Base film for backgrind tape

Abstract

To provide a substrate film for a back-grinding tape having moderate hardness.SOLUTION: A substrate film for a back-grinding tape at least has an A layer that comprises a resin composition containing a polyester resin, and a B layer that comprises a resin composition containing a soft polyester resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a base film for a backgrinding tape used to fix a semiconductor wafer when grinding the back surface of the semiconductor wafer (hereinafter referred to as "backgrinding"). [Background technology]

[0002] When manufacturing semiconductor chips, fixing films (adhesive tapes) are used to fix semiconductor wafers, and after use, these fixing films are peeled off from the semiconductor wafers.

[0003] Processes for fixing semiconductor wafers using fixing films include the back-grinding process, in which the backside of the semiconductor wafer is ground, and the dicing process, in which the semiconductor wafer is cut and separated into chips. In the back-grinding process, the semiconductor wafer is adjusted (thinned) to a desired thickness. During this process, a back-grinding film is attached to the patterned surface of the semiconductor wafer to protect the patterned surface of the semiconductor wafer. The back-grinding film is composed of a base film layer and an adhesive layer, and the semiconductor wafer is adhered via the adhesive layer.

[0004] Patent Document 1 is the applicant's technology, and discloses a base film for back-grinding that is less likely to warp in the semiconductor wafer during the back-grinding process of thin semiconductor wafers, has excellent dimensional stability, and can effectively suppress blocking when the base film is wound up. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5489501 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a new base film for a backgrind tape. [Means for solving the problem]

[0007] The present invention includes a base film for a backgrinding tape used in the backgrinding process of semiconductor wafers.

[0008] Section 1. A substrate film for a backgrind tape, comprising: It has at least layer A and layer B, Layer A is made of a resin composition containing a polyester-based resin, Layer B is made of a resin composition containing a soft polyester resin, Base film for backgrind tape.

[0009] Section 2. Item 2. The base film for a backgrinding tape according to Item 1, wherein the soft polyester resin has a polyester unit and a polyester polyol unit.

[0010] The substrate film for the backgrinding tape of the present invention can be preferably used as a backgrinding film to be used in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (about 25 μm).

[0011] The base film for a backgrinding tape of the present invention exhibits the effect of preventing warpage of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer.

[0012] The substrate film for a backgrinding tape of the present invention exhibits the effect of excellent releasability when peeling off a surface protection tape (adhesive tape for backgrinding). [Effects of the Invention]

[0013] The present invention can provide a new substrate film for a backgrind tape having an appropriate hardness. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention includes a base film for a backgrinding tape used in the backgrinding process of semiconductor wafers.

[0015] (1) Base film for backgrinding tape The base film for the backgrind tape of the present invention is It has at least layer A and layer B, Layer A is made of a resin composition containing a polyester-based resin, The layer B is made of a resin composition containing a soft polyester resin.

[0016] (1-1) Layer A of the base film The layer A of the base film for the backgrinding tape of the present invention is made of a resin composition containing a polyester resin.

[0017] Polyester Resin As the polyester-based resin, it is preferable to use, for example, a resin obtained by polycondensing a dicarboxylic acid and a diol.

[0018] The dicarboxylic acid is not particularly limited, and preferably, for example, o-phthalic acid, terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octylsuccinic acid, cyclohexanedicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylenecarboxylic acid, anhydrides thereof, and lower alkyl esters thereof are used.

[0019] The diol is not particularly limited, and preferred examples thereof include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, dipropylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,3-pentanediol, and 2-ethyl-1,3-hexanediol; Alicyclic diols such as 2,2-bis(4-hydroxycyclohexyl)propane, alkylene oxide adducts of 2,2-bis(4-hydroxycyclohexyl)propane, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol are used.

[0020] Among the polyester-based resins, those containing a component derived from terephthalic acid as a dicarboxylic acid component and a component derived from ethylene glycol as a diol component are preferred, and the use of such polyester-based resins can impart heat resistance.

[0021] When laminating with a flexible polyester resin, the dicarboxylic acid of the polyester resin used to further improve productivity and moldability is 100 mol % of the dicarboxylic acid component, and the lower limit of the component derived from terephthalic acid is preferably 60 mol %, more preferably 65 mol %, and the upper limit is preferably 100 mol %, more preferably 95 mol %. Furthermore, the lower limit of the dicarboxylic acid component other than the component derived from terephthalic acid is preferably 0 mol %, more preferably 5 mol %, and the upper limit is preferably 40 mol %, more preferably 35 mol %.

[0022] When laminating with a flexible polyester resin, the diol component of the polyester resin used to further improve productivity and moldability has a content of ethylene glycol-derived components of 50 mol%, more preferably 60 mol%, and 100 mol%, more preferably 80 mol%, based on a diol component content of 100 mol%. The content of diol components other than ethylene glycol-derived components has a preferred lower limit of 0 mol%, more preferably 20 mol%, and 50 mol%, more preferably 40 mol%.

[0023] One or more components other than the component derived from terephthalic acid in the dicarboxylic acid component can be used, and one or more components other than the component derived from ethylene glycol in the diol component can be used.

[0024] Glass transition temperature (Tg) of polyester resin The glass transition temperature (Tg) of the polyester resin of the present invention is preferably 50 to 100° C., and more preferably 60 to 90° C. The glass transition temperature can also be adjusted by blending polyesters having different glass transition temperatures.

[0025] The glass transition temperature (Tg) of the polyester resin can be measured by a differential scanning calorimeter (DSC) according to a method in accordance with ISO3146:2000.

[0026] The base film for the backgrinding tape of the present invention has a moderate hardness because Layer A has the above-mentioned glass transition temperature (Tg), and can be preferably used as a backgrinding film to be used in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (about 25 μm).

[0027] In the base film of the present invention, the polyester resin contained in layer A may be a polyester resin having the above-mentioned composition alone, or two or more polyester resins having the above-mentioned composition may be used in combination.

[0028] As will be described later, the base film of the present invention has a structure in which Layer A and Layer B are adjacent to each other, and preferably has, as specific examples, a two-layer structure of Layer A / Layer B, a three-layer structure of Layer A / Layer B / Layer A, or a three-layer structure of Layer B / Layer A / Layer B.

[0029] When the layer A forms the front and back layers, the polyester resin may have the same composition in the front and back layers, or different compositions in the back layers. In order to effectively suppress problems such as curling of the film when the layer A forms the front and back layers, the polyester resin is more preferably of the same composition in the front and back layers.

[0030] The base film for the backgrinding tape of the present invention has the above-mentioned structure of Layer A, and therefore has appropriate hardness, and can be preferably used as a backgrinding film to be used in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (approximately 25 μm).

[0031] The base film for the backgrinding tape of the present invention has an appropriate hardness, which provides the effect of preventing warping of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer, and the effect of providing excellent releasability when peeling off the surface protection tape (adhesive tape for backgrinding).

[0032] (1-2) Layer B of the base film The layer B of the base film for the backgrinding tape of the present invention is made of a resin composition containing a soft polyester resin.

[0033] Soft polyester resin The flexible polyester resin preferably comprises, as structural units, 50% to 93% by mass of polyester units (A) each consisting of dicarboxylic acid units (a1) containing 70% by mole or more of a component derived from terephthalic acid and diol units (a2) containing 70% by mole or more of a component derived from ethylene glycol, and 7% to 50% by mass of polyester polyol units (B) each consisting of a component (b1) derived from hydrogenated dimer acid and a component (b2) derived from 1,4-butanediol.

[0034] The content of the polyester polyol units (B) in the total polymer is preferably 7% by mass to 50% by mass, more preferably 15% by mass to 35% by mass. Furthermore, since a flexible polyester resin in which the polyester polyol units (B) are randomly bonded in the polymer chain is obtained, the appearance is colorless and transparent or pale yellow and transparent.

[0035] Polyester unit (A) of soft polyester resin In the polyester unit (A) preferably used in the present invention, the dicarboxylic acid unit (a1) contains 70 mol % or more of a component derived from terephthalic acid. The entire amount of the dicarboxylic acid units may be components derived from terephthalic acid.

[0036] The dicarboxylic acid component other than the component derived from terephthalic acid may be contained in an amount of less than 30 mol %. Preferably, for example, isophthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,12-dodecanoic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. are used, and these components may be used alone or in combination of two or more.

[0037] In the polyester unit (A) preferably used in the present invention, the diol unit (a2) contains 70 mol % or more of a component derived from ethylene glycol. The entire amount of the diol unit may be a component derived from ethylene glycol. If the component derived from ethylene glycol is less than 70 mol %, for example, when blended with a polyethylene terephthalate resin and used in a film, compatibility may be poor.

[0038] The diol component other than the component derived from ethylene glycol may be contained in an amount of less than 30 mol %. Preferably, for example, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, etc. are used, and these may be used alone or in combination of two or more.

[0039] Polyester polyol unit (B) of soft polyester resin The polyester polyol unit (B) preferably used in the present invention is one in which the dicarboxylic acid unit is composed of a component (b1) derived from a hydrogenated dimer acid. Dimer acid is a dicarboxylic acid compound having 36 carbon atoms obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms, such as oleic acid or linoleic acid. A hydrogenated dimer acid is a dimer acid in which the unsaturated double bonds remaining after dimerization are saturated by hydrogenation, and the dicarboxylic acid unit of the polyester polyol unit (B) is composed of a component (b1) derived from this hydrogenated dimer acid.

[0040] Generally, hydrogenated dimer acid is obtained as a mixture of compounds having a linear branched structure, an alicyclic structure, etc., and the contents of these compounds vary depending on the production process, but the contents of these compounds are not particularly limited in the present invention.

[0041] The diol unit of the polyester polyol unit (B) preferably used in the present invention is composed of a component (b2) derived from 1,4-butanediol, and the terminals of the polyester polyol unit (B) are all hydroxyl groups derived from the component (b2) derived from 1,4-butanediol.

[0042] The polyester polyol unit (B) can be obtained by esterifying a component (b1) derived from a hydrogenated dimer acid with a component (b2) derived from 1,4-butanediol by a known method, but the molar ratio of each component during the reaction is adjusted so that the terminals are hydroxyl groups.

[0043] Intrinsic viscosity (IV) of soft polyester resins Intrinsic viscosity (IV) is one of the properties used to measure the viscosity of polyesters and is proportional to the molecular weight of the polyester.

[0044] The intrinsic viscosity (IV) of the flexible polyester resin of the present invention is preferably 0.6 dL / g to 1.2 dL / g, more preferably 0.65 dL / g to 0.9 dL / g, and even more preferably 0.7 dL / g to 0.8 dL / g. The intrinsic viscosity can also be adjusted by blending polyesters having different intrinsic viscosities. In the present invention, for example, a flexible polyester resin having an intrinsic viscosity (IV) of 0.75 dL / g is preferably used.

[0045] The intrinsic viscosity (IV) of the soft polyester resin can be measured, for example, in o-chlorophenol at a temperature of 35°C.

[0046] The base film for the backgrinding tape of the present invention has a moderate hardness because Layer B has the above-mentioned intrinsic viscosity (IV), and can be preferably used as a backgrinding film to be used in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (about 25 μm).

[0047] Glass transition temperature (Tg) of soft polyester resin The glass transition temperature (Tg) of the soft polyester resin of the present invention is preferably 10° C. to 40° C., more preferably 15° C. to 30° C. Polyesters having different glass transition temperatures The glass transition temperature can also be adjusted by blending the polymers.

[0048] The glass transition temperature (Tg) of the soft polyester resin can be measured by a differential scanning calorimeter (DSC) according to a method in accordance with ISO3146:2000.

[0049] The base film for the backgrinding tape of the present invention has a moderate hardness because Layer B has the above-mentioned glass transition temperature (Tg), and can be preferably used as a backgrinding film to be used in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (approximately 25 μm).

[0050] The soft polyester resin of the present invention may contain additives such as a heat stabilizer, an antioxidant, and an ultraviolet absorber, if necessary.

[0051] In the base film of the present invention, the soft polyester resin contained in layer B may be a soft polyester resin having the above-mentioned composition, or two or more soft polyester resins having the above-mentioned composition may be used in combination.

[0052] As will be described later, the base film of the present invention has a structure in which Layer A and Layer B are adjacent to each other, and preferably has, as specific examples, a two-layer structure of Layer A / Layer B, a three-layer structure of Layer A / Layer B / Layer A, or a three-layer structure of Layer B / Layer A / Layer B.

[0053] When Layer B forms the front and back layers, the soft polyester resin may have the same composition as the front and back layers, or different compositions. In order to effectively suppress problems such as curling of the film when Layer B forms the front and back layers, the soft polyester resin is more preferably of the same composition as the front and back layers.

[0054] The base film for the backgrinding tape of the present invention has a moderate hardness due to the B layer having the above-mentioned configuration, and can be preferably used as a backgrinding film to be used in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (approximately 25 μm).

[0055] The base film for the backgrinding tape of the present invention has an appropriate hardness, which provides the effect of preventing warping of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer, and the effect of providing excellent releasability when peeling off the surface protection tape (adhesive tape for backgrinding).

[0056] (1-3) Young's modulus of the base film The base film for the backgrinding tape of the present invention is a base film used to fix a semiconductor wafer in the backgrinding step, and exhibits physical properties suitable for this use.

[0057] The substrate film of the present invention has a Young's modulus at 23°C of 150 MPa to 1,500 MPa.

[0058] The base film of the present invention has a Young's modulus within the above-mentioned specific range, and therefore can be used as a back-grinding film in the back-grinding process of thin semiconductor wafers, and can effectively suppress warpage of the semiconductor wafers after the back-grinding process, even when the semiconductor wafers are ultra-thin (approximately 25 μm).

[0059] Young's modulus is measured in accordance with ISO527-1:2012 using, for example, a tensile testing machine "Strograph VE10" manufactured by Toyo Seiki Seisakusho, under the conditions of a sample width of 25 mm, a gauge length of 250 mm (strip test piece), and a tensile speed of 10 mm / min.

[0060] (1-4) Layer structure of the base film The substrate film for the backgrinding tape of the present invention has at least an A layer and a B layer.

[0061] The base film of the present invention has a structure in which Layer A and Layer B are adjacent to each other. Specific examples include a two-layer structure of Layer A / Layer B, a three-layer structure of Layer A / Layer B / Layer A, or a three-layer structure of Layer B / Layer A / Layer B.

[0062] In the substrate film of the present invention, at least either the side of layer A or the side of layer B may be the chuck table side or the wafer side during grinding (back grinding).

[0063] The thickness of the base film of the present invention is preferably about 60 μm to 250 μm, more preferably about 80 μm to 200 μm, and even more preferably about 90 μm to 150 μm. By adjusting the thickness of the base film for the backgrinding tape, it becomes possible to protect the semiconductor wafer from impact.

[0064] The thickness of the layer A made of a resin composition containing a polyester-based resin is preferably about 5 μm to 100 μm, and more preferably about 10 μm to 50 μm.

[0065] The thickness of layer B made of a resin composition containing a soft polyester-based resin is preferably about 10 μm to 100 μm, and more preferably about 20 μm to 80 μm.

[0066] (2) Manufacturing method of base film for backgrind tape The base film for the backgrind tape of the present invention has a multilayer structure and can be formed by extrusion using a T-die or annular die, calendering, etc. In consideration of the thickness accuracy of the base film, extrusion using a T-die is preferred.

[0067] The extrusion method using a T-die will be explained.

[0068] The resin composition is preferably prepared by dry blending or melt kneading. Additives may be added to the resin composition constituting the layer as needed.

[0069] The resin composition is preferably fed into a temperature-controlled screw extruder, extruded into a film form through a T-die at 180 to 350°C, cooled while passing through a cooling roll at about 20 to 150°C (preferably about 30 to 70°C), and taken up substantially without stretching (extrusion molding).

[0070] When the base film is used as a base film for a backgrinding tape, shrinkage of the film due to stretching during the backgrinding process can be suppressed by not stretching the base film substantially during the take-up process. This "substantially not stretching" includes no stretching or slight stretching to an extent that does not affect the warping of the wafer during backgrinding. Usually, the film is stretched to an extent that does not cause sagging during take-up.

[0071] (3) Back grinding tape The base film of the present invention is a base film used to fix a semiconductor wafer, and is preferably used as a base film for a backgrinding tape. A backgrinding tape can be produced by forming a pressure-sensitive adhesive layer and a release film on the surface of this base film for a backgrinding tape.

[0072] The backgrinding tape (film) of the present invention preferably has an adhesive layer and a release film on the wafer-side surface of the base film for the backgrinding tape.

[0073] A known adhesive is coated on one surface of the base film for the backgrind tape to form an adhesive layer, the thickness of which is preferably about 10 μm to 200 μm.

[0074] The adhesive preferably used is a pressure-sensitive adhesive, an acrylic adhesive, a rubber-based adhesive, etc. Considering the adhesiveness to the semiconductor wafer and the cleanability of the semiconductor wafer after peeling with ultrapure water or an organic solvent such as alcohol, it is preferable to use an acrylic adhesive having an acrylic polymer as the base polymer.

[0075] The backgrinding tape is manufactured by forming an adhesive layer on the surface of a base film for the backgrinding tape, and then providing a release film thereon. The thickness of the release film is preferably about 10 μm to 200 μm.

[0076] By including the base film of the present invention, the backgrinding tape can be preferably used as a backgrinding film used in the backgrinding process of thin semiconductor wafers in relation to ultrathinning of semiconductor wafers (approximately 25 μm). The backgrinding tape exhibits the effect of preventing warping of the semiconductor wafer during the backgrinding process of thin semiconductor wafers. The backgrinding tape exhibits the effect of excellent releasability when peeling off a surface protection tape (adhesive tape for backgrinding). [Example]

[0077] The present invention will be described in more detail below with reference to examples.

[0078] The present invention is not limited to these examples.

[0079] (1) Raw material for the base film of backgrinding tape Pes-1 Polyester Resin 100 mol% terephthalic acid, Ethylene glycol 70 mol% + 1,4-cyclohexanedimethanol 30 mol% Glass transition temperature (Tg) 80℃ Pes-S Soft polyester resin Intrinsic viscosity (IV) 0.75dl / g Glass transition temperature (Tg) 20℃ (2) Manufacturing of base film for backgrind tape A base film for a backgrind tape was prepared by blending resin compositions with the components and compositions to form the layer structure (three layers) shown in Table 1. The resin compositions constituting each layer were fed into respective extruders adjusted to 220°C, extruded through a T-die at 220°C in the order of three layers, laminated, and co-extruded onto a chill roll through which cooling water at 30°C was circulated, yielding a flat five-layer film.

[0080] (3) Evaluation of the base film for backgrinding tape The Young's modulus of the substrate film was measured in accordance with ISO527-1:2012 by cutting a sample having a length of 400 mm, a width of 25 mm, and a gauge length of 250 mm (strip test piece) to prepare a test piece, and measuring it at a tensile speed of 10 mm / min using a Strograph VE-10 manufactured by Toyo Seiki Seisaku-sho, Ltd. For each example and comparative example, the Young's modulus was measured using seven test pieces (n=7) in both the MD and TD directions, and the average value was calculated.

[0081] [Table 1]

[0082] The substrate film for backgrinding tape of the present invention has an appropriate hardness and can therefore be preferably used as a backgrinding tape to be used in the backgrinding process of thin semiconductor wafers in order to make semiconductor wafers ultra-thin (about 25 μm).

[0083] The base film for the backgrinding tape of the present invention has an appropriate hardness, and therefore when used as a backgrinding tape, it exhibits the effects of preventing warping of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer, and of providing excellent releasability when peeling off the surface protection tape (adhesive tape for backgrinding).

Claims

1. A substrate film for a backgrind tape, comprising: It has at least layer A and layer B, The thickness of the base film is 60 μm or more and 250 μm or less, The thickness of the layer B is 20 μm or more and 100 μm or less, the layer A is made of a resin composition containing a polyester-based resin, the layer B is made of a resin composition containing a soft polyester-based resin, The glass transition temperature (Tg) of the polyester resin is 50°C or higher and 100°C or lower, The glass transition temperature (Tg) of the soft polyester resin is 10°C or higher and 40°C or lower. Base film for backgrind tape.

2. 2. The substrate film for a backgrinding tape according to claim 1, wherein the soft polyester resin has polyester units and polyester polyol units.

3. 3. The substrate film for a backgrinding tape according to claim 1, wherein the Young's modulus at 23°C is 150 MPa or more and 1500 MPa or less.

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