JP2005279757A - Production method for laser processed article and laser processing protection sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for a laser processed article using a laser processing protection sheet capable of effectively preventing contamination on the surface of an article to be processed by decomposition products when the article to be processed is processed by the UV absorption ablation of a laser beam, and also capable of increasing processing precision, and to provide the laser processing protection sheet used to the production method for the laser processed product. <P>SOLUTION: In the production method for a laser processed article, the surface of a base material is at least provided with an adhesive agent layer, and a laser processing protection sheet having a refractive index ratio of ≥1 is used. The method includes a step of bonding the adhesive agent layer for the laser processing protection sheet to the laser beam incident surface side of the organic article to be processed, a step of processing the laser processing protection sheet and the organic article to be processed by irradiating the same with a laser beam, and a step of separating the laser processing protection sheet from the organic article to be processed after the processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to various workpieces such as sheet materials, circuit boards, semiconductor wafers, glass substrates, ceramic substrates, metal substrates, light emitting or receiving element substrates such as semiconductor lasers, MEMS substrates, semiconductor packages, cloth, leather, or paper. Further, the present invention relates to a method of manufacturing a laser processed product obtained by performing shape processing such as cutting, drilling, marking, grooving, scribing, or trimming by ultraviolet absorption ablation of laser light. Moreover, this invention relates to the protection sheet for laser processing used for the said manufacturing method.

  With the recent miniaturization of electrical and electronic equipment, parts are becoming smaller and higher definition. For this reason, high-definition and high-precision processing with an accuracy of ± 50 μm or less has been demanded for external processing of various materials. However, the conventional punching process such as press working has an accuracy of about ± 100 μm at most, and cannot meet the recent demand for higher precision. Also, high-definition and high-precision are required for drilling various materials, and it has become impossible to perform drilling with conventional drills or dies.

  In recent years, various methods for processing various materials using laser light have attracted attention as a solution. In particular, a processing method by ultraviolet absorption ablation of laser light, which has low thermal damage and enables high-definition processing, has attracted attention as a precise outer shape processing method and a fine drilling method.

  As the above technique, for example, as a method for dicing a workpiece, a method is proposed in which the workpiece is supported and fixed on a dicing sheet and the workpiece is diced with a laser beam (Patent Document 1). A method of dicing a semiconductor wafer by combining a water microjet and a laser has also been proposed (Patent Document 2). The dicing sheet described in the patent document is provided on the laser beam emitting surface side of the workpiece, and is used for supporting and fixing the workpiece (laser processed product) during dicing and in each subsequent process. .

By the way, when laser light is used, decomposition products such as carbon generated during laser processing adhere to the surface of the workpiece, and thus a post-treatment called desmear is necessary to remove it. Since the adhesion strength of the decomposed product becomes stronger in proportion to the power of the laser beam, there is a problem that it becomes difficult to remove the decomposed product in the post-treatment when the power of the laser beam is increased. In addition, in the case of a strong decomposition product, wet desmearing with a potassium permanganate aqueous solution or the like is generally performed, but there is also a problem that wet desmear has a large environmental load due to waste liquid treatment or the like. In particular, the surface side (laser light emitting surface side) of the workpiece that contacts the processing table or the adhesive sheet is not only the decomposed product of the workpiece, but also the processed table or adhesive sheet decomposed product by laser light irradiation. There is a tendency to adhere firmly to the surface. Therefore, there existed a problem that the improvement of the through-put of a process was prevented or the reliability of a cutting | disconnection and drilling was reduced.
JP 2002-343747 A JP 2003-34780 A

  The present invention provides a protective sheet for laser processing capable of effectively suppressing contamination of the surface of a workpiece by a decomposition product and increasing processing accuracy when processing the workpiece by ultraviolet absorption ablation of laser light. An object of the present invention is to provide a method for producing a laser-processed product using the above. Another object of the present invention is to provide a protective sheet for laser processing used in the method for manufacturing a laser processed product.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by a method for producing a laser processed product using the following protective sheet for laser processing (hereinafter also referred to as a protective sheet). The invention has been completed.

  That is, the present invention has at least a pressure-sensitive adhesive layer on a substrate, and the refractive index (refractive index ratio = laser) of the substrate at a wavelength of 546 nm with respect to the refractive index of the organic workpiece to be used at a wavelength of 546 nm. Using a protective sheet for laser processing having a refractive index at a wavelength of 546 nm of the substrate of the protective sheet for processing / a refractive index at a wavelength of 546 nm of the organic workpiece to be used) of 1 or more, the laser for the organic workpiece The process of applying the adhesive layer of the protective sheet for laser processing to the light incident surface side, the process of processing the protective sheet for laser processing and the organic workpiece by irradiating laser light, after processing the protective sheet for laser processing The present invention relates to a method for producing a laser processed product including a step of peeling from an organic workpiece.

  The protective sheet is laminated on the laser beam irradiation surface side (laser beam incident surface side) of the organic workpiece before laser processing the organic workpiece by ultraviolet absorption ablation of laser light, and is generated by ablation. It is used to protect the surface of an organic workpiece from decomposed or scattered materials.

  As a protective sheet, what has an adhesive layer at least on a base material is used. By imparting adhesiveness to the protective sheet, it is possible to improve the adhesion at the interface between the protective sheet and the organic workpiece, so that entry of the decomposed material into the interface can be suppressed, and as a result, decomposition occurs. It becomes possible to suppress the contamination of the surface of the organic workpiece by the object.

  In the production method of the present invention, the refractive index at a wavelength of 546 nm of the base material with respect to the refractive index at a wavelength of 546 nm of the organic workpiece used (refractive index ratio = the wavelength of the base material of the protective sheet for laser processing at 546 nm). It is necessary to select and use a protective sheet having a refractive index / a refractive index at a wavelength of 546 nm of the organic work piece to be used. The present inventors have a correlation between the refractive index and laser processability, and by using a protective sheet having the refractive index ratio of 1 or more, the effect of contamination of the surface of the organic workpiece by the decomposed product is effective. It was found that it can be suppressed.

  The refractive index ratio is an important parameter regarding the laser processability between the base material of the protective sheet and the organic workpiece to be used. The higher the refractive index of a solid at a certain wavelength, the slower the speed of light traveling through the solid and the higher the probability of photon absorption. The generation mechanism of laser ablation is due to electron excitation by photon absorption, and it is considered that the laser processability increases as the speed of light traveling through the solid decreases (that is, the refractive index increases).

  As in the present invention, by using a protective sheet having a refractive index ratio of 1 or more, photon absorption at the base material is larger than that of an organic workpiece, and the base material is more easily laser processed. Conceivable.

  The reason why the surface of the organic workpiece can be effectively suppressed by using a protective sheet having a refractive index ratio of 1 or more is considered as follows. Since the protective sheet having a refractive index ratio of 1 or more has a laser processability equal to or higher than that of an organic workpiece, the protective sheet is used simultaneously with the organic workpiece or with a laser beam before the organic workpiece. Etched. Therefore, the decomposition product of the organic workpiece is efficiently scattered from the etched portion of the protective sheet to the outside, and hardly enters the interface portion between the protective sheet and the organic workpiece. As a result, it is considered that contamination of the surface of the organic workpiece can be effectively suppressed.

  The refractive index ratio is preferably 1.05 or more, more preferably 1.1 or more, and particularly preferably 1.2 or more. When the refractive index ratio is less than 1, etching of the organic workpiece proceeds before the protective sheet is cut or perforated. In that case, since there is no scattering path of the decomposition product generated by etching the organic workpiece, the decomposition product enters the interface portion between the protective sheet and the organic workpiece and contaminates the organic workpiece surface. There is a fear. If the surface of the organic workpiece is contaminated with decomposition products as described above, it becomes difficult to peel off the protective sheet from the organic workpiece after laser processing the organic workpiece, or post-processing. It is difficult to remove the decomposed product in the process, and the processing accuracy of the organic workpiece tends to be lowered.

  Further, another invention uses a protective sheet for laser processing that has at least a pressure-sensitive adhesive layer on a substrate and has a refractive index of 1.53 or more at a wavelength of 546 nm of the substrate, and is inorganic. A process of applying an adhesive layer of the protective sheet for laser processing to the laser light incident surface side of the workpiece, a process of processing the protective sheet for laser processing and the inorganic workpiece by irradiating laser light, for laser processing The present invention relates to a method for producing a laser processed product including a step of peeling a protective sheet from a processed inorganic work piece.

  In the present invention, the inorganic workpiece is preferably a circuit board, a semiconductor wafer, a glass substrate, a ceramic substrate, a metal substrate, a semiconductor laser light emitting or receiving element substrate, a MEMS substrate, or a semiconductor package.

  When using an inorganic workpiece, it is difficult to measure the refractive index, but by setting the refractive index of the protective sheet substrate to 1.53 or more, the inorganic workpiece due to a decomposition product is used. Surface contamination can be effectively suppressed. The refractive index of the substrate is preferably 1.57 or more, more preferably 1.60 or more.

  Moreover, in this invention, it is preferable that the base material of the said protective sheet contains an aromatic polymer or silicon rubber. Since the above material has a large refractive index at a wavelength of 546 nm, the refractive index ratio can be adjusted to 1 or more relatively easily.

  In the method for manufacturing a laser processed product of the present invention, the processing is preferably cutting or drilling.

  The present invention also relates to a protective sheet for laser processing used in the method for manufacturing a laser processed product. The protective sheet is preferably used particularly when a semiconductor chip is manufactured by dicing a semiconductor wafer.

  As the laser used in the present invention, a laser capable of ablation processing by absorbing ultraviolet light is used so as not to deteriorate the accuracy and appearance of the hole edge and the cut wall surface of the workpiece due to thermal damage during laser processing. . In particular, it is preferable to use a laser capable of condensing laser light in a narrow width of 20 μm or less and emitting ultraviolet light of 400 nm or less.

Specifically, a laser having an oscillation wavelength of 400 nm or less, for example, a KrF excimer laser with an oscillation wavelength of 248 nm, an XeCI excimer laser with 308 nm, a third harmonic (355 nm) or a fourth harmonic (266 nm) of a YAG laser, or In the case of a laser having a wavelength of 400 nm or more, a wavelength of 750 to 800 nm that can absorb light in the ultraviolet region through a multiphoton absorption process and can be cut to a width of 20 μm or less by multiphoton absorption ablation. Examples thereof include a laser having a pulse width of 1e- ⁹ seconds (0.000000001 seconds) or less with a nearby titanium sapphire laser or the like.

  The organic workpiece is not particularly limited as long as it can be processed by ultraviolet absorption ablation of the laser beam output by the laser, and examples thereof include various sheet materials, cloth, leather, and paper. It is done.

  Examples of the various sheet materials include polyimide resins, polyester resins, epoxy resins, urethane resins, polystyrene resins, polyethylene resins, polyamide resins, polycarbonate resins, silicon resins, and fluorine resins. Examples thereof include a polymer film and a nonwoven fabric made of the same, a sheet provided with a physical or optical function by stretching or impregnating those resins.

  The inorganic workpiece is not particularly limited as long as it can be processed by ultraviolet absorption ablation of the laser beam output from the laser, and examples thereof include a circuit board, a semiconductor wafer, a glass substrate, a ceramic substrate, and a metal. Examples include materials, metal substrates, semiconductor laser light emitting or light receiving element substrates, MEMS substrates, and semiconductor packages.

  Examples of the circuit board include a single-sided, double-sided or multilayer flexible printed board, a rigid board made of glass epoxy, ceramic, or metal core board, an optical circuit formed on glass or polymer, or an opto-electric hybrid circuit board. It is done.

  Examples of the metal material include metalloids and alloys, such as gold, SUS, copper, iron, aluminum, stainless steel, silicon, titanium, nickel, and tungsten, and workpieces using these.

  In the method for producing a laser processed product of the present invention, a protective sheet having at least an adhesive layer on a substrate is used. When laser processing an organic workpiece, it is necessary to select and use a protective sheet having a refractive index ratio of 1 or more. On the other hand, when laser processing an inorganic workpiece, it is necessary to select and use a protective sheet having a substrate having a refractive index of 1.53 or more at a wavelength of 546 nm.

  Examples of the material for forming the base material include polyethylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyimide, (meth) acrylic polymer, polyurethane, silicone rubber, and polyolefin polymer such as polyethylene, polypropylene, and polyethylene oxide. However, it is not limited to these. Among these, it is preferable to use materials having a high refractive index at a wavelength of 546 nm, such as aromatic polymers such as polyimide, polyethylene naphthalate, polystyrene, and polycarbonate, and silicon rubber.

  A filler may be added to the substrate. The filler is a material added to increase the refractive index of the substrate, and examples thereof include metal fine particles such as Au, Cu, Pt, and Ag, metal colloids, and inorganic fine particles such as carbon.

  The amount of the filler added can be appropriately adjusted in consideration of the refractive index of the base polymer to be used and the refractive index of the workpiece, but is usually about 2 parts by weight with respect to 100 parts by weight of the base polymer. The amount is preferably about 5 parts by weight.

  The substrate may be a single layer or a multilayer. Moreover, various shapes, such as a film | membrane form and a mesh form, can be taken.

  The thickness of the base material is appropriately adjusted within a range that does not impair the operability and workability in each process such as bonding onto the work piece, cutting and punching of the work piece, and peeling and recovery of the cut piece. However, it is usually 500 μm or less, preferably about 3 to 300 μm, and more preferably 5 to 250 μm. The surface of the substrate is chemically treated by conventional surface treatments such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, and ionizing radiation treatment to improve adhesion to the adhesive layer, retention, etc. Alternatively, physical treatment may be performed.

  As a material for forming the pressure-sensitive adhesive layer, known pressure-sensitive adhesives including (meth) acrylic polymers and rubber-based polymers can be used.

  Examples of the monomer component forming the (meth) acrylic polymer include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an isobutyl group, an amyl group, an isoamyl group, and a hexyl group. Group, heptyl group, cyclohexyl group, 2-ethylhexyl group, octyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, lauryl group, tridecyl group, tetradecyl group, stearyl group, octadecyl group, and Examples thereof include alkyl (meth) acrylates having a linear or branched alkyl group having 30 or less carbon atoms, preferably 4 to 18 carbon atoms, such as a dodecyl group. These alkyl (meth) acrylates may be used alone or in combination of two or more.

  For the purpose of modifying the adhesiveness, cohesive strength, heat resistance, etc. of the (meth) acrylic polymer, monomer components other than those described above may be copolymerized. Examples of such monomer components include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid-containing monomers, anhydrous Acid anhydride monomers such as maleic acid and itaconic anhydride, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6- (meth) acrylic acid Hydroxyl groups such as hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate Contains Nomers, styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalene sulfonic acid Sulfonic acid group-containing monomers, phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate, (meth) acrylamide, (meth) acrylic acid N-hydroxymethylamide, (meth) acrylic acid alkylaminoalkyl esters (for example, dimethylamino) Ethyl methacrylate, t-butylaminoethyl methacrylate, etc.), N-vinylpyrrolidone, acryloylmorpholine, vinyl acetate, styrene, and acrylonitrile. These monomer components may be used alone or in combination of two or more.

  Moreover, a polyfunctional monomer etc. can also be used as a copolymerization monomer component as needed for the purpose of a crosslinking treatment of a (meth) acrylic polymer.

  Examples of polyfunctional monomers include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and pentaerythritol di (Meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, and urethane (meth) acrylate Etc., and the like. These polyfunctional monomers may be used individually by 1 type, and may use 2 or more types together.

  The amount of the polyfunctional monomer used is preferably 30% by weight or less, more preferably 20% by weight or less of the total monomer components from the viewpoint of adhesive properties and the like.

  For the preparation of the (meth) acrylic polymer, an appropriate method such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, or a suspension polymerization method is applied to a mixture containing one or more monomer components. It can be carried out.

  Examples of the polymerization initiator include peroxides such as hydrogen peroxide, benzoyl peroxide, and t-butyl peroxide. Although it is desirable to use it alone, it can also be used as a redox polymerization initiator in combination with a reducing agent. Examples of the reducing agent include ionized salts such as sulfites, hydrogen sulfites, iron, copper, and cobalt salts, amines such as triethanolamine, and reducing sugars such as aldose and ketose. Azo compounds are also preferred polymerization initiators, and are 2,2′-azobis-2-methylpropioamidine, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis- Use N, N'-dimethyleneisobutylaminate, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methyl-N- (2-hydroxyethyl) propionamide, etc. Can do. It is also possible to use two or more of the above polymerization initiators in combination.

  The reaction temperature is usually about 50 to 85 ° C., and the reaction time is about 1 to 8 hours. Among the production methods, a solution polymerization method is preferable, and a polar solvent such as ethyl acetate or toluene is generally used as a solvent for the (meth) acrylic polymer. The solution concentration is usually about 20 to 80% by weight.

  In order to increase the number average molecular weight of the (meth) acrylic polymer that is the base polymer, a crosslinking agent can be appropriately added to the pressure-sensitive adhesive. Examples of the crosslinking agent include polyisocyanate compounds, epoxy compounds, aziridine compounds, melamine resins, urea resins, anhydrous compounds, polyamines, and carboxyl group-containing polymers. In the case of using a crosslinking agent, the amount used is considered to be about 0.01 to 5 parts by weight with respect to 100 parts by weight of the base polymer, considering that the peeling adhesive strength does not decrease too much. Is preferred. In addition to the above-described components, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer may include conventional additives such as various conventionally known tackifiers, anti-aging agents, fillers, anti-aging agents, and coloring agents. It can be included.

  In order to improve the peelability from the workpiece, the pressure-sensitive adhesive is preferably a radiation-curable pressure-sensitive adhesive that is cured by radiation such as ultraviolet rays or electron beams. In addition, when using a radiation curing type adhesive as an adhesive, since the radiation is irradiated to an adhesive layer after a laser processing, the said base material has sufficient radiolucency.

  Examples of the radiation curable pressure-sensitive adhesive include a radiation curable pressure-sensitive adhesive obtained by blending the aforementioned (meth) acrylic polymer with a radiation curable monomer component or oligomer component.

  Examples of the radiation-curable monomer component and oligomer component to be blended include urethane (meth) acrylate oligomer, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, tetraethylene glycol di (meth) acrylate, Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, and 1 Ester compounds composed of (meth) acrylic acid and polyhydric alcohol, such as 1,6-hexanediol di (meth) acrylate, 2-propenyl-3-butenyl isocyanurate DOO, and tris (2-methacryloxyethyl) include isocyanurate compounds such as isocyanurates. These may be used alone or in combination of two or more.

  The blending amount of the radiation curable monomer component or oligomer component is not particularly limited, but in consideration of the tackiness, it is based on 100 parts by weight of the base polymer such as a (meth) acrylic polymer constituting the pressure sensitive adhesive. The amount is preferably about 5 to 500 parts by weight, and more preferably about 70 to 150 parts by weight.

  Moreover, as a radiation curable adhesive, what has a carbon-carbon double bond in a polymer side chain or a principal chain, or the principal chain terminal can also be used as a base polymer. As such a base polymer, a polymer having a (meth) acrylic polymer as a basic skeleton is preferable. In this case, it is not necessary to add a radiation curable monomer component or oligomer component, and its use is optional.

  The radiation curable pressure-sensitive adhesive contains a photopolymerization initiator when cured by ultraviolet rays or the like. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α-methylacetophenone, methoxyacetophenone, and 2,2-dimethoxy-2-phenyl. Acetophenone compounds such as acetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, benzoin ethyl ether, benzoin isopropyl Benzoin ether compounds such as ether and anisoin methyl ether, α-ketol compounds such as 2-methyl-2-hydroxypropylphenone, ketal compounds such as benzyldimethyl ketal, 2-naphthalenesulfonyl chloride Aromatic sulfonyl chloride compounds such as Lido, photoactive oxime compounds such as 1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime, benzophenone, benzoylbenzoic acid, 3,3′-dimethyl Benzophenone compounds such as -4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2 Thioxanthone compounds such as 1,4-diethylthioxanthone and 2,4-diisopropylthioxanthone, camphorquinone, halogenated ketone, acyl phosphinoxide and acyl phosphonate.

  The blending amount of the photopolymerization initiator is preferably about 0.1 to 10 parts by weight with respect to 100 parts by weight of the base polymer such as a (meth) acrylic polymer constituting the pressure-sensitive adhesive, and more preferably is about 0.1. About 5 to 5 parts by weight.

  The said protective sheet can be manufactured by apply | coating an adhesive solution to the surface of a base material, and making it dry (it heat-crosslinks as needed), and forms an adhesive layer. Moreover, after forming an adhesive layer in a release liner separately, the method of bonding it to a base material etc. are employable. The pressure-sensitive adhesive layer may be a single layer or two or more layers. If necessary, a separator may be provided on the surface of the pressure-sensitive adhesive layer.

  The pressure-sensitive adhesive layer preferably has a low content of low molecular weight substances from the viewpoint of preventing contamination of the workpiece or silicon-based material. From this point, the number average molecular weight of the (meth) acrylic polymer is preferably 500,000 or more, more preferably 800,000 to 3,000,000.

  The thickness of the pressure-sensitive adhesive layer can be appropriately selected as long as it does not peel from the workpiece or silicon-based material, but is preferably about 5 to 300 μm, more preferably about 10 to 100 μm, and particularly preferably about 10 to 50 μm. It is.

  Further, the adhesive strength of the pressure-sensitive adhesive layer is preferably 20 N / 20 mm or less, more preferably based on the adhesive strength (90-degree peel value, peeling speed 300 mm / min) at normal temperature (before laser irradiation) to SUS304. 0.001 to 10 N / 20 mm, particularly preferably 0.01 to 8 N / 20 mm.

  The said separator is provided as needed in order to protect a label process or an adhesive layer. Examples of the constituent material of the separator include paper, polyethylene, polypropylene, and synthetic resin films such as polyethylene terephthalate. In order to improve the peelability from the pressure-sensitive adhesive layer, the surface of the separator may be subjected to a peeling treatment such as a silicon treatment, a long-chain alkyl treatment, or a fluorine treatment as necessary. Further, if necessary, an ultraviolet transmission preventing treatment or the like may be performed so that the protective sheet does not react with environmental ultraviolet rays. The thickness of a separator is 10-200 micrometers normally, Preferably it is about 25-100 micrometers.

  Hereinafter, using a protective sheet having a refractive index ratio of 1 or more (or a protective sheet having a substrate having a refractive index of 1.53 or more at a wavelength of 546 nm), a method for producing a laser processed product by ultraviolet absorption ablation of laser light Will be explained. For example, in the case of cutting processing, as shown in FIGS. 1 and 3, the protective sheet 2, the workpiece 1, and the adhesive sheet 3 are bonded together by a known means such as a roll laminator or a press. The object-adhesive sheet laminate 4 is arranged on the suction plate 6 of the suction stage 5, and the laser beam 7 output from a predetermined laser oscillator is condensed on the laminate 4 by the lens on the protective sheet 2. While irradiating, cutting processing is performed by moving the laser irradiation position along a predetermined processing line. The pressure-sensitive adhesive sheet 3 provided on the laser beam emitting surface side of the workpiece plays a role of supporting and fixing the workpiece before laser processing, and plays a role of preventing the cut material from falling after the laser processing. A sheet with low laser processability is used. As the pressure-sensitive adhesive sheet 3, a general sheet in which a pressure-sensitive adhesive layer is laminated on a substrate can be used without particular limitation.

  As the laser beam moving means, a known laser processing method such as a galvano scan, an XY stage scan, or a mask imaging process is used.

  The laser processing conditions are not particularly limited as long as the protective sheet 2 and the workpiece 1 are completely cut, but the workpiece 1 is cut in order to avoid cutting up to the adhesive sheet 3. It is preferable to be within twice the energy condition.

In addition, the cutting margin (cutting groove) can be narrowed by narrowing the beam diameter of the laser beam condensing part.
It is preferable that the beam diameter (μm)> 2 × (laser beam moving speed (μm / sec) / laser beam repetition frequency (Hz)) is satisfied.

  Further, in the case of drilling, as shown in FIG. 2, a protective sheet obtained by bonding the protective sheet 2, the workpiece 1 and the adhesive sheet 3 by a known means such as a roll laminator or a press-workpiece- The pressure-sensitive adhesive sheet laminate 4 is disposed on the suction plate 6 of the suction stage 5, and laser light 7 output from a predetermined laser oscillator is condensed and irradiated on the protective sheet 2 by a lens on the laminate 4. To form holes.

  The hole is formed by a known laser processing method such as galvano scan, XY stage scan, or punching by mask imaging. The optimum laser processing condition may be determined based on the ablation threshold of the material to be processed. In order to avoid punching up to the pressure-sensitive adhesive sheet 3, it is preferable that the workpiece 1 is within twice the energy condition for punching.

  Further, by blowing a gas such as helium, nitrogen, oxygen, or the like onto the laser processing portion, it is possible to improve the efficiency of removing the decomposition products.

  Further, the semiconductor wafer (silicon wafer) is cut by bonding one side of the semiconductor wafer 8 to the adhesive sheet 3 provided on the suction stage 5 as shown in FIG. 4, and further installing the protective sheet 2 on the other side. Laser light 7 output from a predetermined laser oscillator is condensed and irradiated onto the protective sheet 2 by a lens, and cutting processing is performed by moving the laser irradiation position along a predetermined processing line. As a laser beam moving means, a known laser processing method such as galvano scan, XY stage scan, mask, or imaging processing is used. The cutting conditions of the semiconductor wafer are not particularly limited as long as the protective sheet 2 and the semiconductor wafer 8 are cut and the adhesive sheet 3 is not cut.

  In such a semiconductor wafer cutting process, after cutting into individual semiconductor chips, a method of picking up using a push-up pin called a needle by a conventionally known device such as a die bonder, or JP-A-2001-118862. Individual semiconductor chips can be picked up and collected by a known method such as the method shown.

  In the laser processed product manufacturing method of the present invention, the protective sheet 2 is peeled from the laser processed product 10 after the laser processing is completed. The method of peeling is not limited, but it is important to prevent the laser-processed product 10 from undergoing stress that causes permanent deformation during peeling. For example, when a radiation curable pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is cured by irradiation with radiation according to the type of the pressure-sensitive adhesive, thereby reducing the adhesiveness. By the irradiation of radiation, the adhesiveness of the pressure-sensitive adhesive layer is reduced by curing, and peeling can be facilitated. The means for radiation irradiation is not particularly limited. For example, the irradiation is performed by ultraviolet irradiation.

  In the method for producing a laser processed product of the present invention, a protective sheet having a refractive index ratio of 1 or more (or a protective sheet having a substrate having a refractive index of 1.53 or more at a wavelength of 546 nm) is used. The protective sheet is more easily etched than the workpiece, and the underlying workpiece is etched after the laser light irradiation portion of the protective sheet is sufficiently etched. Therefore, the decomposition product of the workpiece is efficiently scattered from the etched portion of the protective sheet to the outside, so that contamination of the interface portion between the protective sheet and the workpiece can be suppressed. Therefore, according to the above manufacturing method, the decomposed material does not adhere to the interface portion between the protective sheet and the workpiece (laser processed product), so the protective sheet can be easily removed from the laser processed product after laser processing the workpiece. Can be peeled off, and the laser processing accuracy of the workpiece can be improved.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Measurement of number average molecular weight)
The number average molecular weight of the synthesized (meth) acrylic polymer was measured by the following method. The synthesized (meth) acrylic polymer was dissolved in THF at 0.1 wt%, and the number average molecular weight was measured by polystyrene conversion using GPC (gel permeation chromatography). Detailed measurement conditions are as follows.
GPC device: Tosoh HLC-8120GPC
Column: manufactured by Tosoh Corporation, (GMHHR-H) + (GMHHR-H) + (G2000HHR)
Flow rate: 0.8ml / min
Concentration: 0.1 wt%
Injection volume: 100 μl
Column temperature: 40 ° C
Eluent: THF

(Measurement of refractive index)
The refractive index of the used base material and the organic workpiece was measured using an Abbe refractometer (manufactured by ATAGO, DR-M4). The measurement wavelength is 546 nm.

Example 1
A polypropylene sheet (thickness 60 μm, refractive index 1.51) was used as a workpiece. On a base material made of polystyrene (thickness 20 μm, refractive index 1.59), an acrylic pressure-sensitive adhesive solution (1) curable by ultraviolet rays is applied and dried to form a pressure-sensitive adhesive layer (thickness 10 μm). A protective sheet was prepared. The refractive index ratio was 1.05.

  The acrylic pressure-sensitive adhesive solution (1) was prepared by the following method. 100 parts by weight of an acrylic polymer having a number average molecular weight of 800,000 obtained by copolymerizing butyl acrylate / ethyl acrylate / 2-hydroxyethyl acrylate / acrylic acid at a weight ratio of 60/40/4/1, and dipentadiene as a photopolymerizable compound 90 parts by weight of erythritol monohydroxypentaacrylate, 5 parts by weight of benzyldimethyl ketal (Irgacure 651) as a photopolymerization initiator, and 2 parts by weight of a polyisocyanate compound (manufactured by Nippon Polyurethane Co., Ltd., Coronate L) are added to 650 parts by weight of toluene, and uniform. Acrylic pressure-sensitive adhesive solution (1) was prepared by dissolving in

  The prepared protective sheet was bonded to one side of the polypropylene sheet with a roll laminator to prepare a polypropylene sheet with a protective sheet.

  And the polypropylene sheet with a protection sheet was arrange | positioned on the XY stage on which the adsorption board made from glass epoxy resin was put. A third harmonic (355 nm) of a YAG laser having a wavelength of 355 nm, an average output of 5 W, and a repetition frequency of 30 kHz is condensed to a 25 μm diameter on the surface of a polypropylene sheet with a protective sheet by an fθ lens, and the laser light is 20 mm / second by a galvano scanner. Scanned at speed and cut. At this time, it was confirmed that the protective sheet and the polypropylene sheet were cut. And the ultraviolet-ray was irradiated to the protective sheet, and the adhesive layer was hardened. Then, when the protective sheet was peeled off and the laser processing peripheral part of the protective sheet bonding surface (laser light incident surface side) of the polypropylene sheet was observed, no decomposition product (adhered matter) was observed.

Comparative Example 1
In Example 1, the polypropylene sheet was subjected to laser processing in the same manner as in Example 1 except that the protective sheet was not provided on one side of the polypropylene sheet. Then, when the processing periphery part of the laser beam incident surface side of a polypropylene sheet was observed, the scattered decomposition residue residue adhered in large quantities.

Comparative Example 2
In Example 1, the polypropylene sheet was laser processed in the same manner as in Example 1 except that a polymethylpentene sheet (thickness: 100 μm, refractive index: 1.46) was used as the base material of the protective sheet. The refractive index ratio was 0.97. As a result, the protective sheet was not cut, and the lower layer polypropylene sheet was laser-processed, and bubbles containing decomposition product residues were generated between the protective sheet and the polypropylene sheet. And the ultraviolet-ray was irradiated to the protective sheet, and the adhesive layer was hardened. Thereafter, when the protective sheet was peeled off and the periphery of the opening on the laser light incident surface side of the polypropylene sheet was observed, a large amount of polypropylene degradation product residue was adhered.

Example 2
A polycarbonate sheet (thickness: 100 μm, refractive index: 1.59) was used as a workpiece. A polycarbonate sheet with a protective sheet was produced in the same manner as in Example 1 except that a polyethylene terephthalate sheet (thickness 20 μm, refractive index 1.66) was used as the base material of the protective sheet. The refractive index ratio was 1.04.

  Moreover, the said acrylic adhesive solution (1) was apply | coated and dried on the base material (100 micrometers in thickness) which consists of polyethylene, and the adhesive layer (10 micrometers in thickness) was formed, and the adhesive sheet was manufactured. The pressure-sensitive adhesive sheet was attached to the back side of the polycarbonate sheet with a protective sheet to produce a polycarbonate sheet with a protective / pressure-sensitive adhesive sheet. Then, when it cut by the method similar to Example 1, the protective sheet and the polycarbonate sheet were cut | disconnected, but the adhesive sheet was not cut | disconnected. And the ultraviolet-ray was irradiated to the protective sheet, and the adhesive layer was hardened. Then, when the protective sheet was peeled and the laser processing peripheral part of the protective sheet bonding surface (laser light incident surface side) of the polycarbonate sheet was observed, no decomposition product (adhered matter) was observed.

Example 3
A silicon wafer with a protective / adhesive sheet was produced in the same manner as in Example 2 except that a silicon wafer (thickness: 100 μm) was used instead of the polycarbonate sheet. Then, when it cut by the method similar to Example 1, the protective sheet and the silicon wafer were cut | disconnected, but the adhesive sheet was not cut | disconnected. And the ultraviolet-ray was irradiated to the protective sheet, and the adhesive layer was hardened. Then, when the protective sheet was peeled and the laser processing peripheral part of the protective sheet bonding surface (laser beam incident surface side) of the silicon wafer was observed, no decomposition product (adhered matter) was observed.

Comparative Example 3
A silicon wafer with a protective / adhesive sheet was produced in the same manner as in Example 3 except that a polypropylene sheet (thickness 60 μm, refractive index 1.51) was used as the base material of the protective sheet. After that, when the cutting process was performed in the same manner as in Example 1, the protective sheet was not cut, the lower silicon wafer was laser processed, and a decomposition product residue was included between the protective sheet and the silicon wafer. Bubbles were generated. And the ultraviolet-ray was irradiated to the protective sheet, and the adhesive layer was hardened. Then, when the protective sheet was peeled off and the periphery of the opening on the laser light incident surface side of the silicon wafer was observed, a large amount of decomposition product residue was adhered.

As is clear from the above Examples and Comparative Examples, a decomposition product is obtained by using a protective sheet having a refractive index ratio of 1 or more, or a protective sheet having a base material having a refractive index of 1.53 or more at a wavelength of 546 nm. It is possible to effectively suppress contamination of the workpiece surface due to the above. And since the decomposition | disassembly product removal process after that can be simplified significantly, not only can it contribute to environmental load reduction, but the improvement of productivity can also be aimed at.

It is a schematic process drawing which shows the example of the manufacturing method of the laser processed product in this invention. It is a schematic process drawing which shows the other example of the manufacturing method of the laser processed product in this invention. It is the schematic which shows the cross section of the laminated body processed by the ultraviolet absorption ablation of a laser beam. It is the schematic which shows the example of the dicing method of a semiconductor wafer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Workpiece 2 Protection sheet for laser processing 3 Adhesive sheet 4 Laminate 5 Adsorption stage 6 Adsorption plate 7 Laser light 8 Semiconductor wafer 9 Dicing frame 10 Laser processed product

Claims (6)

A refractive index at a wavelength of 546 nm of the base material with respect to a refractive index at a wavelength of 546 nm of the organic workpiece to be used (refractive index ratio = base of the protective sheet for laser processing) A protective sheet for laser processing having a refractive index at a wavelength of 546 nm of the material / a refractive index of the organic workpiece to be used at a wavelength of 546 nm) of 1 or more, and the said workpiece on the laser light incident surface side of the organic workpiece. A process of applying an adhesive layer of a protective sheet for laser processing, a process of processing a protective sheet for laser processing and an organic workpiece by irradiating laser light, an organic workpiece after processing the protective sheet for laser processing A method for producing a laser-processed product including a step of peeling from a laser beam. A laser light incident surface of an inorganic workpiece using a protective sheet for laser processing that has at least a pressure-sensitive adhesive layer on the substrate and has a refractive index of 1.53 or more at a wavelength of 546 nm of the substrate. A step of applying an adhesive layer of the protective sheet for laser processing on the side, a step of processing a protective sheet for laser processing and an inorganic workpiece by irradiating laser light, an inorganic system after processing the protective sheet for laser processing A method of manufacturing a laser processed product including a step of peeling from a workpiece. 3. The laser-processed product according to claim 2, wherein the inorganic workpiece is a circuit board, a semiconductor wafer, a glass substrate, a ceramic substrate, a metal substrate, a semiconductor laser light emitting or receiving element substrate, a MEMS substrate, or a semiconductor package. Method. The said base material is a manufacturing method of the laser processed goods in any one of Claims 1-3 containing an aromatic polymer or silicon rubber. The method for producing a laser processed product according to claim 1, wherein the processing is cutting or drilling. The protective sheet for laser processing used for the manufacturing method of the laser processed product in any one of Claims 1-5.

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