CN117457753A - Double-active-layer terbium-doped oxide thin film transistor and preparation method thereof - Google Patents

Double-active-layer terbium-doped oxide thin film transistor and preparation method thereof Download PDF

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CN117457753A
CN117457753A CN202311546351.8A CN202311546351A CN117457753A CN 117457753 A CN117457753 A CN 117457753A CN 202311546351 A CN202311546351 A CN 202311546351A CN 117457753 A CN117457753 A CN 117457753A
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active layer
thin film
layer
terbium
film transistor
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吴丽君
覃雪峰
陈淑娇
徐志福
何鹏辉
廖蕾
邹旭明
刘兴强
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Zhangzhou Heqi Target Technology Co ltd
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Zhangzhou Heqi Target Technology Co ltd
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    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
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    • H01L29/7869—Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
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    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
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    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/78696—Thin film transistors, i.e. transistors with a channel being at least partly a thin film characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel

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Abstract

The invention provides a double-active-layer oxide thin film transistor with good NBIS stability and a preparation method thereof. The invention fully exerts the characteristics of high oxygen binding energy and low charge transfer transition energy of terbium elements, improves the electrical property and stability of the oxide thin film transistor by doping a small amount of terbium elements, adopts two layers of oxide semiconductor thin films with different terbium element contents to build a double-active-layer channel by stacking layer by layer, and realizes the improvement of the carrier mobility and stability of the oxide TFT by precisely controlling the components of the active-layer oxide semiconductor thin film materials.

Description

Double-active-layer terbium-doped oxide thin film transistor and preparation method thereof
Technical Field
The invention belongs to the technical field of microelectronics, in particular to a semiconductor technology, and particularly relates to a terbium-doped oxide transistor with a double active layer and good negative bias illumination stress (negative bias illumination stress, NBIS) and a preparation method thereof.
Background
Thin film transistors (Thin Film Transistor, TFT) have received widespread attention as core devices for display driving. In the back panel driving technology which is commercially applied at present, the field effect mobility of the amorphous silicon TFT is low, and the amorphous silicon TFT cannot meet the requirement of novel display driving. The oxide TFT has high mobility, good large-area uniformity and extremely low off-state current, and provides support for novel high-resolution and low-power consumption display technology.
Conventional InGaZnO TFTs require the incorporation of a large amount of Ga element to suppress carrier concentration in the semiconductor and adjust the threshold voltage. However, since the radii of Ga ions and In ions are greatly different, the large amount of Ga doped affects the overlap of the In ion 5s electron orbitals, resulting In a serious decrease In TFT carrier mobility. More importantly, the oxide TFT can have serious threshold voltage negative drift, even subthreshold swing increase and the like under the action of continuous Negative Bias Illumination Stress (NBIS), and can not be recovered within a few days after the bias stress is removed. This directly results in an increase in the difficulty of designing the compensation circuit in the TFT driving backplate, and increases the manufacturing cost of the AMOLED display.
Therefore, how to improve the carrier mobility and NBIS stability of oxide TFTs has become a problem to be solved at present.
Disclosure of Invention
In order to solve the above problems, the present invention provides a dual active layer oxide thin film transistor and a method for manufacturing the same, and the dual active layer oxide thin film transistor manufactured according to the present invention has the advantages of high mobility, high stability, etc.
According to the invention, two layers of terbium-doped oxide films with different terbium element contents are adopted to construct a double-active-layer channel so as to improve the carrier mobility of an oxide TFT device. Specifically, the terbium-doped oxide film with high terbium content is used as a top channel layer, so that the photoionization of oxygen vacancies in an active layer under NBIS is inhibited, the influence of external water oxygen adsorption on a bottom channel layer for high-speed carrier transmission is reduced, the NBIS stability of a TFT device is improved, and further the oxide TFT with high mobility and high stability is realized.
The above object of the present invention is achieved by the following technical means:
in a first aspect, the present invention provides a dual active layer oxide thin film transistor, the dual active layer oxide thin film transistor including a first active layer and a second active layer, wherein an oxide semiconductor thin film terbium element content of the first active layer is 0 at% to 5 at%; the terbium element content of the oxide semiconductor film of the second active layer is 5 at% to 15 at%, and the terbium element content of the film of the first active layer is smaller than that of the film of the second active layer.
Preferably, the dual active layer oxide thin film transistor is sequentially provided with a substrate, a gate electrode, a gate insulating layer, a first active layer, a second active layer and a source/drain electrode.
Preferably, the terbium-doped oxide semiconductor thin film component in the first active layer and/or the second active layer comprises (InO) x (MO) y (TbO) z Wherein terbium is present in the form of a trivalent ion, a tetravalent ion, or a mixed valence state.
Preferably, the Tb content of the first active layer is 3 at%.
Preferably, the Tb content of the second active layer is 10 at%
Preferably, M is one or a combination of any two elements of Li, zn and Sn.
Preferably, the first active layer is a bottom channel layer, and the second active layer is a top channel layer.
Preferably, the oxide semiconductor thin film thickness of the first active layer is 2 nm to 20 nm; the oxide semiconductor film thickness of the second active layer is 5nm to 50 nm.
Preferably, the first active layer film thickness is smaller than the second active layer film thickness.
Preferably, the carrier mobility of the double active layer oxide thin film transistor is as high as 40 cm 2 A switch current ratio of higher than 10 8 The negative drift value of the threshold voltage under the action of NBIS is less than 1V per hour.
Preferably, the thin film is prepared using vacuum methods including, but not limited to, sputtering, pulsed laser deposition, atomic layer deposition, chemical vapor deposition.
Preferably, the film is prepared using a solution process including, but not limited to, spin coating, ink jet printing, screen printing, knife coating, stamping.
On the other hand, the invention also provides a preparation method of the double-active-layer oxide thin film transistor, which specifically comprises the following steps:
step S1: preparing a gate electrode and a gate insulating layer on the surface of the substrate;
step S2: preparing a precursor solution;
step S3: preparing a first active layer on the surface of one side, far away from the substrate, of the gate insulating layer, and preparing a second active layer on the surface of the first active layer;
step S4: preparing a source-drain electrode to obtain a TFT device;
the terbium element content of the first active layer film is smaller than that of the second active layer film; the preparation of the precursor solution in step S2 may be carried out at any step prior to use.
Preferably, step S2 includes preparing the first active layer and/or the second active layer using a solution method or a vacuum method.
Preferably, step S1 includes: preparing one or more layers of conductive films by adopting a physical vapor deposition method, and patterning by adopting a hollowed-out mask or photoetching method to obtain a gate electrode; the insulating layer is prepared by adopting anodic oxidation, thermal oxidation, physical vapor deposition or chemical vapor deposition, and is patterned by a hollowed-out mask or photoetching method.
Preferably, one or more layers of conductive films are prepared by adopting a vacuum evaporation or sputtering method, and the source electrode and the drain electrode are obtained through patterning by a hollowed-out mask or photoetching method.
Compared with the prior art, the invention has the following advantages and beneficial effects:
the invention provides a Tb doped oxide thin film transistor with a double active layer and high mobility and high stability and a preparation method thereof.
According to the invention, a double-active-layer channel is constructed by stacking two terbium-doped oxide films with different terbium element contents and film thicknesses layer by layer, wherein the terbium-doped oxide film with low terbium content and low film thickness is used as a bottom channel layer, and the terbium-doped oxide film with high terbium content and high film thickness is used as a top channel layer. By precisely controlling the material composition of the channel layer and the thickness of the film, the mobility and stability of the oxide TFT carrier are improved.
The invention adopts the terbium-doped oxide film with high terbium content as the top channel layer, inhibits the photoionization of oxygen vacancies in the active layer under NBIS, reduces the influence of external water oxygen adsorption on the bottom channel layer for high-speed carrier transmission, improves the NBIS stability of the TFT device, and further realizes the oxide TFT with high mobility and high stability.
The terbium-doped oxide thin film transistor with double active layers prepared by the method has the carrier mobility as high as 40 cm 2 Vs, switching current ratio higher than 10 8 And the negative drift value of the threshold voltage under the action of NBIS is less than 1V per hour.
The preparation method directly adopts a sol-gel method, has simple process, low requirement on experimental conditions, high controllable degree, low cost, large-area mass production and high repeatability, and meets the environmental requirement.
Drawings
FIG. 1 is a schematic diagram of a dual active layer oxide thin film transistor device with good NBIS stability prepared by the present invention;
FIG. 2 is a graph showing the transfer characteristics of a dual active layer terbium doped oxide thin film transistor according to one embodiment of the present invention;
FIG. 3 is a transfer characteristic of a single active layer terbium-doped oxide thin film transistor prepared in accordance with comparative example one of the present invention;
FIG. 4 is a transfer characteristic of a single active layer terbium-doped oxide thin film transistor prepared in comparative example two of the present invention;
FIG. 5 is a graph showing the amount of drift of device threshold voltage with stress applied time for NBIS (a) and PBIS (b) of terbium-doped oxide thin film transistors with dual active layers prepared in example one of the present invention and single active layers prepared in comparative example;
FIG. 6 is a transfer characteristic of a dual active layer terbium doped oxide thin film transistor prepared in accordance with example two of the present invention;
fig. 7 is a transfer characteristic curve of a dual active layer terbium-doped oxide thin film transistor prepared in accordance with example three of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
Example 1
Fig. 1 is a schematic diagram of a TFT device with good NBIS stability obtained by the method for manufacturing a double active layer oxide thin film transistor according to the present invention.
The cross-sectional schematic diagram of the double active layer oxide thin film transistor is shown in fig. 1, and a substrate 10, a gate electrode 11, a gate insulating layer 12, a first active layer 13, a second active layer 14, a source electrode 15a and a drain electrode 15b are sequentially arranged.
The first embodiment of the invention provides a preparation method of a double-active-layer oxide thin film transistor with good NBIS stability, which comprises the following steps:
step S1: a gate electrode 11 and a gate insulating layer 12 are prepared on the surface of a substrate 10.
The step S1 specifically includes:
step S11: a layer of metal film is deposited on the surface of the cleaned substrate 10 by adopting a vacuum physical vapor deposition mode to serve as a gate electrode 11.
Preferably, the metal film is an Al metal film, and is patterned by ultraviolet lithography or wet etching.
Step S12: a gate insulating layer 12 is deposited on the surface of the gate electrode 11.
Preferably, an oxide is formed by anodic oxidation as an insulating layer, and surface treatment is performed by ultraviolet light or plasma; the anodized substrate was ultrasonically cleaned in deionized water and isopropyl alcohol, respectively, for 10 minutes, and dried in an oven at 70 c, followed by irradiation with ultraviolet light for 30 minutes.
Step S2: and (3) preparing a precursor solution.
The method comprises the steps of selecting metal salts of indium and terbium as precursors, mixing and dissolving in deionized water or an organic solvent, stirring at room temperature, and filtering before use.
Controlling the total molar concentration of all metal cations to be 0.01-0.5 mol/L, mixing different metal cations according to a specific proportion, respectively marking, marking low molar concentration and low terbium ion content as solution A, and marking high molar concentration and high terbium ion content as solution B.
Preferably, the "stirring at room temperature and filtration before use" step is specifically stirring vigorously at room temperature for 12 hours and filtering through a 0.22 μm filter head before use.
Specifically, in this example, the solution a used indium nitrate hydrate of 0.551, 0.551 g (In (NO 3 ) 3 ·nH 2 O, 0.0085g lithium nitrate hydrate LiNO 3 ·nH 2 O and terbium nitrate of 0.026gHydrate Tb (NO) 3 ) 3 ·nH 2 O is dissolved In deionized water of 10 mL to obtain precursor solution with total cation mole concentration of 0.2 mol/L and In to Li to Tb ion ratio of 92:5:3.
Solution B was prepared using 0.770g of indium nitrate hydrate (In (NO) 3 ) 3 nH2O, 0.026g lithium nitrate hydrate LiNO 3 nH2O and terbium nitrate hydrate Tb (NO) of 0.131g 3 ) 3 nH2O was dissolved In deionized water at 10 mL to give a precursor solution having a total cation molar concentration of 0.3 mol/L and an In: li: tb ion ratio of 85:5:10.
It is worth noting that the preparation step of the precursor solution belongs to a preparation step, which can be placed at any step before use.
Step S3: a first active layer 13 is prepared on the surface of the gate insulating layer 12 on the side away from the substrate 10, and a second active layer 14 is prepared on the surface of the first active layer 13.
The step S3 specifically includes:
step S31: the solution a is pre-grown on the surface of the gate insulating layer 12 by means of solution processing, the molar concentration of the solution is controlled to obtain a desired thickness, and annealing treatment is performed in an atmospheric environment to obtain a terbium-doped oxide film as the first active layer 13.
Preferably, the oxide semiconductor film thickness of the first active layer is 5nm.
Step S32: the first active layer 13 is surface-treated with ultraviolet light or plasma.
Specifically, the first active layer 13 is surface-treated by oxygen plasma cleaning (O-plasma), with a power of 100W and a time of 60 s.
Step S33: the solution B is pre-grown on the surface of the first active layer 13 in a solution processing mode, the molar concentration of the solution is controlled to obtain the required thickness, annealing treatment is carried out in an atmospheric environment to obtain a terbium-doped oxide film to obtain the second active layer 14, and the double-active-layer channel is patterned by ultraviolet lithography or wet etching.
Preferably, the solution B is pre-grown on the first active layer 13 by spin coating to obtain the second active layer 14.
Preferably, the oxide semiconductor film thickness of the second active layer is 7nm.
Further, the precursor solvent can be deionized water, ethylene glycol monomethyl ether or a mixed solution thereof, and the concentration of the precursor solution is 0.01-0.3 mol/L.
The solution processing technology is spin coating, spray coating or ink jet printing; the annealing treatment mode is photon sintering, laser annealing, microwave heating annealing or common heating annealing, and the annealing temperature is 150-500 ℃.
Preferably, the first active layer 13 is a bottom channel layer, and the second active layer 14 is a top channel layer.
Step S4: and preparing a source electrode and a drain electrode to obtain the TFT device.
And evaporating 80-nm-thick Al on the double active layers by using a mask patterning method to serve as a source electrode and a drain electrode, so as to obtain the TFT device.
The transfer characteristic curve of the terbium-doped oxide thin film transistor with the double active layers obtained through testing in the embodiment is shown in fig. 2, wherein the abscissa is the gate voltage, and the ordinate is the source leakage current; the curve test condition is the source/drain voltageV DS =15.1v, gate scan voltageV GS ＝-30～30V。
As shown by test results, the carrier mobility of the dual-active-layer terbium-doped oxide thin film transistor provided by the invention is as high as 40 cm 2 Vs, switching current ratio higher than 10 8 The threshold voltage is close to 0V, NBIS (negative bias illumination stress ) and PBIS (positive bias illumination stress, positive bias illumination stress) are good in stability, and the threshold voltage change value is smaller than 1V per hour.
In order to demonstrate the advantage of the dual active layer oxide thin film transistor provided by the present invention in terms of performance improvement, the present invention also provides two comparative examples (comparative example one and comparative example two) for comparing the electrical properties of the dual active layer terbium-doped oxide thin film transistor, which respectively prepare the single active layer terbium-doped oxide thin film transistor using the same precursor solution (a or B) and the preparation process as the embodiment of the present invention.
Comparative example one
The invention also provides a single active layer terbium-doped oxide thin film transistor as a comparative example I, and the specific preparation method of the single active layer terbium-doped oxide thin film transistor comprises the following steps:
(1) Precursor solution preparation: solution a used a certain amount of indium nitrate hydrate (In (NO 3 ) 3 ·nH 2 O, lithium nitrate hydrate LiNO 3 ·nH 2 O and terbium nitrate hydrate Tb (NO) 3 ) 3 ·nH 2 O is dissolved In deionized water to obtain a precursor solution with the total cation molar concentration of 0.2 mol/L, wherein the ratio of In to Li to Tb ions is 92:5:3. All solutions were vigorously stirred at room temperature for 12 hours and filtered through a 0.22 μm filter head prior to use.
(2) And depositing a layer of Al metal film on the surface of the cleaned glass by adopting a vacuum physical vapor deposition mode to serve as a gate electrode, and carrying out photoetching patterning. An oxide is then formed as an insulating layer by anodic oxidation.
(3) The anodized substrates were ultrasonically cleaned in deionized water and isopropyl alcohol, respectively, for 10 minutes and dried in an oven at 70 ℃. And then irradiated with ultraviolet light for 30 minutes.
And (3) pre-growing the solution A on the gate insulating layer in a spin coating mode, and then annealing in an atmospheric environment to obtain a terbium doped oxide film serving as a single channel layer, and patterning a single active layer channel by utilizing ultraviolet lithography and wet etching.
(4) And evaporating 80 nm thick Al on the double active layers by using a mask patterning method as a source-drain electrode to obtain the TFT device.
The transfer characteristic curve of the Tb doped single active layer thin film transistor with the concentration of 3 at% is shown in fig. 3, and the abscissa is the gate voltage and the ordinate is the source leakage current as shown in fig. 3; the curve test condition is the source/drain voltageV DS =15.1v, gate scan voltageV GS -30V. For a pair ofCompared with a dual active layer terbium doped oxide thin film transistor, the single active layer terbium doped oxide thin film transistor has carrier mobility of 19 cm 2 Vs, it can be seen that the single active layer terbium doped oxide thin film transistor has low mobility and poorer stability.
Comparative example two
As a comparative example II, a single active layer terbium-doped oxide thin film transistor, the specific preparation method of the single active layer terbium-doped oxide thin film transistor is as follows:
(1) Precursor solution preparation: solution B was prepared using 0.770g of indium nitrate hydrate (In (NO) 3 ) 3 ·nH 2 O, 0.026g lithium nitrate hydrate LiNO 3 ·nH 2 O and 0.131g terbium nitrate hydrate Tb (NO) 3 ) 3 ·nH 2 O is dissolved In deionized water of 10 mL to obtain precursor solution with total cation mole concentration of 0.3 mol/L and In to Li to Tb ion ratio of 85:5:10. All solutions were vigorously stirred at room temperature for 12 hours and filtered through a 0.22 μm filter head prior to use.
(2) And depositing a layer of Al metal film on the surface of the cleaned glass by adopting a vacuum physical vapor deposition mode to serve as a gate electrode, and carrying out photoetching patterning. An oxide is then formed as an insulating layer by anodic oxidation.
(3) The anodized substrates were ultrasonically cleaned in deionized water and isopropyl alcohol, respectively, for 10 minutes and dried in an oven at 70 ℃. Thereafter, the mixture was irradiated with ultraviolet light for 30 minutes. And pre-growing the solution B on the gate insulating layer in a spin coating mode, and then annealing in an atmospheric environment to obtain the terbium doped oxide film serving as a single channel layer, and patterning a single active layer channel by utilizing ultraviolet lithography and wet etching.
(4) And evaporating 80 nm thick Al on the double active layers by using a mask patterning method as a source-drain electrode to obtain the TFT device.
The transfer characteristic curve of the Tb doped single active layer thin film transistor with the concentration of 10 at% obtained through testing is shown in fig. 4, and the abscissa is the gate voltage and the ordinate is the source leakage current as shown in fig. 4; the curve test condition is the source/drain voltageV DS =15.1v, gate scan voltageV GS ＝-30～30V。
Compared with the dual-active layer terbium-doped oxide thin film transistor, the carrier mobility of the single-active layer terbium-doped oxide thin film transistor is 1.7 cm 2 The single active layer terbium doped oxide thin film transistor mobility is significantly lower.
For better comparison, the invention provides a performance comparison graph of the dual-active layer terbium-doped oxide thin film transistor and the single-active layer terbium-doped oxide thin film transistor.
FIG. 5 is a graph showing the amount of drift of the threshold voltage of the device with stress applied time for NBIS (a) and PBIS (b) of the dual active layer terbium-doped oxide thin film transistor prepared in example one of the present invention and the single active layer terbium-doped oxide thin film transistor prepared in comparative example one, wherein the abscissa indicates the duration of stress application and the ordinate indicates the threshold voltage variation; the curve test condition is the source/drain voltageV DS =0.1V gate voltageV GS = -20V, the illumination intensity is 1000 Lux.
From comparative example one and comparative example two, in the single active layer terbium-doped oxide thin film transistor, the low terbium-doped device has relatively high mobility, but NBIS stability is poor.
With the increase of terbium doping concentration in the active layer, the threshold voltage of the terbium doped oxide thin film transistor of the single active layer moves forward but the mobility is obviously reduced, which indicates that terbium doping can effectively inhibit the electron concentration in an oxide semiconductor, and the NBIS stability of the device is obviously improved, namely the threshold voltage change value of the device under the action of NBIS is smaller, as shown in fig. 5 (a); however, the high terbium doping concentration may cause an increase in the interface defect of the insulating layer/active layer, so that the stability of the device PBIS is deteriorated, i.e., the threshold voltage variation value of the device under the action of PBIS is greater, as shown in fig. 5 (b). Therefore, in the terbium-doped oxide thin film transistor with a single active layer, there is a significant constraint relationship between mobility and stability of the device.
In contrast, the dual active layer terbium doped oxide thin film transistor prepared using the same process in example one has higher electron mobility and better NBIS and PBIS stability. The first active layer 13 with low terbium doping concentration can provide a good insulating layer/active layer interface and a high-speed electron transport path, so that high PBIS stability and high electron mobility are realized; the second active layer 14 with high terbium doping concentration can improve the total terbium content of the active layer to promote the charge transfer transition of terbium ions and isolate water oxygen adsorption, so as to realize high NBIS stability. The first active layer and the second active layer have good interface characteristics, so that electron aggregation is promoted, and the electron mobility of the device is further improved.
Therefore, the invention adopts two layers of terbium-doped oxide films with different terbium element contents to build a double-active-layer channel by stacking layer by layer, thereby improving the carrier mobility and stability of the oxide TFT device.
The measurement result shows that the carrier mobility of the dual-active layer terbium-doped oxide thin film transistor provided by the invention is as high as 40 cm 2 Vs, switching current ratio higher than 10 8 The threshold voltage is close to 0V, the NBIS and the PBIS have good stability, and the change value of the threshold voltage under the action of the NBIS and the PBIS is smaller than 1V per hour.
From the above, it can be seen that the dual-active layer terbium-doped oxide thin film transistor has high electron mobility, large on-state current and low off-state current, and can realize high on-off current ratio, threshold voltage close to 0V and subthreshold swing of 0.3V/dec, which indicates that the dual-active layer terbium-doped oxide channel has good interface characteristics and low defect state density.
Example two
The second embodiment of the invention provides a preparation method of a dual-active layer terbium-doped oxide thin film transistor with high mobility and high stability, which comprises the following steps:
step S1: precursor solution configuration.
In this example, solution a was prepared using a certain amount of indium nitrate hydrate (In (NO 3 ) 3 ·nH 2 O, lithium nitrate hydrate LiNO 3 ·nH 2 O and terbium nitrate hydrate Tb (NO) 3 ) 3 ·nH 2 O is dissolved in deionized water to obtain a precursor with the total cation molar concentration of 0.2 mol/LThe ratio of In to Li to Tb ions of the precursor solution is 95:5:0.
Solution B employed a quantity of indium nitrate hydrate In (NO 3 ) 3 ·nH 2 O, lithium nitrate hydrate LiNO 3 ·nH 2 O and terbium nitrate hydrate Tb (NO) 3 ) 3 ·nH 2 O is dissolved In deionized water to obtain a precursor solution with the total cation molar concentration of 0.3 mol/L, and the ratio of In to Li to Tb ions is 85:5:10. All solutions were vigorously stirred at room temperature for 12 hours and filtered through a 0.22 μm filter head prior to use.
Step S2: and depositing a layer of Al metal film on the surface of the cleaned glass substrate 10 by adopting a vacuum physical vapor deposition mode to serve as a gate electrode 11, and carrying out photoetching patterning. An oxide is then formed as the gate insulating layer 12 by anodic oxidation.
Step S3: the anodized substrate was ultrasonically cleaned in deionized water and isopropyl alcohol, respectively, for 10 minutes, and dried in an oven at 70 c, followed by irradiation with ultraviolet light for 30 minutes.
Step S4: the solution a is pre-grown on the surface of the gate insulating layer 12 on the side far away from the substrate 10 by spin coating, and then annealed in an atmospheric environment to obtain the first active layer 13.
The thickness of the film obtained by controlling the molar concentration of the solution was 5nm.
Step S5: the first active layer 13 was surface treated with oxygen Plasma at a power of 100 a W a time of 60 a s a.
Step S6: the solution B is pre-grown on the first active layer 13 by adopting a spin coating mode, and then annealing treatment is carried out in an atmospheric environment, so that the second active layer 14 is obtained.
The thickness of the film is 7nm by controlling the molar concentration of the solution, and the double-active-layer channel is patterned by utilizing ultraviolet lithography technology and wet etching.
Step S7: and evaporating 80 nm thick Al on the double active layers by using a mask patterning method as a source-drain electrode to obtain the TFT device.
Test shows that the terbium-doped oxide thin film crystal with the double active layers in the embodiment is obtainedThe transfer characteristic curve of the tube is shown in fig. 6, the abscissa thereof is the gate voltage, and the ordinate thereof is the source leakage current; the curve test condition is the source/drain voltageV DS =15.1v, gate scan voltageV GS ＝-30～30V。
According to experimental measurement results, the carrier mobility of the dual-active-layer terbium-doped oxide thin film transistor provided by the invention is calculated to be as high as 47 cm 2 Vs, switching current ratio higher than 10 8 The NBIS and PBIS have good stability, and the threshold voltage variation value is less than 1V per hour.
Therefore, the dual-active layer terbium-doped oxide thin film transistor has high electron mobility, large on-state current and low off-state current, can realize high on-off current ratio and subthreshold swing of 0.3V/dec, and shows that the dual-active layer terbium-doped oxide channel has good interface characteristics and low defect state density.
Example III
The third embodiment of the invention provides a preparation method of a dual-active layer terbium-doped oxide thin film transistor with high mobility and high stability, which comprises the following steps:
step S1: a gate electrode 11 and a gate insulating layer 12 are prepared on the surface of a substrate 10.
The step S1 specifically includes:
step S11: and depositing a layer of metal film on the surface of the cleaned substrate 10 by adopting a vacuum physical vapor deposition mode to serve as a gate electrode 11, and carrying out photoetching patterning.
Preferably, the metal film Al metal film is patterned by ultraviolet lithography and wet etching.
Step S12: the gate insulating layer 12 is deposited and surface treated with ultraviolet light or plasma.
Preferably, an oxide is formed as an insulating layer by anodic oxidation; the anodized substrate was ultrasonically cleaned in deionized water and isopropyl alcohol, respectively, for 10 minutes, and dried in an oven at 70 c, followed by irradiation with ultraviolet light for another 30 minutes.
Step S3, preparing a first active layer 13 on the surface of the gate insulating layer 12 on the side far away from the substrate 10, and preparing a second active layer 14 on the first active layer 13.
The step S3 specifically includes:
step S31: a terbium doped oxide film of 5nm is deposited on the gate insulating layer 12 by a magnetron sputtering method to serve as the first active layer 13, and annealing treatment is carried out in an atmospheric environment. The target composition used for sputtering was InZnTbO, with a cationic molar ratio of In: zn: tb=15:4:1.
Step S32: and carrying out surface treatment on the bottom channel layer by adopting ultraviolet light or plasma.
Preferably, the first active layer 13 is surface treated with O-plasma at a power of 100W for a time of 60 s.
Step S33: a terbium doped oxide film of 10nm is deposited on the first active layer 13 by a magnetron sputtering method to serve as the second active layer 14, and annealing treatment is carried out in an atmospheric environment. The target composition used for sputtering was InZnTbO, with a cationic molar ratio of In: zn: tb=15:3:2. And patterning the double-active-layer channel by utilizing ultraviolet lithography and wet etching.
Preferably, the annealing treatment is photon sintering, laser annealing, microwave heating annealing or common heating annealing, and the annealing temperature is 150-500 ℃.
Step S4: and preparing a source electrode and a drain electrode to obtain the TFT device.
The transfer characteristic curve of the dual-active layer terbium-doped oxide thin film transistor obtained by testing in this embodiment is shown in fig. 7, and the carrier mobility of the dual-active layer terbium-doped oxide thin film transistor provided in the third embodiment of the invention is as high as 58 cm by testing and calculating 2 Vs, switching current ratio higher than 10 8 The NBIS and PBIS have good stability, and the threshold voltage variation value is less than 1V per hour.
In summary, the invention provides a dual-active layer Tb doped oxide thin film transistor with high mobility and high stability and a preparation method thereof, wherein the dual-active layer Tb doped oxide thin film transistor fully exerts the characteristics of terbium ion high oxygen combination energy and low charge transfer transition energy, and improves the electrical bias stability of a device by doping a small amount of terbium element.
According to the invention, a double-active-layer channel is constructed by stacking two terbium-doped oxide films with different terbium element contents and film thicknesses layer by layer, wherein the terbium-doped oxide film with low terbium content and low film thickness is used as a bottom channel layer, and the terbium-doped oxide film with high terbium content and high film thickness is used as a top channel layer. By precisely controlling the material composition of the channel layer and the thickness of the film, the mobility and stability of the oxide TFT carrier are improved.
The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims (10)

1. A double active layer oxide thin film transistor, characterized in that: the double-active-layer oxide thin film transistor comprises a first active layer and a second active layer, wherein the terbium element content of the oxide semiconductor thin film of the first active layer is 0 at to 5 at percent; the terbium element content of the oxide semiconductor film of the second active layer is 5 at% to 15 at%, and the terbium element content of the film of the first active layer is smaller than that of the film of the second active layer.
2. The dual active layer oxide thin film transistor of claim 1, wherein: the terbium-doped oxide semiconductor film component in the first active layer and/or the second active layer comprises (InO) x (MO) y (TbO) z Terbium is present in the form of trivalent ions, tetravalent ions or mixed valence states.
3. The double active layer oxide thin film transistor according to claim 2, wherein: and M is one or two elements selected from Li, zn and Sn.
4. The dual active layer oxide thin film transistor of claim 1, wherein: the first active layer is a bottom channel layer, and the second active layer is a top channel layer.
5. The dual active layer oxide thin film transistor of claim 1, wherein: the first active layer film thickness is less than the second active layer film thickness.
6. The dual active layer oxide thin film transistor of claim 1, wherein: the carrier mobility of the double active layer oxide thin film transistor exceeds 40 cm 2 /Vs。
7. The preparation method of the double-active-layer oxide thin film transistor is characterized by comprising the following steps of:
step S1: preparing a gate electrode and a gate insulating layer on the surface of the substrate;
step S2: preparing a precursor solution;
step S3: preparing a first active layer on the surface of one side, far away from the substrate, of the gate insulating layer, and preparing a second active layer on the surface of the first active layer;
step S4: preparing a source electrode and a drain electrode to obtain a double-active-layer oxide thin film transistor device;
the terbium element content of the first active layer film is smaller than that of the second active layer film; the step S2 may be placed at any step prior to use.
8. The method of claim 7, wherein step S2 comprises: the first active layer and/or the second active layer is prepared by a solution method or a vacuum method.
9. The method of claim 7, wherein step S1 comprises: preparing one or more layers of conductive films by adopting a physical vapor deposition method, and patterning by adopting a hollowed-out mask or photoetching method to obtain a gate electrode; the gate insulating layer is prepared by anodic oxidation, thermal oxidation, physical vapor deposition or chemical vapor deposition, and is patterned by a hollowed-out mask or photoetching method.
10. The method of claim 7, wherein step S4 comprises: and preparing one or more layers of conductive films by adopting a vacuum evaporation or sputtering method, and patterning by adopting a hollowed-out mask or photoetching method to obtain a source electrode and a drain electrode.
CN202311546351.8A 2023-11-20 2023-11-20 Double-active-layer terbium-doped oxide thin film transistor and preparation method thereof Pending CN117457753A (en)

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KR20140070344A (en) * 2012-11-30 2014-06-10 삼성전자주식회사 Semiconductor material, transistor including semiconductor material and electronic device including transistor
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CN109887991A (en) * 2019-02-25 2019-06-14 华南理工大学 A kind of lamination silicon doped stannum oxide thin film transistor (TFT) and preparation method thereof
CN115295564A (en) * 2022-09-27 2022-11-04 广州华星光电半导体显示技术有限公司 Array substrate and display panel

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KR20140070344A (en) * 2012-11-30 2014-06-10 삼성전자주식회사 Semiconductor material, transistor including semiconductor material and electronic device including transistor
CN106298958A (en) * 2016-10-13 2017-01-04 中山大学 Oxide thin film transistor and preparation method, display device and photographic means
CN107146816A (en) * 2017-04-10 2017-09-08 华南理工大学 A kind of oxide semiconductor thin-film and thin film transistor (TFT) prepared therefrom
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