Transferring structure for flexible electronic device and method for fabricating flexible electronic device

This Application claims priority of Taiwan Patent Application No. 098104140, filed on Feb. 10, 2009, the entirety of which is incorporated by reference herein.

1. Field of the Invention

The present invention relates to a transferring apparatus for a flexible electronic device and method for fabricating a flexible electronic device, and in particular, to a method for debonding a flexible substrate of a flexible electronic device.

2. Description of the Related Art

Flexible displays are popularly applied to portable electronic products due to their sturdiness, light weights, and thin structures. Additionally, flexible displays provide designers with greater degrees of freedom for designing of different shapes or curvatures.

During fabrication of flexible displays, positioning and flat disposition of the flexible substrates is important for higher quality thereof. For fabricating flexible display panels, a plurality of panels is defined on a large-sized substrate. However, a drawback of the conventional fabricating process results in distortion of the flexible substrates cut therefrom, and misalignment of circuits on the flexible substrate when bonding to a flexible printed circuit (FPC) board. Specifically, a peeling problem occurs between the flexible substrates and the glass carrier.

FIG. 1 a shows a conventional flexible thin film transistor (TFT) substrate 5 disclosed in TW. Pat. No. 200806073. A 20 μm organic release film 511 is deposited on a glass carrier 6 , wherein the release film 511 can be directly separated from the glass carrier 6 . Next, an inorganic film 513 and an organic film 514 are formed on the release film 511 . An amorphous silicon or polysilicon TFTs 52 is then formed on the organic film 514 . Next, the release film 511 with TFTs 52 thereon is separated from the glass carrier 6 . A flexible TFT substrate 5 is fabricated. However, the deposition time of the release film 511 is too long to be used in the fabrication processes.

FIG. 1 b shows a conventional display disclosed in U.S. Pat. No. 2007/0091062. A plastic substrate 120 can be separated from glass carrier 122 by gasifying a α-Si release layer 124 using a laser beam 126 to scan the entire forming region of the α-Si release layer 124 . However, a slow throughput problem occurs because the scanning time increases according to increased area of the plastic substrate 120 . Additionally, when the laser beam 126 scans the α-Si release layer 124 , the laser beam 126 may pass through the plastic substrate 120 to destroy components thereon, thereby causing a low fabrication yields.

To solve the above-described problems, a transferring apparatus for a flexible electronic device and a method for fabricating a flexible electronic device are provided. An exemplary embodiment of a transferring apparatus for a flexible electronic device comprises a carrier substrate. A release layer is disposed on the carrier substrate. An adhesion layer is disposed on a portion of the carrier substrate, surrounding the release layer and adjacent to a sidewall of the release layer. A flexible electronic device is disposed on the release layer and the adhesion layer, wherein the flexible electronic device includes a flexible substrate.

An exemplary embodiment of method for fabricating a flexible electronic device is provided, comprising a carrier substrate. A release layer is formed on the carrier substrate. An adhesion layer is formed on a portion of the carrier substrate, surrounding the release layer and adjacent to a sidewall of the release layer. A flexible substrate is formed on the release layer and the adhesion layer. A flexible electronic component is formed on the flexible substrate. A debonding step is performed so that the flexible substrate is separated from the carrier substrate.

A detailed description is given in the following embodiments with reference to the accompanying drawings.

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIGS. 1 a and 1 b show a method for fabricating a conventional flexible electronic device.

FIGS. 2 a to 2 j are cross sections showing one exemplary embodiment of a flexible electronic device of the invention.

FIGS. 3 a to 3 d are cross sections showing another exemplary embodiment of a flexible electronic device of the invention, showing another debonding step of a flexible substrate separated from a carrier substrate.

FIGS. 4 a to 4 d are cross sections showing yet another exemplary embodiment of a flexible electronic device of the invention, showing a debonding step of a flexible substrate separated from a carrier substrate, wherein the adhesion layer surrounds the release layer and is adjacent to a sidewall of the release layer.

FIGS. 5 a to 5 d are cross sections showing yet another exemplary embodiment of a flexible electronic device of the invention, showing yet another debonding step of a flexible substrate separated from a carrier substrate.

The following description is of a mode for carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. Wherever possible, the same reference numbers are used in the drawings and the descriptions to refer the same or like parts.

The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto and is only limited by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual dimensions to practice of the invention.

FIGS. 2 a to 2 j are cross sections showing one exemplary embodiment of a flexible electronic device 500 a of the invention. One exemplary embodiment of a flexible electronic device may comprise a flexible electronic display, a flexible electronic touch panel, a flexible solar cell or a flexible electronic sensor. As shown in FIG. 2 a , a carrier substrate 200 is provided. In one embodiment, the carrier substrate 200 may comprise a hard substrate such as a glass substrate, a silicon substrate, a quartz substrate or a sapphire substrate. The hard substrate maintains an original shape without distortion even when moved or carried. Next, a plurality of release layers 202 are formed on the carrier substrate 200 , separated from each other by a formation method comprising vacuum evaporation or screen printing (two release layers 202 a and 202 b are shown for brevity). The number of release layers is not limited herein but dependant upon the number of the sequence of flexible electronic devices. Also, a single release layer may be formed. The release layers 202 allow the subsequently formed flexible electronic devices on the carrier substrate 200 to be separated from the carrier substrate easily. The separation method is described in the following description. In one embodiment, the release layers 202 may comprise parylene. For example, the release layers 202 may comprise RICHMOND PRODUCTS INC. release layer A5000, VAC-PAK A6200, E3760, VAC-PAK E4760 or E2760.

Next, referring to FIG. 2 b , an adhesion layer 206 is formed on a portion of the carrier substrate 200 by a formation method comprising screen printing, spatula printing, roller coating, spray printing or spin coating. As shown in FIG. 2 b , the adhesion layer 206 covers the release layers 202 a and 202 b and sidewalls 220 a and 220 b of the release layers 202 a and 202 b , wherein an area of the adhesion layer 206 is larger than a total area of the release layers 202 a and 202 b . In one embodiment, the adhesion layer 206 may comprise a material that is easily gasified by a laser beam or a material with a high adhesion force. For example, in one embodiment, the adhesion layer 206 may comprise 3-(Triethoxysilyl)-1-propanamine), epoxy resin, UV-curing resin, silicon resin or the like. In one embodiment, the adhesion layer 206 is used to bond the carrier substrate 200 to the subsequent flexible electronic device formed on the carrier substrate 200 .

Next, referring to FIG. 2 c , a flexible substrate 208 is formed on the release layers 202 a and 202 b and the adhesion layer 206 by a formation method comprising screen printing, spatula printing, roller coating, spray printing, spin coating or slot die coating. Alternatively, a fabricated flexible substrate 208 may be used to bond onto the carrier substrate 200 via an adhesion layer 206 . As shown in FIG. 2 c , the flexible substrate 208 covers the adhesion layer 206 , and the bottom of the flexible substrate 208 is connected to the top of the adhesion layer 206 . In one embodiment, the flexible substrate 208 may comprise a transparent polymer, for example, polyimide or other plastics. Additionally, in one embodiment, an adhesion force between the adhesion layer 206 and the flexible substrate 208 is larger than that between the carrier substrate 200 and the flexible substrate 208 . Thus, a transferring apparatus 600 a for a flexible electronic device is completely formed. The transferring apparatus 600 a is a structure formed during an intermediate process of forming a flexible electronic device. The transferring apparatus 600 a comprises the carrier substrate 200 , the release layer 202 formed on the carrier substrate 200 , and the adhesion layer 206 formed between a portion of the carrier substrate 200 and the flexible substrate 208 , covering the release layer 202 . The transferring apparatus 600 a is used to allow the flexible substrate to be easily separated from the carrier substrate during a subsequent debonding step.

Next, referring to FIG. 2 d , a plurality of flexible electronic components 210 separated from each other are formed in device forming regions 214 a and 214 b of the flexible substrate 208 by a semiconductor process (two flexible electronic components 210 a and 210 b are shown for brevity). The number of flexible electronic components is not limited herein but dependant upon design. Also, a single flexible electronic component may be formed. The flexible electronic components 210 a and 210 b are separated by a scribe line A 1 . In one embodiment, the flexible electronic components 210 may comprise electronic components comprising thin film transistors (TFT) or solar devices. As shown in FIG. 2 d , the device forming regions 214 are substantially directly on the release layers 202 , so that the device forming regions 214 has a projection region located inside the release layers 202 . Therefore, the flexible electronic components 210 may have a projection region located inside the release layers 202 . For example, as shown in FIG. 2 d , the flexible electronic components 210 a and 210 b have projection regions located inside the release layers 202 a and 202 b , respectively. Additionally, the scribe line A 1 is positioned in a region between the device forming regions 214 a and 214 b . Next, conductive lines 212 a and 212 b are formed on the flexible substrate 208 by a semiconductor process. The conductive lines 212 a and 212 b are electrically connected to the flexible electronic components 210 a and 210 b to provide input/output (IO) electrical connecting paths of the flexible electronic components 210 a and 210 b.

Next, referring to FIG. 2 e , a pre-cutting step is performed to cut the flexible substrate 208 , the adhesion layer 206 and the carrier substrate 200 , which are between any two adjacent flexible electronic components 210 a and 210 b and any two adjacent release layers 202 a and 202 b , in sequence along the normal line of the carrier substrate 200 , thereby separating the flexible substrate 208 , the adhesion layer 206 and the carrier substrate 200 into independent flexible electronic device quasi-structures 300 a and 300 b with a larger area. Each of the flexible electronic device quasi-structures 300 a or 300 b is a structure having a single flexible electronic component 210 a or 210 b , so that processes of bonding a flexible printed circuit board (FPC) and debonding the flexible substrate can be performed. As shown in FIG. 2 e , the flexible electronic device quasi-structure 300 a comprises a carrier substrate 200 a , a release layer 202 a , the adhesion layer 206 a , the flexible substrate 208 a , the single flexible electronic component 210 a and the conductive line 212 a . Similarly, the flexible electronic device quasi-structure 300 b comprises a carrier substrate 200 b , a release layer 202 b , the adhesion layer 206 b , the flexible substrate 208 b , the single flexible electronic component 210 b and the conductive line 212 b . It is noted that the flexible substrate 208 is connected to the carrier substrate 200 via an adhesion layer 206 , and the adhesion force between the adhesion layer 206 and the flexible substrate 208 is larger than that between the carrier substrate 200 and the flexible substrate 208 . Therefore, when performing the pre-cutting step, a peeling problem on an interface between the flexible substrate and the carrier substrate of the conventional flexible electronic device does not occur.

Next, referring to FIG. 2 f , a flexible printed circuit board (FPC) 216 a is disposed on the flexible electronic device quasi-structure 300 a by a bonding process (only one flexible electronic device quasi-structure 300 a is shown for brevity.), electrically connected to the flexible electronic component 210 a through the conductive line 212 a so that the flexible electronic component 210 a can couple to other electronic devices.

Next, referring to FIG. 2 g , a separating step may be performed using a cutting tool to cut the flexible substrate 208 a outside of the flexible electronic component 210 a and the adhesion layer 206 a covering the release layer 202 a to the release layer 202 a in sequence, along a scribe line B 1 on the normal line of the carrier substrate 200 a , thereby allowing air to enter into an interface between the adhesion layer 206 a and the release layer 202 a or an interface between the release layer 202 a and the carrier substrate 200 a . In one embodiment, the scribe line B 1 surrounds a subsequent flexible electronic device 500 a as shown in FIG. 2 h . Referring to FIG. 2 h , a cut adhesion layer 226 a is totally separated from the release layer 202 a . Next, a debonding step is performed so that a cut flexible substrate 228 a is separated from the carrier substrate 200 a . Thus, the flexible electronic device 500 a is completely formed. The flexible electronic device 500 a is separated from the carrier substrate 200 a from the release layer 202 of the transferring apparatus 600 a . The adhesion force between the adhesion layer 206 and the flexible substrate 208 is larger than that between the carrier substrate 200 and the flexible substrate 208 . Therefore, when performing the pre-cutting step, a peeling problem on an interface between the flexible substrate and the carrier substrate of the conventional flexible electronic device does not occur.

Additionally, material selection of the release layer depends on materials of the carrier substrate and the adhesion layer. Therefore, the adhesion force between the release layer and the carrier substrate may be changed. In embodiments as shown in FIG. 2 h , when the flexible substrate 228 a is separated from the carrier substrate 200 a , the release layer 202 a and the carrier substrate 200 a are bonded together. Alternatively, as shown in FIG. 2 i , when the flexible substrate 228 a is separated from the carrier substrate 200 a during the debonding step, the cut release layer 222 a may be separated from the carrier substrate 200 a . Further, as shown in FIG. 2 j , when the flexible substrate 228 a is separated from the carrier substrate 200 a during the debonding step, the cut release layer 222 a and the flexible substrate 228 a are bonded together, and a remaining release layer 222 b is on the carrier substrate 200 a.

FIGS. 3 a to 3 d are cross sections showing another exemplary embodiment of a flexible electronic device 500 b of the invention, showing another debonding step of a flexible substrate separated from a carrier substrate. Elements of the embodiments hereinafter, that are the same or similar as those previously described with reference to FIGS. 2 a to 2 j , are not repeated for brevity. As shown in FIG. 3 a , a separating step may be performed using a laser beam 230 to scan a portion of the adhesion layer 206 a adjacent to an interface between the release layer 202 a and the adhesion layer 206 a , thereby gasifying the adhesion layer 206 a , allowing air to enter into an interface between the adhesion layer 206 a and the release layer 202 a or an interface between the release layer 202 a and the carrier substrate 200 a.

Referring to FIG. 3 b , the gasified adhesion layer 206 a is separated from the release layer 202 a after performing the separating step. Next, a debonding step is performed so that the flexible substrate 208 a is separated from the carrier substrate 200 a . Thus, the flexible electronic device 500 b comprising the flexible substrate 208 a and the flexible electronic component 210 a thereon is completely formed. The separating and debonding steps using the laser beam to gasify the adhesion layer can eliminate the slow throughput problem due to a large laser scanning area of the conventional large-sized flexible electronic devices and the low yield problem due to laser beams passing thorough the flexible substrate and destroying the flexible electronic component thereon of the conventional flexible electronic devices.

In embodiment as shown in FIG. 3 b , when the flexible substrate 208 a is separated from the carrier substrate 200 a , the release layer 202 a and the carrier substrate 200 a are bonded together. Alternatively, as shown in FIG. 3 c , when the flexible substrate 208 a is separated from the carrier substrate 200 a during the debonding step, the release layer 202 a may be separated from the carrier substrate 200 a . Further, as shown in FIG. 3 d , when the flexible substrate 208 a is separated from the carrier substrate 200 a during the debonding step, the release layer 202 a and the flexible substrate 208 a are bonded together via an adhesion layer 236 a.

FIGS. 4 a to 4 d are cross sections showing yet another exemplary embodiment of a flexible electronic device 500 c of the invention, showing another transferring apparatus for a flexible electronic device 600 b . As shown in FIG. 4 a , in the transferring apparatus for a flexible electronic device 600 b , an adhesion layer 206 c surrounds the release layer 202 a , adjacent to the sidewalls 220 a and 220 b of the release layer 202 a . The flexible substrate 208 a is disposed on the adhesion layer 206 c and release layer 202 a , connecting to the adhesion layer 206 c and release layer 202 a . The carrier substrate 200 a , the release layer 202 a , adhesion layer 206 c surrounding the release layer 202 a and flexible substrate 208 a on the adhesion layer 206 c and release layer 202 a are constructed as the transferring apparatus for a flexible electronic device 600 b of the invention.

Next, referring to FIG. 4 a again, a separating step may be performed using a cutting tool to cut the flexible substrate 208 a outside of the flexible electronic component 210 a and the adhesion layer 206 a surrounding the release layer 202 a up to the carrier substrate 200 a of a flexible electronic device quasi-structure 300 c in sequence along a scribe line B 2 on the normal line of the carrier substrate 200 a , thereby allowing air to enter into an interface between the adhesion layer 206 c and the release layer 202 a or an interface between the release layer 202 a and the carrier substrate 200 a . In one embodiment, the scribe line B 2 surrounds a subsequent flexible electronic device 500 c as shown in FIG. 4 b . Referring to FIG. 4 b , a cut flexible substrate 248 a is totally separated from the release layer 202 a after performing the separating step. Next, a debonding step is performed so that the cut flexible substrate 248 a is separated from the carrier substrate 200 a , and a remaining flexible substrate 248 b and the adhesion layer 206 c are bonded together. Thus, the flexible electronic device 500 c comprising the flexible substrate 248 a and the flexible electronic component 210 a is completely formed.

In an embodiment as shown in FIG. 4 b , when the flexible substrate 248 a is separated from the carrier substrate 200 a , the release layer 202 a and the carrier substrate 200 a are bonded together. Alternatively, as shown in FIG. 4 c , when the flexible substrate 248 a is separated from the carrier substrate 200 a during the debonding step, the release layer 202 a may be separated from the carrier substrate 200 a . Further, as shown in FIG. 4 d , when the flexible substrate 248 a is separated from the carrier substrate 200 a during the debonding step, the release layer 202 a and the flexible substrate 248 a are bonded together.

FIGS. 5 a to 5 d are cross sections showing yet another exemplary embodiment of a flexible electronic device 500 d of the invention, showing yet another debonding step of a flexible substrate separated from a carrier substrate. Elements of the embodiments hereinafter, that are the same or similar as those previously described with reference to FIGS. 2 a to 2 j , 3 a to 3 d and 4 a to 4 d , are not repeated for brevity. As shown in FIG. 5 a , a separating step may be performed using a laser beam 230 to scan a portion of the adhesion layer 206 c of the flexible electronic device quasi-structure 300 c , wherein the adhesion layer 206 c is adjacent to an interface between the release layer 202 a and the adhesion layer 206 c , thereby totally gasifying the adhesion layer 206 c , allowing air to enter into an interface between the adhesion layer 206 c and the release layer 202 a or an interface between the release layer 202 a and the carrier substrate 200 a.

Referring to FIG. 5 b , the flexible substrate 208 a can be separated from the release layer 202 a after performing the separating step. Next, a debonding step is performed so that the flexible substrate 208 a is separated from the carrier substrate 200 a . Thus, the flexible electronic device 500 d comprising the flexible substrate 208 a and the flexible electronic component 210 a thereon is completely formed.

In embodiment as shown in FIG. 5 b , when the flexible substrate 208 a is separated from the carrier substrate 200 a , the release layer 202 a and the carrier substrate 200 a are bonded together. Alternatively, as shown in FIG. 5 c , when the flexible substrate 208 a is separated from the carrier substrate 200 a during the debonding step, the release layer 202 a may be separated from the carrier substrate 200 a . Further, as shown in FIG. 5 d , when the flexible substrate 208 a is separated from the carrier substrate 200 a during the debonding step, the release layer 202 a and the flexible substrate 208 a are bonded together.

The flexible electronic devices 500 a to 500 c are separated from the carrier substrate 200 from the release layer 202 of the transferring apparatus for a flexible electronic device 600 a or 600 b . The flexible electronic device 600 a or 600 b having an adhesion force between the adhesion layer 206 and the flexible substrate 208 is larger than that between the carrier substrate 200 and the flexible substrate 208 . Therefore, when performing the pre-cutting step, a peeling problem on an interface between the flexible substrate and the carrier substrate of the conventional flexible electronic device does not occur. The flexible electronic devices 500 a to 500 c have improved process stability and process yield. Also, the additional fabrication cost for the debonding step can be reduced. Further, the separating and debonding steps using the laser beam to gasify the adhesion layer can eliminate the slow throughput problem due to a huge laser scanning area of the conventional large-sized flexible electronic devices and the low yield problem due to laser beams passing thorough the flexible substrate and destroying the flexible electronic component thereon of the conventional flexible electronic devices. Moreover, one exemplary embodiment of transferring apparatus for a flexible electronic device and method for fabricating a flexible electronic device of the invention can be applied in any flexible electronic device comprising a flexible electronic display, a flexible electronic touch panel, a flexible solar cell, a flexible electronic sensor or other suitable electronic devices.

While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.