Thin film transistor and preparation method thereof

Abstract

The invention belongs to the technical field of panel display, and particularly relates to a thin film transistor and a preparation method thereof. A gate electrode layer, a gate insulating layer, an initial source electrode and an initial drain electrode are sequentially formed on the upper surface of a substrate part; etching the whole surfaces of the initial source electrode and the initial drain electrode by adopting a dry etching method to form a source electrode, a drain electrode and a channel between the source electrode and the drain electrode, and the length of the channel is less than or equal to 7 microns; and then preparing an active layer and a passivation layer. In conclusion, in combination with an existing solution preparation method, the preparation of the high-precision channel of the device is realized through dry etching; meanwhile, when the channel is prepared by dry etching, the surface of the bottom surface (gate insulating layer) of the channel can be modified, the surface characteristics are improved, and the electrical performance of the device is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of flat panel displays, and in particular relates to a thin film transistor and a preparation method thereof. Background Art

[0002] With the continuous advancement of display technology, thin-film transistors (TFTs) are moving towards higher resolution, higher performance, and lower cost. As core components of display screens, thin-film transistors (TFTs) play a vital role. Traditionally, TFTs are manufactured using vacuum technology, which requires extensive equipment and complex processes, resulting in high manufacturing costs. Therefore, novel printing manufacturing processes are one of the key approaches to reducing manufacturing costs.

[0003] Compared to traditional vacuum evaporation methods, the all-solution method avoids the limitations of high energy consumption and equipment costs. It fabricates thin-film transistor devices through the self-assembly or chemical reaction of material molecules in solution on a substrate. This method not only reduces production costs but also has the potential to enable the production of larger display screens, meeting growing market demand.

[0004] At present, in the process of preparing thin films by the full solution method, the device channel adopts the printing method, and the film solution is directly printed to the designated area through the nozzle, and then the printed solution is cured at high temperature to realize the device pattern preparation. However, the full solution method for preparing devices is limited by the combined effects of the printing accuracy of the printing equipment and the surface tension of the solution, and the dimensional accuracy of the printed graphics is limited. For planar TFT devices, the spacing between the drain and source electrodes determines the channel length (L) of the device, and the channel length determines the size of the device. The printing accuracy of the channel obtained by the current printing display technology is 10μm to 50μm, which makes it difficult to achieve the printing preparation of higher resolution display graphics. Summary of the Invention

[0005] The object of the present invention is to provide a thin film transistor and a method for preparing the same. The preparation method provided by the present invention can achieve higher-precision channel preparation; at the same time, it can perform interface modification on the channel bottom surface, thereby improving the electrical performance of the device.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a thin film transistor, comprising the following steps:

[0008] Printing a gate electrode film layer on the upper surface of the substrate portion, wherein the gate electrode film layer is cured to form a gate electrode layer;

[0009] Printing a first insulating film layer on the remaining upper surface of the substrate and the upper surface of the gate electrode layer, wherein the first insulating film layer is cured to form a gate insulating layer, and the gate insulating layer forms a boss in the gate electrode region;

[0010] Printing a source electrode film layer and a drain electrode film layer on the upper surface of the boss of the gate insulating layer, wherein the source electrode film layer contacts the drain electrode film layer, and the source electrode film layer and the drain electrode film layer form an initial source electrode and an initial drain electrode after being cured, wherein one end edge of the initial source electrode contacts one end edge of the initial drain electrode;

[0011] The entire surface of the initial source electrode and the initial drain electrode is etched by dry etching to form a source electrode, a drain electrode, and a channel between the source electrode and the drain electrode, wherein the length of the channel is ≤7 μm;

[0012] Printing an active material film layer on the upper surface of the source electrode portion, the upper surface of the drain electrode portion and in the channel, wherein the active material film layer forms an active layer after being cured;

[0013] A second insulating film layer is printed on the remaining upper surface of the gate insulating layer, the remaining upper surface of the source electrode, the upper surface of the active layer and the remaining upper surface of the drain electrode, and the second insulating film layer forms a passivation layer after being cured.

[0014] Preferably, the dry etching is plasma etching; the conditions of the dry etching include: the etching gas includes one or more of SF6, CF4, O2 and He, the etching radio frequency (RF) power is 100~800W, the working gas pressure is 0.1~10Pa, and the etching time is 50~400s.

[0015] Preferably, the printing conditions of the gate electrode film layer, the source electrode film layer or the drain electrode film layer include: a printing voltage of 0.5 to 10 V and a pulse frequency of 10 to 60 Hz; the first solution used for printing includes a first printing material and a solvent, the first printing material includes one or more of aluminum sec-butoxide, silver chloride and copper sulfate hydrate, and the molar concentration of the first printing material in the first solution is 0.1 to 0.5 mol / mL.

[0016] Preferably, the square resistance of the gate electrode, the source electrode or the drain electrode is 10 -2 Ω / □~10 2 Ω / □;

[0017] The thickness of the gate electrode, the source electrode or the drain electrode is 30 nm to 100 nm.

[0018] Preferably, the printing conditions of the first insulating film layer or the second insulating film layer include: a printing voltage of 0.5 to 10 V and a pulse frequency of 10 to 60 Hz; the second solution used for printing includes a second printing material and a solvent, the second printing material includes one or more of hafnium oxychloride octahydrate and zirconium oxychloride hydrate, and the molar concentration of the second printing material in the second solution is 0.1 to 0.5 mol / mL.

[0019] Preferably, the relative dielectric constant of the gate insulating layer or the passivation layer is 3 to 30;

[0020] The gate insulating layer or the passivation layer has a thickness of 100 to 150 nm.

[0021] Preferably, the printing conditions of the active material film layer include: a printing voltage of 0.5 to 10 V, a pulse frequency of 10 to 60 Hz; the third solution used for printing includes a third printing material and a solvent, the third printing material includes indium gallium oxide and / or indium gallium zinc oxide, and the molar concentration of the third printing material in the third solution is 0.03 to 0.5 mol / mL.

[0022] Preferably, the Hall mobility of the active layer is 0.5 to 150 cm 2 / Vs;

[0023] The thickness of the active layer is 20-100 nm.

[0024] Preferably, the length of the channel is 2-5 μm.

[0025] The present invention provides a thin film transistor prepared by the preparation method described in the above technical solution.

[0026] The present invention provides a method for preparing a thin film transistor, comprising the following steps: printing a gate electrode film layer on a portion of the upper surface of a substrate, wherein the gate electrode film layer is cured to form a gate electrode layer; printing a first insulating film layer on the remaining upper surface of the substrate and on the upper surface of the gate electrode layer, wherein the first insulating film layer is cured to form a gate insulating layer, wherein the gate insulating layer forms a boss in the gate electrode region; printing a source electrode film layer and a drain electrode film layer on the upper surface of the boss of the gate insulating layer, wherein the source electrode film layer and the drain electrode film layer are in contact with each other, wherein the source electrode film layer and the drain electrode film layer are cured to form an initial source electrode and an initial drain electrode, wherein the initial source electrode The invention relates to a method for fabricating a gate insulating layer, a gate insulating layer and a drain electrode, wherein the gate insulating layer is provided with a first electrode and a second electrode, wherein the first electrode and the drain electrode are provided with a first ... The preparation method provided by the present invention abandons the method of directly obtaining the device channel by printing, and first obtains the initial source electrode and the initial drain electrode in contact with each other on the surface of the gate insulating layer by solution printing. Due to the surface tension of the solution printing, the thickness of the area where the initial source electrode and the initial drain electrode are in contact is thinner than the overall thickness of the initial source electrode and the initial drain electrode; then the present invention adopts a dry etching method to etch the entire plate of the initial source electrode and the initial drain electrode. In the process of thinning the entire plate, the area where the initial source electrode and the initial drain electrode are in contact is thin, so a channel is formed first. Therefore, the present invention adopts a dry etching method to obtain the source electrode, the drain electrode, and the channel between the source electrode and the drain electrode, and the length of the channel is ≤7μm. In summary, the present invention combines the existing solution preparation method and realizes the preparation of high-precision channels of the device by dry etching; at the same time, when the present invention adopts dry etching to prepare the channel, it can modify the surface of the bottom surface of the channel (gate insulating layer), improve the surface characteristics, and enhance the electrical performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the gate electrode layer prepared in an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of the structure of the gate insulating layer prepared in an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of the structure of a source electrode (i.e., an initial source electrode) and a drain electrode (i.e., an initial drain electrode) formed by printing and curing in an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the structure of the source electrode and the drain electrode formed by dry etching in an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of the structure of the active layer prepared in an embodiment of the present invention;

[0032] Figure 6 Schematic diagram of the structure of the passivation layer prepared in an embodiment of the present invention;

[0033] Figure 7 is a flow chart of manufacturing a thin film transistor according to an embodiment of the present invention;

[0034] Figure 8 The transfer characteristic curve of the thin film transistor device prepared in Example 1;

[0035] In the figure: 100 is a substrate, 201 is a gate electrode layer, 301 is a gate insulating layer, 401a is an initial source electrode, 402a is an initial drain electrode, 401b is a source electrode, 402b is a drain electrode, 501 is an active layer, and 601 is a passivation layer. DETAILED DESCRIPTION

[0036] The present invention provides a method for preparing a thin film transistor, comprising the following steps:

[0037] Printing a gate electrode film layer on the upper surface of the substrate portion, wherein the gate electrode film layer is cured to form a gate electrode layer;

[0038] Printing a first insulating film layer on the remaining upper surface of the substrate and the upper surface of the gate electrode layer, wherein the first insulating film layer is cured to form a gate insulating layer, and the gate insulating layer forms a boss in the gate electrode region;

[0039] Printing a source electrode film layer and a drain electrode film layer on the upper surface of the boss of the gate insulating layer, wherein the source electrode film layer contacts the drain electrode film layer, and the source electrode film layer and the drain electrode film layer form an initial source electrode and an initial drain electrode after being cured, wherein one end edge of the initial source electrode contacts one end edge of the initial drain electrode;

[0040] The entire surface of the initial source electrode and the initial drain electrode is etched by dry etching to form the source electrode, the drain electrode, and a channel between the source electrode and the drain electrode, wherein the length of the channel is ≤7 μm;

[0041] Printing an active material film layer on the upper surface of the source electrode portion, the upper surface of the drain electrode portion and in the channel, wherein the active material film layer forms an active layer after being cured;

[0042] A second insulating film layer is printed on the remaining upper surface of the gate insulating layer, the remaining upper surface of the source electrode, the upper surface of the active layer and the remaining upper surface of the drain electrode, and the second insulating film layer forms a passivation layer after being cured.

[0043] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0044] In the present invention, a gate electrode film layer is printed on a portion of the upper surface of a substrate, and the gate electrode film layer is cured to form a gate electrode layer. In the present invention, the substrate is preferably made of glass. In the present invention, the substrate is preferably pre-cleaned. The present invention has no particular requirements for the specific implementation of the pre-cleaning process.

[0045] In the present invention, the printing conditions of the gate electrode film layer preferably include: the printing voltage is preferably 0.5 to 10V, more preferably 2V, and the pulse frequency is preferably 10 to 60Hz, more preferably 30Hz. The first solution used for printing preferably includes a first printing material and a solvent. The first printing material preferably includes one or more of aluminum sec-butoxide, silver chloride and copper sulfate hydrate, more preferably aluminum sec-butoxide. The solvent is preferably an inorganic solvent or an organic solvent, more preferably an organic solvent. The present invention has no special requirements for the type of the organic solvent, as long as the gate electrode film layer is printed normally. The molar concentration of the first printing material in the first solution is preferably 0.1 to 0.5 mol / mL, more preferably 0.3 mol / mL.

[0046] The present invention has no special requirements on the specific implementation of the gate electrode film curing.

[0047] In the present invention, the square resistance of the gate electrode is preferably 10 -2 Ω / □~10 2 Ω / □, more preferably 10 -2 Ω / □.

[0048] In the present invention, the thickness of the gate electrode is preferably 30 nm to 100 nm, more preferably 50 nm.

[0049] After obtaining the gate electrode layer, the present invention prints a first insulating film layer on the remaining upper surface of the substrate and the upper surface of the gate electrode layer. The first insulating film layer is cured to form a gate insulating layer, and the gate insulating layer forms a boss in the gate electrode region. In the present invention, the printing conditions of the first insulating film layer preferably include: the printing voltage is preferably 0.5 to 10V, more preferably 5V. The pulse frequency is preferably 10 to 60Hz, more preferably 60Hz. The second solution used for printing preferably includes a second printing material and a solvent. The second printing material preferably includes one or more of hafnium oxychloride octahydrate and zirconium oxychloride hydrate, more preferably hafnium oxychloride octahydrate. The solvent is preferably an inorganic solvent or an organic solvent, more preferably an organic solvent. The present invention has no special requirements for the type of the organic solvent, as long as the second insulating film layer is printed normally. The molar concentration of the second printing material in the second solution is preferably 0.1 to 0.5 mol / mL, more preferably 0.3 mol / mL.

[0050] The present invention has no special requirements on the specific implementation of curing the first insulating film layer.

[0051] In the present invention, the material of the gate insulating layer preferably includes HfO x and / or ZrO x .

[0052] In the present invention, the relative dielectric constant of the gate insulating layer is preferably 3 to 30, more preferably 20.

[0053] In the present invention, the thickness of the gate insulating layer is preferably 100-150 nm, more preferably 130 nm.

[0054] After obtaining the gate insulating layer, the present invention prints a source electrode film layer and a drain electrode film layer on the upper surface of the boss of the gate insulating layer, the source electrode film layer and the drain electrode film layer are in contact, and the source electrode film layer and the drain electrode film layer are cured to form an initial source electrode and an initial drain electrode, and one end edge of the initial source electrode is in contact with one end edge of the initial drain electrode. In the present invention, the source electrode film and the drain electrode film layer are printed by a solution method. Due to the effect of interfacial tension, the end of the initial source electrode layer and the initial drain electrode layer obtained after curing that is in contact with each other is thinner than the main structure layer of the initial source electrode and the main structure layer of the initial drain electrode, such as Figure 3 shown.

[0055] In the present invention, the printing conditions of the source electrode film layer preferably include: the printing voltage is preferably 0.5 to 10V, more preferably 2V. The pulse frequency is preferably 10 to 60Hz, more preferably 30Hz. The first solution used for printing preferably includes a first printing material and a solvent. The first printing material preferably includes one or more of aluminum sec-butoxide, silver chloride and copper sulfate hydrate, more preferably aluminum sec-butoxide. The solvent is preferably an inorganic solvent or an organic solvent, more preferably an organic solvent. The present invention has no special requirements for the type of the organic solvent, as long as the source electrode film layer is printed normally. The molar concentration of the first printing material in the first solution is preferably 0.1 to 0.5 mol / mL, more preferably 0.3 mol / mL.

[0056] The present invention has no special requirements on the specific implementation method of curing the source electrode film layer.

[0057] In the present invention, the printing conditions of the drain electrode film layer preferably include: the printing voltage is preferably 0.5 to 10V, more preferably 2V, and the pulse frequency is preferably 10 to 60Hz, more preferably 30Hz. The first solution used for printing preferably includes a first printing material and a solvent. The first printing material preferably includes one or more of aluminum sec-butoxide, silver chloride and copper sulfate hydrate, more preferably aluminum sec-butoxide. The solvent is preferably an inorganic solvent or an organic solvent, more preferably an organic solvent. The present invention has no special requirements for the type of the organic solvent, as long as the drain electrode film layer is printed normally. The molar concentration of the first printing material in the first solution is preferably 0.1 to 0.5 mol / mL, more preferably 0.3 mol / mL.

[0058] The present invention has no special requirements on the specific implementation method of curing the drain electrode film layer.

[0059] In the present invention, the sheet resistance of the initial source electrode is preferably 10 -2 Ω / □~10 2 Ω / □, more preferably 10 -2 Ω / □.

[0060] In the present invention, the thickness of the initial source electrode is preferably 30 nm to 100 nm, more preferably 50 nm.

[0061] In the present invention, the sheet resistance of the initial drain electrode is preferably 10 -2 Ω / □~10 2 Ω / □, more preferably 10 -2 Ω / □.

[0062] In the present invention, the thickness of the initial drain electrode is preferably 30 nm to 100 nm, more preferably 50 nm.

[0063] In the present invention, the initial source electrode and the initial drain electrode are preferably made of the same material and have the same thickness.

[0064] After obtaining the initial source electrode and the initial drain electrode, the present invention uses a dry etching method to etch the entire surface of the initial source electrode and the initial drain electrode to form a source electrode, a drain electrode, and a channel between the source electrode and the drain electrode, and the length of the channel is ≤7μm. In the present invention, the dry etching is preferably plasma etching. The conditions of the dry etching preferably include: the etching gas preferably includes one or more of SF6, CF4, O2 and He. The etching gas is more preferably CF4 or O2. The radio frequency (RF) power of the etching is preferably 100~800W, more preferably 400W. The working gas pressure is preferably 0.1~10Pa, more preferably 0.4Pa. The etching time is preferably 50~400s, more preferably 260s. The length of the channel is preferably 2~5μm.

[0065] In the present invention, the thickness of the source electrode is preferably 30 nm.

[0066] In the present invention, the thickness of the drain electrode is preferably 30 nm.

[0067] After obtaining the source and drain electrodes, the present invention prints an active material film layer on the upper surface of the source electrode portion, the upper surface of the drain electrode portion, and within the channel. The active material film layer solidifies to form an active layer. In the present invention, the printing conditions for the active material film layer preferably include: the printing voltage is preferably 0.5 to 10V, more preferably 5V. The pulse frequency is preferably 10 to 60Hz, more preferably 40Hz. The third solution used for printing preferably includes a third printing material and a solvent. The third printing material preferably includes indium gallium oxygen and / or indium gallium zinc oxygen, more preferably indium gallium oxygen. The solvent is preferably an inorganic solvent or an organic solvent, more preferably an inorganic solvent. The present invention has no special requirements for the type of inorganic solvent, as long as the active material film layer is properly printed. The molar concentration of the third printing material in the third solution is preferably 0.03 to 0.5 mol / mL, more preferably 0.25 mol / mL.

[0068] The present invention has no special requirements on the specific implementation of the active material film layer solidification.

[0069] In the present invention, the Hall mobility of the active layer is preferably 0.5 to 150 cm 2 / Vs, more preferably 60cm 2 / Vs.

[0070] In the present invention, the thickness of the active layer is preferably 20-100 nm, more preferably 30 nm.

[0071] After obtaining the active layer, the present invention prints a second insulating film layer on the remaining upper surface of the gate insulating layer, the remaining upper surface of the source electrode, the upper surface of the active layer, and the remaining upper surface of the drain electrode. The second insulating film layer forms a passivation layer after curing. In the present invention, the printing conditions of the second insulating film layer preferably include: the printing voltage is preferably 0.5 to 10V, more preferably 5V. The pulse frequency is preferably 10 to 60Hz, more preferably 60Hz. The second solution used for printing preferably includes a second printing material and a solvent. The second printing material preferably includes one or more of hafnium oxychloride octahydrate and zirconium oxychloride hydrate, more preferably hafnium oxychloride octahydrate. The solvent is preferably an inorganic solvent or an organic solvent, more preferably an organic solvent. The present invention has no special requirements for the type of organic solvent, as long as the second insulating film layer can be printed normally. The molar concentration of the second printing material in the second solution is preferably 0.1 to 0.5 mol / mL, more preferably 0.3 mol / mL.

[0072] The present invention has no special requirements on the specific implementation of the curing of the second insulating film layer.

[0073] In the present invention, the passivation layer preferably comprises HfO x and / or ZrO x .

[0074] In the present invention, the relative dielectric constant of the passivation layer is preferably 3-30, more preferably 20.

[0075] In the present invention, the thickness of the passivation layer is preferably 100-150 nm, more preferably 130 nm.

[0076] The present invention provides a thin film transistor prepared by the preparation method described in the above technical solution. The structural diagram of the thin film transistor provided by the present invention is as follows Figure 6 As shown below. Figure 6 The structure of the thin film transistor provided by the present invention is described in detail. The thin film transistor provided by the present invention includes a substrate 100; a gate electrode layer 201 disposed on a portion of the upper surface of the substrate 100; a gate insulating layer 301 covering the remaining upper surface of the substrate 100 and the upper surface of the gate electrode layer 201, the gate insulating layer 301 having a protrusion formed in the region of the gate electrode layer; a source electrode 401b and a drain electrode 402b disposed on the upper surface of the protrusion of the gate insulating layer 301, a channel formed between the source electrode 401b and the drain electrode 402b, the length of the channel being ≤7μm; an active layer 501 disposed on a portion of the upper surface of the source electrode 401b, the channel, and the drain electrode 402b; and a passivation layer 601 disposed on the remaining upper surface of the gate insulating layer 301, the remaining upper surface of the source electrode 401b, the upper surface of the active layer 501, and the remaining upper surface of the drain electrode 402b.

[0077] In the present invention, the length of the channel is preferably 2 to 5 μm.

[0078] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] The following examples are based on Figure 7 The preparation process of the thin film transistor device is carried out.

[0080] Example 1:

[0081] After cleaning the glass substrate 100, a gate electrode film layer is printed. The printing voltage is 2V. The pulse frequency is 30Hz. The first solution used for printing includes a first printing material and a solvent. The first printing material is aluminum sec-butoxide. The solvent is an organic solvent, and the molar concentration of the first printing material in the first solution is 0.3 mol / mL. The gate electrode film layer is solidified to form a gate electrode layer 201 (such as Figure 1 The square resistance of the gate electrode is 10 -2 Ω / □. The thickness of the gate electrode is 50nm.

[0082] After obtaining the gate electrode layer, a first insulating film layer is printed on the remaining upper surface of the substrate 100 and the upper surface of the gate electrode layer 201, and the printing voltage is 5V. The pulse frequency is 60Hz. The second solution used for printing includes a second printing material and a solvent. The second printing material is hafnium oxychloride octahydrate. The solvent is an organic solvent. The molar concentration of the second printing material in the second solution is 0.3mol / mL. The first insulating film layer is cured to form a gate insulating layer 301, and the gate insulating layer 301 forms a boss in the gate electrode region (such as Figure 2 As shown). The material of the gate insulating layer is HfO x The relative dielectric constant of the gate insulating layer is 20. The thickness of the gate insulating layer is 130 nm.

[0083] After obtaining the gate insulating layer, the source electrode film layer and the drain electrode film layer are printed on the upper surface of the boss of the gate insulating layer. The source electrode film layer and the drain electrode film layer are in contact with each other, and the printing voltage is 2V. The pulse frequency is 30Hz. The first solution used for printing includes a first printing material and a solvent. The first printing material is aluminum sec-butoxide. The solvent is an organic solvent, and the molar concentration of the first printing material in the first solution is 0.3mol / mL. The source electrode film layer and the drain electrode film layer are solidified to form an initial source electrode 401a and an initial drain electrode 402a (such as Figure 3 As shown), one edge of the initial source electrode contacts one edge of the initial drain electrode. The sheet resistance of the initial source electrode is 10 -2 Ω / □. The thickness of the initial source electrode is 50nm. The sheet resistance of the initial drain electrode is 10-2 Ω / □. The initial thickness of the drain electrode is 50 nm.

[0084] After the initial source electrode and the initial drain electrode are obtained, the entire surface of the initial source electrode and the initial drain electrode is etched by plasma etching to form the source electrode 401b, the drain electrode 402b, and the channel between the source electrode 401b and the drain electrode 402b (such as Figure 4 (as shown), the channel length is 5 μm. The thickness of the source electrode 401b and the drain electrode 402b is 30 nm. The etching gas used in the plasma etching is CF4 or O2. The radio frequency (RF) power of the etching is 400 W. The working gas pressure is 0.4 Pa. The etching time is 260 s.

[0085] After obtaining the source electrode and drain electrode,

[0086] The active material film layer is printed on the surface and in the groove, and the printing voltage is 5V. The pulse frequency is 40Hz. The third solution used for printing preferably includes a third printing material and a solvent. The third printing material is indium gallium oxide. The solvent is preferably an inorganic solvent. The molar concentration of the third printing material in the third solution is 0.25 mol / mL. The active material film layer is solidified to form an active layer 501 (such as Figure 5 The Hall mobility of the active layer is 60 cm 2 / Vs. The thickness of the active layer is 30nm.

[0087] After obtaining the active layer, a second insulating film layer is printed on the remaining upper surface of the gate insulating layer, the remaining upper surface of the source electrode, the upper surface of the active layer, and the remaining upper surface of the drain electrode. The printing voltage is 5V. The pulse frequency is 60Hz. The second solution used for printing includes a second printing material and a solvent. The second printing material is hafnium oxychloride octahydrate. The solvent is an organic solvent. The molar concentration of the second printing material in the second solution is 0.3 mol / mL. The second insulating film layer is cured to form a passivation layer 601 (such as Figure 6 As shown). The material of the passivation layer is HfO x The relative dielectric constant of the passivation layer is 20. The thickness of the passivation layer is 130 nm.

[0088] Figure 8 The transfer characteristic curve of the thin film transistor device prepared in Example 1. Figure 8 It can be seen from the transfer characteristic curve that the device prepared in Example 1 has device electrical characteristics of on-off ratio, mobility and subthreshold swing.

[0089] From the above embodiments, it can be seen that the present invention utilizes plasma-assisted etching to solve the technical problem of low resolution in existing printing preparation technology, and further utilizes plasma to modify the surface of the channel interface, improve surface characteristics, and enhance the electrical performance of the device.

[0090] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a thin film transistor, characterized in that: The following steps are involved: Printing a gate electrode film layer on the upper surface of the substrate portion, wherein the gate electrode film layer is cured to form a gate electrode layer; Printing a first insulating film layer on the remaining upper surface of the substrate and the upper surface of the gate electrode layer, wherein the first insulating film layer is cured to form a gate insulating layer, and the gate insulating layer forms a boss in the gate electrode region; Printing a source electrode film layer and a drain electrode film layer on the upper surface of the boss of the gate insulating layer, wherein the source electrode film layer contacts the drain electrode film layer, and the source electrode film layer and the drain electrode film layer form an initial source electrode and an initial drain electrode after being cured, wherein one end edge of the initial source electrode contacts one end edge of the initial drain electrode; The entire surface of the initial source electrode and the initial drain electrode is etched by dry etching to form the source electrode, the drain electrode, and a channel between the source electrode and the drain electrode, wherein the length of the channel is ≤7 μm; Printing an active material film layer on the upper surface of the source electrode portion, the upper surface of the drain electrode portion and in the channel, wherein the active material film layer forms an active layer after being cured; A second insulating film layer is printed on the remaining upper surface of the gate insulating layer, the remaining upper surface of the source electrode, the upper surface of the active layer and the remaining upper surface of the drain electrode, and the second insulating film layer forms a passivation layer after being cured.

2. The preparation method according to claim 1, characterized in that The dry etching is plasma etching; the conditions of the dry etching include: the etching gas includes one or more of SF6, CF4, O2 and He, the etching RF power is 100~800W, the working gas pressure is 0.1~10Pa, and the etching time is 50~400s.

3. The preparation method according to claim 1, characterized in that The printing conditions of the gate electrode film layer, the source electrode film layer or the drain electrode film layer include: a printing voltage of 0.5 to 10 V and a pulse frequency of 10 to 60 Hz; the first solution used for printing includes a first printing material and a solvent, the first printing material includes one or more of aluminum sec-butoxide, silver chloride and copper sulfate hydrate, and the molar concentration of the first printing material in the first solution is 0.1 to 0.5 mol / mL.

4. The preparation method according to claim 1 or 3, characterized in that The square resistance of the gate electrode, the source electrode or the drain electrode is 10 -2 Ω / □~10 2 Ω / □; The thickness of the gate electrode, the source electrode or the drain electrode is 30 nm to 100 nm.

5. The preparation method according to claim 1, characterized in that The printing conditions of the first insulating film layer or the second insulating film layer include: a printing voltage of 0.5 to 10 V and a pulse frequency of 10 to 60 Hz; the second solution used for printing includes a second printing material and a solvent, the second printing material includes one or more of hafnium oxychloride octahydrate and zirconium oxychloride hydrate, and the molar concentration of the second printing material in the second solution is 0.1 to 0.5 mol / mL.

6. The preparation method according to claim 1 or 5, characterized in that The relative dielectric constant of the gate insulating layer or the passivation layer is 3 to 30; The gate insulating layer or the passivation layer has a thickness of 100 to 150 nm.

7. The preparation method according to claim 1, characterized in that The printing conditions of the active material film layer include: a printing voltage of 0.5 to 10 V and a pulse frequency of 10 to 60 Hz; the third solution used for printing includes a third printing material and a solvent, the third printing material includes indium gallium oxide and / or indium gallium zinc oxide, and the molar concentration of the third printing material in the third solution is 0.03 to 0.5 mol / mL.

8. The preparation method according to claim 1 or 7, characterized in that The Hall mobility of the active layer is 0.5 to 150 cm 2 / Vs; The thickness of the active layer is 20-100 nm.

9. The preparation method according to claim 1, characterized in that The length of the channel is 2-5 μm.

10. A thin film transistor prepared by the method according to any one of claims 1 to 9.

Images