JP2011021049A - Protective tape for etching processing, and etching processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective tape for etching processing capable of protecting a member to be protected in etching processing and being easily removed in peeling off, and an etching processing method using it. <P>SOLUTION: In the protective tape for the etching processing, an adhesive layer 3 is provided on one surface of a base material film 2, and the adhesive layer exhibits reduction of adhesion force when it is heated at a temperature of less than 100°C. The etching processing method includes a step for forming a thin film layer 20 on a surface of the substrate 10, a step for adhering the protective tape onto the thin film layer to cover/protect the thin film layer with the protective tape, a step for performing thin film-formation by etching the substrate from a back surface side opposite to the surface of the substrate, and a step for reducing the adhesion force by heating the adhesive layer of the protective tape at a temperature of less than 100°C and peeling off the protective tape from the thin film layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tape that protects a member to be protected such as a thin film layer during etching, and an etching method using the tape.

  A thin film transistor (TFT: Thin Film Transistor), which is a thin film layer, is usually formed on a heat-resistant substrate. This is because in the process of forming the TFT, the atmospheric temperature often becomes high, and when the TFT is formed on, for example, a resin substrate, the resin substrate may be thermally deformed.

  A glass substrate is often adopted as the substrate having heat resistance. The glass substrate has an appropriate thickness in order to stably manufacture the TFT, and is thinned for the purpose of weight reduction after the TFT is formed. This thinning is often performed by etching to uniformly thin the glass substrate.

  The etching is performed by immersing the glass substrate in an etching solution. At this time, it is necessary to protect the circuit surface of the TFT from the etching solution. If an adhesive tape is used as a TFT protection means at the time of etching, it may be possible to easily protect the TFT.

  However, the pressure-sensitive adhesive tape provided with a general acrylic pressure-sensitive adhesive layer is not sufficiently resistant to etching liquid, and the etching liquid may enter the interface between the TFT and the pressure-sensitive adhesive tape to damage the circuit surface of the TFT. is there. Further, a general adhesive tape has a problem that it is difficult to peel off from the TFT. Therefore, an excessive force is applied to the TFT or the thinned glass substrate when the adhesive tape is peeled off, and the TFT or the glass substrate is deformed or damaged. Furthermore, since the peeled adhesive tape cannot be used repeatedly, it is not economical.

  On the other hand, Patent Document 1 describes a pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer contains a foaming agent in a predetermined pressure-sensitive adhesive, and the pressure-sensitive adhesive force decreases due to expansion or foaming of the foaming agent by heat treatment. According to this pressure-sensitive adhesive tape, the pressure-sensitive adhesive force can be reduced at the time of peeling the pressure-sensitive adhesive tape, so it is considered that the load on the TFT and the like applied at the time of peeling can be reduced.

  However, the adhesive strength of the adhesive tape decreases when heated at a temperature of 100 to 150 ° C. Therefore, the pressure-sensitive adhesive tape requires a large amount of heat energy for reducing the adhesive force and cannot be easily peeled off.

  The TFT may be used in a state where it is transferred from a glass substrate onto a transparent and flexible resin substrate. In this case, it is necessary to remove the thinned glass substrate by etching, transfer the TFT onto the resin substrate, and then peel the adhesive tape from the TFT.

  However, in the pressure-sensitive adhesive tape described in Patent Document 1, the atmosphere temperature at the time of peeling of the pressure-sensitive adhesive tape may be higher than the glass transition temperature of the resin substrate. There is a risk of deformation.

JP-A-5-43851

  An object of the present invention is to provide a protective tape for etching process that can protect a member to be protected at the time of etching process and can be easily removed at the time of peeling, and an etching process method using the same.

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) An etching protective mask comprising an adhesive layer provided on one side of a base film, wherein the adhesive layer exhibits a decrease in adhesive strength when heated at a temperature of less than 100 ° C. .
(2) The etching processing protection according to (1), wherein the pressure-sensitive adhesive layer contains a pressure-sensitive adhesive and a side-chain crystalline polymer, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the side-chain crystalline polymer. tape.
(3) The pressure-sensitive adhesive layer is a copolymer of (meth) acrylate having a linear alkyl group having 16 to 22 carbon atoms, butyl acrylate, and a monomer copolymerizable with the (meth) acrylate and butyl acrylate. The protective tape for etching according to the above (1), which contains a polymer.
(4) A step of forming a thin film layer on the surface of the substrate, a step of attaching the protective tape according to claim 1 to the thin film layer, covering and protecting the thin film layer with the protective tape, and the substrate, Etching from the back side opposite to the front surface of the substrate to form a thin film, and heating the pressure-sensitive adhesive layer of the protective tape at a temperature of less than 100 ° C. to reduce the adhesive force, and peeling the protective tape from the thin-film layer And an etching method comprising the steps of:
(5) The etching method according to (4), wherein the etching is performed by immersing the substrate in an etching solution.
(6) The thinned substrate is further removed by etching, the thin film layer is bonded to the surface of the transfer member via an adhesive layer, and then the protective tape is peeled off from the thin film layer (4) or (5) ) Etching method described.
(7) The etching method according to any one of (4) to (6), wherein an etch stopper layer is interposed between the substrate and the thin film layer.

In the present invention, the phrase “expressing a decrease in adhesive strength” means that the rate of decrease in adhesive strength calculated from the following formula (I) is 70% or more, preferably 80% or more.

  When the protective tape for etching according to the present invention is attached to a member to be protected, the adhesive layer of the protective tape adheres to the surface of the member following the surface shape of the member to be protected. There is an effect that can be protected. Moreover, since an adhesive force can be reduced by heating an adhesive layer to the temperature below 100 degreeC after an etching process, a protective tape can be easily peeled from a to-be-protected member. Moreover, even when the member to be protected is transferred from the glass substrate to a transfer member such as a resin substrate, the adhesive tape exhibits a decrease in adhesive strength when heated at a temperature of less than 100 ° C. It is possible to suppress thermal deformation of the resin substrate due to the atmospheric temperature at the time of peeling. Furthermore, since the reduced adhesive force recovers when cooled to a predetermined temperature, it can be used repeatedly.

(A)-(d) is process drawing which shows one Embodiment concerning the etching processing method of this invention. (A)-(d) is process drawing which shows other embodiment concerning the etching processing method of this invention.

<Protective tape for etching>
(First embodiment)
Hereinafter, a first embodiment of a protective tape for etching according to the present invention (hereinafter sometimes referred to as “protective tape”) will be described. The protective tape concerning this embodiment is equipped with the base film and the adhesive layer provided in the single side | surface of this base film.

  Examples of the base film include synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. Examples include a single layer of a film or a multilayer of these.

  The base film preferably employs a film having low rigidity so as not to prevent the pressure-sensitive adhesive layer from adhering to the protected member. Specifically, it is preferable to employ a polyolefin film such as polyethylene or polypropylene. Further, when a base film having a relatively high rigidity, such as a polyethylene terephthalate film, is employed, it is preferable to reduce the thickness to reduce the rigidity.

  The base film preferably has resistance to an etching solution. Examples of such a base film include synthetic resin films such as polyethylene, polyethylene terephthalate, polypropylene, and polyester.

  As thickness of the said base film, about 5-500 micrometers is suitable. In order to improve the adhesiveness with respect to an adhesive layer, surface treatments, such as a corona discharge process, a plasma process, a blast process, a chemical etching process, a primer process, an annealing process, can be given to a base film, for example.

  On the other hand, the adhesive layer exhibits a decrease in adhesive strength when heated at a temperature of less than 100 ° C. Specifically, the pressure-sensitive adhesive layer according to this embodiment contains a pressure-sensitive adhesive and a side chain crystalline polymer.

  The pressure-sensitive adhesive is not particularly limited as long as it is a polymer having tackiness. For example, natural rubber adhesive, synthetic rubber adhesive, styrene / butadiene latex base adhesive, acrylic adhesive, and the like. Is mentioned.

  The acrylic adhesive will be described as an example. Examples of the monomer constituting the acrylic adhesive include (meth) acrylates having an alkyl group having 1 to 12 carbon atoms, and the (meth) acrylates. Examples thereof include ethylhexyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate. Moreover, (meth) acrylate etc. which have a hydroxyalkyl group can also be used, As this (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxyhexyl (meth) acrylate etc. are mentioned, for example. It is done. These exemplified monomers can be used alone or in combination of two or more.

  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 polymer obtained by polymerizing the monomer preferably has a weight average molecular weight of 250,000 to 1,000,000. If the weight average molecular weight is too small, there is a risk that so-called adhesive residue, that is, the protective tape remains on the member to be protected when the protective tape is peeled off, will increase. On the other hand, if the weight average molecular weight is too large, the cohesive force becomes too high and the pressure-sensitive adhesive layer becomes difficult to follow the surface shape of the member to be protected, so that the adhesion to the member surface may be reduced. The weight average molecular weight is a value obtained by measuring the polymer by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

  On the other hand, the side chain crystalline polymer is a polymer that crystallizes at a temperature below the melting point and exhibits fluidity at a temperature above 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 protective tape concerning this embodiment contains the said side chain crystalline polymer in the ratio which adhesive force falls, when the side chain crystalline polymer shows fluidity | liquidity at the temperature more than the said melting | fusing point. Accordingly, when the protective tape is peeled off, if the pressure-sensitive adhesive layer of the protective 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, thereby Since the adhesiveness is hindered and the adhesive strength is thereby reduced, the protective tape can be easily removed from the member to be protected. Further, if the protective tape is cooled to a temperature lower than the melting point of the side chain crystalline polymer, the adhesive strength is recovered by crystallization of the side chain crystalline polymer, so that it can be used repeatedly. In this embodiment, the “adhesive strength lowering expression temperature” in the formula (I) means the melting point of the side chain crystalline polymer.

  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 30 ° C. or higher, preferably 30 to 70 ° C. Thereby, when it heats at the temperature of less than 100 degreeC, specifically 30-70 degreeC, an adhesive layer can express the fall of adhesive force. The melting point can be arbitrarily set to a predetermined value 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 include 16 to 16 carbon atoms such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylate having 22 linear alkyl groups can be mentioned. Examples of the (meth) acrylate having 1 to 6 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) ) Acrylate, hexyl (meth) acrylate and the like. 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; 2 -Hydroxyethyl (meth) acrylate, 2- Mud 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.

  Moreover, the pressure-sensitive adhesive layer containing the side chain crystalline polymer having the above-described composition exhibits resistance to etching liquid. The reason for this is that by including (meth) acrylate having a relatively large carbon number, that is, (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, the hydrophobicity of the entire pressure-sensitive adhesive layer is improved. This is presumed to be due to this.

  On the other hand, 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 2,000 or more, preferably 2,000 to 20,000. If the weight average molecular weight is too small, the adhesive residue may increase when the protective tape is peeled off. On the other hand, if the weight average molecular weight is too large, even if the temperature of the side chain crystalline polymer is set to a temperature equal to or higher than the melting point, it becomes difficult to show fluidity, so that the adhesive strength is hardly lowered. The weight average molecular weight is a value obtained by measuring the side chain crystalline polymer by GPC and converting the obtained measurement value to polystyrene.

  The side chain crystalline polymer may be contained in a proportion of 1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the pressure-sensitive adhesive in terms of solid content. Thereby, at the time of sticking the protective tape, the pressure-sensitive adhesive layer follows the surface shape of the member to be protected, adheres to the surface of the member, can protect the member to be protected from the etching solution, and is at a temperature equal to or higher than the melting point. When the chain crystalline polymer exhibits fluidity, the adhesive strength of the adhesive layer is reduced. On the other hand, if the content of the side chain crystalline polymer is too small, the adhesive strength is hardly lowered even if the pressure-sensitive adhesive layer is heated to a temperature equal to or higher than the melting point of the side chain crystalline polymer. Moreover, when there is too much content of a side chain crystalline polymer, adhesive force will fall and it will become difficult to protect a to-be-protected member.

  In order to provide the pressure-sensitive adhesive layer on one side of the base film, for example, on one side of the base film, a coating solution in which a pressure-sensitive adhesive and a side chain crystalline polymer are added to a solvent in a predetermined ratio is applied and dried. You can do it. Various additives such as a crosslinking agent, a tackifier, a plasticizer, an anti-aging agent, and an ultraviolet absorber can be added to the coating 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 coating solution, a gravure coater, a rod coater or the like can be used.

  The pressure-sensitive adhesive layer has a thickness of 5 to 60 μm, preferably 10 to 60 μm, more preferably 10 to 40 μm. If the pressure-sensitive adhesive layer is too thin, the adhesion to the member surface may be reduced. Moreover, when the thickness of the said adhesive layer is too large, it will become difficult to prepare an adhesive layer with uniform thickness.

(Second Embodiment)
Next, a second embodiment of the protective tape according to the present invention will be described. The protective tape concerning this embodiment is equipped with the base film and the adhesive layer provided in the single side | surface of this base film. Examples of the base film include the same base film as described for the protective tape according to the first embodiment.

  The said adhesive layer expresses the fall of adhesive force, when heated at the temperature below 100 degreeC similarly to the masking tape concerning above-mentioned 1st Embodiment. Specifically, the pressure-sensitive adhesive layer according to this embodiment is a copolymer of (meth) acrylate having a linear alkyl group having 16 to 22 carbon atoms, butyl acrylate, and the (meth) acrylate and butyl acrylate. It contains a copolymer of possible monomers as a main component.

  The pressure-sensitive adhesive layer having such a composition can adhere to the surface of the member following the surface shape of the member to be protected and protect the member to be protected from the etching solution. And the adhesive layer which consists of the said composition expresses the fall of adhesive force, when it heats to the temperature below 100 degreeC. The reason for this is presumed as follows.

  That is, the copolymer containing (meth) acrylate having a linear alkyl group having 16 to 22 carbon atoms and butyl acrylate has increased heat mobility, and when heated, the adhesive strength decreases. Since the behavior to do becomes remarkable, when it heats at the temperature of less than 100 degreeC, specifically 30-70 degreeC, it comes to express the fall of adhesive force. The reduced adhesive strength is usually recovered when cooled to 5 to 10 ° C. or lower of the adhesive strength lowering expression temperature, and can be used repeatedly. In the present embodiment, the “adhesive strength lowering temperature” in the formula (I) is a measurement of a 180 ° peel strength in accordance with JIS Z0237 at a predetermined atmospheric temperature, and actually measuring the temperature at which the adhesive strength is reduced. Means the value obtained. In order to make the said adhesive force fall expression temperature into a predetermined value, it can carry out arbitrarily by changing the composition etc. of an adhesive layer.

  Moreover, the adhesive layer which consists of an above described composition shows etching liquid resistance. The reason for this is that the hydrophobicity of the entire pressure-sensitive adhesive layer is improved by containing (meth) acrylate having a relatively large carbon number, that is, (meth) acrylate having a linear alkyl group having 16 to 22 carbon atoms. It is assumed that this is due to

  In particular, according to the pressure-sensitive adhesive layer of the present embodiment, since the adhesive residue can be reduced when the protective tape is peeled off, it is possible to omit the cleaning process performed when the adhesive residue occurs, and the efficiency. Etching can be performed well.

  Examples of the (meth) acrylate having a linear alkyl group having 16 to 22 carbon atoms include 16 carbon atoms such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. The (meth) acrylate which has a linear alkyl group of -22 is mentioned, These may mix and use 1 type (s) or 2 or more types.

  Examples of the monomer copolymerizable with the (meth) acrylate and butyl acrylate include (meth) acrylate having a hydroxyalkyl group, a carboxyl group, and a glycidyl group. As the (meth) acrylate having the hydroxyalkyl group, , For example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. Examples of the (meth) acrylate having a carboxyl group include (meth) acrylic acid, Examples of the (meth) acrylate having a glycidyl group include glycidyl (meth) acrylate, and these may be used alone or in combination of two or more.

  As the polymerization ratio, for example, 10 to 70 parts by weight of (meth) acrylate having a linear alkyl group having 12 to 22 carbon atoms, 30 to 90 parts by weight of butyl acrylate, copolymerized with (meth) acrylate and butyl acrylate The possible monomer is preferably 1 to 20 parts by weight.

  The polymerization method is not particularly limited, and examples thereof include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method. 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 6 hours.

  The copolymer preferably has a weight average molecular weight of 250,000 to 1,000,000. If the weight average molecular weight of the copolymer is too small, adhesive residue may be generated when the protective tape is peeled off. On the other hand, if the weight average molecular weight is too large, the cohesive force becomes too high, and the adhesion to the member surface may be reduced. The weight average molecular weight is a value obtained by measuring the copolymer with GPC and converting the obtained measurement value into polystyrene. Other configurations are the same as those of the protective tape according to the first embodiment described above, and thus the description thereof is omitted.

<Etching method>
Next, an embodiment according to the etching processing method of the present invention will be described in detail with reference to FIG.

  As shown in FIG. 1A, first, the TFT 20 is formed on the surface 10a of the substrate 10 by a conventional method. The substrate 10 is preferably made of a material having excellent heat resistance. Thereby, even if the atmospheric temperature becomes high when forming the TFT 20, the TFT 20 can be stably formed without thermal deformation of the substrate 10.

  Examples of the material constituting the substrate 10 include (quartz) glass. As thickness of the board | substrate 10, about 0.5-1 mm is suitable. If the thickness of the substrate 10 is too large, the time required for etching, which will be described later, becomes long. On the other hand, if the thickness of the substrate 10 is too thin, the rigidity of the substrate 10 is lowered, and the handling property of the substrate 10 and the stability when forming the TFT 20 are lowered.

  Next, as shown in FIG. 1B, the above-described protective tape 1 for etching processing according to the present invention is attached to the TFT 20, and the TFT 20 is covered and protected with the protective tape 1. The protective tape 1 is configured such that the pressure-sensitive adhesive layer 3 is provided on one side of the base film 2 and the pressure-sensitive adhesive layer 3 exhibits a decrease in adhesive strength when heated at a temperature of less than 100 ° C. .

  Next, the substrate 10 is etched from the back surface 10b side opposite to the front surface 10a of the substrate 10 to form a thin film as shown in FIG. At this time, since the pressure-sensitive adhesive layer 3 of the protective tape 1 is in close contact with the surface of the TFT 20, the substrate 10 can be etched with the TFT 20 protected from the etching solution.

  The etching is performed by immersing the substrate 10 in an etching solution. The etching solution is not particularly limited as long as the substrate 10 can be etched, but a strongly acidic hydrofluoric acid aqueous solution or the like is preferable. The concentration of the etching solution is preferably about 10 to 30% by weight. The temperature of the etching solution is preferably about 20 to 60 ° C. When the concentration and temperature of the etching solution are increased, the time required for etching tends to be shortened. The substrate 10 may be thinned to a desired thickness depending on the application, but it is usually preferable to thin the substrate 10 until the thickness is about 0.01 to 0.3 mm.

  After the substrate 10 is thinned, the ambient temperature is heated to a temperature of less than 100 ° C. using a heating means such as gas. Thereby, the adhesive layer 3 of the protective tape 1 expresses a decrease in adhesive force. Therefore, as shown in FIG. 1D, when the protective tape 1 is moved in the direction of arrow A, peeling usually occurs at the interface between the pressure-sensitive adhesive layer 3 and the TFT 20, and the protective tape 1 can be removed from the TFT 20. At this time, since the adhesive strength of the pressure-sensitive adhesive layer 3 is sufficiently reduced for the reason described above, the load applied to the TFT 20 and the thinned substrate 10 at the time of peeling is small. The protective tape 1 can be used repeatedly many times by performing the same operation as described above.

  Next, another embodiment according to the etching method of the present invention will be described in detail with reference to FIG. In FIG. 2, the same components as those in FIG.

  As shown in FIG. 2A, first, the substrate 10 is thinned in the same manner as in the above-described embodiment except that the etch stopper layer 15 is interposed between the substrate 10 and the TFT 20.

  The etch stopper layer 15 functions as a stopper layer for the etching solution, and any desired one can be used as long as it functions as a stopper layer for the etching solution to be used. As a specific example, when an aqueous hydrofluoric acid solution is used as an etching solution, an etch stopper layer made of molybdenum or the like is suitable. The etch stopper layer made of molybdenum can be formed, for example, by sputtering. The thickness of the etch stopper layer 15 is suitably about 100 to 1000 nm.

  In the present embodiment, the thinned substrate 10 is further etched and removed as shown in FIG. Etching is automatically stopped at the etch stopper layer 15.

  Next, as shown in FIG. 2C, the TFT 20 is bonded to the surface of the transfer member 30 through an adhesive layer 31. The adhesive constituting the adhesive layer 31 is not particularly limited as long as the TFT 20 (etch stopper layer 15) and the transfer member 30 can be bonded and fixed. For example, a reactive curable adhesive, a thermosetting adhesive, Various well-known things, such as photocurable adhesives, such as an ultraviolet curable adhesive, are employable.

  The adhesive layer 31 can be formed by applying the adhesive on a predetermined portion of the transfer member 30 in advance or by applying the adhesive on the lower surface of the etch stopper layer 15. The thickness of the adhesive layer 31 is 1 to 100 μm, preferably about 10 to 50 μm. Adhesion is performed by curing the adhesive by a curing method corresponding to each adhesive exemplified above.

  As the transfer member 30, as long as the TFT 20 can be mounted, a desired one can be adopted. 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 atmospheric temperature is heated to a temperature lower than 100 ° C. and equal to or higher than the pressure lowering expression temperature to reduce the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer 3 of the protective tape 1, as shown in FIG. Then, the protective tape 1 is moved in the direction of arrow B, and the protective tape 1 is peeled off from the TFT 20.

  Although several embodiments according to the present invention have been described above, the present invention is not limited to the above embodiments, and various improvements and modifications can be made within the scope of the claims. is there. For example, in the embodiment according to the above-described etching method, the TFT has been 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 addition, the member to be protected of the etching processing protective tape according to the present invention is not limited to the thin film layer described above, and it is necessary to protect the member during the etching process and to be easily removed at the time of peeling. On the other hand, it can be used suitably.

  EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated in detail, this invention is not limited only to the following synthesis examples and Examples. In the following description, “part” means part by weight.

(Synthesis Example 1)
Add 52 parts of ethylhexyl acrylate, 40 parts of methyl acrylate, 8 parts of hydroxyethyl acrylate, and 0.2 parts of perbutyl ND (manufactured by NOF Corporation) as an initiator to 200 parts of toluene, respectively, at 60 ° C. These monomers were polymerized by stirring for 5 hours. The weight average molecular weight of the obtained copolymer was 460,000.

(Synthesis Example 2)
92 parts of ethylhexyl acrylate, 8 parts of hydroxyethyl acrylate, and 0.2 parts of perbutyl ND (manufactured by NOF Corporation) as an initiator were added to 200 parts of toluene, respectively, and stirred at 60 ° C. for 5 hours. These monomers were polymerized. The weight average molecular weight of the obtained copolymer was 470,000.

(Synthesis Example 3)
40 parts of behenyl acrylate, 35 parts of stearyl acrylate, 20 parts of methyl acrylate, 5 parts of acrylic acid, 6 parts of dodecyl mercaptan as a chain transfer agent, and 1.0 part of perhexyl PV (manufactured by NOF Corporation) as an initiator These monomers were polymerized at a ratio of parts by weight to 100 parts of toluene and stirred at 80 ° C. for 5 hours. The obtained copolymer had a weight average molecular weight of 8,000 and a melting point of 52 ° C.

(Synthesis Example 4)
95 parts of stearyl acrylate, 5 parts of acrylic acid, 5 parts of dodecyl mercaptan as a chain transfer agent, and 1.0 part of perhexyl PV (manufactured by NOF Corporation) as an initiator are added to 100 parts of toluene, respectively. These monomers were polymerized by stirring at 80 ° C. for 5 hours. The obtained copolymer had a weight average molecular weight of 8,500 and a melting point of 51 ° C.

(Synthesis Example 5)
50 parts of cetyl methacrylate, 40 parts of butyl acrylate, 10 parts of hydroxyethyl acrylate, and 0.2 parts of perbutyl ND (manufactured by NOF Corporation) as an initiator were added to 200 parts of toluene, respectively, at 60 ° C. These monomers were polymerized by stirring for 5 hours. The weight average molecular weight of the obtained copolymer was 370,000.

  Table 1 shows the copolymers of Synthesis Examples 1 to 5. In addition, the said weight average molecular weight is a value which measured the copolymer by GPC and converted the obtained measured value into polystyrene. The melting point is a value measured under a measurement condition of 10 ° C./min using a differential thermal scanning calorimeter (DSC).

[Examples 1 to 3 and Comparative Example 1]
<Preparation of protective tape for etching>
As Example 1, 5 parts of the copolymer solution of Synthesis Example 3 and 0.5 part of an isocyanate-based crosslinking agent are added to 100 parts of the copolymer solution of Synthesis Example 1 obtained above in terms of solid content. The pressure-sensitive adhesive solution thus obtained was applied to one side of a 100 μm thick polyethylene terephthalate film and dried to prepare a protective tape on which a pressure-sensitive adhesive layer having a thickness of 30 μm was formed. The adhesive force lowering expression temperature in this protective tape is 52 ° C.

  As Example 2, 5 parts of the copolymer solution of Synthesis Example 4 and 0.5 part of the isocyanate-based crosslinking agent were added to 100 parts of the copolymer solution of Synthesis Example 2 obtained above in terms of solid content. The pressure-sensitive adhesive solution thus obtained was applied to one side of a 100 μm thick polyethylene terephthalate film and dried to prepare a protective tape on which a pressure-sensitive adhesive layer having a thickness of 30 μm was formed. The adhesive force lowering expression temperature in this protective tape is 51 ° C.

  As Example 3, an adhesive solution obtained by adding 1.0 part of an isocyanate-based crosslinking agent in terms of solid content to 100 parts of the copolymer solution of Synthesis Example 5 obtained above was used as a polyethylene having a thickness of 100 μm. A protective tape on which a pressure-sensitive adhesive layer having a thickness of 30 μm was formed was prepared by applying to one side of a terephthalate film and drying. The temperature at which the adhesive force decreases in this protective tape is 45 to 55 ° C. (actual measured value).

  As Comparative Example 1, 2.4 parts of a cross-linking agent (“M-5A” manufactured by Soken Chemical Co., Ltd.) in terms of solid content is added to 100 parts of an acrylic pressure-sensitive adhesive (“SK-1340” manufactured by Soken Chemical Co., Ltd.). The pressure-sensitive adhesive solution thus obtained was applied to one side of a 100 μm thick polyethylene terephthalate film and dried to produce a protective tape on which a pressure-sensitive adhesive layer having a thickness of 30 μm was formed.

<Evaluation>
About each protection tape obtained above, 180 degree peeling strength and etching liquid resistance were evaluated. Each evaluation method is shown below, and the results are shown in Table 2.

(180 ° peel strength)
The 180 degree peel strength (based on JIS Z0237) with respect to the glass substrate in each atmospheric temperature of 23 degreeC and 70 degreeC was measured. Specifically, a glass substrate having a thickness of 250 mm × 140 mm and a thickness of 0.7 mm was prepared. Moreover, the test piece was cut out in the shape of 25 mm x 200 mm from each protective tape. Then, each test piece is attached to the glass substrate at an ambient temperature of 23 ° C., and the test piece is peeled off by 180 ° at a rate of 300 mm / min using a load cell, thereby obtaining a 180 ° peel strength at an ambient temperature of 23 ° C. Measured (n = 2).

  In the same manner, each test piece was adhered to the glass substrate at an ambient temperature of 23 ° C., and the ambient temperature was raised from 23 ° C. to 70 ° C., and then the test piece was 180 at this ambient temperature in the same manner as described above. The film was peeled and the 180 ° peel strength at an atmospheric temperature of 70 ° C. was measured (n = 2).

  Moreover, the destruction state in each atmospheric temperature was evaluated visually. In Table 2, “interfacial fracture” indicates that the adhesive layer and the glass substrate were peeled off, and “partial transfer” indicates that a part of the adhesive layer was transferred from the polyethylene terephthalate film to the glass substrate. Show. Furthermore, the evaluation result of the 180 ° peel strength at 23 ° C. obtained above is A, and the evaluation result of the 180 ° peel strength at 70 ° C. is B, respectively. ) Was calculated.

(Etch resistance)
First, an aqueous hydrofluoric acid solution having a concentration of 20% by weight was prepared as an etching solution. Next, this hydrofluoric acid aqueous solution was accommodated in a vat made of polypropylene.

  On the other hand, a test piece was cut out from each protective tape into a shape of 50 mm × 50 mm. Further, a glass substrate having a thickness of 250 mm × 140 mm and a thickness of 0.7 mm was prepared. Each test piece was bonded to one glass substrate at an ambient temperature of 23 ° C. This glass substrate was accommodated in the bat so that the back surface opposite to the surface on which the test piece was adhered was opposed to the bottom surface of the bat, and each test piece and the glass substrate were immersed in an aqueous hydrofluoric acid solution. Next, in order to prevent volatilization of hydrofluoric acid, the vat opening was closed with a polyethylene film, and the appearance of each test piece after 1 hour, 2 hours and 4 hours was visually observed and evaluated.

The atmospheric temperature under evaluation and the temperature of the hydrofluoric acid aqueous solution were both 22 to 23 ° C. Moreover, when visually observing, the glass substrate was taken out from the vat, and each test piece and the glass substrate were washed with 10 parts and dried. Evaluation criteria were set as follows.
(Circle): The test piece has not peeled from the glass substrate and the penetration degree of the etching liquid to the interface of a test piece and a glass substrate is 1 mm or less.
X: The test piece is peeled off from the glass substrate, or the degree of penetration of the etching solution into the interface between the test piece and the glass substrate is larger than 1 mm.

  As can be seen from Table 2, in Examples 1 to 3, when the 180 ° peel strength is heated from 23 ° C. to 70 ° C., the value is greatly reduced. From this result, it can be said that Examples 1 to 3 exhibit a decrease in adhesive strength when heated at a temperature of less than 100 ° C. In Examples 1 to 3, the evaluation result of the etchant resistance is also good, so that it can be said that the member to be protected can be protected during the etching process.

  On the other hand, in Comparative Example 1, although the adhesive strength is reduced by heating from 23 ° C. to 70 ° C., the reduction rate is significantly smaller than those of Examples 1-3. Moreover, in the comparative example 1, in the evaluation of etching liquid resistance, the result inferior to the evaluation after 4 hours was shown. From these results, it can be seen that in Comparative Example 1, the member to be protected cannot be protected during the etching process and cannot be easily removed at the time of peeling.

DESCRIPTION OF SYMBOLS 1 Etching protective tape 2 Base film 3 Adhesive layer 10 Substrate 10a Front surface 10b Back surface 15 Etch stopper layer 20 TFT
30 Transfer member 31 Adhesive layer

Claims (7)

  A protective tape for etching processing, wherein an adhesive layer is provided on one side of a substrate film, and the adhesive layer exhibits a decrease in adhesive strength when heated at a temperature of less than 100 ° C.   The protective tape for etching processing according to claim 1, wherein the pressure-sensitive adhesive layer contains a pressure-sensitive adhesive and a side chain crystalline polymer, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the side chain crystalline polymer.   The pressure-sensitive adhesive layer is a copolymer of (meth) acrylate having a linear alkyl group having 16 to 22 carbon atoms, butyl acrylate, and a monomer copolymerizable with the (meth) acrylate and butyl acrylate. The protective tape for etching processing according to claim 1, which is contained. Forming a thin film layer on the surface of the substrate;
Attaching the protective tape according to claim 1 to the thin film layer, and covering and protecting the thin film layer with the protective tape;
Etching the substrate from the back side opposite to the surface of the substrate to form a thin film;
Heating the pressure-sensitive adhesive layer of the protective tape at a temperature of less than 100 ° C. to reduce the adhesive force, and peeling the protective tape from the thin film layer;
Etching method characterized by including.   The etching method according to claim 4, wherein the etching is performed by immersing the substrate in an etching solution.   6. The etching processing method according to claim 4, wherein the thinned substrate is further removed by etching, the thin film layer is bonded to the surface of the transfer member via an adhesive layer, and then the protective tape is peeled off from the thin film layer. .   The etching method according to claim 4, wherein an etch stopper layer is interposed between the substrate and the thin film layer.

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