JP4619461B2 - Thin film device transfer method and device manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transfer method for transferring a transfer layer including a thin film device to a transfer body, and a device manufacturing method.
[0002]
[Prior art]
For example, when manufacturing a liquid crystal display (LCD) using a thin film transistor (TFT), a thin film transistor is formed on a transparent substrate by CVD or the like.
[0003]
These thin film transistors include those using amorphous silicon (a-Si) and those using polysilicon (p-Si), and those using polysilicon are formed through a high-temperature process. And those formed through a low-temperature process.
[0004]
By the way, since the thin film transistor is formed on the transparent substrate at a high temperature, it is necessary to use a material having excellent heat resistance as the transparent substrate. Therefore, at present, a transparent substrate made of quartz glass is used because it has a high softening point and a high melting point and can sufficiently withstand a temperature of about 1000 ° C. in a high-temperature process. Further, in the low temperature process, since a temperature around 500 ° C. becomes the maximum process temperature, heat resistant glass is used.
[0005]
However, such quartz glass having excellent heat resistance is a rare and very expensive material compared to ordinary glass, and it is difficult to produce a large transparent substrate. In addition, heat-resistant glass can be made larger than quartz glass, but it is much more expensive than ordinary glass. Further, both quartz glass and heat-resistant glass are brittle and easily broken, and are heavy. This is a serious drawback in constructing an LCD. Therefore, it has been an obstacle to manufacturing a large and inexpensive liquid crystal display.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a peeling method that can be easily peeled regardless of the properties, conditions, etc. of the object to be peeled, and in particular, can be transferred to various transfer bodies.
[0007]
[Means for Solving the Problems]
Such an object is achieved by the present invention described below.
[0008]
In a thin film device transfer method for transferring a transfer layer including a thin film device on a substrate to a transfer body, a step of forming a separation layer on the substrate, a step of forming the thin film device on the separation layer, and the separation A step of causing peeling in the layer and / or interface of the layer, and transferring the transferred layer to the transfer body, and removing the separation layer attached to the substrate after the transfer. It is characterized by that.
[0009]
By irradiating the separation layer with light, peeling occurs in the separation layer and / or at the interface.
[0010]
The substrate is light-transmitting, and the separation layer is irradiated with light from the substrate side.
[0011]
The transfer layer is formed directly on the separation layer.
[0012]
The transferred layer is formed on the separation layer via an intermediate layer.
[0013]
The transfer body is composed of a material having a glass transition point (Tg) or a softening point equal to or lower than Tmax, where Tmax is a maximum temperature in forming the transfer layer.
[0014]
The transfer body is composed of a material having a glass transition point (Tg) or a softening point of 800 ° C. or less.
[0015]
The substrate is made of a material having a strain point equal to or higher than Tmax, where Tmax is a maximum temperature when the transfer layer is formed.
[0016]
The transfer body is made of a glass substrate, and the substrate is made of quartz.
[0017]
For example, a thin film transistor can be used as the thin film device.
[0018]
As said irradiation light, a laser beam can be used, for example, Preferably it is 100-350 nm, Furthermore, it is good in it being a wavelength of 350 nm-1200 nm.
[0019]
As the separation layer, amorphous silicon is preferably used, and the amorphous silicon may contain 2 at% or more of H (hydrogen).
[0020]
The separation layer can be composed of ceramics, metal, organic polymer material, and in the case of organic polymer material, -CH2-, -CO-, -CONH-, -NH-, -COO- , —N═N—, —CH═N—, preferably having at least one bond.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the peeling method of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
[0034]
1-8 is sectional drawing which shows the process of the Example of the peeling method of this invention, respectively. Hereinafter, the steps of the peeling method (transfer method) of the present invention will be sequentially described based on these drawings.
[0035]
[1] As shown in FIG. 1, a separation layer (light absorption layer) 2 is formed on one surface (separation layer formation surface 11) of the substrate 1.
[0036]
When the substrate 1 irradiates the irradiation light 7 from the substrate 1 side, the substrate 1 preferably has translucency through which the irradiation light 7 can pass.
[0037]
In this case, the transmittance of the irradiation light 7 is preferably 10% or more, and more preferably 50% or more. If this transmittance is too low, the attenuation (loss) of the irradiation light 7 increases, and a larger amount of light is required to peel off the separation layer 2.
[0038]
Moreover, it is preferable that the board | substrate 1 is comprised with the material with high reliability, and it is especially preferable that it is comprised with the material excellent in heat resistance. The reason is that, for example, when forming the transferred layer 4 or the intermediate layer 3 described later, the process temperature may be high (for example, about 350 to 1000 ° C.) depending on the type and the forming method. This is because if the substrate 1 is excellent in heat resistance, the range of setting of film forming conditions such as the temperature condition is widened when forming the transferred layer 4 or the like on the substrate 1.
[0039]
Therefore, the substrate 1 is preferably made of a material having a strain point equal to or higher than Tmax, where Tmax is the maximum temperature when the transfer layer 4 is formed. Specifically, the constituent material of the substrate 1 preferably has a strain point of 350 ° C. or higher, more preferably 500 ° C. or higher. Examples of such a material include heat-resistant glass such as quartz glass, soda glass, Corning 7059, and Nippon Electric Glass OA-2.
[0040]
In addition, if the process temperature at the time of formation of the separation layer 2, the intermediate layer 3, and the transferred layer 4 described later is lowered, an inexpensive glass material or synthetic resin having a low melting point can be used for the substrate 1 as well. .
[0041]
The thickness of the substrate 1 is not particularly limited, but is usually preferably about 0.1 to 5.0 mm, more preferably about 0.5 to 1.5 mm. If the thickness of the substrate 1 is too thin, the strength is reduced, and if it is too thick, the irradiation light 7 is easily attenuated when the transmittance of the substrate 1 is low. In addition, when the transmittance | permeability of the irradiation light 7 of the board | substrate 1 is high, the thickness may exceed the said upper limit.
[0042]
In addition, it is preferable that the thickness of the separation layer forming portion of the substrate 1 is uniform so that the irradiation light 7 can be uniformly irradiated.
[0043]
Further, the separation layer forming surface 11 and the irradiation light incident surface 12 of the substrate 1 are not limited to flat surfaces as shown in the figure, and may be curved surfaces.
[0044]
In the present invention, the substrate 1 is not removed by etching or the like, but the separation layer 2 between the substrate 1 and the transferred layer 4 is peeled off to separate the substrate 1. The range of choices for the substrate 1 is wide, such as using a relatively thick substrate.
[0045]
Next, the separation layer 2 will be described.
[0046]
The separation layer 2 has such a property that it absorbs irradiation light 7 described later and causes peeling (hereinafter referred to as “in-layer peeling” or “interface peeling”) in the layer and / or the interface 2a or 2b. Preferably, by irradiating the irradiation light 7, the bonding force between atoms or molecules of the substance constituting the separation layer 2 disappears or decreases, and in reality, by causing ablation or the like, It leads to peeling and / or interfacial peeling.
[0047]
Furthermore, the irradiation of the irradiation light 7 may cause a gas to be released from the separation layer 2 and exhibit a separation effect. That is, there are a case where the component contained in the separation layer 2 is released as a gas, and a case where the separation layer 2 absorbs light and becomes a gas for a moment, and its vapor is emitted, contributing to the separation. .
[0048]
Examples of the composition of the separation layer 2 include the following.
[0049]
(1) Amorphous silicon (a-Si)
This amorphous silicon may contain H (hydrogen). In this case, the H content is preferably about 2 at% or more, more preferably about 2 to 20 at%. As described above, when a predetermined amount of H is contained, hydrogen is released by the irradiation of the irradiation light 7, and an internal pressure is generated in the separation layer 2, which becomes a force for peeling the upper and lower thin films.
[0050]
The content of H in the amorphous silicon is adjusted by appropriately setting film forming conditions such as gas composition, gas pressure, gas atmosphere, gas flow rate, temperature, substrate temperature, and input power in CVD. Can do.
[0051]
(2) Various oxide ceramics such as silicon oxide or silicate compound, titanium oxide or titanate compound, zirconium oxide or zirconate compound, lanthanum oxide or lanthanate compound, dielectric (ferroelectric) or semiconductor
Examples of silicon oxide include SiO, SiO2, and Si3 O2. Examples of silicic acid compounds include K2 SiO3, Li2 SiO3, CaSiO3, ZrSiO4, and Na2 SiO3.
[0052]
Examples of the titanium oxide include TiO, Ti2 O3, and TiO2, and examples of the titanate compound include BaTiO4, BaTiO3, Ba2 Ti9 O20, BaTi5 O11, CaTiO3, SrTiO3, PbTiO3, MgTiO3, ZrTiO2, TiTiO, SnTiO2, and TiTiO3. Is mentioned.
[0053]
Examples of the zirconium oxide include ZrO2, and examples of the zirconate compound include BaZrO3, ZrSiO4, PbZrO3, MgZrO3, and K2 ZrO3.
[0054]
(3) Ceramics such as PZT, PLZT, PLLZT, PBZT or dielectrics (ferroelectric materials)
(4) Nitride ceramics such as silicon nitride, aluminum nitride, titanium nitride
(5) Organic polymer materials
Organic polymer materials include -CH2-, -CO- (ketone), -CONH- (amide), -NH- (imide), -COO- (ester), -N = N- (azo), -CH Any of those having a bond such as = N- (Schiff) (these bonds are cut by irradiation with irradiation light 7), particularly those having many of these bonds may be used. The organic polymer material may have an aromatic hydrocarbon (one or more benzene rings or condensed rings thereof) in the structural formula.
[0055]
Specific examples of such organic polymer materials include polyolefins such as polyethylene and polypropylene, polyimide, polyamide, polyester, polymethyl methacrylate (PMMA), polyphenylene sulfide (PPS), polyethersulfone (PES), and epoxy resin. Etc.
[0056]
▲ 6 ▼ Metal
Examples of the metal include Al, Li, Ti, Mn, In, Sn, Y, La, Ce, Nd, Pr, Gd, Sm, or an alloy containing at least one of these.
[0057]
The thickness of the separation layer 2 varies depending on various conditions such as the purpose of stripping, the composition of the separation layer 2, the layer structure, and the formation method, but it is usually preferably about 1 nm to 20 μm, and about 10 nm to 2 μm. More preferably, it is about 40 nm to 1 μm.
[0058]
If the thickness of the separation layer 2 is too small, the uniformity of film formation may be impaired, and unevenness may occur in the peeling. If the thickness is too thick, good separation of the separation layer 2 is ensured. In addition, it is necessary to increase the power (light quantity) of the irradiation light 7 and it takes time to remove the separation layer 2 later. Note that the thickness of the separation layer 2 is preferably as uniform as possible.
[0059]
The formation method of the separation layer 2 is not particularly limited, and is appropriately selected according to various conditions such as film composition and film thickness. For example, CVD (including MOCVD, low pressure CVD, ECR-CVD), vapor deposition, molecular beam vapor deposition (MB), sputtering, ion plating, PVD and other various vapor deposition methods, electroplating, immersion plating (dipping), Various plating methods such as electroless plating, Langmuir / Blodget (LB) method, spin coating, spray coating, roll coating and other coating methods, various printing methods, transfer methods, ink jet methods, powder jet methods, and the like. Two or more of them can be combined to form.
[0060]
For example, when the composition of the separation layer 2 is amorphous silicon (a-Si), it is preferable to form the film by CVD, particularly low pressure CVD or plasma CVD.
[0061]
In the case where the separation layer 2 is composed of ceramics by a sol-gel method or an organic polymer material, it is preferable to form a film by a coating method, particularly spin coating.
[0062]
The formation of the separation layer 2 may be performed in two or more steps (for example, a layer formation step and a heat treatment step).
[0063]
[2] As shown in FIG. 2, an intermediate layer (underlayer) 3 is formed on the separation layer 2.
[0064]
The intermediate layer 3 is formed for various purposes. For example, a protective layer, an insulating layer, a conductive layer, and an irradiation light 7 that physically or chemically protect the transferred layer 4 described later at the time of manufacture or use. Examples thereof include a light shielding layer, a barrier layer that prevents migration of components to or from the transferred layer 4, and a layer that exhibits at least one of functions as a reflective layer.
[0065]
The composition of the intermediate layer 3 is appropriately set according to the purpose of formation thereof. For example, in the case of the intermediate layer 3 formed between the separation layer 2 made of amorphous silicon and the transferred layer 4 made of a thin film transistor. In the case of the intermediate layer 3 formed between the separation layer 2 and the transferred layer 4 by PZT, for example, Pt, Au, W, Ta, Mo, Al, Cr And metals such as Ti or alloys mainly composed of these.
[0066]
The thickness of such an intermediate layer 3 is appropriately determined according to the purpose of formation and the degree of function that can be exhibited, but it is usually preferably about 10 nm to 5 μm, and preferably about 40 nm to 1 μm. Is more preferable.
[0067]
Moreover, the formation method of the intermediate | middle layer 3 can also mention the method similar to the formation method quoted by the said separation layer 2. Further, the formation of the intermediate layer 3 may be performed in two or more steps.
[0068]
Note that two or more layers having the same or different composition can be formed as the intermediate layer 3. In the present invention, the transfer layer 4 may be formed directly on the separation layer 2 without forming the intermediate layer 3.
[0069]
[3] As shown in FIG. 3, a layer to be transferred (a material to be peeled) 4 is formed on the intermediate layer 3.
[0070]
The transferred layer 4 is a layer to be transferred to a transfer body 6 to be described later, and can be formed by the same method as the forming method described for the separation layer 2.
[0071]
The formation purpose, type, form, structure, composition, physical or chemical characteristics, etc. of the transferred layer 4 are not particularly limited, but in consideration of the purpose and usefulness of the transfer, a thin film, particularly a functional thin film or a thin film device. Is preferred.
[0072]
As functional thin films and thin film devices, for example, thin film transistors, thin film diodes, other thin film semiconductor devices, electrodes (eg, transparent electrodes such as ITO and mesa films), photoelectric conversion elements used for solar cells and image sensors, Switching elements, memories, actuators such as piezoelectric elements, micromirrors (piezo thin film ceramics), magnetic recording media, magneto-optical recording media, optical recording media and other recording media, magnetic recording thin film heads, coils, inductors, thin film high magnetic permeability materials And optical magnetic films such as micro magnetic devices, filters, reflective films, dichroic mirrors, polarizing elements, semiconductor thin films, superconducting thin films (example: YBCO thin films), magnetic thin films, metal multilayer thin films, metal ceramic multilayer thin films, metals Semiconductor multilayer thin film, ceramic semiconductor multilayer thin film, organic Examples include thin films and multilayer thin films of other substances.
[0073]
Among these, it is particularly useful because it is highly useful when applied to a thin film device, a micro magnetic device, a configuration of a micro three-dimensional structure, an actuator, a micro mirror, and the like.
[0074]
Such a functional thin film or thin film device is usually formed through a relatively high process temperature in relation to its formation method. Therefore, in this case, as described above, the substrate 1 needs to have a high reliability that can withstand the process temperature.
[0075]
The transferred layer 4 may be a single layer or a laminate of a plurality of layers. Furthermore, a predetermined patterning may be performed like the thin film transistor. Formation (lamination) and patterning of the transferred layer 4 are performed by a predetermined method corresponding thereto. Such a transferred layer 4 is usually formed through a plurality of steps.
[0076]
The formation of the transferred layer 4 using a thin film transistor is, for example, disclosed in Japanese Patent Publication No. 2-50630 and literature: H. Ohshima et al: International Symposium Digest of Technical Papers SID 1983 “B / W and Color LC Video Display Addressed by Poly
It can be carried out according to the method described in “Si TFTs”.
[0077]
Further, the thickness of the transferred layer 4 is not particularly limited, and is appropriately set according to various conditions such as the purpose of formation, function, composition, and characteristics. When the transferred layer 4 is a thin film transistor, the total thickness is preferably about 0.5 to 200 μm, more preferably about 1.0 to 10 μm. In the case of other thin films, the preferred total thickness may be in a wider range, for example, about 50 nm to 1000 μm.
[0078]
The transferred layer 4 is not limited to the thin film as described above, and may be a thick film such as a coating film or a sheet, and further, for example, constitutes a film (layer) such as a powder. It may be an object to be transferred or an object to be peeled off.
[0079]
[4] As shown in FIG. 4, an adhesive layer 5 is formed on a transfer target layer (object to be peeled) 4, and the transfer body 6 is bonded (bonded) through the adhesive layer 5.
[0080]
Suitable examples of the adhesive constituting the adhesive layer 5 include various curable types such as a reactive curable adhesive, a thermosetting adhesive, a photocurable adhesive such as an ultraviolet curable adhesive, and an anaerobic curable adhesive. An adhesive is mentioned. The composition of the adhesive may be any, for example, epoxy, acrylate, or silicone. Such an adhesive layer 5 is formed, for example, by a coating method.
[0081]
In the case of using the curable adhesive, for example, after applying a curable adhesive on the transfer layer 4 and joining a transfer body 6 to be described later on the curable adhesive, the curing method according to the characteristics of the curable adhesive is used. The curable adhesive is cured, and the transferred layer 4 and the transfer body 6 are bonded and fixed.
[0082]
In the case of using a photocurable adhesive, the translucent transfer body 6 is disposed on the uncured adhesive layer 5, and then the adhesive is cured by irradiating the curing light from the transfer body 6. preferable. If the substrate 1 has translucency, it is preferable to cure the adhesive by irradiating the curing light from both sides of the substrate 1 and the transfer body 6 to ensure the curing.
[0083]
Unlike the illustration, the adhesive layer 5 may be formed on the transfer body 6 side, and the transferred layer 4 may be adhered thereon. Further, an intermediate layer as described above may be provided between the transferred layer 4 and the adhesive layer 5. For example, when the transfer body 6 itself has an adhesive function, the formation of the adhesive layer 5 may be omitted.
[0084]
Although it does not specifically limit as the transfer body 6, A board | substrate (plate material), especially a transparent substrate are mentioned. Such a substrate may be a flat plate or a curved plate.
[0085]
Further, the transfer body 6 may be inferior to the substrate 1 in properties such as heat resistance and corrosion resistance. The reason is that, in the present invention, the transfer layer 4 is formed on the substrate 1 side, and then the transfer layer 4 is transferred to the transfer body 6. This is because it does not depend on the temperature condition or the like when forming the transferred layer 4.
[0086]
Therefore, when the maximum temperature during formation of the transferred layer 4 is Tmax, a material having a glass transition point (Tg) or a softening point equal to or lower than Tmax can be used as a constituent material of the transfer body 6. For example, the transfer body 6 can be made of a material having a glass transition point (Tg) or a softening point of preferably 800 ° C. or lower, more preferably 500 ° C. or lower, and further preferably 320 ° C. or lower.
[0087]
Further, the mechanical properties of the transfer body 6 are preferably those having a certain degree of rigidity (strength), but may be those having flexibility and elasticity.
[0088]
Examples of the constituent material of the transfer body 6 include various synthetic resins or various glass materials, and various synthetic resins and normal (low melting point) inexpensive glass materials are particularly preferable.
[0089]
The synthetic resin may be either a thermoplastic resin or a thermosetting resin. For example, polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), cyclic polyolefin, modified polyolefin , Polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylpentene-1), ionomer, acrylic resin, polymethyl methacrylate (PMMA), acrylonitrile-butadiene-styrene Polymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), butadiene-styrene copolymer, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyester such as polycyclohexane terephthalate (PCT), polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal ( POM), polyphenylene oxide, modified polyphenylene oxide, polysulfone, polyphenylene sulfide (PPS), polyethersulfone (PES), polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluorine resins, Styrene, polyolefin, polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, transpoly Various thermoplastic elastomers such as prene, fluororubber, chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester, silicone resin, polyurethane, etc., or copolymers mainly comprising these, A blend body, a polymer alloy, etc. are mentioned, Among these, it can use 1 type or in combination of 2 or more types (for example, as a laminated body of 2 layers or more).
[0090]
Examples of the glass material include silicate glass (quartz glass), alkali silicate glass, soda lime glass, potash lime glass, lead (alkali) glass, barium glass, borosilicate glass, and the like. Of these, glass other than silicate glass is preferable because it has a lower melting point than silicate glass, is relatively easy to mold and process, and is inexpensive.
[0091]
When the transfer member 6 made of a synthetic resin is used, the large transfer member 6 can be integrally formed, and even a complicated shape such as a curved surface or an uneven surface can be easily formed. In addition, various advantages such as low material cost and low manufacturing cost can be obtained. Therefore, a large and inexpensive device (for example, a liquid crystal display) can be easily manufactured.
[0092]
The transfer body 6 is a part of a device such as a liquid crystal cell that constitutes an independent device itself, such as a color filter, an electrode layer, a dielectric layer, an insulating layer, or a semiconductor element. May be included.
[0093]
Further, the transfer body 6 may be a material such as metal, ceramics, stone, wood, paper, etc., or on an arbitrary surface constituting a certain item (on the surface of the watch, on the surface of the air conditioner, on the printed circuit board). Etc.) and further on the surface of a structure such as a wall, column, beam, ceiling, window glass or the like.
[0094]
[5] As shown in FIG. 5, the irradiation light 7 is irradiated from the back surface side (irradiation light incident surface 12 side) of the substrate 1. The irradiation light 7 passes through the substrate 1 and then is irradiated onto the separation layer 2 from the interface 2a side. As a result, as shown in FIG. 6 or FIG. 7, intra-layer separation and / or interfacial separation occurs in the separation layer 2, and the bonding force decreases or disappears. Therefore, when the substrate 1 and the transfer body 6 are separated from each other, The transfer layer 4 is detached from the substrate 1 and transferred to the transfer body 6.
[0095]
6 shows a case where intra-layer separation occurs in the separation layer 2, and FIG. 7 shows a case where interface separation occurs at the interface 2a in the separation layer 2. FIG. The principle that separation in the separation layer 2 and / or interfacial separation occurs is that ablation occurs in the constituent material of the separation layer 2, the gas contained in the separation layer 2 is released, and further, immediately after irradiation. It is presumed to be due to phase changes such as melting and transpiration.
[0096]
Here, ablation means that a solid material that absorbs irradiation light (a constituent material of the separation layer 2) is photochemically or thermally excited, and its surface or internal atoms or molecules are cut and released. In other words, all or part of the constituent material of the separation layer 2 appears as a phenomenon that causes a phase change such as melting and transpiration (vaporization). In addition, the phase change may result in a fine foamed state, resulting in a decrease in bonding strength.
[0097]
Whether the separation layer 2 causes in-layer separation, interfacial separation, or both depends on the composition of the separation layer 2 and various other factors. As one of the factors, the irradiation light 7 The conditions such as the type, wavelength, intensity, and depth of arrival are included.
[0098]
Irradiation light 7 may be any material as long as it causes intralayer separation and / or interfacial separation in separation layer 2, for example, X-rays, ultraviolet rays, visible light, infrared rays (heat rays), laser light, millimeter waves. , Microwaves, electron beams, radiation (α rays, β rays, γ rays) and the like. Among them, laser light is preferable in that separation (ablation) of the separation layer 2 is likely to occur.
[0099]
Examples of the laser device that generates the laser light include various gas lasers, solid-state lasers (semiconductor lasers), and the like. Excimer lasers, Nd-YAG lasers, Ar lasers, CO2 lasers, CO lasers, He-Ne lasers, and the like. Among them, an excimer laser is particularly preferable.
[0100]
Since the excimer laser outputs high energy in a short wavelength region, the separation layer 2 can be ablated in a very short time. Therefore, the adjacent intermediate layer 3, the transferred layer 4, the substrate 1, etc. In this case, the separation layer 2 can be peeled off with almost no increase in temperature, that is, without causing deterioration or damage.
[0101]
Moreover, when the irradiation light at the time of generating ablation in the separation layer 2 has wavelength dependence, the wavelength of the irradiated laser light is preferably about 100 to 350 nm.
[0102]
In addition, when the separation layer 2 is given a separation characteristic by causing a phase change such as gas release, vaporization, and sublimation, the wavelength of the irradiated laser light is preferably about 350 to 1200 nm.
[0103]
Further, the energy density of the irradiated laser beam, particularly in the case of an excimer laser, is preferably about 10 to 5000 mJ / cm <2>, more preferably about 100 to 500 mJ / cm <2>. The irradiation time is preferably about 1 to 1000 nsec, more preferably about 10 to 100 nsec. When the energy density is low or the irradiation time is short, sufficient ablation or the like does not occur, and when the energy density is high or the irradiation time is long, the transferred layer is irradiated by the irradiation light transmitted through the separation layer 2 and the intermediate layer 3. 4 may be adversely affected.
[0104]
Irradiation light 7 represented by such laser light is preferably irradiated so that its intensity is uniform.
[0105]
The irradiation direction of the irradiation light 7 is not limited to the direction perpendicular to the separation layer 2 and may be a direction inclined by a predetermined angle with respect to the separation layer 2.
[0106]
In addition, when the area of the separation layer 2 is larger than the irradiation area of one irradiation light, the entire area of the separation layer 2 can be irradiated with irradiation light in a plurality of times. Moreover, you may irradiate the same location twice or more.
[0107]
Further, irradiation light (laser light) of different types and different wavelengths (wavelength regions) may be irradiated twice or more to the same region or different regions.
[0108]
[6] As shown in FIG. 8, the separation layer 2 adhering to the intermediate layer 3 is removed by a method such as cleaning, etching, ashing, polishing, or a combination thereof.
[0109]
In the case of intra-layer separation of the separation layer 2 as shown in FIG. 6, the separation layer 2 attached to the substrate 1 is also removed in the same manner.
[0110]
When the substrate 1 is made of an expensive material such as quartz glass or a rare material, the substrate 1 is preferably used for recycling (recycling). In other words, the present invention can be applied to the substrate 1 to be reused, which is highly useful.
[0111]
The transfer of the transfer layer 4 to the transfer body 6 is completed through the above steps. Thereafter, the intermediate layer 3 adjacent to the transferred layer 4 can be removed, or any other layer can be formed.
[0112]
In the present invention, since the layer to be transferred 4 itself, which is the object to be peeled, is not peeled directly, but peels off at the separation layer 2 bonded to the layer to be transferred 4, the characteristics of the object to be peeled (transfer layer 4) Regardless of conditions, etc., it can be peeled (transferred) easily, reliably and uniformly, and there is no damage to the peeled object (transferred layer 4) during the peeling operation, and the transferred layer 4 has high reliability. Can be maintained.
[0113]
In the illustrated embodiment, the transfer method of the transfer layer 4 to the transfer body 6 has been described. However, the peeling method of the present invention may not perform such transfer. In this case, the object to be peeled is used instead of the transfer layer 4 described above. The object to be peeled may be either a layered one or one that does not constitute a layer.
[0114]
Also, the purpose of peeling the object to be peeled is, for example, removal (trimming) of unnecessary portions of the thin film (particularly functional thin film) as described above, and attachments such as dust, oxides, heavy metals, carbon, and other impurities. Anything such as removal and recycling of the substrate using the same may be used.
[0115]
In addition, the transfer body 6 is not limited to the above-described one, and includes, for example, various metal materials, ceramics, carbon, paper material, rubber, and the like, which have completely different properties from the substrate 1 (regardless of translucency). It may be done. In particular, when the transfer body 6 is a material that cannot directly form the transferred layer 4 or is not suitable for forming, the value of applying the present invention is high.
[0116]
Further, in the illustrated embodiment, the irradiation light 7 is irradiated from the substrate 1 side. However, for example, when the deposit (the object to be peeled) is removed, the transferred layer 4 is not adversely affected by the irradiation of the irradiation light 7. In the case of a thing, the irradiation direction of the irradiation light 7 is not limited to the above, and the irradiation light may be irradiated from the side opposite to the substrate 1.
[0117]
As mentioned above, although the peeling method of this invention was demonstrated about the Example of illustration, this invention is not limited to this.
[0118]
For example, the structure may be such that the layer to be transferred 4 is peeled or transferred in the pattern by irradiating irradiation light partially with respect to the surface direction of the separation layer 2, that is, in a predetermined pattern. Method). In this case, in the step [5], the irradiation light incident surface 12 of the substrate 1 is masked corresponding to the pattern and irradiated with the irradiation light 7 or the irradiation position of the irradiation light 7 is set. It can be performed by a method such as precise control.
[0119]
Further, instead of forming the separation layer 2 on the entire surface of the separation layer forming surface 11 of the substrate 1, the separation layer 2 can be formed in a predetermined pattern (second method). In this case, it is possible to form the separation layer 2 in a predetermined pattern in advance by masking or the like, or to form the separation layer 2 on the entire surface of the separation layer forming surface 11 and then pattern or trim by etching or the like. .
[0120]
According to the first method and the second method as described above, the transferred layer 4 can be transferred together with its patterning and trimming.
[0121]
Further, the transfer may be repeated twice or more by the same method as described above. In this case, if the number of times of transfer is an even number, the front / back positional relationship of the transferred layer formed on the last transfer body may be the same as the state in which the transferred layer is first formed on the substrate 1. it can.
[0122]
Further, a small transparent layer 4 (thin film transistor) formed on a small substrate 1 (for example, 45 mm × 40 mm) having a large transparent substrate (for example, an effective area of 900 mm × 1600 mm) as a transfer body 6 is provided. A plurality of times (for example, about 800 times), preferably sequentially transferred to adjacent positions to form the transferred layer 4 over the entire effective area of the large transparent substrate, and finally a liquid crystal display having the same size as the large transparent substrate Can also be manufactured.
[0123]
【Example】
Next, specific examples of the present invention will be described.
[0124]
Example 1
A quartz substrate (softening point: 1630 ° C., strain point: 1070 ° C., excimer laser transmittance: almost 100%) having a length of 50 mm × width of 50 mm × thickness of 1.1 mm is prepared, and a separation layer is provided on one side of the quartz substrate. As the (laser light absorbing layer), an amorphous silicon (a-Si) film was formed by a low pressure CVD method (Si2 H6 gas, 425 DEG C.). The thickness of the separation layer was 100 nm.
[0125]
Next, an SiO2 film was formed as an intermediate layer on the separation layer by the ECR-CVD method (SiH4 + O2 gas, 100 DEG C.). The film thickness of the intermediate layer was 200 nm.
[0126]
Next, an amorphous silicon film having a thickness of 50 nm is formed on the intermediate layer as a transfer layer by low-pressure CVD (Si2 H6 gas, 425 ° C.), and laser light (wavelength 308 nm) is formed on the amorphous silicon film. And crystallized to obtain a polysilicon film. Thereafter, the polysilicon film was subjected to predetermined patterning to form regions serving as the source / drain / channel of the thin film transistor. Thereafter, the surface of the polysilicon film is thermally oxidized at a high temperature of 1000 ° C. or more to form a gate insulating film SiO 2, and then a gate electrode (a refractory metal such as Mo is laminated on the gate insulating film). Structure) and ion implantation using the gate electrode as a mask to form source / drain regions in a self-aligned manner (self-line), thereby forming a thin film transistor. Thereafter, electrodes and wirings connected to the source / drain regions and wirings connected to the gate electrode are formed as necessary. Al is used for these electrodes and wirings, but is not limited thereto. Further, in the case where there is a concern about melting of Al by laser irradiation in the subsequent process, a metal having a melting point higher than that of Al (that is not melted by laser irradiation in the subsequent process) may be used.
[0127]
Next, an ultraviolet curable adhesive is applied on the thin film transistor (film thickness: 100 μm), and a large transparent glass having a length of 200 mm × width of 300 mm × thickness of 1.1 mm is applied to the coating film. After bonding the substrates (soda glass, softening point: 740 ° C., strain point: 511 ° C.), the adhesive was cured by irradiating ultraviolet rays from the glass substrate side, and these were bonded and fixed.
[0128]
Next, Xe-Cl excimer laser (wavelength: 308 nm) was irradiated from the quartz substrate side to cause separation (in-layer separation and interface separation) in the separation layer. The energy density of the irradiated Xe-Cl excimer laser was 250 mJ / cm @ 2, and the irradiation time was 20 nsec. Excimer laser irradiation includes spot beam irradiation and line beam irradiation. In the case of spot beam irradiation, spot irradiation is performed on a predetermined unit region (for example, 8 mm × 8 mm), and this spot irradiation is 1 / of the unit region. Irradiate while shifting by about 10 steps. In the case of line beam irradiation, irradiation is performed while shifting a predetermined unit area (for example, 378 mm × 0.1 mm or 378 mm × 0.3 mm (these are areas where 90% or more of energy is obtained)) by about 1/10. I will do it. Thereby, each point of the separation layer is irradiated at least 10 times. This laser irradiation is performed while shifting the irradiation region with respect to the entire surface of the quartz substrate.
[0129]
Thereafter, the quartz substrate and the glass substrate (transfer body) were peeled off at the separation layer, and the thin film transistor and the intermediate layer formed on the quartz substrate were transferred to the glass substrate side.
[0130]
Thereafter, the separation layer attached to the surface of the intermediate layer on the glass substrate side was removed by etching, washing, or a combination thereof. Further, the same treatment was performed on the quartz substrate and it was reused.
[0131]
If the glass substrate serving as the transfer body is a substrate larger than the quartz substrate, the transfer from the quartz substrate to the glass substrate as in the present embodiment is repeatedly performed in different areas in a plane, and on the glass substrate, More thin film transistors than the number of thin film transistors that can be formed on a quartz substrate can be formed. Furthermore, it can be repeatedly stacked on a glass substrate to form more thin film transistors.
[0132]
(Example 2)
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was an amorphous silicon film containing 20 at% of H (hydrogen).
[0133]
Note that the amount of H in the amorphous silicon film was adjusted by appropriately setting conditions during film formation by the low pressure CVD method.
[0134]
(Example 3)
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was a ceramic thin film (composition: PbTiO3, film thickness: 200 nm) formed by a sol-gel method by spin coating.
[0135]
Example 4
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was a ceramic thin film (composition: BaTiO3, film thickness: 400 nm) formed by sputtering.
[0136]
(Example 5)
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was a ceramic thin film (composition: Pb (Zr, Ti) O3 (PZT), film thickness: 50 nm) formed by laser ablation.
[0137]
(Example 6)
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was a polyimide film (thickness: 200 nm) formed by spin coating.
[0138]
(Example 7)
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was a polyphenylene sulfide film (film thickness: 200 nm) formed by spin coating.
[0139]
(Example 8)
The thin film transistor was transferred in the same manner as in Example 1 except that the separation layer was an Al layer (film thickness: 300 nm) formed by sputtering.
[0140]
Example 9
The thin film transistor was transferred in the same manner as in Example 2 except that a Kr-F excimer laser (wavelength: 248 nm) was used as the irradiation light. The energy density of the irradiated laser was 250 mJ / cm @ 2, and the irradiation time was 20 nsec.
[0141]
(Example 10)
The thin film transistor was transferred in the same manner as in Example 2 except that an Nd-YAIG laser (wavelength: 1068 nm) was used as the irradiation light. The energy density of the irradiated laser was 400 mJ / cm @ 2, and the irradiation time was 20 nsec.
[0142]
(Example 11)
A thin film transistor was transferred in the same manner as in Example 1 except that a thin film transistor having a polysilicon film (film thickness: 80 nm) formed by a high temperature process of 1000 ° C. was used as the transfer layer.
[0143]
(Example 12)
The thin film transistor was transferred in the same manner as in Example 1 except that a transparent substrate made of polycarbonate (glass transition point: 130 ° C.) was used as the transfer body.
[0144]
(Example 13)
The thin film transistor was transferred in the same manner as in Example 2 except that a transparent substrate made of AS resin (glass transition point: 70 to 90 ° C.) was used as the transfer body.
[0145]
(Example 14)
The thin film transistor was transferred in the same manner as in Example 3 except that a transparent substrate made of polymethyl methacrylate (glass transition point: 70 to 90 ° C.) was used as the transfer body.
[0146]
(Example 15)
The thin film transistor was transferred in the same manner as in Example 5 except that a transparent substrate made of polyethylene terephthalate (glass transition point: 67 ° C.) was used as the transfer body.
[0147]
(Example 16)
A thin film transistor was transferred in the same manner as in Example 6 except that a transparent substrate made of high-density polyethylene (glass transition point: 77 to 90 ° C.) was used as the transfer body.
[0148]
(Example 17)
The thin film transistor was transferred in the same manner as in Example 9 except that a transparent substrate made of polyamide (glass transition point: 145 ° C.) was used as the transfer body.
[0149]
(Example 18)
The thin film transistor was transferred in the same manner as in Example 10 except that a transparent substrate made of an epoxy resin (glass transition point: 120 ° C.) was used as the transfer body.
[0150]
(Example 19)
The thin film transistor was transferred in the same manner as in Example 11 except that a transparent substrate made of polymethyl methacrylate (glass transition point: 70 to 90 ° C.) was used as the transfer body.
[0151]
In each of Examples 1 to 19, when the state of the transferred thin film transistor was visually observed with the naked eye and a microscope, there was no defect or unevenness, and the transfer was performed uniformly.
[0152]
【The invention's effect】
As described above, according to the peeling method of the present invention, it can be easily and reliably peeled regardless of the properties, conditions, etc. of the object to be peeled (transferred layer). Transfer to various transfer bodies is possible. For example, transfer to thin materials that cannot be directly formed or are not suitable for forming, materials that are easy to mold, materials that are inexpensive, or large objects that are difficult to move Can form it.
[0153]
In particular, the transfer body may be one having inferior characteristics such as heat resistance and corrosion resistance as compared with the substrate material, such as various synthetic resins and glass materials having a low melting point. Therefore, for example, when manufacturing a liquid crystal display in which a thin film transistor (especially polysilicon TFT) is formed on a transparent substrate, a quartz glass substrate having excellent heat resistance is used as the substrate, and various synthetic resins and low melting points are used as the transfer body. By using a transparent substrate made of an inexpensive and easy-to-process material such as a glass material, a large and inexpensive liquid crystal display can be easily manufactured. Such advantages are not limited to the liquid crystal display, and the same applies to the manufacture of other devices.
[0154]
In addition, while receiving the advantages as described above, a transfer layer such as a functional thin film is formed and patterned on a highly reliable substrate, particularly a substrate having high heat resistance such as a quartz glass substrate. Therefore, a highly reliable functional thin film can be formed on the transfer body regardless of the material characteristics of the transfer body.
[0155]
In addition, such a highly reliable substrate is expensive, but it can be reused, thereby reducing the manufacturing cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing steps of an embodiment of a peeling method of the present invention.
FIG. 2 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
FIG. 3 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
FIG. 4 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
FIG. 5 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
FIG. 6 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
FIG. 7 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
FIG. 8 is a cross-sectional view showing the steps of an embodiment of the peeling method of the present invention.
[Explanation of symbols]
1 Substrate
11 Separation layer forming surface
12 Irradiation light incident surface
2 Separation layer
2a, 2b interface
3 middle class
4 Transfer target layer
5 Adhesive layer
6 Transcript
7 Irradiation light

Claims (7)

In a thin film device transfer method for transferring a transfer layer including a thin film device formed on a translucent substrate to a transfer body,
A first step of forming a separation layer with amorphous silicon in a predetermined pattern on the translucent substrate;
A second step of forming the transferred layer including a thin film transistor which is the thin film device on the separation layer;
A third step of bonding a transfer layer including the thin film device to the transfer body via an adhesive layer;
Irradiating light to the separation layer from the translucent substrate side to cause peeling in the layer and / or interface of the separation layer, and transferring the transferred layer to the transfer body;
A fifth step of removing the separation layer adhering to the light-transmitting substrate after the transfer so that the light-transmitting substrate can be reused;
Equipped with,
The transfer body is composed of a material having a glass transition point (Tg) or a softening point equal to or lower than Tmax, where Tmax is a maximum temperature in forming the transfer layer,
The substrate, when said maximum temperature in formation of the transfer layer was Tmax, the transfer method of the thin film device according to claim Rukoto strain point consists of more materials Tmax. In the transfer method of the thin film device according to claim 1,
A method for transferring a thin film device, wherein the transfer layer is directly formed on the separation layer. In the transfer method of the thin film device according to claim 1,
A method for transferring a thin film device, wherein the transfer layer is formed on the separation layer via an intermediate layer. In the transfer method of the thin film device according to any one of claims 1 to 3 ,
A transfer method for a thin film device, wherein the transfer body is made of a glass substrate, and the substrate is made of quartz. In the transfer method of the thin film device according to any one of claims 1 to 4 ,
The separation of the separation layer is caused by the disappearance or reduction of the bonding force between atoms or molecules of the substance constituting the separation layer. In the transfer method of the thin film device according to any one of claims 1 to 5 ,
The method for transferring a thin film device, wherein the separation layer is formed by CVD (Chemical Vapor Deposition). A device manufacturing method comprising the step of transferring a thin film device by the transfer method of a thin film device according to any one of claims 1 to 6 .

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