JP2018158404A - Method for peeling substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for peeling a substrate which suppresses damage and cracking of a wafer generated in a step of peeling a support substrate while improving work efficiency.SOLUTION: A method for peeling a substrate includes: a first sticking step of sticking a first surface of a first substrate 4 and a second substrate 2 through an adhesive member 5; a substrate formation step of forming a plurality of third substrates 1 connected to the second substrate; a processing step of processing the first substrate so that at least one surface of the first substrate is divided by a groove; and a peeling step of peeling the first substrate formed with the groove and the adhesive member from the second substrate formed with the plurality of third substrates while bending the first substrate and the adhesive member so that a second surface opposite to the first surface becomes inside.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a substrate peeling method used when a plurality of stacked elements are manufactured by stacking wafers using a MEMS (MICRO ELECTRO MECHANICAL SYSTEMS) technique.

  With the recent miniaturization of electronic devices, technical development of electronic devices using MEMS technology has been actively conducted. Of these, many have a laminated structure using bonding technology and grinding / polishing technology, and have been developed for use in technology for ejecting liquid from a pressure chamber whose volume is expanded and contracted by a piezoelectric element in a liquid ejection head that ejects liquid. It has been. Many of such liquid ejection heads have a structure in which a piezoelectric element portion, a wafer substrate having a pressure chamber partition, and an ejection port wafer substrate having ejection ports are bonded and stacked. In such a method for manufacturing a laminated element, a process of grinding and polishing a wafer to make it thin is frequently used. To compensate for the difficulty in handling a wafer after thin plate processing, the wafer is attached to a support substrate. Manufacturing is done.

  Patent Document 1 describes that a wafer is attached to a support substrate, processed and bonded, and the wafer is peeled off from the support substrate in a later process. Patent Document 2 describes that processing is performed in a state where the wafer and the support substrate are bonded, the wafer is cut and cut by dicing, and the support substrate is removed after being cut into chips.

JP 2008-94018 A JP 2009-238781 A

  In Patent Document 1, it is described that when a wafer is peeled from a support substrate, UV is irradiated to reduce the adhesive force between the wafer and the support substrate, and then the wafer is peeled off. However, since the wafer and the support substrate are bonded and closely adhered without bubbles, a force generated when the support substrate having high rigidity is peeled off from the wafer may be applied to the wafer and the wafer may be broken.

  Further, as in Patent Document 2, when the support substrate is removed after being formed into chips, the work is difficult because the work is performed while holding the edge portions of the chips that have been fragmented. There is a problem that man-hours increase because the separation process is performed individually.

  Accordingly, an object of the present invention is to provide a substrate peeling method that suppresses damage and cracking of a wafer that occurs in a step of peeling a support substrate while improving work efficiency.

  Therefore, the substrate peeling method of the present invention includes a first bonding step in which the first surface of the first substrate and the second substrate are bonded through an adhesive member, and the second substrate is connected to the first substrate. Forming a plurality of third substrates, a processing step of processing the first substrate such that at least one surface of the first substrate is divided by the grooves, and forming the grooves The second substrate on which a plurality of the third substrates are formed while bending the first substrate and the adhesive member so that the second surface opposite to the first surface is inside. And a peeling step for peeling from the substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the peeling force which generate | occur | produces at the process of peeling a support substrate can be reduced, improving the working efficiency, and the peeling method of the board | substrate which suppresses the breakage | damage of a thin wafer and a crack can be implement | achieved.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a main part of a liquid discharge head. It is sectional drawing which shows the process process of a flow-path board | substrate in order. It is sectional drawing which shows the manufacturing process of a discharge outlet board | substrate. It is sectional drawing which shows a joining process. It is the top view and sectional drawing which show support substrate processing. It is a figure which shows a support substrate peeling process. It is a top view which shows a support substrate. It is sectional drawing which shows a support substrate process and a support substrate peeling process. It is sectional drawing which shows a support substrate process and a support substrate peeling process. It is sectional drawing which shows a support substrate process and a support substrate peeling process.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

(Channel substrate)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of a main part of the liquid discharge head according to the present embodiment. A liquid discharge portion in the liquid discharge head is formed by bonding the flow path substrate 1 and the discharge port substrate 2, and a PZT piezoelectric body 10 of a piezoelectric actuator and a lower electrode 11 are formed on the surface of the flow path substrate 1. And an upper electrode 12. A part of the liquid chamber 13 is formed on the back surface of the flow path substrate 1 on which the discharge port substrate 2 is bonded. The liquid chamber 13 is formed by bonding to the discharge port substrate 2. . The discharge port substrate 2 is provided with a discharge port 14 at a position corresponding to the liquid chamber 13. When a voltage is applied to the lower electrode 11 and the upper electrode 12 of the flow path substrate configured as described above, the PZT piezoelectric body 10 is deformed and the volume of the liquid chamber 13 is changed, and the liquid chamber 13 is filled. The discharged liquid can be discharged from the discharge port 14.

  2A to 2E are cross-sectional views sequentially showing processing steps of the flow path substrate 1 of the present embodiment. In forming the flow path substrate 1, first, a 6-inch Si wafer 30 having a thickness of 625 μm and a diameter of 150 mm as shown in FIG. 2A is prepared. Thereafter, as shown in FIG. 2B, the diaphragm 15, the lower electrode 11, the PZT piezoelectric body 10, and the upper electrode 12 are sequentially formed on one surface of the Si wafer 30. On the vibration plate 15, a 0.8 μm SiN film is formed on the first surface of the Si wafer 30 using LP-CVD (Low Pressure Chemical Vapor Deposition Method). Subsequently, the lower electrode 11 for applying a voltage to the PZT piezoelectric body 10 is formed on the vibration plate 15 made of a SiN thin film. The lower electrode 11 is formed by depositing Ti having a thickness of 0.01 μm and Pt having a thickness of 0.15 μm in this order.

  Further, a PZT having a thickness of 2.0 μm is formed as a PZT piezoelectric body 10 by a sol-gel method, and baked at 700 ° C. for 20 minutes for crystallization. Further, an upper electrode 12 for applying a voltage to the PZT piezoelectric body 10 is formed. The upper electrode 12 was formed by depositing Ti having a thickness of 0.01 μm and Au having a thickness of 0.15 μm in this order. Thereafter, as shown in FIG. 2C, patterning is performed by etching in the order of the upper electrode 12, the PZT piezoelectric body 10, and the lower electrode 11. As a result, a piezoelectric actuator serving as a pressure generating unit including the lower electrode 11, the PZT piezoelectric body 10, and the upper electrode 12 is formed on the vibration plate 15. Next, as shown in FIG. 2D, the opposite surface of the piezoelectric actuator portion in the Si wafer 30 is thinned to a thickness of 100 μm by grinding and polishing. As this processing method, a back grinder or a CMP method can be applied. After that, as shown in FIG. 2 (e), the silicon wafer 30 is deeply etched with a recess that becomes a part of the liquid chamber 13 and a through hole (not shown) for supplying the liquid on the ground surface of the Si wafer 30. -Formed by RIE method.

(Discharge port substrate)
FIGS. 3A to 3H are cross-sectional views showing the processing steps of the discharge port substrate 2 in the present embodiment. In forming the discharge port substrate 2, an SOI (Silicon) having a first silicon oxide film 23 between a first silicon layer 21 and a second silicon layer 22 as shown in FIG. on Insulator) substrate 3 is prepared. In the present embodiment, the thickness of the first silicon oxide film 23 is 0.5 μm, the thickness of the first silicon layer 21 is 10 μm, the thickness of the second silicon layer 22 is 625 μm, and the diameter is 6 mm. Inch SOI substrate 3 is used. Thereafter, as shown in FIG. 3B, the first silicon layer 21 is finally used as the discharge port substrate 2, and the discharge port 14 is processed so that the surface side of the first silicon layer 21 becomes the discharge surface side. Do. Here, the diameter of the discharge port 14 is Φ20 μm, a resist pattern is formed on the surface of the first silicon layer 21, and hole processing is performed on the first silicon layer 21 by silicon deep processing deep-RIE method. Subsequently, the first silicon oxide film 23 is dry-etched to remove the resist.

  Thereafter, as shown in FIG. 3C, first ink-resistant protective films 24 and 25 are formed on the discharge port processed surface. In this embodiment, the silicon oxide layer is formed with a thickness of 0.2 μm by a thermal oxidation process. As a result, a silicon oxide layer is also formed on the bottom and side walls of the discharge port. Next, as shown in FIG. 3D, a water repellent film 26 is formed on the ink-resistant protective film. The water repellent film 26 is formed of a compound containing fluorine atoms by a film forming method such as spin coater, dipping, or vacuum deposition. In the present embodiment, the fluorine-containing film is formed by a vacuum vapor deposition method. At this time, the compound also enters the inside of the discharge port to form the water repellent film 26.

  Next, as shown in FIG. 3E, glass as the support substrate 4 is attached to the surface on which the water repellent film 26 is formed. The glass of the support substrate 4 had a thickness of 525 μm, and a double-sided tape 5 having an adhesive layer (not shown) on both sides of a polyester film base sheet having a thickness of 100 μm was used as an adhesive member, and was bonded together in a vacuum. In this embodiment, Riba Alpha double-sided tape manufactured by Nitto Denko Corporation was used for the double-sided tape 5. The total thickness of the double-sided tape including the double-sided adhesive material is 158 μm.

  Next, as shown in FIG. 3F, the second silicon layer 22 which is the handle layer of the SOI substrate 3 is removed. As the removing method, the support substrate 4 side was fixed, the second silicon layer 22 was shaved by about 500 μm with a grinder, and then the remaining silicon layer was removed by dry etching using the first silicon layer 21 as a stop layer. After this step, the discharge port substrate 2 is in a thin state with a thickness of about 10 μm. However, since it is bonded to the support substrate 4, there is no problem in handling properties, and it can be processed with a low risk of breakage. In the state processed so far, the first ink-resistant protective film formed in FIG. 3C remains on the bottom of the discharge port, and the discharge port 14 is not penetrating. Thereafter, as shown in FIG. 3G, the ink-resistant protective film and the water-repellent film at the bottom of the ejection port are removed, and the ejection port is penetrated. For removing the ink-resistant protective film, anisotropic dry etching was used.

  Next, as shown in FIG. 3 (h), the water-repellent film that has entered the discharge port is removed. In the removal method, O2 plasma treatment is performed from the surface having the through opening, and the water-repellent film on the side wall of the discharge port is decomposed and removed.

(Joining)
FIG. 4 is a cross-sectional view showing a bonding process in the present embodiment. In a state where the discharge port substrate 2 is bonded to the support substrate 4, a piezoelectric actuator and a part of the liquid chamber 13 and a through hole for supplying liquid are formed on the surface of the discharge port substrate 2 where the discharge port is open. The flow path substrates 1 are joined. As shown in FIG. 4, an adhesive (not shown) is applied to the convex portion on the liquid chamber side of the flow path substrate 1, aligned with the discharge port substrate 2, and heated while applying a load. Were cured and joined. As a result, the discharge port substrate 2 and the flow path substrate 1 in a state in which the support substrate 4 is bonded are joined to each other. Thus, the multilayer substrate becomes a multilayer substrate in which a plurality of chips to be divided in a subsequent process are formed (substrate formation) in a connected state.

(Support substrate processing)
FIG. 5 is a plan view and a cross-sectional view showing support substrate processing in the present embodiment. When the laminated substrate is formed, next, the support substrate 4 is cut using a blade dicer. The surface of the laminated substrate on the flow path substrate 1 side and the dicing tape 27 are joined, and the support substrate 4 side is cut into a strip shape with a blade dicer. At that time, the blade has a width of 100 μm, and the lower end of the blade is adjusted to a height that does not divide the polyester film substrate of the double-sided tape 5 disposed under the support substrate 4 as shown in FIG. The support substrate 4 is cut into strips at intervals of 1 mm. That is, in this state, the support substrate 4 is divided into strips, but the polyester film base material of the double-sided tape 5 is not divided and is connected to the entire laminated substrate.

(Support substrate peeling)
FIGS. 6A and 6B are views showing a support substrate peeling step in the present embodiment. After the cutting process, the support substrate 4 and the double-sided tape 5 as an adhesive member are peeled from the discharge port substrate 2. The laminated substrate is fixed to the dicing tape 27 used in the previous cutting process, and the double-sided tape 5 and the discharge port substrate 2 at the end of the laminated substrate are fixed as shown in FIGS. 6 (a) and 6 (b). And mechanically peel off. At that time, the adhesive surface of the double-sided tape 5 is peeled from the surface of the discharge port substrate 2 by pulling the double-sided tape 5 while bending the double-sided tape 5 inward in a direction substantially orthogonal to the direction in which the support substrate 4 is divided into strips.

  By dividing the support substrate 4 into strips, the double-sided tape 5 can be bent, and peeling as shown in FIG. 6B becomes possible. Thus, by peeling from the discharge port substrate 2 while bending the double-sided tape 5, it is a force applied from the double-sided tape 5 to the discharge port substrate 2 at the time of peeling, and a tensile force that is considered to greatly contribute to cracking of the discharge port substrate 2. Can be reduced. Hereinafter, the reason why the tensile force applied to the discharge port substrate 2 can be reduced will be described.

  First, the case where the support substrate 4 is rigid and peels from the discharge port substrate without bending the double-sided tape will be described. In this case, a tensile force is continuously applied from the double-sided tape to the surface of the discharge port substrate from the start of peeling until the completion of peeling. This tensile force is a force that acts almost perpendicularly to the surface of the discharge port substrate. If the tensile force is evenly applied to the entire surface of the discharge port substrate, the discharge port substrate will not break. However, when the balance of the tensile force on the surface of the discharge port substrate is deteriorated and the tensile force is continuously applied in a state where the discharge port substrate is bent, the discharge port substrate is easily cracked. And, it is difficult to complete the peeling while keeping the tensile force applied to the entire surface of the discharge port substrate uniform at the time of peeling, and if the uneven state of the tensile force continuously occurs until the peeling is completed, the discharging port The substrate will be cracked.

  On the other hand, when peeling from the discharge port substrate 2 while bending the double-sided tape 5, an instantaneous tensile force and shearing force are applied to a part of the discharge port substrate 2 from the double-sided tape 5. The tensile force is a force acting almost perpendicularly to the surface of the discharge port substrate 2, and the shearing force is a force acting almost parallel to the surface of the discharge port substrate 2. In general, when a shearing force is applied, the entire bonding surface is subjected to a uniform stress, and cracking is less likely to occur even when acting on a thin plate as compared with a tensile force.

  At the time of peeling from the discharge port substrate 2, there is a portion where an instantaneous peeling force (tensile force and shearing force) acts from one end portion of the discharge port substrate 2 to the other end portion where the double-sided tape 5 starts to be peeled off. It peels while moving. Since the peeling force acting on the discharge port substrate 2 is divided into a tensile force and a shearing force, the tensile force is weaker than when peeling from the discharge port substrate 2 without bending the double-sided tape 5. Furthermore, since the part where the force acts is peeled off while moving, the tensile force does not continuously act on any part of the discharge port substrate 2. Therefore, compared with the case where the double-sided tape 5 is peeled from the discharge port substrate 2 without bending, the occurrence of cracks in the discharge port substrate 2 at the time of peeling can be suppressed.

  Moreover, since the polyester film base material of the double-sided tape 5 is not divided | segmented and is connected with the whole laminated substrate, it can peel continuously from the several chip | tip formed in the laminated substrate by one peeling.

(Chip division)
Thereafter, the liquid discharge head is completed by dividing the chip into individual chips using the same blade dicer used when forming the grooves in the support substrate 4.

  In this embodiment, a groove having a rectangular cross section is formed on the support substrate, but the present invention is not limited to this, and a wedge-shaped groove having a triangular cross section may be used.

  In this manner, a groove is formed in the support substrate 4, and the support substrate 4 and the double-sided tape 5 are peeled from the discharge port substrate 2 while being bent. Thereby, the tensile stress applied to the discharge port substrate 2 at the time of peeling can be reduced. As a result, the support substrate 4 was able to be peeled without breakage of the thin and fragile discharge port substrate 2 and peeling of the adhesive portion with the flow path substrate 1. Moreover, since the polyester film base material of the double-sided tape 5 is not divided, the entire laminate can be peeled off by a single peeling work, and the work efficiency is improved.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, only the characteristic configuration will be described below.

  FIG. 7 is a plan view showing the support substrate 4 in the present embodiment. In the present embodiment, the support substrate 4 is divided into a lattice shape as shown in FIG. The polyester film base material of the double-sided tape 5 is not divided like the first embodiment, and is in a state connected to the entire substrate.

  In this manner, the support substrate 4 is divided into a lattice shape, and the support substrate 4 and the double-sided tape 5 are bent and peeled from the discharge port substrate 2. Thereby, the tensile stress applied to the discharge port substrate 2 at the time of peeling can be reduced. As a result, the support substrate 4 was able to be peeled without breakage of the thin and fragile discharge port substrate 2 and peeling of the adhesive portion with the flow path substrate 1. Moreover, since the polyester film base material of the double-sided tape 5 is not divided, the entire laminate can be peeled off by a single peeling work, and the work efficiency is improved.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, only the characteristic configuration will be described below.

  FIGS. 8A and 8B are cross-sectional views showing the support substrate processing and the support substrate peeling step in this embodiment. In this embodiment, the support substrate 4 is not divided, and groove processing (groove formation) is performed as shown in FIG. The used blade was 100 μm in width, and the lower end of the blade was adjusted so that the groove depth was 425 μm with respect to the thickness 525 μm of the support substrate 4, and processed into a strip shape with a pitch of 1 mm. That is, each strip is connected to the bottom 100 μm of the support substrate 4 by the polyester film substrate of the double-sided tape 5.

  In this way, a groove is formed in the support substrate 4, and the support substrate 4 and the double-sided tape 5 are bent from the discharge port substrate 2 while being bent. As a result, the rigidity is lower than that of the support substrate in which no groove is formed, and it is possible to bend following the double-sided tape 5, and the tensile stress applied to the discharge port substrate 2 at the time of peeling can be reduced. As a result, the support substrate 4 was able to be peeled without breakage of the thin and fragile discharge port substrate 2 and peeling of the adhesive portion with the flow path substrate 1. Moreover, since the polyester film base material of the double-sided tape 5 is not divided, the entire laminate can be peeled off by a single peeling work, and the work efficiency is improved.

(Fourth embodiment)
The fourth embodiment of the present invention will be described below with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, only the characteristic configuration will be described below.

  FIGS. 9A to 9C are cross-sectional views showing the support substrate processing and the support substrate peeling process in this embodiment. The support substrate 4 in the present embodiment is formed by grooving similarly to the third embodiment, but the timing of grooving is different from that in the third embodiment. In the third embodiment, the groove processing is performed after the support substrate 4 is attached to the discharge port substrate 2 on which the water-repellent film 26 is formed as in the first embodiment. However, in the present embodiment, the support substrate 4 is used. Then, the support substrate 4 is attached to the discharge port substrate 2.

  As shown in FIG. 9A, a single support substrate 4 was grooved using a blade dicer at a width of 100 μm, a depth of 425 μm, and a pitch of 1 mm. Thereafter, as shown in FIG. 9B, the surface of the support substrate 4 where the groove processing is not performed and the surface of the discharge port substrate 2 on which the water repellent film is formed are passed through the double-sided tape 5 as in the first embodiment. And pasted together. Then, the handle layer was removed, the ink-resistant protective film and the water repellent film on the bottom of the discharge port were removed, and the discharge port substrate 2 and the flow path substrate 1 were joined as shown in FIG.

  In this manner, a groove is formed in the support substrate 4 before being attached to the discharge port substrate 2, and thereafter, the groove is attached to the discharge port substrate 2. As a result, the rigidity is lower than that of the support substrate without a groove, and it is possible to bend following the double-sided tape 5 and to reduce the tensile stress applied to the discharge port substrate 2 at the time of peeling. As a result, the support substrate 4 was able to be peeled without breakage of the thin and fragile discharge port substrate 2 and peeling of the adhesive portion with the flow path substrate 1. Moreover, since the polyester film base material of the double-sided tape 5 is not divided, the entire laminate can be peeled off by a single peeling work, and the work efficiency is improved.

(Fifth embodiment)
Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of the present embodiment is the same as that of the first embodiment, only the characteristic configuration will be described below.

  FIGS. 10A to 10C are cross-sectional views showing the support substrate processing and the support substrate peeling step in this embodiment. In the present embodiment, the fourth embodiment is the same as the fourth embodiment until the support substrate 4 is grooved (FIG. 10A). After the groove processing is performed on the support substrate 4, as shown in FIG. 10B, the surface of the support substrate 4 on which the groove processing is performed and the water-repellent film forming surface of the discharge port substrate 2 are the same as those in the first embodiment. Similarly, it bonds together through the double-sided tape 5. Then, the handle layer was removed, the ink-resistant protective film and the water repellent film on the bottom of the discharge port were removed, and the discharge port substrate 2 and the flow path substrate 1 were joined as shown in FIG. Thereafter, the support substrate 4 is thinly processed from the surface opposite to the bonded surface of the support substrate 4 (the surface on which the grooves are not formed) to expose the grooves. For this processing, for example, grinding, polishing, etching or the like is used. This state is almost the same as the state shown in FIG. Thereafter, the same processing as in the first embodiment was performed.

  In this manner, grooves are formed in the support substrate 4 before being attached to the discharge port substrate 2, the surface of the support substrate 4 on which the grooves are formed is attached to the discharge port substrate 2, and then the support substrate 4 is processed. Make the groove appear. Thereby, the tensile stress applied to the discharge port substrate 2 at the time of peeling can be reduced. As a result, the support substrate 4 was able to be peeled without breakage of the thin and fragile discharge port substrate 2 and peeling of the adhesive portion with the flow path substrate 1. Moreover, since the polyester film base material of the double-sided tape 5 is not divided, the entire laminate can be peeled off by a single peeling work, and the work efficiency is improved.

DESCRIPTION OF SYMBOLS 1 Flow path board | substrate 2 Discharge port board | substrate 3 SOI board | substrate 4 Support substrate 5 Double-stick tape

Claims (13)

A first bonding step of bonding the first surface of the first substrate and the second substrate via an adhesive member;
A substrate forming step of forming a plurality of third substrates connected to the second substrate;
A processing step of processing the first substrate such that at least one surface of the first substrate is divided by a groove;
The plurality of third substrates are formed while bending the first substrate having the grooves and the adhesive member so that the second surface opposite to the first surface is inside. And a peeling step for peeling from the second substrate.   The substrate peeling method according to claim 1, wherein the first substrate is divided into a plurality of parts after the processing step.   The substrate peeling method according to claim 2, wherein, in the processing step, the first substrate is divided into a lattice shape.   The substrate peeling method according to claim 1, wherein the first substrate is integrated after the processing step.   5. The substrate peeling method according to claim 4, wherein the processing step is performed after the first bonding step.   5. The substrate peeling method according to claim 4, wherein the processing step is performed before the first bonding step.   The substrate peeling method according to claim 2, wherein the processing step is performed after the first bonding step.   The substrate peeling method according to claim 7, wherein a groove forming step of forming a groove in the first substrate is performed before the first bonding step.   9. The substrate forming process according to claim 1, wherein, after the first bonding process, the substrate forming process includes a shaving process of shaving the second substrate to reduce the thickness. 10. 2. The method for peeling off the substrate according to 1.   The said board | substrate formation process includes the 2nd bonding process of bonding the 4th board | substrate provided with the piezoelectric actuator to the said 2nd board | substrate after the said cutting process. Substrate peeling method.   The substrate peeling method according to claim 10, wherein the peeling step is performed after the second bonding step.   The method for peeling a substrate according to any one of claims 1 to 11, wherein the adhesive member is a double-sided tape in which an adhesive layer is formed on both surfaces of a base sheet. A first bonding step of bonding the first surface of the first substrate and the second substrate via an adhesive member;
A processing step of processing the first substrate such that at least one surface of the first substrate is divided by a groove;
A plurality of connected third substrates are formed while bending the first substrate having the groove and the adhesive member so that the second surface opposite to the first surface is inward. And a peeling step for peeling from the second substrate.

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