JP2006286900A - Method of manufacturing chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing chips in stable quality with higher manufacturing yield without generation of cracks of wafer and damages of chips from a thin film wafer. <P>SOLUTION: The method of manufacturing chips using the laser beam comprises the steps of (a) adhering an adhesive tape for protection to the side of a pattern surface of the wafer on which circuits are formed, (b) grinding the rear surface of the wafer in the opposite side of the surface where the adhesive tape for protection is adhered, (c) adhering an adhesive tape for wafer dicing on the adhesive tape for protection without peeling the adhesive tape for protection, (d) cutting the wafer together with the adhesive tape for protection into fractional pieces with the laser dicing, and (e) picking up chips from the wafers cut into the fractional pieces. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a chip with high yield and stable quality by preventing wafer breakage and chip damage in a process of manufacturing a very thin chip of 100 μm or less.

  In recent years, the evolution of chips, especially semiconductor chips, to thinner and smaller chips has been remarkable, especially in the case of three-dimensional mounting by thinning and high functionality of mobile phones, etc., and semiconductor IC chips such as memory cards and smart cards. In the case of an IC card with a built-in card, the thickness of the semiconductor chip is required to be 100 μm or less, and it is considered that the needs for the above-mentioned thinning and small chip will further increase as these demands increase in the future.

These semiconductor chips are obtained by thinning a semiconductor wafer to a predetermined thickness through a back grinding process, an etching process, etc., and then dicing into a chip. However, these steps are very complicated, and when a semiconductor device is manufactured using a general apparatus, as shown in FIG.
(1) Affixing the protective adhesive tape to the surface of the wafer on which the circuit is formed (2) Grinding the back surface of the wafer (3) Peeling the protective adhesive tape from the wafer (4) A dicing tape is applied to the back surface of the wafer (5) Dicing and dicing the chip into pieces (6) Picking up and taking out the chip are used.

At this time, when the semiconductor wafer is ground to a thin film of 100 μm or less, it is very fragile, so the wafer is damaged when the protective adhesive tape is peeled off and replaced with the adhesive tape for wafer dicing, or between processes. There is a risk.
On the other hand, for the dicing process, a blade cutting method is generally used in which a semiconductor wafer is cut by a dicing blade. In this case, the cutting resistance by the blade is directly applied to the semiconductor wafer at the time of cutting, but this chipping resistance may cause minute chipping (chipping) in the semiconductor chip. The occurrence of chipping not only impairs the appearance of the semiconductor chip but also possibly damages the circuit pattern on the chip, and has recently been regarded as one of important problems. In particular, when the thinned wafer as described above is made into chips, the allowable chipping limit becomes stricter. This chipping problem is easily presumed to become even more serious.

  As one of the methods for solving such wafer cracking and chipping, various so-called laser dicing methods for cutting a semiconductor wafer with a laser beam have been studied. In this case, since the cutting resistance by the blade is not directly applied to the wafer as in the blade cut method, the occurrence of chipping can be reduced to the maximum. Various methods have already been proposed for this laser beam method (for example, Patent Document 1). However, even with such a method, when the surface protection tape is peeled off from the wafer that has been thinned by polishing, it is still necessary to devise another method.

  Further, a method of attaching a dicing tape to the surface of a wafer and performing grinding and dicing is disclosed (for example, Patent Document 2). In this method, dicing is performed separately from a laser dicing apparatus for reducing chipping. A grinding apparatus capable of fixing the work frame is necessary, and it cannot be carried out by an existing grinding apparatus widely used for grinding the back surface, so that a large-scale capital investment is required.

JP 2004-268104 A JP 2004-079746 A

  An object of the present invention is to provide a method of manufacturing a chip having a high yield and a stable quality without causing a wafer crack or a chip damage from a thinned wafer.

  As a result of repeated investigations to solve the above problems, the present inventors applied a protective adhesive tape to the wafer and ground the back surface in the chip manufacturing process, and then attached the protective adhesive tape. By sticking a wafer dicing adhesive tape on it without peeling it and making it smaller by laser dicing, it solves both the problems of wafer cracking and chip chipping, and enables stable production. I found out.

That is, the present invention
(1) In a method of forming a chip by cutting a wafer using a laser beam, (a) a step of attaching a protective adhesive tape to the pattern surface side of the wafer on which a circuit is formed; and (b) the protective adhesive. A step of grinding the back surface of the wafer opposite to the surface on which the tape is applied, and (c) a step of attaching the adhesive tape for wafer dicing on the protective adhesive tape without peeling off the protective adhesive tape. And (d) cutting the protective adhesive tape by laser dicing, cutting the wafer into small pieces, and (e) picking up chips from the cut wafer. Method,
(2) The chip according to (1), wherein the substrate film used for the wafer dicing adhesive tape has a multilayer structure of two or more layers, one of which is a layer that is not cut by a laser. Manufacturing method,
(3) The method for manufacturing a chip according to (1) or (2), wherein the thickness of the wafer after grinding the wafer is 100 μm or less,
(4) The method for manufacturing a chip according to any one of (1) to (3), wherein the adhesive strength of the protective adhesive tape is lower than the adhesive strength of the dicing adhesive tape,
(5) The method for producing a chip according to any one of (1) to (4), wherein the resin composition constituting the pressure-sensitive adhesive of the protective pressure-sensitive adhesive tape is a radiation curable type,
(6) The method for producing a chip according to any one of (1) to (5), wherein the resin composition constituting the adhesive of the dicing tape is non-reactive with respect to radiation,
Is to provide.

  According to the chip manufacturing method of the present invention, the number of steps involved in manufacturing a semiconductor chip can be reduced, and both problems of wafer cracking and chip chipping can be solved, and stable manufacturing can be achieved.

  FIG. 1 is a schematic view in the process of the present invention. The present invention includes (a) a step of attaching a protective adhesive tape to the pattern surface side of a wafer on which a circuit is formed, (b) a step of grinding the back surface of the wafer attached with the protective adhesive tape, c) a step of attaching a wafer dicing adhesive tape on the protective adhesive tape without removing the protective adhesive tape; (d) a step of cutting and fragmenting the wafer by laser dicing; and (e) a small piece. And a step of picking up a chip from the formed wafer.

  In the present invention, first, a protective adhesive tape is attached to the pattern surface side of a wafer on which a circuit is formed. As the protective adhesive tape used here, as long as the substrate film can be cut by a laser, known materials can be arbitrarily used as long as they are general protective adhesive tapes. The substrate film used in the adhesive tape has different laser transmittance in each wavelength region depending on the material thereof, so it is necessary to select appropriately according to the wavelength of the laser used. Specifically, when the wavelength range of the laser used is 400 nm or less, the base film of the adhesive tape is polyvinyl chloride, polyester, a resin having an ester component as a copolymer component, various thermoplastic elastomers, or these Can be used. When the wavelength range of the laser to be used is 400 nm or more, cutting with a laser becomes possible by using a polyethylene multi-component copolymer such as polyethylene or EMMA, an ionomer resin, or a resin material blended with these. Moreover, even if it is a material with a high transmittance | permeability with respect to the wavelength of a laser beam, it becomes possible by mix | blending an absorption imparting agent.

  As the adhesive provided on the substrate film, when the protective adhesive tape is peeled off from the chip that has been cut into pieces after the thinning grinding and dicing, the chip is damaged or the adhesive remains on the circuit surface due to the adhesive remaining. The adhesive is not particularly limited as long as it does not cause problems such as, but radiation, preferably ultraviolet rays, the adhesive exhibits a three-dimensional network, the adhesive strength is reduced, and the adhesive after the peeling on the chip surface It is preferable to use an ultraviolet curable pressure-sensitive adhesive that hardly generates a residue. As such a radiation curable pressure-sensitive adhesive, for example, an acrylic pressure-sensitive adhesive composed of a copolymer of 2-ethylhexyl acrylate and n-butyl acrylate and a (meth) acrylate having an ultraviolet curable carbon-carbon double bond. The thing containing a compound can be mentioned.

Such an acrylic pressure-sensitive adhesive contains a (meth) acrylic copolymer and a curing agent as essential components. The (meth) acrylic copolymer is, for example, a polymer having a (meth) acrylic acid ester as a polymer constituent unit, and a (meth) acrylic polymer of a (meth) acrylic acid ester copolymer, or functionality. Examples include copolymers with monomers, and mixtures of these polymers. As the molecular weight of these polymers, those having a weight average molecular weight of about 500,000 to 1,000,000 are generally applied.
Moreover, a hardening | curing agent is used in order to make it react with the functional group which a (meth) acrylic-type copolymer has, and to adjust adhesive force and cohesion force. For example, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1,3-bis (N, N-diglycidylaminomethyl) toluene, 1,3-bis (N, N-diglycidylaminomethyl) ) Epoxy compounds having two or more epoxy groups in the molecule such as benzene, N, N, N, N′-tetraglycidyl-m-xylenediamine, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate , 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4,4′-diisocyanate, etc., an isocyanate compound having two or more isocyanate groups in the molecule, tetramethylol-tri-β-aziridini Lupropionate, trimethylol-tri-β-aziridinylpropionate, tri Chi trimethylolpropane - tri-.beta.-aziridinyl propionate, trimethylolpropane - aziridine compound having two or more aziridinyl group in the molecule, such as tri-.beta.-(2-methyl aziridine) propionate, and the like. What is necessary is just to adjust the addition amount of a hardening | curing agent according to desired adhesive force, and 0.1-5.0 mass parts is suitable with respect to 100 mass parts of (meth) acrylic-type copolymers.

  Furthermore, as the radiation polymerizable compound, for example, a low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in a molecule that can be three-dimensionally networked by light irradiation is widely used. Trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, 1,6-hexane Diol diacrylate, polyethylene glycol diacrylate, oligoester acrylate, and the like are widely applicable.

  In addition to the above acrylate compounds, urethane acrylate oligomers can also be used. The urethane acrylate oligomer includes a polyol compound such as a polyester type or a polyether type, and a polyvalent isocyanate compound (for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diene). A terminal isocyanate urethane prepolymer obtained by reacting isocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc., with an acrylate or methacrylate having a hydroxyl group (for example, 2-hydroxyethyl) Acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, etc.) Obtained by the reaction.

As a compounding ratio of the acrylic pressure-sensitive adhesive and the radiation-polymerizable compound in the radiation-curable pressure-sensitive adhesive, the radiation-polymerizable compound is preferably 50 to 200 parts by weight, more preferably 50 to 100 parts by weight of the acrylic pressure-sensitive adhesive. It mix | blends in the range of -150 mass parts. In the case of this blending ratio range, the adhesive strength of the pressure-sensitive adhesive layer is greatly reduced after radiation irradiation.
Furthermore, the radiation-curable pressure-sensitive adhesive can be made into a radiation-polymerizable acrylic ester copolymer instead of blending the radiation-polymerizable compound with the acrylic pressure-sensitive adhesive as described above. is there.

When the pressure-sensitive adhesive layer is polymerized by radiation, a photopolymerization initiator such as isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, benzyl methyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxy Methylphenylpropane or the like can be used in combination. By adding at least one of these to the pressure-sensitive adhesive layer, the polymerization reaction can proceed efficiently.
Furthermore, in addition to the photopolymerizable initiator, the radiation curable pressure-sensitive adhesive may contain a photosensitizer, other conventionally known tackifiers, softeners, antioxidants, and the like.
The thickness of the pressure-sensitive adhesive layer is preferably 10 to 200 μm and more preferably 20 to 100 μm in order to improve the adhesion to the step on the circuit surface.

Next, the back surface of the wafer to which the above-described protective tape is attached is ground with a device called a backside grinder to reduce the thickness to a predetermined thickness. When thinning, in order to improve the strength of the wafer, in addition to grinding the backside, any backside polishing / stress relief method using a known etching process (chemical etching, chemical / mechanical etching, dry polishing, plasma etching, etc.) is optional. It may be used.
After grinding the backside of the wafer, a dicing tape is applied on the protective adhesive tape. At this time, as a constituent material of the dicing tape, it is preferable to select a material capable of cutting the protective adhesive tape with respect to the laser, and it is necessary that the base film of the dicing tape is not cut by the laser. As such a film material, it is desirable to use a material that is highly transmissive with respect to the wavelength of the laser in the material used for the surface protection tape. Specifically, when the wavelength range of the laser used is 400 nm or less, polyethylene, a polyethylene multi-component copolymer, an ionomer resin, or a blend thereof can be applied. When the wavelength range of the laser used is 400 nm or more May be polyvinyl chloride, polyester, various thermoplastic elastomers, or those obtained by blending them. Moreover, a base film may be comprised by laminating | stacking these materials, and it may be set as the film from which a base material is not partially cut | disconnected by using these materials for a part of base material.

  The wafer to which the dicing tape is attached is divided into individual chips by a laser dicing apparatus. The wafer is attracted to the table via the dicing tape, and after the dicing position is identified and adjusted by a method of transmitting the wafer such as infrared rays, laser light is incident from the back side of the wafer. As laser dicing equipment, in addition to general laser cutting equipment such as YAG laser, ruby laser, and argon ion laser, the condensing point of the laser light is set in the thickness direction of the wafer, and multiphotons are placed inside the wafer. Various methods such as a method of forming a modified region by absorption and cleaving by natural cleaving or applying a slight external force, or a method in which a water jet is used as a waveguide and a laser is transmitted through the inside to cut the wafer. Can be used.

  Finally, a chip that has been cut into pieces by dicing is picked up. In the pick-up process, a device called a pick-up die bonder that pushes up and collects chips from the dicing tape side with push-up pins is used. However, in the present invention, since the circuit pattern surface of the chips is down, sharp pins are used. Otherwise, it may damage the pattern surface and cause circuit failure. For this reason, it is desirable to collect chips using a pick-up die bonder using a push-up pin with a sharp tip or a needle-less pickup method that does not use a push-up pin.

  In the present invention, since the chip is picked up from the protective adhesive tape, it is desirable that the adhesive strength of the wafer dicing adhesive tape is greater than the adhesive strength of the protective adhesive tape, but the pickup is performed with the protective adhesive tape still attached. A method of peeling off the protective adhesive tape diced with the chip later may be used. In the pick-up process, if the base film is not cut at all during dicing, sufficient expandability cannot be obtained, and there may be a problem during pick-up. For this reason, it is desirable that the base film of the dicing tape has a multilayer structure of two or more layers, and one of the layers is a layer that is not cut by the laser. As a result, the base film is cut as shown in FIG. 2, and the chip interval is expanded by expanding from that portion during expansion, leaving a sufficient interval for the pickup without coming into contact with adjacent chips. It becomes possible.

  Furthermore, among the laser dicing methods, when using a laser dicing method using a water jet, the water jet needs to penetrate the back side of the adhesive tape for supporting and fixing. However, even in the case of this porous substrate film, a multilayer structure in which the layer on the adhesive application side is a layer that can be cut by a laser as shown in FIG. 3 may be used. There is no particular limitation on the method of forming the multilayer structure, and for example, a multilayer structure may be obtained by laminating a layer that is cut by a used laser and a layer that is not cut later.

Hereinafter, it demonstrates in detail using an Example.
The present invention is not limited to the following examples, and can be variously modified.
Example 1
An adhesive was prepared by mixing and stirring 100 parts by mass of an acrylic copolymer, 2.5 parts by mass of a curing agent, 100 parts by mass of a urethane acrylate oligomer, and 2.5 parts by mass of a photopolymerization initiator. This pressure-sensitive adhesive was applied to a base film of a polyester elastomer (trade name manufactured by Toray DuPont, Hytrel 5077: thickness 100 μm) so that the thickness after drying was 30 μm, and a protective pressure-sensitive adhesive tape was prepared. .

  A pressure-sensitive adhesive was prepared by mixing and stirring 100 parts by mass of an acrylic copolymer, 2 parts by mass of a curing agent, 150 parts by mass of a urethane acrylate oligomer, and 1 part by mass of a photopolymerization initiator. The thickness of the pressure-sensitive adhesive after drying is 10 μm on the EMMA side of a base film in which 30 μm of a polyester elastomer (trade name manufactured by Toyobo, Perprene P40H) is laminated on 70 μm of EMMA (trade name, manufactured by Sumitomo Chemical, Aclift WD201). Thus, an adhesive tape for wafer dicing was produced.

  Using these, first, the protective adhesive tape was bonded to an 8-inch bare wafer with DR-8500II (Nitto Denko, trade name), and back grinding (1 axis) with DFG-850 (Disco, trade name) : # 360 finish, 2-axis: # 2000 finish, finish thickness 75 μm). Next, the ground wafer is washed with water, fixed to the stage with the ground surface down, and a wafer dicing adhesive tape is attached to the surface to which the surface protection tape is bonded via a ring frame, and then XSIL The chip was diced to a chip size of 5 mm × 5 mm with a laser dicing apparatus (laser wavelength: 355 nm), and chipping of the chip after dicing was measured.

(Example 2)
A protective adhesive tape was produced in the same manner as in Example 1 except that biaxially stretched PET (trade name S10 (100 μm thickness) manufactured by Toray Industries, Inc.) was used as the base film of the protective adhesive tape.
In addition, a laminated film of 70 μm EMMA (trade name manufactured by Sumitomo Chemical Co., Ltd., Aclift WD201) and 30 μm PVC (trade name manufactured by Kaneka Chemical Co., Ltd., soft vinyl vinyl) is used as the base film for the wafer dicing adhesive tape, and the adhesive film is adhered to the EMMA side. A wafer dicing pressure-sensitive adhesive tape similar to that in Example 1 was prepared except that the agent was applied. Thereafter, a protective adhesive tape was applied to the circuit surface of the wafer, and the back surface was ground. Then, dicing was performed without removing the protective adhesive tape, and then chipping was measured.

(Example 3)
The protective adhesive tape similar to Example 1 was produced except that EVA (manufactured by Nippon Unicar Co., Ltd., trade name NUC-8430: thickness 120 μm) was used as the base film of the protective adhesive tape.
In addition, using a laminated film of EVA (trade name, NUC-8430, manufactured by Nihon Unicar Co., Ltd.) 30 μm and PET fabric (product name: TNo160T, 70 μm) as a base film for wafer dicing adhesive tape, adhesive is applied to the EVA side. The agent was applied to obtain an adhesive tape for wafer dicing. Thereafter, a protective adhesive tape is applied to the circuit surface of the wafer, and the back surface is ground. Thereafter, the wafer dicing tape is applied without peeling off the protective adhesive tape, and the laser dicing apparatus (laser wavelength 1064 nm) manufactured by SYNOVA is used in Example 1. Dicing was performed in the same manner as above to evaluate chipping.

(Comparative Example 1)
A protective pressure-sensitive adhesive tape was produced in the same manner as in Example 1 except that EVA (trade name, NUC-8430: 120 μm in thickness, manufactured by Nippon Unicar Co., Ltd.) was used as the base film for the protective pressure-sensitive adhesive tape. The protective adhesive tape is affixed to the circuit surface of the wafer, and then backside grinding is performed. Subsequently, the protective adhesive tape is not peeled off, and EMMA (trade name, Sumitomo Chemical product name, ACRIFT WD201) is formed on the tape. Adhesive tape for wafer dicing with an adhesive applied to the EMMA side of a laminated film of 70 μm and polyester elastomer (trade name, Toyobo Co., Ltd., 30 μm) is attached to a blade type dicer (trade name, manufactured by DISCO, DAD340). Then, dicing was performed to a chip size of 5 mm × 5 mm, and chipping was measured.

(Comparative Example 2)
Using the same protective adhesive tape and wafer dicing adhesive tape as in Example 1, after grinding the back surface of the wafer, the protective adhesive tape was peeled off and the wafer dicing adhesive tape was bonded to the ground surface side. Dicing was performed in the same manner as in No. 1 to evaluate chipping.

  Of the substrate films, Examples 1 and 2 and Comparative Example 1 were obtained by film forming by the T-die method. The base film for dicing tape of Example 3 and Comparative Example 2 was obtained by laminating each film obtained by the T-die method and a PET fabric by thermocompression bonding with a hot press. The conditions for the heating press were a temperature of 150 ° C., a surface pressure of about 98 kPa, and pressurization for 10 minutes.

Examples 1 to 3: The wafer after back grinding had no cracks and chipping was not observed on the chip after dicing.
Comparative Example 1: No cracking occurred in the wafer after back grinding, but chipping occurred in the chip after dicing, and some of the larger chips exceeded 50% (40 μm) of the chip thickness. The nature was low.
Comparative Example 2: Although there was no crack or the like on the wafer after the back surface grinding, the wafer was cracked when the protective adhesive tape was peeled off.

It is a figure which shows the manufacturing method of the chip | tip of this invention. It is a figure which shows a mode that the notch groove of a base film opens by an expand. It is a figure which shows the adhesive tape for wafer dicing which has a porous layer used for the laser dicing system by a water jet. It is a figure which shows the manufacturing method of the conventional chip | tip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Wafer 1 ': Chip | tip 2: Protection adhesive tape 3: Bonding roller 4: Grinding wheel used for back surface grinding 5: Release tape 6: Adhesive tape for wafer dicing 7: Blade 8: Laser terminal 9: Adhesive 10: Base film 11: Cut groove 11 ': Cut groove expanded by expanding 12: Porous layer 13: Layer cut by laser

Claims (6)

In a method of forming a chip by cutting a wafer using a laser beam, (a) a step of attaching a protective adhesive tape to the pattern surface side of the wafer on which a circuit is formed, and (b) applying the protective adhesive tape Grinding the back surface of the wafer opposite to the attached surface; (c) attaching the wafer dicing adhesive tape on the protective adhesive tape without peeling off the protective adhesive tape; d) A method of manufacturing a chip, comprising the steps of cutting the protective adhesive tape by laser dicing, cutting the wafer into smaller pieces, and (e) picking up the chips from the smaller wafer. 2. The chip production according to claim 1, wherein the base film used for the wafer dicing adhesive tape has a multilayer structure of two or more layers, and one of the layers is a layer that is not cut by a laser. Method. 3. The chip manufacturing method according to claim 1, wherein the thickness of the wafer after grinding the wafer is 100 [mu] m or less. The chip manufacturing method according to any one of claims 1 to 3, wherein the adhesive strength of the protective adhesive tape is lower than the adhesive strength of the dicing adhesive tape. The chip manufacturing method according to any one of claims 1 to 4, wherein the resin composition constituting the pressure-sensitive adhesive for the protective pressure-sensitive adhesive tape is a radiation curable type. The chip manufacturing method according to claim 1, wherein the resin composition constituting the pressure-sensitive adhesive of the dicing tape is non-reactive with respect to radiation.

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