CN110678504B - Film and method for producing film - Google Patents

Abstract

A film characterized in that the film has a stress Ta at 5% elongation at 25 ℃ of 1.0MPa or more and 20.0MPa or less and a load applied thereto of 120g/mm²And Tx1 is-10.00% or more and 10.00% or less, where the 90 ℃ dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature rise rate of 10 ℃/min is defined as 90 ℃ dimensional change rate 1, the direction in which 90 ℃ dimensional change rate 1 is the largest is defined as the X direction, the direction perpendicular to the X direction within the film surface is defined as the Y direction, and the 90 ℃ dimensional change rate in the X direction is defined as Tx1 (%). Provided is a film which has heat resistance to such an extent that flatness can be maintained in a heating step, and which has sufficient flexibility for use as an adhesive film for dicing or the like, and which is suitable as a substrate for a semiconductor manufacturing step.

Description

Film and method for producing film

Technical Field

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

Background

Conventionally, a film member having high flexibility and capable of being stretched even at room temperature under a low load has been used as various products such as a base material for an adhesive tape and the like, a transfer base material for molding, and a cushioning material for pressing, and has been effectively used for a wide range of applications such as production processes of circuits and semiconductors, decoration, and the like.

For example, in a process of manufacturing a semiconductor, there are various processes as follows: a step of sticking a semiconductor wafer processing adhesive tape to the pattern surface of the semiconductor wafer; a back grinding step of grinding the back of the semiconductor wafer to reduce the thickness; mounting the semiconductor wafer, which has been thinned through the step, on a dicing tape; a step of peeling the adhesive tape for processing a semiconductor wafer from the semiconductor wafer; and a step of dividing the semiconductor wafer by dicing.

In recent years, with the miniaturization of electronic devices, semiconductor wafers have been made thinner and their strength has been reduced, and therefore, there has been a problem that these manufacturing processes are prone to breakage and the yield is reduced. For example, an adhesive film excellent in flexibility is required to alleviate a load on a semiconductor wafer, which is generated in a step of picking up (pick up) each chip by radially expanding the adhesive film for dicing after a dicing step. As a method for improving the flexibility of an adhesive film, for example, a method of using a film containing a resin having excellent flexibility, such as a polypropylene-based resin, an olefin-based elastomer, or a styrene-based elastomer, as a main component as a base film of the adhesive film is known (patent document 1).

In addition, a step of bonding a dicing adhesive film to the surface of the semiconductor wafer polished in the back-polishing step and peeling the back-polished sheet by thermal peeling may be used. If the dimensional stability of the adhesive film for cutting, which is heated at the same time, is insufficient, the film is deformed, and wrinkles and slacks may occur. In order to solve such a problem, for example, a film in which heat shrinkage is controlled has been proposed as a base material of an adhesive film for dicing tape (patent document 2).

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open publication No. 2011-119548

Patent document 2: japanese patent laid-open publication No. 2014-157964

Disclosure of Invention

Problems to be solved by the invention

However, the base material used in the pressure-sensitive adhesive tapes described in patent documents 1 and 2 is a non-stretched film obtained by an extrusion method, and therefore has a problem that the base material swells under application of tension and loses the planarity of the film. In addition, a conventional non-stretched film used as a base film such as an adhesive film for dicing is difficult to apply to a semiconductor manufacturing process 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 is insufficient in flexibility, and thus is similarly difficult to apply to this application. As described above, the conventional known films cannot satisfy both heat resistance and flexibility required for a substrate for a semiconductor manufacturing process, and improvement is desired.

The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a film suitable as a substrate for a semiconductor manufacturing process, which has heat resistance to such an extent that flatness can be maintained in a heating process, and which has sufficient flexibility for use as an adhesive film for dicing or the like.

Means for solving the problems

In order to solve such a problem, the present invention includes the following configurations.

(1) A film characterized in that the film has a stress Ta at 5% elongation at 25 ℃ of 1.0MPa or more and 20.0MPa or less and a load applied thereto of 120g/mm²And Tx1 is-10.00% or more and 10.00% or less, where the 90 ℃ dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature rise rate of 10 ℃/min is defined as 90 ℃ dimensional change rate 1, the direction in which 90 ℃ dimensional change rate 1 is the largest is defined as the X direction, the direction perpendicular to the X direction within the film surface is defined as the Y direction, and the 90 ℃ dimensional change rate in the X direction is defined as Tx1 (%).

(2) The film according to (1), wherein a load of 5g/mm is applied²And when the dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/min is defined as 90 ℃ dimensional change rate 2 and the 90 ℃ dimensional change rate 2 in the X direction is defined as Tx2 (%), Tx2 is from-10.00% to 1.00%.

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

(4) The film according to any one of (1) to (3), which has 1 or more layers A when the layer having a glass transition temperature of-40 ℃ or higher and 40 ℃ or lower is the layer A.

(5) The film according to any one of (1) to (4), wherein the Tx1 and Ty1 satisfy the following formula 1, where Ty1 (%) is a 90 ℃ dimensional change rate 1 in the Y direction.

Formula 1: less than or equal to 0.10 | Tx1-Ty1| less than or equal to 3.00 |

(6) The film according to any one of (1) to (5), wherein a static friction coefficient measured by overlapping 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.

Formula 2: SRzjis/SRa is more than or equal to 5.0 and less than or equal to 25.0

(8) The film according to any one of (1) to (7), wherein the thermal shrinkage stress at 90 ℃ in the X direction and the Y direction is 0.010N/mm²Above and 5.000N/mm²The following.

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

(10) The film according to any one of (1) to (9), wherein the Ta and the stress Tb at 5% elongation at 25 ℃ after heating at 90 ℃ for 10 minutes satisfy the following formula 3.

Formula 3: Tb/Ta is more than or equal to 0.85 and less than or equal to 1.30

(11) The film according to any one of (1) to (10), wherein a maximum stress Ka at 50% elongation and a stress Kb at 50% elongation at 25 ℃ satisfy the following formula 4.

Formula 4: Kb/Ka is more than or equal to 0.70 and less than or equal to 1.00

(12) The film according to any one of (1) to (11), wherein the 90 ℃ dimensional change rate 1 in all directions is from-25.00% to 10.00%.

(13) The film according to any one of (1) to (12), wherein the 90 ℃ dimensional change rate 2 in all directions is from-25.00% to 1.00%.

(14) The film according to any one of (1) to (13), wherein the number of adhering foreign matters having a diameter of 100 μm or more is 10/m²The following.

(15) The film according to any one of (1) to (14), wherein the thickness is not all 10.0% or less.

(16) A method for producing a film according to any one of (1) to (15), comprising a step of stretching the film in at least one direction at a magnification of 1.04 to 2.00 times.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention provides 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 substrate for a semiconductor production process.

Detailed Description

The film of the present invention is characterized in that the film has a stress Ta of 1.0MPa or more and 20.0MPa or less at 5% elongation at 25 ℃ and a load of 120g/mm²And when the dimensional change rate at 90 ℃ when the temperature is increased from 25 ℃ to 160 ℃ at a temperature increase rate of 10 ℃/minute is 90 ℃ dimensional change rate 1, the direction in which 90 ℃ dimensional change rate 1 is the largest is defined as the X direction, the direction orthogonal to the X direction within the film surface is defined as the Y direction, and the 90 ℃ dimensional change rate in the X direction is defined as Tx1 (%), Tx1 is from-10.00% to 10.00%.

In the film of the present invention, it is important that the stress Ta at 5% elongation at 25 ℃ is 1.0MPa or more and 20.0MPa or less from the viewpoints of improving heat resistance and reducing chip damage in a semiconductor manufacturing process. If the stress Ta at 5% elongation at 25 ℃ (hereinafter, sometimes simply referred to as Ta) is less than 1.0MPa, the film may be deformed by heating and deformed unevenly when the film is expanded due to the mass of the semiconductor wafer. On the other hand, if Ta is greater than 20.0MPa, the load when picking up the chip is large and the chip may be damaged. From the above viewpoint, Ta is more preferably 1.5MPa or more and 15.0MPa or less, and further preferably 2.0MPa or more and 10.0MPa or less. The method of making Ta in the above range is not particularly limited, and examples thereof include a method of forming a cast film having at least 1 layer or more of a layer having a glass transition temperature of-50 ℃ or more and 50 ℃ or less, preferably an a layer described later, and a method of stretching the cast film in at least one direction at a magnification of 2.00 times or less.

"stress at 5% elongation Ta at 25 ℃" means the stress at 5% elongation at 25 ℃ measured at a test speed of 300 mm/min in accordance with JIS K7127(1999, test piece type 2). The phrase "the stress Ta at 5% elongation at 25 ℃ is 1.0MPa or more and 20.0MPa or less" means that when an arbitrary direction parallel to the film surface is a 0 ° direction and a direction rotated clockwise by 175 ° from the 0 ° direction parallel to the film surface is a 175 ° direction, the stress at 5% elongation at 25 ℃ is measured at a test speed of 300 mm/min at 5 ° intervals in accordance with JIS K7127(1999, test piece type 2) in a range of 0 ° direction to 175 ° direction, and the maximum value of the 36 measurement values obtained is 1.0MPa or more and 20.0MPa or less. In addition, a rectangular sample of 150mm (measurement direction) × 10mm (direction orthogonal to the measurement direction) was used as a sample for evaluation.

The film of the present invention is subjected to a load of 120g/mm²When the dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature rise rate of 10 ℃/min is defined as 90 ℃ dimensional change rate 1, the direction in which 90 ℃ dimensional change rate 1 is the largest is defined as the X direction, the direction perpendicular to the X direction within the film surface is defined as the Y direction, and the 90 ℃ dimensional change rate in the X direction is defined as Tx1 (%), it is important that Tx1 is-10.00% or more and 10.00% or less. By setting Tx1 to the above range, deformation of the semiconductor wafer when heated in a state where the semiconductor wafer is stacked and an extension load is applied to the film can be reduced. If Tx1 is less than-10.00%, wrinkles may be generated due to shrinkage of the film, and if Tx1 is greater than 10.00%, the fixing position of the semiconductor wafer may be changed due to expansion of the film, which may cause a problem in a subsequent process. From the above viewpoint, it is preferable if Tx1 is-10.00% or more and 1.00% or less, more preferable if it is-8.00% or more and 1.00% or less, and more preferable if it is-4.50% or more and 1.00% or lessIt is further preferable that the content of-1.00% or less is in the range of-1.00%.

The film of the present invention is subjected to a load of 5g/mm²When the dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/min is defined as 90 ℃ dimensional change rate 2 and the 90 ℃ dimensional change rate 2 in the X direction is defined as Tx2 (%), Tx2 is preferably from-10.00% to 1.00%. By setting Tx2 to the above range, even when the load applied to the film is small, the deformation due to heating can be reduced. By setting Tx2 to-10.00% or more, the occurrence of wrinkles due to shrinkage of the film can be reduced. Further, by setting Tx2 to 1.00% or less, it is possible to reduce the occurrence of defects in the subsequent process due to the change in the fixing position of the semiconductor wafer caused by the expansion of the film. From the above viewpoint, Tx2 is more preferable if it is-8.00% or more and 0.00% or less, and is further preferable if it is-4.50% or more and-1.00% or less.

The "90 ℃ dimensional change rate 1" can be determined by the following procedure. First, a film sample cut into a size of 15mm (measurement direction) × 4mm (direction orthogonal to the measurement direction) in a room temperature environment was left standing at 25 ℃ for 24 hours in an atmosphere of 65% relative humidity, and the length (L) in the measurement direction was measured₀). Next, the film sample was subjected to a load of 120g/mm²The temperature was raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/min, and the length (L) in the measurement direction at 90 ℃ was measured₁). From the obtained L₀And L₁The 90 ℃ dimensional change rate 1 was obtained by the following equation 5.

Formula 5: 90 ℃ dimensional Change ratio 1 (%) - (L)₁-L₀)×100/L₀。

The apparatus used for the measurement of the dimension for calculating the 90 ℃ dimensional change rate 1 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 セイコーインスツルメンツ) or the like can be used. The X direction is: the 90 ℃ dimensional change rate 1 in any direction parallel to the film surface was measured, and thereafter, the direction in which the 90 ℃ dimensional change rate 1 had the largest value was measured similarly in the 90 ℃ dimensional change rate 1 after rotating clockwise 5 ° parallel to the film surface until the angle with the initially selected direction reached 175 °. The 90 ℃ dimensional change rate 1 at this time was Tx1 (%). Here, "the value of 90 ℃ dimensional change rate 1 is the maximum value of 90 ℃ dimensional change rate 1 obtained by equation 5. For example, if the 90 ℃ dimensional change rate 1 in all directions of the measurement is in the range of-5.00% to 3.00%, the direction having a 90 ℃ dimensional change rate 1 of 3.00% is the X direction.

However, when there are a plurality of directions in which the value of the 90 ℃ dimensional change rate 1 obtained by equation 5 is the largest, the absolute value of the value obtained by subtracting the value of the 90 ℃ dimensional change rate 1 in the direction orthogonal to each measurement direction from the value of the 90 ℃ dimensional change rate 1 in each measurement direction may be obtained, and the direction in which the absolute value is in the range of 0.10% to 3.00% and the smallest direction is the X direction. In any measurement direction, when the absolute value is out of the range of 0.10% to 3.00%, the direction closest to the absolute value in the range of 0.10% to 3.00% is defined as the X direction.

The "90 ℃ dimensional change rate 2" means a value obtained by excluding a load of 5g/mm²The dimensional change rate was measured by the same method as the dimensional change rate at 90 ℃ 1 except that the same apparatus as the dimensional change rate at 90 ℃ 1 was used for the measurement.

The method of adjusting Tx1 to-10.00% or more and 10.00% or less or the above-described 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 stretching a cast film having at least one layer having a glass transition temperature of-50 ℃ or more and 50 ℃ or less in at least one direction at a magnification of 1.04 times or more and 2.00 times or less. The method of setting Tx2 to-10.00% or more and 1.00% or less or the above-described 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 stretching the cast film at a temperature of 70 ℃ or more and film melting point or less at a magnification of 1.04 times or more and 2.00 times or less in at least one direction.

The value of the 90 ℃ 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 heating is performed under a load, the 90 ℃ dimensional change rate 1 in all directions is preferably-25.00% or more and 10.00% or less, preferably-15.00% or more and 1.00% or less, and more preferably-10.00% or more and-1.00% or less. With such a configuration, excessive deformation of the film can be suppressed when the semiconductor wafer is stacked and heated in a state where an elongation load is applied to the film, and therefore, dimensional stability necessary for a semiconductor manufacturing process can be easily achieved.

The value of the 90 ℃ dimensional change rate 2 in the 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 during heating even when the load applied to the film is small, the 90 ℃ dimensional change rate 2 in all directions is preferably from-25.00% to 1.00%, preferably from-15.00% to 0.00%, and more preferably from-10.00% to 1.00%. With such an arrangement, even when the semiconductor wafer is heated in a state where a small load is applied to the film by laminating the semiconductor wafers, excessive deformation of the film can be suppressed, and therefore, dimensional stability necessary for a semiconductor manufacturing process can be easily achieved.

The film of the present invention preferably has a surface orientation coefficient of at least one surface of 0.0080 or more and 0.0800 or less. The plane orientation coefficient is an index indicating the degree of orientation of the polymer in the film plane, and a larger plane orientation coefficient means a higher orientation state. Here, the plane orientation coefficient (fn) is a plane orientation coefficient measured by the following method. First, the refractive index (n α, n β, n γ) in each direction was measured with an abbe refractometer, where α is an arbitrary direction parallel to the film surface, β is a direction orthogonal to the direction within the film surface, and γ is a direction orthogonal to α and β (thickness direction). Using the obtained values, the plane orientation coefficients (fn) were obtained by the following equation 6 for 2 directions on the film surface, which are α and β₀)。

Formula 6: fn₀＝(nα+nβ)/2-nγ。

Then, γ is fixedly set as n β 05 and n β 15 by rotating α and β clockwise by 5 ° while maintaining the parallelism with the film surface, refractive indices (n α 5, n β 5, n γ) in each direction are measured by an abbe refractometer, n α of the above formula 6 is replaced with n α 5, n β is replaced with n β 5, and the plane orientation coefficient (fn) when 2 directions on the film surface are α 5 and β 5 is obtained₅). Hereinafter, the same measurement was repeated in the same manner until 2 directions on the film surface became α 85 and β 85. The resulting fn₀～fn₈₅The average value of the 18 measurement values of (2) becomes the plane orientation coefficient (fn).

In the case of a film having a surface orientation coefficient of less than 0.0080, that is, a state of no orientation or infinitely close to no orientation, although flexibility is sufficient, heat resistance may be poor. On the other hand, if the plane orientation coefficient exceeds 0.0800, the degree of orientation increases, and therefore the heat resistance is excellent, while the flexibility may become insufficient. From the viewpoint of satisfying both flexibility and heat resistance of the film, the surface orientation coefficient of at least one surface of the film of the present invention is more preferably 0.0120 or more and 0.0600 or less, and still more preferably 0.0150 or more and 0.0400 or less.

The method of setting the surface 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 preferable range described above is not particularly limited as long as the effects of the present invention are not impaired, and for example, a method of stretching a cast film at a magnification of 1.04 times or more and 2.00 times or less in at least one direction may be mentioned. By stretching at such a low ratio, the molecules of the resin can be oriented to such an extent that the flexibility of the film is not impaired. From the above viewpoint, when stretching is performed in a direction of biaxial or biaxial, the area stretching ratio obtained by multiplying the stretching ratios in the respective directions 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.

The film of the present invention preferably has at least 1 or more a layers when a layer having a glass transition temperature of-40 ℃ or higher and 40 ℃ or lower is an a layer. By having the a layer, the film has sufficient flexibility even at room temperature. In addition, by combining with the stretching at a magnification of 1.04 times or more and 2.00 times or less described later, the orientation state of the molecules can be controlled to an appropriate range for achieving flexibility and heat resistance which are the objects of the present invention. The glass transition temperature here is a temperature determined based on measurement of a change in heat by Differential Scanning Calorimetry (DSC) (DSC method) in accordance with jis k7121 (2012). From the viewpoint of satisfying both flexibility and heat resistance, the glass transition temperature of the a layer is more preferable if it is-25 ℃ or higher and 20 ℃ or lower, and is further preferable if it is-10 ℃ or higher and 5 ℃ 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), polyarylates, polyethylene, polypropylene, polyamides, polyimides, polymethylpentene, polyvinyl chloride, polystyrene, polymethyl methacrylate, polycarbonate, polyether ether ketone, polysulfone, polyether sulfone, fluorine resin, polyether imide, polyphenylene sulfide, polyurethane, and cyclic olefin resins may be used singly or in combination in plurality. Among them, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polyolefins such as polypropylene are preferably used from the viewpoints of handling properties and dimensional stability of the film and economy in production.

In the present invention, the polyester is a generic name of polymers in which the main bond in the main chain is an ester bond. Generally, the polyester can be obtained by subjecting a dicarboxylic acid component and a diol component to a polycondensation reaction.

The dicarboxylic acid component for obtaining the polyester is not particularly limited as long as the effect of the present invention is not impaired, and for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2, 6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, and 5-sodium sulfodicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, and fumaric acid, alicyclic dicarboxylic acids such as 1, 4-cyclohexanedicarboxylic acid, and hydroxycarboxylic acids such as p-hydroxybenzoic acid can be used. The dicarboxylic acid component may be a dicarboxylic acid ester derivative component, and the ester compounds of the dicarboxylic acid compounds may be used, for example, dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2, 6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl adipate, diethyl maleate, dimethyl dimer acid, and the like.

The diol component for obtaining the polyester is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include aliphatic dihydroxy compounds such as ethylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, and 2, 2-dimethyl-1, 3-propanediol, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol, and polybutylene glycol, alicyclic dihydroxy compounds such as 1, 4-cyclohexanedimethanol, and spiroglycol, and aromatic dihydroxy compounds such as bisphenol a and bisphenol S. Among them, it is preferable to use ethylene glycol, 1, 4-butanediol, 2-dimethyl-1, 3-propanediol, 1, 4-cyclohexanedimethanol, and polytetramethylene glycol from the viewpoint of satisfying both flexibility and heat resistance and workability.

These dicarboxylic acid components and diol components may be used in combination of 2 or more species 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 and propylene/α -olefin copolymers that exhibit isotactic or syndiotactic stereoregularity. 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-1, 1-octene, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, 5-methyl-2-norbornene, and the like. In addition, the propylene/α -olefin copolymer preferably contains more than 50 mol% of propylene units, based on 100 mol% of all the constituent units constituting the polymer, from the viewpoint of improving the workability in processing. The propylene/α -olefin copolymer may be any of 2-, 3-and 4-membered copolymers, and may be any of random copolymers and block copolymers, as long as the effects of the present invention are not impaired. These propylene homopolymers and propylene/α -olefin copolymers may be used in combination in a plurality within a range not impairing the object of the present invention.

In addition, it is also preferable to blend a hydrocarbon elastomer with a polyolefin for the purpose of improving the flexibility of the film. Examples of the hydrocarbon-based elastomer include styrene/conjugated diene-based copolymers such as styrene/butadiene copolymer (SBR), styrene/isobutylene/styrene copolymer (SIS), styrene/butadiene/styrene copolymer (SBS) and hydrogenated styrene/butadiene copolymer (HSBR), hydrogenated products thereof, styrene/ethylene/butylene/styrene copolymer (SEBS), styrene/isobutylene copolymer, and mixtures thereof. These hydrocarbon-based elastomers may be used alone in 1 kind, or in combination with 2 or more kinds, as long as the effects of the present invention are not impaired.

The method for adjusting the glass transition temperature of the a layer to-40 ℃ or higher and 40 ℃ or lower or the above-mentioned preferred range is not particularly limited as long as the effect of the present invention is not impaired, but examples of the resin constituting the a layer include a method using a resin having a glass transition temperature of-40 ℃ or higher and 40 ℃ or lower or within the above-mentioned preferred range. The glass transition temperature of the a layer can be made high by making the resin constituting the a layer a resin having a high glass transition temperature and increasing the ratio of the resin having a high glass transition temperature to the entire resin constituting the a layer.

From the viewpoint of improving heat resistance and reducing deformation due to the weight of a semiconductor wafer, the film of the present invention preferably satisfies the following formula 1 Tx1 and Ty1, where Ty1 (%) is the 90 ℃ dimensional change rate 1 in the Y direction.

Formula 1: the absolute value Tx1-Ty1 is more than or equal to 0.10 and less than or equal to 3.00.

I Tx1-Ty1 is an index indicating the deviation in the direction of the 90 ℃ dimensional change rate 1 in the plane. More specifically, a larger | Tx1-Ty1| means a larger deviation of the 90 ℃ dimensional change rate 1 in the X direction and the Y direction, and a smaller | Tx1-Ty1| means a smaller deviation of the 90 ℃ dimensional change rate 1 in the X direction and the Y direction. By setting | Tx1-Ty1| to 0.10 or more and 3.00 or less, the planarity of the film during heating can be further improved. That is, the effect of maintaining the planarity of the film due to dimensional changes is easily achieved by making the deformation of the film during heating non-uniform to an excessive extent. If | Tx1-Ty1| is larger than 3.00, the deformation of the film during heating is excessively uneven depending on the direction, and therefore wrinkles and slackening are likely to occur in some cases. When | Tx1-Ty1| is smaller than 0.10 and the in-plane deformation hardly changes with the direction, the tension may decrease near the center of the fixed sample, and the strain may be caused by the weight of the semiconductor wafer. From the above viewpoint, | Tx1-Ty1| is more preferably 0.10 or more and 2.20 or less. Examples of the method of adjusting | Tx1-Ty1| to 0.10 or more and 3.00 or less or the preferable range described above include a method of biaxially stretching a cast film composed of the above layers. More specifically, the value of | Tx1-Ty1| can be made small by reducing the difference in stretch ratio in each direction during biaxial stretching.

The film of the present invention may be a single-layer film or a laminated film having 2 or more layers, as long as the effects are not impaired. In the case of the 3-layer structure, it is preferable that the compositions of both surface layers are the same and the lamination thicknesses of both surface layers are equal from the viewpoint of productivity.

In the film of the present invention, it is preferable that the static friction coefficient measured by overlapping different surfaces of the film is 0.10 or more and 0.80 or less from the viewpoints of improving the workability and stretching accuracy at the time of production and reducing the occurrence of surface damage. The static friction coefficient here is a static friction coefficient measured by placing 2 films so that opposite side surfaces thereof are overlapped with each other and rubbing at a speed of 100 mm/min according to jis k7125 (1999). By setting the static friction coefficient measured by overlapping different surfaces of the film to the above range, handling at the time of manufacturing becomes good, stretching accuracy at the time of stretching by a roll can be improved, and occurrence of damage on the surface can also be reduced. In the film production process of the present invention, it is required to appropriately control the stretch ratio in a low region as described above. If the static friction coefficient exceeds 0.80, the stretching ratio may become higher than the design ratio and damage may occur on the film surface, particularly when the friction with the roller becomes excessive. If the static friction coefficient is less than 0.10, roll shifting of the roll is likely to occur, and productivity may be lowered. From the above viewpoint, the static friction coefficient measured by overlapping different surfaces of the film is more preferably 0.10 or more and 0.70 or less, and still more preferably 0.10 or more and 0.60 or less.

The method of adjusting the static friction coefficient to 0.10 or more and 0.80 or less or the above-described 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 including inorganic particles and/or organic particles having an average particle diameter of 1 μm or more and 10 μm or less in at least one outermost layer of a film in the case where the film is formed of a single layer, and in the case where the film is formed of a stacked layer. More specifically, by increasing the content of these particles, the static friction coefficient can be reduced. The average particle size here is a volume average particle size. Further, a method of blending a polyolefin with a hydrocarbon elastomer having different crystallinity is also preferably used. By blending resins having different crystallinities, fine irregularities can be formed on the surface by the difference in crystal growth and stretchability during casting, and the static friction coefficient can be set to a preferred range.

Examples of the particles include inorganic particles such as wet and/or dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, clay, and hydroxyapatite, organic particles obtained by polymerizing styrene, silicone, acrylic acid, methacrylic acid, divinylbenzene, and the like, and organic particles containing polyester, polyamide, and the like as a constituent component. Among them, inorganic particles such as wet and/or dry silica and alumina, organic particles obtained by polymerizing styrene, silicone, acrylic acid, methacrylic acid, divinylbenzene, etc., and organic particles containing polyester, polyamide, etc., as a constituent are preferably used. The particles may be composed of 2 or more kinds of the inner particles, inorganic particles, and organic particles, or 2 or more kinds of the inner particles, inorganic particles, and organic particles.

The content of the particles is preferably in the range of 0.01 to 5% by mass, and more preferably 0.03 to 3% by mass, based on the entire resin composition constituting the outermost layer of the film. If the amount is less than 0.01% by mass, the film may be difficult to wind, and if the amount exceeds 5% by mass, the gloss may be reduced due to coarse protrusions, and the transparency and film-forming properties may be deteriorated.

The film of the present invention preferably has a surface roughness SRa (μm) and a ten-point average roughness SRzjis (μm) satisfying the following formula 2 on at least one side.

Formula 2: SRzjis/SRa is more than or equal to 5.0 and less than or equal to 25.0.

With this configuration, the uniformity of the uneven shape on the film surface can be improved, and the adhesion between the film and the adhesive layer during the adhesive process can be improved. By setting SRzjis/SRa to 25.0 or less, the inhibition of adhesion to the adhesive layer due to coarse protrusions can be reduced, and the aging time during the processing of the adhesive layer can be shortened to improve productivity. In addition, when SRzjis/SRa is less than 5.0, slippage occurs during film formation, and therefore, it is difficult to achieve the production in a generally used production method, and blocking or the like may occur even if it is possible to achieve the production. From the above viewpoint, SRzjis/SRa is more preferable if it is 5.0 or more and 22.0 or less, and is further preferable if it is 5.0 or more and 18.0 or less.

The method of setting SRzjis/SRa to 5.0 to 25.0 or less or the preferable range described above is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include a method of forming projections by blending resins having different crystallinities and stretching the obtained cast film in at least one direction at a low magnification of 1.04 to 2.00 times. Specifically, for example, by blending the polyolefin described above with a hydrocarbon-based elastomer, the stretching ratio is increased in the above range, and SRzjis/SRa can be decreased. By stretching at such a low magnification, the size and number of protrusions can be easily controlled to be uniform. Further, since the degree of orientation of the polymer is also increased by stretching, the strength of the protrusions can be increased, and the change in the surface shape due to shaving in the process can be reduced. Further, as a method for adjusting SRzjis/SRa to 5.0 or more and 25.0 or less or the preferable range described above, a method of performing simultaneous biaxial stretching by a multi-stage method in which stretching is 2 stages or more may be adopted.

The film of the present invention preferably has a heat shrinkage stress at 90 ℃ in the X-direction and Y-direction of 0.010N/mm²Above and 5.000N/mm²The following. With this configuration, even in a state where a load is applied to the film as in the case of stacking wafers, the elongation and the expansion deformation of the film during heating can be reduced. By setting the thermal shrinkage stress at 90 ℃ to 0.010N/mm²As described above, it is possible to reduce the reduction in the positional accuracy of the wafer due to the dimensional change during heating and the occurrence of wrinkles due to in-plane shrinkage deformation. Further, by making the thermal shrinkage stress at 90 ℃ 5.000N/mm²As described below, peeling and breakage of the wafer due to stress generated in the wafer bonding surface by shrinkage can be reduced. From the above viewpoint, the thermal shrinkage stress at 90 ℃ in the X-direction and Y-direction is 0.030N/mm²Above and 4.000N/mm²The above is more preferable, and the content is 0.050N/mm²Above and 3.300N/mm²The above is more preferable.

Here, the thermal shrinkage stress at 90 ℃ can be measured by the following method. First, a film of 15mm (measurement direction) × 4mm (direction orthogonal to the measurement direction) was left to stand at 25 ℃ for 24 hours in an atmosphere of 65% relative humidity to prepare a sample. Subsequently, the sample was heated from 25 ℃ to 160 ℃ at a heating rate of 10 ℃/min, and the thermal shrinkage stress at 90 ℃ was measured and set to 90 ℃. Further, the load at the start of the measurement was set to 5g/mm². The apparatus used for measuring the thermal shrinkage stress at 90 ℃ is not particularly limited and may be suitably selected as long as it can perform the above measurement, and for example, TMA/SS6000 (manufactured by セイコーインスツルメンツ) may be used.

The thermal shrinkage stress at 90 ℃ in the X direction and the Y direction is 0.010N/mm²Above and 5.000N/mm²The method below or within the above preferred range is not particularly limited as long as the effect of the present invention is not impaired, and for example, a method of forming a layer having a glass transition temperature of-30 ℃ to 40 ℃ inclusive and 1.04 ℃ inclusive by a cast film having at least 1 layer of a layerA method of stretching at least one direction at a magnification of 2.00 times or more.

The film of the present invention preferably has a shrinkage of more than 1.00% and 10.00% or less when heated at 80 ℃ for 1 hour. With such a configuration, even in a heating step at a low temperature, deformation during heating can be reduced. When the shrinkage ratio is 1.00% or less when heated at 80 ℃ for 1 hour, it may be difficult to suppress the dimensional change during heating. When the shrinkage rate is more than 10.00% when heated at 80 ℃ for 1 hour, the resin may shrink when heated in a bonding process or the like, and the dimensional change may become large when heated in a subsequent semiconductor manufacturing process. The shrinkage rate when heated at 80 ℃ for 1 hour is more preferably 2.00% or more and 8.00% or less, and still more preferably 3.00% or more and 6.00% or less. The method of making the shrinkage rate when heated at 80 ℃ for 1 hour exceed 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, and for example, a method of stretching a cast film at a magnification of 1.40 times or more and 2.00 times or less in at least one direction may be mentioned.

The film of the present invention preferably has Ta and a 5% elongation stress Tb at 25 ℃ after heating at 90 ℃ for 10 minutes, which satisfy the following formula 3.

Formula 3: Tb/Ta is more than or equal to 0.85 and less than or equal to 1.30.

Tb/Ta satisfying formula 3 means that the change in elongation characteristics after heating is small. By adopting such a configuration, 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 still more 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-described 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 subjecting a cast film to a heat treatment at a temperature of 70 ℃ or more and the melting point of the film or less. The heat treatment may be performed by a conventionally known method such as roll annealing or tenter method, and stretching may be performed simultaneously with heating as long as the effects of the present invention are not impaired.

The maximum stress Ka at 50% elongation and the stress Kb at 50% elongation of the film of the present invention at 25 ℃ preferably satisfy the following formula 4.

Formula 4: Kb/Ka is more than or equal to 0.70 and less than or equal to 1.00.

The Kb/Ka satisfying the formula 4 means that the yield stress is small or substantially not generated when the film is elongated at room temperature. When the yield point stress is high, the degree of elongation is likely to be affected by uneven thickness and uneven stress at the center and end portions during expansion, and the uniformity of elongation in the plane may be reduced. Therefore, by adopting such a configuration, the uniformity of the 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 still more preferably 0.90 or more and 1.00 or less. The method of setting Kb/Ka in a preferred 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 in area magnification.

In the film of the present invention, the number of adhering foreign matters having a diameter of 100 μm or more is preferably 10/m from the viewpoint of reducing a decrease in yield in wafer dicing²Hereinafter, more preferably 2/m²The following. Here, the diameter of the foreign matter is a value when the distance between 2 points on the contour of the foreign matter is maximum. The number of the adhered foreign matters passing through the diameter of more than 100 mu m is 10/m²The generation of chipping can be suppressed at the time of wafer dicing, and the reduction in yield can be reduced. The number of the adhering foreign matters having a diameter of 100 μm or more is 10/m²The following method or the above-described preferred range of methods is not particularly limited as long as the effects of the present invention are not impaired, and examples thereof include a method of improving the cleanliness of a film forming chamber, a method of removing adhering foreign matters by providing a sticking roller or a dust collector in a film forming line, and a method of stretching in a hot air atmosphere using an oven. The lower limit of the number of adhered foreign matters having a diameter of 100 μm or more is preferably 0/m²Is most preferred.

The number of adhered foreign matters having a diameter of 100 μm or more can be measured by the following procedure. First, a visual inspection was performed in a dark room using reflected light from a 3-wavelength fluorescent lamp, and foreign substances on the film sample were extracted. In the observation of foreign bodiesIn the case of the foreign matter, the length of the major axis was measured by observing the foreign matter under magnification with an electron microscope, and only the foreign matter having the major axis length of 100 μm was extracted again. Then, the number of foreign matters adhering to the film sample having a diameter of 100 μm or more (number/m) was determined by dividing the number of extracted foreign matters by the area of the film sample²)。

In the film of the present invention, the thickness unevenness is preferably 10.0% or less from the viewpoint of reducing a decrease in yield in wafer dicing. By setting the thickness unevenness to 10.0% or less, the frequency of occurrence of chipping due to loosening at the time of wafer dicing becomes low, the decrease in yield is reduced, and the uniformity at the time of expansion is improved. From the above viewpoint, it is more preferable if the thicknesses are not all 8.0% or less. The method of adjusting the thickness unevenness to 10.0% or less or the above-described 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 stretching at a stretch ratio of 1.04 times or more and 2.00 times or less. By stretching under such conditions, the thickness unevenness can be reduced while suppressing a decrease in flexibility. If the stretch ratio is less than 1.04, the thickness unevenness of the cast film is not easily eliminated, and if the stretch ratio is 2.00 times or more, the thickness unevenness may be enlarged. The smaller the thickness unevenness, the more preferable, and the lower limit thereof is 0.0% most preferable. As the stretching conditions, a method of reducing the stretching tension by setting the stretching temperature to 90 ℃ or higher and the melting point of the film or lower is also preferably used.

Next, a method for producing a film of the present invention will be described. The method for producing a film of the present invention is characterized by comprising a step of stretching at least one direction at a magnification of 1.04 times or more and 2.00 times or less. By doing so, the dimensional stability during heating is improved. From the above viewpoint, the step of stretching at least one direction at a magnification of 1.20 times or more and 1.80 times or less is preferable, and the step of stretching at least one direction at a magnification of 1.40 times or more and 1.70 times or less is more preferable. In the method for producing a film of the present invention, the film may be biaxially stretched as long as the effects of the present invention are not impaired.

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

First, the polyester was fed to a twin-screw extruder to be melt-extruded. In this case, it is preferable that the oxygen concentration in the extruder is controlled to 0.7 vol% or less under a nitrogen gas atmosphere, and the extrusion temperature is controlled to 20 to 30 ℃ higher than the melting point of the polyester. Subsequently, foreign matters were removed and the extrusion amount was made uniform by a filter and a gear pump, and the mixture was discharged from the T-die in a sheet-like manner on a cooling drum. In this case, the sheet-like polymer is brought into close contact with the casting drum and cooled and solidified to obtain a cast film by an electrostatic application method in which a cooling drum is brought into close contact with the resin by static electricity using an electrode to which a high voltage is applied, a casting method in which a water film is provided between the casting drum and the extruded polymer sheet, a method in which the extruded polymer is adhered by setting the temperature of the casting drum to a temperature of not less than-20 ℃ and not more than the glass transition temperature of the polyester, or a method in which a plurality of these methods are combined. Among these casting methods, the electrostatic application method is preferably used from the viewpoint of productivity and planarity.

In the method for producing a film of the present invention, stretching is performed at a magnification of 1.04 times or more and 2.00 times or less in at least a uniaxial direction for the purpose of imparting dimensional stability during heating. The stretching 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. When the film is biaxially stretched, the area magnification is preferably set to the above range. The stretching speed is desirably 100%/min or more and 200,000%/min or less. The stretching can be performed at any temperature of room temperature or higher, but is preferably 20 ℃ or higher and 160 ℃ or lower, and is preferably preheated for 1 second or higher before the stretching. Further, the stretching may be performed by a sequential biaxial stretching method of stretching the cast film in the width direction after stretching it in the length direction, or stretching it in the length direction after stretching it in the width direction, or a simultaneous biaxial stretching method of stretching it almost simultaneously in the length direction and the width direction of the film, or a uniaxial stretching method of stretching it only in the length direction or the width direction, or the like. Here, the longitudinal direction refers to a moving 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 performed in one stage or in multiple stages as long as the effects of the present invention are not impaired.

Further, heat treatment of the film may be performed after stretching. The heat treatment may be performed by any conventionally known method such as in an oven or a heated roll. The heat treatment is preferably performed at a temperature of not lower than the stretching temperature and not higher than the stretching temperature +50 ℃. The heat treatment temperature here means the highest temperature among heat treatment temperatures performed after stretching. The heat treatment time may be arbitrarily selected within a range that does not deteriorate the characteristics.

The heat-set film is cooled and then wound into an intermediate product roll. Further, the film may be unwound from the intermediate product roll, cut in parallel with the longitudinal direction so as to have a desired width, and wound to obtain a final product roll. In addition, the final product roll obtained from one intermediate product roll may be one or more.

The film of the present invention controls the stretching characteristics at room temperature and the dimensional change characteristics at high temperatures. Therefore, the film of the present invention has both flexibility and heat resistance, and can be suitably used as a substrate for a semiconductor production process or the like.

Examples

The present invention will be described in detail below with reference to examples. The properties were measured and evaluated by the following methods.

(1) Stress at 5% elongation Ta at 25 DEG C

The tensile strength was measured at 25 ℃ and 65% RH using a film tensile strength measuring apparatus (AMF/RTA-100) manufactured by オリエンテック (Ltd.) in accordance with JIS K7127(1999, test piece type 2). First, a sample cut into a size of 150mm in length and 10mm in width in any direction was stretched at a stretching speed of 300 mm/min to obtain a stress Ta at 5% elongation (unit: MPa). Further, 5 times of the same measurement were performed on one sample, and an average value was calculated. Further, the direction was changed clockwise by 5 ° and measured similarly, and the maximum value of the value in each direction of 0 ° to 175 ° was defined as the stress at 5% elongation ta (mpa) at 25 ℃.

(2)90 ℃ dimensional Change Rate 1(Tx1, Ty1)

First, a film sample cut into a size of 15mm (measurement direction) × 4mm (direction orthogonal to the measurement direction) in a room temperature environment was left standing at 25 ℃ for 24 hours in an atmosphere of a relative humidity of 65%, and the length (L) in the measurement direction was measured₀). Next, the film sample was subjected to a load of 120g/mm²The temperature was raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/min, and the length (L) in the measurement direction at 90 ℃ was measured₁). From the obtained L₀And L₁The 90 ℃ dimensional change rate 1 of the film sample was determined by the following formula 5.

Formula 5: 90 ℃ dimensional Change ratio 1 (%) - (L)₁-L₀)×100/L₀。

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

(3)90 ℃ dimensional Change Rate 2(Tx2)

The load during the measurement was set to 5g/mm²The measurement was performed in the same manner as in the method described in (2) except that the measurement direction was set to the X direction, and the obtained value was Tx2 (%). The X direction here is the same as the X direction specified in (2).

(4) Coefficient of plane orientation

The refractive index in each direction of the film was measured using an abbe refractometer 4T manufactured by アタゴ (ltd.) equipped with a polarizer, and the plane orientation coefficient was obtained by the following equation. The light source used halogen lamp, the upper prism used prism with refractive index of 1.740, and the immersion liquid used diiodomethane(refractive index 1.740). In addition, the measurement was performed on both surfaces of the film in an environment in which temperature and humidity were controlled at 23 ℃ and 65 RH% for 24 hours. First, the refractive index (n α, n β, n γ) in each direction was measured with an abbe refractometer, where α is an arbitrary direction parallel to the film surface, β is a direction orthogonal to the direction in the film surface, and γ is a direction (thickness direction) orthogonal to α and β. Using the obtained values, the plane orientation coefficients (fn) were obtained by the following equation 6 for 2 directions on the film surface, which are α and β₀)。

Formula 6: fn₀＝(nα+nβ)/2-nγ。

Then, γ is fixedly set as n β 05 and n β 15 by rotating α and β clockwise by 5 ° while maintaining the parallelism with the film surface, refractive indices (n α 5, n β 5, n γ) in each direction are measured by an abbe refractometer, n α of the above formula 6 is replaced with n α 5, n β is replaced with n β 5, and the plane orientation coefficient (fn) when 2 directions on the film surface are α 5 and β 5 is obtained₅). Hereinafter, the same measurement was repeated in the same manner until 2 directions on the film surface became α 85 and β 85. The obtained fn₀～fn₈₅The average of the 18 measurements was set as the plane orientation coefficient (fn).

(5) Glass transition temperature of each layer

The measurement results were calculated from the following formula 7 by using differential calorimetry (DSC) and keeping the sample at-120 ℃ for 5 minutes under a nitrogen atmosphere in accordance with JIS K7121(2012) and then raising the temperature of the measurement sample to 250 ℃ at a rate of 20 ℃/minute.

Formula 7: glass transition temperature (extrapolated glass transition start temperature + extrapolated glass transition end temperature)/2

The device comprises the following steps: セイコー electronic engineering (Inc.) ロボット DSC-RDC220

A data analysis system: ディスクセッション SSC/5200

Sample quality: 5mg of

When the film had a laminate structure, first, a film cut out with a microtome was cut out using a transmission electron microscope H-7100FA model (manufactured by Hitachi, Ltd.) under an acceleration voltage of 75kVThe cross section in the thickness direction of (2) was enlarged to 40,000 times, and the layer composition was specified and the thickness of each layer was measured. In addition, RuO is used to improve the contrast of each layer according to circumstances₄And OsO 4. From the obtained thickness values of the respective layers, samples of deep portions corresponding to the respective layers were collected, and the glass transition temperatures of the respective layers were measured by the above-described method.

When a plurality of glass transition temperatures are confirmed as a result of the measurement, a value obtained by the following method is used 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 and Tg2 … … Tgn in order of lower temperature. Subsequently, tan δ was obtained for each temperature of the film in accordance with JIS K7244(1999) using a dynamic viscoelasticity measurement device "DMS 6100" manufactured by セイコーインスツルメンツ, and the temperatures giving the maximum values were assigned to Tg1 and Tg2 … … Tgn in order of decreasing. When the values corresponding to the respective layers are separated from each other among Tg1 and Tg2 … … Tgn, the temperature at which the value of tan δ is the largest is used as the glass transition temperature of the layer. The measurement conditions for the dynamic viscoelasticity measurement were a tensile mode, a driving frequency of 1Hz, a distance between chucks of 5mm, and a temperature rise rate of 2 ℃/min.

(6) Specific layer constitution

From the glass transition temperatures of the respective layers of the film measured in (5), the a layer and the other layers (expressed as B layer.) were specified.

(7) Coefficient of static friction

Using an imperial レ type sliding tester 200G-15C (MAKINO SEISAKUSHO), 2 films were arranged so that one surface was in contact with the opposite surface in accordance with JIS K7125(1999), and the values at this time were measured 3 times and the average value was taken as the static friction coefficient.

(8) Surface roughness SRa, ten point average roughness SRzjis

The 3-dimensional surface roughness of the sample surface was measured under the following conditions using a high-precision fine shape measuring instrument (3-dimensional surface roughness meter) by the stylus method in accordance with JISB0601 (2001). Then, the surface roughness SRa and the ten-point average roughness SRzjis were calculated by using an analysis system (model TDA-31) incorporated in the measuring instrument.

A measuring device: 3-dimensional Fine shape measuring apparatus (model ET-4000A) (Katsuka research Ltd.)

Analyzing equipment: 3D surface roughness analytic system (model TDA-31)

A stylus: diamond with a radius of 0.5 μm R at the tip and a diameter of 2 μm

Acupressure: 100 mu N

Measuring direction: the film length direction and the film width direction were each 1 time (average value of both was calculated after measurement)

X measurement of length: 1.0mm

X conveying speed: 0.1mm/s (measuring speed)

Y conveying distance: 5 μm (measurement gap)

Number of Y lines: 81 strips (number of strips)

Z multiplying power: 20 times (longitudinal multiplying power)

Low-range cutoff: 0.20mm (undulation cut-off value)

High-field cutoff: r + Wmm (roughness cut-off), and R + W means not cut-off.

Filter mode: gaussian spatial pattern

Correcting: is (inclination correction)

Area of reference: 1mm²。

(9) Thermal shrinkage stress at 90 DEG C

A film of 15mm (measurement direction). times.4 mm (direction orthogonal to the measurement direction) left standing at 25 ℃ and a relative humidity of 65% for 24 hours was L-assembled in a controlled manner using TMA/SS6000 (manufactured by セイコーインスツルメンツ) to raise the temperature from 25 ℃ to 160 ℃ at a temperature rise rate of 10 ℃/min, and the thermal shrinkage stress at 90 ℃ was determined. Further, the load at the start of the measurement was set to 5g/mm². The measurement directions are specified as the X direction and the Y direction in (2).

(10) Shrinkage when heated at 80 ℃ for 1 hour

The film was heated at 80 ℃ for 1 hour, and the size before heating and the size after heating were calculated from the following formula 8. The respective dimensions were measured by the method defined in JIS K7133 (1999).

Formula 8: shrinkage (%) (dimension before heating-dimension after heating)/dimension before heating × 100.

(11) Stress at 5% elongation Tb at 25 ℃ after heating at 90 ℃ for 10 minutes

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

(12) The ratio of the maximum stress Ka at 50% elongation to the stress Kb at 50% elongation at 25 DEG C

A tensile test of the film was carried out by the method described in (1), and a stress at 50% elongation was obtained. Further, the maximum stress at 50% elongation was read from the maximum value of the stress value in the region where the elongation of the stress-strain curve obtained by the measurement is 50% or less. The same measurement was performed 5 times using samples in the same measurement direction, and the average values of the stress at 50% elongation and the maximum stress at 50% elongation were calculated, and the obtained values were taken as the maximum stress Ka at 50% elongation and the stress Kb at 50% elongation in the measurement direction, and the ratio (Kb/Ka) of Ka and Kb in the direction was calculated. Further, the same measurement was repeated while changing the measurement direction clockwise by 5 °, and the ratio of Ka to Kb in each direction from 0 ° (initial measurement direction) to 175 ° was calculated, and the average value of all directions was used.

(13) The number of foreign matters adhering to the surface of the substrate having a diameter of 100 μm or more

A film of 1m (width direction) × 10m (length direction) was cut out as a sample at the center in the width direction of the rolled sample, and visual inspection was performed in a dark room using the reflected light of a 3-wavelength fluorescent lamp. When foreign matter was observed, the foreign matter was observed with an electron microscope (manufactured by LEICA DMLM ライカマイクロシステムズ K) at a magnification of 100 times, and the length of the long diameter of the foreign matter was measured by the length measuring function of the microscope. The number of foreign matters having a length of 100 μm or more in the major axis is C, and the number of foreign matters adhering to a diameter of 100 μm or more is calculated by the following formula 9Mesh (mu/m)²). In addition, when the size of the film is smaller than the above size, the entire film was visually inspected as a sample.

Formula 9: the number of foreign matters adhering to the surface of the substrate having a diameter of 100 μm or more (number/m)²) C (one)/10 (m)²)。

(14) Uneven thickness

The film was cut out into 10 pieces of 10cm × 10cm from the center and both ends in the width direction of the rolled sample, and the cut pieces were used as samples for evaluation. For each sample, the thickness was measured at 5 points in the longitudinal direction and at 5 points in the width direction for 10 points in total, and the thickness unevenness was determined from the average value, the maximum value, and the minimum value thereof according to the following formula 10.

Formula 10: thickness variation (%) (maximum value of thickness-minimum value of thickness)/average value of thickness

The values of the thickness unevenness of the 10 samples at the obtained position 3 in the width direction (both end portions and the central portion) were calculated as average values and used as the thickness unevenness. When the film is a sheet sample, 30 pieces of 10cm × 10cm are cut at an arbitrary position on the sheet, and the average value of the thickness unevenness of each sample is calculated and used as the thickness unevenness.

(15) Uniform stretchability

Randomly cut out films of 300mm × 300mm squares were measured by drawing 9 lines at 30mm intervals parallel to one side, and drawing 9 lines at 30mm intervals parallel to the other side. The obtained measurement sample was stretched in a direction parallel to one side and in a direction parallel to the other side using a simultaneous biaxial stretching apparatus under the following conditions, and evaluated from the interval of straight lines according to the following criteria. In addition, as for the interval of the straight lines, 6 intervals (12 intervals in total in 2 directions) formed by 7 straight lines excluding 2 straight lines at both ends were measured in each direction, and the value farthest from 39mm was used as the measurement value. The uniform stretchability was defined as B or more.

< stretching Condition >

A stretching device: KARO IV ラボストレッチャー manufactured by BRUCKNER

Stretching temperature: 25 deg.C

Stretching speed: 10 mm/min

Stretching ratio: 1.30 times.

< evaluation Standard >

S: the interval of the straight lines in the stretched film was 39. + -.1 mm.

A: does not conform to S, and the interval of straight lines in the stretched film is 39. + -.3 mm.

B: the interval of the straight lines in the stretched film was 39. + -.6 mm, which did not conform to S and A.

C: does not conform to either of S and A, and B.

(16) Uniform stretchability after heating

A film of 300 mm. times.300 mm square cut out at will was subjected to a heat treatment at 90 ℃ for 10 minutes, and then similarly evaluated by the method described in (15).

(17) Dimensional stability at 90 ℃ (Heat resistance)

A double-sided tape No.500AB manufactured by Rituer computer was used as a measurement sample by sticking a square film of 200 mm. times.200 mm cut out arbitrarily to a metal frame made of stainless steel (outer side: 200 mm. times.200 mm, inner side: 180 mm. times.180 mm). Next, the measurement sample was allowed to stand on a hot plate heated to 90 ℃ so that the film attached to the metal frame was in contact with the heated surface, and the amount of floating up from the reference plane was measured after the sample was left for 240 minutes. From the results obtained, dimensional stability was evaluated by the following criteria. In the measurement of the floating height, the reference plane is set as the heating surface of the electric heating plate. The measurement was performed with the thickness of the metal frame used being 1mm, 2mm, 3mm, and when the sample was observed from a horizontal position, the thickness of the metal frame in which the deformed film could not be observed was used, and when the film could be observed even in the case of the metal frame having the thickness of 3mm, the C evaluation was used. Regarding the dimensional stability, B or more is defined as being acceptable.

S: the floating height of the film is less than 1 mm.

A: does not conform to S, and the floating of the film is less than 2 mm.

B: does not conform to S and A, and the floating of the film is 3mm or less.

C: does not conform to either of S and A, and B.

(18) Dimensional stability at 120 ℃ (Heat resistance)

The same procedure as described in (17) was carried out except that the temperature of the electric heating plate was set to 120 ℃, and the heat resistance was evaluated.

(19) Quality of the product

From the center position in the width direction and the both end positions in the width direction of the sample collected in (13), 10 pieces of the film sample of 200mm × 200mm were cut out, and 30 pieces were counted. All samples were observed with an optical microscope at a magnification of 100 times in a field of 10, and the presence or absence of a flaw having a length of 1 μm or more was confirmed. The number of fields in which damage of 1 μm or more in length was observed was defined as the number of fields in which damage of 1 μm or more in length was observed, which was rounded at the 1 st digit after the decimal point of the average value of the number of fields in which damage of 1 μm or more in length was observed in each sample. The quality was evaluated by the following criteria based on the number of attached foreign matter having a diameter of 100 μm or more measured in (13) and the number of fields where damage having a length of 1 μm or more was observed. In addition, when the number of fields in which damage of 1 μm or more in length is observed and the number of adhering foreign matter of 100 μm or more in diameter are evaluated differently (for example, when the former is a and the latter is B), the difference evaluation (B) is used.

S: the number of fields of view of a damage of 1 μm or more in length is observed to be 0, and the number of adhering foreign matter of 100 μm or more in diameter exceeds 0 and is 5 or less.

A: the number of fields of view of a lesion having a length of 1 μm or more was observed to be 1. Or more than 5 and 8 or less adhering foreign matters having a diameter of 100 μm or more.

B: the number of fields of view for which a damage having a length of 1 μm or more is observed is 2 to 3. Or more than 8 and 10 or less adhering foreign matters having a diameter of 100 μm or more.

C: the number of fields of view of a lesion having a length of 1 μm or more is 4 or more. And/or the number of adhering foreign matters having a diameter of 100 μm or more is more than 10.

(20) Adhesion Property

An adhesive layer composition solution (adhesive: 100 parts by mass of acrylate resin partial pressure-sensitive adhesive "ニッセツ" (registered trademark) "KP-2369" manufactured by Japan カーバイド, Inc. , Inc./2 parts by mass of crosslinking agent "CK-131") was applied to the surface of a square film of 200mm × 200mm arbitrarily cut out so as to have a thickness of about 10 μm by a wire bar coating method, and then dried at 100 ℃ for 1 minute in a hot air OVEN HIGH-TEMP-OVEN PHH-200 manufactured by エスペック, and allowed to stand at room temperature of 25 ℃ under an atmosphere of 65% relative humidity for 3 days. The sample thus obtained was cut into a size of 150mm × 30mm, and subjected to 50% elongation at a speed of 300 mm/min at room temperature and 25 ℃ using a film tensile elongation measuring apparatus (AMF/RTA-100) manufactured by Tokyo オリエンテック. Then, an acrylic adhesive tape (ニットー 31B (manufactured by daily chinese corporation)) was bonded to the adhesive surface with a rubber roll and pressure-bonded with a 5kg pressure-bonding roll, and after leaving for 24 hours, the acrylic adhesive tape was cut out to a width of 10mm as a sample for evaluation, and the end of the acrylic adhesive tape of the sample for evaluation was folded back to 180 °, and the peel strength was measured with a tensile tester and evaluated by the following criteria.

S: the peel strength is 10N/25mm or more.

A: the peel strength is 8N/25mm or more and less than 10N/25 mm.

B: the peel strength is 6N/25mm or more and less than 8N/25 mm.

C: the peel strength is less than 6N/25 mm.

(resin)

The resins used for the production of the film are as follows.

(polyester A)

Using antimony trioxide as a catalyst, polymerization was carried out from terephthalic acid and ethylene glycol by a conventional method to obtain polyester A having an intrinsic viscosity of 0.65.

(polyester B)

A polyethylene terephthalate particle master batch having an intrinsic viscosity of 0.65 of aggregated silica particles having a volume average particle diameter of 4.5 μm was contained in polyester A at a particle concentration of 10 mass%.

(polyester C)

PBT-polyether copolymer "ハイトレル" (registered trademark) 5557 manufactured by "DONG レ - デュポン" DONG "Inc.)

(polyester D)

Polybutylene terephthalate with an intrinsic viscosity of 0.8

(polyester E)

PBT-polyether copolymer "ハイトレル" (registered trade Mark) 3001 manufactured by "Dow レ - デュポン" DONG "PAINT

(polyolefin A)

TF850H manufactured by crystalline Polypropylene プライムポリマー K.K.)

(polyolefin B)

Ethylene-octene-1 copolymer デュポン ダ ウ "エンゲージ" (registered trademark) EG8200

(polyolefin C)

Hydrogenated styrene/butadiene copolymer (HSBR) "DYNARON" (registered trademark) 1320P available from JSR.

(example 1)

The raw materials for obtaining the a layer adjusted to the composition shown in table 1 were supplied to a twin-screw extruder having an oxygen concentration of 0.2 vol%. The raw material for obtaining the layer a was melted with the cylinder temperature of the twin-screw extruder set to 270 ℃, fed to a T-die through a short tube and a die set at a temperature of 270 ℃, and discharged from the T-die in a sheet form onto a cooling drum controlled to a temperature of 25 ℃. At this time, electrostatic application was performed using a linear electrode having a diameter of 0.1mm, and the electrostatic application was closely adhered to a cooling drum to obtain a casting film (casting film). Subsequently, the film was stretched at a ratio of 1.44 times in both the longitudinal direction and the width direction at a preheating temperature of 80 ℃ and a stretching temperature of 90 ℃ by a simultaneous biaxial stretching apparatus, and then, dust on both surfaces of the film was removed by a dust collector to obtain a single layer film having a total thickness of 180 μm. The evaluation results of the properties are shown in table 1.

(examples 2 to 14, 18 to 28, 34, 36 to 38, and 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, the extrusion temperature, and the stretching conditions were as shown in tables 1 to 6. The evaluation results of the properties are shown in tables 1 to 6. In addition, the a layer did not exist in examples 18 and 19, and thus the "raw material for obtaining the a layer" in example 1 was changed to "raw material for obtaining the B layer".

(example 15)

A casting film was obtained in the same manner as in example 8. Subsequently, the film was stretched at a ratio of 1.44 times in both the longitudinal direction and the width direction at a preheating temperature of 100 ℃ and a stretching temperature of 120 ℃ by a simultaneous biaxial stretching apparatus, and then heat-treated in a region heated to 130 ℃ for 10 seconds, and dust on both surfaces of the film was removed by a dust collector before winding, thereby obtaining a single-layer film having a total thickness of 180 μm. The evaluation results of the properties are shown in table 3.

(example 16)

The film structure was as shown in table 3. The raw materials for obtaining the a1 layer and the raw materials for obtaining the a2 layer shown in table 3 were respectively supplied to respective twin-screw extruders having an oxygen concentration of 0.2 vol%. The cylinder temperature of each extruder was 270 ℃, the raw materials were melted and joined, passed through a short tube and a neck mold at a temperature of 270 ℃ to be fed to a T-die, and discharged from the T-die in a sheet-like manner onto a cooling drum controlled to a temperature of 25 ℃. Then, a laminated film having a total thickness of 180 μm was obtained in the same manner as in example 1. The evaluation results of the properties are shown in table 3.

(example 17)

The film structure was as shown in table 3. The raw materials for obtaining the a layer and the raw materials for obtaining the B layer shown in table 3 were respectively fed to respective twin-screw extruders having an oxygen concentration of 0.2 vol%. The cylinder temperature of the extruder supplied with the raw material for obtaining the a layer and the cylinder temperature of the extruder supplied with the raw material for obtaining the B layer were both set to 260 ℃, and the respective raw materials were melted and merged, passed through a short tube and a die set at a temperature of 260 ℃ to be fed to a T-die, and discharged from the T-die in a sheet-like manner onto a cooling drum controlled to a temperature of 25 ℃. 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 changed to the temperature shown in table 3. The evaluation results of the properties are shown in table 3.

(examples 29 to 33)

A casting film was obtained in the same manner as in example 1. Subsequently, the film was stretched at a preheating temperature of 80 ℃ and a stretching temperature of 90 ℃ at a ratio shown in Table 5 in the longitudinal direction by a roll stretcher, and then stretched at a preheating temperature of 80 ℃ and a stretching temperature of 90 ℃ at a ratio shown in Table 5 in the width direction by a tenter stretcher, and then dust on both surfaces of the film was removed by a dust remover to obtain a single-layer film having a total thickness of 180 μm. The evaluation results of the properties are shown in table 5.

(example 35)

A casting film was obtained in the same manner as in example 1. Subsequently, the film was stretched at a preheating temperature of 80 ℃ and a stretching temperature of 90 ℃ at a ratio shown in Table 5 in the longitudinal direction by a roll stretcher, and then stretched at a preheating temperature of 80 ℃ and a stretching temperature of 90 ℃ at a ratio shown in Table 5 in the width direction by a tenter stretcher, to obtain a single-layer film having a total thickness of 180 μm. The evaluation results of the properties are shown in table 5.

(example 39)

Cast films were obtained in the same manner as in example 1, except that the composition of the raw material for obtaining the a layer was as shown in table 6. Subsequently, the film was stretched at a preheating temperature of 100 ℃ and a stretching temperature of 120 ℃ by a simultaneous biaxial stretcher at a ratio of 1.44 times in both the longitudinal direction and the width direction and then held for 3 seconds, and then dust on both surfaces of the film was removed by a dust remover to obtain a single-layer film having a total thickness of 180 μm. The evaluation results of the properties 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, the extrusion temperature, and the stretching conditions were changed as shown in table 7. The evaluation results of the properties are shown in table 7. The "minus" in the drawing manner in comparative examples 2 and 5 means that the drawing itself is not performed.

[ Table 1]

The resin composition in the film composition was calculated assuming that the entire resin components constituting each layer were 100 mass%. The D surface is a surface that comes into contact with the casting drum during film formation, and the ND surface is a surface opposite to the D surface. The same is true for tables 2 to 7.

[ Table 2]

[ Table 3]

[ TABLE 3]

Since example 16 is a film having 3 layers of 2 kinds of layers corresponding to the a layer, each layer is described as a layer a1 and a layer a 2.

[ Table 4]

[ Table 5]

[ TABLE 5]

[ Table 6]

[ TABLE 6]

[ Table 7]

[ TABLE 7]

Industrial applicability

The present invention provides 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 substrate for a semiconductor production process.

Claims (16)

1. A film characterized in that the film has a stress Ta at 5% elongation at 25 ℃ of 1.0MPa or more and 20.0MPa or less,

when a load of 120g/mm is applied²And Tx1 is-10.00% or more and 10.00% or less when the dimension change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/min is defined as 90 ℃ dimension change rate 1, the direction in which 90 ℃ dimension change rate 1 is the largest is defined as the X direction, the direction orthogonal to the X direction within the film surface is defined as the Y direction, the 90 ℃ dimension change rate in the X direction is defined as Tx1, and the unit of Tx1 is% or less,

the resin used for the film is polyester and/or polyolefin.

2. The film of claim 1, wherein the film is subjected to a load of 5g/mm²And when the dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature rise rate of 10 ℃/min is defined as 90 ℃ dimensional change rate 2, and the 90 ℃ dimensional change rate 2 in the X direction is defined as Tx2 and the unit of Tx2 is% the Tx2 is-10.00% or more and 1.00% or less.

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

4. The film according to claim 1 or 2, wherein the film has 1 or more a layers when the layer having a glass transition temperature of-40 ℃ or more and 40 ℃ or less is the a layer.

5. The film according to claim 1 or 2, wherein the Tx1 and Ty1 satisfy the following formula 1, where Ty1 is the 90 ℃ dimensional change rate 1 in the Y direction and% is the unit of Ty1,

formula 1: the absolute value Tx1-Ty1 is more than or equal to 0.10 and less than or equal to 3.00.

6. The film according to claim 1 or 2, wherein the static friction coefficient measured by overlapping different surfaces of the film with each other is 0.10 or more and 0.80 or less.

7. The film according to claim 1 or 2, wherein the surface roughness SRa and the ten-point average roughness SRzjis satisfy the following formula 2 on at least one side,

formula 2: 5.0 or more and SRzjis/SRa or less and 25.0, wherein the unit of SRa and SRzjis is mu m.

8. The film according to claim 1 or 2, wherein the thermal shrinkage stress at 90 ℃ in the X-direction and the Y-direction is 0.010N/mm²Above and 5.000N/mm²The following.

9. The film according to claim 1 or 2, wherein the shrinkage when heated at 80 ℃ for 1 hour is more than 1.00% and 10.00% or less.

10. The film according to claim 1 or 2, wherein said Ta and a stress at 5% elongation Tb at 25 ℃ after heating at 90 ℃ for 10 minutes satisfy the following formula 3,

formula 3: Tb/Ta is more than or equal to 0.85 and less than or equal to 1.30.

11. The film according to claim 1 or 2, wherein the maximum stress Ka at 50% elongation and the stress Kb at 50% elongation at 25 ℃ satisfy the following formula 4,

formula 4: Kb/Ka is more than or equal to 0.70 and less than or equal to 1.00.

12. The film according to claim 1 or 2, wherein the 90 ℃ dimensional change rate 1 in all directions is from-25.00% to 10.00%.

13. The film according to claim 1 or 2, wherein the 90 ℃ dimensional change rate 2 in all directions is from-25.00% to 1.00%.

14. The film according to claim 1 or 2, wherein the number of adhering foreign matters having a diameter of 100 μm or more is 10/m²The following.

15. The film of claim 1 or 2, wherein the thickness is not all 10.0% or less.

16. A method for producing a film according to any one of claims 1 to 15, characterized by comprising a step of stretching the film in at least one direction at a magnification of 1.04 times or more and 2.00 times or less.