JP2006147993A - Polishing solution for cmp and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing solution for achieving improved flatness of a polished surface, making the polishing speed for an interlayer insulating film as high as that for a barrier layer or a wiring portion metal, making the polishing speed for the interlayer insulating film large, suppressing the flocculation of particles, preventing the reduction in the polishing speed for a wiring portion, further enabling the adjustment of the polishing speed for the wiring portion, and reducing the metal residues and polishing flaws after the polishing, and to provide a polishing method in the manufacture of a highly reliable low cost semiconductor device etc. having excellent microminiaturization, film-thinning, size precision, and electric characteristics. <P>SOLUTION: This polishing solution for CMP is characterized by containing abrasive grains whose surfaces are denatured by two or more different organic functional groups. This polishing method is characterized by comprising: a first polishing step for polishing an electrically conductive material layer of a substrate, which substrate having the interlayer insulating film whose surface comprising recesses and projections, a barrier conductor layer for coating the surface of the interlayer insulating film, and the electrically conductive material layer for filling the recesses to coat the barrier conductor layer, to expose the barrier conductor layer on the projections; and a second polishing step for subjecting at least the barrier conductor layer and the electrically conductive material layer in the recesses to chemical and mechanical polishing while supplying the polishing solution for CMP to expose the interlayer insulating film in the recesses. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing liquid for CMP and a polishing method used for polishing in a wiring formation process of a semiconductor device.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (hereinafter referred to as LSIs). A chemical mechanical polishing (hereinafter referred to as CMP) method is one of them, and a technique frequently used in the planarization of an interlayer insulating film, the formation of a metal plug, and the formation of a buried wiring in an LSI manufacturing process, particularly a multilayer wiring forming process. It is. This technique is disclosed in Patent Document 1, for example.

  Recently, in order to improve the performance of LSIs, attempts have been made to use copper and copper alloys as conductive materials serving as wiring materials. However, it is difficult to finely process copper or a copper alloy by a dry etching method frequently used in the formation of a conventional aluminum alloy wiring. Therefore, a so-called damascene method is mainly employed, in which a thin film of copper or a copper alloy is deposited and embedded on an insulating film in which a groove is formed in advance, and the thin film other than the groove is removed by CMP to form a buried wiring. ing. This technique is disclosed in Patent Document 2, for example.

A general method of metal CMP for polishing a metal for a wiring part such as copper or a copper alloy is to apply a polishing cloth (pad) on a circular polishing platen (platen), and to polish the surface of the polishing cloth with a metal polishing liquid. While dipping, the surface of the substrate on which the metal film is formed is pressed against the surface of the polishing cloth, and a predetermined pressure (hereinafter referred to as polishing pressure) is applied to the metal film from the back surface of the polishing cloth, and the polishing platen is turned. The metal film on the convex portion is removed by relative mechanical friction between the polishing liquid and the convex portion of the metal film.
The metal polishing liquid used for CMP is generally composed of an oxidizer and abrasive grains, and a metal oxide solubilizer and a protective film forming agent are further added as necessary. First, it is considered that the basic mechanism is to oxidize the surface of a metal film with an oxidizing agent and scrape the oxidized layer with abrasive grains. Since the oxide layer on the metal surface of the concave portion does not touch the polishing pad so much and the effect of scraping off by the abrasive grains does not reach, the metal layer of the convex portion is removed and the substrate surface is flattened with the progress of CMP. This detail is disclosed in Non-Patent Document 1.

  As a method for increasing the polishing rate by CMP, it is effective to add a metal oxide dissolving agent. It is interpreted that if the metal oxide particles scraped off by the abrasive grains are dissolved in the polishing liquid (hereinafter referred to as etching), the effect of scraping off by the abrasive grains is increased. Although the polishing rate by CMP is improved by adding a metal oxide solubilizer, on the other hand, when the oxide layer on the metal film surface in the recess is also etched to expose the metal film surface, the metal film surface is further oxidized by the oxidant, and this is repeated. As a result, the etching of the metal film in the recesses proceeds. For this reason, a phenomenon occurs in which the central portion of the surface of the metal wiring embedded after polishing is depressed like a dish (hereinafter referred to as dishing), and the planarization effect is impaired.

In order to prevent this, a protective film forming agent is further added. The protective film forming agent forms a protective film on the oxide layer on the surface of the metal film and prevents dissolution of the oxide layer in the polishing liquid. This protective film can be easily scraped off by abrasive grains, and it is desirable not to reduce the polishing rate by CMP.
In order to suppress corrosion during dishing or polishing of copper or copper alloy, and to form a highly reliable LSI wiring, it contains BTA as a protective film forming agent and a metal oxide solubilizer composed of aminoacetic acid or amide sulfuric acid such as glycine A method using a polishing slurry for CMP is proposed. This technique is described in Patent Document 3, for example.

  In metal embedding formation such as damascene wiring formation such as copper or copper alloy and plug wiring formation such as tungsten, interlayer insulation is used when the polishing rate of the silicon dioxide film which is an interlayer insulating film formed other than the embedded portion is high. Thinning occurs where the thickness of the wiring is reduced with each film. As a result, since the wiring resistance increases, the silicon dioxide film must have a sufficiently low polishing rate with respect to the metal film to be polished. Therefore, in order to suppress the polishing rate of silicon dioxide by anions generated by acid dissociation, a method of making the polishing solution pH higher than pKa-0.5 has been proposed. This technique is described in Patent Document 4, for example.

  On the other hand, as a barrier conductor layer (hereinafter referred to as a barrier layer) for preventing copper diffusion into the interlayer insulating film and improving adhesion, for example, tantalum or tantalum is provided below the metal for wiring part such as copper or copper alloy. A layer of an alloy, a tantalum compound such as tantalum nitride, or the like is formed. Therefore, it is necessary to remove the exposed barrier layer by CMP except for the wiring portion in which copper or a copper alloy is embedded. However, the conductors of these barrier layers are harder than copper or copper alloy, so even if a polishing material for copper or copper alloy is combined, a sufficient polishing rate cannot be obtained, and the flatness deteriorates. There are many. In view of this, a two-step polishing method comprising a first step of polishing the wiring portion metal and a second step of polishing the barrier layer has been studied.

U.S. Pat. No. 4,944,836 JP-A-2-278822 JP-A-8-83780 Japanese Patent Publication No. 2819196

Journal of Electrochemical Society, Vol.138, No.11 (issued in 1991), pages 3460-3464

In the second step of polishing the barrier layer in the above-mentioned two-stage polishing method, an interlayer insulating film such as silicon dioxide or trimethylsilane which is a low-k (low dielectric constant) film is used as a starting material for planarization. In some cases, polishing of an organosilicate glass or a wholly aromatic ring-based Low-k film is required. In that case, by making the polishing rate of the barrier layer and the metal for the wiring portion and the polishing rate of the interlayer insulating film substantially equal so that the polished surface is flat when all of the interlayer insulating film is exposed, the barrier layer, A method of polishing while maintaining the flatness of the surfaces of the metal for the wiring portion and the interlayer insulating film is mentioned.
In order to improve the polishing rate of the interlayer insulating film to the same level as that of the barrier layer and the wiring portion metal, for example, it is conceivable to increase the grain size of the abrasive grains in the conductor polishing liquid of the barrier layer. There is a problem in that polishing flaws occur in the alloy or oxide film and cause electrical characteristics defects. Such electric characteristic defects may occur due to insufficient cleaning after polishing by CMP. On the other hand, in the CMP process, there is a problem that the copper residue on the high-density wiring part cannot be completely removed and a short circuit defect occurs.
In order to improve the polishing rate of the interlayer insulating film to the same level as that of the barrier layer and the metal for the wiring portion, for example, it is conceivable to increase the content of abrasive grains in the polishing liquid for the conductor of the barrier layer. Aggregation of the particles tends to proceed, the particle size in the polishing liquid increases, and there are the same problems as described above.

  In view of the above problems, the present invention provides a polishing slurry for CMP having a highly polished surface. Further, the present invention provides a polishing slurry for CMP in which the polishing rate of the interlayer insulating film is as high as that of the barrier layer and the wiring portion metal. And according to this polishing liquid, the polishing rate of the interlayer insulating film is large, the aggregation of particles is suppressed, the polishing rate of the barrier layer is not lowered, and the polishing rate of the wiring part can be adjusted, and the metal residue after polishing And polishing scratches can be suppressed. It is another object of the present invention to provide a polishing method in manufacturing a semiconductor device or the like that is excellent in miniaturization, thinning, dimensional accuracy, and electrical characteristics, has high reliability, and low cost.

The present invention relates to the following invention.
<1> A polishing slurry for CMP, comprising abrasive grains whose surface is modified with two or more different organic functional groups.
<2> Abrasive grains modified with one or more organic functional groups having the effect of preventing the abrasive grains from precipitating on the surface and one or more organic functional groups having an effect of improving the polishing rate of the interlayer insulating film. <1> The polishing slurry for CMP.
<3> Organic functional groups that modify the surface and have the effect of not precipitating abrasive grains are amino groups, and organic functional groups that have an effect of improving the interlayer insulating film polishing rate are epoxy groups, mercapto groups, methacryloxy groups, and chloropropyl groups. <1>-<2> The polishing slurry for CMP according to <1>, wherein the polishing slurry is at least one selected from fluoropropyl groups and ureido groups.
<4> The polishing slurry for CMP according to <1> to <3>, wherein the abrasive is at least one selected from silica, alumina, ceria, titania, zirconia, and germania.
<5> The polishing slurry for CMP according to <1> to <4>, comprising an organic solvent, a metal oxide solubilizer, and water.
<6> The polishing slurry for CMP according to any one of <1> to <5>, comprising a metal oxidizing agent.
<7> The polishing slurry for CMP according to any one of <1> to <6>, comprising a metal anticorrosive.
<8> An interlayer insulating film having a concave portion and a convex surface, a barrier conductor layer covering the interlayer insulating film along the surface, and a conductive material layer filling the concave portion and covering the barrier conductor layer A first polishing step of polishing the conductive material layer of the substrate having the exposed barrier conductor layer to expose the convex barrier conductor layer, and at least the barrier conductive layer and the concave conductive material layer of any one of <1> to <7> And a second polishing step of exposing the convex interlayer insulating film by chemical mechanical polishing while supplying the CMP polishing liquid.
<9> The polishing method according to <8>, wherein the interlayer insulating film is a silicon film or an organic polymer film.
<10> The polishing method according to <8> or <9>, wherein the conductive material contains copper as a main component.
<11> The barrier conductor layer is a barrier layer that prevents the conductive material from diffusing into the interlayer insulating film, and includes tantalum, tantalum nitride, tantalum alloy, other tantalum compounds, titanium, titanium nitride, titanium alloy, and others. The polishing method according to any one of <8> to <10>, comprising at least one selected from the group consisting of titanium compounds, tungsten, tungsten nitride, tungsten alloys, and other tungsten compounds.

  A polished surface with high flatness can be obtained by the CMP polishing liquid of the present invention. Moreover, the particle size of the abrasive grains does not change even after storage for a certain period, and metal residues and polishing scratches after polishing can be suppressed. Further, the polishing rate of the barrier layer is not lowered, the polishing rate of the interlayer insulating film is high, and the polishing rate of the wiring portion can be adjusted. The polishing method of the present invention in which chemical mechanical polishing is performed using this CMP polishing liquid is highly productive, excellent in miniaturization, thinning, dimensional accuracy, electrical characteristics, and highly reliable semiconductor devices and other electronic devices. It is suitable for manufacturing.

  The polishing slurry for CMP of the present invention contains abrasive grains whose surfaces are modified with two or more different organic functional groups. If necessary, it further contains an organic solvent, a metal oxide solubilizer, and water, and preferably contains a metal oxidizer. Furthermore, you may add a metal corrosion inhibitor etc. as needed.

  Although there is no restriction | limiting in particular as an organic solvent in the polishing liquid for CMP of this invention, The thing which can be mixed with water arbitrarily is preferable. For example, the organic solvent is glycols, glycol monoethers, glycol diethers, alcohols, carbonates, lactones, ethers, ketones, other phenols, dimethylformamide, n-methylpyrrolidone, ethyl acetate, ethyl lactate, Examples include sulfolane. Preferably, it is at least one selected from glycol monoethers, alcohols, and carbonates.

  The metal oxide solubilizer in the present invention is not particularly limited, and examples thereof include organic acids, organic acid esters, ammonium salts of organic acids, inorganic acids, and ammonium salts of inorganic acids. Among these, formic acid, malonic acid, malic acid, tartaric acid, citric acid, salicylic acid, and adipic acid are also used at high CMP rates in that the etching rate can be effectively suppressed while maintaining a practical CMP rate. In this respect, sulfuric acid is suitable for a conductive material containing a metal as a main component. These may be used alone or in combination of two or more.

  Abrasive grains may be added to the CMP polishing liquid of the present invention. There are no particular limitations on the abrasive grains modified with organic functional groups on the surface of the present invention, but inorganic abrasive grains such as silica, alumina, zirconia, ceria, titania, germania, silicon carbide, polystyrene, polyacryl, polyvinyl chloride And those obtained by modifying the surface of organic abrasive grains such as organic functional groups. Silica, alumina, zirconia, ceria, titania, and germania are preferable. Particularly, the colloidal has good dispersion stability in the polishing liquid, few polishing scratches (scratches) generated by CMP, and an average particle size of 70 nm or less. Silica and colloidal alumina are preferable, and colloidal silica and colloidal alumina having an average particle size of 40 nm or less are more preferable. Further, particles in which the primary particles are aggregated less than 2 particles on average are preferable, and particles in which the primary particles are aggregated less than 1.2 particles on average are more preferable. Furthermore, the standard deviation of the average particle size distribution is preferably 10 nm or less, and the standard deviation of the average particle size distribution is more preferably 5 nm or less. These may be used alone or in combination of two or more.

  Colloidal silica is known for its production by hydrolysis of silicon alkoxide or ion exchange of sodium silicate, and colloidal alumina is known for its production by hydrolysis of aluminum nitrate. Colloidal silica is most often used in terms of particle size controllability and alkali metal impurities by a production method by hydrolysis of silicon alkoxide. As the silicon alkoxide, TEMS (tetramethoxysilane) or TEOS (tetraethoxysilane) is generally used. In the method of hydrolyzing in an alcohol solvent, parameters affecting the particle size include the concentration of silicon alkoxide, the concentration and pH of ammonia used as a catalyst, the reaction temperature, the type (molecular weight) of the alcohol solvent, and the reaction time. By adjusting these parameters, a colloidal silica dispersion having a desired particle size and agglomeration degree can be obtained.

The method of modifying the abrasive grain surface with an organic functional group is not particularly limited, and examples thereof include a method of reacting a hydroxyl group present on the abrasive grain surface with a silane coupling agent having an organic functional group. The silane coupling agent is hydrolyzed into silanol in an acidic solution having a pH of about 2 to 6 such as water or acetic acid water, and partially condensed into an oligomer state. And it adsorb | sucks to the abrasive grain surface in a hydrogen bond. The silane coupling agent is not particularly limited, but monomethyltrimethoxysilane, dimethyldimethoxysilane, trimethylmonomethoxysilane, monoethyltrimethoxysilane, diethyldimethoxysilane, triethylmonomethoxysilane, vinyltrimethoxysilane, vinyltriethoxy. Silane, 2- (3,4 Epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryl Trimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 -Acryloxypropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltri Ethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane , 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane , Phenyltriethoxysilane, Examples include oxamethyldisilazane, hexyltrimethoxysilane, decyltrimethoxysilane, trifluoropropylmethoxysilane, and heptadecafluoromethoxysilane. Although there is no restriction | limiting in particular as a reaction method, Although it reacts also at room temperature, you may heat in order to accelerate reaction.

A metal oxidizing agent may be added to the polishing slurry for CMP of the present invention. Examples of the metal oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), nitric acid, potassium periodate, hypochlorous acid, ozone water, etc. Among them, hydrogen peroxide is particularly preferable. These may be used alone or in combination of two or more. When the substrate is a silicon substrate including an integrated circuit element, contamination with alkali metal, alkaline earth metal, halide, or the like is not desirable, and thus an oxidizing agent that does not contain a nonvolatile component is desirable. However, hydrogen peroxide is most suitable because ozone water has a severe compositional change over time. However, when the substrate to be applied is a glass substrate or the like that does not include a semiconductor element, an oxidizing agent that includes a nonvolatile component may be used.

Further, a metal anticorrosive may be added to the CMP polishing liquid of the present invention. Examples of metal anticorrosives include 2-mercaptobenzothiazol, 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazol. Benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxyl (-1H-) benzotriazole, 4-carboxyl (-1H-) benzotriazole methyl ester, 4-carboxyl (-1H-) benzotriazole butyl ester, 4-carboxyl (-1H-) benzotriazol octyl ester , 5-hexylbenzotriazol, [1,2,3-benzotriazolyl-1-methyl] [1,2,4-to Azolyl-1-methyl] [2-ethylhexyl] amine, Torirutoriazo - le, Nafutotoriazo - le, bis [(1-benzotriazolyl) methyl] phosphonic acid.
Further, pyrimidine having a pyrimidine skeleton, 1,2,4-triazolo [1,5-a] pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidine 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trione Hydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6 Hydroxylpyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, 2-methyl-5,7-diphenyl- (1,2,4) Riazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl- (1,2,4) triazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl Examples include -4,7-dihydro- (1,2,4) triazolo (1,5-A) pyrimidine, 4-aminopyrazolo [3,4, -d] pyrimidine and the like. These may be used alone or in combination of two or more.

The blending amount of the silane coupling agent having the effect of not causing the abrasive grains to settle in the polishing liquid of the present invention is preferably 0.0001 to 5% by weight in the polishing liquid. For example, it is preferably 0.0001 to 5 g with respect to 100 g of a silane coupling agent, an organic solvent, a metal oxide solubilizer, water, abrasive grains, and a metal oxidizer (hereinafter referred to as the total amount of all components). 0.001 to 3 g is more preferable, and 0.002 to 2 g is particularly preferable. If the blending amount is less than 0.0001 g, the effect of suppressing the aggregation of abrasive grains is low, and if it exceeds 5 g, the polishing rate of the interlayer insulating film tends to decrease.

The blending amount of the silane coupling agent having the effect of improving the polishing rate of the interlayer insulating film in the polishing liquid of the present invention is preferably 0.0005 to 10% by weight in the polishing liquid. For example, it is preferably 0.0005 to 10 g with respect to 100 g of a silane coupling agent, an organic solvent, a metal oxide solubilizer, water, abrasive grains, and a metal oxidizer (hereinafter referred to as the total amount of all components). 0.002 to 5 g is more preferable, and 0.01 to 3 g is particularly preferable. When the blending amount is less than 0.0005 g, the effect of improving the interlayer insulating film polishing rate is low, and when it exceeds 10 g, the abrasive grains tend to settle.

  The blending amount of the organic solvent in the present invention is preferably 0.1 to 95 g, more preferably 0.2 to 50 g, and more preferably 0.5 to 10 g with respect to 100 g of the total amount of all components. Is particularly preferred. If the blending amount is less than 0.1 g, the wettability of the polishing liquid to the substrate is low, and if it exceeds 95 g, there is a possibility of ignition, which is not preferable in the manufacturing process.

  The blending amount of the metal oxide solubilizer in the present invention is preferably 0.001 to 20 g, more preferably 0.002 to 10 g, and more preferably 0.005 to 5 g, with respect to 100 g of the total amount of all components. It is particularly preferable to do this. When the blending amount is less than 0.001 g, the polishing rate is low, and when it exceeds 20 g, it is difficult to suppress etching and the polished surface tends to be rough. Of the six components, the remaining amount of water may be the remainder and there is no particular limitation as long as it is contained.

  When blending abrasive grains, the blending amount of the abrasive grains in the present invention is preferably 0.01 to 50 g, more preferably 0.02 to 20 g, with respect to 100 g of the total amount of all components. 0.05 to 10 g is particularly preferable. When the blending amount is less than 0.01 g, the polishing rate is low, and when it exceeds 50 g, there is a tendency that many polishing scratches are generated.

  When the oxidizing agent is blended, the blending amount of the oxidizing agent in the present invention is preferably 0.01 to 50 g, more preferably 0.02 to 20 g, with respect to 100 g of the total amount of all components. 0.05 to 10 g is particularly preferable. If the blending amount is less than 0.01 g, metal oxidation is insufficient and the CMP rate is low, and if it exceeds 50 g, the polished surface tends to be rough.

  The blending amount of the metal anticorrosive agent in the present invention is preferably 0 to 10 g, more preferably 0.001 to 5 g, and particularly preferably 0.002 to 2 g with respect to 100 g of the total amount of all components. preferable. If this amount exceeds 10 g, the polishing rate tends to be low.

  In addition to the various components described above, the CMP polishing liquid of the present invention may contain a surfactant, a dye such as Victoria Pure Blue, a colorant such as a pigment such as phthalocyanine green, and the like.

  The CMP polishing liquid of the present invention as described above can be used for chemical mechanical polishing (CMP) of the conductive material layer, the barrier layer, and the insulating film. In CMP under the same conditions, the conductive material layer / barrier layer / insulating film are preferably polished at a polishing rate ratio of 1 / 0.1 to 20 / 0.8 to 20. More preferably, it is 1 / 0.5-10 / 1-10, More preferably, it is 1 / 1.5-5 / 2-5.

  When the polishing rate ratio is 1/1/1, considering the surface hardness of each of the conductive material layer, the barrier layer, and the insulating film to be polished, only the conductive material such as copper is excessively shaved, The polishing rate ratio is particularly preferably 1 / (greater than 1) / (greater than 1) because the barrier layer and the insulating film may easily remain. The remaining polishing of the barrier layer leads to a short circuit between the wirings. On the other hand, if the polishing of the interlayer insulating film is slow, the flatness deteriorates.

  Examples of conductive substances include copper, copper alloys, copper oxides or copper alloy oxides, tungsten, tungsten alloys, silver, gold, and other metal-based materials, and copper is the main component. Is preferred. As the conductive material layer, a film in which the material is formed by a known sputtering method or plating method can be used.

  Examples of the insulating film include a silicon-based film and an organic polymer 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 a wholly aromatic low dielectric constant interlayer insulating film. In particular, organosilicate glass is preferable. These films are formed by a CVD method, a spin coating method, a dip coating method, or a spray method. Specific examples of the insulating film include an interlayer insulating film in an LSI manufacturing process, particularly a multilayer wiring forming process.

  The barrier layer is formed to prevent diffusion of the conductive material into the insulating film and to improve the adhesion between the insulating film and the conductive material. Tungsten, tungsten nitride, tungsten alloy, other tungsten compounds, titanium, titanium nitride, Examples thereof include at least one barrier layer selected from titanium alloys, other titanium compounds, tantalum, tantalum nitride, tantalum alloys, and other tantalum compounds, and a laminated film including this barrier layer.

The polishing method of the present invention comprises an interlayer insulating film having a concave portion and a convex surface, a barrier layer that covers the interlayer insulating film along the surface, and a conductive material layer that fills the concave portion and covers the barrier layer. A first polishing step of polishing the conductive material layer of the substrate having the convex portion to expose the barrier layer of the convex portion, and at least the conductive layer of the barrier layer and the concave portion with the polishing slurry for CMP of the present invention. And a second polishing step of exposing the convex interlayer insulating film by chemical mechanical polishing while supplying.
Here, in the chemical mechanical polishing, by moving the polishing platen and the substrate relatively while supplying the polishing liquid while pressing the substrate having the surface to be polished onto the polishing cloth (pad) of the polishing platen. A method of polishing the surface to be polished is mentioned. Other methods for exposing the interlayer insulating film include a method of contacting a metal or resin brush and a method of spraying a polishing liquid at a predetermined pressure.

  As an apparatus for polishing, for example, when polishing with a polishing cloth, a general apparatus having a holder that can hold a substrate to be polished, and a surface plate that is connected to a motor that can change the number of rotations and has a polishing cloth attached thereto. A polishing apparatus can be used. As an abrasive cloth, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used, and there is no restriction | limiting in particular. The polishing conditions are not limited, but the rotation speed of the surface plate is preferably a low rotation of 200 rpm or less so that the substrate does not jump out. The pressure applied to the polishing cloth of the semiconductor substrate having the surface to be polished is preferably 1 to 100 kPa, and 5 to 50 kPa in order to satisfy the uniformity in the wafer surface of the CMP rate and the flatness of the pattern. Is more preferable. During polishing, a polishing slurry for CMP is continuously supplied to the polishing cloth with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of polishing cloth is always covered with polishing liquid. The substrate after polishing is preferably washed in running water and then dried after removing water droplets adhering to the substrate using spin drying or the like. In order to perform chemical mechanical polishing with the surface state of the polishing cloth always the same, it is preferable to perform a conditioning process of the polishing cloth before polishing. For example, the polishing cloth is conditioned with a liquid containing at least water using a dresser with diamond particles. Subsequently, it is preferable to perform a chemical mechanical polishing process according to the present invention, and further add a substrate cleaning process.

The polishing method of the present invention can be applied to the formation of a wiring layer in a semiconductor device, for example. Hereinafter, embodiments of the polishing method of the present invention will be described along with formation of a wiring layer in a semiconductor device.
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. Further, a metal conductive material layer such as copper covering the barrier layer is formed by vapor deposition, plating or CVD so as to fill the concave portion. The formation thickness of the interlayer insulating film, the barrier layer, and the conductive material is preferably about 0.01 to 2.0 μm, 1 to 100 nm, and 0.01 to 2.5 μm, respectively.

  Next, the conductive material layer on the surface of the semiconductor substrate is polished by CMP using, for example, a polishing liquid for the conductive material having a sufficiently high polishing rate ratio of the conductive material / barrier layer (first first material). Polishing process). Thereby, the barrier layer of the convex part on a board | substrate is exposed on the surface, and the desired conductor pattern with which the said electroconductive substance film was left in the recessed part is obtained. The obtained pattern surface can be polished as a surface to be polished for the second polishing step in the polishing method of the present invention using the CMP polishing liquid of the present invention.

  In the second polishing step, at least the exposed conductive material of the barrier layer and the recess is formed by chemical mechanical polishing using the polishing agent of the present invention capable of polishing the conductive material, the barrier layer, and the interlayer insulating film. To polish. The interlayer insulating film under the convex barrier layer is all exposed, the conductive material layer that becomes the wiring layer is left in the concave portion, and the desired pattern in which the cross section of the barrier layer is exposed at the boundary between the convex portion and the concave portion The polishing is finished when it is obtained. In order to ensure better flatness at the end of polishing, over polishing (for example, if the time until a desired pattern is obtained in the second polishing step is 100 seconds, in addition to this 100 second polishing) Polishing for an additional 50 seconds may be referred to as over-polishing 50%), and may be polished to a depth including a portion of the convex interlayer insulating film.

  An interlayer insulating film and a second-layer metal wiring are further formed on the metal wiring thus formed, an interlayer insulating film is formed again between and on the wiring, and then polished to obtain a semiconductor substrate. Make the surface smooth throughout. By repeating this step a predetermined number of times, a semiconductor device having a desired number of wiring layers can be manufactured.

  The CMP polishing agent of the present invention is not only for polishing a silicon compound film formed on a semiconductor substrate as described above, but also for inorganic insulation such as a silicon oxide film, glass, silicon nitride formed on a wiring board having a predetermined wiring. Optical glass such as films, optical masks such as photomasks, lenses, and prisms, inorganic conductive films such as ITO, glass and crystalline materials, optical integrated circuits, optical switching elements, optical waveguides, end faces of optical fibers, scintillators, etc. It can also be used for polishing substrates such as single crystals, solid state laser single crystals, LED sapphire substrates for blue lasers, semiconductor single crystals such as SiC, GaP, and GaAS, glass substrates for magnetic disks, and magnetic heads.

  Hereinafter, the present invention will be described by way of examples. The present invention is not limited by these examples.

(Polishing liquid preparation method)
The raw materials shown in Table 1 were mixed in each formulation to prepare CMP polishing liquids used in Examples 1-12 and Comparative Examples 1-2.

(substrate)
The following substrates were prepared.
Blanket substrate (a): A silicon substrate on which organosilicate glass (thickness: 1000 nm) is formed by CVD using trimethylsilane as a starting material.
Blanket substrate (b): A silicon substrate formed by CVD of silicon dioxide having a thickness of 1000 nm.
Blanket substrate (c): A silicon substrate on which a tantalum film having a thickness of 200 nm is formed by sputtering.
Blanket substrate (d): A silicon substrate on which a copper film having a thickness of 1600 nm is formed by sputtering.
Preparation of pattern substrate (a): The above-mentioned organosilicate glass (thickness: 1000 nm) was formed as a interlayer insulating layer on a silicon substrate by a CVD method. Grooves having a width of 4.5 μm and a spacing of 0.5 μm are formed on this organosilicate glass by a photolithographic method with a depth of 800 nm and a total width of 2.5 mm, and another groove having a width of 100 μm and a spacing of 100 μm is formed with a depth of 800 nm. A concave portion (groove portion) and a convex portion (non-groove portion) were formed on the surface. Further, along this surface, a tantalum film having a thickness of 200 nm was formed as a barrier layer by sputtering. On the tantalum film, a copper film having a thickness of 1.0 μm was formed as a conductive material layer so as to fill all the grooves by sputtering. The projecting copper film is used as a first polishing step, and the substrate is polished and planarized by high-selectivity CMP for polishing only copper until the convex barrier layer is completely exposed on the surface to be polished ( a) was obtained (polishing time 180 seconds, maximum polishing thickness 1.0 μm)

(Examples 1-12 and Comparative Examples 1-2)
Using each polishing liquid prepared above, each substrate prepared above was subjected to chemical mechanical polishing under the following polishing conditions. In addition, the storage stability of the polishing liquid was evaluated. Table 2 shows the evaluation results of the polishing rate, dishing amount, erosion amount, polishing scratches and storage stability by chemical mechanical polishing.

(Polishing conditions: common to the first and second polishing steps)
Polishing pad: Polyurethane foam resin (Model number: IC1000 manufactured by Rodel)
Polishing pressure: 14 kPa
Relative speed between substrate and polishing surface plate: 70 m / min
Supply amount of polishing liquid: 200 ml / min

(Substrate polishing process)
The pattern substrate was subjected to chemical mechanical polishing with the polishing liquid (a) prepared above for 180 seconds under the above polishing conditions. This corresponded to the first polishing step, and the barrier layer was exposed. Furthermore, chemical mechanical polishing was performed for 90 seconds with the polishing liquid (b) prepared above. This corresponds to the second polishing step. In about 30 seconds, all of the convex interlayer insulating layer was exposed on the surface to be polished, and for the remaining about 60 seconds, this interlayer insulating film was polished on the convex portion.

(Substrate cleaning process)
A sponge brush (made of polyvinyl alcohol) was pressed against the surface to be polished of the patterned substrate polished above, and the substrate and the sponge brush were rotated while supplying distilled water to the substrate, followed by washing for 90 seconds. Next, the sponge brush was removed, and distilled water was supplied to the polished surface of the substrate for 60 seconds. Finally, the substrate was dried by spinning off the distilled water by rotating the substrate at a high speed, and evaluated as follows.

(Evaluation item)
(1) Polishing rate: Among the blanket substrates of (a) to (d) polished and washed under the above conditions, the polishing rate of organosilicate glass (a) and silicon dioxide (b) is determined by the difference in film thickness before and after polishing. Was measured using a Dainippon Screen Mfg. Co., Ltd. film thickness measuring apparatus (product name: Lambda Ace VLM8000LS). Further, the polishing rate of the tantalum film (c) and copper (d) was obtained by converting the film thickness difference before and after polishing from the electric resistance value.
(2) Flatness (dishing amount): The surface of the striped pattern portion of the patterned substrate (a) polished and cleaned under the above conditions, in which the wiring metal (copper) portion width of 100 μm and the interlayer insulating film portion width of 100 μm are alternately arranged From the shape, the amount of film reduction of the wiring metal part relative to the insulating film part was determined by a stylus type step gauge.
(3) Flatness (the amount of erosion): a stripe pattern portion having a total width of 2.5 mm in which the wiring metal portion width 4.5 μm and the interlayer insulating film portion width 0.5 μm are alternately arranged on the pattern substrate (a). The surface shape of the film was measured with a stylus type step meter, and the amount of film reduction of the interlayer insulating film portion near the center of the pattern relative to the interlayer insulating film portion around the stripe pattern was determined.
(4) Polishing scratches: The amount of polishing scratches was measured from the pattern substrate (a) using a pattern wafer defect detection device 2138 manufactured by KLA Tencor, and evaluated by the number per 1 cm ² .
(5) Storage stability: The particle size of the abrasive grains in the polishing liquid after storing the polishing liquid in an oven at 30 ° C. for 6 months was measured using a Coulter Counter N4M type manufactured by Coulter. Further, the blanket substrate and the pattern substrate were polished and cleaned using the polishing liquid under the above conditions, and the polishing rate, dishing amount, erosion amount, and amount of polishing flaws were evaluated.

In Comparative Example 1 and Comparative Example 2, the polishing rate of the organosilicate glass is small, and dishing and erosion are large. Moreover, in Comparative Example 1 and Comparative Example 2, the polishing rate of the organosilicate glass particularly during the storage stability evaluation is low, and dishing and erosion are high. In addition, the amount of polishing scratches is large due to the increase in particle size. On the other hand, in Examples 1-12, the polishing rate of organosilicate glass or silicon dioxide is large, and it has good dishing and erosion characteristics. The amount of polishing scratches is small and good. In addition, the same results were obtained when evaluating the storage stability, the particle diameter hardly changed, and the amount of polishing scratches was small and good.

Claims (11)

A polishing slurry for CMP, comprising abrasive grains having a surface modified with two or more different organic functional groups. 2. The abrasive grains modified with one or more kinds of organic functional groups having an effect of preventing the abrasive grains from precipitating on the surface and one or more kinds of organic functional groups having an effect of improving the interlayer insulating film polishing rate. The polishing liquid for CMP as described. Organic functional groups that modify the surface and have the effect of not precipitating abrasive grains are amino groups, and organic functional groups that have an effect of improving the interlayer insulating film polishing rate are epoxy groups, mercapto groups, methacryloxy groups, chloropropyl groups, fluoropropyl 3. The polishing slurry for CMP according to claim 1, wherein the polishing slurry is at least one selected from a group and a ureido group. 4. The polishing slurry for CMP according to claim 1, wherein the abrasive grains are at least one selected from silica, alumina, ceria, titania, zirconia, and germania. The polishing liquid for CMP according to claim 1, comprising an organic solvent, a metal oxide solubilizer, and water. The polishing liquid for CMP according to any one of claims 1 to 5, further comprising a metal oxidizing agent. The polishing liquid for CMP according to any one of claims 1 to 6, further comprising a metal anticorrosive. A substrate having an interlayer insulating film having a concave portion and a convex surface, a barrier conductor layer covering the interlayer insulating film along the surface, and a conductive material layer filling the concave portion and covering the barrier conductor layer A first polishing step for polishing the conductive material layer to expose the barrier conductor layer of the convex portion, and at least the barrier conductive layer and the conductive material layer of the concave portion for CMP according to claim 1. And a second polishing step of exposing the convex interlayer insulating film by chemical mechanical polishing while supplying a polishing liquid. 9. The polishing method according to claim 8, wherein the interlayer insulating film is a silicon film or an organic polymer film. The polishing method according to claim 8 or 9, wherein the conductive substance contains copper as a main component. The barrier conductor layer is a barrier layer that prevents the conductive material from diffusing into the interlayer insulating film, and includes tantalum, tantalum nitride, tantalum alloy, other tantalum compounds, titanium, titanium nitride, titanium alloy, and other titanium compounds. The polishing method according to claim 8, comprising at least one selected from tungsten, tungsten nitride, tungsten alloy, and other tungsten compounds.