WO2018139492A1

WO2018139492A1 - Processing medium, processing composition, and processing method

Info

Publication number: WO2018139492A1
Application number: PCT/JP2018/002150
Authority: WO
Inventors: 慎也 ▲高▼梨; 圭佑 ▲会▼田; 桂 ▲高▼橋
Original assignee: パレス化学株式会社
Priority date: 2017-01-27
Filing date: 2018-01-24
Publication date: 2018-08-02
Also published as: CN110382655A; CN110382655B; KR20190112278A; JPWO2018139492A1; TW201833291A; JP6661175B2; TWI757413B

Abstract

Provided are a processing medium which combines rust-preventive performance with metal-contamination-preventing performance, a processing composition, and a processing method. The processing medium according to the present invention contains a C_2-7 polycarboxylic acid, an aromatic monocarboxylic acid, and a basic substance or contains these ingredients in a neutralized state.

Description

Processing medium, processing composition and processing method

The present invention relates to a processing medium, a processing composition, and a processing method.

When performing processing to cut a workpiece such as an ingot (ingot) into a wafer, processing to grind (grind) the cut surface of the workpiece, or further polish the cut surface of the workpiece to a mirror surface A working medium (working fluid, cutting fluid, coolant) is supplied to a contact portion between a tool (for example, a wire saw, a band saw, an inner peripheral blade, a lap surface plate, etc.) and a workpiece. The processing medium is used after being diluted with a solvent such as water, or further blended with abrasive grains and used as a processing composition (grinding liquid, polishing liquid, slurry). The processing medium includes a cooling action that cools the heat generated between the tool and the workpiece, a lubrication action that lubricates the tool and the work piece, and particles (chips, grinding debris, polishing generated during machining) There is a welding protection action that protects the welding between the scrap) and the tool or workpiece.

Particle-derived metal oxide particulate sludge generated by processing is likely to adhere (adhere, reattach) to the surface of the workpiece. When the sludge adheres to the surface of the workpiece, it leads to metal contamination of the workpiece. In addition, during processing, metal ions eluted into the processing medium due to contact with metal such as tools and pipes are likely to be adsorbed (or penetrated or diffused) on the surface of the workpiece. Metal ions are easy to move on the surface of the workpiece. Due to the movement of metal ions, problems such as malfunction of elements such as transistors formed on the workpiece (for example, wafer), leakage current (leakage current), etc. May occur. Therefore, various processing media and processing compositions have been proposed in order to suppress the adverse effects of sludge and metal ions on the workpiece.

For example, Patent Document 1 discloses a water-soluble cutting oil material containing a primary alkanolamine, a carboxylic acid, and a diamine as a component that suppresses a decrease in rust prevention properties. Further, Patent Document 2 discloses a water-soluble metal anticorrosive agent comprising a tetrazole compound and a water-soluble salt thereof as having excellent rust prevention ability for various metals.

Further, Patent Document 3 discloses a polishing composition containing a chelating agent, an alkali compound, silicon dioxide and water as an effective suppression of contamination of the wafer by metal impurities. Further, Patent Document 4 discloses a polishing composition containing silica, a basic substance, aminopolyphosphonic acid, and water as an element that effectively prevents metal contamination such as nickel, chromium, iron, and copper. . Further, Patent Document 5 discloses a polishing composition containing silica, a basic substance, an amino acid derivative, a salt thereof, and water as one that can prevent metal contamination, particularly copper contamination. Further, Patent Document 6 discloses a polishing composition containing silica, a basic substance, a polyaminopolycarboxylic acid compound having a hydroxyl group, and water as those capable of preventing metal contamination, particularly copper contamination. Further, Patent Document 7 discloses a polishing composition containing silicon dioxide, an alkali compound, and a chelating agent having a phosphonic acid group as one that effectively suppresses contamination of the wafer by metal impurities. Further, Patent Document 8 discloses a polishing slurry containing monoclinic zirconium, a carboxylic acid, and a quaternary alkylammonium hydroxide as one that can effectively prevent copper contamination.

Japanese Unexamined Patent Publication No. 64-43598 JP 7-145491 A International Publication No. 2004/042812 Pamphlet JP 2005-347737 A International Publication No. 2006/046641 Pamphlet International Publication No. 2006/126432 Pamphlet JP 2014-82509 A Japanese Patent No. 5002175

However, there has been no conventional processing composition that has both rust prevention and metal contamination prevention.

The main object of the present invention is to provide a processing medium, a processing composition, and a processing method having both rust prevention performance and metal contamination prevention performance.

The processing medium according to the present invention contains a polyvalent carboxylic acid having 2 to 7 carbon atoms, an aromatic monocarboxylic acid, and a basic substance in a neutralized state.

The processing composition according to the present invention includes the processing medium and abrasive grains.

The processing method according to the present invention processes the workpiece by supplying the processing medium or the processing composition to a contact portion between a tool and the workpiece.

According to the present invention, it is possible to provide a processing medium, a processing composition, and a processing method that have both rust prevention performance and metal contamination prevention performance.

It is a photograph which shows the determination method of metal contamination evaluation of a silicon wafer.

Hereinafter, embodiments will be described. Note that, in the present application, where reference numerals are attached to the drawings, these are only for the purpose of helping understanding, and are not intended to be limited to the illustrated embodiments. The following embodiments are merely examples and do not limit the present invention.

The processing medium according to the embodiment includes processing for cutting a workpiece such as silicon, silicon carbide, sapphire, and gallium nitride ingots, processing for polishing a cutting surface of a workpiece such as a wafer, and polishing the cutting surface to a mirror surface. When performing processing such as machining, tools (for example, wire saws, band saws, inner peripheral blades, lapping surface plates (for example, single-side surface plates, double-side surface plates, cast iron surface plates, copper surface plates, etc.)) Medium (working fluid, cutting fluid, coolant, etc.) supplied to the contact portion with the workpiece. The processing medium can be used after being diluted with water. The processing medium may further contain abrasive grains (for example, diamond, zirconia, alumina, silicon carbide, cubic boron nitride, etc.) and a processing composition (for example, grinding liquid, grinding composition, polishing liquid, polishing composition) , Slurry, suspension, etc.). The processing medium is used in processing apparatuses such as a cutting apparatus (slicing apparatus, cutter machine), a grinding apparatus (lapping apparatus), and a polishing apparatus (polishing apparatus). In the processing apparatus, copper is often used for piping from the tank of the processing medium to the supply unit.

The processing medium preferably has a copper ion concentration in the processing medium of 70 ppm or less, more preferably 60 ppm or less, and particularly preferably 50 ppm or less when copper is immersed in the processing medium. If it exceeds 70 ppm, malfunctions of elements such as transistors formed on the workpiece, leakage current, etc. are likely to occur.

The processing medium contains a polyvalent carboxylic acid, an aromatic monocarboxylic acid, a basic substance, and water in a neutralized or neutralized state. Here, the contained or neutralized state means that the acid and base are not neutralized, the acid and base are in an ionic state, or the acid and base are neutralized or in any state. Say.

The polyvalent carboxylic acid is a polyvalent carboxylic acid having 2 to 7 carbon atoms. The polyvalent carboxylic acid mainly acts to suppress metal contamination of the workpiece. Examples of the polyvalent carboxylic acid include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, fumaric acid, glutaric acid, adipic acid, and pimelic acid; tricarboxylic acids such as annicotic acid; hydroxy acids such as malic acid and citric acid; Oxaloacetic acid or the like can be used. The carbon number of the polyvalent carboxylic acid is preferably 2 or more and 6 or less. If the carbon number is greater than 7, it becomes impossible to suppress metal contamination of the workpiece. Among the above polyvalent carboxylic acids, oxalic acid is excellent in the effect of preventing elution of iron generally used for tools. Moreover, citric acid is excellent in the effect which prevents elution of copper.

An aromatic monocarboxylic acid is a compound having at least one aromatic ring and one carboxyl group. As the aromatic monocarboxylic acid, for example, p-tert-butylbenzoic acid, о-tert-butylbenzoic acid, m-tert-butylbenzoic acid, nitrobenzoic acid, phenylacetic acid, naphthalenecarboxylic acid and the like can be used. Among them, p-tert-butylbenzoic acid is preferable because it has an action of suppressing oxidation of a metal material mainly used in tools (ensuring rust prevention).

Here, it is known to use p-tert-butylbenzoic acid and a base to prevent metal corrosion (see, for example, [0002] of Patent Document 2), but a molecular weight of 2 to 7 carbon atoms. The use of a combination of a low-valent polycarboxylic acid and p-tert-butylbenzoic acid is not disclosed or suggested.

It should be noted that the point to be noted in the processing of a workpiece is that copper used for tools, piping of a processing apparatus, etc. is ionized and adsorbed (or penetrated or diffused) to the workpiece to be contaminated. It is well known that benzotriazoles are used to prevent copper corrosion and elution (see, for example, [0002] of Patent Document 2). Since it is sometimes impossible to suppress metal contamination of the workpiece with respect to other metals, it is preferable to keep the blending amount of benzotriazole in a very small amount, and it is more preferable not to use it.

The total blending amount of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is preferably 0.05 wt% or more and 15 wt% or less, more preferably 0.1 wt% or more and 4 wt% or less in the processing medium, More preferably, it is 0.2 wt% or more and 2 wt% or less. If the concentration is lower than 0.05 wt%, it is difficult to suppress metal contamination of the workpiece. On the other hand, if the concentration is higher than 15 wt%, more base is required to neutralize this. Is easier to elute.

The blending ratio of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is preferably 1: 4 or more and less than 2: 1, more preferably 1: 1.8 or more and 1.8: 1 or less, further preferably Is 1: 1.5 or more and 1.5: 1 or less. When the ratio is less than 1: 4, the copper ion elution amount increases. On the other hand, when the ratio is 2: 1 or more, the copper ion elution amount increases.

The basic substance is at least one of a sodium compound, a potassium compound, an ammonium compound, and an amine compound. The basic substance preferably contains a sodium compound or potassium compound and an amine compound, and more preferably contains a plurality of types of amine compounds. As the basic substance, a compound whose aqueous solution is basic (alkaline; greater than pH 7) can be used, for example, sodium compounds such as sodium hydroxide and sodium carbonate; potassium compounds such as potassium hydroxide and potassium carbonate; Ammonium compounds such as tetramethylammonium hydroxide and ammonium hydroxide; methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, monoethanolamine, N-ethanolamine, diethanolamine, triethylamine, triethanolamine, monoisopropanolamine, diisopropylethylamine, Diisopropanolamine, diethylenetriamine, triethylenetetramine, poly (propylene glycol) diamine, trimethylolpropane poly (oxy) (Propylene) triamine, ethylenediamine, tetramethylethylenediamine, 2-amino-2-methylpropanol, laurylaminopropylamine, ethylaminoethylamine, oleylaminopropylamine, diethylaminobutylamine, ethylaminohexylamine, cyclohexylaminopropylamine, hexamethylenediamine, Spermidine, aniline, phenethylamine, toluidine, pyrrolidine, piperidine, pyridazine, pyrimidine, pyrazine, oxazole, thiazole, N, N-dimethyl-4-aminopyridine, etheramine, anhydrous piperazine, piperazine hexahydrate, 1-piperazine, N -Amine compounds such as methylpiperazine can be used.

Since the processing medium according to the present invention contains a basic substance, the aromatic monocarboxylic acid becomes soluble in water, so that a uniform and stable solution can be obtained. The blending amount of the basic substance in the processing medium is preferably 0.1 wt% or more and 20 wt% or less, more preferably 0.2 wt% or more and 10 wt% or less, and further preferably 0.5 wt% or more and 5 wt% or less. If the concentration is lower than 0.1 wt%, the metal contamination of the workpiece will be adversely affected. If the basic substance is insufficient and the pH is 7 or less, the rust prevention property is lost. On the other hand, when the concentration is higher than 20 wt%, copper ions are likely to be eluted. The basic substance is preferably added in an amount that can neutralize both the polyvalent carboxylic acid and the aromatic monocarboxylic acid, and is preferably blended so that the pH of the processing medium is higher than 7, more preferably 8 and 12. .5 or less, more preferably 8.5 or more and 10 or less. Considering the handling and cost of the processing medium, the pH is preferably 12.5 or less.

Water is a dilute medium of polyvalent carboxylic acid, aromatic monocarboxylic acid and basic substance that are the concentrate components. The amount of water is not particularly limited as long as the stock solution can be diluted to an arbitrary concentration with water. However, in consideration of handling and cost, it is preferably 50 wt% or more and 99.7 wt% or less, more preferably 80 wt%. The amount is 99.5 wt% or less, more preferably 90 wt% or more and 98 wt% or less.

In addition, surfactants, antifoaming agents, preservatives, fragrances, dyes, and the like can be added to the processing medium as necessary.

The surfactant can be blended in consideration of the dispersibility of the abrasive grains and the permeability of the liquid. As the surfactant, nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants and the like can be used. For example, ester type nonionic surfactants such as glyceryl laurate and glyceryl monostearate Surfactants, ether type nonionic surfactants such as polyalkylene glycol monobutyl ether and polyoxyethylene alkyl ether; ester ether type nonionic surfactants such as polyoxyethylene sorbitan fatty acid ester and polyoxyethylene hexitan fatty acid ester; Alkanolamide type nonionic surfactants such as lauric acid diethanolamide and oleic acid diethanolamide; alkyl glucoside type nonionic surfactants such as octylglucoside and decylglucoside; cetanol, stearylamide Higher alcohol type nonionic surfactants such as coal; quaternary ammonium salt type cationic surfactants such as tetramethylammonium chloride and tetramethylammonium hydroxide; alkylamine salts such as monomethylamine hydrochloride and dimethylamine hydrochloride Type cationic surfactants; pyridine ring type cationic surfactants such as butylpyridinium chloride and dodecylpyridinium chloride; carboxylic acid type anionic surfactants such as sodium octoate and sodium decanoate; sodium 1-hexanesulfonate; Sulfonic acid type anionic surfactants such as sodium 1-octane sulfonate; Sulfate type anionic surfactants such as sodium lauryl sulfate and sodium myristyl sulfate; Phosphate type anionic surfactants such as lauryl phosphate and sodium lauryl phosphate Surfactants; alkylbetaine-type amphoteric surfactants such as lauryldimethylaminoacetic acid betaine and stearyldimethylaminoacetic acid betaine; fatty acid amidepropylbetaine-type amphoteric surfactants such as cocamidopropyl betaine and cocamidopropylhydroxysultain; Alkylimidazole-type amphoteric surfactants such as 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine; amino acid-type amphoteric surfactants such as sodium lauroylglutamate and potassium lauroylglutamate; lauryldimethylamine N-oxide, An amine oxide type amphoteric surfactant such as oleyldimethylamine N-oxide can be used. The blending amount of the surfactant can be 0.01 wt% or more and 5 wt% or less with respect to 100 wt% of the processing medium, preferably 0.02 wt% or more and 3 wt% or less, more preferably 0.05 wt%. Above and below 1 wt%.

The antifoaming agent can be blended in consideration of overflow from the processing medium tank and handling during recycling. Examples of antifoaming agents include silicone oils, modified silicones, nonionic surfactants having an HLB (Hydrophilic-Lipophilic Balance) of 7 or more; organic polar compounds such as 2-ethylhexanol and diisooctyl ether; sorbitan esters, pluronics A low hydrophilic surfactant such as L-61; mineral oil to which a fatty acid metal salt is added can be used. The blending amount of the antifoaming agent can be 0.001 wt% or more and 1 wt% or less with respect to 100 wt% of the processing medium, preferably 0.002 wt% or more and 0.5 wt% or less. It is 005 wt% or more and 0.1 wt% or less.

As preservatives, for example, 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, p-hydroxybenzoates, phenoxyethanol and the like can be used.

As the fragrance, for example, natural fragrance such as mastic oil, parsley oil, anise oil, synthetic fragrance such as carvone, anethole, methyl salicylate, blended fragrance, and the like can be used.

Examples of the dye include direct dyes such as Atlas Red R, Azo Blue, and Azo Mauve AM, basic dyes such as Auramin G, Auramin II, and Bismarck Brown; basic Janus dyes such as Janus Blue G, Janus Green B, and Janus Blue R; Mordant dyes such as logwood, fstic, mudder and alizarin; vat dyes such as anthraquinone and indigoid can be used.

In addition, about the said polyhydric carboxylic acid, aromatic monocarboxylic acid, and a basic substance, the salt of the state in which the polyhydric carboxylic acid, aromatic monocarboxylic acid, and basic substance were neutralized instead of those mixtures is a raw material Can be used as

As a method for producing the processing medium, for example, a processing medium that becomes a neutralized salt aqueous solution can be obtained by dissolving a basic substance in water, adding a polyvalent carboxylic acid and an aromatic monocarboxylic acid, and stirring the mixture. . If necessary, surfactants, preservatives, antifoaming agents, fragrances, dyes and the like can be added to the processing medium, and water can be added to adjust the concentration. When obtaining a processing composition, abrasive grains can optionally be blended in the processing medium and stirred. In addition, the manufacturing method of a processing medium and a processing composition is not restricted above. The processing medium or processing composition thus obtained is poured into a tank of the processing apparatus, and the processing medium or processing composition is supplied to the contact portion between the tool of the processing apparatus and the workpiece, and the processing target is processed. Things will be processed.

According to this embodiment, adsorption (or penetration, diffusion) of metal ions dissolved in the processing medium by the polyvalent carboxylic acid can be prevented (suppressed), so that metal contamination of the workpiece can be prevented. It can be prevented (suppressed). Further, according to the present embodiment, the aromatic monocarboxylic acid can prevent (suppress) oxidation of the metal material used in the tool, and thus prevent (suppress) adhesion of sludge to the workpiece. be able to. Furthermore, according to this embodiment, the combination of polyvalent carboxylic acid, aromatic monocarboxylic acid, and basic substance can prevent (suppress) the ionization of copper used for tools, tools for processing devices, and the like. Therefore, copper contamination of the workpiece can be prevented (suppressed).

Next, working medium examples and comparative examples will be described.

[Preparation of sample]
First, processing media (samples) according to Example 1-24 and Comparative Example 1-11 were prepared with the compositional composition shown in Table 1 to Table 7. Here, a basic substance is dissolved in water, and a polyvalent carboxylic acid and p-tert-butylbenzoic acid as an aromatic monocarboxylic acid are added and stirred. If necessary, a surfactant, A processing medium was obtained by adding 3-benzotriazole and adjusting the concentration by adding water. Here, preservatives, antifoaming agents, fragrances, dyes and the like are not included.

The trade names and manufacturer names of the ingredients listed in Table 1 to Table 7 are as follows: Ingredients: Trade name, manufacturer name / oxalic acid: oxalic acid dihydrate, Hishie Chemical Co., Ltd.
-Malic acid: DL-Malic Acid, Tokyo Chemical Industry Co., Ltd.
・ Fumaric acid: Fumaric acid, Fuso Chemical Industry Co., Ltd.
Citric acid: Citric acid (crystal) H, Fuso Chemical Industry Co., Ltd.
Caprylic acid: LUNAC (registered trademark) 8-98, Kao Corporation
-Sebacic acid: Sebacic acid SR, Ito Oil Co., Ltd.
・ P-tert-Butylbenzoic acid: 4-tert-Butylbenzoic acid (PTBBA), Fuso Chemical Industry Co., Ltd.
-Sodium hydroxide: Caustic soda (solid type), Tsurumi Soda Co., Ltd.
Monoisopropanolamine: Monoisopropanolamine (MIPA), NANJING HBL ALKYLOL AMINES CO. , LTD.
・ Diisopropanolamine: Diisopropanolamine 85% GT grade, Dow Chemical Japan Co., Ltd.
Triethanolamine: TEA (triethanolamine) 99, Japan Chemtech Co., Ltd.
Trimethylolpropane poly (oxypropylene) triamine: JEFFAMINE (registered trademark) T-403, Huntsman Japan K.K.
Polyalkylene glycol monobutyl ether: Unilube (registered trademark) 50MB-5, NOF Corporation
• 1,2,3-benzotriazole: Sunlite 123. BTA, Sanwa Kasei Co., Ltd.
・ Water: Tap water (water whose copper ion solubility is below the measurement limit)

[Preparation of processing composition]
A processing composition (slurry) was obtained by adding 30 wt% of abrasive grains (alumina base wrapping material: FO # 1000, Fujimi Incorporated) to 100 wt% of the processing media according to the examples and comparative examples.

[Polishing method]
The processing composition according to the example and the comparative example was supplied to the contact portion between the cast iron surface plate (tool) and the silicon wafer (workpiece) to polish the silicon wafer. The polishing process conditions are as follows.

[Polishing conditions]
Polishing machine: Lab Tester GP1 (Malto Corporation)
Surface plate: Cast iron diameter 250mm
Surface plate groove shape: Lattice (grid 1 side 25mm x 25mm)
Surface plate rotation speed: 100 rpm
Surface pressure on the test piece: 0.6 g / mm ²
Test piece: Single crystal silicon wafer diameter 125mm
Processing composition supply: 1 L / min

[Rust prevention evaluation of cast iron surface plate]
Since the processing composition and the cast iron surface plate are always touched, the rust prevention of the cast iron surface plate was evaluated as follows, assuming that the silicon wafer was contaminated by the occurrence of rust on the cast iron surface plate. . A test piece of a cast iron surface plate (material: FC200) obtained by polishing a silicon wafer using the processing composition according to the example and the comparative example was left to stand at 30 ° C. for 10 minutes while being immersed in the processing composition. The presence or absence of rusting on the cast iron surface plate surface was evaluated visually. When the cast iron surface plate (area: 70 mm x 50 mm) is free of rust, ○ When 10 or fewer rust is generated, △ When 10 or more rust is generated × It was evaluated.

[Metal contamination assessment of silicon wafers]
The silicon wafer after polishing was visually observed, and a test was performed to determine whether metal contamination (dirt due to sludge) on the silicon wafer surface due to particles along the grooves of the cast iron surface plate occurred. When the silicon wafer 1 is free from metal contamination (see judgment in FIG. 1: see the photograph of ○), the metal contamination 2 is present, but the metal contamination 2 (discoloration) is wiped once with a tissue before drying. The case where it was able to be removed was evaluated as Δ, and the case where there was metal contamination 2 and the metal contamination could not be removed even if it was wiped once with a tissue before drying was evaluated as x (see the judgment of FIG. 1: x photograph).

[Evaluation of copper ion elution amount]
Use copper specimens assuming that copper ions are eluted from the copper or its alloy adhering to the polishing machine piping and silicon wafer before cutting the silicon wafer, and that the silicon wafer surface is contaminated by the eluted copper ions. The amount of elution of copper ions was measured. A copper plate (material: C1100P) for JIS K 2513 (petroleum product-copper plate corrosion test method) was used as a test piece (length: about 75 mm, width) on 50 g of the processing medium according to Examples and Comparative Examples (without abrasive grains). Half of about 12.5 mm, thickness 1.5-3.0 mm) was immersed and allowed to stand at 25 ° C. for 18 hours, then the processing medium was taken out and ICP (Inductively Coupled Plasma) The amount of elution of copper ions in the processing medium was measured with an apparatus. The details of the ICP device are as follows.

[ICP equipment]
Manufacturer: AMETEK (Materials ANALYSIS DIVISION)
Device name: SPECTRO ARCOS (registered trademark)
Model: FHM22
Type: MV130 (multi-view)
Measurement conditions: Stock solution measurement Measurement method: SOP (Side On Plasma) side direction (radial)

[PH measurement]
The pH was measured using a pH measuring device (manufactured by HORIBA, Ltd., “Glass electrode type hydrogen ion concentration meter pH METER F-11”, “pH electrode LAQUA (registered trademark) 6377”).

[Evaluation of combination of polycarboxylic acid and monocarboxylic acid]
In Comparative Example 1 containing no polyvalent carboxylic acid and containing p-tert-butylbenzoic acid, the presence of the actions of both polyvalent carboxylic acid and p-tert-butylbenzoic acid is lacking. There was no rust prevention of the board, and the metal contamination of the silicon wafer and the elution amount of copper ions could not be suppressed. However, in Comparative Example 3 which does not contain a polyvalent carboxylic acid and contains p-tert-butylbenzoic acid, the copper elution occurs even when both the polyvalent carboxylic acid and p-tert-butylbenzoic acid are not effective. Due to the action of 1,2,3-benzotriazole as an inhibitor, the cast iron surface plate has rust prevention and the amount of copper ion elution can be suppressed, but the metal contamination of the silicon wafer can be suppressed. could not. From this, it was found that 1,2,3-benzotriazole has the antirust property of the cast iron surface plate, but does not have the effect of suppressing the metal contamination of the silicon wafer.

In Comparative Example 2 containing citric acid (carbon number 6) as the polyvalent carboxylic acid and not containing p-tert-butylbenzoic acid, the action of both the polyvalent carboxylic acid and p-tert-butylbenzoic acid was confirmed. Since it does not exist, the cast iron surface plate has no rust prevention property, and the metal contamination of the silicon wafer and the elution amount of copper ions cannot be suppressed.

In Comparative Example 4 which does not contain a polyvalent carboxylic acid and contains p-tert-butylbenzoic acid, the cast iron surface plate had rust prevention due to the action of other monocarboxylic acid (caprylic acid). Further, since the presence of the actions of both polyvalent carboxylic acid and p-tert-butylbenzoic acid is lacking, the metal contamination of the silicon wafer and the elution amount of copper ions could not be suppressed.

In Comparative Example 5 containing sebacic acid (10 carbon atoms) as the polyvalent carboxylic acid and containing p-tert-butylbenzoic acid, the polyvalent carboxylic acid has too many carbon atoms and has 7 or less carbon atoms. The action based on the presence of both polyvalent carboxylic acid and p-tert-butylbenzoic acid is lost, the cast iron surface plate has no rust prevention, and the silicon wafer metal contamination and copper ion elution amount could not be suppressed. .

In Comparative Example 6 containing citric acid and sebacic acid (carbon number 6 and 10) as the polyvalent carboxylic acid and not containing p-tert-butylbenzoic acid, the cast iron platen Although it was rustproof, it lacked the action of both polyvalent carboxylic acid and p-tert-butylbenzoic acid, so the metal contamination of the silicon wafer and the elution amount of copper ions could not be suppressed. .

In Comparative Example 7 containing citric acid (6 carbon atoms) as the polyvalent carboxylic acid and not containing p-tert-butylbenzoic acid, rust prevention of the cast iron surface plate was effected by the action of monocarboxylic acid (caprylic acid). However, since it lacks the action of both polyvalent carboxylic acid and p-tert-butylbenzoic acid, the metal contamination of the silicon wafer and the elution amount of copper ions could not be suppressed.

In Comparative Example 8 containing isophthalic acid (carbon number 8) as a polyvalent carboxylic acid and containing p-tert-butylbenzoic acid, the cast iron surface plate has rust prevention and suppresses metal contamination of silicon wafers. As a result, there was an effect similar to that based on the presence of both polyvalent carboxylic acid having 7 or less carbon atoms and p-tert-butylbenzoic acid, but there was no tendency to suppress the elution amount of copper ions. However, it did not reach the acceptance criteria.

On the other hand, in Example 1-9, the cast iron surface plate has the rust prevention property by the action of p-tert-butylbenzoic acid, and the metal contamination of the silicon wafer is suppressed by the action of the polyvalent carboxylic acid having 2 to 7 carbon atoms. The elution amount of copper ions could also be suppressed by the presence of both polyvalent carboxylic acid and p-tert-butylbenzoic acid (see Table 1). As in Example 6, when the total blending amount of the polyvalent carboxylic acid and p-tert-butylbenzoic acid was reduced, the rust resistance of the cast iron surface plate was reduced.

[Evaluation of blending ratio of polyvalent carboxylic acid and p-tert-butylbenzoic acid]
Regarding the blending ratio of polyvalent carboxylic acid (citric acid: carbon number 6) and p-tert-butylbenzoic acid, referring to Table 3, in Examples 10-12 of 1: 4 or more and less than 2: 1, cast iron constant The board was rust-proof, and the metal contamination of the silicon wafer and the elution amount of copper ions could be suppressed. In addition, referring to Table 5 regarding the blending ratio of polycarboxylic acid (oxalic acid: carbon number 2) and p-tert-butylbenzoic acid, in Example 19-21, which is less than 2: 1, the resistance of cast iron surface plate is reduced. It was rusting and could suppress the metal contamination of the silicon wafer and the elution amount of copper ions.

[Evaluation of total blending amount of polycarboxylic acid and p-tert-butylbenzoic acid]
Referring to Table 4 for the total amount of polycarboxylic acid (citric acid: 6 carbon atoms) and p-tert-butylbenzoic acid, Example 13 is in the range of 0.05 wt% or more and 15 wt% or less. At -17, the cast iron surface plate had rust prevention, and the metal contamination of the silicon wafer and the elution amount of copper ions could be suppressed. As it approached 0.05 wt% or 15 wt%, the rust prevention property of the cast iron surface plate decreased, and the metal contamination of the silicon wafer tended to increase. In addition, referring to Table 6, the total amount of polycarboxylic acid (oxalic acid: 2 carbon atoms) and p-tert-butylbenzoic acid is in the range of 0.05 wt% or more and 15 wt% or less. In Examples 22 to 24, the cast iron surface plate had rust prevention properties, and metal contamination of the silicon wafer could be suppressed.

[Evaluation of basic substances]
Referring to Table 7, in Comparative Example 11 containing no basic substance, p-tert-butylbenzoic acid was not dissolved in water, and a stable processing medium could not be obtained.

(Appendix)
In the present invention, the form of the processing medium is possible.

In the processing medium, the polyvalent carboxylic acid preferably has 2 or more and 6 or less, 3 or more and 7 or less, more preferably 3 or more and 6 or less carbon atoms.

In the processing medium, the basic substance is one or more of a sodium compound, a potassium compound, an ammonium compound, and an amine compound.

In the processing medium, the basic substance includes a sodium compound and an amine compound.

In the processing medium, the basic substance includes a plurality of types of amine compounds.

The processing medium further includes water.

In the processing medium, the total of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is 0.05 wt% or more and 15 wt% or less, the basic substance is 0.1 wt% or more and 20 wt% or less, and the water is 50 wt%. Above and 99.7 wt% or less. The total blending amount of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is more preferably 0.1 wt% or more and 4 wt% or less, and further preferably 0.2 wt% or more and 2 wt% or less. The blending amount of the basic substance is more preferably 0.2 wt% or more and 10 wt% or less, and further preferably 0.5 wt% or more and 5 wt% or less. The blending amount of water is more preferably 80 wt% or more and 99.5 wt% or less, and further preferably 90 wt% or more and 98 wt% or less.

In the processing medium, the mixing ratio of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is 1: 4 or more and less than 2: 1. The blending ratio of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is more preferably 1: 1.8 or more and 1.8: 1 or less, and further preferably 1: 1.5 or more and 1.5: 1. It is as follows.

The pH of the processing medium is greater than 7. The pH is more preferably 8 or more and 12.5 or less, and still more preferably 8 or more and 10 or less.

The processing medium contains at least one of a surfactant, an antifoaming agent, a preservative, a fragrance, and a dye.

In the processing medium, a surfactant is blended in an amount of 0.01 wt% to 5 wt% with respect to 100 wt% of the processing medium according to any one of claims 5 to 7. The blending amount of the surfactant is preferably 0.02 wt% or more and 3 wt% or less, more preferably 0.05 wt% or more and 1 wt% or less.

In the processing medium, an antifoaming agent is blended in an amount of 0.001 wt% or more and 1 wt% or less with respect to 100 wt% of the processing medium according to claim 5. The blending amount of the antifoaming agent is preferably 0.002 wt% or more and 0.5 wt% or less, more preferably 0.005 wt% or more and 0.1 wt% or less.

The processing medium does not contain benzotriazole.

In the processing medium, the copper ion in the processing medium is 70 ppm or less when copper is immersed in the processing medium. When copper is immersed in the processing medium, the copper ion in the processing medium is preferably 60 ppm or less, more preferably 50 ppm or less.

In the present invention, the form of the processing composition is possible.

In the processing composition, when the silicon wafer is polished by supplying the processing composition to a contact portion between a cast iron surface plate and a silicon wafer, there is no metal contamination on the silicon wafer surface, or the silicon Metal contaminants on the wafer surface can be wiped off before drying.

In the processing composition, when the cast iron platen obtained by polishing a silicon wafer using the processing composition is immersed in the processing composition for 10 minutes at 30 ° C., the cast iron platen There is no generation of rust on the surface, or the generation of rust is 10 or less in an area of 70 mm × 50 mm.

In the present invention, the form of the processing method is possible.

It should be noted that the disclosure of the above patent document is incorporated herein by reference. Within the scope of the entire disclosure (including claims and drawings) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various combinations or selections of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the framework of the entire disclosure of the present invention (necessary) Can be selected). That is, the present invention naturally includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the drawings, and the technical idea. Further, regarding numerical values and numerical ranges described in the present application, it is considered that any intermediate value, lower numerical value, and small range are described even if not specified.

1 Silicon wafer 2 Metal contamination

Claims

A polyvalent carboxylic acid having 2 to 7 carbon atoms;
An aromatic monocarboxylic acid;
A processing medium containing a basic substance in a neutralized or neutralized state.
The processing medium according to claim 1, wherein the basic substance is at least one of a sodium compound, a potassium compound, an ammonium compound, and an amine compound.
The processing medium according to claim 1 or 2, wherein the basic substance includes a plurality of amine compounds.
The processing medium according to any one of claims 1 to 3, further comprising water.
The total of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is 0.05 wt% or more and 15 wt% or less,
The basic substance is 0.1 wt% or more and 20 wt% or less,
The processing medium according to claim 4, wherein the water is 50 wt% or more and 99.7 wt% or less.
The processing medium according to claim 5, wherein a mixing ratio of the polyvalent carboxylic acid and the aromatic monocarboxylic acid is 1: 4 or more and less than 2: 1.
The processing medium according to any one of claims 4 to 6, wherein the pH is greater than 7.
The processing medium according to any one of claims 1 to 7,
A processing composition comprising abrasive grains.
A machining method for machining the workpiece by supplying the machining medium according to any one of claims 1 to 7 or the machining composition according to claim 8 to a contact portion between a tool and the workpiece. .