Wafer processing tape and wafer processing method

Abstract

The objective is to provide a wafer processing tape that can sufficiently reduce adhesive strength when the adhesive layer is irradiated with ultraviolet light after a heating process, and that can be used transversely in semiconductor processing, and a wafer processing method that enables the integration of multiple semiconductor processing processes by using this tape. [Solution] The system comprises a base layer and an adhesive layer disposed on at least one side of the base layer, A tape for wafer processing in which the 5% weight loss temperature of the adhesive layer is 270°C or higher.

Description

Technical Field

[0001] The present invention relates to a tape for wafer processing and a wafer processing method.

Background Art

[0002] When processing a semiconductor wafer, an adhesive sheet is attached to protect it from damage. For example, in the back grinding process when processing a semiconductor wafer, an adhesive sheet is attached to protect the pattern surface of the semiconductor wafer. In addition, in semiconductor processing, various tapes such as back grind tapes, heat-resistant tapes, conductive tapes, dicing tapes, and pickup tapes are used in each process.

[0003] As an example, for the purpose of enhancing the adhesion of a substrate to a stage in a semiconductor wafer processing step, a substrate used for an adhesive sheet for processing a semiconductor wafer having a heat shrinkage rate of 0% or more in both MD and TD after heating at 130°C for 10 minutes for promoting the adhesion of the substrate to the stage in the semiconductor wafer processing step is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In semiconductor processing, different tapes are used in each process because the characteristics required for the wafer processing tape are different in each process. However, since the wafer processing tape needs to be replaced after each process, there is a problem that the number of man-hours in the semiconductor processing step increases and the process becomes complicated.

[0006] The present invention has been made in view of the above problems, and aims to provide a wafer processing tape that can sufficiently reduce adhesive strength when the adhesive layer is irradiated with ultraviolet light after a heating process, and that can be used transversely in semiconductor processing, and a wafer processing method that can integrate multiple semiconductor processing processes by using the tape. [Means for solving the problem]

[0007] In other words, the present invention is as follows: [1] A base layer and The base layer has an adhesive layer disposed on at least one side, The temperature at which the adhesive layer loses 5% of its weight is 270°C or higher. Tape for wafer processing. [2] The weight loss rate of the adhesive layer at 300°C is 88% or more. [1] Wafer processing tape as described in [1]. [3] The adhesive force N1 of the adhesive layer to the silicon wafer after heating at 250°C for 5 minutes is 0.5 to 7.0 N / 25 mm at 25°C. The wafer processing tape described in [1] or [2]. [4] After heating at 250°C for 5 minutes and then UV irradiation, the adhesive strength N2 of the adhesive layer to the silicon wafer is 0.01 to 1.0 N / 25 mm at 25°C. A wafer processing tape as described in any one of items [1] to [3]. [5] The adhesive layer further comprises an acrylic resin having a polymerizable double bond with a hydroxyl group or a carboxyl group. A wafer processing tape as described in any one of items [1] to [4]. [6] The adhesive layer further comprises an epoxy crosslinking agent. A wafer processing tape as described in any one of items [1] to [5]. [7] The adhesive layer contains a base polymer and a crosslinking agent, the content of the crosslinking agent is 0.5 to 6.0 parts by mass with respect to 100 parts by mass of the base polymer, The wafer processing tape according to [6]. [8] The base material layer contains a polyamide resin, The wafer processing tape according to any one of [1] to [7]. [9] The base material layer has no yield point, The wafer processing tape according to any one of [1] to [8].

[10] The ultraviolet transmittance of the base material layer at 365 nm is 70% or more, The wafer processing tape according to any one of [1] to [9].

[11] The wafer processing tape according to any one of [1] to

[10] is attached to a wafer, and has a processing step of performing wafer processing. Wafer processing method.

Advantages of the Invention

[0008] According to the present invention, when ultraviolet irradiation is performed on the adhesive layer after the heating step, the adhesive force can be sufficiently reduced, and a wafer processing tape that can be used transversely in semiconductor processing, and a wafer processing method capable of integrating a plurality of semiconductor processing steps by using the tape can be provided.

Brief Description of the Drawings

[0009] [Figure 1] It is a schematic cross-sectional view showing the wafer processing tape of the present embodiment. [Figure 2] It is a flowchart showing the wafer processing method of the present embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to this, and various modifications are possible without departing from the gist thereof. In the drawings, the same reference numerals are assigned to the same elements, and redundant descriptions are omitted. Also, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0011] 1. Wafer Processing Tape The wafer processing tape of the present embodiment has a base material layer and an adhesive layer disposed on at least one surface side of the base material layer, and the 5% weight loss temperature of the adhesive layer is 270°C or higher.

[0012] FIG. 1 shows a schematic cross-sectional view of the wafer processing tape of the present embodiment. As shown in FIG. 1, the wafer processing tape 10 of the present embodiment has a base material layer 11 and an adhesive layer 12, and may have other layers as necessary. By the surface 12a (exposed surface) of the adhesive layer 12 being in close contact with the element formation surface 20a on which the semiconductor element of the wafer 20 is formed, the semiconductor element on the element formation surface 20a of the wafer 20 can be protected. In the present embodiment, in the wafer processing tape and each of its layers, the surface on the side in contact with the wafer is referred to as the front surface, and the opposite surface is referred to as the back surface.

[0013] Figure 2 shows a flowchart illustrating one embodiment of the wafer processing method of this embodiment in a schematic cross-sectional view. As shown in Figure 2, the wafer processing method may include a bonding step S1 in which the wafer processing tape 10 is bonded to the element formation surface 20a of the wafer 20; a back grinding step S2 in which the non-element formation surface 20b of the wafer 20 bonded to the wafer processing tape 10 is polished with a grinder 40; a metal layer formation step S3 in which a metal layer 21 is formed on the non-element formation surface 20b opposite to the surface to which the wafer processing tape 10 is bonded; a dicing step S4 in which the wafer 20 bonded to the wafer processing tape 10 is diced to produce a chip 30; a processing step S5 in which surface treatment is applied to the back surface of the chip 30 by etching or sputtering or reflow treatment; and a peeling step S6 in which the wafer processing tape is peeled off.

[0014] Note that Figure 2 is an example of a wafer processing method, and it is not necessary to perform all of steps S2 to S5 in the wafer processing method, nor is the order of the steps limited to those specified in Figure 2. Therefore, for example, the metal layer formation step S3 may be omitted, or the processing step S5 may be omitted, or the processing step S5 may be performed before the dicing step S4.

[0015] Incidentally, it has been found that when attempting to reduce the adhesive strength of the adhesive layer by irradiating it with ultraviolet light after heating processes such as the metal layer formation process S3 and the processing process S5, and then proceeding to the peeling process S6, the adhesive strength may not decrease as much as expected. The reason for this is not particularly limited, but it is thought that exposure to high temperatures in the heating processes causes a portion of the base polymer constituting the adhesive layer, or a portion of the three-dimensional crosslinked structure of the base polymer and the crosslinking agent, to decompose and become lower molecular weight. In other words, in the peeling process S6, the adhesive strength is reduced by crosslinking the polymerizable groups with ultraviolet light, but it is thought that because a portion of the base polymer or a portion of the three-dimensional crosslinked structure has decomposed in the heating processes, the improvement in crosslinking density cannot be achieved as much as expected, and therefore the reduction in adhesive strength cannot be expected.

[0016] In contrast, the wafer processing tape 10 of this embodiment specifies that the 5% weight loss temperature of the adhesive layer is 270°C or higher. By using an adhesive layer with high heat resistance in this way, it is possible to suppress the thermal decomposition of a portion of the base polymer or a portion of the three-dimensional crosslinking structure within the adhesive layer. As a result, when ultraviolet irradiation is performed in the peeling process S6, the crosslinking density is further improved, and the adhesive strength can be reduced.

[0017] As described above, the wafer processing tape of this embodiment can sufficiently reduce its adhesive strength when the adhesive layer is irradiated with ultraviolet light after the heating process. Therefore, it is not necessary to replace the wafer processing tape with one appropriate for each wafer processing step, and it can be used across the wafer in a wafer processing method as shown in Figure 2. The composition of each layer will be described in detail below.

[0018] 1.1. Base material layer The substrate layer 11 conforms to the irregularities of the wafer 20, protecting it from damage during the wafer processing process, and also contributes to improved adhesion by preventing gaps from forming between the adhesive layer and the element formation surface 20a.

[0019] The base layer preferably contains a resin, and the resin is not particularly limited, but examples include polyamide resins, ionomer resins, polyolefin resins, vinyl chloride resins, polyester resins, polystyrene resins, phenolic resins, and acrylic resins. These resins may be used individually or in combination of two or more. More specifically, the resins may be mixtures, copolymers, or laminates of one resin with another.

[0020] Among these, polyamide resins, ionomer resins, and polyolefin resins are preferred, with polyamide resins being more preferred. Using such resins tends to improve the wafer's conformability to irregularities, heat resistance, and ultraviolet transmittance.

[0021] The polyamide resin is not particularly limited, but examples include aliphatic polyamides such as polyamide 6 and polyamide 66; semi-aromatic polyamides such as polyamide 6T, polyamide 9T, and polyamide 10T; and fully aromatic polyamides obtained from aromatic dicarboxylic acids and aromatic diamines. Note that aliphatic polyamides may also have alicyclic groups in addition to aliphatic groups.

[0022] The ionomer resin is not particularly limited as long as it is a polymer in which metal ions are intermolecularly bonded, but examples include polyolefin-based ionomers, (meth)acrylic-based ionomers, polystyrene-based ionomers, and polyester-based ionomers. The metal ions that constitute the salt of the ionomer resin are not particularly limited, but examples include monovalent metal ions such as sodium ions and lithium ions; divalent metal ions such as zinc ions, calcium ions, and magnesium ions; and trivalent metal ions such as aluminum ions.

[0023] The polyolefin resin is not particularly limited, but examples include polyethylene, polypropylene, and copolymers thereof.

[0024] The resin content is preferably 80-100% by mass, 85-100% by mass, or 90-100% by mass, relative to the total amount of the substrate layer.

[0025] The base layer may contain additives other than resin, as needed. While not particularly limited, examples of additives include plasticizers, heat stabilizers, colorants, organic lubricants, inorganic lubricants, surfactants, processing aids, and antistatic agents. Additives may be used individually or in combination of two or more.

[0026] It is preferable that the base layer does not have a yield point. In this embodiment, "yield point" refers to the first point in the stress-strain curve where strain increases without an increase in stress. "Having no yield point" means that there is no point in the stress-strain curve where strain increases without an increase in stress. The stress-strain curve can be measured in accordance with JIS K 7161, and the yield point can be identified from the stress-strain curve measured in this manner.

[0027] Resins without a yield point are not particularly limited, but examples include polystyrene resin, acrylic resin, phenolic resin, and polyamide resin.

[0028] The ultraviolet transmittance of the substrate layer at 365 nm is preferably 70% or more, 80-99.5%, and 85-99%. A ultraviolet transmittance of 70% or more allows the adhesive layer 12 to be cured by irradiating it with ultraviolet light from the back surface 11b of the substrate layer, which tends to improve the peelability of the wafer 20 from the adhesive layer 12 during the peeling process.

[0029] The ultraviolet transmittance at 365 nm may also be measured by using a UV-Vis spectrophotometer to measure the light transmittance of the substrate in the wavelength range of 300 nm to 800 nm, and then reading the light transmittance at 365 nm from the obtained measurement results.

[0030] The thickness of the substrate layer is preferably 10 to 500 μm, 15 to 250 μm, or 25 to 100 μm. When the thickness of the substrate layer is within the above range, the ability to follow the irregularities of the wafer is further improved, and gaps such as voids are less likely to enter between the wafer processing tape and the element formation surface, which tends to improve adhesion.

[0031] 1.2. Adhesive layer The adhesive layer 12 is a layer laminated on the surface 11a side of the substrate layer 11. During the semiconductor processing process, the adhesive layer 12 adheres closely to the wafer 20, protecting the element formation surface 20a, and can be peeled off after semiconductor processing without leaving any adhesive residue.

[0032] The 5% weight loss temperature of the adhesive layer is 270°C or higher, preferably 275-350°C, 280-325°C, or 285-300°C. By having a 5% weight loss temperature of 270°C or higher, even after going through processes requiring heating, a portion of the base polymer and a portion of the three-dimensional crosslinking structure do not decompose due to thermal action. In the peeling process, UV irradiation further improves the crosslinking density, which can reduce the adhesive strength.

[0033] Furthermore, the weight loss rate of the adhesive layer at 300°C is preferably 88% or more, 89% or more, and 90% or more. The upper limit of the weight loss rate at 300°C is not particularly limited, but is 100%. By having a weight loss rate of 88% or more at 300°C for the adhesive layer, even after undergoing heating processes, a portion of the base polymer and a portion of the three-dimensional crosslinked structure do not decompose thermally. In the peeling process, UV irradiation further improves the crosslinking density, reducing the adhesive strength.

[0034] The 5% weight loss temperature and the weight loss rate at 300°C can be measured in accordance with JIS K 7120. Furthermore, the 5% weight loss temperature and the weight loss rate at 300°C can be adjusted by the type of base polymer used, the combination of the base polymer and the crosslinking agent, i.e., the type of bond formed between the base polymer and the crosslinking agent, and the amount of crosslinking agent used. In addition, the 5% weight loss temperature and the weight loss rate at 300°C can also be adjusted by the method of forming the adhesive layer. For example, by performing a heat treatment at 100-200°C for 1-30 minutes followed by an aging treatment at 30-70°C for 1-7 days, the reaction between the base polymer and the crosslinking agent proceeds sufficiently, the 5% weight loss temperature tends to increase further, and the weight loss rate at 300°C tends to decrease further.

[0035] It is preferable that the adhesive layer's adhesive strength is reduced by ultraviolet irradiation. This allows the layer to adhere closely to the wafer 20 and protect the element formation surface 20a from the bonding process S1 to the dicing process S4, and then, in the subsequent peeling process, the adhesive strength is reduced by ultraviolet irradiation, allowing the chip to be picked up without any adhesive residue.

[0036] Furthermore, since such a reaction effectively reduces the adhesive strength, the adhesive layer may contain a base polymer having polymerizable double bonds and crosslinkable groups, and a crosslinking agent. In addition, in the adhesive layer, the crosslinkable groups of the base polymer and the crosslinking agent may react to form a three-dimensional crosslinked structure. As a result, when irradiated with ultraviolet light, the photopolymerization initiator causes the three-dimensional crosslinked structure or the polymerizable double bonds of the base polymer to bond together, forming a crosslinked structure. This effectively reduces the adhesive strength of the adhesive layer.

[0037] Furthermore, when the base polymer and crosslinking agent form a three-dimensional crosslinked structure, the photopolymerization initiator becomes the main small molecule in the adhesive layer. Each component is described in detail below.

[0038] The base polymer constituting the main component of the adhesive layer is not particularly limited, but examples include (meth)acrylic acid ester copolymers. The shape of the (meth)acrylic acid ester copolymer is not particularly limited, but examples include linear, branched, or crosslinked shapes. Among these, having a crosslinked shape is preferred. By using such a base polymer, the physical properties of the adhesive layer can be adjusted. The base polymer having a crosslinked or branched shape may be formed by bonding epoxy groups, etc., of a base polymer having a linear or branched shape via a crosslinking agent described later.

[0039] The monomers constituting the (meth)acrylic acid ester copolymer are not particularly limited, but examples include alkyl (meth)acrylic acid esters having an alkyl group with 1 to 3 carbon atoms, (meth)acrylic acid esters having a glycidyl group, (meth)acrylic acid esters having a hydroxyl group, and monomers having an aromatic group. In addition, the (meth)acrylic acid ester copolymer may also contain copolymerizable vinyl monomers other than acrylic monomers.

[0040] The alkyl (meth)acrylate ester having an alkyl group with 1 to 3 carbon atoms is not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate.

[0041] The (meth)acrylic acid ester having a glycidyl group is not particularly limited, but examples include glycidyl (meth)acrylate and allyl glycidyl ether. The constituent units derived from the (meth)acrylic acid ester having a glycidyl group may be used for the purpose of introducing epoxy groups into the base polymer. The epoxy groups introduced into the base polymer react with the crosslinking agent described later, causing the base polymers to bond to each other and become three-dimensionally crosslinked.

[0042] The (meth)acrylic acid ester having a hydroxyl group is not particularly limited, but examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, pentaerythritol triacrylate, glycidol di(meth)acrylate, and dipentaerythritol pentaacrylate. The constituent units derived from the (meth)acrylic acid ester having a hydroxyl group may be used for the purpose of introducing epoxy groups into the base polymer. The hydroxyl groups introduced into the base polymer react with the crosslinking agent described later, causing the base polymers to bond to each other and become three-dimensionally crosslinked.

[0043] The monomers having aromatic groups are not particularly limited, but examples include styrene, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate.

[0044] Among these, an acrylic resin having a polymerizable double bond with a hydroxyl group or a carboxyl group is preferred as the base polymer, and the adhesive layer preferably contains a crosslinked structure derived from the acrylic resin. By including such a base polymer and a crosslinked structure derived therefrom, the adhesiveness tends to be further improved before UV irradiation, and the peelability tends to be further improved after UV irradiation.

[0045] The glass transition temperature of the base polymer is preferably -90 to -30°C, -80 to -40°C, or -70 to -50°C. Furthermore, having the glass transition temperature of the base polymer within the above range tends to make it easier to adjust the adhesive strengths N0 and N1 within the above range.

[0046] The base polymer content is preferably 85-99% by mass, 90-98% by mass, or 92-97% by mass, relative to the total amount of the adhesive layer.

[0047] The crosslinking agent is not particularly limited as long as it has two or more functional groups that react with crosslinkable groups such as carboxyl groups and hydroxyl groups of the base polymer.

[0048] Such crosslinking agents are not particularly limited, but examples include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, isocyanurate of hexamethylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, trim Isocyanate crosslinking agents such as tyrolpropane tolylene diisocyanate adduct, trimethylolpropane xylylene diisocyanate adduct, triphenylmethane triisocyanate, and methylenebis(4-phenylmethane) triisocyanate; N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, bisphenol A·epichlorohydrin type epoxy resins, and N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-yl] Epoxy crosslinking agents such as methylamine, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, etc.; tetramethylolmethane-tri-β-agile Examples include aziridine crosslinking agents such as dinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide); and melamine crosslinking agents such as hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexasubtoxymethylmelamine, hexapentyloxymethylmelamine, and hexahexyloxymethylmelamine.

[0049] Among these, epoxy crosslinking agents and isocyanate crosslinking agents are preferred, with epoxy crosslinking agents being more preferred. By using an epoxy crosslinking agent, the base polymers can be crosslinked with highly heat-resistant ester bonds. By including a crosslinked structure derived from the epoxy crosslinking agent, the adhesive layer is less susceptible to thermal decomposition and exhibits good heat resistance even in processes exposed to high temperatures, such as the metal layer formation process S3.

[0050] The crosslinking agent content is preferably 0.5 to 6.0 parts by mass, 0.7 to 4.0 parts by mass, 1.0 to 3.0 parts by mass, or 1.2 to 2.5 parts by mass per 100 parts by mass of the base polymer. By having the crosslinking agent content within the above range, the adhesive layer is less susceptible to thermal decomposition and can exhibit good heat resistance.

[0051] The photopolymerization initiator is not particularly limited as long as it is an initiator that generates active species such as radicals, but examples include: benzophenone and its derivatives; benzoin-type photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, and benzyldimethyl ketal; acetophenone-type photopolymerization initiators such as diethoxyacetophenone and 4-tert-butyltrichloroacetophenone; thioxanthone and its derivatives; camphorquinone, 7,7-di Camphorquinone-type photopolymerization initiators such as methyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxy-2-bromoethyl ester, 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxy-2-methyl ester, and 7,7-dimethyl-2,3-dioxobicyclo[2.2.1]heptane-1-carboxylic acid chloride; 2-methyl-1-[4-(methylthio)phenyl]-2- α-aminoalkylphenone type photopolymerization initiators such as morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1; benzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, benzoyl diethoxyphosphine oxide, 2,4,6-trimethylbenzoyl dimethoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl diethoxyphenylphosphine oxide, bis( Examples include acylphosphine oxide type photopolymerization initiators such as 2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and α-hydroxyalkylphenone type photopolymerization initiators such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one.

[0052] The content of the photopolymerization initiator is preferably 1.0 to 5.0 parts by mass, 1.5 to 4.0 parts by mass, or 2.0 to 3.0 parts by mass per 100 parts by mass of the base polymer. By having a photopolymerization initiator content within the above range, effective curing occurs upon ultraviolet irradiation. As the reaction progresses, the adhesive strength tends to decrease further.

[0053] The adhesive force N0 of the adhesive layer to the silicon wafer before heating is preferably 0.2 to 5.0 N / 25 mm, 0.3 to 2.5 N / 25 mm, 0.4 to 1.0 N / 25 mm, and 0.5 to 0.8 N / 25 mm at 25°C. By having the adhesive force N0 of the adhesive layer to the silicon wafer within the above range, the element formation surface of the wafer 20 can be protected more appropriately.

[0054] The adhesive force N1 of the adhesive layer to the silicon wafer after heating at 250°C for 5 minutes is preferably 0.5 to 7.0 N / 25 mm, 0.7 to 6.0 N / 25 mm, 1.0 to 5.0 N / 25 mm, and 1.1 to 4.0 N / 25 mm at 25°C. By having the adhesive force N1 of the adhesive layer to the silicon wafer within the above range, adhesion can be maintained even at high temperatures, and the element formation surface of the wafer 20 can be more appropriately protected.

[0055] After heating at 250°C for 5 minutes and then UV irradiation, the adhesive strength N2 of the adhesive layer to the silicon wafer is preferably 0.01 to 1.0 N / 25 mm, 0.03 to 0.80 N / 25 mm, 0.05 to 0.60 N / 25 mm, 0.07 to 0.40 N / 25 mm, and 0.08 to 0.20 N / 25 mm at 25°C. Because the adhesive strength N2 of the adhesive layer to the silicon wafer is within the above range, even when UV irradiation is performed after a heating process, the photopolymerization initiator functions and the crosslinking reaction proceeds, and the adhesive strength can be sufficiently reduced, which tends to further improve peelability.

[0056] The ratio of adhesive strength N1 to adhesive strength N0 (N1 / N0) is preferably 1.0 to 4.0, 1.2 to 3.5, 1.4 to 3.0, or 1.6 to 2.5. When the ratio (N1 / N0) is within the above range, good adhesion tends to be maintained before and after the heating process.

[0057] The ratio of adhesive strength N2 to adhesive strength N1 (N2 / N1) is preferably 0.01 to 0.30, 0.02 to 0.20, or 0.03 to 0.10. When the ratio (N2 / N1) is within the above range, the adhesive strength tends to be sufficiently reduced when the adhesive layer is irradiated with ultraviolet light during the peeling process.

[0058] The adhesive strengths N0 to N2 can be measured according to JIS Z 0237 (2009). Furthermore, the adhesive strengths N0 to N2 can be adjusted by the type and amount of photopolymerization initiator, base polymer, and crosslinking agent used.

[0059] The thickness of the adhesive layer is preferably 0.2 to 100 μm, 0.5 to 50 μm, 0.7 to 25 μm, or 1.0 to 20 μm. Having a thickness within these ranges tends to minimize interference with conformability and reduce adhesive residue.

[0060] 2. Method for manufacturing wafer processing tape The method for manufacturing the wafer processing tape of this embodiment is not particularly limited, but is not particularly limited as long as it includes a step of forming an adhesive layer 12 on the surface 11a of the base layer 11.

[0061] The method for forming the adhesive layer 12 is not particularly limited, but for example, the films may be dry-laminated together, or the composition may be coated onto the surface of the base layer 11, and the composition may be dried or photocured to form the adhesive layer 12. Alternatively, the adhesive layer 12 may be bonded to the base layer 11 via an adhesive layer different from the adhesive layer 12.

[0062] 3. Wafer Processing Method The wafer processing method of this embodiment includes a processing step of attaching the wafer processing tape to a wafer and performing wafer processing.

[0063] As shown in Figure 2, the wafer processing method may include a bonding step S1 in which the wafer processing tape 10 is bonded to the element formation surface 20a of the wafer 20; a back grinding step S2 in which the non-element formation surface 20b of the wafer 20 bonded to the wafer processing tape 10 is polished with a grinder 40; a metal layer formation step S3 in which a metal layer 21 is formed on the non-element formation surface 20b opposite to the surface to which the wafer processing tape 10 is bonded; a dicing step S4 in which the wafer 20 bonded to the wafer processing tape 10 is diced to produce a chip 30; a processing step S5 in which the back surface of the chip 30 is surface treated by etching or sputtering or reflow treatment; and a peeling step S6 in which the wafer processing tape is peeled off.

[0064] 3.1.Lamination process The bonding step S1 is a step of bonding the wafer processing tape 10 to the element formation surface 20a of the wafer 20. The surface of the wafer 20 to which the wafer processing tape 10 is bonded may be the non-element formation surface 20b.

[0065] In the bonding process, the wafer processing tape 10 may be bonded to the wafer main surface 20a after being preheated, or it may be bonded to the wafer main surface 20a and then heated. Alternatively, the wafer processing tape 10 may be bonded to the wafer main surface 20a without heating. By bonding the surface 11a of the adhesive layer 12 to the element formation surface 20a of the wafer while heated, the surface 11a of the adhesive layer 12 can be bonded in a state where it follows the element formation surface 20a of the wafer (see S2 in Figure 2). In this way, the protrusions are embedded in the wafer processing tape 10, thereby protecting the element formation surface 20a of the wafer that has the protrusions.

[0066] The heating temperature is preferably 60 to 150°C, more preferably 70 to 140°C, and even more preferably 80 to 130°C. The heating time for the wafer processing tape 10 is preferably 3 to 120 seconds, and more preferably 5 to 90 seconds. When the heating conditions are within the above range, the conformability of the wafer processing tape 10 tends to improve.

[0067] 3.2. Processing process The processing steps for processing the wafer 20 with the wafer processing tape 10 bonded to the wafer 20 are not particularly limited, and any wafer processing process can be applied as appropriate. For example, processing steps include a backgrinding step S2, a metal layer formation step S3, a dicing step S4, and a processing step S5.

[0068] Furthermore, as shown in Figure 2, a processing process that combines these steps includes a metal layer formation step S3 in which a metal layer 21 is formed after the backgrinding step S2, and a dicing step S4 in which the thinned wafer is diced by blade dicing or the like. In the following, a process in which the metal layer formation step S3 and the dicing step S4 are performed after the backgrinding step S2 will be described, but this embodiment is not limited to this.

[0069] 3.2.1. Backgrinding Process The backgrinding process S2 is a process of polishing the non-element formation surface 20b of the wafer 20 that is bonded to the wafer processing tape 10. Specifically, with the wafer processing tape 10 attached to the element formation surface 20a as a backgrinding tape from the viewpoint of protecting the element formation surface 20a, the non-element formation surface 20b of the wafer 20 is ground (backgrinded) to a desired thickness.

[0070] The specific method of back grinding is not particularly limited, and known methods can be used. For example, a method can be used in which a slurry containing abrasive particles is supplied to the back surface 20b of the wafer 20 while grinding. The thickness of the thinned wafer obtained by this process is not particularly limited as long as it is a thickness suitable for the processing purpose, but as an example, it is preferably 300 μm or less, 150 μm or less, and 50 μm or less.

[0071] In backgrinding, a load is applied in the thickness direction of the wafer 20, which can easily cause damage to protrusions and other parts, leading to a decrease in yield. In contrast, by using the wafer processing tape 10 of this embodiment, it is possible to perform processing with at least a portion of the protrusions embedded in the wafer processing tape 10, thereby avoiding damage to the protrusions and other parts.

[0072] In the wafer processing method of this embodiment, when performing backgrinding on a wafer that has been pre-formed with modified portions or grooves on its surface for fragmentation, the wafer 20 may be thinned to approximately the same depth as the modified portions or grooves when the wafer 20 is thinned from the back surface 20b of the wafer 20. This allows for simultaneous thinning by backgrinding and fragmentation.

[0073] 3.2.2. Metal layer formation process The metal layer formation step S3 is a step in which a metal layer 21 is formed on the surface 20b of the wafer 20 opposite to the surface 20a to which the wafer processing tape 10 is bonded. The method for forming the metal layer is not particularly limited, but examples include ALD (atomic layer deposition) and CVD (chemical vapor deposition). The conditions for forming the metal layer using these methods are not particularly limited, but examples include processing at 200-300°C for 3-10 minutes.

[0074] 3.2.3. Dicing Process The dicing process S4 is a process of dicing the wafer 20. The dicing method is not particularly limited, but one example is blade dicing, in which the wafer is cut into semiconductor chips 30 using a dicing blade.

[0075] 3.2.4. Processing steps In processing step S5, the back surface of the chip 30 may be surface-treated by etching, sputtering, or reflow to form any surface treatment layer 22. The processing method is not particularly limited, and any processing can be selected according to the application of the chip.

[0076] 3.3. Peeling Process The peeling step S6 is the process of peeling the wafer processing tape 10 from the wafer 20 or semiconductor chip 30. The peeling step in which the semiconductor chip 30 is taken from the wafer processing tape is also called the peeling step.

[0077] In the peeling step S6, the wafer processing tape 10 may be peeled off at room temperature, or it may be peeled off under heating. Also, in the peeling step S6, if the adhesive layer 12 contains a base polymer having polymerizable double bond groups and a photopolymerization initiator, the adhesive layer 12 may be cured by irradiation with ultraviolet light before peeling to reduce its adhesion to the wafer 20. This tends to further improve release properties and further suppress contamination by residue from the tape. Note that if the substrate is transparent, the ultraviolet irradiation may be performed from the substrate layer 11 towards the adhesive layer 12.

[0078] Furthermore, when picking up the semiconductor chip 30 from the wafer processing tape, although not particularly limited, for example, the semiconductor chip 30 may be pushed up with a push-up needle and then picked up by suction with a suction collet.

[0079] Alternatively, during pickup, an expanding device may be used to stretch the wafer processing tape 10 in the planar direction, separating each semiconductor chip 30, and then the chips may be picked up by a pickup device. [Examples]

[0080] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples. Unless otherwise specified, each physical property value was measured at room temperature. In addition, unless otherwise specified, the amount of each raw material used is given in terms of solid content. Therefore, if it is stated that 100 parts by mass of a raw material with a solid content of 40% is used, the total amount used, including the liquid content, will be 250 parts by mass.

[0081] (Example 1) A composition for an adhesive layer was prepared by mixing 100 parts by mass of an acrylic resin having polymerizable carbon double bonds, carboxyl groups, and hydroxyl groups (Vinylole ELX-6512, manufactured by Resonaq, with a glass transition temperature of -60°C), 2.5 parts by mass of an acylphosphine oxide type photopolymerization initiator (Omnirad 819, manufactured by IGM Resins BV, with a molecular weight of 418 and a 50% weight loss rate of 246°C), and 1.7 parts by mass of an epoxy crosslinking agent (TETRAD-X, manufactured by Mitsubishi Gas Chemical Company).

[0082] A transparent polyamide film with a thickness of 50 μm (Unitika Corporation, Uniamide EX-50, 365 nm UV transmittance 85%, no yield point) was used as the base layer, and the adhesive layer composition prepared as described above was applied to one surface of the film. After heating at 150°C for 2 minutes, the film was aged at 40°C for 3 days to crosslink the carboxyl and hydroxyl groups of the acrylic resin with the epoxy groups of the epoxy crosslinking agent. This produced the wafer processing tape of Example 1. The thickness of the adhesive layer was 15 μm.

[0083] (Example 2) The wafer processing tape for Example 2 was prepared in the same manner as in Example 1, except that the amount of epoxy crosslinking agent (TETRAD-X, manufactured by Mitsubishi Gas Chemical Company) used was 3.5 parts by mass.

[0084] (Comparative Example 1) A composition for an adhesive layer was prepared by mixing 100 parts by mass of an acrylic resin having polymerizable carbon double bonds and hydroxyl groups (Otsuka Chemical Co., Ltd., PSA-OC50DK, glass transition temperature: -58℃), 2 parts by mass of an acylphosphine oxide type photopolymerization initiator (IGM Resins BV, Omnirad 819, molecular weight 418, 50% weight loss rate 246℃), and 2.3 parts by mass of an isocyanate crosslinking agent (Mitsui Chemicals, Ltd., Takenate D-101E).

[0085] A transparent polyamide film with a thickness of 50 μm (Unitika Corporation, Uniamide EX-50, 365 nm UV transmittance 85%, no yield point) was used as the substrate layer, and the adhesive layer composition prepared as described above was applied to one surface of the film. After heating at 150°C for 2 minutes, the film was aged at 40°C for 3 days to crosslink the carboxyl and hydroxyl groups of the acrylic resin with the epoxy groups of the epoxy crosslinking agent. This produced the wafer processing tape of Comparative Example 1. The thickness of the adhesive layer was 15 μm.

[0086] (Comparative Example 2) A wafer processing tape for Comparative Example 2 was prepared in the same manner as for Comparative Example 1, except that the amount of acylphosphine oxide type photopolymerization initiator (Omnirad 819, molecular weight 418, 50% weight loss rate 246°C, manufactured by IGM Resins BV) used was 5 parts by mass, and the amount of isocyanate crosslinking agent (Takenate D-101E, manufactured by Mitsui Chemicals, Inc.) used was 3.6 parts by mass.

[0087] (Adhesive strength) The adhesive strength was measured in accordance with JIS Z 0237. Specifically, the wafer processing tape was placed on the mirror surface of a silicon wafer, and a 2kg roller was passed over it once to bond it. After that, it was left to stand at 23°C for 30 minutes to bond the surface of the adhesive layer of the wafer processing tape to the mirror surface of the silicon wafer. Then, without heating, the wafer processing tape was peeled off at a peeling angle of 180° and a peeling speed (tensile speed) of 300 mm / min, and the adhesive strength N0 (N / 25mm) was determined.

[0088] Furthermore, after bonding the surface of the adhesive layer of the wafer processing tape to the mirror surface of a silicon wafer, the wafer was heated at 250°C for 5 minutes, and then the adhesive force N1 (N / 25mm) was measured when the wafer processing tape was peeled off at a peeling angle of 180° and a peeling speed (tensile speed) of 300 mm / min.

[0089] Furthermore, after bonding the surface of the adhesive layer of the wafer processing tape to the mirror surface of the silicon wafer, it was heated at 250°C for 5 minutes, and then UV irradiation was applied to the adhesive layer from the back surface 11b of the substrate 11. The adhesive force N1 (N / 25mm) was then measured when the wafer processing tape was peeled off at a peeling angle of 180° and a peeling speed (tensile speed) of 300 mm / min.

[0090] (Processing) A bonding process was performed in which the surface of the adhesive layer of the wafer processing tape was bonded to a silicon wafer, and then it was heated at 250°C for 5 minutes, simulating a metal layer formation process. The wafer was then diced, and 900 mJ / cm² of pressure was applied to the adhesive layer from the back side of the substrate layer of the wafer processing tape using a high-pressure mercury lamp. 2 The adhesive layer was cured by irradiating it with ultraviolet light, and the chip was peeled off the wafer processing tape.

[0091] (Pickup ability) In the above processing process, the rate at which semiconductor chips could be picked up was evaluated according to the following criteria. A: The success rate of picking up chips is over 95%. B: Chip pickup success rate is between 85% and 95% C: Chip pickup success rate is between 75% and 85% D: Chip pickup success rate is less than 75%

[0092] [Table 1]

[0093] In Examples 1 and 2, the use of an epoxy crosslinking agent resulted in the base polymer and the crosslinking agent being bonded via ester bonds to form a three-dimensional crosslinked structure. On the other hand, in Comparative Examples 1 and 2, the use of an isocyanate crosslinking agent resulted in the base polymer and the crosslinking agent being bonded via urethane bonds to form a three-dimensional crosslinked structure. Compared to ester bonds, urethane bonds are generally more susceptible to thermal decomposition at high temperatures, which is thought to be the reason for the decrease in the 5% weight loss temperature.

[0094] Furthermore, although Example 2 contains more crosslinking agent than Example 1, it is thought that the 5% weight loss temperature decreased because there was a relatively larger amount of unreacted crosslinking agent that was not involved in the three-dimensional crosslinked structure.

[0095] On the other hand, the greater the amount of crosslinking agent and the higher the crosslinking density of the three-dimensional crosslinked structure, the lower the adhesive strength tends to be. This is presumed to be because the elastic modulus of the adhesive layer decreases as the crosslinking density increases, reducing the wettability to the adherend (wafer).

[0096] Furthermore, a similar adhesive layer composition to that in Example 1 was prepared, applied to a transparent polyamide film, and then heated at 150°C for 60 minutes without aging to produce a wafer processing tape. The 5% weight loss temperature of this wafer processing tape was less than 270°C. From this, it is considered preferable to perform a predetermined aging treatment from the viewpoint of allowing the reaction between the base polymer and the crosslinking agent to proceed sufficiently and improving the 5% weight loss temperature.

[0097] Furthermore, the wafer processing tapes of Examples 1 and 2 exhibited excellent chemical resistance, dicing properties, and expandability, making them suitable for use as wafer processing tapes that can be used across the wafer during semiconductor processing. [Industrial applicability]

[0098] The present invention has industrial applicability as a wafer processing tape and processing method using the same, because the adhesive strength can be sufficiently reduced when the adhesive layer is irradiated with ultraviolet light after a heating process. [Explanation of Symbols]

[0099] 10... Tape for wafer processing, 11... Substrate layer, 11a... Surface, 12... Adhesive layer, 12a... Surface, 12b... Back surface, 20... Wafer, 20a... Element formation surface, 20b... Non-element formation surface, 21... Metal layer, 22... Arbitrary surface treatment layer, 30... Semiconductor chip, 40... Grinder, S1... Lamination process, S2... Back grinding process, S3... Metal layer formation process, S4... Dicing process, S5... Processing process, S6... Peeling process

Claims

1. A base layer and The base layer has an adhesive layer disposed on at least one side, The temperature at which the adhesive layer loses 5% of its weight is 270°C or higher. Tape for wafer processing.

2. The weight loss rate of the adhesive layer at 300°C is 88% or more. The wafer processing tape according to claim 1.

3. The adhesive strength N1 of the adhesive layer to the silicon wafer after heating at 250°C for 5 minutes is 0.5 to 7.0 N / 25 mm at 25°C. The wafer processing tape according to claim 1.

4. After heating at 250°C for 5 minutes and then UV irradiation, the adhesive strength N2 of the adhesive layer to the silicon wafer is 0.01 to 1.0 N / 25 mm at 25°C. The wafer processing tape according to claim 1.

5. The adhesive layer further comprises an acrylic resin having a polymerizable double bond with a hydroxyl group or a carboxyl group. The wafer processing tape according to claim 1.

6. The adhesive layer further comprises an epoxy crosslinking agent. The wafer processing tape according to claim 1.

7. The adhesive layer comprises a base polymer and a crosslinking agent. The amount of the crosslinking agent is 0.5 to 6.0 parts by mass per 100 parts by mass of the base polymer. The wafer processing tape according to claim 6.

8. The aforementioned substrate layer contains a polyamide resin. The wafer processing tape according to claim 1.

9. The aforementioned substrate layer does not have a yield point. The wafer processing tape according to claim 1.

10. The ultraviolet transmittance of the substrate layer at 365 nm is 70% or more. The wafer processing tape according to claim 1.

11. A processing step comprising attaching a wafer processing tape according to any one of claims 1 to 10 to a wafer and performing wafer processing, Wafer processing method.

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