MACHINING METHOD FOR A PLATE-SHAPED WORKPIECE

Abstract

Machining method for a plate-shaped workpiece for machining a plate-shaped workpiece (11) having a parting line (13) and a metal element (21) formed on the parting line (13) or in an area corresponding to the parting line (13), wherein the machining method for a plate-shaped workpiece comprises: a holding step to hold the plate-shaped workpiece (11) on a clamping table (12) in the state in which the metal element (21) is oriented downwards; a first cutting step for cutting the plate-shaped workpiece (11) along the parting line (13) using a first cutting blade (18) after performing the holding step, thereby forming a first cut groove (23) which has a bottom that does not reach the metal element (21); and a second cutting step to cut the plate-shaped workpiece (11) along the first cut groove (23) using a second cutting blade (18, 18A) after performing the first cutting step, thereby forming a second cut groove (25, 26) which completely cuts the plate-shaped workpiece (11) along the parting line (13) so that the metal element (21) is divided; in contrast to the first cutting step, only the second cutting step includes the step of supplying a cutting fluid (22) containing an organic acid and an oxidizing agent to the plate-shaped workpiece (11).

Description

Field of invention

[0001] The present invention relates to a machining method for a plate-shaped workpiece for machining a plate-shaped workpiece which has a parting line and a metal element which is formed on the parting line or in an area corresponding to the parting line. Description of the state of the art

[0002] A wafer, such as a semiconductor wafer, has a front face on which several components are formed by intersecting division lines. The wafer, containing these components, is cut along the division lines, thereby dividing it into individual component chips. In some cases, a metal film is formed on the back face of the wafer, improving the electrical characteristics of each component. However, when this metal film is cut by a cutting blade, the blade can become clogged. Furthermore, if the wafer is cut by this clogged blade, cracks can form in the wafer, or the cutting blade itself can be damaged.

[0003] In another case, a test element group (TEG) is formed as a metal element at each division line of the wafer, allowing the electrical characteristics of each element to be measured. When this wafer, containing the TEG, is cut along each division line by a cutting blade, the cutting blade can become clogged. Another known plate-shaped workpiece, having a division line and a metal element formed at the division line, is a packed substrate. A packed substrate has an electrode surface in which several electrodes are formed. In a machining process for the packed substrate, the packed substrate is cut from the electrode surface by a cutting blade, thereby dividing it into individual packings.When the packaged substrate is cut through the electrode surface with a cutting blade, a problem arises in that burrs can be formed by the electrodes during the cutting process. To avoid clogging of the cutting blade, a method for cutting a workpiece containing metal electrodes using a saw blade with carbide tips instead of the cutting blade was proposed in JP H09-55573A.

[0004] JP 2002 - 231 658 A relates to a method for cutting a semiconductor.

[0005] JP 2016 - 54 182 A concerns a processing method for a wafer.

[0006] US 2010 / 0 003 771 A1 relates to a process for manufacturing semiconductor components.

[0007] US 2015 / 0262881A1 discloses the use of a cutting fluid containing an organic acid and an oxidizing agent for cutting a metal element. PRESENTATION OF THE INVENTION

[0008] In the cutting method proposed in JP H09-55573A, the saw blade with carbide tips does not have a self-sharpening function, unlike a cutting blade, so the sharpness of the saw blade diminishes over time. Consequently, the saw blade change frequency increases, leading to a reduction in machinability. Furthermore, when a cutting blade cuts a metal element formed on the workpiece, the cutting blade can become clogged, as described above, creating another problem: the metal element being cut is elongated, causing burrs or distortion. Generally, increasing the feed rate increases the cutting load and the heat generated during cutting, resulting in more burrs and distortion.Accordingly, it is difficult to increase the feed rate while preventing a decrease in processing quality.

[0009] It is therefore an objective of the present invention to provide a machining method for a plate-shaped workpiece for machining a plate-shaped workpiece which has a parting line and a metal element which is formed on the parting line or in an area corresponding to the parting line, in which the feed rate can be increased by this method in comparison with the prior art.

[0010] In accordance with one aspect of the present invention, a machining method for a plate-shaped workpiece is provided for machining a plate-shaped workpiece having a parting line and a metal element formed on the parting line or in a region corresponding to the parting line, wherein the machining method for a plate-shaped workpiece comprises a holding step for holding the plate-shaped workpiece on a clamping table in a state in which the metal element is oriented downwards; a first cutting step for cutting the plate-shaped workpiece along the parting line using a first cutting blade after performing the holding step, thereby forming a first cut groove having a bottom that does not reach the metal element;and a second cutting step for cutting the plate-shaped workpiece along the first cut groove using a second cutting blade after performing the first cutting step, thereby forming a second groove that completely cuts the plate-shaped workpiece along the parting line, so that the metal element is divided; wherein, unlike the first cutting step, only the second cutting step includes the step of supplying a cutting fluid, which contains an organic acid and an oxidizing agent, to the plate-shaped workpiece.

[0011] According to the machining method of the present invention, the plate-shaped workpiece is cut in two steps along its thickness direction using a first and second cutting blade. Accordingly, the thickness of the workpiece to be cut can be reduced in each step, thus increasing the machining speed (feed rate) compared to cutting the workpiece completely in one step. Furthermore, during the second cutting step, a cutting fluid containing an organic acid and an oxidizing agent is introduced into the workpiece. The organic acid in the cutting fluid modifies the metal present on the workpiece, reducing its ductility and thereby preventing the formation of burrs.Furthermore, the surface properties of the metal element are altered by the oxidizing agent contained in the cutting fluid, causing the metal element to lose its ductility, resulting in easier cutting and thus improved machinability.

[0012] The above and other aims, features and advantages of the present invention and the manner of realizing them will be made clearer and the invention itself best understood by studying the following description, the claims attached to it, with reference to the attached figures, which show a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE FIGURES Fig. Figure 1A is a perspective view of a semiconductor wafer, viewed from its front side; Fig. 1B is a cross-sectional view of the semiconductor wafer, which is in Fig. 1 is shown; Fig. Figure 2 is a perspective view of a wafer unit designed by carrying the semiconductor wafer on a ring-shaped frame using a divider band; Fig. 3A is a partial sectional view showing a first cutting step; Fig. 3B is an enlarged cross-sectional view of the semiconductor wafer that has been processed by the first cutting step; Fig. 4A is an enlarged sectional view showing a second cutting step in the case of using the same cutting blade as the one used in the first cutting step; Fig. 4B is a view similar to Fig. 4A, which shows the case of using a cutting blade that has a smaller thickness than the cutting blade used in the first cutting step; and Fig. Figure 5 is a side view showing a nozzle means for supplying a cutting fluid in the second cutting step according to a modification. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0013] Preferred embodiments of the present invention will now be described in detail with reference to the figures. Fig. Figure 1A shows a perspective view of a semiconductor wafer (sometimes referred to simply as a wafer in the following). Figure 11 shows the following. As in Fig. Figure 1A shows that the semiconductor wafer 11 has a front side 11a and a back side 11b. Fig. Figure 1A shows the front side 11a of the semiconductor wafer 11. Fig. Figure 1B is a sectional view of the semiconductor wafer. Several intersecting division lines 13 are formed on the front face 11a of the wafer 11 to create several separate areas on which several devices 15, such as LSIs (large-scale integrated circuits), are formed. In particular, the multiple division lines 13 are formed from several parallel division lines extending in a first direction and several parallel division lines extending in a second direction perpendicular to the first direction. As shown in Fig. As shown in Figure 1B, a metal film 21 made of copper (Cu) or aluminum (Al), for example, is formed on the rear side 11b of the wafer 11. With reference to Fig. Figure 2A shows a perspective view of a wafer unit 17, which is configured by supporting the wafer 11 on an annular frame F via a dividing band T. In the processing method for a wafer according to this preferred embodiment, the wafer 11 is formed in the shape of the wafer unit 17, which is configured in Fig. Figure 2 is shown. In particular, the rear side 11b of the wafer 11 is attached to the dividing strip T in its central section and the circumferential section of the dividing strip T is attached to the annular frame F.

[0014] In the processing method for a wafer according to this preferred embodiment, a holding step is first performed to hold the wafer 11 under suction by the dividing belt T on a clamping table 12 of a cutting device in the state in which the metal film 21, which is formed on the rear side 11b of the wafer 11, is oriented downwards, as shown in Fig. 3A shown. Furthermore, the annular frame F is clamped by several clamps 14 which are attached to the outer circumference of the clamping table 12, as shown in Fig. As shown in Figure 3A, the wafer 11 is provided and fixed. Accordingly, the wafer 11 is held by the parting belt T on the clamping table 12 in the state in which the front face 11a of the wafer 11 is exposed. In this state, a first cutting step is performed to cut the wafer 11 from the front face 11a along the parting lines 13 using a cutting blade 18 as a first cutting blade, thereby forming a first cut groove 23, the bottom of which does not reach the metal film 21, along each parting line 13, as shown in Figure 3A. Fig. 3A shown.

[0015] Before performing the first cutting step, an alignment step, known in the prior art, is carried out using an imaging unit (not shown) incorporated in the cutting device. That is, the imaging unit is actuated to image the front face 1a of the wafer 11, which is held on the clamping table 12. Based on an image obtained by the imaging unit, the cutting blade 18, mounted at the front end of a spindle 16, is aligned with one of the division lines 13, which is a target.After performing this alignment step, a first cutting step is carried out in such a way that the cutting blade 18 is rotated at high speed and moved relatively along the target splitting line 13 to cut the wafer 11 from the front side 11a along the target splitting line 13, forming the first cut groove 23 along the target splitting line 13, wherein the first cut groove 23 has a bottom that does not reach the metal film 21 formed on the rear side as 1b of the wafer 11.

[0016] This first cutting step is repeated along all division lines 13 extending in the first direction, while the cutting blade 18 is offset by the distance between the division lines 13. The clamping table 12 is then rotated 90° to perform the first cutting step similarly along all the other division lines 13 extending in the second direction perpendicular to the first direction. Fig. 3B is an enlarged cross-sectional view of wafer 11, which is processed by the first cutting step.

[0017] As in Fig. As shown in Figure 3B, an uncut section 27 remains between the bottom of each first cut groove 23 and the lower surface of the metal film 21. While the thickness of this uncut section 27 is not particularly limited, it is preferably set to approximately 20-30 µm, taking into account the manageability of the following steps.

[0018] After the first cutting step, a second cutting step is performed to cut the wafer 11 along each first cut groove 23 using a second cutting blade, thereby forming a second cut groove that completely cuts the wafer 11 along each parting line 13, thus dividing the metal film 21. In this second cutting step, a cutting fluid containing an organic acid and an oxidizing agent is introduced to the wafer 11. Fig. Figure 4A shows a first preferred embodiment of the second cutting step. In the first preferred embodiment, which is shown in Fig. As shown in Figure 4A, the same cutting blade 18 as used in the first cutting step is used to form a second cut groove 26 that completely cuts the wafer 11 along the first cut groove 23 that was previously formed. As shown in Fig. As shown in Figure 4A, a pair of nozzles 20 for a cutting fluid is provided on both sides of the cutting blade 18, so that a cutting fluid 22, which contains an organic acid and an oxidizing agent, is supplied to the wafer 11. That is, the wafer 11 is cut along each first cut groove 23 by the cutting blade 18 during the supply of the cutting fluid 22, which contains an organic acid and an oxidizing agent, to the wafer 11 in such a way that the lower edge of the cutting blade 18 cuts the bottom of each first cut groove 23 until the parting belt T is reached, and the clamping table 12, which holds the wafer 11 through the parting belt, is supplied.As a result, the second cut groove 26 is designed to completely cut the wafer 11 in such a way that the metal film 21 formed on the rear side 11b (bottom surface) of the wafer 11 is divided by the second cut groove 26. Accordingly, the second cut groove 26 has the same width as that of the first cut groove 23 in the first preferred embodiment.

[0019] Amino acids can be used as the organic acid. Examples of amino acids that can be used here 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-cystic 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, 5-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, Antipain etc.Among others, glycine, L-alanine, L-proline, L-histidine, L-lysine, and dihydroxyethylglycine are particularly preferred.

[0020] Aminopolyacids can also be used as the organic acid. Examples of aminopolyacids that can be used here include iminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, nitrilotrismethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenesulfonic acid, 1,2-diaminopropanetetraacetic acid, glycoletherdiaminetetraacetic acid, transcyclohexanediaminetetraacetic acid, ethylenediamineorthohydroxyphenylacetic acid, ethylenediaminedisuccinic acid (SS isomer), β-alaninediaacetic acid, N-(2-carboxyatoethyl)-L-aspartic acid, N-N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, etc.

[0021] Furthermore, carboxylic acids can be used as organic acids. Examples of carboxylic acids that can be used here include saturated carboxylic acids such as formic acid, glycolic acid, propionic acid, acetic acid, butyric acid, valeric acid, caproic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, malic acid, succinic acid, pimelic acid, mercaptoacetic acid, glyoxylic acid, chloroacetic acid, pyruvic acid, acetoacetic acid, etc.; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mesaconic acid, citraconic acid, aconitic acid, etc.; and cyclic unsaturated carboxylic acids such as benzoic acid, toluic acid, phthalic acid, naphthoic acids, pyromellitic acid, naphthalic acid, etc.

[0022] Examples of oxidizing agents that can be used there include hydrogen peroxide, peroxides, nitrates, iodates, periodates, hypochlorites, chlorites, chlorates, perchlorates, persulfates, dichromates, permanganates, cerates, vanadates, ozonated water, silver(II) salts, iron(III) salts, and their organic complex salts.

[0023] Furthermore, a corrosion inhibitor can be mixed into the cutting fluid 22. Mixing in the corrosion inhibitor prevents corrosion (elution) of the metal contained in the packaged substrate 2. A heterocyclic ring compound having at least three nitrogen atoms in its molecule and a fused ring structure, or a heterocyclic aromatic ring compound having at least four nitrogen atoms in its molecule, is preferably used as the corrosion inhibitor. The aromatic ring compound preferably comprises a carboxyl group, sulfo group, hydroxy group, or alkoxy group. Specifically preferred examples of the aromatic ring compound include tetrazole derivatives, 1,2,3-triazole derivatives, and 1,2,4-triazole derivatives.

[0024] Examples of tetrazole derivatives that can be used as corrosion protection include those that have no substituent group on the nitrogen atoms forming the tetrazole ring and that have a substituent group inserted at the 5-position of the tetrazole selected from the group consisting of a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group, or an alkyl group substituted with at least one substituent group selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group.

[0025] Examples of 1,2,3-triazole derivatives that can be used as corrosion inhibitors include those that have no substituent group on the nitrogen atoms forming the 1,2,3-triazole ring and that have a substituent group inserted at the 4-position and / or the 5-position of the 1,2,3-triazole, selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group, or an alkyl or aryl group substituted with at least one substituent group selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group.

[0026] Furthermore, examples of 1,2,4-triazole derivatives that can be used as corrosion protection include those that do not have a substituent group on the nitrogen atoms forming the 1,2,4-triazole ring and that, inserted at the 2-position and / or the 5-position of the 1,2,4-triazole, have a substituent group selected from the group consisting of a sulfo group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group, or an alkyl or aryl group substituted with at least one substituent group selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group.

[0027] As described above, the cutting fluid 22, which contains an organic acid and an oxidizing agent, is supplied through the nozzles 20 for the second cutting step. Accordingly, the metal forming the metal film 21 is modified by the organic acid contained in the cutting fluid 22, reducing its ductility and thus preventing the formation of burrs. Furthermore, the oxidizing agent in the cutting fluid 22 alters the surface properties of the metal film 21, reducing its ductility and making it more machinable.

[0028] This second cutting step is repeated along all the division lines 13 extending in the first direction, while the cutting blade 18 is offset by the distance between the division lines 13. The clamping table 12 is then rotated 90° to perform the second cutting step similarly along all the other division lines 13 extending in the second direction perpendicular to the first. Consequently, the wafer 11 can be divided into individual component chips, each having the metal film 21 on its back side.

[0029] With reference to Fig. Figure 4B shows a second preferred embodiment of the second cutting step. In the second preferred embodiment, which is shown in Fig. As shown in Figure 4B, a cutting blade 18A, which has a smaller thickness than the cutting blade 18 used in the first cutting step, is used as the second cutting blade to form a second cut groove 25 that completely cuts the wafer 11 along each first cut groove 23 that was previously formed. Accordingly, the second cut groove 25, which is shown in Figure 4B, has a thickness of 18A. Fig. 4B shows a smaller width than that of the first groove 23, i.e., smaller than that of the second cut groove 26, which is shown in Fig. 4A is shown. As in Fig. As shown in Figure 4B, the wafer 11 is cut along each first cut groove 23 by the cutting blade 18A, while the cutting fluid 22, which contains an organic acid and an oxidizing agent, is fed to the wafer 11 such that the lower edge of the cutting blade 18A cuts the bottom of each first cut groove 23 along its center until the parting belt T is reached, and the clamping table 12, which holds the wafer 11 by the parting belt T, is fed. As a result, the second cut groove 25 is formed such that it completely cuts the wafer 11 in such a way that the metal film 21, which is formed on the rear side 11b (bottom surface) of the wafer 11, is divided by the second cut groove 25.

[0030] This second cutting step is repeated along all the other division lines 13 extending in the first direction, while the cutting blade 18A is offset by the distance between the division lines 13. The clamping table 12 is then rotated 90° to perform the second cutting step along all the other division lines 13 extending in the second direction perpendicular to the first direction. Consequently, the wafer 11 can be divided into individual component chips, each of which has a metal film 21 on its back side.

[0031] Furthermore, during the second cutting step, while the cutting fluid 22 is supplied by the pair of nozzles 20 located on both sides of the cutting blade 18 or 18A, any nozzle means capable of supplying the cutting fluid 22 can be adapted in the present invention.

[0032] Fig. Figure 5 is a side view of a cutting unit 6 which includes a nozzle medium suitable for supplying the cutting fluid 22 according to a modification. As in Fig. As shown in Figure 5, the cutting unit 6 includes a nozzle (shower nozzle) 24 for supplying the cutting fluid 22, in addition to the cutting blade 18 and the pair of nozzles 20. The nozzle 24 is located on the front side of the cutting blade 18 in its cutting direction (supply direction). By supplying the cutting fluid 22 from the nozzle 24, the cutting fluid 22 can be easily fed into the first cut groove, so that the metal film 21 can be effectively modified by the cutting fluid 22. In particular, the nozzle opening of the nozzle 24 is preferably inclined upwards (e.g., towards the working position in which the cutting blade 18 cuts the workpiece), as shown in Figure 5. Fig. Figure 5 shows that with this configuration, the metal film 21 can be modified more effectively by the cutting fluid 22. The pair of nozzles 20 and the nozzle 24 are used to inject the cutting fluid 22 into the modified form shown in Figure 5. Fig. As shown in 5, only nozzle 24 can be used to supply the cutting fluid 22.

Claims

[1] Machining method for a plate-shaped workpiece for machining a plate-shaped workpiece (11) having a parting line (13) and a metal element (21) formed on the parting line (13) or in a region corresponding to the parting line (13), wherein the machining method for a plate-shaped workpiece comprises: a holding step to hold the plate-shaped workpiece (11) on a clamping table (12) in the state in which the metal element (21) is oriented downwards; a first cutting step for cutting the plate-shaped workpiece (11) along the parting line (13) using a first cutting blade (18) after performing the holding step, thereby forming a first cut groove (23) which has a bottom that does not reach the metal element (21); and a second cutting step to cut the plate-shaped workpiece (11) along the first cut groove (23) using a second cutting blade (18, 18A) after performing the first cutting step, thereby forming a second cut groove (25, 26) which completely cuts the plate-shaped workpiece (11) along the parting line (13) so that the metal element (21) is divided; in contrast to the first cutting step, only the second cutting step includes the step of supplying a cutting fluid (22) containing an organic acid and an oxidizing agent to the plate-shaped workpiece (11). [2] Machining method for a plate-shaped workpiece according to claim 1, wherein the second cutting blade (18A) is the same as the first cutting blade (18). [3] Machining method for a plate-shaped workpiece (11) according to claim 1, wherein the second cutting blade (18A) has a thickness that is smaller than that of the first cutting blade (18).

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