A method of depositing TaO x
By cleaning the deposition cavity in an oxygen-free environment and bombarding the Ta target with DC pulses, a functional TaOx film was prepared, solving the problems of low preparation efficiency and limited equipment in the existing technology, and achieving efficient preparation and performance improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI INTEGRATED CIRCUIT RESEARCH & DEVELOPMENT CENTER CO LTD
- Filing Date
- 2023-01-06
- Publication Date
- 2026-07-21
Smart Images
Figure CN118308688B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor integrated circuit technology, and more particularly to a TaO x Deposition methods. Background Technology
[0002] In the traditional field of integrated circuit manufacturing, tantalum oxide (Ta2O5) is used as the primary dielectric film. Ta2O5 is an excellent high-refractive-index coating material, suitable for antireflective coatings, anti-reflective films, or light filters, primarily used in optical signal processing chips such as back-illuminated complementary metal-oxide-semiconductor (CMOS) image sensors. Ta2O5 films exhibit stable chemical properties, strong resistance to laser damage, and a high dielectric constant, making them a primary material for thin-film capacitors. However, in emerging resistive switching memory, TaO2 is used instead. x The dielectric film is made of a material between Ta and Ta₂O₅, specifically an incompletely oxidized tantalum oxide. This TaO₂... x The material is mainly used in resistive switching materials and is an important component of resistive switching memory. Among them, TaO... x The fabrication of the membrane is a major technological bottleneck restricting the development of resistive random access memory (RRAM) devices, which are crucial for future in-memory computing and neural network computing. Therefore, various countries are focusing on TaO2. x Preparation is of urgent concern.
[0003] Ta is extremely easily oxidized, and in nature it mainly exists in two states: pure Ta or Ta₂O₅. An intermediate state, TaO, is also present. x Unlike Ta2O5, TaO x The preparation technology for TaO is more difficult and the resources are harder to obtain. Currently, TaO used in the fabrication of resistive switching memory... x There are very few specialized equipment options available, and their preparation efficiency and versatility cannot be compared with conventional physical vapor deposition equipment used to prepare Ta2O5. Summary of the Invention
[0004] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide a TaO x Deposition methods.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows:
[0006] A type of TaO x Deposition methods include:
[0007] A deposition chamber with an oxygen-free environment is provided, wherein a Ta target and a deposition object are disposed in the deposition chamber;
[0008] A sufficient amount of the first inert gas is introduced;
[0009] Before ignition, an appropriate amount of oxygen with a flow rate lower than that of the first inert gas is introduced, and ignition is initiated immediately. This causes the Ta atoms on the Ta target surface to detach from the surface of the Ta target after being bombarded by the formed first inert gas and oxygen plasma before being oxidized to Ta₂O₅. They then move towards the deposition target and, during this process, combine with oxygen atoms in the first inert gas and oxygen plasma to form TaO. x It falls onto the deposited object to form a film.
[0010] Furthermore, during the deposition process, the pressure in the deposition chamber is maintained between 0.002 and 0.02 torr.
[0011] Furthermore, the total gas flow rate when the first inert gas and the oxygen are introduced is 30 to 170 sccm.
[0012] Furthermore, a DC pulse method is used, and a bias power of 1000–4000 W is applied after ignition to control the deposition rate.
[0013] Furthermore, a bias power of 400–600W is used to generate ignition.
[0014] Furthermore, the deposition time is 5–20 s.
[0015] Furthermore, the provision of a deposition chamber with an oxygen-free environment specifically includes:
[0016] The Ta target is disposed in the deposition cavity;
[0017] Introduce a second inert gas;
[0018] Qi Hui utilizes the formed second inert gas plasma to bombard the Ta target, thereby removing the deposits inside the deposition chamber and the oxides on the surface of the Ta target, creating an oxygen-free environment in the deposition chamber;
[0019] The deposition object is placed in the deposition chamber.
[0020] Furthermore, the flow rate of the second inert gas is 30-50 sccm, and after the deposition object is placed in the deposition chamber, it continues to be introduced as the first inert gas.
[0021] Furthermore, the distance between the Ta target and the deposition object is 50–80 mm.
[0022] Furthermore, the deposition chamber includes a deposition chamber for performing physical vapor deposition processes.
[0023] As can be seen from the above technical solution, this invention avoids the influence of residual Ta2O5 in the deposition chamber on the deposition by creating an oxygen-free deposition environment before deposition. Furthermore, by introducing oxygen only before ignition and appropriately reducing its flow rate relative to the inert gas, excessive contact between oxygen and the Ta target can be limited, thus extending the time for the Ta target surface to be oxidized to Ta2O5. Based on this, a strong bombardment effect on the Ta target is created by a large flow rate of inert gas, bombarding as many Ta atoms as possible in a short time. Under relatively low pressure and high power, these Ta atoms combine with a suitable amount of oxygen atoms in the plasma to generate TaO. x This allows for the formation of functional TaO at higher deposition rates. x Film layer. This invention can utilize conventional physical vapor deposition equipment, and by adjusting and optimizing process parameters, TaO with different thicknesses and oxygen contents can be deposited. x The film layer, and the formed TaO x The film layer has a wide resistance range, which allows for the adjustment of the high and low impedance of the resistive switching memory device, improving device performance and increasing device reliability. Attached Figure Description
[0024] Figure 1 A preferred embodiment of the present invention is a TaO x A flowchart of the deposition method;
[0025] Figure 2 A preferred embodiment of the present invention is a TaO x A schematic diagram of the deposition principle. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.
[0027] TaO2 is currently used for fabricating resistive switching memory. xThe types of specialized equipment available for this purpose are limited, and their preparation efficiency and versatility cannot compare with conventional physical vapor deposition (PVD) equipment used for preparing Ta₂O₅. The purpose of this invention is to utilize existing deposition equipment and optimize the deposition process menu to efficiently obtain TaO₂ with a certain thickness and a wide adjustable resistance range. x This allows for the preparation of functional TaO with varying oxygen contents as needed. x The film layer enables the adjustment of the high and low impedance of the resistive switching memory device, thereby improving device performance and increasing device reliability.
[0028] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.
[0029] Please see Figure 1 , Figure 1 A preferred embodiment of the present invention is a TaO x A flowchart of the deposition method. (e.g.) Figure 1 As shown, a TaO of the present invention x The deposition method may include the following steps:
[0030] Step S1: Provide a deposition chamber with an oxygen-free environment.
[0031] Existing Ta₂O₅ film deposition technologies first require the use of Ta₂O₅ targets or pure Ta targets, employing physical vapor deposition (PVD) with the introduction of argon and oxygen to achieve Ta₂O₅ deposition. A crucial factor is the need for continuous plasma bombardment of the target to ensure a stable supply of Ta₂O₅ molecules for deposition on the product surface. Therefore, the oxidation state of Ta on the target surface and the probability of bombarded Ta atoms combining with oxygen atoms during their fall are critical factors. Under traditional Ta₂O₅ preparation techniques, it is essential to ensure that both the target and the inner wall of the deposition chamber are covered with a thin film of Ta₂O₅ before operation, thus maintaining a Ta₂O₅ atmosphere within the deposition chamber. Therefore, an excessive oxygen flow rate is required during film deposition, and oxygen must be introduced from the initial process settings. Secondly, as deposition progresses, Ta₂O₅ also deposits on the inner wall of the deposition chamber. These newly deposited Ta₂O₅ particles, along with existing Ta₂O₅, may be subject to secondary bombardment and deposition on the product surface. Therefore, achieving continuous and stable Ta2O5 deposition is relatively easy, requiring only the introduction of excess oxygen and waiting for the Ta2O5 atmosphere in the deposition chamber to become saturated. Moreover, to pursue uniformity and stability of film thickness, the total gas flow rate is generally set within a small range, and the power is appropriately increased to ensure the efficiency of Ta2O5 deposition.
[0032] The present invention requires the deposition of TaO. xSince Ta₂O₅ is an incompletely oxidized form, existing experience in generating Ta₂O₅ using physical vapor deposition is not applicable. Following the methods for preparing Ta₂O₅ and attempting deposition by simply adjusting the oxygen flow rate does not yield a product with TaO as the main component. x The film quality. Among them, the residual Ta₂O₅ in the deposition cavity and the oxidation level of the target material both affect the TaO₂ film quality. x Important factors in its generation.
[0033] To address the aforementioned problems, this invention proposes a novel TaO x The deposition method. Furthermore, to avoid the residual Ta₂O₅ in the deposition cavity affecting the deposited TaO₂... x To mitigate the impact, the atmosphere in the deposition chamber must first be thoroughly cleaned.
[0034] Please see Figure 2 In some embodiments, a deposition chamber 10 for performing a physical vapor deposition process and having a pulsed DC power supply can be used to place a Ta target 12 on an upper cathode 11 in the deposition chamber 10, and an oxygen-free deposition environment can be formed in the deposition chamber 10 by cleaning the deposition chamber 10.
[0035] In some embodiments, a sacrificial object, such as a sacrificial wafer 16, may be used. The sacrificial wafer 16 is placed on an electrostatic chuck 15 located below the cathode 11 in the deposition chamber 10, and a second inert gas may be introduced. The second inert gas may be, for example, argon (Ar).
[0036] Then, argon plasma can be formed by ignition, and the Ta target 12 and sacrificial wafer 16 can be bombarded by the argon plasma to remove the Ta2O5 deposits on the inner wall of the deposition chamber 10 and the Ta2O5 oxides on the surface of the Ta target 12, so that the inner wall of the deposition chamber 10 is cleaned and the surface of the Ta target 12 is cleaned to become pure Ta, so that there is no oxide interference in the deposition chamber 10, thus forming an oxygen-free environment in the deposition chamber 10.
[0037] In some embodiments, when cleaning the deposition chamber 10, the flow rate of the second inert gas argon can be 30 to 50 sccm, and the cleaning time can be at least 5 minutes, so as to ensure that an oxygen-free environment is formed in the deposition chamber 10.
[0038] Next, replace the sacrificial wafer 16 with the deposition object, such as the deposition wafer 17, and you are ready to start Ta2O5 deposition.
[0039] In some other embodiments, a baffle may be used instead of the sacrificial wafer 16, and the baffle may be placed over the electrostatic chuck 15 to receive bombardment from argon plasma during cleaning of the deposition chamber 10, and the baffle may be removed after cleaning. This protects the equipment components from potential damage caused by argon plasma bombardment.
[0040] During the above process, argon gas is continuously introduced to effectively maintain the anaerobic environment.
[0041] In some embodiments, the distance between the Ta target 12 and the deposition wafer 17 can be 50 to 80 mm.
[0042] Step S2: Set the deposition process parameters and execute.
[0043] The process menu on the deposition chamber 10 device can be used to set the unique deposition process parameters of this invention.
[0044] In some embodiments, deposition process parameters may include pressure, temperature, power, gas flow rate, time, etc. in the deposition chamber 10.
[0045] After the process menu is set, the equipment will execute the process according to the process menu content.
[0046] Step S3: Introduce inert gas.
[0047] After the process menu is activated, the deposition chamber 10 will be controlled to be at a certain temperature and pressure, and a sufficient amount of first inert gas will be introduced into the deposition chamber 10. The first inert gas may be, for example, argon, which is the same as the second inert gas. In some embodiments, argon gas can be introduced into the deposition chamber 10 through a first air inlet 14 provided on the bottom surface of the deposition chamber 10.
[0048] In some embodiments, the pressure in the deposition chamber 10 can be controlled to be maintained between 0.002 and 0.02 torr. The temperature can be set in the same way as usual and is not particularly required.
[0049] It should be noted that the previous cleaning step of deposition chamber 10 was switched to the current TaO cleaning step. x During the deposition step, argon gas is continuously introduced into the deposition chamber 10. That is, after the second inert gas is kept in the pipeline until the sacrificial wafer 16 is replaced by the deposition wafer 17 (or the baffle is removed), it is converted into the first inert gas and continues to be introduced. The only difference is the change in flow rate.
[0050] It should also be noted that the load locking function of the deposition chamber 10 can be used to control the pressure in the deposition chamber 10 to be maintained at a low pressure between 0.002 and 0.02 torr before the deposition wafer 17 is placed in the deposition chamber 10.
[0051] Step S4: Introduce oxygen and ignite immediately.
[0052] To prevent the Ta target 12 from being prematurely and completely oxidized to Ta2O5 by oxygen (O2), thus preventing the attainment of a TaO layer with sufficient thickness. x The film layer needs to minimize contact between oxygen and the Ta target 12. Therefore, one aspect of the originality of this invention lies in the fact that oxygen is only introduced in the final step before ignition, when setting the total deposition gas flow rate (the set gas stabilization time can be less than or equal to 10 s), and a sufficiently thick TaO layer is deposited within a short period after ignition. x Membrane.
[0053] Specifically, before ignition, an appropriate amount of oxygen with a flow rate lower than that of argon is introduced simultaneously with the ignition process, and ignition is initiated immediately.
[0054] In order to deposit TaO more quickly before the Ta atoms are completely oxidized to Ta2O5. x For thin films, a high flow rate of argon gas is required to bombard the Ta target 12, and an appropriate amount of oxygen is introduced to generate incompletely oxidized TaO. x .
[0055] In some embodiments, argon can be used as the carrier gas, and oxygen carried by argon can be introduced into the deposition chamber 10 through the second air inlet 13 provided on the side of the deposition chamber 10.
[0056] In some embodiments, the total gas flow rate of the introduced argon and oxygen (including argon as a carrier gas) can be 30 to 170 sccm.
[0057] In some embodiments, a bias power of 400 to 600 W is used in the ignition step to ensure that the deposition chamber 10 can generate ignition (the time of this step can be minimized, for example, the time setting range can be between 1 and 5 seconds).
[0058] In some embodiments, a DC pulse method can be used to control the deposition rate. Furthermore, after ignition, a bias power of 1000–4000 W can be used to control a faster deposition rate, thereby enabling the formation of TaO in a shorter time. x Membrane.
[0059] Step S5: Form TaO on deposition wafer 17 x Membrane.
[0060] In some embodiments, the deposition time may be 5 to 20 seconds.
[0061] Time is one of the essential factors for ensuring film thickness and resistance. By optimizing the settings for pressure, gas flow rate, and power, the probability of contact between Ta atoms and oxygen atoms on the surface of Ta target 12 can be reduced. This allows as many Ta atoms as possible on the surface of Ta target 12 to detach from the surface of Ta target 12 due to the strong bombardment from a large flow rate of argon and oxygen plasma before being completely oxidized to Ta2O5. Under lower cavity pressure and higher DC bias power, these Ta atoms move towards the deposition wafer 17 at a faster speed. During this process, there is a certain probability that the Ta atoms will combine with a suitable amount of oxygen atoms in the argon and oxygen plasma to form TaO. x Within a short period of 5–20 seconds, the material falls onto the deposition wafer 17, forming a functional TaO layer of a certain thickness. x Membrane.
[0062] After deposition is complete, first turn off the bias power, then stop the oxygen supply, and finally stop the argon supply. Once the state is stable, the deposited wafer 17 can be transferred out of the deposition chamber 10.
[0063] It should be noted that Ta atoms that do not combine with oxygen atoms during the falling process, as pure Ta metal, will also fall onto the surface of deposition wafer 17. As time increases, the surface of Ta target 12 is gradually oxidized by oxygen, forming fully oxidized Ta₂O₅. Therefore, the Ta₂O₅ ejected by argon bombardment increases rapidly, causing a sharp increase in the resistivity of the deposited film. Thus, the deposition rate per second is crucial for monitoring the product. By controlling the time, TaO₂ films of different thicknesses can be obtained. x The final effect of the product can be confirmed by testing the resistance value.
[0064] It should also be noted that after the deposition of the first wafer 17, the atmosphere of the deposition chamber 10 needs to be readjusted by argon gas cleaning between every two consecutive wafers 17. The difference between this cleaning method and the initial cleaning of the deposition chamber 10 before the deposition of the first wafer 17 lies in the argon gas flow rate. Specifically, a sacrificial wafer 16 can be placed (or a baffle can be set), and cleaning can be performed using a smaller argon gas flow rate of 20-30 sccm. The cleaning time can also be appropriately shortened to at least 2 minutes. Furthermore, if the waiting time between the completion of one batch of deposition operations and the next batch does not exceed 24 hours, the cleaning operation can still be performed according to the cleaning requirements between two consecutive wafers 17 in the same batch; if it exceeds 24 hours, the same method as the initial cleaning of the deposition chamber 10 needs to be arranged to perform an oxygen-free atmosphere operation in the deposition chamber 10.
[0065] This invention, based on a pulsed DC physical vapor deposition chamber 10, experimentally determined the distribution range of total argon and oxygen flow rates from 140 to 160 sccm. Based on a single 1R structure operation, TaO was deposited using the method of this invention in the interconnect vias between adjacent TiN interconnect layers. x The film layer was prepared, and its initial resistance was tested. The fabrication results confirmed that the TaO obtained using the method of this invention... x The film's resistance varies over a wide range, from 1E5 to 1E6 ohms, corresponding to a film thickness exceeding [missing information]. The original traditional method of depositing Ta2O5 corresponds to The resistance of the Ta2O5 film will exceed 1E11 ohm.
[0066] Meanwhile, if the traditional method of depositing Ta2O5 is followed, when the film thickness exceeds... Subsequently, because the film material is predominantly Ta₂O₅, it not only has a high electrical resistance but also cannot yield TaO. x The film layer. This indicates that the oxygen pathways in the film formed in this way are not opened, and therefore it has no functional use. Furthermore, through summarizing experimental data from traditional Ta₂O₅ deposition methods, it was found that regardless of the argon-to-oxygen gas flow ratio used, the resistivity and film thickness of the resulting film layer exhibit an exponential positive correlation, and the deposition rate is consistently within [a certain range]. The lower range indicates that these films are all essentially Ta2O5, and there is no fundamental difference in their composition.
[0067] According to the method of the present invention, in one example, when using a total gas flow rate of 148 sccm, the deposition rate is higher than Film thickness reaches The results confirmed that the resistance reached 6E7 ohms; in another example, with a total gas flow rate of 145 sccm, the film thickness could reach... The results confirmed that the resistance reached 3E5 ohms. Therefore, the obtained film thickness not only exceeded... (This can increase the reliability of the device), and the resistance can still be maintained between 1E3 and 1E8. At the same time, the device can be fabricated and exhibits the performance characteristics of a resistive random access memory with periodic high-low resistance switching.
[0068] In summary, this invention avoids the influence of residual Ta₂O₅ in the deposition chamber 10 on the deposition process by creating an oxygen-free deposition environment before deposition. Furthermore, by introducing oxygen only before ignition and appropriately reducing its flow rate relative to the inert gas, excessive contact between oxygen and the Ta target 12 is limited, thus extending the time for the surface of the Ta target 12 to be oxidized to Ta₂O₅. Based on this, a strong bombardment of the Ta target 12 is achieved by using a large flow rate of inert gas to bombard as many Ta atoms as possible in a short time. Under relatively low pressure and high power, these Ta atoms combine with a suitable amount of oxygen atoms in the plasma to generate TaO. x This allows for the formation of functional TaO at higher deposition rates. x Film layer. This invention can utilize conventional physical vapor deposition equipment, and by adjusting and optimizing process parameters, TaO with different thicknesses and oxygen contents can be deposited. x The film layer, and the formed TaO x The film layer has a wide resistance range, which allows for the adjustment of the high and low impedance of the resistive switching memory device, improving device performance and increasing device reliability.
[0069] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.
Claims
1. A type of TaO x The deposition method is characterized by, include: A deposition chamber with an oxygen-free environment is provided, wherein a Ta target and a deposition object are disposed in the deposition chamber; A sufficient amount of the first inert gas is introduced; Before ignition, a proper amount of oxygen with a flow rate less than that of the first inert gas is introduced, and ignition is immediately started, so that the Ta atoms on the surface of the Ta target are knocked off the surface of the Ta target by the plasma of the first inert gas and oxygen formed before the Ta atoms are oxidized to Ta205, move toward the deposition object, and combine with oxygen atoms in the plasma of the first inert gas and oxygen to form TaO in the process, and then fall on the deposition object to form a film. x , fall on the deposition object to form a film.
2. The TaO according to claim 1 x The deposition method is characterized by, During the deposition process, the pressure in the deposition chamber is maintained between 0.002 and 0.02 torr.
3. The TaO according to claim 1 x The deposition method is characterized by, The total gas flow rate when the first inert gas and the oxygen are introduced is 30 to 170 sccm.
4. The TaO according to claim 1 x The deposition method is characterized by, A DC pulse method is used, and a bias power of 1000-4000W is applied after ignition to control the deposition rate.
5. The TaO according to claim 1 x The deposition method is characterized by, Use a bias power of 400-600W to generate ignition.
6. The TaO according to claim 1 x The deposition method is characterized by, The deposition time is 5–20 seconds.
7. The TaO according to claim 1 x The deposition method is characterized by, The provision of a deposition chamber with an oxygen-free environment specifically includes: The Ta target is disposed in the deposition cavity; Introduce a second inert gas; Qi Hui utilizes the formed second inert gas plasma to bombard the Ta target, thereby removing the deposits inside the deposition chamber and the oxides on the surface of the Ta target, creating an oxygen-free environment in the deposition chamber; The deposition object is placed in the deposition chamber.
8. The TaO according to claim 7 x The deposition method is characterized by, The flow rate of the second inert gas is 30-50 sccm, and after the deposition object is placed in the deposition chamber, it continues to be introduced as the first inert gas.
9. The TaO according to claim 1 x The deposition method is characterized by, The distance between the Ta target and the deposition object is 50-80 mm.
10. The TaO according to claim 1 x The deposition method is characterized by, The deposition chamber includes a deposition chamber for performing physical vapor deposition processes.