阅读说明：本技术 柔性InGaZnO薄膜晶体管制备方法 (Preparation method of flexible InGaZnO thin film transistor ) 是由 宋家琪 郑克丽 于 2020-10-29 设计创作，主要内容包括：本发明公开了一种柔性InGaZnO薄膜晶体管制备方法。包括：提供柔性PI衬底,在所述柔性PI衬底上依次形成缓冲层、ITO栅极、高K介质层,对所述高K介质层进行准分子激光退火,在所述高K介质层上形成InGaZnO有源层,通过光刻和显影工艺,在所述InGaZnO有源层上形成源极和漏极的光刻胶图形,对所述InGaZnO有源层进行准分子激光退火,在所述InGaZnO有源层上形成金属薄膜,通过光刻胶的剥离工艺形成源极和漏极。通过使用准分子激光退火,可实现纳米尺度下的局域性退火,对特定的薄膜区域实现温度提升,有效避免了全结构的热效应,降低柔性衬底材料玻璃化温度的限制。(The invention discloses a preparation method of a flexible InGaZnO thin film transistor. The method comprises the following steps: providing a flexible PI substrate, sequentially forming a buffer layer, an ITO grid electrode and a high-K dielectric layer on the flexible PI substrate, performing excimer laser annealing on the high-K dielectric layer, forming an InGaZnO active layer on the high-K dielectric layer, forming photoresist patterns of a source electrode and a drain electrode on the InGaZnO active layer through photoetching and developing processes, performing excimer laser annealing on the InGaZnO active layer, forming a metal film on the InGaZnO active layer, and forming the source electrode and the drain electrode through a photoresist stripping process. By using excimer laser annealing, the local annealing under the nanoscale can be realized, the temperature of a specific film region is increased, the heat effect of the whole structure is effectively avoided, and the limitation of the glass transition temperature of the flexible substrate material is reduced.)

1. The preparation method of the flexible InGaZnO thin film transistor is characterized by comprising the following steps:

providing a flexible PI substrate;

sequentially forming a buffer layer, an ITO grid and a high-K dielectric layer on the flexible PI substrate;

performing excimer laser annealing on the high-K dielectric layer;

forming an InGaZnO active layer on the high-K dielectric layer;

forming photoresist patterns of a source electrode and a drain electrode on the InGaZnO active layer through photoetching and developing processes;

performing excimer laser annealing on the InGaZnO active layer;

and forming a metal film on the InGaZnO active layer, and forming a source electrode and a drain electrode by a photoresist stripping process.

2. The method of claim 1, wherein the buffer layer is an aluminum oxide film formed by an atomic layer deposition process, and the thickness of the aluminum oxide film is 100 nm.

3. The method for preparing the flexible InGaZnO thin film transistor according to claim 2, wherein the ITO gate is an ITO thin film prepared by using a magnetron sputtering process, and the thickness of the ITO thin film is 100 nm.

4. The method for preparing a flexible InGaZnO thin film transistor according to claim 3, wherein the high-K dielectric layer is a high-K dielectric thin film prepared by a magnetron sputtering process, and the thickness of the high-K dielectric thin film is 40nm to 60 nm.

5. The method for preparing the flexible InGaZnO thin film transistor according to claim 4, wherein the InGaZnO active layer is an InGaZnO thin film prepared by using a magnetron sputtering process, the thickness of the InGaZnO thin film is 50nm, and the growth rate of the InGaZnO thin film is 1 nm/min.

6. The method of claim 5, wherein the metal film is a double metal layer structure formed using a thermal evaporation process.

Technical Field

The invention relates to the technical field of thin film transistors, in particular to a flexible InGaZnO thin film transistor and a preparation method thereof.

Background

Thin film transistors, as three-terminal electronic devices, are a common basic unit for many modern electronic devices, including: flexible displays, organic electroluminescent displays and lighting, chemical and biological sensors, flexible photovoltaics, flexible logic and storage, flexible batteries, wearable devices, and the like. However, the channel material of the traditional transistor is mostly monocrystalline siliconPolysilicon, amorphous silicon, etc. face development bottlenecks due to the intrinsic properties of the materials, and cannot meet the diversified requirements of future electronic devices. InGaZnO as a novel oxide semiconductor material has not only high electron mobility ()>50cm²V^-1s^-1) Also belonging to amorphous structure (crystallization temperature)>500 ℃) and the high light transmittance in the visible light band is suitable for diversified application scenes. In addition, InGaZnO has a lower defect state density in the forbidden band and still maintains normal TFT performance output at a radius of curvature of 13 μm. And finally, the preparation process of the InGaZnO material is compatible with the existing Si-based process, so that the production cost of an industrial chain can be greatly reduced.

The realization of high performance of InGaZnO thin film transistors in the related art generally relies on a high temperature annealing optimization process, such as: n2 anneal, NH3 anneal, and the like. The reason is that the secondary self-assembly of the InGaZnO material on the molecular layer surface can be promoted under the high-temperature condition, so that the higher film density and the smoother surface roughness are realized, and meanwhile, the interface state density of a channel transmission layer can be effectively reduced through the permeation of gas atoms, so that the carrier mobility is obviously improved. This optimization process has been widely demonstrated in InGaZnO thin film transistors based on rigid substrates, and the annealing temperature is centered at 400 to 500 ℃. However, in the flexible electronic device, the temperature of the annealing process of the flexible InGaZnO thin film transistor is less than 300 ℃ due to the limitation of the lower glass transition temperature of the flexible substrate material, and the optimization effect is greatly reduced.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a preparation method of a flexible InGaZnO thin film transistor, which realizes local annealing on a specific area, improves the optimization effect and avoids damage to a flexible substrate.

The preparation method of the flexible InGaZnO thin film transistor comprises the following steps: providing a flexible PI substrate; sequentially forming a buffer layer, an ITO grid and a high-K dielectric layer on the flexible PI substrate; performing excimer laser annealing on the high-K dielectric layer; forming an InGaZnO active layer on the high-K dielectric layer; forming photoresist patterns of a source electrode and a drain electrode on the InGaZnO active layer through photoetching and developing processes; performing excimer laser annealing on the InGaZnO active layer; and forming a metal film on the InGaZnO active layer, and forming a source electrode and a drain electrode by a photoresist stripping process.

The flexible InGaZnO thin film transistor provided by the embodiment of the invention at least has the following beneficial effects: by using excimer laser annealing, the local annealing under the nanoscale can be realized, the temperature of a specific film region is increased, the heat effect of the whole structure is effectively avoided, and the limitation of the glass transition temperature of the flexible substrate material is reduced.

According to some embodiments of the invention, the buffer layer is an aluminum oxide film prepared using an atomic layer deposition process, the aluminum oxide film having a thickness of 100 nm.

According to some embodiments of the invention, the ITO gate is an ITO thin film prepared using a magnetron sputtering process, and the thickness of the ITO thin film is 100 nm.

According to some embodiments of the invention, the high-K dielectric layer is a high-K dielectric film prepared by using a magnetron sputtering process, and the thickness of the high-K dielectric film is 40nm to 60 nm.

According to some embodiments of the present invention, the InGaZnO active layer is an InGaZnO thin film prepared using a magnetron sputtering process, the InGaZnO thin film has a thickness of 50nm, and a growth rate of the InGaZnO thin film is 1 nm/min.

According to some embodiments of the invention, the metal thin film is a double metal layer structure formed using a thermal evaporation process.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is a schematic diagram of a flexible InGaZnO thin film transistor structure according to an embodiment of the invention;

FIG. 2 is a schematic diagram of excimer laser annealing of a high-K dielectric layer according to an embodiment of the present invention;

fig. 3 is a schematic diagram of performing excimer laser annealing on an InGaZnO active layer according to an embodiment of the present invention.

Reference numerals:

the flexible substrate 110, the buffer layer 120, the ITO gate 130 and the high-K dielectric layer 140;

an InGaZnO active layer 150, a source electrode 160, a drain electrode 170, and a photoresist 180;

buffer metal layer 161, data metal layer 162.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Interpretation of terms:

the InGaZnO (indium Gallium Zinc oxide) is a novel semiconductor material, has higher electron mobility compared with amorphous silicon, and is used for preparing an active layer of a thin film transistor.

Ito (indium Tin oxide), indium Tin oxide, has better visible light transmittance and flexibility than a single metal material.

The high-K dielectric layer 140, a high-K dielectric layer, has good insulation properties and is typically made of nitride, metal oxide, or ferroelectric material.

Flexible pi (polyimide) substrates, polyimide substrates, are organic polymer materials and widely used as substrates in flexible displays.

In some embodiments of the present invention, referring to fig. 1, a method for manufacturing a flexible InGaZnO thin film transistor is provided, including: providing a flexible PI substrate, sequentially forming a buffer layer 120, an ITO gate 130 and a high-K dielectric layer 140 on the flexible PI substrate, performing excimer laser annealing on the high-K dielectric layer 140, forming an InGaZnO active layer 150 on the high-K dielectric layer 140, forming photoresist patterns of a source electrode 160 and a drain electrode 170 on the InGaZnO active layer 150 through photoetching and developing processes, performing excimer laser annealing on the InGaZnO active layer 150, forming a metal film on the InGaZnO active layer 150, and forming the source electrode 160 and the drain electrode 170 through a stripping process of photoresist 180.

Excimer laser annealing is to irradiate the surface of an annealing material with a laser beam with high energy density, so as to cause the temperature of an irradiated area to rise suddenly, and achieve the effect of annealing the irradiated area. Referring to FIG. 2, a schematic diagram of excimer laser annealing of the high-K dielectric layer 140 is shown, under a non-vacuum room temperature condition, ultra-short pulse ultraviolet (200nm-400nm) laser is used to perform energy density (10-1000 mJ/cm) on the surface of the high-K dielectric layer within a fixed time interval (0.005 mus-250 mus)²) In the annealing treatment, the high-K dielectric layer 140 absorbs the energy of the laser beam to raise the temperature of the high-K dielectric layer 140, so that the number of interface states of the high-K dielectric layer 140 is reduced, and the roughness of the interface layer is reduced, thereby remarkably improving the transmission characteristic of the thin film transistor, wherein the temperature rise starts from the high-K dielectric layer 140, and the temperature of the flexible PI substrate is lower than that of the high-K dielectric layer 140, so that the high-temperature damage to the flexible PI substrate is avoided.

Referring to fig. 3, a schematic diagram of performing excimer laser annealing on the InGaZnO active layer 150 is shown, where the annealing conditions of the excimer laser are the same as those of the high-K dielectric layer, and are not repeated here. The photoresist 180 for forming the pattern on the InGaZnO active layer 150 can absorb the energy of a part of excimer laser, namely, the region which does not need to be annealed can be shielded, the regional annealing effect is achieved, the lattice defect of the InGaZnO active layer 150 is repaired, and the performance and the stability of the flexible InGaZnO thin film transistor are optimized.

In some embodiments, the buffer layer 120 is an aluminum oxide film prepared using an atomic layer deposition process, and the thickness of the aluminum oxide film is 100 nm. After the preparation is finished, ultrasonic cleaning is carried out for 5min by using ethanol, acetone and deionized water in sequence, and finally, blow-drying is carried out by using nitrogen to remove substances with weak surface adhesion. The atomic layer deposition process can plate substances on the surface of the substrate layer by layer in the form of a monoatomic film, and has excellent deposition uniformity and consistency. In some other embodiments, the film can be prepared by a magnetron sputtering process, and the thickness of the aluminum oxide film can be set arbitrarily according to the device preparation requirements.

In some embodiments, the ITO gate 130 is an ITO thin film prepared using a magnetron sputtering process, and the thickness of the ITO thin film is 100 nm. The magnetron sputtering process has the advantages of high deposition speed, low substrate temperature rise and small damage to the film layer. In some other embodiments, the ITO gate 130 may be prepared by chemical vapor deposition, pulsed laser deposition, and the like, and the thickness of the ITO thin film may be set arbitrarily according to the requirements of the device design.

In some embodiments, the high-K dielectric layer 140 is a high-K dielectric film prepared by a magnetron sputtering process, the thickness of the high-K dielectric film is 40nm to 60nm, and the high-K dielectric film is annealed in a nitrogen atmosphere. Specifically, the annealing temperature in nitrogen is less than 300 ℃, the time duration is 10-30 min, and the gas flow is 500 mL/min. The high-K dielectric layer 140 has good insulation property, and is generally made of nitride, metal oxide or ferroelectric material, and the preparation process thereof can be flexibly changed according to the selection of the material, such as preparation of silicon nitride by gel vapor deposition, preparation of ferroelectric material by molecular beam epitaxy, and the like.

In some embodiments, the InGaZnO active layer 150 is an InGaZnO film prepared using a magnetron sputtering process, the InGaZnO film has a thickness of 50nm, and the growth rate of the InGaZnO film is 1 nm/min. The InGaZnO films generated at different sputtering speeds in the magnetron sputtering process have different qualities, which can affect the resistivity of the InGaZnO films. In other embodiments, different film growth rates can be selected according to actual requirements.

In some embodiments, the metal film is a two-metal layer structure formed using a thermal evaporation process. The buffer metal layer 161 and the data metal layer 162 are included, for example, the buffer metal layer 161 on the source electrode 160 is made of titanium, and the data metal layer 162 is made of gold. In other embodiments, the buffer metal layer 161 may be mo, and the data metal layer 162 may be al, cu, or an alloy thereof. The composition of the drain 170 is the same as that of the source 160, and thus is not described in detail.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.