Method for processing substrate

Abstract

[Project] When processing a substrate with metal formed on a planned splitting line along the planned splitting line, the burr is appropriately removed from around the processing groove of the substrate, and the work efficiency of burr removal is also improved. [Solution] A method for processing a substrate having metal formed on a planned division line along a planned division line, comprising a processing groove forming step of forming a processing groove in the substrate along the planned division line, and, after performing the processing groove forming step, a etching solution containing at least an oxidizing agent and subjected to ultrasonic vibration is brought into contact with the substrate, thereby removing the metal burrs generated around the formed processing groove by modifying them with the oxidizing agent included in the etching solution to suppress ductility and weaken them, and also removing them by ultrasonic vibration.

Description

Technology Field

[0001] The present invention relates to a method for processing a substrate, wherein a substrate having metal formed on a line to be divided is processed along a line to be divided. Background Technology

[0002] When forming a processing groove on a substrate that includes metal parts, metal films, or wiring composed of metal, burrs are generated on the metal parts, and problems arise such as short circuits between chip terminals caused by the generated burrs, or bonding defects caused by burrs falling onto bonding pads during handling of the workpiece. For this reason, a device for removing burrs by spraying high-pressure water from a nozzle onto the burrs has been proposed (see, for example, Patent Document 1). Prior art literature

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-125667 The problem to be solved

[0004] However, even if the technology disclosed in Patent Document 1 is used, it is difficult to properly remove burrs around the machining groove, and it is inefficient because a person has to inspect the machining groove and remove the burrs after the machining groove is formed.

[0005] Accordingly, the objective of the present invention is to provide a method for processing a substrate in which, when processing a substrate having metal formed on a planned split line along the planned split line, burrs are appropriately removed from a full-cut or half-cut substrate and the work efficiency of burr removal can also be improved. means of solving the problem

[0006] According to the present invention, a method for processing a substrate having a metal formed on a planned division line is provided, comprising: a processing groove forming step of forming a processing groove in the substrate along the planned division line; and, after the processing groove forming step, a etching solution to which ultrasonic vibration is applied and which includes at least an oxidizing agent is contacted with the substrate, thereby suppressing ductility and weakening metal burrs generated around the formed processing groove by modifying them with the oxidizing agent included in the etching solution, and removing them by the ultrasonic vibration.

[0007] Preferably, the etching solution further contains an organic acid.

[0008] Preferably, the etching solution further includes a corrosion inhibitor.

[0009] Preferably, the burr removal step involves immersing a substrate having the processing groove formed thereon or a plurality of chips fragmented by the processing groove in a tank having an ultrasonic oscillator that stores the etching solution and imparts the ultrasonic vibration.

[0010] Preferably, the etching rate of the burr is controlled by the composition ratio of the etching solution comprising the oxidizing agent and at least one of the organic acid or the anti-corrosion agent. Effects of the invention

[0011] According to the present invention, burrs can be effectively removed and the work efficiency of burr removal can also be improved.

[0012] By including an organic acid in addition to the oxidizing agent in the etching solution used in the burr removal step, the effect of etching for burr removal can be increased.

[0013] By including an anti-corrosion agent in addition to the oxidizing agent in the etching solution used in the burr removal step, unnecessary etching of the device surface of the chip can be slowed down.

[0014] In the burr removal step, the removal of burrs can be performed effectively in a short time by immersing a substrate with a processing groove or a plurality of chips formed by the processing groove in a tank having an ultrasonic oscillator that stores an etching solution and applies ultrasonic vibration. Brief explanation of the drawing

[0015] FIG. 1 is a plan view illustrating an example of a substrate on which processing is performed. FIG. 2 is a side view illustrating an example of a processing groove forming step in which a processing groove is formed along a planned division line on a substrate by blade dicing. Figure 3 is a side view illustrating another example of a processing groove forming step in which a processing groove is formed along a line to be divided on a substrate by laser dicing. FIG. 4 is a cross-sectional view illustrating an example of a burr removal step using a tank in which an etching solution is stored. Specific details for implementing the invention

[0016] The substrate (90) shown in FIG. 1, on which the splitting process is performed, is, for example, a QFN (Quad Flat Non-leaded package) substrate. The substrate (90) has a frame plate (900) with a rectangular shape. On the surface (901) of the substrate (90) shown in FIG. 1, a plurality of device regions (902), which become individual chips (909) equipped with devices by being split, are formed side by side in the longitudinal direction of the substrate (90) (three in the example shown). Each device region (902) is surrounded by a portion (903) of a material that is cut into small pieces and discarded.

[0017] The device area (902) is divided by a plurality of mutually orthogonal division lines (904), and on the division lines (904), a metal (905) constituting a plurality of electrode pads, etc., connected to each device not shown, is disposed. Each metal (905) is insulated from each other by a mold resin not shown on the frame plate (900). Then, the substrate (90) is divided into a mold resin that seals a device not shown and a chip (909) having a plurality of cut metals (905) by cutting the plurality of metals (905) at the center along the division lines (904). Additionally, an oxide film or resin film, such as SiO2 with a thickness in the μm range, may be formed in the device area (902) as a device protective film.

[0018] For example, as shown in FIG. 2, the back surface (907) (see FIG. 2) of the substrate (90) is attached to the adhesive surface (surface) of the dicing tape (91). The outer periphery of the dicing tape (91) is attached to the annular frame (92) shown in FIG. 1 and FIG. 2, and accordingly, the substrate (90) is supported by the annular frame (92) through the dicing tape (91) and becomes a frame unit (9) capable of handling using the annular frame (92). And, the center of the annular frame (92) and the center of the substrate (90) are roughly aligned.

[0019] Additionally, the substrate (90) on which processing is performed may not be a frame unit (9) and may be in a state where it is a substrate alone. Furthermore, the substrate (90) may have a TEG (Test Element Group) formed by combining transistors or resistors, etc., and composed of a metal such as aluminum or copper, formed on the planned division line (904), for example, at a predetermined interval. The TEG is divided through an unillustrated wiring layer made of metal, etc., and is connected to a chip (909) equipped with a device. In addition, the metal formed on the planned division line (904) of the substrate (90) may be wiring in addition to the examples above, and the substrate (90) may be a package substrate in which a device is laminated on the surface of a metal substrate other than a QFN substrate and resin-sealed, or a package substrate in which a metal film is coated as a heat sink on the surface of the substrate on which the planned division line is formed.

[0020] (1-1) First embodiment of the processing groove forming step

[0021] The cutting device (1) illustrated in FIG. 2 is a device capable of performing cutting work on a substrate (90), and is equipped with at least a holding unit (15) for holding the substrate (90) and a cutting unit (11) for cutting the substrate (90) with a rotatable cutting blade (112). In addition, FIG. 2 illustrates a simplified structure of the frame unit (9).

[0022] The holding unit (15) is provided with a flat holding surface (150) that holds, for example, a substrate (90), and is rotatable about an axis of rotation in the vertical direction (Z-axis direction) and is also capable of reciprocating in the X-axis direction (front-back direction of the ground) by a cutting feed means not shown. The holding unit (15) may be a porous chuck in which the holding surface (150) is made of a porous material, or a jig chuck in which the holding surface (150) is provided with a blade undercut. In addition, around the holding unit (15) shown in FIG. 2, fixing clamps (153) capable of gripping and fixing an annular frame (92) when the substrate (90) is a frame unit (9) as in the present embodiment are provided evenly at equal intervals, for example, in the circumferential direction, four of which are provided.

[0023] The cutting unit (11) is capable of indexing feed in the Y-axis direction and cutting feed in the Z-axis direction (vertical direction), and is equipped with at least a cutting blade (112) that rotates and cuts into, for example, a substrate (90), a rotatable spindle (113) that supports the cutting blade (112) mounted on the tip, and a motor not shown. The cutting blade (112) may be an annular washer blade or a hub blade.

[0024] For example, near the cutting unit (11), an alignment means not shown is provided to detect a planned division line (904) (see FIG. 1) of a substrate (90) held in a holding unit (15). The alignment means can detect the position of the planned division line (904) of the surface (901) by image processing, such as pattern matching, based on an image of the surface (901) of the substrate (90).

[0025] In the step of forming a processing groove for blade dicing, a substrate (90) made of a frame unit (9) is first placed on the holding surface (150) of a holding unit (15), and a suction force generated by a suction source not shown is transmitted to the holding surface (150), so that the substrate (90) is suctioned and held on the holding surface (150). The center of the substrate (90) and the center of the holding surface (150) roughly coincide. In addition, the annular frame (92) of the frame unit (9) is clamped and fixed to a fixing clamp (153).

[0026] For example, a holding unit (15) that holds the substrate (90) rotates so that the longitudinal direction of the substrate (90) becomes the X-axis direction, and then, as the holding unit (15) that holds the substrate (90) is sent in the -X direction (backward of the ground), a coordinate position in the Y-axis direction of a target division planned line (904) extending in the X-axis direction that causes the cutting blade (112) to be inserted is detected by an alignment means not shown.

[0027] Next, the cutting blade (112) is aligned with the target division line (904) in the Y-axis direction, and the cutting blade (112) is rotated at high speed in a counterclockwise direction, for example, when viewed from the +Y direction side. Additionally, the cutting unit (11) is fed in the -Z direction, and the bottom end of the cutting blade (112) is positioned at a height where it cuts the substrate (90) completely and is slightly cut into the dicing tape (91). Alternatively, the substrate (90) may be cut in half.

[0028] As the substrate (90) shown in FIG. 2 is also sent in the -X direction (back of the ground) at a predetermined cutting feed rate, the cutting blade (112) cuts into the substrate (90) along the planned division line (904) and cuts the substrate (90) while forming the processing groove (95) shown in FIG. 2. Since a metal (905), such as an electrode pad, is placed on the planned division line (904) shown in FIG. 1, the metal (905) becomes a beard-shaped burr (96), for example, shown in FIG. 2, due to its ductility, and is formed around the processing groove (95), that is, on the inner surface of the processing groove (95) or the upper part of the processing groove (95).

[0029] When the frame unit (9) is sent to a predetermined position on the -X direction side where the cutting blade (112) shown in FIG. 2 completes cutting a line of planned division (904), the cutting feed of the substrate (90) is stopped once to separate the cutting blade (112) from the substrate (90), and then the substrate (90) is moved in the +X direction to return to the origin position. Then, by sequentially performing cutting in the same manner while indexing the cutting blade (112) in the -Y direction at intervals of adjacent lines of planned division (904), the substrate (90) is cut along all lines of planned division (904) in the X-axis direction.

[0030] In addition, the holding unit (15) is rotated 90 degrees and the same type of cutting is performed, so that all planned division lines (904) are cut vertically and horizontally, and the substrate (90) is divided into a chip (909) equipped with a device.

[0031] (1-2) Second embodiment of the processing groove forming step

[0032] Instead of forming a processing groove (95) on the substrate (90) by the above cutting, the step of forming the processing groove may be performed using, for example, a laser processing device (2) shown in FIG. 3. The laser processing device (2) is equipped with at least a chuck table (20) that holds the substrate (90) and a laser beam irradiation unit (22) capable of irradiating a laser beam of, for example, having an absorptive wavelength onto the substrate (90) held on the chuck table (20).

[0033] A chuck table (20) having a flat holding surface (200) in communication with an unillustrated suction source is rotatable and is also capable of reciprocating in the X-axis direction, which is the processing transfer direction, and the Y-axis direction, which is the indexing transfer direction, by means of an unillustrated transfer means.

[0034] The laser beam irradiation unit (22) can accurately concentrate and irradiate a laser beam at a target location on a substrate (90) held by a chuck table (20) by causing a laser beam emitted from a laser oscillator (229) to be incident on a focusing lens (not shown) inside a focusing device (221) through a transmission optical system. The height position of the laser beam focusing point can be adjusted in the Z-axis direction by a focusing point position adjustment means (not shown).

[0035] In the laser processing device (2), the substrate (90) is held by suction on the holding surface (200) of the chuck table (20) with its surface (901) facing upward. Additionally, the annular frame (92) is clamped and fixed by a fixing clamp (204) installed on the chuck table (20). Subsequently, the position of the planned division line (904), which serves as a reference for irradiating the laser beam, is detected by an alignment means not shown. Then, the chuck table (20) is indexed and moved in the Y-axis direction, and alignment is achieved between the planned division line (904) for irradiating the laser beam and the condenser (221) in the Y-axis direction.

[0036] In addition, the height position of the point of concentration of the laser beam, which is concentrated by a non-concentrating lens, is aligned with, for example, the height position of the surface (901) of the substrate (90). Then, the laser oscillator (229) emits a laser beam of a wavelength that is absorbent to the substrate (90), and concentrates and irradiates the laser beam onto the planned split line (904).

[0037] Additionally, the substrate (90) is sent in the forward direction -X direction (backward of the surface) at a predetermined processing feed rate, and a laser beam is irradiated onto the surface (901) of the substrate (90) along the planned division line (904), so that the substrate (90) is ablated from the surface (901) toward the back side (907), and a processing groove (97) is formed to cut the substrate (90), for example, along the planned division line (904). Additionally, the processing groove (97) may be a half-cut groove. At the same time, since a metal (905), such as an electrode pad, is placed on the planned division line (904) shown in FIG. 1, the metal (905) is formed as a molten burr (98) around the processing groove (97), that is, on the inner surface of the processing groove (97) or the upper part of the processing groove (97).

[0038] When the substrate (90) moves in the -X direction to a predetermined position where the laser beam is irradiated along the planned division line (904), the irradiation of the laser beam is stopped. Additionally, the chuck table (20) is indexed and moved in the +Y direction for a predetermined distance so that the point of focus of the condenser (221) is positioned directly below the next target planned division line (904). Then, the substrate (90) is processed and moved in the +X direction (front of the ground), which is the direction of return, and the substrate (90) is ablated along the planned division line (904) in the same way as the laser beam irradiation in the forward direction, and a processing groove (97) is formed along the planned division line (904). Then, by sequentially performing laser processing in the same manner while indexing and moving the chuck table (20) in the -Y direction at intervals of adjacent planned division lines (904), the substrate (90) is cut along all planned division lines (904) extending in the X-axis direction. In addition, laser irradiation on a line scheduled for division (904) may be performed in two or more passes.

[0039] In addition, the chuck table (20) is rotated 90 degrees and laser processing is performed in the same manner, so that all planned division lines (904) are cut vertically and horizontally, and the substrate (90) is divided into a chip (909) equipped with a device.

[0040] (2) Burr removal step

[0041] After the processing groove forming step of the first embodiment or the processing groove forming step of the second embodiment is performed, the frame unit (9) is returned to the tank (5) shown in FIG. 4. For example, the tank (5), which can immerse the entire substrate (90) supported by an annular frame (92), is composed of a side wall (51) and a bottom plate (50) integrally connected to the lower part of the side wall (51), and the etching liquid (500) is stored therein.

[0042] A placement table (52) is provided on the bottom plate (50). The placement table (52) has a placement surface (521) parallel to the X-axis and Y-axis planes. A frame unit (9) is placed on the placement surface (521). An etching solution (500) is supplied to the tank (5) from an etching solution supply source not shown. The tank (5) has a drain port (511) for draining the etching solution (500), for example, on a side wall (51). The drain port (511) is formed at a position higher than the placement surface (521) of the placement table (52) and higher than the upper surface of the frame unit (9) placed on the placement surface (521). Accordingly, the frame unit (9) placed on the placement surface (521) is entirely immersed in the etching solution (500) stored in the tank (5). In the tank (5), a new etching solution (500) is supplied from an etching solution source not shown, and the old etching solution (500) is gradually drained from the drainage port (511).

[0043] On the lower side (-Z direction side) of the placement surface (521), an ultrasonic oscillation unit (53) formed in a disc shape by arranging, for example, a plurality of piezoelectric elements in a row is installed. A terminal not shown is connected to the ultrasonic oscillation unit (53), and a voltage application unit (55) that applies an alternating voltage through this terminal and wiring is connected. In addition, the shape and installation location of the ultrasonic oscillation unit (53) are not limited to this example. The ultrasonic waves generated by the ultrasonic oscillation unit (53) vibrate the placement surface (521) and act on the frame unit (9) placed on the placement surface (521) from below. Since it is undesirable for the frame unit (9) to come into direct contact with the ultrasonic oscillation unit (53) inside the water tank (5), the placement surface (521) is configured to be inserted between them.

[0044] The etching solution (500) contains at least an oxidizing agent, and in this embodiment, also contains an organic acid and a corrosion inhibitor.

[0045] For example, a compound having at least one carboxyl group and at least one amino group within its molecule may be used as the organic acid. In this case, it is preferable that at least one of the amino groups is a secondary or tertiary amino group. Additionally, the compound used as the organic acid may have substituents.

[0046] Amino acids available for use in 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-alloysoleucine, L-isoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allotreonine, L-homoserine, L-thyroxine, L-tyrosine, 3,5-diiodo-L-tyrosine, β-(3,4-dihydroxyphenyl)-L-alanine, 4-hydroxy-L-proline, L-cystine, L-methionine, Examples include L-thionine, L-lanthionine, L-cystathionine, L-cystine, L-cystineic acid, L-glutamic acid, L-aspartic acid, S-(carboxymethyl)-L-cystine, 4-aminobutyric acid, L-asparagine, L-glutamine, azacerin, L-canavanine, L-citrulline, L-arginine, δ-hydroxy-L-lysine, creatinine, L-kynurenine, L-histidine, 1-methyl-L-histidine, 3-methyl-L-histidine, L-tryptophan, actinomycin C1, ergothioneine, apamin, angiotensin I, angiotensin II, and antipine. Among them, glycine, L-alanine, L-proline, L-histidine, L-lysine, and dihydroxyethylglycine are preferred.

[0047] In addition, examples of aminopoly acids that can be used as organic acids include iminodiacetic acid, nitrilo-triamine-tetraacetic acid, diethylenetriamine-tetraacetic acid, ethylenediamine-tetraacetic acid, hydroxyethyliminodiacetic acid, nitrilotris-methylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenesulfonic acid, 1,2-diaminopropane-tetraacetic acid, glycol-etherdiamine-tetraacetic acid, transcyclohexanediamine-tetraacetic acid, ethylenediamine-orthohydroxyphenylacetic acid, ethylenediamine-disuccinic acid (SS form), β-alanine-diacetic acid, N-(2-carboxylate ethyl)-L-aspartic acid, N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, etc.

[0048] Furthermore, 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, gillycone, hexanoic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, malic acid, succinic acid, pimetic acid, mercaptoacetic acid, glyoxylic acid, chloroacetic acid, pyruvate, acetoacetic acid, glutaric acid, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mesaconic acid, citraconic acid, aconitic acid, benzoic acid, toluic acid, phthalic acid, naphthoic acid, pyromethic acid, and naphthalic acid.

[0049] Oxidizing agents may include, for example, hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, dichromate, permanganate, cerate, vanadate, ozone water, and silver(II) salts, iron(III) salts, or their organic complexes.

[0050] In addition, for the anti-corrosion agent, it is preferable to use, for example, a complex aromatic compound having three or more nitrogen atoms in the molecule and also having a ring-condensed structure, or a complex aromatic compound having four or more nitrogen atoms in the molecule. In addition, it is preferable that the aromatic compound includes a carboxyl group, a sulfo group, a hydroxyl group, or an alkoxy group. Specifically, it is preferable that it be a tetrazole derivative, a 1,2,3-triazole derivative, and a 1,2,4-triazole derivative.

[0051] Examples of tetrazole derivatives that can be used as anti-corrosion agents include those that do not have a substituent on the nitrogen atom forming the tetrazole ring and have an alkyl group introduced at the 5 position of the tetrazole, which is substituted with a substituent selected from the group consisting of a sulfo group, an amino group, a carbamoyl group, a carboxyl group, a carbonamide group, a sulfamoyl group, and a sulfonamide group, or at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carboxyl group, a carboxyl group, a carboxyl group, a carbamoyl group, a sulfonamide group, and a sulfonamide group.

[0052] In addition, 1,2,3-triazole derivatives that can be used as anti-corrosion agents may include those that do not have a substituent on the nitrogen atom forming the 1,2,3-triazole ring and have an alkyl or aryl group introduced at the 4th and / or 5th positions of the 1,2,3-triazole, which is substituted with a substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carboxyl group, a carbonamide group, a sulfamoyl group, and a sulfonamide group, or at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carboxyl group, a carboxyl group, a carboxyl group, a sulfonamide group, a sulfonamide group, and a sulfonamide group.

[0053] In addition, 1,2,4-triazole derivatives that can be used as anti-corrosion agents may include those that do not have a substituent on the nitrogen atom forming the 1,2,4-triazole ring and have an alkyl or aryl group introduced at the 2nd and / or 5th positions of the 1,2,4-triazole, which is substituted with a substituent selected from the group consisting of a sulfo group, a carbamoyl group, a carbonamide group, a sulfamoyl group, and a sulfonamide group, or at least one substituent selected from the group consisting of a hydroxyl group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group, and a sulfonamide group.

[0054] In the burr removal step of the present embodiment, for example as shown in FIG. 4, the frame unit (9) is immersed in the etching solution (500) of the water tank (5) with the substrate (90) facing upward, and the frame unit (9) is placed on the placement surface (521) of the placement table (52). Then, a predetermined voltage is applied from the voltage application unit (55) to the ultrasonic oscillation unit (53), and the ultrasonic oscillation unit (53) vibrates mechanically mainly in the up-and-down direction to generate ultrasonic waves of a predetermined frequency. Then, the generated ultrasonic waves propagate through the etching solution (500) to the substrate (90) divided into chips (909).

[0055] A burr (96) (or burr (98) shown in FIG. 3) made of metal formed around a processing groove (95) (or processing groove (97) shown in FIG. 3) of a substrate (90) is modified (oxidized) by an oxidizing agent included in the etching solution (500), thereby reducing the ductility of the metal. That is, it becomes vulnerable to ultrasonic vibrations. In this embodiment, the burr is etched to become thinner in parallel with the weakening by an etching solution (500) containing an organic acid. As a result, the burr (96) (burr (98)) is removed from the chip (909) by ultrasonic vibrations transmitted from the etching solution (500).

[0056] Additionally, in the burr removal step, the rate at which the burr (96) is etched is controlled, for example, by the composition ratio of the etching solution (500) containing an oxidizing agent, an organic acid, and a corrosion inhibitor. That is, although there is a possibility that the metal parts or metal wiring constituting the product part of the device chip (909) may be etched and damaged by the etching solution (500), by controlling the composition ratio of the etching solution (500) containing an oxidizing agent, an organic acid, and a corrosion inhibitor, and by controlling the time the substrate (90) is immersed in the etching solution (500), damage to the device chip (909) can be prevented, and the burr (96) (burr (98)) can be efficiently removed from the chip (909). This is because the burr (96), which is composed of metal, is formed to protrude thinly and longly from the tip of the chip (909), so the reduction in ductility and weakening caused by the oxidizing agent included in the etching solution (500) proceed more rapidly than the product part of the chip (909). Furthermore, by applying ultrasonic vibration, the thin burr (96) (burr (98)) vibrates and is easily bent, making it possible to efficiently complete the removal of the burr (96) (burr (98)) at a stage before damage occurs to the product part of the device chip (909). In addition, for example, since a device protective film such as an oxide film is often formed on the surface of the device chip (909) in advance, it is difficult to be damaged by the etching solution (500) compared to the burr (96) (burr (98)) part.

[0057] For example, when a substrate (90) is fixed on the back side (907) of a high-rigidity substrate (carrier substrate) made of glass or silicon, and the processing groove forming step of the first embodiment or the processing groove forming step of the second embodiment is performed, in the burr removal step, the substrate (90) divided into chips (909) for each carrier substrate may be immersed in a water tank (5).

[0058] Additionally, in the processing groove forming step of the first embodiment or the processing groove forming step of the second embodiment, if a half-cut groove is formed without completely cutting the substrate (90), the undivided substrate (90) alone may be immersed in the water tank (5). Alternatively, for example, a plurality of chips (909) formed by reorganizing the QFN substrate (90) may be immersed in the water tank (5) as is after releasing the tape support.

[0059] The ultrasonic oscillator (53) installed in the tank (5) is not limited to the disc shape shown in FIG. 4. For example, the ultrasonic oscillator may be an ultrasonic horn that extends and retracts in the Z-axis direction and installed to be immersed in the upper part of the tank (5), and the ultrasonic horn may be moved vertically and horizontally along the processing groove (95) (processing groove (97)) of the substrate (90) placed on the placement table (52) while transmitting ultrasonic vibrations to the etching solution (500), thereby modifying the metal burrs (96) (burrs (98)) generated around the processing groove (95) (processing groove (97)) with an oxidizing agent included in the etching solution (500) to suppress ductility and weaken the material, and at the same time, remove them by ultrasonic vibrations. Additionally, the ultrasonic vibration transmitted to the etching solution (500) proceeds in the -Z direction, reaches the bottom plate (50) of the tank (5), and then reflects from the bottom plate (50) back toward the liquid surface. Accordingly, the ultrasonic waves directed toward the bottom plate (50) (incident waves) and the ultrasonic waves reflected from the bottom plate (50) back toward the liquid surface (reflected waves) overlap each other, creating depths of strong and weak sound pressure within the etching solution (500). Furthermore, depending on the frequency of the ultrasonic waves, the depths of the highest sound pressure within the etching solution (500) exist at regular intervals in the Z-axis direction from the liquid surface. Therefore, the depth of the highest sound pressure in the Z-axis direction within the etching solution (500) from the liquid surface is measured when the liquid surface is set to the 0 position. And, the ultrasonic vibration may be applied by aligning the height position of the substrate (90) placed on the placement table (52) with the depth where the sound pressure is highest in the Z-axis direction within the etching solution (500).

[0060] Additionally, for example, an ultrasonic oscillation unit (53) may be installed on the upper surface of a bottom plate (50), and frame placement units for arranging the annular frame (92) of a frame unit (9) may be installed evenly at predetermined intervals in the circumferential direction in an area outside the upper surface of the bottom plate (50) where the ultrasonic oscillation unit (53) is installed. Then, the frame unit (9) is immersed in the etching solution (500) of a water tank (5) in a direction in which the ultrasonic oscillation unit (53) and the surface (901) of the substrate (90) face each other, and the annular frame (92) is arranged on the upper surface of the frame placement units. Then, voltage is applied to the ultrasonic oscillation unit (53) from the voltage application unit (55), and ultrasonic vibration is imparted to the etching solution (500) from the ultrasonic oscillation unit (53).

[0061] In this case, for example, the metal burr (96) (burr (98)) can be removed by ultrasonic vibration by suppressing ductility and weakening it through modification by an oxidizing agent included in the etching solution (500), and the burr (96) (burr (98)) can be effectively removed by shock waves when bubbles (cavitation bubbles) generated in the etching solution (500) by ultrasonic vibration rise up the processing groove (95) (processing groove (97)) of the substrate (90) and come into contact with and break the burr (96) (burr (98)).

[0062] In addition, contact of the etching solution with the substrate (90) in the burr removal step is not limited to the form of immersing the substrate (90) in a tank (5) containing the etching solution (500). For example, after placing the frame unit (9) on the placement table (52) of the tank (5), the etching solution (500) may be sprayed horizontally and vertically along the processing groove (95) (processing groove (97)) of the substrate (90) from an ultrasonic vibration nozzle provided at the top of the tank (5). In this case, for example, the amount of etching solution (500) used can be reduced, and the burr (96) (burr (98)) can be modified by an oxidizing agent included in the etching solution (500) to suppress ductility and weaken it, and the burr (96) can also be removed from the chip (909) by the impact when the etching solution (500) sprayed with ultrasonic vibration collides with the burr (96).

[0063] As described above, the method for processing a substrate according to the present invention, which processes a substrate (90) having a metal (905) formed on a planned division line (904) along the planned division line (904), comprises a processing groove forming step of forming a processing groove (95) on the substrate (90) by, for example, dicing along the planned division line (904), and a burr removal step after the processing groove forming step, wherein an etching solution (500) containing at least an oxidizing agent and subjected to ultrasonic vibration is contacted to remove a burr (96) of the metal (905) generated around the formed processing groove (95) by modifying it with the oxidizing agent included in the etching solution (500) to suppress ductility and weaken it, and also remove it by ultrasonic vibration. By providing this, the burr (96) can be effectively removed, and the operator does not need to inspect the processing groove (95) line by line for the presence or absence of a burr (96), thereby improving the work efficiency of burr removal.

[0064] In addition, by adding an oxidizing agent to the etching solution (500) used in the burr removal step to include an organic acid, the etching effect on the burr (96) can be increased.

[0065] In addition, by adding the etching solution (500) used in the burr removal step to the oxidizing agent and also including a corrosion inhibitor, unnecessary etching on the device surface that becomes the product part of the chip (909) can be delayed.

[0066] The burr removal step allows for the removal of burrs (96) to be performed effectively in a short time by immersing a substrate (90) with a processing groove (95) formed therein or a plurality of chips (909) formed by the processing groove (95) in a tank (5) having an ultrasonic oscillating unit (53) that stores an etching solution (500) and applies ultrasonic vibration.

[0067] It goes without saying that the method for processing a substrate according to the present invention is not limited to the above embodiments and may be implemented in various other forms within the scope of the technical concept. Furthermore, the configuration of each device used when carrying out the processing method may also be appropriately modified within the scope in which the effects of the present invention can be exhibited. Explanation of the symbols

[0068] 9: Frame unit, 90: Substrate, 900: Frame plate, 901: Surface of substrate, 902: Device area, 903: Single material section, 904: Scheduled split line, 905: Metal, 909: Chip, 907: Back side of substrate, 91: Dicing tape, 92: Annular frame, 95: Machining groove, 96: Burr, 97: Machining groove, 98: Burr, 1: Cutting device, 11: Cutting unit, 113: Spindle, 112: Cutting blade, 15: Holding unit, 150: Holding surface, 153: Fixing clamp, 2: Laser processing device, 20: Chuck table, 200: Holding surface, 22: Laser beam irradiation unit, 229: Laser oscillator, 221: Concentrator, 5: Water bath, 500: Etching solution, 50: Base plate, 51: Side wall, 511: Drain, 52: Placement table, 521: Placement surface, 53: Ultrasonic oscillator, 55: Voltage application unit

Claims

Claim 1 A method for processing a substrate having metal formed on a planned division line, wherein the substrate is processed along the planned division line, the method comprises a processing groove forming step of forming a processing groove on the substrate along the planned division line from the surface side of the substrate, and, after the processing groove forming step, a burr removal step of contacting the substrate with an etching solution containing at least an oxidizing agent and to which ultrasonic vibration is applied, thereby modifying the metal burr generated around the formed processing groove by the oxidizing agent included in the etching solution and weakening it by suppressing ductility, and removing it by the ultrasonic vibration, wherein in the burr removal step, an ultrasonic oscillator for applying the ultrasonic vibration is installed on the upper surface of a bottom plate of a tank in which the etching solution is stored, and the substrate is immersed in the etching solution in a direction in which the ultrasonic oscillator and the surface of the substrate face each other. Claim 2 A method for processing a substrate according to claim 1, characterized in that the etching solution further comprises an organic acid. Claim 3 A method for processing a substrate according to claim 1 or 2, wherein the etching solution further comprises a corrosion inhibitor. Claim 4 A method for processing a substrate according to claim 1, wherein the etching solution further comprises at least one of an organic acid or a corrosion inhibitor, and in the burr removal step, the rate at which the burr is etched is controlled by the composition ratio of the etching solution comprising at least one of the oxidizing agent and the organic acid or the corrosion inhibitor. Claim 5 delete

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