JP2009218555A - Cmp polishing solution and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP polishing solution which is capable of making a polishing speed of at least a ruthenium layer higher than that using conventional polishing solutions and of polishing layers such as a copper or copper alloy layer, a barrier layer, and an inter-layer insulating film layer at a desired polishing speed, and a polishing method using the same. <P>SOLUTION: The CMP polishing solution contains composite particles having second inorganic abrasive grains deposited at least partially on surfaces of first inorganic abrasive grains, wherein an average secondary particle size of the composite particles is 20 to 800 nm and a mass ratio of the first inorganic abrasive grains to the second inorganic abrasive grains is 1/10 to 10/1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (LSIs). The chemical mechanical polishing (CMP) method is one of them, and is a technique frequently used in planarization of interlayer insulating film layers, formation of metal plugs, and formation of embedded wiring in an LSI manufacturing process, particularly in a multilayer wiring forming process (for example, , See Patent Document 1).

  Recently, in order to increase the integration density and performance of LSI, it has been attempted to use copper or a copper alloy as a wiring material instead of a conventional aluminum alloy. However, copper or copper alloy is difficult to be finely processed by a dry etching method that is frequently used in forming an aluminum alloy wiring. Therefore, a copper or copper alloy layer (hereinafter sometimes simply referred to as a “copper layer”) is deposited by electroplating on the insulating film layer in which grooves (concave portions) are formed in advance, and the grooves are embedded. A so-called damascene method is mainly employed in which the copper layer deposited on the convex portion is removed by CMP to form a buried wiring (see, for example, Patent Document 2).

  In a general method of CMP of a semiconductor substrate on which a copper layer is formed, first, a polishing pad (polishing cloth) is stuck on a circular polishing surface plate (platen), and the surface of the polishing pad is immersed in a polishing liquid. Next, press the copper layer surface of the substrate against the polishing pad, rotate the polishing platen while applying a predetermined pressure (polishing pressure or polishing load) to the substrate from the back surface of the substrate, and polish the polishing liquid and the convex portion of the insulating film layer The copper layer on the protrusion is removed by mechanical friction with the copper layer deposited thereon.

  The polishing liquid for metal wiring such as copper used for CMP is generally composed of an oxidizer and solid abrasive grains, and a metal oxide solubilizer and a protective film forming agent (metal anticorrosive) are added as necessary. The First, it is considered that the basic mechanism is to oxidize the surface of the copper layer with an oxidizing agent and scrape the oxidized layer with solid abrasive grains.

  The oxidized layer on the surface of the copper layer deposited on the groove (concave portion) does not touch the polishing pad so much and does not have the effect of scraping off by the solid abrasive grains, but the oxidized copper layer surface deposited on the convex portion that touches the polishing pad. In the layer, scraping proceeds. Therefore, as the CMP progresses, the copper layer on the convex portion is removed and the substrate surface is planarized (see, for example, Non-Patent Document 1).

  Under the copper layer, as a barrier conductor layer (hereinafter referred to as “barrier layer”) for preventing copper diffusion into the interlayer insulating film, for example, tantalum, tantalum alloy, tantalum nitride, other tantalum compounds, etc. The layer is formed by physical vapor deposition (PVD) or the like. Further, since the copper layer has low adhesion to the barrier layer, a copper or copper alloy thin film layer called a copper seed layer is generally formed by PVD or the like between the two layers.

  A schematic cross-sectional view of a substrate having such a configuration is shown in FIG. In this substrate, on the insulating film layer 3 having recesses and protrusions due to grooves and holes for forming metal wiring, along the recesses and protrusions on the surface of the insulating film layer 3, the barrier layer 1 and The copper seed layer 2 is laminated in this order, and further, the copper layer (metal wiring layer) 4 covers the copper seed layer 2 in a form in which the concave portion caused by the concave portion of the insulating film layer 3 is filled with copper or a copper alloy. is doing.

  PVD used for the formation of a barrier layer and a copper seed layer has a problem that the upper part of the groove formed in the insulating film layer is narrowed at the time of film formation, and this tendency becomes more prominent as the wiring becomes finer. . For this reason, as the miniaturization of wiring has progressed, the embedding property of copper or copper alloy by electroplating has deteriorated, and the generation of voids has become a problem.

  As a means for solving this problem, a layer made of ruthenium, a ruthenium alloy, or a ruthenium compound having excellent adhesion to copper, instead of the copper seed layer or between the copper seed layer and the barrier layer (hereinafter simply referred to as “ruthenium layer”) In some cases, a method using the above is being studied. A schematic cross-sectional view of a substrate having such a configuration is shown in FIG. In this substrate, a ruthenium layer 5 is used instead of the copper seed layer 2 of FIG. The ruthenium layer 5 can be formed by a chemical vapor deposition method (CVD) or an atomic layer deposition method (ALD), and can correspond to the formation of fine wiring.

  On the other hand, it is necessary to remove the exposed ruthenium layer and the barrier layer by CMP between the wirings (projections) other than the wiring part embedded with copper or copper alloy.

  As an attempt to polish a ruthenium layer by CMP, for example, a method is known in which a ruthenium layer used for a lower electrode of a capacitor is polished using a polishing liquid to which cerium ammonium nitrate is added (see Patent Document 3).

In addition, as an attempt to polish a ruthenium layer used for copper wiring by CMP, for example, a method using a polishing liquid to which phosphoric acid, organic acid, conductor metal anticorrosive or alumina abrasive grains are added is known (patent document). 4).
U.S. Pat. No. 4,944,836 Japanese Patent Laid-Open No. 02-278822 Japanese Patent Application Laid-Open No. 2000-167764 US Pat. No. 7,265,055 Journal of Electrochemical Society, Vol.138, No.11 (1991), 3460-3464

  However, in the method described in Patent Document 3 and the like, the polishing target is only a ruthenium layer, and different polishing targets such as a copper layer, a barrier layer, and an insulating film layer are used as in the use for polishing a copper wiring of a semiconductor element. However, it is difficult to polish a plurality of objects to be polished while maintaining flatness.

  Further, the method described in Patent Document 4 or the like does not always satisfy the required performance because the polishing rate of the insulating film layer is not sufficient.

  Therefore, an object of the present invention is to improve at least the ruthenium layer polishing rate as compared with the case of using a conventional polishing liquid, and to obtain a desired layer such as a copper or copper alloy layer, a barrier layer and an insulating film layer. A CMP polishing liquid capable of polishing at a polishing rate and a polishing method using the same are provided.

  In view of the above circumstances, the present invention is a CMP polishing liquid comprising composite particles having the second inorganic abrasive grains attached to at least a part of the surface of the first inorganic abrasive grains, and an average secondary of the composite particles A CMP polishing liquid having a particle diameter of 20 to 800 nm and a mass ratio of the first inorganic abrasive grains to the second inorganic abrasive grains of 1/10 to 10/1 (1:10 to 10: 1) is provided. .

  According to such a CMP polishing liquid, at least the ruthenium layer polishing rate can be improved as compared with the case where a conventional polishing liquid is used, and each of the copper or copper alloy layer, the barrier layer, and the interlayer insulating film layer can be formed in a desired manner. Polishing can be performed at a polishing rate.

  The first inorganic abrasive is preferably alumina, and the second inorganic abrasive is preferably silica.

  The CMP polishing liquid of the present invention preferably further contains a metal oxide solubilizer.

  The average primary particle diameter of the first inorganic abrasive grains is preferably 10 to 500 nm, and the concentration of the first inorganic abrasive grains is preferably 0.1 to 10% by mass with respect to the entire CMP polishing liquid.

  The average primary particle diameter of the second inorganic abrasive grains is preferably 5 to 200 nm, and the concentration of the second inorganic abrasive grains is preferably 0.1 to 15% by mass with respect to the entire CMP polishing liquid.

  The CMP polishing liquid of the present invention preferably further contains an oxidizing agent. The CMP polishing liquid of the present invention preferably further contains a metal anticorrosive.

  The oxidizing agent preferably contains at least one selected from the group consisting of hydrogen peroxide, periodic acid, periodate, iodate, bromate, and persulfate.

  The CMP polishing liquid of the present invention preferably further contains an organic solvent. The CMP polishing liquid of the present invention preferably further contains a surfactant.

  The present invention also provides a substrate and a polishing surface plate while pressing the substrate on which a film to be polished is pressed against a polishing cloth of a polishing surface plate and supplying the CMP polishing liquid of the present invention between the film and the polishing cloth. A method of polishing a substrate is provided by polishing the film.

  According to this polishing method, since the CMP polishing liquid of the present invention is used, at least the ruthenium layer polishing rate can be improved as compared with the case of using a conventional polishing liquid, and a copper or copper alloy layer, Each of the barrier layer and the interlayer insulating film layer can be polished at a desired polishing rate.

  According to the polishing liquid and the polishing method of the present invention, at least each of a ruthenium layer, a copper or copper alloy layer, a barrier layer, and an interlayer insulating film layer can be polished at a desired polishing rate.

  The best mode for carrying out the present invention will be described in detail below.

(Composite particles)
The CMP polishing liquid of the present invention comprises composite particles in which the second inorganic abrasive grains are attached to at least a part of the surface of the first inorganic abrasive grains.

  Specifically, for example, as shown in FIG. 3, (a) a single second inorganic abrasive grain adheres to the surface of a single first inorganic abrasive grain as shown in FIG. (B) a form in which the associated second inorganic abrasive grains adhere to the surface of the single first inorganic abrasive grain, and (c) a single second in the surface of the associated first inorganic abrasive grain. (D) a form in which the associated second inorganic abrasive grains adhere to the surface of the associated first inorganic abrasive grains, and the like. Alternatively, these states may be mixed in the polishing liquid.

  In the present invention, the adhesion state of the composite particles can be observed using a transmission electron microscope (for example, S4700 manufactured by Hitachi, Ltd.). As a specific measuring method, for example, a composite liquid containing the above two kinds of inorganic abrasive grains and other components are mixed to prepare a polishing liquid, and an appropriate amount of this polishing liquid is collected. The amount to be collected is determined in consideration of the abrasive concentration. For example, when the abrasive concentration is 1% by mass, about 0.2 cc is collected. The collected polishing liquid is dried and observed with a transmission electron microscope.

  As the first inorganic abrasive grains, those having high hardness are preferable, and specific examples thereof include alumina, silicon carbide, ceria and the like, among which alumina is preferable, and α-alumina is more preferable.

  The amount of the first inorganic abrasive added is preferably 0.1% by mass to 10% by mass with respect to the entire polishing liquid, and more preferably in the range of 0.2% by mass to 8.0% by mass. preferable. If this addition amount is 0.1% by mass or more, a physical scraping action can be obtained, and the polishing rate by CMP tends to increase. Moreover, if it is 10 mass% or less, it exists in the tendency which can suppress that a particle | grain coagulates and settles. Further, even if the amount exceeds 10% by mass, there is a tendency that an increase in the polishing rate commensurate with the addition is not observed. These tendencies tend to be more prominent with respect to the ruthenium layer polishing rate.

  As the second inorganic abrasive grains, those having a silanol group are preferable, and specific examples thereof include silica and the like, among which fumed silica and colloidal silica are preferable, and colloidal silica is particularly preferable. .

  The amount of the second inorganic abrasive added is preferably 0.1% by mass to 15% by mass and more preferably 0.5% by mass to 12% by mass with respect to the entire polishing liquid. If this addition amount is 0.1% by mass or more, a sufficient physical scraping action can be obtained, and the polishing rate by CMP tends to increase. Further, even if an amount exceeding 15% by mass is added, there is a tendency that an increase in polishing rate commensurate with the addition is not observed. These tendencies tend to be noticeable depending on the polishing rate of the barrier layer and the interlayer insulating film layer.

  The primary particle diameter of the first inorganic abrasive grains is preferably 500 nm or less, more preferably 300 nm or less, and more preferably 200 nm or less in terms of flatness and the ability to suppress scratches remaining on the polished surface after polishing. It is particularly preferable that the thickness is 150 nm or less. Further, the lower limit of the primary particle diameter is not particularly limited, but is preferably 10 nm or more, particularly preferably 20 nm or more, and 50 nm in that sufficient physical scraping action can be obtained. It is very preferable that it is above.

  The primary particle diameter of the second inorganic abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, and particularly preferably 130 nm or less in terms of flatness. Further, the lower limit of the primary particle diameter is not particularly limited, but is preferably 5 nm or more, and particularly preferably 10 nm or more, from the viewpoint that a sufficient physical scraping action can be obtained.

  The primary particle diameter of the first inorganic abrasive grains is preferably larger than the primary particle diameter of the second inorganic abrasive grains.

  The mass ratio of the first inorganic abrasive grains to the second inorganic abrasive grains is 1/10 to 10/1. The lower limit of the mass ratio is more preferably 0.2 or more in that the ruthenium layer tends to have a high polishing rate. In addition, the upper limit of the mass ratio is more preferably 5 or less, and particularly preferably 3 or less, from the viewpoint of facilitating suppression of settling of abrasive grains. If this mass ratio is less than 0.1, the ruthenium layer polishing rate tends to be low, and if it exceeds 10, the aggregation and precipitation of abrasive grains become prominent when dibasic organic acids are present in the polishing liquid. Tend.

  The average secondary particle diameter of the composite particles is preferably 20 to 800 nm or less. From the viewpoint of improving flatness, the average secondary particle diameter is preferably 500 nm or less, more preferably 400 nm or less, and particularly preferably 300 nm or less. Moreover, the average secondary particle diameter is more preferably 20 or more, and more preferably 50 or more in that the ability to remove the mechanical reaction layer (oxide layer) by the composite particles can be ensured and the polishing rate becomes faster. Particularly preferred.

  In the present invention, the primary particle diameter of the composite particles in the CMP polishing liquid can be measured using a transmission electron microscope (for example, S4700 manufactured by Hitachi, Ltd.). As a specific measuring method, for example, a composite liquid containing the above two kinds of inorganic abrasive grains and other components are mixed to prepare a polishing liquid, and an appropriate amount of this polishing liquid is collected. The amount to be collected is determined in consideration of the abrasive concentration. For example, when the abrasive concentration is 1% by mass, about 0.2 cc is collected. The collected polishing liquid is dried and observed.

  In the present invention, the average secondary particle diameter of the composite particles refers to the secondary particle diameter of the composite particles in the CMP polishing liquid. For example, a light diffraction scattering type particle size distribution meter (for example, manufactured by COULTER Electronics, Inc.) COULTER N4SD).

(Oxidant)
An oxidizing agent can also be added to the CMP polishing liquid of the present invention. Examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), periodic acid, periodate, iodate, bromate, persulfate, etc. Among them, hydrogen peroxide is particularly preferable. These can be used individually by 1 type or in mixture of 2 or more types.

  When the substrate to be polished is a silicon substrate including an integrated circuit element, contamination with alkali metal, alkaline earth metal, halide, or the like is not desirable, and therefore an oxidizing agent that does not contain a nonvolatile component is desirable. However, if the substrate to be polished 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.

When the oxidizing agent is added, the addition amount is preferably 0.05 to 20% by mass, more preferably 0.1 to 10% by mass, based on the entire polishing liquid, It is especially preferable that it is 5 mass%.
By making this addition amount 0.05% by mass or more, it becomes possible to sufficiently oxidize the metal, and the polishing rate of the ruthenium layer, the barrier layer, and the metal wiring layer tends to increase, and it is 20% by mass or less. By doing so, roughening of the polished surface can be particularly prevented.

(Metal oxide solubilizer)
A metal oxide solubilizer may be added to the CMP polishing liquid of the present invention for the purpose of promoting polishing of the metal film. The metal oxide solubilizer has an action of dissolving the metal oxidized by the oxidizer. It is preferable to use an acid or an alkali as the metal oxide solubilizer.

  The metal oxide solubilizer is not particularly limited as long as it is water-soluble, and a compound different from the above oxidizing agent is used. For example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methyl Hexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, lactic acid, glyoxylic acid, 3-hydroxyacetic acid, 2-hydroxyacetic acid, hydroacrylic acid, pyruvic acid, crotonic acid, gluconic acid, Organic acids such as mandelic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid and citric acid, these organic acid esters and these organic Examples include acid ammonium salts. Further, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, and ammonium salts of these inorganic acids such as ammonium persulfate, ammonium nitrate and ammonium chloride, chromic acid and the like can be mentioned. Further, ammonia, dimethylamine, trimethylamine, triethylamine, propylenediamine, ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate, chitosan, and the like can be given. These can be used individually by 1 type or in mixture of 2 or more types.

  Among these, formic acid, glycolic acid, lactic acid, glyoxylic acid, malonic acid, malic acid, maleic acid, tartaric acid, in that the etching rate can be effectively suppressed while maintaining a practical polishing rate. Citric acid, phosphoric acid, and nitric acid are suitable for the ruthenium layer.

  When the metal oxide solubilizer is added, the addition amount is preferably 0.001 to 10% by mass with respect to the entire polishing liquid. By making this addition amount 0.001% by mass or more, the polishing rate of ruthenium layers, barrier layers, and metal wiring layers by CMP tends to increase, and the lower limit is more preferably 0.01% by mass or more. It is preferably 0.02% by mass or more. Moreover, when it exceeds 10 mass%, there exists a tendency for the etching suppression of a metal wiring layer to become difficult at the time of grinding | polishing, and as an upper limit, it is more preferable that it is 8 mass% or less, and it is 5 mass% or less. Particularly preferred.

(Metal anticorrosive)
A metal anticorrosive (conductive metal anticorrosive) can also be added to the CMP polishing liquid of the present invention. The metal anticorrosive is a compound that suppresses etching of a metal layer, particularly a metal wiring layer, and improves dishing characteristics.

  Specific examples of the metal anticorrosive include imine, azole, mercaptan, polysaccharide and the like. Among the above, imine is capable of suppressing the etching rate of the metal layer and achieving both the polishing rate of the metal layer. Of these, those forming a ring and azoles are preferred. These can be used alone or in combination of two or more.

  Specific examples of the imine include dithizone, loin (2,2′-biquinoline), neocuproin (2,9-dimethyl-1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl). -1,10-phenanthroline) and cupelazone (biscyclohexanone oxalyl hydrazone).

  Azole exhibits good anticorrosive ability for copper. Specific examples thereof include benzimidazole-2-thiol, triazinedithiol, triazinetrithiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl)] thiobutyric acid, 2-mercapto. Benzothiazole), 1,2,3-triazole, 1,2,4-triazole, 2-amino-1H-1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 3, 5-diamino-1H-1,2,4-triazole, 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-benzotriazole octyl ester, 5-hexyl benzotriazole, [1,2,3-benzotriazolyl-1-methyl] [ 1,2,4-triazolyl-1-methyl] [2-ethylhexyl] amine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] phosphonic acid, tetrazole, 5-amino-tetrazole, 5- Examples thereof include methyl-tetrazole, 1-methyl-5-mercaptotetrazole, 1-N, N-dimethylaminoethyl-5-tetrazole and the like.

  Specific examples of mercaptans include nonyl mercaptan and dodecyl mercaptan.

  Specific examples of polysaccharides include glucose and cellulose.

  In the case of adding a metal anticorrosive, the amount added is preferably 0.005 to 2.0% with respect to the entire polishing liquid in terms of achieving both an etching suppression function and a polishing rate. It is preferably 0.01% or more from the viewpoint that performance can be obtained with higher etching, and more preferably 0.02% or more. Moreover, it is more preferable to set it as 1.0% or less at the point which becomes easy to obtain a suitable grinding | polishing rate, and it is especially preferable to set it as 0.5% or less.

(Surfactant)
A surfactant can also be added to the CMP polishing liquid of the present invention. The surfactant used in the present invention can be used without particular limitation as long as it is a compound that can adsorb on the metal film layer and the interlayer insulating film layer and can change the wettability of the film surface. It can be adsorbed on the surface and control the polishing rate. Surfactants are generally classified into four types: nonionic surfactants, anionic surfactants, cationic surfactants and amphoteric surfactants.

  Moreover, the surfactant in this invention can also use the fluorine-type surfactant which has a carbon- fluorine chain as a hydrophobic group. For example, perfluoroalkanesulfonic acid and its derivatives are exemplified. Perfluorooctane sulfonic acid and its derivatives are preferred. Fluorosurfactants are also classified into the same four types as described above.

  Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylenepropyl perfluorooctanesulfonamide, polyoxyethylene-polyoxypropylene block polymer, polyoxyethylene Ethylene glycerin fatty acid ester, polyoxyethylene hydrogenated castor oil, polyethylene glycol fatty acid ester, propyl-2-hydroxyethyl perfluorooctanesulfonamide, sorbitan fatty acid ester, glycerin fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide, polyoxyethylene alkyl Examples thereof include amines and derivatives thereof. Moreover, glycols, such as acetylene diol and its ethylene oxide adduct, can be mentioned. The “polyoxyethylene” is a concept including not only one having two or more added ethylene oxides (n) but also one added.

  Specific examples of the anionic surfactant include alkylbenzene sulfonate, perfluorooctane sulfonic acid, bis [2- (N-propylperfluorooctanesulfonylamino) ethyl] ester, and alkyl sulfosuccinate. Examples thereof include salts, alkyl sulfonates, alkyl ether carboxylates, alcohol sulfate esters, alkyl ether sulfate esters, alkyl phosphate ester salts, and the like.

  Specific examples of the cationic surfactant include aliphatic alkylamine salts and aliphatic quaternary ammonium salts. Examples of the amphoteric surfactant include aminocarboxylates. These surfactants are used alone or in combination of two or more.

As the surfactant, nonionic surfactants and anionic surfactants are preferable from the viewpoint of preventing sedimentation of abrasive grains, and those not containing an alkali metal are particularly preferable. More preferably, polyethylene glycol type nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene propyl perfluorooctanesulfonamide, glycols, glycerin fatty acid ester, sorbitan fatty acid ester, fatty acid alkanol At least one surfactant selected from amide, alcohol sulfate ester salt, alkyl ether sulfate ester salt, alkylbenzene sulfonate salt, and alkyl phosphate ester salt is preferable.
Examples of the polyethylene glycol type nonionic surfactant include polyethylene glycol fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, and polyethylene glycol monooleate.

  In the case of adding a surfactant, the addition amount is preferably 0.00001 to 20% by mass with respect to the entire polishing liquid from the viewpoint of dispersibility, prevention of settling, and polishing flaws. It is preferable that it is 0.0001 mass% or more at the point which becomes easy to obtain the wettability with respect to a surface. Moreover, since there exists a tendency for a grinding | polishing rate to fall when surfactant is added too much, in order to suppress such a tendency, it is more preferable to set it as 10 mass% or less, and to 5.0 mass% or less. Is particularly preferred.

(Organic solvent)
An organic solvent can also be added to the CMP polishing liquid of the present invention. By adding an organic solvent, it is adsorbed on the metal film layer and the interlayer insulating film layer, and the wettability of the film surface can be changed. In particular, it is adsorbed on the surface of the Low-k film, and the polishing rate can be controlled.

  The organic solvent is not particularly limited as long as it has the functions described above. However, since the CMP polishing liquid is often an aqueous dispersion, a solvent that can be arbitrarily mixed with water is preferable. Examples of such an organic solvent include lactones, glycols, ethers, alcohols, ketones, and carbonic acid esters. Among these, glycols can be used to improve the polishing rate of low-k films. And at least one selected from alcohols and derivatives thereof, alcohols, and carbonates. These organic solvents can be used individually by 1 type or in combination of 2 or more types.

  Specific examples of the lactones include carbonate esters such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; butyrolactone, propyrolactone, and the like.

  Specific examples of the glycols and derivatives thereof include, for example, glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, and diethylene glycol. Monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl Ether, trip Pyrene glycol monoethyl ether, ethylene glycol monopropyl ether, propylene glycol monopropyl ether, diethylene glycol monopropyl ether, dipropylene glycol monopropyl ether, triethylene glycol monopropyl ether, tripropylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene Glycol monoethers such as glycol monobutyl ether, diethylene glycol monobutyl ether, dipropylene glycol monobutyl ether, triethylene glycol monobutyl ether, tripropylene glycol monobutyl ether, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol di Chill ether, dipropylene glycol dimethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether or ethylene glycol diethyl ether, propylene glycol diethyl ether, diethylene glycol diethyl ether, dipropylene glycol diethyl ether, triethylene glycol diethyl ether, tripropylene glycol diethyl ether or ethylene Glycol dipropyl ether, propylene glycol dipropyl ether, diethylene glycol dipropyl ether, dipropylene glycol dipropyl ether, triethylene glycol dipropyl ether, tripropylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol Examples thereof include derivatives of glycols such as glycol diethers such as cold dibutyl ether, diethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, triethylene glycol dibutyl ether, and tripropylene glycol dibutyl ether.

  Specific examples of ethers include tetrahydrofuran, dioxane, dimethoxyethane, polyethylene oxide, ethylene glycol monomethyl acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and the like.

Specific examples of alcohols include methanol, ethanol, propanol, n-butanol, n-pentanol, n-hexanol, and isopropanol.
Specific examples of ketones include acetone and methyl ethyl ketone.

Specific examples of the carbonate esters include ethylene carbonate and propylene carbonate.
Other examples include phenol, dimethylformamide, n-methylpyrrolidone, ethyl acetate, ethyl lactate, sulfolane and the like.

  The amount of the organic solvent added is not particularly limited as long as it improves the wettability of the polishing liquid to the substrate and does not decrease the solubility of the polishing liquid component. It is preferable to contain 0.1-95 mass% with respect to the whole. From the viewpoint of obtaining wettability of the polishing liquid to the substrate, it is more preferably 0.2% by mass or more, and particularly preferably 0.5% by mass or more. Further, from the viewpoint of maintaining the solubility of the polishing liquid component, it is more preferably 50% by mass or less, and particularly preferably 10% by mass or less.

(Water-soluble polymer)
A water-soluble polymer can be added to the CMP polishing liquid of the present invention in that the flatness after polishing can be improved. In view of the above, the weight average molecular weight of the water-soluble polymer is preferably 500 or more, more preferably 1500 or more, and particularly preferably 5000 or more. The upper limit of the weight average molecular weight is not particularly specified, but is preferably 5 million or less from the viewpoint of solubility. When the weight average molecular weight is less than 500, a high polishing rate tends not to be exhibited.

The weight average molecular weight can be measured using a standard polystyrene calibration curve by gel permeation chromatography (GPC), and more specifically can be measured under the following conditions.
Equipment used: Hitachi L-6000 (Hitachi, Ltd.)
Column: Gel pack GL-R420 + gel pack GL-R430 + gel pack GL-R440 (3 in total) [trade name, manufactured by Hitachi Chemical Co., Ltd.]
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 ml / min.
Detector: L-3300RI [Hitachi, Ltd.]

  The water-soluble polymer having a weight average molecular weight of 500 or more is not particularly limited as long as the solubility of the components of the polishing liquid does not decrease and the abrasive grains do not aggregate. Specifically, for example, polysaccharides, polycarboxylic acids Examples thereof include a vinyl compound, a vinyl polymer, a glycol compound, and the like, and these can be used alone or in combination of two or more. As said polycarboxylic acid type compound, polycarboxylic acid or its salt, polycarboxylic acid ester, or its salt is mentioned.

Specific examples of the polysaccharide include alginic acid, pectic acid, carboxymethylcellulose, agar, curdlan, and pullulan. Specific examples of the polycarboxylic acid-based compound include, for example, polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, Polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic acid ammonium salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt And polycarboxylic acids such as polyglyoxylic acid, polycarboxylic acid esters and salts thereof.
Furthermore, specific examples of the vinyl polymer include polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein. Polyethylene glycol or the like can also be used.

  When the above compound is used, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with an alkali metal, an alkaline earth metal, a halide, or the like is not desirable. Therefore, an acid or an ammonium salt thereof is desirable. This is not the case when the substrate is a glass substrate or the like.

  Among the above-mentioned compounds, pullulan, polymalic acid, polymethacrylic acid, polyacrylic acid, polyacrylamide, polyvinyl alcohol and polyvinylpyrrolidone, esters thereof and ammonium salts thereof are preferable because of high flatness.

(PH)
The pH of the CMP polishing liquid of the present invention is preferably 2 to 12 from the viewpoint of increasing the CMP polishing rate of the ruthenium layer. When the pH is 2 or more or the pH is 12 or less, the polishing rate tends to be further improved. The pH is more preferably 2 to 11, and particularly preferably 2 to 10.

  The CMP polishing liquid of the present invention contains composite particles in which the second inorganic abrasive grains are attached to at least a part of the surface of the first inorganic abrasive grains. By using in combination with components, more preferable polishing characteristics can be obtained taking advantage of the characteristics of the inorganic abrasive grains. For example, it is possible to obtain an effect of further improving the polishing rate of the ruthenium layer, the barrier layer, and the copper layer by using the composite particles in combination with the oxidizing agent or / and the metal oxide dissolving agent. Further, by using the composite particles and the metal anticorrosive agent in combination, it is possible to obtain an effect of suppressing the polishing rate of the copper film while maintaining the polishing rate of the ruthenium layer and the barrier layer.

(Polishing method)
Next, the polishing method of the present invention will be described.
In the polishing method of the present invention, the polishing surface of the substrate is pressed against the polishing cloth of the polishing surface plate, the CMP polishing liquid of the present invention is supplied between the polishing surface and the polishing cloth, In this polishing method, the surface to be polished is polished by moving the substrate relative to the polishing surface plate while applying a predetermined pressure to the surface opposite to the surface).

  As the polishing apparatus, for example, a general polishing apparatus having a motor or the like that can change the number of rotations and having a surface plate to which a polishing cloth (pad) can be attached and a holder that holds the substrate can be used. . Although there is no restriction | limiting in particular as abrasive cloth, A general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used. The polishing conditions are not particularly limited, but it is preferable to set the rotation speed of the surface plate to a low rotation of 200 rpm or less so that the substrate does not jump out.

  The pressure applied to the substrate pressed against the polishing cloth (polishing pressure) is preferably 4 to 100 kPa, and more preferably 6 to 50 kPa from the viewpoint of uniformity within the substrate surface and flatness of the pattern. By using the CMP polishing liquid of the present invention, the ruthenium layer can be polished at a high polishing rate at a low polishing pressure. The fact that polishing is possible with a low polishing pressure is important from the viewpoint of preventing peeling of the polishing layer, chipping, fragmentation, cracking, etc., and the flatness of the pattern.

  During polishing, a CMP polishing liquid 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 a spin dryer or the like.

  The substrate that exhibits the best effect of the CMP polishing liquid of the present invention is a substrate having a barrier film or a layer containing ruthenium, preferably at least an insulating film layer, a barrier layer, and ruthenium on a semiconductor wafer such as silicon. A substrate in which a layer and a metal wiring layer are formed in this order.

  A general example is the substrate shown in FIG. In this substrate, the barrier layer 1 and the ruthenium layer 5 are arranged in this order on the surface of the insulating film layer 3 on the insulating film layer 3 having the concave and convex portions due to the grooves and holes for forming the metal wiring. The ruthenium layer 5 is covered in such a manner that the metal wiring layer (conductive material layer) 4 is stacked along with the concave portions and the convex portions, and the concave portions caused by the concave portions of the insulating film layer 3 are filled with metal. .

  The metal forming the metal wiring layer 4 is preferably at least one selected from copper, a copper alloy, a copper oxide, or a copper alloy oxide. The metal wiring layer 4 can be formed by a known sputtering method or plating method.

  Examples of the material for forming the ruthenium layer 5 include at least one selected from ruthenium, a ruthenium alloy, and other ruthenium compounds.

  The barrier layer 1 is a layer that prevents the conductive material from diffusing into the insulating film layer. The material for forming the barrier layer is selected from tantalum, tantalum alloy, tantalum nitride, other tantalum compounds, titanium, titanium alloy, titanium nitride, other titanium compounds, tungsten, tungsten nitride, tungsten alloy, or other tungsten compounds. At least one selected from the above.

The insulating film layer 3 is made of an SiO ₂ film or an insulating film (Low-k film) that can reduce the parasitic capacitance between elements and wirings as compared with the SiO ₂ film. Examples of such insulating films include inorganic films such as SiOF and Si—H containing SiO ₂ , organic inorganic hybrid films such as carbon containing SiO ₂ (SiOC) and methyl group containing SiO ₂ , or Teflon (registered trademark) polymers and polyimides. Examples thereof include at least one selected from organic polymer films such as a polymer, a polyallyl ether polymer, and a parelin polymer. On the other hand, these insulating films are inferior in mechanical strength to conventional SiO ₂ . By making these porous, the dielectric constant of the insulating film can be further reduced. However, since it is known that the mechanical strength further decreases with this, it is preferable to select appropriately (for example, see IEDM Tech. Digest, (1999), pages 619 to 622).

  Although the above-mentioned substrate can be polished in one step using the CMP polishing liquid of the present invention, it is preferable to polish in two steps or three steps in consideration of the hardness of each layer.

For example, in the substrate shown in FIG. 1B, as shown in FIG. 2A, until a slight metal wiring layer 4 is left on the convex portion of the ruthenium layer 5, or as shown in FIG. A first polishing step for polishing the metal wiring layer 4 until the ruthenium layer 5 or the barrier layer 1 is exposed, and at least an insulating film layer by polishing the ruthenium layer 5 and the barrier layer 1 as shown in FIG. Polishing can be performed by two-stage polishing including a second polishing step for polishing all the barrier layers 1 on the three convex portions.
For the purpose of further flattening, the first step can be divided into a first A step and a first B step, and three-step polishing can be performed. 2B or FIG. 2 (b) or FIG. 2 (b) under conditions where the metal wiring layer 4 has a high polishing rate, for example, the 1A step of rough cutting until the film thickness of the metal wiring layer 4 reaches 200 to 300 nm. The first step can be divided into the first B step of polishing to a state as shown in c).
When performing such two-stage or three-stage polishing, it is preferable that the CMP polishing liquid of the present invention is used at least in the final polishing step.

  When the polishing liquid of the present invention as described above is used for the chemical mechanical polishing (CMP) of the above-described substrate, the metal wiring layer / ruthenium layer or the barrier layer / insulating film has a polishing rate ratio in CMP under the same conditions. Polishing at 1 / 0.01 to 20 / 0.01 to 20 is preferable. As the polishing conditions for determining the polishing rate ratio, for example, the polishing apparatus is Mirra (manufactured by APPLIED MATERIALS), the polishing pad is a foamed polyurethane resin having closed cells, the polishing pressure is 13.7 kPa, the polishing liquid flow rate is 200 mL / And a relative speed between the substrate and the polishing platen: 70 m / min.

The metal wiring layer / ruthenium layer or barrier layer / interlayer insulating film is more preferably polished at a polishing rate ratio of 1 / 0.05 to 10 / 0.05 to 10, more preferably 1 / 0.1 to 10 / 0.01. It is particularly preferable that the polishing is performed at 10 to 10. By setting this ratio (metal wiring layer / ruthenium layer or barrier layer / interlayer insulating film) to 10 or less, it becomes possible to more highly prevent the metal wiring layer from being excessively polished and causing dishing. Good damascene wiring can be formed. On the other hand, if this ratio exceeds 10, the ruthenium layer, the barrier layer, and the interlayer insulating film layer are not polished at a sufficient speed, and there is a tendency that it takes a long time to remove unnecessary layers in the second polishing step.
On the other hand, when the metal wiring layer / ruthenium layer or barrier layer and the metal wiring layer / insulating film are less than 0.05, the metal wiring layer is not polished at a sufficient rate, and the first polishing step in the two-step polishing is insulated. When the removal of the metal wiring layer other than the groove or hole on the film layer is incomplete, it takes a long time to remove the unnecessary metal wiring layer in the second polishing step.

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

(Abrasive dispersibility)
The CMP polishing liquid used in Examples 1 to 4 is 0.5% by mass of maleic acid, 4% by mass of colloidal silica (primary particle diameter 30 nm, secondary particle diameter 68 nm), and the balance is pure with respect to the weight of the polishing liquid. Prepared with water. In Examples 1 and 3, α-alumina (primary particle diameter 100 nm, secondary particle diameter 120 nm) is further 0.2% by mass. In Examples 2 and 4, α-alumina (primary particle diameter 100 nm, secondary particle diameter 120 nm) is further added. 0.4% by mass was added. Further, the CMP polishing liquid used in Comparative Example 1 contains 0.5% by mass of maleic acid, 0.2% by mass of α-alumina (primary particle size 100 nm, secondary particle size 120 nm), and the remaining pure water. Prepared. The CMP polishing liquid used in Comparative Example 2 was prepared by adding 0.5% by mass of maleic acid, 2% by mass of colloidal silica (primary particle size of 30 nm, secondary particle size of 68 nm), and pure water in the balance. The pH of the polishing liquid was adjusted by the amount of ammonia added. Examples 3 and 4 were measured after storing the polishing liquid at room temperature (25 ° C.) for 60 days.
The zeta potential and secondary particle size of the abrasive grains in these polishing liquids were measured. The results are shown in Table 1.

(Liquid property evaluation)
Measurement temperature: 25 ± 5 ° C
Zeta potential, secondary particle size measuring device: Malvern Instruments Ltd. 1 ml of the CMP polishing liquids of Examples 1 to 4 and Comparative Examples 1 and 2 diluted 20 times were supplied to a zeta potential / particle size measurement system Zetasizer 3000HS, and the zeta potential and secondary particle size were determined.
pH measurement: Using a model number PHL-40 manufactured by Electrochemical Instrument Co., Ltd., the value was measured 1 minute after the start of measurement.

Hereinafter, the results shown in Table 1 will be described in detail.
In the polishing liquid of Example 1, the same first inorganic abrasive grains and acid as in Comparative Example 2 were added, but 4% by mass of colloidal silica was further added as the second inorganic abrasive grains. The first inorganic abrasive is α-alumina, and the acid is maleic acid. In Example 1, unlike Comparative Example 1, the zeta potential showed a negative value. Further, the same abrasive dispersibility as in Comparative Example 2 was exhibited. Moreover, when the abrasive grain adhesion form of the abrasive grains was confirmed with an electron microscope, the single second inorganic abrasive grain adhered to the surface of the single first inorganic abrasive grain as shown in FIG. It was.

  In the polishing liquid of Example 2, the same first inorganic abrasive grains and acid as in Comparative Example 2 were added, but 4 mass% of colloidal silica was further added as the second inorganic abrasive grains. The first inorganic abrasive is α-alumina, and the acid is maleic acid. In Example 2, unlike Comparative Example 1, the zeta potential showed a negative value. Further, the same abrasive dispersibility as in Comparative Example 2 was exhibited. Moreover, when the abrasive grain adhesion | attachment form of the abrasive grain was confirmed with the electron microscope, it was a form like Fig.3 (a).

  The polishing liquid of Example 3 is a liquid obtained by adding the same first and second inorganic abrasive grains and acid as in Example 1 and stored at room temperature for 60 days. The first inorganic abrasive grains are α-alumina, the second inorganic abrasive grains are colloidal silica, and the acid is maleic acid. In Example 3, unlike Comparative Example 1, the zeta potential showed a negative value. Further, the same abrasive dispersibility as in Comparative Example 2 was exhibited. Moreover, when the abrasive grain adhesion | attachment form of the abrasive grain was confirmed with the electron microscope, it was a form like Fig.3 (a).

  The polishing liquid of Example 4 is a liquid obtained by adding the same first and second inorganic abrasive grains and acid as in Example 2 for 60 days at room temperature. The first inorganic abrasive grains are α-alumina, the second inorganic abrasive grains are colloidal silica, and the acid is maleic acid. In Example 4, unlike Comparative Example 1, the zeta potential showed a negative value. Further, the same abrasive dispersibility as in Comparative Example 2 was exhibited. Moreover, when the abrasive grain adhesion | attachment form of the abrasive grain was confirmed with the electron microscope, it was a form like Fig.3 (a).

(Polishing liquid preparation method)
The CMP polishing liquid used in Examples 5 to 8 and Comparative Example 3 is 0 to 0.4 mass% of the first inorganic abrasive grains shown in Table 2 and 1 of the second inorganic abrasive grains with respect to the weight of the polishing liquid. It was prepared by adding 0.0% by mass, 3.0% by mass of hydrogen peroxide, 0.5% by mass of acid, 0.2% by mass of benzotriazole (BTA), and pure water in the balance. The pH of the polishing liquid was adjusted by the amount of ammonia added.
Using these polishing liquids, the substrate to be polished was polished under the following polishing conditions.

(Liquid property evaluation)
Measurement temperature: 25 ± 5 ° C
pH: Measured with Model No. PHL-40 manufactured by Electrochemical Instruments.
(CMP polishing conditions)
Polishing device: Desktop lapping device (Nano Factor)
Polishing liquid flow rate: 11 mL / min Substrate: A silicon substrate on which a ruthenium film having a thickness of 0.3 μm is formed by sputtering.
Polishing pad: Foam polyurethane resin with closed cells (Roder model number IC1000)
Polishing pressure: 29.4 kPa
Relative speed between substrate and polishing surface plate: 25 m / min Supply amount of polishing liquid: 11 ml / min Polishing time: 1 minute Cleaning: After polishing, the wafer was thoroughly washed with running water, and then water droplets were removed and dried.

(Abrasive product evaluation items)
Polishing rate: The polishing rate of the ruthenium film polished and washed under the above conditions was determined by converting the film thickness difference before and after polishing from the electrical resistance value.

  Table 3 shows the Ru polishing rate (RuRR) when the CMP polishing liquids of Examples 5 to 8 and Comparative Example 3 were used.

Hereinafter, the results shown in Table 3 will be described in detail.
In Example 5, the same second inorganic abrasive grains, oxidizing agent, acid, and metal anticorrosive agent as in Comparative Example 3 were added, but 0.1 mass% of α alumina was further added as the first inorganic abrasive grains. It is a thing. The second inorganic abrasive grains are colloidal silica, the oxidizing agent is hydrogen peroxide, the acid is malic acid, and the metal anticorrosive is BTA. In Example 5, the ruthenium polishing rate was 32 nm / min, which was faster than Comparative Example 3.

  In Example 6, the same second inorganic abrasive grains, oxidizing agent, acid, and metal anticorrosive agent as in Comparative Example 3 were added, but 0.2 mass% of α-alumina was further added as the first inorganic abrasive grains. It is a thing. The second inorganic abrasive grains are colloidal silica, the oxidizing agent is hydrogen peroxide, the acid is malic acid, and the metal anticorrosive is BTA. In Example 6, the ruthenium polishing rate was 38 nm / min, which was faster than Comparative Example 3.

  In Example 7, the same second inorganic abrasive grains, oxidizing agent, acid, and metal anticorrosive agent as in Comparative Example 3 were added, but 0.3 mass% of α-alumina was further added as the first inorganic abrasive grains. It is a thing. The second inorganic abrasive grains are colloidal silica, the oxidizing agent is hydrogen peroxide, the acid is malic acid, and the metal anticorrosive is BTA. In Example 7, the ruthenium polishing rate was 42 nm / min, which was faster than Comparative Example 3.

  In Example 8, the same second inorganic abrasive grains, oxidizing agent, acid, and metal anticorrosive agent as in Comparative Example 3 were added, but 0.4 mass% of α-alumina was further added as the first inorganic abrasive grains. It is a thing. The second inorganic abrasive grains are colloidal silica, the oxidizing agent is hydrogen peroxide, the acid is malic acid, and the metal anticorrosive is BTA. In Example 8, the ruthenium polishing rate was 44 nm / min, which was faster than Comparative Example 3.

The CMP polishing liquid used in Examples 9 to 11 and Comparative Examples 4 to 6 is 0 to 1.0 mass% of the first inorganic abrasive grains shown in Table 4 with respect to the total amount of the polishing liquid, and the second inorganic abrasive grains. 0.1 to 5.0% by mass, 1.5 to 3% by mass of the oxidizing agent shown in Table 4, 0.5% by mass of acid, 0.2% by mass of BTA, and the balance containing pure water. Prepared. Further, Example 10 was prepared by further containing 8% by mass of propylpropylene glycol (PG) as an organic solvent. The pH of the polishing liquid was adjusted by the amount of ammonia added.
Using these metal polishing liquids, the substrate to be polished was polished under the following polishing conditions.

(Liquid property evaluation)
Measurement temperature: 25 ± 5 ° C
pH: Measured with Model No. PHL-40 manufactured by Electrochemical Instruments.
(CMP polishing conditions)
Polishing device: Mirra (Applied Materials)
Polishing liquid flow rate: 200 mL / min Substrate: (1) A silicon substrate on which a copper film (Cu film) having a thickness of 1.5 μm is formed by sputtering.
(2) A silicon substrate on which a ruthenium film (Ru film) having a thickness of 0.3 μm is formed by sputtering.
(3) A silicon substrate on which a tantalum nitride film (TaN film) having a thickness of 0.2 μm is formed by sputtering.
(4) A silicon substrate on which a silicon dioxide film (SiO ₂ film) having a thickness of 1 μm is formed by a CVD method.
(5) A silicon substrate on which an organosilicate glass (SiOC film) having a thickness of 1 μm is formed by a CVD method.
Polishing pad: Foam polyurethane resin with closed cells (Model number IC1010 manufactured by Rodel)
Polishing pressure: 13.7 kPa
Relative speed between substrate and polishing platen: 70 m / min Polishing time: 1 minute

(Cleaning after CMP)
After the CMP treatment, the substrate was washed with a PVA brush and ultrasonic water and then dried with a spin dryer.

  The presence or absence of polishing scratches was confirmed by visual inspection of the substrate after CMP, optical microscope observation, and electron microscope observation. As a result, no significant polishing scratches were observed in all examples and comparative examples.

(Abrasive product evaluation items)
Polishing rate: Among the blanket substrates (1) to (4) polished and cleaned under the above conditions, the difference in film thickness before and after polishing of the copper film (1), ruthenium film (2) and tantalum nitride film (3). Calculated from the electrical resistance value. Moreover, the film thickness difference before and behind polishing of silicon dioxide (4) was measured and determined using a Dainippon Screen Mfg. Co., Ltd. film thickness measuring device (product name: Lambda Ace VLM8000LS).

The copper polishing rate (CuRR), ruthenium polishing rate RuRR), tantalum nitride polishing rate (TaNRR), SiO ₂ polishing rate (SiO ₂ RR), and SiOC polishing rate (SiOCRR) in Examples 9 to 11 and Comparative Examples 4 to 6 Table 5 shows.

Hereinafter, the results shown in Table 5 will be described in detail.
In Example 9, the same oxidizing agent, acid, and metal anticorrosive agent as in Comparative Examples 4 and 5 were added, but 1 mass% α-alumina and 5.0 mass% colloidal silica were added to the abrasive grains. . The oxidizing agent is hydrogen peroxide, the acid is malic acid, and the metal anticorrosive is BTA. In Example 9, the copper polishing rate and the SiOC polishing rate were the same as those in Comparative Examples 4 and 5. On the other hand, the ruthenium polishing rate is 28 nm / min, which is faster than Comparative Example 4, the tantalum nitride polishing rate is 65 nm / min, and the SiO ₂ polishing rate is 29 nm / min, which is faster than Comparative Example 5. It was.

In Example 10, the same acid and metal anticorrosive agent as those in Comparative Examples 4 and 5 were added, but 1 mass% of α alumina, 5.0 mass% of colloidal silica as abrasive grains, and 8 mass of PG as an organic solvent. %, And 1.5% by mass of hydrogen peroxide as an oxidizing agent. The acid is malic acid and the metal anticorrosive is BTA. In Example 10, the polishing rate equivalent to that of Comparative Examples 4 and 5 was obtained as the copper polishing rate. On the other hand, the ruthenium polishing rate is 20 nm / min, which is faster than Comparative Example 4, the tantalum nitride polishing rate is 59 nm / min, and the SiO ₂ polishing rate is 35 nm / min, which is faster than Comparative Example 5. It was. The SiOC polishing rate was 36 nm / min, which was faster than Comparative Examples 4 and 5.

In Example 11, the same oxidizing agent, acid, and metal anticorrosive agent as in Comparative Examples 4 and 5 were added, but 1 mass% of α-alumina and 0.1 mass% of colloidal silica were added to the abrasive grains. is there. The oxidizing agent is hydrogen peroxide, the acid is malic acid, and the metal anticorrosive is BTA. In Example 11, the copper polishing rate and the SiOC polishing rate were the same as those in Comparative Examples 4 and 5. On the other hand, the ruthenium polishing rate was 26 nm / min, which was faster than Comparative Example 4, but the tantalum nitride polishing rate was 35 nm / min and the SiO ₂ polishing rate was 10 nm / min, which was slower than Comparative Example 4, The polishing rate was the same as in Example 5.

FIG. 1 is a cross-sectional view showing an example of a substrate to be polished according to the present invention. (A) is sectional drawing of the board | substrate which used the copper seed layer in order to maintain the adhesiveness of a conductor film and a barrier layer, (b) is sectional drawing of the board | substrate which replaced the copper seed layer with the ruthenium layer. FIG. 2 is a schematic view showing an example of a polishing method according to the present invention. (A), (b) is sectional drawing which shows the state after the 1st grinding | polishing process of the grinding | polishing target object shown in FIG.1 (b), (c) is a cross section which shows the damascene wiring formed by the grinding | polishing method based on this invention. FIG. FIG. 3 is a schematic view showing an example of composite particles according to the present invention. (A) is a schematic diagram showing a state in which a single second inorganic abrasive grain adheres to the surface of a single first inorganic abrasive grain, and (b) shows an association with the surface of a single first inorganic abrasive grain. Schematic showing a state where the second inorganic abrasive grains adhered, (c) is a schematic diagram showing a state where the single second inorganic abrasive grains adhere to the surface of the associated first inorganic abrasive grains, d) is a schematic view showing a state in which the associated second inorganic abrasive grains adhere to the surface of the associated first inorganic abrasive grains.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Barrier layer, 2 ... Copper seed layer, 3 ... Insulating film layer, 4 ... Metal wiring layer, 5 ... Ruthenium layer.

Claims (13)

A CMP polishing liquid comprising composite particles having the second inorganic abrasive grains attached to at least a part of the surface of the first inorganic abrasive grains,
The average secondary particle size of the composite particles is 20 to 800 nm,
A CMP polishing liquid, wherein a mass ratio of the first inorganic abrasive grains to the second inorganic abrasive grains is 1/10 to 10/1.   The CMP polishing liquid according to claim 1, wherein the first inorganic abrasive grains are alumina.   The CMP polishing liquid according to claim 1 or 2, wherein the second inorganic abrasive is silica.   The CMP polishing liquid according to any one of claims 1 to 3, further comprising a metal oxide dissolving agent.   CMP polishing liquid as described in any one of Claims 1-4 whose average primary particle diameter of a said 1st inorganic abrasive grain is 10-500 nm.   The CMP polishing liquid according to claim 1, wherein the concentration of the first inorganic abrasive grains is 0.1 to 10% by mass with respect to the entire CMP polishing liquid.   CMP polishing liquid as described in any one of Claims 1-6 whose average primary particle diameter of a said 2nd inorganic abrasive grain is 5-200 nm.   The CMP polishing liquid according to claim 1, wherein the concentration of the second inorganic abrasive grains is 0.1 to 15% by mass with respect to the entire CMP polishing liquid.   The CMP polishing liquid according to claim 1, further comprising an oxidizing agent.   The CMP polishing liquid according to any one of claims 1 to 9, further comprising a metal anticorrosive.   The said oxidizing agent contains at least 1 sort (s) chosen from the group which consists of hydrogen peroxide, periodic acid, periodate, iodate, bromate, and persulfate. CMP polishing liquid.   The CMP polishing liquid according to any one of claims 1 to 11, further comprising an organic solvent.   A substrate on which a film to be polished is formed is pressed against a polishing cloth of a polishing platen and pressurized, and the CMP polishing liquid according to any one of claims 1 to 12 is supplied between the film and the polishing cloth. A method for polishing a substrate, wherein the film is polished by moving the substrate and a polishing surface plate.

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