WO2014080729A1

WO2014080729A1 - Polishing pad

Info

Publication number: WO2014080729A1
Application number: PCT/JP2013/079245
Authority: WO
Inventors: 中村　賢治
Original assignee: 東洋ゴム工業株式会社
Priority date: 2012-11-26
Filing date: 2013-10-29
Publication date: 2014-05-30
Also published as: JP2014104521A; TW201429622A

Abstract

The purpose of the present invention is to provide a polishing pad, which hardly generates scratches on a surface of a subject to be polished, and which has a longer service-life. This polishing pad is characterized in that: the polishing pad is provided with a polishing layer having a polishing region and a light transmissive region; the polishing region has a groove on the surface thereof; the surface of the light transmissive region is recessed from the surface of the polishing region; and the recessed quantity of the light transmissive region is 30-100 % of the depth of the groove.

Description

Polishing pad

The present invention relates to a polishing pad for use in planarizing unevenness on the 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. A process for forming an interlayer insulating film is performed on the surface of the wafer, and these processes cause irregularities made of a conductor such as metal or an insulator 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 or the like) 4. And a backing material for uniformly pressing the wafer and a supply mechanism for the abrasive 3. 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 arranged so that the polishing pad 1 and the object to be polished 4 supported on each of them are opposed to each other, and are provided with rotating

shafts

6 and 7 respectively. Further, a pressurizing mechanism for pressing the polishing object 4 against the polishing pad 1 is provided on the support base 5 side.

There is a problem of determining the wafer surface flatness in performing such CMP. 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 when a desired surface property or thickness is obtained on the spot during 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 end point detection methods using such optical means and polishing pads used in the methods have been proposed.

For example, a load is applied between the polishing body and the polishing object, and the relative movement is performed with an abrasive interposed between the polishing body installed on the surface plate and the polishing object. Thus, in the polishing body used in the flattening apparatus for polishing the object to be polished, the polishing body has one or more openings and a window installed in the opening, and the window with respect to the surface of the polishing body There has been proposed a polishing body characterized in that the surface of the object to be polished is recessed and the amount of the recess changes stepwise or continuously (Patent Document 1).

In addition, by applying a load between the polishing body and the polishing object in a state where an abrasive is interposed between the polishing body installed on the surface plate and the polishing object, and by relatively moving the polishing object and the polishing object The polishing body used in the flattening apparatus for polishing the object to be polished has an opening and a window installed in the opening, and the window is formed by laminating two or more transparent materials. A characteristic polishing body has been proposed (Patent Document 2).

(A) a first polishing layer including a polishing surface and a first opening having a first length and a first width; and (b) a main body and a second opening having a second length and a second width. The second layer has substantially the same extent as the first polishing layer, and at least one of the first length and the first width is the second length and the second width, respectively. A second layer, and (c) a substantially transparent window portion disposed within the second opening of the second layer so as to be aligned with the first opening of the first polishing layer; and A polishing pad for chemical mechanical polishing including a substantially transparent window portion that is separated from the main body of the second layer by a gap has been proposed (Patent Document 3).

On the other hand, with the miniaturization of semiconductor devices, it is required more than ever to suppress the generation of scratches (scratches) on the surface of a semiconductor wafer, and the development of a polishing pad that hardly causes scratches is desired. In addition, development of a long-life type polishing pad is desired from the viewpoint of manufacturing cost reduction.

JP 2001-198802 A JP 2001-162520 A Special table 2007-506280 gazette

It is an object of the present invention to provide a polishing pad that hardly causes scratches on the surface of an object to be polished and that has a longer life.

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

That is, the present invention is a polishing pad comprising a polishing layer having a polishing region and a light transmission region, the polishing region has a groove on the surface, the surface of the light transmission region is recessed from the surface of the polishing region, The present invention relates to a polishing pad having a dent amount of 30 to 100% of the depth of the groove.

The structure in which the surface of the light transmission region is recessed from the surface of the polishing region can prevent the surface of the polishing object from coming into contact with the surface of the light transmission region during the polishing operation. As a result, scratches are less likely to occur on the surface of the object to be polished. In addition, although the dent on the surface of the light transmission region is gradually reduced due to wear of the polishing region during the polishing operation of the object to be polished and the dressing operation (sharpening operation) of the surface of the polishing region, By setting the depth of the groove to 30 to 100%, it is possible to extend the life of the polishing pad while maintaining high optical detection accuracy. By setting the dent amount on the surface of the light transmission region to 100% of the depth of the groove in the polishing region, it is possible to maintain a structure in which the surface of the light transmission region is recessed from the surface of the polishing region until there is no groove in the polishing region. This is most preferable from the viewpoint of extending the service life. When the dent amount is less than 30% of the groove depth, the surface of the light transmission region becomes the same height as the surface of the polishing region in a short time due to abrasion of the polishing region, and the surface of the object to be polished is brought into contact with the light transmission region. Scratches are likely to occur. Therefore, it is necessary to replace the polishing pad in a short time. On the other hand, when the dent amount exceeds 100% of the groove depth, the structure in which the surface of the light transmission region is recessed from the surface of the polishing region can be maintained until there is no groove in the polishing region. It is preferable from the viewpoint. However, since the amount of dent on the surface of the light transmission region is large in the initial stage of use of the polishing pad, a large amount of slurry accumulates in the dent portion, thereby reducing the optical detection accuracy, which is not preferable.

In the polishing pad of the present invention, a polishing region, a cushion layer, and a transparent support film are laminated in this order, and a light transmission region is provided in an opening that penetrates the polishing region and the cushion layer and on the transparent support film. Preferably there is. Since the light transmission region, the polishing region, and the cushion layer are formed on the transparent support film, the force that peels off the light transmission region and the polishing region (or the cushion layer) during the polishing operation works from the boundary between the two members. Even if the slurry leaks, the slurry does not leak below the transparent support film.

In the polishing pad of the present invention, a polishing layer having a polishing region and a light transmission region and a cushion layer having a through hole are laminated via a double-sided adhesive sheet so that the light transmission region and the through hole overlap. It may be.

Furthermore, the present invention relates to a semiconductor device manufacturing method including a step of polishing a surface of a semiconductor wafer using the polishing pad.

Since the polishing pad of the present invention has the above-described structure, it is difficult to cause scratches on the surface of the object to be polished and has a longer life.

It is a schematic block diagram which shows an example of the grinding | polishing apparatus used by CMP grinding | polishing. It is a schematic sectional drawing which shows an example of the structure of the polishing pad of this invention. It is a schematic sectional drawing which shows another example of the structure of the polishing pad of this invention.

The polishing pad of the present invention includes a polishing layer having a polishing region and a light transmission region, the polishing region has a groove on the surface, and the surface of the light transmission region is recessed from the surface of the polishing region, The amount of recess is 30 to 100% of the depth of the groove.

The polishing pad of the present invention may be only the polishing layer or a laminate of the polishing layer and other layers (for example, a cushion layer, an adhesive layer, a support film, etc.).

FIG. 2 is a schematic sectional view showing an example of the structure of the polishing pad of the present invention. As shown in FIG. 2, the polishing pad 1 has a polishing region 8, a cushion layer 11, and a transparent support film 12 laminated in this order, and in the opening 10 penetrating the polishing region 8 and the cushion layer 11 and transparent support film. A light transmissive region 9 is provided on 12. A groove 14 is provided on the surface of the polishing region 8.

FIG. 3 is a schematic sectional view showing another example of the structure of the polishing pad of the present invention. As shown in FIG. 3, in the polishing pad 1, a polishing layer having a polishing region 8 and a light transmission region 9 and a cushion layer 11 having a through hole 16 overlap the light transmission region 9 and the through hole 16. In this way, they are laminated via the double-sided adhesive sheet 13. A groove 14 is provided on the surface of the polishing region 8.

The material for forming the light transmission region 9 is not particularly limited, but a material that can detect an optical end point with high accuracy while polishing and has a light transmittance of 10% or more in the entire wavelength range of 400 to 800 nm is used. It is preferable that the material has 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 for forming the light transmission region 9 is preferably the same as the material for forming the polishing region 8 or a material similar to the physical properties of the polishing region 8. In particular, it is preferable to use a polyurethane resin.

The polyurethane resin comprises an isocyanate component, a polyol component (high molecular weight polyol, low molecular weight polyol, etc.), and a chain extender.

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, Examples include p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like. . These may be used alone or in combination of two or more.

Examples of the high molecular weight polyol include a polyether polyol typified by polytetramethylene ether glycol, a polyester polyol typified by polybutylene adipate, a polycaprolactone polyol, a reaction product of a polyester glycol such as polycaprolactone and an alkylene carbonate, and the like. Exemplified polyester polycarbonate polyol, polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the obtained reaction mixture with organic dicarboxylic acid, and polycarbonate obtained by transesterification reaction between polyhydroxyl compound and aryl carbonate A polyol etc. are mentioned. 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, 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, 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, or 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'-dia Nodiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4'-methylene-bis-methyl Anthranilate, 4,4'-methylene-bis-anthranilic acid, 4,4'-diaminodiphenylsulfone, N, N'-di-sec-butyl-p-phenylenediamine, 4,4'-methylene- Bis (3-chloro-2,6-diethylaniline), 4,4′-methylenebis (o-chloroaniline), 3,3′-dichloro-4,4′-diamino-5,5′-diethyldiphenylmethane, , 2-bis (2-aminophenylthio) ethane, trimethylene glycol di-p-aminobenzoate, 3,5-bis (methylthio) -2 Polyamines exemplified 4-toluenediamine, and the like. These may be used alone or in combination of two or more. However, since the polyamines are often colored themselves or resins formed using these are colored in many cases, it is preferable to blend them so as not to impair the physical properties and light transmittance. In addition, when a compound having an aromatic hydrocarbon group is used, the light transmittance on the short wavelength side tends to be lowered. Therefore, it is particularly preferable not to use such a compound. In addition, a compound in which an electron donating group such as a halogen group or a thio group or an electron withdrawing group is bonded to an aromatic ring or the like tends to decrease the light transmittance. Therefore, such a compound may not be used. Particularly preferred. However, you may mix | blend to such an extent that the light transmittance requested | required by the short wavelength side is not impaired.

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 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, more preferably 0.99 to 1.10. 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. From the viewpoint of stability and transparency of the polyurethane resin during polishing, an isocyanate-terminated prepolymer from an organic isocyanate and a polyol in advance. Is preferably synthesized, and a prepolymer method in which a chain extender is reacted with this is preferred. Further, the NCO wt% of the prepolymer is preferably about 2 to 8 wt%, more preferably about 3 to 7 wt%. 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. When there are bubbles in the light transmission region, the attenuation of the reflected light increases due to light scattering, and the polishing end point detection accuracy and the film thickness measurement accuracy tend to decrease. Therefore, in order to remove such bubbles and make the light transmission region non-foamed, it is preferable to sufficiently remove the gas contained in the material by reducing the pressure to 10 Torr or less before mixing the material. . Moreover, in the stirring process after mixing, in the case of the stirring blade type mixer normally used, it is preferable to stir at the rotation speed of 100 rpm or less so that bubbles may not mix. In addition, the stirring step is preferably performed under reduced pressure. Furthermore, since the rotation and revolution type mixer is difficult to mix bubbles even at high rotation, it is also preferable to perform stirring and defoaming using the mixer.

The production method of the light transmission region 9 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 Asker D hardness of the light transmission region 9 is preferably 30 to 60 degrees, more preferably 30 to 50 degrees. By using the light transmission region having the hardness, deformation of the light transmission region can be suppressed.

Examples of the material for forming the polishing region 8 include polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen-based resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, and olefin resin. (Polyethylene, polypropylene, etc.), epoxy resin, photosensitive resin, and the like. These may be used alone or in combination of two or more. The material for forming the polishing region may be the same or different from that of the light transmission region, but it is preferable to use the same type of material as that used for the light transmission region.

Polyurethane resin is a particularly preferable material as a material for forming a polishing region because it has excellent abrasion resistance and a polymer having desired physical properties can be easily obtained by variously changing the raw material composition.

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

The high molecular weight polyol to be used is not particularly limited, and examples thereof include the high molecular weight polyol. The number average molecular weight of these high molecular weight polyols 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. For this reason, the polishing region produced from this polyurethane becomes too hard, which causes scratches on the wafer surface. 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 2,000, polyurethane using this is too soft, and the polishing region produced from this polyurethane tends to have poor planarization characteristics.

Further, as the polyol, in addition to the high molecular weight polyol, the low molecular weight polyol can be used in combination.

Examples of chain extenders include 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, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino- 3,3′-diethyl-5,5′-dimethyldiphenylmethane, N, N′-di-sec-butyl-4,4′-diaminodiphenylmethane, 4 4'-diamino-3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diisopropyl-5 , 5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3,3', 5,5'-tetraisopropyldiphenylmethane, m- List polyamines exemplified by xylylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the low molecular weight polyol components described above. Can do. 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 variously changed depending on the molecular weight of each and the desired physical properties of the polishing region produced from these. In order to obtain a polishing region having excellent polishing characteristics, the number of isocyanate groups in the isocyanate component relative to the total number of functional groups (hydroxyl group + amino group) of the polyol component and the chain extender is preferably 0.95 to 1.15. Preferably it is 0.99 to 1.10.

The polyurethane resin can be produced by the same method as described above. In addition, stabilizers such as antioxidants, surfactants, lubricants, pigments, solid beads, fillers such as water-soluble particles and emulsion particles, antistatic agents, abrasive grains, and other materials as necessary. Additives may be added.

The polishing region is preferably a fine foam. By using a fine foam, the slurry can be held in the fine pores on the surface, and the polishing rate can be increased.

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 is especially preferable. Examples of the silicone surfactant include SH-192, L-5340 (manufactured by Toray Dow Corning Silicon) and the like as suitable compounds.

An example of a method for producing a micro-bubble type polyurethane foam will be described below. The manufacturing method of this polyurethane foam has the following processes.
1) Foaming step for producing a cell dispersion of isocyanate-terminated prepolymer A silicone-based surfactant is added to the isocyanate-terminated prepolymer (first component), and the mixture is stirred in the presence of a non-reactive gas to remove the non-reactive gas. Disperse as fine bubbles to obtain a cell dispersion. When the prepolymer is solid at normal temperature, it is preheated to an appropriate temperature and melted before use.
2) Curing Agent (Chain Extender) Mixing Step A chain extender (second component) is added to the above cell dispersion, mixed and stirred to obtain a foaming reaction solution. 3) Casting process The above foaming reaction liquid is poured into a mold.
4) Curing step The foaming reaction solution poured into the mold is heated to cause reaction curing.

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 silicone-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 that different stirring devices are used for stirring for creating the bubble dispersion in the stirring step and stirring for adding and mixing the chain extender in the mixing step. 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 production method of polyurethane foam, heating and post-curing the foam that has reacted until the foaming reaction liquid is poured into the mold and no longer flows is effective in improving the physical properties of the foam and is extremely suitable. It is. The foam reaction solution may be poured into the mold and immediately put into a heating oven for post cure, and heat is not immediately transferred to the reaction components under such conditions, so the bubble size does not increase. . The curing reaction is preferably performed at normal pressure because the bubble shape is stable.

In the production of a polyurethane resin, a catalyst that promotes a known polyurethane reaction such as a tertiary amine type or an organic tin type 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 may be produced by a batch method in which each component is metered into a container and stirred, and each component and a non-reactive gas are continuously supplied to the stirring device 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 average cell diameter of the polyurethane 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 (flatness) of the polished object (wafer) after polishing tends to decrease.

The specific gravity of the polyurethane 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 object 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 foam is preferably 45 to 70 degrees as measured by an Asker D hardness meter. When the Asker D hardness is less than 45 degrees, the planarity of the object to be polished is reduced. When the Asker D hardness is more than 70 degrees, the planarity is good but the uniformity of the object to be polished is reduced. There is a tendency.

The polishing region 8 is manufactured by cutting the polyurethane foam produced as described above into a predetermined size.

The polishing region 8 is provided with a groove 14 (uneven structure) for holding and renewing slurry on the polishing side surface in contact with the wafer. When the polishing region is formed of fine foam, it has many openings on the polishing surface and has the function of holding the slurry, but in order to more efficiently maintain the slurry and renew the slurry. Also, it is preferable to provide a groove on the surface on the polishing side in order to prevent dechucking error due to wafer adsorption, destruction of the wafer, and reduction in polishing efficiency. The groove 14 is not particularly limited as long as it has a surface shape that holds and renews the slurry. For example, an XY lattice groove, a concentric circular groove, a through hole, a non-through hole, a polygonal column, a cylinder, and a spiral groove , 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. Furthermore, 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 thickness of the polishing region 8 is not particularly limited, but is usually about 0.8 to 4 mm, preferably 1.2 to 2.5 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 depth of the groove 14 is not particularly limited, but is usually about 20 to 70% of the thickness of the polishing region 8 and preferably 20 to 50%.

The cushion layer 11 supplements the characteristics of the polishing region 8. The cushion layer 11 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 polishing object having minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire polishing object. The planarity is improved by the characteristics of the polishing region 8, and the uniformity is improved by the characteristics of the cushion layer 11. In the polishing pad of the present invention, the cushion layer 11 is preferably softer than the polishing region 8.

The material for forming the cushion layer 11 is not particularly limited. For example, 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 resins such as polyurethane foam and polyethylene foam Examples thereof include rubber resins such as foam, butadiene rubber and isoprene rubber, and photosensitive resins.

2 is provided with an adhesive layer on one or both sides of a highly transparent resin film. Examples of the resin film material include polyesters such as polyethylene terephthalate, polyethylene, polypropylene, polystyrene, polyimide, polyvinyl alcohol, polyvinyl chloride, fluorine-containing resins such as polyfluoroethylene, nylon, cellulose, and general-purpose engineering plastics such as polycarbonate; Special engineering plastics such as polyetherimide, polyetheretherketone, and polyethersulfone can be mentioned. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. The adhesive layer of the transparent support film 12 is provided to bond the resin film to the cushion layer 11 or the polishing surface plate 2 and to bond the light transmission region 9 to the resin film.

The thickness of the resin film is not particularly limited, but is preferably about 20 to 200 μm from the viewpoint of transparency and strength.

The transparent support film 12 needs to have at least a size that completely closes the opening 10, and usually has the same size as the cushion layer 11.

The manufacturing method of the polishing pad 1 in FIG. 2 is not particularly limited, and various methods are conceivable. Specific examples will be described below.

Case 1
The polishing region 8 and the cushion layer 11 are bonded together, and then an opening 10 that penetrates the polishing region 8 and the cushion layer 11 is formed. Thereafter, the transparent support film 12 is bonded to one side of the cushion layer 11. Then, the light transmission region 9 is installed in the opening 10 and on the transparent support film 12.

Case 2
The polishing region 8 and the cushion layer 11 are bonded together, and then an opening 10 that penetrates the polishing region 8 and the cushion layer 11 is formed. Thereafter, the transparent support film 12 is bonded to one side of the cushion layer 11. And the light transmissive area | region 9 is formed by inject | pouring a light transmissive resin composition in the opening part 10 and on the transparent support film 12, and making it harden | cure by heating, light irradiation, or moisture.

Further, the manufacturing method of the polishing pad 1 in FIG. 3 is not particularly limited. For example, the polishing region 8 provided with the through-hole 15 and the cushion layer 11 provided with the through-hole 16 are bonded to the adhesive layer of the double-sided adhesive sheet 13 so that the through-holes overlap each other, and then the through-hole 15 It can be manufactured by attaching the light transmission region 9 to the adhesive layer inside. A double-sided tape may be provided on the surface of the cushion layer 11 to be bonded to the polishing surface plate (platen).

As shown in FIGS. 2 and 3, the surface of the light transmission region 9 needs to be recessed from the surface of the polishing region 8, and the amount of the recess is 30 to 100% of the depth of the groove 14, preferably 50 to 100%, more preferably 80 to 100%.

Examples of means for bonding the polishing region 8 and the cushion layer 11 include a method in which the polishing region 8 and the cushion layer 11 are sandwiched between the double-sided adhesive sheets 13 and pressed. The double-sided adhesive sheet 13 has a general configuration in which an adhesive layer is provided on both sides of a substrate such as a nonwoven fabric or a film, and is generally called a double-sided tape. 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. Moreover, since the composition may differ between the grinding | polishing area | region 8 and the cushion layer 11, it is also possible to make the composition of each adhesive bond layer of the double-sided adhesive sheet 13 different, and to optimize the adhesive force of each layer.

The means for forming the opening 10 and the through

holes

15 and 16 are not particularly limited. For example, a method of pressing or grinding with a cutting tool, a method of using a laser such as a carbonic acid laser, and the shape of the through hole are provided. For example, a method may be used in which a raw material is poured into a mold and cured. The size and shape of the opening 10 and the through

holes

15 and 16 are not particularly limited.

The semiconductor device is manufactured through a process 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 5 (polishing head) 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.

Thus, 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.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[Measurement and evaluation method]

(Scratch measurement)
Using ARW-8C1A (manufactured by MAT) as a polishing apparatus, scratches were evaluated using the prepared polishing pad. As polishing conditions, ceria slurry (manufactured by Hitachi Chemical Co., Ltd.) was added as a slurry at a flow rate of 150 ml / min. The polishing load was 350 g / cm ² , the polishing platen rotation speed was 65 rpm, and the wafer rotation speed was 60 rpm. Four 8-inch dummy wafers were polished under the above conditions, and then an 8-inch wafer on which a thermal oxide film having a thickness of 10,000 mm was deposited was polished for 1 minute. Then, using a defect evaluation apparatus (Surfscan SP1) manufactured by KLA Tencor, the number of streaks of 0.19 μm or more on the polished wafer was measured.

Example 1
[Production of light transmission region]
A thermoplastic polyurethane A1098A (manufactured by Toyobo Co., Ltd.) was used to produce a light transmission region (length 60 mm, width 20 mm, thickness 2.4 mm, D hardness 48 degrees) by injection molding.

[Production of polishing area]
In a reaction vessel, 100 parts by weight of a polyether-based prepolymer (manufactured by Uniroyal, adiprene L-325, NCO concentration: 2.22 meq / g), and a silicone-based surfactant (manufactured by 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, 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 (average cell diameter 50 μm, specific gravity 0.86, D hardness 55 degrees). 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 (thickness: 2.0 mm). This buffed sheet is punched out to a diameter of 61 cm, and a concentric groove having a groove width of 0.40 mm, a groove pitch of 3.1 mm, and a groove depth of 0.76 mm is used on the surface using a groove processing machine (manufactured by Toho Steel Co., Ltd.). Processing was performed. Using a laminator on the surface opposite to the grooved surface of this sheet, double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape, thickness: 0.10 mm) is bonded to produce a polishing area with double-sided tape. did.

[Production of polishing pad]
A cushion layer made of polyethylene foam (Toray Industries Inc., TORAYPEF, thickness: 0.8 mm) buffed and corona-treated is bonded to the adhesive surface of the prepared polishing area with double-sided tape using a laminator. An abrasive sheet was prepared. Next, an opening having a size of 60 mm × 20 mm was formed in the polishing sheet. And the transparent support film (base material: polyethylene terephthalate, thickness: 50 micrometers) which has an adhesive bond layer on both surfaces was bonded together to the cushion layer of the polishing sheet, and the laminated body was obtained. Thereafter, a light transmission region was pasted on the transparent support film in the opening of the laminate to prepare a polishing pad having the structure shown in FIG. The amount of depression in the light transmission region was 0.5 mm, which was 65.8% of the groove depth.

Examples 2 to 4, Comparative Examples 1 and 2
A polishing pad was prepared in the same manner as in Example 1 except that the groove depth in the polishing region and the thickness of the light transmission region were changed to change the dent amount to the value shown in Table 1.

Example 5
[Production of light transmission region]
128 parts by weight of a polyester polyol (number average molecular weight 2400) 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 1.5 mm) was prepared by injection molding.

[Production of polishing area]
A sheet having a diameter of 61 cm and a thickness of 2.0 mm having a concentric groove having a groove width of 0.40 mm, a groove pitch of 3.1 mm, and a groove depth of 0.76 mm was produced in the same manner as in Example 1. A through-hole (56 mm × 20 mm) was formed at a position of about 12 cm from the center of the substrate to prepare a polished region.

[Production of polishing pad]
Using a laminator on the surface opposite to the grooved surface of the prepared polishing region, a double-sided tape (manufactured by Sekisui Chemical Co., Ltd., double tack tape) was bonded to prepare a polishing region with double-sided tape. Using a laminator on one side (surface on the polishing surface plate side) of a cushion layer made of polyethylene foam (Toray Industries, Toraypef, thickness: 0.8 mm) buffed and corona-treated, a polishing surface plate A double-sided tape for laminating was laminated to a diameter of 61 cm to produce a cushion layer with a double-sided tape. A through hole (50 mm × 14 mm) was formed at a position of about 12 cm from the center of the cushion layer with the double-sided tape. The structure shown in FIG. 3 is formed by laminating the polishing region with double-sided tape and the cushion layer with double-sided tape so that the through-holes overlap each other, and further bonding the produced light transmission region to the adhesive layer in the through-hole of the polishing region. A polishing pad was prepared. The amount of depression in the light transmission region was 0.5 mm, which was 65.8% of the groove depth.

Comparative Example 3
A polishing pad was produced in the same manner as in Example 5 except that the thickness of the light transmission region was changed and the dent amount was changed to the value shown in Table 1.

The polishing pad of the present invention provides stable and high leveling of flattening of optical materials such as lenses and reflecting mirrors, silicon wafers, aluminum substrates, and materials requiring high surface flatness such as general metal polishing. Can be done with efficiency. 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. Can be used for

1: Polishing pad 2: Polishing surface plate (platen)
3: Abrasive (slurry)
4: Polishing object (semiconductor wafer)
5: Support base (polishing head)
6, 7: Rotating shaft 8: Polishing area 9: Light transmission area 10: Opening part 11: Cushion layer 12: Transparent support film 13: Double-sided adhesive sheet 14: Grooves 15, 16: Through-hole

Claims

In a polishing pad having a polishing layer having a polishing region and a light transmission region, the polishing region has a groove on the surface, the surface of the light transmission region is recessed from the surface of the polishing region, and the amount of the recess is the groove. A polishing pad characterized by being 30 to 100% of the depth of the surface.
In the polishing pad, a polishing region, a cushion layer, and a transparent support film are laminated in this order, and a light transmission region is provided in an opening that penetrates the polishing region and the cushion layer and on the transparent support film. Item 10. A polishing pad according to Item 1.
The polishing pad is formed by laminating a polishing layer having a polishing region and a light transmission region and a cushion layer having a through hole via a double-sided adhesive sheet so that the light transmission region and the through hole overlap. The polishing pad according to claim 1.
A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing pad according to any one of claims 1 to 3.