JP2009224659A - Method of dividing work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of dividing a work which causes no fragments of a chip during grinding processing and causes no damage to the chip when peeling off a protection film from the chip. <P>SOLUTION: In the method, devices are formed in a plurality of regions demarcated by division schedule lines formed in a lattice-like structure on the surface thereof, into individual chips. The method includes steps of: cutting the division schedule lines of the work to form cutting grooves having a depth equivalent to a finish thickness of the chips; applying solventless hydrophilic resin in a liquid or viscoelastic state on the surface of the work where the cutting grooves are formed; hardening the hydrophilic resin; grinding the rear face of the work, exposing the cutting grooves formed in the surface of the work on the rear face, to divide the work into individual chips; and bringing the hydrophilic resin into contact with warm water at 40°C or above to eliminate the hydrophilic resin from each chip. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wafer that divides a wafer (workpiece) in which devices are respectively formed in a plurality of regions partitioned by a predetermined division line formed in a lattice shape on the surface into individual chips (devices) along the predetermined division line. It is related to the division method.

  For example, in a semiconductor device manufacturing process, devices such as IC and LSI are formed in a plurality of regions partitioned by streets (division lines) formed in a lattice shape on the surface of a semiconductor wafer having a substantially disk shape, Individual chips are manufactured by dividing each region in which each device is formed along a predetermined division line.

  As a dividing device that divides a semiconductor wafer into individual chips, a cutting device called a dicing device is generally used. This cutting device uses a cutting blade having a very thin cutting edge to cut the semiconductor wafer along a predetermined dividing line. To cut. The chips thus divided are packaged and widely used in electric devices such as mobile phones and personal computers.

  In recent years, electric devices such as mobile phones and personal computers are required to be lighter and smaller, and a thinner chip is required. As a technique for dividing a wafer into thinner chips, a dividing technique called a so-called dicing method has been developed and put into practical use (see, for example, Japanese Patent Laid-Open Nos. 62-4341 and 64-38209).

  This tip dicing method is a semiconductor in which a dividing groove having a predetermined depth (a depth corresponding to the finished thickness of the chip) is formed along the line to be divided from the surface of the semiconductor wafer, and then the dividing groove is formed on the surface. This is a technique of grinding the back surface of a wafer to expose a dividing groove on the back surface and dividing the wafer into individual chips, and the chip thickness can be processed to 100 μm or less.

  In relation to such a tip dicing method, Japanese Patent Laid-Open No. 6-85055 discloses that a cut groove formed on the surface of the wafer is filled with an ultraviolet curable resin, and a protective tape is applied to the surface of the wafer during backside grinding. The technology to wear is disclosed.

  Japanese Patent Application Laid-Open No. 10-50642 discloses a protective member having a three-layer structure that is attached to the surface of the wafer during back grinding of the wafer, although the technique is not limited to the tip dicing method.

Japanese Patent Laid-Open No. 2003-332280 discloses that a protective member used when grinding a back surface of a wafer is attached to the surface of a wafer using an adhesive having a melting temperature of 40 ° C. to 95 ° C. A method for supporting a semiconductor wafer is disclosed.
JP-A-62-4341 JP-A 64-38209 JP-A-6-85055 Japanese Patent Laid-Open No. 10-50642 JP 2003-332280 A

  In the conventional tip dicing method, that is, after forming a cutting groove on the surface of the wafer, a protective adhesive tape is applied to the surface of the wafer, the back surface of the wafer is ground, and the divided grooves are exposed on the back surface. In some cases, the fixing strength of the wafer was weak and chip jumping occurred.

  Further, when the wafer is divided into individual chips and then peeled off from the protective adhesive tape, the semiconductor chip may be damaged due to damage due to residual adhesive force or contamination due to adhesive residue.

  The present invention has been made in view of the above points, and the object of the present invention is to prevent chip jumping during grinding and to prevent damage to the chip when peeling the chip from the protective film. It is to provide a work dividing method.

  According to the present invention, there is provided a workpiece dividing method for dividing a workpiece in which devices are respectively formed in a plurality of regions partitioned by division lines formed in a lattice shape on a surface into individual chips, the workpiece being divided Cutting the planned line to form a cutting groove having a depth corresponding to the finished thickness of the chip, and the cutting groove of the workpiece is formed in a liquid or viscoelastic state with a solvent-free hydrophilic resin. Applying to the surface, curing the hydrophilic resin, grinding the back surface of the workpiece to expose the cutting groove formed on the surface of the workpiece on the back surface, and dividing the workpiece into individual chips, There is provided a method for dividing a workpiece, comprising the steps of removing the hydrophilic resin from each chip by bringing the hydrophilic resin into contact with warm water of 40 ° C. or higher.

  Preferably, the hydrophilic resin is a water-soluble thermoplastic resin that liquefies at 40 ° C. or higher, and the step of applying the resin is performed in a state where the thermoplastic resin is at 40 ° C. or higher and the resin is cured. Is performed by making the thermoplastic resin lower than 40 ° C., and the step of removing the resin from each chip is performed by liquefying the thermoplastic resin.

  As an alternative, the hydrophilic resin is a water-swellable ultraviolet curable resin that is cured by ultraviolet rays, and the step of applying the resin is performed before the ultraviolet curable resin is irradiated with ultraviolet rays to cure the resin. The step is performed by irradiating the ultraviolet curable resin with ultraviolet rays, and the step of removing the resin from each chip is performed by removing the ultraviolet curable resin from each chip by water swelling.

  According to the present invention, when the workpiece is fixed by the hydrophilic resin during the back grinding of the workpiece, the resin enters the fixing groove and is fixed. As a result, the workpiece can be fixed more firmly than the conventional method in which the protective tape is applied to the surface side of the workpiece and the workpiece is fixed, and the occurrence of chip skipping can be prevented.

  In addition, since the resin is a hydrophilic resin and can be easily removed from the workpiece by contact with warm water of 40 ° C. or higher, the residual adhesive force does not apply stress to the chip, and the adhesive remains. It does not contaminate the chip.

  Hereinafter, a preferred embodiment of a workpiece dividing method according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a perspective view of a semiconductor wafer as a workpiece.

  The semiconductor wafer 2 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 600 μm, and a plurality of division lines 4 are formed in a lattice shape on the surface 2a. On the surface 2a of the semiconductor wafer 2, devices (chips) 6 such as ICs and LSIs are formed in a plurality of regions partitioned by a plurality of division lines 4 formed in a lattice shape.

  In the work (wafer) dividing method according to the embodiment of the present invention, a cutting groove forming step is first performed as a first step. That is, a cutting groove having a predetermined depth (a depth corresponding to the finished thickness of each chip) is formed along the planned dividing line 4 formed on the surface 2a of the wafer 2 by a so-called tip dicing method.

  This cutting groove forming step is performed using a cutting device 10 shown in FIG. The cutting apparatus 10 shown in FIG. 2A includes a chuck table 8 that includes suction holding means and is movable in the X-axis direction, a cutting unit 12, and moves integrally with the cutting unit 12 in the Y-axis direction and the Z-axis direction. A possible alignment unit 14 is included.

  The cutting unit 12 includes a spindle 16 that is rotationally driven by a motor (not shown), and a cutting blade 18 that is attached to the tip of the spindle 16. The alignment unit 14 includes an imaging unit 20 such as a CCD camera.

  In order to carry out the cutting groove forming process, the semiconductor wafer 2 is placed on the chuck table 8 with its surface 2a facing up. Then, the wafer 2 is held on the chuck table 8 by operating a suction means (not shown).

  In this way, the chuck table 8 that sucks and holds the wafer 2 is positioned directly below the imaging means 20 by a cutting feed mechanism (not shown). When the chuck table 8 is positioned immediately below the image pickup means 20, an alignment operation for detecting a cutting region in which a cutting groove is to be formed in the wafer 2 is performed by the image pickup means 20 and a control means (not shown).

  That is, the imaging unit 20 and a control unit (not shown) execute image processing such as pattern matching for aligning the division line 4 formed in a predetermined direction of the wafer 2 with the cutting blade 18, and cutting. Perform region alignment. Further, the alignment of the cutting area is performed in the same manner with respect to the division lines 4 extending in the direction perpendicular to the predetermined direction formed on the wafer 2.

  After such alignment, the chuck table 8 holding the wafer 2 is moved to the cutting start position in the cutting area. Then, the cutting blade 18 moves downward while rotating in the direction indicated by the arrow 21 in FIG.

  The cutting feed position is set such that the outer peripheral edge of the cutting blade 18 is a depth position (for example, 100 μm) corresponding to the finished thickness of the device (chip) from the surface 2 a of the wafer 2.

  When the cutting blade 18 is cut and fed in this way, the chuck table 8 is cut and fed in the X-axis direction, that is, in the direction indicated by the arrow X1 in FIG. As shown in FIG. 2B, a cutting groove 22 having a depth (for example, 100 μm) corresponding to the finished thickness of the device is formed along the planned dividing line 4 (cutting groove forming step). This cutting groove forming step is performed along all the division lines 4 formed on the wafer 2. FIG. 3 shows a top perspective view of the wafer 2 obtained as a result.

  As described above, when the cutting groove 22 having a predetermined depth is formed on the surface 2a of the wafer 2, a resin coating step of applying a solvent-free hydrophilic resin to the surface 2a of the wafer 2 is performed. That is, as shown in FIG. 4, the wafer 2 is mounted on the spinner table 7 with the surface 2 a side up, and the wafer 2 is sucked and held by the spinner table 7. Then, a solventless hydrophilic resin 9 is dropped on the wafer 2 while rotating the spinner table 7 to form a resin film 24 having a uniform thickness on the surface 2 a of the wafer 2.

  The resin coating method is not limited to the spin coating method, and for example, a roll coating method, a dip coating method, a bar coating method, a spray coating method, or the like can be employed. The resin may be applied directly to the wafer 2 or may be applied to the wafer after the resin is applied to the film.

  Here, “solvent-free” means that no solvent is used when the resin is produced. The hydrophilic resin of the present invention contains a hydrophilic thermoplastic resin and a hydrophilic ultraviolet curable resin. Examples of hydrophilic thermoplastic resins (water-soluble hot melts) include polyvinyl alcohol resins or derivatives thereof, polyether polyols, diols including polyester polyols, organic acids or organic acid salts, carbonates, alcohols, and surfactants. Etc. can be used alone or as a mixture.

  When used alone as a water-soluble thermoplastic resin, its melting point or softening point must be 40 ° C. or higher. When used as a mixture, a substance having a melting point or softening point of 40 ° C. or higher is 10% by weight or more. It is preferable to include.

As the polyvinyl alcohol, PVA having various degrees of polymerization and saponification can be used as long as the adhesive strength to the adherend and the coating property are not impaired.
Examples of the polyether polyol include polyoxypropylene glycol obtained by adding propylene oxide and ethylene oxide, polyoxypropylene glycerin, polyoxytetramethylene glycol, polyoxyalkylene triol, polyethylene glycol, polytetramethylene glycol and the like. It is done.

  The polyester polyol is a reaction product of one or more kinds of polycarboxylic acids and one or more kinds of polyols.

  Examples of the polycarboxylic acid include oxalic acid, malonic acid, succinic acid, glutamic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonamethylene dicarboxylic acid, decamethylene dicarboxylic acid, and undecamethylene dicarboxylic acid. And dodecamethylene dicarboxylic acid.

  Examples of the diol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1, Examples include 9-nonanediol and 1,10-decanediol.

  Examples of the carbonate ester include dimethyl carbonate, diethyl carbonate, ethylene carbonate (ethylene carbonate), and propylene carbonate (propylene carbonate).

  Examples of organic acids or organic acid salts include rosin derivatives derived from these rosins, such as gum rosin, wood rosin, tall oil rosin, disproportionated rosin, hydrogenated rosin, and polymerized rosin. The rosin derivative includes a compound in which a carboxyl group remains or is introduced, for example, an ester of rosin and a polyhydric alcohol, a reaction product of rosin and a polybasic acid, a rosin-maleic anhydride adduct and a polyhydric alcohol. Examples thereof include esters and esters produced by reacting rosin and maleic anhydride in the presence of a polyhydric alcohol.

  Moreover, the fatty acid which is carboxylic acid which can be represented with general formula CnHmCOOH, its salt, etc. are mention | raise | lifted. Examples of the alcohols include aliphatic alcohols such as higher alcohols, ethoxylated and propoxylated alcohols, and aromatic alcohols such as phenols, phenol oligomers, and derivatives.

  Examples of the surfactants include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant.

  In addition, as the water-swellable ultraviolet curable resin that is cured by ultraviolet rays, the following resins can be employed.

  (Bifunctional) 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentanediol di (meth) acrylate, 1,6-hexanediol di (meth) Acrylate, 1,9-nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, di (Meth) acryloyl isocyanurate, neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, 2-ethyl-2-butyl-propanediol (meth) acrylate, neopentyl glycol di (meth) acrylate, Ripropylene glycol di (meth) acrylate, 2,2-bis (4- (meth) acryloxydiethoxyphenyl) propane, 2,2-bis (4- (meth) acryloxypropoxyphenyl) propane, 2,2- Bis (4- (meth) acryloxytetraethoxyphenyl) propane, tetraethylene glycol di (meth) acrylate and the like.

  Examples of (trifunctional) include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, and tris (acryloyloxyethyl) isocyanurate.

  (4 or more functional groups) include ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meta) ) Acrylate and the like.

  When a water-soluble thermoplastic resin is used as the hydrophilic resin, the resin coating step is performed by heating the thermoplastic resin to 40 ° C. or higher, and cooling to less than 40 ° C. to cool the surface 2a of the wafer 2 The resin applied to is cured.

  On the other hand, when a water-swellable ultraviolet curable resin is used as the hydrophilic resin, the ultraviolet curable resin is applied on the surface 2a of the wafer 2, and then the resin is cured by irradiation with ultraviolet rays.

  Even when a water-soluble thermoplastic resin that is liquefied at 40 ° C. or higher is used as the resin to be applied onto the surface 2a of the wafer 2, or when a water-swelling ultraviolet curable resin is used, the resin is the cutting groove of the wafer 2. Therefore, when the wafer 2 is sucked and held with the chuck table facing down with the chuck table when the back surface 2b of the wafer 2 is ground, the wafer 2 can be firmly fixed.

  After the resin film 24 is formed on the front surface 2a of the wafer 2, the back surface 2b of the wafer 2 is ground, and the cutting groove 22 is divided into individual chips 6 by exposing the cutting groove 22 to the back surface 2b. Perform the process. As shown in FIG. 5A, this cutting groove exposing step is performed by a grinding device 26 including a chuck table 28 and a grinding unit 30.

  The grinding unit 30 includes a mounter 32 fixed to the tip of a spindle 33 and a grinding wheel 36 fixed to the mounter 32 with bolts 34.

  In this cutting groove exposing step, the back surface 2b of the wafer 2 is held on the chuck table 28. For example, while rotating the chuck table 28 in the direction indicated by the arrow 29 at 300 rpm, the grinding wheel 36 is indicated by the arrow 31. Rotating at 6000 rpm in the direction shown, the grinding wheel 36 is brought into contact with the back surface 2b of the wafer 2 to grind the back surface 2b of the wafer 2. This grinding is performed until the cutting groove 22 appears on the back surface 2b of the wafer 2 as shown in FIG.

  By grinding until the cutting groove 22 is exposed in this way, the wafer 2 is divided into individual chips 6 as shown in FIG. In addition, since the resin film 24 is affixed to the surface 2a of the plurality of divided chips 6, the form of the wafer 2 is maintained without being separated.

  After the back surface 2b of the wafer 2 is ground by the grinding device 26 and the cutting groove exposing process for dividing the wafer 2 into individual chips 6 is performed, the resin film peeling process for peeling the resin film 24 from the chips 6 is performed. To do.

  This resin film peeling step is performed using, for example, a chuck table 40 and a suction head 46 as shown in FIG. As shown in FIG. 6A, the chuck table 40 has a porous suction portion 42 and a recess 44.

  While the resin film 24 is sucked and held by the porous suction portion 42 of the chuck table 40, hot water of 40 ° C. or higher is filled in the concave portion 44 as shown in FIG. At this time, the resin film 24 is applied to warm water of 40 ° C. or higher while the chips 6 are sucked by the suction heads 46 having the suction ports 48 corresponding to the chips 6. The chip 6 can be reliably held by the suction head 46.

  Next, a comparison result when the back surface of the wafer is ground when the water-swellable ultraviolet curable resin or water-soluble thermoplastic resin (water-soluble hot melt) of the present invention is used as a protective film and when a conventional UV tape is used. Is shown below.

Example 1
Table 1 shows the results of measuring the groove width (kerf width) after the back surface grinding of the wafer using each protective film. The kerf width before grinding is 20 μm, and the chip size after grinding is 10 × 10 mm.

  From Table 1, it was confirmed that the ultraviolet curable resin and the water-soluble hot melt of the present invention have less chip displacement than conventional UV tapes and can firmly fix the chip.

Example 2
After half-cut dicing of the front surface 2a of the wafer 2, a protective film made of the resin of the present invention and a protective film made of a conventional UV tape are attached to the surface of the wafer, the back surface of the wafer is ground, and the wafer is divided into chips. The state of each wafer and chip in the peeling process was observed. The results are shown in Table 2.

  From Table 2, by adopting the UV curable resin or water-soluble hot melt of the present invention as the protective film, the wafers can be individually separated without causing chip jumping during back surface grinding and without causing adhesive residue when the protective film is peeled off. It was confirmed that it can be divided into chips.

Example 3
The peelability and solubility according to the water temperature of the ultraviolet curable resin and the water-soluble hot melt in the peeling process were measured. The results are shown in Table 3.

  From Table 3, it was confirmed that the protective film (resin film) can be easily peeled and dissolved by setting the water temperature to 40 ° C. or higher. Accordingly, the protective film could be removed without applying stress to the chip by immersing the protective film in warm water of 40 ° C. or higher.

The following effects can also be expected when the resin film of the present invention is employed as a protective film to be attached to the surface of the wafer 2.
(1) Since the resin film of the present invention does not use an organic solvent, it can be said that the load on the environment is small, that is, it is environmentally friendly.
(2) It is effective because it can be fixed according to the shape even for a non-planar workpiece having bumps on the surface.
(3) Since the adhesiveness is high, it is possible to prevent processing waste from entering between the workpiece and the resin. Furthermore, mixing of bubbles can be prevented.
(4) Even if cutting chips remaining in the dicing groove remain in the cutting groove, the cutting chips do not come out after grinding because they are hardened with resin.

It is a surface side perspective view of a semiconductor wafer. FIG. 2A is an explanatory diagram of the cutting groove forming step, and FIG. 2B is a cross-sectional view of the wafer in which the cutting grooves are formed. It is the surface side perspective view of the wafer in which the cutting groove was formed. It is explanatory drawing of a resin application | coating process. FIG. 5A is an explanatory diagram of a cutting groove exposing process for grinding the back surface of the wafer, FIG. 5B is a cross-sectional view of the state where the cutting groove is exposed on the back surface of the wafer by grinding, and FIG. FIG. 3 is a perspective view of the wafer in a state where cutting grooves are exposed on the back surface of the wafer. It is explanatory drawing of a resin film peeling process.

Explanation of symbols

2 Semiconductor wafer 4 Divided line 6 Chip (device)
8 Chuck table 9 Hydrophilic resin 10 Cutting device 12 Cutting unit 14 Alignment unit 18 Cutting blade 20 Imaging means 22 Cutting groove 24 Resin tape (protective tape)
26 Grinding device 36 Grinding wheel 40 Chuck table 46 Suction head

Claims (3)

A work dividing method for dividing a work in which devices are respectively formed in a plurality of regions partitioned by dividing lines formed in a lattice shape on a surface into individual chips,
Cutting the division line of the workpiece to form a cutting groove having a depth corresponding to the finished thickness of the chip,
Applying a solventless hydrophilic resin to the surface of the workpiece where the cutting grooves are formed in a liquid or viscoelastic state,
Curing the hydrophilic resin;
Grinding the back surface of the workpiece to expose the cutting grooves formed on the surface of the workpiece on the back surface and dividing the workpiece into individual chips;
Removing the hydrophilic resin from each chip by contacting the hydrophilic resin with warm water of 40 ° C. or higher;
A work dividing method characterized by comprising each step. The hydrophilic resin is a water-soluble thermoplastic resin that liquefies at 40 ° C. or higher,
The step of applying the resin is performed in a state where the thermoplastic resin is 40 ° C. or higher,
The step of curing the resin is performed by making the thermoplastic resin less than 40 ° C.,
2. The method for dividing a workpiece according to claim 1, wherein in the step of removing the resin from each chip, the thermoplastic resin is liquefied and removed. The hydrophilic resin is a water-swellable ultraviolet curable resin that is cured by ultraviolet rays,
The step of applying the resin is performed before irradiating the ultraviolet curable resin with ultraviolet rays,
The step of curing the resin is performed by irradiating the ultraviolet curable resin with ultraviolet rays,
2. The method for dividing a workpiece according to claim 1, wherein in the step of removing the resin from each chip, the ultraviolet curable resin is peeled off and removed from each chip by water swelling.

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