JP2010232367A - Method of transferring thin-film layer and adhesive tape for thin-film layer transfer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of easily transferring a thin-film layer formed on a substrate to a transfer member with an excellent yield, and also to provide an adhesive tape for thin-film layer transfer. <P>SOLUTION: The method of transferring the thin-film layer includes processes of: forming a TFT 10 (thin-film layer) on an isolation layer 2 formed on the substrate 1; sticking the adhesive tape 15, which is composed by providing an adhesive layer 16 containing a side-chain crystalline polymer on one surface of a base film 17 and whose adhesive power is to decline at a temperature lower than a melting point of the side-chain crystalline polymer, on the TFT 10; isolating the TFT 10 and the substrate 1 by irradiating the isolation layer 2 with light and transferring the TFT 10 from the substrate 1 to the adhesive tape 15; attaching the transferred TFT 10 onto the transfer member 21 through the adhesive layer 20; and lowering the adhesive power of the adhesive tape 15 and transferring the TFT 10 from the adhesive tape 15 to the transfer member 21. The adhesive tape for thin-film layer transfer comprises the adhesive tape 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for transferring a thin film layer formed on a substrate to a transfer member, and an adhesive tape for transferring the thin film layer.

  A thin film layer such as a thin film transistor (TFT) is usually used in a state of being laminated on a transparent and flexible resin substrate. On the other hand, in the process of forming the TFT, the atmospheric temperature is often higher than the glass transition temperature of the resin substrate. Therefore, when the TFT is directly formed on the resin substrate, there is a problem that the resin substrate is thermally deformed. In order to solve this problem, after forming a TFT on a heat-resistant substrate, the TFT is transferred onto a resin substrate (see, for example, Patent Document 1).

The transfer of the TFT from the heat-resistant substrate to the resin substrate is generally performed through the following steps (i) to (v).
(I) A TFT is formed on a heat-resistant substrate through a separation layer,
(Ii) Affixing an adhesive tape on the TFT,
(Iii) irradiating the separation layer with light to separate the TFT and the heat-resistant substrate, transferring the TFT from the heat-resistant substrate to an adhesive tape,
(Iv) After the transferred TFT is bonded onto the resin substrate via the adhesive layer,
(V) The adhesive tape is peeled from the TFT, and the TFT is transferred from the adhesive tape to the resin substrate.

  However, a normal pressure-sensitive adhesive tape has a problem that it is difficult to peel off from the TFT in the step (v). For this reason, excessive force is applied to the TFT when the adhesive tape is peeled off, causing deformation or breakage. In addition, the adhesive layer may remain on the TFT, so-called adhesive residue may increase. Furthermore, since the peeled adhesive tape cannot be used repeatedly, it is not economical.

JP 2004-111905 A

  An object of the present invention is to provide a method for easily transferring a thin film layer formed on a substrate onto a transfer member with good yield, and an adhesive tape for transferring a thin film layer.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a solution means having the following constitution and have completed the present invention.
(1) A method of transferring a thin film layer formed on a substrate to a transfer member, a step of forming a separation layer on the substrate, a step of forming a thin film layer on the separation layer, and on the thin film layer, A step of applying a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive layer containing a side-chain crystalline polymer on one side of the base film and having a lower adhesive strength at a temperature lower than the melting point of the side-chain crystalline polymer; Irradiating the layer with light, separating the thin film layer and the substrate, transferring the thin film layer from the substrate to the adhesive tape, bonding the transferred thin film layer onto the transfer member via the adhesive layer, and A method of transferring the thin film layer, comprising: reducing the adhesive force by setting the temperature of the adhesive tape to a temperature lower than the melting point of the side chain crystalline polymer, and transferring the thin film layer from the adhesive tape to the transfer member. .
(2) The method for transferring a thin film layer according to (1), wherein the substrate has translucency, and the separation layer is irradiated with light through the translucent substrate.
(3) The method for transferring a thin film layer according to (1) or (2), wherein the thin film layer is a thin film transistor.
(4) The method for transferring a thin film layer according to any one of (1) to (3), wherein the transfer member is made of a resin substrate.
(5) The method for transferring a thin film layer according to any one of (1) to (4), wherein the separation layer is made of hydrogen-containing amorphous silicon.
(6) The method for transferring a thin film layer according to any one of (1) to (5), wherein an underlayer is interposed between the separation layer and the thin film layer.
(7) A thin film characterized in that a pressure-sensitive adhesive layer containing a side chain crystalline polymer is provided on one side of a base film, and the adhesive strength decreases at a temperature lower than the melting point of the side chain crystalline polymer. Adhesive tape for layer transfer.

  According to the present invention, a pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing a side-chain crystalline polymer provided on one side of a base film and having a lower adhesive strength at a temperature lower than the melting point of the side-chain crystalline polymer is used. Then, the thin film layer formed on the substrate is transferred to the transfer member. And when peeling an adhesive tape from a thin film layer, this adhesive tape is cooled to the temperature below melting | fusing point of the said side chain crystalline polymer, and it peels, after reducing adhesive force. Thereby, since an adhesive tape can be easily peeled from a thin film layer, the fall of the yield by a thin film layer deform | transforming or damaged at the time of adhesive tape peeling, or many adhesive residues generate | occur | producing can be suppressed. And since the said adhesive tape utilizes the phase change of a side chain crystalline polymer, it can be used repeatedly.

(A)-(f) is process drawing which shows one Embodiment of the transfer method of the thin film layer concerning this invention.

  First, the adhesive tape for thin film layer transfer (hereinafter referred to as adhesive tape) used in the present invention will be described. The pressure-sensitive adhesive tape is provided with a pressure-sensitive adhesive layer containing a side chain crystalline polymer on one side of a base film.

  The side-chain crystalline polymer is crystallized at a temperature lower than the melting point, and exhibits phase change at a temperature higher than the melting point. That is, the side chain crystalline polymer reversibly causes a crystalline state and a fluid state in response to a temperature change. The pressure-sensitive adhesive layer contains the side-chain crystalline polymer in such a ratio that the adhesive strength decreases when the side-chain crystalline polymer is crystallized at a temperature lower than the melting point. Accordingly, when the pressure-sensitive adhesive tape is peeled from the thin film layer, if the pressure-sensitive adhesive tape is cooled to a temperature lower than the melting point of the side-chain crystalline polymer, the side-chain crystalline polymer is crystallized to cause the adhesive strength. Decreases. In addition, if the pressure-sensitive adhesive tape is heated to a temperature equal to or higher than the melting point of the side chain crystalline polymer, the side chain crystalline polymer exhibits fluidity and exhibits adhesive strength, and therefore can be used repeatedly.

  The melting point means a temperature at which a specific portion of the polymer originally aligned in an ordered arrangement becomes disordered by an equilibrium process, and is measured by a differential thermal scanning calorimeter (DSC) at 10 ° C./min. It is a value obtained by measuring under conditions. The melting point is 0 ° C. or higher, preferably 10 to 60 ° C. The melting point can be arbitrarily set by changing the composition of the side chain crystalline polymer.

  As the composition of the side chain crystalline polymer, for example, 20 to 100 parts by weight of (meth) acrylate having a linear alkyl group having 16 or more carbon atoms and (meth) acrylate 0 having an alkyl group having 1 to 6 carbon atoms. Examples include a polymer obtained by polymerizing ˜70 parts by weight and 0-10 parts by weight of a polar monomer.

  Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms as a side chain include carbon such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylate having a linear alkyl group of 16 to 22 is exemplified, and examples of the (meth) acrylate having an alkyl group of 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, Examples of the polar monomer include butyl (meth) acrylate and hexyl (meth) acrylate. Examples of the polar monomer include carboxyl group-containing ethylenically unsaturated monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid. Body; 2-hydroxyethyl (meth) acrylate, - hydroxypropyl (meth) acrylate, 2-hydroxyhexyl (meth) ethylenically unsaturated monomer having a hydroxyl group such as acrylate and the like, which may be used alone or in combination.

  The polymerization method is not particularly limited, and for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method and the like can be employed. For example, when the solution polymerization method is employed, the monomer can be polymerized by mixing the monomer exemplified above in a solvent and stirring at about 40 to 90 ° C. for about 2 to 10 hours.

  The side chain crystalline polymer has a weight average molecular weight of 100,000 or more, preferably 400,000 to 900,000. If the weight average molecular weight is too small, the adhesive residue may increase when the adhesive tape is peeled from the thin film layer. On the other hand, if the weight average molecular weight is too large, it is difficult to crystallize even if the side chain crystalline polymer is at a temperature lower than the melting point. The weight average molecular weight is a value obtained by measuring a side chain crystalline polymer by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

  On the other hand, as the base film, for example, polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, polyvinyl chloride, etc. A synthetic resin film is mentioned. Moreover, this film may consist of a single layer body or these multilayer bodies, and thickness is about 25-250 micrometers normally. In order to improve the adhesion to the pressure-sensitive adhesive layer, the surface of the base film may be subjected to surface treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, and primer treatment.

  In order to provide the pressure-sensitive adhesive layer on one side of the base film, for example, a polymer solution obtained by adding the polymer to a predetermined solvent may be applied to one side of the base film and dried. Various additives such as a crosslinking agent, a tackifier, a plasticizer, an anti-aging agent, and an ultraviolet absorber can be added to the polymer solution.

  The application can be generally performed by a knife coater, a roll coater, a calendar coater, a comma coater or the like. Further, depending on the coating thickness and the viscosity of the material, a gravure coater, a rod coater or the like can be used. The thickness of the pressure-sensitive adhesive layer is 5 to 60 μm, preferably 10 to 60 μm, more preferably 10 to 40 μm.

  Next, an embodiment of a method for transferring a thin film layer according to the present invention using the above-described adhesive tape will be described in detail with reference to the drawings, taking a TFT as an example of the thin film layer. 1A to 1F are process diagrams showing a thin film layer transfer method according to the present embodiment.

  As shown in FIG. 1A, first, a separation layer 2 is formed on a substrate 1. The substrate 1 has translucency. Thereby, the separation layer 2 can be irradiated with light through the substrate 1. Moreover, it is preferable that the board | substrate 1 is comprised with the material excellent in heat resistance. Thereby, even if the atmospheric temperature becomes high when forming the TFT 10 described later, the thermal deformation of the substrate 1 can be suppressed, and the TFT 10 can be formed stably.

  Examples of the material constituting the substrate 1 include quartz glass. As thickness of the board | substrate 1, about 0.1-5 mm is suitable. If the thickness of the substrate 1 is too large, the translucency may be lowered. If the thickness of the substrate 1 is too small, the rigidity of the substrate 1 is lowered.

  The separation layer 2 has the property of absorbing light when irradiated with light and causing separation in the layer or at the interface. Examples of such a separation layer 2 include those made of hydrogen-containing amorphous silicon. That is, when the separation layer 2 made of hydrogen-containing amorphous silicon is irradiated with light, hydrogen is released and an internal pressure is generated in the separation layer 2 to cause the separation.

  The hydrogen content in the amorphous silicon is 2 atomic% or more, preferably about 2 to 20 atomic%. The separation layer 2 can be formed, for example, by chemical vapor deposition (CVD). The hydrogen content in the amorphous silicon can be adjusted by appropriately setting conditions such as gas composition, gas pressure, gas atmosphere, gas flow rate and the like in the CVD method.

  The thickness of the separation layer 2 is suitably about 1 nm to 20 μm. If the thickness of the separation layer 2 is too small, the thickness of the separation layer 2 will vary and it will be difficult to exfoliate uniformly. On the other hand, if the thickness of the separation layer 2 is too large, it is difficult to cause peeling even when irradiated with light.

After forming the separation layer 2 on the substrate 1, as shown in FIG. 1B, the TFT 10 is formed on the separation layer 2 through the base layer 3 by a conventional method. The underlayer 3 physically or chemically protects the TFT 10 and functions as a light shielding layer or a reflection layer, and is made of, for example, silicon dioxide (SiO ₂ ). A suitable thickness of the underlayer 3 is about 10 nm to 5 μm.

  Next, as shown in FIG. 1C, an adhesive tape 15 made of the above-mentioned adhesive tape is stuck on the TFT 10. The pressure-sensitive adhesive tape 15 is configured such that a pressure-sensitive adhesive layer 16 containing a side chain crystalline polymer is provided on one side of the base film 17 and the adhesive force is reduced at a temperature lower than the melting point of the side chain crystalline polymer. Has been. Depending on the melting point of the side chain crystalline polymer, the adhesive force of the adhesive tape 15 may not be expressed. In this case, the atmospheric temperature may be heated to a temperature equal to or higher than the melting point of the side chain crystalline polymer using a heating means such as a heater, and the adhesive force of the adhesive tape 15 may be expressed.

  After sticking the adhesive tape 15 on the TFT 10, the separation layer 2 is irradiated with light from the direction of arrow A through the translucent substrate 1. As a result, separation occurs in the separation layer 2 and at the interface, so that the TFT 10 and the substrate 1 can be separated. Therefore, as shown in FIG. 1D, the TFT 10 can be moved together with the base layer 3 in the direction of arrow B, and the TFT 10 can be transferred from the substrate 1 to the adhesive tape 15.

Examples of the light to be irradiated include laser light, and examples of the laser device that generates the laser light include an excimer laser. The excimer laser is a gas laser capable of outputting high-energy laser light in the short wavelength ultraviolet region, and uses a combination of a rare gas (Ar, Kr, Xe) and a halogen gas (F ₂ , HCl) as a laser medium. By using it, it is possible to output laser light having four types of wavelengths (XeF = 351 nm, XeCl = 308 nm, KrF = 248 nm, ArF = 193 nm).

  When the TFT 10 is transferred from the substrate 1 to the adhesive tape 15 and a part of the separation layer 2 is adhered to the lower surface of the base layer 3, the separation layer 2 is subjected to a method such as cleaning, etching, polishing, etc. Adopt and remove.

  Next, as shown in FIG. 1E, the transferred TFT 10 is bonded onto the transfer member 21 via the adhesive layer 20. The adhesive constituting the adhesive layer 20 is not particularly limited as long as the TFT 10 (the base layer 3) and the transfer member 21 can be bonded and fixed. For example, a reactive curable adhesive, a thermosetting adhesive, an ultraviolet ray, and the like. Various well-known things, such as photocurable adhesives, such as a curable adhesive, are employable.

  The adhesive layer 20 can be formed by applying the adhesive on a predetermined portion of the transfer member 21 in advance or by applying the adhesive on the lower surface of the base layer 3. The thickness of the adhesive layer 20 is 1-100 μm, preferably about 10-50 μm. Adhesion is performed by curing the adhesive by a curing method corresponding to each adhesive exemplified above.

  As the transfer member 21, a desired member on which the TFT 10 can be mounted can be adopted, and for example, a resin substrate made of a synthetic resin can be used. Examples of the synthetic resin include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. The resin substrate is preferably transparent and preferably has flexibility. The thickness of the resin substrate is 50 to 300 μm, preferably about 100 to 150 μm.

  Then, after the ambient temperature is cooled to a temperature lower than the melting point of the side chain crystalline polymer to reduce the adhesive strength of the adhesive tape 15, the adhesive tape 15 is moved to an arrow C as shown in FIG. The adhesive tape 15 is peeled from the TFT 10 by moving in the direction. Thereby, the TFT 10 is transferred from the adhesive tape 15 to the transfer member 21. At this time, since the adhesive force of the adhesive tape 15 is sufficiently reduced, it is possible to reduce the load applied to the TFT 10 at the time of peeling, and it is possible to suppress the TFT 10 from being deformed or damaged, and the adhesive residue. Occurrence can also be suppressed. Moreover, the adhesive tape 15 can be repeatedly used many times by performing the same operation as described above.

  In the above-described embodiment, the TFT is described as an example of the thin film layer, but the present invention is not limited to this. That is, other thin film layers according to the present invention other than TFT include, for example, thin film diodes, photosensors, solar cells, electrodes, switching elements, memories, actuators such as piezoelectric elements, filters, and the like.

  In the above-described embodiment, the case where the TFT is formed on the separation layer via the base layer has been described. However, the base layer can be omitted depending on the thin film layer. That is, a thin film layer can also be formed directly on the separation layer.

1 Substrate 2 Separation layer 3 Underlayer 10 TFT
15 Adhesive Tape 16 Adhesive Layer 17 Base Film 20 Adhesive Layer 21 Transfer Member

Claims (7)

A method of transferring a thin film layer formed on a substrate to a transfer member,
Forming a separation layer on the substrate;
Forming a thin film layer on the separation layer;
On this thin film layer, a pressure-sensitive adhesive layer containing a side-chain crystalline polymer is provided on one side of a base film, and an adhesive tape whose adhesive strength decreases at a temperature lower than the melting point of the side-chain crystalline polymer is pasted. And a process of
Irradiating the separation layer with light to separate the thin film layer and the substrate, and transferring the thin film layer from the substrate to the adhesive tape;
Bonding the transferred thin film layer onto the transfer member via an adhesive layer;
Reducing the adhesive force by setting the temperature of the adhesive tape to a temperature lower than the melting point of the side chain crystalline polymer, and transferring the thin film layer from the adhesive tape to the transfer member;
A method for transferring a thin film layer, comprising:   The method for transferring a thin film layer according to claim 1, wherein the substrate has translucency, and the separation layer is irradiated with light through the translucent substrate.   The thin film layer transfer method according to claim 1, wherein the thin film layer is a thin film transistor.   The method for transferring a thin film layer according to claim 1, wherein the transfer member is made of a resin substrate.   The method for transferring a thin film layer according to claim 1, wherein the separation layer is made of hydrogen-containing amorphous silicon.   The method for transferring a thin film layer according to claim 1, wherein a base layer is interposed between the separation layer and the thin film layer.   For thin film layer transfer, characterized in that a pressure-sensitive adhesive layer containing a side chain crystalline polymer is provided on one side of a base film, and the adhesive strength is reduced at a temperature below the melting point of the side chain crystalline polymer. Adhesive tape.

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