CN105514118A - Thin film transistor array substrate, preparation method thereof, display panel and display device - Google Patents

Abstract

The invention provides a thin film transistor array substrate and a preparation method thereof, a display panel and a display device. The preparation method includes: simultaneously forming an active region of a switching thin film transistor and a driving thin film transistor on the substrate; forming a switch on the active region The gate insulating layer and gate of the thin film transistor, and the first gate insulating layer of the driving thin film transistor; forming the second gate insulating layer on the first gate insulating layer; forming the gate of driving the thin film transistor; driving the thin film transistor The thickness of the gate insulating layer is greater than the thickness of the gate insulating layer of the switching thin film transistor, so that the subthreshold swing of the driving thin film transistor is greater than the subthreshold swing of the switching thin film transistor. Since the subthreshold swing of the driving thin film transistor is relatively large, it can The display of the gray scale is better controlled, and at the same time, because the sub-threshold swing of the switching thin film transistor is small, the switching performance of the switching thin film transistor is guaranteed, and finally the quality of the display device is improved.

Description

Thin film transistor array substrate and its preparation method, display panel and display device

technical field

The invention relates to the technical field of plane display, in particular to a thin film transistor array substrate and a preparation method thereof, a display panel and a display device.

Background technique

Compared with the current mainstream display technology Thin Film Transistor Liquid Crystal Display (TFT-LCD), organic light-emitting display (Organic Light-Emitting Diode, OLED) has the advantages of wide viewing angle, high brightness, high contrast, low energy consumption, and thinner volume. The focus of flat panel display technology.

There are two driving methods of organic light emitting displays: passive matrix (PM, PassiveMatrix) and active matrix (AM, ActiveMatrix). Compared with the passive matrix drive, the active matrix drive has the advantages of large display information, low power consumption, long device life, and high screen contrast.

Currently, active matrix organic light emitting displays (AMOLEDs) mainly use low temperature polysilicon thin film transistors (LTPS-TFTs) to drive OLEDs to emit light. As shown in FIG. 1 , generally speaking, an active matrix organic light emitting display includes: a switching thin film transistor 2 , a driving thin film transistor 1 and an organic light emitting device (OLED) 3 . The gate of the switching thin film transistor 2 is connected to the scan line 4 , the drain (or source) thereof is connected to the data line 5 , and the source (or drain) is connected to the gate of the driving thin film transistor 1 . The source (or drain) of the driving thin film transistor 1 is connected to the power line 6, the drain (or source) is connected to the anode of the OLED, and the cathode of the OLED is grounded. A storage capacitor 7 is connected between the source (or drain) and the gate of the driving thin film transistor 1 .

Generally, the switching thin film transistor 2 is required to have a low sub-threshold swing (sub-threshold swing, S.S), so that the current varies more with the voltage, and the driving thin film transistor 1 is required to have a higher sub-threshold swing, so that the current varies more with the voltage. Small, this can ensure better switching performance of the switching thin film transistor 2, which is beneficial to gray scale control. The sub-threshold swing of the TFT depends on the gate capacitance, and the gate capacitance depends on the thickness of the gate insulating layer. Therefore, the thickness of the gate insulating layer of the driving TFT 2 should be greater than that of the switching TFT 1. thickness of.

However, in the existing technology, the manufacturing process of the switching thin film transistor 2 and the driving thin film transistor 1 are the same, and the thickness of the gate insulating layer is also the same, which results in equal sub-threshold swings of the two thin film transistors, which is not conducive to effective Turn on and off the switching thin film transistor and the control of the gray scale.

Contents of the invention

The purpose of the present invention is to provide a thin-film transistor array substrate and its preparation method, display panel and display device, which can effectively improve the sub-threshold swing of the driving thin-film transistor under the premise of keeping the sub-threshold swing of the switching thin-film transistor small, thereby ensuring The switching capability of the switching thin film transistor can better control the gray scale display and improve the quality of the display device.

In order to achieve the above object, the present invention provides a method for preparing a thin film transistor array substrate, comprising:

Simultaneously forming the active area of the switching thin film transistor and the active area of the driving thin film transistor on the substrate;

Simultaneously forming a gate insulating layer of a switching thin film transistor and a first gate insulating layer of a driving thin film transistor on the substrate;

forming the gate of the switch thin film transistor on the gate insulating layer of the switch thin film transistor;

forming a second gate insulating layer on the first gate insulating layer of the driving thin film transistor;

A gate of a driving thin film transistor is formed on the second gate insulating layer.

Optionally, the gate insulating layer includes one of a silicon oxide layer, a silicon nitride layer or a combination thereof.

Optionally, after forming the gate of the driving thin film transistor on the second gate insulating layer, it further includes: sequentially forming a protective layer, the source/drain of the switching thin film transistor and the driving thin film transistor, an organic planar layer, organic Electromechanical Luminescent Electrodes and Pixel Definition Layers.

The present invention also provides a method for preparing a thin film transistor array substrate, comprising:

Simultaneously forming the gate of the switching thin film transistor and the gate of the driving thin film transistor on the substrate;

Simultaneously forming a gate insulating layer of a switching thin film transistor and a first gate insulating layer of a driving thin film transistor on the substrate;

forming an active region of the switching thin film transistor on the gate insulating layer of the switching thin film transistor;

forming a second gate insulating layer on the first gate insulating layer of the driving thin film transistor;

An active region for driving a thin film transistor is formed on the second gate insulating layer.

Optionally, the gate insulating layer includes one of a silicon oxide layer, a silicon nitride layer or a combination thereof.

Optionally, after forming the active region of the driving thin film transistor on the second gate insulating layer, it further includes: sequentially forming a protective layer, the source/drain of the switching thin film transistor and the driving thin film transistor, an organic planar layer, Organic electroluminescent electrodes and pixel definition layers.

Correspondingly, the present invention also provides a thin film transistor array substrate, which is prepared by the above method for preparing the thin film transistor array substrate.

Preferably, the switch thin film transistor is a top gate thin film transistor or a bottom gate thin film transistor; the driving thin film transistor is a top gate thin film transistor or a bottom gate thin film transistor.

Correspondingly, the present invention also provides a display panel, including the above thin film transistor array substrate.

Correspondingly, the present invention also provides a display device, including the above-mentioned display panel.

Compared with the prior art, the thin film transistor array substrate and its preparation method, display panel and display device provided by the present invention, after forming the gate pattern of the switching thin film transistor, on the first gate insulating layer of the driving thin film transistor forming a second gate insulating layer, so that the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the gate insulating layer of the switching thin film transistor, so that the gate capacitance of the driving thin film transistor is smaller than the gate capacitance of the switching thin film transistor, Furthermore, the subthreshold swing of the driving thin film transistor is larger than that of the switching thin film transistor. Since the subthreshold swing of the driving thin film transistor is relatively large, the gray scale display can be better controlled. At the same time, due to the subthreshold swing of the switching thin film transistor The swing amplitude is small, which ensures the switching performance of the switching thin film transistor, and finally improves the quality of the display device.

Description of drawings

FIG. 1 is a basic schematic diagram of an existing active matrix organic light emitting display (AMOLED);

FIG. 2 is a flow chart of a method for manufacturing a thin film transistor array substrate provided in Embodiment 1 of the present invention;

3 to 7 are structural schematic diagrams of each step of the manufacturing method of the thin film transistor array substrate provided by Embodiment 1 of the present invention.

detailed description

In order to make the content of the present invention clearer and easier to understand, the content of the present invention will be further described below in conjunction with the accompanying drawings. Of course, the present invention is not limited to this specific embodiment, and general replacements known to those skilled in the art are also covered within the protection scope of the present invention.

Secondly, the present invention is described in detail by means of schematic diagrams. When describing the examples of the present invention in detail, for the convenience of illustration, the schematic diagrams are not partially enlarged according to the general scale, which should not be used as a limitation of the present invention.

The core idea of the present invention is that by forming the second gate insulating layer on the first gate insulating layer of the driving thin film transistor after forming the gate pattern of the switching thin film transistor, the thickness of the gate insulating layer of the driving thin film transistor greater than the thickness of the gate insulating layer of the switching thin film transistor, thereby making the gate capacitance value of the driving thin film transistor smaller than the gate capacitance value of the switching thin film transistor, thereby making the subthreshold swing of the driving thin film transistor larger than that of the switching thin film transistor , due to the large sub-threshold swing of the driving thin film transistor, the display of gray scale can be better controlled, and at the same time, because the sub-threshold swing of the switching thin film transistor is small, the switching performance of the switching thin film transistor is guaranteed, and finally the quality of the display device is improved .

[Example 1]

FIG. 2 is a flow chart of a method for preparing a thin film transistor array substrate provided in Embodiment 1 of the present invention. As shown in FIG. 2 , the present invention proposes a method for preparing a thin film transistor array substrate, which includes the following steps:

Step S01: simultaneously forming an active region of a switching thin film transistor and an active region of a driving thin film transistor on a substrate;

Step S02: simultaneously forming a gate insulating layer of a switching thin film transistor and a first gate insulating layer of a driving thin film transistor on the substrate;

Step S03: forming the gate of the switching thin film transistor on the gate insulating layer of the switching thin film transistor;

Step S04: forming a second gate insulating layer on the first gate insulating layer of the driving thin film transistor;

Step S05: forming a gate of a driving thin film transistor on the second gate insulating layer.

3 to 7 are schematic diagrams of structures formed in each step of the manufacturing method of the thin film transistor array substrate provided by Embodiment 1 of the present invention. The preparation method of the thin film transistor array substrate proposed by the present invention will be described in detail below with reference to FIGS. 2 to 7 .

In step S01 , the active region 11 of the switching thin film transistor and the active region 11 of the driving thin film transistor are simultaneously formed on the substrate 10 , as shown in FIG. 3 . The substrate 10 is a transparent substrate, preferably, the substrate 20 is a glass substrate. The thin film transistor and the active region 11 for driving the thin film transistor are formed on the substrate 10 through processes such as sputtering, exposure, development, etching, and stripping. Wherein, the material of the active region 11 is polysilicon, or other materials known to those skilled in the art.

In step S02 , the gate insulating layer 12 of the switching thin film transistor and the first gate insulating layer 12 of the driving thin film transistor are simultaneously formed on the substrate after the above steps, as shown in FIG. 4 . In this embodiment, a gate insulating layer 12 is formed on the substrate 10 by chemical vapor deposition, exposure, development, etching, stripping and other processes, and the gate insulating layer 12 formed on the active region 11 of the switching transistor is The gate insulating layer of the switching thin film transistor is the first gate insulating layer of the driving thin film transistor formed on the active region 11 of the driving thin film transistor. Preferably, the gate insulating layer 12 is formed by plasma enhanced chemical vapor deposition (PECVD, Plasma Enhanced Chemical Vapor Deposition). It is understood that the gate insulating layer 12 may also be formed by other methods. Wherein, the gate insulating layer 12 is a single-layer or multi-layer structure, which includes one of a silicon oxide layer, a silicon nitride layer or a combination thereof.

In step S03 , the gate 13 of the switch thin film transistor is formed on the gate insulating layer 12 of the switch thin film transistor, as shown in FIG. 5 . Specifically, on the substrate 10 after the above steps are completed, the gate 13 of the switching thin film transistor is formed by processes such as sputtering, exposure, development, etching, and stripping. Wherein, the material of the gate 13 can be molybdenum (Mo), molybdenum niobium alloy (MoNb), aluminum (Al), aluminum neodymium alloy (AlNd), tungsten (W), titanium (Ti) and copper (Cu) A single-layer or multi-layer composite laminate formed of one or more of them.

In step S04 , a second gate insulating layer 14 is formed on the first gate insulating layer 12 of the driving thin film transistor, as shown in FIG. 6 . In this embodiment, the second gate insulating layer 14 is formed by chemical vapor deposition, exposure, development, etching, stripping, etc. It can be understood that other methods can also be used to form the second gate insulating layer 14 . Wherein, the second gate insulating layer 14 is a single-layer or multi-layer structure, which includes one of a silicon oxide layer, a silicon nitride layer or a combination thereof.

That is to say, the gate insulating layer of the driving thin film transistor is the first gate insulating layer plus the second gate insulating layer, that is, the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the gate insulating layer of the switching thin film transistor, according to The capacitance formula C=εAd (wherein C is the capacitance of the thin film transistor, d is the thickness of the gate insulating layer of the thin film transistor, A is the area of the gate insulating layer of the thin film transistor, and ε is the dielectric constant) can draw the capacitance of the thin film transistor and its The thickness of the gate insulating layer is inversely proportional, so that the gate capacitance of the driving thin film transistor is smaller than the gate capacitance of the switching thin film transistor, so that the subthreshold swing of the driving thin film transistor is greater than the subthreshold swing of the switching thin film transistor, because The sub-threshold swing of the driving thin film transistor is relatively large, which can better control the display of the gray scale. At the same time, the switching performance of the switching thin film transistor is guaranteed due to the small sub-threshold swing of the switching thin film transistor, and finally the quality of the display device is improved.

In step S05 , the gate 15 for driving the thin film transistor is formed on the second gate insulating layer 14 , as shown in FIG. 7 . Specifically, on the substrate 10 after the above steps are completed, the gate 15 for driving the thin film transistor is formed by processes such as sputtering, exposure, development, etching, and stripping. Wherein, the material of the gate 15 can be molybdenum (Mo), molybdenum niobium alloy (MoNb), aluminum (Al), aluminum neodymium alloy (AlNd), tungsten (W), titanium (Ti) and copper (Cu) A single-layer or multi-layer composite laminate formed of one or more of them.

After forming the gate 15 of the driving thin film transistor on the second gate insulating layer 14, it also includes: sequentially forming a protective layer, the source/drain of the switching thin film transistor and the driving thin film transistor, an organic planar layer, an organic electro- Light-emitting electrodes, pixel definition layers, etc. The above steps are well known to those skilled in the art and will not be repeated here.

The above method describes the specific preparation method of the thin film transistor array substrate when both the switching thin film transistor and the driving thin film transistor are top-gate thin film transistors. If both the switching thin film transistor and the driving thin film transistor are bottom-gate thin film transistors, the preparation method of the thin film transistor array substrate is similar to the above method, the difference is that:

Step S01: Form the gate 11 of the switching thin film transistor and the gate 11 of the driving thin film transistor on the substrate 10 at the same time; Step S02: Form the gate insulating layer 12 of the switching thin film transistor and the gate insulating layer 12 of the driving thin film transistor on the substrate 10 at the same time. The first gate insulating layer 12; step S03: forming the active region 13 of the switching thin film transistor on the gate insulating layer 12 of the switching thin film transistor; step S04: forming the first gate insulating layer of the driving thin film transistor Forming a second gate insulating layer 14 on 12 ; Step S05 : forming an active region 15 for driving a thin film transistor on the second gate insulating layer 14 .

Wherein, the gate insulating layer includes one of a silicon oxide layer, a silicon nitride layer or a combination thereof; and, after forming the gate 15 of the driving thin film transistor on the second gate insulating layer 14, it further includes: Form the protection layer, the source/drain of the switching thin film transistor and the driving thin film transistor, the organic planar layer, the organic electroluminescence electrode, the pixel definition layer and so on. The above steps are well known to those skilled in the art and will not be repeated here.

Of course, the types of the switching thin film transistor and the driving thin film transistor may also be different, that is, the switching thin film transistor is a top gate thin film transistor, the driving thin film transistor is a bottom gate thin film transistor, or the switching thin film transistor is a bottom gate thin film transistor, The driving thin film transistor is a top-gate thin film transistor. At this time, the thin film transistor array substrate can be prepared separately from the switching thin film transistor and the driving thin film transistor, as long as it is ensured that after the gate or active region pattern of the switching thin film transistor is formed, the driving thin film transistor The second gate insulating layer is formed on the first gate insulating layer of the transistor, so that the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the gate insulating layer of the switching thin film transistor. The preparation method of each thin film transistor is the same as The above methods are similar and will not be repeated here.

[Example 2]

This embodiment provides a thin film transistor array substrate, which is prepared by the manufacturing method of the thin film transistor array substrate described in the first embodiment.

Please refer to FIG. 7, the thin film transistor array substrate includes a switching thin film transistor and a driving thin film transistor, the gate insulating layer of the switching thin film transistor is a gate insulating layer 12, and the gate insulating layer of the driving thin film transistor is The first gate insulating layer 12 and the second gate insulating layer 14, the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the switching thin film transistor gate insulating layer, so that the gate capacitance of the driving thin film transistor is smaller than the switching thin film transistor The gate capacitance value, so that the subthreshold swing of the driving thin film transistor is larger than the subthreshold swing of the switching thin film transistor. Because the subthreshold swing of the driving thin film transistor is larger, the gray scale display can be better controlled. At the same time, because The sub-threshold swing of the switching thin film transistor is small, which ensures the switching performance of the switching thin film transistor, and finally improves the quality of the display device.

Preferably, the switch thin film transistor is a top gate thin film transistor or a bottom gate thin film transistor; the driving thin film transistor is a top gate thin film transistor or a bottom gate thin film transistor.

[Embodiment 3]

This embodiment provides a display panel, which includes the TFT array substrate described in the second embodiment.

The display panel of this embodiment has the thin film transistor array substrate in the second embodiment, so the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the switching thin film transistor gate insulating layer, so that the gate capacitance of the driving thin film transistor smaller than the gate capacitance value of the switching thin film transistor, thereby making the subthreshold swing of the driving thin film transistor larger than the subthreshold swing of the switching thin film transistor, since the subthreshold swing of the driving thin film transistor is larger, the gray scale can be better controlled At the same time, due to the small sub-threshold swing of the switching thin film transistor, the switching performance of the switching thin film transistor is guaranteed, and the quality of the display device is finally improved.

[Embodiment 4]

This embodiment provides a display device, which includes the display panel described in the third embodiment.

The display device in this embodiment has the display panel in Embodiment 3, so the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the gate insulating layer of the switching thin film transistor, so that the gate capacitance of the driving thin film transistor is smaller than that of the switching transistor. The gate capacitance value of the thin film transistor makes the subthreshold swing of the driving thin film transistor larger than the subthreshold swing of the switching thin film transistor. Since the subthreshold swing of the driving thin film transistor is larger, the gray scale display can be better controlled. At the same time, since the sub-threshold swing of the switching thin film transistor is small, the switching performance of the switching thin film transistor is guaranteed, and finally the quality of the display device is improved.

To sum up, the thin film transistor array substrate and its preparation method, display panel and display device provided by the present invention are formed by forming the first gate insulating layer of the driving thin film transistor after forming the gate pattern of the switching thin film transistor. Two gate insulating layers, so that the thickness of the gate insulating layer of the driving thin film transistor is greater than the thickness of the switching thin film transistor gate insulating layer, so that the gate capacitance value of the driving thin film transistor is smaller than the gate capacitance value of the switching thin film transistor, and then makes the gate capacitance value of the switching thin film transistor The subthreshold swing of the driving thin film transistor is larger than that of the switching thin film transistor. Because the subthreshold swing of the driving thin film transistor is larger, the gray scale display can be better controlled. At the same time, due to the subthreshold swing of the switching thin film transistor Smaller, to ensure the switching performance of the switching thin film transistor, and finally improve the quality of the display device.

The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention. Any changes and modifications made by those of ordinary skill in the field of the present invention based on the above disclosures shall fall within the protection scope of the claims.

Claims (10)

1. a preparation method for thin-film transistor array base-plate, is characterized in that, comprising:

Substrate is formed the active area of switching thin-film transistor simultaneously and drives the active area of thin-film transistor;

Form the gate insulator of switching thin-film transistor on the substrate simultaneously and drive the first grid insulating barrier of thin-film transistor;

The gate insulator of described switching thin-film transistor is formed the grid of switching thin-film transistor;

The first grid insulating barrier of described driving thin-film transistor forms second grid insulating barrier;

Described second grid insulating barrier is formed the grid driving thin-film transistor.

2. the preparation method of thin-film transistor array base-plate as claimed in claim 1, it is characterized in that, described gate insulator comprises silicon oxide layer, silicon nitride layer one or a combination set of.

3. the preparation method of thin-film transistor array base-plate as claimed in claim 1; it is characterized in that; after described second grid insulating barrier forms the grid driving thin-film transistor, also comprise: form the source/drain of protective layer, switching thin-film transistor and driving thin-film transistor, organic planarization layer, organic electroluminescent electrode and pixel defining layer successively.

4. a preparation method for thin-film transistor array base-plate, is characterized in that, comprising:

Substrate is formed the grid of switching thin-film transistor simultaneously and drives the grid of thin-film transistor;

Form the gate insulator of switching thin-film transistor on the substrate simultaneously and drive the first grid insulating barrier of thin-film transistor;

The gate insulator of described switching thin-film transistor is formed the active area of switching thin-film transistor;

The first grid insulating barrier of described driving thin-film transistor forms second grid insulating barrier;

Described second grid insulating barrier is formed the active area driving thin-film transistor.

5. the preparation method of thin-film transistor array base-plate as claimed in claim 4, it is characterized in that, described gate insulator comprises silicon oxide layer, silicon nitride layer one or a combination set of.

6. the preparation method of OLED array as claimed in claim 4; it is characterized in that; after described second grid insulating barrier forms the active area driving thin-film transistor, also comprise: form the source/drain of protective layer, switching thin-film transistor and driving thin-film transistor, organic planarization layer, organic electroluminescent electrode and pixel defining layer successively.

7. a thin-film transistor array base-plate, is characterized in that, adopts preparation method's preparation of the thin-film transistor array base-plate according to any one of claim 1 ~ 6.

8. thin-film transistor array base-plate as claimed in claim 7, it is characterized in that, described switching thin-film transistor is top gate type thin film transistor or bottom gate thin film transistor; Described driving thin-film transistor is top gate type thin film transistor or bottom gate thin film transistor.

9. a display floater, is characterized in that, comprises the thin-film transistor array base-plate described in claim 7 or 8.

10. a display unit, is characterized in that, comprises display floater according to claim 9.