Chemical vapor deposition method

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a chemical vapor deposition method which is used for forming a target film layer and comprises the steps that a base layer is deposited on a substrate at a first deposition speed, the thickness of the base layer is smaller than that of the target film layer, and the first deposition speed is smaller than a preset value; and an extension layer is deposited on the side, away from the substrate, of the base layer at a second deposition speed, the second deposition speed is larger than the first deposition speed, and the target film layer comprises the base layer and the extension layer. The base layer is deposited at the first deposition speed, the base layer provides a film forming interface easier to activate, then the extension layer is rapidly formed on the base layer, the base layer and the extension layer jointly form the target film layer, the thickness uniformity of the target film layer can be guaranteed, and the deposition speed of the target film layer is increased.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and specifically relates to a chemical vapor deposition method. Background Art

[0002] Chemical vapor deposition (CVD) is a process in which reactive gases are introduced into a reaction chamber, and these reactive gases react and / or decompose on the surface of a substrate to produce desired deposits, which are then deposited on the surface of the substrate to form a thin film.

[0003] When using chemical vapor deposition process for thin film deposition, the speed of film deposition is affected by factors such as gas pressure, temperature and reaction gas composition. By adjusting factors such as gas pressure, temperature and reaction gas composition, the deposition speed of the film can be increased or decreased. Increasing the deposition speed of the film can improve production efficiency, while decreasing the deposition speed of the film can improve the thickness uniformity of the film, achieve good step coverage and improve product yield.

[0004] However, the deposition speed of the film layer and the thickness uniformity of the film layer are in an antagonistic relationship. When the deposition speed of the film layer is increased, the thickness uniformity of the film layer is reduced, and when the deposition speed of the film layer is reduced, the thickness uniformity of the film layer is improved. How to take into account the deposition speed of the film layer while ensuring the thickness uniformity of the film layer is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The purpose of the present application is to provide a chemical vapor deposition method to ensure the uniformity of the thickness of the film layer while taking into account the deposition speed of the film layer.

[0006] In order to achieve the above object, the present application provides a chemical vapor deposition method for forming a target film layer, the chemical vapor deposition method comprising:

[0007] Depositing a base layer on a substrate at a first deposition speed, wherein the thickness of the base layer is less than the thickness of the target film layer, and the first deposition speed is less than a preset value;

[0008] On a side of the base layer away from the substrate, an extension layer is deposited at a second deposition rate, wherein the second deposition rate is greater than the first deposition rate, and the target film layer includes the base layer and the extension layer.

[0009] Optionally, the chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, and a first gas and a second gas are introduced into a reaction chamber when forming the base layer and the extension layer, the first gas includes dichlorosilane, and the second gas includes ammonia, and the preset value is 10 angstroms per minute.

[0010] Optionally, the base layer has a thickness greater than 50 angstroms.

[0011] Optionally, a first reaction temperature for depositing the base layer is lower than a second reaction temperature for depositing the extension layer.

[0012] Optionally, the chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, and a first gas and a second gas are introduced into the reaction chamber when forming the base layer and the extension layer, the first gas includes dichlorosilane, and the second gas includes ammonia, and the first reaction temperature and the second reaction temperature are both between 630 degrees Celsius and 780 degrees Celsius.

[0013] Optionally, reaction gas is introduced into the reaction chamber when forming the base layer and the extension layer, and the introduction of the reaction gas is stopped during the period when the reaction temperature in the reaction chamber increases from the first reaction temperature to the second reaction temperature.

[0014] Optionally, a first reaction pressure for depositing the base layer is less than a second reaction pressure for depositing the extension layer.

[0015] Optionally, the chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, and a first gas and a second gas are introduced into the reaction chamber when forming the base layer and the extension layer, the first gas includes dichlorosilane, and the second gas includes ammonia, and the first reaction pressure and the second reaction pressure are both between 10 mTorr and 500 mTorr.

[0016] Optionally, reaction gas is introduced into the reaction chamber when forming the base layer and the extension layer, and the introduction of the reaction gas is stopped during the period when the reaction pressure in the reaction chamber increases from the first reaction pressure to the second reaction pressure.

[0017] Optionally, the material of the target film layer includes silicon nitride, and reaction gas is introduced into the reaction chamber when forming the base layer and the extension layer, the reaction gas includes a first gas and a second gas, the first gas includes dichlorosilane, and the second gas includes ammonia, and the proportion of the first gas in the reaction gas introduced when depositing the base layer is smaller than the proportion of the first gas in the reaction gas introduced when depositing the extension layer.

[0018] Optionally, the chemical vapor deposition method includes low-pressure chemical vapor deposition, and the mass flow ratio of the first gas and the second gas in the reaction gas introduced when depositing the base layer is between 1:3 and 1:10, and the mass flow ratio of the first gas and the second gas in the reaction gas introduced when depositing the extension layer is between 1:3 and 1:10.

[0019] Optionally, when the mass flow rate ratio of the first gas to the second gas in the reaction gas introduced into the reaction chamber changes, the overall mass flow rate of the reaction gas is maintained unchanged.

[0020] Optionally, gas is introduced into the reaction chamber when forming the base layer and the extension layer, and the gas includes a reactive gas and an inactive gas. The proportion of the reactive gas in the gas introduced when depositing the base layer is smaller than the proportion of the inactive gas in the gas introduced when depositing the extension layer.

[0021] Optionally, when the mass flow rate ratio of the reaction gas to the inert gas in the gas introduced into the reaction chamber changes, the overall mass flow rate of the gas introduced into the reaction chamber is maintained unchanged.

[0022] Optionally, the chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, the reaction gas includes a first gas and a second gas, the first gas includes dichlorosilane, the second gas includes ammonia, and the inactive gas includes nitrogen.

[0023] The chemical vapor deposition method disclosed in the present application has the following beneficial effects:

[0024] In the present application, the chemical vapor deposition method includes: depositing a base layer on a substrate at a first deposition rate, the thickness of the base layer is less than the thickness of a target film layer, and the first deposition rate is less than a preset value; depositing an extension layer at a second deposition rate on a side of the base layer away from the substrate, and the second deposition rate is greater than the first deposition rate. The base layer is deposited at the first deposition rate, the base layer provides a film-forming interface that is more easily activated, and then the extension layer is quickly formed on the base layer. The base layer and the extension layer together constitute the target film layer, which can not only ensure the uniformity of the thickness of the target film layer, but also increase the deposition rate of the target film layer.

[0025] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0026] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1It is a schematic diagram of the process of the chemical vapor deposition method in the embodiment of the present application.

[0029] Figure 2 It is a schematic diagram of substrate surface activation and nucleation growth of silicon nitride in an embodiment of the present application.

[0030] Figure 3 It is a schematic diagram of a base layer of silicon nitride formed on a substrate in an embodiment of the present application.

[0031] Figure 4 It is a schematic diagram of the surface activation and nucleation growth of silicon nitride on the base layer in the embodiment of the present application.

[0032] Figure 5 It is a schematic diagram of forming a silicon nitride film layer in an embodiment of the present application.

[0033] Figure 6 It is a schematic diagram of substrate surface activation and nucleation growth of silicon nitride in some technical solutions.

[0034] Figure 7 It is a schematic diagram of forming a silicon nitride film layer in some technical solutions.

[0035] Figure 8 It is a process flow chart of the chemical vapor deposition method in the embodiment of the present application.

[0036] Description of reference numerals:

[0037] 100, substrate; 200, target film layer; 210, base layer; 220, extension layer; 200a, target silicon nitride film layer; 300, functional layer. DETAILED DESCRIPTION

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0039] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0040] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be understood as limiting the present application.

[0041] See also Figures 1 to 5 As shown, in this embodiment, the chemical vapor deposition method is used to form a target film layer 200, and the target film layer 200 may include polysilicon, silicon nitride (Si x N y ), titanium nitride, tungsten or titanium, etc. Chemical vapor deposition methods include:

[0042] S100: depositing a base layer 210 on the substrate 100 at a first deposition speed, the thickness of the base layer 210 is less than the thickness of the target film layer 200, and the first deposition speed is less than a preset value;

[0043] S200 : depositing the extension layer 220 at a second deposition rate on a side of the base layer 210 away from the substrate 100 , wherein the second deposition rate is greater than the first deposition rate, and the target film layer 200 includes the base layer 210 and the extension layer 220 .

[0044] The substrate 100 may be a semiconductor substrate, an insulating substrate or a composite substrate. For example, the semiconductor substrate includes a single crystal Si wafer or a Ge wafer, the insulating substrate includes a sapphire substrate, a flexible substrate or a glass substrate, and the composite substrate includes SOI (Silicon On Insulator). The present invention does not specifically limit the material, shape, etc. of the substrate 100. The target film layer 200 may be directly formed on the substrate 100, but is not limited thereto. The target film layer 200 may also be formed on the functional layer 300 on the substrate 100, depending on the specific situation.

[0045] Taking the deposition of silicon nitride film by chemical vapor deposition as an example, in some technical solutions, the reaction chamber needs to be adjusted to a preset pressure and temperature before the deposition, and then the reaction gas, such as the first gas and the second gas, is introduced. The first gas can be dichlorosilane (SiH2Cl2), and the second gas can be ammonia (NH3). The first gas and the second gas undergo a chemical reaction, and the product is deposited on the surface of the substrate 100 (or the functional layer 300) to form the target silicon nitride film 200a, and the gas byproducts are discharged from the reaction chamber through the exhaust device.

[0046] When the target silicon nitride film layer 200a is deposited, the film-forming interface must be activated first. Only after the activation, the interface will nucleate and grow island-shaped silicon nitride, and the island-shaped silicon nitride will diffuse and connect to form a silicon nitride film layer. Compared with the interface of other functional layers 300, the silicon nitride interface is easier to activate. When the silicon nitride deposition speed is fast, the thickness of the region where the film-forming interface nucleates first will be significantly greater than that of other regions, that is, the thickness uniformity of the film layer is reduced. Figure 6 and Figure 7 As shown. For example, the silicon oxide interface is more difficult to activate than the silicon nitride interface, resulting in a decrease in the thickness uniformity of the silicon nitride film layer deposited on the silicon oxide interface.

[0047] By using the chemical vapor deposition method provided in this embodiment, the target film layer 200 is deposited in two stages, so that the thickness uniformity and deposition rate of the target film layer 200 can be taken into account. In the first stage (S100), the base layer 210 is deposited on the substrate 100 at a first deposition rate, and the first deposition rate is less than a preset value to ensure that the film-forming interface on the substrate 100 is densely nucleated and silicon nitride grows, thereby forming a continuous and uniform thickness base layer 210. In other words, the preset value is the upper limit of the deposition rate to ensure that the base layer 210 with thickness uniformity that meets the requirements can be formed. In the second stage (S200), the extension layer 220 is deposited at a second deposition rate, and the second deposition rate is greater than the first deposition rate. Preferably, the second deposition rate is greater than the preset value. Compared with the interface of other functional layers 300, the base layer 210 material and the extension layer 220 material are the same, and the base layer 210 interface is easier to activate. Even if the second deposition rate is greater than the first deposition rate, or even greater than the preset value, an extension layer 220 with thickness uniformity that meets the requirements can be formed.

[0048] The chemical vapor deposition method in this embodiment includes: depositing a base layer 210 on a substrate 100 at a first deposition rate, the thickness of the base layer 210 is less than the thickness of the target film layer 200, and the first deposition rate is less than a preset value; depositing an extension layer 220 at a second deposition rate on a side of the base layer 210 away from the substrate 100, and the second deposition rate is greater than the first deposition rate. The base layer 210 is deposited at the first deposition rate, and the base layer 210 provides a film-forming interface that is more easily activated, and then the extension layer 220 is quickly formed on the base layer 210. The base layer 210 and the extension layer 220 together constitute the target film layer 200, which can not only ensure the uniformity of the thickness of the target film layer 200, but also improve the deposition rate of the target film layer 200.

[0049] In some embodiments, the chemical vapor deposition method includes low-pressure chemical vapor deposition. The material of the target film layer includes silicon nitride. When forming the base layer 210 and the extension layer 220, a reaction gas is introduced into the reaction chamber. The reaction gas includes a first gas and a second gas. The first gas includes dichlorosilane and the second gas includes ammonia. The material of the target film layer 200 includes silicon nitride, and the preset value is 10 angstroms per minute.

[0050] It should be noted that the material of the target film layer 200 may include silicon nitride, but is not limited to this. The target film layer 200 may also include polysilicon, titanium nitride, tungsten or titanium, etc., depending on the specific situation. When the target film layer 200 is polysilicon, titanium nitride, tungsten or titanium, the preset value increases or decreases accordingly, specifically based on the base layer 210 of polysilicon, titanium nitride, tungsten or titanium material that can be formed continuously and with uniform thickness. When the material of the target film layer is silicon nitride, the first gas may be dichlorosilane, and the second gas may be ammonia, but is not limited to this. The first gas may also be silane (SiH4) or silicon chloride (SiCl4), etc. The preset value increases or decreases accordingly, specifically based on the base layer 210 of silicon nitride material that can be formed continuously and with uniform thickness, depending on the specific situation.

[0051] The material of the target film layer 200 is silicon nitride, and the chemical vapor deposition method includes low-pressure chemical vapor deposition. When the first gas is dichlorosilane and the second gas is ammonia, the preset value is 10 angstroms per minute, and the first deposition rate is less than the preset value, that is, silicon nitride is deposited at a rate of less than 10 angstroms per minute, which can form a continuous base layer 210 of silicon nitride material with thickness uniformity that meets the requirements.

[0052] In some embodiments, silicon nitride is deposited by low pressure chemical vapor deposition method with a preset value of 10 angstroms per minute, and the thickness of the base layer 210 is greater than 50 angstroms.

[0053] Since the base layer 210 is formed by diffusion and connection of island-shaped silicon nitride, when the thickness of the base layer 210 is too thin, it is difficult to form a continuous film of the island-shaped silicon nitride. The thickness of the base layer 210 is greater than 50 angstroms, which can ensure that the formed base layer 210 is a continuous silicon nitride film layer with uniform thickness.

[0054] See also Figure 8 As shown, before the first gas and the second gas are introduced into the reaction chamber, the chemical vapor deposition method also includes the steps of adjusting the pressure and temperature of the reaction chamber and maintaining the pressure and temperature of the reaction chamber stable. After forming the target film layer 200, the chemical vapor deposition method also includes the steps of purging the target film layer 200 and the reaction chamber, and cooling down the temperature.

[0055] When purging the target film layer 200 and the reaction chamber, an inactive gas may be introduced into the reaction chamber. The inactive gas may be nitrogen (N2), but is not limited thereto. The inactive gas may also be other inert gases, depending on the specific situation. When adjusting the pressure of the reaction chamber, an inactive gas may be introduced into the reaction chamber. By introducing an inactive gas to adjust the pressure, on the one hand, an inert environment may be formed in the reaction chamber to protect the substrate 100. On the other hand, the inactive gas may be used to purge the reaction chamber to improve the cleanliness in the reaction chamber. In addition, in the process of forming the target film layer 200, an inactive gas may also be introduced to purge the target film layer 200 and the reaction chamber, adjust the pressure of the reaction chamber, and dilute the reaction gas to adjust the deposition rate. This will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0056] See also Figures 3 to 5 and Figure 8 As shown, the first reaction temperature for depositing the base layer 210 is lower than the second reaction temperature for depositing the extension layer 220 .

[0057] Under the same other conditions, the higher the reaction temperature, the faster the deposition speed of the film layer, and the worse the thickness uniformity of the film layer. Depositing the base layer 210 at a relatively low first reaction temperature is conducive to forming a continuous and uniformly thick base layer 210, and depositing the extension layer 220 at a relatively high second reaction temperature is conducive to increasing the deposition speed of the extension layer 220, thereby increasing the deposition speed of the entire target film layer 200. The target film layer 200 is deposited in two stages, which can not only ensure the thickness uniformity of the target film layer 200, but also increase the deposition speed of the target film layer 200.

[0058] For example, the chemical vapor deposition method includes low pressure chemical vapor deposition. The material of the target film layer includes silicon nitride. When forming the base layer 210 and the extension layer 220, a first gas and a second gas are introduced into the reaction chamber, the first gas includes dichlorosilane, and the second gas includes ammonia. The first reaction temperature and the second reaction temperature are both between 630 degrees Celsius and 780 degrees Celsius.

[0059] If the reaction temperature is too high, it is difficult to ensure the uniformity of the thickness of the target film layer 200 formed, and if the reaction temperature is too low, it is difficult to ensure the deposition rate of the target film layer 200 formed. When the target film layer 200 is a silicon nitride film layer, the first reaction temperature and the second reaction temperature are both between 630 degrees Celsius and 780 degrees Celsius, which can ensure the uniformity of the thickness of the silicon nitride film layer and appropriately increase the deposition rate of the silicon nitride film layer.

[0060] In some embodiments, during the period when the reaction temperature in the reaction chamber increases from the first reaction temperature to the second reaction temperature, the introduction of the first gas and the second gas is stopped.

[0061] During the period when the reaction temperature in the reaction chamber increases from the first reaction temperature to the second reaction temperature, the temperature in the reaction chamber is unstable, and the temperatures in different regions on the substrate 100 may be different. The thickness of the film deposited in the regions with different temperatures on the substrate 100 may be greatly different, affecting the thickness uniformity of the target film layer 200. During the period when the reaction temperature in the reaction chamber increases from the first reaction temperature to the second reaction temperature, the first gas and the second gas are stopped from being introduced, the film deposition is interrupted, and then resumed after the reaction temperature stabilizes, so as to improve the thickness uniformity of the target film layer 200. When the first gas and the second gas are stopped from being introduced to interrupt the film deposition, an inactive gas is continuously introduced into the reaction chamber to maintain a stable pressure in the reaction chamber.

[0062] See also Figures 3 to 5 and Figure 8 As shown, the first reaction pressure for depositing the base layer 210 is less than the second reaction pressure for depositing the extension layer 220 .

[0063] Under the same other conditions, the higher the reaction pressure, the faster the deposition speed of the film layer, and the worse the thickness uniformity of the film layer. Depositing the base layer 210 at a relatively low first reaction pressure is conducive to forming a continuous and uniformly thick base layer 210, and depositing the extension layer 220 at a relatively high second reaction pressure is conducive to increasing the deposition speed of the extension layer 220, thereby increasing the deposition speed of the entire target film layer 200. The target film layer 200 is deposited in two stages, which can not only ensure the thickness uniformity of the target film layer 200, but also increase the deposition speed of the target film layer 200.

[0064] For example, the chemical vapor deposition method includes low-pressure chemical vapor deposition. The material of the target film layer includes silicon nitride. When forming the base layer 210 and the extension layer 220, a first gas and a second gas are introduced into the reaction chamber, the first gas includes dichlorosilane, and the second gas includes ammonia. The first reaction pressure and the second reaction pressure are both between 10 mTorr and 500 mTorr.

[0065] If the reaction pressure is too high, it is difficult to ensure the uniformity of the thickness of the formed target film layer 200, and if the reaction pressure is too low, it is difficult to ensure the deposition rate of the formed target film layer 200. When the target film layer 200 is a silicon nitride film layer, the first reaction pressure and the second reaction pressure are both between 10 mTorr and 500 mTorr, which can ensure the uniformity of the thickness of the silicon nitride film layer and appropriately increase the deposition rate of the silicon nitride film layer.

[0066] In some embodiments, during the period when the reaction pressure in the reaction chamber increases from the first reaction pressure to the second reaction pressure, the introduction of the first gas and the second gas is stopped.

[0067] During the period when the reaction pressure in the reaction chamber increases from the first reaction pressure to the second reaction pressure, the pressure in the reaction chamber is unstable, and the thickness of the film deposited in different areas on the substrate 100 may vary greatly, affecting the thickness uniformity of the target film 200. During the period when the reaction temperature in the reaction chamber increases from the first reaction temperature to the second reaction temperature, the first gas and the second gas are stopped from being introduced, the film deposition is interrupted, and then the reaction pressure is resumed after being stabilized, so as to improve the thickness uniformity of the target film 200. When the first gas and the second gas are stopped from being introduced to interrupt the film deposition, the inactive gas is continuously introduced into the reaction chamber to maintain the pressure in the reaction chamber.

[0068] See also Figures 3 to 5 and Figure 8 As shown, the chemical vapor deposition method includes low-pressure chemical vapor deposition. The material of the target film layer includes silicon nitride. When forming the base layer 210 and the extension layer 220, a first gas and a second gas are introduced into the reaction chamber, the first gas includes dichlorosilane, and the second gas includes ammonia. The proportion of the first gas in the reaction gas introduced when depositing the base layer 210 is less than the proportion of the first gas in the reaction gas introduced when depositing the extension layer 220.

[0069] Under the same other conditions and within a certain range of the mass ratio of the first gas to the second gas, the higher the proportion of dichlorosilane in the reaction gas, the faster the deposition speed of the film layer and the worse the thickness uniformity of the film layer. Depositing the base layer 210 with a reaction gas with a relatively low proportion of dichlorosilane is conducive to forming a continuous and uniformly thick base layer 210, and depositing the extension layer 220 with a reaction gas with a relatively high proportion of dichlorosilane is conducive to increasing the deposition speed of the extension layer 220, thereby increasing the deposition speed of the entire target film layer 200. The target film layer 200 is deposited in two stages, which can not only ensure the thickness uniformity of the target film layer 200, but also increase the deposition speed of the target film layer 200.

[0070] For example, when depositing the base layer 210, the mass flow ratio of the first gas to the second gas in the reaction gas is between 1:3 and 1:10, and when depositing the extension layer 220, the mass flow ratio of the first gas to the second gas in the reaction gas is between 1:3 and 1:10.

[0071] If the proportion of dichlorosilane in the reaction gas is too high, the thickness uniformity of the formed target film layer 200 is difficult to ensure, and if the proportion of dichlorosilane in the reaction gas is too low, the deposition rate of the formed target film layer 200 is difficult to ensure. When the target film layer 200 is a silicon nitride film layer, the mass flow ratio of the first gas to the second gas in the reaction gas is between 1:3 and 1:10, which can ensure the thickness uniformity of the silicon nitride film layer and appropriately increase the deposition rate of the silicon nitride film layer.

[0072] In some embodiments, when the mass flow ratio of the first gas to the second gas in the reaction gas introduced into the reaction chamber changes, the overall mass flow of the reaction gas is maintained unchanged, and the overall mass flow of the reaction gas during the deposition of the base layer and the deposition of the extension layer is unchanged, that is, the sum of the mass flow of the first gas and the mass flow of the second gas is unchanged. For example, the sum of the mass flow of the first gas and the mass flow of the second gas can be controlled between 160 sccm and 800 sccm.

[0073] Maintaining the mass flow rate of the first gas and the mass flow rate of the second gas unchanged can prevent the ratio of the first gas to the second gas in the reaction gas from changing, thereby preventing the gas pressure in the reaction chamber from changing.

[0074] See also Figures 3 to 5 and Figure 8 As shown, gas is introduced into the reaction chamber when forming the base layer 210 and the extension layer 220. The gas includes reactive gas and inactive gas. The proportion of reactive gas in the gas introduced when depositing the base layer is less than the proportion of inactive gas in the gas introduced when depositing the extension layer.

[0075] Under the same other conditions and within a certain range of the mass ratio of the reactive gas to the inactive gas, the higher the proportion of the reactive gas in the gas, the faster the deposition speed of the film layer and the worse the thickness uniformity of the film layer. Depositing the base layer 210 with a gas having a relatively low proportion of reactive gas is conducive to forming a continuous and uniformly thick base layer 210. Since the inactive gas has a dilution effect on the reactive gas, the uniformity of the film layer deposition is improved; depositing the extension layer 220 with a gas having a relatively high proportion of reactive gas is conducive to increasing the deposition speed of the extension layer 220, thereby increasing the deposition speed of the entire target film layer 200. The target film layer 200 is deposited in two stages, which can not only ensure the uniformity of the thickness of the target film layer 200, but also increase the deposition speed of the target film layer 200.

[0076] When the material of the target film layer 200 includes silicon nitride, the reaction gas includes a first gas and a second gas, the first gas includes dichlorosilane, the second gas includes ammonia, the inactive gas includes nitrogen, and the chemical vapor deposition method includes low pressure chemical vapor deposition.

[0077] When the first gas includes dichlorosilane, the second gas includes ammonia, and the inactive gas includes nitrogen, the film deposition rate is limited by the reaction pressure, reaction temperature and gas composition, and the film deposition rate can be easily adjusted by the reaction pressure, reaction temperature and gas composition.

[0078] In some embodiments, when the mass flow ratio of the reaction gas to the inactive gas in the gas introduced into the reaction chamber changes, the overall mass flow of the gas introduced into the reaction chamber is maintained unchanged, that is, the sum of the mass flow of the reaction gas and the mass flow of the inactive gas remains unchanged. For example, the sum of the mass flow of the first gas and the mass flow of the second gas can be controlled between 160 sccm and 800 sccm, and the mass flow of the inactive gas can be controlled between 60 sccm and 120 sccm.

[0079] Maintaining a constant balance between the mass flow rate of the reactive gas and the mass flow rate of the inactive gas can prevent changes in the ratio of the reactive gas to the inactive gas in the gas, which would result in changes in the gas pressure in the reaction chamber.

[0080] It should be understood that the deposition rate of the film layer is affected by factors such as reaction pressure, reaction temperature and gas composition. When the target film layer 200 is deposited in two stages, the deposition rate can be adjusted by one of the reaction pressure, reaction temperature and gas composition, or by any two or all of the reaction pressure, reaction temperature and gas composition, so as to achieve the purpose of ensuring the uniformity of the thickness of the target film layer 200 and improving the deposition rate of the target film layer 200.

[0081] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0082] In this application, unless otherwise clearly specified and limited, the terms "assembly", "connection" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0083] In the description of this specification, the description with reference to the terms "some embodiments", "exemplarily", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0084] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application. Therefore, any changes or modifications made in accordance with the claims and description of the present application should fall within the scope of the patent of this application.

Claims

1. A chemical vapor deposition method for forming a target film layer, characterized in that: include: Depositing a base layer on a substrate at a first deposition speed, wherein the thickness of the base layer is less than the thickness of the target film layer, and the first deposition speed is less than a preset value; On a side of the base layer away from the substrate, an extension layer is deposited at a second deposition rate, wherein the second deposition rate is greater than the first deposition rate, and the target film layer includes the base layer and the extension layer.

2. The chemical vapor deposition method according to claim 1, characterized in that: The chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, and a first gas and a second gas are introduced into the reaction chamber when forming the base layer and the extension layer. The first gas includes dichlorosilane, and the second gas includes ammonia. The preset value is 10 angstroms per minute.

3. The chemical vapor deposition method according to claim 2, characterized in that: The thickness of the base layer is greater than 50 angstroms.

4. The chemical vapor deposition method according to claim 1, characterized in that: A first reaction temperature for depositing the base layer is lower than a second reaction temperature for depositing the extension layer.

5. The chemical vapor deposition method according to claim 4, characterized in that: The chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, and a first gas and a second gas are introduced into the reaction chamber when forming the base layer and the extension layer. The first gas includes dichlorosilane, and the second gas includes ammonia. The first reaction temperature and the second reaction temperature are both between 630 degrees Celsius and 780 degrees Celsius.

6. The chemical vapor deposition method according to claim 4, characterized in that: When forming the base layer and the extension layer, reaction gas is introduced into the reaction chamber, and during the period when the reaction temperature in the reaction chamber increases from the first reaction temperature to the second reaction temperature, the introduction of the reaction gas is stopped.

7. The chemical vapor deposition method according to claim 1, characterized in that: A first reaction pressure for depositing the base layer is less than a second reaction pressure for depositing the extension layer.

8. The chemical vapor deposition method according to claim 7, characterized in that: The chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, and a first gas and a second gas are introduced into a reaction chamber when forming the base layer and the extension layer. The first gas includes dichlorosilane, and the second gas includes ammonia. The first reaction pressure and the second reaction pressure are both between 10 mTorr and 500 mTorr.

9. The chemical vapor deposition method according to claim 7, characterized in that: When forming the base layer and the extension layer, reaction gas is introduced into the reaction chamber, and the introduction of the reaction gas is stopped during the period when the reaction pressure in the reaction chamber increases from the first reaction pressure to the second reaction pressure.

10. The chemical vapor deposition method according to claim 1, characterized in that: The material of the target film layer includes silicon nitride, and reaction gas is introduced into the reaction chamber when forming the base layer and the extension layer. The reaction gas includes a first gas and a second gas, the first gas includes dichlorosilane, and the second gas includes ammonia. The proportion of the first gas in the reaction gas introduced when depositing the base layer is smaller than the proportion of the first gas in the reaction gas introduced when depositing the extension layer.

11. The chemical vapor deposition method according to claim 10, characterized in that: The chemical vapor deposition method includes low-pressure chemical vapor deposition, and the mass flow ratio of the first gas and the second gas in the reaction gas introduced when depositing the base layer is between 1:3 and 1:10, and the mass flow ratio of the first gas and the second gas in the reaction gas introduced when depositing the extension layer is between 1:3 and 1:

10.

12. The chemical vapor deposition method according to claim 10, characterized in that: When the mass flow rate ratio of the first gas to the second gas in the reaction gas introduced into the reaction chamber changes, the overall mass flow rate of the reaction gas is maintained unchanged.

13. The chemical vapor deposition method according to claim 1, characterized in that: When forming the base layer and the extension layer, gas is introduced into the reaction chamber, and the gas includes reaction gas and inactive gas. The proportion of reaction gas in the gas introduced when depositing the base layer is smaller than the proportion of inactive gas in the gas introduced when depositing the extension layer.

14. The chemical vapor deposition method according to claim 13, characterized in that: When the mass flow rate ratio of the reaction gas to the inert gas in the gas introduced into the reaction chamber changes, the overall mass flow rate of the gas introduced into the reaction chamber is maintained unchanged.

15. The chemical vapor deposition method according to claim 13, characterized in that: The chemical vapor deposition method includes low-pressure chemical vapor deposition, the material of the target film layer includes silicon nitride, the reaction gas includes a first gas and a second gas, the first gas includes dichlorosilane, the second gas includes ammonia, and the inactive gas includes nitrogen.

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