JP7465690B2 - Base film for backgrind tape - Google Patents

Description

The present invention relates to a base film for backgrinding tape used to secure a semiconductor wafer when grinding the back surface of the semiconductor wafer (hereinafter referred to as "backgrinding").

When producing semiconductor chips, a fixing film (adhesive tape) is used to fix the semiconductor wafer. After use, this fixing film is peeled off from the semiconductor wafer.

Processes for fixing a semiconductor wafer using a fixing film include the backgrinding process, in which the back surface of the semiconductor wafer is ground, and the dicing process, in which the semiconductor wafer is cut and separated into chips. In the backgrinding process, the semiconductor wafer is adjusted (thinned) to the desired thickness. At this time, a backgrinding film is attached to the patterned surface of the semiconductor wafer in order to protect the patterned surface of the semiconductor wafer. The backgrinding film is composed of a base film layer and an adhesive layer, and the semiconductor wafer is adhered via the adhesive layer.

Patent Document 1 is the applicant's technology, and discloses a base film for backgrinding that is less likely to warp the semiconductor wafer during the backgrinding process of thin semiconductor wafers, has excellent dimensional stability, and can effectively suppress blocking when the base film is wound up.

Patent No. 5489501

The objective of the present invention is to provide a new base film for backgrind tape.

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

Item 1.
A base film for a backgrind tape, comprising:
At least an A layer and a B layer are included,
The A layer is made of a resin composition containing a polyester-based resin,
The B layer is made of a resin composition containing a soft polyester resin.
Base film for backgrind tape.

Item 2.
Item 2. The base film for a backgrind tape according to item 1, wherein the soft polyester resin has a polyester unit and a polyester polyol unit.

The base film for the backgrinding tape of the present invention can be preferably used as a backgrinding film for use in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (approximately 25 μm).

The base film for the backgrinding tape of the present invention has the effect of preventing warping of the semiconductor wafer during the backgrinding process of thin semiconductor wafers.

The substrate film for backgrinding tape of the present invention exhibits excellent peelability when peeling off the surface protection tape (adhesive tape for backgrinding).

The present invention can provide a new substrate film for backgrinding tape that has appropriate hardness.

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

(1) Base film for backgrind tape The base film for the backgrind tape of the present invention is
At least an A layer and a B layer are included,
The A layer is made of a resin composition containing a polyester-based resin,
The layer B is made of a resin composition containing a soft polyester resin.

(1-1) Layer A of the Base Film Layer A of the base film for the backgrind tape of the present invention is made of a resin composition containing a polyester-based resin.

Polyester Resin As the polyester resin, it is preferable to use one obtained by polycondensing, for example, a dicarboxylic acid and a diol.

The dicarboxylic acid is not particularly limited, and preferably, for example, o-phthalic acid, terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, octyl succinic acid, cyclohexane dicarboxylic acid, naphthalenedicarboxylic acid, fumaric acid, maleic acid, itaconic acid, decamethylene carboxylic acid, anhydrides thereof, and lower alkyl esters thereof are used.

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

Among the polyester-based resins, those that contain a component derived from terephthalic acid as the dicarboxylic acid component and a component derived from ethylene glycol as the diol component are preferred. By using such polyester-based resins, heat resistance can be imparted.

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

When laminating with a soft polyester resin, the diol component of the polyester resin used when productivity and moldability are to be improved is 100 mol%. The content of the diol component is 100 mol%, and the preferred lower limit of the content of the component derived from ethylene glycol is 50 mol%, more preferably 60 mol%, and the preferred upper limit is 100 mol%, and more preferably 80 mol%. The preferred lower limit of the content of the diol component other than the component derived from ethylene glycol is 0 mol%, more preferably 20 mol%, and the preferred upper limit is 50 mol%, and more preferably 40 mol%.

As for the dicarboxylic acid component, one or more components can be used other than the component derived from terephthalic acid. Also, as for the diol component, one or more components can be used other than the component derived from ethylene glycol.

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

The glass transition temperature (Tg) of polyester resins can be measured using a differential scanning calorimeter (DSC) in accordance with ISO3146:2000.

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

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

As described below, the base film of the present invention has a structure in which layer A and layer B are adjacent to each other, and preferably has a two-layer structure of layer A/layer B, a three-layer structure of layer A/layer B/layer A, or a three-layer structure of layer B/layer A/layer B, etc., as specific examples.

When the A layer forms the surface layer and the back layer, the polyester resin may have the same composition in the surface layer and the back layer, or may have different compositions. When the A layer forms the surface layer and the back layer, the polyester resin is more preferably of the same composition in the surface layer and the back layer, in order to effectively suppress problems caused by curling of the film.

The base film for the backgrind tape of the present invention has a suitable hardness due to the above-mentioned structure of the A layer, and can be preferably used as a backgrind film for use in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning of semiconductor wafers (approximately 25 μm).

The substrate film for the backgrinding tape of the present invention has an appropriate hardness, which prevents warping of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer, and provides excellent peelability when peeling off the surface protection tape (adhesive tape for backgrinding).

(1-2) Layer B of the Base Film Layer B of the base film for the backgrind tape of the present invention is made of a resin composition containing a soft polyester resin.

Flexible Polyester Resin The flexible polyester resin is preferably characterized by comprising, as constituent units, 50% by mass to 93% by mass of polyester units (A) consisting of dicarboxylic acid units (a1) containing 70% by mol or more of a component derived from terephthalic acid and diol units (a2) containing 70% by mol or more of a component derived from ethylene glycol, and 7% by mass to 50% by mass of polyester polyol units (B) consisting of a component (b1) derived from a hydrogenated dimer acid and a component (b2) derived from 1,4-butanediol.

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

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

The dicarboxylic acid components other than the components derived from terephthalic acid may be contained in a range of less than 30 mol%. For example, isophthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,12-dodecanoic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. are preferably used, and these components may be used alone or in combination of two or more types.

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

The diol components other than those derived from ethylene glycol may be contained in an amount of less than 30 mol%. For example, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexane dimethanol, etc. are preferably used, and these may be used alone or in a mixture of two or more types.

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

Hydrogenated dimer acid is usually obtained as a mixture of compounds with linear branched structures, alicyclic structures, etc., and although the content of these compounds varies depending on the manufacturing process, there are no particular limitations on the content of these compounds in the present invention.

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

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

Intrinsic Viscosity (IV) of Soft Polyester Resins
Intrinsic viscosity (IV) is a property used to characterize the viscosity of polyesters and is proportional to the molecular weight of the polyester.

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

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

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

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

The glass transition temperature (Tg) of soft polyester resins can be measured using a differential scanning calorimeter (DSC) in accordance with ISO3146:2000.

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

The soft polyester resin of the present invention may contain additives such as heat stabilizers, antioxidants, and ultraviolet absorbers as necessary.

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

As described below, the base film of the present invention has a structure in which layer A and layer B are adjacent to each other, and preferably has a two-layer structure of layer A/layer B, a three-layer structure of layer A/layer B/layer A, or a three-layer structure of layer B/layer A/layer B, etc., as specific examples.

When layer B forms the surface layer and the back layer, the soft polyester resin may have the same composition in the surface layer and the back layer, or may have different compositions. When layer B forms the surface layer and the back layer, the soft polyester resin is more preferably of the same composition in the surface layer and the back layer, in order to effectively suppress problems caused by curling of the film.

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

The substrate film for the backgrinding tape of the present invention has an appropriate hardness, which prevents warping of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer, and provides excellent peelability when peeling off the surface protection tape (adhesive tape for backgrinding).

(1-3) Young's Modulus of the Base Film The base film for the backgrinding tape of the present invention is a base film used to fix a semiconductor wafer in the backgrinding step, and exhibits physical properties preferable for this application.

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

The base film of the present invention has a Young's modulus within the above-mentioned specific range, and therefore can be used as a backgrinding film in the backgrinding process of thin semiconductor wafers, effectively suppressing warpage of the semiconductor wafer after the backgrinding process, even when the semiconductor wafer is ultra-thinned (approximately 25 μm).

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

(1-4) Layer Structure of the Base Film The base film for the backgrind tape of the present invention has at least an A layer and a B layer.

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

At least either the A layer or B layer of the substrate film of the present invention may be the chuck table side or the wafer side during grinding (back grinding).

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

The thickness of layer A, which is made of a resin composition containing a polyester resin, is preferably about 5 μm to 100 μm, and more preferably about 10 μm to 50 μm.

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

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

Explain the extrusion method using a T-die.

The resin composition is preferably prepared by dry blending or melt kneading. Additives can be added to the resin composition constituting the layer as necessary.

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

When the base film is used as a base film for a backgrinding tape, shrinkage of the film caused by stretching during the backgrinding process can be suppressed by not stretching the base film substantially during withdrawal. This "substantially not stretching" includes no stretching, or slight stretching that does not affect the warping of the wafer during backgrinding. Usually, the film should be pulled to the extent that it does not sag.

(3) Backgrind tape The base film of the present invention is a base film used to fix a semiconductor wafer, and is preferably used as a base film for a backgrind tape. A backgrind tape can be produced by forming an adhesive layer and a release film on the surface of the base film for the backgrind tape.

The backgrind tape (film) of the present invention preferably has an adhesive layer and a release film on the wafer side of the base film for the backgrind tape.

One surface of the base film for the backgrind tape is coated with a known adhesive to form an adhesive layer. The thickness of the adhesive layer is preferably about 10 μm to 200 μm.

As the adhesive, it is preferable to use a pressure-sensitive adhesive, an acrylic adhesive, a rubber adhesive, etc. Considering the adhesion to the semiconductor wafer and the cleaning and washing properties of the semiconductor wafer after peeling with ultrapure water or organic solvents such as alcohol, it is preferable to use an acrylic adhesive that uses an acrylic polymer as the base polymer.

The backgrind tape is manufactured by forming an adhesive layer on the surface of the base film for the backgrind tape, and then providing a release film on top of that. The thickness of the release film is preferably about 10 μm to 200 μm.

The backgrind tape, containing the base film of the present invention, can be preferably used as a backgrind film for use in the backgrinding process of thin semiconductor wafers in relation to ultra-thinning semiconductor wafers (approximately 25 μm). The backgrind tape exhibits the effect of preventing warping of the semiconductor wafer in the backgrinding process of thin semiconductor wafers. The backgrind tape exhibits the effect of excellent releasability when peeling off the surface protection tape (adhesive tape for backgrinding).

The present invention will now be described in more detail with reference to examples.

The present invention is not limited to these examples.

(1) Raw material for the base film of backgrind tape
Pes-1 polyester resin
100 mol% terephthalic acid,
Ethylene glycol 70 mol% + 1,4-cyclohexanedimethanol 30 mol%
Glass transition temperature (Tg) 80℃
Pes-S soft polyester resin
Intrinsic Viscosity (IV) 0.75 dl/g
Glass transition temperature (Tg) 20℃
(2) Manufacturing of base film for backgrind tape
A base film for a backgrind tape was prepared by blending resin compositions with the respective components and compositions to obtain the layer structure (3 layers) shown in Table 1. The resin compositions constituting each layer were fed into respective extruders adjusted to 220°C, extruded through a T-die at 220°C in the order of the three layers, laminated, and co-extruded onto a chill roll through which 30°C cooling water was circulated, to obtain a flat 5-layer film.

(3) Evaluation of the substrate film for backgrind tape The Young's modulus of the substrate film was measured in accordance with ISO527-1:2012 by cutting a sample into a size of 400 mm long x 25 mm wide, with a gauge length of 250 mm (rectangular test piece) to prepare a test piece, and measuring it at a tensile speed of 10 mm/min using a Strograph VE-10 manufactured by Toyo Seiki Seisakusho Co., Ltd. The Young's modulus was measured using seven test pieces (n=7) in both the MD and TD directions for each Example and Comparative Example, and the average value was calculated.

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

The substrate film for the backgrinding tape of the present invention has an appropriate hardness, and as a backgrinding tape, it exhibits the effects of preventing warping of the semiconductor wafer during the backgrinding process of the thin semiconductor wafer, and of excellent peelability when peeling off the surface protection tape (adhesive tape for backgrinding).

Claims (2)

A base film for a backgrind tape, comprising:
At least an A layer and a B layer are included,
The layer A is made of a resin composition containing a polyester-based resin,
The layer B is made of a resin composition containing a soft polyester resin,
The Young's modulus of the base film at 23° C. is 150 MPa or more and 1500 MPa or less,
The soft polyester resin is a base film for a backgrind tape, the base film having a polyester unit and a polyester polyol unit . The glass transition temperature (Tg) of the polyester resin is 50° C. or higher and 100° C. or lower,
2. The substrate film for a backgrind tape according to claim 1, wherein the soft polyester resin has a glass transition temperature (Tg) of 10° C. or higher and 40° C. or lower.