Separation method

Abstract

The present invention provides a separation method capable of easily separating a bonded body of a substrate and a conveyance substrate for conveying said substrate. The separation method includes cooling a bonded body 5 of a substrate 1 and a conveyance substrate 3, and applying ultrasonic vibration U from the surface of the substrate 1 and / or the surface of the conveyance substrate 3 in the thickness direction of the substrate 1 and conveyance substrate 3 toward a bonding layer 7. Bonding in the formation of the bonded body may include performing a surface treatment by irradiating the bonding surface of the substrate and / or the bonding surface of the conveyance substrate with first ultraviolet rays including a wavelength of 200 nm or less.

Description

Peeling method

[0001] The present invention relates to a peeling method.

[0002] Organic electroluminescence (organic EL) elements (organic EL elements) that utilize organic electroluminescence (organic EL) are formed with a planar light-emitting layer made of organic compounds formed on a transparent substrate, and are increasingly being put to practical use in thin displays and the like. Compared to liquid crystal displays, organic EL displays that utilize organic EL elements have a wider viewing angle, lower power consumption, and are flexible enough to be bent, making them highly commercially useful. Furthermore, process development is also underway in the fields of three-dimensional IC packaging and MEMS as a manufacturing method that utilizes thin substrates (1 μm-thick Si wafers).

[0003] Silicon wafers are typically made approximately 0.5-1 mm thick for ease of handling during the manufacturing process. The external dimensions of typical silicon wafers are standardized by industry organizations such as SEMI, with thicknesses of 0.625 mm for a 150 mm (6 inch) diameter, 0.725 mm for a 200 mm (8 inch) diameter, and 0.775 mm for a 300 mm (12 inch) diameter. However, the thin substrates being used are typically between 0.5 μm and 0.2 mm thick, making them difficult to transport in typical manufacturing processes. Furthermore, substrate sizes range from as small as chip size (4 inches square) to as large as over 1 m square, making it difficult to transport thin substrates using robots or other devices during device manufacturing.

[0004] One possible solution is to use a glass substrate, film, or silicon wafer with a thickness of 0.1 mm to 1.1 mm as a transport substrate, and then attach the above-mentioned thin substrate to the surface of the substrate for transport. This method has the advantage that the substrate thickness can be transported using existing equipment. However, the transport substrate must be peeled off after the device is completed.

[0005] There are three types of thin substrates. One is thin glass, and the other is heat-resistant film, typically polyimide. This type of film also includes films created by applying varnish directly to a carrier substrate, baking it, and then forming it into a film. The third type is silicon wafers. In some cases, silicon wafers are protected with adhesive tape. In this case, the substrate is a laminate of silicon wafer and film.

[0006] Currently proposed transport methods use glass or silicon wafers as transport carriers. In the case of thin glass, the method involves keeping the carrier glass surface clean and directly bonding the two materials, due to the characteristics of the two materials being glass. In the case of heat-resistant film, a film that undergoes destruction when irradiated with a laser is formed between the carrier glass and the film, and after bonding, the film is peeled off by laser irradiation. In addition, when the thin substrate is a silicon wafer, non-contact transport methods and special chucking methods have been proposed, but there are limits to the thickness that can be transported. In reality, thicknesses of around 100 μm are feasible, and there are no transport methods for thicknesses such as 1 μm.

[0007] In this case, a carrier substrate can be used. However, there is no good method for peeling. In the case of silicon wafers, polishing may be used to thin them. In this case, adhesive tape is applied to the silicon wafer to prevent cracking or chipping after polishing. In this case, it has also been suggested to use glass as a carrier.

[0008] For example, in the case of displays, thin substrates are heated to temperatures of around 300°C to 500°C in processes such as the TFT formation process. Also, in semiconductor processes for silicon wafers, there is an annealing step in which the substrate is heated to temperatures of 800°C or higher. Because the substrates undergo heated steps, there is no effective method for peeling them off from the transport substrate to which they are attached.

[0009] Meanwhile, as devices become thinner, there has been a growing demand for temporary bonding and peeling technologies. Current temporary bonding and peeling methods involve applying a UV-sensitive tape, and then peeling it off with UV light after all other processes have been completed. Another method, called laser lift-off, involves focusing a laser on the bonding interface to remove the material (used to peel off the carrier glass and pi varnish of flexible organic light-emitting diodes). However, these technologies require the use of materials that are UV-transparent. This technology is an additional application when using a silicon wafer as the carrier. This technology is a solution when UV light is not effective or when organic materials cannot be used as a release film. A major application is the bonding and peeling of silicon wafers and interposers (glass or silicon).

[0010] As device substrates become increasingly thinner, the process of attaching a device substrate to a transport substrate and then thinning it is becoming more common. What is currently required is a process that has adhesive strength that will not peel off even during the thinning process (cutting and polishing), and that also allows for peeling even after the heating process (necessary for device fabrication) after thinning. Device substrates, especially after polishing, are extremely thin (3-10 μm), making mechanical peeling difficult.

[0011] Furthermore, in response to industrial changes centered on advances in AI and the spread of electric vehicles, various devices are being forced to be smaller and thinner. The semiconductor industry is experiencing the greatest demand. Increased electrical processing capacity has necessitated stacking SI wafers. This requires thinner SI wafers. By grinding and polishing SI wafers from approximately 500 to 800 μm to a maximum of 1 μm, a dramatic reduction in the volume of stacked SI wafers is expected. What is needed is a technology that allows for temporary bonding to a carrier wafer (SI wafer, glass wafer) without peeling during subsequent grinding and polishing, and that allows for easy debonding after the device is completed. This temporary bonding method is thought to be applicable not only to SI wafers, but also to glass and other materials. Therefore, further research is needed on temporary bonding methods that assume debonding.

[0012] For example, Patent Document 1 discloses a method of easily separating a thin substrate and a transportation substrate by bonding them together via an inorganic material layer.

[0013] International Publication No. 2016 / 010106

[0014] However, there is a need for a further method for easily separating the thin substrate from the carrier substrate.

[0015] The present invention has been made in view of the above, and an object of the present invention is to provide a peeling method that can easily peel off a bonded assembly of a substrate and a transportation substrate for transporting the substrate.

[0016] In order to solve the above-mentioned problems and achieve the object, the method of the present invention for peeling off a bonded structure of a substrate and a transport substrate includes cooling the bonded structure of the substrate and the transport substrate, and applying ultrasonic vibrations from a surface of either the substrate or the transport substrate, or from a surface of both the substrate and the transport substrate, in the thickness direction of the substrate and the transport substrate and toward the bonding layer.

[0017] In one aspect of the present invention, the method includes placing water on a bonding layer between the substrate and the transfer substrate before applying the ultrasonic vibration.

[0018] In one aspect of the present invention, the method includes, before the cooling, placing water on a bonding layer between the substrate and the transfer substrate.

[0019] In one aspect of the present invention, applying the ultrasonic vibrations includes applying the ultrasonic vibrations through a liquid. In one aspect of the present invention, the liquid is water, an alcohol, or a mixture thereof. In one aspect of the present invention, the liquid is heated.

[0020] In one aspect of the present invention, applying the ultrasonic vibrations includes bringing a hollow metal case into contact with the transfer board, filling the metal case with a liquid, and applying the ultrasonic vibrations from the inside of the metal case to the transfer board.

[0021] In one aspect of the present invention, applying the ultrasonic vibrations includes bringing a metal case having an opening on one side into contact with the transfer board with the opening facing the transfer board, filling the metal case with a liquid, and applying the ultrasonic vibrations from the inside of the metal case to the transfer board.

[0022] In one aspect of the present invention, applying the ultrasonic vibrations includes: placing a metal case having an opening on one side so that the opening faces the substrate for transportation, fixing the open end with a bonding material, filling the metal case with a liquid, applying ultrasonic vibrations from the inside of the metal case to the substrate for transportation, discharging the liquid, and separating and transporting the metal case together with the substrate for transportation.

[0023] In one aspect of the present invention, the substrate is any one or a combination of glass, silicon, a compound semiconductor, and a polymer film, either a simple substance or having a circuit.

[0024] In one aspect of the present invention, the bonded body is bonded via an inorganic film.

[0025] In one aspect of the present invention, the bonded body is bonded by performing a surface treatment of applying energy to a bonding surface of one or both of the substrate and the transportation substrate.

[0026] In one aspect of the present invention, the bonded body is bonded by performing a surface treatment in which the bonding surfaces of one or both of the substrate and the transport substrate are irradiated with first ultraviolet light having a wavelength of 200 nm or less.

[0027] In one aspect of the present invention, the bonding of the bonded body is performed by forming a thin film of Si on the bonding surface by sputtering to a thickness of 0.1 nm to 30 nm, and then irradiating the second ultraviolet light.

[0028] In one aspect of the present invention, the bonding of the bonded body is performed by forming a thin film of Si on the bonding surface by sputtering to a thickness of 0.1 nm to 30 nm, activating the surface of the thin film with an ion beam, and then irradiating it with a second ultraviolet light.

[0029] In one aspect of the present invention, the bonding of the bonded body is performed by selectively bonding only protruding portions of the substrate having a pattern formed thereon.

[0030] In one aspect of the present invention, the liquid is pure water.

[0031] In one aspect of the present invention, oxygen is mixed into the pure water.

[0032] In one aspect of the present invention, nitrogen is mixed into the pure water.

[0033] In one aspect of the present invention, ozone is mixed into the pure water.

[0034] In order to solve the above-mentioned problems and achieve the object, a method for separating a bonded structure of a substrate and a transportation substrate according to the present invention includes cooling the bonded structure and applying ultrasonic vibrations to a part or all of the bonded structure. This configuration not only makes it easier to separate the bonded structure but also shortens the separation time.

[0035] According to the present invention, it is possible to provide a peeling method that can easily peel off a bonded assembly of a substrate and a transport substrate for transporting the substrate.

[0036] FIG. 1 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 4 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 5 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 6 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 7 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 8 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 9 is a schematic diagram illustrating steps of a peeling method according to an embodiment of the present invention. FIG. 10 is a schematic diagram illustrating steps of a joining process of a joined body that is a target of the peeling method according to an embodiment of the present invention. FIG. 11 is a schematic diagram illustrating steps of a joining process of a joined body that is a target of the peeling method according to an embodiment of the present invention. FIG. 12 is a schematic diagram illustrating steps of a joining process of a joined body that is a target of the peeling method according to an embodiment of the present invention. FIG. 13 is a schematic diagram illustrating steps of a joining process of a joined body that is a target of the peeling method according to an embodiment of the present invention.

[0037] The present invention will be described below by way of embodiments, but it is obvious that the present invention is not limited to these specific embodiments.

[0038] 1 to 4 are schematic diagrams illustrating steps of a peeling method according to this embodiment. The steps of the peeling method according to this embodiment will be described below with reference to the drawings.

[0039] (a) Bonded Body Preparation Process As shown in FIG. 1 , this embodiment is a peeling method for peeling off a bonded body 5 of a substrate 1 and a transport substrate 3. The bonded body 5 includes the substrate 1 and the transport substrate 3 bonded together via a bonding layer 7. This bonding layer may be an inorganic film, or a bonding layer formed by applying energy to the bonding surfaces of one or both of the substrate 1 and the transport substrate 3. Here, applying energy includes applying an ion beam, an electron beam, or UV radiation to the surfaces of the substrate 1 and the transport substrate 3. The substrate 1 may be glass, silicon, a compound semiconductor, a polymer film, or a combination thereof, either alone or with a circuit. Here, the term "single" refers to a material that does not have a circuit on its surface, such as glass, silicon, a compound semiconductor, or a polymer film. In this embodiment, the substrate 1 has a circuit layer 9 formed on the surface of a circuit board 11. The state shown in FIG. 1 shows the substrate 1 after the thinning process.

[0040] (b) Cooling Step of Bonded Body As shown in FIG. 2, the bonded body 5 is transferred into a cooling chamber 13 and cooled in an atmosphere F in the cooling chamber 13. The cooling atmosphere F may be ordinary air or may be filled with an inert gas. The atmosphere F may also be a liquid. The liquid may be water, alcohols, or a mixture thereof. The cooling temperature may be −1° C. to −100° C., preferably −20° C. to −50° C.

[0041] (c) Ultrasonic Wave Application Step As shown in Fig. 3, after the cooling step, ultrasonic waves U are applied to the bonded body 5. The ultrasonic waves U are applied from the surface of either the substrate 1 or the transport substrate 3, or from both surfaces of the substrate 1 and the transport substrate 3, in the thickness direction of the substrate 1 and the transport substrate 3, and toward the bonding layer 7. In this embodiment, the ultrasonic waves U are applied from the surface of the transport substrate 3 in the thickness direction of the transport substrate 3, and toward the bonding layer 7. The frequency of the ultrasonic waves at this time may be 20 kHz to 950 kHz, preferably 20 kHz to 100 kHz. These wavelengths may also be mixed.

[0042] (d) Peeling State As shown in FIG. 4, when the ultrasonic wave application process is carried out for a certain period of time, the bonded body is peeled into the substrate 1 and the transfer substrate 3, and the series of processes is completed.

[0043] As described above, in this embodiment, after the bonded body 5 is cooled in the cooling chamber 13, ultrasonic waves U are applied to the bonding layer 7 to separate the substrate 1 from the transport substrate 3. Therefore, even if the bonded body has been firmly bonded through a thermal process or the like, it can be easily separated from the substrate 1 from the transport substrate 3 without causing any damage to the substrate 1 and the transport substrate 3.

[0044] Second Embodiment FIG. 5 is a schematic diagram illustrating one step of this embodiment. In addition to the steps of the first embodiment, this embodiment includes the steps of immersing the bonded structure 5 in a water tank 15 filled with water W to interpose the water between the bonding layer 7 between the substrate 1 and the transport substrate 3, as shown in FIG. 5, before applying the ultrasonic vibrations shown in FIG. 3. Other steps are the same as those of the first embodiment. In this embodiment, water is interposed between the bonding layer 7 between the substrate 1 and the transport substrate 3 before applying the ultrasonic vibrations in the first embodiment, making peeling even easier by the presence of water. In this embodiment, the bonded structure 5 is immersed in a water tank 15 filled with water W to interpose the water between the bonding layer 7 between the substrate 1 and the transport substrate 3 before applying the ultrasonic vibrations, but this step may be performed before cooling the bonded structure 5.

[0045] Third Embodiment FIG. 6 is a schematic diagram illustrating one step of this embodiment. In this embodiment, the application of ultrasonic vibrations shown in FIG. 3 of the first embodiment is performed by immersing the bonded structure 5 in a liquid tank 16 filled with liquid L, as shown in FIG. 6, with the liquid interposed therebetween. Specifically, an ultrasonic vibrator 17 disposed at the bottom of the liquid tank 16 is driven, and ultrasonic waves U are applied to the bonded structure 5 through the liquid L. As shown in the figure, the ultrasonic waves U are applied from the bottom of the substrate 1 in its thickness direction toward the bonding layer 7 through the liquid L. Here, the liquid L may be water, alcohol, or a mixture thereof. The liquid L may be heated. The temperature of the liquid may be 30°C to 100°C, preferably 30°C to 60°C. The frequency of the ultrasonic waves may be 20 kHz to 950 kHz, preferably 20 kHz to 100 kHz. These wavelengths may also be mixed. Other steps are the same as those in the first embodiment. In this embodiment, the application of ultrasonic waves in the first embodiment is performed through the liquid L, so that the application of ultrasonic waves can be performed efficiently, and peeling can be further promoted.

[0046] In this embodiment, the liquid L may be pure water, or as shown in Fig. 9, a gas G may be mixed into the pure water. The gas G may be oxygen, nitrogen, or ozone. By mixing the gas G into the pure water, the peeling can be further promoted.

[0047] Fourth Embodiment FIG. 7 is a schematic diagram illustrating the steps of this embodiment. In this embodiment, the application of ultrasonic vibrations shown in FIG. 3 of the first embodiment is achieved by bringing a hollow metal case 19 into contact with the transfer substrate 3 side of the bonded structure 5, filling the metal case 19 with liquid L, and applying ultrasonic vibrations U from the inside of the metal case 19 to the transfer substrate 3 side, as shown in FIG. 7( a). The bonded structure 5 is held by a chuck 23 and pressed against the metal case 19. As shown in FIG. 7( b), applying ultrasonic waves for a certain period of time can delaminate the bonded structure 5 into the substrate 1 and the transfer substrate 3. Specifically, an ultrasonic vibrator (not shown) is disposed inside the metal case 19, and ultrasonic waves U are applied from the ultrasonic vibrator to the transfer substrate 3 side in the thickness direction toward the bonding layer 7 through the liquid L filled inside the metal case 19, thereby promoting delamination between the substrate 1 and the transfer substrate 3. Here, the liquid L may be water, an alcohol, or a mixture thereof. The liquid L may be heated. The temperature of the liquid may be 30°C to 100°C, preferably 30°C to 60°C. The frequency of the ultrasonic waves may be 20 kHz to 950 kHz, preferably 20 kHz to 100 kHz. These wavelengths may also be mixed. Other steps are the same as those in the first embodiment. In this embodiment, the ultrasonic waves of the first embodiment are applied from inside the metal case 19 through the liquid L, thereby enabling efficient application of the ultrasonic waves and further promoting peeling. In this embodiment, the hollow metal case 19 is filled with the liquid L, but this is not limited thereto. Any medium through which ultrasonic waves can propagate may be used, for example, a gas. Furthermore, ultrasonic waves may be applied using a metal-filled container rather than a hollow container.

[0048] Fifth Embodiment FIG. 8 is a schematic diagram illustrating the steps of this embodiment. In this embodiment, the ultrasonic vibrations shown in FIG. 3 of the first embodiment are applied as shown in FIG. 8( a). A metal case 21 with one opening is placed with the opening facing the transfer substrate 3, the open end is fixed with a sealing material (seal tube) 25, a liquid L is filled into the metal case 21, and ultrasonic vibrations U are applied from the inside of the metal case 21 to the transfer substrate 3 via the liquid L. The bonded body 5 is held by a chuck 23 and in contact with the open side of the metal case 21. As shown in FIG. 8( b), applying ultrasonic waves U for a certain period of time can separate the substrate 1 from the transfer substrate 3. The liquid L is then discharged, and the metal case 21 and the transfer substrate 3 are separated from the substrate 1 and transported. The liquid L is filled and discharged through a tube 27. Specifically, an ultrasonic vibrator (not shown) is placed inside the metal case 21, and ultrasonic waves U are applied from the ultrasonic vibrator to the transfer substrate 3 in the thickness direction toward the bonding layer 7 through the liquid L filled inside the metal case 21, thereby promoting delamination between the substrate 1 and the transfer substrate 3. Here, the liquid L may be water, alcohol, or a mixture thereof. The liquid L may be heated. The temperature of the liquid may be 30°C to 100°C, preferably 30°C to 60°C. The frequency of the ultrasonic waves may be 20 kHz to 950 kHz, preferably 20 kHz to 100 kHz. These wavelengths may also be mixed. Other steps are the same as those in the first embodiment. In this embodiment, the ultrasonic waves of the first embodiment are applied directly toward the transfer substrate 3 through the liquid L from inside the metal case 21, which is open on one side. This allows for efficient application of the ultrasonic waves, thereby further promoting delamination.

[0049] 10 to 19 are diagrams showing a bonding step of a bonded body that is a target of a peeling step in the present invention. The bonding step of the bonded body of this embodiment will be described below with reference to the drawings.

[0050] <1> Preparation of substrate and transportation substrate As shown in Fig. 10, a substrate 1 having a circuit layer 9 on a circuit board 11 and a transportation substrate 3 are prepared. <2> Surface treatment of bonding surfaces As shown in Fig. 11, a surface treatment is performed by irradiating the bonding surfaces of either or both of the substrate 1 and the transportation substrate 3 with first ultraviolet light 31 having a wavelength of 200 nm or less. In this embodiment, the first ultraviolet light 31 is irradiated onto the bonding surfaces of both the substrate 1 and the transportation substrate 3.

[0051] <3> Bonding of the substrate and the substrate for transportation As shown in Fig. 12, the bonding surfaces of the surface-treated substrate 1 and the substrate for transportation 3 are brought into contact with each other and pressure is applied to bond the substrate 1 and the substrate for transportation 3. <4> Completion of the bonded body As shown in Fig. 13, a bonded body 41 is obtained through the above steps. The bonded body 41 is a bonded body 41 in which the substrate 1, which is made of the circuit board 11 and the circuit layer 9, and the substrate for transportation 3 are bonded together.

[0052] By using such a bonded body, processes such as circuit formation can be carried out while maintaining bonding strength that prevents peeling during the transportation process (semiconductor manufacturing process), and by applying the above-described peeling embodiment, a bonded body that can be easily peeled can be provided.

[0053] (Variation 1 of the Sixth Embodiment) In this variation, a bonding layer is formed before the surface treatment (the above-described step <2>) of the bonding surface between the substrate 1 and the transportation substrate 3. As shown in FIG. 14 , a thin film of Si is formed on the bonding surface by sputtering to a thickness of 0.1 nm to 30 nm as the bonding layer 7. As shown in FIG. 15 , the bonding layer 7 is irradiated with second ultraviolet light 33 to activate the bonding layer surface. Alternatively, the bonding layer 7 is irradiated with an ion beam 35, and then the bonding layer 7 is irradiated with second ultraviolet light 33 to activate the bonding layer surface. Thereafter, the above-described bonding steps <2> and subsequent steps are performed to obtain a bonded body 43 shown in FIG. 16 . This embodiment can provide a bonded body 43 that maintains a more stable bonding strength during transportation and can be easily peeled off in the above-described peeling step.

[0054] (Variation 2 of Sixth Embodiment) In this variation, before the surface treatment of the bonding surfaces of the substrate 2 and the transportation substrate 3 (the above-described step <2>), a substrate 2 having a pattern with convex portions formed on the circuit layer 39 is prepared as shown in FIG. 17 . Thereafter, the bonding steps from <2> onwards are performed to obtain a bonded body 45 shown in FIG. 18 . In the bonded body 45 of this variation, as shown in FIG. 18 , only the convex portions are selectively bonded. In this embodiment, a bonded body 45 whose bonding strength can be adjusted by adjusting the pattern of the convex portions can be provided.

[0055] The embodiments of the present invention have been described above. It is clear that modifications can be made to these without departing from the technical concept of the invention as defined in the claims. Furthermore, the configurations described in the above embodiments can be selected or changed as appropriate.

[0056] Examples of the present invention are shown below, but the scope of the present invention should not be construed as being limited to these examples.

[0057] The tests in the examples were carried out according to the following procedure.

[0058] (1) Preparation of Transfer Substrate and Device Substrate As a sample combination, 4-inch silicon wafers were prepared as transfer substrates and device substrates.

[0059] (2) Formation of inorganic layer (bonding layer) For each sample, an inorganic layer (bonding layer) of Si (silicon) was formed on the surface (one side) of the silicon wafer using ion beam sputtering, as shown in Table 1. The number of scans was 1, and 1.5 nm was formed per scan, so a 1.5 nm thick inorganic layer of Si (silicon) was formed.

[0060] (3) Room-temperature bonding treatment The room-temperature bonding treatment was carried out under the following conditions: (Room-temperature bonding conditions) Pressing conditions: 5 kN / 5 min Pressing environment: N ２ (Nitrogen) environment

[0061] (4) Heat Treatment After room temperature bonding, the heat treatment shown in Table 1 below was carried out, simulating the device manufacturing process.

[0062] (5) Cooling Treatment Thereafter, the bonded body was cooled in a cooling chamber at −40° C. for 1 hour.

[0063] (6) Peeling by ultrasonic application Ultrasonic vibration of 38 kHz was applied to the cooled samples. For samples 5 and 6, ultrasonic vibration was applied 15 seconds after cooling, and for the others, ultrasonic vibration was applied after the samples were returned to room temperature.

[0064] (Peeling Results) As shown in Table 1, all samples were peeled off within 10 minutes. The data shows that the peeling time tends to be shorter when ultrasonic waves are applied in a cooled state.

[0065] As comparative examples, peeling was carried out in the same manner as in the above examples except that the cooling treatment in (5) above was not carried out, but peeling was difficult in both cases (Table 1, sample numbers h1 and h2).

[0066] From the above results, it can be seen that the substrate can be easily peeled off by the peeling method according to the present invention.

[0067] REFERENCE SIGNS LIST 1, 2 Substrate 3 Transfer substrate 5, 41, 43, 45 Bonded body 7 Bonding layer 19 Metal case 21 Metal case with one side open 25 Bonding material (seal tube) 31 First ultraviolet light 33 Second ultraviolet light 35 Ion beam 39 Circuit layer with convex portion G Gas (oxygen, nitrogen, ozone) L Liquid U Ultrasonic wave W Water

Claims

1. A method for peeling off a bonded structure of a substrate and a transportation substrate, comprising: cooling the bonded structure of the substrate and the transportation substrate; and applying ultrasonic vibrations from a surface of either the substrate or the transportation substrate, or from a surface of both the substrate and the transportation substrate, in the thickness direction of the substrate and the transportation substrate, and toward the bonding layer.

2. The peeling method according to claim 1, further comprising the step of: interposing water on the bonding layer between the substrate and the transfer substrate before applying the ultrasonic vibration.

3. The method according to claim 1, further comprising the step of: before the cooling, placing water on the bonding layer between the substrate and the transportation substrate.

4. The peeling method according to claim 1 or 2, wherein the application of ultrasonic vibrations is carried out through the presence of a liquid.

5. The stripping method according to claim 4, wherein the liquid is water, an alcohol, or a mixture thereof.

6. The method of claim 4, further comprising the step of: heating the liquid.

7. A peeling method according to claim 1 or 2, wherein the application of ultrasonic vibrations includes bringing a hollow metal case into contact with the transport substrate, filling the inside of the metal case with a liquid, and applying ultrasonic vibrations from the inside of the metal case to the transport substrate.

8. The method of claim 7, further comprising the step of: heating the liquid.

9. A peeling method according to claim 1 or 2, wherein the application of ultrasonic vibrations includes contacting a metal case having an opening on one side with the opening facing the transport substrate, filling the inside of the metal case with liquid, and applying ultrasonic vibrations from the inside of the metal case to the transport substrate.

10. The method of claim 9, further comprising: heating the liquid.

11. The peeling method according to claim 1 or 2, wherein applying the ultrasonic vibrations includes: orienting a metal case having an opening on one side so that the opening faces the transport substrate, fixing the open end with a bonding material, filling the inside of the metal case with a liquid, and applying ultrasonic vibrations from the inside of the metal case to the transport substrate; draining the liquid, and separating and transporting the metal case together with the transport substrate from the substrate.

12. The method of claim 11, further comprising: the liquid being heated.

13. The method according to claim 1 or 2, wherein the substrate is any one or any combination of glass, silicon, a compound semiconductor, and a polymer film, either a simple substance or having a circuit.

14. The peeling method according to claim 1 or 2, wherein the bonded bodies are bonded via an inorganic film.

15. A peeling method according to claim 1 or 2, wherein the bonding of the bonded body is achieved by subjecting either or both of the bonding surfaces of the substrate and the transportation substrate to a surface treatment that applies energy.

16. A peeling method according to claim 1 or 2, wherein the bonding of the bonded body is achieved by subjecting the bonding surfaces of either or both of the substrate and the transport substrate to a surface treatment in which a first ultraviolet ray having a wavelength of 200 nm or less is irradiated onto the bonding surfaces.

17. The peeling method according to claim 16, wherein the bonding of the bonded body is performed by forming a thin film of Si to a thickness of 0.1 nm to 30 nm on the bonding surface by sputtering, and then irradiating the second ultraviolet light.

18. The peeling method according to claim 16, wherein the bonding of the bonded body is performed by forming a thin film of Si on the bonding surface by sputtering to a thickness of 0.1 nm to 30 nm, activating the surface of the thin film with an ion beam, and then irradiating it with a second ultraviolet ray.

19. The peeling method according to claim 16, wherein the bonding of the bonded body is performed by selectively bonding only protruding portions of the substrate that have a pattern formed thereon.

20. The method of claim 4, wherein the liquid is pure water.

21. The stripping method according to claim 20, further comprising mixing oxygen into the pure water.

22. The stripping method according to claim 20, wherein nitrogen is mixed into the pure water.

23. The stripping method according to claim 20, further comprising mixing ozone into the pure water.

24. A method for peeling off a bonded structure of a substrate and a transportation substrate, the method comprising cooling the bonded structure and applying ultrasonic vibrations to a part or all of the bonded structure.

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