JP2009124092A - Cmp solution for tungsten and method of polishing substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide CMP solution with which a tungsten film is polished at high polishing speed and a polishing method by using the same. <P>SOLUTION: The CMP solution for the tungsten containing abrasive grains, periodic acid, a protection film forming agent and water includes the periodic acid of 0.15 mass% or more to the CMP solution for the tungsten. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a CMP polishing liquid for tungsten and a method for polishing a substrate.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (LSIs). A chemical mechanical polishing (hereinafter referred to as CMP) method is one of them, and is 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. Yes (see, for example, Patent Document 1).

  The formation of the buried wiring using the CMP method will be described. A trench is formed in advance in the substrate, a barrier metal film such as titanium nitride is deposited on the entire surface of the interlayer insulating film such as an oxide film on the surface of the trench, and further, tungsten or the like is embedded in the trench on the entire barrier metal film. A wiring metal film is deposited. Next, an unnecessary wiring gold thin film other than the groove and the underlying barrier metal film are removed by CMP to form a buried wiring. This wiring forming method is called a damascene method. The damascene method is disclosed in Patent Document 2, for example.

  A general method for CMP of a metal film is to polish a surface of a substrate on which a metal film is formed while attaching a polishing pad on a circular polishing platen (platen) and immersing the polishing pad surface in a metal film polishing liquid. Press the pad, rotate the polishing platen with a predetermined pressure (polishing pressure or polishing load) applied to the metal film from the back side of the polishing pad, and the convex part by mechanical friction between the polishing liquid and the convex part of the metal film The metal film is removed.

  The metal film polishing liquid used in CMP is generally composed of an oxidizing agent, solid abrasive grains, and water, and a metal oxide solubilizer, a metal anticorrosive, and the like are further added as necessary. It is considered that the basic mechanism is to first oxidize the metal film surface with an oxidizing agent to form an oxide layer, and then scrape the oxide layer with solid abrasive grains. The oxide layer on the surface of the concave metal film does not touch the polishing pad so much that it does not have the effect of scraping off with solid abrasive grains, so the oxide layer of the metal layer on the convex portion is removed and the substrate surface is flattened with the progress of CMP. (See Non-Patent Document 1, for example).

For example, as a CMP polishing liquid for tungsten, an oxidizing agent such as hydrogen peroxide, a CMP polishing liquid containing a catalyst such as iron ions in a solid abrasive such as silica, an addition of an average particle diameter of silica abrasive and NH ₄ OH There has been proposed a wafer polishing agent or the like that appropriately sets the amount and further contains an oxidizing agent (see, for example, Patent Document 3).

However, when a buried wiring is formed by a CMP method using a conventional CMP polishing liquid for tungsten, it is difficult to obtain a high polishing rate for the tungsten film, and impurities such as iron ions remain on the wafer after polishing and become a semiconductor. The insulating film of the high-density wiring section that causes the phenomenon that the central part of the surface of the embedded metal wiring is isotropically corroded and becomes a dish-like depression (hereinafter referred to as dishing) that deteriorates the device characteristics. Problems such as the occurrence of diminishing phenomena (hereinafter referred to as erosion) were likely to occur. In addition, when adding a metal oxide solubilizer and a metal anticorrosive to a conventional CMP polishing liquid for tungsten, it has not always been easy to balance both agents.
U.S. Pat. No. 4,944,836 Japanese Patent Laid-Open No. 02-278822 Journal of Electrochemical Society, Vol. 138, No. 11 (published in 1991), pages 3460-3464 Japanese Patent Laid-Open No. 10-209092

  An object of the present invention is to provide a CMP polishing liquid capable of polishing a tungsten film at a high polishing rate and a polishing method using the same. In addition, the present invention provides a CMP polishing liquid that can suppress etching, dishing, and erosion without reducing contamination at a high polishing rate without being contaminated by impurities such as iron ions when a buried wiring of a tungsten film is formed by CMP. It is to provide a method for polishing a substrate using the same.

  That is, the present invention provides (2) a CMP polishing liquid for tungsten containing abrasive grains, periodic acid, a protective film forming agent, and water, wherein the periodic acid is used for the CMP polishing liquid for tungsten. The present invention relates to a CMP polishing liquid for tungsten characterized by containing 0.15% by mass or more.

  Further, the present invention provides (2) CMP for tungsten as described in (1) above, wherein the content of the protective film forming agent is 0.005 to 10% by mass with respect to the CMP polishing liquid for tungsten. It relates to the polishing liquid.

  Further, the present invention provides (3) CMP for tungsten according to (1), wherein the content of the protective film forming agent is 0.01 to 5% by mass with respect to the CMP polishing liquid for tungsten. It relates to the polishing liquid.

  In the present invention, any one of the above (1) to (3), wherein (4) the protective film forming agent is at least one selected from a compound having a triazole skeleton and a compound having an imidazole skeleton. The tungsten CMP polishing liquid according to claim 1.

  The present invention also relates to (5) the CMP polishing liquid for tungsten according to any one of (1) to (4), wherein the protective film forming agent is a compound having an imidazole skeleton. .

  In the present invention, (6) the compound having an imidazole skeleton is 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 4-ethyl. The tungsten CMP polishing liquid according to (4) or (5) above, which is at least one compound selected from imidazole, 2,4-dimethylimidazole, and 2-ethyl-4-methylimidazole.

  Moreover, this invention is (7) Any one of said (1)-(6) characterized by the content of the said abrasive grain being 0.01-10 mass% with respect to CMP polishing liquid for tungsten. The present invention relates to a CMP polishing liquid for tungsten according to one item.

  Moreover, this invention is (8) Any one of said (1)-(6) characterized by the content of the said abrasive grain being 0.05-10 mass% with respect to CMP polishing liquid for tungsten. The present invention relates to a CMP polishing liquid for tungsten according to one item.

  The present invention also relates to (9) the CMP polishing liquid for tungsten according to any one of (1) to (8), wherein an average particle diameter of the abrasive grains is 10 nm or more.

  In addition, the present invention relates to (10) the CMP polishing liquid for tungsten according to any one of (1) to (8), wherein an average particle diameter of the abrasive grains is 10 to 80 nm. .

  The present invention also relates to the CMP polishing liquid for tungsten according to any one of (1) to (10) above, which comprises (11) a tungsten anticorrosive.

  Moreover, this invention is (12) Content for the said tungsten anticorrosive agent is 0.1-5.0 mass% with respect to CMP polishing liquid for tungsten, The object for tungsten as described in said (11) characterized by the above-mentioned. The present invention relates to a CMP polishing liquid.

  The present invention also relates to (13) the CMP polishing liquid for tungsten according to (11) or (12), wherein the tungsten anticorrosive is an organic acid.

  The present invention also relates to (14) the CMP polishing liquid for tungsten according to (13), wherein the organic acid is at least one selected from tartaric acid and malic acid.

  In the present invention, (15) the CMP polishing for tungsten according to the above (13) or (14), wherein the content of the organic acid is 5% by mass or less based on the CMP polishing liquid for tungsten. Regarding liquids.

  Further, the present invention provides (16) the CMP polishing for tungsten according to the above (14), wherein the tartaric acid content is 0.1 to 0.7% by mass with respect to the CMP polishing liquid for tungsten. Regarding liquids.

  Further, the present invention provides (17) CMP for tungsten according to (14), wherein the content of malic acid is 0.1 to 1.0% by mass with respect to the CMP polishing liquid for tungsten. It relates to the polishing liquid.

  In the present invention, (18) the object to be polished is at least one selected from tungsten, tungsten nitride, a tungsten alloy, and a tungsten compound. The CMP polishing liquid for tungsten as described in 1 above.

  The present invention also provides: (19) a substrate having a film to be polished while supplying the CMP polishing liquid for tungsten according to any one of (1) to (18) above on a polishing cloth of a polishing surface plate; A polishing method for polishing a film to be polished by relatively moving a polishing platen and a substrate while pressed against a polishing cloth.

The present invention also relates to (20) a method for polishing a substrate for forming a conductor embedded wiring in a semiconductor integrated circuit,
At least selected from the group consisting of tungsten, tungsten nitride, tungsten alloys and tungsten compounds while supplying the CMP polishing liquid for tungsten according to any one of (1) to (18) above onto the polishing cloth of the polishing surface plate One kind of tungsten film and at least one kind of barrier metal film selected from the group consisting of titanium, titanium nitride, titanium alloy, titanium compound, tantalum, tantalum nitride, tantalum alloy and tantalum compound are provided under the tungsten film. The present invention relates to a method for polishing a substrate, wherein the tungsten film and the barrier metal film are continuously polished by relatively moving the polishing surface plate and the substrate while the substrate is pressed against the polishing cloth.

  According to the present invention, a CMP polishing liquid capable of polishing a tungsten film at a high polishing rate and a polishing method using the same can be provided. In addition, according to the present invention, when a buried wiring of a tungsten film is formed by the CMP method, there is no contamination by impurities such as iron ions, and CMP polishing that can suppress etching, dishing and erosion without reducing a high polishing rate. A liquid and a method for polishing a substrate using the liquid can be provided.

  The CMP polishing liquid for tungsten of the present invention is a CMP polishing liquid for tungsten containing abrasive grains, periodic acid, a protective film forming agent and water, and the periodic acid is 0.15 relative to the CMP polishing liquid for tungsten. It is characterized by containing at least mass%. Hereafter, each said component is demonstrated in detail.

(Abrasive grains)
In the present invention, the abrasive grains are contained for polishing the tungsten film by a mechanical polishing action. Examples of the abrasive grains used in the present invention include inorganic abrasive grains such as silica, alumina, ceria, titania, zirconia, germania and silicon carbide, and organic abrasive grains such as polystyrene, polyacryl and polyvinyl chloride. Among these, silica or alumina is preferable, colloidal silica or fumed silica is preferable in that the dispersion stability in the polishing liquid is good and the number of polishing scratches (scratches) generated by CMP is small. Colloidal silica can be produced by a known production method based on hydrolysis of silicon alkoxide or ion exchange of sodium silicate. In terms of particle size controllability and alkali metal impurities, silicon alkoxide such as tetramethoxysilane or tetraethoxysilane is used. The method of hydrolysis is most utilized. Fumed silica can be produced by gas phase hydrolysis of silicon tetrachloride in an oxyhydrogen flame. These abrasive grains can be used alone or in combination of two or more.

  In the present invention, the average grain size of the abrasive grains is preferably 10 nm or more. When the average grain size of the abrasive grains is less than 10 nm, the polishing rate for the tungsten film tends to decrease. Further, when the average grain size of the abrasive grains is larger than 80 nm, the polishing rate for the insulating film tends to increase, and the erosion tends to increase when the insulating film is polished. From the viewpoint of suppressing erosion without reducing the thickness, the average particle size of the abrasive grains is preferably 10 to 80 nm, and more preferably 20 to 60 nm. The average particle diameter of the abrasive grains can be measured using a light scattering method and using an N4 MD Sub-micron Particle Analyzer (manufactured by Beckman Coulter, Inc.).

  The abrasive grains are preferably aggregated particles obtained by agglomerating primary particles, more preferably aggregated particles obtained by agglomerating particles having an average of less than 2 particles, and aggregates obtained by agglomerating particles having an average of less than 1.2 particles. Particular preference is given to particles.

  In the present invention, the content of abrasive grains is preferably 0.01 to 10% by mass with respect to the CMP polishing liquid for tungsten. If the content of the abrasive grains is less than 0.01% by mass, the polishing rate for the tungsten film tends to decrease, and if it exceeds 10% by mass, the storage stability of the polishing liquid may be impaired. Further, when the content of the abrasive grains is less than 0.05% by mass, the polishing rate of the tungsten film with respect to the insulating film is low and the polishing time becomes long, so that the erosion tends to increase when the insulating film is polished. From the viewpoint of suppressing erosion without reducing the high polishing rate for the tungsten film, the content of the abrasive grains is preferably 0.05 to 10% by mass, and preferably 0.1 to 5% by mass. More preferred.

(Periodic acid)
In the present invention, it is important to use a specific amount of periodic acid as an oxidizing agent. Although known oxidants other than periodic acid can be used in combination, periodic acid is an essential component for polishing tungsten film, and it is estimated that chemical polishing action of periodic acid polishes tungsten film. The

The periodic acid used in the present invention is not limited as long as the tungsten film can be polished. For example, orthoperiodic acid (H ₅ IO ₆ ), diorthoperiodic acid (H ₈ I ₂ O _11). ), Metaperiodic acid (HIO ₄ ), mesoperiodic acid (H ₃ IO ₅ ), nimesoperiodic acid (H ₂ I ₄ O ₉ ), etc. Therefore, it is preferable to use orthoperiodic acid.

  In the present invention, the content of periodic acid is 0.15% by mass or more with respect to the CMP polishing liquid for tungsten, preferably 0.2% by mass to 10% by mass, more preferably 0.3% by mass to It is 8 mass%, Most preferably, it is 0.5 mass%-5 mass%. By setting the content of periodic acid to 0.15 mass% or more, the tungsten film is sufficiently oxidized, and the tungsten film can be polished at a high polishing rate of 1500 Å / min or more. If the content of periodic acid exceeds 10% by mass, the polishing rate for the tungsten film tends to be too high and it becomes difficult to control the polishing. In this regard, the polishing conditions of the polishing apparatus are appropriately set. Can be overcome.

(Protective film forming agent)
In the present invention, the protective film forming agent is contained in order to form a protective film on the surface of the tungsten film and suppress corrosion of the tungsten film. Examples of the protective film forming agent include a compound having a triazole skeleton, a compound having a pyrimidine skeleton, a compound having an imidazole skeleton, a compound having a guanidine skeleton, a compound having a thiazole skeleton, and a compound having a pyrazole skeleton. One type of protective film forming agent can be used alone, or two or more types can be mixed and used.

  Examples of the compound having a triazole skeleton include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, and 1-dihydroxy. Propylbenzotriazole, 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-hexylbenzotriazole, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) methyl] Acid, 3-aminotriazole, can be exemplified 5-methyl benzotriazole. Among these, in terms of polishing rate and etching rate, 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 4-amino-4H- 1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, and 5-methylbenzotriazole are more preferable.

  Examples of the compound having an imidazole skeleton include 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 4-ethylimidazole, 2,4-dimethylimidazole, Examples include 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-aminoimidazole and the like.

  Examples of the compound having a pyrimidine skeleton include pyrimidine, 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 -Trihydroxypyrimidine, 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) Triazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5,7-diphenyl- (1,2,4) triazolo (1,5-a) pyrimidine, 2-methylsulfanyl-5 , 7-diphenyl-4,7-dihydro- (1,2,4) triazolo (1,5-A) pyrimidine, 4-aminopyrazolo [3,4, -d] pyrimidine and the like.

  Examples of the compound having a guanidine skeleton include 1,3-diphenylguanidine and 1-methyl-3-nitroguanidine.

  Examples of the compound having a thiazole skeleton include 2-mercaptobenzothiazol, 2-aminothiazole, 4,5-dimethylthiazole, 2-amino-2-thiazoline, 2,4-dimethylthiazole, 2-amino-4- Examples thereof include methyl thiazole.

  Examples of the compound having a pyrazole skeleton include 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone, 3-amino-5-methylpyrazole, 3-amino-5-hydroxypyrazole, and 3-amino-5-methylpyrazole. Can be illustrated.

  Among the protective film forming agents, at least one selected from a compound having a triazole skeleton and a compound having an imidazole skeleton is preferable. From the viewpoint of suppressing etching of the tungsten film and suppressing dishing and erosion of the insulating film without reducing the high polishing rate for the tungsten film, a compound having an imidazole skeleton is preferable, for example, 2-methylimidazole, 2 -At least one selected from ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 4-ethylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole Compounds are preferred.

  In the present invention, the content of the protective film forming agent is preferably 0.005 to 10% by mass with respect to the CMP polishing liquid for tungsten. When the content of the protective film forming agent is less than 0.005 mass% or exceeds 10 mass%, the polishing rate for the tungsten film tends to decrease. Further, from the viewpoint of suppressing etching of the tungsten film and suppressing dishing and erosion of the insulating film without reducing the high polishing rate for the tungsten film, the content of the protective film forming agent is 0.01 to 5% by mass. It is preferable that it is 0.015-5 mass%, and it is especially preferable that it is 0.02-5 mass%. If the content of the protective film forming agent is less than 0.01% by mass, it is difficult to suppress etching, dishing and erosion, and if it exceeds 5% by mass, the protective ability of the tungsten film becomes too strong and the polishing rate becomes slow. Tend.

(water)
In the present invention, water is contained as a solvent and dispersion medium for other components. The water used is preferably one containing as little impurities as possible, and more preferably ultrapure water obtained by removing foreign substances through a filter after removing impurity ions with an ion exchange resin.

(Tungsten anticorrosive)
The CMP polishing slurry for tungsten according to the present invention may contain a tungsten anticorrosive. The tungsten anticorrosive is presumed to have an effect of protecting the surface of the tungsten film (having anticorrosive ability), and can solve the problem of flatness such as dishing and erosion. Examples of the tungsten anticorrosive include organic acids, organic acid esters, ammonium salts with organic acids, inorganic acids, ammonium salts of inorganic acids, and the like, and are not particularly limited as long as they are water-soluble. Specific examples of tungsten anticorrosives include tartaric acid, malonic acid, citric acid, malic acid, glycolic acid, glutamic acid, glycolic acid, oxalic acid, tartaric acid, picolinic acid, nicotinic acid, mandelic acid, picolinic acid, acetic acid, formic acid, succinic acid. Acids, adipic acid, glutaric acid, benzoic acid, quinaldic acid, butyric acid, valeric acid, lactic acid, phthalic acid, fumaric acid, maleic acid, aminoacetic acid, salicylic acid, glyceric acid, pimelic acid and other organic acids, and these organic acid esters And ammonium salts of these organic acids, inorganic acids such as sulfuric acid, nitric acid, phosphoric acid, acetic acid and hydrochloric acid, and ammonium salts of these inorganic acids. Tungsten anticorrosive can be used alone or in combination of two or more.

  Among the tungsten anticorrosives, organic acids are suitable, and examples thereof include tartaric acid, malonic acid, citric acid, malic acid, phthalic acid, and maleic acid. Also, tartaric acid or malic acid is preferable from the viewpoint of suppressing etching of the tungsten film and suppressing dishing or erosion of the insulating film without reducing the high polishing rate for the tungsten film.

  In the present invention, the content of the tungsten anticorrosive is 0.1 to 5% by mass with respect to the CMP polishing liquid for tungsten from the viewpoint of suppressing etching and dishing of the tungsten film and suppressing erosion of the insulating film. Preferably there is.

  Moreover, in this invention, when using an organic acid as a tungsten anticorrosive agent, it is preferable that the content shall be 5 mass% or less with respect to CMP polishing liquid for tungsten.

  In the present invention, when tartaric acid is used alone as the tungsten anticorrosive, the content thereof is preferably 0.1 to 0.7% by mass, and 0.2% by mass with respect to the CMP polishing liquid for tungsten. More preferably, it is -0.6 mass%, and it is more preferable that it is 0.25-0.5 mass%. When the tartaric acid content is less than 0.1% by mass, the tungsten film is not sufficiently protected, and it becomes difficult to suppress etching of the tungsten film. When the content of tartaric acid exceeds 0.7% by mass, the pH of the CMP polishing liquid becomes low, the oxidation of the tungsten film is promoted, and the etching of the tungsten film becomes difficult to suppress.

  In the present invention, when malic acid is used alone as the tungsten anticorrosive, the content thereof is preferably 0.1 to 1.0% by mass with respect to the CMP polishing liquid for tungsten, It is more preferable that it is 0.8 mass%, and it is more preferable that it is 0.3-0.7 mass%. If the content of malic acid is less than 0.1% by mass, the tungsten film is not sufficiently protected and it is difficult to suppress etching of the tungsten film. When the content of malic acid exceeds 1.0% by mass, the pH of the CMP polishing liquid becomes low, the oxidation of the tungsten film is promoted, and the etching of the tungsten film is hardly suppressed.

  In the present invention, when tartaric acid and malic acid are mixed and used as the tungsten anticorrosive, the total content of tartaric acid and malic acid is 0.1 to 0.7 mass relative to the CMP polishing liquid for tungsten. %, More preferably 0.2 to 0.6% by mass, and even more preferably 0.25 to 0.5% by mass. When the content is less than 0.1% by mass, the protection of the tungsten film is insufficient and it becomes difficult to suppress the etching of the tungsten film. When the content exceeds 0.7% by mass, the pH of the CMP polishing liquid becomes low, the oxidation of the tungsten film is promoted, and the etching of the tungsten film is hardly suppressed.

(Polishing target)
For example, as shown in FIG. 1, the CMP polishing liquid for tungsten of the present invention has an insulating film with projections and depressions, a barrier metal film formed thereon, and a tungsten film formed to fill the projections and depressions. It can be used for polishing a polishing object. An object to be polished by the CMP polishing liquid for tungsten of the present invention is a tungsten film, for example, at least one selected from tungsten, tungsten nitride, a tungsten alloy, and a tungsten compound. Among these tungsten films, tungsten, tungsten nitride, tungsten alloy and the like are preferable in terms of the balance between the polishing rate and the etching rate. Note that in this specification, a metal containing tungsten may be simply referred to as tungsten metal.

  The CMP polishing liquid for tungsten according to the present invention can polish a tungsten film at a high polishing rate. In addition, by appropriately selecting the type and content of each component contained in the CMP polishing liquid for tungsten, etching and dishing can be suppressed without reducing the high polishing rate for the tungsten film, and erosion to the insulating film can be suppressed. .

(Polishing method)
In the polishing method of the present invention, while supplying the CMP polishing liquid for tungsten of the present invention onto the polishing cloth of the polishing surface plate, the polishing surface plate and the substrate are relatively moved while the substrate having the film to be polished is pressed against the polishing cloth. This is a polishing method in which the film to be polished is polished by moving the film. The film to be polished is a tungsten film, for example, at least one selected from tungsten, tungsten nitride, a tungsten alloy, and a tungsten compound, and can be formed by a known sputtering method or plating method.

  Further, the polishing method of the present invention is a method of polishing a substrate for forming a conductor embedded wiring in a semiconductor integrated circuit, while supplying the tungsten CMP polishing liquid of the present invention onto a polishing cloth of a polishing surface plate, At least one tungsten film selected from the group consisting of tungsten nitride, tungsten alloy and tungsten compound, and titanium, titanium nitride, titanium alloy, titanium compound, tantalum, tantalum nitride, tantalum alloy and tantalum compound under the tungsten film The tungsten film and the barrier metal film are continuously moved by relatively moving the polishing platen and the substrate in a state where the substrate having at least one kind of barrier metal film selected from the group consisting of is pressed against the polishing cloth. And polishing the substrate. Even if the barrier metal film has a single layer structure consisting of at least one selected from the group consisting of titanium, titanium nitride, titanium alloy, titanium compound, tantalum, tantalum nitride, tantalum alloy and tantalum compound, two or more types The laminated structure which consists of may be sufficient. The barrier metal film in FIG. 1 has a two-layer structure made of titanium and titanium nitride, but is not limited to this. Among the above metals, titanium or titanium nitride is preferable in terms of adhesion to tungsten films such as tungsten, tungsten nitride, and tungsten alloys.

  As a polishing apparatus, a general polishing apparatus having a holder for holding a substrate and a polishing surface plate to which a polishing cloth (pad) can be attached and a motor or the like capable of changing the number of rotations 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 pressing pressure of the substrate having the film to be polished onto the polishing cloth is preferably 1 to 100 kPa, and in order to satisfy the uniformity of the wafer in the wafer surface at the CMP rate and the flatness of the pattern, it is preferably 5 to 50 kPa. More preferred.

  During polishing, the CMP polishing liquid for tungsten of the present invention 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.

  The polishing method according to the present invention includes an interlayer insulating film having a concave portion and a convex surface, a barrier metal film covering the interlayer insulating film along the surface, and a tungsten film filling the concave portion and covering the barrier metal film. It is preferably used for polishing a substrate having In this case, the polishing step is a first polishing step in which the tungsten film is polished to expose the barrier metal film of the convex portion, and at least the barrier metal film and the metal in the concave portion are polished to expose the interlayer insulating film of the convex portion. And a second polishing step. If the polishing liquid of this invention is used, a 1st grinding | polishing process and a 2nd grinding | polishing process can be grind | polished continuously.

  Examples of the interlayer 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.

  In the first polishing step, by polishing the tungsten film, the desired barrier metal film with the convex portions on the substrate exposed on the surface and the tungsten film remaining in the concave portions is obtained. Subsequently, in the second polishing step, at least the exposed barrier metal film and the tungsten film in the recess are polished. Desired pattern in which the interlayer insulating film below the convex barrier metal film is exposed, the tungsten film serving as the metal wiring layer is left in the concave portion, and the cross section of the barrier metal film is exposed at the boundary between the convex portion and the concave portion Polishing is finished when 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.

  In the polishing method of the present invention, it is preferable that the polishing rate ratio of tungsten film / barrier metal film / interlayer insulating film is polished at 1/1 to 4/2 to 5 in polishing under the same conditions.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not restrict | limited by these Examples.

Examples 1-6 and Comparative Examples 1-4
(Preparation of CMP polishing liquid for tungsten)
Each component shown in Table 1 was mixed in a predetermined amount (mass%) to prepare CMP polishing liquids for tungsten of Examples 1 to 6 and Comparative Examples 1 to 4. The colloidal silica having an average particle diameter of 40 nm prepared by hydrolysis of tetraethoxysilane in an aqueous ammonia solution was used. The average particle size was measured by a light scattering method, and N4 MD Sub-micron Particle Analyzer (manufactured by Beckman Coulter, Inc.) was used for the measurement.

(Evaluation of CMP polishing liquid for tungsten)
[Substrate]
Base 1: Silicon substrate on which a 800 nm thick tungsten film is formed Base 2: Silicon substrate on which a 200 nm thick titanium nitride film is formed Base 3: Wiring groove depth in silicon dioxide 0.5 μm, width 0.5-100 μm Next, a titanium nitride film having a thickness of 30 nm is formed as a barrier metal film by a known sputtering method, and a tungsten film as a wiring metal is similarly formed by 1.0 μm by a sputtering method. Silicon substrate embedded by heat treatment [Polishing conditions]
Polishing pad: Polyurethane foam resin (Rohm & Haas, model number IC1010)
Polishing pressure: 210 gf / cm ² (20.6 kPa)
Relative speed between substrate and polishing platen: 100 m / min
[Etching conditions]
Liquid temperature of CMP polishing liquid for tungsten: 60 ° C
Amount of CMP polishing liquid for tungsten: 100 g
Rotation speed: 100min ^-1
(1) Polishing speed for tungsten film Using each of the CMP polishing liquids for tungsten of Examples 1 to 6 and Comparative Examples 1 to 4, the substrate 1 was polished for 1 minute under the above polishing conditions, and the difference in tungsten film thickness before and after polishing was determined. Measurement was performed using a sheet resistance measuring instrument (RT-80 / RG-80, manufactured by Napson Co., Ltd.) to obtain a polishing rate (Å / min).

(2) Etching rate for tungsten film The substrate 1 is etched for 5 minutes under the above etching conditions using the tungsten CMP polishing liquids of Examples 1 to 6 and Comparative Examples 1 to 4, and the difference in tungsten film thickness before and after the etching is sheeted. It measured using the resistance measuring device (RT-80 / RG-80 by Napson Corporation), and calculated | required the etching rate (エ ッ チ ン グ / min).

(3) Polishing Rate for Titanium Nitride Film Using the tungsten CMP polishing liquids of Examples 1 to 6 and Comparative Examples 1 to 4, the substrate 2 was polished for 0.5 minutes under the above polishing conditions, and titanium nitride before and after polishing. The film thickness difference was measured using a sheet resistance measuring device (manufactured by Napson Co., Ltd., RT-80 / RG-80) to determine the polishing rate (Å / min).

(4) Dishing amount Using the CMP polishing liquids for tungsten in Examples 1 to 6 and Comparative Examples 1 to 4 until the substrate 3 is exposed on the entire surface of the substrate under the above polishing conditions until the silicon dioxide on the convex portions of the pattern is exposed. Polishing was performed. Then, using a stylus level difference meter (Dektak V-200Si, manufactured by Nippon Vacuum Technology Co., Ltd.), the surface shape after polishing of the stripe-shaped pattern portion in which the wiring metal portion width 100 μm and the insulating film portion width 100 μm are alternately arranged The dishing amount (Å), which is a film reduction amount of the wiring metal part with respect to the insulating film part, was obtained.

(5) Erosion Amount Using the CMP polishing liquid for tungsten of Examples 1 to 6 and Comparative Examples 1 to 4 under the above polishing conditions, until the silicon dioxide on the convex portions of the pattern is exposed on the entire surface of the substrate. Polishing was performed. Then, using a stylus step meter (Dektak V-200Si, manufactured by Nippon Vacuum Technology Co., Ltd.), a stripe having a total width of 2.5 mm in which a wiring metal part width of 4.5 μm and an insulating film part width of 0.5 μm are alternately arranged. The surface shape of the patterned pattern portion after polishing was measured, and the erosion amount (Å), which is the amount of film reduction of the insulating film portion near the center of the pattern with respect to the insulating film field portion around the striped pattern portion, was obtained.

Table 1 shows the evaluation results of (1) to (5) above.

From Table 1, the CMP polishing liquid for tungsten films of Examples 1 to 6 was able to polish the tungsten film at a high polishing rate. Moreover, the CMP polishing liquid for tungsten films of Examples 1 to 6 had a low etching rate with respect to the tungsten film, and could suppress dishing and erosion. On the other hand, the CMP polishing liquid for tungsten of Comparative Examples 1 to 4 having a low orthoperiodic acid content has a low polishing rate for the tungsten film, and the tungsten film cannot be removed. In addition, since the CMP polishing liquid for tungsten of Comparative Examples 1 to 4 could not remove the tungsten film, the dishing amount and the erosion amount could not be measured.
Examples 7-16
Each component shown in Table 2 was mixed in a predetermined amount (mass%) to prepare tungsten CMP polishing liquids of Examples 7 to 16, and evaluated in the same manner as in Example 1. The results are shown in Table 2.

From Table 2, the CMP polishing liquid for tungsten in Examples 7 to 16 was able to polish the tungsten film at a high polishing rate. In particular, the tungsten film CMP polishing liquids of Examples 7 to 12 in which the content of the protective film forming agent is 0.01 to 5% by mass with respect to the tungsten CMP polishing liquid has a low etching rate with respect to the tungsten film, and dishing. And erosion could be suppressed.

Examples 17-28
Each component shown in Table 3 was mixed in a predetermined amount (mass%) to prepare tungsten CMP polishing liquids of Examples 17 to 28 and evaluated in the same manner as in Example 1. The results are shown in Table 3.

From Table 3, the CMP polishing liquid for tungsten of Examples 17 to 28 was able to polish the tungsten film at a high polishing rate. In particular, the CMP polishing liquid for tungsten films of Examples 17 to 24, in which the protective film forming agent is a compound having an imidazole skeleton, has a low etching rate with respect to the tungsten film, and can suppress dishing and erosion.

Examples 28-35
Each component shown in Table 4 was mixed in a predetermined amount (mass%) to prepare tungsten CMP polishing liquids of Examples 28 to 35 and evaluated in the same manner as in Example 1. The results are shown in Table 4.

From Table 4, the tungsten CMP polishing liquids of Examples 28 to 35 were able to polish the tungsten film at a high polishing rate. In particular, the tungsten film CMP polishing liquids of Examples 28 to 33 having an abrasive content of 0.05 to 10% by mass with respect to the tungsten CMP polishing liquid can polish the tungsten film at a high polishing rate. did it. Moreover, the etching rate with respect to the tungsten film was slow, and dishing and erosion could be suppressed.

Examples 36-40
Each component shown in Table 5 was mixed in a predetermined amount (mass%) to prepare CMP polishing liquid for tungsten of Examples 36 to 40, and evaluated in the same manner as in Example 1. The results are shown in Table 5.

  From Table 5, the CMP polishing liquid for tungsten of Examples 36 to 40 was able to polish the tungsten film at a high polishing rate. In particular, the tungsten film CMP polishing liquid of Example 36 having an average grain size of 10 to 80 nm was able to polish the tungsten film at a high polishing rate. Moreover, the etching rate with respect to the tungsten film was slow, and dishing and erosion could be suppressed.

Examples 41-46
Each component shown in Table 6 was mixed in a predetermined amount (mass%) to prepare the CMP polishing liquid for tungsten of Examples 41 to 46, and evaluated in the same manner as in Example 1. The results are shown in Table 6.

From Table 6, the tungsten CMP polishing liquids of Examples 41 to 46 were able to polish the tungsten film at a high polishing rate. In particular, the tungsten film CMP polishing liquid of Examples 41 and 42 in which the tungsten anticorrosive was tartaric acid or malic acid had a slow etching rate with respect to the tungsten film, and was able to suppress dishing and erosion.

Examples 47-55
Each component shown in Table 7 was mixed in a predetermined amount (mass%) to prepare tungsten CMP polishing liquids of Examples 47 to 55 and evaluated in the same manner as in Example 1. The results are shown in Table 7.

  From Table 7, the CMP polishing liquid for tungsten of Examples 47-55 was able to polish the tungsten film at a high polishing rate. In particular, the tungsten film CMP polishing liquids of Examples 47 to 49 in which the tartaric acid content is 0.1 to 0.7% by mass with respect to the tungsten CMP polishing liquid, and the malic acid content is tungsten CMP. The CMP polishing liquid for tungsten films of Examples 50 to 52, which is 0.1 to 1.0% by mass with respect to the polishing liquid, has a low etching rate with respect to the tungsten film, and can suppress dishing and erosion.

It is sectional drawing of the board | substrate which has a tungsten film.

Claims (20)

  A CMP polishing liquid for tungsten containing abrasive grains, periodic acid, a protective film forming agent, and water, wherein the periodic acid is contained in an amount of 0.15% by mass or more based on the CMP polishing liquid for tungsten. CMP polishing liquid for tungsten.   2. The CMP polishing liquid for tungsten according to claim 1, wherein the content of the protective film forming agent is 0.005 to 10 mass% with respect to the CMP polishing liquid for tungsten.   2. The CMP polishing liquid for tungsten according to claim 1, wherein the content of the protective film forming agent is 0.01 to 5 mass% with respect to the CMP polishing liquid for tungsten.   The CMP polishing liquid for tungsten according to any one of claims 1 to 3, wherein the protective film forming agent is at least one selected from a compound having a triazole skeleton and a compound having an imidazole skeleton.   The CMP polishing liquid for tungsten according to any one of claims 1 to 4, wherein the protective film forming agent is a compound having an imidazole skeleton.   The compound having the imidazole skeleton is 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 4-ethylimidazole, 2,4-dimethylimidazole, The CMP polishing liquid for tungsten according to claim 4 or 5, wherein the CMP polishing liquid is at least one compound selected from 2-ethyl-4-methylimidazole.   7. The CMP polishing liquid for tungsten according to claim 1, wherein the content of the abrasive grains is 0.01 to 10% by mass with respect to the CMP polishing liquid for tungsten.   7. The CMP polishing liquid for tungsten according to claim 1, wherein a content of the abrasive grains is 0.05 to 10% by mass with respect to the CMP polishing liquid for tungsten.   The CMP polishing liquid for tungsten according to any one of claims 1 to 8, wherein an average particle diameter of the abrasive grains is 10 nm or more.   9. The CMP polishing liquid for tungsten according to claim 1, wherein an average particle diameter of the abrasive grains is 10 to 80 nm.   11. The tungsten CMP polishing liquid according to claim 1, further comprising a tungsten anticorrosive.   12. The CMP polishing liquid for tungsten according to claim 11, wherein the content of the tungsten anticorrosive is 0.1 to 5.0% by mass with respect to the CMP polishing liquid for tungsten.   The CMP polishing liquid for tungsten according to claim 11 or 12, wherein the tungsten anticorrosive is an organic acid.   The CMP polishing liquid for tungsten according to claim 13, wherein the organic acid is at least one selected from tartaric acid and malic acid.   15. The CMP polishing liquid for tungsten according to claim 13, wherein the content of the organic acid is 5% by mass or less based on the CMP polishing liquid for tungsten.   The tungsten CMP polishing liquid according to claim 14, wherein the tartaric acid content is 0.1 to 0.7 mass% with respect to the tungsten CMP polishing liquid.   15. The CMP polishing liquid for tungsten according to claim 14, wherein a content of the malic acid is 0.1 to 1.0% by mass with respect to the CMP polishing liquid for tungsten.   18. The CMP polishing liquid for tungsten according to claim 1, wherein the polishing target is at least one selected from tungsten, tungsten nitride, a tungsten alloy, and a tungsten compound.   A polishing surface plate and a substrate in a state where a substrate having a film to be polished is pressed against the polishing cloth while supplying the CMP polishing liquid for tungsten according to any one of claims 1 to 18 onto the polishing cloth of the polishing surface plate. A polishing method for polishing a film to be polished by relatively moving the surface. A method of polishing a substrate for forming a conductor-embedded wiring in a semiconductor integrated circuit,
While supplying the CMP polishing liquid for tungsten according to any one of claims 1 to 18 on the polishing cloth of the polishing surface plate, at least one selected from the group consisting of tungsten, tungsten nitride, tungsten alloy, and tungsten compound Polishing a substrate having a tungsten film and at least one barrier metal film selected from the group consisting of titanium, titanium nitride, titanium alloy, titanium compound, tantalum, tantalum nitride, tantalum alloy and tantalum compound under the tungsten film A method for polishing a substrate, wherein the tungsten film and the barrier metal film are continuously polished by relatively moving the polishing platen and the substrate while being pressed against the cloth.