethane resin will be described on behalf of the foam.

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

  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.

  Examples of the high molecular weight polyol include those usually used in the technical field of polyurethane. Examples include polyether polyols typified by polytetramethylene ether glycol, polyethylene glycol, etc., polyester polyols typified by polybutylene adipate, polycaprolactone polyols, reactants of polyester glycols such as polycaprolactone and alkylene carbonate, etc. Polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the obtained reaction mixture with organic dicarboxylic acid, polycarbonate polyol obtained by transesterification of 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 the polyol component, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2 -Hydroxyethoxy) benzene, trimethylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane, methylglucoside, sorbitol, mannitol, dulcitol, sucrose, 2,2,6,6-tetrakis (Hydroxymethyl) cyclohexanol, diethanolamine, N- methyldiethanolamine, and can be used in combination of low molecular weight polyols such as triethanolamine. Moreover, low molecular weight polyamines, such as ethylenediamine, tolylenediamine, diphenylmethanediamine, and diethylenetriamine, can also be used in combination. Also, alcohol amines such as monoethanolamine, 2- (2-aminoethylamino) ethanol, and monopropanolamine can be used in combination. These low molecular weight polyols and low molecular weight polyamines may be used alone or in combination of two or more. The blending amount of the low molecular weight polyol, the low molecular weight polyamine or the like is not particularly limited, and is appropriately determined depending on the characteristics required for the polishing pad to be produced.

  When a polyurethane resin foam is produced by a prepolymer method, a chain extender is used for curing the prepolymer. The chain extender is an organic compound having at least two active hydrogen groups, and examples of the active hydrogen group include a hydroxyl group, a primary or secondary amino group, and a thiol group (SH). Specifically, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3,5 -Bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2 , 6-diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 4,4′-diamino-3,3 ′, 5,5′-tetraethyldiphenylmethane, 4, 4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetra Sopropyldiphenylmethane, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane, N, N′-di-sec-butyl -4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, m-xylylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, m-phenylenediamine And polyamines exemplified by p-xylylenediamine and the like, or the low molecular weight polyols and low molecular weight polyamines mentioned above. 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 can be variously changed depending on the molecular weight of each, the desired physical properties of the polishing pad, and the like. In order to obtain a polishing pad having desired polishing characteristics, the number of isocyanate groups of the isocyanate component relative to the total number of active hydrogen groups (hydroxyl group + amino group) of the polyol component and the chain extender is 0.80 to 1.20. Is more preferable, and 0.99 to 1.15 is more preferable. When the number of isocyanate groups is outside the above range, curing failure occurs and the required specific gravity and hardness cannot be obtained, and the polishing characteristics tend to be deteriorated.

  The polyurethane resin foam can be produced by applying a known urethanization technique such as a melting method or a solution method, but is preferably produced by a melting method in consideration of cost, work environment, and the like.

  The polyurethane resin foam can be produced by either the prepolymer method or the one-shot method. However, an isocyanate-terminated prepolymer is synthesized beforehand from an isocyanate component and a polyol component, and this is reacted with a chain extender. The polymer method is preferred because the resulting polyurethane resin has excellent physical properties.

  Examples of the method for producing a polyurethane resin foam include a method of adding hollow beads, a mechanical foaming method, and a chemical foaming method.

  In particular, a mechanical foaming method using a silicone surfactant which is a copolymer of polyalkylsiloxane and polyether and does not have an active hydrogen group is preferable.

  In addition, you may add stabilizers, such as antioxidant, a lubricant, a pigment, a filler, an antistatic agent, and another additive as needed.

  The polyurethane resin foam may be a closed cell type or an open cell type.

  Polyurethane resin foam can be manufactured by batch feeding each component into a container and stirring, or by continuously supplying each component and non-reactive gas to the stirring device and stirring, It may be a continuous production method in which a dispersion is sent out to produce a molded product.

  Also, put the prepolymer that is the raw material of the polyurethane resin foam into the reaction vessel, then add the chain extender, stir, and then cast into a mold of a predetermined size to make the block into a bowl or band saw shape In the method of slicing using a slicer, or in the step of pouring into the aforementioned mold, a thin sheet may be used. Alternatively, a raw material resin may be dissolved and extruded from a T-die to directly obtain a sheet-like polyurethane resin foam.

  The average cell diameter of the polyurethane resin foam is preferably 30 to 80 μm, more preferably 30 to 60 μm. When deviating from this range, the polishing rate tends to decrease, or the planarity of the polished material (wafer) after polishing tends to decrease.

  The specific gravity of the polyurethane resin foam is preferably 0.5 to 1.3. When the specific gravity is less than 0.5, the surface strength of the polishing region decreases, and the planarity of the material to be polished tends to decrease. On the other hand, when the ratio is larger than 1.3, the number of bubbles on the surface of the polishing region decreases, and planarity is good, but the polishing rate tends to decrease.

  The hardness of the polyurethane resin foam is preferably 40 to 75 degrees as measured by an Asker D hardness meter. When the Asker D hardness is less than 40 degrees, the planarity of the material to be polished is lowered, and when it is larger than 75 degrees, the planarity is good, but the uniformity (uniformity) of the material to be polished is lowered. There is a tendency.

  The polishing surface that comes into contact with the material to be polished in the polishing region preferably has a concavo-convex structure for holding and renewing the slurry. The polishing area made of foam has many openings on the polishing surface and has the function of holding and updating the slurry. By forming a concavo-convex structure on the polishing surface, the slurry can be held and updated more efficiently. It can be performed well, and destruction of the material to be polished due to adsorption with the material to be polished can be prevented. The concavo-convex structure is not particularly limited as long as it is a shape that holds and renews the slurry. For example, an XY lattice groove, a concentric circular groove, an opening, a hole that does not penetrate, a polygonal column, a cylinder, a spiral groove, Examples include eccentric circular grooves, radial grooves, and combinations of these grooves. In addition, these uneven structures are generally regular, but in order to make the slurry retention and renewability desirable, the groove pitch, groove width, groove depth, etc. should be changed for each range. Is also possible.

  The shape of the polishing region is not particularly limited, and may be circular or long. The size of the polishing region can be appropriately adjusted according to the polishing apparatus to be used. In the case of a circular shape, the diameter is about 30 to 150 cm, and in the case of a long shape, the length is about 5 to 15 m. The width is about 60 to 250 cm.

  Although the thickness in particular of a grinding | polishing area | region is not restrict | limited, Usually, it is about 0.8-4 mm, and it is preferable that it is 1.2-2.5 mm.

  The material for forming the light transmission region is not particularly limited, but it is possible to detect the optical end point with high accuracy while polishing and use a material having a light transmittance of 10% or more over the entire wavelength range of 400 to 700 nm. More preferred is a material having a light transmittance of 20% or more, and still more preferred is a material having a light transmittance of 50% or more. Examples of such materials include polyurethane resins, polyester resins, phenol resins, urea resins, melamine resins, epoxy resins, and acrylic resins, and other thermosetting resins, polyurethane resins, polyester resins, polyamide resins, cellulose resins, Acrylic resins, polycarbonate resins, halogen resins (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resins (polyethylene, polypropylene, etc.), thermoplastic resins, butadiene rubber, isoprene rubber, etc. Examples thereof include rubber, photo-curing resin that is cured by light such as ultraviolet rays and electron beams, and photosensitive resin. These resins may be used alone or in combination of two or more.

  The material used for the light transmission region preferably has the same or greater grindability than the material used for the polishing region. Grindability refers to the degree to which a material to be polished is ground during polishing. In such a case, the light transmission region does not protrude from the polishing region, and scratches on the material to be polished and dechucking errors during polishing can be prevented.

  Further, it is preferable to use a forming material used for the polishing region or a material similar to 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 shape and size of the light transmission region are not particularly limited, but it is preferable to have the same shape and size as the opening of the polishing region.

  The Asker D hardness of the light transmission region is preferably 30 to 75 degrees. By using the light transmission region having the hardness, the generation of scratches on the wafer surface and the deformation of the light transmission region can be suppressed. In addition, it is possible to suppress the occurrence of scratches on the surface of the light transmission region, thereby enabling highly accurate optical end point detection to be performed stably. The Asker D hardness in the light transmission region is more preferably 40 to 75 degrees.

  The support layer supplements the characteristics of the polishing region. As the support layer, a layer having a lower elastic modulus than the polishing region (cushion layer) may be used, or a layer having a higher elastic modulus than the polishing region (high elastic layer) may be used. 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 a material having fine irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire material to be polished. The planarity is improved by the characteristics of the polishing region, and the uniformity is improved by the characteristics of the cushion layer. The high elastic layer is used for improving the planarization characteristics of the polishing pad when a soft polishing region is used in CMP to suppress the occurrence of scratches. In addition, by using a highly elastic layer, it is possible to suppress excessive cutting of the edge portion of the material to be polished.

  Examples of the cushion layer include fiber nonwoven fabrics such as polyester nonwoven fabric, nylon nonwoven fabric, and acrylic nonwoven fabric; resin-impregnated nonwoven fabrics such as polyester nonwoven fabric impregnated with polyurethane; polymer resin foams such as polyurethane foam and polyethylene foam; butadiene rubber and Examples thereof include rubber resins such as isoprene rubber; and photosensitive resins.

  Although the thickness in particular of a cushion layer is not restrict | limited, It is preferable that it is 300-1800 micrometers, More preferably, it is 700-1400 micrometers.

  Examples of the highly elastic layer include a metal sheet and a resin film. Examples of the resin film include polyester films such as polyethylene terephthalate film and polyethylene naphthalate film; polyolefin films such as polyethylene film and polypropylene film; nylon film; polyimide film and the like.

  As the highly elastic layer, it is preferable to use a resin film having a dimensional change rate of 1.2% or less after heating at 150 ° C. for 30 minutes and before heating. A resin film having a dimensional change rate of 0.8% or less is more preferable, and a resin film having a dimensional change rate of 0.4% or less is particularly preferable. Examples of the resin film having such characteristics include a polyethylene terephthalate film, a polyethylene naphthalate film, a polyimide film, and the like that have been subjected to heat shrink treatment.

  The thickness of the highly elastic layer is not particularly limited, but is preferably 10 to 200 μm, more preferably 15 to 55 μm from the viewpoint of rigidity, dimensional stability during heating, and the like.

  FIG. 2 is a schematic cross-sectional view showing an example of the polishing pad of the present invention. The polishing region 8 is provided with a light transmission region 9 for detecting an optical end point while polishing. The light transmission region 9 is fixed by being fitted into an opening 10 provided in the polishing region 8 and adhered to the adhesive member 11 below the polishing region 8. The support layer 12 has an opening 13 for transmitting light. The opening 13 may be the same size as the opening 10, may be smaller than the opening 10, or may be larger than the opening 10.

  As the adhesive member 11, it is preferable to use an adhesive layer containing a pressure-sensitive adhesive or a hot melt adhesive, or a double-sided tape in which the adhesive layer is provided on both surfaces of a base material. The double-sided tape is suitable because it prevents the slurry from penetrating to the support layer side by the base material and can effectively prevent peeling between the support layer and the adhesive layer.

  Examples of the base material include a resin film, and examples of the resin film include a polyester film such as a polyethylene terephthalate film and a polyethylene naphthalate film; a polyolefin film such as a polyethylene film and a polypropylene film; a nylon film; and a polyimide film. . Among these, it is preferable to use a polyester film having excellent properties for preventing water permeation.

  The surface of the substrate may be subjected to easy adhesion treatment such as corona treatment or plasma treatment.

  The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 15 to 55 μm from the viewpoint of transparency, flexibility, rigidity, dimensional stability during heating, and the like.

  The thickness of the adhesive layer is preferably 10 to 300 μm, more preferably 25 to 200 μm.

  The arithmetic average roughness Ra of the back surface 14 of the adhesive member 11 in the opening 13 is 1 μm or less, preferably 0.5 μm or less, more preferably 0.3 μm or less, and further preferably 0.2 μm or less. .

  Although the method in particular of making arithmetic mean roughness Ra 1 micrometer or less is not restrict | limited, For example, the following method is mentioned.

  A release film for protecting the adhesive surface is usually provided on the surface of the adhesive layer or the double-sided tape, and it is peeled off during use. The arithmetic average roughness Ra of the surface of a general release film is about 2 to 3 μm, and the arithmetic average roughness Ra of the surface of the adhesive layer in close contact with the release film is also about 2 to 3 μm. By using the release film having a surface arithmetic average roughness Ra of 1 μm or less, the surface roughness is transferred to the surface of the adhesive layer, and the surface of the adhesive layer or double-sided tape is arithmetically averaged. Ra can be 1 μm or less.

  Examples of the release film having an arithmetic mean surface roughness Ra of 1 μm or less include polyester films such as polyethylene terephthalate film and polyethylene naphthalate film; polyolefin films such as polyethylene film and polypropylene film; nylon film; polyimide film and the like. It is done.

  FIG. 3 is a schematic cross-sectional view showing another example of the polishing pad of the present invention. In the polishing pad 1, the polishing layer 8, the adhesive member 11, the support layer 12, and the double-sided adhesive sheet 15 are laminated in this order. In addition, the light transmission region 9 is provided on the double-sided adhesive sheet 15.

  The double-sided adhesive sheet 15 has an adhesive layer on both sides of the substrate, and the double-sided tape can be used. The double-sided adhesive sheet 15 is used for bonding the polishing pad 1 to the polishing surface plate 2.

  The polishing pad 1 can be manufactured, for example, by the following method. First, the polishing layer 8 and the support layer 12 are laminated via the adhesive member 11 to produce a laminated sheet. Openings 16 are formed in the produced laminated sheet. A double-sided adhesive sheet 15 is affixed to the support layer 12 of the laminated sheet in which the opening 16 is formed. Thereafter, the light transmission region 9 is provided in the opening 16 and on the double-sided adhesive sheet 15. Alternatively, the double-sided adhesive sheet 15 may be attached to the support layer 12 and the light transmission region 9 after the light transmission region 9 is inserted into the opening 16.

  The arithmetic average roughness Ra of the back surface 14 of the double-sided adhesive sheet 15 in the opening 16 is 1 μm or less, preferably 0.5 μm or less, more preferably 0.3 μm or less, and even more preferably 0.2 μm or less. is there.

  The method for setting the arithmetic average roughness Ra to 1 μm or less is not particularly limited, and examples thereof include the same method as described above.

  The surface height of the light transmission region 9 is preferably the same as the surface height of the polishing region 8 or lower than the surface height of the polishing region 8. When the surface height of the light transmission region 9 is higher than the surface height of the polishing region 8, there is a risk of damaging the material to be polished by the protruding portion during polishing. Further, the light transmission region 9 is deformed by a stress applied during polishing, and is greatly distorted optically, so that there is a possibility that the optical end point detection accuracy of polishing is lowered.

  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 Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these Examples.

[Measurement and evaluation methods]
(Measurement of arithmetic average roughness)
From the prepared polishing pad, a laminated portion of the light transmission region and the adhesive layer in the opening was cut out to obtain a sample. Based on JIS B0601-1994, arithmetic average roughness Ra (micrometer) of the adhesive layer surface of a sample was measured.

(Evaluation of end point detection)
Using MIRRA (manufactured by AMAT) as a polishing apparatus, using the prepared laminated polishing pad, a wafer with 10,000 tungsten films formed on an 8-inch silicon wafer is polished for 60 seconds per piece to detect an optical end point. Checked.
○: End point can be detected ×: End point cannot be detected

Example 1
[Production of light transmission region]
100 parts by weight of a polyether-based prepolymer (manufactured by Uniroyal Corporation, adiprene L-325, NCO concentration: 2.22 meq / g) was previously temperature-controlled at 70 ° C., and 4,4′- 26 parts by weight of methylene bis (o-chloroaniline) (manufactured by Ihara Chemical Co., Ltd., Iharacamine MT) was added and stirred for about 1 minute. Then, the mixed solution was poured into a mold kept at 100 ° C. and post-cured at 100 ° C. for 8 hours to produce a polyurethane resin. The produced polyurethane resin was cut with a Thomson blade of a predetermined size to produce a light transmission region (55.8 mm × 19.8 mm, thickness 1.95 mm).

[Production of polishing layer with double-sided tape]
In a 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 Corning Silicone, SH- 192) 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. Thereto was added 26 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Iharacamine MT-N, manufactured by Ihara Chemical Co.) previously melted at 120 ° C. Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-shaped open mold. When the fluidity of this reaction solution disappeared, it was put in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane foam block. This polyurethane foam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane 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: 2.00 mm). The buffed sheet is punched into a predetermined diameter (76 cm), and a groove processing machine (manufactured by Toho Steel Machine Co., Ltd.) is used to make a groove width of 0.40 mm, groove pitch of 3.10 mm, and groove depth of 0.76 mm. Concentric grooves were processed. Thereafter, an opening (56 mm × 20 mm) for fitting the light transmission region into a predetermined position of the grooved sheet was formed to prepare a polishing region. Then, on the surface opposite to the grooved surface of the polishing region, a laminator is used to have an adhesive layer on both surfaces of the substrate, and the surface of the adhesive layer is a release film (adhesive layer) A double-sided tape (Sekisui Chemical Co., Ltd., thickness: 0.15 mm) protected with an arithmetic average roughness Ra of the surface in contact with the substrate is attached while peeling the release film, and further in the polishing region. A light-transmitting region was fitted in the opening and bonded to the double-sided tape to prepare a polishing layer with double-sided tape.

[Production of polishing pad]
A cushioning layer made of polyethylene foam (Toray Industries Inc., TORAYPEF, thickness: 0.8 mm) buffed and corona-treated is bonded to the adhesive layer of the prepared double-sided taped abrasive layer using a laminator. A polishing sheet was prepared. Next, a double-sided adhesive sheet was bonded to the cushion layer of the polishing sheet to obtain a laminate. Thereafter, an opening having a size of 60 mm × 20 mm was formed only in the cushion layer and the double-sided adhesive sheet of the laminate, and a polishing pad having the structure of FIG. 2 was produced.

Example 2
[Production of polishing area with double-sided tape]
A polished region was produced in the same manner as in Example 1. Thereafter, a double-sided tape was attached to the surface of the polishing region opposite to the grooved surface using a laminating machine to prepare a polishing region with a double-sided tape.

[Production of polishing pad]
A cushion layer made of polyethylene foam (Toray Industries, Toraypef, thickness: 0.8 mm) buffed and corona-treated is bonded to the adhesive layer in the polishing area with double-sided tape using a laminator. A polishing sheet was prepared. Next, an opening having a size of 60 mm × 20 mm was formed in the polishing sheet. Thereafter, both sides of the substrate have adhesive layers, and the surfaces of the adhesive layers are protected by a release film (the arithmetic average roughness Ra of the surface in contact with the adhesive layer Ra: 0.17 μm). A sheet (base material: polyethylene terephthalate, thickness 25 μm) was bonded to the cushion layer of the polishing sheet with a laminator while peeling the release film to obtain a laminate. Thereafter, the light transmissive region produced in Example 1 was fitted into the opening of the laminate and bonded to the double-sided adhesive sheet to produce a polishing pad having the structure of FIG.

Comparative Example 1
In preparation of the polishing layer with a double-sided tape of Example 1, it has an adhesive layer on both surfaces of the base material, and the surface of the adhesive layer is a release film (the arithmetic average roughness Ra of the surface in contact with the adhesive layer) A polishing pad having the structure of FIG. 2 was prepared in the same manner as in Example 1 except that a double-sided tape protected with 1.5 μm) (base material: polyethylene terephthalate, thickness 25 μm) was used.

  The polishing pad of the present invention is used to flatten optical materials such as lenses and reflection mirrors, silicon wafers, glass substrates for hard disks, aluminum substrates, and materials that require high surface flatness such as general metal polishing. Used for processing. The polishing pad of the present invention is particularly suitable for a step of planarizing a silicon wafer and a device having an oxide layer, a metal layer, etc. formed thereon, before further laminating and forming these oxide layers and metal layers. Used for.

1: Polishing pad 2: Polishing surface plate 3: Abrasive (slurry)
4: Material to be polished (semiconductor wafer)
5: Support base (polishing head)
6, 7: Rotating shaft 8: Polishing area 9: Light transmission area 10, 13, 16: Opening 11: Adhesive member 12: Support layer 14: Back surface of adhesive member or double-sided adhesive sheet in opening 15: Double-sided adhesive sheet

Claims (4)

In the polishing pad in which a polishing layer having a polishing region and a light transmission region and a support layer having an opening are laminated via an adhesive member so that the light transmission region and the opening overlap, A polishing pad, wherein an arithmetic mean roughness Ra of the back surface of the adhesive member is 1 μm or less. The polishing pad according to claim 1, wherein the adhesive member is an adhesive layer or a double-sided tape having an adhesive layer on both surfaces of a substrate. The polishing region, the adhesive member, the support layer, and the double-sided adhesive sheet are laminated in this order, and the light transmission region is provided in the opening that penetrates the polishing region, the adhesive member, and the support layer and on the double-sided adhesive sheet. In the polishing pad, the arithmetic average roughness Ra of the back surface of the double-sided adhesive sheet in the opening is 1 μm or less. The manufacturing method of a semiconductor device including the process of grind | polishing the surface of a semiconductor wafer using the polishing pad in any one of Claims 1-3.

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