CN106463373B - Composite sheet for forming protective film - Google Patents

Composite sheet for forming protective film Download PDF

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Publication number
CN106463373B
CN106463373B CN201580025643.4A CN201580025643A CN106463373B CN 106463373 B CN106463373 B CN 106463373B CN 201580025643 A CN201580025643 A CN 201580025643A CN 106463373 B CN106463373 B CN 106463373B
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protective film
forming
sheet
base material
composite sheet
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CN106463373A (en
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佐伯尚哉
山本大辅
米山裕之
稻男洋一
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Lindeko Corp
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Lindeko Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L21/6836—Wafer tapes, e.g. grinding or dicing support tapes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/324—Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • H01L21/7806—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices involving the separation of the active layers from a substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L24/28—Structure, shape, material or disposition of the layer connectors prior to the connecting process
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Physics & Mathematics (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Dicing (AREA)
  • Adhesive Tapes (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Laminated Bodies (AREA)
  • Laser Beam Processing (AREA)

Abstract

The composite sheet for forming a protective film is a composite sheet (3) for forming a protective film, which comprises a support sheet (4) and a protective film forming film (1) laminated on the 1 st surface side of the support sheet (4), wherein the arithmetic mean roughness (Ra1) of the 2 nd surface of the support sheet (4) is 0.2 [ mu ] m or more, and the arithmetic mean roughness (Ra2) of the 2 nd surface of the support sheet (4) is 0.25 [ mu ] m or less after the support sheet (4) is heated at 130 ℃ for 2 hours.

Description

Composite sheet for forming protective film
Technical Field
The present invention relates to a composite sheet for forming a protective film, which can form a protective film on a workpiece such as a semiconductor wafer or the like, or can form a protective film on a processed product (for example, a semiconductor chip) obtained by processing the workpiece.
The present application claims priority from Japanese application No. 2014-106757, filed on Japanese application 5/23/2014, the contents of which are incorporated herein by reference.
Background
In recent years, semiconductor devices have been manufactured by a mounting method called a flip-chip (face down) method. In this method, when a semiconductor chip having a circuit surface on which electrodes such as bumps are formed is mounted, the circuit surface side of the semiconductor chip is bonded to a chip mounting portion such as a lead frame. Therefore, the back surface side of the semiconductor chip on which no circuit is formed is exposed.
Therefore, in order to protect the semiconductor chip, a protective film made of a thermosetting organic material is often formed on the back surface side of the semiconductor chip. The protective film is generally printed to indicate a product number of the semiconductor chip. As a printing method in this case, a laser marking method (laser printing) in which a protective film is irradiated with a laser beam is generally used.
Patent documents 1 to 3 each disclose a protective film forming/cutting integrated sheet (protective film forming composite sheet) in which a protective film forming layer (protective film forming film) capable of forming the protective film is formed on an adhesive sheet. In these protective film forming/cutting integrated sheets, the protective film forming film is cured by heat treatment to form the protective film. That is, the protective film-forming/dicing integrated sheet can be used to both cut a semiconductor wafer and form a protective film on a semiconductor chip, and a semiconductor chip with a protective film can be obtained.
On the other hand, when manufacturing a processed product including a sheet-like body such as a semiconductor chip from a workpiece such as a semiconductor wafer, conventionally, a cutter dicing process of cutting the workpiece with a rotary cutter to obtain the sheet-like body has been generally performed while cleaning the workpiece by spraying a liquid thereto. However, in recent years, a Stealth Dicing (registered trademark, the same applies hereinafter) process capable of being divided into sheet-like bodies by dry Dicing has been adopted (patent document 3).
For example, patent document 4 discloses an invisible cutting method including: a laminated adhesive sheet (an adhesive sheet formed by laminating 2 adhesive sheets each composed of a base material and an adhesive layer) is attached to an extremely thin semiconductor wafer, the semiconductor wafer is irradiated with a laser beam from the laminated adhesive sheet side through the laminated adhesive sheet to form a modified portion inside the semiconductor wafer, and then the adhesive sheet is subjected to expansion (expansion), whereby the semiconductor wafer is divided along dicing lines to produce semiconductor chips.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2006-140348
Patent document 2: japanese laid-open patent publication No. 2012-33637
Patent document 3: japanese patent laid-open publication No. 2011-151362
Patent document 4: japanese patent No. 3762409
Patent document 5: japanese patent laid-open publication No. 2007-123404
Disclosure of Invention
Problems to be solved by the invention
As described above, when a workpiece is irradiated with laser light, the laser light needs to pass through the pressure-sensitive adhesive sheet to reach the protective film or the workpiece, and therefore the pressure-sensitive adhesive sheet is required to have laser light transmissivity.
However, in many cases, a release sheet is laminated on the side opposite to the adhesive sheet of the protective film forming film in the composite sheet for forming a protective film in order to protect the protective film forming film. When the composite sheet for forming a protective film is fed out in a state of a film roll, a surface of the pressure-sensitive adhesive sheet on the side opposite to the protective film-forming side of the rolled laminate and a surface of the release sheet on the side opposite to the protective film-forming side of the laminate are adhered to each other and are stuck to each other, and thus, a feeding failure from the film roll occurs, or the pressure-sensitive adhesive sheet is transferred to the rolled laminate release sheet, and a work may not be attached.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a composite sheet for forming a protective film, which can suppress the occurrence of blocking when the composite sheet for forming a protective film is fed out from a rolled state, and which has excellent laser transmissivity when irradiated with laser light. Means for solving the problems
In order to achieve the above object, the present invention provides a composite sheet for forming a protective film, comprising a support sheet and a protective film forming film laminated on a1 st surface side of the support sheet, wherein an arithmetic mean roughness (Ra1) of a2 nd surface of the support sheet is 0.2 μm or more, and an arithmetic mean roughness (Ra2) of the 2 nd surface of the support sheet is 0.25 μm or less after the support sheet is heated at 130 ℃ for 2 hours (invention 1). In this specification, the term "sheet" includes a concept such as a long tape.
According to the invention (invention 1), when the composite sheet for forming a protective film is wound in a roll form, the member (for example, a release sheet in the case where the release sheet is provided on the protective film forming film, or a protective film forming film in the case where the release sheet is not provided) which contacts the 2 nd surface of the support sheet is not likely to adhere to the 2 nd surface of the support sheet, and blocking is not likely to occur when the rolled composite sheet for forming a protective film is fed out. When the laser beam is irradiated from the 2 nd surface side of the support sheet, the laser beam passes through the support sheet without being scattered by the irregularities of the 2 nd surface of the support sheet, and efficiently reaches the protective film formed by curing the protective film and the workpiece (semiconductor wafer), and the laser beam transmittance is excellent.
In the invention (invention 1), it is preferable that the arithmetic average roughness (Ra2) of the second surface of the support sheet after heating is smaller than the arithmetic average roughness (Ra1) (invention 2).
In the above inventions (inventions 1 and 2), it is preferable that the support sheet is composed of a base material, or is composed of a base material and an adhesive layer laminated on the 1 st surface side of the support sheet which is one surface side of the base material (invention 3).
In the invention (invention 3), the melting point of the base material is preferably 90 to 180 ℃ (invention 4).
In the above inventions (inventions 3 and 4), it is preferable that the storage modulus of the base material at 130 ℃ is 1 to 100MPa (invention 5).
In the above inventions (inventions 3 to 5), it is preferable that the substrate has a light transmittance of 40% or more at a wavelength of 1064nm after the heating (invention 6).
In the above inventions (inventions 3 to 6), it is preferable that the substrate has a light transmittance of 40% or more at a wavelength of 532nm after the heating (invention 7).
In the above inventions (inventions 3 to 7), it is preferable that the base material is a film made of a copolymer of ethylene and propylene (invention 8).
In the above inventions (inventions 1 to 8), it is preferable that the composite sheet for forming a protective film includes a pressure-sensitive adhesive layer for a jig laminated on an edge portion of the protective film forming film on the side opposite to the support sheet (invention 9).
In the above inventions (inventions 1 to 9), a release sheet (invention 10) laminated on the protective film forming film is preferably provided.
In the above inventions (inventions 1 to 10), the protective film forming film is preferably a layer in which a protective film is formed on a semiconductor wafer or a layer in which a protective film is formed on a semiconductor chip obtained by dicing a semiconductor wafer (invention 11).
ADVANTAGEOUS EFFECTS OF INVENTION
According to the composite sheet for forming a protective film of the present invention, the occurrence of blocking can be suppressed when the composite sheet for forming a protective film is fed out from a rolled state, and the composite sheet for forming a protective film has excellent laser transmissivity when irradiated with a laser beam.
Drawings
Fig. 1 is a sectional view of a composite sheet for forming a protective film according to an embodiment of the present invention.
Fig. 2 is a sectional view showing an example of use of the composite sheet for forming a protective film according to the embodiment of the present invention, specifically, a sectional view showing a laminated structure.
Fig. 3 is a sectional view of a composite sheet for forming a protective film according to another embodiment of the present invention.
Fig. 4 is a plan view of the composite sheet for forming a protective film produced in the example.
Description of the symbols
1 … protective film forming film
101 … circular shape
3. Composite sheet for forming 3A … protective film
4 … supporting sheet
41 … base material
42 … adhesive layer
401 … circle
402 … arc
Line 403 …
5 … adhesive layer for clip
6 … Release sheet
7 … semiconductor wafer
8 … Ring frame
Detailed Description
Hereinafter, embodiments of the present invention will be described.
Fig. 1 is a sectional view of a composite sheet for forming a protective film according to an embodiment of the present invention. As shown in fig. 1, the composite sheet 3 for forming a protective film according to the present embodiment includes a support sheet 4, a protective film forming film 1 laminated on one surface (a "1 st surface" described later; an upper surface in fig. 1) side of the support sheet 4, and a pressure-sensitive adhesive layer 5 for a jig laminated on an edge portion of the protective film forming film 1 opposite to the support sheet 4. The jig adhesive layer 5 is a layer for bonding the composite sheet 3 for forming a protective film to a jig such as an annular frame. The composite sheet 3 for forming a protective film according to the present embodiment has a release sheet 6 on the protective film forming film 1 and the pressure-sensitive adhesive layer 5 for a jig (on the side opposite to the support sheet 4). The release sheet 6 is released and removed when the composite sheet for protective film formation 3 is used, and is not an essential component of the composite sheet for protective film formation 3.
The composite sheet 3 for forming a protective film of the present embodiment is used for attaching to and holding a workpiece when processing the workpiece, and forming a protective film on the workpiece or a processed product obtained by processing the workpiece. The protective film is constituted by a protective film forming film 1, and preferably, is constituted by the cured protective film forming film 1.
As an example, the composite sheet 3 for forming a protective film of the present embodiment is used for holding a semiconductor wafer when the semiconductor wafer as a workpiece is cut, and for forming a protective film on the semiconductor wafer obtained by cutting, but is not limited thereto. The support sheet 4 of the composite sheet 3 for forming a protective film in this case is generally called a dicing sheet.
The composite sheet 3 for forming a protective film of the present embodiment is usually formed in a long strip shape and wound into a roll shape, and can be used in a roll-to-roll (roll) system.
1. Support sheet
The support sheet 4 of the composite sheet 3 for forming a protective film according to the present embodiment is configured to include a base material 41 and an adhesive layer 42, and the adhesive layer 42 is laminated on one surface side (protective film forming film 1 side; upper side in fig. 1) of the base material 41. In the present specification, the surface of the support sheet 4 on the side where the protective film is formed into the film 1 is referred to as "1 st surface", and the surface on the opposite side (hereinafter in fig. 1) is referred to as "2 nd surface". In the support sheet 4, the adhesive layer 42 is laminated on the 1 st surface side of the support sheet 4, and the base material 41 is laminated on the 2 nd surface side of the support sheet 4.
1-1. base material
The surface of the base material 41 opposite to the pressure-sensitive adhesive layer 42 (hereinafter, sometimes referred to as "the back surface of the base material 41", and the back surface of the base material 41 corresponds to the 2 nd surface of the support sheet 4) has an arithmetic average roughness (Ra1) of 0.2 μm or more. After heating the substrate 41 at 130 ℃ for 2 hours and cooling it to room temperature (hereinafter, sometimes simply referred to as "after heating"), the arithmetic average roughness (Ra2) of the back surface of the substrate 41 was 0.25 μm or less. The arithmetic average roughness (Ra1) of the back surface of the substrate 41 is the arithmetic average roughness of the back surface of the substrate 41 before heating at 130 ℃ for 2 hours, and may be hereinafter referred to as "arithmetic average roughness (Ra 1)" in some cases. The arithmetic average roughness (Ra1) before heating and the arithmetic average roughness (Ra2) after heating are based on JISB 0601: 2001, details of the measurement method are shown in test examples described later.
The conditions of the heat treatment (130 ℃/2 hour) are generally conditions of the heat treatment for thermally curing the protective film forming film 1, and the conditions are before heating when the rolled protective film forming composite sheet 3 is fed, and after heating when laser irradiation for laser printing or stealth dicing is performed. However, the heat treatment described above may not be necessarily used for thermally curing the protective film forming film 1, and for example, when the protective film forming film 1 is energy ray-curable, a separate heat treatment may be performed.
Since the arithmetic average roughness (Ra1) of the back surface of the substrate 41 before heating is 0.2 μm or more, the back surface of the substrate 41 and the surface of the release sheet 6 opposite to the protective film forming film 1 are not easily adhered to each other in the state after winding. This makes it difficult for the rolled composite sheet 3 for forming a protective film to stick to each other when it is fed out. Therefore, the occurrence of the feeding failure due to the sticking and the failure of the work to be stuck due to the transfer of the support sheet 4 to the release sheet 6 with the overlapped curl can be suppressed.
From the above viewpoint, the arithmetic average roughness (Ra1) of the back surface of the base material 41 before heating is preferably 0.25 μm or more, and particularly preferably 0.30 μm or more.
Here, the upper limit of the arithmetic average roughness (Ra1) of the back surface of the substrate 41 before heating is preferably 1.0 μm or less, particularly preferably 0.8 μm or less, and more preferably 0.7 μm or less. When the arithmetic average roughness (Ra1) before heating exceeds 1.0 μm, there is a possibility that it is difficult to satisfy the arithmetic average roughness (Ra2) after heating.
That is, the arithmetic average roughness (Ra1) of the back surface of the substrate 41 before heating is preferably in the range of 0.25 to 1.0 μm, and more preferably in the range of 0.30 to 0.7 μm.
On the other hand, when the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating under the above conditions is 0.25 μm or less, the laser light transmits through the support sheet 4 without being scattered by the irregularities of the back surface of the base material 41 when the laser light is irradiated from the back surface side of the base material 41, and the laser light can efficiently reach the protective film and the work (semiconductor wafer) obtained by curing the protective film forming film 1, and is excellent in laser light transmittance. Therefore, the laser beam printer has excellent laser printability, can form a printout having high visibility, and has excellent workpiece dividing performance by stealth dicing.
From the above viewpoint, the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating is preferably 0.20 μm or less, and particularly preferably 0.10 μm or less.
Here, the lower limit of the arithmetic average roughness (Ra2) of the back surface of the substrate 41 after heating is not particularly limited as long as the arithmetic average roughness (Ra1) before heating can be satisfied. However, it is usually 0.001 μm or more, preferably 0.01 μm or more.
That is, the arithmetic average roughness (Ra2) of the back surface of the substrate 41 after heating is preferably in the range of 0.001 to 0.20 μm, and more preferably in the range of 0.01 to 0.10 μm.
In the base material 41, the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating under the above conditions is preferably smaller than the arithmetic average roughness (Ra1) before heating. By setting in this manner, both the blocking suppressing effect before heating and the laser transmissivity after heating can be made more excellent.
The method for adjusting the arithmetic average roughness (Ra1) of the back surface of the substrate 41 before heating is not particularly limited, and the adjustment can be usually performed by changing the surface roughness of the roll surface used when forming the resin film constituting the substrate 41, by sandblasting, or by blending a filler which is melted by heating to form a flat surface, or the like.
On the other hand, as a method for adjusting the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating, it is preferable that the base material 41 is formed of a resin film (a film mainly made of a resin-based material) having a melting point within a predetermined range, and it is particularly preferable that the base material 41 is formed of a resin film having a melting point within a predetermined range and a storage modulus at 130 ℃.
The melting point of the substrate 41 is preferably 90 to 180 ℃, particularly preferably 100 to 160 ℃, and further preferably 110 to 150 ℃. When the melting point of the base material 41 is in the above range, the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating can be easily adjusted to the above range. When the melting point of the base material 41 is lower than 90 ℃, there is a risk that the base material 41 is completely melted during the heat curing process. On the other hand, when the melting point of the base material 41 exceeds 180 ℃, there is a possibility that the arithmetic mean roughness of the back surface of the base material 41 does not change even after heating at 130 ℃/2 hours. The melting point is measured according to JIS K7121(ISO3146), and the details of the measurement method are shown in test examples described later.
The method for adjusting the melting point of the base material 41 is not particularly limited, and can be adjusted mainly by the melting point of the resin material to be used. The base material 41 may be adjusted to any melting point by mixing a plurality of resin materials having different melting points and copolymerizing a plurality of monomers.
The storage modulus of the substrate 41 at 130 ℃ is preferably 1 to 100MPa, particularly preferably 2 to 80MPa, and further preferably 5 to 50 MPa. By setting the storage modulus of the base material 41 at 130 ℃ to the above range, the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating can be easily adjusted to the above range. When the storage modulus of the base material 41 at 130 ℃ is less than 1MPa, the base material 41 may be greatly deformed during the heat treatment, and there is a risk that the workpiece cannot be held. On the other hand, when the storage modulus of the base material 41 at 130 ℃ exceeds 100MPa, there is a possibility that the arithmetic mean roughness of the back surface of the base material 41 does not change even when heated at 130 ℃/2 hours. The method of measuring the storage modulus is shown in test examples described below.
The method for adjusting the storage modulus of the base material 41 at 130 ℃ is not particularly limited, and can be adjusted mainly by the storage modulus of the resin material to be used. In addition, even with the same chemical structure, the storage modulus tends to increase when the molecular weight is large, and the storage modulus tends to increase due to crosslinking or a narrow molecular weight distribution. From such tendency, the base material 41 can be adjusted to have an arbitrary storage modulus.
When a laser beam having a wavelength of 1064nm is used for stealth dicing or the like, the transmittance of the substrate 41 after heating to a light having a wavelength of 1064nm is preferably 40% or more, particularly preferably 50% or more, and more preferably 60% or more. When the transmittance of the base material 41 after heating to light having a wavelength of 1064nm is in the above range, the workpiece obtained by stealth dicing has excellent separability. In the present embodiment, the light transmittance can be achieved by setting the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating to the above range. The higher the light transmittance of the substrate 41 after heating at a wavelength of 1064nm, the better, but the maximum achievable light transmittance is about 99%.
In the case of using a laser beam having a wavelength of 532nm for laser marking or the like of the protective film, the transmittance of the substrate 41 after heating to light having a wavelength of 532nm is preferably 40% or more, particularly preferably 50% or more, and more preferably 60% or more. When the transmittance of the substrate 41 to light having a wavelength of 532nm after heating is in the above range, the laser printability is excellent. In the present embodiment, the above-described light transmittance can be achieved by setting the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating to the above-described range. The transmittance of the substrate 41 after heating to light having a wavelength of 532nm is preferably as high as described above, but the maximum achievable transmittance is about 99%.
Specific examples of the resin film constituting the substrate 41 include: polyolefin-based films such as polyethylene films including low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, and high-density polyethylene (HDPE) films, polypropylene films, ethylene-propylene copolymer films, polybutylene films, polybutadiene films, polymethylpentene films, ethylene-norbornene copolymer films, and norbornene resin films; ethylene copolymer films such as ethylene-vinyl acetate copolymer films, ethylene- (meth) acrylic acid copolymer films, and ethylene- (meth) acrylate copolymer films; polyvinyl chloride films such as polyvinyl chloride films and vinyl chloride copolymer films; polyester-based films such as polyethylene terephthalate films and polybutylene terephthalate films; a polyurethane film; a polyimide film; a polystyrene film; a polycarbonate film; fluororesin films, and the like. Further, modified films such as crosslinked films and ionomer films can also be used. A laminated film obtained by laminating a plurality of the above films may be used. In the present specification, "(meth) acrylic acid" means both acrylic acid and methacrylic acid. Other similar terms are treated the same.
In the case of a laminated film, for example, it is preferable to provide a film having a changed arithmetic mean roughness before and after heating on the back surface side of the substrate 41, and to provide a film having heat resistance and not being deformed at high temperature on the pressure-sensitive adhesive layer 42 side of the substrate 41.
Among the above, polyolefin-based films are preferable, particularly polyethylene films, polypropylene films and ethylene-propylene copolymer films are preferable, and ethylene-propylene copolymer films are more preferable. These resin films are easy to satisfy the above-mentioned physical properties, and particularly in the case of an ethylene-propylene copolymer film, the above-mentioned physical properties are easy to satisfy by adjusting the copolymerization ratio of an ethylene monomer and a propylene monomer. These resin films are also preferable from the viewpoint of work adhesiveness and chip releasability.
The resin film may be subjected to surface treatment by an oxidation method, a roughening method, or the like, or undercoating treatment on one or both sides as required, in order to improve adhesion to the pressure-sensitive adhesive layer 42 laminated on the surface thereof. Examples of the oxidation method include: corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet method), flame treatment, hot air treatment, ozone, ultraviolet irradiation treatment, and the like, and examples of the method of forming concavities and convexities include: sand blasting, spray coating, and the like.
The base material 41 may further contain various additives such as a colorant, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and a filler in the resin film.
The thickness of the substrate 41 is not particularly limited as long as it can function properly in each step using the composite sheet 3 for forming a protective film, and is preferably 20 to 450 μm, particularly preferably 25 to 400 μm, and further preferably 50 to 350 μm.
1-2 adhesive layer
The adhesive layer 42 provided in the support sheet 4 of the composite sheet 3 for forming a protective film according to the present embodiment may be composed of a non-energy ray-curable adhesive or an energy ray-curable adhesive. As the non-energy ray-curable pressure-sensitive adhesive, pressure-sensitive adhesives having desired adhesive strength and removability are preferable, and for example, acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyurethane pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyvinyl ether pressure-sensitive adhesives, and the like can be used. Among them, an acrylic pressure-sensitive adhesive which has high adhesion to the protective film forming film 1 and can effectively suppress the falling off of the work or the processed product in the dicing step or the like is preferable.
On the other hand, since the energy ray-curable adhesive has a reduced adhesive force when irradiated with energy rays, when a work or a processed object is to be separated from the support sheet 4, the separation can be easily performed by the energy ray irradiation.
In the case where the adhesive layer 42 is formed of an energy ray-curable adhesive, the adhesive layer 42 in the composite sheet 3 for forming a protective film is preferably cured. Since a material obtained by curing an energy ray-curable adhesive is generally high in elastic modulus and high in surface smoothness, when a protective film is formed by curing the protective film forming film 1 in contact with a cured portion formed of the material, the smoothness (glossiness) of the surface in contact with the cured portion of the protective film is increased, and the material has excellent appearance as a protective film for chips. In addition, when laser printing is performed on a protective film having high surface smoothness, the visibility of the printing is improved.
The energy ray-curable adhesive constituting the adhesive layer 42 may have a polymer having energy ray-curability as a main component, or may have a mixture of a polymer having no energy ray-curability and an energy ray-curable polyfunctional monomer and/or oligomer as a main component.
Hereinafter, a case where the energy ray-curable adhesive contains a polymer having energy ray-curability as a main component will be described.
The polymer having energy ray-curability is preferably a (meth) acrylate (co) polymer (a) having a functional group having energy ray-curability (energy ray-curability group) introduced into a side chain thereof (hereinafter, may be referred to as "energy ray-curable polymer (a)"). The energy ray-curable polymer (a) is preferably a compound obtained by reacting a (meth) acrylic copolymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a substituent to be bonded to the functional group.
The acrylic copolymer (a1) is composed of a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth) acrylate monomer or a derivative thereof.
The functional group-containing monomer as a constituent unit of the acrylic copolymer (a1) is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, an amino group, a substituted amino group, or an epoxy group in the molecule.
More specific examples of the above-mentioned functional group-containing monomer include: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like, and these compounds may be used alone or in combination of 2 or more.
As the (meth) acrylate monomer constituting the acrylic copolymer (a1), an alkyl (meth) acrylate having an alkyl group with 1 to 20 carbon atoms, a cycloalkyl (meth) acrylate, and benzyl (meth) acrylate can be used. Among them, alkyl (meth) acrylates having an alkyl group of 1 to 18 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, are particularly preferably used.
The acrylic copolymer (a1) contains a structural unit derived from the functional group-containing monomer in a proportion of usually 3 to 100% by mass, preferably 4 to 80% by mass, more preferably 5 to 40% by mass, based on the total mass of the acrylic copolymer (a1), and contains a structural unit derived from a (meth) acrylate monomer or a derivative thereof in a proportion of usually 0 to 97% by mass, preferably 60 to 95% by mass, based on the total mass of the acrylic copolymer (a 1).
The acrylic copolymer (a1) can be obtained by copolymerizing the functional group-containing monomer with a (meth) acrylate monomer or a derivative thereof by a usual method, and besides these monomers, dimethylacrylamide, vinyl formate, vinyl acetate, styrene, and the like can be copolymerized.
The energy ray-curable polymer (a) can be obtained by reacting the acrylic copolymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a substituent to be bonded to the functional group.
The substituent group of the unsaturated group-containing compound (a2) can be appropriately selected depending on the kind of the functional group-containing monomer unit of the acrylic copolymer (a 1). For example, when the functional group is a hydroxyl group, an amino group or a substituted amino group, an isocyanate group or an epoxy group is preferable as the substituent, and when the functional group is an epoxy group, an amino group, a carboxyl group or an aziridine group is preferable as the substituent.
The unsaturated group-containing compound (a2) preferably contains 1 to 5 energy ray-polymerizable carbon-carbon double bonds per 1 molecule, and 1 to 2 energy ray-polymerizable carbon-carbon double bonds per 1 molecule. Specific examples of such unsaturated group-containing compound (a2) include: 2-methacryloyloxyethyl isocyanate, m-isopropenyl-alpha, alpha-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1- (bisacryloxymethyl) ethyl isocyanate; an acryloyl monoisocyanate compound obtained by the reaction of a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth) acrylate; an acryloyl monoisocyanate compound obtained by the reaction of a diisocyanate compound or a polyisocyanate compound, a polyol compound and hydroxyethyl (meth) acrylate; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1-aziridinyl) ethyl (meth) acrylate, 2-vinyl-2-
Figure BDA0001155972010000111
Oxazoline, 2-isopropenyl-2-Oxazoline, and the like.
The unsaturated group-containing compound (a2) is usually used in an amount of 10 to 100 equivalents, and preferably 20 to 95 equivalents, per 100 equivalents of the functional group-containing monomer of the acrylic copolymer (a1) (a 2).
In the reaction of the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and the type of a catalyst can be appropriately selected depending on the combination of the functional group and the substituent. Thus, the functional group present in the acrylic copolymer (a1) reacts with the substituent in the unsaturated group-containing compound (a2), and the unsaturated group is introduced into the side chain in the acrylic copolymer (a1), thereby obtaining the energy ray-curable polymer (a).
The weight average molecular weight of the energy ray-curable polymer (a) thus obtained is preferably 1 ten thousand or more, particularly preferably 15 to 150 ten thousand, and more preferably 20 to 100 ten thousand. The weight average molecular weight (Mw) in the present specification is a value measured by gel permeation chromatography (GPC method) in terms of polystyrene.
When the energy ray-curable adhesive contains an energy ray-curable polymer as a main component, the energy ray-curable adhesive may further contain an energy ray-curable monomer and/or oligomer (B).
Examples of the energy ray-curable monomer and/or oligomer (B) include esters of a polyol and (meth) acrylic acid.
Examples of the energy ray-curable monomer and/or oligomer (B) include: and polyfunctional acrylates such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and dimethylol tricyclodecane di (meth) acrylate, polyester oligo (meth) acrylate, and urethane oligo (meth) acrylate.
When the energy ray-curable monomer and/or oligomer (B) is blended, the content of the energy ray-curable monomer and/or oligomer (B) in the energy ray-curable adhesive is preferably 5 to 80% by mass, and particularly preferably 20 to 60% by mass, based on the total mass of the energy ray-curable adhesive.
Here, when ultraviolet rays are used as the energy rays for curing the energy ray-curable resin composition, it is preferable to add a photopolymerization initiator (C), and by using the photopolymerization initiator (C), the polymerization curing time and the amount of light irradiation can be reduced.
Specific examples of the photopolymerization initiator (C) include: benzophenone, acetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoylbenzoic acid methyl ester, benzoin dimethyl ether, 2, 4-diethyl thiazolone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, bibenzyl, butanedione, beta-chloroanthraquinone, (2,4, 6-trimethylbenzyldiphenyl) phosphine oxide, N, 2-benzothiazolyl N-diethyldithiocarbamate, oligo { 2-hydroxy-2-methyl-1- [4- (1-propenyl) phenyl ] propanone }, 2-dimethoxy-1, 2-diphenylethan-1-one, and the like. These compounds may be used alone, or 2 or more of them may be used in combination.
The amount of the photopolymerization initiator (C) used is preferably 0.1 to 10 parts by mass, and particularly preferably 0.5 to 6 parts by mass, based on 100 parts by mass of the energy ray-curable copolymer (a) (when the energy ray-curable monomer and/or oligomer (B) is blended, based on 100 parts by mass of the total amount of the energy ray-curable copolymer (a) and the energy ray-curable monomer and/or oligomer (B)).
In addition to the above components, other components may be appropriately blended in the energy ray-curable adhesive. As other components, for example: a polymer component or oligomer component (D) having no energy ray curability, a crosslinking agent (E), and the like.
Examples of the polymer component or oligomer component (D) having no energy ray curability include: polyacrylate, polyester, polyurethane, polycarbonate, polyolefin, etc., preferably a polymer or oligomer having a weight average molecular weight (Mw) of 3000 to 250 ten thousand.
As the crosslinking agent (E), a polyfunctional compound reactive with a functional group of the energy ray-curable copolymer (a) or the like can be used. Examples of such polyfunctional compounds include: isocyanate compound, epoxy compound, amine compound, melamine compound, aziridine compound, hydrazine compound, aldehyde compound, amino acid compound,
Figure BDA0001155972010000131
oxazoline compound, metal alkoxide compound, and metal chelateChemical compounds, metal salts, ammonium salts, reactive phenolic resins, and the like.
By blending the other components (D) and (E) in the energy ray-curable adhesive, the adhesiveness and releasability of the adhesive layer 42 before curing, the strength after curing, the adhesiveness to other layers, the storage stability, and the like can be improved. The amount of these other components to be blended is not particularly limited, and may be appropriately determined in the range of 0 to 40 parts by mass based on 100 parts by mass of the energy ray-curable copolymer (A).
Next, a case where the energy ray-curable adhesive contains a mixture of a polymer component not curable with energy rays and an energy ray-curable polyfunctional monomer and/or oligomer as main components will be described.
As the polymer component having no energy ray curability, for example, the same components as those of the acrylic copolymer (a1) can be used. The content of the polymer component not curable by energy rays in the energy ray-curable resin composition is preferably 20 to 99.9% by mass, and particularly preferably 30 to 80% by mass, based on the total mass of the energy ray-curable resin composition.
The energy ray-curable polyfunctional monomer and/or oligomer may be selected from the same components as the component (B). The compounding ratio of the polymer component having no energy ray-curability to the energy ray-curable polyfunctional monomer and/or oligomer is as follows: the amount of the polyfunctional monomer and/or oligomer is preferably 10 to 150 parts by mass, and particularly preferably 25 to 100 parts by mass, based on 100 parts by mass of the polymer component.
In this case, the photopolymerization initiator (C) and the crosslinking agent (E) may be appropriately blended in the same manner as described above.
The thickness of the pressure-sensitive adhesive layer 42 is not particularly limited as long as it can function properly in each step using the protective film-forming sheet 3. Specifically, the thickness of the adhesive layer 42 is preferably 1 to 50 μm, particularly preferably 2 to 30 μm, and more preferably 3 to 20 μm.
2. Protective film forming film
The protective film forming film 1 is used for forming a protective film on a workpiece or a work obtained by processing the workpiece. The protective film is constituted by a protective film forming film 1, and preferably, is constituted by the cured protective film forming film 1. Examples of the workpiece include a semiconductor wafer, and examples of the processed object obtained by processing the workpiece include a semiconductor chip. When the workpiece is a semiconductor wafer, the protective film is formed on the back surface side of the semiconductor wafer (the side on which the electrodes such as bumps are not formed).
The protective film forming film 1 may be formed of a single layer or a plurality of layers, and is preferably formed of a single layer in view of ease of controlling light transmittance and manufacturing cost.
The protective film forming film 1 is preferably formed of an uncured curable adhesive. In this case, by laminating a work such as a semiconductor wafer on the protective film forming film 1 and then curing the protective film forming film 1, the protective film can be firmly adhered to the work, and a protective film having durability can be formed for a chip or the like.
The protective film forming film 1 preferably has adhesiveness at normal temperature or exerts adhesiveness by heating. Thus, when a work such as a semiconductor wafer is laminated on the protective film forming film 1 as described above, the work and the protective film can be bonded to each other. Therefore, positioning can be reliably performed before curing the protective film forming film 1.
The curable adhesive constituting the protective film forming film 1 having the above characteristics preferably contains a curable component and a binder polymer component. As the curable component, a thermosetting component, an energy ray curable component, or a mixture thereof can be used, and a thermosetting component is particularly preferably used. That is, the protective film forming film 1 is preferably made of a thermosetting adhesive.
Examples of the thermosetting component include: epoxy resin, phenol resin, melamine resin, urea resin, polyester resin, polyurethane resin, acrylic resin, polyimide resin, and benzo
Figure BDA0001155972010000141
Oxazine resins and the like and mixtures thereofA compound (I) is provided. Among them, epoxy resins, phenol resins, and mixtures thereof are preferably used as the thermosetting component.
Epoxy resins have the property of forming a strong coating film by three-dimensional reticulation upon heating. As such an epoxy resin, various conventionally known epoxy resins can be used, and a resin having a number average molecular weight of about 300 to 2000 is generally preferable, and a resin having a number average molecular weight of 300 to 500 is particularly preferable. Furthermore, it is preferable to use an epoxy resin having a number average molecular weight of 330 to 400, which is liquid in a normal state, and an epoxy resin having a number average molecular weight of 400 to 2500, which is solid at normal temperature, particularly an epoxy resin having a number average molecular weight of 500 to 2000, in a form of a blend. The epoxy equivalent of the epoxy resin is preferably 50 to 5000 g/eq. The number average molecular weight of the epoxy resin can be determined by a method using GPC.
Specific examples of such epoxy resins include: glycidyl ethers of phenols such as bisphenol a, bisphenol F, resorcinol, novolak type, and cresol novolak type; glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ethers of carboxylic acids such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidyl-type or alkyl glycidyl-type epoxy resins obtained by substituting active hydrogens bonded to nitrogen atoms of aniline isocyanurates with glycidyl groups; so-called alicyclic epoxy oxides in which an epoxy group is introduced by, for example, oxidizing a carbon-carbon double bond in the molecule, such as vinylcyclohexane diepoxide, methyl 3, 4-epoxycyclohexylmethyl-3, 4-bicyclohexanecarboxylate, and 2- (3, 4-epoxy) cyclohexyl-5, 5-spiro (3, 4-epoxy) cyclohexane-dioxane. In addition, epoxy resins having a biphenyl skeleton, a bicyclohexadiene skeleton, a naphthalene skeleton, or the like can also be used.
Among them, bisphenol glycidyl epoxy resins, o-cresol novolac epoxy resins, and phenol novolac epoxy resins are preferably used as the epoxy resin. These epoxy resins may be used alone in 1 kind, or in combination of 2 or more kinds.
When an epoxy resin is used, a thermally active latent epoxy resin curing agent is preferably used in combination as an auxiliary agent. The heat-active latent epoxy resin curing agent is a curing agent which does not react with an epoxy resin at room temperature, and is activated by heating to a certain temperature or higher to react with the epoxy resin. The method for activating the heat-active latent epoxy resin curing agent comprises the following steps: a method of generating active species (anion, cation) by a chemical reaction based on heating; a method of stably dispersing in an epoxy resin at around room temperature, and initiating a curing reaction by being compatible/soluble with the epoxy resin at high temperature; a method of causing a curing reaction by dissolving out a molecular sieve-blocked curing agent at a high temperature; a method using a microcapsule, and the like.
Specific examples of the heat-reactive latent epoxy resin curing agent include various types
Figure BDA0001155972010000151
Salts, or high melting point active hydrogen compounds such as dibasic acid dihydrazide compounds, dicyandiamide, amine adduct curing agents, imidazole compounds, and the like. These heat-reactive latent epoxy resin curing agents may be used alone in 1 kind or in combination of 2 or more kinds. The thermally active latent epoxy resin curing agent is preferably used in a proportion of 0.1 to 20 parts by weight, particularly preferably 0.2 to 10 parts by weight, and more preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the epoxy resin.
The phenol resin may be, but is not particularly limited to, a condensate of a phenol such as an alkylphenol, a polyphenol, or naphthol, and an aldehyde. Specifically, for example: phenol novolac resin, o-cresol novolac resin, p-cresol novolac resin, t-butylphenol novolac resin, dicyclopentadiene cresol resin, poly-p-vinylphenol resin, bisphenol a type novolac resin, or modified products thereof.
The phenolic hydroxyl group contained in these phenolic resins can be easily subjected to an addition reaction with the epoxy group of the epoxy resin by heating, and a cured product having high impact resistance can be formed. Therefore, an epoxy resin and a phenol resin may be used in combination as a thermosetting component.
The binder polymer component can impart appropriate tackiness to the protective film forming film 1, thereby improving the workability of the protective film forming composite sheet 3. The weight average molecular weight of the binder polymer is usually in the range of 5 to 200 ten thousand, preferably 10 to 150 ten thousand, and particularly preferably 20 to 100 ten thousand. If the molecular weight is too low, the film formation of the protective film forming film 1 is insufficient, and if it is too high, the compatibility with other components is deteriorated, and as a result, uniform film formation is inhibited. As such a binder polymer, for example: acrylic polymers, polyester resins, phenoxy resins, polyurethane resins, silicone resins, rubber-based polymers, and the like, and acrylic polymers are particularly preferably used.
Examples of the acrylic polymer include: a (meth) acrylate copolymer of a (meth) acrylate monomer and a structural unit derived from a (meth) acrylic acid derivative. Here, as the (meth) acrylate monomer, alkyl (meth) acrylates having an alkyl group of 1 to 18 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and the like, are preferably used. Examples of the (meth) acrylic acid derivative include (meth) acrylic acid, glycidyl (meth) acrylate, and hydroxyethyl (meth) acrylate.
Among these, when a glycidyl group is introduced into an acrylic polymer using glycidyl methacrylate or the like as a structural unit, compatibility with the epoxy resin as the thermosetting component is improved, the glass transition temperature (Tg) of the protective film forming film 1 after curing is increased, and heat resistance is improved. Among the above, when hydroxyl groups are introduced into an acrylic polymer using hydroxyethyl acrylate or the like as a constituent unit, the adhesion to a work and the adhesive properties can be controlled.
When an acrylic polymer is used as the binder polymer, the weight average molecular weight of the polymer is preferably 10 ten thousand or more, and particularly preferably 15 to 100 ten thousand. The acrylic polymer has a glass transition temperature of usually 20 ℃ or lower, preferably about-70 to 0 ℃, and has adhesiveness at normal temperature (23 ℃).
The compounding ratio of the thermosetting component to the adhesive polymer component was as follows: the thermosetting component is preferably blended in an amount of 50 to 1500 parts by weight, particularly preferably 70 to 1000 parts by weight, and further preferably 80 to 800 parts by weight based on 100 parts by weight of the binder polymer component. When the thermosetting component and the adhesive polymer component are blended in such a ratio, a suitable viscosity is exhibited before curing, a stable pasting operation can be performed, and a protective film having excellent film strength can be obtained after curing.
The protective film forming film 1 preferably contains a colorant and/or a filler, and particularly preferably contains both a colorant and a filler.
As the colorant, for example: in view of improving controllability of light transmittance, the colorant preferably contains an organic colorant. The colorant is preferably composed of a pigment from the viewpoint of improving chemical stability of the colorant (specifically, the ease of dissolution, the ease of color migration, and the extent of change with time can be exemplified).
Examples of the filler include: silica such as crystalline silica, fused silica or synthetic silica, and inorganic fillers such as alumina or glass spheres. Among these, silica is preferable as the filler, synthetic silica is more preferable, and particularly synthetic silica of a type in which a radiation source of α rays, which is a factor causing malfunction of a semiconductor device, is removed as much as possible is most preferable. Examples of the shape of the filler include: spherical, needle-like, amorphous, etc., preferably spherical, and particularly preferably spherical. When the filler is spherical or spherical, diffuse reflection of light hardly occurs, and the spectral profile of the light transmittance of the protective film forming film 1 is easily controlled.
In addition, the protective film forming film 1 may contain a coupling agent. By containing the coupling agent, the adhesiveness/close adhesion of the protective film to the workpiece can be improved after the protective film forming film 1 is cured without impairing the heat resistance of the protective film, and the water resistance (moist heat resistance) can be improved. As the coupling agent, a silane coupling agent is preferable in view of its versatility, cost advantage, and the like.
Examples of the silane coupling agent include: gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, gamma- (methacryloxypropyl) trimethoxysilane, gamma-aminopropyltrimethoxysilane, N-6- (aminoethyl) -gamma-aminopropylmethyldiethoxysilane, N-phenyl-gamma-aminopropyltrimethoxysilane, gamma-ureidopropyltriethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, bis (3-triethoxysilylpropyl) tetrasulfide, beta-3, 4-epoxycyclohexyl) ethyltrimethoxysilane, gamma-glycidoxypropyl-trimethoxysilane, gamma-aminopropyltriethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, gamma-glycidoxypropyl-trimethoxysilane, beta-3-glycidoxypropyl, Methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, imidazolesilane and the like. These silane coupling agents may be used alone in 1 kind, or in a mixture of 2 or more kinds.
The protective film-forming film 1 may further contain a crosslinking agent such as an organic polyisocyanate compound, an organic polyimine compound, or an organic metal chelate compound in order to adjust the cohesive force before curing. In addition, the protective film forming film 1 may further contain an antistatic agent in order to suppress static electricity and improve chip reliability. In addition, the protective film forming film 1 may further contain a flame retardant such as a phosphoric acid compound, a bromine compound, or a phosphorus compound in order to improve the flame retardant property of the protective film and improve the reliability of the package.
In order to effectively function as a protective film, the thickness of the protective film forming film 1 is preferably 3 to 300 μm, particularly preferably 5 to 200 μm, and further preferably 7 to 100 μm.
3. Adhesive layer for clip
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 5 for a jig preferably has desired adhesive strength and removability, and for example: acrylic adhesives, rubber adhesives, silicone adhesives, polyurethane adhesives, polyester adhesives, polyvinyl ether adhesives, and the like. Among them, an acrylic adhesive which has high adhesion to a jig such as an annular frame and can effectively suppress the peeling of the composite sheet for forming a protective film 3 from the annular frame or the like in a dicing step or the like is preferable. The base material serving as the core material may be sandwiched inside the adhesive layer 5 for a jig in the thickness direction.
On the other hand, the thickness of the pressure-sensitive adhesive layer 5 for a jig is preferably 5 to 200 μm, and particularly preferably 10 to 100 μm, from the viewpoint of adhesiveness to a jig such as an annular frame.
4. Release sheet
The release sheet 6 in the present embodiment protects the protective film forming film 1 and the pressure-sensitive adhesive layer 5 for a jig until the protective film forming composite sheet 3 is used.
The structure of the release sheet 6 is arbitrary, and a film obtained by peeling a plastic film with a release agent or the like can be exemplified. Specific examples of the plastic film include: polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. As the release agent, for example: among them, the inexpensive and stable silicone is preferable. The thickness of the release sheet 6 is not particularly limited, and is usually about 20 to 250 μm.
5. Method for manufacturing composite sheet for forming protective film
The composite sheet 3 for forming a protective film is preferably produced by separately producing a1 st laminate including the protective film forming film 1 and a2 nd laminate including the support sheet 4, and then laminating the protective film forming film 1 and the support sheet 4 by using the 1 st laminate and the 2 nd laminate, but is not limited thereto.
In the production of the 1 st laminate, a protective film formation film 1 is formed on the release surface of the 1 st release sheet. Specifically, a coating agent for forming a protective film is prepared, and the coating agent for forming a protective film, which contains a curable adhesive agent constituting the protective film forming film 1 and, if necessary, a solvent, is applied to the release surface of the 1 st release sheet by a coater such as a roll coater, a knife coater, a roll coater, an air knife coater, a die coater, a bar coater, a gravure coater, or a curtain coater, and dried to form the protective film forming film 1. Next, the release surface of the 2 nd release sheet was laminated on the exposed surface of the protective film formation film 1 and pressure-bonded to obtain a laminate (1 st laminate) in which the protective film formation film 1 was sandwiched by the 2 nd release sheets.
The 1 st laminate may be cut into a cutting blade or half-cut by laser irradiation from the 1 st or 2 nd release sheet side as necessary to form the protective film formation film 1 (and the 2 nd release sheet) into a desired shape, for example, a circular shape. In this case, the unnecessary portions of the protective film forming film 1 and the 2 nd release sheet resulting from the half-cut can be appropriately removed.
On the other hand, in the production of the 2 nd laminate, the pressure-sensitive adhesive layer 42 is formed by applying a coating agent for a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 42 and, if necessary, a solvent to the release surface of the 3 rd release sheet and drying the coating agent. Then, the base material 41 was pressure-bonded to the exposed surface of the adhesive layer 42, and a laminate (2 nd laminate) comprising a support sheet 4 and a 3 rd release sheet was obtained, the support sheet 4 being composed of the base material 41 and the adhesive layer 42.
Here, in the case where the adhesive layer 42 is formed of an energy ray-curable adhesive, the adhesive layer 42 may be cured by irradiating the adhesive layer 42 with an energy ray at this stage, or the adhesive layer 42 may be cured after the lamination with the protective film forming film 1. In the case where the pressure-sensitive adhesive layer 42 is cured after the lamination with the protective film forming film 1, the pressure-sensitive adhesive layer 42 may be cured before the dicing step, or the pressure-sensitive adhesive layer 42 may be cured after the dicing step.
As the energy ray, ultraviolet rays, electron beams, or the like are generally used. The dose of the energy ray varies depending on the type of the energy ray, and in the case of ultraviolet rays, for example, the dose is preferably 50 to 1000mJ/cm in terms of light quantity2Particularly preferably 100 to 500mJ/cm2. In addition, in the case of an electron beam, it is preferably about 10 to 1000 krad.
After the 1 st laminate and the 2 nd laminate are obtained as described above, the 2 nd release sheet of the 1 st laminate is peeled off, and the 3 rd release sheet of the 2 nd laminate is peeled off, and the protective film forming film 1 exposed in the 1 st laminate and the adhesive layer 42 of the supporting sheet 4 exposed in the 2 nd laminate are laminated and pressure-bonded. The support sheet 4 may be half-cut as necessary to have a desired shape, for example, a circular shape having a larger diameter than the protective film forming film 1. In this case, the excess portion of the support sheet 4 resulting from the half-cut can be appropriately removed.
As a result, the composite sheet 3 for forming a protective film is obtained, which comprises the support sheet 4, the protective film forming film 1 and the 1 st release sheet, wherein the support sheet 4 is formed by laminating the adhesive layer 42 on the substrate 41, the protective film forming film 1 is laminated on the adhesive layer 42 side of the support sheet 4, and the 1 st release sheet is laminated on the side opposite to the support sheet 4 of the protective film forming film 1. Finally, the 1 st release sheet is peeled off, and then the adhesive layer 5 for a jig is formed at the edge portion of the protective film forming film 1 on the opposite side to the support sheet 4. The jig adhesive layer 5 can be formed by coating in the same manner as the adhesive layer 42 described above.
6. Method for using composite sheet for forming protective film
As an example of using the composite sheet 3 for forming a protective film according to the present embodiment, a method for producing a chip with a protective film from a semiconductor wafer as a workpiece will be described below.
First, the rolled composite sheet 3 for forming a protective film is fed, and as shown in fig. 2, the composite sheet 3 for forming a protective film is attached with the protective film forming film 1 of the composite sheet 3 for forming a protective film being attached to the semiconductor wafer 7, and the adhesive layer 5 for a jig is attached to the ring frame 8.
In the composite sheet 3 for forming a protective film of the present embodiment, the arithmetic mean roughness (Ra1) of the back surface of the base material 41 before heating is 0.2 μm or more, so that blocking is less likely to occur at the time of the feeding, and therefore, the occurrence of a feeding failure can be suppressed, and the failure to attach the sheet to a workpiece can be suppressed.
Then, the protective film forming film 1 is cured to form a protective film, and a laminated structure (hereinafter, also referred to as "laminated structure L") having a structure in which the semiconductor wafer 7 with the protective film is laminated on the surface on the pressure-sensitive adhesive layer 42 side of the support sheet 4 functioning as an extensible dicing sheet is obtained. The multilayer structure L shown in fig. 2 further includes a jig adhesive layer 5 and an annular frame 8. In the case where the protective film forming film 1 is a thermosetting adhesive, the protective film forming film 1 may be heated at a given temperature for an appropriate time. When the protective film forming film 1 is not a thermosetting adhesive, a heating process is separately performed.
The heating temperature is preferably 50 to 200 ℃, particularly preferably 90 to 150 ℃, and the heating time is preferably 0.1 to 10 hours, particularly preferably 1 to 3 hours. The composite sheet 3 for forming a protective film according to the present embodiment has an arithmetic average roughness (Ra2) of the back surface of the base material 41 of 0.25 μm or less by the heat treatment.
After the multilayer structure L including the semiconductor wafer 7 with the protective film is obtained as described above, the protective film is irradiated with laser light through the support sheet 4 as necessary to perform laser printing.
Next, the laminate L is subjected to a stealth dicing step. Specifically, the multilayer structure L is set in a laser irradiation device for division processing, the surface position of the semiconductor wafer 7 coated with the protective film 1 is detected, and then the semiconductor wafer 7 is irradiated with laser light through the support sheet 4 to form a modified layer in the semiconductor wafer 7. Then, by performing a sheet expanding step of expanding the support sheet 4 functioning as a dicing sheet, a force (a tensile force in the direction of the main surface) is applied to the semiconductor wafer 7 with the protective film. As a result, the semiconductor wafer 7 with the protective film attached to the support sheet 4 is divided, and chips with the protective film (chips with the protective film) are obtained. Then, the chip with the protective film is picked up from the support sheet 4 using a pickup device.
The composite sheet 3 for forming a protective film according to the present embodiment is excellent in laser transmissivity by setting the arithmetic average roughness (Ra2) of the back surface of the base material 41 after heating to 0.25 μm or less, and therefore is excellent in laser printability in the laser printing step and can form laser prints having high visibility. In addition, in the stealth dicing step, the workpiece is excellent in separability by stealth dicing.
7. Other embodiment of the composite sheet for forming a protective film
Fig. 3 is a sectional view of a composite sheet for forming a protective film according to another embodiment of the present invention. As shown in fig. 3, the composite sheet 3A for forming a protective film of the present embodiment includes: a support sheet 4 in which the adhesive layer 42 is laminated on one surface of the substrate 41, and a protective film laminated on the adhesive layer 42 side of the support sheet 4 form a film 1. The protective film forming film 1 in the present embodiment is formed substantially the same as the workpiece in the plane direction or formed slightly larger than the workpiece, and is formed smaller than the supporting sheet 4 in the plane direction. The pressure-sensitive adhesive layer 42 of the portion where the protective film forming film 1 is not laminated can be attached to a jig such as a ring frame.
The materials and thicknesses of the respective members of the composite sheet for forming a protective film 3A of the present embodiment are the same as those of the respective members of the composite sheet for forming a protective film 3. In the case where the adhesive layer 42 is formed of an energy ray-curable adhesive, it is preferable that the energy ray-curable adhesive is cured in a portion of the adhesive layer 42 which is in contact with the protective film forming film 1, and the energy ray-curable adhesive is not cured in the other portion. This can not only improve the smoothness (glossiness) of the protective film obtained by curing the protective film forming film 1, but also maintain high adhesion to a jig such as an annular frame.
In the adhesive layer 42 of the support sheet 4 included in the protective film forming composite sheet 3A, a jig adhesive layer similar to the jig adhesive layer 5 of the protective film forming composite sheet 3 may be separately provided at the edge portion on the opposite side of the substrate 41.
The support sheet 4 in the present embodiment may be (only) composed of the base material 41 without the adhesive layer 42. In this case, the surface of the base material 41 on the side where the protective film is formed into a film 1 corresponds to the 1 st surface of the support sheet 4, and the surface of the base material 41 on the side opposite to the side where the protective film is formed into a film 1 corresponds to the 2 nd surface of the support sheet 4.
When the support sheet 4 is formed of the base material 41, the adhesive layer 5 for a jig as shown in fig. 1 is preferably provided on the edge portion of the protective film formation film 1 opposite to the base material 41 (support sheet 4).
The above-described embodiments are described for easy understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments includes all design modifications and equivalents that fall within the technical scope of the present invention.
For example, other layers may be sandwiched between the substrate 41 and the adhesive layer 42 of the support sheet 4. Further, another layer may be laminated on the 1 st surface of the support sheet 4 made of the base material 41.
The composite sheet for forming a protective film of the present invention has an arithmetic average roughness (Ra1) of about 0.51 to 0.65 μm before heating of the back surface of the base material 41, an arithmetic average roughness (Ra2) of about 0.08 to 0.22 after heating at 130 ℃ for 2 hours, a storage modulus of about 13 to 20MPa at 130 ℃ of the base material 41, a light transmittance after heating of about 73 to 91% at 532nm and about 77 to 91% at 1064nm, and thus has more excellent blocking resistance, laser printability and dicing ability.
Examples
The present invention will be described more specifically with reference to examples and the like, but the scope of the present invention is not limited to these examples and the like.
[ example 1 ]
In example 1, a composite sheet 3 for forming a protective film shown in fig. 3 and 4 was produced as follows.
(1) Production of the 1 st laminate comprising a protective film formation film
The following components were mixed at the following mixing ratios (converted to solid contents) and diluted with methyl ethyl ketone so that the solid content concentration became 61 mass%, to prepare a coating agent for forming a protective film.
(A) Adhesive polymer: (meth) acrylate copolymer (weight-average molecular weight: 80 ten thousand, glass transition temperature: -1 ℃ C.) obtained by copolymerizing 10 parts by mass of n-butyl acrylate, 70 parts by mass of methyl acrylate, 5 parts by mass of glycidyl methacrylate, and 15 parts by mass of 2-hydroxyethyl acrylate, and 100 parts by mass of the copolymer
(B-1) bisphenol A epoxy resin (Mitsubishi chemical corporation, jER828, epoxy equivalent 184-194 g/eq)60 parts by mass
(B-2) bisphenol A epoxy resin (Mitsubishi chemical corporation, jER1055, epoxy equivalent 800-900 g/eq)10 parts by mass
(B-3) 30 parts by mass of a dicyclopentadiene type epoxy resin (EPICLON HP-7200HH, epoxy equivalent 255-260 g/eq, manufactured by DIC Co., Ltd.)
(C) Thermally active latent epoxy resin curing agent: dicyandiamide (manufactured by ADEKA corporation, Adeka Harden EH-3636AS, active hydrogen amount 21g/eq)2 parts by mass
(D) Curing accelerator: 2 parts by mass of 2-phenyl-4, 5-dimethylol imidazole (Curezol 2PHZ, manufactured by Siguo Kagaku Co., Ltd.)
(E) 320 parts by mass of silica Filler (SC 2050MA, average particle diameter 0.5 μm, manufactured by Admatechs Co., Ltd.)
(F) Colorant: 0.6 part by mass of carbon black (manufactured by Mitsubishi chemical corporation, # MA650, average particle diameter 28nm)
(G) Silane coupling agent: 0.4 part by mass of gamma-glycidoxypropyltrimethoxysilane (KBM 403, methoxy equivalent: 12.7mmol/g, molecular weight: 236.3, manufactured by shin-Etsu chemical Co., Ltd.)
First, the coating agent for forming a protective film was applied to the release surface of a1 st release sheet (SP-PET 3811, manufactured by Lindco corporation, having a thickness of 38 μm) by a blade coater so that the thickness of the finally obtained protective film-forming film was 25 μm, and the film was dried at 120 ℃ for 2 minutes to form a protective film-forming film. Then, the release surface of the 2 nd release sheet (SP-PET 381031, manufactured by linaceae corporation, thickness 38 μm) was laminated on the protective film forming film, and the two were bonded to each other, thereby obtaining a laminate composed of the 1 st release sheet (release sheet 6 in fig. 3 and 4), the protective film forming film (protective film forming film 1 in fig. 3 and 4), and the 2 nd release sheet. The laminate is long and wound into a roll to form a roll.
The roll of the long laminate thus obtained was cut into a width of 300mm (w in FIG. 4)1Representation). Then, the above-mentioned laminate is laminatedThe body is continuously formed in a circular shape (diameter d) at the widthwise central portion of the laminate from the 2 nd release sheet side1: 220 mm; reference numeral 101 in fig. 4) so that the 2 nd peel sheet and the protective film forming film are cut off. Then, the 2 nd release sheet and the protective film forming film existing outside the circular shape formed by half-cutting are removed. Thus, a1 st laminate was obtained in which a circular protective film forming film was laminated on the release surface of the 1 st release sheet, and a circular 2 nd release sheet was laminated thereon.
(2) Production of No. 2 laminate comprising support sheet
The following (H) and (I) components were mixed and diluted with methyl ethyl ketone so that the solid content concentration was 30 mass%, to prepare a coating agent for an adhesive layer.
(H) A main adhesive agent: (meth) acrylate ester copolymer (copolymer obtained by copolymerizing 40 parts by mass of butyl acrylate, 55 parts by mass of 2-ethylhexyl acrylate and 5 parts by mass of 2-hydroxyethyl acrylate, weight average molecular weight: 60 ten thousand) 100 parts by mass
(I) A crosslinking agent: 10 parts by mass of an aromatic polyisocyanate compound (Takenate D110N, manufactured by Mitsui chemical Co., Ltd.)
Next, an ethylene-propylene copolymer film was produced, one surface of which (corresponding to the back surface of the base material (the 2 nd surface of the support sheet)) had an arithmetic average roughness before heating (Ra1) and an arithmetic average roughness after heating (130 ℃/2 hours) (Ra2), a melting point and a storage modulus at 130 ℃ adjusted as shown in table 1 below, and the other surface of the film was subjected to corona treatment to obtain a base material. The arithmetic mean roughness (Ra1) before heating was adjusted by changing the arithmetic surface roughness of the surface of the metal roll on the back side of the substrate when the substrate was formed. The arithmetic mean roughness (Ra2) after heating was adjusted by changing the copolymerization ratio of ethylene and propylene in the ethylene-propylene copolymer constituting the substrate.
A release sheet (SP-PET 381031, manufactured by Linekeko Co., Ltd.) was prepared by forming a silicone release agent layer on one surface of a PET film having a thickness of 38 μm, and the release surface of the release sheet was coated with a doctor blade coaterThe coating agent for an adhesive layer was applied so that the thickness of the adhesive layer finally obtained was 10 μm, and dried to form an adhesive layer. Then, the corona-treated surface of the base material was laminated on the adhesive layer, and the two were bonded to each other, thereby obtaining a2 nd laminate composed of a support sheet (support sheet 4 in fig. 3 and 4) composed of a base material (base material 41 in fig. 3) and an adhesive layer (adhesive layer 42 in fig. 3) and a release sheet. The laminate was a long strip, wound into a roll to form a roll, and cut into a width of 300mm (w in FIG. 4)1Representation).
(3) Production of composite sheet for Forming protective film
The circular 2 nd release sheet was peeled from the 1 st laminate obtained in the above (1) to expose the circular protective film formation film. On the other hand, the release sheet was peeled from the 2 nd laminate obtained in the above (2) to expose the adhesive layer. The 1 st laminate and the 2 nd laminate were laminated so that the protective film forming film was in contact with the adhesive layer, and a 3 rd laminate was obtained by laminating a support sheet composed of a base material and an adhesive layer, a protective film forming film, and a1 st release sheet.
Next, the 3 rd laminate was half-cut from the base material side so that the supporting sheet (base material and adhesive layer) was cut. Specifically, as shown in fig. 4, a protective film forming film (diameter d) larger than the circular shape is formed1: 220mm) larger concentric circles (diameter d)2: 270 mm; symbol 401 in fig. 4; a circular support piece) and is formed with a spacing of 20mm from the circular shape to the outside (in fig. 4, w)2Indicated) of the circular arc (symbol 402 in fig. 4). Further, 2 straight lines (reference numeral 403 in fig. 4) parallel to the end portions in the width direction of the 3 rd laminated body are formed between the adjacent circular shapes, and the adjacent circular arcs are connected to the straight lines.
Then, the portions between the circular support piece and the circular arc and the portions sandwiched by the 2 straight lines were removed, and a composite sheet for forming a protective film shown in fig. 3 and 4 was obtained.
[ examples 2 to 5 and comparative examples 1 to 3 ]
Composite sheets for forming a protective film of examples 2 to 5 and comparative examples 1 to 3 were produced in the same manner as in example 1 except that the arithmetic average roughness (Ra1) before heating and the arithmetic average roughness (Ra2) after heating, the melting point, and the storage modulus at 130 ℃.
[ test example 1 ] measurement of arithmetic mean roughness of base Material
Using a contact surface roughness meter (SURFTEST SV-3000, manufactured by MITUTOYO corporation), the cutoff λ c was set to 0.8mm, the evaluation length Ln was set to 4mm, and the surface roughness was measured in accordance with JIS B0601: 2001 the arithmetic mean roughness before heating (Ra 1: μm) and the arithmetic mean roughness after heating (Ra 2: μm) of the back surface of the base material used in the examples and comparative examples were measured. The results are shown in table 1 below.
The arithmetic mean roughness (Ra2) after heating was measured by heating the composite sheets for protective film formation of examples and comparative examples, which were provided with the above-described base materials, in an oven at 130 ℃ for 2 hours in an atmospheric atmosphere while being fixed to an annular frame, leaving them to stand, and cooling to room temperature. During this heat treatment, the measurement surface (the back surface of the substrate) was not in contact with the inner wall and the bottom in the oven.
[ test example 2 ] measurement of melting Point of base Material >
The melting peak temperature of the substrate used in the examples and comparative examples was determined by using a differential scanning calorimeter (Q2000, manufactured by TA INSTRUMENTS) in accordance with JIS K7121(ISO 3146). Specifically, the substrate was heated at 10 ℃ per minute from 23 ℃ to 200 ℃ and the DSC curve was plotted. The melting peak temperature (. degree. C.) was determined from the obtained DSC curve at the time of temperature rise. The results are shown in table 1 below.
[ test example 3 ] measurement of storage modulus of substrate >
For the substrates used in examples and comparative examples, the storage modulus at 130 ℃ was measured by the following apparatus and conditions. The results are shown in table 1 below.
A measuring device: dynamic elastic modulus measuring device "DMA Q800", manufactured by TA INSTRUMENTS Inc "
Test start temperature: 0 deg.C
Test end temperature: 200 deg.C
Temperature rise rate: 3 ℃/min
Frequency: 11Hz
Amplitude: 20 μm
[ test example 4 ] < measurement of light transmittance >
After heating the substrates used in examples and comparative examples at 130 ℃ for 2 hours as shown in test example 1, the light transmittance at a wavelength of 200 to 1200nm was measured using an ultraviolet-visible spectrophotometer (UV-3101 PC, manufactured by Shimadzu corporation, without using an integrating sphere) for the heated substrates, and the measured values at wavelengths of 532nm and 1064nm were read. The results are shown in table 1 below.
[ test example 5 ] < evaluation of anti-blocking Property >
The 1 st release sheet was peeled from the composite sheet for protective film formation produced in examples and comparative examples. The obtained composite sheet for forming a protective film was bonded to a silicon wafer (outer diameter: 8 inches, thickness: 100 μm) and an annular frame (made of stainless steel) in a roll-to-roll manner at 70 ℃ using a bonding apparatus (RAD-2700F/12, manufactured by Lingdeko Co., Ltd.). At this time, 10 sheets of the paste operation were continuously performed, and the blocking resistance was evaluated based on the following criteria. The results are shown in table 1 below.
A: the pasting can be performed without any problem (no blocking at all occurs).
B: the adhesive layer can be adhered to the base material, but the base material and the release sheet on the back side of the base material are partially adhered to each other, and when the composite sheet for forming a protective film is fed out, the release sheet is partially peeled from the upper portion of the adhesive layer or the protective film forming film.
C: a defective adhesion (blocking) occurs, for example, when at least 1 supporting sheet is transferred to the back side of the base material, or when the composite sheet for forming the protective film cannot be fed out.
[ test example 6 ] < evaluation of laser printability >
The 1 st release sheet was peeled from the composite sheet for protective film formation produced in examples and comparative examples. The obtained composite sheet for forming a protective film was bonded to a silicon wafer (outer diameter: 8 inches, thickness: 100 μm) and an annular frame (made of stainless steel) at 70 ℃ by using a bonding apparatus (RAD-2700F/12, manufactured by Lingdeko Co., Ltd.). Then, heat treatment was performed at 130 ℃ for 2 hours to thermally cure the protective film-forming film to form a protective film.
Next, the protective film was irradiated with a laser beam having a wavelength of 532nm through the supporting sheet by using a printer (MD-T1000, manufactured by KEYENCE corporation), and laser printing was performed on the protective film under the following conditions.
Condition 1 … text size: 0.4mm × 0.5mm, text interval: 0.3mm, number of words: 20 character
Condition 2 … text size: 0.2mm × 0.5mm, text interval: 0.3mm, number of words: 20 character
The visibility (laser printability) of laser-printed characters formed on a protective film through a support sheet was evaluated based on the following criteria. The results are shown in table 1 below.
A: all the letters under condition 1 and condition 2 can be read without problems.
B: in condition 2, although there is an unclear portion, the entire character can be read without any problem in condition 1.
C: there are unclear portions in both condition 1 and condition 2.
[ test example 7 ] < evaluation of cutting Dividence >
The 1 st release sheet was peeled from the composite sheet for protective film formation produced in examples and comparative examples. The obtained composite sheet for forming a protective film was bonded to a silicon wafer (outer diameter: 8 inches, thickness: 100 μm) and an annular frame (made of stainless steel) at 70 ℃ by using a bonding apparatus (RAD-2700F/12, manufactured by Lingdeko Co., Ltd.). Then, heat treatment was performed at 130 ℃ for 2 hours to thermally cure the protective film-forming film to form a protective film.
Next, the obtained silicon wafer with a protective film was subjected to a dividing process by stealth dicing, which was performed by a laser dicing machine (manufactured by DISCO corporation, DFL 7360).
(step 1) the silicon wafer and the ring frame to which the composite sheets for forming a protective film of examples and comparative examples were attached were set at predetermined positions on a laser beam cutter so that the laser beam could be irradiated from the support sheet side (back side of the base material).
(step 2) the surface position of the silicon wafer coated with the protective film was detected, and then the focal position of the laser beam from the laser dicing machine was set, and the laser beam having a wavelength of 1064nm from the laser dicing machine was irradiated 10 times from the protective film side along the line to cut which was set so as to form a 9mm × 9mm chip body on the silicon wafer with the protective film, thereby forming a modified layer in the silicon wafer.
(step 3) the silicon wafer and the ring frame to which the composite sheet for forming a protective film was attached were set in a die cutter (DDS 2300, manufactured by DISCO Co.) and the sheet was expanded at a drawing speed of 100 mm/sec and an expansion amount of 10 mm.
Through the above steps, at least a part of the silicon wafer having the modified layer formed therein is divided along the lines to be divided, and a plurality of chips with protective films are obtained. Based on the dividing ratio in this case (number of chips obtained by actual division/number of chips obtained by predetermined division) × 100) (%), the dicing ability was evaluated in accordance with the following criteria. The results are shown in Table 1.
A: chip dividing rate of 100% (good dividing property)
B: the chip dividing ratio is more than 90% and less than 100% (with allowable dividing property)
C: the chip dividing ratio is 80% or more and less than 90% (with allowable dividing property)
D: chip separation ratio lower than 80% (without allowable separability)
TABLE 1
Figure BDA0001155972010000281
As is clear from table 1, the composite sheet for forming a protective film of the example in which the arithmetic mean roughness (Ra1) of the back surface of the base material before heating was 0.2 μm or more and the arithmetic mean roughness (Ra2) of the back surface of the base material after heating at 130 ℃ for 2 hours was 0.25 μm or less was excellent in blocking resistance and also excellent in laser printability and dicing ability.
Industrial applicability
The composite sheet for forming a protective film of the present invention is suitable for use in a case where the composite sheet includes a step of irradiating a substrate with laser light so as to transmit the substrate, such as laser printing or stealth dicing.

Claims (8)

1. A composite sheet for forming a protective film, comprising:
a support sheet having a base material,
A protective film forming film laminated on the 1 st surface side of the support sheet, and
a release sheet laminated on the protective film forming film,
wherein the content of the first and second substances,
the support sheet has an arithmetic average roughness Ra1 of 0.47 [ mu ] m or more on the 2 nd surface,
the arithmetic average roughness Ra2 of the 2 nd surface of the support sheet is 0.25 [ mu ] m or less after the support sheet is heated at 130 ℃ for 2 hours,
the melting point of the base material is 90-131 ℃.
2. The composite sheet for forming a protective film according to claim 1, wherein the support sheet is composed of a base material, or is composed of a base material and an adhesive layer laminated on the 1 st surface side of the support sheet on one surface side of the base material.
3. The composite sheet for forming a protective film according to claim 1 or 2, wherein the storage modulus of the base material at 130 ℃ is 1 to 100 MPa.
4. The composite sheet for forming a protective film according to claim 1 or 2, wherein the substrate has a light transmittance of 40% or more at a wavelength of 1064nm after the heating.
5. The composite sheet for forming a protective film according to claim 1 or 2, wherein the substrate has a transmittance of 40% or more for light having a wavelength of 532nm after the heating.
6. The composite sheet for forming a protective film according to claim 1 or 2, wherein the substrate is a film made of a copolymer of ethylene and propylene.
7. The composite sheet for forming a protective film according to claim 1 or 2, wherein the composite sheet for forming a protective film comprises an adhesive layer for a jig, and the adhesive layer for a jig is laminated on an edge portion of the protective film forming film on the side opposite to the supporting sheet side.
8. The composite sheet for forming a protective film according to claim 1 or 2, wherein the protective film forming film is a layer for forming a protective film on a semiconductor wafer or a layer for forming a protective film on a semiconductor chip obtained by dicing a semiconductor wafer.
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CN106463373A (en) 2017-02-22
WO2015178346A1 (en) 2015-11-26
TW201940624A (en) 2019-10-16
SG11201609543VA (en) 2016-12-29
JP6319433B2 (en) 2018-05-09
JPWO2015178346A1 (en) 2017-04-20
KR20170008749A (en) 2017-01-24
PH12016502286A1 (en) 2017-02-13
TW201602303A (en) 2016-01-16
KR102378063B1 (en) 2022-03-23

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