Patent Description:
One or more embodiments relate to a method of manufacturing an electronic device, and more particularly, to a method of manufacturing an electronic device, the method being capable of reducing damage and deformation of an electronic device which occur in the process of peeling off the electronic device, and manufacturing a large-area electronic device having a complex shape.

In general, when manufacturing an electronic device, an electronic device may be directly formed on a transfer target to be a component of the electronic device. However, if necessary, the electronic device may be formed on a transfer substrate and then peeled off from the transfer substrate and transferred to the transfer target.

However, when the electronic device is peeled off from the transfer substrate, the arrangement of the electronic device may be different from an initial arrangement due to the flow of a solution used for the detachment, or the electronic device may be damaged by a laser. Document <CIT> is directed at a laminating system, IC sheet, scroll of IC sheet, and a method for manufacturing an IC chip. The sealing means passes the thin film integrated circuits through the two rollers and seals the thin film integrated circuits by performing either or both of a pressure treatment and a heating treatment. A second sheet member and a resin introduced between a crimping roller and a cooling roller is cooled while applying pressure by the crimping roller and the cooling roller to bond the resin to the first surface of the thin film integrated circuits. Document <CIT> describes a thin film device supply body and a method of fabricating the same and its use in a transfer method. Irradiation light induces separation. Document <CIT> is directed to a separating method, a method for transferring a thin film device, a thin film device, a thin film integrated circuit device, and a liquid crystal display device manufactured by using the transferring method. The rear surface of the substrate is irradiated with, for example, Xe-CI excimer laser beams in order to cause internal and/or interfacial exfoliation of the separation layer. The separation layer is removed by etching. In<NPL>, Weinheim) state that "For direct transfer printing, PVP layer was coated onto the substrate by two-step spin coating at the same condition with a receive substrate. After peeling off transfer medium, finally, the devices were baked at <NUM> for <NUM>. The morphology of the Si NWs and the structure of Si NWs imbedded in PVP were observed by using field-emission scanning microscopy. Document <CIT> deals with a process for fabricating a thin film device using a transfer technique.

The invention is described in the claims. The invention provides a method of manufacturing an electronic device according to claim <NUM>. Preferred embodiments are described in the dependent claims. The embodiments which do not fall within the scope of the claims are to be interpreted as examples useful for a better understanding of the invention.

According to the invention, a method of manufacturing an electronic device includes forming a stack structure by placing a to-be-peeled layer on a substrate, applying thermal shock to the stack structure, detaching the to-be-peeled layer from the substrate, and transferring the detached to-be-peeled layer to a target substrate.

The applying of the thermal shock may include generating thermal stresses in opposite directions in the substrate and the to-be-peeled layer.

The applying of the thermal shock includes cooling the stack structure immediately after heating the stack structure.

The applying of the thermal shock includes heating the substrate until a temperature of the substrate reaches from <NUM> to <NUM>.

The applying of the thermal shock includes cooling the substrate until a temperature of the substrate reaches room temperature.

The to-be-peeled layer includes a thin film and a functional layer, wherein the forming of the stack structure includes placing the thin film on the substrate, and placing the functional layer on the thin film.

The substrate and the thin film have different thermal expansion coefficients, wherein the applying of the thermal shock includes generating shear stress at an interface between the substrate and the thin film to peel off the thin film from the substrate.

The thin film includes metal having a thermal expansion coefficient higher than a thermal expansion coefficient of the substrate.

The functional layer may include a protective layer in contact with the thin film, and an electronic element arranged on the protective layer.

The detaching of the to-be-peeled layer may include bonding a transfer layer onto the to-be-peeled layer, and detaching the to-be-peeled layer and the transfer layer bonded to each other from the substrate.

The transfer layer may include any one of polydimethyl siloxane (PDMS), heat-peeling tape, or water-soluble tape.

Other aspects, features, and advantages other than those described above will become apparent from the following detailed description, claims, and drawings.

It will be understood that although the terms "first", "second", etc. may be used herein to describe various components, these components should not be limited by these terms. The terms are only used to distinguish one component from another.

Terms used herein are for the purpose of describing particular example embodiments and are not intended to limit the present disclosure. It will be further understood that the terms "comprise", "include", and "have" used herein are intended to indicate that there is a feature, a number, a step, an operation, a component, a part, or a combination thereof described in the specification, and the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof is not precluded.

Hereinafter, one or more embodiments of the present disclosure will be described below in more detail with reference to the accompanying drawings.

<FIG> are diagrams illustrating a method of manufacturing an electronic device (hereinafter, referred to as "electronic device manufacturing method"), according to an embodiment.

Referring to <FIG>, the electronic device manufacturing method includes forming a stack structure <NUM> by placing a layer <NUM> (hereinafter, referred to as "to-be-peeled layer") to be peeled off on a substrate <NUM>, applying thermal shock to the stack structure <NUM>, detaching the to-be-peeled layer <NUM> from the substrate <NUM>, and transferring the detached to-be-peeled layer <NUM> to a transfer target <NUM>.

First, the substrate <NUM> is prepared. The material of the substrate <NUM> is not particularly limited, and a generally used silicon substrate may be used as the substrate <NUM>. The substrate <NUM> may include an opaque material. That is, in the electronic device manufacturing method according to an embodiment, a general-purpose substrate may be used as it is, and thus its utilization is high. In an embodiment, the substrate <NUM> may include a silicon substrate or a glass substrate.

Next, as shown in <FIG>, a thin film <NUM> is placed on the substrate <NUM>. The thin film <NUM> is in direct contact with the substrate <NUM> and is interposed between the substrate <NUM> and a functional layer <NUM>. Although the thickness of the thin film <NUM> is not particularly limited, as described later, the thickness of the thin film <NUM> may be several nm to several hundred nm in order for the thin film <NUM> to be easily peeled off according to a difference in the coefficient of thermal expansion between the substrate <NUM> and the thin film <NUM> when a thermal shock is applied to the stack structure <NUM>. In addition, the thickness of the thin film <NUM> may be relatively small so as to implement a flexible electronic device <NUM>. The thin film <NUM> may have a high thermal expansion coefficient and includes metal. For example, the thin film <NUM> may include any one of gold (Au), silver (Ag), and copper (Cu).

A method of placing the thin film <NUM> on the substrate <NUM> is not particularly limited, and a conventional deposition method may be applied. For example, a physical vapor deposition (PVD) method such as sputtering deposition or E-beam evaporation may be applied.

Next, as shown in <FIG>, the functional layer <NUM> is placed on the thin film <NUM>. The functional layer <NUM> may be an electronic element coated with a protective layer. The protective layer may be an insulator that protects the electronic element from a physical shock and a sudden temperature change. For example, the protective layer may include a polymer such as polyimide.

The functional layer <NUM> may be placed on the thin film <NUM> in the following manner. First, a polymer is coated as a protective layer on the thin film <NUM> placed on the substrate <NUM>. Next, a metal is deposited on the polymer and patterned. Then, a polymer is again coated to cover a metal part. However, it is not necessary to cover the metal part, and a next process may be performed in an exposed state.

The thin film <NUM> and the functional layer <NUM>, which are stacked on the substrate <NUM>, form the to-be-peeled layer <NUM>. The to-be-peeled layer <NUM> is peeled off from the substrate <NUM> by a peeling process and finally placed on the transfer target <NUM>. In addition, the substrate <NUM> and the to-be-peeled layer <NUM> form the stack structure <NUM>.

According to the electronic device manufacturing method according to an embodiment, an electronic device of nanometers to meters may be manufactured without distortion and deformation of a shape. Therefore, the sizes and shapes of the thin film <NUM> and the functional layer <NUM> are not particularly limited, and the thin film <NUM> and the functional layer <NUM> having various shapes and patterns may be used. In addition, the thin film <NUM> and the functional layer <NUM> may have shapes corresponding to each other, or the thin film <NUM> may have a larger area than the functional layer <NUM>.

In an embodiment, the substrate <NUM> and the thin film <NUM> may have different thermal expansion coefficients. For example, the thermal expansion coefficient of the thin film <NUM> may be greater than the thermal expansion coefficient of the substrate <NUM> so that, by a thermal shock, tensile stress acts on the substrate <NUM> and compressive stress acts on the thin film <NUM>.

Next, a thermal shock is applied to the stack structure <NUM>. The thermal shock causes a sudden temperature change in an object and causes a physical change in the object. In an embodiment, the thermal shock is given by heating the stack structure <NUM> and then immediately cooling the stack structure <NUM>.

First, as shown in <FIG>, the stack structure <NUM> is heated. The arrow shown in <FIG> shows a state in which heat is supplied to the stack structure <NUM> from the outside. A method of heating the stack structure <NUM> is not specifically limited. The stack structure <NUM> may be placed in a heating chamber or an oven, and then the stack structure <NUM> may be heated as a whole, the interface between the substrate <NUM> and the thin film <NUM> may be selectively heated, or a lower portion of the substrate <NUM> may be selectively heated using a hot plate or the like. In an embodiment, a hot plate may be arranged below the substrate <NUM> as a heating portion to heat the stack structure <NUM>. When the stack structure <NUM> is heated, thermal stress is generated in the substrate <NUM> and the thin film <NUM>.

Specifically, as shown in <FIG>, which is an enlarged view of an area A of FIG. 3A, when the stack structure <NUM> is heated, as the temperature of the substrate <NUM> increases, the substrate <NUM> expands to thereby generate tensile stress therein. On the other hand, since the thermal expansion coefficient of the thin film <NUM> is greater than the thermal expansion coefficient of the substrate <NUM> as described above, the thin film <NUM> has an expansion ratio greater than that of the substrate <NUM>. However, since the thin film <NUM> is in a state where the shape thereof is fixed by the substrate <NUM>, the expansion of the thin film <NUM> is restricted, and thus compressive stress is generated inside the thin film <NUM>. Therefore, as indicated by the arrow in <FIG>, thermal stresses in opposite directions occur in an upper portion of the substrate <NUM> and a lower portion of the thin film <NUM>. Accordingly, shear stress is generated at the interface between the substrate <NUM> and the thin film <NUM> in a direction parallel to the interface, thereby weakening a bonding force between the substrate <NUM> and the thin film <NUM>.

The heating process is performed until the temperature of the substrate <NUM> reaches from <NUM> to <NUM>. When the temperature of the substrate <NUM> is less than <NUM>, thermal stress is not sufficiently generated in the substrate <NUM> and the thin film <NUM>, and thus the thin film <NUM> may not be peeled off from the substrate <NUM>. On the contrary, when the temperature of the substrate <NUM> exceeds <NUM>, the functional layer <NUM> may be damaged.

The time required for the heating process depends on the materials and sizes of the substrate <NUM> and the thin film <NUM>, the characteristics of the heating portion, and the like, and is not particularly limited. For example, it may take about <NUM> minutes to heat the substrate <NUM> to <NUM> by using a hot plate as the heating portion.

Next, as shown in <FIG>, the stack structure <NUM> is cooled. The arrow shown in <FIG> shows a state in which heat is released from the stack structure <NUM> to the outside. A cooling process is carried out immediately after the heating operation is completed, in order to apply a thermal shock to the stack structure <NUM>. As in the heating process, the stack structure <NUM> may be cooled as a whole, the interface between the substrate <NUM> and the thin film <NUM> may be selectively cooled, or a lower portion of the substrate <NUM> may be selectively cooled by using a cooling portion. In an embodiment, the cooling portion may be attached to the lower portion of the substrate <NUM>. When the stack structure <NUM> is cooled, thermal stress is generated in the substrate <NUM> and the thin film <NUM>.

Specifically, as shown in <FIG>, which is an enlarged view of an area B of <FIG>, when the stack structure <NUM> is cooled, the substrate <NUM> contracts as the temperature thereof drops, and compressive stress is generated in the substrate <NUM>. On the other hand, since the thermal expansion coefficient of the thin film <NUM> is greater than the thermal expansion coefficient of the substrate <NUM> as described above, the thin film <NUM> has a shrinkage ratio greater than that of the substrate <NUM>. However, since the thin film <NUM> is in a state where the shape thereof is fixed by the substrate <NUM>, the shrinkage of the thin film <NUM> is restricted, and thus tensile stress is generated inside the thin film <NUM>. That is, in the cooling process, thermal stress is generated in the stack structure <NUM> in a direction opposite to that of the thermal stress generated in the heating process. Accordingly, in a state in which a bonding force between the substrate <NUM> and the thin film <NUM> is weakened during the heating process, shear stress is generated at the interface between the substrate <NUM> and the thin film <NUM> while the thermal stress acts in the opposite direction. As a result, fine peeling occurs from the lengthwise end of the thin film <NUM>, and the thin film <NUM> is peeled off from the substrate <NUM>. That is, the to-be-peeled layer <NUM> is peeled off from the substrate <NUM>.

The cooling portion is not particularly limited. However, in order to quickly cool the heated stack structure <NUM> and apply thermal shock thereto, a cooling plate including a material having high thermal conductivity may be attached to a lower portion of the substrate <NUM> to perform cooling. Specifically, an aluminum plate may be used as the cooling plate.

A cooling temperature in the cooling process is not particularly limited, and the substrate <NUM> is cooled until the temperature of the substrate <NUM> reaches room temperature. Alternatively, the substrate <NUM> and the thin film <NUM> may be cooled to room temperature or lower in order to reliably peel off the thin film <NUM> from the substrate <NUM>.

The time required for the cooling process depends on the materials and sizes of the substrate <NUM> and the thin film <NUM> and the characteristics of the cooling portion, and is not particularly limited. However, the time required for the cooling process may be relatively short in order to apply thermal shock to the stack structure <NUM>, and the thin film <NUM> is easily peeled off from the substrate <NUM> by cooling the substrate <NUM> to room temperature within <NUM> minute.

In addition, after the heating process and the cooling process, the thin film <NUM> does not necessarily have to be physically completely peeled off from the substrate <NUM>. That is, in the process of detaching the to-be-peeled layer <NUM> from the substrate <NUM> by using the transfer layer <NUM> as described below, it is sufficient that an adhesive force between the substrate <NUM> and the thin film <NUM> is weakened to prevent damage to the substrate <NUM> and the to-be-peeled layer <NUM>.

Next, the to-be-peeled layer <NUM> peeled off from the substrate <NUM> is detached from the substrate <NUM>. A method of detaching the to-be-peeled layer <NUM> from the substrate <NUM> is not particularly limited, but in an embodiment, the transfer layer <NUM> is bonded onto the to-be-peeled layer <NUM>, and then the to-be-peeled layer <NUM> and the transfer layer <NUM>, which are bonded to each other, may be detached from the substrate <NUM>.

First, as shown in <FIG>, the transfer layer <NUM> is bonded to the upper surface of the to-be-peeled layer <NUM>. The transfer layer <NUM> may be a member that is easily bonded to the functional layer <NUM> and is suitable for transferring the functional layer <NUM> to the transfer target <NUM>. The area of the transfer layer <NUM> may be appropriately selected in consideration of the area of the to-be-peeled layer <NUM> and may be greater than that of the to-be-peeled layer <NUM> in order to easily perform a transfer process. The transfer layer <NUM> may include any one of polydimethyl siloxane (PDMS), heat-peeling tape, or water-soluble tape.

Next, as shown in <FIG>, the transfer layer <NUM> bonded to the to-be-peeled layer <NUM> is lifted up to detach the to-be-peeled layer <NUM> from the substrate <NUM>. As described above, after the operation of applying thermal shock to the stack structure <NUM> is completed, the to-be-peeled layer <NUM> may be completely peeled from from the substrate <NUM> or the to-be-peeled layer <NUM> and the substrate <NUM> may be adhered to each other while maintaining a very weak adhesive force. In this case, a predetermined force necessary for peeling may be applied to completely detach the to-be-peeled layer <NUM> from the substrate <NUM>. In any case, after the to-be-peeled layer <NUM> is detached from the substrate <NUM> after the thermal shock is applied, the thin film <NUM> does not remain on the upper surface of the substrate <NUM>.

Next, as shown in <FIG>, the detached to-be-peeled layer <NUM> is transferred to the transfer target <NUM>. Specifically, the transfer layer <NUM> is arranged such that the lower surface of the to-be-peeled layer <NUM> (the thin film <NUM>) bonded to the transfer layer <NUM> contacts the upper surface of the transfer target <NUM>. The lower surface of the to-be-peeled layer <NUM> may be adhered to the upper surface of the transfer target <NUM>, and then the transfer layer <NUM> may be removed.

A method for removing the transfer layer <NUM> is not particularly limited. For example, when the transfer layer <NUM> includes PDMS, the upper surface of the transfer target <NUM> may include a member (e.g., polyimide, etc.) having greater adhesion than PDMS. In this case, the to-be-peeled layer <NUM> may be bonded to the transfer target <NUM>, and then the transfer layer <NUM> may be removed from the to-be-peeled layer <NUM>. In addition, when the transfer layer <NUM> includes a heat-peeling tape, the transfer layer <NUM> placed on the upper surface of the transfer target <NUM> may be heated to a predetermined temperature to peel off the transfer layer <NUM> from the to-be-peeled layer <NUM>. In addition, when the transfer layer <NUM> includes a water-soluble tape, the transfer layer <NUM> may be removed by bringing water into contact with the transfer layer <NUM>. As described above, in the electronic device manufacturing method according to the embodiment, various transfer methods may be used.

After the transfer layer <NUM> is removed, only the to-be-peeled layer <NUM> remains on the upper surface of the transfer target <NUM>. Then, the electronic device <NUM> is finally completed by attaching a commercial chip or light-emitting diode (LED) to the upper surface of the to-be-peeled layer <NUM>.

<FIG> is a diagram illustrating a partial configuration of the electronic device <NUM> manufactured by the electronic device manufacturing method according to the embodiment. More specifically, <FIG> illustrate the upper surface of the to-be-peeled layer <NUM> peeled off from the substrate <NUM>.

Referring to <FIG>, in the electronic device <NUM> manufactured by the electronic device manufacturing method according to the embodiment, even when the thin film <NUM> and the functional layer <NUM> each have the shape of a complicated pattern having a very narrow width, the distortion and deformation of the shape hardly occur.

<FIG> are X-ray photoelectron spectroscopy (XPS) analysis graphs of the electronic device <NUM> manufactured using the electronic device manufacturing method according to an embodiment.

<FIG> is a graph showing the result of XPS analysis on the lower surface of the thin film <NUM> after peeling, and <FIG> is a graph showing the result of XPS analysis on the upper surface of the substrate <NUM> after peeling. In this case, the material of the substrate <NUM> and the material of the thin film <NUM> include Si and Cu, respectively. As shown in <FIG>, almost no Si is present in the lower surface of the thin film <NUM> after peeling, and almost no Cu is present in the upper surface of the substrate <NUM> after peeling. That is, according to the electronic device manufacturing method according to the embodiment, the components of the substrate <NUM> and the thin film <NUM> are peeled off without remaining on the opposite side. Accordingly, the lower surface of the thin film <NUM> may be flat and uniform after peeling, and thus the thin film <NUM> and the transfer target <NUM> may be bonded more reliably to each other. In addition, since the component of the substrate <NUM> is not mixed with the thin film <NUM>, the electronic device <NUM> having desired physical properties may be finally obtained.

<FIG> is a diagram for comparing the electronic device manufacturing method according to the embodiment and a conventional electronic device manufacturing method.

<FIG> is a diagram illustrating an original design drawing of an electronic element, <FIG> show a to-be-peeled layer <NUM> peeled off according to the electronic device manufacturing method according to the embodiment, and <FIG> show an electronic element peeled off by a wet peeling method of a conventional electronic device manufacturing method.

Even when the electronic element has a complicated pattern as shown in <FIG>, in the to-be-peeled layer <NUM> obtained by using the electronic device manufacturing method according to the embodiment, as shown in <FIG>, wrinkles are not formed in the surface thereof and there is almost no deviation in shape as compared with the original design drawing.

On the other hand, in the case of the electronic element obtained by the wet peeling method of the conventional electronic device manufacturing method, as shown in <FIG>, wrinkles form in the electronic element and the deviation of the shape is relatively large.

This is because, since a separate solution is used to remove a sacrificial layer in the case of the wet peeling method, the placement of the electronic element is changed from an initial design due to a meniscus phenomenon, in which a solution forms a curved surface along the interface of the electronic element, or the movement of the solution, and thus the shape of the electronic element is distorted.

On the other hand, in the case of the electronic device manufacturing method according to the embodiment, since a solution is not used, the problem that the placement of the to-be-peeled layer <NUM> is deformed or distorted by the solution as shown in <FIG> does not occur.

In addition, in the case of the wet peeling method, since a solution is diffused into a sacrificial layer interposed between a substrate and an electronic element and needs to chemically react with the sacrificial layer, it takes a long time to melt the sacrificial layer for a large area substrate. The time required for the peeling process may vary depending on the materials or sizes of the substrate and the sacrificial layer, but for a large area substrate, it usually takes several hours to complete the peeling process. There is also the problem of hazards due to the use of chemical solutions.

In addition, in the case of a laser lift-off method using a laser in the conventional electronic device manufacturing method, the substrate has to include a light-transmitting material that may transmit the laser and it is expensive to construct laser equipment. In addition, since the interface between the substrate and a to-be-peeled layer is heated to a very high temperature, deformation due to high heat is inevitable. In addition, because the laser has to be concentrated in a certain area, it is not suitable for manufacturing a large-area electronic element.

On the other hand, in the electronic device manufacturing method according to the embodiment, only a time required for cooling the substrate <NUM> after heating the substrate <NUM> to a predetermined temperature is required. Thus, a to-be-peeled layer <NUM> having a large area may also be peeled off quickly, and thus there is no restriction on the sizes of the thin film <NUM> and the functional layer <NUM>, and the time required for the electronic device manufacturing process may be shortened. In addition, since the peeling process is performed within a temperature range where deformation caused by heat does not occur, deformation does not occur in the substrate <NUM> or the to-be-peeled layer <NUM>.

In addition, in the electronic device manufacturing method according to the embodiment, the peeling process is performed in a state in which the thin film <NUM> and the functional layer <NUM> are formed on the substrate <NUM>, and there is no need to additionally form a separate layer (e.g., hydrogen ion implantation layer). Thus, the process of manufacturing the electronic device <NUM> is very simple and the time and cost required for the process may be drastically reduced. In addition, a thin film <NUM> having an extremely small thickness of several nm may be used to implement a very flexible electronic device <NUM>.

The electronic device manufacturing method according to the embodiment may reduce damage to an electronic element and distortion and deformation of the electronic element, which are generated in the process of peeling off the electronic element.

In addition, the time required for peeling off the electronic element may be drastically reduced, and thus a large area electronic element having a complicated shape may be quickly manufactured.

Claim 1:
A method of manufacturing an electronic device, the method comprising:
forming a stack structure by placing a to-be-peeled layer on a substrate, wherein the to-be-peeled layer comprises a thin film and a functional layer, and wherein the thin film is placed on the substrate and the functional layer is placed on the thin film ;
applying a thermal shock to the stack structure, wherein the applying of the thermal shock comprises cooling the substrate until a temperature of the substrate reaches room temperature within <NUM> minute after heating the substrate until a temperature of the substrate reaches from <NUM> to <NUM>, and causing a sudden temperature change in the stack structure by carrying out the cooling immediately after the heating is completed;
detaching the to-be-peeled layer from the substrate; and
transferring the detached to-be-peeled layer to a target substrate, and
wherein the thin film comprises metal having a thermal expansion coefficient higher than a thermal expansion coefficient of the substrate,
wherein the applying of the thermal shock comprises generating shear stress at an interface between the substrate and the thin film to peel off the thin film from the substrate.