JPWO2004090963A1 - Polishing pad, manufacturing method thereof, and polishing method using the same - Google Patents

Abstract

A polishing pad comprising a fiber containing organic fibers and a matrix resin holding the fibers, and at least the organic fibers are exposed on the surface of the object to be polished at least after dressing. Thereby, generation | occurrence | production of the fine grinding | polishing damage | wound of a to-be-polished object can be suppressed, and flat grinding | polishing can be performed by low load. Further, the polishing end point of the object to be polished can be managed without polishing scratches by the system for detecting the polishing state of the object to be polished by an optical method. For this reason, for example, in the manufacturing process of a semiconductor device, polishing with a low load on the interlayer insulating film and excellent flatness can be performed, and the next generation dual damascene method can be easily performed.

Description

  The present invention relates to a polishing pad used for chemical mechanical polishing (CMP) in semiconductor device manufacturing technology and the like, precision polishing in hard disk manufacturing technology, a manufacturing method thereof, and a polishing method using the polishing pad.

Current ultra-large scale integrated circuits tend to increase packaging density, and various microfabrication technologies are being researched and developed. The design rules are already in the sub-half micron order. One of the techniques that have been developed in order to satisfy such demands for strict miniaturization is a CMP (chemical mechanical polishing) technique. This technique contributes to completely flattening the layer to be exposed in the semiconductor device manufacturing process, reducing the burden of the exposure technique, and stabilizing the manufacturing yield at a high level, and performs the following polishing. Is. The object to be polished is pressed against the polishing pad, and while the slurry-like CMP polishing liquid is supplied between the object to be polished and the polishing pad, the polishing pad is relatively slid between the object to be polished, The required amount of film on the surface of the polished object is precisely removed. For this reason, for example, this technique is indispensable when performing flattening of interlayer insulating films and BPSG films, shallow trench isolation, and the like.
A polishing pad made of foamed or non-foamed organic resin has been used as a polishing pad used for these CMP techniques (refer to Japanese Patent Publication No. 8-511210, claims and background of the invention). For example, a foamed urethane resin sheet in which concentric or lattice-shaped grooves are formed is generally used.
Here, damage (polishing scratches) to the polished surface due to abrasive grains and polishing waste is a problem. In the case of a normal foamed or non-foamed organic resin polishing pad, it is very effective to reduce the hardness of the polishing pad in order to reduce polishing scratches. However, when this hardness is lowered, the polishing rate is reduced, and the dishing of the trench portion tends to deteriorate. It was difficult to satisfy these simultaneously.
On the other hand, from the initial Al wiring, the embedded wiring by dual damascene using Cu having a low electric resistance as a wiring metal and a low dielectric constant material as an interlayer insulating film has become mainstream.
In such a dual damascene method, selection of a polishing pad in addition to selection of a polishing liquid has become extremely important. In particular, the metal is rich in chemical reactivity as compared with the interlayer insulating film and is soft, so that defects due to polishing scratches and corrosion are likely to occur. On the other hand, dishing is more likely to be deformed, that is, the smaller the elastic modulus. However, increasing the elastic modulus of the pad generally increases the pad hardness, which causes defects such as polishing scratches.
In addition, the application of low dielectric constant materials to interlayer insulating films, which has been promoted in recent years, is accompanied by a decrease in the mechanical properties of the insulating layer and a decrease in adhesion to metal, which causes defects during polishing. Therefore, a polishing system with a smaller mechanical load during polishing is required.
Further, in the shallow trench isolation process, the metal wiring polishing process in the dual damascene method, and the interlayer insulating film polishing process, it is necessary to manage an appropriate polishing amount at the time of CMP polishing. In addition to strict polishing time management, this method includes a method of detecting torque fluctuations due to friction between the pad and wafer during polishing of the motor that drives the polishing apparatus, and the capacitance of the object to be polished. There is also a method to measure. However, a polishing apparatus equipped with a sensor that optically detects a change in the surface state of the wafer accompanying polishing has also been used, and laser light or infrared light is applied to the polishing surface of the wafer through a polishing pad from the polishing apparatus side. A technique for managing the polishing state of a wafer by irradiating and detecting the reflected light again through a polishing pad with a sensor of a polishing apparatus is becoming mainstream. In particular, the shallow trench isolation process, dual damascene method, etc. expose a barrier film on the wafer surface at the end of polishing, so if a suitable wavelength of light is used for detection, a large change in reflectance can be obtained. This technique is useful. In the step of polishing the insulating film having no barrier film, the polishing amount can be detected by interference between the reflected light from the wafer surface and the reflected light from the silicon layer under the insulating film. As a typical example of the polishing pad used in this optical method, a polishing pad in which a transparent window material that transmits light is inserted into a part of a polyurethane foam resin plate is used. In addition, a technique for transmitting light to a polishing pad made of a non-foamed resin such as polyurethane, polycarbonate, nylon, acrylic polymer, or polyester has been proposed (see, for example, US Pat. No. 5,605,760). However, these polishing pads optically detect the end point and at the same time have problems of reducing polishing scratches and ensuring the polishing speed during CMP polishing. Especially in the damascene method, the generation of defects due to polishing scratches and corrosion is reduced as described above. is important.

The present invention has been found by variously examining the structure of a polishing pad in order to solve the above problems.
The present invention relates to planarization and metal wiring formation efficiency in CMP technology used for planarization of an interlayer insulating film, a BPSG film, a shallow trench isolation insulating film, and the like in a semiconductor element manufacturing process, and formation of a metal wiring portion. It is intended to provide a polishing pad capable of suppressing scratches on the polishing surface and defects of the insulating layer simultaneously with practical implementation, a method for producing the same, and a polishing method using the polishing pad. In addition, the surface of the object to be polished such as a semiconductor wafer is irradiated with light through a polishing pad, the change in the reflectance is detected, and the light transmission suitable for use in a polishing process for managing the polishing end point is provided. A polishing pad that suppresses generation of polishing flaws on an object to be polished, and a polishing method for polishing using the polishing pad are provided.
The present invention relates to (1) a polishing pad comprising an organic fiber-containing fiber and a matrix resin holding the fiber, and at least the organic fiber is exposed on the surface of the object to be polished.
Further, the present invention is characterized in that (2) a fiber containing organic fibers and a matrix resin holding the fibers, and at least the organic fibers are exposed on the surface of the object to be polished after the dressing process. The present invention relates to a polishing pad.
The present invention relates to (3) the polishing pad according to (1) or (2), wherein the matrix resin contains at least one thermoplastic resin.
The present invention relates to (4) the polishing pad according to any one of (1) to (3), wherein the matrix resin comprises a semicrystalline thermoplastic resin.
The present invention relates to (5) the polishing pad according to any one of (1) to (4), wherein an elastomer is dispersed in a matrix resin.
The present invention relates to (6) the polishing pad according to (5), wherein the glass transition point of the elastomer is 0 ° C. or lower.
The present invention relates to (7) the polishing pad according to any one of (1) to (6), wherein the fibers are made of an aromatic polyamide.
The present invention relates to (8) the polishing pad according to any one of (1) to (7), comprising 1 to 50% by weight of organic fibers.
The present invention relates to (9) the polishing pad according to any one of (1) to (8), wherein the organic fiber has a diameter of 1 mm or less.
The present invention relates to (10) the polishing pad according to any one of (1) to (9), wherein the organic fiber has a length of 1 cm or less.
The present invention relates to (11) the polishing pad according to any one of (1) to (10), wherein the abrasive particles are held by organic fibers exposed on the surface to be polished.
The present invention relates to (12) the polishing pad according to any one of (1) to (11), wherein the exposed organic fiber has a maximum exposed portion length of 0.1 mm or less.
The present invention relates to (13) the polishing pad according to (12), wherein the exposed organic fiber is made of polyester.
The present invention relates to (14) the polishing pad according to (12) or (13), wherein chopped polyester fibers are dispersed in a matrix resin.
The present invention relates to (15) the polishing pad according to (12) or (13), wherein a polyester nonwoven fabric is laminated in a matrix resin.
The present invention is (16) a polishing pad useful for optically detecting the polishing end point during polishing of the surface of an object to be polished, and a substantially non-foamed matrix containing 1 to 20% by weight of organic fibers (1), (2) to (4), (7), (9) made of resin, having a function of transporting and holding abrasive slurry particles, and transmitting light having a wavelength in the range of 190 to 3500 nm It is related with the polishing pad in any one of-(11).
The present invention is (17) a polishing pad useful for optically detecting the polishing end point during polishing of the surface of an object to be polished, comprising a portion through which light having a wavelength in the range of 190 to 3500 nm is transmitted, The portion is made of a substantially non-foamed matrix resin containing 1 to 20% by weight of organic fibers, and has a function of transporting and holding abrasive slurry particles. (1), (2) to (4) , (7), and (9) to the polishing pad according to any one of (11).
The present invention relates to (18) the polishing pad according to (16) or (17), wherein the organic fiber is an aramid fiber.
The present invention is (19) a method for producing a polishing pad that is used by being attached to a surface plate to flatten the surface to be polished, and comprising mixing a fiber composition containing an organic fiber and a matrix composition containing a thermoplastic resin. The present invention relates to a method for producing a polishing pad comprising a step of obtaining a mixture, a step of converting the mixture into pellets or tablets, and a step of processing the pellets or tablets into a plate or sheet by extrusion molding or injection molding.
The present invention is (20) a method of manufacturing a polishing pad that is used by being attached to a surface plate to flatten the surface to be polished, and is impregnated with a matrix resin composition impregnated into a fiber substrate containing organic fibers. The present invention relates to a method for producing a polishing pad comprising a step of producing a sheet-like fiber substrate, and a step of laminating the sheet-like fiber substrate including the resin-impregnated sheet-like fiber substrate and subjecting the sheet-like fiber substrate to heating and pressing.
The present invention relates to (21) the method for producing a polishing pad according to the above (19) or (20), which further comprises a step of exposing fibers on the surface.
In the present invention, (22) the surface to be polished of the object to be polished is pressed against the organic fiber exposed surface of the polishing pad according to any one of (1) to (18), and the polishing liquid is interposed between the surface to be polished and the polishing pad. The present invention relates to a polishing method in which a surface to be polished is polished by relatively sliding an object to be polished and a pad while supplying to the surface.
(23) The polishing according to (22), wherein the surface to be polished comprises a laminate in which a conductor layer and a copper layer are further coated on an insulating layer having a dielectric constant of 2.7 or less in which wirings and trenches are formed. Regarding the method.
The present invention relates to (24) a polishing method for optically detecting a polishing end point using the polishing pad according to any one of (16) to (18).
The organic fibers exposed on the surface relieve stress between the abrasive grains and foreign matters in the polishing liquid and the object to be polished during polishing, and prevent the surface of the object to be scratched from being generated. Further, in the conventional polishing pad made of only a general resin, the foam holes and the large and small grooves on the surface provide the ability to transport and hold the abrasive grains of the polishing liquid, but the polishing pad of the present invention is exposed on the surface. The organic fiber has the ability to transport and retain abrasive grains of the polishing liquid, and plays a role in obtaining a polishing rate and improving flatness uniformity.

The structure of the polishing pad of the present invention comprises a fiber containing organic fibers and a matrix resin holding the fibers. The organic fibers may be part or all of the fibers, and the fibers may include inorganic fibers such as glass fibers in addition to the main organic fibers.
Further, there is no particular limitation as long as at least the organic fiber is exposed on the surface to be polished. In the present invention, the term “exposed organic fibers” includes the surface to be polished after dressing treatment, that is, at least the organic fibers are exposed at least during use.
Specific examples of the structure of the polishing pad include a structure in which chopped fibers are dispersed in a matrix resin, and a structure in which nonwoven fabrics or woven fabric fibers are laminated in a matrix resin.
As the matrix resin for holding the fibers of the polishing pad of the present invention, ordinary thermosetting resins and thermoplastic resins can be used without any particular limitation. A resin belonging to a class having a relatively high elastic modulus, for example, a resin having a room temperature elastic modulus of 0.1 GPa or more, more preferably 0.5 GPa or more, is preferable. If the elastic modulus is small, the flatness tends to deteriorate.
As the thermosetting resin, for example, epoxy resins such as bisphenol A type epoxy resin and cresol novolac type epoxy resin, unsaturated polyester resin, acrylic resin, polyurethane resin and the like can be used. These may be used alone or in admixture of two or more. When these thermosetting resins are epoxy resins, a curing agent, a curing accelerator and the like are usually blended. As the curing agent, dicyandiamide, organic acid, organic acid anhydride, polyamine or the like can be used, and as the curing accelerator, for example, 2-ethyl-4-methylimidazole or the like can be used.
Examples of the thermoplastic resin include polycarbonate, polymethyl methacrylate, AS (acrylonitrile-styrene copolymer), ABS (acrylonitrile-butadiene rubber-styrene copolymer), polyethylene, polypropylene, polybutene, and 4-methyl-pentene-1. , Ethylene-propylene copolymer, ethylene vinyl acetate copolymer, polyester, polyamide, polyamideimide, polyacetal and the like. These may be used alone or in admixture of two or more. In particular, if a semi-crystalline thermoplastic polymer resin is used as the matrix resin, a highly durable polishing pad having excellent wear resistance can be obtained.
1st embodiment of the polishing pad of this invention is a polishing pad in which the said matrix resin contains at least 1 type of thermoplastic resin. Here, the matrix resin can be used without particular limitation as long as it contains at least one kind of thermoplastic resin, and the thermoplastic resin is preferably the main component.
In a second embodiment of the polishing pad of the present invention, the maximum exposed portion length of the organic fiber exposed on the surface to be polished is 0.1 mm or less. Here, the maximum exposed portion length of the exposed organic fiber is the length of the exposed portion of the fiber that is substantially fixed to the surface of the polishing pad, and refers to the maximum length. In practice, measurement is possible by observing about 5 or more points on the pad surface using an SEM (scanning electron microscope) or the like.
A third embodiment of the polishing pad of the present invention is a polishing pad useful for optically detecting a polishing end point during polishing of the surface of an object to be polished, part or all of which is 190 to 3500 nm. It is a polishing pad that is substantially non-foamed matrix resin that transmits light in the wavelength range and contains 1 to 20% by weight of organic fiber, and that has a function of transporting and holding abrasive slurry particles.
Regarding the matrix resin, particularly in the first embodiment, in addition to the thermoplastic resin, a cross-linked and non-cross-linked elastomer, a cross-linked polystyrene, a cross-linked polymethyl methacrylate, and the like as additives are further mixed and dispersed in the matrix resin. Also good. It is more preferred to add a thermoplastic elastomer and an elastomer with a low degree of crosslinking. The elastomer can be used without particular limitation as long as it has a glass transition point of room temperature or lower, and more preferably 0 ° C. or lower. Examples thereof include elastomers such as olefinic elastomers, styrene elastomers, urethane elastomers, ester elastomers, alkenyl aromatic compound-conjugated diene copolymers, and polyolefin copolymers. As the amount of these elastomers added increases, the impact resistance becomes higher and the resin becomes tenacious, and the frictional force between the pad surface and the metal increases.
As the organic fiber in the polishing pad of the present invention, materials that can be made into a fibrous form such as aramid, polyester, polyimide, and the like can be widely used. In addition, two or more of these can be selected and mixed.
From the viewpoint of the durability of the pad and the retention of the abrasive grains by the fibers, it is preferable to select an aramid, that is, an aromatic polyamide fiber as the main component, and more preferably an aramid fiber alone. That is, the aramid fiber has higher tensile strength than other general organic fibers, and when the surface of the polishing pad of the present invention is mechanically roughened to expose the fiber, the fiber tends to remain on the surface. This is because it is effective for holding particles. It also has the effect of improving the durability of the polishing pad and extending the service life. Aramid fibers are particularly preferable in the case of the first and third embodiments.
The aramid fiber has a para type and a meta type, and the para-type aramid fiber is more suitable because it has higher mechanical strength and lower moisture absorption than the meta type fiber. As the para-aramid fiber, poly p-phenylene terephthalamide fiber and poly p-phenylene diphenyl ether terephthalamide fiber are commercially available and can be used.
Further, from the viewpoint of adjusting the maximum exposure length and the surface roughness, it is preferable to use polyester as a main component as the organic fiber. This is because when the fibers of the polishing pad are exposed, the maximum exposed length can be reduced because the shear strength of the polyester fibers is smaller than that of the hard fibers. It is particularly preferable for the polishing pad of the second embodiment. On the other hand, when other hard fibers such as aramid fiber and polyimide fiber are used, the maximum exposed length is adjusted by refining the grindstone particle size used. At this time, since the roughness of the pad surface depends on the grain size of the grindstone, the irregularities on the surface of the pad inevitably are affected and affect the polishing rate. On the other hand, when polyester is used, the exposed length hardly changes even if a grindstone having any particle diameter is used. Therefore, the surface roughness of the pad itself can be arbitrarily adjusted while the fiber length is constant.
Here, you may mix and use the said other hard fiber with a polyester fiber. At this time, the ratio of the polyester fiber is desirably 40 to 100% by weight, preferably 70 to 100% by weight, and more preferably 80 to 100% by weight. When there are many polyester fibers, a fiber exposure layer will become small, and conversely, when there are many hard fibers, it will become thick and will tend to deteriorate flatness.
An organic fiber having a fiber diameter (diameter) of 1 mm or less can be preferably used, and is preferably 200 μm or less. Preferably it is 1-200 micrometers, More preferably, it is 5-150 micrometers. If it is too thick, the mechanical strength is too high, which may cause polishing scratches or defective dresses. If it is too thin, the handleability may be reduced, or the durability of the pad may be reduced due to insufficient strength.
The fiber length is not particularly limited, but in the case of a polishing pad in which the fibers are dispersed in a chopped form in the resin, the fiber length is preferably 10 mm or less, and more preferably 5 mm or less. More preferably, it is 0.1-3 mm. If it is too short, the exposed fiber will not be effectively held in the pad when the pad surface is mechanically roughened. If it is too long, it may become difficult to mold due to thickening when mixed with resin. . Even if these use the chop which cut | disconnected the short fiber to predetermined length, the thing of several types of fiber lengths can also be mixed and used.
Moreover, in order to improve the affinity with the resin, the fiber surface may be roughened mechanically or chemically in advance, or may be modified with a coupling material or the like. From the viewpoint of handling, a bundle of short fiber chops coated with a very small amount of resin can be used. However, this is only required to have a holding power enough to disperse the short fibers in the matrix resin by heating during mixing with the matrix resin or by an applied shearing force.
In addition, for a polishing pad in which a nonwoven fabric or a woven fabric is laminated, when using a nonwoven fabric, the same fibers as described above having a length of 1 mm or more are formed into a sheet shape by using the fusion force of the fibers themselves or an adhesive. Can be used. As the adhesive, an adhesive made of an epoxy resin such as a water-soluble epoxy resin binder can be used. When the adhesive is used, the amount is not particularly limited, but is preferably 3 to 20 parts by weight, more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the fiber. In the case of a woven fabric in which long fibers are woven, the weaving method can be used without any particular limitation. A polishing pad in which such fibers are laminated is particularly suitable for the polishing pad of the second embodiment of the present invention.
The unit weight of the above nonwoven fabric and woven fabric is 36-100 g / m. ² Preferably, it is 55 to 72 g / m. ² It is more preferable that
The content of the organic fiber is not particularly limited, but when chopped fiber is used for the entire pad, it is preferably 1 to 50% by weight, more preferably 1 to 20% by weight, even more preferably. Is 5 to 20% by weight. If the amount of fibers is small, the polishing scratches on the polished surface become prominent, and if the amount is too large, the moldability tends to deteriorate. On the other hand, in the case of a woven fabric and a nonwoven fabric, 50 weight% or more is preferable, More preferably, it is 60 to 80 weight%.
In particular, in the case of the third embodiment, the content of the organic fiber in the portion having the light transmittance needs to be within a range in which the polished state of the wafer can be detected without impeding the light transmittance. Therefore, 1 to 20% by weight of the entire polishing pad is preferable, and more preferably 2 to 10% by weight. If the amount of fiber is small, polishing scratches on the polished surface become prominent, and if it is too large, moldability tends to deteriorate.
The polishing pad can be produced by a method in which fibers are dispersed and molded in a resin composition as a matrix, a woven fabric or non-woven fabric containing fibers is impregnated with a resin varnish to obtain a prepreg, and laminated. However, it is not limited to these.
Below, the manufacturing method of the polishing pad of this invention is demonstrated.
The first production method is a process of mixing a fiber containing organic fibers and a matrix resin composition to obtain a mixture, a process of making the mixture into pellets or tablets, and a plate-like by extrusion or injection molding of the pellets or tablets. Or the process of processing into a sheet form is included. A second production method includes a step of producing a resin-impregnated sheet-like fiber base material by impregnating a fiber base material containing organic fibers with a matrix resin composition, a sheet-like fiber base material containing the resin-impregnated sheet-like fiber base material The process of laminating and applying heat and pressure forming is included. The fiber substrate preferably contains mainly polyester fibers.
The preparation of the matrix resin composition for producing the polishing pad of the present invention and the method of mixing with the fiber can be carried out by a conventionally known method and are not particularly limited.
That is, when the chopped fiber is dispersed as it is in the matrix resin composition as the first production method, for example, each resin composition forming the matrix is uniformly mixed with a Henschel mixer, a super mixer, a turntable mixer, a ribbon blender, or the like. After (dry blending), it is melt kneaded with a single screw extruder, a twin screw extruder, a Banbury mixer, or the like. Further, fibers are added and melt-mixed in the same manner. Then, it is cooled and tableted or pelletized. When water is used for cooling, it must be sufficiently dried and dehydrated.
The obtained tablet or pellet is again extruded through a die with an extrusion molding machine and rolled with a roll, whereby a sheet-like or plate-like molding can be produced. As another manufacturing method, a sheet-like or plate-like molded article may be formed by injection molding into a mold instead of the extrusion molding.
On the other hand, when the matrix resin composition is a liquid thermosetting resin composition, a predetermined amount of chopped fibers are dispersed in the liquid thermosetting resin composition, and after pouring into a mold or the like to remove bubbles by decompression, By proceeding with heat curing, a molded product can be obtained. Similarly to the above, it may be produced by pressurizing and pouring into a mold in a heated state.
The second manufacturing method can also be performed by a conventionally known method, and is particularly suitable for manufacturing the polishing pad of the second embodiment. For example, when a woven fabric or a nonwoven fabric is used as the fiber substrate, the resin-impregnated sheet-like fiber substrate or the resin-impregnated sheet-like fiber substrate and the resin-unimpregnated sheet-like fiber substrate (that is, woven or nonwoven fabric) Prepare. These can be integrated by heating and pressing to obtain a molded product. At this time, it is preferable that an organic fiber is exposed on the surface by disposing a resin-unimpregnated sheet-like fiber base material on at least one surface.
The resin-impregnated sheet-like fiber base material is obtained by impregnating a resin composition into a resin-unimpregnated sheet-like fiber base material, and is usually called a prepreg. The method for preparing the prepreg is not particularly limited, but it can be obtained by preparing a varnish in which the above matrix resin composition components are dissolved in an organic solvent, impregnating the resin-unimpregnated sheet-like fiber base material, and then drying by heating. it can. The type of the solvent can be used without particular limitation as long as it can dissolve the resin composition uniformly. For example, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetone, lower alcohols such as ethyl alcohol, propyl alcohol, and isopropyl alcohol, amides such as dimethylformamide, formamide, and the like can be used as a mixture. Is possible. The fiber content in the resin-impregnated sheet-like fiber base material is desirably 60 to 140 parts by weight, and preferably 90 to 120 parts by weight, with respect to 100 parts by weight of the resin composition and the adhesive. More preferred.
Further, the ratio of the resin-unimpregnated sheet-like fiber base material to the whole is determined in consideration of the fiber content in the polishing pad, particularly the organic fiber content of the surface layer that is pressed against the object to be polished. . According to this method, in order to change the fiber content of the polishing pad, it is not necessary to change the resin content at the time of manufacturing the prepreg, and it can be adjusted by changing the usage ratio of the resin-impregnated sheet-like fiber base material. It is.
In heating and pressing, generally, the heating temperature is usually 150 to 200 ° C., and the pressure is 50 to 500 kPa. These can be appropriately adjusted depending on the type and content of the thermosetting resin used.
These molded products are appropriately processed in accordance with the shape of the surface plate of a predetermined polishing apparatus as required to obtain a final product polishing pad. As an example, it is possible to obtain a polishing pad which is a final product by cutting the sheet-like molded product into a circular shape.
The entire thickness of the polishing pad is preferably 0.1 to 5 mm, and more preferably 0.5 to 2 mm. In addition, grooves that serve as a flow path for the polishing liquid and polishing debris may be formed on the polishing surface of the pad in a concentric or lattice shape using an NC lathe or the like.
In order to obtain a polishing pad in which at least organic fibers are exposed on the surface of the object to be polished according to the present invention, the surface of the object to be polished side of the pad is treated as necessary to expose the fibers. As a method of forming this exposed fiber, a dressing process, that is, a method of scraping off the resin on the pad surface using a grindstone such as diamond and exposing the fiber can be employed. A wire brush, a metal scraper, a resin brush, glass or a ceramic plate may be used instead of the grindstone.
These use conditions need to be well adjusted to control the exposed length of the fiber. The maximum exposed fiber length greatly depends on the hardness of the fiber, but if polyester fiber is used for the pad, it can be easily adjusted to be short.
In general, the maximum length of the portion exposed on the surface of the organic fiber can be practically 1 mm or less, and is desirably 200 μm or less. More preferably, it is 1-200 micrometers, More preferably, it is 10-150 micrometers. If it is too short, the retention of the polishing liquid will decrease and the polishing rate will decrease, and if it is too long, the flatness will tend to be adversely affected.
In particular, the polishing pad of the second embodiment of the present invention has a maximum exposed portion length of the exposed organic fiber of 0.1 mm or less. Here, the maximum exposed portion length can be used without particular limitation as long as it is 0.1 mm or less, preferably 1 to 50 μm, more preferably 1 to 25 μm. If the maximum exposed portion length increases, the flatness decreases, and if it decreases, the polishing rate tends to decrease.
Such organic fibers exposed on the surface of the object to be polished can efficiently hold abrasive particles (abrasive grains) in a polishing liquid, which will be described later, during polishing.
Next, the polishing pad of 3rd embodiment of this invention is demonstrated. This polishing pad optically detects the polishing amount of an object to be polished, manages its end point, and suppresses generation of polishing flaws during polishing while maintaining a high polishing rate and uniformity. Such a configuration can be realized by devising the structure of the polishing pad, the resin composition, the filler, and the like.
The structure of this polishing pad is such that the material of the polishing pad is transparent to light having a wavelength in the range of 190 to 3500 nm, or a part of the polishing pad is formed of this light-transmitting material. Is. In the latter case, for example, the member of the polishing pad is formed into a small piece and inserted as a window material for transmitting light to a part of another polishing pad that does not have sufficient light transmittance.
Thus, since the polishing pad or a part thereof transmits light having a wavelength in the range of 190 to 3500 nm, the polishing surface of the object to be polished is irradiated with light through the polishing pad to change the reflectance. By detecting, the polishing end point can be managed. In the present invention, transmitting light having a wavelength in the range of 190 to 3500 nm usually means that the transmittance of the light of this wavelength of the polishing pad or a part thereof before exposing the organic fiber is 10 to 100%. means. This transmittance is preferably 30 to 100%.
As a matrix resin used for such a light-transmitting material, a resin belonging to a class having a relatively high elastic modulus is preferable, and the above-described resins can be used without particular notice. In particular, if a semi-crystalline thermoplastic polymer resin is used, a highly durable polishing pad having excellent wear resistance can be obtained. Moreover, it is preferable that this resin is a form which does not have a foaming hole substantially. This is because the form having the foamed holes hinders light transmission and impairs detection of the polished state of the wafer. As the organic fiber, it is preferable to select an aramid fiber alone or as a main component.
The manufacturing method is the same as the manufacturing method described above, and each molded product is matched to the surface plate shape of a predetermined polishing apparatus, cut into a circular shape or the like to make a polishing pad, or this molded product is processed into small pieces, A light-transmitting window is inserted into another low light-transmitting polishing pad, which is partially cut off, to obtain a light-detectable polishing pad. In the latter case, in order to enhance the effect of the present invention, it is desirable that the low light-transmitting polishing pad into which the window portion is inserted is also formed of a resin plate or the like containing organic fibers, There is no particular limitation on the fiber content. Further, the inserted window material needs to contact the object to be polished on the pad surface during polishing. This is because if the gap between the window material and the object to be polished is large, the polishing liquid flows in, scatters the transmitted light, and hinders light detection. There are no particular restrictions on the shape of the window, but the size of the window must be large enough to secure the optical path required for the system consisting of the light irradiation and detection sensor attached to the polishing device that performs light detection. In addition, the area is preferably about 0.1 to 10% of the entire polishing pad surface.
Hereinafter, a polishing method using the polishing pad of the present invention will be described. In the polishing method of the present invention, the surface to be polished of the object to be polished is pressed against the exposed surface of the organic fiber of any of the above-described polishing pads of the present invention, and the polishing liquid is supplied between the surface to be polished and the polishing pad. However, this is a polishing method for polishing the surface to be polished by relatively sliding the object to be polished and the pad.
A substrate having a silicon oxide film formed thereon by TEOS-plasma CVD or the like after etching a Si exposed portion after forming a device pattern formed with a silicon nitride film in a shallow trench isolation process as an object to be polished. In the damascene method, a barrier conductor film is formed on an interlayer insulating film in which via holes and wiring trenches are formed by dry etching so as to completely cover the opening and the inner wall, and a Cu film is further grown thereon to completely open the opening. A substrate in which is embedded.
The CMP polishing liquid used in the polishing method of the present invention is not particularly defined. For example, for an insulating film, a composition comprising cerium oxide particles (ceria) or silicon oxide (silica) and a dispersant is used as a dispersion medium such as water. And obtained by further adding an additive. Examples of the polishing liquid for a metal layer such as Cu include polishing liquid in which abrasive grains such as silica, alumina, ceria, titania, zirconia, and germania, additives and anticorrosive are dispersed in water, and a peroxide is further added. . As the abrasive, colloidal silica particles or alumina particles are particularly preferable. The abrasive particle content is preferably 0.1 to 20% by weight. The abrasive particles do not limit the production method, but the average particle size is preferably 0.01 to 1.0 μm. If the average particle size is less than 0.01 μm, the polishing rate becomes too low, and if it exceeds 1.0 μm, it tends to cause scratches.
There is no restriction | limiting in particular in the apparatus which grind | polishes, It can use with a disk type polisher and a linear type polisher. For example, a general polishing apparatus having a holder for holding an object to be polished and a polishing surface plate to which a polishing pad is attached and a motor or the like capable of changing the number of rotations can be used. As an example, polishing apparatus manufactured by Ebara Corporation: model number EPO111 can be used.
In particular, in the polishing method using the polishing pad of the third embodiment for optically detecting the polishing end point, the object to be polished and the polishing pad are relatively slid using the polishing pad as described above. While polishing the surface to be polished, the polishing surface of the object to be polished is irradiated with a light beam having a wavelength of 190 to 3500 nm through the polishing pad, and the change in the reflectance is detected to manage the polishing end point.
When the polishing pad of the third embodiment is used, the polishing apparatus is used for laser light irradiation and detection of reflected light on a surface plate to which the polishing pad is attached, such as the MIRRA polishing apparatus manufactured by Applied Materials, USA. It is necessary to have a device. There is no particular limitation on the polishing conditions, but it is desirable to optimize depending on the object to be polished. In order to polish accurately, the exposure of the silicon nitride film is detected in the shallow trench isolation process, and in the damascene method, the reflection of the light irradiated to the wafer surface is detected and the polishing end point is managed on the polishing apparatus side. . At this time, a program for controlling the progress of polishing is incorporated in the polishing apparatus in advance.
In order to fix the polishing pad of the present invention to the surface plate of the polishing apparatus, an adhesive such as a double-sided adhesive tape can be used on the side opposite to the polishing surface. Alternatively, it may be attached via a low elastic modulus subpad made of foamed polyurethane or the like.
In order to perform polishing by sliding the polishing pad and the object to be polished relative to each other while the surface to be polished of the object is pressed against the polishing pad, specifically, at least between the object to be polished and the polishing surface plate Move one side. In addition to rotating the polishing surface plate, polishing may be performed by rotating or swinging the holder. Further, a polishing method in which a polishing platen is rotated on a planetary surface, a polishing method in which a belt-like polishing pad is moved linearly in one direction in the longitudinal direction, and the like can be given. The holder may be in any state of being fixed, rotating and swinging. These polishing methods can be appropriately selected depending on the surface to be polished and the polishing apparatus as long as the polishing pad and the object to be polished are moved relatively.
There is no particular limitation on the polishing conditions, but it is desirable to optimize the polishing conditions according to the object to be polished. For example, the rotation speed of the polishing platen is preferably a low rotation of 200 rpm or less so that the object to be polished does not jump out, and the pressure applied to the object to be polished is a pressure at which scratches do not occur after polishing, for example, when the surface to be polished is copper. Is preferably about 50 kPa or less. Moreover, when using the to-be-polished object which has a low dielectric constant interlayer insulation film, 20 kPa or less is preferable.
During polishing, a polishing liquid is continuously supplied by a pump or the like between the polishing pad and the surface to be polished. Although there is no restriction | limiting in this supply amount, It is preferable that the surface of a polishing pad is always covered with polishing liquid. The abrasion of the pad and exposed organic fiber due to polishing is regenerated and maintained by dressing. The object to be polished after polishing is preferably washed in running water and then dried after removing water droplets adhering to the polishing surface using a spin dryer or the like.
Hereinafter, as one aspect of the polishing method of the present invention, in accordance with the wiring formation step of the semiconductor device, the surface to be polished has a barrier conductor layer, and further a metal layer such as copper on the insulating layer in which the wiring and the trench are formed. A polishing method comprising a coated laminate will be described.
The metal layer is mainly composed of metal such as copper, copper alloy, copper oxide, copper alloy oxide (hereinafter referred to as copper and its compounds), tungsten, tungsten alloy, silver, and gold. It is preferable that copper, such as copper and its compound, is a main component.
The barrier conductor layer (hereinafter referred to as a barrier layer) covered with the metal layer is preferably a barrier layer for the above-mentioned copper and its compound, particularly copper and a copper alloy, among the above metals. The barrier layer is formed to prevent diffusion of the metal layer into the insulating film and to improve the adhesion between the insulating film and the metal layer. Examples of the conductor composition include tantalum, titanium, tungsten, and compounds such as nitrides, oxides, and alloys thereof.
Examples of the insulating film include a silicon-based film and an organic polymer film interlayer insulating film. Silicon-based coatings include silicon dioxide, fluorosilicate glass, organosilicate glass obtained using trimethylsilane and dimethoxydimethylsilane as starting materials, silicon-based coatings such as silicon oxynitride and silsesquioxane hydride, silicon carbide and A silicon nitride is mentioned. Examples of the organic polymer film include wholly aromatic low dielectric constant interlayer insulating films. In particular, the interlayer insulating film preferably has a dielectric constant of 2.7 or less.
First, an interlayer insulating film such as silicon dioxide is laminated on a silicon substrate. Next, a known pattern concave portion (substrate exposed portion) is formed on the surface of the interlayer insulating film by a known means such as resist layer formation or etching to obtain an interlayer insulating film having convex portions and concave portions. On this interlayer insulating film, a barrier layer made of tantalum or the like covering the interlayer insulating film is formed along the surface irregularities by vapor deposition or CVD. Furthermore, a metal layer such as copper covering the barrier layer is formed by vapor deposition, plating, CVD, or the like so as to fill the concave portion.
Next, the metal layer on the surface of the substrate is polished by CMP using the polishing pad of the present invention while supplying a polishing liquid (first polishing step). Thereby, the barrier layer of the convex part on a board | substrate is exposed on the surface, and the desired wiring pattern with which the said metal film was left in the recessed part is obtained. When this polishing proceeds, a part of the convex barrier layer may be polished simultaneously with the metal layer. In the second polishing step, at least the exposed barrier layer and the recessed metal layer are polished by CMP using a polishing liquid capable of polishing the metal layer, the barrier layer, and the interlayer insulating film. The interlayer insulation film under the barrier layer of the convex part was all exposed, the metal layer to be the wiring layer was left in the concave part, and the desired pattern was obtained in which the cross section of the barrier layer was exposed at the boundary between the convex part and the concave part At this point, the polishing is finished. The polishing pad of the present invention is used at least in the second polishing step, and is preferably used in the first polishing step as in this embodiment.
In order to ensure better flatness at the end of polishing, further overpolishing (for example, if the time until a desired pattern is obtained in the second polishing step is 100 seconds, additional 50 seconds are added for polishing) This may be referred to as over-polishing 50%) and may be polished to a depth that includes a portion of the convex interlayer insulating film.
The polishing pad of the present invention and the polishing method using the same are applied not only to a film containing mainly a metal such as Cu, Ta, TaN, and Al, but also to a predetermined wiring board by embedding the composite opening of the insulating layer. It is composed of formed silicon oxide film, glass, inorganic insulating film such as silicon nitride, film mainly containing polysilicon, optical glass such as photomask / lens / prism, inorganic conductive film such as ITO, glass and crystalline material Optical integrated circuits, optical switching elements, optical waveguides, optical fiber end faces, scintillator and other optical single crystals, solid state laser single crystals, sapphire substrates for blue laser LEDs, semiconductor single crystals such as SiC, GaP, and GaAs, for magnetic disks It can also be applied to polishing glass or aluminum substrates, magnetic heads, and the like.

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

  Poly-p-phenylene terephthalamide fiber (trade name “Kevlar” manufactured by DuPont, fiber diameter 12.5 μm, fiber length 3 mm) as organic fiber, and ABS resin pellets as matrix composition are melt-mixed in an extruder, and tableted Turned into. Here, the poly-p-phenylene terephthalamide fiber was adjusted to 10% by weight. After the tablet was dried at 120 ° C. for 5 hours with a large dryer, a sheet-shaped molded product having a thickness of 1.2 mm and a width of 1 m was produced using an extrusion molding and a roll. Grooves having a rectangular cross-sectional shape with a depth of 0.6 mm and a width of 2.0 mm were formed in a grid shape with a pitch of 15 mm, and then cut into a circle. Furthermore, a double-sided tape was bonded to the opposite side of the grooved surface to obtain a polishing pad.

  A polishing pad was obtained in the same manner as in Example 1 except that polyethylene, polypropylene, and styrene elastomer were mixed at a weight ratio of 50: 50: 100 as the matrix composition.

つづいて、研磨液は上記の検討から研磨速度の高かった砥粒入り研磨剤を使用し、かつ加工荷重２×１０^４Ｐａとした以外は上記と同様に研磨し評価した結果を表２に示す。ここで、表２から、実施例では、上記研磨条件と殆ど研磨速度に差がなく、低荷重すなわち低摩擦力でも研磨が可能であることが確認できた。一方、比較例では、本条件のような低荷重では研磨速度が極端に低下してしまった。

以上の検討から、本発明による研磨パッドを使用すれば、ＣＭＰ時に絶縁層にかかる負荷を低減しつつ、平坦性を向上できることが分かった。
次に、実施例により、研磨パッドを介して半導体ウエハ表面へ光を照射し、その反射率の変化を検知し、研磨終点を管理する研磨工程に使用するのに適した本発明の研磨パッドを説明するが、本発明はこれらの実施例に限定されるものではない。
研磨パッドを作製するために以下の板材１〜３を準備した。
［板材１］
有機繊維としてポリ−ｐ−フェニレンテレフタルアミド繊維（デュポン製「ケブラー」、繊維径１２．５μｍ．繊維長３ｍｍ）、マトリックス樹脂としてＡＳ樹脂ペレット（日本エイアンドエル株式会社製、商品名：ライタックＡ−１００ＰＣ）を押し出し成形機にて溶融混合し、タブレット化した。ここで、ポリ−ｐ−フェニレンテレフタルアミド繊維は、５重量％になるように調整した。タブレットを大型乾燥機にて１２０℃、５ｈ乾燥した後、押し出し成形及びロールを用いて、厚さ１．２ｍｍ、幅１ｍのシート状成形品を作製した。
［板材２］
ＡＳ樹脂ペレット（同上）を押し出し成形機にて溶融し、タブレット化した。このタブレットを大型乾燥機にて１２０℃、５ｈ乾燥した後、押し出し成形及びロールを用いて、厚さ１．２ｍｍ、幅１ｍのシート状成形品を作製した。この板材は有機繊維を含まない。
［板材３］
パラ系アラミド繊維チョップ（繊維径：１２．５μｍ、繊維長：５ｍｍ、デュポン製「ケブラー」）とパラ系アラミド繊維パルプ（繊維径：１μｍ、繊維長：１ｍｍ、デュポン製「ケブラー」）とメタ系アラミド繊維チョップ（繊維径：２５μｍ、繊維長：６ｍｍ、軟化温度２８０℃、帝人（株）製「コーネックス」）を混抄し、水溶性エポキシ樹脂バインダ（ガラス転移温度１１０℃、大日本インキ化学工業（株）製、商品名「Ｖコート」）の２０重量％水溶液をスプレーして加熱乾燥（１５０℃、３ｍｉｎ）し、さらに、一対の熱ロール間（温度３００℃、線圧力１９６ｋＮ／ｍ）に通すことにより加熱圧縮し、メタ系アラミド繊維チョップをパラ系アラミド繊維チョップに熱融着した不織布を準備した。単位質量７０ｇ／ｍ^２、パラ系アラミド繊維チョップ／パラ系アラミド繊維パルプ／メタ系アラミド繊維チョップ／エポキシ樹脂バインダの配合質量比５８／１７／８／１７であった。
硬化剤としてジシアンジアミドを、硬化促進剤として２−エチル−４メチルイミダゾールを配合したビスフェノールＡ型エポキシ樹脂（油化シェル（株）製、商品名「ＥＰ−８２８ＳＫ」）ワニスを準備した。ワニスの調整には、ビスフェノールＡ型エポキシ樹脂１００重量部に対し、硬化剤を２０重量部、硬化促進剤を０．１重量部、溶剤としてメチルエチルケトンを４０重量部用いた。
このワニスを前述のアラミド繊維不織布に含浸し加熱乾燥（１７０℃、５ｍｉｎ）してプリプレグとした。このプリプレグは、加熱加圧成形後の厚さが０．０８ｍｍになるように樹脂付着量を調整したものである。アラミド繊維不織布の含有率は６０重量％である。
このプリプレグを１２枚重ねたプリプレグ層の両表面に離型フィルム（５０μｍ厚のポリプロピレンフィルム）を配置し、これをステンレス製鏡面板に挟み込み、その複数組をプレス熱盤間に投入し、熱盤との間にはクラフト紙層からなる厚さ１０ｍｍのクッション材を介在させて加熱加圧成形して（温度１７０℃、圧力３００ｋＰａ、時間１２０ｍｉｎ）、厚さ１．０ｍｍの積層板を得た。A polishing pad was obtained in the same manner as in Example 1 except that polypropylene was used as the matrix composition.
(Comparative Example 1)
A polishing pad was produced in the same manner as in Example 1 except that no organic fiber was used.
(Comparative Example 2)
A foamed polyurethane polishing pad was prepared.
Each of the above pads was attached to a surface plate of a polishing apparatus, and the surface was roughened for 30 minutes with a dresser equipped with a # 160 diamond wheel.
(Preparation of polishing liquid)
As a polishing liquid for copper, an abrasive-free abrasive (trade name HS-C430 slurry manufactured by Hitachi Chemical Co., Ltd.) and colloidal silica having an average secondary particle diameter of 35 nm were added to adjust to 0.37% by weight. An abrasive containing abrasive was used. Both were mixed at a volume ratio of polishing liquid: hydrogen peroxide solution = 7: 3 at the time of use.
(Polishing the substrate)
Using the polishing pads prepared in Examples and Comparative Examples and the above polishing liquid, a silicon wafer substrate without wiring or with wiring formed thereon is polished as follows, and dishing is performed as an index of polishing speed, polishing scratches, and flatness. Was measured.
That is, the wafer was set in a holder to which a suction pad for wafer attachment of a polishing apparatus was attached. In addition, the polishing pads produced in Examples and Comparative Examples were attached to the polishing surface plate of the polishing apparatus, and the holder was attached to the polishing apparatus with the surface to be polished facing down. While supplying the above polishing liquid at 150 cc / min, the surface plate and the wafer were rotated at 38 rpm, polished with a processing load of 4 × 10 ⁴ Pa, and evaluated. The results are shown in Table 1.
(Evaluation of polishing rate)
Polishing was performed for 2 minutes using a silicon wafer substrate (diameter 13 cm) with a silicon dioxide film layer on which a 1 μm-thick copper film was formed and no wiring was formed. The copper film thickness before and after polishing was measured by using a Napson Co., Ltd. model number RT-7, the sheet resistance value was measured, the film thickness was calculated from the resistivity, and the film thickness difference before and after CMP was calculated. The results are listed in Table 1.
(Evaluation of polishing scratches)
Using the wafer on which the polishing rate was evaluated, the scratches were evaluated visually. The results are also shown in Table 1.
○: Less than 5 scratches on the polished surface after polishing ×: 5 or more scratches on the polished surface after polishing (dishing amount)
A silicon dioxide film having a thickness of 300 nm is formed on a silicon wafer, a groove having a wiring density of 50% and a depth of 0.5 μm is formed in the silicon dioxide, and a tantalum nitride film having a thickness of 50 nm is formed as a barrier layer by a known sputtering method. Similarly, a copper film of 1.0 μm is formed by sputtering and embedded by a known heat treatment, and a stripe shape in which a wiring metal part (copper) width of 100 μm and an insulating film (silicon dioxide) part width of 100 μm are alternately arranged A silicon substrate (diameter 13 cm) having the surface shape of the pattern portion was prepared as an object to be polished.
Using this object to be polished, two-stage polishing consisting of polishing of a copper film and polishing of a barrier layer is performed, and insulation is performed from the surface shape of the stripe-shaped pattern portion with a stylus type step meter (Dektat 3030 manufactured by Veeco / Sloan). The amount of reduction of the wiring metal part relative to the film part was measured. The results are also shown in Table 1. In the table, “impossible to measure” indicates a state in which the substrate cannot be polished at a low polishing rate or cannot be measured due to excessive polishing scratches.
The polishing pads produced in Example 1 and Comparative Example 1 have the same matrix resin, and are different in whether or not they contain fibers. Example 1 which is the polishing pad of the present invention is good in that the occurrence of scratches is suppressed as compared with Comparative Example 1 which does not contain organic fibers. In Comparative Example 1, polishing scratches were severe and dishing measurement was impossible. In the examples, it is apparent that when the abrasive-free abrasive is used, the polishing can hardly be performed, and the polishing is performed by a polishing apparatus structure different from Comparative Example 1 or Comparative Example 2 having a high polishing rate.

Table 2 shows the results of polishing and evaluation in the same manner as described above except that the polishing liquid used was a polishing agent containing abrasive grains having a high polishing rate from the above examination and the processing load was set to 2 × 10 ⁴ Pa. . Here, from Table 2, it was confirmed that in the Examples, there was almost no difference in the polishing conditions and the polishing rate, and polishing was possible even with a low load, that is, a low frictional force. On the other hand, in the comparative example, the polishing rate was extremely reduced at a low load as in this condition.

From the above study, it was found that the use of the polishing pad according to the present invention can improve the flatness while reducing the load applied to the insulating layer during CMP.
Next, according to the embodiment, the polishing pad of the present invention suitable for use in a polishing process in which light is irradiated to the surface of the semiconductor wafer through the polishing pad, the change in reflectance is detected, and the polishing end point is managed. As will be described, the present invention is not limited to these examples.
In order to prepare a polishing pad, the following plate materials 1 to 3 were prepared.
[Plate 1]
Poly-p-phenylene terephthalamide fiber (Du Pont “Kevlar”, fiber diameter 12.5 μm, fiber length 3 mm) as organic fiber, AS resin pellet as matrix resin (trade name: LIGHTAC A-100PC, manufactured by Nippon A & L Co., Ltd.) Was melt-mixed in an extruder and tableted. Here, the poly-p-phenylene terephthalamide fiber was adjusted to 5% by weight. After the tablet was dried at 120 ° C. for 5 hours with a large dryer, a sheet-like molded product having a thickness of 1.2 mm and a width of 1 m was prepared using an extrusion molding and a roll.
[Plate material 2]
AS resin pellets (same as above) were melted in an extruder and tableted. The tablet was dried at 120 ° C. for 5 hours with a large dryer, and then a sheet-like molded product having a thickness of 1.2 mm and a width of 1 m was produced using extrusion molding and a roll. This plate material does not contain organic fibers.
[Plate 3]
Para-aramid fiber chop (fiber diameter: 12.5 μm, fiber length: 5 mm, DuPont “Kevlar”) and para-aramid fiber pulp (fiber diameter: 1 μm, fiber length: 1 mm, DuPont “Kevlar”) and meta Aramid fiber chop (fiber diameter: 25 μm, fiber length: 6 mm, softening temperature 280 ° C., Teijin's “Conex”) was mixed and water-soluble epoxy resin binder (glass transition temperature 110 ° C., Dainippon Ink & Chemicals, Inc.) Sprayed with a 20% by weight aqueous solution (trade name “V coat”, manufactured by Co., Ltd.) and dried by heating (150 ° C., 3 min), and further between a pair of hot rolls (temperature 300 ° C., linear pressure 196 kN / m) A non-woven fabric was prepared by heat-compressing by passing, and heat-sealing the meta-aramid fiber chop to the para-aramid fiber chop. The unit mass was 70 g / m ² , and the blending mass ratio of para-aramid fiber chop / para-aramid fiber pulp / meta-aramid fiber chop / epoxy resin binder was 58/17/8/17.
A bisphenol A type epoxy resin (trade name “EP-828SK”, manufactured by Yuka Shell Co., Ltd.) varnish in which dicyandiamide was blended as a curing agent and 2-ethyl-4methylimidazole was blended as a curing accelerator was prepared. For adjusting the varnish, 20 parts by weight of the curing agent, 0.1 part by weight of the curing accelerator and 40 parts by weight of methyl ethyl ketone as the solvent were used with respect to 100 parts by weight of the bisphenol A type epoxy resin.
This varnish was impregnated into the aramid fiber nonwoven fabric described above and dried by heating (170 ° C., 5 min) to obtain a prepreg. This prepreg is obtained by adjusting the resin adhesion amount so that the thickness after heat and pressure molding becomes 0.08 mm. The content of the aramid fiber nonwoven fabric is 60% by weight.
A release film (50 μm-thick polypropylene film) is placed on both surfaces of the prepreg layer in which 12 prepregs are stacked, and this is sandwiched between stainless mirror plates, and a plurality of sets are put between press hot plates. A 10 mm thick cushioning material made of a kraft paper layer was interposed between the two and heated and pressure-molded (temperature 170 ° C., pressure 300 kPa, time 120 min) to obtain a laminated plate having a thickness of 1.0 mm.

  The plate 1 is processed into a disk shape of φ500 mm, and a groove is processed on the surface so that the polishing liquid supplied at the time of polishing passes under the jig holding the wafer and flows under the wafer (lattice Shape, groove width 2 mm, groove pitch 15 mm, groove depth 0.6 mm), and a double-sided tape was attached to the opposite surface to obtain a polishing pad.

以上のように研磨装置にセットした各実施例、従来例、参考例および比較例の研磨パッドとＣＭＰ研磨液により、シリコンウエハ（絶縁膜ブランケットウエハおよびＴＥＧウエハ）の研磨を次のように実施し、その特性を次の観点から評価した。これら評価結果を表４に示す。
（研磨傷数の評価）
φ２００ｍｍシリコンウエハ上にＴＥＯＳ−プラズマＣＶＤ法で酸化珪素膜を１μｍ形成したブランケットウエハを研磨装置にセットした。このとき、ウエハはヘッド部に保持され、酸化珪素膜面を定盤上の研磨パッドに当接されていた。研磨中にウエハの表面にかかる研磨圧力を２１ｋＰａ（３ＰＳＩ）に設定し、酸化セリウム系研磨液（日立化成工業（株）製 ＨＳ−８００５）を供給量４０ｍＬ／ｍｉｎと添加剤（日立化成工業（株）製 ＨＳ−８１０２ＧＰ）を供給量１６０ｍＬ／ｍｉｎで混合して定盤上に滴下しながら、定盤を１００ｒｐｍ、ヘッドを９０ｒｐｍで回転させて、ウエハ上の酸化珪素膜を１分間研磨した。研磨後のシリコンウエハを純水で十分に洗浄後、乾燥した後、ウエハの表面全体を顕微鏡で暗視野にて観察を行い、研磨傷をカウントした。
（研磨速度の評価）
研磨傷数の評価の終わった各ブランケットウエハの酸化珪素膜厚を光干渉式膜厚測定装置により測定し、研磨前に測定した酸化珪素膜厚との差から平均研磨速度を求めた。
（均一性の評価）
研磨速度の測定と同様に各ブランケットウエハ面内の直行する直径上にて端部５ｍｍから８ｍｍおきの４５点について、各箇所の酸化珪素膜の研磨速度を測定し、標準偏差（１δ）から研磨速度のばらつき（１δ／平均研磨速度×１００）を求めた。
（終点管理の可否の評価）
φ２００ｍｍシリコンウエハ上に幅および間隔を２５〜２０００μｍとしたラインなどのパターンを厚み１００ｎｍの窒化珪素膜で作製した後、Ｓｉ露出部を深さ３５０ｎｍエッチングし、このウエハ上にＴＥＯＳ−プラズマＣＶＤ法で酸化珪素膜を６００ｎｍ形成した表面に４５０ｎｍの凹凸を持ったＴＥＧウエハを準備した。このウエハを前述したブランケットウエハと同条件で研磨する際に、評価に用いた研磨装置（アプライドマテリアルテクノロジー社製ＭＩＲＲＡ）に付属するレーザ光によるＩＳＲＭ終点管理システムを使用して、窒化珪素膜の露出検知の可否を判別した。
（平坦性の評価）
前述の終点管理にて窒化珪素膜の露出を検知し、研磨を終了したＴＥＧウエハの窒化珪素膜のライン（幅１００μｍ）とその隣り合った酸化珪素膜のライン（幅３００μｍ）との表面の段差を触針式段差計Ｄｅｋｔａｋ３０３０（ＳＬＯＡＮ社製）を用いて測定した。

表４の実施例３および４の結果から本発明に係る研磨パッドを用いることにより、光検知による終点の管理ができ、なおかつ従来例１、および比較例３との比較から有機繊維の効果で研磨傷の発生を抑制できることが判る。また、このとき、研磨速度が高く、均一性も充分であることが判った。なお、参考例１の研磨パッドは評価に用いたＴＥＧウエハを研磨するにあたり、光照射により終点を検知するのに、充分顕著な反射率の変化がみられなかった。これは、参考例１の研磨パッドが先の検討で光透過率が低い結果となったことと相応する。
次に最大露出繊維長さに関する実施例について説明する。The plate 1 was processed into a rectangular piece having a length of 56 mm, a width of 19 mm, and a rounded corner (curvature radius of 1.0 mm). Next, the plate material 3 was processed into a disk shape of φ500 mm in the same manner as in Example 3, and groove processing was performed on the surface thereof. A rectangular hole having a radius of 56 mm in length and 19 mm in width and having the same radius as the above at the corner was cut out so that the longitudinal direction would be on the radius side. A rectangular small piece made of the above-described plate material 1 was inserted into the hole of the disk to form a transmission window for light detection. Finally, a double-sided tape was attached to the opposite side of the grooved surface to obtain a polishing pad.
(Conventional example 1)
A polishing pad made of a foamed polyurethane-based resin and having a light-transmitting transmission window made of a rectangular transparent resin plate having a length of 56 mm and a width of 19 mm and a corner at the corner was prepared. (Thickness 1.2 mm, “IC-1000 / Suba-400” manufactured by Rodel)
(Comparative Example 3)
The plate 2 was processed in the same manner as in Example 3 to produce a polishing pad.
(Reference Example 1)
The plate 3 was processed in the same manner as in Example 3 to produce a polishing pad. This polishing pad does not have a window as in the fourth embodiment.
The light transmittances of the polishing pads of these Examples, Conventional Examples, Reference Examples and Comparative Examples were measured. For the polishing pad having the light transmission window, measurement was performed at the window portion, and for the polishing pad not having the light transmission window, measurement was performed on the plate material of the polishing pad main body. The transmittance was measured using a spectrophotometer UV-2200 manufactured by Shimadzu Corporation, and the measurement wavelength was 670 nm. The measured value was converted to a transmittance of a plate thickness of 1 mm using Lambert Beer's law.
As the polishing apparatus, an MIRRA machine manufactured by Applied Materials, Inc., USA was used, and each of these polishing pads was stuck on a surface plate of φ500 mm and fixed. A polishing pad having a light transmission window for light detection was aligned so that the window of the surface plate of the polishing apparatus and the window of the polishing pad did not shift. After each polishing pad is affixed to the surface plate, a diamond dresser (Abrasive: # 170 with acrylic coat) manufactured by Asahi Diamond Co., Ltd. is attached to the pad conditioner mechanism attached to this polishing apparatus, and 15 minutes at 9 LB. Dressed up. At this time, when the surface state of each polishing pad was observed, fiber exposure (exposure length: around 500 μm) was observed on the surfaces of the polishing pads of Example 3 and Reference Example 1. Also in the polishing pad of Example 4, similar fiber exposure (exposure length: around 500 μm) was observed on the entire pad surface including the window portion. The polishing pads of Conventional Example 1 and Comparative Example 3 did not expose these fibers.
Table 3 summarizes the structures, surface states, and light transmittances of the polishing pads of these examples, conventional examples, reference examples, and comparative examples.

As described above, polishing of silicon wafers (insulating film blanket wafer and TEG wafer) was carried out as follows using the polishing pad and CMP polishing liquid of each of the examples, conventional examples, reference examples and comparative examples set in the polishing apparatus. The characteristics were evaluated from the following viewpoints. These evaluation results are shown in Table 4.
(Evaluation of the number of polishing scratches)
A blanket wafer in which a silicon oxide film of 1 μm was formed on a φ200 mm silicon wafer by TEOS-plasma CVD was set in a polishing apparatus. At this time, the wafer was held by the head portion, and the silicon oxide film surface was in contact with the polishing pad on the surface plate. The polishing pressure applied to the wafer surface during polishing was set to 21 kPa (3 PSI), and a cerium oxide-based polishing liquid (HS-8005 manufactured by Hitachi Chemical Co., Ltd.) was supplied at 40 mL / min and additives (Hitachi Chemical Industry ( HS-8102GP) was mixed at a supply rate of 160 mL / min and dropped onto the platen, while rotating the platen at 100 rpm and the head at 90 rpm, the silicon oxide film on the wafer was polished for 1 minute. The polished silicon wafer was thoroughly washed with pure water and dried, and then the entire surface of the wafer was observed with a microscope in a dark field, and polishing scratches were counted.
(Evaluation of polishing rate)
The silicon oxide film thickness of each blanket wafer after the evaluation of the number of polishing flaws was measured with an optical interference film thickness measuring device, and the average polishing rate was determined from the difference from the silicon oxide film thickness measured before polishing.
(Evaluation of uniformity)
Similar to the measurement of the polishing rate, the polishing rate of the silicon oxide film at each point is measured at 45 points every 5 mm to 8 mm on the direct diameter in each blanket wafer surface, and polishing is performed from the standard deviation (1δ). Variation in speed (1δ / average polishing speed × 100) was determined.
(Evaluation of availability of end point management)
A pattern such as a line having a width and interval of 25 to 2000 μm is formed on a φ200 mm silicon wafer with a silicon nitride film having a thickness of 100 nm, and then an Si exposed portion is etched to a depth of 350 nm. The TEOS-plasma CVD method is formed on this wafer. A TEG wafer having 450 nm irregularities on the surface on which a 600 nm silicon oxide film was formed was prepared. When this wafer is polished under the same conditions as the blanket wafer described above, the silicon nitride film is exposed using the ISRM end point management system using laser light attached to the polishing apparatus (MIRRA manufactured by Applied Material Technology) used for evaluation. It was determined whether or not detection was possible.
(Evaluation of flatness)
The surface level difference between the silicon nitride film line (width: 100 μm) and the adjacent silicon oxide film line (width: 300 μm) of the TEG wafer whose polishing has been finished by detecting the exposure of the silicon nitride film by the end point management described above. Was measured using a stylus type step gauge Dektak 3030 (manufactured by SLOAN).

By using the polishing pad according to the present invention from the results of Examples 3 and 4 in Table 4, it is possible to manage the end point by light detection, and polishing by the effect of organic fiber from comparison with Conventional Example 1 and Comparative Example 3 It can be seen that the occurrence of scratches can be suppressed. At this time, it was found that the polishing rate was high and the uniformity was sufficient. Note that the polishing pad of Reference Example 1 did not show a sufficiently significant change in reflectance to detect the end point by light irradiation when polishing the TEG wafer used for evaluation. This corresponds to the result that the polishing pad of Reference Example 1 has a low light transmittance in the previous examination.
Next, examples relating to the maximum exposed fiber length will be described.

A nonwoven fabric (“EPM-4070TE” manufactured by Nippon Vilene Co., Ltd.) having a unit mass of 70 g / m ² made of polyester fiber having a fiber diameter of 12.5 μm and a fiber length of 5 mm is impregnated with the following varnish and dried at 170 ° C. for 5 minutes. A prepreg was prepared.
The varnish is dissolved in 40 parts by weight of methyl ethyl ketone by adding 20 parts by weight of dicyandiamide as a curing agent and 0.1 part by weight of 2-ethyl-4-methylimidazole as a curing accelerator to 100 parts by weight of a bisphenol A type epoxy resin. Made.
20 sheets of the above prepregs were laminated, and release films (polypropylene, 50 μm thickness) were placed on the top and bottom, sandwiched between mirror plates. Heat pressing was performed between press hot plates through cushion paper having a thickness of 10 mm. Here, the molding conditions were 175 ° C., 400 kPa, and 120 minutes. As a result, a laminated plate having a thickness of 1.5 mm was obtained. The fiber content of the entire laminate was 50% by weight. This was cut into a circular shape, and the surface was cut using a # 70 diamond grindstone, and then the groove was processed to obtain a polishing pad. Here, a groove having a groove width of 2 mm, a depth of 0.6 mm, and a pitch of 15 mm was formed.

  A 1.5 mm thick laminate was obtained in the same manner as in Example 5 except that 10 prepregs and 10 non-resin impregnated polyester nonwoven fabrics were laminated alternately. The fiber content of the entire laminate was 70% by weight. Thereafter, the surface was cut in the same manner as in Example 5, and the grooves were processed to obtain a polishing pad.

A polishing pad was prepared in the same manner as in Example 5 except that a polyester woven fabric having a unit mass of 130 g / m ³ (“BKE poplin” manufactured by Asahi Kasei Corporation, fiber diameter: 9 μm) was used as the fiber. In this example, the fiber content of the entire laminate was 50% by weight.

表５から、最大露出繊維長さが０．１ｍｍ以下である研磨パッドを用いれば、研磨傷なしに平坦性、トレンチ部の耐ディッシング性を向上でき、層間絶縁膜、ＢＰＳＧ膜の平坦化、シャロー・トレンチ分離の形成をはじめとする半導体形成プロセスを効率的に行えることがわかる。A polyester fiber (manufactured by Nippon Vileen Co., Ltd.) having a fiber diameter of 12.5 μm and a fiber length of 3 mm as organic fibers and ABS resin pellets as a matrix resin were melt-mixed in an extrusion molding machine and tableted. Here, the fiber content was adjusted to 10% by weight. After the tablet was dried at 120 ° C. for 5 hours with a large dryer, a sheet-like molded product having a thickness of 1.2 mm and a width of 1 m was prepared using an extrusion molding and a roll. Grooves having a rectangular cross-sectional shape with a depth of 0.6 mm and a width of 2.0 mm were formed in a grid shape with a pitch of 15 mm, and then cut into a circle. Furthermore, after a double-sided tape was bonded to the opposite side of the grooved surface, the surface was roughened using a # 70 diamond grindstone to obtain a polishing pad.
(Reference Example 2)
Para-aramid fiber chops (fiber diameter: 12.5 μm, fiber length: 5 mm, “Technola” manufactured by Teijin Ltd.) and meta-para-aramid fiber chops (fiber diameter: 25 μm, fiber length: 6 mm) After spraying a 20% by weight aqueous solution of a water-soluble epoxy resin binder (Dainippon Ink Chemical Co., Ltd., trade name “V Coat”) to a mixture of Teijin's “Conex”), 150 ° C. The same as in Example 5 except that the nonwoven fabric was heated and dried for 3 minutes to give a nonwoven fabric of 70 g / m ² , and this nonwoven fabric was passed through a hot roll at 300 ° C. and a linear pressure of 196 kN / m and heated and compressed. Thus, a polishing pad was obtained. The surface was cut using a # 150 diamond grindstone. In this reference example, the fiber content of the entire laminate was 50% by weight.
(Comparative Example 4)
A 1.5 mm thick ABS (acrylonitrile-butadiene rubber-styrene copolymer) plate was used to cut into a circle, and the surface was processed with a grid-like groove having a groove width of 2 mm, a depth of 0.6 mm, and a pitch of 15 mm. . Thereafter, the surface was roughened using a # 70 diamond grindstone to obtain a polishing pad.
(Reference Example 3)
A polishing pad was prepared in the same manner as in Example 8 except that a # 70 diamond grindstone was used for surface scraping.
(Surface observation)
The SEM (scanning electron microscope) was used to observe five arbitrary points on the pad surface at 100 times and 200 times, and the maximum length of the exposed fiber was measured.
(Polishing liquid)
A CMP slurry was prepared as a polishing liquid by the following method.
2 kg of cerium carbonate hydrate was put in a platinum container, and 1 kg of cerium oxide powder obtained by firing in air at 800 ° C. for 2 hours was dry pulverized using a jet mill. To this, 23 g of an aqueous polyacrylic acid ammonium salt solution (40% by weight) and 8977 g of deionized water were mixed and subjected to ultrasonic dispersion for 10 minutes while stirring. The resulting slurry was filtered with a 1 micron filter, and deionized water was added to obtain a 5 wt% slurry. The slurry pH was 8.3. In order to measure the slurry particles with a laser diffraction particle size distribution meter, the slurry was diluted to an appropriate concentration, and as a result, D99% of the particle diameter was 0.99 μm.
(Evaluation of polishing method and polishing characteristics)
A blanket wafer having a silicon oxide film of 2 μm formed by TEOS-plasma CVD method on a φ127 mm Si substrate and a trench having square convex portions arranged on a φ200 mm Si substrate are provided, and a Si ₃ N ₄ film and TEOS-plasma CVD method are provided thereon. A test wafer on which a silicon oxide film was formed to 600 μm was prepared. As the trench, a portion having a depth of 0.35 μm, a density of 60% of the convex portion, and a trench width of 500 μm was used.
Set the wafer on the holder of the polishing machine with the suction pad for attaching the wafer substrate, and place the holder on the surface plate of φ380mm with the prepared polishing pad attached, and place the holder on the bottom to further process The load was set to 29 kPa (300 gf / cm ² ). While the cerium oxide polishing liquid was dropped onto the surface plate at a rate of 150 cc / min, the surface plate and the wafer were rotated at 38 rpm for 2 minutes to polish the insulating film. The polished wafer was thoroughly washed with pure water and then dried. The difference in film thickness before and after polishing was measured using an optical interference type film thickness measuring device, and the polishing rate was calculated. Regarding the polishing scratches, the polished wafer surface was observed with a microscope in a dark field, and the scratches caused by polishing existing on the wafer surface were counted.
For evaluation of flatness, a step of 1 μm between the convex part and the concave part of the TEG wafer was cut, and the final step before the convex Si ₃ N ₄ film was exposed was measured. Further, dishing of the above-mentioned trench portion of the TEG wafer was measured with a stylus type step gauge.
Table 5 shows the polishing characteristics of Examples, Reference Examples and Comparative Examples. Examples 5, 6, 7 and 8 containing the polyester fiber according to the present invention are easy to reduce the exposed fiber length, excellent in flatness and polished compared to Reference Example 2 containing the aramid fiber which is a high-hardness fiber. There is no wound. Further, as is clear when Examples 5, 6, 7 and 8 are compared with Comparative Example 4 which does not contain fibers, the polishing rate is improved and polishing scratches are eliminated.

From Table 5, if a polishing pad having a maximum exposed fiber length of 0.1 mm or less is used, the flatness and dishing resistance of the trench portion can be improved without polishing scratches, and the interlayer insulating film and BPSG film can be flattened. It can be seen that the semiconductor formation process including trench isolation can be performed efficiently.

Industrial applicability

When CMP is performed using the polishing pad of the present invention or the polishing pad produced by the manufacturing method of the present invention, fine polishing scratches on the object to be polished are generated by the organic fibers exposed on the surface of the object to be polished of the polishing pad. Can be suppressed. Thereby, flat polishing can be performed with a low load. Further, the polishing end point of the object to be polished by the system for detecting the polishing state of the object to be polished by an optical method can be managed without any polishing scratches. Thus, the productivity and yield of the workpiece can be improved.
For this reason, for example, in the manufacturing process of a semiconductor device, polishing with a low load on the interlayer insulating film and excellent flatness can be performed, and the next generation dual damascene method can be easily performed.

Claims (24)

A polishing pad comprising an organic fiber-containing fiber and a matrix resin holding the fiber, wherein at least the organic fiber is exposed on the surface of the object to be polished. A polishing pad comprising a fiber containing organic fibers and a matrix resin holding the fibers, wherein at least the organic fibers are exposed on the surface of the object to be polished after the dressing process. The polishing pad according to claim 1 or 2, wherein the matrix resin contains at least one thermoplastic resin. The polishing pad according to any one of claims 1 to 3, wherein the matrix resin is made of a semicrystalline thermoplastic resin. The polishing pad according to any one of claims 1 to 4, wherein an elastomer is dispersed in the matrix resin. The polishing pad according to claim 5, wherein the glass transition point of the elastomer is 0 ° C or lower. The polishing pad according to any one of claims 1 to 6, wherein the fibers are made of an aromatic polyamide. The polishing pad according to any one of claims 1 to 7, comprising 1 to 50% by weight of organic fibers. The polishing pad according to any one of claims 1 to 8, wherein the organic fiber has a diameter of 1 mm or less. The polishing pad according to any one of claims 1 to 9, wherein the organic fiber has a length of 1 cm or less. The polishing pad according to any one of claims 1 to 10, wherein the abrasive particles are held by organic fibers exposed on the surface of the object to be polished. The polishing pad according to any one of claims 1 to 11, wherein the exposed length of the exposed organic fiber is 0.1 mm or less. The polishing pad according to claim 12, wherein the exposed organic fibers are made of polyester. The polishing pad according to claim 12 or 13, wherein chopped polyester fibers are dispersed in a matrix resin. The polishing pad according to claim 12 or 13, wherein a polyester nonwoven fabric is laminated in a matrix resin. A polishing pad useful for optically detecting the polishing end point during polishing of the surface of an object to be polished, comprising a substantially non-foamed matrix resin containing 1 to 20% by weight of organic fibers, and polishing slurry particles In addition, the light beam having a wavelength in the range of 190 to 3500 nm is transmitted, and the light beam of the first, second to fourth, seventh, and ninth to eleventh aspects is transmitted. Any polishing pad. A polishing pad useful for optically detecting a polishing end point during polishing of a surface of an object to be polished, including a portion that transmits a light beam having a wavelength in a range of 190 to 3500 nm. A portion consisting of a substantially non-foamed matrix resin containing up to 20% by weight and having a function of transporting and holding abrasive slurry particles. The polishing pad according to any one of Items 9 to 11. The polishing pad according to claim 16 or 17, wherein the organic fiber is an aramid fiber. A method of manufacturing a polishing pad that is used by being attached to a surface plate to flatten a surface to be polished, the process of mixing a fiber containing organic fibers and a matrix composition containing a thermoplastic resin to obtain a mixture, the mixture A method for producing a polishing pad comprising the steps of: converting the pellet or tablet into a plate or sheet by extrusion molding or injection molding. A method of manufacturing a polishing pad that is used by attaching to a surface plate to flatten the surface to be polished, and impregnating a matrix resin composition into a fiber substrate containing organic fibers to produce a resin-impregnated sheet-like fiber substrate A method for producing a polishing pad, comprising: a step of laminating a sheet-like fiber base material including the resin-impregnated sheet-like fiber base material, and subjecting the sheet-like fiber base material to heating and pressing. 21. The method for producing a polishing pad according to claim 19, further comprising a step of exposing the fiber to the surface. The surface to be polished of the object to be polished is pressed against the organic fiber exposed surface of the polishing pad according to any one of claims 1 to 18 while supplying the polishing liquid between the surface to be polished and the polishing pad. A polishing method for polishing a surface to be polished by relatively sliding an object to be polished and a pad. 23. A polishing method according to claim 22, wherein said surface to be polished comprises a laminate in which a conductor layer and a copper layer are further coated on an insulating layer having a dielectric constant of 2.7 or less in which wirings and trenches are formed. A polishing method for optically detecting a polishing end point using the polishing pad according to any one of claims 16 to 18.