JP2006066839A - Metal impurity remover used for cmp process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CMP process metal impurity remover which is excellent in performance for removing metal impurities attached to the surface of a semiconductor substrate subjected to a CMP treatment without having any adverse effect on the semiconductor substrate in the manufacture of semiconductor elements, such as ICs, LSIs and the like, and liquid crystal panel elements. <P>SOLUTION: The metal impurity remover, which is used after a CMP treatment is carried out, consists of a hydrofluorocarbon and an oxygen-containing organic compound. Further, it is preferable that ethanol or propylene glycol monomethyl ether is used as the above oxygen-containing organic compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a metal impurity removing agent having excellent metal impurity removal performance in a CMP process. In particular, a metal impurity remover excellent in metal impurity removal performance on the substrate surface, useful in the CMP process in the manufacture of semiconductor elements such as IC and LSI and liquid crystal panel elements, and a substrate surface using the metal impurity remover The present invention relates to a method for removing metal impurities.

  In recent years, with the high integration of LSI, chemical mechanical polishing (hereinafter referred to as “chemical mechanical polishing”) such as planarization of an insulating film such as an interlayer insulating film, element isolation on a silicon substrate, via formation, copper damascene wiring formation, etc. Abbreviated as “CMP.”) Technology has been introduced into the semiconductor manufacturing process. CMP is a technique that uses a slurry, which is a mixture of abrasive particles and chemicals, to combine chemical action and physical action to polish and planarize the insulating film and metal material. The surface is contaminated with metal impurities from the slurry. These metal impurities not only deteriorate the electrical characteristics of the substrate itself, but also contaminate the production line. Therefore, it is necessary to remove the metal impurities adsorbed by the CMP process before the next step.

As a general method for removing metal impurities adsorbed by the CMP process, there is an immersion process using a cleaning liquid. Patent Documents 1 and 2 disclose performing an immersion treatment using a cleaning liquid containing an organic acid such as oxalic acid or citric acid and mainly containing water. However, in order to obtain good metal impurity removal performance with these aqueous cleaning solutions, brush cleaning is essential, and damage such as peeling of the low dielectric constant film due to brush cleaning is large.
Also, recently, the insulating film subjected to CMP treatment has been changed from a conventional silicon oxide film to methyl siloxane, an organic spin-on-glass that is a porous film thereof, or a carbon-containing silicon oxide film obtained by chemical vapor deposition. , Is moving to low dielectric constant materials with high surface hydrophobicity. The above-mentioned cleaning liquid containing water as a main component has poor wettability with respect to an insulating film using such a new material, and has a problem that a sufficient cleaning effect cannot be obtained, and the exposed copper wiring is corroded. On the other hand, there is hydrofluorocarbon (Patent Document 3) as a non-aqueous cleaning solution. Even if the substrate after CMP treatment is immersed and cleaned using this, it is effective in suppressing copper corrosion, but metal impurity removal performance. Was not enough.

Japanese Patent Laid-Open No. 10-72594 JP 2001-7071 A JP-A-10-316596

  An object of the present invention is to provide a metal impurity removing agent that is excellent in metal impurity removal performance on a substrate surface after CMP treatment and has little adverse effect on the substrate in the manufacture of semiconductor elements such as IC and LSI and liquid crystal panel elements. There is.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have excellent metal impurity removal performance by using a metal impurity remover containing hydrofluorocarbon and oxygen-containing organic compound, to the substrate. The present invention has been completed by finding that a metal impurity removing agent for CMP process is obtained that has little adverse effect and is particularly useful for the production of semiconductor elements such as IC and LSI and liquid crystal panel elements.

（Ｒ_１は、−ＣＨＦ−ＣＨ_２−で表される炭素鎖を示す。Ｒｆ_１およびＲｆ_２は、各々、パーフルオロアルキル基であり、また、Ｒｆ_１およびＲｆ_２は互いに結合して環を形成していてもよい。）
（３）上記記載のＣＭＰ工程用金属不純物除去剤をＣＭＰ処理後の基板表面に接触させ、金属不純物を除去する工程を有する金属不純物除去方法、
を提供するものである。 That is, the present invention
(1) Metal impurity removing agent for CMP process, comprising hydrofluorocarbon and oxygen-containing organic compound,
(2) The metal impurity removing agent for CMP process as described above, wherein the hydrofluorocarbon is represented by the following formula (1):

(R ₁ represents a carbon chain represented by —CHF—CH ₂ —. Rf ₁ and Rf ₂ are each a perfluoroalkyl group, and Rf ₁ and Rf ₂ are bonded to each other to form a ring. (It may be formed.)
(3) A metal impurity removal method comprising a step of bringing the metal impurity remover for CMP process described above into contact with the substrate surface after the CMP treatment and removing the metal impurities;
Is to provide.

  The metal impurity removing agent of the present invention is particularly useful in the manufacture of semiconductor elements such as IC and LSI, and liquid crystal panel elements because it is particularly excellent in metal impurity removal performance on the substrate surface after CMP treatment and hardly adversely affects the substrate. It is.

（Ｒ_１は、−ＣＨＦ−ＣＨ_２−で表される炭素鎖を示す。Ｒｆ_１およびＲｆ_２は、各々、パーフルオロアルキル基であり、また、Ｒｆ_１およびＲｆ_２は互いに結合して環を形成していてもよい。） The hydrofluorocarbon used in the present invention preferably has 4 to 6 carbon atoms, particularly preferably 5 carbon atoms. When the carbon number is within the above range, the metal impurity removal performance is improved, and recovery and reuse are facilitated.
The hydrofluorocarbon may be either a chain or a ring, but is preferably a ring from the viewpoint of metal impurity removal performance.
Among hydrofluorocarbons, trihydrohydrofluorocarbons having 4 to 6 carbon atoms are preferable from the viewpoint of metal impurity removal performance, and trihydrohydrofluorocarbons having 4 to 6 carbon atoms represented by the following formula (1) are particularly preferable.

(R ₁ represents a carbon chain represented by —CHF—CH ₂ —. Rf ₁ and Rf ₂ are each a perfluoroalkyl group, and Rf ₁ and Rf ₂ are bonded to each other to form a ring. (It may be formed.)

  The boiling point of the hydrofluorocarbon used in the present invention is preferably 25 ° C. to 150 ° C., particularly preferably 50 ° C. to 100 ° C., from the viewpoint of metal impurity removal performance and ease of handling.

Specific examples of preferred hydrofluorocarbons include 1,1,1,2,4,4,4-heptafluoro-n-butane, 1,1,1,2, from the viewpoint of ease of handling and metal impurity removal performance. , 2,3,5,5,5-nonafluoro-n-pentane, 1,1,1,2,2,4,5,5,5-nonafluoro-n-pentane, 1,1,1,2,2 , 3,3,4,6,6,6-undecafluoro-n-hexane, 1,1,1,2,2,3,3,5,6,6,6-undecafluoro-n-hexane A chain fluorinated hydrocarbon having 4 to 6 carbon atoms such as 1,1,1,2,2,4,5,5,6,6,6-undecafluoro-n-hexane; 1,2,2,3-pentafluorocyclobutane, 1,1,2,2,3,3,4-heptafluorocyclopentane, and , 1, 2, 2, 3, 3, 4, 4, 5-nonafluorocyclohexane, etc., cyclic fluorinated hydrocarbons having 4 to 6 carbon atoms; , 2,3,5,5,5-nonafluoro-n-pentane, 1,1,1,2,2,4,5,5,5-nonafluoro-n-pentane, and 1,1,2,2, 3,3,4-Heptafluorocyclopentane is preferred, and 1,1,2,2,3,3,4-heptafluorocyclopentane is particularly preferred.
Hydrofluorocarbons may be used singly or in combination of two or more, but are preferably used singly for ease of recovery and reuse.

  The oxygen-containing organic compound used in the present invention is not particularly limited as long as it is an organic compound having an oxygen atom in the molecule, but is preferably liquid at room temperature. The boiling point of the oxygen-containing organic compound is preferably 50 to 200 ° C, more preferably 80 to 150 ° C, and particularly preferably 90 to 120 ° C. When it is in the above range, a metal impurity removing agent for CMP process that is easy to handle and has better metal impurity removal performance can be obtained.

  Specific examples of the oxygen-containing organic compound include ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, 3-methyl-3-methoxybutanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether (butyl carbitol). Glycol ethers such as ethylene glycol and propylene glycol; sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; 1,3-dimethyl-2-imidazolidinone, N, N′-dimethylpropylene urea and 1,1,3 -Ureas such as tetramethylurea; methanol, ethanol, isopropanol, n-propanol, n-butanol, s-butanol, t-butanol, n-pentanol, isopentanol, t-amyl alcohol, n-hexanol, iso Alcohols such as hexanol, 2-ethylhexanol and n-octanol; acetone, 2-butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-methyl-2-butanone, cyclopentanone, cyclohexanone, 2-methyl Ketones such as cyclopentanone and 2-methylcyclohexanone; methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate Esters such as pill, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, methyl valerate and ethyl valerate; phenol, p-chlorophenol, o-cresol, m-cresol and p-cresol Phenols; volatile organic silicones such as hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane; From the viewpoint of impurity removal performance, glycol ethers, ketones and alcohols are preferred, glycol ethers and alcohols are more preferred, propylene glycol monomethyl ether and ethanol are more preferred. Ethanol is particularly preferred.

In the metal impurity removing agent for CMP process of the present invention, the weight ratio of (hydrofluorocarbon) / (oxygen-containing organic compound) is preferably 1000/1 to 80/20, more preferably 99/1 to 90/10, particularly preferably. 97/3 to 92/8 Furthermore, the total proportion of the hydrofluorocarbon and the oxygen-containing organic compound in the metal impurity removing agent for CMP process of the present invention is preferably 70% by weight or more, more preferably 90% by weight. Particularly preferred is 99% by weight or more.
When it is within the above range, a metal impurity removing agent for CMP process having better metal impurity removing performance can be obtained.

  The metal impurity removing agent for CMP process of the present invention may contain various organic solvents and additives as necessary, as long as it does not deviate from the characteristic configuration of the present invention and does not impair the effect. Good. For example, there are organic solvents and additives for the purpose of improving the uniformity of the metal impurity removing agent, lowering the melting point, adjusting the detergency, interfacial activation, stabilization, oxidation prevention, ultraviolet absorption and defoaming.

  The organic solvent is not particularly limited in its type, and examples thereof include hydrocarbons, nitriles, heterocyclic compounds, chlorinated hydrocarbons and other fluorinated hydrocarbons. A combination of more than one species can be used. The amount of the organic solvent in the metal impurity removing agent for CMP process is preferably 30% by weight or less, more preferably 10% by weight or less, and particularly preferably 1% by weight or less.

  Specific examples of hydrocarbons include n-pentane, n-hexane, n-heptane, isohexane, isoheptane, n-octane, isooctane, n-decane, isodecane, n-undecane, n-dodecane and n-tridecane. Aliphatic hydrocarbons; cycloaliphatic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene;

  Specific examples of nitriles include acetonitrile and benzonitrile.

  Specific examples of the heterocyclic compounds include pyridine and N-methylpyrrolidone.

  Specific examples of chlorinated hydrocarbons include methylene chloride, dichloroethane, dichloroethylene, trichloroethylene, and perchloroethylene.

  Other fluorinated hydrocarbons include carbon atoms and fluorine atoms, and may contain oxygen atoms and unsaturated bonds, but are other than the hydrofluorocarbons. Of these, those having a boiling point of 25 ° C. or higher are preferred. Specific examples of such other fluorinated hydrocarbons include perfluoropropyl methyl ether, perfluorobutyl methyl ether, perfluorobutyl ethyl ether, and octafluorocyclopentene.

  The additive is not particularly limited in its type, and examples thereof include surfactants, stabilizers, antioxidants, ultraviolet absorbers and antifoaming agents, and are used alone or in combination of two or more. be able to. The proportion of the additive in the metal impurity removing agent for CMP process is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 1% by weight or less.

  As the surfactant, known anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants can be used. Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. Examples of the cationic surfactant include salts of amines with various acids and quaternary ammonium salts. Examples of the nonionic surfactant include polyoxyethylene ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, and fatty acid partial ester of polyhydric alcohol. Examples of amphoteric surfactants include betaines, amino organic acids, and amine salts of fatty acids. In addition, an activator containing a fluorine atom in the molecule of these compounds is also preferably used.

  Stabilizers include aliphatic nitro compounds such as nitromethane and nitroethane; acetylene alcohols such as 3-methyl-1-butyn-3-ol and 3-methyl-1-pentyn-3-ol; glycidol, methyl glycidyl ether And epoxides such as ethyl glycidyl ether; ethers such as dimethoxymethane, 1,3-dimethoxyethane and 1,4-dioxane; unsaturated hydrocarbons such as hexene, heptene, cyclopentene and cyclohexene; allyl alcohol and 1-butene Unsaturated alcohols such as -3-ol; acrylic acid esters such as methyl acrylate and ethyl acrylate; and the like.

  Antioxidants include 1-oxy-3-methyl-4-isopropylbenzene, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butylphenol, butylhydroxyanisole, 2,6-di- -T-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, triethylene glycol-bis [3- (3 -T-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] and octadecyl-3 Phenolic antioxidants such as-(3,5-di-t-butyl-4-hydroxyphenyl) propionate; diphenyl-p-phenyle Amine-based antioxidants such as diamine, 4-amino-p-diphenylamine and p, p′-dioctyldiphenylamine; phenylisodecyl phosphite, diphenyldiisooctyl phosphite, diphenyldiisodecyl phosphite, triphenyl phosphite, tris Phosphorous antioxidants such as nonylphenyl phosphite and bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite; dilauryl-3,3′-thiodipropionic acid ester, ditridecyl-3,3 And sulfur-based antioxidants such as' -thiodipropionic acid ester, dimyristyl-3,3'-thiodipropionic acid ester and distearyl-3,3'-thiodipropionic acid ester.

  Examples of ultraviolet absorbers include 4-hydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4′-chlorobenzophenone, 2, 2 ′. -Hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,4-dihydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4 ' -Benzophenones such as dimethoxybenzophenone and 4-dodecyl-2-hydroxybenzophenone; phenyl salicylates such as phenyl salicylate, 4-t-butylphenyl salicylate, 4-octylphenyl salicylate and bisphenol A-di-salicylate 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α′-didimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3 , 5-Di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2′-hydroxy-4′-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) Benzotriazoles such as benzotriazole and 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole;

  Examples of the antifoaming agent include self-emulsifying silicone, silicon, fatty acid, higher alcohol, polypropylene glycol polyethylene glycol, and fluorine-based surfactant.

  As a suitable specific example of the metal impurity contamination to be cleaned by the metal impurity removing agent for CMP process of the present invention, a silicon wafer or glass substrate after the CMP process in the manufacturing process of semiconductor elements such as IC and LSI and liquid crystal panel elements Or metal impurity contamination on the surface of the substrate on which the metal or / and dielectric is laminated, or on the surface of the substrate when the metal or / and dielectric laminate is processed. Semiconductor elements such as IC and LSI It is particularly preferably used for metal impurity contamination on the surface of the semiconductor substrate after the CMP process in the manufacturing process.

  The method for removing metal impurities of the present invention comprises a step of bringing the metal impurity removing agent for CMP process of the present invention into contact with the substrate surface and removing metal impurities (hereinafter abbreviated as “metal impurity removing step”). And

  A board | substrate means the board which formed the conductive wiring pattern on the insulator. Examples of the substrate include a silicon wafer and a glass substrate in the manufacturing process of semiconductor elements such as IC and LSI, and liquid crystal panel elements, and a metal or / and dielectric laminate of the substrate.

The method for contacting the substrate with the metal impurity removing agent for CMP process of the present invention is not particularly limited. For example, immersion cleaning, stirring cleaning, rocking cleaning, ultrasonic cleaning, jet cleaning, nozzle cleaning, shower cleaning, barrel rotation cleaning, brush Any conventionally known contact means such as cleaning and air bubbling cleaning can be applied.
In addition, 0-50 degreeC is preferable from a viewpoint of the metal impurity removal performance and the simplification of an installation, and the temperature at the time of a metal impurity removal process is especially preferable 10-35 degreeC.

In the metal impurity removal method of the present invention, it is preferable that after the metal impurity removal step, the hydrofluorocarbon is brought into contact with the substrate surface and rinsed, and then the hydrofluorocarbon is evaporated to dry the object to be cleaned. As the rinsing method, the same methods as various metal impurity removal methods in the metal impurity removal step can be used.
In addition, the thing similar to what was used for the said metal impurity removal agent for CMP processes is used for hydrofluorocarbon.

The temperature of the hydrofluorocarbon during rinsing is preferably 0 to 50 ° C., particularly preferably 10 to 35 ° C., from the viewpoint of metal impurity removal performance and facility simplification.
Examples of the drying method include high-speed spin drying, steam drying, reduced pressure drying, and vacuum heating drying.

  After the metal impurity removal step, the hydrofluorocarbon is brought into contact with the substrate surface and rinsed, and then the semiconductor substrate is dried by evaporating the hydrofluorocarbon. Rinsing with water is not necessary, and it is effective for improving problems caused by using water such as watermarks.

The method for removing metal impurities of the present invention is used for removing metal impurities from a substrate after CMP.
As a CMP method for a substrate, for example, an abrasive (slurry) obtained by mixing an abrasive such as alumina particles or silica particles together with other optional components together with a necessary medium, etc., is pressure-bonded with a buff. Then, by rotating, the surface of the substrate is generally polished to flatten the film. By this CMP treatment, a large amount of metal impurities such as metal impurities contained in the abrasive component; metal ions in the case where metal wiring is formed on the semiconductor substrate surface are attached to the substrate surface. The metal impurity removing agent for CMP process of the present invention is suitably used for removing these metal impurities.

  The present invention will be specifically described with reference to the following examples, but the contents of the present invention are not limited thereto.

[Create evaluation board]
In order to confirm the removal performance of the metal component remaining on the surface of the interlayer insulating film after the chemical mechanical polishing (CMP) of copper in the copper wiring formation process by the dual damascene method, a simulated substrate was prepared as follows.
A clean silicon substrate having a diameter of 6 inches was placed in a spin coater, and a 500 ppm concentration Cu (NO ₃ ) ₂ solution (Cu1000 manufactured by Wako Pure Chemical Industries, Ltd. was diluted twice with pure water) to silicon. 1.5 ml was dropped onto the mirror surface of the substrate. After the dropping, the number of rotations was quickly increased to 1000 rpm so that the droplets were not dried, and spin drying was performed while discharging excess droplets for coating on the substrate surface. When the number of Cu particles on the substrate surface in this state was measured with a total reflection fluorescent X-ray apparatus TREX610 (manufactured by Technos), the amount of Cu contamination on the substrate was 1 × 10 ¹³ atoms / cm ² .
The initial value of the clean silicon substrate used at this time was 1 × 10 ¹⁰ atoms / cm ² .

[Example 1]
The Cu-contaminated substrate prepared above was immersed in a metal impurity removing agent (liquid) for CMP process having the composition shown in Table 1 held at 25 ° C. for 3 minutes, and then nitrogen gas was sprayed onto the substrate surface to dry it. . This was measured by the same method as that for the contaminated substrate. The amount of Cu contamination on the substrate was 8 × 10 ¹¹ atoms / cm ² .
The results are shown in Table 1.

[Example 2]
When the Cu-contaminated substrate was washed in the same manner as in Example 1 except that the metal impurity removing agent for the CMP process was used (liquid) having the composition shown in Table 1, the amount of Cu contamination on the substrate was 5 × 10 ^{It was 11} atoms / cm ² .
The results are shown in Table 1.

[Comparative Example 1]
Removal of metal impurities from a Cu-contaminated substrate in the same manner as in Example 1 except that only 1,1,2,2,3,3,4-heptafluorocyclopentane (liquid) was used as a metal impurity removing agent for the CMP process. As a result, Cu on the substrate surface could not be removed at all, and the amount of Cu contamination on the substrate remained at 1 × 10 ¹³ atoms / cm ² .
The results are shown in Table 1.

[Comparative Example 2]
Further, when the metal impurities were removed from the Cu-contaminated substrate in the same manner as in Example 1 except that only propylene glycol monomethyl ether was used as the metal impurity removing agent for the CMP process, the amount of Cu contamination on the substrate was 1 × 10. ^{It was 12} atoms / cm ² .
The results are shown in Table 1.

[Comparative Example 3]
Further, when the metal impurity was removed from the Cu-contaminated substrate in the same manner as in the example except that only ethanol was used as the metal impurity removing agent for the CMP process, the amount of Cu contamination on the substrate was 6 × 10 ¹¹ atoms / cm. ² .
The results are shown in Table 1.

  From Table 1, it can be seen that the metal impurity removing agent for CMP process of the present invention is excellent in removing metal impurities on the substrate surface.

Claims (3)

  A metal impurity removing agent for CMP process, comprising a hydrofluorocarbon and an oxygen-containing organic compound. The metal impurity removing agent for CMP process according to claim 1, wherein the hydrofluorocarbon is represented by the following formula (1).

(R ₁ represents a carbon chain represented by —CHF—CH ₂ —. Rf ₁ and Rf ₂ are each a perfluoroalkyl group, and Rf ₁ and Rf ₂ are bonded to each other to form a ring. (It may be formed.)   A metal impurity removing method comprising the step of bringing the metal impurity removing agent for CMP process according to claim 1 into contact with a substrate surface after CMP treatment to remove the metal impurities.