Circuit using three-dimensional wiring and method for fabricating the same

Abstract

To suppress a defective electric connection from being caused and contact resistance from increasing between surface-side wiring and three-dimensional wiring of a film substrate.SOLUTION: In a pixel circuit 1 which drives a switching TFT 50, a driving TFT 51 and a light-emitting element 57 formed on a top surface side of a film substrate 101 using three-dimensional wiring 63 connecting a reverse-surface electrode 110 as reverse surface-side wiring of the film substrate 101 and a signal line 10 as top surface-side wiring, a scanning line 53, a ground line 54, and a power supply line 55, a contact electrode 11 which partially expands the width of the signal line 10 is formed halfway on the signal line 10 as an electrode for connecting the three-dimensional wiring 63. Consequently, the contact electrode 11 that the signal line 10 comprises can make the signal line 10 partially wider in width than a through hole 62 where the three-dimensional wiring 63 is formed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0004]

[0001] The present invention relates to a circuit for driving a TFT (Thin Film Transistor) using three-dimensional wiring and a method for manufacturing the same.

Background Art

[0002] Conventionally, a tiling display configured by arranging a plurality of panel units side by side is known (see, for example, Non-Patent Documents 1 and 2). The tiling display has the advantage of being able to realize various sizes, shapes, and aspect ratios.

[0003] However, in the case of a general panel unit, it is necessary to form signal wirings and the like on the peripheral portion thereof, and it is difficult to eliminate the frame (bezel) provided on the peripheral portion. Therefore, when panel units are arranged side by side to form a tiling display, there is a problem that the seams between the panel units become conspicuous due to the bezels.

[0004] In order to solve this problem, a structure is assumed in which signal wirings and the like are taken out to the back side of the panel unit using three-dimensional wiring through through-holes. With this structure, it becomes unnecessary to form signal wirings and the like on the peripheral portion of the panel unit, a bezel-less panel unit can be realized, and seamless and inconspicuous tiling becomes possible.

[0005] As an element technology for realizing such a bezel-less panel unit, a TFT (three-dimensional wiring TFT) that can be driven by three-dimensional wiring through through-holes from the back side of a film substrate using an ultra-thin polyimide (PI) film substrate has been developed (see, for example, Non-Patent Document 3).

[0006] FIG. 6 is a schematic diagram showing a cross-sectional structure of a circuit including a conventionally three-dimensionally-wirable TFT. This circuit 100 has a laminated structure in which an underlayer film 105, an insulating film 104, a protective film 102, etc. are formed on the front side of a film substrate 101, and a planarization layer 106, etc. are formed on the back side.

[0007] Furthermore, in this circuit 100, a gate electrode 107 is formed above the underlayer 105, a source electrode 108 and a drain electrode 109 are formed above the insulating film 104 and the semiconductor layer 103, and back surface electrodes 110-1, 110-2, and 110-3 are formed below the planarization layer 106.

[0008] Furthermore, the circuit 100 is provided with through-holes 111-1, 111-3 that pass through (penetrate) the insulating film 104, the base film 105, the film substrate 101, and the planarization layer 106, and through-hole 111-2 that passes through the base film 105, the film substrate 101, and the planarization layer 106.

[0009] Three-dimensional wiring 112-1 is formed in the through-hole 111-1 for electrically connecting the drain electrode 109 and the back electrode 110-1, three-dimensional wiring 112-2 is formed in the through-hole 111-2 for electrically connecting the gate electrode 107 and the back electrode 110-2, and three-dimensional wiring 112-3 is formed in the through-hole 111-3 for electrically connecting the source electrode 108 and the back electrode 110-3.

[0010] The back electrodes 110-1, 110-2, and 110-3 are collectively referred to as back electrode 110, the through holes 111-1, 111-2, and 111-3 are collectively referred to as through holes 111, and the three-dimensional wiring 112-1, 112-2, and 112-3 are collectively referred to as three-dimensional wiring 112.

[0011] Figure 7 shows the arrangement of each element constituting a conventional pixel circuit, and illustrates the arrangement of each element as seen from the surface side of the film substrate 101 when the circuit 100 shown in Figure 6 is applied to a pixel circuit for driving a light-emitting element.

[0012] This pixel circuit 100' is equipped with three light-emitting elements 57, and a switching TFT 50, a driving TFT 51, a holding capacitor 52, and a signal line 56 are formed corresponding to each of the three light-emitting elements 57, while a scan line 53 and a ground line 54 common to all three light-emitting elements 57 are formed. Vias 60 are also formed on the electrodes of the holding capacitor 52, the driving TFT 51, and the light-emitting elements 57.

[0013] Referring to Figures 6 and 7, in the pixel circuit 100', in order to drive the switching TFT 50 and driving TFT 51 (corresponding to the TFT shown in the dotted frame in Figure 6) and the light-emitting element 57 formed on the surface side of the film substrate 101 using three-dimensional wiring 112, it is necessary to electrically connect the scanning line 53, ground line 54, power line 55, and signal line 56 and the corresponding back electrode 110 of each of these lines using three-dimensional wiring 112 formed in through holes 111 that penetrate from the back side to the front side of the film substrate 101.

[0014] Here, the scan line 53, ground line 54, power line 55, and signal line 56 are surface-side wiring formed on the surface side of the film substrate 101, and the back electrode 110 is back-side wiring formed on the back side of the film substrate 101. [Prior art documents] [Non-patent literature]

[0015] [Non-Patent Document 1] D. Nakamura et al., SID 2015 DIGEST, pp.1031-1034 (2015) [Non-Patent Document 2] G. Biwa et al., SID 2019 DIGEST, pp.121-124 (2019) [Non-Patent Document 3] H.Tsuji et al., Proceedings of the 28th International Display Workshops (IDW '21), p.143 (2021) [Overview of the Initiative] [Problems that the invention aims to solve]

[0016] As mentioned above, in the pixel circuit 100' shown in Figure 7, in order to drive the switching TFT 50, the driving TFT 51, and the light-emitting element 57 from the back side of the film substrate 101, it is necessary to electrically connect the front-side wiring and the back-side wiring using the three-dimensional wiring 112 formed in the through-hole 111 shown in Figure 6.

[0017] Here, when a display is constructed using multiple pixel circuits 100' as shown in Figure 7, the area per pixel decreases as the display resolution increases. Consequently, in order to reduce the area per pixel, it is necessary to narrow the width of the scan line 53, ground line 54, power line 55, and signal line 56 in the pixel circuit 100'.

[0018] However, narrowing the width of these wires can lead to electrical connection problems between these wires and the three-dimensional wiring 112, resulting in increased contact resistance. This problem is particularly likely to occur with signal lines 56, as their width is narrower than that of scan lines 53, ground lines 54, and power lines 55.

[0019] Figure 8 illustrates the width of the signal line 56 and the width of the through-hole 111 in the conventional pixel circuit 100' shown in Figure 7. The width (diameter) of the through-hole 111 is constant regardless of the display resolution (generally 10 μm or less), and is set to 10 μm here.

[0020] (1) shows an example where the width of signal line 56-1 is greater than or equal to the diameter of the through hole 111. (2) shows an example where the wiring width of signal line 56-1 shown in (1) becomes narrower as the resolution of the display increases, that is, where the width of signal line 56-2 is narrower than the diameter of the through hole 111.

[0021] As shown in (2), when the width of the signal line 56-2 is smaller than the diameter of the through hole 111, an electrical connection failure occurs between the signal line 56-2 and the three-dimensional wiring 112 formed in the through hole 111, resulting in a problem of increased contact resistance.

[0022] Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a circuit and a method for manufacturing the same that can suppress the occurrence of electrical connection failures and an increase in contact resistance between the surface-side wiring and the three-dimensional wiring of a film substrate.

Means for Solving the Problems

[0023] In order to solve the above problems, the circuit according to claim 1 is a circuit that drives a TFT formed on a film substrate using three-dimensional wiring, and includes a surface-side wiring formed on the surface side of the film substrate, a back-side wiring formed on the back side of the film substrate, a three-dimensional wiring formed in a through hole passing from the back side to the surface side of the film substrate for connecting the surface-side wiring and the back-side wiring, and a TFT formed on the surface side of the film substrate and driven from the back side of the film substrate by the surface-side wiring via the three-dimensional wiring from the back-side wiring, wherein the surface-side wiring As the resolution of the display configured using the said circuit increases, the width of the surface wiring is narrowed, and in the middle of the longitudinal strip having a width narrower than the through-hole, the width is greater than or equal to the width of the through-hole. includes a contact electrode that is partially widened, and the three-dimensional wiring formed in the through hole is connected to the contact electrode.

[0024] Further, the circuit according to claim 2 is characterized in that, in the circuit according to claim 1, the width of the contact electrode is set to a predetermined value that is equal to or greater than the width of the through hole.

[0025] Further, the circuit according to claim 3 is characterized in that, in the circuit according to claim 2, the width of the contact electrode is set to a predetermined value of 10 μm or more.

[0026] Further, the circuit according to claim 4 is characterized in that, in the circuit according to claim 1, the contact electrode is formed of a metal laminated film containing molybdenum.

[0027] Furthermore, the circuit of claim 5 is characterized in that, in the circuit of claim 1, the surface wiring is integrally formed from the same material as the contact electrode.

[0028] Furthermore, the circuit of claim 6 is characterized in that, in the circuit of claim 1, the surface wiring consists of a signal line, a scan line, a power line, and a ground line, and the signal line among the surface wiring is equipped with the contact electrode.

[0029] Furthermore, the manufacturing method of claim 7 is a method for manufacturing a circuit that drives a TFT formed on a film substrate by three-dimensional wiring, comprising: a first step of forming a base film on the surface side of the film substrate; a second step of forming a metal laminated film on the base film to form the gate electrode, scan line, ground line and power line of the TFT; a third step of forming an insulating film on the surface side of the base film, the gate electrode, scan line, ground line and power line of the TFT; a fourth step of forming a semiconductor layer on the insulating film; and a metal laminated film on the surface side of the insulating film and the semiconductor layer to form the source electrode and drain electrode of the TFT and the power line. The process includes a fifth step of forming the signal lines, a sixth step of forming a protective film on the surface side of the insulating film, the semiconductor layer, the source and drain electrodes of the TFT, and the signal lines, a seventh step of forming a planarization layer on the back side of the film substrate, an eighth step of forming through holes from the back side to the front side of the film substrate, and a ninth step of forming the three-dimensional wiring in the through holes and forming back wiring for connecting to the gate electrode, source and drain electrodes of the TFT, the scan lines, the ground lines, the power lines, and the signal lines via the three-dimensional wiring, wherein the fifth step, when forming the signal lines, As the resolution of the display configured using the said circuit is increased, the width of the signal line is narrowed, and in the middle of the longitudinal strip having a width narrower than the through-hole, the width is greater than or equal to the width of the through-hole. The method is characterized by forming a partially widened contact electrode, and by step 9, connecting the three-dimensional wiring formed in the through hole to the contact electrode. [Effects of the Invention]

[0030] As described above, according to the present invention, it is possible to suppress the occurrence of electrical connection failures and the increase in contact resistance between the surface wiring and three-dimensional wiring of the film substrate. [Brief explanation of the drawing]

[0031] [Figure 1] (1) is a diagram showing an example of the arrangement of each element in a pixel circuit according to an embodiment of the present invention, as viewed from the surface side of the film substrate. (2) is a magnified view of the contact electrode formed on the signal line. [Figure 2] (1) is a diagram showing an example of the arrangement of each element in a pixel circuit according to an embodiment of the present invention, as viewed from the back side of the film substrate. (2) is a magnified view of the contact electrodes and through holes formed on the signal lines in a pixel circuit according to an embodiment of the present invention. (3) is a magnified view of the signal lines and through holes in a conventional pixel circuit. [Figure 3] This figure illustrates an example of the process for manufacturing a pixel circuit according to an embodiment of the present invention. [Figure 4] This diagram explains the continuation of Figure 3. [Figure 5] This figure shows a micrograph of an embodiment of the pixel circuit. [Figure 6] This is a schematic diagram showing the cross-sectional structure of a circuit including a TFT that can be driven by conventional three-dimensional wiring. [Figure 7] This diagram shows the arrangement of each element that makes up a conventional pixel circuit. [Figure 8] This diagram illustrates the width of signal lines and through-holes in a conventional pixel circuit. [Modes for carrying out the invention]

[0032] The embodiments for carrying out the present invention will be described in detail below with reference to the drawings. The present invention is a circuit that drives a TFT formed on the surface side of a film substrate by three-dimensional wiring connecting the surface wiring and the back wiring, characterized in that the surface wiring is provided with a contact electrode whose width is partially widened, and the three-dimensional wiring is connected to the contact electrode.

[0033] This allows the width of the surface-side wiring to be partially wider than the width of the through-hole where the three-dimensional wiring is formed, in the contact electrodes provided on the surface-side wiring. Therefore, it is possible to suppress the occurrence of electrical connection failures and an increase in contact resistance between the surface-side wiring and the three-dimensional wiring.

[0034] [Pixel circuit configuration] First, the configuration of the pixel circuit according to an embodiment of the present invention will be described. Figure 1(1) is a diagram showing an example of the arrangement of each element in the pixel circuit according to an embodiment of the present invention as viewed from the surface side of the film substrate 101, and shows the circuit formed on the surface side of the film substrate 101. Figure 1(2) is a magnified view of the contact electrode formed on the signal line.

[0035] Note that Figure 1(1) shows only the components related to the present invention, and components unrelated to the invention have been omitted. The same applies to Figure 2(1), which will be described later.

[0036] This pixel circuit 1, similar to the circuit 100 shown in Figure 6, has a laminated structure in which a base film 105, insulating film 104, and protective film 102 are formed on the front side of a film substrate 101, and a planarization layer 106 is formed on the back side. It is composed of a switching TFT 50, a driving TFT 51, a holding capacitor 52, front-side wiring (scanning line 53, ground line 54, power line 55, and signal line 10), a light-emitting element 57, back-side wiring (back electrode 110), and three-dimensional wiring 63 formed in through holes 62.

[0037] Note that Figure 1(1) shows an example of the arrangement of each element as viewed from the front side of the film substrate 101, and therefore the back side wiring (back side electrodes 110), the three-dimensional wiring 63 formed in the through holes 62, etc. are not shown.

[0038] The pixel circuit 1 has three light-emitting elements (LEDs in this example) 57 on the surface side of the film substrate 101. Each of the three light-emitting elements 57 is provided with a switching TFT 50 and a driving TFT 51 corresponding to the TFT (dotted outline) shown in Figure 6, as well as a holding capacitor 52 and a signal line 10. The pixel circuit 1 also has a scan line 53, a ground line 54, and a power line 55 common to all three light-emitting elements 57.

[0039] The central squares of the switching TFT 50 and the driving TFT 51 represent the semiconductor layer 103. The signal line 10 is connected to the source electrode 108 of the switching TFT 50, and the scan line 53 also serves as the gate electrode 107 of the switching TFT 50.

[0040] Furthermore, vias 60 are formed on the electrodes of the holding capacitance 52, the driving TFT 51, and the light-emitting element 57. The vias 60 of the driving TFT 51 electrically connect the ground line 54 to the electrodes of the driving TFT 51, and the vias 60 of the light-emitting element 57 electrically connect the power line 55 to the electrodes of the light-emitting element 57.

[0041] In the pixel circuit 1, in order to drive the switching TFT 50, the driving TFT 51, and the light-emitting element 57 provided on the surface side of the film substrate 101, the surface side wiring and the back side wiring are electrically connected by three-dimensional wiring 63 (see Figure 2, described later) formed in through holes 62 that penetrate from the back side to the front side of the film substrate 101.

[0042] Furthermore, in the pixel circuit 1, a contact electrode 11 is integrally formed at a predetermined location along the longitudinal direction of the strip-shaped signal line 10. In other words, the signal line 10 is equipped with a contact electrode 11. Also, as shown in Figure 1(2), the contact electrode 11 has a protrusion 61 that partially widens the width of the signal line 10. The contact electrode 11 is an electrode for three-dimensional wiring 63, which is not shown.

[0043] Although not shown in Figure 1(1), the film substrate 101 used in the pixel circuit 1 is, for example, a polyimide (PI) substrate, and various resin (plastic) substrates can be used depending on the application.

[0044] Figure 2(1) is a diagram showing an example of the arrangement of each element in the pixel circuit 1 according to the embodiment of the present invention shown in Figure 1, as viewed from the back side of the film substrate 101, and shows the circuit formed on the back side of the film substrate 101. Figure 2(2) is an enlarged view of the contact electrode 11 and through hole 62 formed on the signal line 10 in the pixel circuit 1 according to the embodiment of the present invention, and Figure 2(3) is an enlarged view of the signal line 56 and through hole 111 in the conventional pixel circuit 100' shown in Figure 7.

[0045] Note that the arrangement example shown in Figure 2(1) is viewed from the back side of the film substrate 101, so the left and right orientation of each element is reversed compared to the arrangement example shown in Figure 1(1). Also, the back electrode 110 (see Figure 6) formed on the back side of the film substrate 101 is omitted. The three-dimensional wiring 63 formed in the through hole 62 is connected to the back electrode 110.

[0046] In the pixel circuit 1, the signal line 10 is provided with a contact electrode 11 whose width is partially widened. The contact electrode 11 is integrally formed with the signal line 10 at a predetermined location along the longitudinal direction of the strip-shaped signal line 10. As shown in Figure 2(2), the contact electrode 11 has a protrusion 61 which is a partially widened portion of the signal line 10, and a three-dimensional wiring 63 formed in a through hole 62 is connected to it.

[0047] In the conventional technology shown in Figure 2(3), the width of the signal line 56 is narrower than the width of the through hole 111. In contrast, in the embodiment of the present invention shown in Figure 2(2), the width of the signal line 10 in the contact electrode 11 is greater than or equal to the width of the through hole 62.

[0048] Furthermore, similar to the signal line 10, the strip-shaped scan line 53, ground line 54, and power line 55 are connected to the three-dimensional wiring 63 formed in the through hole 62.

[0049] As a result, the signal line 10, scan line 53, ground line 54, and power line 55 provided on the front side of the film substrate 101 are electrically connected to the back electrode 110 (not shown) provided on the back side of the film substrate 101 by three-dimensional wiring 63 formed in the through hole 62. This allows the switching TFT 50, driving TFT 51, and light-emitting element 57 provided on the front side of the film substrate 101 to be driven.

[0050] [Method for fabricating pixel circuit 1] Next, a method for manufacturing the pixel circuit 1 according to an embodiment of the present invention will be described. Figure 3 is a diagram illustrating an example of the manufacturing process for the pixel circuit 1 according to the embodiment of the present invention shown in Figures 1 and 2, and Figure 4 is a diagram illustrating a continuation of Figure 3.

[0051] First, a PI film substrate 101 with a thickness of 10 μm is formed on the first glass substrate (first glass substrate), and a silicon nitride film with a thickness of 50 nm is formed on the film substrate 101 (on the surface side of the film substrate 101) by sputtering as an undercoat 105 (step P301).

[0052] Next, a 140 nm thick metal multilayer film composed of molybdenum alloy and aluminum is formed on the underlayer film 105 (on the surface side) by sputtering. Then, the gate electrode 107 of the switching TFT 50, the gate electrode 107 of the driving TFT 51, the scan line 53, the ground line 54, and the power line 55 are formed by a photolithography process (step P302).

[0053] Next, a 200 nm thick insulating film 104, composed of silicon oxide, is formed on the undercoat 105, the gate electrode 107 of the switching TFT 50, the gate electrode 107 of the driving TFT 51, the scanning line 53, the ground line 54, and the power line 55 (on the surface side) using a sputtering apparatus (step P303).

[0054] Next, a 30 nm thick semiconductor layer (active layer) 103 composed of In-Sn-Zn-O(ITZO) is deposited on the insulating film 104 using a sputtering apparatus, and a pattern is formed by a photolithography process (step P304).

[0055] Next, a hot plate is used to perform a heat treatment at 300°C for 1 hour in the atmosphere (step P305) to form vias 60 by dry etching (step P306).

[0056] Next, a 170 nm thick metal multilayer film composed of gold, molybdenum alloy, and aluminum is formed on the insulating film 104 and the semiconductor layer 103 (on the surface side) by sputtering. Then, the source electrode 108 and drain electrode 109 of the switching TFT 50, the source electrode 108 and drain electrode 109 of the driving TFT 51, the signal line 10 (including the contact electrode 11), and the contact electrode for the light-emitting element 57 are formed by a photolithography process (step P401).

[0057] In step P401, the contact electrode 11 is formed as part of the signal line 10, simultaneously with and integrally with the signal line 10.

[0058] Next, a protective film 102 is formed on the insulating film 104, the semiconductor layer 103, the source electrode 108 and drain electrode 109 of the switching TFT 50, the source electrode 108 and drain electrode 109 of the driving TFT 51, the signal line 10, and the contact electrode for the light-emitting element 57 (on the surface side) using a coating-compatible organic film. Then, a heat treatment is performed in air at 150°C for 1 hour (step P402).

[0059] Next, a second glass substrate (second glass substrate) is attached to the protective film 102 using an adhesive layer (fix film) (step P403). After that, the first glass substrate is peeled off by laser lift-off (step P404).

[0060] Next, after peeling off the first glass substrate in step P404, a planarization layer 106 is formed on the back side of the film substrate 101 using a coating-compatible organic film, and heat treatment is performed in air at 150°C for 1 hour (step P405).

[0061] Next, through holes 62 are formed by dry etching (step P406), and three-dimensional wiring 63 and back wiring (back electrode 110) made of molybdenum alloy are formed (step P407).

[0062] Finally, the second glass substrate and the adhesive layer (fix film) are peeled off (step P408).

[0063] This makes it possible to fabricate a pixel circuit 1 using three-dimensional wiring 63. In addition, in step P406, the through holes 62 may be formed by wet etching, laser drilling, or other methods in addition to dry etching.

[0064] [Examples] Next, an embodiment of the pixel circuit 1 shown in Figures 1 and 2 will be described. Figure 5 is a micrograph of the embodiment of the pixel circuit 1 shown in Figure 1.

[0065] This micrograph shows an example of the arrangement of a pixel circuit 1 fabricated on a 10 μm thick PI film substrate 101, as viewed from the surface side of the film substrate 101, as shown in Figure 1. Note that the surrounding area, including the light-emitting element 57, is omitted from the micrograph as it is not part of the image.

[0066] The signal line 10 formed on the surface side of the film substrate 101 is composed of a four-layer laminated film in which gold with a thickness of 30 nm, molybdenum alloy with a thickness of 20 nm, aluminum with a thickness of 100 nm, and molybdenum alloy with a thickness of 20 nm are stacked in that order from top to bottom.

[0067] The width of the signal line 10 (the width of the area excluding the contact electrode 11) is approximately 6 μm, which is narrower than the typical width of a through hole 62, which is 10 μm.

[0068] Furthermore, a contact electrode 11 with a width of approximately 17 μm is formed at a predetermined location along the longitudinal direction of the signal line 10.

[0069] This allows the width of the signal line 10 at the contact electrode 11 to be sufficiently wider than the width of the through hole 62. As a result, the problems of electrical connection failure between the signal line 10 and the three-dimensional wiring 63 formed in the through hole 62, and the increase in contact resistance can be solved.

[0070] Therefore, the three-dimensional wiring 63 ensures that the signal lines 10 on the front surface of the film substrate 101 and the back surface electrodes 110 on the back surface of the film substrate 101 are electrically and reliably connected.

[0071] Furthermore, the width of the contact electrode 11 provided on the signal line 10 must be greater than or equal to the width of the through hole 62 in order to suppress the occurrence of electrical connection failures and the increase in contact resistance. If the width of the through hole 62 is 10 μm, then the width of the contact electrode 11 is preferably 10 μm or greater.

[0072] As described above, according to the pixel circuit 1 of the embodiment of the present invention, in a pixel circuit 1 that drives a switching TFT 50, a driving TFT 51 and a light-emitting element 57 formed on the surface side of a film substrate 101 using three-dimensional wiring 63 that connects the back electrode 110, which is the back side wiring of the film substrate 101, and the signal line 10, scan line 53, ground line 54 and power line 55, which are the front side wiring, a contact electrode 11 is formed in the middle of the signal line 10, which is an electrode for connecting the three-dimensional wiring 63 and partially widens the width of the signal line 10.

[0073] This allows the width of the signal line 10 to be partially wider than the width of the through-hole 62 in which the three-dimensional wiring 63 is formed, in the contact electrode 11 provided on the signal line 10.

[0074] Therefore, it is possible to suppress the occurrence of electrical connection failures and increases in contact resistance between the signal line 10 and the three-dimensional wiring 63.

[0075] Furthermore, the width of all the surface-side wirings of the film substrate 101—signal lines 10, scan lines 53, ground lines 54, and power lines 55—can be made wider than the width of the through-holes 62. As a result, the three-dimensional wiring 63 can reliably connect the surface-side wiring and the back-side wiring of the film substrate 101 electrically.

[0076] In other words, the switching TFT 50, driving TFT 51, and light-emitting element 57 formed on the front side of the film substrate 101 can be reliably driven from the back side of the film substrate 101.

[0077] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above embodiments and can be modified in various ways without departing from the technical concept.

[0078] In the above embodiment, an example of a pixel circuit 1 comprising a switching TFT 50, a driving TFT 51, and a light-emitting element 57 was described, but the present invention is applicable not only to pixel circuits 1 but also to circuits other than pixels. In short, the present invention is applicable to circuits that drive TFTs formed on a film substrate 101 by three-dimensional wiring 63.

[0079] Furthermore, in the above embodiment, a contact electrode 11 is formed at a predetermined location along the longitudinal direction of the signal line 10 to partially widen the width of the signal line 10. In contrast, a contact electrode 11 may be formed at a predetermined location along the longitudinal direction of the scan line 53 to partially widen the width of the scan line 53. Alternatively, a contact electrode 11 may be formed in the middle of the ground line 54 to partially widen its width, or a contact electrode 11 may be formed in the middle of the power line 55 to partially widen its width.

[0080] Furthermore, in the above embodiment, as shown in step P401 of Figure 4, the contact electrode 11 is formed simultaneously with and integrally with the signal line 10. In this case, the materials of the signal line 10 and the contact electrode 11 are the same: gold, molybdenum alloy, and aluminum.

[0081] In contrast, the contact electrode 11 may be formed in a separate process from the signal line 10 and using a different material. Specifically, after forming the signal line 10, the contact electrode 11 is formed using a different material from the signal line 10, such that it has the protrusion 61 shown in Figure 1(2) at a predetermined location along the longitudinal direction of the signal line 10. As a result, a contact electrode 11 with a partially widened width is formed at a predetermined location along the longitudinal direction of the signal line 10.

[0082] Furthermore, in the above embodiment, as shown in step P401 of Figure 4, the contact electrode 11 is formed from a metal multilayer film of gold, molybdenum alloy, and aluminum. However, this is just one example, and it may be formed from a multilayer film of other metals containing molybdenum. For example, the contact electrode 11 may be formed from a multilayer film of molybdenum plus one or more metals from among gold, silver, copper, and aluminum. By including molybdenum, it is possible to form a contact electrode 11 that is resistant to oxidation and has stable properties. [Explanation of symbols]

[0083] 1,100 pixel circuit 10,56 signal line 11 Contact electrodes 50 Switching TFTs 51 Driving TFT 52 Holding capacity 53 scan lines 54 Ground Line 55 Power line 57 Light-emitting element 60 Beer 61 Convex part 62,111 through holes 63,112 3D wiring 100 circuits 101 Film substrate 102 Protective film 103 Semiconductor layer 104 Insulating film 105 Undercoat 106 Planarization layer 107 Guard Post 108 Source Electrode 109 Drain electrode 110 Backside electrode

Claims

1. In a circuit that drives TFTs formed on a film substrate using three-dimensional wiring, Surface wiring formed on the surface side of the film substrate, The back side wiring formed on the back side of the film substrate, The three-dimensional wiring is formed in a through hole that passes from the back side to the front side of the film substrate, and is used to connect the front-side wiring and the back-side wiring. The film substrate comprises a TFT formed on the surface side and driven from the back side of the film substrate by the surface side wiring via the three-dimensional wiring from the back side wiring, The circuit is characterized in that the surface wiring has a strip-shaped longitudinal section with a width narrower than the through-hole when the width of the surface wiring is narrowed in accordance with the increase in resolution of the display configured using the circuit, and is partially widened to be greater than or equal to the width of the through-hole, and the three-dimensional wiring formed in the through-hole is connected to the contact electrode.

2. In the circuit described in claim 1, A circuit characterized in that the width of the contact electrode is set to a predetermined value greater than or equal to the width of the through hole.

3. In the circuit described in claim 2, A circuit characterized in that the width of the contact electrode is set to a predetermined value of 10 μm or more.

4. In the circuit described in claim 1, The circuit is characterized in that the contact electrode is formed of a metal multilayer film containing molybdenum.

5. In the circuit described in claim 1, The circuit is characterized in that the surface wiring is integrally formed from the same material as the contact electrodes.

6. In the circuit described in claim 1, The surface-side wiring consists of signal lines, scan lines, power lines, and ground lines. The circuit is characterized in that the signal line among the surface-side wiring is equipped with the contact electrode.

7. In a method for fabricating a circuit that drives TFTs formed on a film substrate by three-dimensional wiring, The first step is to form an underlayer on the surface side of the film substrate, A second step involves forming a metal laminated film on the aforementioned underlayer to form the gate electrode, scan line, ground line, and power line of the TFT, A third step involves forming an insulating film on the surface side of the undercoat, the gate electrode of the TFT, the scanning line, the ground line, and the power line. A fourth step involves forming a semiconductor layer on the insulating film, A fifth step involves forming a metal multilayer film on the surface side of the insulating film and the semiconductor layer to form the source electrode and drain electrode of the TFT, as well as the signal line. A sixth step involves forming a protective film on the surface side of the insulating film, the semiconductor layer, the source electrode and drain electrode of the TFT, and the signal line. A seventh step involves forming a planarization layer on the back side of the film substrate, An eighth step involves forming a through hole that runs from the back side to the front side of the film substrate, The ninth step involves forming the three-dimensional wiring in the through-hole, and forming back-side wiring via the three-dimensional wiring to connect to the gate electrode, source electrode and drain electrode of the TFT, the scan line, the ground line, the power line, and the signal line. The fifth step is, When forming the signal line, if the width of the signal line is narrowed in accordance with the increase in resolution of the display configured using the circuit, a contact electrode is formed in the middle of the longitudinal strip, which has a width narrower than the through hole, and is partially widened to be greater than or equal to the width of the through hole. A manufacturing method characterized in that, by the ninth step, the three-dimensional wiring formed in the through hole is connected to the contact electrode.

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