A plasma treatment method for oxide semiconductor channel thin films

Abstract

This invention provides a plasma treatment method for oxide semiconductor channel thin films, comprising: preparing an amorphous oxide semiconductor channel thin film on a substrate to obtain an amorphous oxide semiconductor sample containing the channel thin film; placing the sample into the reaction chamber of a plasma device and evacuating the reaction chamber; introducing a reactive gas and an auxiliary gas into the evacuated reaction chamber; adjusting the input power and gas partial pressure of the plasma device for the first time to excite the reactive gas to ignite and generate plasma within the reaction chamber; and adjusting the input power and gas partial pressure of the plasma device for the second time within a preset first time threshold to change the density and energy of the plasma, thereby achieving plasma treatment of the amorphous oxide semiconductor channel thin film within the reaction chamber. This method utilizes oxygen exchange between oxygen plasma and the oxygen-containing amorphous oxide semiconductor thin film to reduce the hydrogen concentration in the channel and improve the quality of the amorphous oxide semiconductor channel.

Description

Technical Field

[0001] This invention relates to the fields of plasma and semiconductor technology, and specifically to a plasma processing method for oxide semiconductor channel thin films. Background Technology

[0002] Amorphous oxide semiconductors (AOS), such as amorphous indium gallium zinc oxide (a-IGZO), have important applications in thin-film transistors (TFTs) due to their excellent electron mobility and low processing temperature. However, currently, the fabrication process of AOS thin films inevitably introduces impurity hydrogen, which has multiple impacts on device performance. Low concentrations of hydrogen atoms can passivate interface defects, reduce subthreshold swing, and improve TFT characteristics; however, as the hydrogen concentration increases, it affects the negative bias stability of thin-film transistors, leading to threshold voltage drift and increased subthreshold swing.

[0003] To address these issues, existing technologies employ various post-treatment methods, such as room-temperature hydrogen plasma treatment and high-temperature H2 annealing. These methods use hydrogen as a dopant, increasing carrier concentration and improving device performance, but they introduce reliability problems, particularly high-temperature stability (>400℃). Therefore, minimizing the hydrogen concentration in the AOS thin film is an effective way to improve the long-term reliability of the device. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the aforementioned shortcomings, the main objective of this invention is to provide a plasma treatment method for oxide semiconductor channel thin films. This method utilizes the oxygen exchange phenomenon between oxygen plasma and oxygen-containing amorphous oxide semiconductor thin films to achieve the outward diffusion of hydrogen atoms, thereby reducing the hydrogen concentration in the channel and improving the quality of the amorphous oxide semiconductor channel.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides a plasma treatment method for oxide semiconductor channel thin films, comprising: preparing an amorphous oxide semiconductor channel thin film on a substrate to obtain an amorphous oxide semiconductor sample containing the channel thin film; placing the amorphous oxide semiconductor sample containing the channel thin film into the reaction chamber of a plasma device and evacuating the reaction chamber; introducing a reactive gas and an auxiliary gas into the evacuated reaction chamber; adjusting the input power and gas partial pressure of the plasma device for the first time to excite the reactive gas to ignite and generate plasma in the reaction chamber; and adjusting the input power and gas partial pressure of the plasma device for the second time within a preset first time threshold to change the density and energy of the plasma, thereby realizing the plasma treatment of the amorphous oxide semiconductor channel thin film in the reaction chamber.

[0008] In the above scheme, the reactant gas is oxygen, and the auxiliary gas is one or more of nitrogen and inert gases.

[0009] In the above scheme, the input power and gas partial pressure of the plasma device are adjusted for the first time to excite the reaction gas to ignite and generate plasma in the reaction chamber. This includes: exciting oxygen to ignite and generate oxygen plasma by adjusting the input power and oxygen partial pressure of the plasma device for the first time.

[0010] In the above scheme, the input power and gas partial pressure of the plasma device are adjusted a second time to change the density and energy of the plasma, thereby realizing plasma treatment of the amorphous oxide semiconductor channel film in the reaction chamber. This includes: changing the density and energy of the oxygen plasma by adjusting the input power and oxygen partial pressure of the plasma device a second time to obtain an oxygen-containing plasma environment; and realizing plasma treatment of the amorphous oxide semiconductor channel film by oxygen exchange between the oxygen plasma and the oxygen-containing amorphous oxide semiconductor film based on the oxygen-containing plasma environment.

[0011] In the above scheme, plasma is generated through excitation, and the excitation methods include microwave-excited plasma, inductively coupled plasma, cyclotron resonance-excited plasma, and radio frequency-excited plasma.

[0012] In the above scheme, the density and energy of the oxygen plasma are changed by second-order adjustment of the input power and oxygen partial pressure of the plasma device, thereby obtaining an oxygen-containing plasma environment. This includes: changing the density of the oxygen plasma and the ratio of oxygen exchange by adjusting the oxygen partial pressure.

[0013] In the above scheme, oxygen is excited to generate oxygen plasma, and the types of oxygen plasma excited include molecules, atoms and ions.

[0014] In the above scheme, amorphous oxide semiconductor channel films are prepared on the substrate by deposition or sputtering.

[0015] In the above scheme, the substrate is a material that does not react with oxide semiconductors. The substrate material includes silicon, silicon carbide, silicon on an insulating substrate, glass, and sapphire.

[0016] In the above scheme, the materials of the amorphous oxide semiconductor thin film include indium gallium zinc oxide, indium oxide, indium gallium oxide, zinc oxide, and indium tin oxide.

[0017] (III) Beneficial Effects

[0018] The technical solutions of the embodiments of the present invention have at least the following beneficial effects:

[0019] (1) Plasma is used for processing. Based on the oxygen exchange phenomenon between oxygen plasma and oxygen-containing amorphous oxide semiconductor thin film, the amorphous oxide semiconductor channel can be regarded as a dynamic exchange network, which is conducive to the diffusion of hydrogen atoms to the outside of the channel and reduces the hydrogen defects in the channel.

[0020] (2) Using oxygen-containing plasma for processing is different from the traditional approach of using thermal energy to achieve atomic diffusion, thus avoiding damage to the channel caused by high temperature.

[0021] (3) Using oxygen-containing plasma for treatment does not introduce external atoms into the oxide semiconductor channel, thus avoiding the introduction of new defects. Attached Figure Description

[0022] Figure 1 A flowchart of a plasma processing method for oxide semiconductor channel thin films according to an embodiment of the present invention is shown;

[0023] Figure 2 The illustration shows the use of an embodiment of the present invention. 18 Schematic diagram of the process of O plasma treatment of oxide semiconductor channel thin films;

[0024] Figure 3 The illustration shows an embodiment of the present invention. 18 The change in oxygen intensity in the channel film before and after O plasma treatment, characterized by secondary ion mass spectrometry.

[0025] Figure 4 The illustration shows an embodiment of the present invention. 18 The change in hydrogen intensity in the channel film before and after O plasma treatment, characterized by secondary ion mass spectrometry.

[0026] Figure 5 A schematic diagram of an IGZO bottom-gate TFT device according to an embodiment of the present invention is shown.

[0027] Figure 6 The diagram illustrates the change in threshold voltage stability of an oxide semiconductor device after oxygen plasma treatment according to an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] Figure 1 A flowchart of a plasma processing method for oxide semiconductor channel thin films according to an embodiment of the present invention is shown.

[0030] like Figure 1As shown, the plasma treatment method for oxide semiconductor channel thin films specifically includes operations S1 to S5.

[0031] In operation S1, an amorphous oxide semiconductor channel film is prepared on the substrate to obtain an amorphous oxide semiconductor sample containing the channel film.

[0032] In embodiments of the present invention, an amorphous oxide semiconductor channel film can be prepared on a substrate by deposition or sputtering to obtain an amorphous oxide semiconductor sample containing the channel film.

[0033] For example, the substrate is a material that does not react with oxide semiconductors, such as silicon, silicon carbide, silicon on an insulating substrate, glass, and sapphire.

[0034] For example, the materials of amorphous oxide semiconductor thin films can be indium gallium zinc oxide, indium oxide, indium gallium oxide, zinc oxide and indium tin oxide, etc.

[0035] In operation S2, an amorphous oxide semiconductor sample containing a channel thin film is placed into the reaction chamber of the plasma device, and the reaction chamber is evacuated.

[0036] In operation S3, the reaction gas and auxiliary gas are introduced into the vacuumed reaction chamber.

[0037] Specifically, after completing the above operation S1, the generated amorphous oxide semiconductor channel film is placed into the reaction chamber, and the reaction chamber is evacuated. After evacuation, the reaction gas and auxiliary gas are introduced.

[0038] For example, the reactant gas is oxygen, and the auxiliary gas is one or more of nitrogen and inert gases.

[0039] In operation S4, the input power and gas partial pressure of the plasma device are adjusted for the first time to excite the reactive gas to ignite and generate plasma in the reaction chamber.

[0040] Specifically, the ignition process is completed by first adjusting the input power and oxygen partial pressure of the plasma device to excite oxygen to ignite and generate oxygen plasma. The plasma is generated through excitation methods, such as microwave-excited plasma, inductively coupled plasma, cyclotron resonance-excited plasma, and radio frequency-excited plasma.

[0041] It should be noted that oxygen plasma is generated by exciting oxygen to produce oxygen plasma. The types of oxygen plasma that can be excited include molecules, atoms, and ions, all of which can reduce the hydrogen concentration in the channel.

[0042] In the embodiments of this invention, oxygen-containing plasma is used for processing, which differs from the traditional approach of using thermal energy to achieve atomic diffusion, thus avoiding damage to the channel caused by high temperatures. Using oxygen-containing plasma for processing does not introduce external atoms into the oxide semiconductor channel, avoiding the introduction of new defects.

[0043] In operation S5, within a preset first time threshold, the input power and gas partial pressure of the plasma device are adjusted a second time to change the density and energy of the plasma, thereby realizing plasma processing of amorphous oxide semiconductor channel thin films in the reaction chamber.

[0044] In embodiments of the present invention, plasma treatment of amorphous oxide semiconductor channel thin films is performed by adjusting parameters such as the input power of the plasma device, the gas partial pressure, and a preset processing time threshold.

[0045] Specifically, within a preset first time threshold, such as 3 minutes or 12 minutes, the input power and gas partial pressure of the plasma device are adjusted a second time to change the density and energy of the plasma, thereby realizing the plasma post-processing of the amorphous oxide semiconductor channel film. For example, this includes: changing the density and energy of the oxygen plasma by adjusting the input power and oxygen partial pressure of the plasma device a second time to obtain an oxygen-containing plasma environment; and based on the oxygen-containing plasma environment, realizing the plasma processing of the amorphous oxide semiconductor channel film by oxygen exchange between the oxygen plasma and the oxygen-containing amorphous oxide semiconductor film.

[0046] In an embodiment of the present invention, the density of oxygen plasma and the ratio of oxygen exchange are changed by adjusting the oxygen partial pressure.

[0047] In the embodiments of the present invention, plasma is used for processing. Based on the oxygen exchange phenomenon between oxygen plasma and oxygen-containing amorphous oxide semiconductor thin films, the amorphous oxide semiconductor channel thin film can be regarded as a dynamic exchange network, which is conducive to the diffusion of hydrogen atoms out of the channel and reduces channel hydrogen defects.

[0048] Based on the aforementioned plasma treatment method for oxide semiconductor channel films, this invention proposes an embodiment. In this embodiment, the high energy of atoms in an oxygen plasma environment is utilized to achieve dynamic atomic exchange, thereby reducing the hydrogen content in the AOS film. This solves the problems of diffusion and the introduction of doped atoms to passivate hydrogen defects in traditional thermal treatment, providing a new method for improving the quality of oxide semiconductor channel films in terms of process technology.

[0049] For example, firstly, an indium gallium zinc oxide (IGZO) thin film is prepared on the surface of a silicon oxide (SiO2 / Si) sample on a silicon substrate by sputtering for 40 minutes. IGZO is typically used as the channel material to obtain the channel film of the IGZO / SiO2 / Si sample. The IGZO / SiO2 / Si sample containing the channel film is then placed in a microwave plasma oxidation cavity, and the cavity is evacuated to a vacuum level of <10. -4 Pa range; isotopic oxygen is introduced into the cavity after vacuuming. 18 With O2 and a gas pressure of 1 kPa, after the gas supply is stopped, the microwave input power of the microwave plasma generator is first adjusted to 600 W. At this time, the microwave excites the isotope oxygen to glow, forming... 18 O plasma.

[0050] Furthermore, the microwave input power and reactant gas pressure of the microwave plasma generator are adjusted a second time, thereby changing... 18 The energy and density of O plasma. Utilizing 18 O plasma was used to post-process the IGZO / SiO2 / Si sample for 12 minutes. After the post-processing was completed, the microwave input power was turned off and the oxygen isotope was stopped.

[0051] Furthermore, secondary ion mass spectrometry characterization was performed on the IGZO / SiO2 / Si samples after and without microwave plasma post-treatment. Specifically, to verify whether oxygen exchange was achieved in the plasma-treated amorphous oxide semiconductor thin films described in the above embodiments, a detailed explanation follows.

[0052] This embodiment adopts 18 O2 isotope substitution routine 16 For example, O2 Figure 2 As shown, Figure 2 The illustration shows the use of an embodiment of the present invention. 18 A process diagram illustrating the O-plasma treatment of oxide semiconductor channel thin films. Silicon oxide (SiO2) is applied to a silicon substrate. 16 Indium gallium zinc oxide (IGZ) was prepared on the surface of the O2 / Si sample by sputtering. 16 O) film, then IGZ 16 O / Si 16 The O2 / Si sample was placed in a microwave plasma oxidation cavity, and the cavity was evacuated to a vacuum level of <10. -4 Within the Pa range, isotopic oxygen is introduced into the cavity after vacuuming. 18 With O2 and a gas pressure of 1 kPa, after the gas supply is stopped, the microwave input power of the microwave plasma generator is first adjusted to 600 W. At this time, the microwave excites the isotope oxygen to glow, forming... 18O-plasma. Furthermore, the microwave input power and reactant gas pressure of the microwave plasma generator are adjusted a second time, thereby changing... 18 The energy and density of O plasma. Utilizing 18 O plasma for IGZ 16 O / Si 16 The O2 / Si sample underwent post-processing for 12 minutes to obtain IGZ. 16，18 O / Si 16 After O2 / Si, turn off the microwave input power and stop the introduction of isotopic oxygen.

[0053] Figure 3 The illustration shows an embodiment of the present invention. 18 The graph shows the changes in oxygen intensity in the channel film before and after O plasma treatment, characterized by secondary ion mass spectrometry.

[0054] like Figure 3 As shown, without microwave plasma treatment, the IGZO thin film... 18 The strength of O is almost zero, while 16 The O intensity distribution is uniform, indicating that there is almost no O in the IGZO film. 18 O, all are made of 16 O composition; after microwave plasma treatment, the upper surface region of the IGZO thin film 18 O intensity increased significantly 16 O strength is significantly reduced. Therefore, as Figure 3 As shown, during microwave plasma treatment, oxygen exchange occurred in the IGZO thin film from the upper surface to the lower interface.

[0055] Figure 4 The illustration shows an embodiment of the present invention. 18 The graph shows the change in hydrogen intensity in the channel film before and after O plasma treatment, characterized by secondary ion mass spectrometry.

[0056] like Figure 4 As shown, the hydrogen intensity change after microwave plasma post-treatment reveals that the intensity of both OH and H ions in the IGZO film decreases after plasma treatment, demonstrating that plasma treatment facilitates the outward diffusion of hydrogen atoms and reduces the hydrogen concentration in the channels. It should be noted that the temperature during microwave plasma post-treatment in this embodiment is <300℃, far lower than the temperature required for high-temperature annealing.

[0057] Based on the plasma processing method for oxide semiconductor channel thin films described above, this invention proposes another embodiment.

[0058] For example, firstly, an indium gallium zinc oxide (IGZO) thin film is prepared on the surface of a silicon oxide (SiO2 / Si) sample on a silicon substrate by sputtering for 40 minutes. IGZO is typically used as the channel material to obtain the channel film of the IGZO / SiO2 / Si sample. The IGZO / SiO2 / Si sample containing the channel film is then placed in a microwave plasma oxidation cavity, and the cavity is evacuated to a vacuum level of <10. -4 Pa range; after the cavity is evacuated, oxygen is introduced into it at a pressure of 1 kPa. After the gas supply is stopped, the microwave input power of the microwave plasma generator is adjusted to 600 W for the first time. At this time, the microwave excites the isotope oxygen to glow, forming oxygen plasma.

[0059] Furthermore, the microwave input power and reactant gas pressure of the microwave plasma generator were adjusted a second time to change the energy and density of the oxygen plasma. The IGZO / SiO2 / Si sample was then post-treated using the oxygen plasma for 3 minutes. After the post-treatment, the microwave input power was turned off, and the oxygen supply was stopped.

[0060] In an embodiment of the present invention, indium tin oxide (ITO) electrodes were simultaneously sputtered onto IGZO / SiO2 / Si samples that had undergone microwave plasma post-treatment and those that had not, and positive and negative bias threshold stability tests were conducted.

[0061] Figure 5 A schematic diagram of an IGZO bottom-gate TFT device according to an embodiment of the present invention is shown. Figure 6 The diagram illustrates the change in threshold voltage stability of an oxide semiconductor device after oxygen plasma treatment according to an embodiment of the present invention.

[0062] like Figure 5 As shown, indium tin oxide (ITO) electrodes were sputtered onto IGZO / SiO2 / Si samples with and without microwave plasma post-treatment to obtain bottom-gate TFT devices. Threshold stability tests under positive and negative bias voltages were performed on the bottom-gate TFT devices with and without microwave plasma post-treatment.

[0063] like Figure 6 As shown, the threshold voltage offset of the bottom-gate TFT device after microwave plasma treatment is significantly reduced, indicating that microwave plasma treatment reduces the hydrogen concentration in the channel and improves the quality of the amorphous oxide semiconductor channel.

[0064] Through embodiments of the present invention, the oxygen exchange phenomenon between oxygen plasma and oxygen-containing amorphous oxide semiconductor thin films is utilized to promote the diffusion of hydrogen atoms out of the channel, thereby reducing hydrogen defects in the channel. Furthermore, embodiments of the present invention break through conventional methods of hydrogen atom removal, avoiding new defects caused by high temperatures and the introduction of exogenous atoms, thus meeting the industrial requirement of "low temperature."

[0065] Those skilled in the art will understand that although the invention has been shown and described with reference to specific exemplary embodiments thereof, they should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Therefore, the scope of the invention should not be limited to the above embodiments, but should be determined not only by the appended claims, but also by their equivalents.

[0066] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A plasma treatment method for oxide semiconductor channel thin films, characterized in that, The method includes: Amorphous oxide semiconductor channel films are prepared on a substrate to obtain amorphous oxide semiconductor samples containing channel films. The amorphous oxide semiconductor sample containing the channel thin film is placed in the reaction chamber of the plasma device, and the reaction chamber is evacuated. After evacuation, a reaction gas and an auxiliary gas are introduced into the reaction chamber. The reaction gas is oxygen, and the auxiliary gas is one or more of nitrogen and an inert gas. The input power and gas partial pressure of the plasma device are adjusted for the first time to excite the reactive gas to ignite and generate plasma in the reaction chamber. Within a preset first time threshold, the input power and gas partial pressure of the plasma device are adjusted a second time to change the density and energy of the plasma, and the plasma treatment of the amorphous oxide semiconductor channel film is realized in the reaction chamber to obtain an oxygen-containing plasma environment. Based on the oxygen-containing plasma environment, the plasma treatment of the amorphous oxide semiconductor channel film is achieved through oxygen exchange between the oxygen plasma and the oxygen-containing amorphous oxide semiconductor film.

2. The plasma treatment method for oxide semiconductor channel thin films according to claim 1, characterized in that, The first adjustment of the input power and gas partial pressure of the plasma device to excite the reactive gas to ignite and generate plasma in the reaction chamber includes: By first adjusting the input power and oxygen partial pressure of the plasma device, oxygen plasma is generated by igniting oxygen.

3. The plasma treatment method for oxide semiconductor channel thin films according to claim 2, characterized in that, The second adjustment of the input power and gas partial pressure of the plasma device to change the density and energy of the plasma, thereby realizing the plasma treatment of the amorphous oxide semiconductor channel thin film within the reaction chamber, includes: By adjusting the input power and oxygen partial pressure of the plasma device a second time, the density and energy of the oxygen plasma are changed, thus obtaining an oxygen-containing plasma environment.

4. The plasma treatment method for oxide semiconductor channel thin films according to claim 1, characterized in that, The plasma is generated by excitation, and the excitation methods include microwave-excited plasma, inductively coupled plasma, cyclotron resonance-excited plasma, and radio frequency-excited plasma.

5. The plasma treatment method for oxide semiconductor channel thin films according to claim 3, characterized in that, The process of adjusting the input power and oxygen partial pressure of the plasma device a second time to change the density and energy of the oxygen plasma and obtain an oxygen-containing plasma environment includes: The density of the oxygen plasma and the ratio of oxygen exchange are changed by adjusting the oxygen partial pressure.

6. The plasma treatment method for oxide semiconductor channel thin films according to claim 2, characterized in that, The oxygen plasma is generated by exciting oxygen to ignite, wherein the types of oxygen plasma excited include molecules, atoms and ions.

7. The plasma treatment method for oxide semiconductor channel thin films according to claim 1, characterized in that, The amorphous oxide semiconductor channel film is prepared on the substrate by deposition or sputtering.

8. The plasma treatment method for oxide semiconductor channel thin films according to claim 1 or 7, characterized in that, The substrate is a material that does not react with oxide semiconductors, and the substrate material includes silicon, silicon carbide, silicon on an insulating substrate, glass, and sapphire.

9. The plasma treatment method for oxide semiconductor channel thin films according to claim 1, characterized in that, The materials of the amorphous oxide semiconductor thin film include indium gallium zinc oxide, indium oxide, indium gallium oxide, zinc oxide, and indium tin oxide.

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