阅读说明：本技术 膜及膜的制造方法 (Film and method for producing film ) 是由 荘司秀夫 田中照也 真锅功 于 2018-04-16 设计创作，主要内容包括：一种膜,其特征在于,25℃下的5％伸长时应力Ta为1.0MPa以上且20.0MPa以下,在将施加荷重120g/mm<Sup>2</Sup>,且以10℃/分钟的升温速度从25℃升温至160℃时的90℃下的尺寸变化率设为90℃尺寸变化率1,将90℃尺寸变化率1最大的方向设为X方向,将与X方向在膜面内正交的方向设为Y方向,将X方向的90℃尺寸变化率设为Tx1(％)时,Tx1为-10.00％以上且10.00％以下。提供具备在加热工序中能够维持平面性的程度的耐热性、和对于作为切割用粘着膜等使用而言充分的柔软性的、适合作为半导体制造工序用基材的膜。(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/mm 2 And the dimensional change rate at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/min is set to 90 ℃ dimensional change rate 1, the direction in which 90 ℃ dimensional change rate 1 is the largest is set to the X direction, the direction orthogonal to the X direction in the film surface is set to the Y direction, and the film is formed by the methodWhen the 90 ℃ dimensional change rate in the X direction is Tx1 (%), Tx1 is-10.00% or more and 10.00% or less. 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.)

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% to 10.00% 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 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, the 90 ℃ dimensional change rate in the X direction is defined as Tx1, and the unit of Tx1 is% inclusive.

2. The film of claim 1, wherein the film is subjected to a load of 5g/mm²And Tx2 is-10.00% or more and 1.00% 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 2, the 90 ℃ dimensional change rate 2 in the X direction is defined as Tx2, and the unit of Tx2 is defined as% >.

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 any one of claims 1 to 3, wherein the film has 1 or more A layers when the layer having a glass transition temperature of-40 ℃ or higher and 40 ℃ or lower is the A layer.

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

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 any one of claims 1 to 5, wherein the 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 claims 1 to 6, 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 any one of claims 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 claims 1 to 8, 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 any one of claims 1 to 9, wherein the Ta and the 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 any one of claims 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 claims 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 claims 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 claims 1 to 13, wherein the number of adhered foreign matters having a diameter of 100 μm or more is 10/m²The following.

15. The film of any one of claims 1-14, 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 at least one direction at a magnification of 1.04 times or more and 2.00 times or less.

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 or 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 manufacturing 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).

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 stress Ta at 5% elongation at 25 ℃ is 1.0MPa or more and 2Under 0.0MPa, under the applied load 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 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 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 at 90 ℃ when the temperature is raised from 25 ℃ to 160 ℃ at a temperature raising rate of 10 ℃/minWhen the dimensional change rate of (2) is 90 ℃ dimensional change rate 1, the direction in which the 90 ℃ dimensional change rate 1 is the largest is the X direction, the direction perpendicular to the X direction within the film surface is the Y direction, and the 90 ℃ dimensional change rate in the X direction is Tx1 (%), Tx1 is-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 invention is to be appliedLoad 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 still more preferable if it is-4.50% or more and-1.00% or less.

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 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 measurement was performedLength in definite direction (L)₀). 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/mm²In addition toThe dimensional change rate was measured by the same method as that for the 90 ℃ dimensional change rate 1, and the same apparatus as that for the 90 ℃ dimensional change rate 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 a configuration, even when the semiconductor wafer is heated in a state where a small load is applied to the film by stacking the semiconductor wafers, excessive deformation of the film can be suppressed, and thus 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 α 5 and n β 5 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 of the 18 measurements 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 viewpoint 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 of adjusting the glass transition temperature of the a layer to-40 ℃ or higher and 40 ℃ or lower or the above-described preferred range is not particularly limited as long as the effect of the present invention is not impaired, but as the resin constituting the a layer, a method of using a resin having a glass transition temperature of-40 ℃ or higher and 40 ℃ or lower or within the above-described preferred range can be cited. 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 by Tx1 and Ty1 when the 90 ℃ dimensional change rate 1 in the Y direction is Ty1 (%).

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) on at least one side satisfying the following formula 2.

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. Further, when SRzjis/SRa is less than 5.0, it is difficult to realize the SRzjis/SRa in a production method which is generally used because slippage occurs during film formation, and blocking or the like may occur even when the slip is realized. 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 surface shape due to scraping in the process can be reduced. As a method of adjusting SRzjis/SRa to 5.0 or more and 25.0 or less or the preferable range described above, a method of setting the stretching to multiple stages of 2 stages or more and a method of performing simultaneous biaxial stretching may be employed.

The film of the present invention preferably has a thermal shrinkage stress of 0.010N/mm at 90 ℃ in the X-direction and Y-direction²Above 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, 15mm (measurement direction) × 4mm (square orthogonal to the measurement direction) was measuredTo) was left standing at a temperature of 25 ℃ for 24 hours in an atmosphere of 65% relative humidity to obtain 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 in the above-mentioned preferred range is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include a method in which a cast film having at least 1 or more a layers is used to set the glass transition temperature of the a layer to-30 ℃ or more and 40 ℃ or less, and the a layer is stretched in at least one direction at a magnification of 1.04 times or more and 2.00 times or less.

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 effect of the present invention is 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. The diameter of the foreign matter here means the outline of the foreign matterAnd the distance between 2 points above and the value is the maximum value. The number of the foreign matters passing through the adhesive film is 10/m²The occurrence 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. When foreign matter was observed, 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 a major axis length of 100 μm was extracted again. Then, the number of foreign matters adhered to the film sample was determined by dividing the number of extracted foreign matters by the area of the film sample to obtain the number of foreign matters adhered to the film sample having a diameter of 100 μm or more (number/m)²)。

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 on a cooling drum in a sheet form. 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.