Remote plasma-based silicon carbon film deposition using silicon

Abstract

Doped or undoped silicon carbide films may be deposited using remote plasma chemical vapor deposition (CVD) techniques. One or more silicon-containing precursors are provided to the reaction chamber. A free radical species, such as a free radical species of hydrogen, is provided in a substantially low energy state or ground state and interacts with one or more silicon-containing precursors to deposit a silicon carbide film. A carbon-containing precursor may flow with one or more silicon-containing precursors, where the carbon-containing precursor has one or more carbon-carbon double bonds or triple bonds, and each silicon-containing precursor is a silane-based precursor having at least one silicon atom having two or more hydrogen atoms bonded to the silicon atom.

Description

This application is a divisional application of application No. 201980049654.4, filed on July 22, 2019, and entitled “Remote plasma-based silicon carbide film deposition using silicon-containing and carbon-containing precursors.” Incorporated by Reference

[0001] The PCT application form is filed concurrently with this specification as a part of this application. Each application from which this application claims the benefit of priority as identified in the concurrently filed PCT application form is incorporated herein by reference in its entirety and for all purposes. Background Art

[0002] Silicon carbide (SiC) films possess unique physical, chemical, and mechanical properties and are used in a variety of applications, particularly integrated circuits. Types of SiC films include oxygen-doped silicon carbide (also known as silicon oxycarbide), nitrogen-doped silicon carbide (also known as silicon carbonitride), oxygen- and nitrogen-doped silicon carbide (also known as silicon carbonoxynitride), and undoped silicon carbide.

[0003] The background description provided here is for the purpose of generally presenting the context of the present disclosure. No admission is made, either explicitly or implicitly, that the work of the presently designated inventors is prior art to the present disclosure to the extent that it is described in this background section and in aspects of the specification that were not determined to be prior art at the time the application was filed. Summary of the Invention

[0004] A method for depositing a silicon carbide film on a substrate is provided. The method comprises: providing a substrate in a reaction chamber; flowing a silicon-containing precursor into the reaction chamber and toward the substrate; and flowing a co-reactant into the reaction chamber along with the silicon-containing precursor. The silicon-containing precursor has at least two hydrogen atoms bonded to silicon atoms, and the co-reactant is a hydrocarbon molecule. The method further comprises: generating hydrogen radicals from a hydrogen source gas in a remote plasma source, the hydrogen radicals being generated upstream of the silicon-containing precursor and the co-reactant; and introducing the hydrogen radicals into the reaction chamber and toward the substrate, wherein the hydrogen radicals are in a ground state to react with the silicon-containing precursor and the co-reactant to form a doped or undoped silicon carbide film on the substrate.

[0005] In some embodiments, all or substantially all of the hydrogen radicals in the environment adjacent to the substrate are hydrogen radicals in the ground state. In some embodiments, the hydrocarbon molecules have one or more carbon-carbon double or triple bonds. The hydrocarbon molecules comprise propylene, ethylene, butene, pentene, butadiene, pentadiene, hexadiene, heptadiene, toluene, benzene, acetylene, propyne, butyne, pentyne, or hexyne. In some embodiments, the silicon-containing precursor comprises silane, disilane, trisilane, methylsilane, or dimethylsilane. In some embodiments, the doped or undoped silicon carbide film has no or substantially no C-C bonds. In some embodiments, the method further comprises: providing a nitriding agent in the remote plasma source together with the hydrogen source gas, wherein free radicals of the nitriding agent are generated in the remote plasma source; and introducing the free radicals of the nitriding agent together with the free radicals of the hydrogen into the reaction chamber and directed toward the substrate, wherein the free radicals of the nitriding agent and the free radicals of the hydrogen react with the silicon-containing precursor and the co-reactant to form a silicon carbonitride (SiCN) film. The SiCN film has no or substantially no C-C bonds and has no or substantially no C-N bonds. In some embodiments, the method further comprises: providing an oxidizing agent in the remote plasma source together with the hydrogen source gas, wherein free radicals of the oxidizing agent are generated in the remote plasma source; and introducing the free radicals of the oxidizing agent together with the free radicals of the hydrogen into the reaction chamber and directed toward the substrate, wherein the oxidizing agent and the free radicals of the hydrogen react with the silicon-containing precursor and the co-reactant to form a silicon oxycarbide (SiCO) film. The SiCO film has no or substantially no C-C bonds and no or substantially no C-O bonds. In some embodiments, the doped or undoped silicon carbide film has a conformality of at least 75%. In some embodiments, the silicon-containing precursor (i) has no C-O bonds and (ii) has no C-N bonds.

[0006] These and other embodiments are described further below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A Schematic cross-sectional views of exemplary doped or undoped silicon carbide films deposited on a substrate are shown.

[0008] Figure 1B Schematic cross-sectional views of exemplary doped or undoped silicon carbide films conformally deposited on features of a substrate are shown.

[0009] Figure 1CSchematic cross-sectional views of exemplary doped or undoped silicon carbide vertical structures on the sidewalls of a gate electrode of a transistor are shown.

[0010] Figure 1D Schematic cross-sectional views of exemplary doped or undoped silicon carbide vertical structures on exposed sidewalls of copper lines in an airgap-type metallization layer are shown.

[0011] Figure 1E Schematic cross-sectional views of exemplary doped or undoped silicon carbide pore sealants for porous dielectric materials are shown.

[0012] Figure 2 Exemplary chemical structures of representative cage-type siloxane precursors are shown.

[0013] Figure 3 A schematic diagram of an exemplary plasma processing apparatus with a remote plasma source is shown, according to some embodiments.

[0014] Figure 4 A schematic diagram of an exemplary plasma processing apparatus with a remote plasma source is shown according to some other embodiments.

[0015] Figure 5 An example of the chemical reaction between activated alkanes from carbon-containing precursors and activated silane-based precursors is shown.

[0016] Figure 6A Shown are FTIR spectra of remote plasma CVD of silicon carbide films formed using a silicon-containing precursor and varying amounts of a carbon-containing precursor.

[0017] Figure 6B Shows Figure 6A A magnified view of a portion of the FTIR spectrum.

[0018] Figure 7 Shown are TEM images of silicon carbide films deposited on substrate features using silicon-containing precursors and carbon-containing precursors. DETAILED DESCRIPTION

[0019] In this disclosure, the terms "semiconductor wafer," "wafer," "substrate," "wafer substrate," and "partially fabricated integrated circuit" are used interchangeably. It will be understood by those skilled in the art that the term "partially fabricated integrated circuit" can refer to a silicon wafer during any of the many stages of integrated circuit fabrication. Wafers or substrates used in the semiconductor device industry typically have a diameter of 200 mm, 300 mm, or 450 mm. The following detailed description assumes that the present disclosure is implemented on a wafer. However, the present disclosure is not so limited. The workpiece can be of various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that can take advantage of the present disclosure include various items such as printed circuit boards. introduction

[0020] The manufacture of semiconductor devices typically involves depositing one or more thin films on a substrate in an integrated manufacturing process. In some aspects of the manufacturing process, thin film types such as silicon carbide, silicon oxycarbide, silicon carbonitride, and silicon carbon oxynitride are deposited using atomic layer deposition (ALD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), or any other suitable deposition method. As used herein, the term "silicon carbide" includes undoped or doped silicon carbides, such as oxygen-doped silicon carbide (SiCO), nitrogen-doped silicon carbide (SiCN), and nitrogen and oxygen-doped silicon carbide (SiOCN). For the most part, doped silicon carbide has up to about 50% atomic dopant atoms, whether these atoms are atoms of oxygen, nitrogen, or other elements. The doping level provides the desired film properties.

[0021] Precursor molecules for depositing silicon carbide may include silicon-containing molecules having silicon-hydrogen (Si-H) bonds and / or silicon-silicon (Si-Si) bonds, and silicon-carbon (Si-C) bonds. Precursor molecules for depositing silicon oxycarbide include silicon-containing molecules having silicon-hydrogen (Si-H) bonds and / or silicon-silicon (Si-Si) bonds, as well as silicon-oxygen (Si-O) bonds, and / or silicon-carbon (Si-C) bonds. Precursor molecules for depositing silicon carbonitride include silicon-containing molecules having silicon-hydrogen (Si-H) bonds and / or silicon-silicon (Si-Si) bonds, as well as silicon-nitrogen (Si-N) bonds, and / or silicon-carbon (Si-C) bonds. Precursor molecules for depositing silicon oxycarbonitride include silicon-containing molecules having silicon-hydrogen (Si-H) bonds, and / or silicon-silicon (Si-Si) bonds, as well as silicon-nitrogen (Si-N) bonds, silicon-oxygen (Si-O) bonds, and / or silicon-carbon (Si-C) bonds. Current PECVD processes may use in-situ plasma treatment, in which plasma is provided directly in the vicinity of the substrate.

[0022] It has been found that depositing high quality silicon carbide films can present several challenges, such as providing films with good step coverage, low dielectric constant, high breakdown voltage, low leakage current, high porosity, and / or coverage over exposed metal surfaces without oxidizing the metal surfaces.

[0023] While the present invention is not limited to any particular theory, it is believed that the plasma conditions in a typical PECVD process fragment the silicon-containing precursor molecules in a manner that produces adverse effects. For example, PECVD can break Si-O bonds and / or Si-C bonds in the precursor molecules to produce highly reactive free radicals or other fragment types with high sticking coefficients. The resulting fragments of the doped silicon carbide film can include silicon, carbon, and / or oxygen atoms with "dangling" bonds, meaning that the silicon, carbon, and / or oxygen atoms have active, unpaired valence electrons. The high sticking coefficients of the precursor molecules and their fragments can deposit silicon carbide films with poor step coverage because the reactive precursor fragments can disproportionately adhere to the upper regions of the sidewalls of recessed features and other structures.

[0024] Dangling bonds can generate silanol groups (Si-OH) in the deposited silicon oxycarbide or silicon oxycarbonitride films. Dangling bonds can also generate silanolamine groups (Si-NH2) in the deposited silicon carbonitride films. Due to these functional groups, the films may have an undesirably high dielectric constant. Film quality may also be affected because direct plasma conditions tend to extract carbon from the deposited films.

[0025] Furthermore, dangling bonds can lead to an increase in silicon-hydrogen (Si-H) bonds in the deposited silicon carbide film. Destroyed Si-C bonds can be replaced with Si-H bonds under direct plasma deposition conditions. The presence of Si-H bonds in the silicon carbide film can result in a film with poor electrical properties. For example, the presence of Si-H bonds can reduce the breakdown voltage and increase leakage current because the Si-H bonds provide a leakage path for electrons.

[0026] Additionally, dangling bonds can lead to uncontrolled chemical or morphological structures in the silicon carbide film. In some cases, such structures are dense filaments with low or no porosity, resulting in films with unacceptably high dielectric constants. The lack of porosity can be a result of direct plasma conditions breaking Si-C and / or Si-O bonds in the cyclosiloxanes that would otherwise provide porosity in the ultra-low-k dielectric material.

[0027] Sometimes the use of direct plasma conditions in PECVD can lead to directionality in deposition because the energy to break down the precursor molecules can be low frequency, resulting in a large number of ion bombardments at the surface. Directed deposition can also lead to the deposition of silicon carbide films with poor step coverage. A direct plasma is one in which the plasma (a moderate concentration of electrons and positive ions) resides close to the substrate surface during deposition, sometimes separated from the substrate surface only by a plasma sheath.

[0028] Typical PECVD processes are sometimes unsuitable for depositing silicon carbide films on exposed copper or other metal surfaces because the process can oxidize the metal. Oxidants such as oxygen (O2), ozone (O3), carbon dioxide (CO2), or other oxidizing species can be used in PECVD processes to form silicon oxycarbide films. Substrate surface environment during deposition

[0029] Figure 1A A cross-section of an exemplary silicon carbide film deposited on a substrate is shown. The silicon carbide film 101 can be formed under process conditions that create a relatively mild environment adjacent to the substrate 100. The substrate 100 can be any wafer, semiconductor wafer, partially manufactured integrated circuit, printed circuit board, display screen, or other suitable workpiece. The process for depositing the silicon carbide film 101 can include one or more silicon-containing precursors having one or more Si-H bonds and / or one or more Si-Si bonds. Optionally, the one or more silicon-containing precursors can include other bonds (e.g., Si-C bonds, Si-O bonds, and / or Si-N bonds), depending on the type of doped structure to be generated.

[0030] Some applications using silicon carbide membranes are Figures 1B-1E . In some embodiments, the silicon-containing precursor may include a silicon-oxygen precursor, a silicon-nitrogen precursor, and / or a silicon-carbon precursor. The silicon-oxygen precursor may include one or more Si-O bonds, the silicon-nitrogen precursor may include one or more Si-N bonds, and the silicon-carbon precursor may include one or more Si-C bonds. In some embodiments, for example, the silicon-containing precursor may include a single reactant A having a Si-O bond and a Si-C bond or a Si-N bond and a Si-C bond. In some embodiments, the silicon-containing precursor may include a reactant B having a Si-O bond or a Si-N bond, and a reactant C having a Si-C bond. It should be understood that any number of suitable reactants may be used within the scope of the present invention. The chemical structures of exemplary silicon-containing precursors will be discussed in further detail below.

[0031] The silicon-containing precursor contains one or more Si-H bonds and / or one or more Si-Si bonds. However, it should be understood that the additional silicon-containing precursors do not necessarily need to contain Si-H or Si-Si bonds. These additional silicon-containing precursors can be provided simultaneously with the silicon-containing precursor having one or more Si-H and / or Si-Si bonds. During the deposition process, the Si-H bonds and / or Si-Si bonds are broken and serve as active sites for forming bonds between the silicon-containing precursor or other precursors in the deposited silicon carbide film 101. The broken bonds can also serve as sites for crosslinking in heat treatments performed during or after deposition. Bonding and crosslinking at the active sites can together form the primary backbone or matrix in the resulting silicon carbide film 101.

[0032] In some embodiments, the process conditions can maintain or substantially maintain the Si-C bonds, as well as the Si-O and Si-N bonds, if present, in the deposited silicon carbide film 101 layer. Thus, the reaction conditions adjacent to the substrate 100 provide for selectively destroying Si-H and / or Si-Si bonds, for example, extracting hydrogen from the destroyed Si-H bonds, but the reaction conditions do not provide for extracting oxygen from Si-O bonds, nitrogen from Si-N bonds, or carbon from Si-C bonds. However, the introduction of a co-reactant such as oxygen can extract carbon from Si-C bonds. It should be understood that other reaction mechanisms may occur in an environment adjacent to the substrate surface, including kinetically less favorable reaction mechanisms, such as substitution reactions. Typically, the reaction conditions described are present at the exposed surface of the substrate 100 (the surface where the silicon carbide film 101 is deposited). They may also be present at a distance above the substrate 100, for example, at a distance of about 0.5 microns to about 150 mm above the substrate 100. In practice, the activation of the precursors can occur in the gas phase at a considerable distance above the substrate 100. Typically, the associated reaction conditions will be uniform or substantially uniform across the exposed surface of substrate 100, although some applications may allow for some variation.

[0033] In addition to the silicon-containing precursor, the environment near the workpiece (e.g., substrate 100) may include one or more free radical species, preferably free radical species in a substantially low energy state. Examples of these species include hydrogen radicals (i.e., atomic hydrogen radicals). In some embodiments, all, or substantially all, or a substantial portion of the atomic hydrogen radicals may be in the ground state, for example, at least about 90% or 95% of the atomic hydrogen radicals near the workpiece are in the ground state. In certain embodiments, the gas source is provided in a carrier gas (e.g., helium). As an example, hydrogen gas may be provided in a helium carrier at a concentration of about 1-10%. The pressure, the proportion of the carrier gas (e.g., helium), and other process conditions are selected so that the hydrogen atoms collide with the substrate 100 as free radicals in a low energy state that have not been recombined.

[0034] As explained elsewhere, hydrogen can be supplied to a remote plasma source to generate hydrogen atom radicals. The remote plasma source can be positioned upstream of the substrate surface and the environment adjacent to the substrate surface. Once generated, the hydrogen atom radicals can be in an excited energy state. For example, hydrogen in an excited energy state can have an energy of at least 10.2 eV (first excited state). Excited hydrogen atom radicals can cause non-selective decomposition of silicon-containing precursors. For example, hydrogen atom radicals in an excited state can easily destroy Si-H bonds, Si-Si bonds, Si-N bonds, Si-O bonds, and Si-C bonds, which can change the composition or physical properties or electrical properties of the silicon carbide film 101. In some embodiments, when the excited hydrogen atom radicals lose their energy or relax, the excited hydrogen atom radicals can become hydrogen atom radicals in a substantially low energy state or a ground state hydrogen atom radical. Hydrogen radicals in a substantially low energy state or ground state are capable of selectively destroying Si-H bonds and Si-Si bonds, while generally retaining Si-O bonds, Si-N bonds, and Si-C bonds. In some embodiments, process conditions may be provided such that the excited hydrogen radicals lose energy or relax to form hydrogen radicals in a substantially low energy state or ground state. For example, the remote plasma source or associated components may be designed such that the residence time of hydrogen radicals diffused from the remote plasma source to the substrate 100 is greater than the energetic relaxation time of the excited hydrogen radicals. The energetic relaxation time of the excited hydrogen radicals may be approximately equal to or less than approximately 1×10 -3 Second.

[0035] The state in which a considerable portion of hydrogen atomic radicals is in the ground state can be achieved by various techniques. As described below, some devices are designed to achieve this state. Device features and process control features can be tested and adjusted to produce a mild state in which a considerable portion of hydrogen atomic radicals is in the ground state. For example, the device can be operated and tested for charged particles downstream of the plasma source (i.e., near the substrate 100). The process and device can be adjusted until there is essentially no charged species near the substrate 100. In addition, the features of the device and process can be adjusted to a configuration in which these devices and processes begin to produce silicon carbide film 101 from a standard silicon-containing precursor. Relatively mild conditions that support the deposition of such a film are selected.

[0036] Other examples of free radical species include: oxygen-containing species, such as elemental oxygen radicals (atomic or diatomic); nitrogen-containing species, such as elemental nitrogen radicals (atomic or diatomic); and NH-containing radicals, such as ammonia radicals, wherein nitrogen is optionally incorporated into the film. Examples of NH-containing free radicals include, but are not limited to, free radicals of methylamine, dimethylamine, and aniline. The above-mentioned free radical species can be prepared from a source gas comprising a hydrogen-containing species, a nitrogen-containing species, an NH-containing species, or a mixture thereof. In some embodiments, substantially all or most of the atoms of the deposited film are provided by precursor molecules. In this case, the low-energy free radicals used to drive the deposition reaction can be entirely hydrogen or other species that do not substantially contribute to the quality of the deposited layer. In some embodiments, as discussed in further detail below, the free radical species can be generated by a remote plasma source. In some embodiments, some free radicals or even ions in higher energy states can potentially exist near the wafer plane.

[0037] In some embodiments, the process conditions utilize radical species in a substantially low energy state sufficient to break Si-H bonds and / or Si-Si bonds while substantially maintaining Si-O bonds, Si-N bonds, and Si-C bonds. Such process conditions may not have a significant amount of ions, electrons, or radical species in a high energy state (e.g., a state above the ground state). In some embodiments, the ion concentration in the region adjacent to the membrane is no more than about 10 7 / cm 3 The presence of a large number of ions or high-energy radicals can tend to break Si-O, Si-N, and Si-C bonds, which can produce films with non-ideal electrical properties (e.g., high dielectric constant and / or low breakdown voltage) and poor conformality. It is believed that the overly reactive environment produces reactive precursor fragments with high sticking coefficients (indicating a tendency to chemically or physically adhere to the sidewalls of the workpiece), leading to poor conformality.

[0038] In an environment adjacent to the substrate 100, the silicon-containing precursor is typically transported with other substances (particularly a carrier gas). In some implementations, the silicon-containing precursor exists together with free radical substances and other substances (including other active substances and / or carrier gases). In some embodiments, the silicon-containing precursor can be introduced as a mixture. Upstream of the deposition reaction surface, the silicon-containing precursor can be mixed with an inert carrier gas. Examples of inert carrier gases include, but are not limited to, argon (Ar) and helium (He). In addition, the silicon-containing precursor can be introduced into a mixture with a primary and secondary substance, and the secondary substance containing some elements or structural features (e.g., annular structure, cage structure, unsaturated bond, etc.) is present in the silicon carbide film 101 with a relatively low concentration. However, it should be understood that the secondary substance may not significantly affect the composition or structural features of the silicon carbide film 101. A variety of precursors can exist in equimolar or relatively similar ratios to be suitable for forming a primary backbone or matrix in the resulting silicon carbide film 101. In other embodiments, the relative amounts of different precursors significantly deviate from equimolar ratios.

[0039] In some embodiments, the one or more silicon-containing precursors provide substantially all of the mass of the deposited silicon carbide film 101, with a small amount of hydrogen or other elements from the remote plasma providing less than about 5 atomic percent of the film mass or less than about 2 atomic percent of the film mass. In some embodiments, only the radical species and the one or more silicon-containing precursors contribute to the composition of the deposited silicon carbide film 101. In other embodiments, the deposition reaction includes other co-reactants other than the one or more silicon-containing precursors and the radical species, which may or may not contribute to the composition of the deposited silicon carbide film 101. Examples of such co-reactants include carbon dioxide (CO), carbon monoxide (CO), water (H2O), methanol (CH3OH), oxygen (O2), ozone (O3), nitrogen (N2), nitrous oxide (N2O), ammonia (NH3), diazene (N2H2), methane (CH4), ethane (C2H6), acetylene (C2H2), ethylene (C2H4), diborane (B2H6), and combinations thereof. Such materials can be used as nitriding agents, oxidizing agents, reducing agents, and the like. In some cases, they can be used to adjust the amount of carbon in the deposited film by removing or adding a portion of the carbon provided with the silicon-containing precursor. In some embodiments employing non-hydrogen co-reactants, the co-reactant is introduced into the reaction chamber via the same flow path as the silicon-containing precursor; for example, a path including a gas outlet or a showerhead, generally not directly exposed to the plasma. In some embodiments, oxygen and / or carbon dioxide are introduced with the precursor to change the composition of the silicon carbide film 101 by removing carbon from the film or precursor during deposition. In some implementations employing non-hydrogen co-reactants, the co-reactant is introduced into the reaction chamber via the same flow path as hydrogen so that the co-reactant is at least partially converted into free radicals and / or ions. In such an implementation, both hydrogen radicals and co-reactant radicals react with one or more silicon-containing precursors to produce the deposited silicon carbide film 101.

[0040] In certain embodiments where a co-reactant is used and the co-reactant is introduced into the chamber together with the substance to be converted into free radicals (e.g., hydrogen), the co-reactant can be provided to the reaction chamber in a relatively small amount compared to the other gases in the reaction chamber, including the free radical source (e.g., hydrogen) and any one or more carrier gases (e.g., helium). For example, the co-reactant can be present in the process gas at a mass ratio of about 0.05% or less, or a mass ratio of about 0.01% or less, or a mass ratio of about 0.001% or less. For example, the reactant mixture (which enters the plasma source) can be about 10-20 liters / minute (L / m) of He, about 200-500 standard cubic centimeters / minute (sccm) of H2, and about 1-10 sccm of oxygen. However, it should be understood that in certain embodiments, the co-reactant can be present in the process gas at a ratio of about 0.05% by mass or more, or 1% by mass or more, or 20% by mass or more. When the co-reactant is introduced into the reaction chamber with the silicon-containing precursor (e.g., through a gas outlet or showerhead), the co-reactant can be present in a relatively high concentration, such as about 2 mass % or less, or about 0.1 mass % or less. When the co-reactant is a relatively weak reactant (e.g., a weak oxidant such as carbon dioxide), it can be present in even higher concentrations, such as about 10 mass % or less, or about 4 mass % or less. When the co-reactant is an additive or another precursor, it can be present in even higher concentrations, such as about 10 mass % or more, or about 20 mass % or more.

[0041] The temperature of the environment adjacent to substrate 100 can be any suitable temperature that promotes the deposition reaction, but is sometimes limited by the application of the device containing silicon carbide film 101. In some embodiments, during the deposition of silicon carbide film 101, the temperature of the environment adjacent to substrate 100 can be largely controlled by the temperature of the susceptor on which substrate 100 is supported. In some embodiments, the operating temperature can be between about 50°C and about 500°C. For example, in many integrated circuit applications, the operating temperature can be between about 250°C and about 400°C. In some embodiments, increasing the temperature can result in increased crosslinking on the substrate surface.

[0042] The pressure in the environment adjacent to substrate 100 can be any suitable pressure for generating active radicals in the reaction chamber. In some embodiments, the pressure can be about 35 Torr or less. For example, in embodiments where microwaves are used to generate the plasma, the pressure can be between about 10 Torr and about 20 Torr. In other examples, such as in embodiments where radio frequency (RF) is used to generate the plasma, the pressure can be less than about 5 Torr, or between about 0.2 Torr and about 5 Torr.

[0043] The environment adjacent to the substrate 100 facilitates the deposition of the silicon carbide film 101 on the substrate 100 by remote plasma CVD. A source gas is supplied to the remote plasma source, and power is provided to the remote plasma source, which power can cause the source gas to dissociate and generate ions and free radicals in an excited energy state. After excitation, the free radicals in the excited energy state relax into free radicals in a substantially low energy state or a ground state, such as a ground state hydrogen radical. The hydrogen radicals in the relaxed energy state can be used to selectively break bonds in the silicon-containing precursor. The hydrogen radicals in the relaxed energy state can be used to selectively break bonds in a co-reactant or another precursor to activate the co-reactant or another precursor.

[0044] Silicon carbide films are frequently used in semiconductor devices. For example, doped or undoped silicon carbide films can be used as metal diffusion barriers, etch stop layers, hardmask layers, gate spacers for source and drain implants, capping barriers for magnetoresistive random access memory (MRAM) or resistive random access memory (RRAM), and hermetic diffusion barriers in air gaps. Figures 1B-1E Shown are cross sections of structures containing silicon carbide films used in various applications. Figure 1B A thin film of silicon carbide is shown conformally deposited on features of a substrate. Figure 1C Silicon carbide vertical structures on the sidewalls of a gate electrode structure of a transistor are shown. Figure 1D Shown are vertical silicon carbide structures on the exposed copper line sidewalls in an air gap type metallization layer. Figure 1E Silicon carbide pore sealants for porous media materials are shown. Each of these applications will be discussed in further detail below. Chemical structure of the precursor

[0045] As discussed, the precursors employed in forming the silicon carbide film may include silicon-containing precursors, wherein at least some of the silicon-containing precursors have at least one Si-H bond and / or at least one Si-Si bond. In certain embodiments, the silicon-containing precursor has at most one hydrogen atom on each silicon atom. Thus, for example, a precursor having one silicon atom has at most one hydrogen atom bonded to the silicon atom; a precursor having two silicon atoms has one hydrogen atom bonded to one silicon atom and optionally another hydrogen atom bonded to a second silicon atom; a precursor having three silicon atoms has at least one hydrogen atom bonded to one silicon atom and optionally one or more hydrogen atoms bonded to the remaining one or two silicon atoms, and so on. However, in some embodiments, the silicon-containing precursor has two or more hydrogen atoms bonded to the silicon atom or to each silicon atom. Furthermore, the silicon-containing precursor may include at least one Si-O bond, at least one Si-N bond, and / or at least one Si-C bond. While any number of suitable precursors may be used during the formation of the silicon carbide film, at least some of the precursors will include a silicon-containing precursor having at least one Si-H bond or Si-Si bond and optionally at least one Si-O bond, Si-N bond, and / or Si-C bond. In various embodiments, one or more of the silicon-containing precursors does not contain an O-C bond or a N-C bond; for example, one or more of the precursors does not contain an alkoxy (-OR) group, where R is an organic group, such as a hydrocarbon group, or an amine (-NR1R2) group, where R1 and R2 are each independently hydrogen or an organic group. Such groups are believed to impart a high adhesion coefficient to the precursor or fragment in which they reside.

[0046] In certain embodiments, some of the carbon provided in the silicon carbide film can be provided by one or more hydrocarbon moieties on a silicon-containing precursor. These moieties can be selected from alkyl, alkenyl, alkynyl, aryl, and the like. In certain embodiments, the hydrocarbon group has a single carbon atom to minimize steric hindrance to Si-H and / or Si-Si bond breakage reactions during deposition. However, the precursor is not limited to a single carbon group; a larger number of carbon atoms, such as 2, 3, 4, 5, or 6 carbon atoms, can be used. In certain embodiments, the hydrocarbon group is linear. In certain embodiments, the hydrocarbon group is cyclic.

[0047] In certain embodiments, a portion of the carbon provided in the silicon carbide film can be provided by one or more hydrocarbon molecules in the carbon-containing precursor. Such hydrocarbon molecules can comprise carbon-carbon chains, wherein several carbon atoms can be used, for example, 2, 3, 4, 5, 6, or 7 carbon atoms. In some embodiments, the hydrocarbon molecules comprise one or more carbon double bonds and / or carbon triple bonds.

[0048] In some embodiments, the silicon-containing precursor falls within the chemical class It should be understood that other chemical classes of silicon-containing precursors may also be employed, and the silicon-containing precursors are not limited to the chemical classes discussed below.

[0049] In some embodiments, the silicon-containing precursor can be a siloxane. In some embodiments, the siloxane can be cyclic. Cyclic siloxanes can include cyclotetrasiloxanes, such as 2,4,6,8-tetramethylcyclotetrasiloxane (TMCTS), octamethylcyclotetrasiloxane (OMCTS) and hexamethylcyclotetrasiloxane (HMCTS). Other cyclic siloxanes can also include, but are not limited to, cyclotrisiloxane and cyclopentasiloxane. An embodiment using cyclic siloxanes is an annular structure that can introduce pores into the silicon carbide film, wherein the size of the pores corresponds to the radius of the ring. For example, the cyclotetrasiloxane ring can have a radius of about 6.7 angstroms.

[0050] In some embodiments, the siloxane may have a three-dimensional or cage-like structure. Figure 2 Representative examples of cage-shaped siloxane precursors are shown. Cage-shaped siloxanes have silicon atoms bridged to each other via oxygen atoms to form a polyhedron or any 3-D structure. An example of a cage-shaped siloxane precursor molecule is silsesquioxane. Cage-shaped siloxane structures are further described in detail in the co-owned U.S. Patent No. 6,576,345 of Cleemput et al., which is incorporated herein by reference in its entirety for all purposes. Similar to cyclic siloxanes, cage-shaped siloxanes can introduce pores into silicon carbide membranes. In some embodiments, the pore size is mesoporous.

[0051] In some embodiments, the siloxane can be linear. Examples of suitable linear siloxanes include, but are not limited to, disiloxanes (such as pentamethyldisiloxane (PMDSO) and tetramethyldisiloxane (TMDSO)); and trisiloxanes (such as hexamethyltrisiloxane, heptamethyltrisiloxane).

[0052] In some embodiments, the silicon-containing precursor can be an alkylsilane or other hydrocarbyl-substituted silane. The alkylsilane includes a central silicon atom, one or more alkyl groups bonded to the central silicon atom, and one or more hydrogen atoms bonded to the central silicon atom. In certain embodiments, any one or more of the alkyl groups contain 1 to 5 carbon atoms. The hydrocarbyl group can be saturated or unsaturated (for example, olefins (such as ethylene), alkynes, and aromatic groups). Examples include, but are not limited to, trimethylsilane (3MS), triethylsilane, pentamethyldisilane ((CH 3 ) 2Si-CH 2 -Si(CH 3 ) 3 ), and dimethylsilane (2MS).

[0053] In some embodiments, the silicon-containing precursor can be an alkoxysilane. However, in some embodiments, it should be understood that the silicon-containing precursor is not an alkoxysilane to avoid the presence of an alkoxy group. Alkoxysilanes include a central silicon atom and one or more alkoxy groups bonded to the central silicon atom and one or more hydrogen atoms bonded to the central silicon atom. Examples include, but are not limited to, trimethoxysilane (TMOS), dimethoxysilane (DMOS), methoxysilane (MOS), methyldimethoxysilane (MDMOS), diethoxymethylsilane (DEMS), dimethylethoxysilane (DMES), and dimethylmethoxysilane (DMMOS).

[0054] Disilane, trisilane or other higher silanes can be used instead of monosilane. An example of such a disilane from the alkylsilane class is hexamethyldisilane (HMDS). Another example of a disilane from the alkylsilane class can include pentamethyldisilane (PMDS). Other types of alkylsilanes can include alkylcarbosilanes, which can have a branched polymeric structure having a carbon bonded to a silicon atom and an alkyl bonded to the silicon atom. Examples include dimethyltrimethylsilylmethane (DTMSM) and bis-dimethylsilylethane (BDMSE). In some embodiments, one of the silicon atoms can have a carbon-containing group or a hydrocarbon-containing group connected to it, and one of the silicon atoms can have a hydrogen atom connected to it.

[0055] In some embodiments, the silicon-containing precursor can be a nitrogen-containing compound, such as silicon nitride (e.g., silazane). Typically, this compound contains carbon, but is only bonded to silicon atoms, not to nitrogen atoms. In certain embodiments, the nitrogen-containing compound does not have any carbon-nitrogen bond. In certain embodiments, the nitrogen-containing compound does not have any amine moiety (-C-NR1R2), wherein R1 and R2 are identical or different groups, such as hydrogen atoms and hydrocarbon groups (e.g., alkyl, alkenyl, or alkynyl). Examples of suitable silicon-nitrogen precursors include various silazanes, such as cyclic and linear silazanes, which contain one or more hydrocarbon moieties bonded to one or more silicon atoms and one or more hydrogen atoms bonded to one or more silicon atoms. Examples of silazanes include methyl-substituted disilazane and trisilazanes, such as tetramethyldisilazane and hexamethyltrisilazane.

[0056] During the deposition of silicon carbide, a variety of silicon-containing precursors may be present in the process gas. For example, siloxane and alkylsilane may be used together, or siloxane and alkoxysilane may be used together. The relative proportions of the various precursors may be selected based on the chemical structure of the selected precursors and the application of the resulting silicon carbide film. For example, as discussed in more detail below, the mole percentage of siloxane may be greater than the mole percentage of silane to produce a porous film.

[0057] For depositing oxygen-doped silicon carbide films, examples of suitable precursors may include cyclic siloxanes, such as cyclotetrasiloxanes (e.g., heptamethylcyclotetrasiloxane (HMCTS) and tetramethylcyclotetrasiloxane). Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxane and cyclopentasiloxane. For depositing oxygen-doped silicon carbide films, other examples of suitable precursors include linear siloxanes, such as, but not limited to, disiloxanes, such as pentamethyldisiloxane (PMDSO), tetramethyldisiloxane (TMDSO), hexamethyltrisiloxane, and heptamethyltrisiloxane.

[0058] For the deposition of undoped silicon carbide films, examples of suitable precursors may include monosilanes substituted with one or more alkane, alkene, and / or alkyne groups containing, for example, 1-5 carbon atoms. Examples include, but are not limited to, trimethylsilane (3MS), dimethylsilane (2MS), triethylsilane (TES), and pentamethyldisilane. Furthermore, disilane, trisilane, or other higher silanes may be used in place of monosilane. Examples of disilanes include hexamethyldisilane (HMDS) and pentamethyldisilane (PMDS). Other types of alkylsilanes may include alkylcarbosilanes. Examples include dimethyltrimethylsilylmethane (DTMSM) and bis-dimethylsilylethane (BDMSE).

[0059] For the deposition of nitrogen-doped silicon carbide films, examples of suitable precursors may include silazanes, such as alkyldisilazanes, and possibly compounds containing an amino group (-NH2) and an alkyl group, each bonded to one or more silicon atoms. Alkyldisilazanes contain silazane and an alkyl group bonded to two silicon atoms. One example includes 1,1,3,3-tetramethyldisilazane (TMDSN).

[0060] As explained, the silicon-containing precursor is selected to provide a highly conformal silicon carbide film. It is believed that a silicon-containing precursor with a low sticking coefficient is capable of producing a highly conformal film. "Stick-on coefficient" is a term used to describe the ratio of the number of adsorbed species (e.g., fragments or molecules) that adsorb / adhere to a surface compared to the total number of species that strike the surface in the same period of time. Symbol S c Sometimes used to refer to the adhesion coefficient. S cThe value of is between 0 (meaning none of the material adheres) and 1 (meaning all of the impinging material adheres). A variety of factors affect the adhesion coefficient, including the type of impinging material, the surface temperature, the surface coverage, the structural details of the surface, and the kinetic energy of the impinging material. Some materials are inherently more "adhesive" than others, making them more likely to adsorb to the surface each time the material impacts the surface. These more adhesive materials have a larger adhesion coefficient (all other factors being equal) and are more likely to adsorb near the entrance of the recessed feature than less adhesive, sticky materials with lower adhesion coefficients. In some cases, the adhesion coefficient of the precursor (under relevant deposition conditions) may be about 0.05 or less, such as about 0.001 or less. Device

[0061] One aspect of the present invention is an apparatus configured to implement the methods described herein. Suitable apparatus include hardware for implementing the process operations and a system controller having instructions for controlling the process operations according to the present invention. In some embodiments, the apparatus for performing the aforementioned process operations may include a remote plasma source. Compared to direct plasma, a remote plasma source provides milder reaction conditions. Examples of suitable remote plasma apparatus are described in U.S. Patent Application No. 14 / 062,648, filed October 24, 2013, which is incorporated herein by reference in its entirety and for all purposes.

[0062] Figure 3 A schematic diagram of a remote plasma apparatus according to certain embodiments is shown. The apparatus 300 includes a reaction chamber 310 having a showerhead 320. Inside the reaction chamber 310, a substrate 330 rests on a pedestal or base 335. In some embodiments, the base 335 may be equipped with heating / cooling elements. A controller 340 may be connected to the components of the apparatus 300 to control the operation of the apparatus 300. For example, the controller 340 may include instructions for controlling process conditions for the operation of the apparatus 300, such as temperature process conditions and / or pressure process conditions. In some embodiments, the controller 340 may include instructions for controlling the flow rates of precursor gases, co-reactant gases, source gases, and carrier gases. The controller 340 may include instructions for varying the flow rate of the co-reactant gases over time. Additionally or alternatively, the controller 340 may include instructions for varying the flow rate of the precursor gases over time. A more detailed description of the controller 340 is provided below.

[0063] In operation, a gas or gas mixture is introduced into the reaction chamber 310 via one or more gas inlets coupled to the reaction chamber 310. In some embodiments, two or more gas inlets are coupled to the reaction chamber 310. A first gas inlet 355 can be coupled to the reaction chamber 310 and connected to the container 350, and a second gas inlet 365 can be coupled to the reaction chamber 310 and connected to the remote plasma source 360. In embodiments including a remote plasma configuration, the delivery lines for the precursor and the radical species generated in the remote plasma source are separate. Thus, the precursor and radical species do not substantially interact before reaching the substrate 330. It should be understood that in some embodiments, the gas lines can be reversed so that the container 350 can provide the precursor gas flow via the second gas inlet 365, while the remote plasma source 360 ​​can provide the ions and radicals via the first gas inlet 355.

[0064] One or more free radical species may be generated in a remote plasma source 360 ​​and configured to enter the reaction chamber 310 via a second gas inlet 365. Any type of plasma source may be used in the remote plasma source 360 ​​to create the free radical species. This includes, but is not limited to, capacitively coupled plasma, inductively coupled plasma, microwave plasma, DC plasma, and laser generated plasma. An example of a capacitively coupled plasma may be a radio frequency (RF) plasma. A high frequency plasma may be configured to operate at 13.56 MHz or higher. An example of such a remote plasma source 360 ​​may be a plasma source manufactured by Lam Research Corporation (Fremont, California). Another example of such a radio frequency remote plasma source 360 ​​may be manufactured by MKS Instruments of Wilmington, Massachusetts. It can operate at 440 kHz and can be provided as a subunit bolted onto a larger device for processing one or more substrates in parallel. In some embodiments, microwave plasma can be used as a remote plasma source 360, such as It is also manufactured by MKS Instruments. The microwave plasma can be configured to operate at a frequency of 2.45 GHz. The gas provided to the remote plasma source can include hydrogen, nitrogen, oxygen, and other gases as mentioned elsewhere herein. In certain embodiments, the hydrogen is provided in a carrier such as helium. As an example, the hydrogen can be provided in a helium carrier at a concentration of about 1-10% hydrogen.

[0065] A precursor may be provided in a container 350 and may be supplied to a showerhead 320 via a first gas inlet 355. The showerhead 320 distributes the precursor into the reaction chamber 310 toward a substrate 330. The substrate 330 may be positioned below the showerhead 320. It should be understood that the showerhead 320 may have any suitable shape and may have any number and arrangement of ports for distributing gas to the substrate 330. The precursor may be supplied to the showerhead 320 and ultimately to the substrate 330 at a controlled flow rate.

[0066] The one or more free radical species formed in the remote plasma source 360 ​​can be transported in a gas phase toward the substrate 330. The one or more free radical species can flow into the reaction chamber 310 through the second gas inlet 365. It should be understood that, as Figure 3 As shown, the second gas inlet 365 need not be transverse to the surface of the substrate 330. In some embodiments, the second gas inlet 365 may be directly above the substrate 330 or at another location. The distance between the remote plasma source 360 ​​and the reaction chamber 310 can be configured to provide mild reaction conditions so that the ionized species generated in the remote plasma source 360 ​​are substantially neutral, but at least some radical species in a substantially low energy state remain in the environment adjacent to the substrate 330. Such low energy radical species do not recombine to form stable compounds. The distance between the remote plasma source 360 ​​and the reaction chamber 310 can be a function of the aggressiveness of the plasma (e.g., determined in part by the source RF power level), the density of the gas in the plasma (e.g., if a high concentration of hydrogen atoms is present, a significant portion of them may recombine to form H2 before reaching the reaction chamber 310), and other factors. In some embodiments, the distance between the remote plasma source 360 ​​and the reaction chamber 310 can be between about 1 cm and 30 cm, for example, about 5 cm or about 15 cm.

[0067] In some embodiments, a co-reactant other than the primary silicon-containing precursor or hydrogen radical is introduced during the deposition reaction. In some embodiments, the apparatus is configured to introduce the co-reactant through the second gas inlet 365, in which case the co-reactant is at least partially converted into plasma. In some embodiments, the apparatus is configured to introduce the co-reactant through the showerhead 320 via the first gas inlet 355. Examples of co-reactants include oxygen, nitrogen, ammonia, carbon dioxide, carbon monoxide, and the like. The flow rate of the co-reactant can be varied over time to produce a composition gradient in the graded film.

[0068] Figure 4A schematic diagram of an exemplary plasma processing apparatus with a remote plasma source is shown according to certain other embodiments. Plasma processing apparatus 400 includes a remote plasma source 402 separated from a reaction chamber 404. Remote plasma source 402 is fluidically coupled to reaction chamber 404 via a multi-port gas distributor 406, which may also be referred to as a showerhead. Free radical species are generated in remote plasma source 402 and supplied to reaction chamber 404. One or more silicon-containing precursors are supplied to reaction chamber 404 downstream of remote plasma source 402 and multi-port gas distributor 406. The one or more silicon-containing precursors react with the free radical species in a chemical vapor deposition region 408 of reaction chamber 404 to deposit a silicon carbide film on the surface of substrate 412. Chemical vapor deposition region 408 includes an environment adjacent to the surface of substrate 412.

[0069] The substrate 412 is supported on a substrate support or pedestal 414. The pedestal 414 is movable within the reaction chamber 404 to position the substrate 412 within the chemical vapor deposition region 408. Figure 4 In the illustrated embodiment, pedestal 414 is shown elevating substrate 412 within chemical vapor deposition region 408. In certain embodiments, pedestal 414 may also adjust the temperature of substrate 412. Pedestal 414 may provide some selective control over thermally activated surface reactions on substrate 412.

[0070] Figure 4 A coil 418 is shown disposed around a remote plasma source 402, wherein the remote plasma source 402 includes an outer wall (e.g., a quartz dome). The coil 418 is electrically coupled to a plasma generator controller 422, which can be used to form and maintain a plasma within a plasma region 424 via inductively coupled plasma generation. In certain embodiments, the plasma generator controller 422 can include a power supply for supplying power to the coil 418, wherein the power can be in the range of approximately 1 to 6 kilowatts (kW) during plasma generation. In certain embodiments, electrodes or antennas used for parallel plate or capacitively coupled plasma generation can be used to generate a continuous supply of free radicals via plasma excitation, rather than using inductively coupled plasma generation. Regardless of the mechanism used to ignite and maintain the plasma within the plasma region 424, plasma excitation can be utilized to continuously generate free radical species during film deposition. In certain embodiments, hydrogen radicals are generated under approximately steady-state conditions during steady-state film deposition, but transients may occur at the beginning and end of film deposition.

[0071] When hydrogen or other source gas is supplied to the remote plasma source 402, a supply of hydrogen radicals can be continuously generated within the plasma region 424. Excited hydrogen radicals can be generated in the remote plasma source 402. If not re-excited or re-energized or recombined with other radicals, the excited hydrogen radicals lose their energy or relax. As a result, the excited hydrogen radicals can relax to form hydrogen radicals in a substantially low energy state or ground state.

[0072] The hydrogen or other source gas may be diluted with one or more additional gases. The one or more additional gases may be supplied to the remote plasma source 402. In certain embodiments, the hydrogen or other source gas is mixed with one or more additional gases to form a gas mixture, wherein the one or more additional gases may include a carrier gas. Non-limiting examples of additional gases may include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and nitrogen (N2). The one or more additional gases may support or stabilize a steady-state plasma state within the remote plasma source 402, or assist in the ignition or extinction process of a transient plasma. In some embodiments, diluting the hydrogen or other source gas with, for example, helium may facilitate a higher total pressure without causing an accompanying plasma breakdown. In other words, a diluted gas mixture of hydrogen and helium may facilitate a higher total gas pressure without increasing the plasma power supplied to the remote plasma source 402. As Figure 4 As shown, a source gas supply source 426 is fluidly coupled to the remote plasma source 402 to supply hydrogen or source gas. In addition, an additional gas supply source 428 is fluidly coupled to the remote plasma source 402 to supply one or more additional gases. The one or more additional gases may also include the co-reactant gas described above. Although Figure 4 The embodiments depict the gas mixture of the source gas and one or more additional gases being introduced through separate gas outlets, but it should be understood that the gas mixture can be introduced directly into the remote plasma source 402. That is, a premixed dilution gas mixture can be supplied to the remote plasma source 402 through a single gas outlet.

[0073] Gases (e.g., excited hydrogen and helium radicals and relaxed gases / radicals) flow from the remote plasma source 402 and into the reaction chamber 404 via a multi-port gas distributor 406. The gases within the multi-port gas distributor 406 and within the reaction chamber 404 are generally not subjected to continuous plasma excitation therein. In certain embodiments, the multi-port gas distributor 406 includes an ion filter and / or a photon filter. Filtering the ions and / or photons can reduce damage to the substrate, undesired re-excitation of molecules, and / or selective cracking or decomposition of silicon-containing precursors within the reaction chamber 404. The multi-port gas distributor 406 can have a plurality of gas ports 434 to diffuse the gas flow into the reaction chamber 404. In certain embodiments, the plurality of gas ports 434 can be spaced apart from one another. In certain embodiments, the plurality of gas ports 434 can be arranged as an array of regularly spaced channels or through-holes that extend through a plate separating the remote plasma source 402 from the reaction chamber 404. The plurality of gas ports 434 may smoothly disperse and diffuse the radicals exiting from the remote plasma source 402 into the reaction chamber 404 .

[0074] Typical remote plasma sources are located relatively far from the reaction vessel. Consequently, free radical annihilation and recombination (e.g., through wall collision events) can significantly reduce the number of reactive species. Conversely, in certain embodiments, the dimensions of the multiple gas ports 434 can be configured based on the mean free path or gas flow residence time under typical processing conditions to facilitate free radical entry into the reaction chamber 404. In certain embodiments, the openings of the multiple gas ports 434 can occupy between approximately 5% and approximately 20% of the exposed surface area of ​​the multi-port gas distributor 406. In certain embodiments, the multiple gas ports 434 can each have an axial length-to-diameter ratio between approximately 3:1 and 10:1, or between approximately 6:1 and 8:1. This aspect ratio can reduce the frequency of wall collisions of free radical species passing through the multiple gas ports 434 while providing sufficient time for most excited radical species to relax into ground-state free radical species. In certain embodiments, the dimensions of the multiple gas ports 434 can be configured so that the residence time of gas passing through the multi-port gas distributor 406 is greater than the typical energy relaxation time of excited radical species. The excited radical species of hydrogen source gas Figure 4 Zhong Keyou·H * Indicates that the ground state free radical species of hydrogen source gas are Figure 4 It can be represented by H.

[0075] In certain embodiments, excited radical species exiting the plurality of gas ports 434 may flow into a relaxation region 438, which is contained within the interior of the reaction chamber 404. The relaxation region 438 is located upstream of the chemical vapor deposition region 408 but downstream of the multi-port gas distributor 406. Substantially all, or at least 90%, of the excited radical species exiting the multi-port gas distributor 406 are converted into relaxed radical species within the relaxation region 438. In other words, substantially all of the excited radical species (e.g., excited hydrogen radicals) entering the relaxation region 438 become de-excited or converted into relaxed radical species (e.g., ground-state hydrogen radicals) before exiting the relaxation region 438. In certain embodiments, the process conditions or geometry of the relaxation region 438 may be configured such that the residence time (e.g., determined by the mean free path and average molecular velocity) of the radical species flowing through the relaxation region 438 results in the relaxed radical species flowing out of the relaxation region 438.

[0076] As the radical species are delivered from the multi-port gas distributor 406 to the relaxation zone 438, one or more silicon-containing precursors and / or one or more co-reactants can be introduced into the chemical vapor deposition zone 408. The one or more silicon-containing precursors can be introduced through the gas distributor or gas outlet 442, wherein the gas outlet 442 can be fluidly coupled to the precursor supply 440. The relaxation zone 438 can be contained within the space between the multi-port gas distributor 406 and the gas outlet 442. The gas outlet 442 can include openings spaced apart from each other so that the one or more silicon-containing precursors can be introduced in a direction parallel to the gas mixture flowing from the relaxation zone 438. The gas outlet 442 can be located downstream of the multi-port gas distributor 406 and the relaxation zone 438. The gas outlet 442 can be located upstream of the chemical vapor deposition zone 408 and the substrate 412. The chemical vapor deposition zone 408 is located within the interior of the reaction chamber 404 and between the gas outlet 442 and the substrate 412.

[0077] Substantially all of the one or more silicon-containing precursor streams can be prevented from mixing with excited radical species adjacent to the multi-port gas distributor 406. Relaxed or ground-state radical species mix with the one or more silicon-containing precursors in a region adjacent to the substrate 412. The chemical vapor deposition region 408 includes a region adjacent to the substrate 412 in which the relaxed or ground-state radical species mix with the one or more silicon-containing precursors. During CVD formation of the silicon carbide film, the relaxed or ground-state radical species mix with the one or more silicon-containing precursors in a vapor phase.

[0078] In certain embodiments, a co-reactant may be introduced from gas outlet 442 and flowed with one or more silicon-containing precursors. The co-reactant may include a carbon-containing precursor as described below. The co-reactant may be introduced downstream of remote plasma source 402. The co-reactant may be supplied from precursor supply 440 or other source (not shown) fluidically coupled to gas outlet 442. The co-reactant may be a carbon-containing precursor as described below. In certain embodiments, the co-reactant may be introduced from multi-port gas distributor 406 and flowed into reaction chamber 404 along with radical species generated in remote plasma source 402. This may include radicals and / or ions of the co-reactant gas provided in remote plasma source 402. The co-reactant may be supplied from additional gas supply 428.

[0079] The gas outlet 442 can be separated from the multi-port gas distributor 406 by a sufficient distance to prevent back diffusion or back flow of the one or more silicon-containing precursors. In certain embodiments, the gas outlet 442 can be separated from the plurality of gas ports 434 by a distance between about 0.5 inches and about 5 inches, or between about 1.5 inches and about 4.5 inches, or between about 1.5 inches and about 3 inches.

[0080] Process gases can be removed from reaction chamber 404 via outlet 448, which is configured to be fluidically coupled to a pump (not shown). Thus, excess silicon-containing precursors, co-reactants, radical species, and dilution and displacement or purge gases can be removed from reaction chamber 404. In certain embodiments, system controller 450 is in operative communication with plasma processing apparatus 400. In certain embodiments, system controller 450 includes a processor system 452 (e.g., a microprocessor) configured to execute instructions stored in a data system 454 (e.g., a memory). In certain embodiments, system controller 450 can communicate with plasma generator controller 422 to control plasma parameters and / or conditions. In certain embodiments, system controller 450 can communicate with pedestal 414 to control pedestal height and temperature. In some embodiments, the system controller 450 can control other processing conditions, such as RF power settings, frequency settings, duty cycle, pulse time, pressure within the reaction chamber 404, pressure within the remote plasma source 402, gas flow rates from the source gas supply 426 and the additional gas supply 428, gas flow rates from the precursor supply 440 and other sources, the temperature of the pedestal 414, and the temperature of the reaction chamber 404, among others.

[0081] The following Figure 4 Aspects of the controller 450 also apply to Figure 3Controller 340. Controller 450 may contain instructions for controlling the process conditions of the operation of plasma processing apparatus 400. Controller 450 will typically include one or more memory devices and one or more processors. The processors may include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, etc. Instructions for implementing appropriate control operations are executed on the processors. These instructions may be stored in a memory device associated with controller 450, or they may be provided over a network.

[0082] In certain embodiments, the controller 450 controls all or most of the activities of the plasma processing apparatus 400 described herein. For example, the controller 450 may control all or most of the activities of the plasma processing apparatus 400 associated with depositing a silicon carbide film and, optionally, other operations in a manufacturing process involving the silicon carbide film. The controller 450 may execute system control software comprising a set of instructions for controlling timing, gas composition, gas flow rate, chamber pressure, chamber temperature, RF power level, substrate position, and / or other parameters. In some embodiments, other computer programs, scripts, or programs stored on a memory device associated with the controller 450 may be employed. To provide relatively mild reaction conditions in the environment adjacent to the substrate 412, parameters such as RF power level, gas flow rate to the plasma region 424, gas flow rate to the chemical vapor deposition region 408, and timing of plasma ignition may be adjusted and maintained by the controller 450. Additionally, adjusting the substrate position may further reduce the presence of high-energy radical species in the environment adjacent to the substrate 412. In a multi-station reactor, the controller 450 may include different or identical instructions for different equipment stations, thereby enabling independent or synchronized operation of the equipment stations.

[0083] In some embodiments, the controller 450 may include instructions for, for example, flowing one or more silicon-containing precursors into the reaction chamber 404 through the gas outlet 442, providing a source gas to the remote plasma source 402, generating one or more radical species of the source gas in the remote plasma source 402, and introducing the one or more radical species in a substantially low energy state from the remote plasma source 402 into the reaction chamber 404 to react with the one or more silicon-containing precursors to deposit a silicon carbide film on the substrate 412. The one or more radical species in the environment of the reaction chamber 404 adjacent to the substrate 412 may be hydrogen radicals in a ground state. In some embodiments, the controller 450 may include instructions for flowing a co-reactant into the reaction chamber 404 along with the one or more silicon-containing precursors. The co-reactant may be a hydrocarbon molecule, and each of the one or more silicon-containing precursors may have at least two hydrogen atoms bonded to silicon atoms.

[0084] In some embodiments, the apparatus 400 may include a user interface associated with the controller 450. The user interface may include a display screen, a graphical software display of the apparatus 400 and / or process conditions, and user input devices such as a pointing device, a keyboard, a touch screen, a microphone, and the like.

[0085] The computer program code for controlling the operations described above may be written in any conventional computer readable programming language: for example, assembly language, C, C++, Pascal, Fortran or others. The compiled object code or script is executed by the processor to perform the tasks identified in the program.

[0086] The signals used to monitor the process may be provided by analog and / or digital input connections of the system controller.The signals used to control the process are output on analog and digital output connections of the processing system.

[0087] Typically, the methods described herein can be performed on a system comprising semiconductor processing equipment, such as one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems can be integrated with electronic devices for controlling their operation before, during, and after processing semiconductor wafers or substrates. Typically, the electronic device can be referred to as a "controller," which can control various elements or subcomponents of one or more systems. Depending on the processing requirements and / or the type of system, the controller can be programmed to control any process disclosed herein, including controlling process gas delivery, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, wafer transfer in and out tools and other transfer tools, and / or load locks connected to or interfaced with a specific system.

[0088] Broadly speaking, a controller can be defined as an electronic device having various integrated circuits, logic, memory and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, and the like. The integrated circuit can include a chip in the form of firmware that stores program instructions, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions can be instructions that communicate with the controller in various individually configured forms (or program files) and define operating parameters for performing a specific process on or for a semiconductor wafer or system. In some embodiments, the operating parameters can be part of a recipe defined by a process engineer for completing one or more processing steps during the preparation of one or more layers, materials (e.g., silicon carbide), surfaces, circuits, and / or dies of a wafer.

[0089] In some embodiments, the controller can be part of or coupled to a computer that is integrated with the system, coupled to the system, connected to the system via a network, or a combination thereof. For example, the controller can be in the "cloud" or all or part of a wafer fab host system that can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of manufacturing operations, review the history of past manufacturing operations, review trends or performance standards for multiple manufacturing operations, change parameters of the current process, set processing steps to follow the current process, or start a new process. In some instances, a remote computer (e.g., a server) can provide process recipes to the system via a network that can include a local network or the Internet. The remote computer can include a user interface that allows for input or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some instances, the controller receives instructions in the form of data that specify the parameters for each processing step to be performed during one or more operations. It should be understood that the parameters can be specific to the type of process to be performed and the type of tool to which the controller is configured to connect or control the tool type. Thus, as described above, the controller can be distributed, for example, by including one or more discrete controllers that are connected together via a network and work toward a common goal (e.g., the process and control described herein). Examples of distributed controllers for these purposes can be one or more integrated circuits within a chamber that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which combine to control the process within the chamber.

[0090] In addition to the silicon carbide deposition and processing described herein, example systems may also include plasma etch chambers or modules, deposition chambers or modules, spin cleaning chambers or modules, metal plating chambers or modules, cleaning chambers or modules, bevel edge etch chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etch (ALE) chambers or modules, ion implantation chambers or modules, track chambers or modules, and any other semiconductor processing system that may be associated with or used in the preparation and / or manufacture of semiconductor wafers.

[0091] As described above, depending on the process step or steps to be performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, combination tools, other tool interfaces, adjacent tools, adjacent tools, tools located throughout the fab, a host computer, another controller, or tools used in material handling for moving containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

[0092] The apparatus / processes described above can be used in conjunction with photolithographic patterning tools or processes, for example, for preparing or manufacturing semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, although not necessarily, these tools / processes will be used or operated together in a common manufacturing facility. Photolithographic patterning of films typically involves some or all of the following operations, each of which uses multiple available tools: (1) applying photoresist to a workpiece, i.e., a substrate, using a spin coating or spray coating tool; (2) curing the photoresist using a hot plate or oven or UV curing tool; (3) exposing the photoresist to visible light or ultraviolet light or x-ray lamps using a tool such as a wafer stepper; (4) developing the resist to selectively remove the resist and thereby pattern it using a tool such as a wet bench; (5) transferring the resist pattern to an underlying film or workpiece using a dry or plasma assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper. Remote plasma CVD using silicon-containing precursors and carbon-containing precursors

[0093] The deposition of silicon carbide films (including silicon carbonitride films) using ALD presents many challenges, including thermodynamic challenges that may make ALD of silicon carbide films difficult to achieve. In addition, the deposition rate of ALD is slow compared to typical CVD techniques and may not be desirable in the manufacturing process. In addition, it can be quite difficult to incorporate carbon into silicon-based films or silicon nitride-based films without compromising the step coverage, film density and / or film quality characteristics of the silicon carbide film. The present disclosure relates to the deposition of silicon carbide films using remote plasma CVD. In the present disclosure, the incorporation of carbon into silicon-based films or silicon nitride-based films can be achieved without forming any CC bonds and NC bonds. The presence of CC or NC bonds may adversely affect the characteristics of the silicon carbide film.

[0094] As described above, the deposition reaction for depositing the silicon carbide film may also include a co-reactant in addition to the silicon-containing precursor and the radical species. The introduction of the co-reactant can be used to adjust the composition of the silicon carbide film. The co-reactant can be made to flow into the reaction chamber together with the silicon-containing precursor, wherein the co-reactant can be made to flow downstream of the remote plasma source. For example, a gas outlet for introducing the silicon-containing precursor and the co-reactant can be located downstream of the remote plasma source. The remote plasma source is considered to be upstream of the substrate and the environment adjacent to the substrate. In some embodiments, the gas outlet for introducing the silicon-containing precursor and the co-reactant can be located downstream of the remote plasma source and upstream of the environment adjacent to the substrate.

[0095] In addition to the silicon-containing precursor, a co-reactant may be introduced as a second precursor. The second precursor has a chemical property for adjusting the composition of the silicon carbide film. In some embodiments, the second precursor has a chemical property for improving the step coverage of the silicon carbide film. The step coverage of the deposited silicon carbide film can be measured relative to one or more features of the substrate. As used herein, "feature" may refer to a non-planar structure on a substrate, which is typically a surface modified during semiconductor device processing operations. Examples of features include grooves, through-holes, pads, columns, domes, etc. Features typically have a certain aspect ratio (depth or height to width). In some embodiments, the step coverage of the silicon carbide film is at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0096] In some embodiments, the co-reactant is a hydrocarbon molecule. The co-reactant of the present disclosure may also be referred to as a carbon-containing precursor, which flows with the silicon-containing precursor. In some embodiments, the hydrocarbon molecule may be a short-chain hydrocarbon molecule having at least one double bond or at least one triple bond. For example, the hydrocarbon molecule comprises a carbon chain between 3 carbon atoms and 7 carbon atoms. The hydrocarbon molecule may comprise one or more unsaturated carbon bonds, such as one or more carbon-to-carbon double bonds or triple bonds. Therefore, the hydrocarbon molecule may comprise an alkene or alkynyl group. Examples of suitable hydrocarbon molecules include propylene, ethylene, butene, pentene, butadiene, pentadiene (e.g., 1,4-pentadiene), hexadiene, heptadiene, toluene, and benzene. Other examples of suitable hydrocarbon molecules include acetylene, propyne, butyne, pentyne (e.g., 1-pentyne), and hexyne (e.g., 2-hexyne).

[0097] The carbon-containing precursor may flow with one or more silicon-containing precursors. In some embodiments, each of the silicon-containing precursors does not have a C-O bond and a C-N bond. Each of the silicon-containing precursors may contain two or more Si-H bonds. In practice, each of the silicon-containing precursors has at least one silicon atom and two or more hydrogen atoms bonded thereto. Thus, the at least one silicon atom does not have more than two carbon atoms, nitrogen atoms, and / or oxygen atoms bonded thereto. Examples of silicon-containing precursors include, but are not limited to, silanes and higher silanes, or alkylsilanes and higher alkylsilanes. For example, the silicon-containing precursor may be silane, disilane, trisilane, methylsilane, or dimethylsilane. Thus, the silicon-containing precursor flowing with the carbon-containing precursor may be a silane-based precursor. The silane-based precursor has a silicon atom and four substituents bonded to the silicon atom. Of the four substituents on the silicon atom, at least two substituents are hydrogen.

[0098] The carbon-containing precursor and the silicon-containing precursor are introduced into the reaction chamber downstream of one or more free radical species. The free radical species can be generated in a remote plasma source upstream of a gas outlet for introducing the carbon-containing precursor and the silicon-containing precursor. The free radical species can include hydrogen radicals, wherein the hydrogen radicals are in a substantially low energy state or ground state when mixed or interacted with the carbon-containing precursor and the silicon-containing precursor.

[0099] When depositing a silicon carbide film by remote plasma CVD, most (if not all) of the Si-C bonds in the silicon carbide film can typically be provided by existing Si-C bonds in the silicon-containing precursor. This can limit the ability to adjust the composition of the silicon carbide film. Flowing a co-reactant with the silicon-containing precursor can add greater flexibility in adjusting the composition of the silicon carbide film so that more or less carbon can be incorporated into the silicon carbide film. However, in the case where the co-reactant is a carbon-containing precursor, the co-reactant does not contribute to adjusting the composition of the silicon carbide film or the co-reactant adds C-C bonds, C-O bonds, or C-N bonds that may adversely affect the electrical properties and / or step coverage of the silicon carbide film. In the present disclosure, the carbon-containing co-reactant and the silicon-containing precursor are selected so that the carbon-containing co-reactant contributes to adjusting the composition of the silicon carbide film without adding C-C bonds, C-O bonds, or C-N bonds. The carbon-containing co-reactant and the silicon-containing precursor add additional process knobs for adjusting the composition of the silicon carbide film, while maintaining or improving film quality, compared to silicon carbide films deposited using existing Si-C bonds in the silicon-containing precursor.

[0100] Hydrogen radicals in a substantially low energy state or ground state can interact with carbon-containing precursors and silane-based precursors. Without being limited by any theory, one of the kinetically more favorable reaction mechanisms in the deposition reaction includes hydrogen abstraction, which involves the selective cleavage of Si-H bonds in silane-based precursors. The hydrogen abstraction reaction results in an activated silane-based precursor. Without being limited by any theory, hydrogen radicals in a substantially low energy state or ground state can interact with alkyne or alkene groups in hydrocarbon molecules, resulting in the formation of activated alkanes (e.g., methane). In some cases, the hydrocarbon molecules are broken into short-chain hydrocarbon molecules or radicals. The activated alkanes contain carbon radicals as activation sites, and the activated silane-based precursors contain silicon radicals as activation sites, and these activation sites can react together to form Si-C bonds. Figure 5 An example of the chemical reaction between activated alkanes from carbon-containing precursors and activated silane-based precursors is shown.

[0101] Rather than being a passive spectator, the carbon-containing precursor can contribute significantly to the composition of the silicon carbide film. The carbon-containing precursor and byproducts of any reaction with hydrogen radicals in a substantially low energy state or ground state can be incorporated into the silicon carbide film in significant amounts. As used herein, with respect to the case where carbon from the carbon-containing precursor is incorporated into the silicon carbide film, the term "substantial amounts" can mean that the change in atomic concentration of carbon is equal to or greater than about 5% compared to a silicon carbide film deposited without the carbon-containing precursor. The contribution of carbon from the carbon-containing precursor avoids or minimizes the addition of C-C bonds. The silicon carbide film has no C-C bonds, or substantially no C-C bonds. In some embodiments, the percentage of C-C bonds in the silicon carbide film is equal to or less than about 2%, equal to or less than about 1%, equal to or less than about 0.5%, or even 0%.

[0102] The remote plasma CVD process of the present invention may comprise a remote hydrogen plasma, wherein hydrogen radicals interact with a carbon-containing precursor and a silicon-containing precursor downstream of the remote plasma source. In some embodiments, the remote hydrogen plasma may also comprise a remote nitrogen plasma or a remote oxygen plasma. A nitriding agent or an oxidizing agent may be added to the remote plasma source to generate nitrogen radicals or oxygen radicals, respectively. The nitriding agent may promote the formation of a silicon carbonitride (SiCN) film, while the oxidizing agent may promote the formation of a silicon oxycarbide (SiCO) film.

[0103] When forming a SiCN film, a nitriding agent and hydrogen may be provided to a remote plasma source. In some embodiments, a carrier gas (e.g., helium) is provided to the remote plasma source to mix with the nitriding agent and hydrogen. Free radicals of the nitriding agent and hydrogen may be generated in the remote plasma source. In some embodiments, the nitriding agent comprises nitrogen (N2) or ammonia (NH3). Free radicals of the nitriding agent may be introduced from the remote plasma source into the reaction chamber along the flow path of the hydrogen free radicals. The nitriding agent and hydrogen free radicals react with one or more silicon-containing precursors and co-reactants to form the SiCN film. Without being limited by any theory, amine free radicals or nitrogen free radicals interact with the activated silicon-containing precursor to form Si-N bonds. The SiCN film has no C-C bonds or substantially no C-C bonds, and has no C-N bonds or substantially no C-N bonds. In some embodiments, the percentage of C-C bonds or C-N bonds in the SiCN film is equal to or less than about 2%, equal to or less than about 1%, equal to or less than about 0.5%, or even 0%.

[0104] When forming a SiCO film, an oxidant and hydrogen can be provided to a remote plasma source. In some embodiments, a carrier gas (e.g., helium) is provided to the remote plasma source to mix with the oxidant and hydrogen. Free radicals of the oxidant and hydrogen can be generated in the remote plasma source. In some embodiments, the oxidant comprises carbon dioxide (CO2), carbon monoxide (CO), oxygen (O2), ozone (O3), or nitrous oxide (N2O). Free radicals of the oxidant can be introduced from the remote plasma source into the reaction chamber along the flow path of the hydrogen free radicals. The oxidant and hydrogen free radicals react with one or more silicon-containing precursors and co-reactants to form a SiCO film. Without being limited by any theory, the oxygen free radicals interact with the activated silicon-containing precursor to form Si-O bonds. The SiCO film does not have a C-C bond or substantially does not have a C-C bond, and does not have a C-O bond or substantially does not have a C-O bond. In some embodiments, the percentage of CC bonds or CO bonds in the SiCO film is equal to or less than about 2%, equal to or less than about 1%, equal to or less than about 0.5%, or even 0%.

[0105] Figure 6A Shown are FTIR spectra of remote plasma CVD of silicon carbide films using a silicon-containing precursor and varying amounts of a carbon-containing precursor. Figure 6B Shows Figure 6A A magnified view of a portion of the FTIR spectrum in FIG. A carbon-containing precursor and a silicon-containing precursor are provided downstream of a remote plasma. The remote plasma contains hydrogen radicals and nitrogen radicals. Figures 6A-6B In FIG. 1 , the FTIR spectrum shows several plots, a plot with the highest peak having a carbon-containing precursor with a flow rate of 0 sccm, a plot with the second highest peak having a carbon-containing precursor with a flow rate of 1 sccm, a plot with the third highest peak having a carbon-containing precursor with a flow rate of 3 sccm, a plot with the fourth highest peak having a carbon-containing precursor with a flow rate of 5 sccm, a plot with the fifth highest peak having a carbon-containing precursor with a flow rate of 10 sccm, a plot with the sixth highest peak having a carbon-containing precursor with a flow rate of 15 sccm, and a plot with the shortest peak having a carbon-containing precursor with a flow rate of 24 sccm. -1 The Si-N bond was observed at about 790 cm -1 The presence of Si-C bonds was observed.

[0106] In the absence of a carbon-containing precursor, a silicon nitride film is deposited when a silicon-containing precursor reacts with a remote plasma containing nitrogen radicals. The introduction of a carbon-containing precursor causes the formation of a silicon carbonitride film. The silicon carbonitride film contains both Si-N bonds and Si-C bonds. Figures 6A-6BAs shown, increasing the flow rate of the carbon-containing precursor increases the amount of Si-C bonds in the silicon carbonitride film. The Si-C bonds are a result of the carbon-containing precursor. While the presence of Si-C bonds typically results from a single silicon-containing precursor, the present invention can incorporate both a silicon-containing precursor and a carbon-containing precursor to form Si-C bonds in doped or undoped silicon carbide films.

[0107] Figure 7 TEM images of silicon carbide films deposited on substrate features using silicon-containing precursors and carbon-containing precursors are shown. The remote plasma contains hydrogen and nitrogen radicals. X-ray photoelectron spectroscopy (XPS) data can identify the presence of Figure 7 The composition of the deposited films, including the silicon carbide films in FIG. A summary of the XPS data compiled for the silicon carbide films is shown in Table 1. The elemental composition is expressed in atomic percent concentrations and shows the atomic percent ratios of carbon to silicon (C / Si), nitrogen to silicon (N / Si), and carbon to nitrogen (C / N). As shown in Table 1, the introduction of a carbon-containing precursor results in a doped silicon carbide film with a high carbon content. Table 1

[0108] The introduction of a second precursor, particularly a carbon-containing precursor, significantly improves the step coverage of the silicon carbide film. In some embodiments, the step coverage of the silicon carbide film is at least 75%, at least 80%, at least 85%, or at least 90%. Film quality and film density are also substantially maintained with the introduction of the carbon-containing precursor. For example, the film density can be equal to or greater than about 2.0 g / cm 3 . Structure and properties of deposited films

[0109] The deposited film comprises silicon, carbon, and in some cases, oxygen, nitrogen, and / or one or more other elements. In some embodiments, the atomic concentration of silicon is between approximately 15% and 45% (or approximately 25% and 40%), the atomic concentration of carbon is between approximately 10% and 50%, the atomic concentration of oxygen is between approximately 0% and 45%, and the atomic concentration of nitrogen is between approximately 0% and 45%. In one example, the atomic concentration of silicon is approximately 30%, the atomic concentration of oxygen is approximately 25%, and the atomic concentration of carbon is approximately 45%. In another example, the atomic concentration of silicon is approximately 30%, the atomic concentration of oxygen is approximately 45%, and the atomic concentration of carbon is approximately 25%. In another example, the film contains approximately 10-15% carbon and approximately 30-40% oxygen, both based on atomic concentrations. In all cases, the film contains some hydrogen. However, it should be understood that the relative atomic concentration of hydrogen is small, for example, equal to or less than approximately 5%. It should be understood that the relative atomic concentrations can vary depending on the choice of precursor. Silicon atoms form bonds with carbon atoms and optionally with nitrogen and / or oxygen atoms. In some embodiments, the deposited film contains more Si-C bonds than Si-N bonds. In some examples, the deposited film contains a ratio of Si-C bonds to Si-N bonds between about 0.5:1 and 3:1. In certain embodiments, the film density is between about 2 and 2.7 g / cm 3 between.

[0110] When using a carbon-containing precursor and a silicon-containing precursor having at least two hydrogen atoms bonded to a silicon atom, the relative atomic concentrations of silicon and carbon can be relatively high compared to other elements in the silicon carbide film. In some embodiments, the relative atomic concentration of silicon can be at least 25% or at least 30%, and the relative atomic concentration of carbon can be at least 25% or at least 30% or at least 40%. Furthermore, for the doped silicon carbide film, the relative atomic concentration of oxygen can be less than about 10%, and the relative atomic concentration of nitrogen can be less than about 10%.

[0111] In some embodiments, the internal structure of the precursor is maintained in the deposited film. This structure can retain all or most of the Si-C bonds, and Si-O bonds and / or Si-N bonds (if present) in the precursor, while linking or cross-linking individual precursor moieties through bonds present in the precursor molecule at the location of Si-H bonds and / or Si-Si bonds and / or through additional condensation reactions on the growth surface (if sufficient thermal energy is provided).

[0112] The process conditions described previously herein can provide highly conformal film structures. Relatively mild process conditions can minimize the degree of ion bombardment at the substrate surface, resulting in a lack of directionality in the deposition. Additionally, relatively mild process conditions can reduce the number of free radicals with high adhesion coefficients, which tend to adhere to the sidewalls of previously deposited layers or films. In certain embodiments, for aspect ratios of approximately 2:1 to 10:1, the silicon carbide film can be deposited with a conformality between approximately 25% and 100%, more typically between approximately 50% and 100%, and even more typically between approximately 80% and 100%. The conformality can be calculated by comparing the average thickness of the deposited film at the bottom, sidewalls, or top of a feature to the average thickness of the deposited film at the bottom, sidewalls, or top of the feature. For example, the conformality can be calculated by dividing the average thickness of the deposited film on the feature sidewalls by the average thickness of the deposited film at the feature top and multiplying by 100 to obtain a percentage. For some applications, a conformality between about 85% and 95% is sufficient. In some examples of depositing silicon carbide on features with aspect ratios between about 2:1 and about 4:1, the conformality is at least about 90%. Certain BEOL (back-end of line) processes fall into this category. In some examples of depositing silicon carbide on features with aspect ratios between about 4:1 and about 6:1, the conformality is at least about 80%. Certain pad deposition processes fall into this category. In some examples of depositing silicon carbide on features with aspect ratios between about 7:1 and about 10:1 (or even higher), the conformality is at least about 90%. Certain DRAM (dynamic random access memory) manufacturing processes fall into this category.

[0113] The process conditions can also provide a film structure with high breakdown voltage and low leakage current. By introducing a limited amount of oxygen or nitrogen into a SiC-type material, the leakage paths provided by Si-H bonds and / or Si-CH2-Si bonds can be blocked by the oxygen or nitrogen. The conduction modes in Si-O and Si-N can be different at low electric fields. This can provide improved electrical properties while maintaining a relatively low dielectric constant. In various embodiments, the film has an effective dielectric constant of about 5 or less, or about 4.0 or less, in some cases about 3.5 or less, in some cases about 3.0 or less, or even in some embodiments about 2.5 or less. The effective dielectric constant can depend on the bonding and density. In some embodiments, SiOC films are made with a dielectric constant of 6 or higher, especially when the carbon content is relatively high. If leakage current is a significant consideration, the SiOC film needs to have a dielectric constant of less than 5. The lower the dielectric constant, the worse its sealing, barrier, and thermal resistance properties. In certain embodiments where applications require low sealing and diffusion restrictions, excellent etch resistance, thermal stability, etc., silicon carbide films can be made dense and highly cross-linked. This can be achieved, for example, by a) depositing the film at relatively high temperatures, and / or b) providing a relatively high radical:precursor ratio. In some embodiments, silicon carbide films can be relatively thin and still serve as effective sealing and diffusion barriers.

[0114] In some embodiments, the deposited film can be porous. As previously discussed herein, silicon-containing precursors can include annular siloxanes and cage-shaped siloxanes. These precursors and other with significant internal open space can introduce significant porosity into the structure of the deposited film. The porosity in the deposited film can further reduce the dielectric constant. In some embodiments, the porosity of the deposited silicon carbide film is between approximately 20% to 50%. The pore size of the porous film can follow the pore size of annular or cage-shaped precursors. In some embodiments, the average hole size of the film is between approximately 5 angstroms to 20 angstroms, for example, approximately 16 angstroms. application

[0115] The present disclosure may be further understood by reference to the following applications directed to high quality silicon carbide films, which applications are intended to be purely exemplary. The present invention is not limited in scope by the specific applications, which are merely brief illustrations of aspects of the disclosure.

[0116] In some embodiments, a silicon carbide film can be deposited on exposed copper. In some embodiments of depositing a silicon carbide film, the reaction conditions adjacent to the substrate can be free of oxidants (such as O2, O3, and CO2), including their free radicals. Therefore, the silicon carbide film can be deposited directly on the exposed copper without oxidizing the copper (e.g., generating copper oxide). Such a film can serve as an etch stop layer, which can also serve as a copper diffusion barrier. The presence of the silicon carbide film can provide a sufficiently low dielectric constant with excellent leakage characteristics to serve as a diffusion barrier. The silicon carbide film itself or as a bilayer stack (e.g., a SiCO / SiNC bilayer deposited on exposed copper) can be an etch stop and / or diffusion barrier. In some embodiments, the silicon carbide film can be placed between adjacent metallization layers, typically produced by a damascene process. The silicon carbide film can withstand etching and can be sufficiently dense to minimize the diffusion of copper ions into adjacent areas of the dielectric material. In some embodiments, nitrogen can be incorporated into the film using nitrogen-containing precursors or plasma-activated nitrogen-containing radicals (such as elemental nitrogen radicals or amine radicals).

[0117] In such Figure 1B In some embodiments shown, a silicon carbide film 111 can be conformally deposited on features 112 of a substrate 110. Features 112 can be isolated or densely packed features, wherein features 112 can have a relatively small critical dimension (CD). In some embodiments, the features can have a CD of approximately 20 nm or less, approximately 10 nm or less, or approximately 5 nm or less. The aspect ratio of the height to the width of features 112 can be greater than 2:1, greater than 5:1, greater than 10:1, or greater than 20:1. The step coverage of the silicon carbide film 111 deposited on features 112 can be at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0118] In some embodiments, the silicon carbide film can be deposited as a vertical structure adjacent to a metal or semiconductor structure. The deposition of silicon carbide provides excellent step coverage along the sidewalls of the metal or semiconductor structure to create a vertical structure. In certain embodiments, the vertical structure can be referred to as a spacer or liner.

[0119] Figure 1C Figure 1 shows a cross section of a silicon carbide liner deposited on the sidewalls of a gate electrode structure of a transistor. Figure 1C As shown in FIG, the transistor may be a CMOS transistor having a silicon substrate 120 with a source 122 and a drain 123. A gate dielectric 124 may be deposited on the silicon substrate 120, and a gate electrode 125 may be deposited on the gate dielectric 124 to form the transistor. Silicon carbide spacers or liners 121 may be deposited on the sidewalls of the gate electrode 125 and the gate dielectric 124.

[0120] In another example, Figure 1D A cross-section of silicon carbide deposited on the sidewalls of exposed copper lines in an air gap type metallization layer is shown. Air gaps 130 can be introduced into an integrated circuit layer between copper lines 132, thereby reducing the effective k value of that layer. Silicon carbide liner 131 can be deposited on the sidewalls of copper lines 132, and a non-conformal dielectric layer 133 can be deposited over air gap 130, liner 131, and copper lines 132. Examples of such air gap type metallization layers are described in U.S. Patent Application Publication No. 2004 / 0232552 to Fei Wang et al., which is incorporated herein by reference in its entirety and for all purposes.

[0121] In some embodiments, a silicon carbide film can be deposited on the sidewalls of a patterned porous dielectric material. Ultra-low-k dielectric materials can be made of porous structures. The pores in such materials can provide access areas for metal during the deposition of subsequent layers, including the deposition of diffusion barriers containing metals such as tantalum (Ta). If too much metal migrates into the dielectric material, the dielectric material can provide a short circuit between adjacent copper metallization lines.

[0122] Figure 1E A cross-section of a silicon carbide film as a pore sealant for a porous dielectric material is shown. The porous dielectric layer 142 may have a plurality of grooves or through-holes cut into the porous dielectric layer 142 to form pores 140. A silicon carbide film 141 may be deposited along the pores 140 to effectively seal the pores 140. Sealing the pores 140 with the silicon carbide film 141 may avoid damage to the porous dielectric layer 142 that would otherwise be caused by other sealing techniques using plasma. The silicon carbide film 141 may be sufficiently dense to act as a pore sealant. In some embodiments, the etched dielectric material, such as the porous dielectric layer 142, may first be treated by a "k-restore" process, which exposes the porous dielectric layer 142 to UV radiation and a reducing agent. This restoration process is further described in commonly owned U.S. Patent Application Publication No. 2011 / 0111533 to Varadarajan et al., which is incorporated herein by reference in its entirety for all purposes. In another "k-restore" process, the porous dielectric layer 142 can be exposed to UV radiation and a chemical silanizing agent. This restoration process is further described in commonly owned U.S. Patent Application Publication No. 2011 / 0117678 to Varadarajan et al., which is incorporated herein by reference in its entirety and for all purposes. After the pores 140 are exposed to the restoration treatment, thereby making the surface more hydrophilic and providing a monolayer of material, a layer of conformally deposited silicon carbide film 141 can be deposited to effectively seal the pores of the porous dielectric layer 142.

[0123] In some embodiments, the silicon carbide film can be deposited as the ultra-low-k dielectric material itself. Ultra-low-k dielectrics are generally defined as those having a dielectric constant lower than 2.5. In such a configuration, the ultra-low-k dielectric material of silicon carbide can be a porous dielectric layer. The pores of the dielectric layer can be introduced by using cyclic or cage-like precursor molecules including cyclic siloxanes and silsesquioxanes. In one example, the porosity of the ultra-low-k dielectric layer of silicon carbide can be between about 20% and 50%. In addition, the ultra-low-k dielectric layer can have an average pore size of less than about 100 angstroms, such as an average pore size between about 5 angstroms and 20 angstroms. For example, the cyclosiloxane rings can have a radius of about 6.7 angstroms. Although increasing the number and size of the pores can reduce the dielectric constant, the mechanical integrity of the dielectric layer can be compromised if it is too porous. in conclusion

[0124] In the above description, numerous specific details are set forth to provide a thorough understanding of the presented embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other instances, well-known process operations are not described in detail in order not to obscure the present invention. Although the disclosed embodiments are described in conjunction with specific embodiments, it should be understood that this is not intended to limit the disclosed embodiments.

[0125] Although the above embodiments have been described in some detail for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be implemented within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the processes, systems, and apparatus of the provided embodiments. Therefore, the described embodiments are to be considered as illustrative rather than restrictive, and the embodiments should not be limited to the details given herein.

Claims

1. A method for depositing a silicon carbide film on a substrate, the method comprising: flowing a silicon-containing precursor into a reaction chamber and toward the substrate; flowing a carbon-containing precursor along with the silicon-containing precursor into the reaction chamber along a flow path that is not exposed to plasma, wherein the silicon-containing precursor and the carbon-containing precursor flow into the reaction chamber through a remote plasma source and one or more gas outlets downstream of a gas distributor for delivering radical species, wherein the carbon-containing precursor is a hydrocarbon molecule having one or more carbon-carbon double or triple bonds, and wherein a space between the gas distributor and the one or more gas outlets forms a relaxation region such that excited radical species exiting the gas distributor are converted into relaxed radical species in the relaxation region; generating excited radical species from a source gas in the remote plasma source, the excited radical species being generated upstream of the silicon-containing precursor and the carbon-containing precursor; and The excited radical species are introduced into the reaction chamber through the gas distributor and directed toward the substrate, wherein the excited radical species relax into the relaxed radical species in the relaxation zone to react with the silicon-containing precursor and the carbon-containing precursor, thereby forming a doped or undoped silicon carbide film on the substrate. 2 . The method of claim 1 , wherein the silicon-containing precursor has at least two hydrogen atoms bonded to a silicon atom.

3. The method of claim 1, wherein the hydrocarbon molecule comprises propylene, butene, pentene, butadiene, pentadiene, hexadiene, heptadiene, toluene, benzene, propyne, butyne, pentyne, or hexyne.

4. The method of claim 1, wherein the silicon-containing precursor is silane, disilane, trisilane, methylsilane, or dimethylsilane.

5. The method of claim 1, wherein the doped or undoped silicon carbide film has a conformality of between 80% and 100% in one or more recessed features of the substrate.

6. The method according to claim 1, wherein Introducing the excited radical species into the reaction chamber includes continuously introducing the excited radical species into the reaction chamber, wherein the relaxed radical species react with the silicon-containing precursor and the carbon-containing precursor in a chemical vapor deposition reaction to form the doped or undoped silicon carbide film. The method of claim 1 , wherein the relaxed state radical species comprises a ground state hydrogen radical. 8 . The method of claim 1 , wherein a percentage of CC bonds in the doped or undoped silicon carbide film is equal to or less than 1% of the bonds of the doped or undoped silicon carbide film.

9. The method according to claim 1, further comprising: providing a nitriding agent with the source gas in the remote plasma source, wherein radicals of the nitriding agent are generated in the remote plasma source; and The radicals of the nitriding agent are introduced into the reaction chamber along with the excited radical species and directed toward the substrate, wherein the radical species and the relaxed radical species of the nitriding agent react with the silicon-containing precursor and the carbon-containing precursor to form a silicon carbonitride film.

10. The method of claim 9, wherein the nitriding agent comprises nitrogen or ammonia.

11. The method according to claim 1 , further comprising: providing an oxidant with the source gas in the remote plasma source, wherein radical species of the oxidant are generated in the remote plasma source; and The radical species of the oxidant and the excited radical species are introduced into the reaction chamber and directed toward the substrate, wherein the radical species of the oxidant and the relaxed radical species react with the silicon-containing precursor and the carbon-containing precursor to form a silicon oxycarbide film.

12. The method of claim 11, wherein the oxidant comprises carbon dioxide, carbon monoxide, oxygen, ozone, or nitrous oxide.

13. The method of claim 1, wherein the silicon-containing precursor is a silane-based precursor. The method according to claim 1 , wherein the silicon carbide film is undoped silicon carbide.

15. The method of claim 1, wherein the atomic concentration of silicon in the doped or undoped silicon carbide film is at least 25%, and wherein the atomic concentration of carbon in the doped or undoped silicon carbide film is at least 25%.

16. The method of claim 1, wherein the substrate comprises one or more recessed features, and each of the one or more recessed features has an aspect ratio of at least 10:

1.

17. The method of claim 1, wherein the silicon-containing precursor (i) has no CO bonds and (ii) has no CN bonds.

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