Method for forming sicn thin film

Abstract

According to an embodiment of the present application, in the formation of a SiCN film, the SiCN film is formed under conditions in which the refractive index of the SiCN film reaches a predetermined reference refractive index or more, thereby improving a deterioration phenomenon caused by the adsorption of moisture or oxygen after the formation of the film, and thereby improving the reliability of the element.

Description

Technical Field

[0001] This invention relates to SiCN thin film formation, and more specifically, to a method for forming SiCN thin films by forming SiCN thin films under film-forming conditions where the refractive index of the SiCN thin film reaches a specific refractive index or higher, thereby improving the degradation phenomenon caused by the adsorption of moisture or oxygen after film formation and thus improving the reliability of the device. Background Technology

[0002] In recent years, with the increasing multi-layering of wiring structures in semiconductor devices, there is a need for high coverage under high aspect ratio.

[0003] Therefore, as Figure 1 As shown, compared to memory elements, non-memory elements such as LOGICs, which require multiple layers of metal to be laminated, mainly use copper, which has low resistance and excellent migration characteristics. Therefore, as a low-k etch-prevention film, PE-SiCN (silicon carbonnitride) films, which have excellent copper barrier layer characteristics and etch-prevention properties, are used instead of the conventional PE-SIN films.

[0004] Furthermore, as the size of devices continues to shrink in the field of memory semiconductors, the metal layer has changed from aluminum to copper, leading to an increase in the frequency of using PE-CVD SiCN thin films.

[0005] As mentioned above, the reason for the increased frequency of using PE-CVD SiCN films is that although replacing the metal layer with a copper layer can reduce wiring resistance, copper has a larger diffusion coefficient, which has a more fatal negative impact on component characteristics. Therefore, the diffusion prevention performance of copper is more important.

[0006] That is, the dielectric constant of SiCN film is 4.9 to 5.2, which is lower than that of SiN film (7.0 to 8.0). Therefore, it is more advantageous in terms of RC delay problem and can achieve excellent diffusion prevention effect against Cu, O and H. Compared with SiN film, it exhibits excellent etch selectivity characteristics, and is therefore suitable for copper diffusion prevention.

[0007] However, for SiCN thin films recently used in ultra-high integration dynamic random access memory (DRAM) or NAND flash memory below 14nm, the problem of SiCN film properties deteriorating and device reliability being severely damaged due to the adsorption of moisture or oxygen after SiCN film formation has emerged.

[0008] Therefore, the need for a new method for forming SiCN thin films under new conditions, where the properties of the SiCN thin films are not degraded by the adsorption of moisture or oxygen, continues to be raised.

[0009] [Support national research and development efforts for this invention]

[0010] [Project Number] 1711139190 (2021)

[0011] [Name of the agency responsible for project management] Nanotechnology Institute

[0012] [Research Topic] Development of a Plasma Enhanced Chemical Vapor Deposition System (PECVD System) that improves Ctch selectivity of SiCN thin films by more than 20% compared to previous methods, and also improves Cu phase adhesion and deposition rate.

[0013] [Contribution Rate] 1 / 2

[0014] [Project Implementing Agency] Nanotechnology Research Institute

[0015] [Research Period] January 1, 2021 – December 31, 2022 (24 months)

[0016] [Project Number] 1425154175

[0017] [Name of the agency responsible for project management] Small and Medium Enterprise Technology Information Promotion Institute

[0018] [Research Topic Title] Development of a Dual-Type 300mm PECVD System for SiCN Thin Film Deposition

[0019] [Contribution Rate] 1 / 2

[0020] [Project Implementing Agency] ISTE Corporation

[0021] [Research Period] June 1, 2021 – May 31, 2025 (48 months) Summary of the Invention

[0022] Technical issues

[0023] Therefore, the object of the present invention is to provide a method for forming SiCN thin films, wherein the SiCN thin film is formed under film-forming conditions in which the refractive index of the SiCN thin film reaches a certain refractive index or higher, thereby improving the degradation phenomenon caused by the adsorption of moisture or oxygen after the film is formed, thereby improving the reliability of the device.

[0024] The objectives of this invention are not limited to those mentioned above. Other objectives and advantages of the invention not mentioned can be understood from the following description and will become more apparent from embodiments of the invention. Furthermore, it is readily apparent that the objectives and advantages of the invention are achieved through the means and combinations thereof described in the claims.

[0025] Problem-solving methods

[0026] The SiCN thin film formation method according to the present invention may include: placing a target wafer in a chuck heater within a cavity; heating the target wafer by driving the chuck heater to achieve a target deposition temperature of 200–550°C; setting the target process pressure within the cavity to 2.0–10.0 Torr; and injecting a plasma excitation gas, a first reactive gas, and a second reactive gas for SiCN thin film formation into the cavity where the target deposition temperature and the target process pressure are set, thereby forming a SiCN thin film with a refractive index of 1.80–2.40 on the target wafer.

[0027] Furthermore, the plasma excitation gas is selected from at least one of He, Ne, Ar, Xe, Kr, and N2, and flows into the cavity at a rate of 300 to 3000 sccm. The first reaction gas is selected from either 3 MS or 4 MS, and the second reaction gas is NH3. The distribution ratio of the first reaction gas and the second reaction gas can be adjusted to 1:1.2 to 1:4.

[0028] Furthermore, the flow rate of the plasma excitation gas and the flow rate of the second reaction gas can be inversely proportional.

[0029] Furthermore, the aforementioned RF power can be set to 150–800 watts.

[0030] Furthermore, when the target deposition temperature is set to 200–350°C, the target process pressure can be set to 2.0–4.5 Torr, the flow rate of the plasma excitation gas can be set to 1000–3000 sccm, and the RF power can be set to 650–1500 Watts.

[0031] Furthermore, when the target material process pressure is set to 4.5 to 10.0 Torr, the target material deposition temperature can be set to 350 to 550°C, the flow rate of the plasma excitation gas can be set to 1000 to 3000 sccm, and the RF power can be set to 650 to 1500 Watts.

[0032] Furthermore, the SiCN thin film formation method according to the present invention may include: the step of placing a target wafer in a chuck heater within a cavity; the step of forming a first SiCN thin film with a first thickness and a refractive index of less than 1.80; and the step of forming a second SiCN thin film with a second thickness and a refractive index of 1.80 or more on the upper part of the first SiCN thin film, wherein the ratio of the first thickness to the second thickness may be set to 1:1 to 1:2.

[0033] Furthermore, the step of forming the second SiCN thin film may include: heating the target wafer for forming the first SiCN thin film by driving the clamp heater, so that the temperature of the target wafer reaches a target deposition temperature of 200 to 550°C; setting the target process pressure in the cavity to 2.0 to 10.0 Torr; and injecting plasma excitation gas, a first reaction gas and a second reaction gas for forming SiCN thin films into the cavity with the target deposition temperature and the target process pressure set, to form the second SiCN thin film with a refractive index of 1.80 to 2.40 on the target wafer.

[0034] Furthermore, the plasma excitation gas is selected from at least one of He, Ne, Ar, Xe, Kr, and N2, and flows into the cavity at a rate of 300 to 3000 sccm. The first reaction gas is selected from either 3 MS or 4 MS, and the second reaction gas is NH3. The distribution ratio of the first reaction gas and the second reaction gas can be adjusted to 1:1.2 to 1:4.

[0035] Furthermore, the flow rate of the plasma excitation gas and the flow rate of the second reaction gas can be inversely proportional.

[0036] Furthermore, the aforementioned RF power can be set to 150–800 watts.

[0037] Furthermore, the target deposition temperature can be set to 200–350°C, the target process pressure can be set to 2.0–4.5 Torr, the flow rate of the plasma excitation gas can be set to 1000–3000 sccm, and the RF power can be set to 650–1500 Watts.

[0038] Furthermore, when the target material process pressure is set to 4.5 to 10.0 Torr, the target material deposition temperature can be set to 350 to 550°C, the flow rate of the plasma excitation gas can be set to 1000 to 3000 sccm, and the RF power can be set to 650 to 1500 Watts.

[0039] Invention Effects

[0040] According to one embodiment of the present invention, in the formation of SiCN thin films, SiCN thin films are formed under film-forming conditions where the refractive index of the SiCN thin film reaches a specific refractive index or higher. As a result, the degradation phenomenon caused by the adsorption of moisture or oxygen after the formation of the thin film is improved, thereby improving the reliability of the device.

[0041] The above-mentioned effects and the specific effects of the present invention will be described together with the following specific embodiments. Attached Figure Description

[0042] Figure 1 This is an example of a cross-sectional view of a conventional storage element and a non-storage element.

[0043] Figure 2 This is a flowchart illustrating an example of a SiCN thin film formation method according to an embodiment of the present invention.

[0044] Figure 3 A simplified cross-sectional view of the process cavity for forming a SiCN thin film according to an embodiment of the present invention.

[0045] Figure 4 This is a flowchart illustrating an example of a method for forming SiCN thin films with different refractive indices according to an embodiment of the present invention.

[0046] Figure 5 This represents the refractive index of the SiCN thin film determined based on various film formation conditions, and the degradation characteristics of the SiCN thin film based on the refractive index.

[0047] Figures 6 to 10 Example graphs of X-ray photoelectron spectroscopy (XPS) of SiCN thin films with different refractive indices according to embodiments of the present invention. Detailed Implementation

[0048] The working principle of the present invention will now be described in detail with reference to the accompanying drawings. In describing the present invention, detailed descriptions of well-known functions or structures will be omitted where it is deemed that such descriptions might unnecessarily obscure the spirit of the invention. Furthermore, the terminology used hereafter is defined in consideration of the functions in the present invention and may vary depending on the intentions or conventions of the user or operator. Therefore, it should be defined based on the entire contents of this specification.

[0049] Figure 2 This is a flowchart illustrating an example of a SiCN thin film formation method according to an embodiment of the present invention.

[0050] Figure 3 A simplified cross-sectional view of the process cavity for forming a SiCN thin film according to an embodiment of the present invention.

[0051] First, such as Figure 2 As shown, the target wafer 304, which will be used for SiCN thin film deposition, is placed on top of the chuck heater 302 inside the deposition vacuum chamber 300 (S200). A Cu layer or silicon oxide film, etc., may be formed on top of this target wafer.

[0052] Next, the clamp heater is driven to heat the target wafer at a target deposition temperature in the range of 200 to 550°C (S202), and the target process pressure in the cavity is set to 2.0 to 10.0 Torr (S204).

[0053] Next, the plasma excitation gas and the first and second reaction gases for SiCN thin film formation are injected into the cavity (S206).

[0054] Next, RF power is applied to the electrode section inside the cavity, and the first and second reaction gases are separated into ions by means of plasma excitation gas and deposited on the upper part of the silicon oxide film to form a SiCN thin film (S208).

[0055] At this point, as mentioned above, a SiCN thin film is formed. When the refractive index of the SiCN thin film is less than 1.80, the properties of the SiCN thin film deteriorate due to the adsorption of moisture or oxygen after its formation, resulting in serious damage to the reliability of the components.

[0056] Therefore, in one embodiment of the present invention, the flow rate of plasma excitation gas with a refractive index of 1.80 to 2.40 of the SiCN thin film is determined, and the distribution ratio of the first reactant gas and the second reactant gas is determined to form a SiCN thin film (S208).

[0057] At this time, for example, at least one of the following plasma excitation gases, such as He, Ne, Ar, Xe, Kr, and N2, is injected into the cavity at a flow rate of 300 to 3000 sccm.

[0058] Furthermore, for example, the first reactant gas is selected from 3MS and 4MS, and NH3 is selected as the second reactant gas and injected into the cavity.

[0059] At this point, the distribution ratio of the first reactant gas and the second reactant gas within the cavity is preferably in the range of 1:12 to 1:4, but is not limited to this.

[0060] Furthermore, the RF power is set to 150–1500 Watt.

[0061] Furthermore, the flow rates of the second reactant gas and the plasma excitation gas are set inversely proportional. That is, for example, if the ratio of the second reactant gas is decreased, the flow rate of the plasma excitation gas is increased inversely proportional to it, and if the ratio of the second reactant gas is increased, the flow rate of the plasma excitation gas is decreased.

[0062] As described above, by setting the target deposition temperature, target process pressure, and target RF power for the target wafer, and by adjusting the flow rate of the plasma excitation gas and the ratio between the first and second reactant gases, a SiCN thin film with a refractive index of 1.80 to 2.40 can be formed, and a SiCN thin film that does not deteriorate due to the adsorption of moisture or oxygen after the formation of the SiCN thin film can be formed.

[0063] Furthermore, as another embodiment, when the target deposition temperature must be reduced to 200–550°C, a SiCN thin film with a refractive index of 1.80 or higher can be formed by reducing the target process pressure, increasing the flow rate of the plasma excitation gas, and increasing the RF power.

[0064] At this time, for example, when the target deposition temperature is reduced from 200-550°C to 200-350°C, preferably, the target process pressure is set to a lower value of 2.0-4.5 Torr, the flow rate of the plasma excitation gas is set to 1000-3000 sccm, and the RF power is set to 650-1500 Watt.

[0065] Furthermore, as another embodiment, when the target material process pressure must be increased from 2.0 to 10.0 Torr, a SiCN thin film with a refractive index of 1.80 or higher can be formed by increasing the target material deposition temperature, increasing the flow rate of the plasma excitation gas, and increasing the RF power.

[0066] In this case, for example, when the target material process pressure is to be increased from 2–10 Torr to 4.5–10.0 Torr, the target material deposition temperature is set to the range of 350–550°C, and the flow rate of the plasma excitation gas is set to 1000–3000 sccm, most preferably 1500 sccm or higher. Furthermore, the RF power can be set to 650–1500 Watt.

[0067] Figure 4 This is a flowchart illustrating an example of a method for forming SiCN thin films with different refractive indices according to an embodiment of the present invention.

[0068] First, such as Figure 4 As shown, a target wafer for SiCN thin film deposition is placed on top of a clamp heater inside a vacuum chamber for deposition (S400). A silicon oxide film can be formed on top of this target wafer.

[0069] Next, a first SiCN thin film with a first thickness of less than 1.80 is formed on the target wafer as the first film formation condition (S402). At this time, the first film formation condition can mean one of the general film formation conditions used in the formation of conventional SiCN thin films, regardless of the refractive index, but is not limited to this.

[0070] Next, a second SiCN thin film with a second thickness of 1.80 to 2.40, which is the second film-forming condition according to an embodiment of the present invention, is formed on the upper part of the target wafer on which the first SiCN thin film is formed (S404). At this time, the ratio of the first thickness to the second thickness is preferably in the range of 1:1 to 1:2, and the second thickness of the second SiCN thin film is preferably formed to be 10 to 12 nm, for example, but is not necessarily limited to this.

[0071] The process of forming the second SiCN thin film is described in more detail below. As explained above, firstly, the chuck heater is driven to heat the target wafer for forming the first SiCN thin film at a target deposition temperature in the range of 200 to 550-500°C, and the target process pressure in the cavity is set to 2 to 10 Torr.

[0072] Next, the plasma excitation gas and the first and second reaction gases for SiCN thin film formation are injected into the cavity.

[0073] Next, RF power is applied to the electrode section inside the cavity. The first and second reactant gases are separated into ions by means of plasma excitation gas and deposited on the upper part of the silicon oxide film to form a second SiCN thin film.

[0074] At this time, for example, at least one of the following plasma excitation gases, such as He, Ne, Ar, Xe, Kr, and N2, is injected into the cavity at a rate of 300 to 3000 sccm.

[0075] Furthermore, for example, the first reactant gas is selected from 3MS and 4MS, and NH3 is selected as the second reactant gas and injected into the cavity.

[0076] At this point, the distribution ratio of the first reactant gas and the second reactant gas within the cavity is preferably in the range of 1:12 to 1:4, but is not limited to this.

[0077] Furthermore, the RF power is set to 150–800 Watt.

[0078] Furthermore, the flow rates of the second reactant gas and the plasma excitation gas are set inversely proportional. That is, for example, if the ratio of the second reactant gas is decreased, the flow rate of the plasma excitation gas is increased inversely proportional to it, and if the ratio of the second reactant gas is increased, the flow rate of the plasma excitation gas is decreased.

[0079] As described above, by setting the target deposition temperature, target process pressure, and target RF power for the target wafer used to form the first SiCN thin film, and by adjusting the flow rate of the plasma excitation gas and the cavity distribution ratio between the first and second reactant gases, a second SiCN thin film with a refractive index of 1.80 to 2.40 can be formed as a capping layer. After the SiCN thin film is formed, a SiCN thin film that does not deteriorate due to the adsorption of moisture or oxygen can be formed.

[0080] On the other hand, in one embodiment of the present invention, when the refractive index of the SiCN thin film is less than 1.80, degradation was found to occur through experiments.

[0081] Figure 5 This represents the refractive index of the SiCN thin film determined based on various film formation conditions, and the degradation characteristics of the SiCN thin film based on the refractive index.

[0082] at this time, Figure 5 This describes the characteristics of SiCN films deteriorating due to moisture or atmospheric oxygen after being exposed to HAST conditions following the formation of SiCN films with different refractive indices using different process conditions. HAST conditions are assumed, for example, to be exposing the SiCN film to water at 110°C, 85% relative humidity, and 122 kPa for 96 hours.

[0083] refer to Figure 5 As shown in Figure 510, for SiCN films with a refractive index below 1.80, it can be seen that after treatment under HAST conditions, they are oxidized and their thickness increases.

[0084] Figures 6 to 10 Example graphs of X-ray photoelectron spectroscopy (XPS) of SiCN thin films with different refractive indices according to embodiments of the present invention.

[0085] First, the states of the reference samples (SiCN thin films) before and after the HAST conditions are shown. Figure 6 It can be seen that oxygen inflow into the SiCN thin film does not occur at least during the film formation process within the vacuum chamber.

[0086] Furthermore, no oxygen inflow was observed in sample #1 even when exposed to the atmosphere, while a large amount of oxygen inflow was observed in the As-depo of sample #2, and the oxygen inside the film flowed into the interior of the SiCN film after being exposed to the atmosphere.

[0087] That is, even after HAST treatment, no additional changes were observed in the oxygen content of the film for sample #1, nor was any change in thickness before and after HAST. However, for sample #2, a surge in oxygen content and a significant increase in film thickness were observed.

[0088] Furthermore, it can be confirmed that the difference between sample #1 and sample #2 is based on the difference in refractive index (RI) of the SiCN thin film.

[0089] At this point, when a refractive index of 1.80 is set as the reference refractive index, the refractive index is lower than the reference refractive index, which means that the density of the film is relatively low, and in this case, it can be considered unable to withstand oxygen inflow. Furthermore, this difference in As depo is as... Figure 5 As shown, the differences are more pronounced after HAST processing.

[0090] That is, when the refractive index is below 1.80, the density of the film decreases, and atmospheric oxygen is adsorbed into the film. Under these conditions, if the SiCN film is exposed to a high-humidity environment, the film itself will be oxidized and expand, leading to a sharp deterioration in the film's properties.

[0091] Then, refer to Figure 7 For samples #4 and #5 (SiCN thin films), the TMS:NH3 ratio was set to 1:3.65. Unlike the ratio of 1:9.3 for sample #1, the ratio of TMS was increased and the refractive index was less than 1.80.

[0092] In this case, it can be seen that the oxygen content in the As-depo film is higher than that in sample #1, the thickness changes greatly before and after HAST, and a sharp increase in oxygen content can be seen after HAST treatment.

[0093] That is, for samples #4 and #5, the reason for the decrease in refractive index of SiCN film is different from that of sample #2. However, just like sample #2, if SiCN film is exposed to a high humidity environment, the film itself will be oxidized and expand, resulting in a sharp deterioration of film properties.

[0094] Then, refer to Figure 8 For samples #6, #7, #8, and #9 (SiCN thin films), although the ratio of TMS to NH3 varies between 1:12 and 1:6, the refractive index of all samples is above 1.80.

[0095] In this case, the oxygen content of the As-depo state is reduced to below 1.5%, so it is not oxidized even after HAST treatment and still maintains a low oxygen content. The thickness change before and after HAST is almost negligible.

[0096] then, Figure 9 The refractive index variation and its impact based on process pressure changes in samples #10 and #11 (SiCN thin films) were evaluated.

[0097] For sample #10, compared to the severely oxidized sample #2 mentioned above, the process pressure was further reduced. The results confirmed a refractive index change of over 1.80 and an oxygen content in the As-depo state of less than 1.2%, which is very low. That is, it can be confirmed that even after HAST treatment, it is not oxidized and maintains a low oxygen content, and there is no increase in thickness.

[0098] For sample #11, compared to sample #1 which had no oxidation issues, only the process pressure was further increased. The results showed that the refractive index change was less than 1.80, the oxygen content in the As-depo state reached a very high 16%, and the oxygen content increased dramatically after HAST treatment, as did the thickness.

[0099] For sample #12, compared to sample #1 which had no oxidation issues, the RF power was further reduced. The results showed that the refractive index change was less than 1.80, the oxygen content in the As-depo state reached over 20%, which is very high. After HAST treatment, the oxygen content increased dramatically, and the thickness also increased significantly.

[0100] For sample #13, compared to sample #1 which had no oxidation issues, the process temperature was further reduced. The results showed a refractive index change of less than 1.80, and an oxygen content in the As-depo state exceeding 25%, which is very high. After HAST treatment, the oxygen content increased dramatically, and the thickness also increased significantly.

[0101] That is, for samples #11, #12, and #13, the reasons for the decrease in refractive index are different compared to sample #1. However, when the refractive index decreases unconditionally regardless of these reasons, the oxygen content in the As-depo state is observed to increase to a higher level. Furthermore, in this state, similar to HAST treatment, when the SiCN film is exposed to a high-humidity environment, the film itself is oxidized and expands, the oxygen content within the film increases dramatically, and the film properties deteriorate rapidly.

[0102] In contrast to sample #2, sample #10, which only had its process pressure reduced, showed an increased refractive index of over 1.80 and a very low oxygen content of less than 1.2% in the As-depo state. It was not oxidized after HAST treatment and maintained a low oxygen content.

[0103] Next, refer to Figure 10 For samples #14 and #15 (SiCN thin films), compared to sample #1, the total flow rate of the plasma excitation gas was maintained in the same manner, but the structure of the reaction gas was adjusted differently.

[0104] The results show that, for samples #14 and #15, similar to sample #1, they maintain a low oxygen content in the As-depo state, with a refractive index above 1.80.

[0105] Furthermore, after HAST treatment, certain differences were observed only in the degree of oxygen diffusion near the surface. Similar to sample #1, a surge in oxygen content and an increase in thickness were observed.

[0106] On the other hand, in cases where film formation is unavoidable under conditions where the refractive index is less than 1.80, such as Figure 6 As shown in sample #3, a first SiCN film with a refractive index less than 1.80 and a second SiCN film with a refractive index greater than 1.80 can be deposited sequentially.

[0107] In this scenario, a first SiCN film with a refractive index less than 1.80 is first deposited to the required thickness. Then, an in-situ process is used to immediately deposit a second SiCN film with a refractive index greater than 1.80 as a capping layer on top of the first SiCN film. This way, even if the film with a refractive index less than 1.80 is susceptible to oxygen inflow, the inflow of atmospheric oxygen can be blocked by the second SiCN film as a capping layer. Therefore, even when exposed to high humidity environments, the degradation of the SiCN film's properties is prevented.

[0108] Next, refer to Figure 11 For samples #16 and #17 (SiCN thin films), the process gas remained unchanged compared to sample #1, with only the temperature increasing.

[0109] As the temperature increases, the density of the film increases, and the refractive index increases. This confirms that sample #16 has a higher refractive index than sample #1, exhibiting higher oxidation resistance.

[0110] For sample #17, helium (He) and nitrogen (N2) were not introduced to reduce the refractive index at 400°C. The results confirmed a reduction in refractive index to 1.749. Upon exposure to air, some of the sample was immediately oxidized, and HAST treatment confirmed an increase in oxygen content to 50%.

[0111] Next, refer to Figure 12 For samples #18 and #19 (SiCN thin films), the process gas remained unchanged compared to sample #1, with only the RF power increasing.

[0112] If the RF power increases, the density of the thin film increases, and the refractive index increases. This confirms that sample #18 has an increased refractive index compared to sample #1, exhibiting high oxidation resistance.

[0113] For sample #19, helium and nitrogen were not introduced to reduce the refractive index under RF power of 1200W. The results confirmed a reduction in refractive index to 1.763. Upon exposure to air, a portion of the sample was immediately oxidized, and HAST treatment confirmed an increase in oxygen content to 50%.

[0114] Next, refer to Figure 13 Compared to sample #1, samples #20 and #21 (SiCN thin films) had no change in process gas, but the temperature was increased to 550℃.

[0115] As the temperature increases, the density and refractive index of the film increase. This confirms that sample #20 has a higher refractive index than sample #1, exhibiting higher oxidation resistance.

[0116] For sample #21, helium and nitrogen were not added to reduce the refractive index at 550°C. The results confirmed that although the refractive index decreased to 1.920, it still exhibited a high refractive index and high oxidation resistance.

[0117] As described above, according to an embodiment of the present invention, in the formation of SiCN thin films, SiCN thin films are formed under film-forming conditions where the refractive index of the SiCN thin film reaches a specific refractive index or higher. As a result, the degradation phenomenon caused by the adsorption of moisture or oxygen after the formation of the thin film is improved, thereby improving the reliability of the device.

[0118] As described above, the present invention has been illustrated with reference to the accompanying drawings, but the invention is not limited to the embodiments and drawings disclosed in this specification. It is evident that those skilled in the art can make various modifications within the scope of the technical concept of the invention. Furthermore, even in cases where embodiments of the invention are not described above and the effects of the structure are not explicitly stated, predictable effects can obviously be determined based on this structure.

[0119] Explanation of reference numerals in the attached figures

[0120] 300: Cavity; 302: Jacket heater

[0121] 304: Target wafer

Claims

1. A method for forming a SiCN thin film, characterized by, include: The step of placing the target wafer into the cavity of the clamp heater; The step of heating the target wafer by driving the clamp heater to bring the temperature of the target wafer to the target deposition temperature of 350°C. The step of setting the target material process pressure in the cavity to 2.0~4.2 Torr; The step of injecting plasma excitation gas, a first reactive gas, and a second reactive gas for SiCN thin film formation into a cavity that sets the target deposition temperature and the target process pressure, thereby forming a SiCN thin film with a refractive index of 1.80~1.857 on the target wafer. The plasma excitation gas is selected from at least one of He, Ne, Ar, Xe, Kr, and N2, and flows into the cavity at a rate of 300-3000 sccm. The first reactant gas was selected to be either 3 MS or 4 MS. The second reacting gas is NH3. The distribution ratio of the first reactant gas and the second reactant gas is adjusted to 1:12 to 1:

4. The flow rate of the plasma excitation gas is inversely proportional to the flow rate of the second reaction gas. The RF power applied within the cavity is set to 650 watts.

2. A method for forming SiCN thin films, characterized in that, include: The step of placing the target wafer into the cavity of the clamp heater; The step of forming a first SiCN thin film with a first thickness and a refractive index of less than 1.80; The step of forming a second SiCN film with a refractive index of 1.80~1.857 on top of the first SiCN film. The ratio of the first thickness to the second thickness is set to 1:1 to 1:

2. The step of forming the second SiCN thin film includes: The step of heating the target wafer that forms the first SiCN thin film by driving the clamp heater, so that the temperature of the target wafer reaches the target deposition temperature of 350°C. The step of setting the target material process pressure in the cavity to 2.0~4.2 Torr; The step of injecting plasma excitation gas, a first reactive gas, and a second reactive gas for SiCN thin film formation into a cavity that sets the target deposition temperature and the target process pressure, to form a second SiCN thin film with a refractive index of 1.80~1.857 on the target wafer. The plasma excitation gas is selected from at least one of He, Ne, Ar, Xe, Kr, and N2, and flows into the cavity at a rate of 300-3000 sccm. The first reactant gas was selected to be either 3 MS or 4 MS. The second reacting gas is NH3. The distribution ratio of the first reactant gas and the second reactant gas is adjusted to 1:12 to 1:

4. The flow rate of the plasma excitation gas is inversely proportional to the flow rate of the second reaction gas. The RF power applied within the cavity is set to 650 watts.

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