TW202344659A - Protective sheet for workpiece processing and manufacturing method for singulated workpiece - Google Patents

Abstract

To provide a protective sheet for workpiece processing that can reduce the crack generation rate of singulated workpieces after grinding even when obtaining a singulated workpiece by grinding a workpiece with LDBG. A protective sheet for workpiece processing has a substrate and an adhesive layer arranged on the substrate. The substrate has a support material and a soft material. The soft material and the adhesive layer are arranged on one main surface of the support material in this order. The product of the tensile modulus of the substrate and the thickness of the substrate is 100,000 N/m or more. The tensile modulus of the soft material is 450 MPa or less.

Description

Method for manufacturing protective sheet for workpiece processing and individual workpiece flakes

The present invention relates to a protective sheet for workpiece processing and a method of manufacturing an individual workpiece into pieces. In particular, it relates to a protective sheet for workpiece processing suitable for a method of grinding the back side of a workpiece and dividing the workpiece into individual pieces based on stress, and workpiece processing using this protective sheet. A method for manufacturing individual pieces of workpieces using protective sheets.

In the process of miniaturization and multi-function of various electronic devices, the semiconductor chips mounted in these devices are also required to be miniaturized and thin. In order to reduce the thickness of the wafer, the back surface of the semiconductor wafer is usually ground to adjust the thickness. In addition, in order to obtain a thinned wafer, a process method called Dicing Before Grinding (DBG) is sometimes used, in which a groove of a predetermined depth is formed from the surface side of the wafer by a cutting knife, and then the wafer is then The back side of the wafer is ground, and the wafer is individually sliced by grinding to obtain wafers. DBG can perform backside grinding of wafers and individual wafers at the same time, so thin wafers can be manufactured efficiently.

In the past, when grinding the backside of a semiconductor wafer or manufacturing individual workpiece flakes such as semiconductor wafers by DBG, etc., in order to protect the circuits on the front side of the workpiece or to retain the workpiece and the individual workpiece flakes, affixes were usually attached to the front side of the workpiece. Adhesive tape called backing pad.

As a back polishing pad used in DBG, an adhesive tape including a base material and an adhesive layer provided on one side of the base material is used. As an example of such an adhesive tape, Patent Document 1 discloses an adhesive tape provided with a high Young's modulus base material, with a buffer layer provided on one side of the base material and an adhesive layer provided on the other side.

In recent years, as a modification of the pre-dicing method, a method has been proposed in which a modified region is provided inside the wafer using a laser, and the wafer is divided into individual wafers based on the stress during grinding of the backside of the wafer. Hereinafter, this method may be described as LDBG (Laser Dicing Before Grinding). In LDBG, the wafer is cut along the crystallographic direction starting from the modified area. Therefore, chipping can be reduced more than the pre-cutting method using a dicing knife. In addition, compared with DBG in which a trench of a predetermined depth is formed on the front surface of the wafer by a dicing blade, there is no area where the wafer is cut off by the dicing blade, that is, the kerf width is extremely small, so the wafer yield is excellent. [Advanced technical documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2015-183008

[Problem to be solved by the invention]

However, when individual workpieces such as wafers are diced using LDBG using the adhesive tape described in Patent Document 1, the individual diced workpieces may move slightly due to the shearing force applied to the individual diced workpieces such as wafers. The problem occurs when individual pieces of the workpiece are in contact with each other. As a result, the probability (crack occurrence rate) of generating cracks (unwanted cracks) in individual flakes of the workpiece increases. The increased incidence of cracks is also caused by the extremely small width of the incision as mentioned above.

In view of this fact, the object of the present invention is to provide a protective sheet for workpiece processing that can reduce the number of individual workpiece pieces after grinding even if the workpiece is ground by LDBG to obtain individual pieces of the workpiece. The incidence of cracks. [Means used to solve problems]

Aspects of the present invention are as follows. [1] A protective sheet for workpiece processing, which has a base material and an adhesive layer disposed on the base material, wherein The base material has a support material and a soft material, and a soft material and an adhesive layer are sequentially arranged on one main surface of the support material; The product of the tensile elastic coefficient of the base material and the thickness of the base material is more than 100000N/m; The tensile elastic coefficient of soft materials is 450MPa or less. [2] The protective sheet for workpiece processing according to [1], wherein the base material further has a buffer material, and the buffer material is arranged on the other main surface of the support material. [3] The protective sheet for workpiece processing as described in [1] or [2], wherein the thickness of the adhesive layer is less than 50 μm. [4] The protective sheet for workpiece processing according to any one of [1] to [3], wherein the thickness of the support material is 20 μm or more and 80 μm or less. [5] The protective sheet for workpiece processing according to any one of [1] to [4], wherein the thickness of the soft material is 10 μm or more and 75 μm or less. [6] The protective sheet for workpiece processing according to any one of [2] to [5], wherein the thickness of the buffer material is 10 μm or more and 75 μm or less. [7] The protective sheet for workpiece processing according to any one of [1] to [6], wherein the stress relaxation rate of the soft material is 50% or less. [8] The protective sheet for workpiece processing according to any one of [1] to [7], which includes the step of individually chipping the workpiece into individual workpiece pieces on the back surface of the workpiece having a modified region formed therein by grinding. , attached to the front of the workpiece and used.

[9] A method for manufacturing individual flakes of workpieces, which has the following steps: Attach the protective sheet for workpiece processing as described in any one of [1] to [8] to the front of the workpiece; Formation of modified areas inside the workpiece from the front or back of the workpiece; Attach a protective sheet for workpiece processing to the front side, grind the workpiece from the back side to form a modified area, and individually slice the workpiece into a plurality of individual workpiece pieces starting from the modified area; and The protective sheet for workpiece processing is peeled off from the workpiece that has been divided into individual pieces. [Invention effect]

According to the present invention, it is possible to provide a protective sheet for workpiece processing that can reduce the occurrence rate of cracks in the ground individual workpiece pieces even when the workpiece is ground by LDBG to obtain individual workpiece pieces.

[Form used to implement the invention]

Hereinafter, the present invention will be described in detail based on specific embodiments and drawings. First, the main terms used in this manual will be explained.

The workpiece refers to a plate-like body to which a protective sheet for workpiece processing related to this embodiment is attached and is subsequently cut into individual pieces. Examples of the workpiece include a circular wafer (including a case with an orientation plane), a square panel level package, a tape (rectangular substrate) sealed with a molding resin, and the like. Among them, wafers are preferred from the viewpoint of easily obtaining the effects of the present invention. The wafer may be a semiconductor wafer such as silicon wafer, gallium arsenide wafer, silicon carbide wafer, gallium nitride wafer, indium phosphide wafer, etc.; glass wafer, lithium tantalate wafer, niobium An insulator wafer such as a lithium acid wafer may also be used, or a reconfiguration wafer composed of resin and semiconductor used for manufacturing fan-out packages and the like. From the viewpoint of easily obtaining the effects of the present invention, a semiconductor wafer or an insulator wafer is preferred as the wafer, and a semiconductor wafer is more preferred.

Individual chipping of the workpiece refers to dividing the workpiece into each circuit to obtain individual pieces of the workpiece. For example, when the workpiece is a wafer, the individual pieces of the workpiece are wafers; when the workpiece is a strip (rectangular substrate) that has been subjected to panel-level packaging or molding resin sealing, the individual pieces of the workpiece are semiconductor packages.

The "front" of the workpiece refers to the surface on which circuits, electrodes, etc. are formed, and the "back" of the workpiece refers to the surface where no circuits, etc. are formed. The electrode may be a convex electrode such as a bump.

DBG refers to a method in which a groove of a predetermined depth is formed on the front side of the workpiece, then ground from the back side of the workpiece, and the workpiece is divided into individual pieces by grinding. The groove formed on the front side of the workpiece is formed by blade cutting, laser cutting, plasma cutting, etc.

In addition, LDBG is a modification of DBG. It refers to using laser to set up a fragile modified area inside the workpiece (such as a wafer). The stress during grinding of the back side of the workpiece causes cracks to develop starting from the modified area. A method of cutting workpieces into individual pieces.

The "group of individual workpiece flakes" refers to a plurality of individual workpiece flakes held on the workpiece processing protective sheet related to the present invention after the workpieces are individually flaked. These individual pieces of workpieces as a whole have the same shape as the semiconductor wafer. In addition, the "wafer group" refers to a plurality of wafers that are held on the protective sheet for workpiece processing of the present invention after wafers serving as workpieces are individually sliced. These wafers as a whole have the same shape as the wafer.

"(Meth)acrylate" is used as a term indicating both "acrylate" and "methacrylate", and the same applies to other similar terms.

"Energy rays" refer to ultraviolet rays, electron beams, etc., with ultraviolet rays being preferred.

"Weight average molecular weight", unless otherwise specified, refers to the polystyrene-converted value measured by gel permeation chromatography (GPC). For measurement based on such a method, for example, high-speed chromatography columns "TSK guard column H _XL -H", "TSK Gel GMH _XL ", and "TSK Gel G2000 _H The device is a high-speed GPC device "HLC-8120GPC" manufactured by Tosoh Corporation. The column temperature is 40°C, the liquid delivery temperature is 1.0 mL/min, and the detector is a differential refractometer.

The release sheet is a sheet that supports the adhesive layer in a peelable manner. Sheet-like material is used as a concept including a film without limiting the thickness.

The mass ratio in the description of compositions such as the adhesive layer composition is based on the active ingredient (solid content), and the solvent is not included unless otherwise specified.

(1. Protective sheet for workpiece processing) The workpiece processing protective sheet 1 according to this embodiment has a base material 10 and an adhesive layer 20 arranged on the base material 10 as shown in FIG. 1A . Furthermore, the base material 10 has a support material 12 and a soft material 14 . In the workpiece processing protective sheet 1 , the soft material 14 is arranged between the support material 12 and the adhesive layer 20 . Viewed from the support material 12 , the soft material 14 and the adhesive layer 20 are arranged in sequence on one main surface 12 a of the support material 12 .

In this embodiment, as shown in FIG. 2 , the workpiece processing protective sheet 1 is used with the main surface 20 a of the adhesive layer 20 attached to the front surface 100 a of the workpiece 100 (for example, a wafer). The front surface 100a of the workpiece 100 is a surface having circuits, electrodes, and the like. The surface with the circuit may be a surface on which the circuit is exposed, or may be the main surface of a protective layer formed on the circuit to protect the circuit. In addition, convex electrodes such as bumps may be formed on the circuit.

In this embodiment, the workpiece to which the protective sheet for workpiece processing is attached is individually sliced into a plurality of individual workpiece slices (for example, wafers). As a method of individualizing workpieces, DBG can be used. However, the workpiece processing protective sheet 1 according to this embodiment is suitable for individualizing workpieces based on LDBG.

Therefore, after the modified region is formed inside the workpiece, the workpiece 100 (for example, a wafer) with the workpiece processing protective sheet 1 attached to the front surface 100a is ground, and the back surface 100b is ground. The back surface 100b is the main surface opposite to the front surface 100a. .

Once grinding is performed, the workpiece continues to become thinner, and at the same time, by applying shear force or pressure to the modified area formed inside the workpiece, cracks are generated in the modified area and progress to both sides of the workpiece. As a result, the workpiece is individually sliced. In individual chipping based on LDBG, since there is almost no area cut off from the workpiece, the distance (kerf width) between the individual workpiece chippings and adjacent individual workpiece chippings is very small. Small.

In addition, the time point for individualizing the workpiece is not at the same time, but after grinding and individualizing a part of the workpiece, and until the entire workpiece is individualized. Therefore, individual pieces of the workpiece are also continuously subjected to the shear force from the grinding wheel. The non-smooth grinding wheel surface constantly rotates and contacts the individual flakes of the workpiece. Therefore, the same shear force is not applied to all the individual flakes of the workpiece at the same time. The shear force applied to the individual flakes of the workpiece varies with each individual workpiece. Different flakes. Therefore, in a direction parallel to the workpiece plane (that is, the plane of the individual workpiece flakes group), the individual workpiece flakes move unevenly and the slit width is small, so that the individual workpiece flakes may come into contact with each other. Once such contact occurs, problems such as cracks occurring in individual flakes of the workpiece and a decrease in the yield of individual flakes of the workpiece may occur.

The protective sheet for workpiece processing according to this embodiment has a base material and an adhesive layer described later, and therefore can effectively suppress the occurrence of the above-mentioned problems.

The protective sheet for workpiece processing is not limited to the structure shown in FIG. 1A , and may have other layers as long as the effects of the present invention can be obtained. That is, if the base material 10 and the adhesive layer 20 have the above-mentioned structures, for example, another layer may be formed between the support material 12 and the soft material 14 to protect the adhesive layer 20 until the adhesive layer 20 is attached to the object. , a release sheet may also be disposed on the main surface 20a of the adhesive layer 20.

Especially in this embodiment, as shown in FIG. 1B , from the viewpoint of further suppressing the occurrence of the above-mentioned problems, the base material 10 is preferably provided with a buffer material 16 in addition to the support material 12 and the soft material 14 . The buffer material 16 is formed on the main surface 12b of the support material 12 opposite to the main surface 12a on which the soft material 14 is formed. By having the buffer material 16, the occurrence of the above-mentioned problems can be further suppressed.

On the other hand, from the viewpoint of reducing the cost of raw materials and reducing the risk of thickness variation during base material manufacturing due to an increase in the thickness of the constituent layers, it is preferable not to substantially include the cushioning material 16 . Not substantially present means that there is no buffer material at all or the thickness is less than 1 μm.

In the following, the components of the workpiece processing protective sheet 1 shown in FIG. 1B will be described in detail.

(2.Substrate) In this embodiment, as shown in Figures 1A and 1B, the base material is a composite material having a plurality of constituent materials. That is, in Figure 1A, the base material 10 is composed of the support material 12 and the soft material 14; in Figure 1B, the base material 10 is composed of the support material 12, the soft material 14 and the cushioning material 16. In this embodiment, the base material has the following physical properties.

(2.1 The product of the tensile elastic coefficient of the base material and the thickness of the base material) The base material must have sufficient rigidity to prevent deformation of the workpiece fixed to the adhesive layer and the workpiece processing protective sheet when the workpiece is ground by shear force and pressure. In this embodiment, such rigidity is evaluated by the product of the tensile elastic coefficient (Young's coefficient) of the base material and the thickness of the base material.

In this embodiment, the product of the tensile elastic coefficient of the base material and the thickness of the base material is 100,000 N/m or more. When the product of the tensile elastic coefficient of the base material and the thickness of the base material is within the above range, the rigidity of the protective sheet for workpiece processing is ensured and movement of individual workpiece fragments is difficult to occur. Therefore, individual workpiece fragmentation after grinding of the workpiece can be suppressed. The occurrence rate of chemical cracks. For example, when the tensile elastic coefficient of the base material is 2500 MPa and the thickness of the base material is 100 μm, the product of the tensile elastic coefficient of the base material and the thickness of the base material becomes 250000 N/m.

The product of the tensile elastic coefficient of the base material and the thickness of the base material is preferably 150,000 N/m or more, more preferably 180,000 N/m or more, and more preferably 200,000 N/m or more.

On the other hand, the upper limit of the product of the tensile elastic coefficient of the base material and the thickness of the base material is not particularly limited, but from the viewpoint of workability and cost of attaching the workpiece processing protective sheet to the base material, 600000N/m The following is preferred, 400,000N/m or less is more preferred, and 300,000N/m or less is more preferred.

The product of the tensile elastic coefficient of the base material and the thickness of the base material may be adjusted to fall within the above range. In this embodiment, the tensile elastic coefficient of the base material is preferably in the range of 1000 to 4000 MPa, and more preferably in the range of 1300 to 3000 MPa. In addition, the thickness of the base material is preferably in the range of 50 to 200 μm, and more preferably in the range of 70 to 150 μm.

In this embodiment, the tensile elastic coefficient of the base material is the tensile elastic coefficient (Young's coefficient) at 23°C. The tensile elastic coefficient is measured based on JIS K 7127. That is, the measurement is performed in the same manner as the measurement method specified in JIS K 7127, but the measurement conditions may be different. Specific measurement methods are described in the Examples.

Below, the support material, soft material and buffer material of the base material components are explained.

(2.2 Support material) The support material is a member that serves as the rigidity of the base material. In this embodiment, the support material is composed of various resin films used as the base material of the back polishing pad. The material of the support material may be selected so that the product of the tensile elastic coefficient of the base material and the thickness of the base material falls within the above range.

In this embodiment, examples of the resin film constituting the support material include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and fully aromatic polyester. Polyester; resins such as polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polystyrene, polyetherketone, biaxially stretched polypropylene, etc. membrane. Among these, two or more types of resin films may be combined.

In addition, the thickness of the support material may be selected so that the product of the tensile elastic coefficient of the base material and the thickness of the base material falls within the above range.

In this embodiment, from the viewpoint of making it easier to keep the product of the tensile elastic coefficient of the base material and the thickness of the base material within the above range, the material of the support material is preferably polyester, and polyethylene terephthalate is used as the material. Diester is preferred. In addition, the thickness of the support material is preferably in the range of 20 μm or more and 80 μm or less. In addition, even if they are made of the same material, as the density increases, the tensile elastic coefficient tends to increase.

In addition, the support material may also contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc. within the scope that does not impair the effects of the present invention. Moreover, the support material may be a transparent thing or an opaque thing. For example, the support material may have a colored layer for the purpose of identifying the protective sheet for workpiece processing.

At least one main surface of the support material may be subjected to an adhesion treatment such as corona treatment in order to improve the adhesion with the soft material formed on the main surface or with the soft material and the buffer material. In addition, an easy-adhesion layer may be formed on at least one main surface of the support material in order to improve the adhesion with the soft material formed on the main surface or with the soft material and the buffer material.

The easy-adhesive layer-forming composition for forming the easy-adhesive layer is not particularly limited, and examples thereof include combinations containing polyester resins, urethane resins, polyester urethane resins, acrylic resins, and the like. things. The composition for forming an easily adhesive layer may contain a cross-linking agent, a photopolymerization initiator, an antioxidant, a softener (plasticizer), a filler, a rust inhibitor, a pigment, a dye, etc. as necessary.

The thickness of the easy-adhesion layer is preferably 0.01 to 10 μm, and preferably 0.03 to 5 μm.

In addition, in this embodiment, the thickness of the support material includes, in addition to the thickness of the resin film constituting the support material, the thickness of the above-mentioned colored layer, easy-adhesion layer, etc.

(2.3 Soft materials) Soft material is a component that is softer than the support material. Soft materials have the following physical properties in order to relax the shear force exerted on individual pieces of the workpiece when grinding the workpiece.

(2.3.1 Tensile elastic coefficient of soft materials) In this embodiment, the tensile elasticity coefficient (Young's coefficient) of the soft material is 450 MPa or less. When the tensile elastic coefficient of the soft material is within the above range, the soft material exhibits moderate cushioning properties and can alleviate the shear force applied to individual pieces of the workpiece during grinding. As a result, the occurrence rate of cracks in individual pieces of the workpiece after grinding can be suppressed.

The tensile elasticity coefficient of the soft material is preferably 400MPa or less, more preferably 370MPa or less, more preferably 340MPa or less, and particularly preferably 200MPa or less.

On the other hand, the lower limit of the tensile elastic coefficient of the soft material is not particularly limited, but is preferably 100 MPa or more from the viewpoint of making the soft material stable, easy to handle, and cost-effective.

In this embodiment, the tensile elastic coefficient of the soft material is the same as the tensile elastic coefficient of the base material at 23°C. The tensile elastic coefficient of soft materials is measured based on JIS K 7127. That is, the measurement is performed in the same manner as the measurement method specified in JIS K 7127, but the measurement conditions may be different. Specific measurement methods are described in the Examples.

(2.3.2 Stress relaxation rate of soft materials) The stress relaxation rate of soft materials is preferably less than 50%. When the grinding of the workpiece is started and the workpiece is individually divided into a plurality of individual workpiece pieces, and the connected state before individualization and the individual workpiece pieces after individualization are mixed, there is a grinding wheel applied to each individual piece. The occurrence of uneven pressure on individual pieces of workpiece. Among individual pieces of workpieces where the applied pressure becomes non-uniform, if the individual pieces of workpieces located in a region where the pressure is somewhat high are soft materials and have a high stress relaxation rate, the high pressure is applied to the protective sheet for workpiece processing. Pushing in the direction (soft material deforms), there is a tendency for individual pieces of the workpiece to tilt. As a result, an unexpected load is likely to be applied to the moved individual workpiece fragments, and the individual workpiece fragments are more likely to come into contact with each other, thereby tending to cause cracks.

Therefore, when the stress relaxation rate of the soft material is within the above range, the deformation of the soft material accompanying the pressure on the individual pieces of the workpiece can be suppressed. Therefore, the occurrence rate of cracks in the individual pieces of the workpiece after grinding can be further reduced.

The stress relaxation rate of soft materials is preferably 40% or less, and more preferably 30% or less.

On the other hand, the lower limit of the stress relaxation rate of the soft material is not particularly limited, but from the viewpoint of the physical properties of the soft material, cost, etc., it is preferably 5% or more.

In this embodiment, the stress relaxation rate of the soft material is measured using a tensile testing machine. Specific measurement methods are described in the Examples.

(2.3.3 Materials of soft materials) In this embodiment, the soft material is preferably made of a resin film. The material of the soft material may be selected so that the tensile elastic coefficient of the soft material (and, if necessary, the stress relaxation rate of the soft material) falls within the above range.

In this embodiment, the material of the soft material is preferably a polyolefin resin film. Examples of the polyolefin resin include ultra-low density polyethylene (VLDPE, density: 880 kg/m ³ or more and less than 910 kg/m ³ ), low-density polyethylene (LDPE, density: 910 kg/m ^{3 or more and less than 942 kg/m 3} ). m ³ ), high-density polyethylene (HDPE, density: 942kg/m ³ or more) and other polyethylene resins, polypropylene resins, polyethylene-polypropylene copolymers, olefin elastomers (TPO), cyclic olefin resins, poly Vinyl chloride (PVC), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-maleic anhydride copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer Materials, ethylene-(meth)acrylate-maleic anhydride copolymer, etc. These polyolefin resins can be used individually or in combination of 2 or more types.

Among the above-mentioned polyolefin resins, from the viewpoint of setting the physical properties of the soft material within the above-mentioned range, polyethylene resin is preferable, and low-density polyethylene (LDPE) is more preferable. In addition, even if they are made of the same material, if the density is lowered, the tensile elastic modulus tends to be lowered.

The thickness of the soft material is preferably 10 μm or more from the viewpoint of exerting the above-mentioned cushioning properties. On the other hand, if the thickness of the soft material is too large, the entire workpiece processing protective sheet will be easily deformed in the shearing direction during grinding, so individual pieces of the workpiece will tend to move and cracks will tend to occur. Therefore, from this point of view, the thickness of the soft material is preferably 75 μm or less, and more preferably 40 μm or less.

In addition, the ratio of the thickness of the support material to the thickness of the soft material (thickness of the support material/thickness of the soft material) is not particularly limited, but from a manufacturing point of view, it is preferably in the range of 0.5 to 5.

The soft material may also contain plasticizers, lubricants, infrared absorbers, ultraviolet absorbers, fillers, colorants, antistatic agents, antioxidants, catalysts, etc. within the scope that does not impair the effects of the present invention. In addition, the soft material may be transparent or opaque, and may be colored or evaporated as needed.

(2.4 Buffer material) In this embodiment, the buffer material is an optional element in the workpiece processing protective sheet. A workpiece (such as a wafer) to which a protective sheet for workpiece processing is attached is placed on the adsorption table with the protective sheet for workpiece processing interposed therebetween during grinding. At this time, the surface of the base material on which the adhesive layer is not formed is connected to the adsorption stage. Once the cushioning material is formed on the side where the adhesive layer is not formed, the cushioning material will be in close contact with the adsorption stage while burying the unevenness caused by foreign matter on the adsorption stage. As a result, cracks in individual pieces of the workpiece (for example, wafers) caused by foreign matter can be reduced. Therefore, by having a buffer material on the base material, the occurrence rate of cracks can be further reduced.

From the viewpoint of exerting the above-mentioned functions, the cushioning material is a softer member than the supporting material. In this embodiment, the material of the buffer material is preferably a polyolefin resin film. Examples of the polyolefin resin include ultra-low density polyethylene (VLDPE, density: 880 kg/m ³ or more and less than 910 kg/m ³ ), low-density polyethylene (LDPE, density: 910 kg/m ^{3 or more and less than 942 kg/m 3} ). m ³ ), high-density polyethylene (HDPE, density: 942kg/m ³ or more) and other polyethylene resins, polypropylene resins, polyethylene-polypropylene copolymers, olefin elastomers (TPO), cyclic olefin resins, poly Vinyl chloride (PVC), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-maleic anhydride copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer Materials, ethylene-(meth)acrylate-maleic anhydride copolymer, etc. These polyolefin resins can be used individually or in combination of 2 or more types.

Among the above-mentioned polyolefin resins, as the material of the buffer material, polyethylene resin is preferred, and low-density polyethylene (LDPE) is preferred.

The thickness of the buffer material is preferably 10 μm or more from the viewpoint of exerting the above-mentioned foreign matter burying property. On the other hand, if the thickness of the buffer material is too large, the entire workpiece processing protective sheet will be easily deformed in the shearing direction during grinding, so cracks will tend to easily occur. Therefore, the thickness of the buffer material is preferably 75 μm or less, and more preferably 40 μm or less.

(3. Adhesive layer) The adhesive layer is attached to the front side of the workpiece (that is, the side with circuits, electrodes, etc.), which protects the front side and supports the workpiece until it is peeled off from the front side. The adhesive layer may be composed of one layer (single layer), or may be composed of two or more layers. When the adhesive layer has a plurality of layers, the plurality of layers may be the same as or different from each other, and the combination of the layers constituting the plurality of layers is not particularly limited.

In this embodiment, the thickness of the adhesive layer is preferably less than 50 μm, more preferably 45 μm or less, and more preferably 40 μm or less. When the thickness of the adhesive layer is within the above-mentioned range, minute movement of individual workpiece flakes caused by pressure applied to the workpiece or the group of individual workpiece flakes during grinding can be suppressed. As a result, the probability that individual pieces of the workpiece come into contact with each other is reduced, and the occurrence rate of cracks can be suppressed.

On the one hand, from the viewpoint of burying circuits, electrodes, etc. formed on the workpiece in the adhesive layer, the thickness of the adhesive layer is preferably 10 μm or more.

In addition, the thickness of the adhesive layer means the thickness of the entire adhesive layer. For example, the thickness of an adhesive layer composed of a plurality of layers means the total thickness of all the layers constituting the adhesive layer.

The composition of the adhesive layer is not limited as long as it has a level of adhesiveness that can protect the front surface of the workpiece. In this embodiment, the adhesive layer is preferably composed of, for example, an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, or the like.

In addition, the adhesive layer is preferably formed of an energy ray curable adhesive. The adhesive layer of the protective sheet for workpiece processing is made of energy ray-hardening adhesive. When it is attached to the workpiece, it adheres to the workpiece with high adhesion. When it is peeled off from the workpiece, it can be irradiated with ultraviolet rays to improve the adhesion. reduce. Therefore, it appropriately protects the circuits of the workpiece, etc., and prevents the circuits, electrodes, etc. on the front side of the workpiece from being damaged when peeling off the protective sheet for workpiece processing, and prevents adhesive from adhering to the workpiece.

In this embodiment, the energy ray-curable adhesive is preferably composed of an adhesive composition containing an acrylic adhesive. The acrylic adhesive contains an acrylic polymer.

The acrylic polymer may be any known acrylic polymer, but in this embodiment, an acrylic polymer containing a functional group is preferred. The acrylic polymer containing functional groups can be a monopolymer formed from one acrylic monomer, or a copolymer formed from a plurality of acrylic monomers, or one or a plurality of acrylic monomers. Copolymer with monomers other than acrylic monomers.

In this embodiment, the functional group-containing acrylic polymer is preferably an acrylic copolymer obtained by copolymerizing an alkyl (meth)acrylate and a functional group-containing monomer.

Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and (meth)acrylate. n-butyl acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethyl (meth)acrylate Hexyl ester, isooctyl (meth)acrylate, n-octyl (meth)acrylate, etc.

The functional group-containing monomer is a reactive functional group-containing monomer. The reactive functional group is a functional group that can react with other compounds such as a cross-linking agent, which will be described later. Examples of the functional group in the functional group-containing monomer include a hydroxyl group, a carboxyl group, and an epoxy group, with a hydroxyl group being preferred.

Examples of the hydroxyl-containing monomer include: hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. , (meth)hydroxyalkyl acrylates such as 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc.; vinyl alcohol, propenol, etc. Non-(meth)acrylic unsaturated alcohol (unsaturated alcohol without (meth)acrylyl group).

The acrylic polymer is an energy-beam-curable polymer having an energy-ray-curable group obtained by reacting (for example, an addition reaction) an energy-beam-curable material having an energy-ray-curable group with a functional group of an acrylic polymer. Resistant acrylic polymers are preferred. The energy ray curable substance having an energy ray curable group is preferably a compound having one or more compounds selected from an isocyanate group, an epoxy group and a carboxyl group in addition to the energy ray curable group. The compound having an isocyanate group Compounds are preferred. The isocyanate group can be added to the hydroxyl group of the acrylic polymer containing a functional group.

Examples of the compound having an isocyanate group include 2-methacryloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methacrylyl isocyanate, and isocyanate. Propyl ester, 1,1-(bisacrylyloxymethyl)ethyl isocyanate; acryl monoisocyanate compound obtained by the reaction of a diisocyanate compound or a polyisocyanate compound and hydroxyethyl (meth)acrylate; by An acryl monoisocyanate compound obtained by the reaction of a diisocyanate compound or a polyisocyanate compound with a polyol compound, hydroxyethyl (meth)acrylate, etc.

The adhesive composition preferably contains an energy ray curable compound in addition to an acrylic polymer. As the energy ray curable compound, a monomer or oligomer that has an unsaturated group in the molecule and can be polymerized and cured by energy ray irradiation is preferred.

Examples of such energy ray curable compounds include: trimethylolpropane tri(meth)acrylate, neopentylerythritol (meth)acrylate, neopentylerythritol tetra(meth)acrylate, Polyvalent (meth)acrylic acid such as dipenterythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, etc. Ester monomers, urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, epoxy (meth)acrylate, etc. oligomers.

Among these, urethane (meth)acrylate oligomer is preferable from the viewpoint that the molecular weight is relatively high and the shear storage modulus of the adhesive layer is not easily reduced.

The molecular weight (weight average molecular weight in the case of an oligomer) of the energy ray curable compound is preferably 100 to 12,000, more preferably 200 to 10,000, more preferably 400 to 8,000, and particularly preferably 600 to 6,000.

The content of the energy ray curable compound in the adhesive composition is preferably 5 to 100 parts by mass, more preferably 10 to 70 parts by mass, and 15 to 40 parts by mass relative to 100 parts by mass of the acrylic polymer. Better.

The adhesive composition preferably further contains a cross-linking agent. The crosslinking agent reacts with a functional group to crosslink the resins contained in the functional group-containing acrylic polymer, for example.

Examples of the cross-linking agent include isocyanate-based cross-linking agents (cross-linking agents having an isocyanate group) such as toluene diisocyanate, hexamethylene diisocyanate, and the above adducts; ethylene glycol glycidyl Epoxy cross-linking agents such as ether (cross-linking agents having a glycidyl group); aziridine cross-linking agents such as hexa[1-(2-methyl)-aziridinyl]triazine triphosphite (cross-linking agent with aziridine group); metal chelate cross-linking agent such as aluminum chelate (cross-linking agent with metal chelate structure); isocyanurate cross-linking agent (with isocyanurate Urea acid skeleton cross-linking agent), etc.

From the viewpoint of increasing the cohesive force of the adhesive to increase the adhesive force of the adhesive layer, and from the viewpoint of ease of acquisition, an isocyanate-based crosslinking agent is preferred.

The adhesive composition may further contain a photopolymerization initiator. Since the adhesive composition contains a photopolymerization initiator, the curing reaction can be sufficiently advanced even when relatively low-energy energy rays such as ultraviolet rays are irradiated.

Examples of the photopolymerization initiator include photoinitiators such as benzoin compounds, acetophenone compounds, phosphine oxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds. Photosensitizers such as amines and quinones, etc. Specifically, examples include α-hydroxycyclohexylphenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl sulfide, benzyl dimethyl ketal, tetramethylthiuram monosulfide, Azobisisobutyronitrile, bibenzyl, biacetyl, β-chloroanthraquinone, 2,4,6-trimethylbenzyldiphenylphosphine oxide, etc.

(4. Method of manufacturing protective sheet for workpiece processing) The method of manufacturing the workpiece processing protective sheet according to this embodiment may be a known method.

First, a base material including a support material and a soft material is produced. For example, a base material is produced by laminating a resin film constituting a support material and a resin film constituting a soft material.

An example of a method for laminating resin films is a dry lamination method, in which one resin film (for example, a resin film constituting a support material) is bonded to another resin film (for example, a support material) via an easily adhesive layer formed on one main surface thereof For example, a resin film constituting a soft material) is laminated.

In the dry lamination method, a resin film having an easily adhesive layer may be used, or a resin film in which an easily adhesive layer forming composition is applied to a surface that has been subjected to an adhesive treatment such as corona treatment to form an easily adhesive layer may be used. In addition, another layer may be formed between the resin film and the easily bonded layer. As such another layer, a colored layer for improving the visibility of the workpiece processing protective sheet is exemplified.

In addition, the following method is exemplified: using a T-die film forming machine or the like to melt/knead the resin constituting the soft material, and moving the support material at a constant speed while extruding and laminating the molten resin onto one surface of the support material. side. Furthermore, an example is a method in which a soft material is directly laminated on a support material by heat sealing or the like.

In addition, when manufacturing has a support material, a soft material and a cushioning material, the cushioning material and the soft material may be formed on the support material in the same manner.

Next, as a composition for forming the adhesive layer, for example, an adhesive composition constituting the adhesive layer or a composition in which the adhesive composition is diluted with a solvent is prepared (these two compositions are called "coating"). agent"). The prepared coating agent is applied to the release surface of the release film and dried as necessary to form an adhesive layer on the release film. Thereafter, the soft material side surface of the base material and the exposed surface of the adhesive layer are bonded together to obtain a workpiece processing protective sheet with an adhesive layer formed on the base material. Alternatively, the prepared coating agent may be directly applied to the soft material side surface of the base material to form an adhesive layer.

(5. Method for manufacturing individual pieces of workpiece) As described above, the protective sheet for workpiece processing related to the present invention is suitable for use in the method of individualizing workpieces using LDBG.

As a non-limiting use example of the protective sheet for workpiece processing, a method for manufacturing individual workpiece pieces (for example, wafers) using LDBG will be specifically described below.

Specifically, the manufacturing method of individual pieces of workpieces includes at least the following steps 1 to 4. Step 1: Attach the above protective sheet for workpiece processing to the front of the workpiece; Step 2: The step of forming a modified area inside the workpiece from the front or back of the workpiece; Step 3: The step of grinding the workpiece with a protective sheet for workpiece processing attached to the front and having a modified area formed on the back side, and using the modified area as a starting point to form individual workpieces into individual pieces; Step 4: A step of peeling off the workpiece processing protective sheet from the workpieces that have been individually divided into pieces (that is, a plurality of individual pieces of workpieces).

Hereinafter, each step of the method for manufacturing the individual workpiece flakes will be described in detail. In the description, a wafer is used as a specific example of a workpiece, and a wafer is used as a specific example of an individual piece of workpiece.

(step 1) In step 1, the adhesive layer of the workpiece processing protective sheet related to this embodiment is attached to the front surface of the wafer. This step can be performed after step 2 described below, but from the viewpoint of reducing the risk of accidentally individualizing the wafer when attaching the protective sheet for workpiece processing, it is better to perform step 1 before step 2.

The thickness of the wafer used in this manufacturing method before grinding is not particularly limited, but is usually about 500 to 1000 μm.

In addition, a circuit is formed on the front surface of the wafer. The circuit can be formed on the front surface of the wafer by various methods including etching, lift-off, and other commonly used methods in the past.

The formed loop can also be exposed, or a loop protection layer can be formed to protect the loop. The circuit protective layer is usually formed by applying a composition constituting the circuit protective layer and thermally hardening the composition. In addition, convex electrodes such as bumps and pillars can also be formed in the circuit.

(Step 2) In step 2, a modified region is formed inside the wafer from the front or back side of the wafer.

The modified area formed in this step is the embrittled portion of the wafer. Through the modified region, cracks are easily generated by the shear force and pressure applied to the wafer. Such cracks become the starting point for dividing the wafer. That is, in step 2, the modified region is formed along the dividing line when the wafer is divided into individual wafers in step 3 described below.

The modified area is formed by irradiating the laser focused on the inside of the wafer. Therefore, the modified region is formed inside the semiconductor wafer. Laser irradiation can be performed from the front side or the back side of the wafer. In addition, when step 2 is performed after step 1 and laser irradiation is performed from the front surface of the wafer, the wafer is irradiated with laser through a protective sheet for workpiece processing.

The wafer with the protective sheet for workpiece processing attached and the modified area formed thereon is placed on the suction table and held by the suction table. At this time, the front side of the wafer is arranged on the suction table side via the workpiece processing protective sheet and is suctioned.

(Step 3) After steps 1 and 2, the back surface of the wafer on the adsorption table is ground to separate the wafers into a plurality of wafers.

Here, backside grinding is performed until the grinding surface (wafer backside) reaches the modified area, but the grinding surface may not reach the modified area exactly. That is, it is sufficient to grind the wafer to a position close to the modified region, and use the modified region as a starting point to divide the wafer into individual wafers.

In addition, after backside grinding using a grinding wheel, stress relief such as dry polishing can also be performed.

The shape of the individually sliced wafers may be square or rectangular or other elongated shapes. In addition, the thickness of the individual wafers is not particularly limited, but is preferably about 5 to 100 μm, and more preferably 10 to 45 μm. Using LDBG, it is easy to set the thickness of individual wafers to 50 μm or less, preferably 10 to 45 μm. In addition, the size of the individual wafers is not particularly limited. For example, the chip area is preferably less than 600mm ² , preferably less than 400mm ² , and more preferably less than 120mm ² .

By using the protective sheet for workpiece processing related to this embodiment, the occurrence of cracks in the wafer after backside grinding (step 3) is reduced.

(Step 4) Next, the workpiece processing protective sheet is peeled off from the individually sliced wafers (that is, the wafer group). This step is performed, for example, by the following method.

First, when the adhesive layer of the workpiece processing protective sheet is formed of an energy ray-curable adhesive, energy rays are irradiated to harden the adhesive layer. For example, the illumination intensity of the energy ray is preferably 120~280 mW/cm ² and the light intensity of the energy ray is 100~1000 mJ/cm ² . As an energy ray, ultraviolet light is the best. Next, the pick-up tape is attached to the back side of the wafer group, and the position and direction are aligned so that the pick-up can be performed. At this time, the ring frame located on the outer peripheral side of the wafer is also attached to the pickup belt, and the outer peripheral edge of the pickup belt is fixed to the ring frame. In the pick-up belt, the wafer and the ring frame can be bonded at the same time, or they can be bonded according to different timings. Next, the plurality of wafers held on the pickup tape are peeled off from the workpiece processing protective sheet.

Subsequently, a plurality of semiconductor wafers located on the pickup belt are picked up. Next, the wafer is fixed on a device substrate or the like to manufacture the device. For example, when the wafer is a semiconductor, the wafer is fixed on a substrate for a semiconductor device or the like to manufacture the semiconductor device.

In addition, the pick-up tape is not particularly limited, and may be, for example, an adhesive tape including a base material and an adhesive layer provided on at least one surface of the base material.

The embodiments of the present invention have been described above. The present invention should not be limited in any way by the above-mentioned embodiments, and may be modified in various ways within the scope of the present invention. [Example]

Hereinafter, the invention will be described in further detail using examples, but the invention is not limited by these examples.

The measurement method and evaluation method in this example are as follows.

(The product of the tensile elastic coefficient of the base material and the thickness of the base material) The base materials produced in Examples and Comparative Examples were cut into a size of 130 mm in length and 15 mm in width to obtain a measurement sample for measuring the tensile elastic coefficient. At this time, the long side (130 mm) of the measurement sample was set in a direction parallel to the flow direction during base material production, and the short side (15 mm) of the measurement sample was set in a direction perpendicular to the flow direction. With a tensile testing machine (product name "Autograph (registered trademark) AG-IS 500N", manufactured by SHIMADZU Co., Ltd.), the distance between the initial clamping jaws (that is, the length of the specimen for measurement) is measured at a speed of 200 mm/min. ) is 100 mm, the obtained measurement sample is stretched in the length direction of the measurement sample in an environment of 23°C, and the value of the tensile elastic coefficient (Young's coefficient) at 23°C is calculated from the measurement results. Let this value be the tensile elastic coefficient at 23°C (unit: MPa). From the obtained value of the tensile elastic coefficient, the product of the tensile elastic coefficient of the base material and the thickness of the base material was calculated. The results are shown in Table 1.

(Tensile elastic coefficient of soft materials) The soft materials produced in Examples and Comparative Examples were cut into a size of 130 mm in length and 15 mm in width to obtain a measurement sample for measuring the tensile elastic coefficient. Using the obtained measurement sample, the tensile elastic coefficient (Young's coefficient) (unit: MPa) of the soft material at 23° C. was calculated by the same measurement method as the method for measuring the tensile elastic coefficient of the base material. The results are shown in Table 1.

(Stress Relaxation Rate of Soft Material) The soft material produced in the Examples and Comparative Examples was cut into a size of 130 mm in length and 15 mm in width to obtain a measurement sample for measuring the tensile elastic coefficient. By using a tensile testing machine (product name "Autograph (registered trademark) AG-IS 500N", manufactured by SHIMADZU Co., Ltd.), at a speed of 200 mm/min and an initial distance between jaws of 100 mm, in an environment of 23°C, The obtained measurement sample is stretched in the length direction of the measurement sample, and the stretching is stopped when the measurement sample has been stretched by 10% (that is, the distance between the jaws is 110 mm), and the stress A (N/m) at the stop is measured. ² ) and the stress B (N/m ² ) after stopping the stretching of the measurement sample for 1 minute. From the measured values of stress A and stress B, the stress relaxation rate is calculated by the following formula. Stress relaxation rate={(AB)/A}×100(%)

(crack incidence rate) Using a tape laminator for back grinding (manufactured by LINTEC, device name "RAD-3510F/12"), the protective sheet for workpiece processing produced in the Examples and Comparative Examples was attached to a workpiece having a diameter of 12 inches and a thickness of 780 μm. Silicon wafer. A laser cutting machine (manufactured by DISCO, device name "DFL7361") is used to form a grid-shaped modified area on the wafer. In addition, the grid size is set to 10mm×10mm.

Next, a back grinding device (manufactured by DISCO, device name "DGP8761") is used to grind (including dry polishing) the opposite surface of the wafer in which the modified area has been formed to the surface on which the protective sheet for workpiece processing is attached, until The thickness of the wafer (wafer group) was 18 μm, and the wafers were individually sliced into a plurality of wafers. After the grinding step, energy rays (ultraviolet) are irradiated, and dicing tape (ADwill D-175D* manufactured by LINTEC) is attached to the opposite side of the protective sheet for workpiece processing, and then the protective sheet for workpiece processing is peeled off. Thereafter, the individually sliced wafers were observed using DFL7361, and wafers in which at least one crack with a length of 10 μm or more had occurred were regarded as cracked wafers, and the crack occurrence rate was calculated based on the following equation. At this time, wafers whose circumferential portion size of the circular wafer group does not satisfy 10 mm×10 mm (for example, triangular wafers) are eliminated from the observation object. The case where the crack occurrence rate is 5.0% or less is evaluated as "good", and the case other than this is evaluated as "poor". Crack occurrence rate (%) = (number of wafers with cracks/number of total wafers) × 100

(Example 1) (1)Substrate First, as a support material, a PET film (thickness: 50 μm, Young's coefficient at 23° C.: 4300 MPa) was prepared.

On one side of the prepared PET film, an easy-to-adhere layer with a thickness of 2.5 μm is provided, and a colorless and transparent low-temperature film with a breaking energy of 48 MJ/m ³ , a density of 919 kg/m ³ and a thickness of 25 μm is attached using a dry lamination method. Density polyethylene (LDPE1) is used as a soft material. Next, an easy-adhesion layer with a thickness of 2.5 μm is placed on the other side of the PET film, and a colorless and transparent layer with a breaking energy of 48 MJ/m ³ , a density of 919 kg/m ³ , and a thickness of 25 μm is adhered by the dry lamination method. Low-density polyethylene (LDPE1) was used as a cushioning material, and a base material obtained by laminating a support material, a soft material, and a cushioning material was obtained. The thickness of the substrate is 105 μm.

In addition, the breaking energy of the above-mentioned soft materials and cushioning materials and the numerical values of the breaking energy of the subsequent soft materials and cushioning materials are determined by using the same procedure as the measurement of the "tensile elastic coefficient of the soft material". The value calculated from the strain and stress when stretching soft materials and buffer materials and then continuing to stretch until they break.

(2) Adhesive layer (Preparation of composition for adhesive) To an acrylic polymer obtained by copolymerizing 65 parts by mass of n-butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA), and 15 parts by mass of 2-hydroxyethyl acrylate (2HEA), 80 equivalents of hydroxyl groups out of the total hydroxyl groups (100 equivalents) of the acrylic polymer are reacted with 2-methacryloyloxyethyl isocyanate (MOI) to obtain an energy ray curable acrylic copolymer. Things (MW: 500,000).

To 100 parts by mass of this energy ray-curable acrylic copolymer, 10 parts by mass of a polyfunctional urethane acrylate ultraviolet curable compound (manufactured by Mitsubishi Chemical Corporation, product name "UT-4332"), and an isocyanate-based copolymer were prepared. 0.38 parts by mass of a coupling agent (manufactured by TOSOH Co., product name "CORONATE L") and 1 part by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator were used. Methyl ethyl ketone was diluted to prepare a coating agent of a composition for an adhesive layer having a solid content concentration of 34% by mass.

(Manufacturing of protective sheets for workpiece processing) The coating agent of the adhesive layer composition obtained above is applied to the silicone release-treated surface of a release sheet (manufactured by LINTEC, trade name "SP-PET381031"), and heated and dried to form a thickness on the release sheet. It is a 40μm adhesive layer.

Thereafter, the soft material of the base material and the adhesive layer are bonded together to produce a protective sheet for workpiece processing. That is, the protective sheet for workpiece processing shown in Figure 1B is manufactured. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 2) A colorless and transparent low-density polyethylene (LDPE2) with a breaking energy of 61 MJ/m ³ , a density of 937 kg/m ³ , and a thickness of 25 μm was formed as a soft material and buffer material by using the same method as Example 1 The protective sheet for workpiece processing is manufactured using the same method. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 3) A colorless and transparent low-density polyethylene (LDPE3) with a breaking energy of 30 MJ/m ³ , a density of 940 kg/m ³ , and a thickness of 25 μm was formed as a soft material and buffer material by using the same method as Example 1 The protective sheet for workpiece processing is manufactured using the same method. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 4) As a support material, an easy-adhesion layer with a thickness of 2.5 μm was provided on one side of a PET film (thickness: 50 μm, Young's coefficient at 23°C: 4300 MPa) to form a breaking energy of 48 MJ/m ³ , A colorless and transparent low-density polyethylene (LDPE1) with a density of 919 kg/m ³ and a thickness of 25 μm was used as a soft material and did not form a buffer material. In addition, a protective sheet for workpiece processing was produced in the same manner as in Example 1. That is, the protective sheet for workpiece processing shown in Figure 1A is manufactured. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 5) A colorless and transparent low-density polyethylene (LDPE3) with a breaking energy of 30 MJ/m ³ , a density of 940 kg/m ³ , and a thickness of 25 μm was produced as a soft material by the same method as in Example 4, except that Protective sheet for workpiece processing. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 6) A protective sheet for workpiece processing was produced in the same manner as in Example 5 except that the thickness of the adhesive layer was 60 μm. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 7) As a support material, a 40 μm thick PET film (Young's coefficient at 23° C.: 4300 MPa) was used, and the thickness of the adhesive layer was set to other than 30 μm, and a protective sheet for workpiece processing was produced in the same manner as in Example 1. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 8) As the support material, a 40 μm thick PET film (Young's coefficient at 23° C.: 4300 MPa) was used, and the thickness of the adhesive layer was set to other than 30 μm, and a workpiece processing protective sheet was produced in the same manner as in Example 2. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 9) A protective sheet for workpiece processing was produced in the same manner as in Example 4 except that the thickness of the soft material was 50 μm. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Example 10) A protective sheet for workpiece processing was produced in the same manner as in Example 3, except that a 25 μm-thick PET film (Young's coefficient at 23° C.: 4300 MPa) was used as a support material. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Comparative Example 1) High-density polyethylene (HDPE1) with a breaking energy of 19 MJ/m ³ , a density of 945 kg/m ³ , and a thickness of 25 μm was produced by the same method as Example 1, except that it was used as a soft material and a buffer material. Protective sheet for workpiece processing. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Comparative example 2) A protective sheet for workpiece processing was produced in the same manner as in Example 4, except that high-density polyethylene (HDPE1) with a thickness of 25 μm was formed as a soft material. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

(Comparative example 3) A protective sheet for workpiece processing was produced in the same manner as in Example 1, except that a 25 μm-thick PET film (Young's coefficient at 23° C.: 4300 MPa) was used as a support material. The composition and thickness of the base material and the thickness of the adhesive layer are shown in Table 1.

The above-described measurement and evaluation were performed on the obtained samples (Examples 1 to 10 and Comparative Examples 1 to 3). The results are shown in Table 1.

[Table 1] Protective sheet for semiconductor processing physical properties Evaluation results base material Adhesive buffer material Support material Soft material thickness Tensile elastic coefficient of soft materials The product of the tensile elastic coefficient of the substrate and the thickness of the substrate Stress relaxation rate of soft materials [%] Crack incidence rate [%] Material thickness Material thickness Material thickness mm mm mm mm MPa N/m Example 1 LDPE1 25 PET 55 LDPE1 25 40 140 210000 15 1.8 Example 2 LDPE2 25 PET 55 LDPE2 25 40 330 225750 27 2.2 Example 3 LDPE3 25 PET 55 LDPE3 25 40 430 231000 36 2.7 Example 4 - - PET 52.5 LDPE1 25 40 140 209250 15 3.8 Example 5 - - PET 52.5 LDPE3 25 40 430 217775 36 4.3 Example 6 - - PET 52.5 LDPE3 25 60 430 217775 36 4.8 Example 7 LDPE1 25 PET 45 LDPE1 25 30 140 161500 15 3.1 Example 8 LDPE2 25 PET 45 LDPE2 25 30 330 171000 27 1.5 Example 9 - - PET 52.5 LDPE1 50 40 140 210125 15 2.6 Example 10 LDPE3 25 PET 30 LDPE3 25 40 430 120000 36 4.1 Comparative example 1 HDPE1 25 PET 55 HDPE1 25 40 800 241500 43 6.5 Comparative example 2 - - PET 52.5 HDPE1 25 40 800 217000 43 7.3 Comparative example 3 LDPE1 25 PET 30 LDPE1 25 40 140 96000 15 6.2

According to Table 1, it can be confirmed that when the product of the tensile elastic coefficient of the base material and the thickness of the base material and the tensile elastic coefficient of the soft material are within the above range, even if the wafer is individually sliced by LDBG, the crack occurrence rate is Still low.

1: Protective sheet for workpiece processing 10:Substrate 12: Support material 12a,12b,20a: Main side 14:Soft material 16:Buffer material 20: Adhesive layer 100:Artifact 100a: Front 100b: back

Fig. 1A is a schematic cross-sectional view showing an example of a protective sheet for workpiece processing according to this embodiment. Fig. 1B is a schematic cross-sectional view showing another example of the protective sheet for workpiece processing according to this embodiment. Figure 2 is a schematic cross-sectional view showing how the protective sheet for workpiece processing according to this embodiment is attached to the front side of the workpiece.

1: Protective sheet for workpiece processing

10:Substrate

12: Support material

12a,20a: Main side

14:Soft material

20: Adhesive layer

Claims (9)

A protective sheet for workpiece processing, which has a base material and an adhesive layer arranged on the base material, wherein The aforementioned base material has a support material and a soft material, and the aforementioned soft material and the aforementioned adhesive layer are sequentially arranged on one main surface of the aforementioned support material; The product of the tensile elastic coefficient of the aforementioned base material and the thickness of the aforementioned base material is 100,000 N/m or more; The tensile elastic coefficient of the soft material is 450 MPa or less. The protective sheet for workpiece processing according to claim 1, wherein the base material further has a buffer material, and the buffer material is arranged on the other main surface of the support material. For example, the protective sheet for workpiece processing according to claim 1 or 2, wherein the thickness of the adhesive layer is less than 50 μm. The protective sheet for workpiece processing according to claim 1 or 2, wherein the thickness of the support material is 20 μm or more and 80 μm or less. The protective sheet for workpiece processing according to claim 1 or 2, wherein the thickness of the soft material is 10 μm or more and 75 μm or less. The protective sheet for workpiece processing according to Claim 2, wherein the thickness of the buffer material is 10 μm or more and 75 μm or less. The protective sheet for workpiece processing according to claim 1 or 2, wherein the stress relaxation rate of the soft material is 50% or less. A protective sheet for workpiece processing according to claim 1 or 2, which is attached to the front side of the workpiece in the step of grinding the backside of the workpiece with the modified region formed therein into individual workpiece pieces. And use. A method for manufacturing individual pieces of workpieces, which has the following steps: Attach the protective sheet for workpiece processing as described in any one of requirements 1 to 8 on the front side of the workpiece; Form a modified area inside the workpiece from the front or back of the workpiece; The protective sheet for workpiece processing is attached to the front side, and the workpiece with the modified area formed by grinding from the back side is individually sliced into a plurality of individual workpiece pieces starting from the modified area; and The protective sheet for workpiece processing is peeled off from the workpiece that has been divided into individual pieces.

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