JP7010218B2 - Film and film manufacturing method - Google Patents

Description

The present invention relates to a film and a method for producing a film.

Conventionally, highly flexible film members that can be stretched with a low load even at room temperature have been applied as various products such as base materials such as adhesive tapes, transfer base materials for molding, and cushioning materials during pressing. However, it is used in a wide range of fields such as circuits and semiconductor manufacturing processes and decorations.

For example, in the process of manufacturing a semiconductor, a process of attaching an adhesive tape for semiconductor wafer processing to the pattern surface of a semiconductor wafer, a back grind process of polishing the back surface of the semiconductor wafer to reduce the thickness, and a process of reducing the thickness in the process. There are various steps such as a step of mounting a semiconductor wafer on a dicing tape, a step of peeling the adhesive tape for semiconductor wafer processing from the semiconductor wafer, and a step of dividing the semiconductor wafer by dicing.

In recent years, with the miniaturization of electronic devices, the thickness of semiconductor wafers has been reduced, and the strength thereof has decreased. Therefore, it is liable to be damaged during these manufacturing processes, and a decrease in yield has become an issue. For example, there is a demand for a highly flexible adhesive film that reduces the load on a semiconductor wafer generated in the process of radially expanding a dicing adhesive film after the dicing step and picking up individual chips. As a method for increasing the flexibility of the pressure-sensitive adhesive film, for example, a film containing a resin having excellent flexibility such as a polypropylene-based resin, an olefin-based elastomer, and a styrene-based elastomer as a main component is used as a base film for the pressure-sensitive adhesive film. The method to be used is known (Patent Document 1).

Further, a step of attaching a dicing adhesive film to the surface of the semiconductor wafer polished in the back grind step and peeling the back grind sheet by thermal peeling may be used. At that time, if the dimensional stability of the adhesive film for dicing that is heated at the same time is insufficient, there is a problem that the film is deformed, causing wrinkles and slack. To solve such a problem, for example, a film having controlled heat shrinkage has been proposed as a base material of an adhesive film for dicing tape (Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-119548 Japanese Unexamined Patent Publication No. 2014-157964

However, since the base material used for the adhesive tape described in Patent Document 1 and Patent Document 2 is a non-stretched film obtained by an extrusion method, there is a problem that the film expands under tension and loses the flatness of the film. be. Further, the non-stretched film conventionally used as a base film such as an adhesive film for dicing is difficult to be applied to semiconductor manufacturing process applications because the film expands when heated under a low load. On the other hand, a film having high dimensional stability such as a biaxially stretched film can reduce deformation during heating, but lacks flexibility, so that it is also difficult to apply to the application. As described above, conventionally known films cannot achieve both heat resistance and flexibility required for a substrate for a semiconductor manufacturing process, and improvement has been desired.

The present invention solves the above-mentioned problems of the prior art, has heat resistance to the extent that flatness can be maintained in the heating process, and has sufficient flexibility to be used as an adhesive film for dicing and the like. An object thereof is to provide a film suitable as a base material for a semiconductor manufacturing process.

In order to solve such a problem, the present invention has the following configuration.

(1) The stress Ta at 5% elongation at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less, and a load of 120 g / mm ² is applied to raise the temperature from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min. The dimensional change rate at 90 ° C. when heated is 90 ° C. dimensional change rate 1, the direction in which the 90 ° C. dimensional change rate 1 is maximum is the X direction, and the direction orthogonal to the X direction in the film surface is the Y direction and the X direction. When the dimensional change rate at 90 ° C is Tx1 (%), at least one layer having Tx1 of -10.00% or more and 10.00% or less and a glass transition temperature of -50 ° C or more and 50 ° C or less is formed. A film characterized by having .

(2) The dimensional change rate at 90 ° C. when the temperature is raised from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min under a load of 5 g / mm ² is 90 ° C. dimensional change rate 2 in the X direction. The film according to (1), wherein the Tx2 is -10.00% or more and 1.00% or less when the dimensional change rate 2 at 90 ° C. is Tx2 (%).

(3) The film according to (1) or (2), wherein the plane orientation coefficient of at least one side is 0.0080 or more and 0.0800 or less.

(4) The film according to any one of (1) to (3), wherein the glass transition temperature is −40 ° C. or higher and 40 ° C. or lower.

(5) Any of (1) to (4), wherein the Tx1 and Ty1 satisfy the following formula 1 when the 90 ° C. dimensional change rate 1 in the Y direction is Ty1 (%). The film described.
Equation 1: 0.10 ≦ | Tx1-Ty1 | ≦ 3.00
(6) The film according to any one of (1) to (5), wherein the static friction coefficient measured by superimposing different surfaces of the film is 0.10 or more and 0.80 or less.

(7) The film according to any one of (1) to (6), wherein the surface roughness SRa (μm) and the ten-point average roughness SRzjis (μm) satisfy the following formula 2 on at least one side. ..
Equation 2: 5.0 ≤ SRzjis / SRa ≤ 25.0
(8) Any of (1) to (7), wherein the heat shrinkage stress at 90 ° C. in the X direction and the Y direction is 0.010 N / mm ² or more and 5.000 N / mm ² or less. The film described in.

(9) The film according to any one of (1) to (8), wherein the shrinkage rate when heated at 80 ° C. for 1 hour is more than 1.00% and 10.00% or less.

(10) The invention according to any one of (1) to (9), wherein the stress Tb during 5% stretching at 25 ° C. after heating with Ta at 90 ° C. for 10 minutes satisfies the following formula 3. the film.
Equation 3: 0.85 ≤ Tb / Ta ≤ 1.30
(11) The film according to any one of (1) to (10), wherein the maximum stress Ka at 25 ° C. and the stress Kb at 50% elongation satisfy the following formula 4.
Equation 4: 0.70 ≦ Kb / Ka ≦ 1.00
(12) The film according to any one of (1) to (11), wherein the 90 ° C. dimensional change rate 1 in all directions is -25.00% or more and 10.00% or less.

(13) The film according to any one of (1) to (12), wherein the dimensional change rate 2 at 90 ° C. in all directions is -25.00% or more and 1.00% or less.

(14) The film according to any one of (1) to (13), wherein the amount of adhered foreign matter having a diameter of 100 μm or more is 10 pieces / m ² or less.

(15) The film according to any one of (1) to (14), wherein the thickness unevenness is 10.0% or less.

(16) The method for producing a film according to any one of (1) to (15), which comprises a step of stretching in at least one direction at a magnification of 1.04 times or more and 2.00 times or less. How to make a film.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a film having both flexibility and heat resistance and a method for producing the same, and the film of the present invention can be suitably used as a base material for a semiconductor manufacturing process.

The film of the present invention has a 5% stretching stress Ta at 25 ° C. of 1.0 MPa or ^more and 20.0 MPa or less, and a temperature rise rate of 10 ° C./ The dimensional change rate at 90 ° C. when the temperature is raised in minutes is 90 ° C. dimensional change rate 1, the direction in which the 90 ° C. dimensional change rate 1 is maximum is the X direction, and the direction orthogonal to the X direction in the film plane is the Y direction. When the 90 ° C. dimensional change rate in the X direction is Tx1 (%) , at least a layer having Tx1 of -10.00% or more and 10.00% or less and a glass transition temperature of -50 ° C. or more and 50 ° C. or less. It is characterized by having one or more layers .

From the viewpoint of improving heat resistance and reducing chip damage in the semiconductor manufacturing process, it is important that the film of the present invention has a 5% elongation stress Ta at 25 ° C. of 1.0 MPa or more and 20.0 MPa or less. If the stress Ta at 5% elongation at 25 ° C. (hereinafter, may be simply referred to as Ta) is less than 1.0 MPa, the film may be deformed during heating due to the mass of the semiconductor wafer, or may not be expanded when the film is expanded. It may be deformed uniformly. On the other hand, if Ta is larger than 20.0 MPa, the load when picking up the chip is large and the chip may be damaged. From the above viewpoint, Ta is more preferably 1.5 MPa or more and 15.0 MPa or less, and further preferably 2.0 MPa or more and 10.0 MPa or less. The method in which Ta is in the above range is a method of forming a cast film having at least one layer having a glass transition temperature of −50 ° C. or higher and 50 ° C. or lower, preferably a layer A described later, or a cast film 2.00 times. Examples thereof include a method of stretching in at least one direction at the following magnifications.

"5% stretching stress Ta at 25 ° C" means 5% stretching stress at 25 ° C measured at a test speed of 300 mm / min according to JIS K7127 (1999, test piece type 2). Further, "the stress Ta at 5% stretching at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less" means that any direction parallel to the film surface is parallel to the film surface in the 0 ° direction and from the 0 ° direction to the film surface. When the direction rotated 175 ° clockwise is the 175 ° direction, the test speed is 300 mm according to JIS K7127 (1999, test piece type 2) at 5 ° intervals in the range from 0 ° to 175 °. It means that the maximum value of the measured values for 36 times obtained by measuring the stress during stretching at 25 ° C. at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less. Further, as the sample for evaluation, a rectangular one having a size of 150 mm (measurement direction) × 10 mm (direction orthogonal to the measurement direction) is used.

In the film of the present invention, the dimensional change rate at 90 ° C. when the temperature is raised from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min under a load of 120 g / mm ² is 90 ° C. dimensional change rate 1, 90. When the direction in which the ° C. dimensional change rate 1 is maximized is the X direction, the direction orthogonal to the X direction in the film plane is the Y direction, and the 90 ° C. dimensional change rate in the X direction is Tx1 (%), Tx1 is -10. It is important that it is 0.00% or more and 10.00% or less. By setting Tx1 in the above range, it is possible to reduce the deformation when the semiconductor wafers are laminated and heated in a state where the film is stretched and loaded. If Tx1 is less than -10.00%, wrinkles may occur due to shrinkage of the film, and if Tx1 is larger than 10.00%, the fixing position of the semiconductor wafer fluctuates due to the expansion of the film. Problems may occur in the process. From the above viewpoint, Tx1 is preferably -10.00% or more and 1.00% or less, more preferably -8.00% or more and 1.00% or less, and -4.50% or more and -1.00%. The following is more preferable.

The film of the present invention has a dimensional change rate of 90 ° C. when the temperature is raised from 25 ° C. to 160 ° C. at a temperature rise rate of 10 ° C./min under a load of 5 g / mm ² . When the 90 ° C. dimensional change rate 2 in the X direction is Tx2 (%), Tx2 is preferably -10.00% or more and 1.00% or less. By setting Tx2 in the above range, it is possible to reduce deformation due to heating even when the load applied to the film is small. By setting Tx2 to -10.00% or more, it is possible to reduce the occurrence of wrinkles due to film shrinkage. Further, by setting Tx2 to 1.00% or less, it is possible to reduce the occurrence of defects in the post-process due to the change in the fixed position of the semiconductor wafer due to the expansion of the film. From the above viewpoint, Tx2 is more preferably −8.00% or more and 0.00% or less, and further preferably -4.50% or more and −1.00% or less.

The "90 ° C. dimensional change rate 1" can be measured by the following procedure. First, a film sample cut into a size of 15 mm (measurement direction) x 4 mm (direction orthogonal to the measurement direction) under a room temperature environment is allowed to stand for 24 hours in an atmosphere having a temperature of 25 ° C. and a relative humidity of 65%. Measure the length (L ₀ ) in the measurement direction. Next, the film sample is heated from 25 ° C. to 160 ° C. with a load of 120 g / mm ² at a heating rate of 10 ° C./min, and the length (L ₁ ) in the measurement direction at 90 ° C. is measured. From the obtained values of L ₀ and L ₁ , the dimensional change rate 1 at 90 ° C. is obtained by the following equation 5.
Equation 5: 90 ° C. Dimensional change rate 1 (%) = (L ₁ − L ₀ ) × 100 / L ₀ .

The device used for measuring the dimensions for calculating the dimensional change rate 1 at 90 ° C. is not particularly limited as long as the effect of the present invention is not impaired, and for example, a thermal analyzer TMA / SS6000 (manufactured by Seiko Instruments) or the like is used. Can be done. In the X direction, the dimensional change rate of 90 ° C. 1 is measured in any direction parallel to the film surface, and then rotated clockwise by 5 ° in parallel with the film surface so that the angle with the originally selected direction becomes 175 °. When the 90 ° C. dimensional change rate 1 is measured in the same manner until the value is reached, the value of the 90 ° C. dimensional change rate 1 is set to the largest direction. Then, the value of the dimensional change rate 1 at 90 ° C. at that time is Tx1 (%). Here, "the value of the 90 ° C. dimensional change rate 1 is the largest" means that the value of the 90 ° C. dimensional change rate 1 obtained by the equation 5 is the largest. For example, if the measured 90 ° C. dimensional change rate 1 in all directions is in the range of −5.00% to 3.00%, the direction in which the 90 ° C. dimensional change rate 1 is 3.00% is the X direction.

However, when there are a plurality of directions in which the value of the 90 ° C. dimensional change rate 1 obtained by Equation 5 is the largest, the 90 ° C. in the direction orthogonal to each measurement direction is obtained from the value of the 90 ° C. dimensional change rate 1 in each measurement direction. The absolute value of the value obtained by subtracting the value of the dimensional change rate 1 is obtained, and the absolute value is within the range of 0.10% or more and 3.00% or less, and the smallest direction is the X direction. Can be done. If this absolute value is outside the range of 0.10% or more and 3.00% or less in any measurement direction, this absolute value is closest to the range of 0.10% or more and 3.00% or less. The direction is the X direction.

Further, "90 ° C. dimensional change rate 2" means a dimensional change rate measured by the same method as 90 ° C. dimensional change rate 1 except that the load size is 5 g / mm ² , and the measurement is 90. A device similar to the ° C. dimensional change rate 1 can be used.

In the method of setting Tx1 to -10.00% or more and 10.00% or less or the above-mentioned preferable range, a cast film having at least one layer having a glass transition temperature of -50 ° C or more and 50 ° C or less is 1.04 times or more. Examples thereof include a method of stretching in at least one direction at a magnification of 2,000 times or less. Further, the method of setting Tx2 to -10.00% or more and 1.00% or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired. Examples thereof include a method of stretching in at least one direction at a magnification of 1.04 times or more and 2.00 times or less at the temperature of.

The value of the 90 ° C. dimensional change rate 1 in a direction other than the X direction is not particularly limited as long as the effect of the present invention is not impaired. However, from the viewpoint of reducing the dimensional change when heated by applying a load, the dimensional change rate 1 at 90 ° C. in all directions is preferably -25.00% or more and 10.00% or less, preferably -15.00%. It is preferably 1.00% or more, and more preferably -10.00% or more and -1.00% or less. With such an embodiment, when semiconductor wafers are laminated and heated in a state where a stretch load is applied to the film, excessive deformation of the film is suppressed, so that the dimensional stability required in the semiconductor manufacturing process can be easily achieved. realizable.

The value of the dimensional change rate 2 at 90 ° C. in a direction other than the X direction is not particularly limited as long as the effect of the present invention is not impaired. However, from the viewpoint of reducing the dimensional change when heated even when the load applied to the film is small, the 90 ° C. dimensional change rate 2 in all directions must be -25.00% or more and 1.00% or less. It is preferably -15.00% or more and 0.00% or less, and more preferably -10.00% or more and -1.00% or less. With such an embodiment, even when semiconductor wafers are laminated and heated with a small load applied to the film, excessive deformation of the film is suppressed, so that dimensional stability required in the semiconductor manufacturing process can be easily achieved. Can be realized.

The film of the present invention preferably has a plane orientation coefficient of at least one side of 0.0080 or more and 0.0800 or less. The plane orientation coefficient is an index showing the degree of orientation of the polymer in the film plane, and the larger the plane orientation coefficient, the higher the orientation state. The plane orientation coefficient (fn) referred to here means a plane orientation coefficient measured by the following method. First, an arbitrary direction parallel to the film plane is α, a direction orthogonal to this in the film plane is β, α and a direction orthogonal to β (thickness direction) is γ, and the refraction in each direction (nα, nβ, nγ) is measured with an Abbe refractometer. Using each of the obtained values, the plane orientation coefficient (fn ₀ ) when the two directions on the film surface are α and β is obtained by the following equation 6.
Equation 6: fn ₀ = (nα + nβ) / 2-nγ.

Next, γ is fixed and α and β are rotated clockwise by 5 ° while maintaining parallelism with the film surface to obtain nα5 and nβ5, and the refractive index (nα5, nβ5, nγ) in each direction is abbe. It is measured with a refractive index meter, and nα in the above formula 6 is replaced with nα5 and nβ is replaced with nβ5, respectively, and the plane orientation coefficient (fn ₅ ) when the two directions on the film surface are α5 and β5 is obtained. Hereinafter, the same measurement is repeated until the two directions on the film surface become α85 and β85. The average value of the obtained measured values for 18 times from fn ₀ to fn ₈₅ is the plane orientation coefficient (fn).

In the case of a film having a plane orientation coefficient of less than 0.0080, that is, a film that is unoriented or almost non-oriented, the flexibility is sufficient, but the heat resistance may be inferior. On the other hand, if the plane orientation coefficient exceeds 0.0800, the degree of orientation becomes high, so that the heat resistance is excellent, but the flexibility may be insufficient. From the viewpoint of achieving both flexibility and heat resistance of the film, the film of the present invention preferably has a plane orientation coefficient of at least one side of 0.0120 or more and 0.0600 or less, and more preferably 0.0150 or more and 0.0400 or less. It is more preferable to have.

The method of setting the plane orientation coefficient of at least one side of the film of the present invention to 0.0080 or more and 0.0800 or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired. Examples thereof include a method of stretching in at least one direction at a magnification of 04 times or more and 2.00 times or less. By stretching at such a low magnification, the resin molecules can be oriented to the extent that the flexibility of the film is not impaired. From the above viewpoint, when stretching in two or more directions, the area stretching ratio multiplied by the stretching ratio in each direction is preferably 1.20 times or more and 1.80 times or less, and 1.40 times or more and 1 It is more preferably .70 times or less.

The film of the present invention preferably has at least one A layer when the layer having a glass transition temperature of −40 ° C. or higher and 40 ° C. or lower is defined as the A layer. By having the A layer, the film has sufficient flexibility even at room temperature. Further, by combining with stretching at a magnification of 1.04 times or more and 2.00 times or less, which will be described later, the orientation state of the molecule is controlled within an appropriate range to realize the flexibility and heat resistance which are the objects of the present invention. Can be done. Here, the glass transition temperature means a temperature obtained based on the measurement of calorific value change (DSC method) by differential scanning calorimetry (DSC) in accordance with JIS K7121 (2012). From the viewpoint of achieving both flexibility and heat resistance, the glass transition temperature of the A layer is more preferably −25 ° C. or higher and 20 ° C. or lower, and further preferably −10 ° C. or higher and 5 ° C. or lower.

The resin used for the film of the present invention is not particularly limited as long as the effect of the present invention is not impaired, and for example, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyallylate, and the like. Polyethylene, polypropylene, polyamide, polyimide, polymethylpentene, polyvinyl chloride, polystyrene, polymethylmethacrylate, polycarbonate, polyether ether ketone, polysulfone, polyether sulfone, fluororesin, polyetherimide, polyphenylene sulfide, polyurethane, and cyclic Olefin-based resins and the like can be used alone or in combination of two or more. Of these, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyolefins such as polypropylene are preferably used from the viewpoints of film handleability, dimensional stability, and economic efficiency during manufacturing.

In the present invention, polyester is a general term for polymers having an ester bond as a major bond in the main chain. Usually, polyester can be obtained by polycondensing the dicarboxylic acid component and the glycol component.

The dicarboxylic acid component for obtaining a polyester is not particularly limited as long as the effect of the present invention is not impaired, and for example, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonicdicarboxylic acid. , Aromatic dicarboxylic acids such as diphenoxyetane dicarboxylic acid, 5-sodium sulfonate dicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid, 1,4 -Each component such as an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid and an oxycarboxylic acid such as paraoxybenzoic acid can be used. Further, the dicarboxylic acid component may be a dicarboxylic acid ester derivative component, and an esterified product of the above dicarboxylic acid compound, for example, dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethylmethyl ester terephthalate, 2,6-naphthalenedicarboxylic acid. Each component such as dimethyl, dimethyl isophthalate, dimethyl adipate, diethyl maleate, and dimethyl dimerate can also be used.

Further, the glycol component for obtaining polyester is not particularly limited as long as the effect of the present invention is not impaired, and for example, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and the like. Aliphatic dihydroxy compounds such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetra. Each component can be used, such as polyoxyalkylene glycol such as methylene glycol, alicyclic dihydroxy compound such as 1,4-cyclohexanedimethanol and spiroglycol, and aromatic dihydroxy compound such as bisphenol A and bisphenol S. Among them, ethylene glycol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, and poly in terms of both flexibility and heat resistance and handleability. It is preferable to use each component of tetramethylene glycol.

Two or more of these dicarboxylic acid components and glycol components may be used in combination as long as the effects of the present invention are not impaired.

Examples of the polyolefin that can be preferably used in the present invention include homopolymers of propylene exhibiting isotactic or syndiotactic stereoregularity, propylene / α-olefin copolymers, and the like. Specific examples of the α-olefin include ethylene, 1-butene, 1-pentene, 3-methylpentene-1,3-methylbutene-1,1-hexene, 4-methylpentene-1,5-ethylhexene-. Examples thereof include 1,1-octene, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, 5-methyl-2-norbornene and the like. From the viewpoint of good handling during processing, the propylene / α-olefin copolymer contains more than 50 mol% of propylene units when the total constituent units constituting the polymer are 100 mol%. preferable. Further, the propylene / α-olefin copolymer may be any binary system, ternary system, or quaternary system as long as the effect of the present invention is not impaired, and is a random copolymer or a block copolymer. It may be any of. A plurality of these propylene homopolymers and propylene / α-olefin copolymers may be mixed and used as long as the object of the present invention is not impaired.

Further, for the purpose of improving the flexibility of the film, it is also preferable to blend the polyolefin with the hydrocarbon-based elastomer. Examples of the hydrocarbon-based elastomer include styrene / butadiene copolymer (SBR), styrene / isobutylene / styrene copolymer (SIS), styrene / butadiene / styrene copolymer (SBS), and hydrogenated styrene / butadiene copolymer (s). Examples thereof include styrene / conjugated diene-based copolymers such as HSBR), hydrogenated products thereof, styrene / ethylene / butylene / styrene copolymers (SEBS), styrene / isobutylene copolymers, and mixtures thereof. Only one type of these hydrocarbon-based elastomers may be used as long as the effects of the present invention are not impaired, or two or more types may be used in combination.

The method of setting the glass transition temperature of the A layer to −40 ° C. or higher and 40 ° C. or lower or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, but the glass transition temperature of the resin constituting the A layer is −. Examples thereof include a method of using one having a temperature of 40 ° C. or higher and 40 ° C. or lower, or the above-mentioned preferable range. The glass transition temperature of the A layer is increased by making the resin constituting the A layer have a high glass transition temperature and by increasing the ratio of the resin having a high glass transition temperature to the entire resin constituting the A layer. be able to.

From the viewpoint of improving heat resistance and reducing deformation due to the weight of the semiconductor wafer, the film of the present invention has the following formulas for Tx1 and Ty1 when the dimensional change rate 1 at 90 ° C. in the Y direction is Ty1 (%). It is preferable to satisfy 1.
Equation 1: 0.10 ≦ | Tx1-Ty1 | ≦ 3.00.

| Tx1-Ty1 | is an index showing the variation in the plane of the 90 ° C. dimensional change rate 1 depending on the direction. More specifically, the larger | Tx1-Ty1 |, the larger the variation of the 90 ° C. dimensional change rate 1 in the X direction and the Y direction, and the smaller the | Tx1-Ty1 |, the larger the 90 ° C. dimensional change rate in the X direction and the Y direction. It means that the variation of 1 is small. When | Tx1-Ty1 | is 0.10 or more and 3.00 or less, the flatness of the film at the time of heating can be further improved. That is, by making the deformation of the film non-uniform to the extent that it does not become excessive during heating, the effect of maintaining the flatness of the film due to the dimensional change is likely to appear. When | Tx1-Ty1 | is larger than 3.00, the deformation of the film during heating becomes excessively non-uniform depending on the direction, so that wrinkles and slacks may easily occur. Further, when | Tx1-Ty1 | is smaller than 0.10 and the deformation in the plane does not depend on the direction, the tension may decrease near the center of the fixed sample, and the deformation may occur due to the weight of the semiconductor wafer. There is. From the above viewpoint, | Tx1-Ty1 | is more preferably 0.10 or more and 2.20 or less. Examples of the method of setting | Tx1-Ty1 | to 0.10 or more and 3.00 or less or the above-mentioned preferable range include a method of biaxially stretching a cast film having the above-mentioned layer structure. More specifically, the value of | Tx1-Ty1 | can be reduced by reducing the difference in stretching ratio in each direction when stretching in two axes.

The film of the present invention may be a single-layer film or a laminated film having two or more layers as long as the effect is not impaired. In the case of a three-layer structure, from the viewpoint of productivity, it is preferable that the composition of both surface layers is the same and the laminated thickness of both surface layers is the same.

The film of the present invention has a static friction coefficient of 0.10 or more and 0.80 or less measured by superimposing different surfaces of the film from the viewpoint of handling at the time of manufacturing, improvement of stretching accuracy, and reduction of generation of scratches on the surface. Is preferable. Here, the static friction coefficient means a static friction coefficient measured by arranging two films so that their opposite sides overlap each other and rubbing them at a speed of 100 mm / min according to JIS K7125 (1999). By setting the static friction coefficient measured by superimposing different surfaces of the film within the above range, it is possible to improve the handling at the time of manufacturing, improve the stretching accuracy when stretching with a roll, and also to improve the surface. It is also possible to reduce the occurrence of scratches in. In the film manufacturing process of the present invention, as described above, it is required to appropriately control the draw ratio in a low region. If the static friction coefficient exceeds 0.80, the draw ratio may be higher than the design or the film surface may be scratched, especially when the friction with the roll is excessive. If the coefficient of static friction is less than 0.10, winding misalignment of the roll is likely to occur, and productivity may decrease. From the above viewpoint, the static friction coefficient measured by superimposing different surfaces of the film is more preferably 0.10 or more and 0.70 or less, and further preferably 0.10 or more and 0.60 or less.

The method for setting the static friction coefficient to 0.10 or more and 0.80 or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, but when the film has a single-layer structure, the film is contained in the film. In the case of a laminated structure, a method of incorporating inorganic particles and / or organic particles having an average particle size of 1 μm or more and 10 μm or less in at least one outermost layer may be mentioned. More specifically, by increasing the content of these particles, the coefficient of static friction can be lowered. The average particle size referred to here is a volume average particle size. Further, a method of blending a polyolefin with a hydrocarbon-based elastomer having different crystallinity is also preferably used. By blending resins having different crystallinity, fine irregularities can be formed on the surface due to differences in crystal growth and stretchability during casting, and the coefficient of static friction can be set in a preferable range.

Examples of the particles include wet and / or dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, clay, and inorganic particles such as hydroxyapatite, styrene, silicone, and acrylic. Polymerized acid, methacrylic acid, divinylbenzene and the like, and organic particles containing polyester, polyamide and the like as constituents can be used. Among them, wet and / or dry inorganic particles such as silica and alumina, polymerized styrene, silicone, acrylic acid, methacrylic acid, divinylbenzene and the like, and organic particles containing polyester, polyamide and the like as constituents are preferably used. To. As the particles, two or more kinds of internal particles, inorganic particles, and organic particles may be used, or two or more kinds of internal particles, inorganic particles, and organic particles may be combined in combination.

The content of the particles is preferably in the range of 0.01 to 5% by mass, more preferably 0.03 to 3% by mass, based on the entire resin composition constituting the outermost surface layer of the film. .. If it is less than 0.01% by mass, it may be difficult to wind the film, and if it exceeds 5% by mass, it may cause deterioration of glossiness due to coarse protrusions, deterioration of transparency and film forming property.

In the film of the present invention, it is preferable that the surface roughness SRa (μm) and the ten-point average roughness SRzjis (μm) satisfy the following formula 2 on at least one side.
Equation 2: 5.0 ≦ SRzjis / SRa ≦ 25.0.

With such an aspect, the uniformity of the uneven shape of the film surface can be enhanced, and the adhesion between the film and the adhesive layer at the time of adhesive processing can be improved. By setting SRzjis / SRa to 25.0 or less, it is possible to reduce the inhibition of adhesion to the adhesive layer due to the coarse protrusions and to shorten the aging time during processing of the adhesive layer to improve productivity. Further, setting SRzjis / SRa to less than 5.0 is difficult to realize in a normally used manufacturing method because slippage occurs during film formation, and even if it can be realized, blocking or the like may occur. be. From the above viewpoint, SRzjis / SRa is more preferably 5.0 or more and 22.0 or less, and further preferably 5.0 or more and 18.0 or less.

The method of setting SRzjis / SRa to 5.0 or more and 25.0 or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, but for example, protrusions are formed by blending resins having different crystallinity. Examples thereof include a method of stretching the obtained cast film in at least one direction at a low magnification of 1.04 times or more and 2.00 times or less. Specifically, for example, SRzjis / SRa can be reduced by blending the above-mentioned polyolefin with a hydrocarbon-based elastomer and increasing the draw ratio within the above range. By stretching at such a low magnification, it becomes easy to control the protrusion size and the number of protrusions to make them uniform. In addition, since the degree of orientation of the molecules is increased by stretching, the strength of the protrusions can be improved and the change in surface shape due to scraping during the process can be reduced. Further, as a method of setting SRzjis / SRa to 5.0 or more and 25.0 or less or the above-mentioned preferable range, a method of performing multi-step stretching of two or more steps or a method of simultaneous biaxial stretching can be adopted. ..

The film of the present invention preferably has a heat shrinkage stress at 90 ° C. in the X and Y directions of 0.010 N / mm ² or more and 5.000 N / mm ² or less. With such an embodiment, it is possible to reduce the elongation and expansion deformation of the film when heated even in a state where a load is applied to the film as in the case where wafers are laminated. By setting the thermal shrinkage stress at 90 ° C to 0.010 N / mm ² or more, it is possible to reduce the deterioration of the position accuracy of the wafer due to dimensional changes during heating and the occurrence of wrinkles due to shrinkage deformation in the plane. can. Further, by setting the thermal shrinkage stress at 90 ° C. to 5.000 N / mm ² or less, it is possible to reduce the peeling and breakage of the wafer due to the stress generated on the wafer contact surface due to shrinkage. From the above viewpoint, the heat shrinkage stress at 90 ° C. in the X and Y directions is more preferably 0.030 N / mm ² or more and 4.000 N / mm ² or more, and 0.050 N / mm ² or more 3.300 N / mm ² . The above is more preferable.

Here, the heat shrinkage stress at 90 ° C. can be measured by the following method. First, a film of 15 mm (measurement direction) × 4 mm (direction orthogonal to the measurement direction) is allowed to stand for 24 hours in an atmosphere having a temperature of 25 ° C. and a relative humidity of 65% to prepare a sample. Next, the sample is heated from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min, and the heat shrinkage stress at 90 ° C. is measured and used as the heat shrinkage stress at 90 ° C. The load at the start of measurement is 5 g / mm ² . The device used for measuring the heat shrinkage stress at 90 ° C. is not particularly limited as long as it can measure the above, and can be appropriately selected. For example, TMA / SS6000 (manufactured by Seiko Instruments, Inc.) can be used.

The method of setting the heat shrinkage stress at 90 ° C. in the X and Y directions to 0.010 N / mm ² or more and 5.000 N / mm ² or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired. For example, in a cast film having at least one layer A, the glass transition temperature of the layer A is -30 ° C or higher and 40 ° C or lower, and the film is stretched in at least one direction at a magnification of 1.04 times or higher and 2.00 times or lower. How to do it.

The film of the present invention preferably has a shrinkage rate of more than 1.00% and 10.00% or less when heated at 80 ° C. for 1 hour. With such an aspect, it is possible to reduce the deformation at the time of heating even in the heating step at a low temperature. When the shrinkage rate when heated at 80 ° C. for 1 hour is 1.00% or less, it may be difficult to suppress the dimensional change during heating. Further, when the shrinkage rate when heated at 80 ° C. for 1 hour is larger than 10.00%, the shrinkage occurs when heated in an adhesive processing step or the like, and the dimensional change changes when heated in a subsequent semiconductor manufacturing step. It may be large. The shrinkage rate when heated at 80 ° C. for 1 hour is more preferably 2.00% or more and 8.00% or less, and further preferably 3.00% or more and 6.00% or less. The method for setting the shrinkage rate when heated at 80 ° C. for 1 hour to be more than 1.00% and 10.00% or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, but for example, cast. Examples thereof include a method of stretching the film in at least one direction at a magnification of 1.40 times or more and 2.00 times or less.

In the film of the present invention, it is preferable that the stress Tb during stretching at 25 ° C. after heating at Ta and 90 ° C. for 10 minutes satisfies the following formula 3.
Equation 3: 0.85 ≦ Tb / Ta ≦ 1.30.

Satisfaction of Tb / Ta with Equation 3 means that the change in elongation characteristics after heating is small. With such an embodiment, the film can be preferably used even when the film is expanded after the heating step. From the above viewpoint, Tb / Ta is more preferably 0.85 or more and 1.23 or less, and further preferably 0.85 or more and 1.15 or less. The method of setting Tb / Ta to 0.85 or more and 1.30 or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired. Examples include a method for processing. The heat treatment can be carried out by a conventionally known method such as roll annealing or a tenter method, and stretching may be carried out at the same time as heating as long as the effect of the present invention is not impaired.

In the film of the present invention, it is preferable that the maximum stress Ka at 50% elongation and the stress Kb at 50% elongation at 25 ° C. satisfy the following formula 4.
Equation 4: 0.70 ≦ Kb / Ka ≦ 1.00.

Satisfaction of Kb / Ka with Equation 4 means that the yield point stress is small or substantially nonexistent when the film is stretched at room temperature. When the yield point stress is high, uneven thickness and stress spots at the central and end portions during expansion tend to affect the degree of elongation, and the uniformity of elongation in the plane may decrease. Therefore, by adopting such an embodiment, the uniformity of in-plane elongation can be further improved. From the above viewpoint, Kb / Ka is more preferably 0.80 or more and 1.00 or less, and further preferably 0.90 or more and 1.00 or less. The method of setting Kb / Ka in a preferable range is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include a method of biaxially stretching a cast film at a magnification of 1.04 times or more and 2.00 times or less. Be done.

From the viewpoint of reducing the decrease in yield in wafer dicing, the film of the present invention preferably contains 10 pieces / m ² or less of adhered foreign matter having a diameter of 100 μm or more, and more preferably 2 pieces / m ² or less. Here, the diameter of the foreign matter is the distance between two points on the contour of the foreign matter, and the value thereof is the maximum. When the number of adhered foreign substances having a diameter of 100 μm or more is 10 pieces / m ² or less, the occurrence of chipping during wafer dicing can be suppressed and the decrease in yield can be reduced. The method of setting the amount of adhered foreign matter having a diameter of 100 μm or more to 10 pieces / m ² or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired. A method of installing an adhesive roll or a dust remover on the surface to remove foreign matter, a method of stretching in a hot air environment using an oven, and the like can be mentioned. The smaller the number of adhered foreign substances having a diameter of 100 μm or more is, the more preferable, and the lower limit thereof is most preferably 0 pieces / m ² .

The number of adhered foreign substances having a diameter of 100 μm or more can be measured by the following procedure. First, a visual inspection is performed using the reflected light of a three-wavelength fluorescent lamp in a dark room to extract foreign substances on the film sample. When a foreign substance is observed, the foreign substance is magnified and observed with an electron microscope to measure the length of the major axis, and only the foreign substance having a major axis length of 100 μm is extracted again. Then, the number of extracted foreign substances is divided by the area of the film sample to obtain the number of adhered foreign substances (pieces / m ² ) having a diameter of 100 μm or more.

The film of the present invention preferably has a thickness unevenness of 10.0% or less from the viewpoint of reducing a decrease in yield in wafer dicing. When the thickness unevenness is 10.0% or less, the frequency of chipping due to rattling during wafer dicing is reduced, the decrease in yield is reduced, and the uniformity during expansion is improved. From the above viewpoint, it is more preferable that the thickness unevenness is 8.0% or less. The method of setting the thickness unevenness to 10.0% or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, and for example, a method of stretching at a draw ratio of 1.04 times or more and 2.00 times or less is used. Can be mentioned. By stretching under such conditions, it is possible to reduce thickness unevenness while suppressing a decrease in flexibility. If the draw ratio is less than 1.04, it is difficult to eliminate the thickness unevenness of the cast film, and if the draw ratio is 2.00 times or more, the thickness unevenness may increase. The smaller the thickness unevenness, the more preferable, and the lower limit thereof is most preferably 0.0%. As a stretching condition, a method in which the stretching temperature is 90 ° C. or higher and the melting point of the film or lower is set to reduce the stretching tension is also preferably used.

Next, the method for producing the film of the present invention will be described. The method for producing a film of the present invention is characterized by having a step of stretching in at least one direction at a magnification of 1.04 times or more and 2.00 times or less. With such an aspect, the dimensional stability at the time of heating is improved. From the above viewpoint, it is preferable to have a step of stretching in at least one direction at a magnification of 1.20 times or more and 1.80 times or less, and a step of stretching in at least one direction at a magnification of 1.40 times or more and 1.70 times or less. It is more preferable to have. Further, in the method for producing a film of the present invention, the film may be biaxially stretched as long as the effect of the present invention is not impaired.

Hereinafter, the method for producing a film of the present invention will be specifically described by taking a single-layer film made of polyester as an example, but the present invention is not limited to such an example.

First, polyester is supplied to a twin-screw extruder for melt extrusion. At this time, it is preferable to set the oxygen concentration to 0.7% by volume or less in the flow nitrogen atmosphere in the extruder and control the extrusion temperature to a range of 20 to 30 ° C. higher than the melting point of polyester. Next, the foreign matter is removed and the extrusion amount is proportionalized through the filter and the gear pump, and the foreign matter is discharged from the T-die onto the cooling drum in the form of a sheet. At that time, the electrostatic application method in which the cooling drum and the resin are brought into close contact with each other by static electricity using an electrode to which a high voltage is applied, the casting method in which a water film is provided between the casting drum and the extruded polymer sheet, and the casting drum temperature are set to polyester glass. A sheet-like polymer is brought into close contact with a casting drum and cooled and solidified to obtain a casting film by a method of adhering an extruded polymer at a transition point of -20 ° C or higher and a glass transition temperature or lower, or a method of combining a plurality of these methods. .. Among these casting methods, the electrostatic application method is preferably used from the viewpoint of productivity and flatness.

In the method for producing a film of the present invention, the film is stretched in at least one axial direction at a magnification of 1.04 times or more and 2.00 times or less for the purpose of imparting dimensional stability during heating. The draw ratio in the case of stretching in the uniaxial direction is preferably 1.20 times or more and 1.80 times or less, and more preferably 1.40 times or more and 1.70 times or less. Further, when the film is stretched in the biaxial direction, it is preferable that the area magnification is in the above range. Further, it is desirable that the stretching speed is 100% / min or more and 200,000% / min or less. Stretching can be performed at any temperature of room temperature or higher, but it is preferably 20 ° C. or higher and 160 ° C. or lower, and it is preferable to preheat for 1 second or longer before stretching. Further, the stretching method is a sequential biaxial stretching method in which the casting film is stretched in the longitudinal direction and then stretched in the width direction, or stretched in the width direction and then stretched in the longitudinal direction, or the film is stretched in the longitudinal direction and the width direction. It can be carried out by a simultaneous biaxial stretching method in which stretching is performed almost simultaneously, or a uniaxial stretching method in which stretching is performed only in the longitudinal direction or the width direction. Here, the longitudinal direction refers to the traveling direction of the film, and the width direction refers to a direction parallel to the film surface and orthogonal to the longitudinal direction. The stretching may be carried out in one step or in multiple steps as long as the effect of the present invention is not impaired.

Further, the film may be heat-treated after stretching. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. This heat treatment is preferably performed at a temperature equal to or higher than the stretching temperature and lower than the stretching temperature of + 50 ° C. The heat treatment temperature referred to here means the temperature at which the temperature becomes the highest among the heat treatment temperatures performed after stretching. Further, the heat treatment time can be arbitrary as long as the characteristics are not deteriorated.

The heat-fixed film is cooled and then wound up as an intermediate product roll. Further, the film can be unwound from the intermediate product roll and cut in parallel with the longitudinal direction so as to have a desired width to obtain a wound final product roll. The final product roll obtained from one intermediate product roll may be one or a plurality of rolls.

In the film of the present invention, the stretching property at room temperature and the dimensional change property at high temperature are controlled. Therefore, the film of the present invention has both flexibility and heat resistance, and can be suitably used as a base material for a semiconductor manufacturing process or the like.

Hereinafter, the present invention will be described in detail with reference to Examples. The characteristics were measured and evaluated by the following methods.

(1) Stress at 5% elongation at 25 ° C. Ta
According to JIS K7127 (1999, test piece type 2), the film was measured at 25 ° C. and 65% RH using a film strength elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. First, a sample cut into a size of 150 mm in length and 10 mm in width in an arbitrary direction was stretched at an original length of 50 mm and a tensile speed of 300 mm / min to obtain a stress Ta (unit: MPa) at 5% stretching. .. The same measurement was performed 5 times for each sample, and the average value was calculated. Further, the measurement was performed in the same manner by changing the direction clockwise by 5 °, and the maximum value of the values in each direction from 0 ° to 175 ° was defined as the 5% elongation stress Ta (MPa) at 25 ° C.

(2) 90 ° C. Dimensional change rate 1 (Tx1, Ty1)
First, a film sample cut into a size of 15 mm (measurement direction) x 4 mm (direction orthogonal to the measurement direction) under a room temperature environment is allowed to stand for 24 hours in an atmosphere having a temperature of 25 ° C. and a relative humidity of 65%. The length (L ₀ ) in the measurement direction was measured. Next, this film sample was heated from 25 ° C. to 160 ° C. under a load of 120 g / mm ² at a heating rate of 10 ° C./min, and the length (L ₁ ) in the measurement direction at 90 ° C. was measured. From the obtained values of L ₀ and L ₁ , the 90 ° C. dimensional change rate 1 of the film sample was determined by the following formula 5.
Equation 5: 90 ° C. Dimensional change rate 1 (%) = (L ₁ − L ₀ ) × 100 / L ₀ .

The measurement direction was arbitrarily selected, measurement was performed 5 times in the selected measurement direction, and the average value of the obtained measured values was set to a dimensional change rate of 1 (%) at 90 ° C. in that direction. Further, the same measurement was performed by rotating the measurement direction clockwise by 5 °, and similarly, the value of 90 ° C. dimensional change rate 1 (%) in each direction until the rotation angle reached 175 ° was obtained. The maximum value obtained was defined as Tx1 (%), and the direction in which Tx1 (%) was obtained was defined as the X direction. Further, the direction orthogonal to the X direction in the plane is defined as the Y direction, and the dimensional change rate Ty1 (%) in the Y direction is determined from the value obtained by the previous measurement.

(3) 90 ° C. Dimensional change rate 2 (Tx2)
The measurement was carried out in the same manner as in (2) except that the load at the time of measurement was 5 g / mm ² and the measurement direction was the X direction, and the obtained value was Tx2 (%). The X direction referred to here is the same as the X direction specified in (2).

(4) Planar Orientation Coefficient The refractive index in each direction of the film was measured using an Abbe refractive index meter 4T manufactured by Atago Co., Ltd. equipped with a polarizing element, and the plane orientation coefficient was obtained by the following equation. A halogen lamp was used as the light source, a prism having a refractive index of 1.740 was used, and methylene iodide (refractive index 1.740) was used as the immersion liquid. Further, the measurement was carried out on both sides of the film under the environment of 23 ° C. and 65 RH% for 24 hours using the sample whose temperature and humidity were controlled. In the measurement, first, the arbitrary direction parallel to the film plane is α, the direction orthogonal to this in the film plane is β, and the directions orthogonal to α and β (thickness direction) are γ, and the refractive index (nα) in each direction is defined as γ. , Nβ, nγ) was measured with an Abbe refractometer. Using each of the obtained values, the plane orientation coefficient (fn ₀ ) was obtained when the two directions on the film surface were α and β by the following equation 6.
Equation 6: fn ₀ = (nα + nβ) / 2-nγ.

Next, γ is fixed and α and β are rotated clockwise by 5 ° while maintaining parallelism with the film surface to obtain nα5 and nβ5, and the refractive index (nα5, nβ5, nγ) in each direction is abbe. It was measured with a refractive index meter, and nα in the above formula 6 was replaced with nα5 and nβ was replaced with nβ5, respectively, to obtain the plane orientation coefficient (fn ₅ ) when the two directions on the film surface were α5 and β5. Hereinafter, the same measurement was repeated until the two directions on the film surface became α85 and β85. The average value of the obtained measured values for 18 times from fn ₀ to fn ₈₅ was defined as the plane orientation coefficient (fn).

(5) Using differential calorimetry (DSC) for the glass transition temperature of each layer, hold the sample at −120 ° C. for 5 minutes under a nitrogen atmosphere in accordance with JIS K7121 (2012), and then measure the sample at a rate of 20 ° C./min to 250 ° C. The temperature was raised and calculated from the measurement results by the following formula 7.
Equation 7: Glass transition temperature = (external glass transition start temperature + external glass transition end temperature) / 2
Equipment: Robot DSC-RDC220 manufactured by Seiko Electronics Inc.
Data analysis system: Disk session SSC / 5200
Sample mass: 5 mg
When the film has a laminated structure, first, a cross section in the thickness direction of the film cut out using a microtome is subjected to a transmission electron microscope H-7100FA type (manufactured by Hitachi, Ltd.) under the condition of an acceleration voltage of 75 kV. An image was taken at a magnification of 40,000 times, the layer structure was specified, and the thickness of each layer was measured. In some cases, in order to increase the contrast of each layer, a known dyeing method using RuO ₄ or OsO ₄ was used. From the obtained values of the thickness of each layer, a sample of the depth portion corresponding to each layer was taken, and the glass transition temperature of each layer was measured by the above method.

When a plurality of glass transition temperatures were confirmed as a result of the measurement, the value obtained by the following method was adopted as the glass transition temperature of the layer. First, the glass transition temperature of the film was measured by the above method, and the obtained measured values were Tg1, Tg2 ... Tgn in ascending order of temperature. Next, according to JIS K7244 (1999), the tan δ for each temperature of the film was obtained using the dynamic viscoelasticity measuring device “DMS6100” manufactured by Seiko Instruments, Inc., and the temperatures giving the maximum values were determined in ascending order of Tg1, Tg2 ... Tgn. Corresponded to. Of Tg1, Tg2, ... Tgn, when the values corresponding to each layer were separated, the temperature having the largest value of tan δ was adopted as the glass transition temperature of the layer. The measurement conditions for the dynamic viscoelasticity measurement were a tensile mode, a drive frequency of 1 Hz, a distance between chucks of 5 mm, and a heating rate of 2 ° C./min.

(6) Specification of layer structure The A layer and other layers (referred to as B layer) were specified from the glass transition temperature of each film layer measured in (5).

(7) Static friction coefficient Using a Toray slip tester 200G-15C (manufactured by MAKINO SEISAKUSHO), two films are brought into contact with one side and the opposite side according to JIS K7125 (1999). The value when placed and rubbed was measured three times, and the average value was taken as the static friction coefficient.

(8) Surface roughness SRa, 10-point average roughness SRzjis
The three-dimensional surface roughness of the sample surface was measured under the following conditions in accordance with JIS B0601 (2001) using a high-definition fine shape measuring instrument (three-dimensional surface roughness meter) of the stylus method. Then, the surface roughness SRa and the ten-point average roughness SRzjis were calculated using the analysis system (model TDA-31) built in the measuring instrument.

Measuring device: 3D fine shape measuring device (model ET-4000A) manufactured by Kosaka Laboratory Co., Ltd. Analytical device: 3D surface roughness analysis system (model TDA-31)
Stylus: Tip radius 0.5 μmR, diameter 2 μm, made of diamond Needle pressure: 100 μN
Measurement direction: Once each in the film longitudinal direction and film width direction (calculate the average value of both after measurement)
X measurement length: 1.0 mm
X feed speed: 0.1 mm / s (measurement speed)
Y feed pitch: 5 μm (measurement interval)
Number of Y lines: 81 (measurement number)
Z magnification: 20 times (vertical magnification)
Low frequency cutoff: 0.20 mm (waviness cutoff value)
High frequency cutoff: R + Wmm (roughness cutoff value), R + W means no cutoff.

Filter method: Gaussian spatial type Leveling: Yes (tilt correction)
Reference area: 1 mm ² .

(9) Thermal shrinkage stress at 90 ° C. A film of 15 mm (measurement direction) x 4 mm (direction orthogonal to the measurement direction), which was allowed to stand at a temperature of 25 ° C. and a relative humidity of 65% for 24 hours, was applied to TMA / SS6000 (Seiko Instruments). The temperature was raised from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min in the L assembly control mode, and the heat shrinkage stress at 90 ° C. was determined. The load at the start of measurement was 5 g / mm ² . The measurement directions were the X direction and the Y direction specified in (2).

(10) Shrinkage rate when heated at 80 ° C. for 1 hour The film was heated at 80 ° C. for 1 hour and calculated from the dimensions before heating and the dimensions after heating by the following formula 8. Each dimension was measured by the method specified in JIS K7133 (1999).
Equation 8: Shrinkage rate (%) = (dimensions before heating-dimensions after heating) / dimensions before heating x 100.

(11) 5% elongation stress Tb at 25 ° C after heating at 90 ° C for 10 minutes
The stress at 5% elongation at 25 ° C. was measured in the same manner as in (1) except that the measurement sample was allowed to stand in an oven set at 90 ° C. for 10 minutes in advance, and the obtained value was taken as Tb.

(12) Ratio of maximum stress Ka at 25 ° C. and stress at 50% elongation Kb A tensile test was performed on the film by the method described in (1) to obtain a stress at 50% elongation. Then, the maximum stress when the stress-strain curve was extended by 50% from the maximum value of the stress value in the region of the elongation of 50% or less obtained by the measurement was read. The same measurement was performed 5 times using samples in the same measurement direction, average values were calculated for each of the 50% elongation stress and the maximum stress at 50% elongation, and the obtained values were 50 in the measurement direction. The ratio of Ka to Kb (Kb / Ka) in this direction was calculated with the maximum stress Ka at the time of% elongation and the stress Kb at the time of 50% elongation. Furthermore, the same measurement is repeated by changing the measurement direction clockwise by 5 °, calculating the ratio of Ka and Kb in each direction from 0 ° (first measurement direction) to 175 °, and calculating the average value in all directions. Adopted.

(13) Number of adhered foreign substances with a diameter of 100 μm or more A film of 1 m (width direction) × 10 m (longitudinal direction) is cut out at the center of the roll sample in the width direction to make a sample, and the reflected light of a three-wavelength fluorescent lamp is used in a dark room. And a visual inspection was performed. When a foreign substance was observed, the foreign substance was observed with an electron microscope (manufactured by LEICA DMLM Leica Microsystems, Inc.) at a magnification of 100 times, and the length of the major axis of the foreign substance was measured by the length measuring function of the microscope. The number of foreign substances having a major axis length of 100 μm or more was defined as C, and the number of adhered foreign substances having a diameter of 100 μm or more (pieces / m ² ) was determined by the following formula 9. When the size of the film was less than the above dimensions, the entire film was used as a sample for visual inspection.
Equation 9: Number of adhered foreign substances with a diameter of 100 μm or more (pieces / m ² ) = C (pieces) / 10 (m ² ).

(14) Thickness unevenness Ten films of 10 cm × 10 cm were cut out from the center portion in the width direction and the positions of both ends of the roll sample to prepare a sample for evaluation. For each sample, the thicknesses of 5 points in the longitudinal direction, 5 points in the width direction, and a total of 10 points were measured, and the thickness unevenness was determined from the average value, the maximum value, and the minimum value according to the following formula 10.
Equation 10: Thickness unevenness (%) = (maximum thickness-minimum thickness) / average thickness Obtained 3 points in the width direction (both ends and center) About the value of thickness unevenness of each 10 samples The average value was calculated and used as the thickness unevenness. When the film was a sheet sample, 30 sheets were cut into 10 cm × 10 cm at an arbitrary position on the sheet, the average value of the thickness unevenness of each sample was calculated, and the film was adopted as the thickness unevenness.

(15) Uniform stretchability Nine straight lines are drawn at intervals of 30 mm in parallel with one set of sides on an arbitrarily cut out 300 mm × 300 mm square film, and nine at intervals of 30 mm in parallel with another set of sides. The straight line of was drawn and used as a measurement sample. Using the simultaneous biaxial stretching device, the obtained measurement sample is stretched in the direction parallel to one set of sides and the direction parallel to the other set of sides under the following conditions, and the distance between the straight lines is based on the following criteria. evaluated. The distance between the straight lines was measured from 6 distances (12 distances in total in 2 directions) formed by 7 straight lines excluding the 2 straight lines at both ends in each direction, and was farthest from 39 mm. The value was adopted as the measured value. For uniform stretchability, B or higher was regarded as acceptable.

<Stretching conditions>
Stretching device: KARO IV lab stretcher made by BRUCKNER Stretching temperature: 25 ° C
Stretching speed: 10 mm / min Stretching ratio: 1.30 times.

<Evaluation criteria>
S: The distance between the straight lines in the stretched film was 39 ± 1 mm.
A: It did not correspond to S, and the distance between the straight lines in the stretched film was 39 ± 3 mm.
B: Not applicable to S and A, and the distance between the straight lines in the stretched film was 39 ± 6 mm.
C: Neither S, A, nor B was applicable.

(16) Uniform stretchability after heating An arbitrarily cut 300 mm × 300 mm square film was heat-treated at 90 ° C. for 10 minutes, and then evaluated in the same manner by the method described in (15).

(17) Dimensional stability at 90 ° C (heat resistance)
A 200 mm x 200 mm square film cut out arbitrarily was used with Nitto Denko's double-sided tape No. It was attached to a stainless steel metal frame (outside: 200 mm × 200 mm, inside: 180 mm × 180 mm) at 500 AB to prepare a measurement sample. Next, the measurement sample was allowed to stand on a hot plate heated to 90 ° C. so that the film attached to the metal frame was in contact with the heated surface, and the amount of lift with respect to the reference plane when left for 240 minutes was measured. From the obtained results, the dimensional stability was evaluated according to the following criteria. In the measurement of the amount of floating, the reference plane was used as the heating surface of the hot plate. The measurement was performed by changing the thickness of the gold frame to be used to 1 mm, 2 mm, and 3 mm. If the film could be confirmed even in the frame, it was evaluated as C. For dimensional stability, B or higher was regarded as acceptable.
S: The lift of the film was 1 mm or less.
A: It did not correspond to S, and the lift of the film was 2 mm or less.
B: It did not correspond to S and A, and the lift of the film was 3 mm or less.
C: Neither S, A, nor B was applicable.

(18) Dimensional stability at 120 ° C (heat resistance)
The heat resistance was evaluated in the same manner as in (17) except that the temperature of the hot plate was set to 120 ° C.

(19) Quality A total of 30 film samples of 200 mm × 200 mm were cut out from the center position in the width direction and the positions at both ends in the width direction of the sample collected in (13). All the samples were observed with an optical microscope at a magnification of 100 times in 10 fields, and the presence or absence of scratches having a length of 1 μm or more was confirmed. The value obtained by rounding off the first decimal place of the average value of the number of visual fields in which scratches having a length of 1 μm or more were observed in each sample was defined as the number of visual fields in which scratches having a length of 1 μm or more were observed. The quality was evaluated according to the following criteria based on the number of adhered foreign substances having a diameter of 100 μm or more measured in (13) and the number of visual fields in which scratches having a length of 1 μm or more were observed. If the number of fields of view in which scratches with a length of 1 μm or more are observed and the number of adhered foreign substances with a diameter of 100 μm or more are evaluated differently (for example, when the former is A and the latter is B), the worse one. Evaluation (B) was adopted.
S: The number of visual fields in which scratches having a length of 1 μm or more were observed was 0, and the number of adhered foreign substances having a diameter of 100 μm or more was more than 0 and 5 or less.
A: The number of visual fields in which scratches having a length of 1 μm or more were observed was 1. Alternatively, the number of adhered foreign substances having a diameter of 100 μm or more was more than 5 and 8 or less.
B: The number of visual fields in which scratches having a length of 1 μm or more were observed was 2 to 3. Alternatively, the number of adhered foreign substances having a diameter of 100 μm or more was more than 8 and 10 or less.
C: The number of visual fields in which scratches having a length of 1 μm or more were observed was 4 or more. And / or the number of adhered foreign substances having a diameter of 100 μm or more was more than 10.

(20) Adhesiveness A pressure-sensitive adhesive layer composition solution (adhesive: acrylic acid ester manufactured by Nippon Carbide Industries Co., Ltd.) on the surface of an arbitrarily cut 200 mm × 200 mm square film so that the thickness is about 10 μm by the wire bar coating method. Apply 100 parts by mass of the resin-based solvent-based pressure-sensitive adhesive "Nisetsu" (registered trademark) "KP-2369" / 2 parts by mass of the cross-linking agent "CK-131"), and then apply the hot air oven HIGH manufactured by Espec Co., Ltd. -The film was dried in TEMP-OVEN PHH-200 at 100 ° C. for 1 minute and allowed to stand in an atmosphere at room temperature of 25 ° C. and relative humidity of 65% for 3 days. The sample thus obtained was cut into a size of 150 mm × 30 mm, and a speed of 300 mm / min was used at a room temperature of 25 ° C. using a film strength elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. It grew by 50%. After that, an acrylic adhesive tape (Nitto 31B (manufactured by Nitto Denko Corporation) is attached to the adhesive surface with a rubber roll, crimped with a 5 kg crimping roller, left for 24 hours, cut into 10 mm width, and used as an evaluation sample. The end of the acrylic adhesive tape of the evaluation sample was folded back at 180 °, the peel strength was measured with a tensile tester, and the evaluation was made according to the following criteria.
S: Peeling strength is 10N / 25mm or more.
A: The peel strength is 8N / 25mm or more and less than 10N / 25mm.
B: Peeling strength is 6N / 25mm or more and less than 8N / 25mm.
C: Peeling strength is less than 6N / 25mm.

(resin)
The resins used in the production of the film are as follows.

(Polyester A)
Polymerization of terephthalic acid and ethylene glycol using antimony trioxide as a catalyst was carried out by a conventional method to obtain polyester A having an intrinsic viscosity of 0.65.

(Polyester B)
A polyethylene terephthalate particle master having an intrinsic viscosity of 0.65 containing aggregated silica particles having a volume average particle diameter of 4.5 μm in polyester A at a particle concentration of 10% by mass.

(Polyester C)
PBT-Polyester Copolymer "Hytrel" (registered trademark) manufactured by Toray DuPont Co., Ltd. 5557
(Polyester D)
Polybutylene terephthalate (polyester E) with an intrinsic viscosity of 0.8
PBT-Polyester Copolymer "Hytrel" (registered trademark) manufactured by Toray DuPont Co., Ltd. 3001
(Polyolefin A)
Crystalline polypropylene Prime Polymer Co., Ltd., TF850H
(Polyolefin B)
Ethylene-octene-1 copolymer "Engage" (registered trademark) EG8200 manufactured by DuPont Dow Inc.
(Polyolefin C)
Hydrogenated styrene-butadiene copolymer (HSBR) "DYNARON" (registered trademark) 1320P manufactured by JSR Corporation.

(Example 1)
The raw material for obtaining the A layer adjusted to the composition shown in Table 1 was supplied to a twin-screw extruder having an oxygen concentration of 0.2% by volume. The raw material for obtaining the A layer is melted at a cylinder temperature of 270 ° C. of the twin-screw extruder, then sent to a T die via a short tube and a mouthpiece having a temperature of 270 ° C., and the temperature is controlled to 25 ° C. from the T die. It was discharged in the form of a sheet on the cooling drum. At that time, static electricity was applied using a wire-shaped electrode having a diameter of 0.1 mm, and the film was brought into close contact with the cooling drum to obtain a casting film. Next, the film was stretched at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. at a magnification of 1.44 times in both the longitudinal direction and the width direction using a simultaneous biaxial stretching device, and then dust was removed from both surfaces of the film with a dust remover. A single-layer film having a thickness of 180 μm was obtained. The evaluation results of each characteristic are shown in Table 1.

(Examples 2 to 14, 18 to 28, 34, 36 to 38, 40)
A single-layer film having a total thickness of 180 μm was obtained in the same manner as in Example 1 except that the film composition, extrusion temperature, and stretching conditions were as shown in Tables 1 to 6. The evaluation results of each characteristic are shown in Tables 1 to 6. Since the A layer does not exist in Examples 18 and 19, the “raw material for obtaining the A layer” in Example 1 is the “raw material for obtaining the B layer”.

(Example 15)
A casting film was obtained in the same manner as in Example 8. Next, the film was stretched at a preheating temperature of 100 ° C. and a stretching temperature of 120 ° C. at a magnification of 1.44 times in both the longitudinal direction and the width direction using a simultaneous biaxial stretching device, and then heat-treated in a zone heated to 130 ° C. for 10 seconds. Before winding, dust on both sides of the film was removed using dust removers to obtain a single-layer film having a total thickness of 180 μm. The evaluation results of each characteristic are shown in Table 3.

(Example 16)
The film composition is as shown in Table 3. The raw material for obtaining the A1 layer and the raw material for obtaining the A2 layer shown in Table 3 were supplied to separate twin-screw extruders having an oxygen concentration of 0.2% by volume. The cylinder temperature of each extruder is set to 270 ° C, and the raw materials are melted and then merged. It was discharged in the form of a sheet. After that, a laminated film having a total thickness of 180 μm was obtained in the same manner as in Example 1. The evaluation results of each characteristic are shown in Table 3.

(Example 17)
The film composition is as shown in Table 3. The raw material for obtaining the A layer and the raw material for obtaining the B layer shown in Table 3 were supplied to separate twin-screw extruders having an oxygen concentration of 0.2% by volume. The cylinder temperature of the extruder that supplied the raw material for obtaining the A layer and the cylinder temperature of the extruder that supplied the raw material for obtaining the B layer were both set to 260 ° C., and the raw materials were melted and then merged to bring the temperature to 260 ° C. It was sent to the T-die through the short tube and the base, and was discharged in the form of a sheet on a cooling drum whose temperature was controlled to 25 ° C. from the T-die. After that, a laminated film having a total thickness of 180 μm was obtained in the same manner as in Example 1 except that the stretching temperature was as shown in Table 3. The evaluation results of each characteristic are shown in Table 3.

(Examples 29 to 33)
A casting film was obtained in the same manner as in Example 1. Next, the film was stretched in the longitudinal direction at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. at the magnification shown in Table 5 using a roll stretching machine, and then in the width direction at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. using a tenter stretching machine. After that, dust on both surfaces of the film was removed with a dust remover to obtain a single-layer film having a total thickness of 180 μm. The evaluation results of each characteristic are shown in Table 5.

(Example 35)
A casting film was obtained in the same manner as in Example 1. Next, the film was stretched in the longitudinal direction at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. at the magnification shown in Table 5 using a roll stretching machine, and then in the width direction at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. using a tenter stretching machine. A single-layer film having a total thickness of 180 μm was obtained by stretching at the magnification described in 1. The evaluation results of each characteristic are shown in Table 5.

(Example 39)
A casting film was obtained in the same manner as in Example 1 except that the raw material composition for obtaining the A layer was as shown in Table 6. Next, the film was stretched at a preheating temperature of 100 ° C. and a stretching temperature of 120 ° C. at a simultaneous biaxial stretching machine at 1.44 times in both the longitudinal direction and the width direction, held for 3 seconds, and then dust was removed from both surfaces of the film with a dust remover. A single-layer film having a total thickness of 180 μm was obtained. The evaluation results of each characteristic are shown in Table 6.

(Comparative Examples 1 to 5)
A single-layer film having a total thickness of 180 μm was obtained in the same manner as in Example 1 except that the film composition, extrusion temperature, and stretching conditions were as shown in Table 7. The evaluation results of each characteristic are shown in Table 7. The stretching method "-" in Comparative Examples 2 and 5 means that the stretching itself was not performed.

The resin composition in the film composition was calculated with the total of the resin components constituting each layer as 100% by mass. The D surface is the surface that was in contact with the cast drum when the film was formed, and the ND surface is the surface opposite to the D surface. The same applies to Tables 2 to 7.

Since Example 16 is a film having a three-layer structure having two types of layers corresponding to the A layer, each layer is described as an A1 layer and an A2 layer.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a film having both flexibility and heat resistance and a method for producing the same, and the film of the present invention can be suitably used as a base material for a semiconductor manufacturing process.

Claims (16)

The stress Ta at 5% elongation at 25 ° C. is 1.0 MPa or more and 20.0 MPa or less.
When a load of 120 g / mm ² is applied and the temperature is raised from 25 ° C to 160 ° C at a temperature rise rate of 10 ° C / min, the dimensional change rate at 90 ° C is 90 ° C dimensional change rate 1 and 90 ° C dimensional change rate 1. When the maximum direction is the X direction, the direction orthogonal to the X direction in the film plane is the Y direction, and the 90 ° C. dimensional change rate in the X direction is Tx1 (%), Tx1 is -10.00% or more. A film having at least one layer having a glass transition temperature of −50 ° C. or higher and 50 ° C. or lower, which is 00% or less. When a load of 5 g / mm ² is applied and the temperature is raised from 25 ° C to 160 ° C at a temperature rise rate of 10 ° C / min, the dimensional change rate at 90 ° C is 90 ° C dimensional change rate 2, and the 90 ° C dimension in the X direction. The film according to claim 1, wherein when the rate of change 2 is Tx2 (%), Tx2 is -10.00% or more and 1.00% or less. The film according to claim 1 or 2, wherein the plane orientation coefficient of at least one side is 0.0080 or more and 0.0800 or less. The film according to any one of claims 1 to 3, wherein the glass transition temperature is −40 ° C. or higher and 40 ° C. or lower. The film according to any one of claims 1 to 4, wherein Tx1 and Ty1 satisfy the following formula 1 when the 90 ° C. dimensional change rate 1 in the Y direction is Ty1 (%).
Equation 1: 0.10 ≦ | Tx1-Ty1 | ≦ 3.00 The film according to any one of claims 1 to 5, wherein the static friction coefficient measured by superimposing different surfaces of the film is 0.10 or more and 0.80 or less. The film according to any one of claims 1 to 6, wherein the surface roughness SRa (μm) and the ten-point average roughness SRzjis (μm) satisfy the following formula 2 on at least one side.
Equation 2: 5.0 ≤ SRzjis / SRa ≤ 25.0 The film according to any one of claims 1 to 7, wherein the heat shrinkage stress at 90 ° C. in the X direction and the Y direction is 0.010 N / mm ² or more and 5.000 N / mm ² or less. The film according to any one of claims 1 to 8, wherein the shrinkage rate when heated at 80 ° C. for 1 hour is more than 1.00% and 10.00% or less. The film according to any one of claims 1 to 9, wherein the 5% stretching stress Tb at 25 ° C. after heating with Ta at 90 ° C. for 10 minutes satisfies the following formula 3.
Equation 3: 0.85 ≤ Tb / Ta ≤ 1.30 The film according to any one of claims 1 to 10, wherein the maximum stress Ka at 25 ° C. and the stress Kb at 50% elongation satisfy the following formula 4.
Equation 4: 0.70 ≦ Kb / Ka ≦ 1.00 The film according to any one of claims 1 to 11, wherein the 90 ° C. dimensional change rate 1 in all directions is -25.00% or more and 10.00% or less. The film according to any one of claims 1 to 12, wherein the dimensional change rate 2 at 90 ° C. in all directions is -25.00% or more and 1.00% or less. The film according to any one of claims 1 to 13, wherein the amount of adhered foreign matter having a diameter of 100 μm or more is 10 pieces / m ² or less. The film according to any one of claims 1 to 14, wherein the thickness unevenness is 10.0% or less. The method for producing a film according to any one of claims 1 to 15, which comprises a step of stretching in at least one direction at a magnification of 1.04 times or more and 2.00 times or less. Method.