阅读说明：本技术 复合金属氧化物半导体及薄膜晶体管与应用 (Composite metal oxide semiconductor, thin film transistor and application ) 是由 徐苗 徐华 吴为敬 陈为峰 王磊 彭俊彪 于 2019-09-18 设计创作，主要内容包括：本发明公开了复合金属氧化物半导体,该复合金属氧化物半导体为金属氧化物中掺有稀土氧化物,该复合金属氧化物可以在较低的氧化镱或氧化镨掺杂浓度下,有效抑制薄膜中的氧空位浓度,同时,其迁移率可以保持在较高的值；关键的,形成的薄膜能避免光照对I-V特性和稳定性的影响,大幅度提高金属氧化物半导体器件在光照下的稳定性。本发明还提供基于该复合金属氧化物半导体的薄膜晶体管与应用。(The invention discloses a composite metal oxide semiconductor, which is formed by doping rare earth oxide in metal oxide, wherein the composite metal oxide can effectively inhibit the concentration of oxygen vacancy in a film under the lower doping concentration of ytterbium oxide or praseodymium oxide, and meanwhile, the mobility of the composite metal oxide semiconductor can be kept at a higher value; the formed film can avoid the influence of illumination on I-V characteristics and stability, and greatly improve the stability of the metal oxide semiconductor device under illumination. The invention also provides a thin film transistor based on the composite metal oxide semiconductor and application thereof.)

1. The composite metal oxide semiconductor is characterized in that the composite metal oxide semiconductor is formed by doping rare earth oxide into metal oxide;

the metal oxide is a metal oxide semiconductor formed by indium oxide and one or two of zinc oxide and gallium oxide; the rare earth oxide is praseodymium oxide and/or ytterbium oxide; the mole ratio of praseodymium and/or ytterbium to the metal oxide in the rare earth oxide is 0.002-0.4: 1;

the composite metal oxide semiconductor has a photogenerated carrier fast recombination center.

2. The composite metal oxide semiconductor according to claim 1, wherein the metal oxide is a composite metal oxide of indium oxide and one of zinc oxide and gallium oxide, and a molar ratio of indium to zinc or gallium is in a range from 5:1 to 4.

3. The composite metal oxide semiconductor according to claim 1, wherein the metal oxide is a composite metal oxide formed of zinc oxide, gallium oxide, and indium oxide, and the atomic ratio relationship of the three metal elements In, Ga, and Zn is as follows: In/(In + Zn) is not less than 0.76, Ga/In is not less than 0 and not more than 0.8.

4. The composite metal oxide semiconductor according to claim 1, wherein a doping molar ratio of praseodymium and/or ytterbium to the metal oxide is 0.02 to 0.40: 1.

5. The composite metal oxide semiconductor according to claim 1, wherein a doping molar ratio of praseodymium and/or ytterbium to the metal oxide is 0.10 to 0.20: 1.

6. A thin film transistor comprising an active layer, wherein the active layer is prepared from the composite metal oxide semiconductor according to any one of claims 1 to 5 by a physical vapor deposition process, a chemical vapor deposition process, an atomic layer deposition process, a laser deposition process, or a solution method;

the starting voltage of the thin film transistor is changed to △ V under the illumination and non-illumination conditions_onThe amount is less than 2V.

7. The thin film transistor according to claim 6, wherein the active layer is formed by a magnetron sputtering process, a sputtering pressure is 0.1 to 0.6Pa, an oxygen volume ratio in a sputtering atmosphere is 10 to 50%, and a substrate temperature is from room temperature to 300 ℃.

8. The thin film transistor of claim 6, further comprising a substrate, a gate electrode, a gate insulating layer, a source drain electrode, and a passivation layer, wherein the thin film transistor employs an etch-stop type structure, a back channel etch type structure, or a self-aligned type structure.

9. The thin film transistor according to claim 8, wherein the passivation layer is a silicon oxide thin film, or a stacked structure of silicon nitride and silicon oxide.

10. Use of the thin film transistor of claim 6 in a display panel or a detector.

Technical Field

The invention relates to the field of semiconductor manufacturing, in particular to a material and a device structure for manufacturing a metal oxide semiconductor thin film transistor backboard in flat panel display and detector application, and specifically relates to a composite metal oxide semiconductor, a thin film transistor and application.

Background

In the existing metal oxide semiconductor system³⁺The 5s orbit of the ion is the main electron transport channel. However, since the bond breaking energy after the In ion is bonded to the O ion is low, the In ion is pure In₂O₃A large number of oxygen vacancy defects are present in the film. And oxygen vacancies are a major cause of deterioration in the stability of the metal oxide thin film transistor. Usually, doping and In are required³⁺Ga of equivalent ion number³⁺The ions regulate and control oxygen vacancies.

Meanwhile, in order to ensure the performance uniformity of the semiconductor device, the metal oxide semiconductor thin film is required to maintain an amorphous thin film structure. Crystal structure of ZnO and In₂O₃And Ga₂O₃The crystal structures of the two materials are different greatly, so that Zn ions with the amount equivalent to that of In ions are doped into the film, the crystallization of the materials can be inhibited, and the amorphous structure of the film can be maintained. Therefore, IGZO (In: Ga: Zn ═ 1:1:1mol) is the most widely used metal oxide semiconductor material at present. However, IGZO has a problem that Ga is³⁺And Zn²⁺The large amount of ions is added to greatly dilute In³⁺And thus the overlapping degree of the 5s orbitals is reduced, and the electron mobility is lowered.

In addition, IGZO and the like materials have a large number of trap states near the valence band. This results in the generation of photogenerated carriers even when the illumination energy is lower than the forbidden band width, and at the same time, the generation of photogenerated holes near the valence band. The photo-generated holes are easily injected into the gate insulating layer under the action of an electric field, so that the conventional oxide semiconductor has the problem of poor light stability.

Disclosure of Invention

In order to overcome the defects of the prior art, an object of the present invention is to provide a composite metal oxide semiconductor with relatively high mobility and strong light stability. The composite metal oxide semiconductor effectively inhibits the oxygen vacancy concentration in the film by doping a small amount of ytterbium oxide or praseodymium oxide rare earth oxide in the metal oxide, and simultaneously can form a composite center of a photon-generated carrier so as to improve the stability of the semiconductor under illumination.

The second objective of the present invention is to provide a thin film transistor comprising the composite metal oxide semiconductor.

The invention also provides the application of the thin film transistor.

One of the purposes of the invention is realized by adopting the following technical scheme:

a composite metal oxide semiconductor in which a rare earth oxide is doped in a metal oxide;

the metal oxide is a metal oxide semiconductor formed by indium oxide and one or two of zinc oxide and gallium oxide; the rare earth oxide is praseodymium oxide and/or ytterbium oxide; the mole ratio of praseodymium and/or ytterbium to the metal oxide in the rare earth oxide is 0.002-0.4: 1;

the composite metal oxide semiconductor has a photogenerated carrier fast recombination center.

The composite metal oxide semiconductor provided by the invention is an indium oxide-based composite semiconductor, and praseodymium oxide or ytterbium oxide can inhibit oxygen vacancies at a low doping amount, so that the semiconductor has high mobility and the stability of the semiconductor under the illumination condition is improved.

Further, the metal oxide is a composite metal oxide formed by indium oxide and one of zinc oxide and gallium oxide, and the molar ratio of indium to zinc or gallium is in the range of 5: 1-4. Illustratively, indium gallium oxide, such as In, may be selected₂O₃:Ga₂O₃As 5:4, with a mobility of 14.8cm in undoped condition²·V^-1·S^-1The mobility of the material is still maintained at 9.5cm after being doped with praseodymium or ytterbium in a molar ratio of 0.1²·V^-1·S^-1(ii) a Or indium zinc oxide, e.g. In₂O₃ZnO 2.5:1, which is higherMobility of greater than 50cm²·V^-1·S^-1It can be doped with up to 0.2 mole ratio of ytterbium or praseodymium, and the mobility is still 33cm²·V^-1·S^-1The above; on the basis of keeping higher current switching ratio, good stability and weaker photogenerated current characteristics can be obtained.

Further, the metal oxide semiconductor is a composite metal oxide formed by zinc oxide, gallium oxide and indium oxide, and the atomic proportion relationship of the three metal elements of In, Ga and Zn is as follows: In/(In + Zn) is not less than 0.76, Ga/In is not less than 0 and not more than 0.8. Illustratively, indium gallium zinc oxide may be selected, In: Ga: Zn ═ 3.170:1.585:1(mol), praseodymium oxide or ytterbium oxide may be doped at a molar ratio, and at up to 0.1 molar ratio of ytterbium or praseodymium oxide, the mobility is still higher than 10cm²·V^-1·S^-1(ii) a Or In Ga: Zn: 3.170:2.536:1 (mol).

More preferably, the doping molar ratio of praseodymium and/or ytterbium in the rare earth oxide to the metal oxide is 0.02-0.40: 1. in other words, in this doping range, praseodymium oxide or ytterbium oxide can be used to exhibit a preferable suppression of the photo-generated current characteristics, and at the same time, the metal oxide semiconductor can maintain a preferable mobility. More preferably, the rare earth oxide has a praseodymium and/or ytterbium doping molar ratio to the metal oxide of 0.10-0.20: 1. Within this range, the mobility of the composite metal oxide semiconductor is relatively high and the current on/off ratio is 10⁸About the order of magnitude of (A), and simultaneously, the light stability is very good.

The second purpose of the invention is realized by adopting the following technical scheme:

the thin film transistor comprises an active layer, wherein the active layer is prepared from the composite metal oxide semiconductor through a physical vapor deposition process, a chemical vapor deposition process, an atomic layer deposition process, a laser deposition process or a solution method.

Namely, the invention also provides a thin film transistor formed on the basis of an active layer made of the composite metal oxide semiconductor, and the thin film transistor has the starting voltage change of △ V under the illumination and non-illumination conditions_onLess than 2V or further, △ V_onLess than 1V.

Further, the active layer is prepared by a magnetron sputtering process, the sputtering pressure is 0.1-0.6Pa, the oxygen volume percentage in the sputtering atmosphere is 10-50%, and the substrate temperature is room temperature to 300 ℃. Specifically, a single-target sputtering or co-sputtering mode is adopted, and under the sputtering condition, an active layer with uniform texture, good adhesion and good film texture can be deposited.

Preferably, the active layer of the thin film transistor is prepared by adopting a single-target magnetron sputtering mode.

The thin film transistor further comprises a substrate, a grid electrode, a grid insulating layer, a source drain electrode and a passivation layer, wherein the thin film transistor adopts an etching blocking type structure, a back channel etching type structure or a self-aligning type structure.

Further, the passivation layer is a silicon oxide film or a laminated structure composed of silicon nitride and silicon oxide.

Further, the substrate may be a rigid alkali glass, alkali-free glass, quartz glass, and silicon substrate, or a flexible Polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), Polyethylene (PE), polypropylene (PP), Polystyrene (PS), Polyaluminium Ether (PEs), or foil.

Further, the gate electrode may be a transparent conductive oxide, graphene, a metal-oxide semiconductor stack, or a metal-metal stack. Wherein the transparent conductive oxide comprises ITO, AZO, GZO, IZO, ITZO and FTO; the metal-oxide semiconductor stack comprises ITO/Ag/ITO, IZO/Ag/IZO; the metal-metal stack comprises Mo/Al/Mo, Ti/Al/Ti.

The preparation method of the grid electrode can be a sputtering method, electroplating, thermal evaporation and other deposition modes, and the sputtering deposition mode is preferred because the prepared film has good adhesion with the substrate, excellent uniformity and can be prepared in a large area.

The gate insulating layer on the gate electrode may be one or more of silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, hafnium oxide, yttrium oxide, or a polymer organic film layer stacked on the gate insulating layer. The gate insulating layer may be formed by stacking a plurality of insulating films, so that the gate insulating layer has a better insulating property and an interface property between the active layer and the gate insulating layer is improved. Moreover, the gate insulating layer can be prepared in various ways, such as physical vapor deposition, chemical vapor deposition, atomic layer deposition, laser deposition, anodic oxidation or solution method.

In addition, it should be noted that, in the preparation of a device with a back channel etching structure, the source/drain electrode and the active layer need to have a proper etching selection ratio, otherwise, the preparation of the device cannot be realized. The better etching liquid is hydrogen peroxide water-based etching liquid, mainly because the metal oxide semiconductor material of the invention can effectively resist the etching of the wet hydrogen peroxide water-based etching liquid, the metal oxide semiconductor material and metal (such as molybdenum, molybdenum alloy, molybdenum/copper, titanium/copper and the like) have very high etching selection ratio, the metal oxide semiconductor layer is basically not influenced by the etching liquid, and the prepared device has excellent performance and good stability.

The third purpose of the invention is realized by adopting the following technical scheme:

the thin film transistor is applied to a display panel or a detector.

The principle of the invention is as follows:

the composite metal oxide semiconductor of the present invention is obtained by using a compound of oxygen and oxygen^2-The bonding energy between ions is as high as 753.0 (delta Hf298, kJ/mol) praseodymium oxide and 715.1 (delta Hf298, kJ/mol) ytterbium oxide to dope the indium oxide-based semiconductor, and compared with the traditional indium gallium zinc oxide semiconductor which needs to use gallium with large concentration to inhibit the oxygen vacancy concentration, the oxygen vacancy concentration in the oxide semiconductor film can be effectively controlled by only doping a small amount of rare earth ions. Therefore, under the condition of a considerable amount of oxygen vacancy concentration, the doping concentration can be greatly reduced, the overlapping degree of In ion 5s orbitals is favorably improved, and the mobility of the material is improved. Compared with the traditional IGZO material, the mobility is only 10cm²The novel praseodymium ion and ytterbium ion doped metal oxide semiconductor has the device mobility as high as 50cm²/vs。

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a praseodymium oxide or ytterbium oxide doped indium oxide semiconductor, which can effectively reduce oxygen vacancy in a film under relatively low doping concentration, and the indium oxide semiconductor can be indium zinc oxide, indium gallium oxide or indium gallium zinc oxide semiconductor; compared with the traditional indium gallium zinc oxide semiconductor, the mobility of the device is basically not influenced;

after the praseodymium oxide or the ytterbium oxide is doped in the composite metal oxide semiconductor, an impurity energy level is introduced near the Fermi level of an energy band, and a recombination center of a photon-generated carrier is formed in a range close to the Fermi level +/-0.3 eV. The recombination centers can provide a fast recombination channel of photon-generated carriers and avoid the influence on I-V characteristics and stability. Thereby greatly improving the stability of the metal oxide semiconductor device under illumination.

Drawings

Fig. 1 is a schematic view of the structures of thin film transistors of examples 9 and 10;

fig. 2 is a schematic structural view of a thin film transistor according to embodiment 11;

fig. 3 is a schematic structural view of a thin film transistor according to embodiment 12;

FIG. 4 is a graph showing the photo-generated current characteristics and the irradiation stability under negative bias in example 9;

FIG. 5 is a graph showing the photo-generated current characteristics and the negative bias light irradiation stability of example 10;

FIG. 6 is a graph showing the photo-generated current characteristics and the negative bias light irradiation stability of example 11;

FIG. 7 is a graph showing the photo-generated current characteristics and the negative bias light irradiation stability of example 12;

fig. 8 is a characterization of PL spectra and lifetime measurements for undoped (y 0) and doped (y 0.1) praseodymium indium gallium zinc oxide films from example 7;

in the figures, the various reference numbers: 01. a substrate; 02. a gate electrode; 03. a gate insulating layer; 04. an active layer; 05. etching the barrier layer; 06-1, a source electrode; 06-2, a drain electrode; 07. a passivation layer; 08. a buffer layer; 09. a spacer layer.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.

The following are specific examples of the present invention, and raw materials, equipments and the like used in the following examples can be obtained by purchasing them unless otherwise specified.