JP2007288080A - Flexible electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible electronic device capable of suppressing cracks to be generated in transfer, improving durability against the bending stress of the device to be acquired, and having excellent indication quality and electric characteristics. <P>SOLUTION: This flexible electronic device is provided with a substrate having flexibility, a thin film element layer including a semiconductor layer, an insulating layer, and a conductive layer on the substrate. In this electronic device, at least one part of each of the layers constituting the thin film element layer has a patterned slit or a hole. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flexible electronic device, and more particularly, to a flexible electronic device that suppresses cracks that occur during transfer and improves resistance to bending stress of the resulting device.

A flexible electronic device is a device in which a thin film transistor is mounted on a plastic substrate, and application to electronic paper, an IC card, an IC tag, and the like has been studied by taking advantage of its flexibility.
For example, an electrophoretic display sheet (so-called EPD display device) in which an electrophoretic element is formed on a plastic transparent substrate is a flexible display device using electrophoresis in which particles dispersed in a solvent move by application of voltage. Compared to LCD (liquid crystal display), it is easier to process and handle, and is expected to be used for portable devices and information devices.

As a manufacturing method of a flexible electronic device, for example, a method of transferring a thin film device layer formed on an inorganic substrate to a flexible substrate has been proposed (Patent Document 1).
Japanese Patent Laid-Open No. 10-125931

However, when the process of transferring the thin film device layer to the flexible substrate or bending the obtained device, the internal stress generated by thermal stress or bending stress is not released, and stress concentration occurs locally, cracks and wiring patterns There is a problem that disconnection is caused.
These are differences in thermal expansion coefficient and Young's modulus between each layer in thin film device layers composed of inorganic insulating layers, organic insulating layers, amorphous layers, metal layers, etc., and thermal expansion coefficients between flexible substrates and thin film device layers. It is thought that this is due to the difference in Young's modulus. For example, when transferring a thin film device layer by thermocompression bonding, thermal stress is applied to the entire device, and undulation may occur around the pattern formed of a member having a high thermal expansion coefficient due to the difference in thermal expansion coefficient of each layer. is there.
Further, there is a problem that a crack generated from one place easily propagates through the inorganic insulating layer and spreads over the entire thin film device layer. In particular, cracks tend to occur and propagate easily in an inorganic insulating layer having a high Young's modulus.

  Therefore, the present invention suppresses cracks that occur when a thin film device layer is transferred to a flexible substrate, etc., and improves resistance to bending stress of the obtained device, and has excellent display quality and electrical characteristics. The purpose is to provide.

  The present invention is (1) a flexible electronic device comprising a flexible substrate and a thin film element layer including a semiconductor layer, an insulator layer and a conductive layer on the substrate, and the thin film element layer is configured. At least a portion of each of the layers has a patterned slit or hole; (2) the slit is along a direction in which a current of the semiconductor layer and / or the conductor layer flows. The flexible electronic device according to the above (1), which is formed; (3) the flexible electronic device according to the above (1), wherein at least a part of each layer constituting the thin film element layer forms a network by having the holes. (4) The conductive layer is a gate electrode and a source / drain electrode constituting a thin film transistor, and the gate electrode and the source / drain electrode The flexible electronic device according to any one of (1) to (3), wherein at least a part has a patterned slit or hole; (5) the semiconductor layer and the gate electrode on the substrate; The flexible electronic device according to (4), wherein an insulating film stack including the pattern is formed, and the source / drain electrodes are formed on the insulating film stack; (6) the gate electrode and the The gate electrode and / or the source / drain electrode is formed discontinuously in a pattern in at least a part of the source / drain electrode and does not have a function as a driving circuit, and a symbol, an alignment mark, or The flexible electronic device according to (4), which has a display function as a scrub line.

In the present invention, “patterned slits or holes” means that two or more slits or holes are regularly provided in at least a part of each layer constituting the thin film element layer.
“At least part of each layer constituting the thin film element layer” means that a slit or a hole may be formed only in any one of the layers constituting the thin film element layer, or formed in all the layers. May be. Moreover, the slit or the hole may be formed only in a part of each layer constituting the thin film element layer, or may be formed over all the layers.

  “Flexible electronic devices” include displays, televisions, electronic books, electronic papers, wristwatches, electronic notebooks, calculators, mobile phones, personal digital assistants, etc., equipped with display units that use electrophoretic materials. IC cards, IC tags, and moreover, for example, flexible paper / film-like objects, those belonging to real estate such as wall surfaces to which these objects are attached, vehicles, flying objects, ships and other moving objects Including those that belong.

According to the present invention, since at least a part of the thin film element layer including the semiconductor layer, the insulator layer, and the conductive layer has the patterned slits or holes, the thin film device layer can be flexible without impairing the function as the wiring. When the step of transferring to the substrate or the obtained device is bent, the internal stress can be released and the stress concentration can be relaxed. As a result, the occurrence of cracks or the destruction of the drive circuit of the device can be suppressed, and the transfer yield and the reliability after manufacture can be improved.
Moreover, even if a crack occurs in one place, it can be prevented from propagating to the surroundings.

  The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. The present invention can be implemented in various forms without departing from the gist thereof.

(First embodiment)
FIGS. 1-12 is a figure explaining the structure and manufacturing process of a flexible electronic device which concern on Embodiment 1. FIGS.

  As shown in FIG. 1, a separation layer 120 is formed on a flexible substrate 100, a base insulating film 142 is formed thereon, and semiconductor layer patterns 143b and 143c are formed thereon.

  The flexible substrate 100 is made of resin, for example.

  The separation layer 120 is preferably made of a-Si (amorphous silicon). Alternatively, the separation layer 120 may be made of various oxide ceramics such as silicon oxide or silicate compound, titanium oxide or titanate compound, zirconium oxide or zirconate compound, lanthanum oxide or lanthanum oxide compound, PZT, PLZT, PLLZT, PBZT, etc. It may be made of ceramics or dielectric (ferroelectric), nitride ceramics such as silicon nitride, aluminum nitride and titanium nitride, organic polymers, alloys and the like.

The separation layer 120 can be formed by, for example, CVD methods (MOCVD, low pressure CVD, ECR-CVD, etc.), CVD, vapor deposition, molecular beam vapor deposition (MB), sputtering, ion plating, PVD and other various gas phase film formation methods, Various plating methods such as electroplating, immersion plating (dipping), electroless plating, Langmuir ProJet (LB) method, spin coating, spray coating, roll coating and other coating methods, various printing methods, transfer methods, inkjet methods, Performed by powder jet method or the like.
When the separation layer 120 is made of amorphous silicon, it is preferably formed by a CVD method, and when the separation layer 120 is made of ceramics or an organic polymer, it is preferably formed by spin coating. .

The formation of the base insulating film 142 is performed by, for example, a CVD method. The base insulating film 142 is preferably made of SiO ₂ or Si ₃ N ₄ .
The semiconductor layer patterns 143b and 143c are formed by first depositing a-Si on the base insulating film 142 by a CVD method or the like, and then annealing by irradiating laser light from above to recrystallize the a-Si layer. To obtain a polysilicon layer. Next, the polysilicon layer is patterned to obtain semiconductor layer patterns 143b and 143c made of polysilicon islands.

  Next, as shown in FIG. 2, source / drain regions are formed. The mask layer 171 masks the entire semiconductor layer pattern 143c and a part of the semiconductor layer pattern 143b. For example, phosphorus is ion-implanted in a high concentration (n +) source into a region to be an n-type TFT of the semiconductor layer pattern 143b. An n + layer 144 that is a drain region (HDD region) is formed.

Next, as shown in FIG. 3, a gate insulating film 153 made of, for example, SiO _{2 is} formed on the base insulating film 142 and the semiconductor layer patterns 143b and 143c by, for example, a CVD method.

  Next, as shown in FIG. 4, a pattern of the gate electrode 152 having the slits S patterned using a predetermined mask is formed on the gate insulating film 153. For the gate electrode 152, a metal such as aluminum or tantalum, or a material such as polysilicon can be used.

  FIG. 11A is a view of the gate electrode 152 as viewed from above. As shown in FIG. 11A, the gate electrode 152 has a patterned slit S. Since the slits S are patterned, the gate electrode 152 can maintain an electrically equivalent state. The slit S is formed along the direction in which a current flows in the gate electrode 152.

As described above, since the gate electrode 152 has the patterned slit S, the process of transferring the thin film device layer to the flexible substrate or the like without bending the function as the wiring or the obtained device is bent. Stress can be released and stress concentration can be relaxed. As a result, the occurrence of cracks or the destruction of the drive circuit of the device can be suppressed, and the transfer yield and the reliability after manufacture can be improved. Moreover, even if a crack occurs in one place, it can be prevented from propagating to the surroundings.
The effect of the present invention is particularly remarkable in an electrode having a large area whose width exceeds 100 μm. The width of the slit S is preferably 10 μm.

  Another configuration example of the gate electrode 152 includes a configuration in which the patterned slits S as shown in FIG. 11B are formed along the direction of current flow, and the patterning as shown in FIG. A configuration having a patterned hole C, a configuration having a mesh shape by forming a patterned hole C as shown in FIG. 11D, and a configuration having a patterned hole C as shown in FIG. It may be.

  Another example of the configuration of the gate electrode 152 may be a configuration having a comb-like shape by having a patterned slit S as shown in FIG. Note that the slit configuration shown in FIGS. 11A and 11B, in which the slit S is formed along the direction in which the current flows, is preferable to this example because the electrically equivalent state can be maintained.

  Further, as shown in FIG. 4, the semiconductor layer pattern 143c is masked by the mask layer 172, and, for example, phosphorus is ion-implanted at a low concentration into a predetermined region of 143b, and a low concentration (n−) source / drain region (LDD) is formed. Region) is formed.

  Next, as shown in FIG. 5, using the mask layer 173 and the gate electrode 152 as a mask, for example, boron (B) ions are implanted into a predetermined region of the semiconductor layer pattern 143b to form a p + layer 146.

Next, as shown in FIG. 6, a first interlayer insulating film 147 made of, for example, SiO _{2 is formed} on the pattern of the gate insulating film 153 and the gate electrode 152 by, eg, CVD.
Further, for example, a mask made of polyimide (not shown) is patterned, and the gate insulating film 153 and the first interlayer insulating film 147 are selectively etched to form the first contact hole 157. The first contact hole 157 penetrates the gate insulating film 153 and the first interlayer insulating film 147 and reaches the semiconductor layer patterns 143b and 143c.

  Next, as shown in FIG. 7, a predetermined mask is formed on the first interlayer insulating film 147, and patterned slits S or holes as exemplified in FIGS. A source / drain electrode 158 having C is formed. A metal such as aluminum can be used for the source / drain electrode 158. Since the slits S or the holes C are patterned, the source / drain electrodes 158 can maintain an electrically equivalent state.

Thus, since the source / drain electrodes 158 have the patterned slits S or holes C, the process of transferring the thin film device layer to the flexible substrate and the obtained device are bent without impairing the function as the wiring. In this case, internal stress can be released and stress concentration can be relaxed. As a result, the occurrence of cracks or the destruction of the drive circuit of the device can be suppressed, and the transfer yield and the reliability after manufacture can be improved. Moreover, even if a crack occurs in one place, it can be prevented from propagating to the surroundings.
The effect of the present invention is particularly remarkable in an electrode having a large area whose width exceeds 100 μm. The width of the slit S is preferably 10 μm.

Next, as shown in FIG. 8, a second interlayer insulating film 160 is formed on the source / drain electrodes 158 and the exposed first interlayer insulating film 147. The second interlayer insulating film 160 may be an inorganic insulating film such as SiO ₂ or Si ₃ N _4, but is preferably made of a resin such as acrylic. By using the resin, the planarized second interlayer insulating film 160 can be easily obtained.

  Next, as shown in FIG. 9, the second interlayer insulating film 160 is etched to form a second contact hole 162 reaching the source / drain electrode 158, and the pixel electrode 161 is patterned. The pixel electrode 161 is formed using an oxide semiconductor such as ITO or a metal such as aluminum.

Next, as shown in FIG. 10A, a primary transfer substrate 163 made of a resin such as glass or acrylic is bonded onto the TFT using a water-soluble adhesive 164, and a laser is applied from the back surface of the substrate 100, for example. Irradiate light. When the laser beam is transmitted through the substrate 100 and irradiated onto the separation layer 120, peeling occurs in the layer or the interface of the separation layer 120, and the thin film device becomes a primary transfer substrate 163 as shown in FIG. Is transcribed.
Preferable examples of the water-soluble adhesive 164 include epoxy-based, acrylate-based, and silicone-based adhesives.

  Then, a secondary transfer substrate (flexible substrate) made of, for example, a resin is bonded to the surface from which the substrate 100 and the separation layer 120 have been peeled off using a water-insoluble adhesive, and the entire laminate is immersed in water. Next, the transfer substrate 163 is peeled off. Since the primary transfer substrate 163 is bonded by the water-soluble adhesive 164, it can be easily peeled off.

  The resin used for the substrate 100, the primary transfer substrate 163, and the secondary transfer substrate may be either a thermoplastic resin or a thermosetting resin. For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-acetic acid. Polyolefin such as vinyl copolymer (EVA), cyclic polyolefin, modified polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polyamideimide, polycarbonate, poly- (4-methylbenten-1), ionomer, acrylic Resin, polymethyl methacrylate, acrylic-styrene copolymer (AS resin), butadiene-styrene copolymer, polio copolymer (EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), precyclohe Polyester such as terephthalate (PCT), polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM), polyphenylene oxide, modified polyphenylene oxide, polyarylate, aromatic polyester ( Liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polyvinyl chloride, polyurethane, fluororubber, chlorinated polyethylene, and other thermoplastic elastomers, epoxy resins, Phenolic resins, urea resins, melamine resins, unsaturated polyesters, silicone resins, polyurethanes, etc., or copolymers, blends, polymer alloys, etc. mainly comprising these, Chino (for example as a laminate of two or more layers) one or a combination of two or more may be used.

  Further, for example, an electrophoretic display device can be obtained by bonding a display element layer composed of a microcapsule, an ITO electrode, and a counter substrate to the obtained transfer body.

  Since the flexible electronic device of the present invention has the slit S or the hole C in which at least a part of the gate electrode 152 and / or the source / drain electrode 158 is patterned as described above, the function as the wiring is not impaired. When the thin film device layer is transferred to the flexible substrate or the obtained device is bent, the internal stress can be released and the stress concentration can be reduced. As a result, the occurrence of cracks or the destruction of the drive circuit of the device can be suppressed, and the transfer yield and the reliability after manufacture can be improved. Moreover, even if a crack occurs in one place, it can be prevented from propagating to the surroundings.

  In the above description, the case where the gate electrode 152 and the source / drain electrode 158 have the slit S or the hole C has been described. However, the present invention is not limited to this. It is good also as a structure which has a hole.

  In the above description, the case where both the gate electrode 152 and the source / drain electrode 158 have the slits S or the holes C patterned over all the electrodes has been described. Alternatively, it may be formed only on one of the source / drain electrodes 158 or may be formed only on a part of the electrode.

  In the above description, the case where the flexible electronic device is manufactured by the transfer method has been described. However, the transfer method is not limited.

  In the above description, the case where the microcapsule is used as the display element layer has been described.

  In addition, the primary transfer substrate 163 may be an independent device such as a liquid crystal cell, for example, a thin film transistor, a thin film diode, a ferroelectric thin film element, a color filter, an electrode layer, a dielectric layer, A part of the device may be configured like an insulating layer or a semiconductor element.

  In addition to TFTs, thin film devices include, for example, thin film diodes, photoelectric conversion elements (photosensors, solar cells) and silicon resistance elements composed of silicon PIN junctions, other thin film semiconductor devices, electrodes (eg, ITO, Transparent electrodes such as mesa films), actuators such as switching elements, memories, piezoelectric elements, micromirrors (piezo thin film ceramics), magnetic recording thin film heads, coils, inductors, thin film highly magnetically permeable materials, and micro magnetic devices that combine them A filter, a reflective film, a dichroic mirror, or the like may be used.

(Second Embodiment)
12A is a view of a different configuration example of the gate electrode 152 as viewed from above, and FIG. 12B is an enlarged view of a portion P in FIG.

  As shown in FIG. 12A, in the second embodiment, when the gate electrode 152 has a patterned slit S as shown in FIG. 11A, the end that does not have a function as a drive circuit is further provided. This embodiment is different from the first embodiment in that the gate electrode 152 is discontinuously formed in a pattern so that the letter E can be displayed.

As shown in the enlarged view of the part P in FIG. 12B, the letter E is composed of minute electrode patterns that are discontinuous with each other and are provided in a part of the gate electrode 152. This can be formed using a predetermined mask.
As described above, the display function as a logo is provided by forming the gate electrode 152 in a discontinuous pattern in a portion having no function as a drive circuit.

In the second embodiment, the case where the gate electrode 152 has the display function of the letter E has been described. However, the present invention is not limited to this, and the source / drain electrode 158 may have the display function.
Further, the gate electrode 152 and / or the source / drain electrode 158 may have a display function such as an alignment mark for alignment of exposure and a scrub line for cutting of the device.

FIG. 1 is a partial sectional view showing a polysilicon patterning process. FIG. 2 is a partial cross-sectional view showing an n + ion implantation process. FIG. 3 is a partial cross-sectional view showing a step of forming a gate insulating film. FIG. 4 is a partial cross-sectional view showing a gate electrode patterning and N- ion implantation process. FIG. 5 is a partial sectional view showing a p + ion implantation process. FIG. 6 is a partial cross-sectional view showing the patterning of the first contact hole and the island formation process. FIG. 7 is a partial cross-sectional view showing the patterning process of the source / drain electrodes. FIG. 8 is a partial cross-sectional view showing the formation process of the second interlayer insulating film. FIG. 9 is a partial cross-sectional view showing a pixel electrode patterning process. FIG. 10A is a partial cross-sectional view showing a primary transfer substrate bonding and laser light irradiation step, and FIG. 10B is a partial cross-sectional view showing a manufacturer substrate peeling step. FIGS. 11A to 11F are diagrams showing configuration examples of the gate electrode. FIG. 12 is a diagram showing a different configuration example of the gate electrode.

Explanation of symbols

100 substrate, 120 separation layer, 142 base insulating film, 143b, c semiconductor layer pattern, 171, 172, 173 mask layer, 144 n + layer, 145 n− layer, 146 p + layer, 153 gate insulating film, 152 gate electrode, 147 First interlayer insulating film, 157 First contact hole, 158 Source / drain electrode, 160 Second interlayer insulating film, 161 Pixel electrode, 164 Water-soluble adhesive, 163 Primary transfer substrate

Claims (6)

A flexible electronic device,
A flexible substrate;
A thin film element layer including a semiconductor layer, an insulator layer, and a conductive layer is provided on the substrate.
At least a part of each layer constituting the thin film element layer has a patterned slit or hole.   The flexible electronic device according to claim 1, wherein the slit is formed along a direction in which a current of the semiconductor layer and / or the conductor layer flows.   The flexible electronic device according to claim 1, wherein at least a part of each layer constituting the thin film element layer has a mesh shape by having the holes.   The conductive layer is a gate electrode and a source / drain electrode constituting a thin film transistor, and at least a part of the gate electrode and the source / drain electrode has a patterned slit or hole. The flexible electronic device in any one. On the substrate, an insulating film stack including a pattern of the semiconductor layer and the gate electrode is formed,
The flexible electronic device according to claim 4, wherein the source / drain electrodes are formed on the insulating film laminate.   The gate electrode and / or the source / drain electrode are discontinuously formed in a pattern in at least a part of the gate electrode and the source / drain electrode and not having a function as a drive circuit, The flexible electronic device according to claim 4, which has a display function as an alignment mark or a scrub line.

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