Thin film transistor substrate and display device comprising the same

Abstract

A thin-film transistor substrate includes: a first switching thin-film transistor located on a substrate; and a second driving thin-film transistor located on the substrate and spaced apart from the first switching thin-film transistor. The first switching thin-film transistor includes: a first active layer; a first gate electrode at least partially overlapping the first active layer; and a first light-shielding layer disposed between the substrate and the first active layer and overlapping the first active layer. The second driving thin-film transistor includes: a second active layer; a second gate electrode at least partially overlapping the second active layer; and a second light-shielding layer disposed between the substrate and the second active layer and overlapping the second active layer. Furthermore, the first and second light-shielding layers are made of different materials, and the hydrogen concentration of the second active layer is higher than that of the first active layer.

Description

[Technical Field]

[0001] This disclosure relates to an apparatus, and more specifically to a thin-film transistor substrate and a display device comprising such a thin-film transistor substrate. [Previous Technology]

[0002] Transistors are widely used in the field of electronic devices as switching or driving devices. Specifically, thin-film transistors (TFTs) are widely used as switching devices in display devices such as liquid crystal displays (LCDs) or organic light-emitting diodes (OLEDs) because they can be manufactured on glass or plastic substrates. However, TFTs for switching and TFTs for driving have different optimal characteristics. [Summary of the Invention]

[0003] Accordingly, one of the objectives of this disclosure is to overcome the differences in component characteristics between switching thin-film transistors and driving thin-film transistors.

[0004] Another object of this disclosure is to provide a thin film transistor substrate that has improved characteristics of a first thin film transistor and a second thin film transistor by providing different light-shielding layers.

[0005] Another object of this disclosure is to provide a thin-film transistor substrate, wherein the hydrogen concentration of each active layer of the first thin-film transistor and the second thin-film transistor is controlled by providing different light-shielding layers.

[0006] Another object of this disclosure is to provide a thin-film transistor substrate, wherein the threshold voltages of the first thin-film transistor and the second thin-film transistor are controlled by employing different light-shielding layers.

[0007] To achieve the aforementioned and other advantages, and in accordance with the purposes of this disclosure, as specifically implemented and broadly described herein, one aspect of this disclosure provides a thin-film transistor substrate comprising: a first switching thin-film transistor located on a base substrate; and a second driving thin-film transistor located on the base substrate and spaced apart from the first switching thin-film transistor, wherein the first thin-film transistor comprises: a first active layer; a first gate electrode at least partially overlapping the first active layer; and a first light-shielding layer disposed between the base substrate and the first active layer and overlapping the first active layer, and the second thin-film transistor comprises: a second active layer; at least partially overlapping the second active layer; and a second light-shielding layer disposed between the base substrate and the second active layer and overlapping the second active layer. Furthermore, the first light-shielding layer and the second light-shielding layer are made of different materials, and the hydrogen concentration (at %) of the second active layer is higher than that of the first active layer.

[0008] Furthermore, the atomic percentage of hydrogen concentration in the first active layer based on the overall hydrogen concentration of the first active layer can be greater than or equal to 1 x 10¹⁰ and less than 1 x 10¹⁷ atomic percentages (at %), and the atomic percentage of hydrogen concentration in the second active layer based on the overall hydrogen concentration of the second active layer is 1 x 10¹⁷ to 1 x 10²¹ atomic percentages (at %). The carrier mobility of the second active layer can be greater than that of the first active layer, and the threshold voltage of the first thin-film transistor can be greater than that of the second thin-film transistor.

[0009] Furthermore, the first light-shielding layer comprises a first metallic material, and the second light-shielding layer comprises a second metallic material. The binding energy of the first metallic material with hydrogen can be greater than the binding energy of the second metallic material with hydrogen. The first metallic material may comprise one of titanium (Ti), molybdenum-titanium alloy (MoTi), lithium (Li), hafnium (Hf), argonium (Lu), tantalum (Ta), magnesium (Mg), vanadium (V), rubidium (Rb), scandium (Sc), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), cesium (Cs), barium (Ba), and lanthanum (La). The second metallic material may comprise one of molybdenum (Mo), copper (Cu), tungsten (W), cobalt (Co), zinc (Zn), gallium (Ga), silver (Ag), cadmium (Cd), indium (In), tin (Sn), iridium (Ir), platinum (Pt), and gold (Au).

[0010] In addition, the first active layer may be disposed between the first light-shielding layer and the first gate electrode, and the second active layer may be disposed between the second light-shielding layer and the second gate electrode. The first gate electrode may be disposed between the first light-shielding layer and the first active layer, and the second gate electrode may be disposed between the second light-shielding layer and the second active layer.

[0011] Another embodiment of this disclosure provides a thin-film transistor substrate, which includes: a first thin-film transistor located on a substrate; and a second thin-film transistor spaced apart from the first thin-film transistor. Furthermore, the first thin-film transistor includes: a first active layer; and a first gate electrode disposed between the substrate and the first active layer and at least partially overlapping the first active layer. Furthermore, the second thin-film transistor also includes: a second active layer; and a second gate electrode disposed between the substrate and the second active layer and at least partially overlapping the second active layer. The first gate electrode and the second gate electrode are made of different materials, and the hydrogen concentration (at %) of the second active layer is higher than that of the first active layer (at %). The first gate electrode includes a first metal material, and the second gate electrode includes a second metal material, wherein the binding energy of the first metal material with hydrogen can be greater than the binding energy of the second metal material with hydrogen.

[0012] Another embodiment of this disclosure provides a thin-film transistor substrate, which includes: a third thin-film transistor located on a base substrate; and a fourth thin-film transistor spaced apart from the third thin-film transistor, wherein the third thin-film transistor includes a first active layer; a first gate electrode at least partially overlapping the first active layer; and a first light-shielding layer disposed between the base substrate and the first active layer and overlapping the first active layer. The fourth thin-film transistor further includes: a second active layer; a second gate electrode at least partially overlapping the second active layer; and a second light-shielding layer disposed between the base substrate and the second active layer and overlapping the second active layer. Further, the first active layer includes a first oxide semiconductor material, the second active layer includes a second oxide semiconductor material, the carrier mobility of the first oxide semiconductor material is greater than the carrier mobility of the second oxide semiconductor material, and the thickness of the first light-shielding layer is greater than the thickness of the second light-shielding layer.

[0013] The first active layer is based on a hydrogen concentration of greater than or equal to 1x10¹⁰ and less than 1x10¹⁷ atomic percentages (at %), and the second active layer is based on a hydrogen concentration of 1x10¹⁷ to 1x10²¹ atomic percentages (at %). Each of the first and second light-shielding layers comprises a first metallic material, which may comprise any one of titanium (Ti), molybdenum-titanium alloy (MoTi), lithium (Li), hafnium (Hf), argonium (Lu), tantalum (Ta), magnesium (Mg), vanadium (V), rubidium (Rb), scandium (Sc), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), cesium (Cs), barium (Ba), and lanthanum (La).

[0014] Another embodiment of this disclosure provides a display device including a thin-film transistor substrate. This display device includes: a gate driver and a pixel driving circuit, located on the substrate; a first thin-film transistor may be included in the gate driver or may serve as a switching thin-film transistor in the pixel driving circuit, and a second thin-film transistor may serve as a driving thin-film transistor in the pixel driving circuit.

[0015] The display device further includes a gate driver and a pixel driving circuit on a substrate, wherein the first thin-film transistor and the second thin-film transistor may be included in the gate driver or may be used as switching thin-film transistors in the pixel driving circuit.

[0016] The scope of the present invention will become clearer from the detailed description below. However, it should be understood that although the detailed description and specific embodiments illustrate preferred embodiments of the present invention, they are merely illustrative examples. As those skilled in the art will readily recognize from the detailed description, all variations and modifications made within the concept and scope of the present invention are included.

Implementation Method

[0018] The advantages, features, and implementation methods of this disclosure will be illustrated by the following embodiments described with reference to the accompanying drawings. However, it should be understood that this disclosure may be embodied in different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to make this disclosure more detailed and complete, and to fully convey the scope of this disclosure to those skilled in the art. Furthermore, this disclosure is defined only by the scope of the claims.

[0019] The shapes, dimensions, scales, angles, and quantities disclosed in the accompanying drawings for illustrative purposes are merely examples, and therefore, this disclosure is not limited to the details shown in the drawings. Throughout the specification, the same element symbols refer to the same elements. In the following description, detailed descriptions of related known functions or configurations will be omitted or provided only briefly when it is determined that such detailed descriptions may unnecessarily obscure the focus of this disclosure.

[0020] When using the terms "comprising," "having," and "including" as described in this specification, an additional part may be added unless "only" is used. Unless otherwise stated, singular terms may include plural forms. When interpreting an element, even without explicit description, the element is interpreted as including a tolerance range. Furthermore, when referring to any dimensions, relative sizes, or other numerical values, it should be understood that the numerical values ​​or corresponding information (e.g., levels, ranges, etc.) of an element or feature, even without explicit description, still include tolerances or error ranges that may be caused by various factors such as process factors, internal and external influences, and noise. It should also be specifically noted that the term "may" as used in this document fully encompasses the entire semantic scope of "can."

[0021] Any implementation described herein as an "example" should not necessarily be construed as superior or more advantageous than other implementations. When describing positional relationships, such as when using expressions like "above," "over," "below," and "adjacent," one or more intermediate parts may exist between two parts unless qualifiers such as "exactly" or "directly" are used.

[0022] Spatial relative terms such as “below,” “under,” “lower,” “above,” and “higher” may be used herein to facilitate the description of the relationship between one or more elements and another element or more, as illustrated in the figures. It should be understood that these terms are intended to cover different orientations of the device other than those shown in the figures. For example, if the device shown in the figures is inverted, a device described as being “below” or “under” another device could instead be described as being “above” another device. Therefore, the exemplary term “below” or “under” may include both “below” and “above” orientations. Similarly, the exemplary term “above” or “above” may include both “above” and “below” orientations.

[0023] When describing temporal relationships, such as when using temporal terms like "after," "following," "next," and "before," discontinuous situations may be included unless qualifiers such as "exactly" or "directly" are used. It should be understood that although terms such as "first" and "second" may be used herein to describe various elements, such elements should not be limited by such terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0024] It should be understood that the term "at least one" includes all combinations relating to any one item. For example, "at least one of the first element, the second element, and the third element" may include all combinations of two or more elements selected from the first, second, and third elements, as well as each single element of the first, second, and third elements. When expressed as the first element, the second element, and / or the third element, it should be understood as one of the first, second, and third elements, or any or all combinations of the first, second, and third elements. For example, A, B, and / or C may refer to: only A; only B; only C; any or some combinations of A, B, and C; or all of A, B, and C.

[0025] The technical features of the various embodiments disclosed herein can be partially or entirely coupled or combined with each other, and those skilled in the art should fully understand that these technical features can cooperate with each other in various ways and be driven by technical means. The embodiments disclosed herein can be executed independently of each other, or they can be executed jointly based on interdependence. When reference symbols are marked on the components of the various figures in the embodiments of this disclosure, the same components may be marked with the same symbols in other figures.

[0026] Unless otherwise expressly defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the exemplary embodiments pertain. It should also be understood that even terms defined in common dictionaries shall be interpreted as having a meaning consistent with the context of the relevant technical field, and shall not be interpreted in an idealized or overly formalized manner unless expressly defined herein. For example, the terms "part" or "unit" may apply to, for example, discrete circuits or structures, integrated circuits, operational blocks of circuit devices, or, as one of ordinary skill in the art would understand, any structure configured to perform the stated function.

[0027] Conversely, these embodiments are provided to make this disclosure sufficiently detailed and complete to assist those skilled in the art in fully understanding the scope of this disclosure. In the embodiments disclosed herein, source electrodes and drain electrodes are distinguished for ease of description, and source electrodes and drain electrodes are interchangeable. A source electrode can serve as a drain electrode, and vice versa. Furthermore, a source electrode in one embodiment can be a drain electrode in another embodiment, and a drain electrode in one embodiment can be a source electrode in another embodiment.

[0028] In some embodiments of this disclosure, for ease of description, the source region is distinguished from the source electrode, and the drain region is distinguished from the drain electrode; however, the embodiments of this disclosure are not limited thereto. The source region can serve as the source electrode, and the drain region can serve as the drain electrode. Furthermore, the source region can serve as the drain electrode, and the drain region can serve as the source electrode.

[0029] FIG1 is a schematic cross-sectional view of a thin-film transistor substrate 100 according to an embodiment of the present disclosure. Referring to FIG1, the thin-film transistor substrate 100 includes a first thin-film transistor TR11 and a second thin-film transistor TR12 spaced apart from each other.

[0030] Referring to FIG1, the first thin-film transistor TR11 includes a first active layer 130, a first gate electrode 150 at least partially overlapping the first active layer 130, and a first light-shielding layer 115 disposed between the substrate 110 and the first active layer 130 and overlapping the first active layer 130. Furthermore, the second thin-film transistor TR12 includes a second active layer 230, a second gate electrode 250 at least partially overlapping the second active layer 230, and a second light-shielding layer 215 disposed between the substrate 110 and the second active layer 230 and overlapping the second active layer 230.

[0031] The components of a thin-film transistor substrate 100 according to an embodiment of the present disclosure will be described in more detail below.

[0032] In particular, the substrate 110 can be made of glass or plastic, and a flexible transparent plastic (such as polyimide) can be used. When polyimide is used as the substrate 110, considering that a high-temperature deposition process needs to be performed on the substrate 110, a heat-resistant polyimide that can withstand high temperatures can be used. At this time, in order to form a thin-film transistor, deposition and etching processes can be performed simultaneously by placing the polyimide substrate on a carrier substrate made of a highly durable material (such as glass).

[0033] Referring to Figure 1, the first light-shielding layer 115 and the second light-shielding layer 215 can be disposed on the substrate 110. As shown, the first light-shielding layer 115 and the second light-shielding layer 215 can be disposed between the substrate 110 and the buffer layer 120. Furthermore, the first light-shielding layer 115 and the second light-shielding layer 215 overlap with the first active layer 130 and the second active layer 230, respectively. Specifically, the first light-shielding layer 115 and the second light-shielding layer 215 can overlap with the channel portions 130n and 230n. Moreover, the first light-shielding layer 115 and the second light-shielding layer 215 block light incident from the outside, thereby protecting the channel portions 130n and 230n.

[0034] Furthermore, the first light-shielding layer 115 and the second light-shielding layer 215 are made of different materials. Specifically, the first light-shielding layer 115 contains a first metallic material, and the second light-shielding layer 215 contains a second metallic material. More specifically, the first metallic material can be a metallic material that captures hydrogen (H), and the second metallic material can be a metallic material that does not capture hydrogen (H) or releases hydrogen (H). That is, the first metallic material can bind with hydrogen more stably than the second metallic material. For example, the second metallic material can have voids between atoms. At high temperatures, the second metallic material can contain hydrogen present in the voids between atoms. Furthermore, when the temperature decreases, the hydrogen present in the second metallic material can be released to the outside.

[0035] More specifically, the first metallic material may include any one of titanium (Ti), molybdenum-titanium alloy (MoTi), lithium (Li), hafnium (Hf), argonium (Lu), tantalum (Ta), magnesium (Mg), vanadium (V), rubidium (Rb), scandium (Sc), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), cesium (Cs), barium (Ba), and lanthanum (La). The second metallic material may include any one of molybdenum (Mo), copper (Cu), tungsten (W), cobalt (Co), zinc (Zn), gallium (Ga), silver (Ag), cadmium (Cd), indium (In), tin (Sn), iridium (Ir), platinum (Pt), and gold (Au).

[0036] Typically, there are characteristic differences between switching thin-film transistors and driving thin-film transistors. For example, as the bezel width increases, the manufacturing cost of the display device increases. In view of this problem, when the switching thin-film transistor is included in the gate driver 321 (see FIG. 5), a short channel is preferably implemented. Furthermore, to increase the current capacity in the channel of the switching thin-film transistor, a short channel is implemented.

[0037] Furthermore, for driving thin-film transistors, it is preferable to reduce the dispersion of the threshold voltage to ensure driving stability. For example, if the dispersion of the threshold voltage of the driving thin-film transistor is increased, it becomes difficult to maintain a constant threshold voltage. As a result, the reliability of the driving thin-film transistor deteriorates, leading to a decrease in the uniformity of display brightness.

[0038] Therefore, the switching thin-film transistor preferably achieves a short channel, and the driving thin-film transistor preferably achieves improved driving stability. Furthermore, by controlling the hydrogen capture performance of the light-shielding layers of the switching and driving thin-film transistors, the desired device characteristics of each can be improved simultaneously within a single panel. Specifically, by capturing hydrogen flowing into the switching thin-film transistor, the switching thin-film transistor can achieve a short channel; and by not capturing hydrogen flowing into the driving thin-film transistor, the driving stability of the driving thin-film transistor can be improved.

[0039] Therefore, a thin-film transistor substrate 100 according to an embodiment of the present disclosure includes: a first thin-film transistor TR11, which includes a first light-shielding layer 115; and a second thin-film transistor TR12, which includes a second light-shielding layer 215. In this example, the first thin-film transistor TR11 may be included in a gate driver 321 or a switching thin-film transistor, and the second thin-film transistor TR12 may be a driving thin-film transistor of a pixel driving circuit PDC.

[0040] Specifically, compared to the second light-shielding layer 215 of the second thin-film transistor TR12, the first light-shielding layer 115 of the first thin-film transistor TR11 is made of a material that is stably bonded to hydrogen. For example, compared to the second light-shielding layer 215, the first light-shielding layer 115 may be made of a material with a higher bonding energy with hydrogen.

[0041] If the first light-shielding layer 115 of the first thin-film transistor TR11, which is used as a switching thin-film transistor, is made of a metal material (e.g., a second metal material) that is unstable in bonding with hydrogen (H), then hydrogen (H) will diffuse into the first thin-film transistor TR11. Therefore, hydrogen can penetrate into the channel portion 130n of the first active layer 130, thereby causing a negative (-) shift in the threshold voltage (Vth) of the first thin-film transistor TR11, and making it difficult for the first thin-film transistor TR11 to achieve a short channel.

[0042] Therefore, since the first light-shielding layer 115 is made of a first metallic material that is stably bonded to hydrogen, hydrogen (H) can be effectively blocked. Therefore, the channel portion 130n of the first active layer 130 can be effectively protected, and the first thin-film transistor TR11 can realize a short channel.

[0043] Furthermore, if the second light-shielding layer 215 of the second thin-film transistor TR12, which serves as the driving thin-film transistor, is made of a metal material that can stably bond with hydrogen, for example, if the second light-shielding layer 215 is made of a first metal material, then hydrogen (H) will hardly diffuse into the second thin-film transistor TR12. Therefore, the threshold voltage (Vth) of the second thin-film transistor TR12 may experience a positive (+) shift. This reduces the reliability of driving the thin-film transistor, thereby causing a problem of reduced brightness uniformity in the display.

[0044] Therefore, since the second light-shielding layer 215 is made of a second metallic material that emits hydrogen (and does not capture hydrogen), the positive (+) shift of the threshold voltage (Vth) of the second thin-film transistor TR12 can be suppressed. Thus, the driving stability of the second thin-film transistor TR12 is improved.

[0045] According to one embodiment of the present invention, the threshold voltage (Vth) of the first thin-film transistor TR11 can be greater than the threshold voltage (Vth) of the second thin-film transistor TR12. At the same time, the hydrogen concentration (at %) of the second active layer 230 can be higher than the hydrogen concentration of the first active layer 130.

[0046] For example, the atomic percentage of hydrogen concentration in the first active layer 130 based on the overall hydrogen concentration of the first active layer 130 may be greater than or equal to 1 x 10¹⁰ and less than 1 x 10¹⁷ atomic percentages (at %), and the atomic percentage of hydrogen concentration in the second active layer 230 based on the overall hydrogen concentration of the second active layer 230 may be 1 x 10¹⁷ to 1 x 10²¹ atomic percentages (at %). According to one embodiment of this disclosure, the carrier mobility of the second active layer 230 may be greater than the carrier mobility of the first active layer 130.

[0047] Referring to FIG1, a buffer layer 120 may be disposed on the first light-shielding layer 115 and the second light-shielding layer 215. Specifically, the buffer layer 120 may be disposed over the entire area of ​​the first thin-film transistor TR11 and the second thin-film transistor TR12. The buffer layer 120 is also formed on the substrate 110 and may contain inorganic or organic materials. For example, the buffer layer 120 may contain insulating oxides such as silicon oxide (SiOx) or aluminum oxide (Al2O3).

[0048] Furthermore, the buffer layer 120 protects the first active layer 130 and the second active layer 230 by blocking impurities such as moisture and oxygen from flowing in from the substrate 110, and is used to flatten the upper part of the substrate 110, and can be formed as a single-layer structure or a multi-layer structure. When the buffer layer 120 has a multi-layer structure, each layer in the multi-layer structure can be formed of different materials.

[0049] Referring again to FIG1, the first active layer 130 and the second active layer 230 may be disposed on the buffer layer 120. Furthermore, the first thin-film transistor TR11 includes the first active layer 130 located on the buffer layer 120, and the second thin-film transistor TR12 includes the second active layer 230. As shown in FIG1, the first active layer 130 and the second active layer 230 are configured to be spaced apart from each other.

[0050] Furthermore, each of the first active layer 130 and the second active layer 230 may include channel portions 130n, 230n, first connection portions 130a, 230a, and second connection portions 130b, 230b. Specifically, the first active layer 130 may include: a channel portion 130n that overlaps with the first gate electrode 150 in a planar view; a first connection portion 130a that does not overlap with the first gate electrode 150 in a planar view and is connected to one side of the channel portion 130n; and a second connection portion 130b that does not overlap with the first gate electrode 150 in a planar view and is connected to the other side of the channel portion 130n.

[0051] In addition, the second active layer 230 may include: a channel portion 230n that overlaps with the second gate electrode 250 in a planar view; a first connection portion 230a that does not overlap with the second gate electrode 250 in a planar view and is connected to one side of the channel portion 230n; and a second connection portion 230b that does not overlap with the second gate electrode 250 in a planar view and is connected to the other side of the channel portion 230n.

[0052] According to one embodiment of this disclosure, the first connection portions 130a, 230a and the second connection portions 130b, 230b are spaced apart from each other, and channel portions 130n, 230n are located between the first connection portions and the second connection portions. Furthermore, the first active layer 130 and the second active layer 230 may be formed of semiconductor material and include oxide semiconductor material.

[0053] Furthermore, for example, the oxide semiconductor material may include at least one selected from the group consisting of IZO (InZnO)-based oxide semiconductor materials, IGO (InGaO)-based oxide semiconductor materials, ITO (InSnO)-based oxide semiconductor materials, IGZO (InGaZnO)-based oxide semiconductor materials, IGZTO (InGaZnSnO)-based oxide semiconductor materials, GZTO (GaZnSnO)-based oxide semiconductor materials, GZO (GaZnO)-based oxide semiconductor materials, ITZO (InSnZnO)-based oxide semiconductor materials, and FIZO (FeInZnO)-based oxide semiconductor materials. However, the embodiments disclosed herein are not limited thereto, and the first active layer 130 and the second active layer 230 may also be formed of other oxide semiconductor materials.

[0054] Furthermore, the first connection portions 130a and 230a and the second connection portions 130b and 230b can be formed by selectively conductiveizing the first active layer 130 and the second active layer 230 made of semiconductor material. According to one embodiment of this disclosure, selective conductiveizing means imparting conductivity to specific portions of the first active layer 130 and the second active layer 230, enabling these active layers to function as conductors.

[0055] For example, the first active layer 130 and the second active layer 230 can be selectively conductiveized by ion doping. Thus, first connection portions 130a and 230a and second connection portions 130b and 230b can be formed. However, the first active layer 130 and the second active layer 230 can also be selectively conductiveized by other methods.

[0056] Furthermore, the first connection portions 130a, 230a and the second connection portions 130b, 230b do not overlap with the first gate electrode 150 and the second gate electrode 250. Moreover, compared to the channel portions 130n, 230n, the first connection portions 130a, 230a and the second connection portions 130b, 230b have superior conductivity and higher mobility. Therefore, each of the first connection portions 130a, 230a and the second connection portions 130b, 230b can function as a wiring device.

[0057] According to one embodiment of the present disclosure, the first active layer 130 and the second active layer 230 may have a multilayer structure. Furthermore, the first active layer 130 and the second active layer 230 may also contain the same or similar semiconductor materials, or they may contain different semiconductor materials.

[0058] The first thin-film transistor TR11 may further include a gate insulating film 140 disposed between the first active layer 130 and the first gate electrode 150. Furthermore, the second thin-film transistor TR12 may further include a gate insulating film 240 disposed between the second active layer 230 and the second gate electrode 250. Specifically, the first connection portion 130a and the second connection portion 130b of the first active layer 130 may be exposed from the gate insulating film 140, and the first connection portion 230a and the second connection portion 230b of the second active layer 230 may be exposed from the gate insulating film 240.

[0059] Furthermore, the gate insulating films 140 and 240 may be configured to cover the entire surface of the first active layer 130 and the second active layer 230, or the gate insulating films 140 and 240 may be formed as an integral structure. The gate insulating films 140 and 240 may contain at least one selected from silicon oxide, silicon nitride, and metal oxides, and may have a single-layer film structure or a multi-layer film structure. Moreover, the gate insulating films 140 and 240 may protect the channel portions 130n and 230n.

[0060] Referring to Figure 1, the first gate electrode 150 and the second gate electrode 250 are disposed on the gate insulating films 140 and 240. As shown in the figure, the first gate electrode 150 and the second gate electrode 250 overlap with the channel portions 130n and 230n of the first active layer 130 and the second active layer 230.

[0061] Furthermore, the first gate electrode 150 and the second gate electrode 250 may be made of aluminum-based metals (e.g., aluminum (Al) or aluminum alloys), silver-based metals (e.g., silver (Ag) or silver alloys), copper-based metals (e.g., copper (Cu) or copper alloys), molybdenum-based metals (e.g., molybdenum (Mo) or molybdenum alloys), chromium (Cr), tantalum (Ta), neodymium (Nd), and titanium (Ti). The first gate electrode 150 and the second gate electrode 250 may also have a multilayer structure comprising at least two conductive films with different physical properties.

[0062] Referring to Figure 1, an interlayer insulating film 160 is disposed on the first gate electrode 150 and the second gate electrode 250. Specifically, the interlayer insulating film 160 is an insulating layer made of insulating material and may be made of organic material, inorganic material, or a laminate of organic material layers and inorganic material layers. As shown, the interlayer insulating film 160 may also be configured to cover the entire first thin-film transistor TR11 and the second thin-film transistor TR12.

[0063] Referring again to FIG1, source electrodes 171, 271 and drain electrodes 172, 272 are disposed on interlayer insulating film 160. As shown in FIG1, the first thin film transistor TR11 and the second thin film transistor TR12 respectively include source electrodes 171, 271 and drain electrodes 172, 272.

[0064] Furthermore, source electrodes 171, 271 and drain electrodes 172, 272 are disposed on gate insulating layers 140, 240. In particular, the first gate electrode 150 and the second gate electrode 250 may be disposed on the same layer as the source electrodes 171, 271 and the drain electrodes 172, 272. The first gate electrode 150 and the second gate electrode 250 may also be made of the same or similar materials and processes.

[0065] Furthermore, the source electrodes 171, 271 and drain electrodes 172, 272 may comprise at least one of the following materials: aluminum-based metals (such as aluminum (Al) or aluminum alloys), silver-based metals (such as silver (Ag) or silver alloys), copper-based metals (such as copper (Cu) or copper alloys), molybdenum-based metals (such as molybdenum (Mo) or molybdenum alloys), chromium (Cr), tantalum (Ta), neodymium (Nd), and titanium (Ti). The source electrodes 171, 271 and drain electrodes 172, 272 may also have a multilayer structure comprising at least two conductive films, each conductive film having different physical properties.

[0066] As shown in FIG1, the source electrodes 171, 271 and the drain electrodes 172, 272 are connected to the first active layer 130 and the second active layer 230 through contact holes. Specifically, the source electrodes 171, 271 and the drain electrodes 172, 272 are connected to the first active layer 130 and the second active layer 230 through contacting the first connection portions 130a, 230a and the second connection portions 130b, 230b.

[0067] Furthermore, the first active layer 130 may be disposed between the first light-shielding layer 115 and the first gate electrode 150, and the second active layer 230 may be disposed between the second light-shielding layer 215 and the second gate electrode 250. In FIG1, the first active layer 130 is shown disposed between the first light-shielding layer 115 and the first gate electrode 150, and the second active layer 230 is shown disposed between the second light-shielding layer 215 and the second gate electrode 250.

[0068] In addition, in an alternative embodiment, additional measures may be taken to increase the release of hydrogen from the driving transistor. For example, virtual vias may be formed in the driving transistor to increase hydrogen release, and an additional virtual layer may be formed using a second material.

[0069] Next, FIG2 is a cross-sectional schematic diagram of the thin film transistor substrate 200, FIG3 is a cross-sectional schematic diagram of the thin film transistor substrate 300, and FIG4 is a cross-sectional schematic diagram of the thin film transistor substrate 400 according to other embodiments of the present disclosure.

[0070] As shown in FIG2, the first gate electrode 350 may be disposed between the first light-shielding layer 315 and the first active layer 330, and the second gate electrode 450 may be disposed between the second light-shielding layer 415 and the second active layer 430. Referring to FIG2, a thin-film transistor substrate 200 according to an embodiment of the present disclosure includes a first thin-film transistor TR21 and a second thin-film transistor TR22 spaced apart from each other.

[0071] As shown in FIG2, the first thin-film transistor TR21 includes a first active layer 330, a first gate electrode 350 at least partially overlapping the first active layer 330, and a first light-shielding layer 315 disposed between the substrate 310 and the first active layer 330 and overlapping the first active layer 330. Furthermore, the second thin-film transistor TR22 includes a second active layer 430, a second gate electrode 450 at least partially overlapping the second active layer 430, and a second light-shielding layer 415 disposed between the substrate 310 and the second active layer 430 and overlapping the second active layer 430.

[0072] Furthermore, as shown in FIG2, the first gate electrode 350 may be disposed between the first light-shielding layer 315 and the first active layer 330, and the second gate electrode 450 may be disposed between the second light-shielding layer 415 and the second active layer 430. Furthermore, the first light-shielding layer 315 and the second light-shielding layer 415 are spaced apart from each other and disposed on the substrate 310, and a buffer layer 320 is disposed on the first light-shielding layer 315 and the second light-shielding layer 415. The first gate electrode 350 and the second gate electrode 450 are disposed on the buffer layer 320, and gate insulating films 340 and 440 are disposed on the first gate electrode 350 and the second gate electrode 450. Furthermore, the first active layer 330 and the second active layer 430 are disposed on the gate insulating film 440. As shown in the figure, source electrode 371 and drain electrode 372 are disposed on the first active layer 330, and source electrode 471 and drain electrode 472 are disposed on the second active layer 430. Interlayer insulating film 360 is also disposed on source electrode 371, 471 and drain electrode 372, 472.

[0073] The description of the substrate 310, first light-shielding layer 315, second light-shielding layer 415, buffer layer 320, first gate electrode 350, second gate electrode 450, gate insulating film 340, gate insulating film 440, first active layer 330, second active layer 430, source electrode 371, source electrode 471, drain electrode 372, drain electrode 472, and interlayer insulating film 360 shown in FIG. 1 is the same as the description of the substrate 110, first light-shielding layer 115, second light-shielding layer 215, buffer layer 120, first gate electrode 150, second gate electrode 250, gate insulating film 140, gate insulating film 240, first active layer 130, second active layer 230, source electrode 171, source electrode 271, drain electrode 172, drain electrode 272, and interlayer insulating film 160 shown in FIG. 2. Compared to the thin-film transistor substrate 100 in FIG1, the thin-film transistor substrate 200 in FIG2 has gate insulating films 340, 440 that are configured to cover the entire upper surface of the buffer layer 320.

[0074] Referring to FIG3, the first gate electrode 550 and the second gate electrode 650 may be made of different materials, and the hydrogen concentration (at %) of the second active layer 630 may be higher than the hydrogen concentration (at %) of the first active layer 530. In addition, the thin film transistor substrate 300 in FIG3 includes a first thin film transistor TR31 and a second thin film transistor TR32 spaced apart from each other.

[0075] In particular, compared to the thin-film transistor substrate 200 of FIG2, the thin-film transistor substrate 300 of FIG3 does not include the first light-shielding layer 315 and the second light-shielding layer 415. The description of the substrate 510, buffer layer 520, gate insulating film 540, gate insulating film 640, first active layer 530, second active layer 630, source electrode 571, source electrode 671, drain electrode 572, drain electrode 672 and interlayer insulating film 560 shown in FIG3 is the same as the description of the substrate 310, buffer layer 320, gate insulating film 340, gate insulating film 440, first active layer 330, second active layer 430, source electrode 371, source electrode 471, drain electrode 372, drain electrode 472 and interlayer insulating film 360 shown in FIG2.

[0076] Referring to Figure 3, the first gate electrode 550 and the second gate electrode 650 are made of different materials. Specifically, the first gate electrode 550 comprises a first metallic material, and the second gate electrode 650 comprises a second metallic material. More specifically, the first metallic material can be a metallic material that captures hydrogen (H), and the second metallic material can be a metallic material that does not capture or release hydrogen (H). That is, the first metallic material can bind with hydrogen more stably than the second metallic material. For example, the binding energy of the first metallic material with hydrogen can be greater than the binding energy of the second metallic material with hydrogen.

[0077] The descriptions of the first metallic material and the second metallic material are repeated from the previous descriptions. In addition, the threshold voltage (Vth) of the first thin-film transistor TR31 may be greater than the threshold voltage (Vth) of the second thin-film transistor TR32.

[0078] Furthermore, the hydrogen concentration (at %) of the second active layer 630 may be higher than that of the first active layer 530. For example, based on the entire first active layer 530, the atomic percentage of hydrogen concentration in the first active layer 530 may be greater than or equal to 1 x 10¹⁰ and less than 1 x 10¹⁷ atomic percentages (at %), and based on the entire second active layer 630, the atomic percentage of hydrogen concentration in the second active layer 630 may be between 1 x 10¹⁷ and 1 x 10²¹ atomic percentages (at %). Further, the carrier mobility of the second active layer 630 may be greater than that of the first active layer 530.

[0079] Referring to FIG4, the thin film transistor substrate 400 may include a third thin film transistor TR11a located on the substrate 110a and a fourth thin film transistor TR12a spaced apart from the third thin film transistor TR11a. The substrate 110a shown in FIG4 corresponds to the substrate 110 shown in FIG1.

[0080] Furthermore, the third thin-film transistor TR11a includes a first active layer 131, a first gate electrode 150a that at least partially overlaps with the first active layer 131, and a first light-shielding layer 115a disposed between the substrate 110a and the first active layer 131 and overlapping with the first active layer 131. As shown in the figure, the fourth thin-film transistor TR12a includes a second active layer 132, a second gate electrode 150b that at least partially overlaps with the second active layer 132, and a second light-shielding layer 115b disposed between the substrate 110a and the second active layer 132 and overlapping with the second active layer 132.

[0081] Furthermore, the first active layer 131 comprises a first oxide semiconductor material, and the second active layer 132 comprises a second oxide semiconductor material. For example, the first oxide semiconductor material may be a high-mobility material, and the second oxide semiconductor material may be a low-mobility material. In addition, the carrier mobility of the first oxide semiconductor material may be greater than the carrier mobility of the second oxide semiconductor material.

[0082] Further, as shown in Figure 4, the thickness of the first light-shielding layer 115a can be greater than the thickness of the second light-shielding layer 115b. Furthermore, each of the first light-shielding layer 115a and the second light-shielding layer 115b can contain a first metallic material. For example, the first metallic material can contain any one of titanium (Ti), molybdenum-titanium alloy (MoTi), lithium (Li), hafnium (Hf), argonium (Lu), tantalum (Ta), magnesium (Mg), vanadium (V), rubidium (Rb), scandium (Sc), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), cesium (Cs), barium (Ba), and lanthanum (La).

[0083] Furthermore, the first light-shielding layer 115a and the second light-shielding layer 115b can stably bind with hydrogen. For example, the first metallic material can be a metallic material that captures hydrogen (H). Specifically, when the thickness of the first light-shielding layer 115a is greater than the thickness of the second light-shielding layer 115b, the first light-shielding layer 115a has more space inside for capturing hydrogen than the second light-shielding layer 115b, so the first light-shielding layer 115a can bind or capture a larger amount of hydrogen than the second light-shielding layer 115b.

[0084] Even if the first oxide semiconductor material of the first active layer 131 has a higher carrier mobility than the second oxide semiconductor material of the second active layer 132, the thickness of the first light-shielding layer 115a is also greater than the thickness of the second light-shielding layer 115b, thereby controlling the hydrogen concentration of the first active layer 131. In other words, even if the first oxide semiconductor material of the first active layer 131 has a higher carrier mobility than the second oxide semiconductor material of the second active layer 132, the hydrogen concentration of the first active layer 131 as a whole is greater than or equal to 1x10¹⁰ and less than 1x10¹⁷ atomic percentages (at %), while the hydrogen concentration of the second active layer 132 as a whole can be 1x10¹⁷ to 1x10²¹ atomic percentages (at %).

[0085] Furthermore, according to one embodiment of the present disclosure, the third thin-film transistor TR11a and the fourth thin-film transistor TR12a of the thin-film transistor substrate 400 may be included in the gate driver 321 or may be switching thin-film transistors. For example, even if the first oxide semiconductor material of the first active layer 131 of the third thin-film transistor TR11a has a high carrier mobility, the hydrogen concentration in the first active layer 131 can be maintained at an atomic percentage (at %) of 1x10¹⁰ or higher and less than 1x10¹⁷ by controlling the thickness of the first light-shielding layer 115a. Therefore, the third thin-film transistor TR11a can realize a short channel and the current capacity of the third thin-film transistor TR11a can be increased.

[0086] For example, even if the carrier mobility of the second oxide semiconductor material in the second active layer 132 of the fourth thin-film transistor TR12a is low, the hydrogen concentration in the second active layer 132 can be maintained at an atomic percentage (at %) of 1x10¹⁰ or higher and less than 1x10¹⁷ by controlling the thickness of the second light-shielding layer 115b. Therefore, the fourth thin-film transistor TR12a can realize a short channel and can increase the current capacity of the fourth thin-film transistor TR12a.

[0087] Next, FIG5 is a schematic diagram of a display device 1000 according to an embodiment of the present disclosure. As shown in the figure, the display device 1000 may include a display panel 311, a gate driver 321, a data driver 331, and a control unit 341.

[0088] As shown in FIG5, the display panel 311 includes a gate line GL and a data line DL, and a pixel P disposed at the intersection of the gate line GL and the data line DL. The image is displayed by driving the pixel P, and the gate line GL, the data line DL and the pixel P can be disposed on the substrate 110.

[0089] Furthermore, the control unit 341 controls the gate driver 321 and the data driver 331. Specifically, by using signals provided by an external system, the control unit 341 outputs a gate control signal GCS for controlling the gate driver 321 and a data control signal DCS for controlling the data driver 331. In addition, the control unit 341 samples the input image data from the external system, rearranges the input image data, and provides the data driver 331 with reset digital image data RGB. The gate control signal GCS includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable signal (GOE), a start signal (Vst), and a gate clock (GCLK). Furthermore, the gate control signal GCS may include a control signal for controlling the shift register.

[0090] In addition, the data control signal DCS includes a source start pulse (SSP), a source shift clock signal (SSC), a source output enable signal (SOE), and a polarity control signal (POL). The data driver 331 provides data voltage to the data lines DL of the display panel 311. Specifically, the data driver 331 converts the image data RGB input from the control unit 341 into analog data voltage and provides the data voltage to the data lines DL.

[0091] Furthermore, the gate driver 321 can be mounted on the display panel 311. Moreover, the gate driver 321 directly mounted on the display panel 311 is referred to as a gate-in-panel (GIP) structure. Specifically, in the GIP structure, the gate driver 321 can be disposed on the substrate 110.

[0092] Furthermore, the display device 1000 may include the aforementioned thin-film transistor substrates 100, 200, 300, and 400. More specifically, the gate driver 321 may include the aforementioned thin-film transistor substrates 100, 200, 300, and 400. The gate driver 321 may also include a shift register 351.

[0093] Specifically, the shift register 351 utilizes the start signal and gate clock transmitted from the control unit 341 to sequentially provide multiple gate pulses to the gate line GL, each pulse required to provide one frame. Here, one frame refers to the time period required to output one image through the display panel 311. The gate pulse has a turn-on voltage that enables the thin-film transistors of the switching elements disposed within the pixel P to conduct.

[0094] Furthermore, during the remaining period of a frame when no gate pulse is provided, the shift register 351 supplies a gate turn-off signal capable of turning off the switching element to the gate line GL. Hereinafter, the gate pulse and the gate turn-off signal will be collectively referred to as the scan signal (SS or Scan). The shift register 351 may include the aforementioned thin-film transistor substrates 100, 200, 300, and 400.

[0095] Next, FIG6 is a circuit diagram of a pixel P in FIG5. Specifically, the circuit diagram of FIG6 is an equivalent circuit diagram of pixel P of the display device 1000, which includes an organic light-emitting diode (OLED) as a display element 710. Referring to FIG6, pixel P includes a display element 710 and a pixel driving circuit PDC that drives the display element 710. Specifically, the display device 1000 according to an embodiment of the present disclosure may include a pixel driving circuit PDC located on a substrate 110.

[0096] Furthermore, the pixel driving circuit PDC shown in FIG. 6 includes a first thin-film transistor TR1 as a switching transistor and a second thin-film transistor TR2 as a driving transistor. According to the embodiment disclosed herein, the pixel driving circuit PDC includes first thin-film transistors TR11, TR21, and TR31 as switching transistors according to the embodiment disclosed herein, and second thin-film transistors TR12, TR22, and TR32 as driving transistors according to the embodiment disclosed herein. Furthermore, the pixel driving circuit PDC may include either the third thin-film transistor TR11a or the fourth thin-film transistor TR12a shown in FIG. 4 as switching transistors.

[0097] Furthermore, the first thin-film transistor TR1 is connected to the gate line GL and the data line DL, and is turned on or off through the scan signal SS provided by the gate line GL. The data line DL provides a data voltage Vdata to the pixel driving circuit PDC, and the first thin-film transistor TR1 controls the application of the data voltage Vdata. The driving power line PL provides a driving voltage Vdd to the display element 710, and the first thin-film transistor TR1 controls the driving voltage Vdd. The driving voltage Vdd is the pixel driving voltage used to drive the organic light-emitting diode (OLED), which is the display element 710.

[0098] When the first thin-film transistor TR1 is turned on by the scan signal SS from the gate driver 321 applied through the gate line GL, the data voltage Vdata provided through the data line DL is supplied to the gate electrode of the second thin-film transistor TR2 connected to the display element 710. The data voltage Vdata charges the storage capacitor C1 formed between the gate electrode and the source electrode of the second thin-film transistor TR2. Through the second thin-film transistor TR2, the amount of current supplied to the organic light-emitting diode (OLED) that serves as the display element 710 is controlled according to the data voltage Vdata, thereby controlling the gradient of the light output by the display element 710.

[0099] Next, FIG7 is a planar schematic diagram of the pixels in FIG6, and FIG8 is a cross-sectional schematic diagram obtained along the cross-sectional line I-I' in FIG7. Referring to FIG7 and FIG8, the first thin-film transistor TR1 and the second thin-film transistor TR2 are disposed on the substrate 110. The substrate 110 may be made of glass or plastic. As the substrate 110, a plastic with flexible properties, such as polyimide (PI), can be used.

[0100] As shown in the figure, a first light-shielding layer 115 and a second light-shielding layer 215 are disposed on a substrate 110. In particular, the first light-shielding layer 115 and the second light-shielding layer 215 have light-shielding properties. Therefore, the first light-shielding layer 115 and the second light-shielding layer 215 can block light incident from the outside to protect the active layers (A1, A2).

[0101] Furthermore, as mentioned above, the first light-shielding layer 115 may contain a first metallic material, and the second light-shielding layer 215 may contain a second metallic material. Moreover, a buffer layer 120 is provided on both the first light-shielding layer 115 and the second light-shielding layer 215. More specifically, the buffer layer 120 is made of an insulating material and protects the active layers A1 and A2 from moisture or oxygen flowing in from the outside.

[0102] Furthermore, the active layer A1 of the first thin-film transistor TR1 and the active layer A2 of the second thin-film transistor TR2 are disposed on the buffer layer 120. The active layers A1 and A2 may contain, for example, an oxide semiconductor material, and may have a multilayer structure made of an oxide semiconductor material.

[0103] Furthermore, a gate insulating film 140 is disposed on the active layers A1 and A2. Moreover, the gate insulating film 140 covers the upper surface of the active layers A1 and A2. The gate electrode G1 of the first thin-film transistor TR1 and the gate electrode G2 of the second thin-film transistor TR12 are disposed on the gate insulating film 140. Furthermore, a gate line GL may also be disposed on the gate insulating film 140. The gate electrode G1 of the first thin-film transistor TR1 may extend from the gate line GL, or may be part of the gate line GL.

[0104] Referring to Figures 7 and 8, a first capacitor electrode CE1 for a storage capacitor Cst is formed on the gate insulating film 140. The first capacitor electrode CE1 may be made of the same or similar material as the gate electrodes G1 and G2, and manufactured through the same or similar processes. An interlayer insulating film 160 is disposed on the gate electrodes G1 and G2 and the first capacitor electrode CE1.

[0105] In addition, the data line DL and the drive power line PL are disposed on the interlayer insulating film 160. Furthermore, the source electrode S1 and drain electrode D1 of the first thin-film transistor TR1 are disposed on the interlayer insulating film 160, and the source electrode S2 and drain electrode D2 of the second thin-film transistor TR2 are disposed on the interlayer insulating film 160.

[0106] Furthermore, the source electrode S1 of the first thin-film transistor TR1 can be integrally formed with the data line DL, and can have a structure extending from the data line DL. The source electrode S1 of the first thin-film transistor TR1 can contact the first light-shielding layer 115 of the first thin-film transistor TR1 through the first contact hole H1. The source electrode S1 of the first thin-film transistor TR1 can contact the side of the active layer A1 of the first thin-film transistor TR1 through the second contact hole H2.

[0107] Furthermore, the drain electrode D1 of the first thin-film transistor TR1 contacts the other side of the active layer A1 of the first thin-film transistor TR1 through the third contact hole H3. Additionally, the drain electrode D1 of the first thin-film transistor TR1 is connected to the first capacitor electrode CE1 through the fourth contact hole H4. Therefore, the first capacitor electrode CE1 can be connected to the first thin-film transistor TR1.

[0108] Furthermore, the drain electrode D2 of the second thin-film transistor TR2 can be integrally formed with the driving power line PL, and can have a structure extending from the driving power line PL. The drain electrode D2 of the second thin-film transistor TR2 can contact the side of the active layer A2 of the second thin-film transistor TR2 through the seventh contact hole H7.

[0109] Furthermore, the source electrode S2 of the second thin-film transistor TR2 contacts the other side of the active layer A2 of the second thin-film transistor TR2 through the sixth contact hole H6. Additionally, the source electrode S2 of the second thin-film transistor TR2 is connected to the second light-shielding layer 215 through the fifth contact hole H5. The same voltage as the source electrode S2 of the second thin-film transistor TR2 can be applied to the second light-shielding layer 215 overlapping with the second thin-film transistor TR2. The source electrode S2 of the second thin-film transistor TR2 can extend onto the interlayer insulating film 160 to form the second capacitor electrode CE2 of the storage capacitor Cst. Furthermore, the first capacitor electrode CE1 and the second capacitor electrode CE2 can overlap to form the storage capacitor Cst.

[0110] Referring to Figures 7 and 8, a data line DL, a drive power line PL, a source electrode S1, a source electrode S2, a drain electrode D1, a drain electrode D2, and a second capacitor electrode CE2 are disposed on the planarization layer 190. Specifically, the planarization layer 190 planarizes the upper portions of the first thin-film transistor TR1 and the second thin-film transistor TR2, and protects the first thin-film transistor TR1 and the second thin-film transistor TR2. Therefore, the planarization layer 190 functions as a protective layer.

[0111] Furthermore, the first electrode 711 of the display element 710 is placed on the planarization layer 190. As shown, the first electrode 711 of the display element 710 contacts the second capacitor electrode CE2 through the eighth contact hole H8 formed in the planarization layer 180. Therefore, the first electrode 711 of the display element 710 can be connected to the source electrode S2 of the second thin-film transistor TR2. A embankment layer 750 is provided at the edge of the first electrode 711. The embankment layer 750 defines the light-emitting area of ​​the display element 710.

[0112] As shown in the figure, an organic light-emitting layer 712 is disposed on the first electrode 711, and a second electrode 713 is disposed on the organic light-emitting layer 712. Therefore, the display element 710 is completed. The display element 710 shown in Figure 8 is an organic light-emitting diode (OLED). Therefore, the display device 1000 according to an embodiment of the present invention is an organic light-emitting display device.

[0113] The pixel driving circuit PDC according to another embodiment of this disclosure can be formed in various structures other than those described above. For example, the PDC may contain three or more thin-film transistors.

[0114] Furthermore, the following beneficial effects can be obtained according to the embodiments disclosed herein. In particular, by including a first thin-film transistor and a second thin-film transistor with different light-shielding layers, the thin-film transistor substrate of one embodiment of the present disclosure can improve the device characteristics.

[0115] Furthermore, by including a first thin-film transistor and a second thin-film transistor with different light-shielding layers, the hydrogen concentration of the active layer can be controlled according to one embodiment of the present disclosure. This thin-film transistor substrate includes a first thin-film transistor and a second thin-film transistor with different light-shielding layers, thereby differentially controlling the threshold voltage, thereby increasing the current capacity of the switching transistor and improving the driving stability of the driving transistor.

[0116] The technical features of the various embodiments disclosed herein can be partially or entirely coupled or combined with each other, and those skilled in the art should fully understand that these technical features can operate on each other in various ways and be driven by technical means. The embodiments disclosed herein can be implemented independently of each other, or they can be implemented together in a mutually dependent manner.

[0117] It should be clearly understood by those skilled in the art that the content of this disclosure is not limited to the foregoing embodiments and drawings, and that various substitutions, modifications, and alterations can be made to this disclosure without departing from the technical concept or scope thereof. Therefore, the scope of this disclosure shall be determined by the appended claims, and all changes or modifications derived from the wording, scope, and equivalent concepts of the claims shall be deemed to fall within the scope of this disclosure. [Simplified Explanation of the Diagram]

[0017] The aforementioned objects, features, and advantages of this disclosure will become more apparent from the following detailed description taken in conjunction with the drawings, in which: FIG1 is a schematic cross-sectional view of a thin-film transistor substrate according to one embodiment of the present disclosure. FIG2 is a schematic cross-sectional view of a thin-film transistor substrate according to another embodiment of the present disclosure. FIG3 is a schematic cross-sectional view of a thin-film transistor substrate according to yet another embodiment of the present disclosure. FIG4 is a schematic cross-sectional view of a thin-film transistor substrate according to still another embodiment of the present disclosure. FIG5 is a schematic diagram of a display device according to an embodiment of the present disclosure. FIG6 is a circuit diagram of a pixel P in FIG5. FIG7 is a schematic plan view of a pixel in FIG6. FIG8 is a schematic cross-sectional view obtained along section line I-I' in FIG7.

Claims

1. A thin-film transistor substrate, comprising: a first switching thin-film transistor located on a substrate; and a second driving thin-film transistor located on the substrate and spaced apart from the first switching thin-film transistor, wherein the first switching thin-film transistor comprises: a first active layer; a first gate electrode at least partially overlapping the first active layer; and a first light-shielding layer disposed between the substrate and the first active layer and overlapping the first active layer; wherein the second driving thin-film transistor comprises: a second active layer; a second gate electrode at least partially overlapping the second active layer; and a second light-shielding layer disposed between the substrate and the second active layer and overlapping the second active layer, wherein the first light-shielding layer and the second light-shielding layer are made of different materials, and wherein the hydrogen concentration of the second active layer is higher than the hydrogen concentration of the first active layer.

2. The thin-film transistor substrate as claimed in claim 1, wherein the hydrogen concentration of the first active layer is greater than or equal to 1 x 10¹⁰ atomic percentages and less than 1 x 10¹⁷ atomic percentages, and wherein the hydrogen concentration of the second active layer is between 1 x 10¹⁷ atomic percentages and 1 x 10²¹ atomic percentages.

3. The thin-film transistor substrate as claimed in claim 1, wherein the carrier mobility of the second active layer is greater than that of the first active layer, and wherein the threshold voltage of the first switching thin-film transistor is greater than that of the second driving thin-film transistor.

4. The thin-film transistor substrate as claimed in claim 1, wherein the first light-shielding layer comprises a first metal material, wherein the second light-shielding layer comprises a second metal material, and wherein the binding energy of the first metal material with hydrogen is greater than the binding energy of the second metal material with hydrogen.

5. The thin-film transistor substrate as claimed in claim 4, wherein the first metallic material comprises any one of titanium, molybdenum-titanium alloy, lithium, hafnium, argon, tantalum, magnesium, vanadium, rubidium, scandium, strontium, yttrium, zirconium, niobium, cesium, barium, and lanthanum, and wherein the second metallic material comprises any one of molybdenum, copper, tungsten, cobalt, zinc, gallium, silver, cadmium, indium, tin, iridium, platinum, and gold.

6. The thin-film transistor substrate as claimed in claim 1, wherein the first active layer is disposed between the first light-shielding layer and the first gate electrode, and wherein the second active layer is disposed between the second light-shielding layer and the second gate electrode.

7. The thin-film transistor substrate as claimed in claim 1, wherein the first gate electrode is disposed between the first light-shielding layer and the first active layer, and wherein the second gate electrode is disposed between the second light-shielding layer and the second active layer.

8. A thin-film transistor substrate, comprising: a first switching thin-film transistor located on a substrate; and a second driving thin-film transistor located on the substrate and spaced apart from the first switching thin-film transistor, wherein the first switching thin-film transistor comprises: a first active layer; and a first gate electrode disposed between the substrate and the first active layer and at least partially overlapping the first active layer, wherein the second driving thin-film transistor comprises: a second active layer; and a second gate electrode disposed between the substrate and the second active layer and at least partially overlapping the second active layer, wherein the first gate electrode and the second gate electrode are made of different materials, and wherein the hydrogen concentration of the second active layer is higher than the hydrogen concentration of the first active layer.

9. The thin-film transistor substrate as claimed in claim 8, wherein the hydrogen concentration of the first active layer is greater than or equal to 1 x 10¹⁰ atomic percentages and less than 1 x 10¹⁷ atomic percentages, and wherein the hydrogen concentration of the second active layer is between 1 x 10¹⁷ atomic percentages and 1 x 10²¹ atomic percentages.

10. The thin-film transistor substrate as claimed in claim 8, wherein the carrier mobility of the second active layer is greater than that of the first active layer, and wherein the threshold voltage of the first switching thin-film transistor is greater than that of the second driving thin-film transistor.

11. The thin-film transistor substrate as claimed in claim 8, wherein the first gate electrode comprises a first metal material, wherein the second gate electrode comprises a second metal material, and wherein the binding energy of the first metal material with hydrogen is greater than the binding energy of the second metal material with hydrogen.

12. The thin-film transistor substrate as claimed in claim 11, wherein the first metallic material comprises any one of titanium, molybdenum-titanium alloy, lithium, hafnium, argon, tantalum, magnesium, vanadium, rubidium, scandium, strontium, yttrium, zirconium, niobium, cesium, barium, and lanthanum, and wherein the second metallic material comprises any one of molybdenum, copper, tungsten, cobalt, zinc, gallium, silver, cadmium, indium, tin, iridium, platinum, and gold.

13. A thin-film transistor substrate, comprising: a first switching thin-film transistor located on a substrate; and a second driving thin-film transistor spaced apart from the first switching thin-film transistor, wherein the first switching thin-film transistor comprises: a first active layer; a first gate electrode at least partially overlapping the first active layer; and a first light-shielding layer disposed between the substrate and the first active layer and overlapping the first active layer; wherein the second driving thin-film transistor comprises: a second active layer; a second gate electrode at least partially overlapping the second active layer; and a second light-shielding layer disposed between the substrate and the second active layer and overlapping the second active layer, wherein the first active layer comprises a first oxide semiconductor material, and the second active layer comprises a second oxide semiconductor material, wherein the carrier mobility of the first oxide semiconductor material is greater than the carrier mobility of the second oxide semiconductor material, and wherein the thickness of the first light-shielding layer is greater than the thickness of the second light-shielding layer.

14. The thin-film transistor substrate as claimed in claim 13, wherein the hydrogen concentration of the first active layer, based on the total hydrogen concentration of the first active layer, is greater than or equal to 1 x 10¹⁰ atomic percentages and less than 1 x 10¹⁷ atomic percentages, and wherein, The second active layer is based on the fact that the overall hydrogen concentration of the second active layer is greater than or equal to 1 x 10¹⁰ atomic percentages and less than 1 x 10¹⁷ atomic percentages.

15. The thin-film transistor substrate as claimed in claim 13, wherein each of the first light-shielding layer and the second light-shielding layer comprises a first metallic material, and wherein the first metallic material comprises any one of titanium, molybdenum-titanium alloy, lithium, hafnium, argon, tantalum, magnesium, vanadium, rubidium, scandium, strontium, yttrium, zirconium, niobium, cesium, barium, and lanthanum.

16. A display device comprising: a display panel; a gate driver mounted on the display panel and including a first switching thin-film transistor; and a pixel driving circuit including the first switching thin-film transistor and a second driving thin-film transistor, wherein the first switching thin-film transistor includes: a first active layer; a first gate electrode at least partially overlapping the first active layer; and a first light-shielding layer disposed between the substrate and the first active layer and overlapping the first active layer, wherein the second driving thin-film transistor includes: a second active layer; a second gate electrode at least partially overlapping the second active layer; and a second light-shielding layer disposed between the substrate and the second active layer and overlapping the second active layer, wherein the first light-shielding layer and the second light-shielding layer are made of different materials, and wherein the hydrogen concentration of the second active layer is higher than the hydrogen concentration of the first active layer.

17. The display device as claimed in claim 16, wherein the first active layer comprises a first oxide semiconductor material, the second active layer comprises a second oxide semiconductor material, wherein the carrier mobility of the first oxide semiconductor material is greater than the carrier mobility of the second oxide semiconductor material.

18. The display device as claimed in claim 17, wherein the first light-shielding layer comprises a first metallic material, wherein the second light-shielding layer comprises a second metallic material, and wherein the binding energy of the first metallic material with hydrogen is greater than the binding energy of the second metallic material with hydrogen.

19. The display device as claimed in claim 16, wherein the hydrogen concentration of the first active layer is greater than or equal to 1 x 10¹⁰ atomic percentage and less than 1 x 10¹⁷ atomic percentage, and wherein the hydrogen concentration of the second active layer is between 1 x 10¹⁷ atomic percentage and 1 x 10²¹ atomic percentage.

20. The display device as claimed in claim 16, wherein the carrier mobility of the second active layer is greater than that of the first active layer, and wherein the threshold voltage of the first switching thin-film transistor is greater than that of the second driving thin-film transistor.

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