JP2010225681A - Back grinding film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate film for back grinding having excellent dimension stability that hardly causes warpage on a thin semiconductor wafer in a back grinding process of the thin semiconductor wafer, and to provide a back grinding film. <P>SOLUTION: The substrate film for back grinding includes at least three layers including front and rear layers and an intermediate layer. The intermediate layer is made of a resin composition containing 0-60 wt.% polypropylene-based resin and 40-100 wt.% olefin-based thermoplastic elastomer (A), and the front and rear layers are made of (a) resin composition containing 40-100 wt.% polypropylene-based resin and 0-60 wt.% olefin-based thermoplastic elastomer (B), or (b) a resin composition containing 60-100 wt.% polypropylene-based resin and 0-40 wt.% copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon or its hydrogenation object. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a back grind film that is used by being attached to a semiconductor wafer when the back surface of the semiconductor wafer is ground (hereinafter referred to as “back grind”).

  When manufacturing a semiconductor, after forming a circuit on the surface of a semiconductor wafer by ion implantation, etching, etc., the surface opposite to the circuit formation surface of the wafer is ground with a grinder to make the wafer a predetermined thickness. In general, a back grinding process is performed.

  In order to prevent damage to the semiconductor wafer and to facilitate grinding during back grinding of this semiconductor wafer, a surface protective film (back grind film) for back grinding is attached to the circuit forming surface (front surface) of the semiconductor wafer. A way to protect is taken.

  The back grind film is heated by frictional heat during back grinding, and is cooled to room temperature after the back grinding is completed. It is known that a conventionally used back grind film is warped on the semiconductor wafer side because it shrinks in the cooling process after the back grind is completed.

  In recent years, due to the ultra-thin semiconductor wafer (less than 50 μm), the semiconductor wafer attached following the warp of the back grind film is likely to be warped, and the chip of the semiconductor wafer chip is eventually generated. (See, for example, FIG. 1). Therefore, there has been a demand for a back grind film excellent in dimensional stability that hardly warps during a back grind process of a thin semiconductor wafer.

  In order to solve the problem of warpage of the wafer, various back grind films have been developed. For example, an ethylene-vinyl alcohol copolymer (EVA) film is laminated on an adhesive layer, and further an adhesive and polyethylene terephthalate. A protective sheet for processing a semiconductor wafer obtained by laminating a (PET) film is known (for example, see Patent Document 1). However, in the protective sheet described in Patent Document 1, it is proposed that a layer having a very low tensile elastic modulus is provided as an intermediate layer to alleviate slight dimensional changes of the base material and suppress warpage of the wafer. However, when a dimensional change that cannot be alleviated occurs, there is a problem that warpage increases.

  Furthermore, an adhesive film for protecting a semiconductor wafer surface (for example, refer to Patent Document 2) or a diene block, in which an adhesive is applied to one surface of a base film made of a polyolefin copolymer such as an ethylene-vinyl acetate copolymer. A back grind tape made of an elastomer containing at least one selected from a hydrogenated polymer and a polar group-modified olefin polymer is known (for example, see Patent Document 3). However, these patent documents do not sufficiently study the case where they are used for thin semiconductor wafers of about 50 μm, and as a result, the protective materials of these literatures suppress warpage of thin semiconductor wafers. Was not enough.

JP 2006-128292 A JP 2006-261482 A JP 2005-191296 A

  The present invention provides a substrate film for back grinding that has excellent dimensional stability in which warpage of the semiconductor wafer is unlikely to occur in a back grinding process of a thin semiconductor wafer and can suppress blocking during film winding, and the back grinding An object of the present invention is to provide a back grind film including a substrate film for use.

  As a result of intensive studies to solve the above problems, the present inventor is a back-grind base film comprising at least three layers including front and back layers and an intermediate layer, and the intermediate layer is formed of polypropylene resin 0 to The resin composition comprises 60% by weight and 40 to 100% by weight of an olefinic thermoplastic elastomer, and the front and back layers are (a) 40 to 100% by weight of a polypropylene resin and 0 to 60 of an olefinic thermoplastic elastomer. A resin composition containing 5% by weight, or (b) a polypropylene resin 60-100% by weight, and a copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon or hydrogenated product thereof, 0-40% by weight. The base film for back grinding made of the resin composition has excellent dimensional stability in the back grinding process, and when the film is wound Kicking blocking has been found that can be suppressed. Based on this knowledge, further studies have been made and the present invention has been completed.

That is, the present invention provides the following back-grind base film, a back-grind film containing the base film, a semiconductor wafer back-grind method, and a back-grind base film manufacturing method.
Item 1. A base film for back grinding comprising at least three layers including front and back layers and an intermediate layer,
The intermediate layer comprises a resin composition containing 0 to 60% by weight of a polypropylene resin and 40 to 100% by weight of an olefinic thermoplastic elastomer (A), and
The base film for back grinds whose front and back layers are composed of the following resin composition (a) or resin composition (b).
Resin composition (a):
A resin composition comprising 40 to 100% by weight of a polypropylene resin and 0 to 60% by weight of an olefinic thermoplastic elastomer (B),
Resin composition (b):
A resin composition comprising 60 to 100% by weight of a polypropylene resin and 0 to 40% by weight of a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated product thereof.
Item 2. 2. The bag according to item 1, wherein the olefinic thermoplastic elastomers (A) and (B) are elastomers having a sea-island structure in which a copolymer rubber of propylene and ethylene is finely dispersed in a polypropylene resin. Grinding base film.
Item 3. The olefin-based thermoplastic elastomer (A) has an elution amount at 0 ° C. in the temperature rising elution fractionation between 0 ° C. and 140 ° C. using o-dichlorobenzene as a solvent, and is 60 to 80 wt. Item 3. The backgrind substrate film according to Item 1 or 2, which is%.
Item 4. Item 4. The backgrind substrate film according to any one of Items 1 to 3, which has a thickness of 50 to 300 µm.
Item 5. The back grind film which has an adhesive layer and a release film on the surface of the base film for back grinds in any one of said items 1-4.
Item 6. 6. A backgrinding method for a semiconductor wafer, comprising attaching the backgrind film according to the above item 5 to the surface of a semiconductor wafer, grinding the back surface of the semiconductor wafer, and removing the backgrind film from the semiconductor wafer.
Item 7. A method for producing a substrate film for backgrind, characterized by coextrusion molding in the order of surface layer / intermediate layer / back layer,
The intermediate layer comprises a resin composition containing 0 to 60% by weight of a polypropylene resin and 40 to 100% by weight of an olefinic thermoplastic elastomer (A), and
The manufacturing method of the base film for back grinds whose front and back layers consist of the following resin compositions (a) or resin compositions (b).
Resin composition (a):
A resin composition comprising 40 to 100% by weight of a polypropylene resin and 0 to 60% by weight of an olefinic thermoplastic elastomer (B),
Resin composition (b):
A resin composition comprising 60 to 100% by weight of a polypropylene resin and 0 to 40% by weight of a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated product thereof.

  The substrate film for back grinding according to the present invention is excellent in dimensional stability because the semiconductor wafer is hardly warped in the back grinding process of a thin semiconductor wafer. Moreover, blocking at the time of winding the base film can be effectively suppressed.

It is the figure which showed typically that the curvature generate | occur | produces also in a semiconductor wafer and the chip | tip generate | occur | produces following the curvature of the base film for back grinding. It is the figure which showed typically the measuring method of the curvature of the base film for back grinding.

1. Backgrind Base Film The backgrind base film of the present invention comprises at least three layers including a front and back layer and an intermediate layer, and the front and back layers and the intermediate layer are formed from the resin composition shown below. Here, the front and back layers indicate both the front and back layers formed on the front and back surfaces of the intermediate layer.

The intermediate layer is composed of a resin composition containing 0 to 60% by weight of a polypropylene resin and 40 to 100% by weight of an olefinic thermoplastic elastomer (A),
The front and back layers
Resin composition (a): Resin composition containing 40 to 100% by weight of polypropylene resin and 0 to 60% by weight of olefinic thermoplastic elastomer (B), or resin composition (b): 60 to 100% of polypropylene resin %, And a copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon or a hydrogenated product thereof in an amount of 0 to 40% by weight.

  When the resin composition (a) is used as the front and back layers, the back-grind base film 1 is used, and when the resin composition (b) is used as the front and back layers, the back-grind base film 2 is used as follows. The composition of the backgrind base films 1 and 2 will be described in detail.

1.1 Back Grinding Base Film 1
(1) Intermediate layer The intermediate layer of the substrate film 1 for back grind is a resin composition (hereinafter referred to as an intermediate layer resin) containing 0 to 60% by weight of a polypropylene resin and 40 to 100% by weight of an olefinic thermoplastic elastomer (A). Called composition).
(1-1) Polypropylene resin The polypropylene resin (PP) used in the present invention is preferably crystalline. Examples of the crystalline propylene-based resin include a propylene homopolymer or a random or block copolymer of propylene and a small amount of α-olefin and / or ethylene.

  When the polypropylene resin is a copolymer, the copolymerization ratio of α-olefin and / or ethylene is preferably the ratio shown below.

  In the case of a random copolymer, the α-olefin and / or ethylene other than propylene is generally 10% by weight or less in total and preferably 0.5 to 7% by weight in the copolymer. In the case of a block copolymer, the α-olefin and / or ethylene other than propylene is generally 40% by weight or less, preferably 1 to 40% by weight, more preferably in the copolymer. Is 1 to 25% by weight, more preferably 2 to 20% by weight, particularly preferably 3 to 15% by weight.

  These polypropylene polymers may be a mixture of two or more polymers.

  As an index of the crystallinity of polypropylene, for example, a melting point, a heat of crystal fusion, and the like are used. The melting point is preferably 120 to 176 ° C., and the heat of crystal fusion is preferably 60 to 120 J / g.

  The polypropylene-based resin can employ multistage polymerization by combining a gas phase polymerization method, a bulk polymerization method, a solvent polymerization method and any combination thereof, and there is no particular limitation on the number average molecular weight of the polymer, Preferably, it is adjusted to 10,000 to 1,000,000.

  As this crystalline polypropylene resin, in accordance with JIS K7210, MFR (melt flow rate) when measured at a temperature of 230 ° C. and a load of 21.18 N is generally 0.5 to 20 g / 10 min. Preferably it is 0.5-10 g / 10min.

(1-2) Olefin-based thermoplastic elastomer (A)
The olefinic thermoplastic elastomer (A) used in the present invention preferably contains a polypropylene resin component and a copolymer rubber component of propylene and ethylene. In the polypropylene resin (matrix phase), propylene and More preferably, it is an elastomer having a sea-island structure in which a copolymer rubber with ethylene is finely dispersed.

  In the olefinic thermoplastic elastomer (A), the polypropylene resin component is preferably 10 to 40% by weight, and more preferably 20 to 30% by weight. The copolymer rubber component of propylene and ethylene is preferably 60 to 90% by weight, and more preferably 70 to 80% by weight.

(I) Polypropylene resin component The polypropylene resin is preferably a propylene homopolymer having an isotactic index of 90% or more, and more preferably a propylene homopolymer having 95% or more. If the isotactic index of the polypropylene resin is less than 90%, the heat resistance of the olefinic thermoplastic elastomer (A) tends to be inferior.

(Ii) Copolymer rubber component of propylene and ethylene The copolymerization ratio of propylene and ethylene is not particularly limited and can be appropriately determined. As an example, propylene / ethylene = 10-90 / 90-10 (weight%) etc. can be mentioned, for example.

  The copolymer rubber may contain a copolymer component in addition to propylene and ethylene. Examples of the copolymer component include 1,4-hexadiene, 5-methyl 1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5- Non-conjugated dienes such as butylidene-2-norbornene and 2-isopropenyl-5-norbornene can be mentioned. These addition amounts are not particularly limited, and can be added within a range not impairing the effects of the present invention.

  In the olefinic thermoplastic elastomer (A) used in the present invention, the amount of elution at 0 ° C. in the temperature rising elution fractionation between 0 ° C. and 140 ° C. using o-dichlorobenzene as a solvent is based on the total amount of elution. It is preferable that it is 60 to 80 weight%. It is preferable that the elution amount at 0 ° C. is within this range because warpage can be effectively suppressed.

  Here, temperature rising elution fractionation (TREF) is a known analysis method. As a specific measuring method, for example, a method disclosed in JP-A-2003-7654 can be exemplified.

(Iii) Method for Producing Olefin-Based Thermoplastic Elastomer (A) The method for producing the olefin-based thermoplastic elastomer (A) used in the present invention is not particularly limited and may be any known method. An example of a manufacturing method is shown below.

  In the first stage, propylene is supplied to the reaction vessel, the temperature is 50 to 150 ° C. (preferably 50 to 100 ° C.), and the partial pressure of propylene is 0.5 to 4.5 MPa (preferably 1. The polymerization of the propylene homopolymer is carried out under the condition of 0 to 3.5 MPa).

  Subsequently, in the second stage, propylene and ethylene are supplied, and in the presence of a catalyst, the temperature is 50 to 150 ° C. (preferably 50 to 100 ° C.), and propylene and ethylene partial pressures are each 0.3 to 4.5 MPa (preferably Is produced by polymerizing a propylene-ethylene copolymer under the conditions of 0.5 to 3.5 MPa).

(1-3) Intermediate Layer Resin Composition The intermediate layer resin composition used for the base film 1 for back grind of the present invention comprises 0 to 60% by weight of the polypropylene resin and 40 to 50% of the olefin thermoplastic elastomer (A). 100% by weight, preferably 10 to 50% by weight of the polypropylene resin and 50 to 90% by weight of the olefinic thermoplastic elastomer (A), and 20 to 40% by weight of the polypropylene resin and the olefinic resin. More preferably, it contains 60 to 80% by weight of the thermoplastic elastomer (A). It is preferable that the composition of the resin composition for an intermediate layer is within the above range because the dimensional stability in the back grinding process of the thin semiconductor wafer is excellent.

  In addition to the polypropylene resin or the olefinic thermoplastic elastomer (A), the resin composition may contain known additives such as antioxidants and weathering agents. Although it does not specifically limit as the addition range, It is preferable that it is 10 weight% or less in a resin composition total solid, and can mention the range of 5 to 1 weight%.

(2) Front and back layers In the present invention, the front and back layers may be layers composed of the same resin composition or may be layers composed of different resin compositions. In the back grinding process, it is preferable that the surface layer and the back layer are made of the same resin composition from the viewpoint that the semiconductor wafer is hardly warped and has excellent dimensional stability.

  In this specification, the resin composition for forming the surface layer is the resin composition for the surface layer, and the resin composition for forming the back layer is the resin composition for the back layer. Moreover, these may be put together and it may be called the resin composition for front and back layers.

  The front and back layer resin composition of the base film 1 for back grind is a resin composition (a) containing 40 to 100% by weight of a polypropylene resin and 0 to 60% by weight of an olefinic thermoplastic elastomer (B).

  Examples of the polypropylene resin include the same ones that can be used in the intermediate layer, and the olefin thermoplastic elastomer (B) is the same as the olefin thermoplastic elastomer (A) used in the intermediate layer. Can be mentioned.

  Since the polypropylene-based resin used in the present invention has excellent heat resistance, it has sufficient resistance against heating due to frictional heat during back grinding.

  The resin composition for front and back layers used for the base film 1 for back grind of the present invention contains 40 to 100% by weight of a polypropylene resin and 0 to 60% by weight of an olefinic thermoplastic elastomer (B). Preferably, the resin contains 60 to 100% by weight of the resin and 0 to 40% by weight of the olefinic thermoplastic elastomer (B), and 70 to 100% by weight of the polypropylene resin and 0 to 30% by weight of the olefinic thermoplastic elastomer (B). More preferably. It is preferable that the composition of the resin composition for the front and back layers is within the above range since blocking at the time of winding the base film can be suppressed.

  Moreover, the said resin composition for front and back layers can contain antioxidant, a weather resistance agent, etc. other than the said polypropylene resin and an olefin type thermoplastic elastomer (B). Although it does not specifically limit as the addition range, It is preferable that it is 10 weight% or less in a resin composition total solid part, and the range of 5 to 1 weight% can be mentioned.

1.2 Backgrind base film 2
(1) Intermediate layer The intermediate layer in the back-grind base film 2 is the same as the intermediate layer of the back-grind base film 1.

(2) Front and back layers Also in the base film 2 for back grind, the front layer and the back layer may be layers composed of a resin composition having the same composition, or may be layers composed of different resin compositions. In the back grinding process of a thin semiconductor wafer, the surface layer and the back layer are preferably made of the same resin composition from the viewpoint that the semiconductor wafer is hardly warped and has excellent dimensional stability.

  The resin composition for the front and back layers of the base film 2 for back grind is a polypropylene resin 60 to 100% by weight, and a copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon or hydrogenated product thereof 0 to 40% by weight. It is a resin composition (b) containing this.

(2-1) Polypropylene resin Examples of the polypropylene resin include the same resins as those used for the resin composition for the intermediate layer of the substrate film 1 for back grinding.

(2-2) Copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon or hydrogenated product Vinyl aromatic hydrocarbon is an aromatic hydrocarbon having at least one vinyl group, for example, Styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N, N-dimethyl-p-aminoethylstyrene, N, N-diethyl-p-aminoethylstyrene, etc. Can do. These can be used individually by 1 type or in mixture of 2 or more types. Among these, styrene is preferable.

  The conjugated diene hydrocarbon is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1, Examples include 3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and the like. These can be used individually by 1 type or in mixture of 2 or more types. Of these, butadiene is preferred.

  For the resin composition for the front and back layers of the substrate film 2 for back grind, a copolymer of the vinyl aromatic hydrocarbon and the conjugated diene hydrocarbon is used, and a hydrogenated product of the copolymer is used. Is preferable from the viewpoint of compatibility with the polypropylene resin contained in the resin composition for the front and back layers. In addition, the film tends to become brittle due to oxidative degradation caused by the presence of double bonds in the conjugated diene hydrocarbon, but hydrogenated products are preferred because the oxidative degradation can be prevented.

  In the hydrogenated vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer, the double bond derived from the conjugated diene hydrocarbon is saturated by hydrogenation (for example, nickel catalyst) by a known method. It is preferable. Thereby, in addition to the above effects, a more stable resin excellent in heat resistance, chemical resistance, durability and the like can be obtained, which is preferable.

  The hydrogenation rate of the hydrogenated product of the vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer is preferably 85% or more of the double bond derived from the conjugated diene hydrocarbon in the copolymer, more preferably. Is 90% or more, more preferably 95% or more. This hydrogenation rate can be measured using a nuclear magnetic resonance apparatus (NMR).

  The content of vinyl aromatic hydrocarbon units in a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated product thereof is usually 5 to 40% by weight, preferably 5 to 15% by weight. . Moreover, content of a conjugated diene hydrocarbon unit is 60 to 95 weight% normally, Preferably it is 85 to 95 weight%. The content of styrene monomer units is measured using an ultraviolet spectrophotometer or a nuclear magnetic resonance apparatus (NMR), and the content of diene monomer units is measured using a nuclear magnetic resonance apparatus (NMR). be able to.

  The hardness (JISK6253 durometer type A) of the vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer or a hydrogenated product thereof is usually about 40 to 90, preferably about 55 to 85.

  The specific gravity (ASTMD 297) of the vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer or hydrogenated product thereof is usually about 0.85 to 1.0, and MFR (ASTM D1238: 230 ° C., 21.2 N). ) Is usually about 2 to 6 g / 10 min.

  The weight average molecular weight (Mw) of the vinyl aromatic hydrocarbon-conjugated diene hydrocarbon copolymer or the hydrogenated product thereof is, for example, usually about 100,000 to 500,000, preferably about 150,000 to 300,000. Good. The weight average molecular weight can be measured using commercially available standard gel permeation chromatography (GPC).

(2-3) Front and Back Layer Resin Composition The front and back layer resin composition (b) used for the back grind base film 2 of the present invention is conjugated with polypropylene resin 60 to 100% by weight and vinyl aromatic hydrocarbon. A copolymer of a diene hydrocarbon or a hydrogenated product thereof containing 0 to 40% by weight, a polypropylene resin 65 to 90% by weight, and a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon It is preferable to contain 10 to 35% by weight of the hydrogenated product, 70 to 85% by weight of the polypropylene resin, and a copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon or 15 to 30% by weight of the hydrogenated product. It is more preferable to contain. It is preferable that the composition of the resin composition for the front and back layers is within the above range because the dimensional stability in the back grinding process of the thin semiconductor wafer is excellent and blocking at the time of winding the base film can be suppressed.

  In addition to the polypropylene resin, a copolymer of vinyl aromatic hydrocarbon and conjugated diene hydrocarbon, or a hydrogenated product thereof, the resin composition for the front and back layers contains an antioxidant, a weather resistance agent, and the like. be able to. Although it does not specifically limit as the addition range, It is preferable that it is 10 weight% or less in a resin composition solid content, and the range of 5 to 1 weight% can be mentioned.

1.3 Layer Structure The back-grind base film (back-grind base films 1 and 2) of the present invention comprises at least three layers including the front and back layers and the intermediate layer as described above. Specifically, it is a film laminated in the order of surface layer / intermediate layer / back layer. Moreover, it is not restricted to the said 3 layers, In the range which does not impair the effect of this invention, layers other than the above (for example, adhesive layer etc.) may be included.

  The thickness ratio of the surface layer / intermediate layer / back layer is preferably 1/1/1 to 1/40/1, more preferably 1/1/1 to 1/10/1, and 1/1. More preferably, the ratio is / 1 to 1/6/1. When the thickness ratio is within the above range, molding defects due to a difference in melt viscosity at the time of multilayering are less likely to occur, and the ratio of the entire intermediate layer is increased in the back grinding process of a thin semiconductor wafer. This is preferable because the semiconductor wafer is less likely to warp.

  The total thickness of the backgrind base film of the present invention is not particularly limited as long as it can be easily wound in a roll shape, but is preferably 80 to 230 μm, for example, 100 to 180 μm. More preferably.

  The thickness of the intermediate layer is preferably 60 to 220 μm, and more preferably 80 to 150 μm. It is preferable that the thickness of the intermediate layer is within this range because excellent dimensional stability can be obtained.

  The thickness of the front and back layers is preferably 5 to 70 μm, and more preferably 5 to 50 μm.

  The backgrind base films 1 and 2 of the present invention are both excellent in dimensional stability, in which the semiconductor wafer is hardly warped in the backgrinding process of a thin semiconductor wafer, and further, blocking when the base film is wound. Can be effectively suppressed.

2. Method for Producing Back Grinding Base Film The method for producing the back grinding base film of the present invention comprises the above-mentioned surface layer resin composition, intermediate layer resin composition, and back layer resin composition. The method includes a step of coextrusion molding in the order of the layers, and as a coextrusion molding method, a conventionally used method such as an extrusion method using a T die or an annular die can be appropriately used. Among these, the extrusion method using a T die is preferable from the viewpoint of the thickness accuracy of the base film.

  Hereinafter, an extrusion method using a T die will be described.

  Using a plurality of extruders, each raw resin is charged into each extruder, and a roll-shaped multilayer substrate film is obtained in the same manner as described above. Specifically, in the case of forming a three-layer back-grind base film composed of a surface layer / intermediate layer / back layer, the raw material resin for each of the above layers is used.

  The raw material resin composition can be prepared by dry blending or melt-kneading. The raw material resin composition is supplied to a screw type extruder, extruded from a T die into a film at 180 to 225 ° C., cooled while passing through a cooling roll at 50 to 70 ° C., and taken substantially unstretched. . Alternatively, the raw material resin may be once obtained as pellets and then extruded as described above.

  The reason why the film is substantially unstretched at the time of taking is to suppress shrinkage of the film due to stretching in the back grinding process. This substantially non-stretching includes non-stretching or slight stretching that does not affect the warpage of the wafer during back grinding. In general, the film may be pulled to such an extent that no sagging occurs when the film is taken up.

  As a method of providing the pressure-sensitive adhesive layer and the release film on the surface of the substrate film for back grinding obtained above, a known method can be adopted. The back grind film is usually obtained in a rolled state cut into a tape shape.

3. Back Grind Film The back grind film of the present invention has a pressure-sensitive adhesive layer and a release film on the surface of the above-mentioned substrate film for back grind. More specifically, a known pressure-sensitive adhesive is coated on one surface of the above-described back-grind base film to form a pressure-sensitive adhesive layer, and a release film is further provided on the pressure-sensitive adhesive layer. Grind film is produced.

  The thickness of the pressure-sensitive adhesive layer is, for example, about 10 to 200 μm, and the thickness of the release film may be, for example, about 10 to 100 μm.

  As the pressure-sensitive adhesive component used in the pressure-sensitive adhesive layer, a known pressure-sensitive adhesive can be used without particular limitation. For example, the pressure-sensitive adhesive component described in JP 2006-128292 A can be used. A known release film is also used.

  As the pressure-sensitive adhesive, for example, a commonly used pressure-sensitive pressure-sensitive adhesive can be used, and an appropriate pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive can be used. Among these, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable from the viewpoints of adhesion to a semiconductor wafer and cleanability of the semiconductor wafer after peeling with an organic solvent such as ultrapure water or alcohol.

  Specifically, an acrylic polymer selected from a homopolymer and a copolymer having (meth) acrylic acid ester as a main constituent monomer unit, a copolymer with another functional monomer, and Mixtures of these polymers are used. For example, (meth) acrylic acid ester includes ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, Glycidyl acrylate, 2-hydroxyethyl acrylate and the like can be preferably used.

  The back grind film is usually obtained in a rolled state cut into a tape shape.

4). Semiconductor wafer back grinding method The back grinding method of the present invention attaches a back grinding film to the front surface (circuit surface) of the semiconductor wafer, grinds the back surface of the semiconductor wafer, and removes the back grinding film from the semiconductor wafer.

  Specifically, the release film is peeled off from the pressure-sensitive adhesive layer of the back grind film, the surface of the pressure-sensitive adhesive layer is exposed, and the semiconductor wafer on the side where the integrated circuit is incorporated through the pressure-sensitive adhesive layer Stick to the surface. The thickness of the semiconductor wafer before grinding is usually about 300 to 1000 μm. Next, the semiconductor wafer is fixed and the back surface thereof is ground by a conventional method. Although the thickness of the semiconductor wafer after grinding is selected according to the size of the chip to be obtained, the type of circuit, the application, etc., it is, for example, about 50 to 200 μm. After the back surface grinding is completed, a chemical etching process or a CMP (mechanochemical polishing) process may be added as necessary. Thereafter, the back grind film is peeled (removed). If necessary, after the back grind film is peeled off, the surface of the semiconductor wafer is subjected to a cleaning process such as water cleaning or plasma cleaning.

  Hereinafter, the present invention will be described in more detail using Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1 to 5, Comparative Examples 1 and 2
(Manufacture of resin composition)
Each raw material shown in Table 1 was dry blended at the blending ratio shown in Table 1 to obtain a resin composition. In addition, the raw material described in Table 1 is as follows.

<Polypropylene resin>
Novatec PP FX4E (MFR (JIS K7210, 230 ° C., load 21.18 N): 5.3 g / 10 min, peak based on crystal melting: 130 ° C., 95 J / g, peak based on crystallization: 75 ° C., 95 J / g, manufactured by Nippon Polypro Co., Ltd.).

<Olefin-based thermoplastic elastomer>
Zelas ZT813 (manufactured by Mitsubishi Chemical Corporation).

(Manufacture of substrate film for back grinding)
The resin composition for the surface layer, the resin composition for the intermediate layer, and the resin composition for the back layer were supplied in this order to a multilayer extruder having a barrel temperature of 180 to 220 ° C. It was extruded from a 230 ° C. T-die, cooled and solidified with a take-up roll having a set temperature of 40 ° C., and wound up in an unstretched state. The thickness of each layer of the obtained film is as shown in Table 1.

Examples 6 to 9, Comparative Examples 3 and 4
(Manufacture of resin composition)
Each raw material shown in Table 2 was dry blended at a blending ratio shown in Table 2 to obtain a resin composition. In addition, the raw material described in Table 2 is as follows.

<Polypropylene resin>
Novatec PP FX4E (MFR (JIS K7210, 230 ° C., load 21.18 N): 5.3 g / 10 min, peak based on crystal melting: 130 ° C., 95 J / g, peak based on crystallization: 75 ° C., 95 J / g, manufactured by Nippon Polypro Co., Ltd.).

<Olefin-based thermoplastic elastomer>
Zelas ZT813 (manufactured by Mitsubishi Chemical Corporation).

<SEBS>
Styrene-butadiene block copolymer hydrogenated product, MD6945 (trade name), manufactured by Kraton Polymer Japan Co., Ltd.

(Manufacture of substrate film for back grinding)
The resin composition for the surface layer, the resin composition for the intermediate layer, and the resin composition for the back layer were supplied in this order to a multilayer extruder having a barrel temperature of 180 to 220 ° C. It was extruded from a 230 ° C. T-die, cooled and solidified with a take-up roll having a set temperature of 40 ° C., and wound up in an unstretched state. The thickness of each layer of the obtained film is as shown in Table 2.

  About the film obtained in Examples 1-9 and Comparative Examples 1-4, it evaluated by the following evaluation method. The results are shown in Tables 1 and 2.

Evaluation method ( evaluation of warpage)
As an alternative to wafers, polyimide (PI) tape (Scotch polyimide tape No. 5434, thickness 53 μm, Sumitomo 3M Co., Ltd.) that is as dimensionally stable as semiconductor wafers in the temperature range from room temperature (25 ° C.) to 50 ° C. )).

  The PI tape (width 2 cm x length 14 cm) was pasted on the produced back grind base film, cut out as a sample, sandwiched between two stainless steel plates (thickness 2 mm), and heated in an oven set at 50 ° C. for 10 minutes. . Thereafter, the sample was taken out and allowed to cool at room temperature (25 ° C.) for 10 minutes, and the warpage caused by the shrinkage of the film was measured.

  The amount of warping is the height of the end of the PI tape that is most floated from the horizontal plane with the back-grind base film placed on the horizontal plane with the PI tape affixed to the back-grind base film. (Mm) was measured (FIG. 2). If the measured value is 3 mm or less, there is no problem of warping of the semiconductor wafer and it is a practical level.

(Evaluation of blocking)
Two measurement samples were cut out from an arbitrary location of the obtained base film to a size of 100 mm × width 30 mm (the sample was cut out with the film flow direction as the vertical direction and the width direction as the horizontal direction). . Two measurement samples are placed so that the same surface (surface in contact with the cooling roll) overlaps with an area of 40 mm × 30 mm wide, and the overlapped measurement samples are sandwiched between two glass plates, from above A 600 g weight was placed on the part where the samples overlapped. This was placed in a constant temperature bath at 40 ° C. and left for 7 days. Seven days later, the sample taken out from the thermostatic chamber was set in a peel tester (Peeling TESTER HEIDON-17) manufactured by Shinto Kagaku Co., Ltd., and the 180 degree shear peel strength was measured at a pulling rate of 200 mm / min. When the measured value was 4.9 N / 10 mm or less, no blocking was considered.

Claims (7)

A base film for back grinding comprising at least three layers including front and back layers and an intermediate layer,
The intermediate layer comprises a resin composition containing 0 to 60% by weight of a polypropylene resin and 40 to 100% by weight of an olefinic thermoplastic elastomer (A), and
The base film for back grinds whose front and back layers are composed of the following resin composition (a) or resin composition (b).
Resin composition (a):
A resin composition comprising 40 to 100% by weight of a polypropylene resin and 0 to 60% by weight of an olefinic thermoplastic elastomer (B),
Resin composition (b):
A resin composition comprising 60 to 100% by weight of a polypropylene resin and 0 to 40% by weight of a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated product thereof. 2. The bag according to claim 1, wherein the olefinic thermoplastic elastomers (A) and (B) are elastomers having a sea-island structure in which a copolymer rubber of propylene and ethylene is finely dispersed in a polypropylene resin. Grinding base film. The olefin-based thermoplastic elastomer (A) has an elution amount at 0 ° C. in the temperature rising elution fractionation between 0 ° C. and 140 ° C. using o-dichlorobenzene as a solvent, and is 60 to 80 wt. The substrate film for back grinding according to claim 1 or 2, wherein The base film for back grinding according to any one of claims 1 to 3, wherein the thickness is 50 to 300 µm. The back grind film which has an adhesive layer and a release film on the surface of the base film for back grinds in any one of Claims 1-4. 6. A backgrinding method for a semiconductor wafer, comprising attaching the backgrind film according to claim 5 to the surface of a semiconductor wafer, grinding the back surface of the semiconductor wafer, and removing the backgrind film from the semiconductor wafer. A method for producing a substrate film for backgrind, characterized by coextrusion molding in the order of surface layer / intermediate layer / back layer,
The intermediate layer comprises a resin composition containing 0 to 60% by weight of a polypropylene resin and 40 to 100% by weight of an olefinic thermoplastic elastomer (A), and
The manufacturing method of the base film for back grinds whose front and back layers consist of the following resin compositions (a) or resin compositions (b).
Resin composition (a):
A resin composition comprising 40 to 100% by weight of a polypropylene resin and 0 to 60% by weight of an olefinic thermoplastic elastomer (B),
Resin composition (b):
A resin composition comprising 60 to 100% by weight of a polypropylene resin and 0 to 40% by weight of a copolymer of a vinyl aromatic hydrocarbon and a conjugated diene hydrocarbon or a hydrogenated product thereof.

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