KR20130095724A - Aqueous processing solution for fixed abrasive grain wire saw - Google Patents

Abstract

According to the water-soluble processing liquid for fixed abrasive wire containing at least 1 type or more water-soluble polymer chosen from the copolymer containing (A) polyvinylpyrrolidone, and vinylpyrrolidone of this invention, and (B) water, The thickening of the processing liquid into which the chip is mixed can be suppressed, the reaction between the processing liquid and the chip can be suppressed to suppress the generation of hydrogen, and the thickening and gelation of the processing liquid into which the chip is mixed can be suppressed.

Description

Aqueous processing liquid for fixed abrasive wire use {AQUEOUS PROCESSING SOLUTION FOR FIXED ABRASIVE GRAIN WIRE SAW}

TECHNICAL FIELD This invention relates to the water-soluble process liquid for fixed abrasive wire saws, and relates to the water-soluble process liquid for fixed abrasive wire saws used when cut | disconnecting a silicon wafer with a fixed abrasive wire saw in detail.

In order to reduce the manufacturing cost of a silicon wafer, improvement of the cutting process technology of a silicon wafer becomes important. In the processing of a silicon wafer, although the cutting by the wire saw in a glass abrasive grain type | system | group is the mainstream, there exist the following various problems in the process of the said glass abrasive grain type | system | group.

(1) As a processing liquid, since the slurry which disperse | distributed the abrasive grain to oil was used, it is difficult to isolate | separate a glass abrasive grain and cutting chips. (2) There is a limitation in improving the processing efficiency because there is a limitation in the wire traveling speed. (3) When the wire is thinned so as to reduce the kerf-loss, disconnection occurs during processing and the yield decreases. (4) In the case where the abrasive grains are atomized in order to reduce the cutting loss, problems of adverse effects have been pointed out such that the slurry viscosity increases and the cutting loss is increased.

In response to such a problem, a fixed abrasive wire saw in which diamond abrasive grains are fixed to electrode surfaces such as piano wires by electrodeposition, resin bond, or the like has been recently developed (Patent Document 1). When a brittle material is processed using a fixed abrasive wire saw, a processing liquid is used for the purpose of lubricating, cooling, and dispersing cut debris. As said processing liquid, when a flammability problem etc. are also considered, it is preferable to use a water-soluble processing liquid. However, when the workpiece is silicon, the reactivity between the chip and the processing liquid is higher than that of the general material, and the silicon chips (chip) may react with moisture or alkali in the processing liquid to generate hydrogen and ignite. Therefore, it is preferable that it is a process liquid which suppressed the reactivity with silicone. From this viewpoint, the process liquid as disclosed in patent document 2 is proposed.

Japanese Patent Application No. 2001-054850 Japanese Patent Application No. 2003-082334

However, it has been found that chips have become finer by improving processing accuracy in recent years, and sufficient stability cannot be obtained in the processing liquid as disclosed in Patent Document 2. In particular, it has been found that the viscosity of the processing liquid into which the chips are mixed increases, causing various problems. In addition, in the case of the processing liquid containing a large amount of water and having a pH of alkaline, not only the problem of generating hydrogen but also the problem of thickening and gelation occurred.

Thickening and gelation of the processing liquid cause the following problems.

(1) The introduction flow volume carried in by a wire changes, and thickness fluctuation becomes large (deterioration of product quality).

(2) Wire slip occurs and the wire is disconnected (decrease in yield).

(3) It becomes difficult to wash | clean in a subsequent process (it is difficult to remove the chip | tip and oil agent between wafers).

(4) The oil life is short, and the amount of fluid is increased (cost increases).

Therefore, in the present invention, the thickening of the processing liquid into which the chip is mixed can be suppressed, the reaction between the processing liquid and the chip can be suppressed to suppress the generation of hydrogen, and further the thickening and gelation of the processing liquid can be suppressed. It is a subject to provide the water-soluble processing liquid for fixed abrasive grain wire use.

MEANS TO SOLVE THE PROBLEM In order to solve the above problem, the present inventors earnestly examined and found the following matter.

(1) The increase in viscosity due to the mixing of Si chips occurs because the Si chips to be mixed are fine powders and the dispersibility of the Si chips is inferior.

(2) The increase in viscosity can be solved by containing a predetermined water-soluble polymer in the processing liquid and improving the dispersibility of the Si chip.

(3) When a Si chip is contained in a process liquid, Si chip and a process liquid may react, and hydrogen may generate | occur | produce.

(4) In the case of a processing liquid containing a large amount of water, thickening and gelation may occur by containing Si chips.

(5) The problems of (3) and (4) can be solved by containing a predetermined water-soluble polymer in the processing liquid.

MEANS TO SOLVE THE PROBLEM The present inventors earnestly examined the said problem, and came to complete the following invention.

1st this invention is water-soluble processing liquid for fixed abrasive wire containing at least 1 sort (s) or more water-soluble polymer chosen from the copolymer containing (A) polyvinylpyrrolidone and vinylpyrrolidone, and (B) water. (Hereinafter, it may be called "the processing liquid of this invention.").

When the processing liquid of the present invention contains a predetermined water-soluble polymer as the component (A), when the processing liquid contains silicon powder, the dispersibility of the silicon powder can be improved, and the viscosity of the processing liquid containing the silicon powder is increased. Can be suppressed. In addition, while the processing liquid and the silicon powder react with each other to suppress the generation of hydrogen, the thickening and gelation of the processing liquid containing the silicon powder can be suppressed.

In 1st this invention, it is preferable that the weight average molecular weights of the said (A) component are 2,000-1,000,000.

In 1st this invention, it is preferable to make content of the said (A) component into the mass of the whole water-soluble process liquid for fixed abrasive wires 100 mass%, and to set it as 0.02 mass% or more and 7 mass% or less.

It is preferable that the water-soluble process liquid for fixed abrasive wire strips of 1st this invention further contains the alkali salt of (C) polyhydric carboxylic acid. It is preferable that content of the said (C) component makes the mass of the whole water-soluble processing liquid for fixed abrasive wires small 100 mass%, and is 0.01 mass% or more and 10 mass% or less. The processing liquid of the present invention can easily impart dispersibility, detergency, and corrosion resistance by containing an alkali salt of a polyvalent carboxylic acid as the component (C).

It is preferable that the water-soluble process liquid for fixed abrasive wire use of 1st this invention further contains 1 or more types chosen from the group which consists of (D) glycols, glycol ethers, and polyoxyalkylene glycols. It is preferable that content of the said (D) component makes 0.1 mass% or more and 95 mass% or less the mass of the whole water-soluble processing liquid for fixed abrasive wires as 100 mass%.

It is preferable that the viscosity of the water-soluble process liquid for fixed abrasive wires of 1st this invention is 50 mPa * s or less at 25 degreeC. When the viscosity of the processing liquid itself is high, the viscosity of the processing liquid containing silicon powder becomes higher. Therefore, it is preferable that the viscosity of process liquid itself is below a predetermined value.

The viscosity of the processing liquid (pseudo-use liquid) formed by adding 10 mass% of silicon powder having an average particle diameter of 1.5 µm to the water-soluble processing liquid for fixed abrasive wire for use according to the first aspect of the invention and stirring it is 100 mPa · s or less at 25 ° C. desirable. When the viscosity of the pseudo-use liquid containing a predetermined | prescribed silicone powder is high, there exists a possibility that the various problems described in the column of the said subject may arise.

According to the water-soluble processing liquid for fixed abrasive wire use of this invention, since it contains a predetermined water-soluble polymer, when the processing liquid contains the silicon powder which is a silicon chip, the said silicon powder can be disperse | distributed in a processing liquid. Therefore, the viscosity rise of the processing liquid containing a silicon powder can be suppressed. In addition, since the processing liquid of the present invention contains a predetermined water-soluble polymer, it is possible to suppress the reaction between the silicon powder and the processing liquid to generate hydrogen, and to suppress the thickening and gelation of the processing liquid containing the silicon powder. Can be.

<Water-soluble processing liquid for fixed abrasive wire use>

The water-soluble processing liquid for fixed abrasive wire strips of this invention contains at least 1 type or more water-soluble polymer chosen from the copolymer containing (A) polyvinylpyrrolidone, and vinylpyrrolidone, and (B) water. .

(Component (A))

The processing liquid of the present invention contains at least one or more water-soluble polymers selected from copolymers containing polyvinylpyrrolidone and vinylpyrrolidone as the component (A). By containing this water-soluble polymer in a processing liquid, the dispersibility of the said silicon powder can be improved in the processing liquid containing a silicon powder. Therefore, the raise of the viscosity of the processing liquid containing a silicon powder can be suppressed. Moreover, reaction of a silicon powder and a processing liquid can be suppressed, and generation | occurrence | production of hydrogen in the processing liquid containing a silicon powder can be suppressed. Moreover, the thickening and gelatinization of the processing liquid containing a silicon powder can be suppressed.

The weight average molecular weight of the water-soluble polymer of the component (A) by gel permeation chromatography / multi-angle laser light scattering detector method is preferably at least 2,000, more preferably at least 8,000, and preferably at most 1,000,000, Preferably it is 700,000 or less, More preferably, it is 500,000 or less. If the molecular weight is too small out of the above range, the effect of adding the component (A) may not be expressed. On the contrary, if the molecular weight is too large, the aggregation or the viscosity of the processing liquid may be too high.

As for content of (A) component, the lower limit becomes like this. Preferably it is 0.02 mass% or more, More preferably, 0.05 mass% or more, More preferably, the mass of the whole water-soluble processing liquid for fixed abrasive wires is a reference | standard (100 mass%). Is 0.2 mass% or more, and an upper limit becomes like this. Preferably it is 7 mass% or less, More preferably, it is 5 mass% or less, More preferably, it is 3 mass% or less. If the content of the component (A) is too small outside the above range, the effect of inhibiting thickening and the effect of inhibiting hydrogen generation may become insufficient. On the contrary, when too large, the viscosity of the processing liquid may increase.

The water-soluble polymer of (A) component is a copolymer containing polyvinylpyrrolidone or vinylpyrrolidone, These can also be used in mixture of 2 or more type. In the copolymer containing vinylpyrrolidone, the proportion of vinylpyrrolidone units is preferably 60 mol% or more based on the entire copolymer. Vinyl acetate is mentioned as a monomer copolymerized with vinylpyrrolidone.

((C) component)

The process liquid of this invention may further contain the alkali salt of polyhydric carboxylic acid as (C) component. By adding (C) component and adjusting the addition amount, it has the effect of providing dispersibility, washability, and corrosion resistance.

As polyhydric carboxylic acid, adipic acid, oxalic acid, dodecanedioic acid, citric acid, malic acid, etc. are mentioned. Examples of the alkali include amines such as hydroxides of alkali metals such as potassium hydroxide and sodium hydroxide, triethanolamine, triisopropanolamine, ethylenediamine, and N- (2-aminoethyl) -2-aminoethanol.

As for content of (C) component, the lower limit becomes like this. Preferably it is 0.01 mass% or more, More preferably, it is 0.1 mass% or more, and an upper limit is preferable based on the mass of the whole process liquid of this invention as a reference | standard (100 mass%). Is 10 mass% or less, More preferably, it is 2 mass% or less, More preferably, it is 1 mass% or less. If the content of the component (C) is too small outside the above range, the effect of adding the component (C) is hardly exerted. On the contrary, if the content is too large, thickening, gelation or precipitation from the stock solution may occur.

(Component (D))

The processing liquid of the present invention may further contain one or more selected from the group consisting of glycols, glycol ethers, and polyoxyalkylene glycols as the component (D). By containing (D) component, there exists an effect of providing lubricity and wettability.

Examples of the glycols include propylene glycol, diethylene glycol, ethylene glycol, butylene glycol, and the like. Examples of the glycol ethers include alkyl ethers of the above glycols, and examples of the alkyl group include a methyl group, an ethyl group, and a butyl group. In addition, a part of the hydroxyl groups of glycols may be alkyl ether, and all may be alkyl ether. As an example of glycol ethers, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, propylene glycol monoethyl ether, etc. are mentioned.

Examples of the polyoxyalkylene glycols include polyethylene glycol, polypropylene glycol, copolymers of polyoxyethylene and polyoxypropylene, and the weight average molecular weight (polystyrene conversion using gel permeation chromatography) is preferably 10000 or less. More preferably, it is 5000 or less, More preferably, it is 400 or less.

As for content of (D) component, as a reference | standard (100 mass%) the mass of the whole process liquid of this invention, a minimum is preferably 0.1 mass% or more, More preferably, it is 0.5 mass% or more, More preferably, 1 It is mass% or more, More preferably, it is 3 mass% or more, Especially preferably, it is 10 mass% or more, An upper limit becomes like this. Preferably it is 95 mass% or less, More preferably, it is 90 mass% or less, More preferably, it is 80 mass% or less to be. If the content of the component (D) is too small outside the above range, the effect of adding the component (D) will not be expressed. On the contrary, if the content of the component (D) is too large, the cooling property may be lowered.

The processing liquid of the present invention contains the above-mentioned (A) component, and optionally contains (C) component and (D) component, and remainder becomes (B) water. As water, the kind, such as distilled water and tap water, is not specifically limited. Moreover, in the processing liquid with much content of (B) water, the processing liquid containing a silicon powder thickens and gelatinizes easily. In contrast, in the processing liquid of the present invention, thickening and gelation of the processing liquid containing silicon powder are prevented even in a composition having a large amount of water, for example, a composition in which water is 90% by mass or more based on the mass of the entire processing liquid. It can be suppressed.

<Appearance of Processing Amount>

The viscosity of the processing liquid of the present invention is preferably 50 mPa · s or less at 25 ° C., more preferably 25 mPa · s or less, still more preferably 20 mPa · s or less. Moreover, the viscosity of the processing liquid (pseudo-use liquid) in which the predetermined | prescribed silicone powder was disperse | distributed to the processing liquid of this invention is 100 mPa * s at 25 degreeC, Preferably it is 55 mPa * s or less, More preferably, it is 50 mPa * s It is below, More preferably, it is 45 mPa * s or less. As for the viscosity of the said pseudo-use liquid, 10 mass% of silicon powder (particle diameter: 1.5 micrometers) is added to the process liquid of this invention, after stirring-mixing, stainless steel balls (diameter 2 mm) are put, and it stirs at 1000 rpm for 10 hours. In addition, it measures about the pseudo-use liquid obtained by filtering and filtering the said stainless steel ball. If the viscosity of the above-mentioned processing liquid itself is too high, the viscosity of the pseudo-use liquid containing the silicon powder also inevitably increases. Moreover, when the viscosity of a pseudo use liquid is too high, there exists a possibility that the various problems described in the column of the said subject may arise. In addition, the viscosity of a process liquid and pseudo use liquid can be measured with a Brookfield viscometer.

The pH of the processing liquid is preferably 5.0 or more and 9.0 or less. If the pH of the processing liquid is too low, there is a risk of corrosion of the steel or wire to which the processing liquid contacts. Conversely, if the pH of the processing liquid is too high, the processing liquid and the silicon powder may react to generate hydrogen. have. Although the processing liquid of this invention can also be diluted and used in water, also in this case, it is preferable that the pH of the processing liquid after dilution is in the said range.

[Example]

<Examples 1 to 13, Comparative Examples 1 to 5>

The water-soluble processing liquid for fixed abrasive wire wire (Examples 1-13) of this invention, and the water-soluble processing liquid for fixed abrasive wire wire (Comparative Examples 1-5) other than this invention were produced so that it might become a composition as shown in Tables 1-3. . While measuring the pH of the produced process liquid, the viscosity in 25 degreeC was measured with the Brookfield viscometer.

Furthermore, 10 mass% of silicon powder (average particle system 1.5 m) was added to each process liquid, and after stirring and mixing, stainless steel balls (diameter 2 mm) were put, and it stirred at 1000 rpm for 10 hours, and formed the pseudo use liquid. . The stainless steel balls were separated by filtration using a wire mesh (50 mesh) from the pseudo use liquid, and the viscosity (mPa · s, 25 ° C.) of the pseudo use liquid was measured by a Brookfield viscometer. Furthermore, 10 ml of pseudo-use liquids were heated to 50 degreeC, and the amount of hydrogen (ml) generate | occur | produced in 30 minutes was measured.

In addition, the weight average molecular weight of polyvinylpyrrolidone (PVP) was 9700 for PVP K-15, 70000 for PVP K-30, and 400000 for PVP K-60. Moreover, PVP / VA is a copolymer of vinylpyrrolidone and vinyl acetate, the weight average molecular weight is 32,000 and the ratio of the vinylpyrrolidone in a copolymer is 70 mol%.

In the processing liquid of the comparative example, the pseudo-use liquid viscosity rose all and exceeded 55 mPa * s. On the other hand, the process liquid (Examples 1-13) of this invention is small in viscosity change also in pseudo use liquid, and all are 45 mPa * s or less.

In Examples 1 to 3 and Comparative Examples 1 and 2, the stock solution was diluted 10 times. Therefore, the composition of the stock solution is 10 times each compound.

(Group I)

Group I is Examples 1-6 and Comparative Examples 1-3, and is an example of the processing liquid with a large amount of moisture. Although the compositions (Comparative Examples 1 to 3), which were the processing liquids of the comparative examples and had a large amount of moisture, were all thickened and gelled, the processing liquids (Examples 1 to 6) of the present invention to which PVP was added were not gelled and hardly thickened. .

In addition, about the hydrogen generation amount, in Examples 1-6, hydrogen generation was 5 ml or less, whereas in Comparative Examples 1-3, the hydrogen generation amount was 15 ml or more.

(Group II)

Groups II are Examples 7 to 12 and Comparative Example 4, in which the kind and amount of the component (C) and the component (D) were unified and changed with respect to the component (A). From this, the thickening inhibitory effect of various polyvinylpyrrolidone (PVP) and vinylpyrrolidone / vinyl acetate copolymer (PVP / VA) was shown.

In addition, about the amount of hydrogen generation, compared with Examples 7-12 and the comparative example 4, the process liquid of this invention containing polyvinylpyrrolidone etc. had little hydrogen generation amount.

(Group III)

Group III is Example 13 and Comparative Example 5, and contains a component (D) different from Groups I and II. From this, the effect of the thickening suppression by polyvinylpyrrolidone (PVP) appeared regardless of the kind of (D) component.

In addition, when Example 13 was compared with Comparative Example 5, Example 13 containing polyvinylpyrrolidone had little hydrogen generation amount.

From the above, the processing liquid of the present invention containing at least one or more water-soluble polymers selected from polyvinylpyrrolidone and a copolymer containing vinylpyrrolidone has a viscosity increase in the pseudo-use liquid in which silicone powder is dispersed. It has been shown that there is an effect of suppressing the generation of hydrogen while suppressing.

As mentioned above, although this invention was demonstrated regarding embodiment which is considered most practical and desirable at this time, this invention is not limited to embodiment disclosed in this specification, and the summary of invention understood from a claim and the whole specification. Or it can be suitably changed in the range which does not contrary to an idea, and it should also be understood that the water-soluble processing liquid for fixed abrasive wire accompanying such a change is also included in the technical scope of this invention.

The water-soluble processing liquid for fixed abrasive wire saw of this invention can be used especially preferably when cut | disconnecting a silicon wafer using a fixed abrasive wire saw.

Claims (9)

A water-soluble process liquid for fixed abrasive wire saws containing (A) at least one or more water-soluble polymers selected from a copolymer comprising polyvinylpyrrolidone and vinylpyrrolidone, and (B) water. The water-soluble process liquid for fixed abrasive wires of Claim 1 whose weight average molecular weights of the said (A) component are 2,000-1,000,000. The water-soluble working solution for fixed abrasive wire firing according to claim 1 or 2, wherein the content of the component (A) is 0.02% by mass or more and 7% by mass or less as the mass of the whole water-soluble working solution for fixed abrasive wires is 100% by mass. . (C) The water-soluble process liquid for fixed abrasive wire use of any one of Claims 1-3 which further contains the alkali salt of polyhydric carboxylic acid. The water-soluble process liquid for fixed abrasive wire grades of Claim 4 whose content of the said (C) component is 0.01 mass% or more and 10 mass% or less as the mass of the whole water-soluble process liquid for fixed abrasive wires. The water-soluble processing for fixed abrasive wire use according to any one of claims 1 to 5, further comprising one or more selected from the group consisting of (D) glycols, glycol ethers, and polyoxyalkylene glycols. liquid. The water-soluble working solution for fixed abrasive wires according to claim 6, wherein the content of the component (D) is 0.1% by mass or more and 95% by mass or less as the mass of the whole water-soluble working solution for fixed abrasive wires is 100% by mass. The water-soluble process liquid for fixed abrasive wires of any one of Claims 1-7 whose viscosity of a process liquid is 50 mPa * s or less at 25 degreeC. The fixed abrasive grain as described in any one of Claims 1-8 whose viscosity of the pseudo-use liquid formed by adding 10 mass% of silicon powder with an average particle diameter of 1.5 micrometers to the said process liquid and stirring it is 100 mPa * s or less at 25 degreeC. Aqueous processing liquid for wire use.