Polishing composition and polishing method

Abstract

To provide a polishing composition capable of improving polishing rate, and a polishing method using the polishing composition.SOLUTION: A polishing composition according to the present invention comprises water, alumina abrasive grains, and a nonionic surfactant, the polishing composition having a surface tension of 50 mN / m or less. A polishing method according to the present invention comprises a step of polishing an object to be polished with the polishing composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polishing composition and a polishing method using the polishing composition. [Background technology]

[0002] Conventionally, chemical mechanical polishing (hereinafter referred to as CMP) is performed in the manufacture of semiconductor devices. For example, in the manufacture of printed wiring boards, CMP is performed to polish a resin substrate on which metal wiring such as copper is formed. Furthermore, in the CMP of semiconductor devices having multilayer wiring such as LSIs, an interlayer insulating film made of resin such as polyimide resin is polished together with the metal wiring.

[0003] Generally, a polishing composition containing water and abrasive grains is used in a CMP process. For example, Patent Document 1 describes a polishing composition containing alumina abrasive grains and an anionic surfactant such as alkylbenzene sulfonate. Patent Document 1 also shows that the combination of alumina abrasive grains and anionic surfactant improves the polishing rate for resin films. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 176558 Summary of the Invention [Problem to be solved by the invention]

[0005] With the future development of high-integration technology, semiconductor devices with more advanced multi-layer wiring are expected to be put into practical use, and this will require further improvements in the polishing speed of CMP.

[0006] In view of the above circumstances, an object of the present invention is to provide a polishing composition capable of improving the removal rate, and a polishing method using the polishing composition. [Means for solving the problem]

[0007] The polishing composition according to one aspect of the present invention comprises: The method comprises: water, alumina abrasive grains, and a nonionic surfactant; The surface tension is 50 mN / m or less.

[0008] It is believed that the nonionic surfactant in such a polishing composition makes the surface tension of the composition 50 mN / m or less, which facilitates the flow of the alumina abrasive grains, thereby improving the polishing rate.

[0009] The polishing composition according to one aspect of the present invention comprises: The nonionic surfactant has a surface tension of 50 mN / m or less in a 0.5% by mass aqueous solution.

[0010] The polishing composition according to one aspect of the present invention comprises: The nonionic surfactant is at least one selected from the group consisting of polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, and alkylene oxide adducts of acetylene glycol.

[0011] In a polishing composition according to one embodiment of the present invention, the content of the nonionic surfactant is 0.2 mass % or more.

[0012] A polishing composition according to one embodiment of the present invention does not contain an anionic surfactant, a cationic surfactant, or an amphoteric surfactant.

[0013] The polishing composition according to one embodiment of the present invention further comprises a complexing agent.

[0014] The polishing composition according to one embodiment of the present invention has a pH of 2 or more and less than 9.

[0015] The polishing method according to the present invention comprises the steps of: A method for polishing a resin film using any one of the polishing compositions described above, When the zeta potential of the resin film is negative, the zeta potential of the alumina abrasive grains is set to be positive; When the zeta potential of the resin film is positive, the zeta potential of the alumina abrasive grains is negative. [Effects of the Invention]

[0016] As described above, the present invention can provide a polishing composition capable of improving the removal rate, and a polishing method using the polishing composition. [Brief explanation of the drawings]

[0017] [Figure 1] 1 shows cross sections in the thickness direction of polishing pads that have absorbed the polishing compositions of Example 1 and Comparative Examples 1 and 2, as analyzed by EDX. DETAILED DESCRIPTION OF THE INVENTION

[0018] The polishing composition according to an embodiment of the present invention will be described below.

[0019] The polishing composition of this embodiment contains water, alumina abrasive grains, and a nonionic surfactant. The polishing composition is a polishing slurry in which the alumina abrasive grains are dispersed in water. The polishing composition may also contain other additives.

[0020] The water is preferably purified, such as distilled water or ion-exchanged water, and the content of the water is preferably 90% by mass or more, more preferably 95% by mass or more, based on the total mass of the polishing composition.

[0021] The alumina abrasive grains may be particles made of α-alumina, γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, χ-alumina, etc. The alumina abrasive grains may be made of only one type of alumina particles, or two or more types of alumina particles.

[0022] The median diameter of the alumina abrasive grains is typically 0.05 to 1 μm. The median diameter is preferably 0.1 to 0.5 μm. The median diameter can be measured as follows: A laser diffraction / scattering particle distribution analyzer LA-920 (manufactured by Horiba, Ltd.) is used to determine the volumetric particle size distribution by laser diffraction / scattering. The particle diameter at which the cumulative volume frequency of the obtained volumetric particle size distribution is 50% is defined as the median diameter of the alumina abrasive grains.

[0023] The content of the alumina abrasive grains is preferably 0.5% by mass or more, more preferably 1% by mass or more, based on the total mass of the polishing composition, and may be 5% by mass or less, or even 3% by mass or less.

[0024] The nonionic surfactant is preferably one that causes the surface tension of a 0.5% by mass aqueous solution (the mass ratio of the nonionic surfactant to the water is 0.5:99.5) to be 50 mN / m or less. By including such a nonionic surfactant, the surface tension of the polishing composition is 50 mN / m or less. The surface tensions of the 0.5% by mass aqueous solution of the nonionic surfactant and the polishing composition can be measured by the hanging drop method using a contact angle meter (DM500, manufactured by Kyowa Interface Science Co., Ltd.). The measurement conditions are as follows: (Surface tension measurement conditions) Needle: 18G (Teflon coated) Sample density: 1.000g / cm 3 Temperature: 25℃ Number of repetitions: 10 times (the average value of the 10 times is used as the measurement value) Analysis: Young-Laplace method Image Processing: Image Mode = Frame

[0025] The nonionic surfactant may be an ether-type nonionic surfactant, which may be any one of an ethylene oxide (EO) and / or propylene oxide (PO) adduct of an alkyl alcohol, an EO and / or PO adduct of an aryl alcohol, and an EO and / or PO adduct of an acetylene glycol.

[0026] The nonionic surfactant may be a polyoxyalkylene alkyl ether. The polyoxyalkylene alkyl ether is preferably an EO adduct of an alkyl alcohol, more preferably an EO and PO adduct of an alkyl alcohol. The number of moles of EO added to the polyoxyalkylene alkyl ether is preferably 5 to 30, more preferably 5 to 20. This allows the polyoxyalkylene alkyl ether to be sufficiently dissolved in the water, and the surface tension of the polishing composition exhibits an effective value of 50 mN / m or less, thereby imparting fluidity to the alumina abrasive grains that can improve the polishing rate. The number of moles of PO added to the polyoxyalkylene alkyl ether is preferably smaller than the number of moles of EO added, for example, 1 to 10, preferably 1 to 5.

[0027] The alkyl group derived from the alkyl alcohol of the polyoxyalkylene alkyl ether is preferably an alkyl group having from 8 to 18 carbon atoms, more preferably from 8 to 16 carbon atoms, even more preferably from 8 to 14 carbon atoms, and even more preferably from 8 to 10 carbon atoms. The alkyl group is preferably linear, but may have a branched chain. Examples of the polyoxyalkylene alkyl ether include polyoxyethylene dodecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene myristyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene decyltetradecyl ether, and polyoxyethylene polyoxypropylene lauryl ether.

[0028] The nonionic surfactant may be a polyoxyalkylene aryl ether. The polyoxyalkylene aryl ether is preferably an EO adduct of an aryl alcohol. The number of moles of EO added to the polyoxyalkylene aryl ether is preferably 5 to 30, more preferably 5 to 20. This can impart fluidity to the alumina abrasive grains that can improve the polishing rate.

[0029] The aryl group of the polyoxyalkylene aryl ether may contain one to four benzene rings. The aryl group may contain a structure in which two benzene rings are connected via a methylene group. Examples of the polyoxyalkylene aryl ether include polyoxyethylene styryl phenyl ether, polyoxyethylene polystyryl phenyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene cumyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene benzyl phenyl ether, polyoxyethylene tribenzyl phenyl ether, polyoxyethylene naphthyl ether, and polyoxyethylene phenyl ether.

[0030] The nonionic surfactant may be an EO adduct of acetylene glycol. The number of moles of EO added in the EO adduct of acetylene glycol is preferably 5 to 30, and from the viewpoint of solubility in water, more preferably 10 to 30. This provides the alumina abrasive grains with fluidity that can improve the polishing rate.

[0031] Examples of the acetylene glycol include 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6-diol, 4,7-dimethyl-5-decyne-4,7-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, 7-10-dimethyl-8-hexadecyne-7,10-diol, and 3-methyl-1-nonyne-3-ol.

[0032] The lower limit of the content of the nonionic surfactant is preferably 0.1 mass % or more, more preferably 0.2 mass % or more, based on the total mass of the polishing composition. This allows the polishing rate to be sufficiently improved. The upper limit of the content of the anionic surfactant is not particularly limited, but is usually 1 mass % or less.

[0033] The mass ratio of the alumina abrasive grains to the nonionic surfactant (mass of the alumina abrasive grains: mass of the nonionic surfactant) is preferably 1:0.1 or more, more preferably 1:0.2 or more, and even more preferably 1:0.25 or more.

[0034] The polishing composition may contain only one type of nonionic surfactant, or may contain two or more types. The polishing composition preferably does not contain anionic surfactants, cationic surfactants, and amphoteric surfactants in a content equal to or greater than the content of the nonionic surfactants. For example, the total content of the anionic surfactants, cationic surfactants, and amphoteric surfactants is preferably less than 0.1 mass%, more preferably 0.05 mass% or less, and even more preferably 0.01 mass% or less, based on the total mass of the polishing composition. The polishing composition preferably does not contain the anionic surfactants, the cationic surfactants, and the amphoteric surfactants.

[0035] The pH of the polishing composition is preferably 2 or more and less than 9, or more than 9 and less than 12, more preferably 2 or more and less than 8, or 9.5 or more and less than 12, and even more preferably 2 or more and less than 8.

[0036] Examples of the additives include pH adjusters, complexing agents, antifoaming agents, and biocides.

[0037] Examples of the pH adjuster include inorganic acids such as nitric acid, sulfuric acid, boric acid, carbonic acid, and phosphoric acid; inorganic alkali compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, and ammonia; carboxylic acids such as formic acid, acetic acid, oxalic acid, citric acid, malonic acid, tartaric acid, maleic acid, and malic acid; amino acids such as arginine; primary amines, secondary amines, tertiary amines, quaternary ammonium and hydroxides thereof; and amine compounds such as heterocyclic amines.

[0038] The complexing agent is preferably one capable of forming a copper complex. Examples of such complexing agents include ammonia; amines such as tri-n-butylamine, 2-ethylhexylamine, and triisobutylamine; polyethyleneamines such as ethylenediamine, triethylenetetramine, hexamethylenetetramine, and pentaethylenehexamine; alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, 2-(2-aminoethoxy)ethanol, and triisopropanolamine; amino acids such as glycine, alanine, arginine, glutamic acid, and aspartic acid; and carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, benzoic acid, phthalic acid, salicylic acid, tartaric acid, citric acid, gluconic acid, glyoxylic acid, and malic acid. The content of the complexing agent is preferably 0.1% by mass or more and 2% by mass or less based on the total mass of the polishing composition, which is thought to not inhibit the effect of the nonionic surfactant in improving the polishing rate.

[0039] The antifoaming agent is preferably a silicone-based antifoaming agent such as a silicone emulsion. The content of the antifoaming agent is preferably 0.05% by mass or more and 1% by mass or less based on the total mass of the polishing composition. Generally, the nonionic surfactant is known as a surfactant that does not easily cause foaming. In this embodiment, however, the antifoaming agent is preferably contained in order to suppress foaming caused by a polishing pad rotating at high speed, thereby improving workability and the quality of the polished object.

[0040] Examples of the biocide include antiseptics and antifungal agents. The content of the biocide may be 0.1 mass % or less, or 0.05 mass % or less, based on the total mass of the polishing composition.

[0041] Next, a polishing method using the polishing composition according to the embodiment will be described.

[0042] The object to be polished in the polishing method according to this embodiment may be, for example, a resin substrate on which metal wiring such as copper is formed in the CMP of a printed wiring board, or a resin film such as an interlayer insulating film in the CMP of a semiconductor device. That is, the polishing method according to this embodiment may comprise polishing the resin film. The object to be polished may include metal wiring embedded in the resin film. Examples of resins that form the resin film include polyimide resin, polybenzoxazole resin, epoxy resin, and benzocyclobutene resin. Examples of metals that form the wiring include copper and aluminum.

[0043] The polishing method can use a polishing pad. In the polishing method, the polishing pad may be pressed against the workpiece and rotated relative to each other while the polishing composition is supplied to the workpiece. The alumina particles contained in the polishing composition are easily flowable within the polishing pad, increasing the chance of contact with the workpiece, thereby improving the polishing rate.

[0044] Examples of the polishing pad include a polishing pad made of a nonwoven fabric such as polyester impregnated with a thermosetting resin such as a thermosetting polyurethane resin, and a polishing pad made of a foam such as a urethane resin.

[0045] In the polishing method, it is preferable to make the zeta potential of the alumina abrasive grains positive when the zeta potential of the resin film is negative, and to make the zeta potential of the alumina abrasive grains negative when the zeta potential of the resin film is positive. That is, by making the zeta potentials of the resin film and the alumina abrasive grains oppositely positive and negative, the resin film and the alumina abrasive grains are thought to attract each other, thereby improving the polishing rate. For example, since the resin film formed from the polyimide resin exhibits a negative zeta potential in any pH range, in this case, the pH of the polishing composition is adjusted to less than 9, preferably from 2 to 8, using the pH adjuster, to make the zeta potential of the alumina abrasive grains positive. Such polishing conditions can further improve the polishing rate.

[0046] Although the embodiments have been shown as examples, the polishing composition and polishing method according to the present invention are not limited to the configurations of the above-mentioned embodiments. Furthermore, the polishing composition and polishing method according to the present invention are not limited by the above-mentioned effects. The polishing composition and polishing method according to the present invention can be modified in various ways without departing from the spirit of the present invention.

[0047] For example, the polishing composition of the present invention may contain, as additives other than those mentioned above, an oxidizing agent such as hydrogen peroxide solution, a water-soluble polymer, and a metal corrosion inhibitor.

[0048] Examples of the water-soluble polymer that can be used include celluloses such as hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, cellulose acetate, and methyl cellulose; vinyl polymers such as polyvinyl alcohol (PVA), modified PVA, and polyvinylpyrrolidone; glycosides such as alkylene oxide derivatives of methyl glucoside; and polyhydric alcohols.

[0049] Examples of the metal corrosion inhibitor include nitrogen-containing heterocyclic compounds such as pyrrole compounds such as 1H-pyrazole, imidazole compounds such as imidazole and 1-methylimidazole, triazole compounds such as 1,2,3-triazole, tetrazole compounds such as 1H-tetrazole, indole compounds such as 1H-indole, indazole compounds such as 1H-indazole, pyridine compounds, pyrazine compounds, pyridazine compounds, pyrindine compounds, indolizine compounds, isoindole compounds, purine compounds, quinolizine compounds, quinoline compounds, isoquinoline compounds, naphthyridine compounds, phthalazine compounds, quinoxaline compounds, quinazoline compounds, cinnoline compounds, buteridine compounds, thiazole compounds, isothiazole compounds, oxazole compounds, isoxazole compounds, and furazan compounds.

[0050] The present disclosure includes the following. (1) The method comprises: water, alumina abrasive grains, and a nonionic surfactant; A polishing composition having a surface tension of 50 mN / m or less. (2) The polishing composition according to (1) above, wherein the nonionic surfactant has a surface tension of 50 mN / m or less in a 0.5 mass % aqueous solution. (3) The polishing composition according to (1) or (2) above, wherein the nonionic surfactant is one or more selected from the group consisting of polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, and alkylene oxide adducts of acetylene glycol. (4) The polishing composition according to any one of (1) to (3) above, wherein the content of the nonionic surfactant is 0.2 mass % or more. (5) The polishing composition according to any one of (1) to (4) above, which does not contain an anionic surfactant, a cationic surfactant, or an amphoteric surfactant. (6) The polishing composition according to any one of (1) to (5) above, further comprising a complexing agent. (7) The polishing composition according to any one of (1) to (6) above, which has a pH of 2 or more and less than 9. (8) A method for polishing a resin film on a substrate using the polishing composition according to any one of (1) to (7) above, When the zeta potential of the resin film is negative, the zeta potential of the alumina abrasive grains is set to be positive; When the zeta potential of the resin film is positive, the zeta potential of the alumina abrasive grains is made negative. [Example]

[0051] The present invention will be further explained below with reference to examples, but the present invention is not limited thereto.

[0052] [Raw materials used] (nonionic surfactant) Polyoxyalkylene alkyl ether (EO and PO adduct of 1-nonanol, EO adduct mole count: 8.3 moles, PO adduct mole count: 3.0 moles, average molecular weight: 680 g / mol) Polyoxyethylene polystyrylphenyl ether Polyoxyethylene cumyl phenyl ether Acetylene glycol (2,4,7,9-tetramethyl-5-decyne-4,7-diol) EO adduct (EO adduct moles: 10 moles) Acetylene glycol ethylene oxide (2,4,7,9-tetramethyl-5-decyne-4,7-diol) EO adduct (EO adduct moles: 20 moles) Acetylene glycol (2,4,7,9-tetramethyl-5-decyne-4,7-diol) EO adduct (EO adduct moles: 30 moles) (anionic surfactants) Dodecylbenzenesulfonic acid triethanolamine salt

[0053] Polishing compositions were prepared according to the formulations in Table 1, and the removal rate was evaluated under the following polishing condition 1. The surface tension of a 0.5 mass % aqueous solution of the surfactant used and the surface tension of the prepared polishing composition were measured using the above-mentioned measurement method. The results are shown in Table 1. Furthermore, as shown in FIG. 1, EDX analysis was performed on the cross section in the thickness direction of the polishing pad (after 20 minutes of polishing) that had absorbed each polishing composition in Table 1.

[0054] (Polishing condition 1) Polishing device: SH24 (SpeedFam) Polishing pad: Suba400 (Nitta-DuPont, a polishing pad made of polyester nonwoven fabric impregnated with thermosetting polyurethane resin) Polishing load: 3 psi Table rotation speed: 90 rpm Head rotation speed: 89 rpm Slurry flow rate: 150 mL / min Polished object: Wafer with polyimide resin film (Hitachi Chemical Co., Ltd. PI2727) Board size: 200mm

[0055] [Table 1]

[0056] As shown in Figure 1, in Example 1, which contains a nonionic surfactant (polyoxyalkylene alkyl ether), EDX analysis confirmed that the alumina abrasive grains were dispersed throughout the thickness of the polishing pad. That is, Example 1 is considered to have excellent fluidity of the alumina abrasive grains. This is considered to have contributed to the improved polishing rate in Example 1, as shown in Table 1.

[0057] On the other hand, the results in Table 1 show that although anionic surfactants can reduce the surface tension of the polishing composition to 50 mN / m or less, they cannot improve the polishing rate. This is thought to be because the anionic surfactants are adsorbed to the alumina abrasive grains and polishing pad, causing steric hindrance and electrostatic repulsion, which inhibit the alumina abrasive grains from penetrating into the polishing pad.

[0058] Next, the effects of additives such as complexing agents and antifoaming agents were evaluated using the formulations shown in Table 2 and the above-mentioned polishing condition 1. The results are shown in Table 2.

[0059] [Table 2]

[0060] The results in Table 2 show that the addition of complexing agents and antifoaming agents did not inhibit performance.

[0061] Next, the influence of the type of abrasive grain was evaluated using the formulation shown in Table 3 and the above-mentioned polishing condition 1. The results are shown in Table 3.

[0062] [Table 3]

[0063] The results in Table 3 show that the combination of alumina abrasive grains and a nonionic surfactant improved the polishing rate, while the combination of colloidal silica and a nonionic surfactant did not.

[0064] Next, the pH and content of the nonionic surfactant (polyoxyalkylene alkyl ether) were evaluated using the formulation shown in Table 4 and the following polishing condition 2. The results are shown in Table 4.

[0065] (Polishing condition 2) Polishing equipment: Ecomet3 (Buehler) Polishing pad: Suba400 (Nitta-DuPont, a polishing pad made of polyester nonwoven fabric impregnated with thermosetting polyurethane resin) Polishing load: 2.2psi Table rotation speed: 100 rpm Head rotation speed: 95 rpm Slurry flow rate: 10 mL / min Polished object: Wafer with polyimide resin film (Hitachi Chemical Co., Ltd. PI2727) Board size: 40mm x 40mm

[0066] [Table 4]

[0067] Next, other surfactants and additives showing a surface tension of 50 mN / m or less were evaluated using the formulations shown in Tables 5 and 6 and the above-mentioned polishing condition 2. The results are shown in Tables 5 and 6.

[0068] [Table 5]

[0069] [Table 6]

[0070] The results in Table 5 show that nonionic surfactants with a surface tension of 50 mN / m or less tend to improve the polishing rate.

[0071] On the other hand, the results in Table 6 show that even if the additive was nonionic, those with a surface tension exceeding 50 mN / m did not improve the polishing rate.

[0072] The results in Tables 1 to 6 show that the addition of a nonionic surfactant showing a surface tension of 50 mN / m or less improved the polishing rate in both the near-neutral pH range of 7 to 7.5 (Tables 1 and 2) and the alkaline pH range (Tables 3 to 6). That is, the results in Tables 1 to 6 show that the addition of the nonionic surfactant improved the polishing rate in each pH range.

Claims

1. The method comprises: water, alumina abrasive grains, and a nonionic surfactant; A polishing composition having a surface tension of 50 mN / m or less.

2. 2. The polishing composition according to claim 1, wherein the nonionic surfactant has a surface tension of 50 mN / m or less in a 0.5% by mass aqueous solution.

3. 3. The polishing composition according to claim 2, wherein the nonionic surfactant is at least one selected from the group consisting of polyoxyalkylene alkyl ethers, polyoxyalkylene aryl ethers, and alkylene oxide adducts of acetylene glycol.

4. 4. The polishing composition according to claim 3, wherein the content of the nonionic surfactant is 0.2 mass % or more.

5. The polishing composition according to claim 1 , which does not contain an anionic surfactant, a cationic surfactant, or an amphoteric surfactant.

6. The polishing composition of claim 1 , further comprising a complexing agent.

7. The polishing composition according to claim 1 , having a pH of 2 or more and less than 9.

8. A method for polishing a resin film on a substrate using the polishing composition according to any one of claims 1 to 4, When the zeta potential of the resin film is negative, the zeta potential of the alumina abrasive grains is set to be positive; When the zeta potential of the resin film is positive, the zeta potential of the alumina abrasive grains is made negative.

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