Dicing tape base film

Abstract

To provide a dicing tape base film made of a polyolefin resin that has no yield point during expansion and exhibits excellent uniform expansion.SOLUTION: A dicing tape base film includes a release layer, a base layer, and a dicing layer in this order, and the release layer is primarily composed of an ethylene-propylene copolymer, the base layer contains a 1-butene polymer, a thermoplastic elastomer, and mineral oil, and the dicing layer contains at least one of an ethylene-propylene copolymer and an olefin-based thermoplastic elastomer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a substrate film for a dicing tape, which is used to fix a semiconductor wafer when the semiconductor wafer is diced into chips. [Background technology]

[0002] A known method for manufacturing semiconductor chips is to slice a cylindrical single crystal silicon ingot using a wire saw or similar, etch and polish it, and then dice (cut and separate) the resulting semiconductor wafers into chips with diameters of approximately 12 inches and 8 inches. The diced chips are then transferred to an expanding process where they are picked up.

[0003] Dicing tape is used to fix the semiconductor wafer in the dicing process.

[0004] During dicing, a wafer is attached to a dicing tape with an adhesive layer formed on a dicing tape substrate film. The wafer is then diced while fixed in place. The dicing tape is then expanded to increase the spacing between chips, allowing the chips to be picked up in a subsequent process. If the dicing tape expands in an insufficient manner, the spacing between chips may become narrow, potentially causing sensors and other devices to malfunction during pickup. Furthermore, if the thickness of the dicing tape substrate film varies significantly due to discharge fluctuations such as draw resonance during melt film formation, the dicing tape may experience poor processing stability. To address these issues, dicing tape substrate films are required to have no yield point and excellent expandability. Patent Document 1 proposes a substrate film for dicing tape made of a polyolefin resin containing at least a 1-butene homopolymer.

[0005] However, the base film described in Patent Document 1 has a problem in that the uniformity when the dicing tape is expanded is insufficient. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-66587 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a substrate film for dicing tape made of a polyolefin substrate that has no yield point during expansion and exhibits excellent uniform expansion. [Means for solving the problem]

[0008] The present invention is as follows. [1] A substrate film for dicing tape having a release layer, a base layer, and a dicing layer in this order, wherein the release layer is primarily composed of an ethylene-propylene copolymer, the base layer contains a 1-butene polymer, a thermoplastic elastomer, and mineral oil, and the dicing layer contains at least one of an ethylene-propylene copolymer and an olefin-based thermoplastic elastomer. [2] The substrate film for a dicing tape according to [1], wherein the 1-butene polymer in the substrate layer is a 1-butene homopolymer, and the thermoplastic elastomer is a styrene-based elastomer. [3] The substrate film for dicing tape according to [1], wherein the substrate layer contains 10 to 75 mass% of a 1-butene polymer, 9 to 38 mass% of a thermoplastic elastomer, 11 to 47 mass% of a mineral oil, and 0 to 70 mass% of other polyolefins (wherein the total mass of the substrate layer is 100 mass%). [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a base film for a dicing tape that has no yield point during expansion, has a 25% modulus of 4 N / 10 mm or more, and can be expanded uniformly. DETAILED DESCRIPTION OF THE INVENTION

[0010] The substrate film for dicing tape of the present invention will be specifically described below.

[0011] The present invention is a laminated film having a release layer, a substrate layer, and a dicing layer in this order.

[0012] The method for producing the substrate film for dicing tape of the present invention is not particularly limited. For example, melt extrusion molding methods such as the T-die method and inflation method can be mentioned, but the T-die method is preferred from the viewpoint of thickness accuracy.

[0013] [Release layer] In the present invention, the resin constituting the release layer preferably contains an ethylene-propylene copolymer as a main component, taking into consideration the transportability and windability in the melt extrusion film-forming process and the expandability in the semiconductor wafer dicing process. Examples of the ethylene-propylene copolymer include an ethylene-propylene random copolymer and an ethylene-propylene block copolymer, with an ethylene-propylene block copolymer being particularly preferred.

[0014] Here, the main component means 50% by mass or more of the total amount of resin in the release layer.

[0015] A surface roughening agent may be added to the release layer to improve the lubricity.

[0016] Preferred examples of the surface-roughening agent include inorganic particles, organic particles, etc. As the inorganic particles, one or more types of inorganic particles selected from the group consisting of inorganic oxide particles (silica particles, alumina particles, titanium oxide particles, etc.), inorganic carbonate particles (calcium carbonate particles, barium carbonate particles, etc.), and inorganic silicate particles (aluminum silicate particles, talc particles, kaolin particles, etc.) can be preferably used, and as the organic particles, one or more types of organic particles selected from the group consisting of acrylic resin particles, polyolefin resin particles, and polystyrene resin particles can be preferably used.

[0017] The inorganic particles and organic particles preferably have an average particle size in the range of 1 to 20 μm. If the average particle size is less than 1 μm, the particles may become more cohesive and less dispersible in the release layer, whereas if the average particle size is more than 20 μm, the particles may fall off during film formation and processing.

[0018] The polyolefin resin particles are preferably polyethylene resin particles. The polyethylene resin particles have a density of 0.935 g / cm. 3 The above high density polyethylenes are preferred, and crosslinked polyethylenes are preferred from the viewpoint of heat resistance and uniformity of particle size.

[0019] The acrylic resin particles are preferably crosslinked polymethyl acrylate particles.

[0020] The polystyrene resin particles are preferably crosslinked polystyrene particles.

[0021] The content of the surface-roughening agent in the release layer is preferably in the range of 0.2 to 5.0% by mass. If the content is less than 0.2% by mass, the effect of adding the agent may not be observed, whereas if the content is more than 5.0% by mass, particles may fall off.

[0022] [Base material layer] The substrate layer contains 1-butene polymer, thermoplastic elastomer, mineral oil and other polyolefins.

[0023] The substrate layer preferably comprises 10 to 75% by mass of 1-butene polymer, 9 to 38% by mass of thermoplastic elastomer, 11 to 47% by mass of mineral oil, and 0 to 70% by mass of other polyolefins (where the total amount of the substrate layer is 100% by mass), and more preferably 10 to 60% by mass of 1-butene polymer, 16 to 38% by mass of thermoplastic elastomer, 19 to 47% by mass of mineral oil, and 0 to 55% by mass of other polyolefins (where the total amount of the substrate layer is 100% by mass).

[0024] Mineral oil is an oil obtained from petroleum, and is a general term for hydrocarbon compounds derived from underground resources such as petroleum (crude oil), natural gas, and coal, or mixtures containing impurities. Examples include those commonly used as lubricants in industrial products. Most mineral oil-based lubricants are composed of aromatic hydrocarbons, paraffinic hydrocarbons, and naphthenic (cycloalkane) hydrocarbons, with the majority of base oils being paraffinic hydrocarbons. The carbon number is preferably C15-C50, the molecular weight is preferably 200-700 g / mol, and the boiling point converted to atmospheric pressure is preferably in the range of 250-600°C. The use of the 1-butene polymer as the resin component of the base layer results in a low yield point and excellent uniformity during expansion. The 1-butene polymer is preferably a homopolymer or a copolymer with an α-olefin, with the homopolymer being particularly preferred because it provides high stress during expansion. The high stress during expansion makes it easier to widen the gap (kerf width) between the silicon wafers that are cut by expanding them after the silicon wafer is attached to the dicing tape and diced.

[0025] Preferred examples of the α-olefin include ethylene, propylene, 1-hexene, and 1-octene.

[0026] If the content of the 1-butene polymer is less than 10% by mass, the stress during expansion may be insufficient, and if it exceeds 75% by mass, the uniformity of expansion may deteriorate.

[0027] The thermoplastic elastomer, which is the resin component of the base layer, is preferably one or more selected from the group consisting of ethylene-based elastomers, propylene-based elastomers, 1-butene-based elastomers, 4-methylpentene-1-based elastomers, and styrene-based elastomers. Styrene-based elastomers are particularly preferred, and examples of styrene-based elastomers include SEBS (hereinafter sometimes abbreviated as SEBS) obtained by hydrogenating styrene-butadiene-styrene copolymer (SBS), and SEPS (hereinafter sometimes abbreviated as SEPS) obtained by hydrogenating styrene-isoprene-styrene copolymer (SIS).

[0028] If the content of the thermoplastic elastomer is less than 16% by mass, the expandability may be insufficient, and if it exceeds 38% by mass, the dispersibility may be poor and the elastomer may become gel.

[0029] Furthermore, it is preferable to contain a mineral oil in order to obtain good expandability. Examples of the mineral oil include mineral oil, which is preferable because it contributes to uniform expandability.

[0030] If the content of the mineral is less than 19% by mass, the additive effect may not be observed, and if it exceeds 47% by mass, it may bleed out onto the surface of the release layer and dicing layer, causing process contamination and reduced processability.

[0031] The other polyolefin is preferably polypropylene and / or polyethylene, and as polypropylene, ethylene-propylene random copolymer, ethylene-propylene block copolymer, polypropylene homopolymer, etc. are more preferred, and as polyethylene, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, etc. are more preferred.

[0032] [Dicing layer] The dicing layer contains at least one of an ethylene-propylene copolymer and an olefin-based thermoplastic elastomer.

[0033] Preferred examples of the ethylene-propylene copolymer include ethylene-propylene random copolymers and ethylene-propylene block copolymers, and ethylene-propylene block copolymers are particularly preferred because they have good process transportability during film formation and high stress during expansion.

[0034] In the dicing layer of the present invention, an olefin-based thermoplastic elastomer with low crystallinity is preferred because it is less likely to generate cutting waste during the dicing process in which semiconductor wafers such as silicon wafers, sapphire wafers, and SiC wafers are diced (cut) into chips.

[0035] The olefin-based thermoplastic elastomer may preferably be one or more olefin-based thermoplastic elastomers selected from the group consisting of ethylene-based elastomers, propylene-based elastomers, 1-butene-based elastomers, and 4-methylpentene-1-based elastomers. In particular, propylene-based elastomers are preferred from the viewpoint of suppressing cutting debris during dicing.

[0036] An adhesive is applied to the dicing layer, and the resulting dicing tape is used in the dicing and expanding processes of semiconductor wafers. Examples of suitable adhesives include known pressure-sensitive adhesives, heat-curable adhesives, and UV-curable adhesives used in dicing tapes. The adhesive layer can be provided by directly coating the adhesive on the dicing layer. Alternatively, the adhesive layer can be provided by laminating the adhesive layer on a separator or the like having a release layer, attaching the adhesive layer side to the dicing layer of the present invention, and transferring the adhesive layer.

[0037] The dicing layer on which the pressure-sensitive adhesive is processed is preferably surface-treated to improve the adhesiveness of the pressure-sensitive adhesive. Preferred examples of such surface treatment methods include mechanical treatments such as embossing and hairline processing, physicochemical treatments such as plasma treatment, corona treatment and flame treatment, and chemical treatments such as primer treatment using a coupling agent. Among these, physicochemical treatments such as plasma treatment, corona treatment and flame treatment are preferred in view of their simplicity and reduction of the environmental load during treatment.

[0038] The substrate film for a dicing tape of the present invention may contain any other components to the extent that the effects of each layer are not impaired.

[0039] Examples of other components include other polymers, tackifiers, plasticizers, antidegradants, pigments, dyes, antioxidants, antistatic agents, lubricants, foaming agents, heat stabilizers, light stabilizers, inorganic fillers, organic fillers, etc. These may be used alone or in combination of two or more.

[0040] The film thickness of the substrate film for dicing tape of the present invention can be adjusted appropriately according to the required properties, but is preferably 10 to 200 μm, more preferably 20 to 150 μm, and particularly preferably 80 to 140 μm. If the film is thinner than 10 μm, the strength may be insufficient, making it difficult to transport in the dicing tape manufacturing process or causing it to tear during processing or use. If the film is thicker than 200 μm, it may be difficult to transport in the dicing tape manufacturing process, or the clip ring may be difficult to attach after expansion in the dicing process or may come off. If the 25% modulus of the substrate film for dicing tape is 4 N / 10 mm or more, the wafer after stealth dicing can be divided by tape expansion on the expansion stage. [Example]

[0041] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to these examples. These examples and comparative examples were evaluated using the evaluation methods shown below.

[0042] (1) Expandability evaluation (elongation rate) An expanding device manufactured by Hugle Electronics was used. A film was attached to a 6-inch wafer ring and grid lines were drawn at 50 mm intervals. The stage was raised and the film was stretched. The film was clamped with a clip ring and fixed in place in the stretched state. The amount of stretch after expansion was divided by 50 mm to determine the elongation percentage. Stage height: 30mm, 50mm Stage temperature: 25℃ Average elongation rate in MD and TD. △ or above is within the practical range. 〇: 7% or more △: 5% or more ×: Less than 5%.

[0043] (2) Confirmation of yield point and 25% modulus (4N / 10mm) Using a tensile tester (Orientec's universal testing machine "Tensilon (registered trademark)"), tensile tests were performed five times in each of the machine direction (MD) and width direction (TD) of the substrate film in accordance with JIS K 7113-1995 at a temperature of 23°C and a speed of 300 mm / min, and the arithmetic mean value (average value for a total of 10 tests) was used as the tensile test value of the substrate film. The test specimens used for the measurements were rectangular, 10 mm wide and 100 mm long, and the measurement was performed with a chuck distance of 50 mm. At this time, the presence or absence of a yield point and the 25% modulus were confirmed on the tensile strength-tensile elongation curve. No yield point:○ Yield point: × 25% modulus 7N / 10mm or more: Yes 25% modulus 4N / 10mm or more to less than 7N / 10mm: △ 25% modulus less than 4N / 10mm: × △ and above are within the practical range.

[0044] (3) Bleed contamination The dicing tape substrate film, stored and conditioned for 24 hours at 23°C and 60% RH, was laminated to both sides of a 2.0mm thick, 50mm wide, and 100mm long polycarbonate plate (hereafter referred to as PC plate) using a roll press (special pressure roller manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at a lamination pressure of 9,100 N / m and a lamination speed of 300 cm / min. After 24 hours of storage and conditioning at 23°C and 60% RH, the laminated dicing tape substrate film was peeled off in a darkroom and the PC plate was irradiated with a 200-lumen LED and visually inspected for reflected light. The presence or absence of bleed contamination was determined by comparing the degree of opacity of the PC plate surface with that of a raw PC plate without the dicing substrate film. PC board without dicing base film: Standard PC board with dicing substrate film attached, cloudy: bleeding contamination No clouding of PC board with dicing substrate film: No bleeding contamination.

[0045] (1) Ethylene-propylene copolymer (PP-1) MFR: 9.0 (at 230°C) Melting point: 167°C (2) Polypropylene homopolymer (PP-2) MFR: 7.5 (at 230°C) Melting point: 163°C (3) 1-butene polymer: 1-butene homopolymer (PB) MFR: 1.8 (at 190°C) Melting point: 125°C (4) Styrene-based elastomer (TPO-1) MFR: 11.0 (at 230°C), Melting point: No information (5) Propylene elastomer (TPO-2) MFR: 8.0 (at 230℃), Melting point: No information (6) Linear low-density polyethylene (PE-1) MFR: 3.8 (at 190°C), melting point: 90°C, density: 0.904 (7) Mineral oil (lubricant) Properties: Lubricant for plastics (8) Polyethylene resin particles (AB agent) Base resin: Polypropylene, concentration: 10% by mass master Density: 0.94g / cm 3 Average particle size: 10μm.

[0046] Example 1 The constituent resins of each layer listed in Table 1 were fed into three extruders: one for a release layer φ20, one for a base layer φ40, and one for a dicing layer φ35. The extrusion rate of each extruder was adjusted in a T-die composite film-forming machine (multi-manifold) to give a lamination ratio of 12.5% ​​for the release layer, 67.5% for the base layer, and 20.0% for the dicing layer. The layers were laminated in this order and extruded from the T-die composite film-forming machine at an extrusion temperature of 230°C to form a film with a total thickness of 80 μm.

[0047] <Example 2> A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (30% by mass), TPO-1 (27% by mass), lubricant (33% by mass), and PP-2 (10% by mass).

[0048] Example 3 A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (10% by mass), TPO-1 (36% by mass), lubricant (44% by mass), and PP-2 (10% by mass).

[0049] Example 4 A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (10% by mass), TPO-1 (27% by mass), lubricant (33% by mass), and PP-2 (30% by mass).

[0050] <Example 5> A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (10% by mass), TPO-1 (18% by mass), lubricant (22% by mass), and PP-2 (50% by mass).

[0051] Example 6 A laminated film was formed and evaluated in the same manner as in Example 1, except that the base layer composition in Example 1 was changed to PB (40% by mass), TPO-1 (22% by mass), lubricant (28% by mass), and PP-2 (10% by mass), and the dicing layer composition was changed to TPO-2 (100% by mass).

[0052] Example 7 A laminated film was formed and evaluated in the same manner as in Example 1, except that the base layer composition in Example 1 was changed to PB (30% by mass), TPO-1 (27% by mass), lubricant (33% by mass), PP-2 (5% by mass), and TPO-2 (5% by mass), and the dicing layer composition was changed to TPO-2 (100% by mass).

[0053] <Comparative Example 1> A laminated film was formed and evaluated in the same manner as in Example 1, except that the base layer composition in Example 1 was changed to PB (30% by mass), TPO-1 (27% by mass), lubricant (33% by mass), and PP-2 (10% by mass), and the dicing layer composition was changed to PE-1 (100% by mass).

[0054] <Comparative Example 2> A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (68% by mass), TPO-1 (0% by mass), lubricant (22% by mass), and PP-2 (10% by mass).

[0055] <Comparative Example 3> A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (60% by mass), TPO-1 (30% by mass), lubricant (0% by mass), and PP-2 (10% by mass).

[0056] <Comparative Example 4> A laminated film was formed and evaluated in the same manner as in Example 1, except that the substrate layer composition in Example 1 was changed to PB (0 mass%), TPO-1 (23 mass%), lubricant (22 mass%), and PP-2 (55 mass%).

[0057] The base films of Examples 2, 6, and 7 in Table 1 had excellent expandability, with a 25% modulus of 4 N / 10 mm or more, no yield point, and no bleeding contamination. The base films of Examples 1, 3, 4, and 5 in Table 1 had inferior expandability to the base films of Examples 2, 6, and 7, but had a 25% modulus of 4 N / 10 mm or more, no yield point, and no bleeding contamination.

[0058] The base film of Comparative Example 1 in Table 1 was insufficient in expandability and 25% modulus, and yield point and staining were also confirmed. The base film of Comparative Example 2 in Table 1 was insufficient in expandability and 25% modulus, but yield point and bleeding staining were not confirmed. The base film of Comparative Example 3 in Table 1 was insufficient in expandability, but the 25% modulus was 4 N / 10 mm or more, there was no yield point, and bleeding staining was not confirmed. The base film of Comparative Example 4 in Table 1 was insufficient in expandability, and a yield point was confirmed. The 25% modulus was 4 N / 10 mm or more, and bleeding staining was not confirmed.

[0059] [Table 1]

Claims

1. A substrate film having a release layer, a substrate layer, and a dicing layer in this order, a base film for a dicing tape, wherein the release layer contains an ethylene-propylene copolymer as a main component; the base layer contains a 1-butene polymer, a thermoplastic elastomer, and a mineral oil; and the dicing layer contains at least one of an ethylene-propylene copolymer and an olefin-based thermoplastic elastomer.

2. 2. The substrate film for a dicing tape according to claim 1, wherein the 1-butene polymer in the substrate layer is a 1-butene homopolymer, and the thermoplastic elastomer is a styrene-based elastomer.

3. 2. The substrate film for dicing tape according to claim 1, wherein the substrate layer contains 10 to 75% by mass of a 1-butene polymer, 9 to 38% by mass of a thermoplastic elastomer, 11 to 47% by mass of a mineral oil, and 0 to 70% by mass of other polyolefins (wherein the total amount of the substrate layer is 100% by mass).

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