Method for depositing silicon oxide films on large scale
By optimizing the steps and parameters of the flow method in the atomic layer deposition equipment, the problems of film thickness uniformity and insufficient deposition rate of silicon oxide films in PECVD technology were solved, achieving efficient large-scale production, reducing production costs and improving film quality.
Patent Information
- Application Number
- CN202510671484.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-09-12
AI Technical Summary
Traditional PECVD technology has problems such as high deposition temperature, insufficient film density, poor film thickness uniformity, low step coverage and poor conformality of high aspect ratio structures when depositing silicon oxide films. In addition, the DIPAS and ozone flow methods have short source entry time and low concentration, resulting in insufficient film thickness uniformity and deposition rate.
Using atomic layer deposition equipment, the stop valve between the chamber and the vacuum pump is closed before entering the source to extend the residence time of the precursor in the chamber. The pressure holding method is used to increase the diffusion and concentration of the precursor in the chamber, and the steps and parameters of the flow method are optimized to improve the film thickness uniformity and deposition rate.
The film thickness uniformity and deposition rate of silicon oxide films are significantly improved, production costs are reduced, step coverage and conformality of high aspect ratio products are improved, and precise control of film density and thickness is achieved.
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Figure CN120625017A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing technology, in particular to a method for depositing silicon oxide films in large quantities. Background Art
[0002] In the field of semiconductor manufacturing, the deposition of silicon oxide films is a key technology, widely used in the preparation of structures such as insulating layers, passivation layers, and gate dielectric layers. Traditional silicon oxide deposition methods mainly use PECVD technology, which has the advantages of fast deposition rate and short process time. However, PECVD technology has obvious limitations, such as high deposition temperature, difficulty in accurately controlling film thickness, poor film thickness uniformity, and insufficient density of the formed silicon oxide film layer. In addition, for products with high aspect ratio structures, PECVD technology has poor conformality on the substrate surface, and step coverage is usually difficult to achieve the ideal level. These problems limit its promotion in certain high-end applications.
[0003] In the process, problems were discovered when using DIPAS and ozone as precursors and a flow method (the shut-off valve between the pump and the chamber was always open) to deposit silicon oxide: 1. Due to the relatively low reactivity of DIPAS, chemical saturation adsorption cannot be achieved within a reaction time of 1 second. The reaction time for saturated adsorption to occur in the chamber is relatively long, and a certain reaction time in the chamber is required for saturated adsorption reaction to occur. When the silicon source is introduced using the flow method, the silicon source stays on the silicon wafer surface for a short time. Moreover, when processing more than 400 4-inch silicon wafers at a time, the diffusion in the chamber is insufficient, resulting in a low adsorption rate on the silicon wafer surface, difficulty in achieving saturated chemical adsorption, poor film thickness uniformity, and the silicon source will be directly pumped away by the pump. A longer silicon source introduction time is required to achieve even a small improvement, which leads to an extension of the process time and an increase in source consumption, resulting in increased production costs, as well as a slow deposition rate and poor film thickness uniformity within and between wafers. 2. The problems with using the flow method to introduce ozone into the source are: 1. The ozone concentration produced by the ozone generator is low (10% to 15%), and the amount of ozone entering the chamber is far from enough, making it difficult to achieve adsorption saturation in a short time. 2. Ozone has a very short half-life of only 1 to 2 seconds at a high temperature of 250°C. When flowing through the chamber, its concentration decays rapidly when encountering high temperatures, and there is a large concentration decay along the direction of the airflow, which will lead to large differences in adsorption rate within the wafer, resulting in slow deposition rate and poor film thickness uniformity. In actual production, the uniformity of silicon oxide film thickness and deposition rate cannot be guaranteed. Summary of the Invention
[0004] The present invention discloses a method for depositing silicon oxide films in large quantities, aiming to solve the above-mentioned problems.
[0005] The present invention adopts the following scheme:
[0006] A method for depositing silicon oxide thin films in large quantities, using an atomic layer deposition apparatus, wherein the atomic layer deposition apparatus includes a chamber suitable for placing a substrate, the chamber being connected to a vacuum pump, an inert gas pipeline, a first reaction source pipeline, and a second reaction source pipeline, and a shutoff valve is provided on the connecting pipeline between the vacuum pump and the chamber. The method comprises the following steps:
[0007] S1. Place a batch of single crystal silicon wafers into the chamber of the atomic layer deposition equipment and evacuate the chamber;
[0008] S2. Precursor A is introduced into the chamber and the shut-off valve between the chamber and the vacuum pump is closed before the source is introduced; after the source is introduced, the chamber is inflated;
[0009] S3. After the filling is completed, the chamber is purged with inert gas to remove excess precursor A and by-products;
[0010] S4, introducing precursor B into the chamber, and closing the stop valve between the chamber and the vacuum pump before entering the source;
[0011] S5. After the filling is completed, the chamber is purged with inert gas to remove excess precursor B and by-products;
[0012] S6. Repeat steps S2-S5 1 to 500 times to obtain the target coating layer.
[0013] Furthermore, in S1, the vacuum in the chamber needs to be evacuated to 0.001 to 1.0 tor, and the reaction temperature in the chamber needs to be set to 250° C. for a holding time of not less than 1 hour.
[0014] Further, in S2, the precursor A is a silicon source.
[0015] Furthermore, the silicon source is diisopropylamine silane, and the source feeding time is controlled between 0.5 seconds and 1 second.
[0016] Furthermore, the precursor B is an oxygen precursor.
[0017] Furthermore, the oxygen precursor is ozone, and the time of entering the source is 1 second to 6 seconds.
[0018] Furthermore, the inert gas is argon or nitrogen, the purge time is 1 to 10 seconds, and the purge times are 1 to 3 times.
[0019] Furthermore, after the source precursor A is fed in, nitrogen or argon is filled in for 1 to 3 seconds, and the cycle is repeated once. At this time, the stop valve is closed.
[0020] Beneficial effects:
[0021] 1. By closing the shut-off valve between the chamber and the vacuum pump before the silicon source enters, the precursor A can be prevented from being quickly drawn away by the vacuum pump when flowing through the chamber, so that the silicon source has sufficient residence time on the surface of the silicon wafer, which plays a key role in improving the film formation rate and film thickness uniformity.
[0022] 2. Since the silicon source enters the chamber in a short time, within 1 second, if the stop valve is closed before the source enters and the exhaust valve is opened at the moment the source enters, the silicon source will still be pumped away by the pump, and the residence time in the chamber will still be short, making it difficult to achieve saturated chemical adsorption. The silicon source cannot fully diffuse in the chamber, and the film thickness uniformity within and between slices is poor. Therefore, after the silicon source is introduced, the stop valve is not opened, and nitrogen is continuously filled into the chamber for 2 to 3 seconds. This not only completely brings the silicon source remaining in the pipeline into the chamber, but also increases the residence time of the silicon source in the chamber, allowing the silicon source to diffuse more fully in the chamber and have sufficient reaction time. The addition of this process significantly helps improve the uniformity of film thickness, and can improve the utilization rate of the silicon source, reduce the source entry time, and reduce source consumption.
[0023] 3. Close the shut-off valve between the chamber and the vacuum pump before ozone is introduced, and keep it closed during the ozone introduction process. This can continuously increase the amount of ozone in the chamber and avoid the rapid decrease of ozone in the chamber due to the low content of the prepared ozone itself and the half-life of 2-3 seconds at a high temperature of 250°C. Within a short ozone introduction time (5-6 seconds), there can be enough ozone in the chamber for saturated chemical adsorption, and ozone can be fully diffused in the chamber along with the carrier gas, which has a positive effect on improving the film formation rate and the uniformity of film thickness between sheets. At the same time, it can greatly shorten the ozone introduction time, shorten the process time, and thus reduce oxygen consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 is a schematic diagram of an atomic layer deposition apparatus according to an embodiment of the present invention; DETAILED DESCRIPTION
[0025] Combine Figure 1 This embodiment provides a method for depositing silicon oxide thin films in large quantities, using an atomic layer deposition apparatus. The atomic layer deposition apparatus includes a chamber suitable for placing a substrate, the chamber being connected to a vacuum pump, an inert gas pipeline, a first reaction source pipeline, and a second reaction source pipeline. A shut-off valve is provided on the connecting pipeline between the vacuum pump and the chamber. The method includes the following steps:
[0026] S1. Place batches of single-crystal silicon wafers (i.e., substrates) into the chamber of the atomic layer deposition equipment and evacuate the chamber. The vacuum in the chamber must be reduced to 0.001 to 1.0 Torr. This low vacuum environment helps reduce impurity interference and improve the adsorption efficiency of the precursor. The reaction temperature in the chamber is set to 250°C ± 10°C and maintained for at least 1 hour to ensure uniform temperature distribution in the chamber and avoid uneven film quality due to local temperature differences.
[0027] S2. Precursor A is introduced into the chamber, and the shut-off valve between the chamber and the vacuum pump is closed before the source is introduced to prevent the precursor A from being quickly drawn away, thereby extending its residence time in the chamber; the chamber is inflated after the source is introduced; the precursor A is a silicon source, preferably, the silicon source is diisopropylamine silane, and the source introduction time is controlled between 0.5 seconds and 1 second; due to the low reactivity of DIPAS, it is difficult to achieve saturated adsorption within a short source introduction time, so it is necessary to close the shut-off valve to ensure that the pressure in the chamber rises, so that DIPAS can be evenly distributed and fully diffused in the cavity. Furthermore, closing the shutoff valve significantly increases the concentration of DIPAS within the chamber, reducing its loss through the chamber walls and piping, thereby improving precursor utilization and shortening process time. After the source precursor A is introduced, nitrogen or argon is purged for 1 to 3 seconds, with one cycle. During this period, the shutoff valve remains closed, allowing precursor A to remain within the chamber or piping. During the purge process, the chamber pressure continuously rises, and precursor A is carried around by the carrier gas, preventing it from being directly pumped out by the pump. This purge process has a dual purpose: first, it completely draws any DIPAS remaining in the silicon source piping into the chamber, preventing precursor A from being wasted. Second, it further extends the DIPAS's residence time within the chamber and promotes its uniform diffusion, thereby improving film thickness uniformity within and between wafers. Experimental verification demonstrates that purge-assisted diffusion significantly improves film thickness uniformity while reducing DIPAS source introduction time and consumption, thereby lowering production costs.
[0028] S3. After the gas filling is completed, the stop valve is opened to purge the chamber with inert gas to remove excess precursor A and by-products;
[0029] S4. Precursor B is introduced into the chamber, and the shutoff valve between the chamber and the vacuum pump is closed before the source is introduced. Precursor B is an oxygen precursor, specifically ozone, and the introduction time is 1 to 6 seconds. During the ozone introduction stage, the ozone content in the chamber is increased by maintaining pressure, overcoming the problems of low ozone concentration and short half-life at high temperatures, ensuring sufficient ozone in the chamber for saturated chemical adsorption. In particular, ozone is fully diffused within the chamber with the carrier gas, further improving the film formation rate and inter-sheet film thickness uniformity, while also shortening the ozone introduction time.
[0030] S5. After the filling is completed, the chamber is purged with inert gas to remove excess precursor B and by-products; the inert gas can be argon or nitrogen, the purging time is 1 to 10 seconds, and the purging frequency is 1 to 3 times.
[0031] S6. Steps S2-S5 are repeated 1 to 500 times to obtain a target coating layer (silicon dioxide) of about 100 nm.
[0032] Taking DIPAS and O3 as an example, the reaction equation for generating the target coating layer is: DIPAS + O3 → SiO2 + H2. It should be noted that the stop valve needs to be open during the purge period.
[0033] This embodiment, by improving the steps and parameters of flow deposition, solves the problem of traditional flow deposition, in which DIPAS and ozone are difficult to achieve saturated chemical adsorption within a short source entry time when entering the chamber, resulting in poor film thickness uniformity, low deposition rate, and long process time. Through this embodiment, the film thickness uniformity of silicon oxide films at a process temperature of 250°C can be greatly improved, reaching 1% within a slice and 2% between slices. By closing the shut-off valve between the chamber and the vacuum pump before source entry, this embodiment can maintain a continuous increase in chamber pressure during the source entry process, ensuring uniform diffusion of the precursor in the chamber, increasing the precursor content in the chamber, and increasing the residence time of the precursor in the chamber. The advantage of this is that only a small amount of precursor is required to achieve saturation of the adsorption reaction, which not only saves precursor consumption but also shortens process time. In mass production, production costs are significantly reduced, providing potential for the application of silicon oxide in the semiconductor industry.
[0034] This embodiment optimizes the process recipe by adjusting hardware and recipes. This reduces source loading time, thereby lowering source consumption, shortening process time, improving deposition rate and film thickness uniformity, and reducing equipment and production costs. This provides a reference for the mass production of high-temperature thermal silicon oxide. Furthermore, the silicon oxide deposited by atomic layer deposition can precisely control thickness and achieve good film uniformity, with better density than silicon oxide deposited by PECVD, and at a lower deposition temperature. Furthermore, it achieves excellent conformality for high-aspect-ratio products, with step coverage exceeding 90%.
[0035] Table 1 shows the experimental data comparison of the deposition rate and film thickness uniformity of the pressure-maintaining deposition scheme of this embodiment with those of the traditional flow deposition method and the silicon source flow ozone pressure-maintaining deposition method:
[0036]
[0037] It can be seen from the experimental data in Table 1 that the deposition method of the embodiment can greatly improve the deposition rate and the uniformity of the film thickness between wafers by adopting the pressure-maintaining deposition method of the embodiment.
[0038] It should be understood that the above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.
[0039] The above description of the drawings used in the implementation manner only shows certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without making any creative efforts.
Claims
1. A method for depositing silicon oxide thin films in large quantities, using an atomic layer deposition apparatus, wherein the atomic layer deposition apparatus comprises a chamber suitable for placing a substrate, the chamber being connected to a vacuum pump, an inert gas pipeline, a first reaction source pipeline, and a second reaction source pipeline, wherein a shutoff valve is provided on the pipeline connecting the vacuum pump and the chamber; The steps include: S1. Place a batch of single crystal silicon wafers into the chamber of the atomic layer deposition equipment and evacuate the chamber; S2. Precursor A is introduced into the chamber and the shut-off valve between the chamber and the vacuum pump is closed before the source is introduced; after the source is introduced, the chamber is inflated; S3. After the filling is completed, the chamber is purged with inert gas to remove excess precursor A and by-products; S4, introducing precursor B into the chamber, and closing the stop valve between the chamber and the vacuum pump before entering the source; S5. After the filling is completed, the chamber is purged with inert gas to remove excess precursor B and by-products; S6. Repeat steps S2-S5 1 to 500 times to obtain the target coating layer.
2. The method for depositing silicon oxide thin films in large quantities according to claim 1, wherein: In S1, the vacuum in the chamber needs to be evacuated to 0.001 to 1.0 tor, and the reaction temperature in the chamber needs to be set to 250°C for a maintenance time of not less than 1 hour.
3. The method for depositing silicon oxide thin films in large quantities according to claim 1, wherein: In S2, the precursor A is a silicon source.
4. The method for depositing silicon oxide thin films in large quantities according to claim 3, wherein: The silicon source is diisopropylamine silane, and the source feeding time is controlled between 0.5 seconds and 1 second.
5. The method for depositing silicon oxide thin films in large quantities according to claim 3, wherein: The precursor B is an oxygen precursor.
6. The method for depositing silicon oxide thin films in large quantities according to claim 5, wherein: The oxygen precursor is ozone, and the time of entering the source is 1 second to 6 seconds.
7. The method for depositing silicon oxide thin films in large quantities according to claim 1, wherein: The inert gas is argon or nitrogen, the purge time is 1 to 10 seconds, and the purge times are 1 to 3 times.
8. The method for depositing silicon oxide thin films in large quantities according to claim 2, wherein: After the source precursor A is filled with nitrogen or argon, the filling time is 1 to 3 seconds, and the cycle is 1 time. At this time, the stop valve is closed.