WO2012132448A1

WO2012132448A1 - Hydrous cutting fluid for slicing silicon ingot

Info

Publication number: WO2012132448A1
Application number: PCT/JP2012/002176
Authority: WO
Inventors: 剛福島; 吉隆勝川; 聖二山下
Original assignee: 三洋化成工業株式会社
Priority date: 2011-03-31
Filing date: 2012-03-29
Publication date: 2012-10-04
Also published as: JP2013047319A; KR20140009333A; MY162332A; KR101577588B1; JP5634428B2; CN103502409A; CN103502409B

Abstract

The present invention provides a cutting fluid which, in the step of cutting a silicon ingot, is superior to conventional products in the removal of processing heat, infiltrating property, inhibition of reaction between water and the silicon, and antifoaming property to thereby attain an improvement in cutting efficiency, and with which silicon wafers having satisfactory flatness are yielded. The accuracy of the processed surface can hence be kept high even under severe slicing conditions. The cutting fluid is a hydrous cutting fluid for silicon-ingot slicing, characterized by comprising a polyoxyalkylene adduct (A) of a compound (a) having 3-8 hydroxy groups, the adduct (A) being represented by general formula (1), and water as essential components, the polyoxyalkylene adduct (A) having an HLB of 6.0-20.0. R{O-(A¹O)_m-H}_f (1) [In formula (1), R represents the residue formed by removing the hydroxyl groups from a compound having 3-8 hydroxy groups; (A¹O) represents a C_2-4 oxyalkylene; m, indicating the average number of moles of a C_2-4 alkylene oxide which has added, is a number of 1-350; and f is an integer of 3-8.]

Description

Hydrous cutting fluid for slicing silicon ingot

The present invention relates to a water-containing cutting fluid used when cutting a silicon ingot. More specifically, the present invention relates to a water-containing cutting fluid that has high cooling properties, excellent penetrability, suppression of reaction between silicon and water, foam suppression, and flatness of a silicon wafer.

The slicing method using a silicon ingot wire includes (1) a method using an abrasive slurry in which free abrasive grains are dispersed in a cutting fluid, and (2) a fixed abrasive wire in which the abrasive grains are fixed to the wire by electrodeposition or resin adhesion. The method is roughly classified into methods using a water-containing cutting fluid.
In recent years, the water-containing cutting fluid used in the slicing method with a fixed abrasive wire is intended to improve the workability by reducing the risk of flammability caused by organic solvents, and to increase the cooling performance of frictional heat generated during cutting. A hydrous cutting fluid containing water having a high specific heat has been developed (for example, Patent Document 1).

Although conventional water-containing cutting fluid can increase the specific heat of the cutting fluid itself by increasing the moisture content, the penetration of the cutting fluid into the cutting part is low, so the cooling heat cannot be removed sufficiently. There was a problem that the processing accuracy of was low.
In addition, there is insufficient suppression of the reaction between silicon chips and silicon wafers generated by cutting and water, and hydrogen gas is generated, which may cause a flammable explosion. Furthermore, in the slicing process of the silicon ingot, there is a problem such as foaming because the cutting fluid is circulated and reused.

In recent years, silicon wafers are being made thinner for the purpose of increasing the production efficiency of silicon wafers.
Usually, the thinning of the wire and the narrowing of the pitch width between the wires reduce the thickness of the silicon wafer, but this increases the contact area between the wire and the silicon ingot and increases the processing heat during processing. Development of cutting fluid with high cooling performance is desired.
In addition, since the silicon wafer interval during processing becomes narrower than before in order to make the silicon wafer thinner, high penetrability of the cutting fluid into the cutting portion is required.

However, generally, when the silicon wafer is thinned or the slice processing time is shortened, there is a problem that the flatness of the silicon wafer surface generally deteriorates.
Therefore, as a countermeasure, a method of adding an alkylene oxide adduct of an organic amine as a lubricating component has been proposed (for example, Patent Document 2), but the effect on the level of flatness corresponding to the thinning is still insufficient. .
That is, in recent years, from the viewpoint of simplifying the silicon wafer flattening process and increasing the accuracy of texture formation, higher flatness is desired in the silicon wafer after slicing.

JP 2003-82335 A JP 2009-57423 A

Therefore, the water-containing cutting fluid of the present invention is for silicon ingot slices that have high cooling performance of processing heat, excellent permeability, excellent suppression of reaction between water and silicon, foam suppression, and extremely good flatness of silicon wafers. It aims at providing a water-containing cutting fluid.

The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention contains a polyoxyalkylene adduct (A) of a compound (a) having 3 to 8 hydroxyl groups represented by the following general formula (1) and water as essential components. Hydrous cutting fluid for silicon ingot slice characterized by HLB of adduct (A) being 6.0 to 20.0; wire saw for fixed abrasive with this hydrous cutting fluid and abrasive grains fixed to wire Slicing method of silicon ingot to be used; manufacturing method of slicing silicon ingot with this water-containing cutting fluid by fixed abrasive method; silicon wafer manufactured by slicing silicon ingot using this water-containing cutting fluid; and using this silicon wafer It is an electronic material manufactured by

[In the formula (1), R represents a residue obtained by removing a hydroxyl group from a compound having 3 to 8 hydroxyl groups, and (A ¹ O) represents an oxyalkylene group having 2 to 4 carbon atoms. m represents the average number of moles of alkylene oxide having 2 to 4 carbon atoms and represents a number of 1 to 350, and f is an integer of 3 to 8. ]

The present invention has a high process heat cooling property in the cutting process of the silicon ingot, and is excellent in permeability, water reaction suppression property, and foam suppression property. Even under severe slicing conditions, the flatness of the work surface can be maintained high.

The hydrous cutting fluid for slicing silicon ingot of the present invention contains a polyoxyalkylene adduct (A) of a compound (a) having 3 to 8 hydroxyl groups and water as essential components. And m which is the average addition mole number of HLB (hydrophilic-hydrophobic balance) and alkylene oxide of the polyoxyalkylene adduct (A) is in a specific range.

The polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups, which is the first essential component of the water-containing cutting fluid of the present invention, is represented by the following general formula (1).

[In the formula (1), R represents a residue obtained by removing a hydroxyl group from the compound (a) having 3 to 8 hydroxyl groups, and (A ¹ O) represents an oxyalkylene group having 2 to 4 carbon atoms. m represents the average number of moles of alkylene oxide having 2 to 4 carbon atoms and represents a number of 1 to 350, and f is an integer of 3 to 8. ]

Specific examples of the compound (a) having 3 to 8 hydroxyl groups used in the present invention include
Compounds having three hydroxyl groups such as glycerin, trimethylolpropane, trimethylolethane;
Compounds having four hydroxyl groups such as pentaerythritol, glucose, fructose, diglycerin;
Compounds having five hydroxyl groups such as xylitol and triglycerin;
Compounds having 6 hydroxyl groups such as sorbitol and dipentaerythritol;
Compounds having 8 hydroxyl groups such as sucrose;
Polyvinyl alcohol, polyglycerin, etc. are mentioned.

Among these compounds (a) having 3 to 8 hydroxyl groups, preferred are compounds having 3 to 6 hydroxyl groups from the viewpoint of permeability. More preferred are glycerin having three hydroxyl groups, trimethylolpropane, and pentaerythritol.

In the present invention, the HLB of the polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups is usually 6.0 to 20.0. It is preferably 10.0 to 18.5. If it is this range, the permeability of cutting fluid will be excellent and the cooling property of processing heat will improve more.
On the other hand, if it is less than 6.0, solubility in water becomes difficult. When it exceeds 20.0, the reaction inhibition property between silicon and water deteriorates.

Here, “HLB” is an index indicating a balance between hydrophilicity and lipophilicity, and is described in, for example, “Introduction to Surfactants” (published by Sanyo Chemical Industries, Ltd., 2007, Takehiko Fujimoto), page 212. It is known as the calculated value by the Oda method, not the calculated value by the Griffin method.
The HLB value can be calculated from the ratio between the organic value and the inorganic value of the organic compound.
HLB = 10 × inorganic / organic The organic value and the inorganic value for deriving HLB can be calculated using the values in the table described in the above “Introduction to Surfactant” page 213.

A ¹ O represents an oxyalkylene group having 2 to 4 carbon atoms, and specific examples thereof include an oxyethylene group, an oxypropylene group, and an oxybutylene group.
In the case of an oxyethylene group, ethylene oxide, in the case of an oxypropylene group, 1,2-propylene oxide, 1,3-propylene oxide, in the case of an oxybutylene group, tetrahydrofuran, 1,2-butylene oxide and the like can be used.

In the polyoxyalkylene adduct (A) in the present invention, one kind of ethylene oxide, propylene oxide, tetrahydrofuran, and 1,2-butylene oxide is added alone to the compound (a) having 3 to 8 hydroxyl groups. They may be added, or two or more of these may be used in combination.
From the viewpoint of permeability, two types of combined use of ethylene oxide and propylene oxide are preferable.

In the polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups in the present invention, the addition form when two or more alkylene oxides or tetrahydrofuran is used in combination may be random or block, Further, the order of adding two or more alkylene oxides, for example, ethylene oxide and propylene oxide is not limited.

m represents the average number of moles of alkylene oxide having 2 to 4 carbon atoms, and when two or more kinds of alkylene oxide are used in combination, the total number of moles of two or more kinds of added moles.
m is usually a number from 1 to 350, preferably from 1 to 100.
When m is less than 1, the reaction inhibition property between silicon and water deteriorates. On the other hand, when m exceeds 350, the viscosity of the cutting fluid is too high, so that the permeability, foam suppression, and flatness of the silicon wafer are lowered.

-(A ¹ O) _m-in the formula (2) of the polyoxyalkylene adduct (A) in the present invention can be represented by the following general formula (2).

Wherein ^{(2), A} 2 O is an oxyethylene group, ^{A 3} O represents an oxypropylene group. n represents the average number of moles of ethylene oxide added and represents a number of 1 to 250, k represents the average number of moles of propylene oxide added and represents a number of 1 to 100, and n / (n + k) is 0.1 to 0.9. The addition form of ethylene oxide and propylene oxide may be random or block. ]

n represents the average number of moles of ethylene oxide added, and is a number from 1 to 250, preferably from 1 to 20, more preferably from 1 to 250 from the viewpoints of solubility in water, foam suppression and silicon wafer permeability. 15.

k represents the average number of added moles of propylene oxide, and is a number of 1 to 100, preferably 1 to 15, more preferably 1 to 12 from the viewpoint of the reaction suppression between silicon and water and the flatness of the silicon wafer. It is.

N / (n + k) is 0.1 to 0.9. From the viewpoint of solubility in water and penetration of the cutting fluid into the machined part, it is preferably 0.4 to 0.7. Note that n + k = m.

In the present invention, the addition state of ethylene oxide and propylene oxide in the polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups may be random or block, and the compound having 3 to 8 hydroxyl groups The order of addition to (a) does not matter.

Specific examples of the polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups in the present invention include:
A polyoxyalkylene adduct of a compound having three hydroxyl groups such as glycerin, trimethylolpropane and trimethylolethane;
A polyoxyalkylene adduct of a compound having four hydroxyl groups such as pentaerythritol, glucose, fructose, diglycerin;
A polyoxyalkylene adduct of a compound having five hydroxyl groups such as xylitol and triglycerin;
A polyoxyalkylene adduct of a compound having 6 hydroxyl groups such as sorbitol and dipentaerythritol;
A polyoxyalkylene adduct of a compound having 8 hydroxyl groups such as sucrose;
Examples thereof include polyoxyalkylene adducts such as polyvinyl alcohol and polyglycerin.

The polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups in the present invention is preferably a polyoxyalkylene adduct of a compound having 3 to 6 hydroxyl groups from the viewpoint of permeability.
More preferred are polyoxyalkylene adducts of glycerin, trimethylolpropane, pentaerythritol and sorbitol.

Specific examples of the polyoxyalkylene adduct (A) of the present invention include 4.8 moles of glycerol ethylene oxide (hereinafter sometimes abbreviated as EO) and 1,2-propylene oxide (hereinafter abbreviated as PO). 3.6 mol random adduct, glycerin EO 17.1 mol and PO 12.9 mol random adduct, glycerin EO 30.9 mol and PO 23.4 mol random adduct, glycerin EO23 EO-PO random adducts of glycerin such as .7 mol and PO 35.7 mol random adducts;
EO-PO block adducts of glycerin, such as block adducts of glycerin EO 12.0 mol and PO 9.0 mol, glycerin EO 11.3 mol and PO 57.7 mol;
PO adducts of glycerin such as PO 15.6 mol adduct of glycerin;
An EO adduct of glycerin, such as an EO 70.0 molar adduct of glycerin;
EO-PO random adduct of trimethylolpropane such as 30.3 mol of trimethylolpropane EO and 23.1 mol of PO random adduct;
EO-PO random adducts of pentaerythritol, such as 40.4 mol of EO of pentaerythritol and a random adduct of 30.8 mol of PO;
EO-PO block adduct of pentaerythritol, such as a block adduct of 19.6 mol EO of pentaerythritol and 12.0 mol of PO;
Sorbitol EO-PO random adducts such as sorbitol EO 60.6 mol and PO 45.6 mol random adduct.
Of these, EO-PO random adduct of glycerin and EO-PO block adduct of glycerin are preferable from the viewpoints of permeability and reaction inhibition.

The number average molecular weight of the polyoxyalkylene adduct (A) in the present invention is preferably 400 to 10,000, more preferably 400 to 6, from the viewpoints of permeability and productivity of the polyoxyalkylene adduct (A). 000.
The number average molecular weight is a molecular weight determined by gel permeation chromatography (GPC).

The content of the polyoxyalkylene adduct (A) in the present invention is 0.1 to 40% by weight with respect to the cutting fluid at the time of use. Preferably, the content is 0.4 to 30% by weight, and more preferably 0.4 to 25% by weight.

The water, which is the second essential component of the water-containing cutting fluid for silicon ingot slicing of the present invention, may be any of pure water, ion exchange water, tap water, city water, industrial water, and the like.

In the water-containing cutting fluid for silicon ingot slicing of the present invention, it is preferable to further contain an aliphatic carboxylic acid (B) for the purpose of improving the flatness of the silicon wafer.

The aliphatic carboxylic acid (B) used for this purpose is a monovalent or divalent linear or branched aliphatic carboxylic acid having 8 or 9 carbon atoms including the carbon atom of the carbonyl group. When the aliphatic carboxylic acid is used, the flatness of the silicon wafer can be further improved while maintaining the foam suppression property of the cutting fluid.

Specific examples of the aliphatic carboxylic acid (B) include monovalent caprylic acid and pelargonic acid; divalent suberic acid and azelaic acid.
Among the aliphatic carboxylic acids (B), caprylic acid and azelaic acid are preferable from the viewpoint of foam suppression and flatness of the silicon wafer.

It is preferable that the water-containing cutting fluid for slicing silicon ingot of the present invention further contains a specific nonionic surfactant for the purpose of improving permeability.

The specific nonionic surfactant used for this purpose is a nonionic surfactant (C) having an HLB of 6.0 to 8.5, but the polyoxyalkylene adduct (A), which is an essential component, is a nonionic surfactant. Excluded from surfactant (C). When the HLB is within this range, the wettability of the cutting fluid with respect to silicon is improved, and the permeability can be further improved.

Specific examples of the nonionic surfactant (C) having an HLB of 6.0 to 8.5 include butanol, PO 4.5 mol adduct, propylene glycol EO 4.5 mol PO, 28.0 mol block adduct, etc. An alkylene oxide adduct (C1) of a monohydric or dihydric alcohol having an HLB of 6.0 to 8.5;
An alkylene oxide adduct (C2) of an amine having an HLB of 6.0 to 8.5, such as a random adduct of stearylamine EO 3 mol PO3 mol, dibutylamine EO 3.0 mol and PO 11.0 block adduct;
Examples thereof include alkylene oxide adducts (C3) of higher fatty acids such as EO 3.0 mol adduct of oleic acid and EO 3.0 mol adduct of stearic acid.

The water-containing cutting fluid for slicing a silicon ingot of the present invention can be suitably used when slicing a silicon ingot with a wire.
As a method of slicing a silicon ingot using the water-containing cutting fluid for slicing silicon ingot of the present invention, a method using an abrasive slurry in which free abrasive grains are dispersed in a cutting fluid, a fixed abrasive wire saw in which the abrasive is fixed to a wire There is a method of using. Although the water-containing cutting fluid of the present invention can be applied to any of them, it is particularly suitable for a silicon ingot slicing method using a fixed abrasive wire saw.

The water-containing cutting fluid for slicing silicon ingot of the present invention can be suitably used when a silicon wafer is produced by slicing a silicon ingot with a wire.
As a method of manufacturing a silicon wafer by slicing a silicon ingot using the water-containing cutting fluid for slicing silicon ingot of the present invention, a method using an abrasive slurry in which free abrasive grains are dispersed in a cutting fluid, or an abrasive grain is fixed to a wire There is a method using a fixed abrasive wire saw. Although the water-containing cutting fluid of the present invention can be applied to any of them, it is particularly suitable for a silicon wafer manufacturing method for slicing a silicon ingot using a fixed abrasive wire saw.

A silicon wafer can be manufactured by slicing a silicon ingot using the water-containing cutting fluid for slicing silicon ingot and the wire of the present invention. The silicon wafer sliced by the above manufacturing method can be used as a silicon wafer for solar cells, a silicon wafer for semiconductor devices, or the like.

The above silicon wafer can be used for electronic materials such as solar cell, memory element, oscillation element, amplification element, transistor and diode.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

Production Example 1 <Production of glycerin EO-PO random adduct (A-1)>
A stainless steel pressure reactor was charged with 92 parts of glycerin and 0.05 part of sodium hydroxide, and after nitrogen substitution, a mixed liquid of 204 parts of ethylene oxide and 204 parts of propylene oxide was injected at 120 to 140 ° C. in about 4 hours.
The reaction is further performed at the same temperature for 10 hours to obtain an EO-PO random adduct (A-1) of glycerin of the present invention (f = 3; m = 2.8; n = 1.6; k = 1.2; n /(N+k)=0.57; number average molecular weight 500; HLB = 17.5). The number average molecular weight is a molecular weight determined by gel permeation chromatography (GPC).

Production Example 2 <Production of glycerin EO-PO random adduct (A-2)>
The same operation as in Production Example 1 was performed except that 29 parts of glycerin, 238 parts of ethylene oxide, and 238 parts of propylene oxide were produced in Production Example 1, and the EO-PO random adduct (A- 2) (f = 3; m = 12.0; n = 5.7; k = 4.3; n / (n + k) = 0.57; number average molecular weight 1,600; HLB = 13.3) It was.

Production Example 3 <Production of glycerin EO-PO random adduct (A-3)>
The same operation as in Production Example 1 was conducted except that 16.4 parts of glycerin, 241 parts of ethylene oxide, and 241 parts of propylene oxide were produced in Production Example 1, and the EO-PO random adduct of glycerin of the present invention ( A-3) (f = 3; m = 18.1; n = 10.3; k = 7.8; n / (n + k) = 0.57; number average molecular weight 2,800; HLB = 12.6) Got.

Production Example 4 <Production of glycerin EO-PO random adduct (A-4)>
In Production Example 1, the same procedure as in Production Example 1 was carried out except that 14.4 parts of glycerin, 163 parts of ethylene oxide, and 323 parts of propylene oxide were used, and the EO-PO random adduct of glycerin of the present invention ( A-4) (f = 3; m = 19.8; n = 7.9; k = 11.9; n / (n + k) = 0.40; number average molecular weight 3,200; HLB = 10.0) Got.

Production Example 5 <Manufacture of EO-PO random adduct (A-5) of trimethylolpropane>
In Production Example 1, the same operation as in Production Example 1 was performed except that glycerol was changed to 23.9 parts of trimethylolpropane, ethylene oxide was changed to 238 parts, and propylene oxide was changed to 238 parts. -PO random adduct (A-5) (f = 3; m = 17.8; n = 10.1; k = 7.7; n / (n + k) = 0.57; number average molecular weight 2,800; HLB = 12.3) was obtained.

Production Example 6 <Production of Pentaerythritol EO-PO Random Additive (A-6)>
In Production Example 1, except that glycerin was changed to 18.4 parts of pentaerythritol, ethylene oxide was changed to 241 parts, and propylene oxide was changed to 241 parts, EO of pentaerythritol of the present invention was performed. -PO random adduct (A-6) (f = 4; m = 17.8; n = 10.1; k = 7.7; n / (n + k) = 0.57; number average molecular weight 3,700; HLB = 12.5) was obtained.

Production Example 7 <Production of sorbitol EO-PO random adduct (A-7)>
The same operation as in Production Example 1 was performed except that glycerin was changed to 16.6 parts sorbitol, ethylene oxide was 242 parts, and propylene oxide was 242 parts in Production Example 1, and the sorbitol EO-PO of the present invention was used. Random adduct (A-7) (f = 6; m = 17.7; n = 10.1; k = 7.6; n / (n + k) = 0.57; number average molecular weight 5,500; HLB = 12.7) was obtained.

Production Example 8 <Production of glycerin EO-PO block adduct (A-8)>
A stainless steel pressure reactor was charged with 267 parts of glycerin ethylene oxide addition polymer (number average molecular weight; 620) and 0.05 parts of sodium hydroxide, and after nitrogen substitution, about 228 parts of propylene oxide at 120 to 140 ° C. Press fit in time.
EO-PO block adduct of glycerin of the present invention (A-8) (f = 3; m = 7.0; n = 4.0; k = 3.0; n / (N + k) = 0.57; number average molecular weight 1,150; HLB = 14.1).

Production Example 9 <Production of EO-PO block adduct (A-9) of glycerin>
A pressure reactor made of stainless steel was charged with 74.5 parts of glycerin ethylene oxide addition polymer (number average molecular weight; 600) and 0.05 part of sodium hydroxide, and after substitution with nitrogen, 423 parts of propylene oxide was added at 120 to 140 ° C. Press-fitting was performed in about 4 hours.
EO-PO block adduct of glycerin of the present invention (A-9) (f = 3; m = 21.6; n = 3.8; k = 17.8; n / (N + k) = 0.18; number average molecular weight 3,700; HLB = 7.0).

Production Example 10 <Production of Pentaerythritol EO-PO Block Adduct (A-10)>
A stainless steel pressure reactor was charged with 244 parts of a propylene oxide addition polymer of pentaerythritol (number average molecular weight; 830) and 0.05 part of sodium hydroxide, and after nitrogen substitution, about 256 parts of ethylene oxide was added at 120 to 140 ° C. Press fit in 4 hours.
An additional EO-PO block adduct of pentaerythritol of the present invention (A-10) (f = 4; m = 7.9; n = 4.9; k = 3.0; n /(N+k)=0.62; number average molecular weight 1,700; HLB = 14.4).

Production Example 11 <Production of glycerin PO adduct (A-11)>
A stainless steel pressure reactor was charged with 46.0 parts of glycerin and 0.05 part of sodium hydroxide. After purging with nitrogen, 454 parts of propylene oxide were injected at 120 to 140 ° C. in about 4 hours.
By reacting for 10 hours at the same temperature, PO adduct of glycerin of the present invention (A-10) (f = 3; m = 5.2; n = 0; k = 5.2; n / (n + k) = 0 A number average molecular weight of 1,000; HLB = 7.4).

Production Example 12 <Production of EO-PO adduct (C-1) of propylene glycol>
A stainless steel pressure reactor is charged with 448 parts of a propylene oxide addition polymer of propylene glycol (number average molecular weight; 1,700) and 0.05 part of sodium hydroxide, and after nitrogen substitution, 52 parts of ethylene oxide at 120 to 140 ° C. Was pressed in about 4 hours.
The mixture was further reacted at the same temperature for 10 hours to obtain an EO-PO adduct (C-1) (HLB = 6.7) of propylene glycol of the present invention.

Production Example 13 <Production of Stearylamine EO-PO Random Adduct (C-2)>
A stainless steel pressure reactor was charged with 234 parts of stearylamine and 0.05 parts of sodium hydroxide. After purging with nitrogen, a mixed solution of 115 parts of ethylene oxide and 151 parts of propylene oxide was injected at 70 to 90 ° C. in about 4 hours. .
The mixture was further reacted at the same temperature for 10 hours to obtain an EO-PO random adduct (C-2) (HLB = 8.1) of stearylamine of the present invention.

Production Example 14 <Production of EO-PO random adduct (A'-1) of diethylene glycol>
Except that glycerin was replaced with 53 parts of diethylene glycol, 218 parts of ethylene oxide and 230 parts of propylene oxide were used, the same operation as in Production Example 1 was carried out, and an EO-PO random adduct of diethylene glycol for comparison (A′- 1) (f = 2; m = 8.9; n = 4.9; k = 4.0; n / (n + k) = 0.55; number average molecular weight 1,000; HLB = 12.8) It was.

Production Example 15 <Production of glycerin EO adduct (A'-3)>
A stainless steel pressure reactor was charged with 33 parts of glycerin and 0.05 part of sodium hydroxide, and after nitrogen substitution, 469 parts of ethylene oxide was injected at 120 to 140 ° C. in about 4 hours.
EO adduct of glycerin (A′-3) for comparison at the same temperature for another 10 hours (f = 3; m = 9.9; n = 9.9; k = 0; n / (n + k) = 1.00; number average molecular weight 1,400; HLB = 20.4).

Production Example 16 <Production of glycerin PO adduct (A'-4)>
A stainless steel pressure reactor was charged with 25.5 parts of glycerin and 0.05 part of sodium hydroxide, and after nitrogen substitution, 474 parts of propylene oxide was injected at 120 to 140 ° C. in about 4 hours.
The reaction was carried out at the same temperature for another 10 hours, and the PO adduct of glycerin (A′-4) for comparison (f = 3; m = 9.8; n = 0; k = 9.8; n / (n + k) = 0; number average molecular weight 1,800; HLB = 5.8).

Production Example 17 <Production of EO-PO random adduct (A'-5) of glycerin>
A EO-PO random adduct of glycerin for comparison (A′-5) was prepared in the same manner as in Production Example 1 except that 0.87 part of glycerin, 326 parts of ethylene oxide and 173 parts of propylene oxide were used. ) (F = 3; m = 365; n = 260; k = 105; n / (n + k) = 0.72; number average molecular weight 52,700; HLB = 13.9).

Production Example 18 <Production of Triethanolamine EO-PO Adduct (A'-7)>
A stainless steel pressure reactor was charged with 37.3 parts of triethanolamine and 0.05 parts of sodium hydroxide. After purging with nitrogen, a mixture of 114 parts of ethylene oxide and 349 parts of propylene oxide was added at 120 to 140 ° C. for about 4 hours. Press-fitted with.
The mixture was further reacted at the same temperature for 10 hours to obtain an EO-PO adduct (A′-7) (number average molecular weight 2,000) of triethanolamine for comparison.

Examples 1 to 11 and Comparative Examples 1 to 7
Each component was blended in the blending ratio (parts by weight) shown in Table 1, and the cutting fluids of Examples 1 to 11 and Comparative Examples 1 to 7 were prepared to obtain permeability, reaction suppression, foam suppression, and silicon wafer. The flatness was evaluated for performance.

In Table 1, “PEG-6000 (A′-2)” used was PEG-6000 (polyoxyethylene glycol having a number average molecular weight of 6,000) manufactured by Sanyo Chemical Industries.

The specific heat of the cutting fluids of Examples 1 to 11 and Comparative Examples 1 to 7 was measured. Moreover, the following method evaluated the permeability, reaction suppression property, foam suppression property, and the flatness of the silicon wafer.

<Measurement of specific heat>
The specific heat at 25 ° C. of the cutting fluid was measured using a differential scanning calorimeter (manufactured by Perkin Elmer). The results are shown in Table 1.

<Evaluation of permeability>
The permeability was evaluated by the following method.
(1) Grooves with a width of 0.2 mm, a length of 25 mm, and a depth of 5 mm are formed on a 25 mm square polycrystalline silicon ingot using a diamond fixed abrasive wire and a single wire saw cutting machine (manufactured by SOUTH BAY TECHNOLOGY). A test piece was obtained.
(2) With this test piece fixed so that the length direction of the groove was horizontal, a drop of the dropper (0.02 g) was attached to the end of the groove.
(3) After the cutting fluid was attached to the groove, the time required for the cutting fluid to reach the end of the opposite groove attached by capillary action was recorded.

The permeability was evaluated according to the following criteria.
◎: Less than 10 seconds ○: More than 10 seconds to less than 15 seconds △: More than 15 seconds to less than 20 seconds ×: More than 20 seconds

<Evaluation of reaction inhibition by hydrogen generation amount>
The evaluation of the suppression of hydrogen generation by the reaction between water and silicon was carried out by the following method.
(1) 20 g of silicon powder (manufactured by High Purity Chemical Laboratories; particle size of 1 μm or less) assuming silicon ingot chips is mixed in 80 g of cutting fluid, and stirred and dispersed for 1 minute at 3000 rpm using a disperser. A cutting fluid containing silicon powder was obtained.
(2) The mouth of the glass sample bottle containing the cutting fluid containing silicon powder prepared above was sealed with a rubber stopper through a glass tube, filled with water, and turned upside down into a water tank. The other end of the glass tube was introduced into the cylinder, and the generated hydrogen gas was set to replace the water inside the graduated cylinder.
(3) A series of sample bottles containing these water tanks, graduated cylinders, glass tubes and slurries are allowed to stand in a constant temperature and high temperature tank at 60 ° C. for 2 hours, and the hydrogen generated during this period is measured with a water displacement method. The amount of hydrogen generation was measured by collecting in a cylinder.

The evaluation of reaction inhibition was performed according to the following criteria.
○: Hydrogen gas generation amount is less than 4 mL △: Hydrogen gas generation amount is 4 mL or more to less than 8 mL ×: Hydrogen gas generation amount is 8 mL or more

<Evaluation of foam suppression>
The evaluation of foam suppression was performed by the following method.
(1) 40 mL of cutting fluid was put into a 100 mL measuring cylinder with a stopper having an inner diameter of 3 cm, and the distance (liquid level height) from the bottom of the measuring cylinder to the liquid level was recorded.
(2) The graduated cylinder containing the cutting fluid was shaken 40 times in 10 seconds.
(3) Immediately after shaking, the distance from the bottom of the graduated cylinder to the highest bubble surface (bubble surface height) was measured, and the difference between the bubble surface height and the liquid surface height was recorded.

The evaluation of foam suppression was performed according to the following criteria.
◎: Less than 7 mm ○: 7 mm or more to less than 20 mm Δ: 20 mm or more to less than 35 mm x: 35 mm or more

<Flatness of silicon wafer>
Evaluation of the flatness of the silicon wafer was performed by the following method.
(1) Using a polycrystalline silicon cylindrical pellet having a diameter of 25 mm as a material to be cut, a cutting test was carried out with a diamond fixed abrasive wire and a single wire saw cutting machine (manufactured by SOUTH BAY TECHNOLOGY).
Cutting conditions: coolant flow rate 2 ml / min, average wire travel speed 20 m / min, wire reciprocation 400 times / min, wire usage 0.1 m
(2) The wafer surface roughness (Ra) after cutting was measured using a laser scanning microscope (VK-8710, manufactured by Keyence Corporation).

The flatness of the silicon wafer was evaluated according to the following criteria.
◎: Ra is less than 0.1 μm ○: Ra is 0.1 μm or more to less than 0.2 μm Δ: Ra is 0.2 μm or more to less than 0.3 μm ×: Ra is 0.3 μm or more

As is clear from the results in Table 1, all of the cutting fluids of the present invention of Examples 1 to 11 have specific heat close to 4.2 of water, permeability, reaction suppression, foam suppression, and flatness of silicon wafers. Excellent in both properties.
On the other hand, Comparative Example 1 using a polyoxyalkylene adduct of a compound having two hydroxyl groups has insufficient foam suppression.
Comparative Example 2 using a polyoxyalkylene adduct of a compound having two hydroxyl groups, and Comparative Example 3 using a polyoxyalkylene adduct having an HLB of more than 20 are penetrability, reaction inhibition, foam suppression, All of the flatness of the silicon wafer is inferior. On the other hand, Comparative Example 4 having an HLB of less than 6.0 does not dissolve in water.
In Comparative Example 5 using a polyoxyalkylene compound having an average added mole number of m exceeding 350, the permeability, the foam-suppressing property, and the flatness of the silicon wafer are insufficient.
Comparative Example 6 using propylene glycol, which is a divalent alcohol, is inferior in permeability, reaction suppression and flatness of the silicon wafer.
Comparative Example 7 using a polyoxyalkylene compound obtained by adding alkylene oxide to triethanolamine instead of polyhydric alcohol has insufficient reaction suppression, foam suppression and flatness of the silicon wafer.

The water-containing cutting fluid for slicing silicon ingot of the present invention is excellent in cooling of processing heat, penetrability, water-silicon reaction suppression, foam suppression, and silicon wafer flatness. It is useful as a cutting fluid used when slicing an ingot.
Silicon wafers manufactured by cutting a silicon ingot using the water-containing cutting fluid for slicing silicon ingots of the present invention include, for example, solar cell, memory element, oscillation element, amplification element, transistor, diode, LSI electronic material These electronic materials can be used for solar power generation devices, personal computers, mobile phones, displays, audios, and the like.
Further, the water-containing cutting fluid for silicon ingot slicing of the present invention is excellent in cooling and penetrability of processing heat, so that it is used when cutting hard materials such as quartz, silicon carbide, sapphire, etc. in addition to silicon ingot. It is also useful as a liquid.

Claims

A polyoxyalkylene adduct (A) of the compound (a) having 3 to 8 hydroxyl groups represented by the following general formula (1) and water as essential components, the polyoxyalkylene adduct (A) A water-containing cutting fluid for slicing silicon ingot, characterized by having an HLB of 6.0 to 20.0.

[In the formula (1), R represents a residue obtained by removing a hydroxyl group from a compound having 3 to 8 hydroxyl groups, and (A 1 O) represents an oxyalkylene group having 2 to 4 carbon atoms. m represents the average number of moles of alkylene oxide having 2 to 4 carbon atoms and represents a number of 1 to 350, and f is an integer of 3 to 8. ]
The hydrous cutting fluid for silicon ingot slice according to claim 1, wherein-(A 1 O) m -in the polyoxyalkylene adduct (A) is represented by the following general formula (2).

Wherein (2), A 2 O is an oxyethylene group, A 3 O represents an oxypropylene group. n represents the average number of moles of ethylene oxide added and represents a number of 1 to 250, k represents the average number of moles of propylene oxide added and represents a number of 1 to 100, and n / (n + k) is 0.1 to 0.9. When ethylene oxide and propylene oxide are used in combination, the addition form may be random or block. ]
The water-containing cutting fluid for silicon ingot slice according to claim 1 or 2, wherein n / (n + k) in the polyoxyalkylene adduct (A) is 0.4 to 0.7.
The water-containing cutting fluid for silicon ingot slice according to any one of claims 1 to 3, wherein the polyoxyalkylene adduct (A) has a number average molecular weight of 400 to 10,000.
The hydrous cutting fluid for silicon ingot slice according to any one of claims 1 to 4, wherein the polyoxyalkylene adduct (A) has an HLB of 10.0 to 18.5.
The polyoxyalkylene adduct (A) is a polyoxyalkylene adduct of a compound having one or more 3 to 6 hydroxyl groups selected from the group consisting of glycerin, trimethylolpropane, pentaerythritol and sorbitol. 6. A water-containing cutting fluid for slicing silicon ingots according to any one of 1 to 5.
The water-containing cutting fluid for silicon ingot slices according to any one of claims 1 to 6, wherein the content of the polyoxyalkylene adduct (A) in the cutting fluid when used is 0.1 to 40% by weight.
The silicon ingot slice according to any one of claims 1 to 7, further comprising a monovalent or divalent linear or branched aliphatic carboxylic acid (B) having 8 or 9 carbon atoms including a carbon atom of a carbonyl group. Water-containing cutting fluid.
The water-containing cutting fluid for silicon ingot slices according to any one of claims 1 to 8, further comprising a nonionic surfactant (C) having an HLB of 6.0 to 8.5.
A method for slicing a silicon ingot using the wire saw for fixed abrasive grains in which the water-containing cutting fluid for slicing silicon ingots and abrasive grains according to any one of claims 1 to 9 are fixed to a wire.
A method for producing a silicon wafer, comprising slicing a silicon ingot using the water-containing cutting fluid for slicing silicon ingot according to any one of claims 1 to 9 and a fixed abrasive wire saw in which abrasive particles are fixed to a wire.
A silicon wafer produced by slicing a silicon ingot by the production method according to claim 11.
An electronic material manufactured using the silicon wafer according to claim 12.
A solar battery cell manufactured using the silicon wafer according to claim 12.