CN116043190A

CN116043190A - Silicon dioxide film, pre-deposition method thereof and semiconductor structure

Info

Publication number: CN116043190A
Application number: CN202211364242.XA
Authority: CN
Inventors: 邱立峰
Original assignee: Changxin Memory Technologies Inc
Current assignee: Changxin Memory Technologies Inc
Priority date: 2022-11-02
Filing date: 2022-11-02
Publication date: 2023-05-02

Abstract

The embodiment of the application provides a silicon dioxide film, a pre-deposition method thereof and a semiconductor structure, wherein the method comprises the following steps: a precursor is supplied into a chamber, and the silicon dioxide film is pre-deposited in the chamber at a deposition rate of 0.2nm/s to 5nm/s using a first chemical vapor deposition process.

Description

Silicon dioxide film, pre-deposition method thereof and semiconductor structure

Technical Field

The present application relates to the field of semiconductor technology, and relates to, but is not limited to, a silicon dioxide film, a pre-deposition method thereof, and a semiconductor structure.

Background

Chemical vapor deposition cleans the reaction chamber after the deposition of the previous film is completed. After the cleaning is finished, a layer of silicon dioxide film is pre-deposited on the inner wall of the chamber, so that when the film is deposited on the next round, particles which are generated by insufficient nucleation fall on the film on the next round from the inner wall of the chamber, and the defect of the film on the next round is caused; and simultaneously, the concentration of pollutants in the chamber in the cleaning process can be reduced so as to promote the formation of a film in the next round.

In the related art, many particles still fall on the film during the next round of film deposition, resulting in defects in the film.

Disclosure of Invention

In view of the foregoing, embodiments of the present application provide a silicon dioxide film, a pre-deposition method thereof, and a semiconductor structure.

In a first aspect, embodiments herein provide a method of pre-depositing a silicon dioxide film, the method comprising: a precursor is supplied into a chamber, and the silicon dioxide film is pre-deposited within the chamber using a first chemical vapor deposition process at a deposition rate of 0.2 nanometers per second (nm/s) to 5 nm/s.

In some embodiments, further comprising: placing a first substrate into the chamber; depositing the silicon-containing film on the first substrate using a second chemical vapor deposition process.

In some embodiments, the material of the silicon-containing film comprises at least one of: silicon dioxide, silicon oxynitride, silicon nitride and silicon oxycarbide.

In some embodiments, the precursor includes ethyl orthosilicate, oxygen, and helium.

In some embodiments, the first chemical vapor deposition process and the second chemical vapor deposition process each comprise: plasma enhanced chemical vapor deposition, or low pressure chemical vapor deposition.

In some embodiments, where the first chemical vapor deposition process is plasma enhanced chemical vapor deposition, the process parameters of the first chemical vapor deposition process include: the high frequency power ranges from 200 to 500 watts (W), the mass of tetraethyl orthosilicate ranges from 1500 to 2000 milligrams (mg), the flow rate of oxygen ranges from 6000 to 8000 standard milliliters per minute (sccm), and the flow rate of helium ranges from 8000 to 9000sccm.

In some embodiments, the temperature range of the first chemical vapor deposition process is 350 to 550 degrees celsius (°c).

In some embodiments, the first chemical vapor deposition process has a pressure in the range of 3 to 7Torr (Torr).

In some embodiments, prior to supplying the precursor into the chamber, further comprising: after the front layer film is deposited by adopting the previous chemical vapor deposition process, the byproducts generated in the chamber when the front layer film is deposited are removed.

In some embodiments, the by-product comprises silicon dioxide or silicon nitride, and the removing of the by-product generated within the chamber during deposition of the front layer film comprises: generating cleaning material fluoride ions by using a remote plasma system; fluorine ions of the cleaning substance are input into the chamber to remove byproducts generated in the chamber when the front layer film is deposited.

In some embodiments, before the removing of byproducts generated in the chamber during the deposition of the front layer film, further comprising: depositing the front layer film on a second substrate in the chamber by utilizing the front chemical vapor deposition process; and taking the second substrate out of the chamber.

In some embodiments, the material of the front layer film comprises at least one of: silicon dioxide, silicon oxynitride, silicon nitride and silicon oxycarbide.

In some embodiments, the precursor is fed into the chamber through a showerhead.

In a second aspect, embodiments herein provide a silica film prepared according to the method of pre-depositing a silica film described above.

In a third aspect, embodiments of the present application provide a semiconductor structure including a silicon-containing film prepared according to the method of pre-depositing a silicon dioxide film described above.

In the embodiment of the application, since the deposition rate of the first chemical vapor deposition process is 0.2nm/s to 5nm/s, the deposition rate is lower, so that the void in the silicon dioxide film obtained by the first chemical vapor deposition process is smaller, more compact and more stressed. Therefore, under the condition that other silicon-containing films are deposited after the silicon dioxide film is deposited, on one hand, the silicon dioxide film is denser, has higher etching resistance and can resist the environmental damage of the deposited silicon-containing film, so that some particles in the silicon dioxide film can be prevented from falling on the surface of the silicon-containing film, and film defects are prevented from being generated; on the other hand, because the stress of the silicon dioxide film is larger, the silicon dioxide film has better adhesiveness to particles which are insufficiently nucleated in the deposition process of the silicon-containing film, so that the particles which are insufficiently nucleated are not easy to fall on the surface of the silicon-containing film, and the occurrence of film defects is reduced.

Drawings

FIG. 1A is a schematic flow chart of a method for pre-depositing a silicon dioxide film according to an embodiment of the present application;

FIG. 1B is a graph showing the relationship between the deposition rate of a silicon dioxide film and the high frequency power, the mass of tetraethyl orthosilicate, the oxygen flow rate and the helium flow rate according to the embodiment of the present application;

FIG. 1C is a graph showing the relationship between the deposition rate of another silicon dioxide film and the high frequency power, the mass of tetraethyl orthosilicate, the oxygen flow rate and the helium flow rate according to the embodiments of the present application;

FIG. 1D is a schematic diagram showing the differences between a solution in the related art and a solution in an embodiment of the present application;

FIG. 1E is a box plot of performance parameters of a related art solution provided by an embodiment of the present application and a silica film obtained by the solution of the embodiment of the present application;

fig. 1F is a schematic structural diagram of a related art solution provided in an embodiment of the present application and a silica film obtained by the solution in the embodiment of the present application;

FIG. 2A is a schematic diagram of a remote plasma system and chamber connection provided in an embodiment of the present application;

FIG. 2B is a schematic diagram of a structure of a front layer deposited on a second substrate in a chamber by a front chemical vapor deposition process according to an embodiment of the present disclosure;

FIG. 2C is a schematic diagram of a structure obtained after removing by-products generated in the chamber during deposition of the pre-layer film according to the embodiment of the present application;

FIG. 2D is a schematic diagram of a structure of a pre-deposited silicon dioxide film in a chamber according to an embodiment of the present disclosure;

FIG. 3 is a schematic flow chart of another method for pre-depositing a silicon dioxide film according to an embodiment of the present application.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application may be practiced without one or more of these details. In other instances, well-known features have not been described in detail so as not to obscure the application; that is, not all features of an actual implementation are described in detail herein, and well-known functions and constructions are not described in detail.

In the drawings, the size of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like numbers refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on" … …, "" adjacent to "… …," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" … …, "" directly adjacent to "… …," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application. When a second element, component, region, layer or section is discussed, it does not necessarily mean that the first element, component, region, layer or section is present in the present application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

Semiconductor devices, such as dynamic random access memory (Dynamic Random Access Memory, DRAM), typically include multiple layers of films, such as conductive layer films, insulating layer films, etc., in the structure, and most of these films can be prepared by chemical vapor deposition processes. Since semiconductor devices are small and highly accurate, very small defects can affect the performance of the resulting device. Therefore, in the process of manufacturing a semiconductor device, the number of defects in the thin film is reduced. In the chemical vapor deposition process, some particles are generated due to insufficient nucleation and fall on the film in the nucleation process, so that the film is defective.

Based on this, the embodiment of the present application provides a method for pre-depositing a silicon dioxide film, as shown in fig. 1A, the method includes the following step S101:

step S101: a precursor is supplied into the chamber and a silicon dioxide film is pre-deposited within the chamber using a first chemical vapor deposition process at a deposition rate of 0.2nm/s to 5 nm/s.

Here, the chamber refers to a space in which a chemical vapor deposition reaction is performed. In some embodiments, a chamber refers to the interior of a chamber of a chemical vapor deposition apparatus.

Chemical vapor deposition (Chemical Vapor Deposition, CVD) refers to the process of reacting a reactant gas with a substrate surface under process conditions such as temperature and pressure to decompose some components in the reactant gas or to cause a vapor reaction and form a solid film on the substrate surface. Chemical vapor deposition generally involves three processes: generating volatile carrier compounds, carrying the carrier to a deposition area, and generating a solid film layer by chemical vapor reaction. The method for preparing the film by using the chemical vapor deposition method is divided into four stages: critical nuclei are generated, particles grow, compact structures are formed, and continuous films are formed. It is at the stage of critical nuclei formation that insufficient nucleation may occur to produce particles, eventually leading to defects in the film formed.

The precursor refers to a precursor or raw material for forming the silicon dioxide film, i.e. a reactant for forming the silicon dioxide film by using a first chemical vapor deposition process.

In some embodiments, the precursor may include silane (SiH ₄ ) And oxygen and nitrogen, wherein the nitrogen is used to dilute the concentration of silane and oxygen, thereby adjusting the deposition rate of the silicon dioxide film.

The reaction equation is the following equation (1):

SiH ₄ +O ₂ ＝SiO ₂ +2H ₂ (1)；

it can be seen that the silane reacts with oxygen to form silicon dioxide and hydrogen, wherein the silicon dioxide forms a solid film layer on the surface of the substrate, namely a silicon dioxide film. In some embodiments, the chamber further comprises an air outlet through which hydrogen resulting from the reaction of silane and oxygen can be vented.

In some embodiments, the precursor may also include ethyl orthosilicate (Si (OC) ₂ H ₅ ) ₄ TEOS), oxygen, and helium, wherein helium is used to dilute the concentrations of tetraethyl orthosilicate and oxygen, thereby adjusting the deposition rate of the silicon dioxide film.

The reaction equation is the following equation (2) and equation (3):

Si(OC ₂ H ₅ ) ₄ ＝SiO ₂ +4C ₂ H ₄ +2H ₂ O (2)；

Si(OC ₂ H ₅ ) ₄ +12O ₂ ＝SiO ₂ +8C ₂ H ₄ +10H ₂ O (3)；

it can be seen that where the precursor includes tetraethyl orthosilicate, oxygen and helium, the silica film can be obtained by two reactions. The first reaction is the reaction of TEOS and oxygen to form silica, ethylene and water; the second reaction is a decomposition reaction of TEOS, which also produces silica, ethylene and water; wherein, the reaction of TEOS and oxygen and the decomposition reaction of TEOS are carried out simultaneously, and because ethylene and water are both gases, the ethylene and water can be discharged through the gas outlet of the chamber. The embodiment of the application does not limit the types of the precursors.

In the embodiment of the application, in the case that the precursor includes TEOS, oxygen and helium, the following effects are obtained:

in a first aspect, since TEOS is liquid at room temperature, the chemistry is relatively inert; compared with silicon dioxide film deposition by taking silane as a silicon source, the method has the advantages that the deposition temperature is reduced under the same deposition rate condition, and the crystal defects caused by high temperature can be effectively reduced. Thus, it is safer to use.

In the second aspect, the silicon oxide film deposition method has better step coverage capability and gap filling characteristics compared with silicon oxide film deposition using silane as a silicon source. Thus, the resulting silica film can be made more dense.

The deposition rate of the first chemical vapor deposition process is 0.2nm/s to 5nm/s, i.e., a film with a thickness of 0.2 to 5nm is deposited per second. Since the deposition rate in the related art is mostly above 10nm/s, the deposition rate of the first chemical vapor deposition process provided in the embodiments of the present application is a lower deposition rate. In some embodiments, the deposition rate may be changed by changing parameters such as the type, concentration, deposition temperature, and pressure of the precursor, and the method for obtaining the deposition rate of 0.2nm/s to 5nm/s is not limited in the embodiments of the present application. Because the deposition rate of the first chemical vapor deposition process is lower, the silicon dioxide gas obtained by the first chemical vapor deposition process can be deposited on the surface of the substrate more uniformly, so that the silicon dioxide film obtained on the surface of the substrate has smaller gaps, is more compact and has larger stress.

In some embodiments, after deposition of the silicon dioxide film, other silicon-containing films may also be deposited on the substrate within the chamber. Since the deposition process of silicon-containing films is a nucleation, agglomeration and accumulation film formation process, which does not ensure a very uniform and complete combination of the percentage into the desired film, sometimes insufficient nucleation during agglomeration may result in particles similar to the composition of the film. The silicon dioxide film contains abundant oxygen groups with better adhesiveness, so that a layer of silicon dioxide film is deposited in advance before the silicon-containing film is deposited, and particles generated in the process of depositing the next round of film can be adhered by using the silicon dioxide film, so that the occurrence of defects caused by falling of the particles on the silicon-containing film is reduced.

In the embodiment of the application, since the deposition rate of the first chemical vapor deposition process is 0.2nm/s to 5nm/s, the deposition rate is lower, so that the void in the silicon dioxide film obtained by the first chemical vapor deposition process is smaller, more compact and more stressed. Therefore, under the condition that other silicon-containing films are deposited after the silicon dioxide film is deposited, on one hand, the silicon dioxide film is denser, has higher etching resistance and can resist the environment for depositing the silicon-containing film, so that some particles in the silicon dioxide film can be prevented from falling on the surface of the silicon-containing film, and film defects are prevented from being generated; on the other hand, because the stress of the silicon dioxide film is larger, the silicon dioxide film has better adhesiveness to particles which are insufficiently nucleated in the deposition process of the silicon-containing film, so that the particles which are insufficiently nucleated are not easy to fall on the surface of the silicon-containing film, and the occurrence of film defects is reduced.

In some embodiments, the first chemical vapor deposition process may include: plasma enhanced chemical vapor deposition, or low pressure chemical vapor deposition.

In general, the morphology of the presence of a substance is in one-to-one correspondence with a binding energy of a certain order of magnitude. In some embodiments, the morphology in which the substance is present may include solid, liquid, gaseous, and plasma. Wherein, the solid state is the first state of the substance, and when the kinetic energy in the molecule exceeds the binding energy in the crystal, the inherent structure of the crystal is destroyed and then converted into the liquid state (namely the second state of the substance); when the molecular kinetic energy in the second state exceeds the van der Waals bonding energy, the liquid state is converted into a gaseous state (i.e., the third state of the substance); when the gas is excited under special conditions with high energy, ionization occurs, so that part of outer electrons in the gas are separated from atomic nuclei, and a mixed aggregate form (namely, a fourth state of a substance) consisting of electrons, positive ions and neutral particles is changed into a plasma.

Here, plasma enhanced chemical vapor deposition (Plasma Enhanced Chemical Vapor Deposition, PECVD) is a technique that uses a plasma activated reactive gas to promote chemical reactions in the substrate surface or near-surface space to produce a solid film. The basic principle of the plasma enhanced chemical vapor deposition technology is that under the action of a high-frequency or direct-current electric field, source gas is ionized to form plasma, low-temperature plasma is used as an energy source, a proper amount of reaction gas is introduced, and plasma discharge is used to activate the reaction gas and realize the chemical vapor deposition technology.

In some embodiments, when preparing a thin film material using plasma enhanced chemical vapor deposition, the thin film growth process may comprise three processes:

the first process: in the non-equilibrium plasma, electrons in the plasma and the precursor undergo primary reaction, so that the precursor is decomposed to form a mixture of ions and active groups;

the second process: the diffusion and transportation of various active groups to the film growth surface and the inner wall of the chamber, and the secondary reaction between the precursors occur simultaneously;

the third process: the products of the various primary and secondary reactions reaching the growth surface of the substrate are adsorbed and react with the substrate surface with the simultaneous re-release of the vapor phase molecules, thereby forming a thin film on the substrate surface.

The difference between the plasma enhanced chemical vapor deposition and the traditional chemical vapor deposition method is that: the plasma contains a large number of high energy electrons which can provide the activation energy required in the chemical vapor deposition process, thereby changing the energy supply mode of the reaction system. Since the electron temperature in the plasma is up to 10000 Kelvin (K), the collision of electrons and gas phase molecules can promote the chemical bond breakage and recombination of precursor molecules to generate chemical groups with higher activity, and the whole reaction system keeps lower temperature. The characteristic enables the chemical vapor deposition process which is originally required to be carried out at high temperature to be carried out at low temperature, thereby improving the safety of the reaction.

The low pressure chemical vapor deposition (Low Pressure Chemical Vapor Deposition, LPCVD) is a chemical vapor deposition reaction in which the operating pressure of the precursor in the chamber is reduced to less than about 133 pascal (Pa). The film formed by adopting the low-pressure chemical vapor deposition method has the following effects:

first aspect: the low-pressure high-heat environment of the low-pressure chemical vapor deposition method improves the diffusion coefficient and the average free path of the gas in the chamber, and greatly improves the uniformity of the film, the uniformity of the resistivity and the covering and filling capacity of the groove.

Second aspect: the gas substance transmission rate is faster under the low-pressure environment, impurities and reaction byproducts diffused out of the substrate can be quickly brought out of the reaction zone through the boundary layer, and the precursor can quickly reach the surface of the substrate through the boundary layer to react, so that the production efficiency can be improved while the self-doping is effectively inhibited.

Third aspect: the low pressure chemical vapor deposition method does not require a carrier gas, and thus, can greatly reduce the pollution source.

In summary, the plasma enhanced chemical vapor deposition and the low pressure chemical vapor deposition method are widely used in the semiconductor field with high precision requirements due to their superior effects.

In some embodiments, where the first chemical vapor deposition process is plasma enhanced chemical vapor deposition, the process parameters for forming the silicon dioxide film at a deposition rate of 0.2nm/s to 5nm/s may include: the high frequency power ranges from 200 to 500W, the mass of the tetraethyl orthosilicate ranges from 1500 to 2000mg, the flow rate of oxygen ranges from 6000 to 8000sccm, and the flow rate of helium ranges from 8000 to 9000sccm. For example: the high-frequency power was 300W, the mass of tetraethyl orthosilicate was 1800mg, the flow rate of oxygen was 7000sccm, and the flow rate of helium was 8500sccm.

Fig. 1B shows the relationship between the deposition rate of the silicon oxide film and the high frequency power, the mass of the tetraethyl orthosilicate, the flow rate of oxygen gas, and the flow rate of helium gas, and it can be seen that the high frequency power and the mass of the tetraethyl orthosilicate are both in direct proportion to the deposition rate of the silicon oxide film, i.e., the larger the mass of the high frequency power or the tetraethyl orthosilicate, the larger the deposition rate of the silicon oxide film. Wherein, the influence of the mass of the tetraethyl orthosilicate on the deposition rate of the silicon dioxide film is larger, namely, the slight change of the mass of the tetraethyl orthosilicate can cause larger change of the deposition rate of the silicon dioxide film.

The flow rate of oxygen and the flow rate of helium are inversely proportional to the deposition rate of the silicon dioxide film, i.e. the larger the flow rate of oxygen or the flow rate of helium is, the smaller the deposition rate of the silicon dioxide film is. Wherein the influence of the oxygen flow and the helium flow on the deposition rate of the silicon dioxide film is similar or the same.

To further explain the deposition rate of the silicon dioxide film and the high frequency power, tetraethyl orthosilicateThe relation among the mass, the oxygen gas flow and the helium gas flow is determined by singly changing the high-frequency power, the tetraethyl orthosilicate mass, the oxygen gas flow or the helium gas flow through a controlled variable method, so that the relation among the deposition rate of the silicon dioxide film, the high-frequency power, the tetraethyl orthosilicate mass, the oxygen gas flow and the helium gas flow is obtained. FIG. 1C shows the Thickness (THK) of a silicon dioxide film and the high frequency power (HF), the mass of Tetraethylorthosilicate (TEOS), the flow rate of oxygen (O) ₂ ) And the gas flow (He) of helium. When in implementation, firstly, corresponding points are drawn in a coordinate system according to different high-frequency power, the mass of tetraethoxysilane, the air flow of oxygen or the air flow of helium and the corresponding deposition thickness thereof so as to obtain a scatter diagram; fitting is then performed on the scatter plot according to the locations of the points, resulting in a relationship plot as shown in fig. 1C.

As shown in fig. 1C, the deposition rate of the silicon oxide film is linearly related to the high frequency power, the mass of tetraethyl orthosilicate, the flow rate of oxygen gas and the flow rate of helium gas, and the correlation is high. From the resulting linear equation, it can be seen that the slope of the linear equation where the mass of ethyl orthosilicate is located is greatest, followed by high frequency power, then helium flow, and finally oxygen flow. The magnitude of the slope represents the magnitude of the effect of the variable on the deposition thickness (i.e., deposition rate), and therefore, the effect of the mass of ethyl orthosilicate on the deposition rate is greatest among the high frequency power, the mass of ethyl orthosilicate, the mass of oxygen, and the mass of helium, the high frequency power being low, the mass of helium, and finally the mass of oxygen.

Since ethyl orthosilicate is the main source of silicon dioxide, the mass of ethyl orthosilicate has the greatest effect on deposition rate; whereas the high frequency power affects the speed at which the tetraethyl orthosilicate is ionized into a plasma, and thus, the high frequency power is positively correlated with the deposition rate; helium is used to dilute the concentration of ethyl orthosilicate, so helium is inversely proportional to the deposition rate; since the silicon dioxide film is formed partly from the decomposition reaction of TEOS and partly from the reaction of TEOS and oxygen, the flow rate of oxygen has a small influence on the deposition rate, and the flow rate of oxygen dilutes the concentration of ethyl orthosilicate, so that the flow rate of oxygen is inversely proportional to the deposition rate.

In some embodiments, the temperature of the first chemical vapor deposition process is in the range of 350 to 550 ℃, e.g., 400 ℃.

In some embodiments, the first chemical vapor deposition process has a pressure in the range of 3 to 7Torr, for example, a pressure of 5Torr. Thus, a deposition rate of 0.2nm/s to 5nm/s can be obtained to form a silicon dioxide film with a dense structure and a large stress.

The performance of the formed silicon dioxide film will be further described below by taking the example of forming a silicon dioxide film by a plasma enhanced chemical vapor deposition process.

Fig. 1D shows the differences between the solution in the related art and the silicon dioxide film obtained by the solution in the embodiment of the present application using the plasma enhanced chemical vapor deposition process in three dimensions of stress, deformation and defect number, where the process parameters adopted by the solution in the related art are: the high frequency power ranges from 650 to 850W, the mass of the tetraethyl orthosilicate ranges from 5000 to 7000mg, the flow rate of oxygen ranges from 3000 to 4000sccm, and the flow rate of helium ranges from 4000 to 5000sccm. The technical parameters adopted by the scheme of the embodiment of the application are as follows: the high frequency power ranges from 200 to 500W, the mass of the tetraethyl orthosilicate ranges from 1500 to 2000mg, the flow rate of oxygen ranges from 6000 to 8000sccm, and the flow rate of helium ranges from 8000 to 9000sccm. The three dimensional differences are specified as follows:

stress aspect: the stress of the silicon dioxide film obtained by the scheme in the related art is-380 Pa, and the stress of the silicon dioxide film obtained by the scheme in the embodiment of the application is-160 Pa, namely the stress of the silicon dioxide film obtained by the scheme in the related art is smaller than the stress of the silicon dioxide film obtained by the scheme in the embodiment of the application.

Deformation aspect: the surface convexity of the silica film obtained by the scheme in the related art is higher, while the surface convexity of the silica film obtained by the scheme in the embodiment of the application is lower, that is, the deformation of the silica film obtained by the scheme in the related art is larger than the deformation of the silica film obtained by the scheme in the embodiment of the application.

Defect number: the average value of the defect number in the film corresponding to the next round of deposition obtained by the scheme in the related art is 1, and the average value of the defect number in the film corresponding to the next round of deposition obtained by the scheme in the embodiment of the application is 0, i.e. the silicon dioxide film obtained by the scheme in the embodiment of the application is more beneficial to the reduction of the defect number in the film of the next round of deposition.

Here, the defect number refers to the number of defects generated by dropping particles on the next round of film due to insufficient nucleation of particles generated during deposition of the next round of film due to non-adhesion of the silicon oxide film.

In summary, compared with the related art, the silicon dioxide film obtained by the scheme of the embodiment of the application has larger stress and smaller deformation, and the defect number in the film deposited in the next round is smaller.

Fig. 1E is a box line graph of performance parameters of a silica thin film obtained by the scheme in the related art and the scheme of the embodiment of the present application. The explanation of the defect number and stress can be seen in fig. 1D. The wet etching rate is the etching rate of the deposited silicon dioxide film etched by adopting a wet etching process. It can be seen that under the same etching conditions, the wet etching rate of the silicon dioxide film obtained by the scheme in the related art is 25.17nm/s, while the wet etching rate of the silicon dioxide film obtained by the scheme of the embodiment of the application is 17.23nm/s; namely, under the same etching condition, the wet etching rate of the silicon dioxide film obtained by the scheme in the related technology is larger than that of the silicon dioxide film obtained by the scheme in the embodiment of the application; that is, the silica film obtained by the scheme of the present embodiment is more dense than the silica film obtained by the scheme of the related art.

In order to further illustrate that the silica film obtained by the solution in the embodiment of the present application is denser than the silica film obtained by the solution in the related art, fig. 1F shows the structure of the silica film obtained by the solution in the related art and the solution in the embodiment of the present application, it can be seen that the silica film obtained by the solution in the related art has more voids and a looser structure; the silicon dioxide film obtained by the scheme of the embodiment of the application has fewer gaps and a compact structure. In summary, compared with the related art, the silica film obtained by the scheme of the embodiment of the application has a more compact structure.

In some embodiments, after the silicon dioxide film is deposited in the chamber, the implementation of depositing a silicon-containing film on the substrate in the chamber may include the following steps S102 and S103:

step S102: placing a first substrate into the chamber;

here, the first substrate is a substrate for depositing a silicon-containing film after pre-depositing a silicon oxide film, wherein the first substrate may be a single-layer substrate such as a silicon (Si) substrate, a germanium (Ge) substrate, a silicon germanium (SiGe) substrate, a gallium arsenide substrate, a ceramic substrate, a quartz substrate, or a glass substrate for a display; the first substrate may also be a multi-layer substrate, such as a silicon-on-insulator (Silicon On Insulator, SOI) substrate, or a germanium-on-insulator (Germanium On Insulator, GOI) substrate, etc. Shallow trench isolation (Shallow Trench Isolation, STI) may also be formed in the single or multi-layer substrate, isolating a number of active regions in an array or other distribution type within the substrate. STI may be formed by forming a trench in the substrate and then filling the trench with a layer of isolation material. The material filled in the STI may include silicon nitride or silicon oxide, etc., and the silicon oxide may be formed by thermal oxidation.

Step S103: a silicon-containing film is deposited on the first substrate using a second chemical vapor deposition process.

Here, the second chemical vapor deposition process may also include: plasma enhanced chemical vapor deposition, or low pressure chemical vapor deposition. The type of the second chemical vapor deposition process may be the same as the type of the first chemical vapor deposition process.

The silicon-containing film is a film containing silicon element, and because the pre-deposited silicon dioxide film contains silicon element, under the condition that the film deposited on the first substrate contains silicon element, the silicon-containing film and the pre-deposited silicon dioxide film can be removed by the same cleaning substance such as fluoride ion, so that the process is simplified, and the operation is convenient; in addition, as the silicon-containing film and the silicon dioxide film are cleaned by the same cleaning substance, the elements in the two materials are similar, so that the types of the precursors in the process of forming by utilizing the chemical vapor deposition process are similar, and the influence of the precursors of the silicon dioxide film and byproducts generated in the deposition process on the silicon-containing film deposition process can be reduced. Wherein the ionic reaction equation between the fluoride ion and the silicon-containing film and the pre-deposited silicon dioxide film is the following equation (4):

Si ⁴⁺ +4F ^- ＝SiF ₄ (4)；

it can be seen that the reaction between fluoride ions and silicon ions (silicon ions in the silicon-containing film and silicon ions in the pre-deposited silicon dioxide film) generates a silicon fluoride gas, which can be exhausted through the gas outlet of the chamber, thereby functioning to clean the silicon-containing film and the pre-deposited silicon dioxide film.

In some embodiments, the material of the silicon-containing film may include at least one of: silicon dioxide, silicon oxynitride, silicon nitride and silicon oxycarbide. In some embodiments, the silicon-containing film may be a sacrificial layer, an insulating layer, a dielectric layer, etc. in a semiconductor device, and the functions of the silicon-containing film in the embodiments of the present application are not limited.

In the embodiment of the application, after depositing a silicon dioxide film in a chamber, a first substrate is firstly put into the chamber; a silicon-containing film is then deposited on the first substrate. Since the silicon dioxide film contains abundant oxygen groups with better adhesiveness, the silicon-containing film is deposited after the silicon dioxide film is deposited, and particles generated in the process of depositing the silicon-containing film can be adhered by using the silicon dioxide film, so that the occurrence of defects caused by falling of the particles on the silicon-containing film can be reduced; in addition, the silicon dioxide film is deposited before the silicon-containing film is deposited, and the precursor introduced into the chamber in the process of pre-depositing the silicon dioxide film can be used for reducing the concentration of pollutants in the chamber in the process of the previous cleaning procedure, so that the formation of the subsequent silicon-containing film is facilitated.

In some embodiments, "before supplying the precursor into the chamber" in step S101, the following step S104 may be further included:

step S104: after the front layer film is deposited by adopting the previous chemical vapor deposition process, the byproducts generated in the chamber during the deposition of the front layer film are removed.

Here, the previous chemical vapor deposition process is a chemical vapor deposition process before the first chemical vapor deposition process. In some embodiments, the type of the previous chemical vapor deposition process may be the same as the type of the first chemical vapor deposition process.

In some embodiments, the material of the front film may include at least one of: silicon dioxide, silicon oxynitride, silicon nitride and silicon oxycarbide. In this way, the same cleaning material can be used to remove the pre-deposited silicon dioxide film.

By-product is meant particles similar to the composition of the front layer film due to insufficient nucleation during deposition of the front layer film. In some embodiments, the by-products generated within the chamber during deposition of the front layer film may include silicon dioxide, silicon nitride, and the like. Correspondingly, the implementation of step S104 "the removal of by-products generated in the chamber when depositing the pre-layer film" may include the following steps S1041 and S1042:

step S1041: generating cleaning material fluoride ions by using a remote plasma system;

here, a remote plasma system (Remote Plasma System, RPS) refers to a plasma ionization region that is remote from a plasma processing region (a solid surface that produces deposition, etching, surface modification, etc.) for providing a plasma. Remote plasma systems are relative to direct methods (i.e., plasma ionization region and plasma processing region are one region). That is, the remote plasma system refers to a system that synthesizes plasma outside of a plasma processing region, and then introduces the plasma into the plasma processing region using an air flow, an electric field, a magnetic field, etc. This choice is to obtain better spatial uniformity or more suitable ion, neutral composition ratios and different radical ratios in order to obtain better plasma treatment results.

Fig. 2A is a schematic diagram of the connection between the RPS and the chamber, wherein the chamber 101 may be a chamber (i.e., a plasma processing region) of a chemical vapor deposition apparatus. The implementation of step S1041 may include: firstly, argon (Ar) and nitrogen trifluoride (NF) are input into RPS ₃ ) The gas, then, the argon is energized to dissociate the nitrogen trifluoride gas, thereby generating fluoride ions.

Step S1042: fluorine ions of a cleaning substance are introduced into the chamber to remove by-products generated in the chamber when the front layer film is deposited.

With continued reference to fig. 2A, the fluoride ions may react with and etch away the deposits within the chamber 101 to clean the chamber. Since the by-products include silicon dioxide or silicon nitride, the fluoride ions can react with the silicon dioxide or silicon nitride to generate a silicon fluoride gas, which is discharged from the gas outlet of the chamber, so as to clean the film deposited in the chamber, and other by-products are not generated.

In some embodiments, before the step S104 "purge by-products generated in the chamber when depositing the pre-layer film", the following steps S1051 and S1052 may be further included:

step S1051: depositing a front layer film on a second substrate in the chamber by utilizing a front chemical vapor deposition process;

as shown in fig. 2B, a front layer film 201 is deposited on a second substrate 203 within the chamber 101. In some embodiments, the second substrate 203 is placed on a support 205 within the chamber 101. In some embodiments, a thin film of silicon dioxide 202 is pre-deposited on a support 205 within the chamber 101, and then a second substrate 203 is placed on the support 205 on which the thin film of silicon dioxide 202 is deposited; a front layer film 201 is then deposited on the second substrate 203.

Step S1052: the second substrate is removed from the chamber.

The second substrate on which the front layer film was deposited was taken out for other processes. After the second substrate is removed, the by-products generated in the chamber during the removal of the film of the pre-deposition layer in step S104 are formed into a schematic structure shown in fig. 2C, and at this time, no film is present on the support 205 in the chamber 101, and all the by-products are removed by the cleaning material.

The embodiment of the application also provides a method for pre-depositing a silicon dioxide film, as shown in fig. 3, which includes the following steps S201 to S204:

step S201: depositing a front layer film on a second substrate in the chamber by utilizing a front chemical vapor deposition process;

as shown in fig. 2B, a front layer film 201 is deposited on a second substrate 203 within the chamber 101 using a front-end chemical vapor deposition process.

Step S202: removing the second substrate from the chamber;

step S203: generating cleaning material fluoride ions by using a remote plasma system;

as shown in fig. 2A, cleaning substance fluoride ion (F) is generated using a remote plasma system 102 ^- )。

Step S204: fluorine ions of a cleaning substance are input into the chamber to remove byproducts generated in the chamber when the front layer film is deposited;

as shown in fig. 2A, cleaning material fluoride ion (F ^- ) The chamber 101 is fed to remove by-products generated in the chamber during deposition of the front layer film, resulting in a schematic structure as shown in fig. 2C.

Step S205: supplying a precursor into the chamber, pre-depositing a silicon dioxide film within the chamber using a first chemical vapor deposition process at a deposition rate of 0.2nm/s to 5 nm/s;

as shown in fig. 2D, a precursor is supplied into the chamber 101, and a silicon dioxide film 202 is pre-deposited in the chamber 101 using a first chemical vapor deposition process at a deposition rate of 0.2nm/s to 5 nm/s.

In some embodiments, the precursor may be supplied into the chamber 101 through a showerhead 206 as shown in fig. 2D to form a silicon dioxide film within the chamber 101.

Step S206: placing a first substrate into the chamber;

step S207: a silicon-containing film is deposited on the first substrate using a second chemical vapor deposition process.

The embodiment of the application also provides a silicon dioxide film, which is prepared according to the method for pre-depositing the silicon dioxide film.

The embodiment of the application also provides a semiconductor structure, which comprises the silicon-containing film prepared by the method for pre-depositing the silicon dioxide film.

Features disclosed in several method or structural embodiments provided in the present application may be combined arbitrarily without any conflict to obtain new method embodiments or structural embodiments.

The description of the semiconductor structure embodiments above is similar to that of the method embodiments described above, with similar advantageous effects as the method embodiments. For technical details not disclosed in the embodiments of the semiconductor structure of the present application, please refer to the description of the method embodiments of the present application for understanding.

The foregoing description of the exemplary embodiments of the present application is not intended to limit the scope of the present application, but is intended to cover any modifications, equivalents, and alternatives falling within the spirit and principles of the present application.

Claims

1. A method of pre-depositing a thin film of silicon dioxide comprising:

a precursor is supplied into a chamber, and the silicon dioxide film is pre-deposited in the chamber at a deposition rate of 0.2nm/s to 5nm/s using a first chemical vapor deposition process.

2. The method as recited in claim 1, further comprising:

placing a first substrate into the chamber;

and depositing a silicon-containing film on the first substrate by using a second chemical vapor deposition process.

3. The method of claim 2, wherein the material of the silicon-containing film comprises at least one of: silicon dioxide, silicon oxynitride, silicon nitride and silicon oxycarbide.

4. The method of claim 1 or 2, wherein the precursor comprises ethyl orthosilicate, oxygen, and helium.

5. The method of claim 2, wherein the first chemical vapor deposition process and the second chemical vapor deposition process each comprise:

plasma enhanced chemical vapor deposition, or low pressure chemical vapor deposition.

6. The method of claim 5, wherein, in the case where the first chemical vapor deposition process is plasma enhanced chemical vapor deposition,

the process parameters of the first chemical vapor deposition process include:

the high frequency power ranges from 200 to 500W, the mass of the tetraethyl orthosilicate ranges from 1500 to 2000mg, the flow rate of oxygen ranges from 6000 to 8000sccm, and the flow rate of helium ranges from 8000 to 9000sccm.

7. The method of claim 6, wherein the temperature range of the first chemical vapor deposition process is 350 to 550 ℃.

8. The method of claim 6 or 7, wherein the first chemical vapor deposition process has a gas pressure in the range of 3 to 7Torr.

9. The method of any one of claims 1, 2, 5to 7, further comprising, prior to feeding the precursor into the chamber:

after the front layer film is deposited by adopting the previous chemical vapor deposition process, the byproducts generated in the chamber when the front layer film is deposited are removed.

10. The method of claim 9, wherein the by-products comprise silicon dioxide or silicon nitride, and the purging of by-products generated within the chamber during deposition of the front layer film comprises:

generating cleaning material fluoride ions by using a remote plasma system;

fluorine ions of the cleaning substance are input into the chamber to remove byproducts generated in the chamber when the front layer film is deposited.

11. The method of claim 9, further comprising, prior to said purging byproducts generated within said chamber during deposition of said front layer film:

depositing the front layer film on a second substrate in the chamber by utilizing the front chemical vapor deposition process;

and taking the second substrate out of the chamber.

12. The method of claim 9, wherein the material of the front film comprises at least one of: silicon dioxide, silicon oxynitride, silicon nitride and silicon oxycarbide.

13. The method of any one of claims 1, 2, 5to 7, wherein the precursor is fed into the chamber through a showerhead.

14. A silica film prepared according to the method of any one of claims 1 to 13.

15. A semiconductor structure comprising a silicon-containing film prepared according to the method of any one of claims 2 to 13.