JP5225711B2 - Laser dicing sheet and chip body manufacturing method - Google Patents

Description

  The present invention also refers to a dicing sheet (hereinafter referred to as “laser dicing sheet”) suitably used for fixing an object to be cut (hereinafter referred to as “work”) when dicing a workpiece with laser light into a chip. And a method for manufacturing a chip body suitably performed using the laser dicing sheet.

  Laser dicing has attracted particular attention in recent years because it sometimes cuts workpieces that are difficult to cut by blade dicing. Various dicing sheets used for such laser dicing have been proposed (Patent Documents 1 to 3).

  In laser dicing, a workpiece fixed on a dicing sheet is scanned with a laser beam to cut the workpiece (dicing). At this time, the focal point of the laser beam moves as follows. That is, acceleration is performed from the surface of the dicing sheet (outer edge portion of the workpiece) to which the workpiece is not attached, the workpiece surface is scanned at a constant speed, and the deceleration is stopped at the other outer edge portion of the workpiece. Thereafter, the traveling direction is reversed, and after acceleration, the workpiece surface is scanned, and then decelerated, stopped, and reversed again.

  Therefore, at the time of acceleration / deceleration in the movement of the laser beam focus, the laser beam is directly applied to the end of the dicing sheet to which no workpiece is attached. At this time, there is a problem that the end of the dicing sheet is cut by the laser beam, or the laser beam is transmitted through the dicing sheet to damage the chuck table. Furthermore, the surface of the dicing sheet in contact with the chuck table heated by the laser beam may be melted and fused to the chuck table.

In order to avoid these problems, a technique has been adopted in which a thick dicing sheet is used to increase the distance between the workpiece and the chuck table surface (Patent Document 4). In this method, the base material has a two-layer structure of an expanded film and a protective film, thereby increasing the thickness of the dicing sheet. Since a thick substrate is used at the time of laser dicing, the laser beam that has reached the chuck table is not focused, and therefore the energy density is low, so that the chuck table is not damaged. Moreover, the above-mentioned problem of fusion of the dicing sheet does not occur. After the laser dicing is completed, the protective film constituting the substrate is peeled off, and then the expansion and the chip are picked up. However, after the laser dicing is completed, one of the constituent layers of the substrate needs to be peeled off, which complicates the process. In addition, the expanded film may be cut by laser light during laser dicing, and expansion may not be performed.
JP 2002-343747 A JP 2005-236082 A JP 2005-252094 A JP 2006-245487 A

  The present invention seeks to solve the problems associated with the prior art as described above. That is, the present invention relates to a laser dicing sheet capable of preventing cutting of a dicing sheet by laser light, damage to the chuck table and fusion of the dicing sheet to the chuck table in laser dicing, and a chip body by a laser dicing method using the same. It aims at providing the manufacturing method of.

  The gist of the present invention aimed at solving such problems is as follows.

(1) a base material made of polyester (meth) acrylate, which is a cured product obtained by irradiating an energy beam to a compound containing an energy beam curable ester (meth) acrylate oligomer and an energy beam curable monomer; A laser dicing sheet comprising an adhesive layer formed on one side thereof.
(2) The laser dicing sheet according to (1), wherein the energy ray-curable ester (meth) acrylate oligomer is a polyether ester (meth) acrylate oligomer.
(3) The ether bond portion of the polyether ester (meth) acrylate oligomer is an alkyleneoxy group (-(-RO-) n-: where R is an alkylene group having 1 to 6 carbon atoms, and n is 2 to 2. 200), the laser dicing sheet according to (2).
(4) The laser dicing sheet according to (3), wherein the alkylene group R of the alkyleneoxy group (-(-RO-) n-) is ethylene, propylene, butylene, or tetramethylene.
(5) A workpiece is attached to the pressure-sensitive adhesive layer of the laser dicing sheet according to any one of (1) to (4) above,
A method for manufacturing a chip body, wherein a chip is manufactured by dividing a workpiece into pieces by laser light.

  In the present invention, since polyester (meth) acrylate is used as the constituent resin of the base material, even if the base material is irradiated with laser light, damage to the base material is small and not cut. Even if the substrate is not damaged, the amount of light that passes through the substrate and reaches the chuck table is reduced. As a result, in laser dicing, cutting of the dicing sheet by laser light, damage to the chuck table, and fusion of the dicing sheet to the chuck table are prevented, and the manufacturing process of the chip body by laser dicing can be performed smoothly.

  The present invention will be described more specifically. The laser dicing sheet according to the present invention includes a base material and a pressure-sensitive adhesive layer formed thereon. In the laser dicing sheet of the present invention, the substrate is made of a resin film containing polyester (meth) acrylate as a main constituent component.

  Hereinafter, the polyester (meth) acrylate film which comprises the base material of the laser dicing sheet of this invention is demonstrated concretely. In the present specification, “(meth) acryl” is used to mean both acrylic and methacrylic.

(Polyester (meth) acrylate film)
The polyester (meth) acrylate film constituting the base material of the laser dicing sheet of the present invention is prepared by forming a composition containing an energy ray-curable ester (meth) acrylate oligomer and an energy ray-curable monomer, and then forming the compound. A cured product obtained by irradiation with energy rays is preferred.

  The energy ray-curable ester (meth) acrylate oligomer is obtained by reacting a polyol compound such as a polyester type or a polyether type with (meth) acrylic acid. The energy ray curable ester (meth) acrylate oligomer can also be obtained by reacting (meth) acrylic acid with a prepolymer obtained by reacting a polyol compound and a polyvalent carboxylic acid.

  The polyol compound may be any of an alkylene diol, a polyether type polyol, a polyester type polyol, and a polycarbonate type polyol, but a better effect can be obtained by using the polyether type polyol. The polyol is not particularly limited, and may be a bifunctional diol or a trifunctional triol, but it is particularly preferable to use a diol from the viewpoint of availability, versatility, reactivity, and the like. . Accordingly, polyether type diols are preferably used.

  The polyether type diol is generally represented by HO-(-R-O-) n-H. Here, R is a divalent hydrocarbon group, preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms, and particularly preferably an alkylene group having 2 or 3 carbon atoms. Examples of the alkylene group having 1 to 6 carbon atoms include methylene, ethylene, methylmethylene, propylene, trimethylene, ethylmethylene, butylene, tetramethylene, 1-methyltrimethylene, 2-methyltrimethylene, 1,1-dimethylethylene. 1,2-dimethylethylene, n-propylmethylene, isopropylmethylene, pentamethylene, hexamethylene and the like, among which ethylene, propylene, butylene or tetramethylene are preferred, and ethylene or propylene is particularly preferred. Further, n is preferably 2 to 200, more preferably 10 to 100. Accordingly, particularly preferable polyether type diols include polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol, and more particularly preferable polyether type diols include polyethylene glycol and polypropylene glycol.

  Polyether-type diol is an energy ray-curable polyether-type ester that induces an ether bond (-(-RO-) n-) by reaction with (meth) acrylic acid and has a (meth) acryloyl group at the terminal. A (meth) acrylate oligomer is produced. Such an ether bond may have a structure derived from a ring-opening reaction of a cyclic ether such as ethylene oxide, propylene oxide, and tetrahydrofuran.

  The resulting polyether type ester (meth) acrylate oligomer is represented by the general formula: Z—X—Z (where X is a structural unit derived from a polyether type diol, and Z is (meth) acrylic acid). A (meth) acryloyl group derived from

  The polyether-type ester (meth) acrylate oligomer can also be obtained by reacting (meth) acrylic acid with a prepolymer obtained by reacting the above polyol compound with a polyvalent carboxylic acid. The polyol compound is the same as described above, and examples of the polyvalent carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid, phthalic acid, trimellitic acid, and tricarbaryl. Acids, 1,3,5-benzenetricarboxylic acid, oxydicarboxylic acids such as malic acid and tartaric acid, oxytricarboxylic acids such as citric acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, tetraethylenepenta Minheptaacetic acid and the like. Particularly preferred are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid and fumaric acid which do not have an aromatic ring.

  The polyether-type diol induces an ether bond portion (-(-R-O-) n-) by reaction with a polyvalent carboxylic acid to generate an ether bond-containing prepolymer.

  Subsequently, an ether bond-containing prepolymer and (meth) acrylic acid are reacted to obtain a polyether-type ester (meth) acrylate oligomer. The resulting polyether-type ester (meth) acrylate oligomer is represented by the general formula: Z- (Y- (XY) m) -Z (where X is a structural unit derived from a polyether-type diol). Y is a structural unit derived from a polyvalent carboxylic acid, and Z is a (meth) acryloyl group derived from (meth) acrylic acid. In the above general formula, m is preferably selected to be 1 to 200, more preferably 1 to 50.

  The obtained polyether type ester (meth) acrylate oligomer has a photopolymerizable double bond in the molecule, and has a property of being polymerized and cured by irradiation with energy rays to form a film.

  The weight average molecular weight of the polyether ester (meth) acrylate oligomer preferably used in the present invention is in the range of 1000 to 50000, more preferably 2000 to 40000. Said polyether-type ester (meth) acrylate oligomer can be used individually by 1 type or in combination of 2 or more types.

  In many cases, it is difficult to form a film only with the polyether-type ester (meth) acrylate oligomer as described above. In the present invention, after diluting with an energy ray-curable monomer to form a film, this is cured. Get a film. The energy ray curable monomer has an energy ray polymerizable double bond in the molecule, and in the present invention, an acrylic ester compound having a relatively bulky group is preferably used.

  Specific examples of the energy ray-curable monomer used for diluting such a polyether type ester (meth) acrylate oligomer include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl ( Alicyclic compounds such as (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantane (meth) acrylate, aromatic compounds such as phenylhydroxypropyl acrylate, benzyl acrylate, phenol ethylene oxide modified acrylate, or Heterocyclic compounds such as tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, N-vinylpyrrolidone or N-vinylcaprolactam can be mentioned. Moreover, you may use polyfunctional (meth) acrylate as needed. Such energy ray-curable monomers may be used alone or in combination.

  The energy ray curable monomer is preferably 5 to 900 parts by weight, more preferably 10 to 500 parts by weight, and particularly preferably 30 to 200 parts by weight with respect to 100 parts by weight of the ester (meth) acrylate oligomer. Used.

  The polyester (meth) acrylate film constituting the substrate is obtained by forming and curing a blend containing an ester (meth) acrylate oligomer and an energy ray curable monomer. At this time, by mixing a photopolymerization initiator in the blend, it is possible to reduce the polymerization curing time and energy beam irradiation amount by energy beam irradiation. Examples of such photopolymerization initiators include photoinitiators such as benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds, and photosensitizers such as amines and quinones. Specifically, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyldiphenyl sulfide, tetramethyl Examples include thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone, 1,2-diphenylmethane, 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

  The amount of the photopolymerization initiator used is preferably 0.05 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the ester (meth) acrylate oligomer and the energy ray curable monomer. Parts, particularly preferably 0.3 to 5 parts by weight.

  Moreover, you may add metal fillers, such as inorganic fillers, such as a calcium carbonate, a silica, and a mica, iron, and lead, in the above-mentioned compound. Furthermore, in addition to the above components, the substrate may contain additives such as colorants such as pigments and dyes.

  As the film forming method, a technique called casting film formation (cast film formation) can be preferably employed. Specifically, after a liquid compound (resin before curing, resin solution, etc.) is cast into a thin film on a process sheet, for example, the coating film is irradiated with energy rays such as ultraviolet rays and electron beams for polymerization. A base material can be produced by curing to form a film. According to such a manufacturing method, the stress applied to the resin during film formation is small, and the formation of fish eyes is small. Moreover, the uniformity of the film thickness is also high, and the thickness accuracy is usually within 2%.

  In addition, in order to improve the adhesiveness with the adhesive on the upper surface of the base material, that is, the surface on which the adhesive layer is provided, a primer layer is provided with an ethylene vinyl acetate copolymer or the like. Also good. Moreover, you may use the laminated film which has another film and coating film on the opposite surface to an adhesive layer as a base material. The laser dicing sheet according to the present invention is manufactured by providing a pressure-sensitive adhesive layer on the base material as described above. When the pressure-sensitive adhesive layer is composed of an ultraviolet curable pressure-sensitive adhesive, the substrate needs to be transparent to ultraviolet rays. In the laser dicing sheet of the present invention, the thickness of the substrate is not particularly limited as a solution means of the present invention, but is preferably 10 to 500 μm, more preferably 30 to 300 μm, particularly preferably from the viewpoint of workability. 50-200 μm.

  The pressure-sensitive adhesive layer can be formed of various conventionally known pressure-sensitive adhesives. Such an adhesive is not limited at all, but an adhesive such as rubber-based, acrylic-based, silicone-based, or polyvinyl ether is used. In addition, an energy ray curable adhesive, a heat-foaming adhesive, or a water swelling adhesive can be used.

  As the energy ray curable (ultraviolet ray curable, electron beam curable) pressure-sensitive adhesive, it is particularly preferable to use an ultraviolet curable pressure-sensitive adhesive.

  The thickness of the pressure-sensitive adhesive layer is preferably 1 to 100 μm, more preferably 3 to 80 μm, and particularly preferably 5 to 50 μm. In addition, in order to protect an adhesive layer before the use, the peeling sheet may be laminated | stacked on the adhesive layer.

  The release sheet is not particularly limited. For example, a film made of a resin such as polyethylene terephthalate, polypropylene, or polyethylene or a foamed film thereof, paper such as glassine paper, coated paper, laminated paper, silicone-based, fluorine A system and a release agent such as a long chain alkyl group-containing carbamate can be used.

  The method of providing the pressure-sensitive adhesive layer on the surface of the substrate may be to transfer the pressure-sensitive adhesive layer formed by applying on the release sheet so as to have a predetermined film thickness to the surface of the substrate, or to apply directly to the surface of the substrate. A pressure-sensitive adhesive layer may be formed.

  Next, a method for manufacturing a chip body using the laser dicing sheet of the present invention will be described.

  In the manufacturing method of the chip body of the present invention, a workpiece is attached to the pressure-sensitive adhesive layer of the laser dicing sheet, the workpiece surface is scanned with laser light, and the workpiece is cut to obtain a chip body. Such a laser dicing method itself is known. In laser dicing, the focal point of laser light moves as follows. That is, acceleration is performed from the exposed surface (outer edge portion of the workpiece) of the dicing sheet to which the workpiece is not attached, the workpiece surface is scanned at a constant speed, and is decelerated and stopped at the other outer edge portion of the workpiece. Thereafter, the traveling direction is reversed, and after acceleration, the workpiece surface is scanned again, and then decelerated, stopped, and reversed again. Usually, laser beam scanning is performed about once to a plurality of times per dicing line.

  At the time of acceleration / deceleration in the movement of the laser beam focus, the laser beam is directly applied to the end of the dicing sheet to which no workpiece is attached. At this time, the laser beam sometimes cuts the dicing sheet. In addition, there is a problem that the laser beam is transmitted through the dicing sheet and damages the chuck table. Furthermore, the surface of the dicing sheet in contact with the chuck table heated by the laser beam may be melted and fused to the chuck table.

  However, in this invention, said subject is solved by using the polyester (meth) acrylate film mentioned above as a base material of a laser dicing sheet. That is, when the laser dicing sheet of the present invention was used, it was confirmed that the substrate was not easily damaged by the laser light even if the laser light was directly irradiated onto the laser dicing sheet. Specifically, only a part of the substrate surface is cut by laser light, and the substrate is not cut. Further, laser light having high energy did not pass through the base material to reach the chuck table, and no fusion of the laser dicing sheet was confirmed.

  After laser dicing is completed, the laser dicing sheet is expanded as necessary to widen the chip interval. By widening the chip interval, damage due to contact between chips is reduced. Thereafter, the chip is picked up and taken out to obtain a chip body. In the case where the pressure-sensitive adhesive layer is made of an ultraviolet curable pressure-sensitive adhesive, ultraviolet irradiation is performed before pick-up as necessary. The ultraviolet curable pressure-sensitive adhesive is polymerized and cured by irradiation with ultraviolet rays, and the adhesive force is reduced, so that the chip can be picked up smoothly.

  The workpiece applicable in the present invention is not limited as long as the workpiece can be cut by laser light. For example, a semiconductor wafer, a glass substrate, a ceramic substrate, an organic material substrate such as an FPC, or a precision component. Various articles, such as metal materials, etc. can be mentioned.

  A laser is a device that generates light having a uniform wavelength and phase, such as a solid-state laser such as YAG (fundamental wavelength = 1064 nm) or ruby (fundamental wavelength = 694 nm), or an argon ion laser (fundamental wavelength = 1930 nm). Gas lasers and their harmonics are known, and various lasers can be used in the present invention.

  In the present invention, since the polyester (meth) acrylate film is used as the constituent resin of the base material, even when the base material laser light is irradiated, the damage to the base material is small, and the chuck table is transmitted through the base material. The amount of light reaching up to is reduced. As a result, in laser dicing, damage to the chuck table due to laser light and fusion of the dicing sheet to the chuck table are prevented, and the manufacturing process of the chip body by laser dicing can be performed smoothly.

(Example)
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

  In the following examples and comparative examples, the following compositions were used as pressure-sensitive adhesives.

[Adhesive composition]
Polyvalent isocyanate for a 30% toluene solution of a copolymer (weight average molecular weight 700,000) consisting of 84 parts by weight of butyl acrylate, 10 parts by weight of methyl methacrylate, 1 part by weight of acrylic acid and 5 parts by weight of 2-hydroxyethyl acrylate 5.5 parts by weight of a compound (Coronate L (manufactured by Nippon Polyurethane Co., Ltd.)) was mixed to obtain an adhesive composition.

  Moreover, the laser dicing conditions and the evaluation method of a dicing result are shown below.

[Laser dicing conditions]
・ Equipment: Nd-YAG laser ・ Chuck table material: Quartz ・ Wavelength: 355 nm (third harmonic)
・ Output: 5.5W
・ Repetition frequency: 10kHz
・ Pulse width: 35nsec
・ Irradiation frequency: 2 times / 1 line ・ Cutting speed: 200mm / sec
・ Defocus amount: + 50μm from the tape surface (focus on the wafer surface)
・ Wafer material: Silicon ・ Wafer thickness: 50 μm
・ Wafer size: 6 inches ・ Cut chip size: 5 mm
・ Laser scanning distance outside the wafer: 5mm
[Incision depth evaluation]
After laser dicing was completed, the cut line was cross-sectionally observed, and the depth of cut from the surface of the sheet including the adhesive layer was measured (the observation site was a portion where the wafer was not applied and the laser was directly irradiated). What has been cut is indicated as “cut”.

[Damage of chuck table]
After the laser dicing was completed, the table surface was visually observed to check for damage. The table with no damage was designated as “A”, and the table with damage was designated as “B”.

[Fusion to chuck table]
When removing a wafer with a laser dicing sheet from the dicing table using the transfer mechanism built into the laser dicing device after laser dicing, the case where there was no problem with the transfer was designated as “A”, and the laser dicing sheet was thermally fused to the table for smooth The item that was difficult to convey was designated as “B”.

Example 1
Polypropylene glycol (PPG: weight average molecular weight 1,000) and acrylic acid (AAc) were prepared in a molar ratio of PPG: AAc = 1: 2. These were reacted to obtain a polyether-type ester acrylate oligomer.

  Next, 50 parts by weight of the above polyether ester acrylate oligomer, 50 parts by weight of energy ray curable monomer (isobornyl acrylate), and 0.5 parts by weight of photoinitiator (Darocur 1173, manufactured by Ciba Specialty Chemicals) And a coating solution for forming a coating film was obtained.

The above coating solution was applied by a fountain die method onto a polyethylene terephthalate (PET) film (SP-PET3801 manufactured by Lintec Co., Ltd.), which had been subjected to silicone release treatment, to a thickness of 80 μm to form a resin composition layer. Immediately after coating, a PET film that has been subjected to the same silicone release treatment is laminated on the resin composition layer, and then energy is applied using a high-pressure mercury lamp under the conditions of an illuminance of 250 mW / cm ² and a light intensity of 600 mJ / cm ^2. The resin composition layer was crosslinked and cured by irradiating with rays (ultraviolet rays) to obtain a base film having a thickness of 80 μm.

  The release films laminated on both sides were peeled before transferring the adhesive layer described later.

  Separately, the above-mentioned pressure-sensitive adhesive composition was applied and dried (100 ° C., 1 minute) on a PET film (SP-PET3801 manufactured by Lintec Co., Ltd.) subjected to silicone release treatment so that the dry film thickness was 10 μm.

  The pressure-sensitive adhesive layer was transferred onto the base film from which the release film was peeled off to obtain a laser dicing sheet.

  The PET film (SP-PET3801 manufactured by Lintec Co., Ltd.) on the adhesive layer was peeled off, a 50 μm thick silicon wafer was attached, and laser dicing was performed under the above conditions. The results are shown in Table 1.

(Example 2)
Instead of the polyether-type ester acrylate oligomer of Example 1, polytetramethylene glycol (PTMG: weight average molecular weight 2,000) and acrylic acid (AAc) were reacted at PTMG: AAc = 1: 2 (molar ratio). The same operation as in Example 1 was performed except that the obtained polyether type ester acrylate oligomer was used. The results are shown in Table 1.

(Comparative Example 1)
The same operation as in Example 1 was performed, except that a polyvinyl chloride film having a thickness of 100 μm (containing 25% by weight of dioctyl phthalate as a plasticizer) was used as the base film. The results are shown in Table 1.

(Comparative Example 2)
The same operation as in Example 1 was performed except that an ethylene-methacrylic acid copolymer film (methacrylic acid copolymerization ratio 9% by weight) having a thickness of 100 μm was used as the base film. The results are shown in Table 1.

  The laser dicing sheets of Examples 1 and 2 were not cut, and the damage to the chuck table and the fusion to the chuck table were not observed. The laser dicing sheet of Comparative Example 1 was cut and the chuck table was damaged and fused to the chuck table. The laser dicing sheet of Comparative Example 2 was not cut, but damage to the chuck table and fusion to the chuck table were observed by the laser light transmitted through the dicing sheet.

Claims (5)

  A base material made of polyester (meth) acrylate, which is a cured product obtained by irradiating an energy ray to a compound containing an energy ray curable ester (meth) acrylate oligomer and an energy ray curable monomer, on one side thereof A laser dicing sheet comprising a formed pressure-sensitive adhesive layer.   The laser dicing sheet according to claim 1, wherein the energy ray-curable ester (meth) acrylate oligomer is a polyether-type ester (meth) acrylate oligomer.   The ether bond portion of the polyether ester (meth) acrylate oligomer is an alkyleneoxy group (-(-RO-) n-: where R is an alkylene group having 1 to 6 carbon atoms, and n is an integer of 2 to 200. The laser dicing sheet according to claim 2.   The laser dicing sheet according to claim 3, wherein the alkylene group R of the alkyleneoxy group (-(-R-O-) n-) is ethylene, propylene, butylene, or tetramethylene. Affixing a workpiece on the adhesive layer of the laser dicing sheet according to any one of claims 1 to 4,
A method for manufacturing a chip body, wherein a chip is manufactured by dividing a workpiece into pieces by laser light.