High-stress silicon nitride film and method of forming same

Abstract

The application discloses a method for forming high-stress silicon nitride film, which comprises the following steps: before depositing the silicon nitride film on a substrate, introducing a silicon-containing gas, silane, ammonia and laughing gas into a reaction chamber, and depositing a silicon oxide film on the surface of the chamber to protect the chamber. The application controls the stress and thickness of the deposited silicon oxide film, so that the silicon oxide film is not easy to fall off particles when depositing the high-stress silicon nitride film, thereby reducing the particle defects of the formed high-stress silicon nitride film. After two ten thousand pieces of continuous film coating by using the method of the application, the particle defects are still stable, and by using the optimal process parameter condition, the number of particles can be stably maintained below 10.

Description

Technical Field

[0001] This invention relates to the field of silicon nitride thin film preparation technology, and particularly to a method for forming a high-stress silicon nitride thin film. Background Technology

[0002] Silicon nitride thin films possess excellent optoelectronic and mechanical properties, finding wide applications in integrated circuits, microelectromechanical systems (MEMS), solar cells, and display devices. Plasma-enhanced chemical vapor deposition (PECVD) has become one of the main methods for preparing silicon nitride thin films due to its high deposition efficiency, good film uniformity, and flexible operation. Currently, the process for forming high-stress silicon nitride thin films mainly involves reacting silane and ammonia in a plasma atmosphere to generate silicon nitride. Using a large amount of nitrogen as the atmosphere gas and a small amount of reactant gas, a high-tensile-stress silicon nitride thin film is formed, playing a crucial role in device manufacturing. However, due to the high tensile stress, when this silicon nitride thin film is deposited on the cavity surface as a protective film, it easily forms sheet-like films that fall off the reaction cavity surface. This increases the number of particles in the subsequent deposition of the high-stress silicon nitride thin film on the substrate, resulting in a limited number of deposition cycles and thus restricting the utilization rate of the deposition equipment. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for forming high-stress silicon nitride thin films.

[0004] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0005] This invention provides a method for forming a high-stress silicon nitride thin film, comprising the following steps:

[0006] S1. Control the temperature of the vacuum reaction chamber of the PECVD equipment to 350-400 ℃, then remove impurities from the chamber and fluorinate the upper electrode plate of the vacuum reaction chamber to form aluminum fluoride.

[0007] S2. After purging the vacuum reaction chamber with inert gas, introduce silicon-containing gases silane, ammonia and nitrous oxide for pretreatment; then continue to introduce silicon-containing gases silane, ammonia and nitrous oxide into the vacuum reaction chamber, and control the radio frequency power to 1200-1300 W to deposit a protective silicon oxide film on the surface of the chamber.

[0008] S3. After purging the vacuum reaction chamber with inert gas, nitrous oxide is introduced and the radio frequency power is controlled at 500-1000 W for a certain period of time.

[0009] S4. Place the substrate on the base inside the vacuum reaction chamber, and introduce silicon-containing gases silane and ammonia into the vacuum reaction chamber for pretreatment; then continue to introduce silicon-containing gases silane and ammonia into the vacuum reaction chamber, while simultaneously introducing N2, to deposit a high-stress silicon nitride thin film on the substrate surface.

[0010] In step S2, the specific steps for pretreatment are as follows: introduce silicon-containing gases silane (400-500 sccm), ammonia (130-170 sccm), and nitrous oxide (4000-5000 sccm) into the vacuum reaction chamber for 5-10 seconds.

[0011] In step S2, during the step of depositing a silicon oxide film to protect the cavity surface, the pressure inside the vacuum reaction chamber is maintained at 1–10 torr, the flow rates of silicon-containing gases silane, ammonia, and nitrous oxide are the same as those in the pretreatment, the deposition time is 17–29 s, the thickness of the deposited silicon oxide film is 1000–2000 Å, and the stress is -50–-75 MPa.

[0012] Preferably, in the step of depositing a protective silicon oxide film on the surface of the cavity, the deposition time is controlled to be 17-21 s, and the thickness of the deposited silicon oxide film is 1000-1400 Å.

[0013] Preferably, the ratio of the silicon-containing gas silane to ammonia is 3:1.

[0014] Preferably, in step S3, the flow rate of the nitrous oxide is 5000-10000 sccm, so that the pressure is stabilized at 2-10 torr.

[0015] Preferably, in step S3, the processing time is 10-15 seconds.

[0016] Preferably, in step S1, the specific steps for removing impurities from the cavity and fluorinating the upper electrode plate of the vacuum reaction chamber to form aluminum fluoride are as follows: introducing 2000-6000 sccm of nitrogen fluoride gas and 4000-12000 sccm of argon gas that have dissociated into fluoride ions outside the chamber for 30-60 s, and maintaining the pressure inside the vacuum reaction chamber at 1-10 torr.

[0017] Preferably, in step S4, the specific steps of the pretreatment are as follows: 30-80 sccm of silicon-containing silane and 60-160 sccm of ammonia are introduced into the vacuum reaction chamber for 5-10 s.

[0018] Preferably, in step S4, during the step of depositing a high-stress silicon nitride thin film on the substrate surface, the pressure in the vacuum reaction chamber is maintained at 1–10 torr, silicon-containing gases silane (30–80 sccm) and ammonia (60–160 sccm) are introduced, N2 (2000–4000 sccm) is introduced, the radio frequency power is controlled at 50–150 W, the deposition time is 50–100 s, and the thickness of the deposited silicon nitride film is 100–500 Å.

[0019] Preferably, the ratio of the silicon-containing gas silane to ammonia is 1:2.

[0020] The present invention also provides a high-stress silicon nitride thin film prepared according to the aforementioned method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) The present invention introduces a silicon oxide film with low stress (-50 to -100 MPa) and suitable thickness (1000 to 2000 Å) as a protective cavity film, so that the silicon oxide film is less likely to lose particles when depositing high-stress silicon nitride film, thereby reducing particle defects in the formed high-stress silicon nitride film.

[0023] 2) The present invention also protects the base by treating the surface of the cavity and the base with nitrous oxide plasma after forming the silicon oxide film of the protective cavity and before depositing the high-stress silicon nitride film.

[0024] 3) Using the method of the present invention, after continuous coating of 20,000 pieces, the particle defects remain stable, and by adopting the optimal process parameters, the number of particles can be kept stable at less than 10. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 The particle size distribution of the high-stress silicon nitride thin film prepared by the method in Comparative Example 1 is shown under different numbers of coated films.

[0027] Figure 2 The image shows the particle size distribution of the high-stress silicon nitride thin film prepared by the method in Example 1 under different numbers of coated films;

[0028] Figure 3The image shows the particle size distribution of the high-stress silicon nitride thin film prepared by the method in Example 2 under different numbers of coated films;

[0029] Figure 4 The image shows the particle size distribution of the high-stress silicon nitride thin film prepared by the method in Example 3 under different numbers of coated films. Detailed Implementation

[0030] The present invention will be described in detail below with reference to specific embodiments and examples, thereby making the advantages and various effects of the present invention more clearly apparent. Those skilled in the art should understand that these specific embodiments and examples are for illustrative purposes only and are not intended to limit the present invention.

[0031] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In the event of any conflict, this specification shall prevail.

[0032] Unless otherwise specified, all raw materials, reagents, instruments, machines and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0033] Prior to this application, existing methods for preparing high-stress silicon nitride thin films typically use silicon-containing gases silane and ammonia as the reaction source gases, and nitrogen is introduced to deposit a silicon nitride thin film on the surface of a vacuum reaction chamber. However, due to the high tensile stress, this silicon nitride thin film tends to form sheet-like films on the surface of the reaction chamber, which then fall onto the silicon nitride thin film deposited on the substrate during subsequent deposition steps. This results in a significant increase in the number of particles in the high-stress silicon nitride thin film deposited on the substrate as the number of coated sheets increases.

[0034] Based on this, the present invention provides a method for forming a high-stress silicon nitride thin film, the method comprising the following steps:

[0035] 1. A PECVD vacuum reaction chamber using aluminum (Al) as the chamber wall material and aluminum nitride (ALN) as the high-temperature resistant substrate, wherein the temperature of the vacuum reaction chamber is controlled at 350–400 °C and maintained at this temperature in subsequent steps, high-stress silicon nitride thin films can be prepared at this temperature; for example, the controlled temperature can be any one value or a range between any two values ​​from 350 °C, 355 °C, 360 °C, 365 °C, 370 °C, 375 °C, 380 °C, 385 °C, 390 °C, 395 °C, to 400 °C, and this invention does not impose any particular limitation, and it has little impact on the performance of the final high-stress silicon nitride thin film.

[0036] 2. Introduce 2000–6000 sccm of nitrogen fluoride (after dissociation into fluoride ions outside the chamber) and 4000–12000 sccm of argon for 30–60 seconds. Maintaining a pressure of 1–10 torr within the PECVD vacuum reaction chamber, remove chamber impurities under this environment and form aluminum fluoride on the upper electrode plate. The flow rate of nitrogen fluoride can be adjusted arbitrarily within the range of 2000–6000 sccm depending on the chamber size, and the flow rate of argon should be adjusted accordingly based on the ratio of nitrogen fluoride to argon (this step is mainly for fluorinating the upper electrode plate after fluoride ion treatment; the optimal concentration of effective fluoride ions is achieved when the ratio of nitrogen fluoride (NF3) to argon (AR) is 1:2. Without this step, the coating process in the next step will be affected, and the adsorption capacity will decrease).

[0037] 3. After purging the PECVD vacuum reaction chamber with an inert gas (such as helium), introduce silicon-containing gases silane (SIH4) at 400–500 sccm, ammonia (NH3) at 130–170 sccm, and nitrous oxide (N2O) at 4000–5000 sccm for 5–10 s for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 1–10 torr, continue introducing the same flow rates of silicon-containing gases silane, ammonia, and nitrous oxide into the vacuum reaction chamber to ensure pressure stability. Control the RF power at 1000–1400 W and the deposition time at 17–29 s to deposit a silicon oxide thin film on the surface of the vacuum reaction chamber with a thickness of approximately 1000–2000 Å and a film stress of -50 to -100. MPa, mainly serves to protect the cavity; the flow rates of silane, ammonia and nitrous oxide can be adjusted within the aforementioned flow ranges, with the preferred flow ratio of silane and ammonia being 3:1. The radio frequency (RF) power and deposition time used in depositing silicon oxide thin films can be adjusted within the aforementioned power range. By varying the RF power and deposition time, silicon oxide thin films with different stresses and thicknesses can be obtained. Preferably, the RF power is 1200–1400 W, resulting in a silicon oxide thin film stress of -50 to -100 MPa, which has lower stress. More preferably, the RF power is 1200–1300 W, resulting in a silicon oxide thin film stress of -50 to -75 MPa. Most preferably, the RF power is 1200 W, resulting in a silicon oxide thin film stress of -50 MPa. Preferably, the deposition time is 17–25 s, resulting in a silicon oxide thin film thickness of 1000–1800 Å. More preferably, the deposition time is 17–21 s, resulting in a silicon oxide thin film thickness of 1000–1400 Å. Most preferably, the deposition time is 21 s, resulting in a silicon oxide thin film thickness of 1400 Å.

[0038] 4. After purging the vacuum reaction chamber of PECVD with an inert gas (such as helium), introduce N2O at 5000-10000 sccm, ensuring the pressure is stable at 2-10 torr, controlling the RF power at 500-1000 W, and the processing time at 10-15 s, to remove unreacted SI-H bonds on the chamber surface and protect the base.

[0039] 5. Then, place the substrate (a 12-inch wafer) on the base of the PECVD vacuum reaction chamber. Introduce 30–80 sccm of silicon-containing silane (SIH4) and 60–160 sccm of ammonia (NH3) into the PECVD vacuum reaction chamber for 5–10 s as pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 1–10 torr, continue introducing the same flow rates of silicon-containing silane and ammonia into the vacuum reaction chamber, and introduce N2 at 2000–4000 sccm to ensure pressure stability. Control the RF power at 50–150 W and the deposition time at 50–100 s to deposit a silicon nitride thin film with a thickness of approximately 100–500 Å on the surface of the 12-inch wafer. The flow rates of silane and ammonia can be adjusted within the aforementioned flow ranges, with a preferred flow ratio of 1:2. The flow rate of nitrogen can also be adjusted within the aforementioned flow ranges, ensuring stable pressure.

[0040] Example

[0041] The method for forming low-temperature silicon nitride thin films of this application will be described in detail below with reference to embodiments and experimental data.

[0042] Comparative Example 1

[0043] This comparative example provides a method for forming a high-stress silicon nitride thin film, the specific steps of which are as follows:

[0044] 1) A PECVD vacuum reaction chamber with Al as the cavity wall material and aluminum nitride (ALN) as the high-temperature resistant base is used. The temperature of the vacuum reaction chamber is controlled at 380 °C and is kept constant in subsequent steps.

[0045] 2) Introduce 4000 sccm of nitrogen fluoride (introduced after dissociation into fluoride ions outside the chamber) and 8000 sccm of argon for 40 s. Under the condition of maintaining the pressure in the PECVD vacuum reaction chamber at 5 torr, remove chamber impurities and form aluminum fluoride on the upper electrode plate of the vacuum reaction chamber.

[0046] 3) Introduce 50 sccm of silicon-containing silane (SiH4) and 100 sccm of ammonia (NH3) into the PECVD vacuum reaction chamber for 8 s. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, continue to introduce 50 sccm of silicon-containing silane (SiH4) and 100 sccm of ammonia (NH3), and introduce 3000 sccm of nitrogen (N2) to ensure pressure stability. Control the radio frequency power at 100 W and the deposition time at 50 s to deposit a silicon nitride film with a thickness of approximately 200 Å on the reaction surface of the vacuum chamber, which mainly serves to protect the chamber.

[0047] 4) Then, a 12-inch wafer is placed on the base of the vacuum reaction chamber. 50 sccm of silicon-containing gas silane (SiH4) and 100 sccm of ammonia (NH3) are introduced into the PECVD vacuum reaction chamber for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, the same flow rate of silicon-containing gas silane and ammonia is continued to be introduced into the vacuum reaction chamber, and 3000 sccm of N2 is introduced to ensure pressure stability. The RF power is controlled at 100 W and the deposition time is 75 s to deposit a silicon nitride thin film with a thickness of approximately 300 Å on the surface of the 12-inch wafer.

[0048] 20,000 high-stress silicon nitride films were continuously prepared using this comparative method, and their particle size distribution was examined. The results are as follows: Figure 1 As shown, the particle size (particle size > 0.12 μm) of the high-stress silicon nitride thin film varies greatly under different numbers of coated films, the number of particles is unstable, and it shows a significant upward trend with the increase of the number of coated films.

[0049] Example 1

[0050] This embodiment provides a method for forming a high-stress silicon nitride thin film, the specific steps of which are as follows:

[0051] 1) A PECVD vacuum reaction chamber with Al as the cavity wall material and aluminum nitride (ALN) as the high-temperature resistant base is used. The temperature of the vacuum reaction chamber is controlled at 380 °C and is kept constant in subsequent steps.

[0052] 2) Introduce 4000 sccm of nitrogen fluoride (introduced after dissociation into fluoride ions outside the chamber) and 8000 sccm of argon for 40 s. Under the condition of maintaining the pressure in the PECVD vacuum reaction chamber at 5 torr, remove chamber impurities and form aluminum fluoride on the upper electrode plate of the vacuum reaction chamber.

[0053] 3) After purging the PECVD vacuum reaction chamber with an inert gas, introduce silicon-containing gases silane (SiH4) at 450 sccm, ammonia (NH3) at 150 sccm, and nitrous oxide (N2O) at 4500 sccm for 8 s for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, continue to introduce the same flow rates of silicon-containing gases silane, ammonia, and nitrous oxide into the vacuum reaction chamber to ensure pressure stability. Control the radio frequency power at 1200–1400 W and the deposition time at 17 s to deposit a silicon oxide film with a thickness of approximately 1000 Å on the surface of the vacuum reaction chamber.

[0054] 4) After purging the vacuum reaction chamber of PECVD with inert gas, introduce N2O 7000 sccm to ensure the pressure is stable at 6 torr, control the RF power to 800 W and the deposition time to 12 s, in order to remove unreacted SI-H bonds on the surface of the chamber and protect the substrate.

[0055] 5) Then, a 12-inch wafer is placed on the base of the vacuum reaction chamber. 50 sccm of silicon-containing gas silane (SiH4) and 100 sccm of ammonia (NH3) are introduced into the PECVD vacuum reaction chamber for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, the same flow rate of silicon-containing gas silane and ammonia is continued to be introduced into the vacuum reaction chamber, and 3000 sccm of N2 is introduced to ensure pressure stability. The RF power is controlled at 100 W and the deposition time is 75 s to deposit a silicon nitride film with a thickness of approximately 300 Å on the surface of the 12-inch wafer.

[0056] Using the method of this embodiment, silicon oxide films were deposited on the surface of the vacuum reaction chamber at radio frequency power controlled at 1200, 1300, and 1400 W in step 3), respectively, and the stresses of silicon oxide films 1-1, 1-2, and 1-3 are shown in Table 1. Following subsequent steps, silicon nitride films were deposited on the surface of a 12-inch wafer, with 20,000 films deposited consecutively. The particle size (particle size > 0.12 μm) of the silicon nitride films prepared under different numbers of wafers, with different silicon oxide films 1-1, 1-2, and 1-3 protecting the chamber, are shown in Table 2. Figure 2 As shown.

[0057] Example 2

[0058] This embodiment provides a method for forming a high-stress silicon nitride thin film, the specific steps of which are as follows:

[0059] 1) A PECVD vacuum reaction chamber with Al as the cavity wall material and aluminum nitride (ALN) as the high-temperature resistant base is used. The temperature of the vacuum reaction chamber is controlled at 380 °C and is kept constant in subsequent steps.

[0060] 2) Introduce 4000 sccm of nitrogen fluoride (introduced after dissociation into fluoride ions outside the chamber) and 8000 sccm of argon for 40 s. Under the condition of maintaining the pressure in the PECVD vacuum reaction chamber at 5 torr, remove chamber impurities and form aluminum fluoride on the upper electrode plate of the vacuum reaction chamber.

[0061] 3) After purging the PECVD vacuum reaction chamber with an inert gas, introduce silicon-containing gases silane (SiH4) at 450 sccm, ammonia (NH3) at 150 sccm, and nitrous oxide (N2O) at 4500 sccm for 8 s for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, continue to introduce the same flow rates of silicon-containing gases silane, ammonia, and nitrous oxide into the vacuum reaction chamber to ensure pressure stability. Control the radio frequency power at 1200–1400 W and the deposition time at 21 s to deposit a silicon oxide film with a thickness of approximately 1400 Å on the surface of the vacuum reaction chamber.

[0062] 4) After purging the vacuum reaction chamber of PECVD with inert gas, introduce N2O 7000 sccm to ensure the pressure is stable at 6 torr, control the RF power to 800 W and the deposition time to 12 s, in order to remove unreacted SI-H bonds on the surface of the chamber and protect the substrate.

[0063] 5) Then, a 12-inch wafer is placed on the base of the vacuum reaction chamber. 50 sccm of silicon-containing gas silane (SiH4) and 100 sccm of ammonia (NH3) are introduced into the PECVD vacuum reaction chamber for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, the same flow rate of silicon-containing gas silane and ammonia is continued to be introduced into the vacuum reaction chamber, and 3000 sccm of N2 is introduced to ensure pressure stability. The RF power is controlled at 100 W and the deposition time is 75 s to deposit a silicon nitride film with a thickness of approximately 300 Å on the surface of the 12-inch wafer.

[0064] Using this method, silicon oxide films were deposited on the surface of the vacuum reaction chamber at radio frequency power controlled at 1200, 1300, and 1400 W in step 3), respectively. The stresses of the silicon oxide films 2-1, 2-2, and 2-3 are shown in Table 1. Following subsequent steps, silicon nitride films were deposited on a 12-inch wafer surface, with 20,000 films deposited consecutively. The particle size (particle size > 0.12 μm) of the silicon nitride films prepared under different numbers of wafers, with different silicon oxide films 2-1, 2-2, and 2-3 protecting the chamber, are shown in Table 2. Figure 3 As shown.

[0065] Example 3

[0066] This embodiment provides a method for forming a high-stress silicon nitride thin film, the specific steps of which are as follows:

[0067] 1) A PECVD vacuum reaction chamber with Al as the cavity wall material and aluminum nitride (ALN) as the high-temperature resistant base is used. The temperature of the vacuum reaction chamber is controlled at 380 °C and is kept constant in subsequent steps.

[0068] 2) Introduce 4000 sccm of nitrogen fluoride (introduced after dissociation into fluoride ions outside the chamber) and 8000 sccm of argon for 40 s. Under the condition of maintaining the pressure in the PECVD vacuum reaction chamber at 5 torr, remove chamber impurities and form aluminum fluoride on the upper electrode plate of the vacuum reaction chamber.

[0069] 3) After purging the PECVD vacuum reaction chamber with an inert gas, introduce silicon-containing gases silane (SiH4) at 450 sccm, ammonia (NH3) at 150 sccm, and nitrous oxide (N2O) at 4500 sccm for 8 s for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, continue to introduce the same flow rates of silicon-containing gases silane, ammonia, and nitrous oxide into the vacuum reaction chamber to ensure pressure stability. Control the radio frequency power at 1200–1400 W and the deposition time at 25 s to deposit a silicon oxide film with a thickness of approximately 1800 Å on the surface of the vacuum reaction chamber.

[0070] 4) After purging the vacuum reaction chamber of PECVD with inert gas, introduce N2O 7000 sccm to ensure the pressure is stable at 6 torr, control the RF power to 800 W and the deposition time to 12 s, in order to remove unreacted SI-H bonds on the surface of the chamber and protect the substrate.

[0071] 5) Then, a 12-inch wafer is placed on the base of the vacuum reaction chamber. 50 sccm of silicon-containing gas silane (SiH4) and 100 sccm of ammonia (NH3) are introduced into the PECVD vacuum reaction chamber for pretreatment. Then, while maintaining the pressure in the PECVD vacuum chamber at 5 torr, the same flow rate of silicon-containing gas silane and ammonia is continued to be introduced into the vacuum reaction chamber, and 3000 sccm of N2 is introduced to ensure pressure stability. The RF power is controlled at 100 W and the deposition time is 75 s to deposit a silicon nitride film with a thickness of approximately 300 Å on the surface of the 12-inch wafer.

[0072] Using this method, silicon oxide films were deposited on the surface of the vacuum reaction chamber at radio frequency power controlled at 1200, 1300, and 1400 W in step 3), respectively. The stresses of the silicon oxide films 3-1, 3-2, and 3-3 are shown in Table 1. Following subsequent steps, silicon nitride films were deposited on the surface of a 12-inch wafer. 20,000 wafers were continuously deposited. The SiO2 particle size (particle size > 0.12 μm) of the silicon nitride films prepared under different numbers of wafers, with different silicon oxide films 3-1, 3-2, and 3-3 protecting the chamber, are shown in Table 2. Figure 4 As shown.

[0073] Table 1

[0074]

[0075] Table 2

[0076]

[0077] From Table 2 above and Figure 2-4 The results (with the number of coated wafers as the x-axis and the number of particles as the y-axis) show that the stress of the silicon oxide film has a significant impact on the number of SiO2 particles in the prepared high-stress silicon nitride film. Silicon nitride films with a small and stable number of particles can be obtained when the stress of the silicon oxide film is between -50 and -75 MPa, and the number of particles does not increase significantly with the increase of the number of coated wafers. In particular, when the stress of the silicon oxide film is -50 MPa, the number of particles in the prepared silicon nitride film shows almost no increase at 1000, 5000, 10000, and 20000 wafers, and the number of particles is below 10, demonstrating a very significant effect. Furthermore, the thickness of the silicon oxide film also has a certain impact on the number of SiO2 particles in the prepared high-stress silicon nitride film; when the thickness of the silicon oxide film is 1000-1400 Å, the number of particles is even lower.

[0078] Finally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0079] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0080] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method of forming a high-stress silicon nitride film, comprising: The method comprises the following steps: S1, controlling the temperature of the vacuum reaction chamber of the PECVD equipment to be 350-400 DEG C, then removing the cavity impurities, and fluorinating the upper pole plate of the vacuum reaction chamber to form aluminum fluoride; S2, after purging the vacuum reaction chamber with inert gas, pre-treating by introducing silane, ammonia and laughing gas; then continuously introducing silane, ammonia and laughing gas into the vacuum reaction chamber, and controlling the radio frequency power to be 1200-1300 W to deposit a silicon oxide film on the surface of the cavity for protecting the cavity; S3, after purging the vacuum reaction chamber with inert gas, introducing laughing gas, and controlling the radio frequency power to be 500-1000 W for a certain time; S4, placing the substrate on the susceptor in the vacuum reaction chamber, pre-treating by introducing silane and ammonia into the vacuum reaction chamber; then continuously introducing silane and ammonia into the vacuum reaction chamber, and introducing N2 to deposit a high-stress silicon nitride film on the surface of the substrate; In step S2, the specific pre-treatment steps are as follows: introducing silane 400-500 sccm, ammonia 130-170 sccm and laughing gas 4000-5000 sccm into the vacuum reaction chamber, and the introduction time is 5-10 s; In step S2, in the step of depositing a silicon oxide film on the surface of the cavity for protecting the cavity, the pressure in the vacuum reaction chamber is kept at 1-10 torr, the flow rates of the introduced silane, ammonia and laughing gas are the same as those in the pre-treatment, the deposition time is 17-29 s, the thickness of the deposited silicon oxide film is 1000-2000 Å, and the stress is -50 to -75 Mpa.

2. The method of forming a high-stress silicon nitride film according to claim 1, wherein In the step of depositing a silicon oxide film on the surface of the cavity for protecting the cavity, the deposition time is controlled to be 17-21 s, and the thickness of the deposited silicon oxide film is 1000-1400 Å.

3. The method of forming a high-stress silicon nitride film of claim 1, wherein The introduced amount ratio of the silane and ammonia is 3:

1.

4. The method of forming a high-stress silicon nitride film of claim 1, wherein In step S3, the flow rate of the introduced laughing gas is 5000-10000 sccm, and the pressure is kept at 2-10 torr.

5. The method for forming a high-stress silicon nitride film according to claim 1 or 4, wherein In step S3, the certain time is 10-15 s.

6. The method of forming a high-stress silicon nitride film of claim 1, wherein In step S1, the specific steps of removing the cavity impurities and fluorinating the upper pole plate of the vacuum reaction chamber to form aluminum fluoride are as follows: introducing nitrogen fluoride 2000-6000 sccm and argon 4000-12000 sccm dissociated into fluoride ions outside the chamber, and the introduction time is 30-60 s, and the pressure in the vacuum reaction chamber is kept at 1-10 torr.

7. The method of forming a high-stress silicon nitride film of claim 1, wherein In step S4, the specific pre-treatment steps are as follows: introducing silane 30-80 sccm and ammonia 60-160 sccm into the vacuum reaction chamber, and the introduction time is 5-10 s.

8. The method of forming a high-stress silicon nitride film according to claim 1 or 7, wherein In step S4, the pressure in the vacuum reaction chamber is kept at 1-10 torr, the flow rate of the silicon-containing gas silane is 30-80 sccm, the flow rate of ammonia is 60-160 sccm, the flow rate of N2 is 2000-4000 sccm, the radio frequency power is controlled at 50-150 W, the deposition time is 50-100 s, and the thickness of the deposited silicon nitride film is 100-500 Å.

9. The method of forming a high-stress silicon nitride film of claim 8, wherein, The flow rate ratio of the silicon-containing gas silane to ammonia is 1:

2.

10. A high-stress silicon nitride film prepared by the method of any one of claims 1-9.

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