JP4874772B2 - Cleaning composition for sliced silicon wafer or ingot - Google Patents

Description

  The present invention relates to a water-dilutable sliced silicon wafer or ingot cleaning composition.

Silicon wafers used for substrates such as ICs and LSIs and solar cells are manufactured by slicing cylindrical ingots. As an apparatus for slicing a silicon wafer, there are mainly an inner peripheral blade method, a band saw method, a wire saw method, and the like. In recent years, with the increase in the diameter of silicon wafers, a wire saw method is frequently used which can reduce the cutting time because a large number of slices can be sliced at a time and can improve the yield because the slice thickness can be made uniform.
In the wire saw method, an ingot of a silicon wafer bonded with an epoxy adhesive to a slice base is cut using a cutting device in which a wire having a thickness of about 200 μm is installed at equal intervals of several tens to several thousand μm as necessary. To do. In this cutting step, a grinding fluid in which abrasive grains such as silicon carbide (SiC) are dispersed in a high-viscosity cutting oil is used. The ingot after slicing was in a state in which dirt such as abrasive grains, cutting oil, silicon polishing scraps, and the like were clogged in the gap of about 200 μm through which the wire passed, and its cleaning was extremely difficult.
As a method for cleaning dirt adhered to an ingot after cutting with a wire saw, after removing from the slice base or in the state of the ingot, first, oily dirt derived from cutting oil is washed with kerosene, and then polished with an alkaline cleaner. There is known a method of cleaning mainly particle dirt such as grains and polishing waste. However, kerosene cleaning is unsuitable for cleaning using mechanical force because of the risk of ignition, and lacks cleaning power for particle dirt, so that even oily dirt adhering to particles cannot be sufficiently cleaned. For this reason, there is a problem in that a cleaning failure is caused by subsequent alkali cleaning, and the cleaning power is rapidly reduced.
In order to solve the above problem, a semi-aqueous cleaning agent composed of a hydrocarbon, a glycol solvent, a nonionic surfactant and water for simultaneously cleaning oily soil and particle soil has been proposed (Patent Document 1). In addition, an aqueous detergent comprising an ethylene glycol solvent, a surfactant, and water that can be diluted with water by removing hydrocarbon components such as kerosene from the composition has been proposed (Patent Document 2). However, in the semi-aqueous cleaning agent, when the water is diluted such as when water is mixed from the previous process, the liquid stability is not sufficient in that the oil and water are separated into white turbidity, and the aqueous cleaning does not contain hydrocarbons. The agent is not sufficient for cleaning oily soil.

Japanese Patent Laid-Open No. 9-223679 (Claims, Examples, etc.) JP 2000-77380 A (Claims, Examples, etc.)

  The present invention relates to a semi-aqueous cleaning agent mainly composed of kerosene or an oil agent (hydrocarbon solvent), which is mainly used for cleaning a polishing liquid (cutting oil, abrasive, cutting waste, etc.) after cutting a silicon wafer. Of these, attention is paid to the cutting oil cleaning power possessed by the hydrocarbon solvent-based cleaning agent, and it is an object to solve the problems of the prior art possessed by such cleaning agent. That is, the present invention provides a cleaning composition for use in a semi-aqueous silicon wafer manufacturing process that does not perform liquid separation (oil-water separation) even in a state diluted with water, and has excellent cleaning properties and rinsing properties. This is the issue.

As a result of intensive studies by the present inventors, it has been found that the above-mentioned problems can be solved by adjusting the blending amount and blending ratio of hydrocarbon and anionic surfactant and employing an organic carboxylic acid chelating agent as the chelating agent. . That is, the present invention
(A) C10-14 aliphatic hydrocarbon: 10-40% by mass
(B) Anionic surfactant: 20-50% by mass
(C) Short chain glycol ether represented by the following formula (I) R—O (AO) nH (I): 1 to 55% by mass
(In the formula, R is a hydrocarbon group having 1 to 6 carbon atoms, AO is oxyethylene or oxypropylene, and n is 1 to 4.)
(D) Organic carboxylic acid chelating agent: 0.01-0.5% by mass
(E) Water: 5-30% by mass
It is an object of the present invention to provide a cleaning composition for sliced silicon wafers or ingots, which contains a component (A) / component (B) ratio of 0.3 to 2.0 (mass ratio).

  According to the present invention, not only during storage in the state of the stock solution, but also in a state diluted with water to be used for cleaning, liquid separation does not occur at room temperature or low temperature, and the cleaning property, particularly the particle cleaning property. In addition, it is possible to provide a cleaning composition excellent in rinsing properties for use in a silicon wafer manufacturing process. The cleaning composition provided by the present invention does not separate from the state of (W / O) emulsion at the time of concentration to the state of (O / W) emulsion diluted with water during dilution with water, and excessively Smooth phase inversion without thickening.

(Component A): Aliphatic hydrocarbon The aliphatic hydrocarbon has a cutting oil dissolution effect, that is, an oil cleaning effect. The aliphatic hydrocarbon that can be used in the present invention is a linear or branched saturated or unsaturated hydrocarbon compound having 10 to 14 carbon atoms, specifically, decane, undecane, dodecane, tridecane, tetradecane, and the like. Examples of olefins corresponding to the paraffins. If the carbon number is less than 10, it is dangerous because the cleaning composition is easily flammable, and if the carbon number exceeds 14, the dissolving power of the cutting oil-derived oily dirt against hydrocarbons is not preferable. A linear or branched saturated or unsaturated hydrocarbon compound having 12 to 14 carbon atoms, particularly 12 carbon atoms is preferred because it has excellent dissolving power for oily soils and is difficult to ignite due to its relatively high boiling point. Aliphatic hydrocarbons can be used alone or in combination of two or more. A commercial item can be used as an aliphatic hydrocarbon, for example, normal energy N12D by Japan Energy can be used.
In the composition of this invention, a component (A) is contained in the quantity of 10-40 mass%. If the amount is less than 10% by mass, the cleaning property (oily soil cleaning property) when diluted and washed with water may decrease, and if it exceeds 40% by mass, the liquid stability (liquid may be separated) may be decreased. From the viewpoint of the detergency of oily soil, it is preferably contained in an amount of 15 to 40% by mass, more preferably 25 to 35% by mass.

(Component B): Anionic surfactant The anionic surfactant is transparent and uniform when improved in particle cleaning properties, solubilization of oil and water, that is, when the oily soil derived from the hydrocarbon of component (A) and cutting oil is mixed with water. Contributes to the formation of a stable emulsion. The anionic surfactant that can be used in the present invention is not particularly limited. For example, an α-olefin sulfonate having an average carbon number of 10 to 20, a sulfosuccinic acid type anionic surfactant (for example, dialkyl or dialkenyl sulfosuccinate), a paraffin sulfonate, an alkyl sulfate having an average carbon number of 10 to 20 An alkyl (or alkenyl) ether sulfate having a linear or branched alkyl or alkenyl group having an average carbon number of 10 to 20 and having an average of 0.5 to 8 moles of ethylene oxide added, an average carbon number of 5 to 22 And saturated or unsaturated fatty acid salts, linear alkylbenzene sulfonates having an alkyl group having an average carbon number of 8 to 16 and the like.
Of these, dialkyl or dialkenyl sulfosuccinates and paraffin sulfonates are preferred because they are excellent in water and oil solubilizing power and liquid stability. In particular, dialkyl or dialkenyl sulfosuccinate is more preferable because it is excellent in solubilizing power of organic substances, contributes to improvement of penetrating power, and is excellent in performance of raising the cloud point of the composition.
As the sulfosuccinic acid type anionic surfactant, a sulfosuccinic acid alkyl (or alkenyl) ester type surfactant represented by the following general formula is particularly preferred.

In the formula, R ² and R ³ may be the same or different and each represents an alkyl group or alkenyl group having 3 to 22 carbon atoms, preferably 6 to 12 carbon atoms, preferably an alkyl group. For example, isobutyl, pentyl, hexyl, octyl, 2-ethylhexyl, dodecyl, hexadecyl and the like can be mentioned. Of these, octyl having excellent liquid stability and the like is particularly preferable. M is a counter ion and represents an alkali metal, alkaline earth metal, ammonium or amine compound salt. As the ammonium ion, quaternary ammonium ions of various amine compounds can be used. M is preferably an alkali metal, and more preferably sodium. An anionic surfactant can also be used individually by 1 type, and can also use 2 or more types together.
Commercially available products can be used as the anionic surfactant, and for example, Lion's Ripar 870P, Clariant Japan's HOSTAPUR SAS 30 can be used.

In the composition of the present invention, the component (B) is contained in an amount of 20 to 50% by mass. If the amount is less than 20% by mass, the cleaning property (particle contamination) may be reduced, or the liquid stability of the cleaning agent composition may be reduced. May be worse. Preferably it is 20-40 mass%, More preferably, it is 20-35 mass%.
In the cleaning composition of the present invention, the mass ratio of the component (A) to the component (B) needs to be 0.3 to 2.0. Outside the above range, it is extremely difficult to obtain a uniform cleaning composition when diluted with water. Preferably it is 0.3-1.8, More preferably, it is 0.6-1.8, It is especially preferable to set it as 0.9-1.3.

(Component C): Short-chain glycol ether The short-chain glycol ether plays a role of solubilizing the hydrocarbon and oily soil of the component (A) and stabilizing a transparent and uniform liquid state. The short-chain glycol ether that can be used in the present invention is an alkylene oxide adduct of a monohydric alcohol having a short-chain alkyl (alkenyl) represented by the above general formula (I).
In the formula (I), R is a hydrocarbon group having 1 to 6 carbon atoms, preferably 4 to 6 carbon atoms, AO is oxyethylene or oxypropylene, and n is a number from 1 to 4, preferably 1 to 3. It is. AO is preferably oxyethylene. Specific examples include diethylene glycol n-butyl ether, triethylene glycol n-butyl ether, tripropylene glycol n-butyl ether, ethylene glycol n-hexyl ether, and diethylene glycol n-hexyl ether (hexyl diglycol). Among these, from the viewpoint of solubilization and liquid stabilization of oil water, diethylene glycol n-butyl ether, triethylene glycol n-butyl ether, ethylene glycol n-hexyl ether, and hexyl diglycol are preferable, and hexyl diglycol is more preferable. A short chain glycol ether can also be used individually by 1 type, and can also use 2 or more types together.
Commercially available products can be used as the short-chain glycol ether. For example, hexyl diglycol manufactured by Nippon Emulsifier can be used.
In the composition of the present invention, the component (C) is contained in an amount of 1 to 55% by mass. If it is less than 1%, the liquid stability may be lowered, and if it exceeds 55%, the washability may be lowered. Preferably it is 20-40 mass%, More preferably, it is 20-30 mass%.

(Component D): Organic carboxylic acid-based chelating agent The organic carboxylic acid-based chelating agent is effective for cleaning and removing particles such as abrasives. If not blended, the particles may adhere and cause poor cleaning. Examples of organic carboxylic acid chelating agents that can be used in the present invention include carboxylic acid chelating agents such as oxalic acid, maleic acid and salts thereof, and hydroxycarboxylic acid chelating agents such as citric acid, tartaric acid, gluconic acid and salts thereof. Aminocarboxylic acid chelating agents such as nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminopentaacetic acid (DTPA) and their salts, and hydroxyaminocarboxylic acid chelating agents such as dihydroxyethylglycine and its salts And ether carboxylic acid-based chelating agents such as carboxymethyl tantronic acid, carboxymethyl oxysuccinic acid, and salts thereof. The organic carboxylic acid chelating agent can be used alone or in combination of two or more.
Of these, hydroxycarboxylic acid-based chelating agents and aminocarboxylic acid-based chelating agents are preferred because they are easily dissolved in water and have excellent chelating power. Excellent liquid stability, even if more can be added, water dilution is not impaired, chelating power is weaker than amino, but liquid stability (especially low temperature) is excellent and liquid separation is difficult to occur. Therefore, hydroxycarboxylic acid-based chelating agents such as citric acid are more preferable, and citric acid and salts thereof are particularly preferable.
In the composition of the present invention, the component (D) is contained in an amount of 0.01 to 0.5% by mass. If it is less than 0.01%, the washability may be lowered, and if it exceeds 0.5%, the liquid stability may be lowered. From the viewpoint of achieving both particle cleaning properties and liquid stability (water dilution properties), the content is preferably 0.1 to 0.3% by mass.

(Component E): Water Water is used to make the composition of the present invention non-hazardous. The water that can be used in the present invention is not particularly limited as long as it does not impair the effect of the cleaning composition of the present invention. Specifically, ultrapure water, pure water, ion exchange water, distilled water, normal tap water, or the like can be used.
In the composition of the present invention, the component (E) is contained in an amount of 5 to 30% by mass. If it is less than 5%, the composition of the present invention may be flammable. If it exceeds 30% by mass, the proportion of the cleaning component is reduced when it is further diluted with water and sufficient detergency can be exhibited. Since it disappears, it is not preferable. From the viewpoint of safety (flammability), it is preferably 10 to 30%.

In the composition of the present invention, as an optional component, a preservative, a rust preventive agent, or the like can be blended to such an extent that the liquid stability of the composition is not impaired.
The composition of the present invention is not particularly limited as a production method, and may be prepared by blending each component according to a conventional method. In this case, the blending order of each component may be arbitrary, but after thoroughly mixing components other than water, it is preferable to prepare a uniform liquid composition while adding water little by little.
When using the detergent composition, it can be used as it is or diluted with water. The water used for dilution can be ion-exchanged water, distilled water, city water, etc. For example, it is diluted 2 to 4 times by mixing at a weight ratio of detergent composition: water = 1: 1 to 1: 3. A washed liquid can be obtained. As a cleaning method, immersion cleaning, jet cleaning, ultrasonic cleaning, or the like can be used. The silicon wafer slicing method mainly includes an inner peripheral blade method, a band saw method, a wire saw method, etc., but the composition of the present invention is particularly suitable for cleaning a polishing solution of a silicon wafer cut by a wire saw method, and further 180 μm. It is suitable for cleaning contaminants such as cutting oil, grindstones, and cutting powder clogged in a narrow gap of about 200 μm in a cutting portion of an ingot cut with a wire saw having a thickness of about.
If the composition of the present invention is used, water is brought into the cleaning tank of the silicon wafer or the cut ingot when the ingot cut in the previous step is washed with water, and the cleaning agent in the cleaning tank is used with the water. Even if the composition is diluted, it can be washed without causing liquid separation of oil and water.

  Using the substances shown in Table 1 below, the cleaning compositions of Examples and Comparative Examples were prepared. Each composition was stirred and adjusted to be a uniform transparent liquid composition while adding components other than water little by little to water.

About each adjusted composition, liquid stability, washability, and a rinse were evaluated as follows. The compounding amount of each component in Table 2 is shown in mass% with respect to the total amount of the cleaning composition. The results are shown in Table 2.
Evaluation method 1) Liquid stability:
After blending each composition in the range of 20-40 ° C. to obtain a uniform transparent liquid, it was stored at room temperature (25 ° C.) and low temperature (5 ° C.) for 1 day, and the liquid state was visually confirmed after 1 day. . (Liquid stability is good if uniform and transparent). The compositions of Examples 1 and 2 had good liquid stability (evaluation ◎) even when diluted 4 times.
Evaluation: ◎; Uniform and transparent at both room temperature and low temperature ○; Uniform and transparent at room temperature, White turbidity at low temperature △; White turbidity at room temperature, separation at low temperature ×: White turbid separation at both room temperature and low temperature

2) Detergency:
A 2-inch wrapped wafer (sales agent: Wakatech Co., Ltd.) was used as the cleaning test piece. The model dirt was prepared by adjusting a polishing liquid in which a mineral oil-based cutting oil (PS-1 manufactured by Palace Chemical Co., Ltd.) and a silicon carbide abrasive (manufactured by Fujimi Incorporated) were mixed at a ratio of 1: 1. Apply 0.3g of this model dirt to one wafer, apply a 200μm thick vinyl tape to a part of the edge of this wafer and adjust it so that there is a 200μm gap. The test piece for cleaning was clamped with a wafer and fastened with a clip. The width of the gap was confirmed by measuring the thickness of the two wafers and the thickness of the two stacked tapes with a micrometer (thickness meter), and checking the difference between the two. This model dirt wafer was immersed in various cleaning liquids heated to 50 ° C. and irradiated with 50 kHz ultrasonic waves for ultrasonic cleaning. Subsequently, it was immersed in 90 degreeC hot water for 5 minutes, and rinsed. The rinsed wafer was dried with a dryer at 100 ° C. for 30 minutes, and the cleaning rate was calculated from the change in the weight of the dirt. (Higher cleaning rate is better). The compositions of Examples 1 and 2 had a good cleaning rate (evaluation で も) even when diluted 4 times.
Cleaning rate (%) = {(stained weight before cleaning−stained weight after cleaning) / stained weight before cleaning} × 100
Evaluation: ◎; Cleaning rate of 95% or more ◎ to ○; Cleaning rate of 90 to less than 95% ○; Cleaning rate of 80 to less than 90% ○ to Δ; Cleaning rate of 70 to less than 80% Less than -70% Slightly contaminated with particles Δ-X; Cleaning rate of less than 50-60% Many particles with contamination ×: Cleaning rate of less than 50%

3) Rinsing property: The surface state of the silicon wafer after the cleaning test was observed and visually judged. (It is better to have no stain residue). The compositions of Examples 1 and 2 had good rinsing properties (evaluation ◎) even when diluted 4 times.
Evaluation: ◎; No stain left on the cleaning agent ◎ ~ ○: Slight stain on the cleaning agent is observed ○; Slight stain on the cleaning agent is observed ○ ~ △; △: About half of the stain on the surface of the silicon wafer is observed Δ-X: About 3/4 of the stain on the surface of the silicon wafer is observed on the surface of the silicon wafer ×; Can be seen all over

Claims (3)

(A) C10-14 aliphatic hydrocarbon: 10-40% by mass
(B) Anionic surfactant: 20-50% by mass
(C) Short chain glycol ether represented by the following formula (I) R—O (AO) nH (I): 1 to 55% by mass
(In the formula, R is a hydrocarbon group having 1 to 6 carbon atoms, AO is oxyethylene or oxypropylene, and n is 1 to 4.)
(D) Organic carboxylic acid chelating agent: 0.01-0.5% by mass
(E) Water: 5-30% by mass
And a cleaning composition for a sliced silicon wafer or ingot having a component (A) / component (B) ratio of 0.3 to 2.0 (mass ratio).   (B) The detergent composition according to claim 1, wherein the anionic surfactant is dioctylsulfosuccinic acid or a salt thereof.   (D) The detergent composition according to claim 1 or 2, wherein the organic carboxylic acid chelating agent is sodium citrate.