Additive for processing water and processing method for processed material

Abstract

To reduce the degree of discoloration in an additive and reduce the amount of bubbles generated in the additive.SOLUTION: An additive for processing water to be added to processing water used when processing a metal-containing region of a workpiece with a processing tool contains an organic acid, an oxidizing agent, and a chelating agent, and the organic acid and the chelating agent contain different substances. The chelating agent has one or a combination of two or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and gluconic acid.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an additive for processing water added to the processing water and a method for processing a workpiece, in which a metal-containing region of the workpiece is processed with a processing tool.

Background Art

[0002] As semiconductor devices used in electronic devices such as mobile phones and personal computers (PCs), package devices such as QFN (Quad Flat Non-leaded package) are known. A package device is manufactured by forming a strip substrate by encapsulating a plurality of semiconductor device chips with resin and then dividing the strip substrate into individual semiconductor device chips using a cutting device (see, for example, Patent Document 1).

[0003] Since a plurality of metal terminals are exposed on the planned division line (i.e., street) of the strip substrate, when dividing the strip substrate, the plurality of metal terminals are cut with a cutting blade. However, since the metal terminals have ductility and malleability, metal burrs are generated during cutting.

[0004] Metal burrs lead to problems such as short circuits between terminals of the package device and poor bonding. Therefore, in order to reduce the amount of metal burrs, it has been studied to reduce the amount of metal burrs by supplying cutting water containing an organic acid and an oxidizing agent to the contact point (i.e., processing point) between the cutting blade and the strip substrate during cutting (see, for example, Patent Document 2).

[0005] When preparing cutting water containing an organic acid and an oxidizing agent, first, a liquid additive in which the organic acid and the oxidizing agent are mixed is prepared. After preparing the additive, the additive is added to pure water to prepare cutting water, and this cutting water is supplied to the processing point during cutting.

[0006] By the way, the additive may be stored for several days before being added to pure water. However, during this storage period, problems such as discoloration of the additive and generation of bubbles in the additive have occurred.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] The present invention has been made in view of such problems, and an object thereof is to reduce the degree of discoloration in the additive and to reduce the amount of bubbles generated in the additive.

Means for Solving the Problems

[0009] According to one aspect of the present invention, there is provided an additive for machining water to be added to machining water used when machining a metal-containing region of a workpiece with a machining tool, the additive for machining water including an organic acid, an oxidizing agent, and a chelating agent, wherein the organic acid and the chelating agent include different substances.

[0010] Preferably, the chelating agent has one or a combination of two or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and gluconic acid.

[0011] Preferably, the content of the chelating agent is 0.003 wt% or more and 1.333 wt% or less.

[0012] According to another aspect of the present invention, there is provided a method for machining a workpiece, which uses the machining water containing the above-described additive and pure water to machine a metal-containing region of the workpiece with a machining tool, the method including: a holding step of holding the workpiece on a holding table of a machining apparatus; and a machining step of machining the metal-containing region while supplying the machining water to a machining point where the machining tool and the workpiece are in contact with each other.

Advantages of the Invention

[0013] According to the applicant's intensive research, the additive contains trace amounts of metal ions and the like as impurities. Due to these impurities, it is presumed that a chemical reaction proceeds in one or both of the organic acid and the oxidizing agent, resulting in discoloration of the additive and generation of bubbles from the additive.

[0014] An additive for machining water according to one aspect of the present invention contains an organic acid, an oxidizing agent, and a chelating agent, and the organic acid and the chelating agent contain different substances from each other. The chelating agent can reduce the degree of discoloration in the additive and the amount of bubbles generated in the additive by inactivating the impurities.

[0015] In the method for machining a workpiece according to another aspect of the present invention, machining water containing the above-described additive and pure water is used. In the additive, the action of the chelating agent reduces the degree of discoloration and the amount of bubbles generated. That is, the consumption of the organic acid and the oxidizing agent due to the impurities is reduced.

[0016] Therefore, compared with the case where an additive not containing a chelating agent is used in machining water, the effective amounts of the organic acid and the oxidizing agent that act to reduce the ductility and malleability of the metal terminals in the workpiece can be increased. Thereby, the amount of burrs of the metal generated during machining of the workpiece can be reduced.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] With reference to the accompanying drawings, embodiments according to one aspect of the present invention will be described. FIG. 1 is a photograph of the additive 2 for the cutting water 6 (that is, the processing water; see FIG. 6(B)). The additive 2 shown in FIG. 1 contains an organic acid, a corrosion inhibitor, a chelating agent, and an oxidizing agent.

[0019] The additive 2 can be produced, for example, by mixing a first aqueous solution in which an organic acid, a corrosion inhibitor, and a chelating agent are dissolved in pure water and a second aqueous solution in which an oxidizing agent is dissolved in pure water at a predetermined ratio.

[0020] The weight ratio of the first aqueous solution (A) to the second aqueous solution (B) is, for example, 1 to 1 (A:B = 1:1), 1 to 2 (A:B = 1:2), 2 to 1 (A:B = 2:1), or 3 to 1 (A:B = 3:1), but is not limited to only these integer ratios.

[0021] FIG. 1 shows the state when the additive 2 is created by mixing an organic acid, an oxidizing agent, and a chelating agent, and then this additive 2 is placed in a self-standing test tube 4 and left at room temperature for 2 hours. In the photograph shown in FIG. 1, by tilting the test tube 4, the liquid surface 2a of the additive 2 appears elliptical. Droplets of the additive 2 adhere to the inner wall of the test tube 4 located above the liquid surface 2a.

[0022] As shown in Fig. 1, even when left standing at room temperature for 2 hours, Additive 2 did not change color, and no bubbles were generated in Additive 2. Further, even when Additive 2 was left standing at room temperature for 12 hours, there was no color change or bubble generation, and even when left standing at room temperature for 3 days, there was no color change or bubble generation.

[0023] In contrast, Fig. 2 is a photograph of Comparative Example Additive 12 that contains an organic acid and an oxidizing agent but does not contain a chelating agent. Fig. 2 shows the state when, after preparing Additive 12 by mixing an organic acid and an oxidizing agent, this Additive 12 was placed in a self-standing test tube 14 and left standing at room temperature for 2 hours.

[0024] In the photograph shown in Fig. 2, by tilting the test tube 14, the liquid surface 12a of Additive 12 appears elliptical. Droplets of Additive 12 are adhering to the inner wall of the test tube 14 located above the liquid surface 12a.

[0025] As shown in Fig. 2, even when left standing at room temperature for 2 hours, Additive 12 did not change color, but bubbles 12b already existed in the liquid of Additive 12. Further, even when left standing at room temperature for 12 hours, Additive 12 did not change color, but bubbles 12b existed in the liquid of Additive 12. When left standing at room temperature for 3 days, Additive 12 changed color, and bubbles 12b existed in the liquid of Additive 12.

[0026] According to the applicant's intensive research, Additive 12 contains trace amounts of metal ions and the like as impurities, and due to these impurities, a chemical reaction proceeds in one or both of the organic acid and the oxidizing agent, resulting in the color change of Additive 12 and the generation of bubbles 12b from Additive 12. It is presumed that this occurs.

[0027] The additive 2 for cutting fluid according to the present invention contains an organic acid, an oxidizing agent, and a chelating agent, and the organic acid and the chelating agent contain different substances from each other. It is considered that the chelating agent inactivates impurities such as metal ions, thereby reducing the degree of color change in Additive 2 and reducing the amount of bubbles 12b generated in Additive 2.

[0028] Organic acids have the effect of modifying metal materials to reduce the degree of ductility and malleability. As the organic acid, for example, a compound having at least one carboxyl group and at least one amino group in the molecule can be used. In this case, it is preferable that at least one of the amino groups is a secondary or tertiary amino group. Further, the compound used as the organic acid may have a substituent.

[0029] Examples of amino acids that can be used as organic acids include glycine, dihydroxyethylglycine, glycylglycine, hydroxyethylglycine, N-methylglycine, β-alanine, L-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-alloisoleucine, L-isoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-thyroxine, L-tyrosine, 3,5-diiodo-L-tyrosine, β-(3,4-dihydroxyphenyl)-L-alanine, 4-hydroxy-L-proline, L-cysteine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L-cysteic acid, L-glutamic acid, L-aspartic acid, S-(carboxymethyl)-L-cysteine, 4-aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-canavanine, L-citrulline, L-arginine, δ-hydroxy-L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, 3-methyl-L-histidine, L-tryptophan, actinomycin C1, ergothioneine, apamin, angiotensin I, angiotensin II, and antipain, etc. Among them, glycine, L-alanine, L-proline, L-histidine, L-lysine, and dihydroxyethylglycine are preferable.

[0030] Examples of aminopolyacids that can be used as organic acids include iminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, nitrilotris(methylenephosphonic acid), ethylenediamine-N,N,N’,N’-tetramethylenesulfonic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diamine tetraacetic acid, trans-cyclohexanediaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form), β-alanine diacetic acid, N-(2-carboxylateethyl)-L-aspartic acid, N,N’-bis(2-hydroxybenzyl)ethylenediamine-N,N’-diacetic acid, and the like.

[0031] Furthermore, examples of carboxylic acids that can be used as organic acids include saturated carboxylic acids such as formic acid, glycolic acid, propionic acid, acetic acid, butyric acid, valeric acid, hexanoic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, malic acid, succinic acid, tartaric acid, citric acid, pimelic acid, mercaptoacetic acid, glyoxylic acid, chloroacetic acid, pyruvic acid, acetoacetic acid, glutaric acid, and unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mesaconic acid, citraconic acid, aconitic acid, cyclic unsaturated carboxylic acids such as benzoic acids, toluic acids, phthalic acids, naphthoic acids, pyromellitic acid, naphthalic acid, and the like.

[0032] The organic acid may be in various forms such as a solid (e.g., powder), a liquid, an aqueous solution in which the solid is dissolved in a solvent, or a mixture in which the solid and the solvent are mixed. The content of the organic acid in Additive 2 is, for example, 0.667 wt% or more and 7.500 wt% or less (see Table 2 described later).

[0033] The oxidizing agent has the effect of reducing the degree of ductility and malleability of the metal by oxidizing the surface of the metal material, and making the workpiece 11 (see FIG. 3) in a state suitable for cutting when cutting the workpiece 11.

[0034] Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, dichromate, permanganate, cerate, vanadate, ozone water, silver (II) salt, iron (III) salt, and their complex salts, etc.

[0035] The oxidizing agent may be in various forms such as solid (e.g., powder), liquid, aqueous solution in which the solid is dissolved in a solvent, and mixture in which the solid and the solvent are mixed. The content of the oxidizing agent in Additive 2 is, for example, 8.750 wt% or more and 23.333 wt% or less (see Table 2).

[0036] The chelating agent has the effect of inactivating impurities such as metal ions contained in Additive 2. Therefore, by containing the chelating agent in Additive 2, the degree of discoloration in Additive 2 can be reduced, and the amount of bubbles 12b generated in Additive 2 can be reduced.

[0037] The chelating agent has one or a combination of two or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, gluconic acid, hydroxyethyliminodiacetic acid, dihydroxyethylglycine, glycol ether diamine tetraacetic acid, dicarboxymethylglutamic acid, ethylenediamine disuccinic acid (SS form), hydroxyethanediphosphonic acid, nitrilotris(methylenephosphonic acid), phosphonobutane tricarboxylic acid.

[0038] The content of the chelating agent in Additive 2 is preferably 0.003 wt% or more and 1.333 wt% or less (see Table 2). If the content of the chelating agent is less than 0.003 wt%, it may be difficult to reduce the discoloration and foaming of Additive 2.

[0039] On the other hand, when the content of the chelating agent exceeds 1.333 wt%, all of the chelating agent becomes difficult to dissolve in the solvent (for example, pure water), and the cost of Additive 2 increases (that is, the cost-effectiveness deteriorates). Also, when the content of the chelating agent exceeds 1.333 wt%, the metal terminals of the workpiece 11 may corrode.

[0040] However, the material that functions as an organic acid and the material that functions as a chelating agent in Additive 2 contain different substances from each other.

[0041] An anticorrosive agent may be mixed into Additive 2. By mixing an anticorrosive agent, corrosion (elution) of the metal terminals in the workpiece 11 can be prevented. As the anticorrosive agent, for example, it is preferable to use a heteroaromatic ring compound having three or more nitrogen atoms in the molecule and having a condensed ring structure, or a heteroaromatic ring compound having four or more nitrogen atoms in the molecule. Further, the aromatic ring compound preferably contains a carboxyl group, a sulfo group, a hydroxy group, or an alkoxy group. Specifically, a tetrazole derivative, a 1,2,3-triazole derivative, and a 1,2,4-triazole derivative are preferable.

[0042] Examples of the tetrazole derivative that can be used as the anticorrosive agent include those having no substituent on the nitrogen atom forming the tetrazole ring and having a substituent selected from the group consisting of a sulfo group, an amino group, a carbamoyl group, a carboxamide group, a sulfamoyl group, and a sulfonamide group, or an alkyl group substituted with at least one substituent selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carboxamide group, a sulfamoyl group, and a sulfonamide group introduced at the 5-position of tetrazole.

[0043] In addition, examples of 1,2,3-triazole derivatives that can be used as corrosion inhibitors include those having no substituent on the nitrogen atom forming the 1,2,3-triazole ring, and having a substituent selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carboxamide group, a sulfamoyl group, and a sulfonamide group at the 4-position and / or 5-position of 1,2,3-triazole, or those having an alkyl group or an aryl group substituted with at least one substituent selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carboxamide group, a sulfamoyl group, and a sulfonamide group introduced therein.

[0044] In addition, examples of 1,2,4-triazole derivatives that can be used as corrosion inhibitors include those having no substituent on the nitrogen atom forming the 1,2,4-triazole ring, and having a substituent selected from the group consisting of a sulfo group, a carbamoyl group, a carboxamide group, a sulfamoyl group, and a sulfonamide group at the 2-position and / or 5-position of 1,2,4-triazole, or those having an alkyl group or an aryl group substituted with at least one substituent selected from the group consisting of a hydroxy group, a carboxy group, a sulfo group, an amino group, a carbamoyl group, a carboxamide group, a sulfamoyl group, and a sulfonamide group introduced therein.

[0045] Examples of corrosion inhibitors used include benzotriazole, tolyltriazole, and 2-mercaptobenzothiazole. The corrosion inhibitor may be in various forms such as a solid (e.g., powder), a liquid, an aqueous solution in which the solid is dissolved in a solvent, or a mixture in which the solid and the solvent are mixed. The content of the corrosion inhibitor in Additive 2 is, for example, 0.003 wt% or more and 0.500 wt% or less (see Table 2).

[0046] Next, the experiments conducted to confirm the effect of the chelating agent and the results thereof will be described. First, a plurality of Additives 2 containing an organic acid, a corrosion inhibitor, a chelating agent, and an oxidizing agent (see Examples 1 to 28 in Tables 1 and 2 below), and a plurality of Additives 12 containing an organic acid, a corrosion inhibitor, and an oxidizing agent but not containing a chelating agent (see Comparative Examples 1 to 4 in Tables 3 and 4 below) were prepared.

[0047] Table 1 shows each component constituting the first aqueous solution and the second aqueous solution in Examples 1 to 28, and the mixing ratio of the first aqueous solution and the second aqueous solution constituting Additive 2. The numerical values of each component constituting the first aqueous solution and the second aqueous solution, and the numerical values of the first aqueous solution and the second aqueous solution in the mixing ratio are shown as weight ratios (wt%).

[0048] (Example 1) A first aqueous solution was prepared by dissolving 15.00 parts by mass of glycolic acid (organic acid), 0.005 parts by mass of tolyltriazole (corrosion inhibitor), and 1.000 parts by mass of ethylenediaminetetraacetic acid (chelating agent) in 83.95 parts by mass of pure water (see the column of "First Aqueous Solution" in Table 1).

[0049] Also, an aqueous hydrogen peroxide solution (second aqueous solution) was prepared by dissolving 35 parts by mass of hydrogen peroxide in 65 parts by mass of pure water (see the column of "Second Aqueous Solution" in Table 1).

[0050] Then, the first aqueous solution and the second aqueous solution were mixed so that the ratio of the first aqueous solution to the second aqueous solution was 1:2 by weight (see the column of "Mixing Ratio" in Table 1). That is, Additive 2 was prepared by mixing 33.33 parts by mass of the first aqueous solution and 66.67 parts by mass of the second aqueous solution (see Example 1 in Table 2).

[0051] This Additive 2 was placed in a self-standing test tube 4 and the discoloration and generation of bubbles were confirmed at room temperature after standing for 2 hours, 12 hours, and 3 days respectively. As a result, at the time point after 3 days, Additive 2 did not change color and no bubbles were generated in Additive 2 (see the column of "Observation Results" in Table 2 below).

[0052] Table 2 shows the conversion values of the weight ratios of the respective components in Additive 2 in which the first aqueous solution and the second aqueous solution are mixed at a predetermined ratio as shown in the mixing ratio of Table 1. Further, it shows the presence or absence of coloring and the presence or absence of foam generation when Additive 2 is left in a room temperature environment.

[0053] Furthermore, in Table 2, a case where Additive 2 did not color is indicated by a check, and a case where Additive 2 colored is indicated by an ×. Similarly, a case where no foam was generated in Additive 2 is indicated by a check, and a case where foam was generated in Additive 2 is indicated by an ×.

[0054] (Examples 2 to 10) For Examples 2 to 10, in the same manner, a first aqueous solution and a second aqueous solution were prepared, but the types and / or weight ratios of the organic acid, the corrosion inhibitor, and the chelating agent in the first aqueous solution were changed.

[0055] Also, the ratio of the first aqueous solution to the second aqueous solution was set to 1:1 by weight. That is, an Additive 2 was prepared by mixing 50.00 parts by mass of the first aqueous solution and 50.00 parts by mass of the second aqueous solution.

[0056] (Examples 11 to 22) For Examples 11 to 22, in the same manner, a first aqueous solution and a second aqueous solution were prepared, but the types and / or weight ratios of the organic acid, the corrosion inhibitor, and the chelating agent in the first aqueous solution were changed.

[0057] In Examples 11 to 22, the ratio of the first aqueous solution to the second aqueous solution was set to 1:2 by weight. That is, an Additive 2 was prepared by mixing 33.33 parts by mass of the first aqueous solution and 66.67 parts by mass of the second aqueous solution.

[0058] (Examples 23 to 26) For Examples 23 to 26, in the same manner, a first aqueous solution and a second aqueous solution were prepared, but the types and / or weight ratios of the organic acid and the chelating agent in the first aqueous solution were changed. Note that the type and weight ratio of the corrosion inhibitor were fixed.

[0059] In Examples 23 to 26, the ratio of the first aqueous solution to the second aqueous solution was set to 2:1 by weight. That is, Additive 2 was prepared by mixing 66.67 parts by mass of the first aqueous solution and 33.33 parts by mass of the second aqueous solution.

[0060] (Examples 27 and 28) For Examples 27 and 28, the first aqueous solution and the second aqueous solution were prepared in the same manner, but the ratio of the first aqueous solution to the second aqueous solution was set to 3:1 by weight. That is, Additive 2 was prepared by mixing 75.00 parts by mass of the first aqueous solution and 25.00 parts by mass of the second aqueous solution.

[0061] The Additive 2 of Examples 2 to 28 was placed in a self-standing test tube 4 and left at room temperature for 2 hours, 12 hours, and 3 days, respectively, and discoloration and generation of bubbles were confirmed. As a result, at the time point after 3 days had elapsed, Additive 2 had not discolored and no bubbles had been generated in Additive 2.

[0062] [Table 1]

[0063] [Table 2]

[0064] Table 3 shows each component constituting the first aqueous solution and the second aqueous solution in Comparative Examples 1 to 4, and the mixing ratio of the first aqueous solution and the second aqueous solution constituting Additive 12. The numerical values of each component constituting the first aqueous solution and the second aqueous solution, and the numerical values of the first aqueous solution and the second aqueous solution in the mixing ratio are shown in weight ratio (wt%).

[0065] (Comparative Example 1) In Comparative Example 1, a first aqueous solution was prepared by dissolving 15.00 parts by mass of citric acid (organic acid) and 0.10 parts by mass of benzotriazole (corrosion inhibitor) in 84.90 parts by mass of pure water (see the column of "First Aqueous Solution" in Table 3).

[0066] Also, an aqueous hydrogen peroxide solution (second aqueous solution) was prepared by dissolving 35 parts by mass of hydrogen peroxide in 65 parts by mass of pure water (see the column of "second aqueous solution" in Table 3).

[0067] Then, the first aqueous solution and the second aqueous solution were mixed so that the ratio of the first aqueous solution to the second aqueous solution was 1:1 by weight (see the column of "mixing ratio" in Table 3). That is, an additive 12 was prepared by mixing 50.00 parts by mass of the first aqueous solution and 50.00 parts by mass of the second aqueous solution (see Comparative Example 1 in Table 4).

[0068] This additive 12 was placed in a self-standing test tube 4 and left at room temperature for 2 hours, 12 hours, and 3 days, respectively, and the discoloration and generation of bubbles were confirmed. As a result, bubbles had already occurred in the additive 12 at the time point of 2 hours elapsed, and the additive 12 had discolored at the time point of 3 days elapsed (see the column of "observation results" in Table 4).

[0069] Table 4 shows the conversion values of the weight ratios of the respective components in the additive 2 in which the first aqueous solution and the second aqueous solution were mixed at a predetermined ratio as shown in the mixing ratio of Table 3. Also, it shows the presence or absence of coloring and the presence or absence of bubble generation when the additive 12 was left in a room temperature environment.

[0070] Furthermore, in Table 4, the case where the additive 12 did not color is indicated by a check, and the case where the additive 12 colored is indicated by an ×. Similarly, the case where no bubbles occurred in the additive 12 is indicated by a check, and the case where bubbles occurred in the additive 12 is indicated by an ×.

[0071] (Comparative Examples 2 to 4) For Comparative Examples 2 to 4 as well, the first aqueous solution and the second aqueous solution were prepared in the same manner, but the type and / or weight ratio of the organic acid and the corrosion inhibitor in the first aqueous solution were changed. Also, the ratio of the first aqueous solution to the second aqueous solution was 1:1 by weight. As a result of leaving it in the same manner, bubbles occurred in the additive 12 at the time point of 2 hours elapsed, and the additive 12 had discolored at the time point of 3 days elapsed.

[0072]

Table 3

[0073]

Table 4

[0074] Next, referring to FIGS. 3 to 6(B), cutting (i.e., machining) of the workpiece 11 using the cutting fluid 6 to which the above-described additive 2 is added will be described. The workpiece 11 shown in FIG. 3 is a strip substrate that is finally divided into a plurality of QFNs.

[0075] FIG. 3 is a plan view of the workpiece 11. The workpiece 11 has a rectangular metal frame 13 that constitutes the outer shape of the workpiece 11. The metal frame 13 is formed of a metal such as copper (Cu), 42 alloy (i.e., an alloy of iron (Fe) and nickel (Ni)), or the like.

[0076] The metal frame 13 has three device regions 11a, 11b, and 11c defined by an outer peripheral region 13a and linear non-device regions 13b, respectively. In each of the device regions 11a, 11b, and 11c, a plurality of first division planned lines (i.e., metal-containing regions) 15a and a plurality of second division planned lines (i.e., metal-containing regions) 15b are provided in a lattice pattern.

[0077] Each of the first division planned lines 15a is substantially parallel to the long side direction 11d of the workpiece 11. Also, each of the second division planned lines 15b is substantially parallel to the short side direction 11e of the workpiece 11. A semiconductor device chip (not shown) is provided in each rectangular region 17 defined by the plurality of first division planned lines 15a and the plurality of second division planned lines 15b.

[0078] A plurality of metal terminals 19 are arranged at substantially regular intervals around each rectangular region 17. The plurality of metal terminals 19 provided around one rectangular region 17 are electrically connected to one semiconductor device chip. The plurality of metal terminals 19 are exposed from a mold resin formed to cover the plurality of device chips.

[0079] Each metal terminal 19 includes a part of the metal frame 13 and a plating layer made of a metal such as tin (Sn), nickel, palladium (Pd), gold (Au), etc. The plating layer may be composed of one type of metal or alloy, or may have a laminated structure in which layers of different types of metals are stacked.

[0080] By using a cutting device 20 (see FIG. 4) to cut the workpiece 11 along each first division planned line 15a and each second division planned line 15b, the metal terminals 19 are exposed on the outer peripheral side surface of the QFN (i.e., the four end faces formed by cutting).

[0081] Next, the cutting device (i.e., the processing device) 20 will be described. FIG. 4 is a perspective view of the cutting device 20. The X-axis direction (processing feed direction), Y-axis direction (indexing feed direction), and Z-axis direction (vertical direction, cutting direction) shown in FIG. 4 are perpendicular to each other.

[0082] The cutting device 20 includes a base 22 that supports each component. On the upper surface of the base 22, a rectangular opening 22a with a long hand part arranged along the X-axis direction is formed. A ball screw type table moving mechanism 24 is provided below the opening 22a.

[0083] The table moving mechanism 24 includes an X-axis moving table (not shown). The X-axis moving table is movable along the X-axis direction. The upper parts of the table moving mechanism 24 and the X-axis moving table are covered by a table cover 26a and a bellows cover 26b.

[0084] On the table cover 26a, a chuck table (holding table) 28 for holding the workpiece 11 is provided. The chuck table 28 is supported by the X-axis moving table of the table moving mechanism 24 and is movable along the X-axis direction together with the table cover 26a.

[0085] The chuck table 28 is connected to a rotational drive source (not shown) such as a motor and is rotatable about a rotational axis substantially parallel to the Z-axis direction. The chuck table 28 has a table base 30 having a plurality of flow paths inside.

[0086] On the upper surface 30a of the table base 30, a plate-shaped holding jig 32 having an outer diameter larger than the outer shape of the workpiece 11 is mounted. A suction source (not shown) such as a vacuum pump is connected to the holding jig 32, and the holding jig 32 is suction-held on the upper surface 30a of the table base 30 by the negative pressure generated by the suction source.

[0087] The holding jig 32 is formed of a flexible material that can suppress vibration of the workpiece 11 during cutting. The holding jig 32 is formed of, for example, urethane rubber, nitrile rubber, ethylene rubber, butyl rubber, fluorine rubber, silicone rubber, isoprene rubber, butadiene rubber, acrylic rubber, polysulfide rubber, or the like.

[0088] On the surface 32a of the holding jig 32, a plurality of grooves each having a predetermined depth that does not reach from the surface 32a to the back surface 32b are provided in a lattice pattern. In FIG. 4, the plurality of grooves are indicated by lines on the surface 32a.

[0089] Each groove on the surface 32a is at a position corresponding to the first planned division line 15a or the second planned division line 15b of the workpiece 11. However, the width of each groove is wider than the width of the cutting blade 56 described later.

[0090] In each rectangular region partitioned by the plurality of grooves, cylindrical suction holes (not shown) penetrating from the surface 32a to the back surface 32b of the holding jig 32 are provided. When the negative pressure generated by the above-described suction source is transmitted to the surface 32a through the suction holes, the surface 32a of the holding jig 32 functions as a holding surface for suction-holding the workpiece 11.

[0091] Above the abutment 22, a portal-shaped support structure 34 is arranged so as to straddle the opening 22a. On the upper front part of the support structure 34, a cutting unit moving mechanism 36 is provided. The cutting unit moving mechanism 36 has a pair of Y-axis guide rails 38.

[0092] A Y-axis moving plate 40 is slidably attached to the pair of Y-axis guide rails 38 along the Y-axis direction. On the back surface side of the Y-axis moving plate 40, a nut portion (not shown) is provided, and a screw shaft 42 is rotatably fixed to this nut portion.

[0093] One end of the screw shaft 42 is connected to a stepping motor (not shown). If the screw shaft 42 is rotated by this stepping motor, the Y-axis moving plate 40 moves along the Y-axis direction. On the surface of the Y-axis moving plate 40, a pair of Z-axis guide rails 44 are provided.

[0094] A Z-axis moving plate 46 is slidably attached to the pair of Z-axis guide rails 44 along the Z-axis direction. On the back surface side of the Z-axis moving plate 46, a nut portion (not shown) is provided, and a screw shaft 48 is rotatably fixed to this nut portion.

[0095] The upper end of the screw shaft 48 is connected to a stepping motor 50. If the screw shaft 48 is rotated by the stepping motor 50, the Z-axis moving plate 46 moves along the Z-axis direction. A cutting unit 52 is fixed to the lower part of the Z-axis moving plate 46.

[0096] The cutting unit 52 has a cylindrical spindle housing 54 with a long hand portion arranged along the Y-axis direction. Inside the spindle housing 54, a part of a columnar spindle (not shown) arranged substantially parallel to the Y-axis direction is rotatably accommodated.

[0097] The spindle can rotate at high speed by a driving source (not shown) such as a servo motor. A cutting blade (i.e., a machining tool) 56 is attached to the tip of the spindle. In addition, a plurality of cutting fluid supply nozzles are provided at the tip of the spindle housing 54.

[0098] As shown in FIG. 6(B), the plurality of cutting fluid supply nozzles include a pair of cooler nozzles 58a arranged to sandwich the cutting blade 56 in the Y-axis direction. In FIG. 6(B), only one of the cooler nozzles 58a is shown.

[0099] The pair of cooler nozzles 58a supplies the cutting fluid 6 in which the above-mentioned additive 2 is diluted 150 times by pure water by weight ratio toward the vicinity of the lower end of the cutting blade 56 including the machining point 56a where the cutting blade 56 and the workpiece 11 come into contact, among both sides of the annular cutting edge of the cutting blade 56.

[0100] Note that in the cutting edge of the cutting blade 56, super abrasive grains formed of diamond, cBN (cubic boron nitride), etc. are fixed by a bonding material such as a resin bond, a metal bond, a vitrified bond, an electrodeposited bond, an electroformed bond. The cutting blade 56 may be a hub blade in which the cutting edge is fixed to an annular base, or may be a hubless blade (i.e., a washer blade) composed only of the cutting edge.

[0101] The plurality of cutting fluid supply nozzles include a shower nozzle 58b. The shower nozzle 58b is arranged above the pair of cooler nozzles 58a and supplies the cutting fluid 6 with the above-mentioned additive 2 added to the outer peripheral portion of the cutting blade 56. The pair of cooler nozzles 58a and the shower nozzle 58b continue to supply the cutting fluid 6 during the cutting of the workpiece 11.

[0102] A pair of coolant nozzles 58a are connected to a coolant supply source 62 via a pipe portion 60a, and a shower nozzle 58b is connected to the coolant supply source 62 via a pipe portion 60b. The coolant supply source 62 is provided, for example, inside the cutting device 20, but may be provided as a separate device beside the cutting device 20.

[0103] The coolant supply source 62 includes a coolant storage tank (not shown) in which the coolant 6 is stored, and a pump (not shown) for supplying the coolant 6 to the pipe portions 60a and 60b from the coolant storage tank at a predetermined flow rate.

[0104] The coolant storage tank may be provided with a stirrer (not shown) for stirring the above-described additive 2 and pure water. The stirrer may have a rotating blade, or may be a stationary stirrer without a rotating blade. Pure water is supplied to the coolant supply source 62 from a pure water supply source 64a.

[0105] The pure water supply source 64a is, for example, equipment installed in a building such as a factory. The pure water supply source 64a includes a pure water storage tank (not shown) in which pure water is stored, and a pump (not shown) for supplying pure water to the coolant storage tank from the pure water storage tank at a predetermined flow rate.

[0106] In addition, the above-described organic acid, chelating agent, etc. are supplied to the coolant supply source 62 from a first component supply source 64b. The first component supply source 64b includes a first component storage tank (not shown) in which a first aqueous solution containing an organic acid, a chelating agent, etc. is stored. The supply of the first aqueous solution from the first component storage tank to the coolant storage tank is controlled by a pump, a flow rate adjustment valve, etc. (all not shown).

[0107] In addition, the above-described oxidizing agent is supplied to the coolant supply source 62 from a second component supply source 64c. The second component supply source 64c includes a second component storage tank (not shown) in which a second aqueous solution containing an oxidizing agent is stored. The supply of the second aqueous solution from the second component storage tank to the coolant storage tank is controlled by a pump, a flow rate adjustment valve, etc. (all not shown).

[0108] Pure water, a first component (organic acid and chelating agent), and a second component (oxidizing agent) are mixed in a cutting fluid storage tank, whereby cutting fluid 6 containing pure water and the above-described additive 2 is created and stored in the cutting fluid storage tank.

[0109] Returning to FIG. 4, a microscope camera unit 66 is provided below the Z-axis moving plate 46 in a manner adjacent to the cutting unit 52 in the X-axis direction. The microscope camera unit 66 includes a light source such as an LED (Light Emitting Diode), one or more lenses, and an imaging element. The microscope camera unit 66 is used for adjusting the cutting position and the like.

[0110] Next, referring to FIGS. 5, 6(A), and 6(B), a cutting method for cutting the workpiece 11 with the cutting blade 56 will be described. FIG. 5 is a flowchart of the cutting method for the workpiece 11, and FIG. 6(A) is a diagram showing a holding step S10 of holding the workpiece 11 on the surface 32a of the holding jig 32 on the chuck table 28.

[0111] After sucking and holding the workpiece 11 in the holding step S10, the orientation of the chuck table 28 is adjusted in the XY plane using the microscope camera unit 66 so that the first division planned line 15a is substantially parallel to the X-axis direction.

[0112] Next, the cutting blade 56 disposed outside the chuck table 28 in the XY plane is disposed on the extension line of the first division planned line 15a, and the lower end position of the cutting blade 56 is positioned between the surface 32a of the holding jig 32 and the bottom of the groove of the holding jig 32 while the cutting blade 56 is rotated at high speed.

[0113] Then, by moving the chuck table 28 along the X-axis direction, the rotating cutting blade 56 and the workpiece 11 are relatively moved along the X-axis direction. At this time, for example, the rotation direction of the cutting blade 56 and the moving direction of the chuck table 28 are adjusted in advance so that down-cut cutting is realized.

[0114] FIG. 6(B) is a diagram showing a cutting process (i.e., a machining process) S20. When cutting the first division planned line 15a of the workpiece 11 with the cutting blade 56, cutting is performed while supplying the cutting water 6 to the machining point 56a at a predetermined flow rate from a pair of cooler nozzles 58a and a shower nozzle 58b, respectively.

[0115] In this cutting method, by using the cutting water 6 having the additive 2 containing a chelating agent, the amount of the organic acid and the oxidizing agent that act to reduce the degree of ductility and malleability of the metal terminal 19 can be increased compared to the case of using the cutting water having the additive 12 not containing a chelating agent. Therefore, the amount of metal burrs generated during cutting of the workpiece 11 can be reduced.

[0116] After cutting the workpiece 11 along all the first division planned lines 15a, the chuck table 28 is rotated approximately 90 degrees. Then, similarly, the workpiece 11 is cut along all the second division planned lines 15b, thereby dividing the workpiece 11 into a plurality of QFNs.

[0117] In addition, the structures, methods, etc. according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the object of the present invention. For example, the workpiece 11 is not limited to a strip substrate in which the metal frame 13 and a plurality of device chips are sealed with a molding resin.

[0118] The workpiece 11 may be a semiconductor wafer in which a TEG (Test Element Group) is exposed at the division planned line. In the cutting process S20, by using the cutting water 6 containing the additive 2, the degree of ductility and malleability of the metal can be reduced, so that the amount of metal burrs generated during cutting can be reduced.

[0119] Further, in addition to the organic acid, the oxidizing agent, and the chelating agent, the additive 2 may contain a very small amount of a water-soluble basic material such as ammonia, triethanolamine, and tetramethylammonium hydroxide as a pH adjuster.

[0120] Note that the additive 2 described in this specification is not limited to the cutting of the workpiece 11 with the cutting blade 56, and can also be applied to the grinding of the workpiece 11 with a grinding wheel (not shown) having one or more grinding wheels, the cutting of the workpiece 11 with a tool bit (not shown) having a cutting edge fixed to the tip of the shank, etc.

[0121] The grinding device (processing device) not shown includes a disk-shaped chuck table (i.e., holding table) and a grinding unit disposed above the chuck table. The grinding unit has a columnar spindle housing whose longitudinal direction is along the Z-axis direction (i.e., the height direction of the grinding device).

[0122] A part of a columnar spindle whose longitudinal direction is along the Z-axis direction is rotatably accommodated in the spindle housing by an air bearing. A disk-shaped mount is fixed to the lower end of the spindle, and an annular grinding wheel (i.e., processing tool) is fixed to the lower surface side of the mount by a fixing member such as a bolt.

[0123] The grinding wheel is made of metal and has an annular base. A plurality of grinding wheels are arranged along the circumferential direction of the base at substantially equal intervals. In each grinding wheel, super abrasive grains formed of diamond, cBN (cubic boron nitride), etc. are fixed by a bonding material such as a resin bond, a metal bond, or a vitrified bond.

[0124] The workpiece to be ground (i.e., processed) by the grinding wheel is, for example, a wafer (i.e., WL-CSP (Wafer level Chip Size Package) substrate) in which a rewiring layer and metal posts (i.e., columnar electrodes) are sealed with a resin layer or the like. When this resin layer is ground and thinned, the metal posts will be ground. That is, this resin layer becomes the metal-containing region in the grinding process.

[0125] Note that the workpiece to be ground by the grinding wheel is not limited to the above example, and may be a metal plate, a wafer having TSV (Through Silicon Via), a wafer on which a metal film, metal bumps, etc. are formed, or a plate-like object containing metal on the processed surface.

[0126] In the Z-axis direction, a nozzle for supplying grinding water (i.e., processing water) to the processing point is provided between the holding surface of the chuck table and the grinding wheel. Grinding water containing the above-mentioned additive and pure water is supplied from the nozzle at a predetermined flow rate.

[0127] When thinning the workpiece by infeed grinding using the grinding apparatus, similar to the flow shown in FIG. 5, first, the workpiece is sucked and held by the chuck table (holding step). Next, the chuck table and the spindle are rotated at a predetermined speed, and the spindle housing is fed downward at a predetermined processing feed rate.

[0128] At this time, the above-mentioned grinding water is supplied to the processing point where the workpiece and the grinding wheel come into contact at a predetermined flow rate (grinding step (i.e., processing step)). Also in this grinding method (i.e., processing method), grinding water having additive 2 containing a chelating agent is used.

[0129] Therefore, compared with the case of using grinding water having additive 12 that does not contain a chelating agent, the amount of the organic acid and the oxidizing agent that act to reduce the degree of ductility and malleability of the metal post, etc. can be increased. Therefore, the amount of metal burrs generated during grinding of the workpiece can be reduced.

[0130] A turning device (i.e., processing device) (not shown) also similarly includes a disk-shaped chuck table (i.e., holding table) and a tool unit disposed above the chuck table. The tool unit has a columnar spindle housing whose longitudinal direction is along the Z-axis direction (i.e., the height direction of the turning device).

[0131] A part of a columnar spindle whose longitudinal direction is arranged along the Z-axis direction is rotatably accommodated in the spindle housing by an air bearing. A disk-shaped mount is fixed to the lower end of the spindle, and an annular cutting tool (i.e., a machining tool) is fixed to the lower surface side of the mount by a fixing member such as a bolt.

[0132] The cutting tool is made of metal and has an annular base. A prismatic shank made of metal is fixed to the base. The shank is arranged so as to protrude from the lower surface of the base. A diamond cutting edge is fixed to the lower end of the shank.

[0133] The workpiece to be cut (i.e., machined) by the cutting tool is also, for example, a wafer (i.e., a WL-CSP substrate) in which a rewiring layer and metal posts are sealed with a resin layer or the like. When cutting and thinning this resin layer, the metal posts will be cut. That is, this resin layer becomes the metal-containing region in the cutting process.

[0134] Note that the workpiece to be cut by the cutting tool is not limited to the above example, and may be a plate-like object containing metal on the machined surface, such as a metal plate, a wafer having TSV (Through Silicon Via), a metal film, a wafer on which metal bumps or the like are formed.

[0135] In the Z-axis direction, a nozzle for supplying cutting water (i.e., machining water) 6 to the machining point is provided between the holding surface of the chuck table and the cutting tool. Cutting water containing the above-mentioned additive and pure water is supplied from the nozzle at a predetermined flow rate.

[0136] When using the cutting device to cut a workpiece, similar to the flow shown in FIG. 5, first, the workpiece is sucked and held by the chuck table (holding step). Next, the spindle is rotated at a predetermined speed, and the height position of the cutting edge of the cutting tool is positioned a predetermined depth below the machined surface of the workpiece.

[0137] In this state, the chuck table is moved at a predetermined feed rate along the X-axis direction orthogonal to the Z-axis direction (the turning cutting process (i.e., the machining process)). At this time, the cutting fluid described above is supplied at a predetermined flow rate to the machining point where the workpiece and the cutting edge come into contact. Also in this cutting method (i.e., the machining method), the cutting fluid 6 having the additive 2 containing a chelating agent is used.

[0138] Therefore, compared with the case of using a cutting fluid having an additive 12 that does not contain a chelating agent, the amount of the organic acid and the oxidizing agent that act to reduce the degree of ductility and malleability of a metal post or the like can be increased. Accordingly, the amount of metal burrs generated during cutting of the workpiece can be reduced.

Explanation of Signs

[0139] 2: Additive, 2a: Liquid surface, 4: Test tube, 6: Cutting fluid (machining water) 11: Workpiece, 11a, 11b, 11c: Device regions 11d: Long side direction, 11e: Short side direction 12: Additive, 12a: Liquid surface, 12b: Bubbles 13: Metal frame, 13a: Outer peripheral region, 13b: Non-device region 14: Test tube 15a: First division planned line (metal-containing region) 15b: Second division planned line (metal-containing region) 17: Rectangular region, 19: Metal terminal (metal) 20: Cutting device (machining device), 22: Base, 22a: Opening, 24: Table moving mechanism 26a: Table cover, 26b: Bellows cover 28: Chuck table (holding table), 30: Table base, 30a: Upper surface 32: Holding jig, 32a: Surface, 32b: Back surface 34: Support structure, 36: Cutting unit moving mechanism, 38: Y-axis guide rail 40: Y-axis moving plate, 42: Screw shaft 44: Z-axis guide rail, 46: Z-axis moving plate, 48: Screw shaft, 50: Stepping motor 52: Cutting unit, 54: Spindle housing 56: Cutting blade (processing tool), 56a: Processing point 58a: Cooler nozzle, 58b: Shower nozzle, 60a, 60b: Pipe part 62: Cutting water supply source, 64a: Pure water supply source 64b: First component supply source, 64c: Second component supply source 66: Microscope camera unit S10: Holding process, S20: Cutting process (processing process)

Claims

1. An additive for machining water added to the machining water used when machining a metal-containing region of a workpiece with a machining tool, comprising an organic acid, an oxidizing agent, and a chelating agent, wherein the organic acid and the chelating agent contain different substances from each other, and being an additive for machining water.

2. The chelating agent has one or a combination of two or more selected from ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, and gluconic acid, and being the additive for machining water according to Claim 1.

3. The content of the chelating agent is 0.003 wt% or more and 1.333 wt% or less, and being the additive for machining water according to Claim 1 or 2.

4. A machining method of a workpiece, using the machining water containing the additive according to Claim 1 and pure water, to machine the metal-containing region of the workpiece with the machining tool, comprising a holding step of holding the workpiece by a holding table of a machining apparatus, and a machining step of machining the metal-containing region while supplying the machining water to a machining point where the machining tool and the workpiece are in contact, and being a machining method of a workpiece.

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