Process for regulating oxygen vacancy content of multi-component oxide thin films
By combining rapid thermal annealing and laser annealing processes, the oxidation state of multi-element oxide thin films is optimized, solving the problem of insufficient conduction current in oxide semiconductor DRAM transistors in existing technologies and realizing the application requirements of high-performance DRAM write transistors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG UNIV
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-10
AI Technical Summary
Existing post-processing techniques for multi-component oxide thin films cannot accurately achieve the ideal thin film state of "high metal-oxygen bonds, low adsorbed oxygen, and moderate oxygen vacancies," resulting in insufficient conduction current of oxide semiconductor DRAM transistors at high threshold voltages, which limits their application in high-performance DRAM.
By employing a combination of rapid thermal annealing and laser annealing processes, and controlling the ratio of metal-oxygen bonds, oxygen vacancies, and defects or adsorbed oxygen in multi-component oxide films, XPS quantitative analysis was used to establish the correlation between process parameters and oxidation states, thereby optimizing the oxidation state distribution.
While maintaining a high threshold voltage, the conduction current is significantly increased, achieving an ideal thin film state of "high metal-oxygen bond, low adsorbed oxygen, and moderate oxygen vacancy", which meets the requirements of high-performance DRAM write transistors.
Smart Images
Figure CN122373692A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for regulating the oxygen vacancy content of multi-component oxide thin films, belonging to the field of methods for controlling the electrical properties of oxide semiconductors. Background Technology
[0002] As integrated circuit technology enters the post-Moore's Law era, the traditional 1T1C structure of DRAM, due to difficulties in miniaturizing storage capacitors and complex leakage paths, suffers from low data retention time and high refresh power consumption, becoming a key bottleneck restricting further improvements in storage performance. To overcome this limitation, capacitor-free 2T0C structures based on oxide semiconductors (such as IGZO) have received widespread attention in recent years. This type of structure utilizes the extremely low off-state current of oxide transistors, which can significantly extend data retention time and has the advantage of non-destructive readout, providing a new path for achieving high-density, low-power storage.
[0003] However, existing 2T0C DRAMs based on oxide semiconductors (such as IGZO) still face significant challenges in practical applications: to achieve sufficient hold time, the write transistor typically needs to operate in enhancement-mode (E-mode), i.e., with a high positive threshold voltage (Vth) to effectively suppress charge leakage at the memory node under zero hold voltage; however, high Vth is often accompanied by a decrease in channel doping concentration, leading to a decrease in carrier mobility and an increase in the source-drain contact barrier, which in turn significantly reduces the on-current (Ion), severely limiting the write speed. Therefore, how to achieve high Ion under high Vth conditions has become a core technical challenge for the application of oxide semiconductors in DRAM transistors.
[0004] To address these challenges, researchers have conducted extensive research on post-processing techniques for multi-component oxide thin films. In the field of rapid thermal annealing (RTA), studies have shown that it can promote the formation of metal-oxygen networks in oxides at lower temperatures through photothermal synergy. However, the electrical performance of devices after RTA is highly dependent on the annealing atmosphere: in a vacuum, there are too many oxygen vacancies, resulting in metal-like conductivity; in an oxygen atmosphere, oxygen vacancies can be filled, achieving a transition from conductor to semiconductor. In the field of laser annealing, millisecond-level laser annealing has expanded into various applications in CMOS manufacturing processes, such as doping activation and improving the reliability of high-k dielectrics. However, excessively long processing times can damage metal-oxygen bonds, leading to deterioration in device performance. Therefore, researchers have further proposed multi-combination process strategies to balance precise diffusion control and efficient doping activation.
[0005] The aforementioned studies clearly demonstrate that post-processing, especially the combination of RTA and laser annealing, has a decisive impact on the oxygen vacancy content, metal-oxygen bond ratio, and final electrical properties of multi-component oxide thin films. However, existing research largely focuses on optimizing single process parameters and characterizing final electrical properties, lacking a systematic understanding of the intrinsic relationship between the evolution of oxidation states and electrical properties. In multi-component oxide thin films, the oxygen content plays a crucial role in film performance. A higher metal-oxygen bond ratio and a lower adsorbed oxygen ratio typically correspond to a more complete crystal structure and fewer defect states, while oxygen vacancies need to be controlled within a moderate range to balance carrier concentration and device stability. However, existing post-processing research rarely establishes a direct correlation between process parameters and oxygen vacancy regulation based on quantitative analysis of such oxidation states, and has not yet developed a systematic method for synergistically optimizing the oxidation state ratio through combined thermal treatment. This deficiency makes it difficult to accurately achieve the ideal thin film state of "high metal-oxygen bond ratio, low adsorbed oxygen ratio, and moderate oxygen vacancy ratio," limiting the further application of multi-component oxide-based transistors in high-performance DRAM write devices. Summary of the Invention
[0006] To address the lack of a systematic understanding of the intrinsic relationship between the evolution of oxidation states and electrical properties in existing post-processing techniques for multi-component oxide thin films, particularly the difficulty in accurately achieving the ideal thin film state of "high metal-oxygen bonds, low adsorbed oxygen, and moderate oxygen vacancies," this invention provides a process method for controlling the oxygen vacancy content of multi-component oxide thin films. This method increases the conduction current while maintaining a high threshold voltage, meeting the application requirements of high-performance DRAM write transistors.
[0007] To achieve the above objectives, the present invention provides a process for controlling the oxygen vacancy content of multi-component oxide thin films, comprising the following steps:
[0008] (1) Preparation of multi-component oxide thin films;
[0009] (2) Perform a first heat treatment on the multi-component oxide film prepared in step (1);
[0010] (3) Perform a second heat treatment on the IGZO film after the first heat treatment in step (2);
[0011] (4) By controlling the process parameters of the first heat treatment and the second heat treatment, the ratio of metal-oxygen bonds, oxygen vacancies and defects or adsorbed oxygen in the multi-element oxide film can be adjusted.
[0012] Furthermore:
[0013] In step (1), the multi-element oxide thin film is prepared by magnetron sputtering. The multi-element oxide thin film is an IGZO thin film, the target material is a ceramic target with an In:Ga:Zn atomic ratio of 1:1:1, the sputtering power is 90W, the working pressure of argon gas is 0.37Pa, and the substrate temperature is room temperature.
[0014] The thickness of the multi-element oxide film in step (1) is 100 nm.
[0015] The first heat treatment in step (2) is rapid thermal annealing. The rapid thermal annealing is carried out in an oxygen-containing atmosphere, with an annealing temperature of 300℃~400℃ and an annealing time of 1 minute~5 minutes.
[0016] The second heat treatment in step (3) is laser annealing. The laser annealing is a continuous laser annealing process. The laser annealing is carried out in an air atmosphere, with a laser wavelength of 1080nm, a power density of 200W / cm², and a scanning speed of 200mm / s.
[0017] The first heat treatment in step (2) and the second heat treatment in step (3) enable the multi-element oxide film to have an optimal post-processing window. Specifically, it involves first performing a rapid thermal annealing treatment at an annealing temperature of 400°C and an annealing time of 3 minutes, followed by continuous laser annealing treatment.
[0018] The above method, by combining rapid thermal annealing with laser annealing, increases the proportion of metal-oxygen bonds in multi-component oxide films by more than 5 percentage points compared to rapid thermal annealing alone.
[0019] The present invention also provides a multi-component oxide thin film, which is prepared by the above method, wherein the proportion of metal-oxygen bonds in the multi-component oxide thin film is greater than 50%, the proportion of oxygen vacancies is less than 30%, and the proportion of defects or adsorbed oxygen is less than 15%.
[0020] Furthermore, the ratio of metal-oxygen bonds to oxygen vacancies in the multi-element oxide film exhibits a negative correlation.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] Based on XPS for precise decomposition of oxidative states, this invention is the first to take metal-oxygen bonds, oxygen vacancies, and the ratio of adsorbed oxygen / hydrogenated states as direct targets for post-treatment process control, and establishes a clear correlation between "process parameters, oxidative states, and electrical properties", overcoming the blindness of existing studies that rely solely on macroscopic electrical performance optimization.
[0023] This invention modulates the oxygen vacancy content and metal-oxygen bond ratio in multi-component oxide thin films through post-processing. A combination of rapid thermal annealing and laser annealing is employed. Rapid thermal annealing achieves initial control of oxygen vacancies and lattice repair, while laser annealing further optimizes the metal-oxygen bond network structure. The synergistic effect of these two processes significantly increases the proportion of metal-oxygen bonds in the film while effectively suppressing the formation of adsorbed oxygen / hydrogen-containing states, achieving an oxidation state distribution superior to that of a single treatment method. Based on the quantitative characterization of oxidation states using X-ray photoelectron spectroscopy, the combined rapid thermal annealing and laser annealing process synergistically optimizes the ratio of metal-oxygen bonds, oxygen vacancies, and adsorbed oxygen, thereby increasing the conduction current while maintaining a high threshold voltage, meeting the application requirements of high-performance DRAM write transistors.
[0024] XPS quantitative analysis showed that the multi-element oxide film processed by the optimized process of this invention can increase the metal-oxygen bond ratio to more than 50%, control the oxygen vacancy ratio to less than 30%, and reduce the adsorbed oxygen / hydrogen-oxygen ratio to less than 15%, thus achieving the ideal film state of "high metal-oxygen bond ratio, low adsorbed oxygen ratio, and moderate oxygen vacancy ratio".
[0025] The multi-element oxide thin film prepared in this invention, when applied to DRAM write transistors, can achieve higher on-current while maintaining a high positive threshold voltage, effectively resolving the contradiction between high threshold voltage and high on-current. This provides crucial material and process support for 2TOC DRAM structures based on oxide semiconductors. XPS analysis further reveals the negative correlation distribution between metal-oxygen bonds and oxygen vacancies, providing a clear direction for optimizing post-processing windows, avoiding oxidation state deterioration due to over-processing, and exhibiting good process controllability and repeatability. Attached Figure Description
[0026] Figure 1 This is a schematic flowchart of the process method for regulating the oxygen vacancy content of multi-component oxide thin films according to the present invention.
[0027] Figure 2 This is a schematic diagram of the peak fitting of the oxygen O1s spectrum in X-ray photoelectron spectroscopy before and after treatment of the multi-component oxide thin film. The O1 peak corresponds to the metal-oxygen bond, the O2 peak corresponds to the oxygen vacancy, and the O3 peak corresponds to the adsorbed oxygen / hydrogen oxidation state. The left image is the untreated image; the right image is the treated image.
[0028] Figure 3 The diagram shows the distribution of the O1 and O2 ratios of the multi-component oxide films in the embodiments and comparative examples of the present invention. It shows that the two are negatively correlated, and the post-processed samples are all concentrated in the lower right region of the unprocessed samples, indicating that post-processing can effectively increase the O1 ratio and decrease the O2 ratio.
[0029] Figure 4This is a comparison chart of the O1 ratio between the rapid thermal annealing group and the rapid thermal annealing + laser annealing combination group at different processing times (1 min, 3 min, 5 min) at a rapid thermal annealing temperature of 300℃ in the embodiments of the present invention. It shows that the addition of laser annealing can further improve the O1 ratio.
[0030] Figure 5 The diagram shows the O1 ratio comparison between the rapid thermal annealing group and the rapid thermal annealing + laser annealing combination group at different processing times (1 min, 3 min, 5 min) at a rapid thermal annealing temperature of 400℃ in this embodiment of the invention. It shows that the addition of laser annealing can further improve the O1 ratio. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0032] This invention provides a method for controlling the oxygen vacancy content of multi-component oxide thin films through post-processing. The core of this method lies in the quantitative analysis of oxidative states (metal-oxygen bond O1, oxygen vacancy O2, and adsorbed oxygen / hydrogen hydroxide O3) based on X-ray photoelectron spectroscopy. By combining rapid thermal annealing and laser annealing, the proportions of each oxidative state are synergistically optimized, thereby obtaining multi-component oxide thin films with "high O1, moderate O2, and low O3" characteristics to meet the application requirements of high-performance DRAM write transistors. The following examples use IGZO thin films as an example, but the invention is not limited to this and is also applicable to other multi-component oxide thin films such as IGO and IZO.
[0033] Example 1
[0034] Thin film preparation: An IGZO thin film (as a type of multi-component oxide thin film) was deposited on a silicon substrate using magnetron sputtering. The target material was a ceramic target with an In:Ga:Zn atomic ratio of 1:1:1. The sputtering power was 90W, the argon working pressure was 0.37Pa, and the substrate temperature was room temperature. The thickness of the deposited IGZO thin film was 100nm.
[0035] First heat treatment (rapid thermal annealing): The deposited IGZO film was placed in a rapid thermal annealing furnace and annealed in an oxygen-containing atmosphere. The annealing temperature was 400℃, the heating rate was 50℃ / s, the holding time was 3 minutes, and then it was allowed to cool naturally to room temperature.
[0036] Second heat treatment (laser annealing): The IGZO film after the first heat treatment is placed in a continuous laser annealing device with a laser wavelength of 1080nm, a power density of 200W / cm², and a scanning speed of 200mm / s, and annealed in an air atmosphere.
[0037] Example 2
[0038] The difference between this embodiment and Embodiment 1 is that the rapid thermal annealing temperature is 300℃, the holding time is still 3 minutes, and the laser annealing power density is still 200W / cm².
[0039] Example 3
[0040] The difference between this embodiment and Embodiment 1 is that the rapid thermal annealing temperature is still 400℃, the holding time is 1 minute, and the laser annealing power density is still 200W / cm².
[0041] Comparative Example 1
[0042] The difference between this comparative example and Example 1 is that only rapid thermal annealing (400°C, 3 minutes) is performed, without laser annealing.
[0043] Comparative Example 2
[0044] The difference between this comparative example and Example 2 is that only rapid thermal annealing (300°C, 3 minutes) is performed, and laser annealing is not performed.
[0045] Comparative Example 3
[0046] The difference between this comparative example and Example 3 is that only rapid thermal annealing (400°C, 1 minute) is performed, without laser annealing.
[0047] Comparative Example 4
[0048] The difference between this comparative example and Example 1 is that no post-processing is performed.
[0049] XPS testing and oxidative state analysis were then performed.
[0050] The oxidation states of the multi-component oxide thin films (IGZO thin films) prepared in the above examples and comparative examples were analyzed using X-ray photoelectron spectroscopy. Figure 2 As shown, the binding energies of all samples were charge-corrected using the carbon C1s peak (284.8 eV). The oxygen O1s spectrum was decomposed into three characteristic peaks using a Gaussian-Lorentz mixture function:
[0051] O1 peak (approximately 529.8–530.5 eV): corresponds to metal-oxygen bond (MO), representing lattice integrity;
[0052] O2 peak (approximately 531.0–531.8 eV): corresponds to oxygen vacancies, which act as donors to provide free electrons;
[0053] O3 peak (approximately 532.0–533.0 eV): corresponds to defect oxygen or adsorbed oxygen, and is related to surface defects and moisture adsorption.
[0054] The proportions of oxidative states (the proportion of each peak area to the total O1s peak area) in each embodiment and comparative example are shown in the table below:
[0055]
[0056] The results above show that Example 1 (400℃ / 3min RTA + laser annealing) achieved the optimal oxidation state distribution, with an O1 ratio as high as 60.93%, an O2 ratio controlled at 29.19%, and an O3 ratio reduced to 9.88%, fully meeting the ideal thin film state of "high O1 (>60%), moderate O2 (<30%), and low O3 (<10%)".
[0057] Examples 2 and 3, by changing the temperature and processing time of the RTA, showed a significant increase in O1 compared to the untreated device, but the O2 ratio was too high and the O3 ratio did not drop to the ideal range. Comparative Examples 1 to 3 show that although RTA treatment alone can increase the O1 ratio, there are still many oxygen vacancies and the O3 ratio is too high; Comparative Example 4, without any post-annealing treatment, had the worst oxidation state distribution.
[0058] In summary, the combined treatment of rapid thermal annealing and laser annealing can synergistically optimize the oxidation state distribution of multi-component oxide films. However, it is necessary to precisely control the process parameters to avoid overtreatment leading to an increase in the proportion of adsorbed oxygen. The process window represented by Example 1 (RTA temperature 400°C, time 3 minutes, combined with laser annealing) can achieve an ideal film state with high metal-oxygen bonds, moderate oxygen vacancies, and low adsorbed oxygen.
[0059] The following is a correlation analysis between O1 and O2.
[0060] like Figure 3 As shown, statistical analysis of the O1 and O2 ratios of multi-component oxide films obtained under different process conditions revealed a significant negative correlation between the two. When the O1 ratio is below 40%, the O2 ratio is usually above 40%; when the O1 ratio is above 60%, the O2 ratio is usually below 30%. This pattern indicates that increasing the metal-oxygen bond ratio is accompanied by the effective filling of oxygen vacancies, providing a clear direction for optimizing post-processing. Notably, a few data points in the upper left corner (corresponding to over-processing conditions) show that while O1 is high, O2 is also relatively high, indicating that excessive heat treatment can disrupt the oxidation chemical equilibrium, thus suggesting the existence of an optimal process window.
[0061] The following analysis examines the changes in O1 content over RTA time.
[0062] like Figure 4 As shown, under fixed laser annealing conditions (power density 200 W / cm², scanning speed 200 mm / s), the effect of RTA holding time (1 min, 3 min, 5 min) on the O1 ratio was investigated at different RTA temperatures (300℃, 400℃). The results show that:
[0063] (1) All post-treatment conditions increased the O1 ratio, all of which were higher than the 33.65% of the untreated sample;
[0064] (2) At the same RTA temperature, the O1 ratio of the RTA+LA group was higher than that of the RTA-only group, indicating that the addition of laser annealing helps to form a higher quality metal-oxygen network.
[0065] (3) Under the same RTA time, increasing the RTA temperature and adding laser annealing treatment will increase the O1 ratio accordingly;
[0066] (4) When the RTA temperature is 400℃ and the holding time is 1min, the O1 ratio of the RTA+LA group reaches the highest value (about 72%), but the O2 and O3 ratios are also high at this time (O2 about 14% and O3 about 15%), indicating that overtreatment leads to an increase in the proportion of oxygen vacancies and adsorbed oxygen.
[0067] (5) When the RTA holding time is extended to 3 min, the O1 ratio stabilizes at about 61%, while the O2 and O3 ratios drop to 29% and 9% respectively, resulting in the best overall effect;
[0068] (6) When the RTA holding time exceeds 5 minutes, the O1 ratio decreases significantly, indicating that prolonged heat treatment will cause the metal-oxygen bond to be destroyed.
[0069] The optimal process window will be determined below.
[0070] like Figure 5 As shown, based on the above analysis of oxidation states, this invention determined the optimal post-processing window: rapid thermal annealing at 400℃ for 3 minutes in an oxygen-containing atmosphere; followed by continuous laser annealing at a laser power density of 200W / cm² and a scanning speed of 200mm / s. The multi-element oxide film treated with this optimal process exhibits an oxidation state distribution of over 60% O1, approximately 29% O2, and approximately 9% O3, achieving the ideal state of "high O1, moderate O2, and low O3".
[0071] Those skilled in the art will understand that the multi-component oxide thin films described in this invention are not limited to magnetron sputtering preparation, but can also be prepared by atomic layer deposition, pulsed laser deposition, or solution methods. Furthermore, the methods proposed in this invention are also applicable to various multi-component oxide semiconductor thin films such as IGO and IZO. The atmosphere for the rapid thermal annealing process is not limited to oxygen; it can also be carried out in nitrogen, air, or a vacuum, but the parameters need to be adjusted according to the specific target. The laser annealing process is not limited to continuous laser; pulsed lasers (such as nanosecond lasers or femtosecond lasers) can also be used, but appropriate parameters need to be selected according to the film thickness and heat-affected zone requirements. In addition, the oxygen vacancy ratio range described in this invention can be adjusted within a certain range according to the specific device requirements. For example, when a higher carrier concentration is required, the oxygen vacancy ratio can be appropriately increased (e.g., controlled at 25%–30%), but it is necessary to ensure that the O3 ratio does not exceed 15% to avoid excessive defect states.
[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A process for controlling the oxygen vacancy content of multi-component oxide thin films, characterized in that, Includes the following steps: (1) Preparation of multi-component oxide thin films; (2) Perform a first heat treatment on the multi-component oxide film prepared in step (1); (3) Perform a second heat treatment on the multi-element oxide film after the first heat treatment in step (2); (4) By controlling the process parameters of the first heat treatment and the second heat treatment, the ratio of metal-oxygen bonds, oxygen vacancies and defects or adsorbed oxygen in the multi-element oxide film can be adjusted.
2. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 1, characterized in that, In step (1), the multi-element oxide thin film is prepared by magnetron sputtering. The multi-element oxide thin film is an IGZO thin film, the target material is a ceramic target with an In:Ga:Zn atomic ratio of 1:1:1, the sputtering power is 90W, the working pressure of argon gas is 0.37Pa, and the substrate temperature is room temperature.
3. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 1, characterized in that, The thickness of the multi-element oxide film in step (1) is 100 nm.
4. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 1, characterized in that, The first heat treatment in step (2) is rapid heat annealing.
5. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 4, characterized in that, The rapid thermal annealing process is carried out in an oxygen-containing atmosphere, with an annealing temperature of 300℃~400℃ and an annealing time of 1 minute~5 minutes.
6. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 1, characterized in that, The second heat treatment in step (3) is laser annealing, which is a continuous laser annealing process.
7. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 6, characterized in that, The laser annealing is performed in an air atmosphere with a laser wavelength of 1080nm, a power density of 200W / cm², and a scanning speed of 200mm / s.
8. The process method for regulating the oxygen vacancy content of multi-component oxide thin films according to claim 1, characterized in that, The first heat treatment in step (2) and the second heat treatment in step (3) enable the multi-element oxide film to have an optimal post-processing window. Specifically, it involves first performing a rapid thermal annealing treatment at an annealing temperature of 400°C and an annealing time of 3 minutes, followed by continuous laser annealing treatment.
9. A multi-component oxide thin film, characterized in that, The multi-component oxide film is prepared by the process method for controlling the oxygen vacancy content of the multi-component oxide film according to any one of claims 1-8, wherein the proportion of metal-oxygen bonds in the multi-component oxide film is greater than 50%, the proportion of oxygen vacancies is less than 30%, and the proportion of defects or adsorbed oxygen is less than 15%.
10. The multi-component oxide thin film according to claim 9, characterized in that, The ratio of metal-oxygen bonds to oxygen vacancies in the multi-component oxide film is negatively correlated.