JP2005279676A - Method of producing laser-processed product and adhesive sheet for laser processing used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of effectively suppressing contamination on the surface of an object to be processed caused by a decomposition product, enabling a laser-processed product to be easily produced with enhanced production efficiency in processing the object to be processed by ablation using a laser light. <P>SOLUTION: The method of producing the laser-processed product uses a sheet, as an adhesive sheet 2 for laser processing, on the base material of which at least an adhesive agent layer is disposed and for which the adhesive having the ratio of the coefficient of light absorption expressed of the adhesive sheet for laser processing at 355 nm wavelength to the coefficient of light absorption of the object to be processed at 355 nm wavelength of <1 is used. The method includes a step of bonding the adhesive sheet 2 to the laser-light exit surface side of the object 1 to be processed with the adhesive agent layer in between, a step of processing the object 1 by irradiating it with a laser beam 6 having irradiation intensity that is greater than a threshold value at which the object 1 causes ablation and is not more than twice the irradiation intensity at which a through-hole is formed in the object 1, and a step of separating the adhesive sheet 2 for laser processing from the object 1 processed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes workpieces such as various sheet materials, circuit substrates, semiconductor wafers, glass substrates, ceramic substrates, metal substrates, light emitting or receiving element substrates such as semiconductor lasers, MEMS substrates, semiconductor packages, cloth, leather, and paper. The present invention relates to a method for producing a laser-processed product in which, for example, cutting or drilling is performed using a laser, and a pressure-sensitive adhesive sheet for laser processing used therefor.

  With the recent miniaturization of electrical and electronic equipment, the miniaturization of parts and high definition have progressed, and the outline processing of various materials has been required to have high precision and high accuracy with processing accuracy of ± 50 μm or less. ing. However, the conventional punching process such as press working has an accuracy of about ± 100 μm at the most, and is currently unable to meet such a requirement. 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.

  However, when laser light is used, there is a problem that decomposition products such as carbon generated from the workpiece, the adhesive tape, or the suction plate adhere to the surface of the workpiece during laser processing. For this reason, post-processing called desmear for removing decomposition products is required. However, when wet desmear or the like is performed using, for example, a potassium permanganate aqueous solution or the like, there is a problem that environmental pollution increases due to the waste liquid treatment or the like.

  Moreover, the adhesion strength of the decomposition product becomes stronger in proportion to the power of the laser beam. For this reason, when laser processing is performed with the laser beam power increased, it is difficult to remove decomposition products in the post-treatment.

  In addition, if a predetermined region of the workpiece is cut at a time, the workpiece (cut piece) is dropped immediately after the processing, which is difficult to handle. For this reason, the technique of leaving a part of an unprocessed part at the time of a process is taken.

  As a specific example of the laser processing, for example, a semiconductor wafer dicing method described in Patent Document 1 below is disclosed. In this method, a workpiece is supported and fixed on a dicing sheet, and the workpiece is diced with a laser beam. According to the description of Patent Document 1, the dicing sheet includes a base material including a support sheet and an adhesive layer disposed on one surface of the base material. Further, the pressure-sensitive adhesive layer can be cut by a laser beam, and the support sheet has a configuration that cannot be cut by a laser beam.

  When the dicing sheet described in Patent Document 1 below is used, the pressure-sensitive adhesive layer is cut by thermal processing with the laser beam of the fundamental wave (wavelength 1064 nm) or ruby laser (wavelength 694 nm) of the YAG laser used. For this reason, the decomposition product of the pressure-sensitive adhesive layer may enter the interface between the dicing sheet and the workpiece and adhere firmly at the interface portion. As a result, it becomes difficult to peel the dicing sheet from the workpiece after laser processing. In addition, it is difficult to completely remove the deposits even after the post-treatment. Further, since the processing goes through the thermal processing process, the thermal damage of the edge portion is large. For this reason, the processing accuracy is lowered, and the reliability is also lowered accordingly.

  In addition, a laser processing method using both a fundamental wave of a YAG laser and a water microjet has been proposed (see Patent Document 2 below). In this patent document 2, as a laser dicing adhesive tape, a non-radiation curable adhesive layer and a radiation curable adhesive layer are provided on one side of a substrate, and the substrate is a jet of water jet. It is disclosed that it is transmissive and a non-radiation curable pressure-sensitive adhesive layer is provided between the substrate and the radiation curable pressure-sensitive adhesive layer.

When this adhesive tape is used in a method of dicing a semiconductor wafer by combining a water microjet and a laser, the thermal damage of the adhesive tape is reduced by the cooling effect of the water jet. For this reason, it is thought that it can suppress that an adhesive layer and a base material melt | dissolve and decompose by the heat | fever by laser irradiation. However, when the adhesive tape is used in a method of dicing a semiconductor wafer using only a laser, the adhesive layer or the substrate is melted by the heat of laser irradiation, or the adhesive is bonded to the interface between the adhesive sheet and the semiconductor wafer. The decomposition product of the layer or the base material may invade and adhere firmly at the interface portion, which may cause the same problem as described above. Further, when a water microjet is used, there is a limit to reducing the cutting width during dicing. This is because the cutting width is defined by the diameter of the water jet. Therefore, the manufacturing efficiency of the semiconductor chip is inferior.
JP 2002-343747 A JP 2003-34780 A

  The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to effectively suppress contamination of the surface of the workpiece by the decomposition product when processing the workpiece by laser beam ablation. Thus, an object of the present invention is to provide a method for producing a laser processed product with high production efficiency and easily. Moreover, it aims at providing the adhesive sheet for laser processing used for the manufacturing method of the said laser processed product.

  In order to solve the above-described conventional problems, the inventors of the present application have made extensive studies on a method for producing a laser-processed product and a pressure-sensitive adhesive sheet for laser processing. As a result, focusing on the physical property of the absorption coefficient of the laser processing adhesive sheet, it was found that the above-described object can be achieved by the following constitution, and the present invention has been completed.

  That is, the method of manufacturing a laser processed product according to the present invention uses a laser processing adhesive sheet to convert laser light having a wavelength in the ultraviolet region or laser light that can absorb light in the ultraviolet region through a multiphoton absorption process. A method of manufacturing a laser processed product by irradiating a workpiece and processing the workpiece by ablation, wherein the pressure-sensitive adhesive sheet for laser processing is provided with at least an adhesive layer on a substrate. A step of adhering a pressure-sensitive adhesive sheet for laser processing via the pressure-sensitive adhesive layer to the laser light emitting surface side of the workpiece using a ratio of the extinction coefficient represented by the following formula: The workpiece is processed by irradiating the workpiece with a laser beam that is equal to or higher than a threshold irradiation intensity that causes ablation and is within twice the irradiation intensity at which a through hole is formed on the workpiece. And extent, characterized in that it comprises a step of peeling the pressure-sensitive adhesive sheet for laser processing from the workpiece after processing.

前記被加工物としては、シート材料、回路基板、半導体ウエハ、ガラス基板、セラミック基板、金属基板、半導体レーザーの発光若しくは受光素子基板、ＭＥＭＳ基板、または半導体パッケージを使用することができる。

As the workpiece, a sheet material, 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 can be used.

In addition, the method for producing a laser processed product according to the present invention uses a laser processing pressure-sensitive adhesive sheet, and uses a laser beam having a wavelength in the ultraviolet region or a laser beam capable of absorbing light in the ultraviolet region via a multiphoton absorption process. A method of manufacturing a laser processed product by irradiating a workpiece made of a metal-based material and processing the workpiece by ablation, wherein at least an adhesive layer is provided on a substrate as the pressure-sensitive adhesive sheet for laser processing And having a light absorption coefficient of less than 20 cm ⁻¹ for laser light having a wavelength of 355 nm, a laser processing pressure-sensitive adhesive sheet is disposed on the laser light emitting surface side of the workpiece via the pressure-sensitive adhesive layer. A step of bonding and an irradiation intensity equal to or higher than a threshold at which the workpiece causes ablation, and the irradiation intensity is less than twice the irradiation intensity at which a through hole is formed in the workpiece. The method includes a step of irradiating a laser beam to process the workpiece, and a step of peeling the laser processing pressure-sensitive adhesive sheet from the processed workpiece.

  As the workpiece, a semiconductor wafer or a metal substrate can be used.

  Examples of the step of processing the workpiece include a step of cutting or punching the workpiece.

  The pressure-sensitive adhesive sheet for laser processing according to the present invention is used in the method for manufacturing a laser processed product.

  The method for producing a laser processed product according to the present invention uses a laser processing pressure-sensitive adhesive sheet (hereinafter referred to as “pressure-sensitive adhesive sheet”) in which at least a pressure-sensitive adhesive layer is provided on a substrate. This pressure-sensitive adhesive sheet satisfies that the ratio of the extinction coefficient represented by the following formula is less than 1.

吸光係数の比が１未満の粘着シートを使用すると、被加工物よりもレーザー光の侵入長（＝１／（吸光係数））を深くすることができる。粘着シートの吸光係数が被加工物の吸光係数よりも小さいからである。よって、レーザー光が照射されても、粘着シートの体積当たりに蓄積する熱量を被加工物よりも少なくできる。その結果、粘着シートは被加工物よりも難加工とすることができる。

When an adhesive sheet having an extinction coefficient ratio of less than 1 is used, the penetration depth of laser light (= 1 / (absorption coefficient)) can be made deeper than the workpiece. This is because the extinction coefficient of the adhesive sheet is smaller than the extinction coefficient of the workpiece. Therefore, even when the laser beam is irradiated, the amount of heat accumulated per volume of the pressure-sensitive adhesive sheet can be less than that of the workpiece. As a result, the pressure-sensitive adhesive sheet can be made more difficult to process than the workpiece.

  Therefore, when the workpiece is irradiated with a laser beam that is equal to or higher than the irradiation intensity of the threshold that causes the workpiece to ablate and is within twice the irradiation intensity at which a through hole is formed in the workpiece, The workpiece is laser processed, but the adhesive sheet is difficult to process. When the pressure-sensitive adhesive sheet is more difficult to process than the workpiece, the generation of decomposition residue due to the ablation of the pressure-sensitive adhesive sheet can be reduced. Thereby, the decomposition residue residue does not adhere between a workpiece and an adhesive sheet, and it can suppress that what is called a processing back surface is contaminated. As a result, it is possible to provide a method for manufacturing a laser-processed product easily and efficiently.

  Furthermore, post-process such as wet desmear, for example, can be omitted to remove the decomposition residue. In addition, there is no need for waste liquid treatment required in the post-process, which can contribute to reducing the environmental burden. In addition, since the adhesion of decomposition products can be reduced, it is possible to increase the power of the laser beam and improve the throughput.

  In addition, since laser light having a wavelength in the ultraviolet region or laser light that can absorb light in the ultraviolet region via a multiphoton absorption process is used, for example, when the workpiece is made of a polymer material, a thermal processing process is performed. Processing is possible by photochemical ablation without going through. Thereby, there is no thermal damage to the edge portion, the cut portion and the opening can be processed more sharply, and processing accuracy and reliability can be improved. Furthermore, local focusing is possible compared with laser light in the infrared region, and there is no need to make a large margin. Therefore, dicing or the like with a thinner margin than before is possible.

When the method for producing a laser processed product according to the present invention is applied to a workpiece made of a metal material, an adhesive sheet having an extinction coefficient of less than 20 cm ⁻¹ for laser light having a wavelength of 355 nm is used. The extinction coefficient of a workpiece made of a metal material is about 5 × 10 ⁷ cm ^{−1 with} respect to laser light having a wavelength of 355 nm. That is, since the extinction coefficient of the adhesive sheet is smaller than the extinction coefficient of the workpiece, the adhesive sheet can be made more difficult to process than the workpiece, as described above. Therefore, with this configuration, it is possible to suppress the so-called processed back surface, in which the decomposition product residue generated from the pressure-sensitive adhesive sheet exists between the workpiece and the pressure-sensitive adhesive sheet, from being contaminated.

  Furthermore, the post-process for removing the decomposition product residue can be omitted, and the waste liquid treatment required in the post-process is not required. As a result, it can contribute to the reduction of environmental load. In addition, since the adhesion of decomposition products can be reduced, it is possible to increase the power of the laser beam and improve the throughput.

  In addition, since laser light with a wavelength in the ultraviolet region or laser light that can absorb light in the ultraviolet region through a multiphoton absorption process is used, local focusing is possible compared to laser light in the infrared region. It is not necessary to take a large margin. Therefore, dicing or the like with a thinner margin than before is possible.

  In addition, the manufacturing method of the laser processed product which concerns on this invention uses what is equipped with the adhesive layer which adhere | attaches and fixes a to-be-processed object as an adhesive sheet as above-mentioned. Therefore, for example, even when a predetermined region of the workpiece is cut at a time, the workpiece (cut piece) is bonded and fixed to the pressure-sensitive adhesive layer. For this reason, it is possible to prevent the workpiece from falling off and to improve handling properties. Furthermore, it is not necessary to adopt a drop-off prevention method of leaving a partially unprocessed part.

(Embodiment 1)
A method for manufacturing a laser processed product according to Embodiment 1 of the present invention will be described with reference to FIGS. However, parts that are not necessary for the description are omitted, and there are parts that are illustrated in an enlarged or reduced manner for ease of explanation.

  The method for producing a laser processed product according to the present embodiment uses a laser processing pressure-sensitive adhesive sheet (hereinafter referred to as “pressure-sensitive adhesive sheet”) having at least a pressure-sensitive adhesive layer on a base material, A step of attaching an adhesive sheet to the laser light emitting surface side through the adhesive layer, and the workpiece has an irradiation intensity equal to or higher than a threshold that causes the workpiece to ablate, and penetrates the workpiece. A step of processing the workpiece by irradiating laser light within twice the irradiation intensity at which holes are formed, and a step of peeling the laser processing pressure-sensitive adhesive sheet from the workpiece after processing. .

  First, the adhesive sheet used in the present embodiment will be described. The pressure-sensitive adhesive sheet is used when processing a workpiece by ablation using laser light having a wavelength in the ultraviolet region or laser light capable of absorbing light in the ultraviolet region via a multiphoton absorption process. The configuration is such that at least a pressure-sensitive adhesive layer is provided on the base material (details of the base material and the pressure-sensitive adhesive layer will be described later). In addition, the pressure sensitive adhesive sheet is equal to or higher than the threshold irradiation intensity at which the work piece causes ablation, and is irradiated with a laser beam within twice the irradiation intensity at which the through hole is formed on the work piece. The physical properties are such that the ratio of the extinction coefficients obtained in 1 is less than 1.

吸光係数の比は、粘着シートと被加工物との両者の加工性の差にとって重要なパラメーターである。その理由は、次の通りである。即ち、一般に、ある固体の吸光係数が小さい場合、その固体によるエネルギー吸収は小さいことを意味する。一方、固体中での光吸収は、光の侵入長（固体表面から（１／吸光係数）の有効距離）で起こる。吸光係数が小さいと光の侵入長は長くなるので、固体の体積あたりに蓄積する熱量が少なくなる。即ち、その固体は、レーザー光により加工され難いと言える。よって、前記の吸光係数の比が１未満であると、粘着シートは被加工物よりも加工性が低いことを示す。この観点から、本実施の形態に係る粘着シートは、レーザー加工用として有用であると言える。

The ratio of the extinction coefficient is an important parameter for the difference in processability between the pressure-sensitive adhesive sheet and the workpiece. The reason is as follows. That is, generally, when the extinction coefficient of a certain solid is small, it means that the energy absorption by the solid is small. On the other hand, light absorption in a solid occurs with the penetration depth of light (effective distance of (1 / absorption coefficient) from the solid surface). If the extinction coefficient is small, the penetration depth of light becomes long, so that the amount of heat accumulated per volume of the solid decreases. That is, it can be said that the solid is difficult to be processed by laser light. Therefore, when the ratio of the extinction coefficient is less than 1, it indicates that the pressure-sensitive adhesive sheet has lower processability than the workpiece. From this viewpoint, it can be said that the pressure-sensitive adhesive sheet according to the present embodiment is useful for laser processing.

  Here, the ratio of the extinction coefficients is more preferably 0.9 or less, and further preferably 0.8 or less. However, when the extinction coefficient ratio is 1 or more, cutting or punching of the adhesive sheet proceeds before the workpiece is processed. Thereby, the decomposition product from an adhesive sheet generate | occur | produces between a to-be-processed object and an adhesive sheet, and there exists a problem that the process back surface is contaminated. However, in the present embodiment, since the extinction coefficient ratio is less than 1, such a problem does not occur.

  Next, each process will be described. The step of bonding the pressure-sensitive adhesive sheet and the workpiece can be performed by a conventionally known method using a roll laminator or the like. Bonding is performed via a pressure-sensitive adhesive layer on the surface opposite to the processed surface of the workpiece.

  The step of processing the workpiece is a step of performing laser processing on the workpiece by ablation using laser light. In this step, it is preferable to use the laser beam having a wavelength in the ultraviolet region. In particular, it is more preferable to use a laser beam that causes photochemical ablation without going through a thermal processing process. Furthermore, it is more preferable to use a laser beam that can be condensed into a narrow width of 20 μm or less and can be processed such as cutting. This is because the use of such a laser beam improves the accuracy of the edge of the hole and the cut wall surface due to thermal damage during laser processing and improves the appearance.

  Further, it is preferable to use a laser beam having a irradiation intensity equal to or higher than a threshold value that causes the workpiece to ablate and within twice the irradiation intensity at which a through hole is formed in the workpiece. Moreover, it is preferable to carry out by a pulse laser.

Further, the laser light as described above is preferably one that can be ablated by ultraviolet absorption of 400 nm or less. Specifically, for example, KrF excimer laser (oscillation wavelength 248 nm), XeCl excimer laser (308 nm), YAG laser third harmonic (355 nm) or fourth harmonic (266 nm), or YLF (yttrium lithium) A laser beam having an oscillation wavelength of 400 nm or less such as the third harmonic or the fourth harmonic of a solid-state laser such as fluoride) or YVO ₄ (yttrium vanadate) can be exemplified. In addition, even a laser having a wavelength exceeding 400 nm 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. A laser having a pulse width of 1e- ⁹ seconds (0.000000001 seconds) or less, such as a nearby titanium sapphire laser, is also suitable.

  If a laser beam such as a fundamental wave of YAG laser (wavelength: 1.06 μm) or ruby laser (wavelength: 694 nm) is used, the beam diameter can only be reduced to about 50 μm even if it is condensed. . However, when ultraviolet laser light is used as in the present embodiment, the beam diameter can be further reduced (for example, about 20 μm). Therefore, it is not necessary to make a large margin for cutting.

  The processing performed in this step is shape processing such as cutting processing, drilling processing, marking, grooving processing, scribing processing, or trimming processing. In the case of cutting, it is performed as shown in FIGS. FIG. 1 is a schematic diagram for explaining a cutting process of a workpiece according to the present embodiment. FIG. 2 is a cross-sectional view showing a cutting process according to the present embodiment.

  A workpiece 3 shown in FIGS. 1 and 2 is a laminate of a workpiece 1 and an adhesive sheet 2. The pressure-sensitive adhesive sheet 2 has a configuration in which a pressure-sensitive adhesive layer 2a is provided on a substrate 2b. Bonding of the workpiece 1 and the pressure-sensitive adhesive sheet 2 can be performed by a known method such as a roll laminator or a press. The cutting process is performed by fixing the workpiece 3 on the suction plate 5 of the suction stage 4. Laser light 6 output from a predetermined laser oscillator is collected by a lens and irradiated onto a workpiece. Along with the irradiation, the laser irradiation position is moved along a predetermined processing line to perform cutting processing. For the cutting process, a known laser processing method such as a laser processing method using a galvano scan or an XY stage scan, or a mask imaging type laser processing is used.

  The laser processing conditions are not particularly limited as long as the workpiece 1 is completely cut. In other words, the optimum value of the irradiation intensity may be determined based on the ablation threshold value of the workpiece material. However, in order to avoid the adhesive sheet 2 from being cut, it is desirable that the pressure is not more than twice the processing conditions for forming the through hole in the workpiece 1. Further, the cutting margin can be reduced by narrowing the beam path of the laser beam condensing portion, but it is preferable that the following relationship is satisfied in order to obtain the accuracy of the cut end face.

被加工物１の裏面に粘着シート２を貼らない場合には、被加工物１および吸着ステージ４に由来する分解飛散物が、レーザー加工品のレーザー出射側の切断端面近傍に付着する。しかし、これらの汚染は、本実施の形態に係る粘着シート２を貼ることにより防ぐことができる。

When the pressure-sensitive adhesive sheet 2 is not pasted on the back surface of the workpiece 1, decomposed and scattered materials derived from the workpiece 1 and the suction stage 4 adhere to the vicinity of the cut end surface on the laser emission side of the laser processed product. However, these contaminations can be prevented by sticking the pressure-sensitive adhesive sheet 2 according to the present embodiment.

  In the case of drilling, it is performed as shown in FIG. FIG. 3 is a schematic diagram for explaining the drilling of the workpiece according to the present embodiment. For the drilling, a known laser processing method such as a laser processing method using a galvano scan or an XY stage scan, or a punching processing by mask imaging is used.

  In this step, a sheet having good laser processability or another adhesive sheet may be bonded to the laser incident side. Further, a gas such as helium, nitrogen, oxygen, or the like may be blown onto a laser processed portion. This is because the removal of the residue on the surface of the workpiece on the laser incident side can be facilitated by performing these steps.

  The step of peeling the pressure-sensitive adhesive sheet is a step of peeling the pressure-sensitive adhesive sheet from the processed workpiece (laser processed product 9 shown in FIGS. 2 and 3). The peeling method is not particularly limited, and a conventionally known method can be employed. However, it is preferable not to apply a stress that causes the workpiece to be permanently deformed during peeling. Therefore, from the viewpoint of eliminating such stress, an adhesive sheet whose adhesive strength is reduced by, for example, radiation irradiation or heating may be used. This is because such a pressure-sensitive adhesive sheet has both the holding power during processing and the ease during peeling. When a radiation curable pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, 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 case of semiconductor wafer cutting (dicing), one side of the semiconductor wafer (workpiece) 7 is bonded to the laser processing adhesive sheet 2 provided on the suction stage 4 as shown in FIG. Fix to the dicing frame 8. Further, the laser beam 6 output from a predetermined laser oscillator is condensed and irradiated onto the semiconductor wafer 7 by a lens, and the laser irradiation position is moved along a predetermined processing line to perform cutting processing. . As the laser beam moving means, a known laser processing method such as galvano scan, XY stage scan, mask, or image song processing is used. The processing conditions for the semiconductor wafer are not particularly limited as long as the semiconductor wafer 7 is cut and the adhesive sheet 2 is not cut. A protective sheet may be provided on the laser light incident surface side of the semiconductor wafer 7.

  In such dicing processing of the semiconductor wafer 7, after cutting into individual semiconductor chips (laser processed products), a method of picking up with a conventionally known device such as a die bonder using a push-up pin called a needle, or Individual semiconductor chips can be picked up and collected by a known method such as the method disclosed in Japanese Patent Laid-Open No. 2001-118862.

  In the present embodiment, the workpiece that can be laser processed is not particularly limited as long as it can be laser processed by ablation with the laser beam. For example, various sheet materials, circuit substrates, semiconductor wafers, glass substrates, ceramic substrates, metal substrates, light emitting or receiving element substrates such as semiconductor lasers, MEMS (Micro Electro Mechanical System) substrates, semiconductor packages, cloth, leather, paper, etc. Can be mentioned. Various sheet materials include, for example, polyimide resins, polyester resins, epoxy resins, urethane resins, polystyrene resins, polyethylene resins, polyamide resins, polycarbonate resins, silicone resins, fluorine resins, etc. Molecular film or non-woven fabric, those obtained by imparting physical or optical functions to the resin by stretching, impregnation, etc., metal sheets such as copper, aluminum, and stainless steel, or the above polymer sheet and / or metal sheet directly or The one laminated with an adhesive or the like is raised. Examples of the circuit board include a single-sided, double-sided or multilayer flexible printed board, a rigid board made of glass epoxy, ceramic, metal core board, etc., an optical circuit formed on glass or polymer, or an opto-electric hybrid circuit board. It is done. A specific pressure-sensitive adhesive sheet is bonded to the surface opposite to the laser irradiation surface of the workpiece thus prepared.

  In the present embodiment, the base material may be a single layer or a multilayer. Various shapes such as a film shape or a mesh shape can be selected. The thickness of the base material can be appropriately selected and set within a range that does not impair the operability and workability in each process such as bonding to the workpiece, cutting of the workpiece, peeling of the cut piece, and recovery. it can. Usually, it is set to 500 μm or less, preferably about 3 to 300 μm, more preferably about 5 to 260 μm. Conventional surface treatment can be performed on the surface of the base material in order to improve adhesion, retention, and the like with adjacent layers such as an adsorption stage. Examples of such surface treatments include chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, ionizing radiation treatment, and other chemical or physical treatments, and coating treatment with a primer (for example, an adhesive substance described later). it can.

  In the present embodiment, the pressure-sensitive adhesive layer may be formed of an acrylic or rubber-based pressure-sensitive adhesive. Examples of the acrylic pressure-sensitive adhesive include a polymer of (meth) acrylic acid alkyl ester, and if necessary, a copolymerizable monomer is added to (meth) acrylic acid alkyl ester for the purpose of modification such as adhesiveness, cohesive strength, and heat resistance. Examples thereof include acrylic polymers such as copolymerized copolymers.

  Here, the (meth) acrylic acid alkyl ester means an acrylic acid ester and / or a methacrylic acid ester, and (meth) in the present invention has the same meaning. For example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, isobutyl group, amyl group, isoamyl vine, hexyl group, heptyl group, cyclohexyl group, 2-ethylhexyl group, octyl group, isooctyl group A direct mirror of 30 to 30 carbon atoms, especially 4-18, such as a group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, lauryl group, tridecyl group, tetradecyl group, stearyl group, octadecyl group, dodecyl group Examples thereof include polymers having one or more (meth) acrylic acids having a branched alkyl group as components.

  Other monomers that may form the polymer include, for example, acrylic acid and methacrylic acid, carboxyethyl acrylate and carboxypentyl acrylate, itaconic acid and maleic acid, carboxyl group-containing monomers such as fumaric acid and crotonic acid, or Acid anhydride monomers such as hydrothermal maleic acid and itaconic anhydride, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and (meth) acrylic acid Contains hydroxyl groups such as 6-hydroxyhexyl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate Sulfones such as nomers, styrene sulfonic acid and acrylic sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate and (meth) acryloyloxynaphthalene sulfonic acid 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, dimethylaminoethyl methacrylate) , T-butylaminoethyl methacrylate, etc.), N-vinylpyrrolidone, acryloylmorpholine, vinyl acetate, styrene, acrylonitrile and the like.

  In addition, a polyfunctional monomer or the like can be used as a monomer component for copolymerization, if necessary, for the purpose of crosslinking the acrylic polymer. Examples of such monomers include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di ( Examples include meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol hexa-tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate. One or more polyfunctional monomers can be used, and the amount used is preferably 30% by weight or less of the total monomers from the viewpoint of adhesive properties and the like. The acrylic polymer may have a photopolymerizable carbon-carbon double bond in the molecule. In addition to the above components, conventionally known various additives such as various tackifiers, anti-aging agents, fillers, and coloring agents can be contained. The acrylic polymer can be prepared, for example, by applying an appropriate method such as a solution polymerization method, an emulsion polymerization method, a current polymerization method, or a suspension polymerization method to a mixture of one or more component monomers.

  The acrylic polymer is preferably one that suppresses the inclusion of a low molecular weight substance from the viewpoint of preventing contamination of the workpiece, and the number average molecular weight of the acrylic polymer is preferably 500,000 or more, more preferably 80 to 300. It is about ten thousand.

  In order to prevent peeling of the chip at the time of cutting and to improve the peelability from the chip at the time of peeling, the pressure-sensitive adhesive is preferably a radiation curable pressure-sensitive adhesive that is cured by ultraviolet rays, electron beams or the like. In addition, when using a radiation curing type adhesive as an adhesive, since a radiation is irradiated to an adhesive layer after a cutting process, what has sufficient radiation transparency is preferable for the said base material sheet. As the radiation curable pressure-sensitive adhesive, those having a radiation curable functional group such as a carbon-carbon double bond and exhibiting adhesiveness can be used without particular limitation.

  Examples of the radiation curable pressure-sensitive adhesive include those obtained by blending the aforementioned 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, and tetraethylene glycol di (meth) acrylate. , Pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 4-butylene glycol di (meth) acrylate, 1,6 Esterified product of (meth) acrylic acid such as hexanediol (meth) acrylate and polyhydric alcohol; 2-propenyl-3-butenyl cyanurate, tris (2-meta Rirokishiechiru) isocyanurate or isocyanurate compounds such as isocyanurate. The blending amount of the oligomer component is preferably 5 to 500 parts by weight, particularly preferably 70 to 160 parts by weight with respect to 100 parts by weight of the main polymer (acrylic polymer).

  As an example of a photopolymerization initiator that may be blended in the case of adopting a curing method using ultraviolet rays or the like in the radiation curable component monomer mixture, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2) -Propyl) ketone, α-hydroxy-α, α-methylacetophenone, methoxyacetophenone, 2,2-dimethoxy-2-saphenylacetophenone, 2,2-diethoxyacetophenone, -hydroxycyclohexylphenylketone, 2-methyl-1 -[4- (methylthio) -phenylcoe acetophenone compounds such as 2-morpholinopropane-1, benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether and anisoin methyl ether, 2-methyl-2-hydroxypro Piophenone Α-ketol compounds, ketal compounds such as benzyldimethyl ketal, aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride, 1-phenone-1,1-propanedione-2- (Ο-ethoxycarbonyl) oxime Photoactive oxime compounds such as benzophenone and benzoylbenzoic acid, benzophenone compounds such as 3,3, -dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone and 2,4-dimethyl Thioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, thioxanthone compounds such as 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone, camphorquinone and halogenated ketone, A Such as Le phosphine Inoki Sid and acyl phosphine Honor door, and the like. The crosslink density of the pressure-sensitive adhesive layer is controlled by, for example, a suitable cross-linking agent such as a polyfunctional isocyanate compound, an epoxy compound, a melamine compound, a metal salt compound, a metal chelate compound, an amino resin compound, or a peroxide. It is possible to carry out by an appropriate method such as a method of crosslinking via a method and a method of mixing a low molecular compound having two or more carbon-carbon double bonds and crosslinking by irradiation with energy rays.

  As a method of providing the pressure-sensitive adhesive layer on the substrate, a known method can be employed. For example, an appropriate method such as a method of directly applying to a substrate or a method of transferring an adhesive provided on a sheet coated with a template is used. One or two or more pressure-sensitive adhesive layers may be laminated. The thickness of the pressure-sensitive adhesive layer can be appropriately selected within a range where it does not peel from the workpiece and the target adherend. Usually, it is about 5-300 micrometers, Preferably it is about 10-100 micrometers, More preferably, it is about 20-60 micrometers.

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

(Embodiment 2)
The second embodiment relates to an aspect in which laser processing is performed on a workpiece made of a metal-based material. The second embodiment is different from the first embodiment in that an adhesive sheet having an extinction coefficient of the substrate with respect to laser light having a wavelength of 355 nm is less than 20 cm ⁻¹ .

When the workpiece is made of a metal-based material, when the pressure-sensitive adhesive sheet according to the present embodiment exhibits an extinction coefficient of less than 20 cm ^{−1 in} 355 nm light, the pressure-sensitive adhesive sheet is more difficult to process than the workpiece. Show.

The metallic material exhibits an extinction coefficient of ¹ million cm ⁻¹ or more. Accordingly, with respect to the penetration length of the laser beam, the pressure-sensitive adhesive sheet is longer than the metal-based material. Therefore, even if the adhesive sheet and the workpiece are both irradiated with the same laser light, the amount of heat accumulated per volume of the adhesive sheet can be reduced compared to the workpiece. As a result, it can be made more difficult to process than the workpiece.

The extinction coefficient is more preferably 100 cm ⁻¹ or less, and particularly preferably 50 cm ⁻¹ or less. This is because there is an advantage that a reaction by light hardly occurs.

  The metal-based material includes a similar metal. More specifically, gold, SUS, copper, iron, aluminum, silicon, titanium, nickel, tungsten, zirconia, and the like can be given.

  The method for manufacturing a laser processed product according to the second embodiment can be performed in the same manner as in the first embodiment.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example, unless the summary is exceeded.

(Example 1)
On a polyethylene film (base material) having a thickness of 50 μm, an acrylic pressure-sensitive adhesive solution that can be cured by ultraviolet rays was applied and dried to form a pressure-sensitive adhesive layer having a thickness of 10 μm to obtain a pressure-sensitive adhesive sheet. With respect to this pressure-sensitive adhesive sheet, when the absorbance at 355 nm was measured with a spectrophotometer (U3410 manufactured by Hitachi, Ltd.) and the extinction coefficient was determined, it was 41 cm ⁻¹ . The base material acrylic pressure-sensitive adhesive solution was prepared as follows. That is, an acrylic polymer obtained by copolymerizing butyl acrylate, ethyl acrylate, 2-hydroxyacrylate, and acrylic acid in a weight ratio of 60/40/4/1 (weight average molecular weight (number average molecular weight) approximately 800,000) 100 parts by weight, 90 parts by weight of dipentaerythritol monohydroxypentaacrylate as a photopolymerizable compound, 5 parts by weight of benzyldimethyl ketal (Irgacure 651) as a photopolymerization initiator, a polyisocyanate compound (trade name “ 2 parts by weight of "Coronate L" (manufactured by Nippon Polyurethane) was blended. Further, the blended product was uniformly dissolved in toluene as an organic solvent to prepare an acrylic pressure-sensitive adhesive solution.

  The number average molecular weight of the synthesized acrylic polymer was measured by the following method. That is, 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). Measurement conditions are: GPC device: manufactured by Tosoh Corporation, HLC-8120GPC, column: manufactured by Tosoh Corporation, (GMHHR-H) + (GMHHR-H) + (G2000HHR), flow rate: 0.8 ml / min, concentration: 0.1 wt%, Injection volume: 100 μl, column temperature: 40 ° C., eluent: THF.

Next, when the absorbance of polystyrene (thickness: 100 μm) used as a workpiece was measured and the extinction coefficient was determined, it was 48 cm ⁻¹ . The ratio of the extinction coefficient of the pressure-sensitive adhesive sheet / polystyrene was 0.85.

  Subsequently, one surface of the polystyrene and the pressure-sensitive adhesive sheet were bonded together with a roll laminator so that the pressure-sensitive adhesive layer became an adhesive surface. This was placed on an XY stage on which a glass epoxy resin suction plate in a processing apparatus was placed so that the workpiece was on the upper side. Further, the third harmonic (355 nm) of a YAG laser having an average output of 5 W and a repetition frequency of 30 kHz is condensed to a 25 μm diameter on the polystyrene surface by an fθ lens, and the laser beam is scanned at a speed of 20 mm / second by a galvano scanner. And cut. At this time, it was confirmed that the pressure-sensitive adhesive sheet was not cut and only the workpiece was cut. Thereafter, when the pressure-sensitive adhesive sheet was peeled from the polystyrene and the periphery of the processed hole on the pressure-sensitive adhesive sheet bonding surface (laser emission surface) was observed, no deposit was observed. Since the adhesive sheet was not cut, no contamination from the adsorption stage was confirmed.

(Comparative Example 1)
In Comparative Example 1, the workpiece was processed in the same manner as in Example 1 except that laser processing was performed without attaching an adhesive sheet. Observation of the periphery of the cut portion of the polystyrene (workpiece) on the laser emission surface side confirmed that a large amount of the degradation residue of polystyrene and the degradation residue of the glass epoxy resin adsorption plate adhered.

(Comparative Example 2)
In Comparative Example 2, laser processing was performed in the same manner as in Example 1 except that polyethylene terephthalate (thickness: 100 μm, hereinafter abbreviated as PET) was used as the pressure-sensitive adhesive sheet. Here, the extinction coefficient of the PET base adhesive sheet was 80 cm ⁻¹ , and the extinction coefficient ratio of the adhesive sheet / workpiece was 1.7.

  After the laser processing, when the work piece and the pressure sensitive adhesive sheet were observed, the polystyrene was cut, but the pressure sensitive adhesive sheet was greatly damaged, and bubbles containing decomposition product residues of the pressure sensitive adhesive sheet were generated between the pressure sensitive adhesive sheet and the polystyrene. . Furthermore, when the adhesive sheet was peeled off and the periphery of the cut portion on the laser emission surface side was observed, it was confirmed that a large amount of a degradation product residue of polyethylene terephthalate was adhered.

(Example 2)
In Example 2, except that a film made of an ethylene vinyl acetate copolymer (thickness 100 μm) was used as the base material of the pressure-sensitive adhesive sheet, and a silicon wafer (thickness 100 μm) was used as the workpiece, The workpiece was laser processed in the same manner as in Example 1. Here, the extinction coefficient of the adhesive sheet of the film base material made of an ethylene vinyl acetate copolymer was 19.8 cm ⁻¹ .

  When the workpiece and the adhesive sheet were observed after laser processing, it was confirmed that the adhesive sheet was not cut and only the workpiece was cut. Thereafter, the pressure-sensitive adhesive sheet was peeled off, and the periphery of the cut surface of the pressure-sensitive adhesive sheet bonding surface (laser emission surface) was observed, and no deposit was observed.

(Example 3)
In Example 3, the same procedure as in Example 1 was used, except that a film made of polypropylene / polybutadiene polymer (Dynalon HSBR manufactured by JSR Corporation, thickness 100 μm) was used as the base material of the pressure-sensitive adhesive sheet. Laser processing was performed. Here, the extinction coefficient of the adhesive sheet of the HSBR substrate was 15 cm ⁻¹ .

  When the workpiece and the adhesive sheet were observed after laser processing, it was confirmed that the adhesive sheet was not cut and only the workpiece was cut. Thereafter, the pressure-sensitive adhesive sheet was peeled off, and the periphery of the cut surface of the pressure-sensitive adhesive sheet bonding surface (laser emission surface) was observed, and no deposit was observed.

It is the schematic for demonstrating the laser processing of the to-be-processed object which concerns on embodiment of this invention. It is a cross-sectional schematic diagram for demonstrating the laser processing which concerns on the said embodiment. It is the schematic for demonstrating other laser processing of the to-be-processed object which concerns on the said embodiment. 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 Laser processing adhesive sheet 2a Adhesive layer 2b Base material 3 Workpiece 4 Adsorption stage 5 Adsorption plate 6 Laser light 7 Semiconductor wafer (workpiece)

Claims (6)

Using an adhesive sheet for laser processing, the workpiece is irradiated with laser light having a wavelength in the ultraviolet region or laser light that enables light absorption in the ultraviolet region via a multiphoton absorption process, and the workpiece is ablated. A method of manufacturing a laser processed product to be processed,
As the pressure-sensitive adhesive sheet for laser processing, a sheet having at least a pressure-sensitive adhesive layer provided on a base material and having a ratio of an extinction coefficient represented by the following formula of less than 1 is used. A step of attaching an adhesive sheet for laser processing to the laser light emitting surface side through the adhesive layer;
A step of processing the workpiece by irradiating the workpiece with a laser beam that is equal to or higher than a threshold irradiation intensity that causes ablation and is within twice the irradiation intensity at which a through hole is formed on the workpiece. When,
And a step of peeling the laser processing pressure-sensitive adhesive sheet from the processed object after processing.

Using an adhesive sheet for laser processing, a workpiece made of a metal-based material is irradiated with laser light having a wavelength in the ultraviolet region or laser light capable of absorbing light in the ultraviolet region via a multiphoton absorption process. A method of manufacturing a laser processed product for processing a workpiece by ablation,
As the pressure-sensitive adhesive sheet for laser processing, a substrate having at least a pressure-sensitive adhesive layer provided thereon and having an extinction coefficient of less than 20 cm ⁻¹ for laser light having a wavelength of 355 nm is used. A step of attaching a pressure-sensitive adhesive sheet for laser processing to the light emitting surface side through the pressure-sensitive adhesive layer;
A step of processing the workpiece by irradiating the workpiece with a laser beam that is equal to or higher than a threshold irradiation intensity that causes ablation and is within twice the irradiation intensity at which a through hole is formed on the workpiece. When,
And a step of peeling the laser processing pressure-sensitive adhesive sheet from the processed object after processing.   2. The laser processed product according to claim 1, wherein the workpiece is a circuit board, a semiconductor wafer, a metal substrate, a semiconductor laser emitting or receiving element substrate, a MEMS substrate, or a semiconductor package. Method.   The method of manufacturing a laser processed product according to claim 2, wherein a semiconductor wafer or a metal substrate is used as the workpiece.   The method of manufacturing a laser processed product according to any one of claims 1 to 4, wherein the step of processing the workpiece is a step of cutting or punching the workpiece. The adhesive sheet for laser processing used with the manufacturing method of the laser processed product of any one of Claims 1-5.

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