阅读说明：本技术 氧化物薄膜晶体管及其制作方法、阵列基板 (Oxide thin film transistor, manufacturing method thereof and array substrate ) 是由 赵舒宁 卓毅 于 2020-11-03 设计创作，主要内容包括：本申请提供一种氧化物薄膜晶体管及其制作方法、阵列基板,该氧化物薄膜晶体管通过调控栅极层的上层部分的功函数与栅极层的下层部分的功函数之间的关系,调控了栅极层整体的功函数,从而与仅有栅极层的下层部分的薄膜晶体管相比,增大了氧化物薄膜晶体管的阈值电压。该氧化物薄膜晶体管的制作方法通过对栅极层进行表面处理,调控栅极层的上层部分的功函数,从而调控栅极层的上层部分的功函数与栅极层的下层部分的功函数之间的关系,增大了氧化物薄膜晶体管的阈值电压。本申请通过调控栅极层表面的功函数,从而调控了氧化物薄膜晶体管整体的功函数匹配,能够增大氧化物薄膜晶体管的阈值电压,减小因长时间光照导致的阈值电压负偏效应。(The application provides an oxide thin film transistor, a manufacturing method thereof and an array substrate, wherein the oxide thin film transistor regulates and controls the whole work function of a grid layer by regulating and controlling the relation between the work function of an upper layer part of the grid layer and the work function of a lower layer part of the grid layer, so that the threshold voltage of the oxide thin film transistor is increased compared with a thin film transistor only with the lower layer part of the grid layer. According to the manufacturing method of the oxide thin film transistor, the surface treatment is carried out on the grid layer, the work function of the upper layer part of the grid layer is regulated and controlled, so that the relation between the work function of the upper layer part of the grid layer and the work function of the lower layer part of the grid layer is regulated and controlled, and the threshold voltage of the oxide thin film transistor is increased. According to the method, the work function of the surface of the grid layer is regulated, so that the whole work function matching of the oxide thin film transistor is regulated, the threshold voltage of the oxide thin film transistor can be increased, and the negative bias effect of the threshold voltage caused by long-time illumination is reduced.)

1. An oxide thin film transistor is characterized by comprising a substrate base plate and a grid layer arranged on the substrate base plate;

the work function of the upper layer part of the grid layer is different from that of the lower layer part of the grid layer, so that the work function of the grid layer is adjusted and controlled to increase the threshold voltage of the oxide thin film transistor.

2. The oxide thin film transistor according to claim 1, wherein if the oxide thin film transistor is an N-type thin film transistor, a work function of an upper layer portion of the gate layer is larger than a work function of a lower layer portion of the gate layer.

3. The oxide thin film transistor according to claim 1, wherein if the oxide thin film transistor is a P-type thin film transistor, a work function of an upper layer portion of the gate layer is smaller than a work function of a lower layer portion of the gate layer.

4. The oxide thin film transistor according to claim 1, further comprising:

and the grid insulating layer, the oxide semiconductor layer, the etching barrier layer and the source drain layer are sequentially arranged on the grid layer.

5. A method for manufacturing an oxide thin film transistor is characterized by comprising the following steps:

providing a substrate base plate;

forming a gate layer on the substrate;

and performing surface treatment on the gate layer to enable the work function of the upper layer part of the gate layer to be different from that of the lower layer part of the gate layer, so as to increase the threshold voltage of the oxide thin film transistor by regulating and controlling the work function of the gate layer.

6. The method according to claim 5, wherein if the oxide thin film transistor is an N-type thin film transistor, performing surface treatment on the gate layer to make a work function of an upper layer portion of the gate layer different from a work function of a lower layer portion of the gate layer, specifically comprises:

and doping oxygen into the upper layer part of the gate layer, so that the work function of the upper layer part of the gate layer is larger than that of the lower layer part of the gate layer.

7. The method according to claim 5, wherein if the oxide thin film transistor is a P-type thin film transistor, performing surface treatment on the gate layer to make a work function of an upper layer portion of the gate layer different from a work function of a lower layer portion of the gate layer, specifically comprises:

and doping hydrogen into the upper layer part of the gate layer, so that the work function of the upper layer part of the gate layer is smaller than that of the lower layer part of the gate layer.

8. The method of claim 6, wherein the doping the upper portion of the gate layer with oxygen comprises:

and bombarding the upper layer part of the grid layer by using oxygen or nitrous oxide plasma to perform plasma surface treatment on the grid layer.

9. The method of claim 7, wherein the doping the upper portion of the gate layer with hydrogen comprises:

and bombarding the upper layer part of the grid layer by using hydrogen plasma to perform plasma surface treatment on the grid layer.

10. An array substrate comprising the oxide thin film transistor according to any one of claims 1 to 4, and a passivation layer, a planarization layer, an anode electrode, and a pixel defining layer over the source and drain layers of the oxide thin film transistor.

Technical Field

The application relates to the technical field of display, in particular to an oxide thin film transistor, a manufacturing method thereof and an array substrate.

Background

Compared with a conventional amorphous silicon thin film transistor (a-Si TFT), an oxide thin film transistor (IGZO TFT) has advantages of high carrier mobility, good uniformity, high optical transmittance, and the like due to the use of an oxide semiconductor as an active layer material, and thus is widely used in the manufacture of display panels. However, oxide semiconductors are sensitive to light irradiation, and long-time light irradiation increases the concentration of photogenerated carriers, electrons or holes, so that the threshold voltage of the oxide thin film transistor generates negative bias, and the function of the device is disabled.

In order to adjust the negatively biased threshold voltage, the oxygen flow rate during film deposition of the channel of the oxide thin film transistor can be increased, so that the generation of oxygen vacancies in the channel layer can be effectively inhibited, the carrier concentration is reduced, the saturation mobility of the oxide thin film transistor is reduced, and the threshold voltage is positively biased.

Disclosure of Invention

In order to solve the above problems, the present application provides an oxide thin film transistor, a method for manufacturing the same, and an array substrate.

In a first aspect, the present application provides an oxide thin film transistor comprising a substrate base plate and a gate layer provided on the substrate base plate; the work function of the upper layer part of the grid layer is different from that of the lower layer part of the grid layer, so that the work function of the grid layer is adjusted and controlled to increase the threshold voltage of the oxide thin film transistor.

In some embodiments, if the oxide thin film transistor is an N-type thin film transistor, a work function of an upper layer portion of the gate layer is greater than a work function of a lower layer portion of the gate layer.

In some embodiments, if the oxide thin film transistor is a P-type thin film transistor, a work function of an upper layer portion of the gate layer is smaller than a work function of a lower layer portion of the gate layer.

In some embodiments, the oxide thin film transistor further includes: and the grid insulating layer, the oxide semiconductor layer, the etching barrier layer and the source drain layer are sequentially arranged on the grid layer.

In a second aspect, the present application further provides a method for manufacturing an oxide thin film transistor, including:

a base substrate is provided.

A gate layer is formed on the substrate.

And performing surface treatment on the gate layer to enable the work function of the upper layer part of the gate layer to be different from that of the lower layer part of the gate layer, so as to increase the threshold voltage of the oxide thin film transistor by regulating and controlling the work function of the gate layer.

In some embodiments, if the oxide thin film transistor is an N-type thin film transistor, performing a surface treatment on the gate layer to make a work function of an upper layer portion of the gate layer different from a work function of a lower layer portion of the gate layer, specifically including:

and doping oxygen into the upper layer part of the gate layer, so that the work function of the upper layer part of the gate layer is larger than that of the lower layer part of the gate layer.

In some embodiments, if the oxide thin film transistor is a P-type thin film transistor, performing a surface treatment on the gate layer to make a work function of an upper layer portion of the gate layer different from a work function of a lower layer portion of the gate layer, specifically including:

and doping hydrogen into the upper layer part of the gate layer, so that the work function of the upper layer part of the gate layer is smaller than that of the lower layer part of the gate layer.

In some embodiments, for an N-type thin film transistor, the doping oxygen to the upper layer portion of the gate layer specifically includes:

and bombarding the upper layer part of the grid layer by using oxygen or nitrous oxide plasma to perform plasma surface treatment on the grid layer.

In some embodiments, for a P-type thin film transistor, the doping the upper layer portion of the gate layer with hydrogen specifically includes:

and bombarding the upper layer part of the grid layer by using hydrogen plasma to perform plasma surface treatment on the grid layer.

In some embodiments, the method of making further comprises:

and sequentially forming a grid insulating layer, an oxide semiconductor layer, an etching barrier layer and a source drain layer on the grid layer.

In a third aspect, the present application also provides an array substrate, which includes the oxide thin film transistor as described above, and a passivation layer, a planarization layer, an anode and a pixel definition layer on the source drain layer of the oxide thin film transistor.

In the oxide thin film transistor, the manufacturing method thereof and the array substrate, the oxide thin film transistor regulates and controls the whole work function of the gate layer by regulating and controlling the relation between the work function of the upper layer part of the gate layer and the work function of the lower layer part of the gate layer, so that the threshold voltage of the oxide thin film transistor is increased compared with a thin film transistor only with the lower layer part of the gate layer. According to the manufacturing method of the oxide thin film transistor, the surface treatment is carried out on the grid layer, the work function of the upper layer part of the grid layer is regulated and controlled, so that the relation between the work function of the upper layer part of the grid layer and the work function of the lower layer part of the grid layer is regulated and controlled, and the threshold voltage of the oxide thin film transistor is increased. According to the method, the work function of the surface of the grid layer is regulated, so that the whole work function matching of the oxide thin film transistor is regulated, the threshold voltage of the oxide thin film transistor can be increased, and the negative bias effect of the threshold voltage caused by long-time illumination is reduced.

Drawings

The technical solution and other advantages of the present application will become apparent from the detailed description of the embodiments of the present application with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a first basic structure of an oxide thin film transistor provided in an embodiment of the present application;

fig. 2 is a schematic diagram of a second basic structure of an oxide thin film transistor according to an embodiment of the present disclosure;

fig. 3 is a schematic diagram of a first specific structure of an oxide thin film transistor according to an embodiment of the present disclosure;

fig. 4 is a schematic diagram of a second specific structure of an oxide thin film transistor according to an embodiment of the present disclosure;

fig. 5 is a schematic flow chart illustrating a method for fabricating an oxide thin film transistor according to an embodiment of the present disclosure;

fig. 6 is a schematic flow chart illustrating a method for fabricating an N-type oxide thin film transistor according to an embodiment of the present disclosure;

fig. 7 is a schematic flowchart illustrating a method for fabricating a P-type oxide thin film transistor according to an embodiment of the present disclosure;

fig. 8 is a schematic view of a first structure of an array substrate according to an embodiment of the present disclosure;

fig. 9 is a schematic view of a second structure of the array substrate according to the embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is known that the threshold voltage of an oxide thin film transistor is related to the work function of the gate thereof, and for an N-type thin film transistor, the larger the work function of the gate, the larger the threshold voltage; for a P-type thin film transistor, the smaller the work function of the gate electrode, the larger the threshold voltage.

Fig. 1 is a schematic diagram of a first basic structure of an oxide thin film transistor provided in an embodiment of the present application, and as shown in fig. 1, the oxide thin film transistor includes: a substrate base plate 1 and a gate layer 2 provided on the substrate base plate 1; wherein, the work function of the upper layer part 21 of the gate layer is different from that of the lower layer part 22 of the gate layer, so as to adjust the work function of the gate layer 2 to increase the threshold voltage of the oxide thin film transistor.

According to the oxide thin film transistor provided by the embodiment of the application, the overall work function of the gate layer 2 is regulated and controlled by regulating and controlling the relation between the work function of the upper layer part 21 of the gate layer and the work function of the lower layer part 22 of the gate layer, so that the threshold voltage of the oxide thin film transistor is increased compared with a thin film transistor only having the lower layer part 22 of the gate layer.

Further, if the oxide thin film transistor is an N-type thin film transistor, the work function of the upper layer portion 21 of the gate layer is larger than that of the lower layer portion 22 of the gate layer. It is to be noted that, at this time, the base substrate 1 is a P-type base substrate.

In the N-type oxide thin film transistor provided by the embodiment of the present application, the work function of the upper layer portion 21 of the gate layer is greater than the work function of the lower layer portion 22 of the gate layer, so that the work function of the entire gate layer 2 is greater than the work function of the lower layer portion 22 of the gate layer.

Alternatively, if the oxide thin film transistor is a P-type thin film transistor, the work function of the upper layer portion 21 of the gate layer is smaller than the work function of the lower layer portion 22 of the gate layer. It is to be noted that, at this time, the base substrate 1 is an N-type base substrate.

In the pmos semiconductor structure provided in the embodiment of the present invention, the work function of the upper portion 21 of the gate layer is smaller than that of the lower portion 22 of the gate layer, so that the work function of the entire gate layer 2 is smaller than that of the lower portion 22 of the gate layer, and compared with a tft with only the lower portion 22 of the gate layer, the threshold voltage of the pmos tft is increased, and the negative bias effect of the threshold voltage due to long-time light can be reduced.

A glass substrate is generally used as the base substrate 1.

Fig. 2 is a schematic diagram of a second basic structure of an oxide thin film transistor according to an embodiment of the present disclosure, and as shown in fig. 2, the oxide thin film transistor may further include a high work function layer 11 disposed on the gate layer 2, where for an N-type oxide thin film transistor, a work function of the high work function layer 11 is greater than a work function of the gate layer 2, so that a work function of the high work function layer 11 and the gate layer 2 as a whole is greater than a work function of the gate layer 2; for a P-type oxide thin film transistor, the work function of the high work function layer 11 is smaller than that of the gate layer 2, and the work function of the high work function layer 11 and the gate layer 2 as a whole is smaller than that of the gate layer 2, so that the threshold voltage of the oxide thin film transistor is larger than that of a thin film transistor only including the gate layer 2, that is, the threshold voltage of the thin film transistor is increased and the negative bias effect of the threshold voltage is reduced by regulating and controlling the relation between the work function of the high work function layer 11 and the work function of the gate layer 2.

The second structure provided by the embodiment of the present application is different from the first structure in that: the first structure is to integrate the upper layer part 21 of the gate layer and the lower layer part 22 of the gate layer, the second structure is to integrate the high work function layer 11 and the gate layer 2, the upper layer part 21 of the gate layer in the first structure is equivalent to the high work function layer 11 in the second structure, and the work function of the upper layer part 21 of the gate layer in the first structure is equivalent to the work function of the high work function layer 11 in the second structure, so that the work function matching of the whole oxide thin film transistor is regulated, and the threshold voltage of the oxide thin film transistor is increased.

It should be noted that the gate layer 2 or the high work function layer 11 may adopt one or more of Mo, Al, Ti, etc., and may have a single-layer or multi-layer structure, and when having a multi-layer structure, the materials used in each layer may be the same or different; the thickness is 500-1000A.

Fig. 3 is a first specific structural schematic diagram of an oxide thin film transistor provided in an embodiment of the present application, and as shown in fig. 1 and fig. 3, the oxide thin film transistor further includes: and the grid insulating layer 3, the oxide semiconductor layer 4, the etching barrier layer 5 and the source drain layer 6 are sequentially arranged on the grid layer 2.

It should be noted that the gate insulating layer 3 may be SiNx or SiOx, and may have a single-layer or multi-layer structure, and when the gate insulating layer has a multi-layer structure, the materials used for each layer may be the same or different, and the thickness is 1000 to 8000A; the oxide semiconductor layer 4 can be IGZO, ITZO or IGZTO, and the thickness is 100-1000A; the etching barrier layer 5 can also adopt SiNx or SiOx, can be of a single-layer or multi-layer structure, and has the thickness of 500-8000A; the source drain layer 6 can be one or more of Mo, Al, Cu, Ti and the like, and the thickness is 1000-5000A.

In addition, with respect to the second basic structure shown in fig. 2, fig. 4 is a schematic diagram of a second specific structure of the oxide thin film transistor provided in the embodiment of the present application, and with reference to fig. 2 and fig. 4, a high work function layer 11 is disposed on the gate layer 2, and then a gate insulating layer 3, an oxide semiconductor layer 4, an etch stop layer 5, and a source drain layer 6 are sequentially disposed on the high work function layer 11.

Fig. 5 is a schematic flow chart of a method for manufacturing an oxide thin film transistor according to an embodiment of the present application, and with reference to fig. 1 and fig. 5, the method for manufacturing an oxide thin film transistor includes:

s501, a base substrate 1 is provided.

S502, the gate layer 2 is formed on the substrate 1.

S503, performing a surface treatment on the gate layer 2 to make the work function of the upper layer portion 21 of the gate layer different from the work function of the lower layer portion 22 of the gate layer, so as to increase the threshold voltage of the oxide thin film transistor by adjusting the work function of the gate layer 2.

According to the method for manufacturing the oxide thin film transistor, the overall work function of the gate layer 2 is regulated and controlled by regulating and controlling the relation between the work function of the upper layer part 21 of the gate layer and the work function of the lower layer part 22 of the gate layer, so that the threshold voltage of the oxide thin film transistor is increased compared with a thin film transistor only with the lower layer part 22 of the gate layer.

Further, if the oxide thin film transistor is an N-type thin film transistor, the surface treatment on the gate layer 2 in step S503 to make the work function of the upper portion 21 of the gate layer different from the work function of the lower portion 22 of the gate layer specifically includes:

the upper layer portion of the gate layer 2 is doped with oxygen so that the work function of the upper layer portion 21 of the gate layer is greater than the work function of the lower layer portion 22 of the gate layer.

Wherein, doping oxygen to the upper layer part 21 of the gate layer specifically includes: the upper layer portion 21 of the gate electrode layer is bombarded with a plasma of oxygen or nitrous oxide to plasma surface treat the gate electrode layer 2.

Further, if the oxide thin film transistor is a P-type thin film transistor, the surface treatment on the gate layer 2 in step S503 to make the work function of the upper portion 21 of the gate layer different from the work function of the lower portion 22 of the gate layer specifically includes:

the upper layer portion of the gate layer 2 is doped with hydrogen so that the work function of the upper layer portion 21 of the gate layer is smaller than the work function of the lower layer portion 22 of the gate layer.

The doping of hydrogen to the upper layer portion 21 of the gate layer specifically includes: the upper layer portion 21 of the gate layer is bombarded with a plasma of hydrogen to perform a plasma surface treatment on the gate layer 2.

Based on the foregoing embodiments, fig. 6 is a schematic flow chart of a method for manufacturing an N-type oxide thin film transistor according to an embodiment of the present application, and as shown in fig. 6, the method for manufacturing an N-type oxide thin film transistor includes:

s601, providing a P-type substrate base plate 1.

S602, a gate layer 2 is formed on the P-type substrate 1.

And S603, carrying out surface treatment on the gate layer 2 to dope oxygen into the upper layer part 21 of the gate layer so that the work function of the upper layer part 21 of the gate layer is greater than that of the lower layer part 22 of the gate layer.

According to the manufacturing method of the N-type oxide thin film transistor, the gate layer 2 is subjected to surface treatment, the upper layer part 21 of the gate layer is doped with oxygen, so that the overall work function of the gate layer 2 is larger than that of the lower layer part 22 of the gate layer, and compared with a thin film transistor only with the lower layer part 22 of the gate layer, the work function of the gate layer 2 is increased, so that the threshold voltage of the N-type oxide thin film transistor is increased, and the negative bias effect of the threshold voltage caused by long-time illumination can be reduced.

Based on the foregoing embodiments, fig. 7 is a schematic flowchart of a method for manufacturing an N-type oxide thin film transistor according to an embodiment of the present application, and as shown in fig. 7, the method for manufacturing a P-type oxide thin film transistor includes:

and S701, providing an N-type substrate base plate 1.

S702, a gate layer 2 is formed on the N-type substrate 1.

And S703, performing surface treatment on the gate layer 2 to dope the upper layer part 21 of the gate layer with hydrogen so that the work function of the upper layer part 21 of the gate layer is smaller than that of the lower layer part 22 of the gate layer.

According to the manufacturing method of the P-type oxide thin film transistor, the gate layer 2 is subjected to surface treatment, the upper layer part 21 of the gate layer is doped with hydrogen, so that the work function of the whole gate layer 2 is smaller than that of the lower layer part 22 of the gate layer, and compared with a thin film transistor only with the lower layer part 22 of the gate layer, the work function of the gate layer 2 is reduced, so that the threshold voltage of the P-type oxide thin film transistor is increased, and the negative bias effect of the threshold voltage caused by long-time illumination can be reduced.

In addition, for the second basic structure shown in fig. 2, the high work function layer 11 on the gate layer 2 may be doped with oxygen to increase the work function of the N-type oxide thin film transistor, so as to increase the threshold voltage of the N-type oxide thin film transistor, by the above method; or for a P-type oxide thin film transistor, the high work function layer 11 is doped with hydrogen to reduce the work function, thereby increasing the threshold voltage of the P-type oxide thin film transistor.

Further, the method for manufacturing the oxide thin film transistor further comprises the following steps: a gate insulating layer 3, an oxide semiconductor layer 4, an etch stopper layer 5, and a source drain layer 6 are sequentially formed on the gate layer 2.

Based on the foregoing embodiment, an array substrate is further provided in an embodiment of the present application, fig. 8 is a schematic view of a first structure of the array substrate provided in the embodiment of the present application, and fig. 9 is a schematic view of a second structure of the array substrate provided in the embodiment of the present application, where the array substrate includes the oxide thin film transistor described above, and as shown in fig. 8 or fig. 9, the array substrate further includes a passivation layer 7, a planarization layer 8, an anode 9, and a pixel defining layer 10 on a source drain layer 6 of the oxide thin film transistor.

The anode layer 9 may be one or more of ITO and IZO, or may be a multi-layer structure of ITO/Ag/ITO, IZO/Ag/IZO, etc., and when the structure is a multi-layer structure, the materials used in each layer may be the same or different.

If the array substrate adopts the oxide thin film transistor with the first structure in fig. 1, as shown in fig. 8, the first manufacturing method of the array substrate specifically includes the following steps in sequence:

a) cleaning the substrate 1;

b) depositing a gate layer 2, and defining an area of the gate layer 2 by yellow light;

c) performing plasma treatment on the surface of the gate layer 2 to dope the upper layer part 21 of the gate layer with oxygen or hydrogen;

d) depositing a gate insulating layer 3;

e) depositing an oxide semiconductor layer 4, and defining a region of the oxide semiconductor layer 4 by using yellow light;

f) depositing an etching barrier layer 5, and defining the area of the etching barrier layer 5 by using yellow light;

g) depositing a source drain layer 6, and defining the area of the source drain layer 6 by using yellow light;

h) depositing a passivation layer 7, and defining a region 7 of the passivation layer by using yellow light;

i) manufacturing a planarization layer 8, and opening holes at the positions where the pixel electrodes are connected;

j) depositing an anode 9;

k) a pixel defining layer 10 is fabricated.

If the array substrate adopts the oxide thin film transistor with the second structure in fig. 2, as shown in fig. 9, the second manufacturing method of the array substrate specifically includes the following steps in sequence:

a') cleaning the substrate 1;

b') depositing the grid layer 2, and defining the area of the grid layer 2 by yellow light;

c') depositing a high work function layer 11;

d') plasma treating the high work function layer 11 to dope the high work function layer 11 with oxygen or hydrogen;

e') depositing a gate insulating layer 3;

f') depositing an oxide semiconductor layer 4, defining a region of the oxide semiconductor layer 4 by using yellow light;

g') depositing an etching barrier layer 5, and defining the area of the etching barrier layer 5 by using yellow light;

h') depositing a source drain layer 6, and defining the area of the source drain layer 6 by using yellow light;

i') depositing a passivation layer 7, and defining the area of the passivation layer 7 by using yellow light;

j') forming a planarization layer 8, and forming a hole at a position where the pixel electrode is connected;

k') depositing an anode 9;

l') the pixel defining layer 10 is fabricated.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The principle and the implementation of the present application are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present application; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.