THIN FILM TRANSISTOR AND LIQUID CRYSTAL DISPLAY DEVICE

Abstract

Related to is a thin film transistor and a liquid crystal display device. The thin film transistor comprises a substrate, and a conductive laminate and a light-shielding layer that are both arranged on the substrate, wherein the light-shielding layer is located below and directly opposite to the conductive laminate. The thin film transistor is provided therein with the light-shielding layer for shading light from irradiating the conductive laminate, thereby effectively preventing unfavorable influences imposed on the electrical properties of oxides by illumination, and thus improving the electrical properties of the thin film transistor.

Claims

1. A thin film transistor, comprising a substrate, and a conductive laminate and a light-shielding layer that are both arranged on the substrate, wherein the light-shielding layer is located below and directly opposite to the conductive laminate.

2. The thin film transistor according to claim 1, wherein the conductive laminate is arranged on a first surface of the substrate, and the light-shielding layer is arranged on a second surface of the substrate, the first surface and the second surface being opposite to each other.

3. The thin film transistor according to claim 2, wherein the second surface of the substrate is provided with a photosensitive material, and a portion of the photosensitive material corresponding to the conductive laminate is exposed to become opaque, so as to form the light-shielding layer.

4. The thin film transistor according to claim 2, wherein an opaque layer is provided on the second surface of the substrate in a region directly facing the conductive laminate, so as to form the light-shielding layer.

5. The thin film transistor according to claim 4, wherein the opaque layer is a metal layer or a nonmetallic oxide layer.

6. The thin film transistor according to claim 5, wherein the opaque layer is made of one selected from a group consisting of aluminum, molybdenum, aluminum neodymium alloy, and silicon dioxide.

7. The thin film transistor according to claim 1, wherein the conductive laminate is arranged on a first surface of the substrate, while the light-shielding layer is arranged in an inner portion of the substrate.

8. The thin film transistor according to claim 7, wherein the inner portion of the substrate is provided with a photosensitive material, and a portion of the photosensitive material corresponding to the conductive laminate is exposed to become opaque, so as to form the light-shielding layer.

9. The thin film transistor according to claim 1, wherein a dimension of the light-shielding layer is larger than or equal to that of the conductive laminate.

10. The thin film transistor according to claim 2, wherein a dimension of the light-shielding layer is larger than or equal to that of the conductive laminate.

11. The thin film transistor according to claim 7, wherein a dimension of the light-shielding layer is larger than or equal to that of the conductive laminate.

12. A liquid crystal display device, comprising a thin film transistor, which includes a substrate, and a conductive laminate and a light-shielding layer that are both arranged on the substrate, wherein the light-shielding layer is located below and directly opposite to the conductive laminate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the following, the present disclosure will be illustrated in detail in connection with embodiments and accompanying drawings, in which:

[0018] FIG. 1 schematically shows a first embodiment of a thin film transistor according to the present disclosure;

[0019] FIG. 2 schematically shows a second embodiment of the thin film transistor according to the present disclosure;

[0020] FIG. 3 schematically shows the structure of a thin film transistor having a climbing region; and

[0021] FIGS. 4 and 5 schematically show features of materials in different regions as indicated in FIG. 3, respectively.

[0022] In the drawings, the same components are indicated with the same reference signs. The figures are not drawn in accordance with an actual scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The present disclosure will be further explained in conjunction with the accompanying drawings.

[0024] FIG. 1 schematically shows a first embodiment of a thin film transistor 10 according to the present disclosure. As illustrated in FIG. 1, the thin film transistor 10 comprises a substrate 1, and a conductive laminate 2 and a light-shielding layer 3 that are both arranged on the substrate 1. The substrate 1 can be a transparent glass substrate. And the conductive laminate 2 typically can include a source, a drain, an oxide active layer, a gate insulator, and a gate. This is well known by those skilled in the art, and will therefore not be repeated.

[0025] The light-shielding layer 3 is located below and directly opposite to the conductive laminate 2. Such being the case, light from below the substrate 1 will not irradiate the conductive laminate 2, the electrical properties of which will thus not be deteriorated due to such irradiation. The electrical properties of the thin film transistor 10 will also be maintained well thereby. This is rather favorable for a liquid crystal display device (not shown) using the thin film transistor 10. Preferably, the dimension of the light-shielding layer 3 is larger than or equal to that of the conductive laminate 2, so as to prevent scattered light from bypassing the light-shielding layer 3 to irradiate the conductive laminate 2.

[0026] In order to enable the conductive laminate 2 to have a completely planar structure, the conductive laminate 2 and the light-shielding layer 3 are arranged on different side surfaces of the substrate 1, respectively. As shown in FIG. 1, the conductive laminate 2 is arranged on a first surface 11 of the substrate 1, while the light-shielding layer 3 is arranged on a second surface 12 of the substrate 1, wherein the first surface 11 and the second surface 12 are opposite to each other. As such, the conductive laminate 2 will have a completely planar structure, particularly without any projecting portions. The grain size and morphology of the material of the conductive laminate 2 and the thickness of the conductive laminate 2 are substantially homogeneous. As a result, on the whole, the electrical properties of the conductive laminate 2 are all same in different regions, thereby rendering the electrical properties of the thin film transistor 10 superior also.

[0027] Contrary to the embodiment as shown in FIG. 1, a conductive laminate 2 as depicted in FIG. 3 has a climbing region 40, which is formed due to an additional layer 41 disposed between the conductive laminate 2 and a substrate 1. The additional layer 41 can be a light-shielding layer. Because the additional layer 41 has a certain thickness, a region 42 of the conductive laminate 2 located above the additional layer 41 is lifted, i.e., the conductive laminate 2 has a projecting region 42 and an original region 43. And the climbing region 40 is formed between the original region 43 and the projecting region 42. The projecting region 42 or the original region 43 has a grain size therein (as shown in FIG. 4) much larger than the grain size in the climbing region 40 (as shown in FIG. 5). Therefore, the electrical properties of the conductive laminate 2 will be different in different regions thereof due to different characteristics of materials. This will impose unfavorable influences on the electrical properties of the thin film transistor.

[0028] The light-shielding layer 3 as shown in FIG. 1 can be achieved as follows. A photosensitive material layer can be provided on the second surface 12 of the substrate 1. A portion of the photosensitive material corresponding to the conductive laminate 2 can be exposed and become opaque, so as to form the light-shielding layer 3. In one embodiment, the photosensitive material can be a silver halide, such as silver iodide, and can also be a dichromate, such as ammonium dichromate. Other similar photosensitive materials can be used also, and will not be repeated herein. A mask plate can be used to selectively expose the photosensitive material, and form the light-shielding layer 3, which is rather favorable for controlling position and area of the light-shielding layer 3.

[0029] The light-shielding layer 3 as shown in FIG. 1 can be achieved through the following approach also. An opaque layer can be arranged on the second surface 12 of the substrate 1 in a region thereof directly facing the conductive laminate 2, so as to form the light-shielding layer 3. The opaque layer can, for example, be a metal layer or a nonmetallic oxide layer. Preferably, the metal layer can be aluminum, molybdenum, or aluminum neodymium alloy. And the nonmetallic oxide layer can be silicon dioxide. In addition, such an opaque layer can have a thickness in the range from 5 to 8 m. It can be formed through a procedure such as evaporation coating and magnetron sputtering, and firmly attached to the substrate 1.

[0030] FIG. 2 schematically shows a light-shielding layer 32 according to a second embodiment. The light-shielding layer 32 is herein formed in an inner portion of the substrate 1 in a position opposite to the conductive laminate 2. Since the light-shielding layer 32 is located within the substrate 1, it will be completely free from influences or damages by external factors, thereby ensuring that the conductive laminate 2 will not be influenced by irradiation.

[0031] In one embodiment, the inner portion of the substrate 1 can be provided with a photosensitive material, a portion of which corresponding to the conductive laminate 2 can be exposed and become opaque, so as to form the light-shielding layer 32. The photosensitive material can be a silver halide, such as silver iodide, and can also be a dichromate, such as ammonium dichromate. Other similar photosensitive materials can be used also, and will not be repeated herein. In practice, the photosensitive material can be added while the substrate 1 is being prepared. And when the substrate 1 is used to manufacture the thin film transistor, a mask plate (not shown) can be turned to, for selective exposure of the photosensitive material, so as to form the light-shielding layer 32. No opaque layers or opaque substances will be necessary to be arranged on an outer surface of the substrate 1, thereby significantly simplifying manufacturing procedures of the thin film transistor or the liquid crystal display device, and cutting down costs thereof

[0032] Although the present disclosure has been described with reference to preferred embodiments, various modifications and variants to the present disclosure may be made by anyone skilled in the art, without departing from the scope of the present disclosure. In particular, as long as there is no structural conflict, various embodiments as well as the respective technical features mentioned herein may be combined with one another in any manner. The present disclosure is not limited to the specific embodiments disclosed herein, but rather includes all the technical solutions falling within the scope of the claims.