Silicon carbide film deposition using remote plasma-based methods with silicon- and carbon-containing precursors

Abstract

A doped or undoped silicon carbide film may be deposited using remote plasma chemical vapor deposition (CVD) techniques. One or more silicon-containing precursors are provided to a reaction chamber. Free radical species, such as hydrogen free radical species, are provided in a substantially low energy state or ground state and interact 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, wherein 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

[0001] Incorporated by Reference

[0002] 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

[0003] Silicon carbide (SiC) films have unique physical, chemical and mechanical properties and are used in a variety of applications, especially in integrated circuit applications. Types of SiC films include oxygen-doped silicon carbide (also known as silicon oxycarbide), nitrogen-doped silicon carbide (also known as silicon carbonitride), and oxygen- and nitrogen-doped silicon carbide (also known as silicon carbon oxynitride), and undoped silicon carbide.

[0004] The background description provided here is for the purpose of generally presenting the context of the present disclosure. The work of the presently designated inventors is neither explicitly nor implicitly admitted to be prior art against 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

[0005] 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 together 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 also 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 directed toward the substrate, wherein the hydrogen radicals are in a ground state to react with the silicon-containing precursor and the co-reactant, thereby forming a doped or undoped silicon carbide film on the substrate.

[0006] 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 molecule has one or more carbon-carbon double or triple bonds. The hydrocarbon molecule comprises 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 C-C bond or substantially no C-C bond. In some embodiments, the method further comprises: providing a nitriding agent together with the hydrogen source gas in the remote plasma source, 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 to 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 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 method further comprises: providing an oxidant together with the hydrogen source gas in the remote plasma source, wherein free radicals of the oxidant are generated in the remote plasma source; and introducing the free radicals of the oxidant together with the free radicals of the hydrogen into the reaction chamber and directed to the substrate, wherein the oxidant 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 CC bonds and no or substantially no CO 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 CO bonds and (ii) has no CN bonds.

[0007] These and other embodiments are described further below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0009] Figure 1B Schematic cross-sectional views of exemplary doped or undoped silicon carbide films conformally deposited on features of a substrate are shown.

[0010] 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.

[0011] 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.

[0012] Figure 1E Schematic cross-sectional views of exemplary doped or undoped silicon carbide pore sealants for porous dielectric materials are shown.

[0013] Figure 2 Exemplary chemical structures of representative cage-type siloxane precursors are shown.

[0014] Figure 3 A schematic diagram of an exemplary plasma processing apparatus with a remote plasma source is shown according to some embodiments.

[0015] Figure 4 A schematic diagram of an exemplary plasma processing apparatus having a remote plasma source according to some other embodiments is shown.

[0016] Figure 5 An example of the chemical reaction between activated alkanes from carbon-containing precursors and activated silane-based precursors is shown.

[0017] Fig. 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.

[0018] Figure 6B Shows Fig. 6A A magnified view of a portion of the FTIR spectrum.

[0019] Figure 7 TEM images of silicon carbide films deposited on substrate features using silicon-containing precursors and carbon-containing precursors are shown. DETAILED DESCRIPTION

[0020] In the present disclosure, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate" and "partially manufactured integrated circuit" are used interchangeably. It should be understood by those of ordinary skill in the art that the term "partially manufactured integrated circuit" can refer to a silicon wafer during any of the many stages of integrated circuit manufacturing. Wafers or substrates used in the semiconductor device industry typically have a diameter of 200 mm or 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, etc.

[0021] introduction

[0022] The manufacture of semiconductor devices generally 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 oxycarbonitride 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% atoms of doping atoms, whether these atoms are atoms of oxygen, nitrogen, or other elements. The doping level provides the desired film properties.

[0023] 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 carbon oxide include silicon-containing molecules having silicon-hydrogen (Si-H) bonds and / or silicon-silicon (Si-Si) bonds, and silicon-oxygen (Si-O) bonds, and / or silicon-carbon (Si-C) bonds. Precursor molecules for depositing carbon nitride include silicon-containing molecules having silicon-hydrogen (Si-H) bonds and / or silicon-silicon (Si-Si) bonds, and silicon-nitrogen (Si-N) bonds, and / or silicon-carbon (Si-C) bonds. Precursor molecules for depositing carbon nitride silicon oxide include silicon-containing molecules having silicon-hydrogen (Si-H) bonds, and / or silicon-silicon (Si-Si) bonds, and 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 processing, in which plasma is provided directly in the vicinity of the substrate.

[0024] It has been found that depositing high quality silicon carbide films can present several challenges, such as providing a film 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.

[0025] Although the present invention is not limited by 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 adhesion 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 adhesion coefficients of the precursor molecules and their fragments can deposit silicon carbide films with poor step coverage because the active precursor fragments can disproportionately adhere to the upper regions of the sidewalls of the recessed features and other structures.

[0026] Dangling bonds can generate silanol groups (Si-OH) in the deposited silicon oxycarbide film or silicon oxycarbonitride film. Dangling bonds can also generate silylamine groups (Si-NH2) in the deposited silicon carbonitride film. Due to these functional groups, the film may have an unfavorably high dielectric constant. Film quality may also be affected because direct plasma conditions tend to extract carbon from the deposited film.

[0027] In addition, dangling bonds can produce increased silicon-hydrogen bonds (Si-H) in the deposited silicon carbide film. Destroyed Si-C bonds can be replaced with Si-H under direct plasma deposition conditions. The presence of Si-H bonds in the silicon carbide film can produce a film with poor electrical properties. For example, the presence of Si-H bonds can reduce the breakdown voltage and increase the leakage current because the Si-H bonds provide a leakage path for electrons.

[0028] Additionally, dangling bonds can result in uncontrolled chemical or morphological structures in the silicon carbide film. In some cases, such structures are dense filaments with low porosity or no pores, resulting in films with unacceptably high dielectric constants. The lack of porosity may be a result of direct plasma conditions breaking Si-C bonds and / or Si-O bonds in the cyclosiloxane that would otherwise provide porosity in the ultra-low k dielectric material.

[0029] 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 of low frequency, producing 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.

[0030] Typical PECVD processes are sometimes not suitable 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 the PECVD process to form silicon oxycarbide films.

[0031] The environment of the substrate surface during deposition

[0032] 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 produce 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 may 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 may contain 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.

[0033] Some applications using silicon carbide membranes are Figure 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 structure of an exemplary silicon-containing precursor will be discussed in further detail below.

[0034] 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 additional silicon-containing precursors may not necessarily contain Si-H or Si-Si bonds. These additional silicon-containing precursors may 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 used as active sites to form bonds between the silicon-containing precursor or other precursors in the deposited silicon carbide film 101. The broken bonds can also be used as sites for crosslinking in the heat treatment performed during or after deposition. Bonding and crosslinking at the active sites can together form a primary backbone or matrix in the resulting silicon carbide film 101.

[0035] In some embodiments, the process conditions can maintain or substantially maintain the Si-C bonds in the deposited silicon carbide film 101 layer, as well as the Si-O bonds and Si-N bonds if present. Therefore, the reaction conditions adjacent to the substrate 100 provide for selectively destroying Si-H bonds 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 co-reactants such as oxygen can extract carbon from Si-C bonds. It should be understood that other reaction mechanisms may occur in the environment adjacent to the substrate surface, including kinetically less favorable reaction mechanisms, such as substitution reactions. Typically, the reaction conditions described exist on the exposed surface of the substrate 100 (the surface where the silicon carbide film 101 is deposited). They may also exist at a certain distance above the substrate 100, for example, at about 0.5 microns to about 150 millimeters above the substrate 100. In fact, the activation of the precursor 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 entire exposed surface of substrate 100, although some applications may allow for some variation.

[0036] 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., hydrogen atom radicals). In some embodiments, all, or substantially all, or a considerable portion of the hydrogen atom radicals may be in the ground state, for example, at least about 90% or 95% of the hydrogen atom 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 can be provided in a helium carrier at a concentration of about 1-10%. The pressure, the ratio 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 without recombination.

[0037] 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 the hydrogen atom radical is generated, it 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 radical loses its energy or relaxes, the excited hydrogen atom radical can become a substantially low-energy state hydrogen atom radical or a ground state hydrogen atom radical. Hydrogen atom 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 so that the excited hydrogen atom radicals lose energy or relax to form hydrogen atom 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 atom radicals diffused from the remote plasma source to the substrate 100 is greater than the energetic relaxation time of the excited hydrogen atom radicals. The energetic relaxation time of the excited hydrogen atom radicals may be approximately equal to or less than approximately 1×10 -3 Second.

[0038] The state in which a considerable portion of hydrogen atom radicals are 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 atom radicals are 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 substantially no charged material 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 this film are selected.

[0039] Other examples of free radical species include: oxygen-containing species, such as elemental oxygen free radicals (atomic or diatomic); nitrogen-containing species, such as elemental nitrogen free radicals (atomic or diatomic); and NH-containing free radicals, such as ammonia free 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 by 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 substances 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.

[0040] In some embodiments, the process conditions use free 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 free 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 bonds, Si-N bonds, 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 an overly reactive environment produces reactive precursor fragments with a high sticking coefficient (indicating a tendency to chemically or physically stick to the sidewalls of a workpiece), resulting in poor conformality.

[0041] In the environment adjacent to the substrate 100, the silicon-containing precursor is usually transported with other substances (particularly 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 gas). In some embodiments, the silicon-containing precursor can be introduced as a mixture. In the 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 primary and secondary substances, and secondary substances containing some elements or structural features (for example, annular structures, cage structures, unsaturated bonds, etc.) are present in the silicon carbide film 101 with relatively low concentrations. However, it should be understood that the secondary substances 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 are significantly deviated from equimolar ratios.

[0042] In some embodiments, 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 mass of the film or less than about 2% atomic mass of the film. In some embodiments, only radical species and 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 one or more silicon-containing precursors and 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 (CO2), 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 using non-hydrogen co-reactants, the co-reactant is introduced into the reaction chamber through 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 using 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 a deposited silicon carbide film 101.

[0043] In certain embodiments where a co-reactant is used and the co-reactant is introduced into the chamber together with a substance to be converted into free radicals (e.g., hydrogen), the co-reactant may be provided to the reaction chamber in a relatively small amount compared to other gases in the reaction chamber including a free radical source (e.g., hydrogen) and any one or more carrier gases (e.g., helium). For example, the co-reactant may 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) may be about 10-20 liters / minute (L / m) of He, about 200-500 standard cubic centimeters / minute (sccm) of H2, and about 1-10sccm of oxygen. However, it should be understood that in certain embodiments, the co-reactant may 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 higher concentration; for example, 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 (e.g., about 10 mass % or more, or about 20 mass % or more).

[0044] The temperature in the environment adjacent to the substrate 100 can be any suitable temperature that promotes the deposition reaction, but is sometimes limited by the application of the device containing the silicon carbide film 101. In some embodiments, during the deposition of the silicon carbide film 101, the temperature in the environment adjacent to the substrate 100 can be largely controlled by the temperature of the susceptor on which the 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 surface of the substrate.

[0045] The pressure in the environment adjacent to the substrate 100 can be any suitable pressure for generating active free radicals in the reaction chamber. In some embodiments, the pressure can be about 35 Torr or less. For example, as 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.

[0046] The environment adjacent to the substrate 100 facilitates the deposition of the silicon carbide film 101 on the substrate 100 by remote plasma CVD. The source gas is supplied to the remote plasma source, and power is provided to the remote plasma source, which can dissociate the source gas and generate ions and free radicals in an excited energy state. After excitation, the free radicals in the excited energy state relax to 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 the bonds in the silicon-containing precursor. The hydrogen radicals in the relaxed energy state can be used to selectively break the bonds in the co-reactant or another precursor to activate the co-reactant or another precursor.

[0047] Silicon carbide films are often used in semiconductor devices. For example, doped or undoped silicon carbide films can be used as metal diffusion barriers, etch stop layers, hard mask 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 at air gaps, etc. Figure 1B-1E Shown is a cross section of a structure containing a silicon carbide film for various applications. Figure 1B A thin film of silicon carbide is shown conformally deposited on a feature of a substrate. Figure 1C Silicon carbide vertical structures on the sidewalls of a gate electrode structure of a transistor are shown. Figure 1D Silicon carbide vertical structures on the exposed copper line sidewalls in an air gap type metallization layer are shown. Figure 1E Silicon carbide pore sealants for porous media materials are shown. Each of these applications will be discussed in further detail below.

[0048] Chemical structure of the precursor

[0049] As discussed, the precursors used 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. In addition, 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 do not contain an OC bond or a NC bond; for example, one or more of the precursors do 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. It is believed that such a group can provide a high adhesion coefficient to the precursor or fragment in which it resides.

[0050] In certain embodiments, some of the carbon provided in the silicon carbide film can be provided by one or more hydrocarbon moieties on the silicon-containing precursor. These moieties can be selected from alkyl, alkenyl, alkynyl, aryl, etc. In certain embodiments, the hydrocarbon group has a single carbon atom to minimize the steric hindrance of the cleavage reaction of Si-H and / or Si-Si bonds 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.

[0051] 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 include carbon-carbon chains, in which several carbon atoms can be used, such as 2, 3, 4, 5, 6, or 7 carbon atoms. In some embodiments, the hydrocarbon molecules include one or more carbon double bonds and / or carbon triple bonds.

[0052] In some embodiments, the silicon-containing precursor falls into a 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.

[0053] 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 in which pores can be introduced into a silicon carbide film, wherein the size of the pores corresponds to the radius of the ring. For example, a cyclotetrasiloxane ring can have a radius of about 6.7 angstroms.

[0054] 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 polyhedra 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. 6576345 of Cleemput et al., which is incorporated herein by reference 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.

[0055] In some embodiments, the siloxane may 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).

[0056] 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 (e.g., olefins (such as ethylene), alkynes and aromatic groups). Examples include, but are not limited to, trimethylsilane (3MS), triethylsilane, pentamethyldisilane ((CH3)2Si-CH2-Si(CH3)3), and dimethylsilane (2MS).

[0057] In some embodiments, the silicon-containing precursor can be an alkoxysilane. However, in some embodiments, it is 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).

[0058] Disilane, trisilane or other higher silanes can be used instead of monosilane. An example of such a disilane from alkylsilanes is hexamethyldisilane (HMDS). Another example of a disilane from alkylsilanes can include pentamethyldisilane (PMDS). Other types of alkylsilanes can include alkylcarbosilanes, which can have a branched polymeric structure with a carbon bonded to a silicon atom and an alkyl bonded to a 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.

[0059] 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 bonds. 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.

[0060] 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 precursor and the application of the resulting silicon carbide film. For example, as discussed in more detail below, the molar percentage of the amount of siloxane may be greater than the molar percentage of the amount of silane to produce a porous film.

[0061] For depositing oxygen-doped silicon carbide films, examples of suitable precursors may include cyclosiloxanes, 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.

[0062] For the deposition of undoped silicon carbide films, examples of suitable precursors may include monosilanes substituted with one or more alkane, alkene, and / or alkynyl groups containing, for example, 1-5 carbon atoms. Examples include, but are not limited to, trimethylsilane (3MS), dimethylsilane (2MS), triethylsilane (TES), and pentamethyldisilane. In addition, disilane, trisilane, or other higher silanes may be used to replace 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).

[0063] For the deposition of nitrogen-doped silicon carbide films, examples of suitable precursors may include silazanes such as alkyldisilazanes, and possible compounds including amino groups (-NH2) and alkyl groups, each bonded to one or more silicon atoms. Alkyldisilazanes include silazanes and alkyl groups bonded to two silicon atoms. One example includes 1,1,3,3-tetramethyldisilazane (TMDSN).

[0064] As explained, the silicon-containing precursor is selected to provide a highly conformal silicon carbide film. It is believed that a silicon-containing precursor having a low sticking coefficient is capable of producing a highly conformal film. The "sticking coefficient" is a term used to describe the ratio of the number of adsorbed species (e.g., fragments or molecules) adsorbed / adhered to the 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 greater 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.

[0065] Device

[0066] One aspect of the present invention is a device configured to implement the method described herein. Suitable devices include hardware for implementing process operations and a system controller having instructions for controlling process operations according to the present invention. In some embodiments, the device for performing the aforementioned process operations may include a remote plasma source. Compared to direct plasma, the remote plasma source provides mild reaction conditions. Examples of suitable remote plasma devices are described in U.S. Patent Application No. 14 / 062,648 filed on October 24, 2013, which is incorporated herein by reference in its entirety and for all purposes.

[0067] Figure 3 A schematic diagram of a remote plasma device according to certain embodiments is shown. The device 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 a heating / cooling element. A controller 340 may be connected to the components of the device 300 to control the operation of the device 300. For example, the controller 340 may include instructions for controlling process conditions for the operation of the device 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 changing the flow rate of co-reactant gases over time. Additionally or alternatively, the controller 340 may include instructions for changing the flow rate of precursor gases over time. A more detailed description of the controller 340 is provided below.

[0068] 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 separated. Therefore, the precursor and the 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 a precursor gas flow via the second gas inlet 365, and the remote plasma source 360 ​​can provide ions and radicals via the first gas inlet 355.

[0069] One or more free radical species may be generated in the remote plasma source 360 ​​and configured to enter the reaction chamber 310 via the 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, direct current 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 plasma 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, hydrogen is provided in a carrier such as helium. As an example, hydrogen can be provided in a helium carrier at a concentration of about 1-10% hydrogen.

[0070] The 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 to the reaction chamber 310 toward a substrate 330. The substrate 330 may be located 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.

[0071] 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 transverser to the surface of the substrate 330. In some embodiments, the second gas inlet 365 may be directly above the substrate 330 or at other locations. 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 produced 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 no longer 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 there is a high concentration of hydrogen atoms, 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 may be between about 1 cm and 30 cm, such as about 5 cm or about 15 cm.

[0072] In some embodiments, a co-reactant that is not a primary silicon-containing precursor or hydrogen radical is introduced during the deposition reaction. In some embodiments, the device 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 device 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, etc. The flow rate of the co-reactant can be varied over time to produce a composition gradient in the gradient film.

[0073] 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 fluidly 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.

[0074] 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, the pedestal 414 is shown to have elevated the substrate 412 within the chemical vapor deposition region 408. In certain embodiments, the pedestal 414 may also adjust the temperature of the substrate 412. The pedestal 414 may provide some selective control over thermally activated surface reactions on the substrate 412.

[0075] 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 in a plasma region 424 by inductively coupled plasma generation. In certain embodiments, the plasma generator controller 422 may include a power supply that supplies power to the coil 418, wherein the power may be in the range of about 1 to 6 kilowatts (kW) during plasma generation. In certain embodiments, electrodes or antennas used for parallel plate or capacitively coupled plasma generation may be used to generate a continuous supply of free radicals by plasma excitation rather than using inductively coupled plasma generation. Regardless of the mechanism used to ignite and maintain a plasma in the plasma region 424, free radical species may be continuously generated using plasma excitation 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.

[0076] When hydrogen or other source gas is supplied to the remote plasma source 402, a supply of hydrogen radicals may be continuously generated within the plasma region 424. Excited hydrogen radicals may be generated in the remote plasma source 402. The excited hydrogen radicals lose their energy or relax if not re-excited or re-energized or recombined with other radicals. Thus, the excited hydrogen radicals may relax to form hydrogen radicals in a substantially low energy state or ground state.

[0077] One or more additional gases may be used to dilute hydrogen or other source gases. The one or more additional gases may be supplied to the remote plasma source 402. In certain embodiments, hydrogen or other source gases are 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 hydrogen or other source gases 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, source gas supply source 426 is fluidly coupled to remote plasma source 402 to supply hydrogen or source gas. In addition, additional gas supply source 428 is fluidly coupled to 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 a gas mixture of a source gas and one or more additional gases being introduced via separate gas outlets, but it should be understood that the gas mixture may be introduced directly into the remote plasma source 402. That is, a premixed dilution gas mixture may be supplied to the remote plasma source 402 via a single gas outlet.

[0078] Gases (e.g., excited hydrogen and helium radicals and relaxed gases / radicals) flow from the remote plasma source 402 and flow into the reaction chamber 404 via the 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 molecular re-excitation, 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 .

[0079] Typical remote plasma sources are far away from the reaction vessel. Therefore, free radical elimination and recombination (e.g., through wall collision events) can greatly reduce active species. In contrast, in certain embodiments, the size of multiple gas ports 434 can be configured based on the mean free path or gas flow residence time under typical processing conditions to assist free radicals to enter the reaction chamber 404 freely. In certain embodiments, the openings of multiple gas ports 434 can occupy an exposed surface area between about 5% and about 20% of the multi-port gas distributor 406. In certain embodiments, multiple gas ports 434 can each have an axial length to diameter ratio between about 3:1 and 10:1, or between about 6:1 and 8:1. This aspect ratio can reduce the wall collision frequency of free radical species passing through multiple gas ports 434, and at the same time provide sufficient time for most excited radical species to relax into ground-state free radical species. In certain embodiments, the size of 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 general energy relaxation time of excited radical species. The excited free radical species of the hydrogen source gas Figure 4 Zhong Keyou·H * Indicates that the ground state free radical species of the hydrogen source gas are Figure 4 It can be represented by ·H.

[0080] In certain embodiments, the 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 in 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., time determined by the mean free path and the average molecular velocity) of the radical species flowing through the relaxation region 438 causes the relaxed radical species to flow out of the relaxation region 438.

[0081] 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 may be introduced into the chemical vapor deposition zone 408. The one or more silicon-containing precursors may be introduced through a gas distributor or a gas outlet 442, wherein the gas outlet 442 may be fluidly coupled to the precursor supply 440. The relaxation zone 438 may be contained within a space between the multi-port gas distributor 406 and the gas outlet 442. The gas outlet 442 may include openings spaced apart from one another so that one or more silicon-containing precursor flows may be introduced in a direction parallel to the gas mixture flowing out of the relaxation zone 438. The gas outlet 442 may be located downstream of the multi-port gas distributor 406 and the relaxation zone 438. The gas outlet 442 may 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.

[0082] Substantially all of the one or more silicon-containing precursor streams may be prevented from mixing with excited radical species adjacent to the multi-port gas distributor 406. The 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 gas phase.

[0083] 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 source 440 or other source (not shown) fluidly 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 with free radical species generated in remote plasma source 402. This may include free 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 source 428.

[0084] 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 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 to about 5 inches, or between about 1.5 inches to about 4.5 inches, or between about 1.5 inches to about 3 inches.

[0085] Process gases may be removed from reaction chamber 404 via outlet 448, which is configured to be fluidly coupled to a pump (not shown). Thus, excess silicon-containing precursors, co-reactants, radical species, and dilution and replacement or purge gases may 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 may communicate with plasma generator controller 422 to control plasma parameters and / or conditions. In certain embodiments, system controller 450 may communicate with pedestal 414 to control pedestal height and temperature. In some embodiments, the system controller 450 may 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 source 426 and the additional gas supply source 428, gas flow rates from the precursor supply source 440 and other sources, the temperature of the pedestal 414, and the temperature of the reaction chamber 404, etc.

[0086] The following Figure 4 Aspects of the controller 450 are also applicable to Figure 3Controller 340. Controller 450 may contain instructions for controlling process conditions for the operation of plasma processing device 400. Controller 450 will typically include one or more memory devices and one or more processors. The processor 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 processor. These instructions may be stored in a memory device associated with controller 450, or they may be provided over a network.

[0087] In certain embodiments, the controller 450 controls all or most of the activities of the plasma processing device 400 described herein. For example, the controller 450 may control all or most of the activities of the plasma processing device 400 associated with depositing a silicon carbide film and optionally other operations in a manufacturing process containing a silicon carbide film. The controller 450 may execute system control software including grouped instructions for controlling timing, gas composition, gas flow rate, chamber pressure, chamber temperature, RF power level, substrate position, and / or other parameters. Other computer programs, scripts, or programs stored on a memory device associated with the controller 450 may be used in some embodiments. In order 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. In addition, 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, controller 450 may include different or identical instructions for different equipment stations, thereby enabling independent or synchronized operation of the equipment stations.

[0088] In some embodiments, the controller 450 may include instructions for, for example, flowing one or more silicon-containing precursors into the reaction chamber 404 via the gas outlet 442, providing a source gas into 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.

[0089] 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 a user input device such as a pointing device, a keyboard, a touch screen, a microphone, and the like.

[0090] 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.

[0091] 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.

[0092] Typically, the methods described herein can be performed on a system including 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 connected to a specific system through an interface.

[0093] Broadly speaking, a controller can be defined as an electronic device with various integrated circuits, logic, memory and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. 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 set 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 a part of a recipe defined by a process engineer for completing one or more processing steps during the preparation of one or more (kinds) of a wafer, a material (e.g., silicon carbide), a surface, a circuit, and / or a die.

[0094] In some embodiments, the controller can be part of or coupled to a computer that is integrated with the system, coupled to the system, or connected to the system via a network, or a combination of these. For example, the controller can be in the "cloud" or all or part of a wafer factory (fab) host system, which can allow remote access to wafer processing. The computer can enable remote access to the system to monitor the current progress of the manufacturing operation, check the history of past manufacturing operations, check the trends or performance standards of multiple manufacturing operations, change the parameters of the current processing, set the processing steps to follow the current processing or start a new process. In some instances, a remote computer (e.g., a server) can provide a process recipe to the system via a network, which can include a local network or the Internet. The remote computer can include a user interface that allows 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 of each processing step to be performed during one or more operations. It should be understood that the parameters can be for the type of process to be performed and the type of tool, and the controller is configured to connect or control the tool type. Thus, as described above, the controller may be distributed, for example, by including one or more discrete controllers that are networked together and work toward a common goal (e.g., the process and control described herein). Examples of distributed controllers for these purposes may 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) that combine to control the process within the chamber.

[0095] In addition to the silicon carbide deposition and processing described herein, example systems may also include plasma etching chambers or modules, deposition chambers or modules, spin cleaning chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfer edge etching 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 etching (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.

[0096] As described above, depending on one or more process steps to be performed by the tool, the controller can 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 factory, a host computer, another controller, or tools used in material handling of moving containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing facility.

[0097] The apparatus / process described above can be used in conjunction with a photolithographic patterning tool or process, e.g., for preparing or manufacturing semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, though 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 enables multiple available tools: (1) applying a 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 heating furnace or a 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 by 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.

[0098] Remote plasma CVD using silicon-containing precursors and carbon-containing precursors

[0099] 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 desired in the manufacturing process. In addition, it may 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.

[0100] 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 free 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 flow downstream of the remote plasma source. For example, the 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.

[0101] In addition to the silicon-containing precursor, a co-reactant may also 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. "Feature" as used herein may refer to a non-planar structure on a substrate, which is typically a surface modified during a semiconductor device processing operation. 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%.

[0102] 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-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).

[0103] 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 CO bond and a CN bond. Each of the silicon-containing precursors may contain two or more Si-H bonds. In fact, each of the silicon-containing precursors has at least one silicon atom and two or more hydrogen atoms bonded thereto. Therefore, the at least one silicon atom will 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. Therefore, 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 are bonded to the silicon atom. Among the four substituents on the silicon atom, at least two substituents are hydrogen.

[0104] 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 may 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 may 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.

[0105] When a silicon carbide film is deposited by remote plasma CVD, most (if not all) of the Si-C bonds in the silicon carbide film may typically be provided by existing Si-C bonds in the silicon-containing precursor. This may limit the ability to adjust the composition of the silicon carbide film. Flowing a co-reactant with the silicon-containing precursor may add greater flexibility in adjusting the composition of the silicon carbide film, so that more or less carbon may 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 the composition adjustment of the silicon carbide film or the co-reactant adds CC bonds, CO bonds, or CN bonds that may adversely affect the electrical properties and / or step coverage of the silicon carbide film. In the present disclosure, a carbon-containing co-reactant and a silicon-containing precursor are selected so that the carbon-containing co-reactant contributes to the composition adjustment of the silicon carbide film without adding CC bonds, CO bonds, or CN bonds. The carbon-containing co-reactant and the silicon-containing precursor add an additional process knob for adjusting the composition of the silicon carbide film, while maintaining or improving the film quality, compared to silicon carbide films deposited using existing Si-C bonds in the silicon-containing precursor.

[0106] 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 more kinetically favorable reaction mechanisms in the deposition reaction includes hydrogen abstraction, which involves the selective breaking 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, 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.

[0107] 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 large quantities. As used herein, for the case where carbon from a carbon-containing precursor is incorporated into the silicon carbide film, the term "large quantities" can refer to: the change in atomic concentration of carbon is equal to or greater than about 5% compared to the deposition of the silicon carbide film without the use of a carbon-containing precursor. The contribution of carbon from the carbon-containing precursor avoids the addition of CC bonds or minimizes them. The silicon carbide film has no CC bonds, or substantially no CC bonds. In some embodiments, the percentage of CC 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%.

[0108] The remote plasma CVD process of the present invention may include a remote hydrogen plasma, wherein hydrogen radicals interact with carbon-containing precursors and silicon-containing precursors downstream of the remote plasma source. In some embodiments, the remote hydrogen plasma may also include 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.

[0109] When forming the SiCN film, the nitriding agent and hydrogen can be provided to the 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 can 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 can be introduced into the reaction chamber from the remote plasma source along the flow path of the free radicals of hydrogen. The free radicals of the nitriding agent and hydrogen react with one or more silicon-containing precursors and co-reactants to form the SiCN film. Without being limited by any theory, amine radicals or nitrogen radicals interact with activated silicon-containing precursors to form Si-N bonds. The SiCN film does not have a CC bond or substantially does not have a CC bond, and does not have a CN bond or substantially does not have a CN bond. In some embodiments, the percentage of CC bonds or CN 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%.

[0110] When forming SiCO film, oxidant and hydrogen can be provided to remote plasma source. In some embodiments, carrier gas (e.g., helium) is provided to remote plasma source to mix with oxidant and hydrogen. Free radicals of oxidant and hydrogen can be generated in remote plasma source. In some embodiments, oxidant comprises carbon dioxide (CO2), carbon monoxide (CO), oxygen (O2), ozone (O3), or nitrous oxide (N2O). Free radicals of oxidant can be introduced into reaction chamber from remote plasma source along the flow path of free radicals of hydrogen. Free radicals of oxidant and hydrogen react with one or more silicon-containing precursors and co-reactants to form SiCO film. Without being limited by any theory, oxygen free radicals interact with activated silicon-containing precursors to form Si-O bonds. SiCO film does not have CC bond or substantially does not have CC bond, and does not have CO bond or substantially does not have CO 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%.

[0111] Fig. 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 Fig. 6A A carbon-containing precursor and a silicon-containing precursor are provided downstream of the remote plasma. The remote plasma contains hydrogen radicals and nitrogen radicals. Figure 6A-6B In FIG. 1 , the FTIR spectrum shows several plots, the plot with the highest peak has a carbon-containing precursor with a flow rate of 0 sccm, the plot with the second highest peak has a carbon-containing precursor with a flow rate of 1 sccm, the plot with the third highest peak has a carbon-containing precursor with a flow rate of 3 sccm, the plot with the fourth highest peak has a carbon-containing precursor with a flow rate of 5 sccm, the plot with the fifth highest peak has a carbon-containing precursor with a flow rate of 10 sccm, the plot with the sixth highest peak has a carbon-containing precursor with a flow rate of 15 sccm, and the plot with the shortest peak has a carbon-containing precursor with a flow rate of 24 sccm. The carbon-containing precursor may be formed at about 835 cm -1 The Si-N bond was observed at about 790 cm -1 The presence of Si-C bonds was observed.

[0112] 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. Figure 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 the result of the carbon-containing precursor. Although the presence of Si-C bonds is usually from a single silicon-containing precursor, the present invention can introduce a silicon-containing precursor and a carbon-containing precursor to form Si-C bonds in a doped or undoped silicon carbide film.

[0113] 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 Figure 7 The composition of the deposited films, including the silicon carbide films in . 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 concentration and shows the atomic percent ratios between carbon and silicon (C / Si), nitrogen and silicon (N / Si), and carbon and 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.

[0114] Table 1

[0115]

[0116] The introduction of the second precursor, especially the 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%. In the case of introducing the carbon-containing precursor, the film quality and film density are also substantially maintained. For example, the film density can be equal to or greater than about 2.0 g / cm 3 .

[0117] Structure and properties of deposited films

[0118] 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 about 15% and 45% (or about 25% to 40%), the atomic concentration of carbon is between about 10% and 50%, the atomic concentration of oxygen is between about 0% and 45%, and the atomic concentration of nitrogen is between about 0% and 45%. In one example, the atomic concentration of silicon is about 30%, the atomic concentration of oxygen is about 25%, and the atomic concentration of carbon is about 45%. In another example, the atomic concentration of silicon is about 30%, the atomic concentration of oxygen is about 45%, and the atomic concentration of carbon is about 25%. In another example, the film contains about 10-15% carbon and about 30-40% oxygen, both based on atomic concentration. In all cases, the film contains some hydrogen. However, it should be understood that the relative atomic concentration of hydrogen is small, such as equal to or less than about 5%. It should be understood that the relative atomic concentrations can vary depending on the choice of precursors. 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.

[0119] 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%. In addition, for doped silicon carbide films, 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%.

[0120] 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 parts through bonds where Si-H bonds and / or Si-Si bonds exist in the precursor molecule and / or through additional condensation reactions on the growth surface (if sufficient thermal energy is provided).

[0121] The process conditions described above herein can provide a highly conformal film structure. Relatively mild process conditions can minimize the degree of ion bombardment at the substrate surface so that the deposition lacks directionality. In addition, relatively mild process conditions can reduce the number of free radicals with a high adhesion coefficient, and free radicals with a high adhesion coefficient tend to adhere to the sidewalls of previously deposited layers or films. In certain embodiments, for aspect ratios of about 2: 1 to 10: 1, the silicon carbide film can be deposited with a conformality between about 25% and 100%, more typically between about 50% and 100%, and even more typically between about 80% and 100%. The conformality can be calculated by comparing the average thickness of the deposited film at the bottom, sidewall or top of a feature with the average thickness of the deposited film at the bottom, sidewall or top of a feature. For example, the conformality can be calculated by dividing the average thickness of the deposited film on the feature sidewall by the average thickness of the deposited film at the top of the feature 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%. Some 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%. Some 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%. Some DRAM (dynamic random access memory) manufacturing processes fall into this category.

[0122] 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 path provided by the Si-H bond and / or the Si-CH2-Si bond can be blocked by oxygen or nitrogen. The conduction mode in Si-O and Si-N may 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, about 3.5 or less in some cases, about 3.0 or less in some cases, and even about 2.5 or less in some embodiments. The effective dielectric constant may depend on the bond and density. In some embodiments, the SiOC film is made to have a dielectric constant of 6 or more, especially when the carbon content is relatively high. If leakage current is an important consideration, the SiOC film needs a dielectric constant of less than 5. The lower the dielectric constant, the worse its sealing and barrier and thermal resistance properties. In certain embodiments where applications require low sealing and diffusion limitation, 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.

[0123] 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 about 20% to 50%. The pore size of the porous film can follow the pore size of the annular or cage-shaped precursor. In some embodiments, the average hole size of the film is between about 5 angstroms to 20 angstroms, for example, about 16 angstroms.

[0124] application

[0125] The present disclosure may be further understood by reference to the following applications for 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 present disclosure.

[0126] 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 (for example, 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 a 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 double-layer stack (for example, a SiCO / SiNC double layer deposited on exposed copper) can be an etch stop and / or diffusion barrier. In some embodiments, a silicon carbide film can be placed between adjacent metallization layers that are 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 regions of the dielectric material. In some embodiments, nitrogen can be incorporated into the film by using nitrogen-containing precursors or plasma-activated nitrogen-containing radicals (such as elemental nitrogen radicals or amine radicals).

[0127] In such Figure 1B In some embodiments shown, the silicon carbide film 111 can be conformally deposited on the features 112 of the substrate 110. The features 112 can be isolated or densely packed features, wherein the features 112 can have a relatively small critical dimension (CD). In some embodiments, the features can have a CD equal to or less than about 20 nm, equal to or less than about 10 nm, or equal to or less than about 5 nm. The aspect ratio of the height to the width of the 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 the features 112 is at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99%.

[0128] 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.

[0129] Figure 1C 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. 1 , 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. A silicon carbide spacer or liner 121 may be deposited on the sidewalls of the gate electrode 125 and the gate dielectric 124.

[0130] 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 the 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 on air gap 130, liner 131, and copper lines 132. Examples of such air gap type metallization layers can be 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.

[0131] In some embodiments, the silicon carbide film can be deposited on the sidewalls of the patterned porous dielectric material. Ultra-low-k dielectric materials can be made of porous structures. The holes in such materials can provide access areas for metals 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 short circuits between adjacent copper metallization lines.

[0132] Figure 1E A cross section of a silicon carbide film as a hole 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 the holes 140. The silicon carbide film 141 may be deposited along the holes 140 to effectively seal the holes 140. Sealing the holes 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 as a hole sealant. In some embodiments, the etched dielectric material, such as the porous dielectric layer 142, may first be treated by a "k-recovery" process, which exposes the porous dielectric layer 142 to UV radiation and a reducing agent. The recovery process is further described in co-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 may be exposed to UV radiation and a chemical silylating agent. The restoration process is further described in co-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 may be deposited to effectively seal the pores of the porous dielectric layer 142.

[0133] In some embodiments, the silicon carbide film may be deposited as an ultra-low k dielectric material itself. Ultra-low k dielectrics are generally defined as materials having a dielectric constant lower than a dielectric constant of 2.5. In such a configuration, the ultra-low k dielectric material of silicon carbide may be a porous dielectric layer. The pores of the dielectric layer may 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 may be between about 20% and 50%. In addition, the ultra-low k dielectric layer may have an average pore size less than about 100 angstroms, such as an average pore size between about 5 angstroms and 20 angstroms. For example, a cyclosiloxane ring may have a radius of about 6.7 angstroms. Although increasing the number and size of the holes can reduce the dielectric constant, the mechanical integrity of the dielectric layer may be compromised if it is too porous.

[0134] in conclusion

[0135] In the above description, numerous specific details are described to provide a thorough understanding of the proposed embodiments. The disclosed embodiments may be practiced without some or all of these specific details. In other examples, 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 they are not intended to limit the disclosed embodiments.

[0136] Although the above-described embodiments have been described in detail for the purposes of clarity and understanding, it will be apparent that certain variations 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 devices of the provided embodiments. Therefore, the described embodiments should be considered 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: providing a substrate in a reaction chamber; flowing a silicon-containing precursor into the reaction chamber and toward the substrate, wherein the silicon-containing precursor has at least two hydrogen atoms bonded to silicon atoms; flowing a carbon-containing precursor into the reaction chamber along a flow path that is not exposed to plasma along with the silicon-containing precursor, wherein the silicon-containing precursor and the carbon-containing precursor flow into the reaction chamber through one or more gas outlets downstream of a remote plasma source, wherein the carbon-containing precursor is a hydrocarbon molecule having one or more carbon-carbon double or triple bonds; generating hydrogen radicals from a hydrogen source gas in the remote plasma source, the hydrogen radicals being generated upstream of the silicon-containing precursor and the carbon-containing precursor; as well as The hydrogen radicals are introduced into the reaction chamber and directed toward the substrate, wherein the hydrogen radicals are in a ground state 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 all or substantially all of the hydrogen radicals in the environment adjacent to the substrate are hydrogen radicals in the ground state.

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 comprises silane, disilane, trisilane, methylsilane, or dimethylsilane.

5. The method of claim 1, wherein the silicon-containing precursor having at least two hydrogen atoms bonded to the silicon atom does not have more than two carbon atoms, nitrogen atoms, and / or oxygen atoms bonded to the silicon atom. 6 . The method of claim 1 , wherein the doped or undoped silicon carbide film has no or substantially no CC bonds.

7. The method according to any one of claims 1 to 6, further comprising: providing a nitriding agent in the remote plasma source together with the hydrogen source gas, wherein radicals of the nitriding agent are generated in the remote plasma source; and The radicals of the nitriding agent and the radicals of hydrogen are introduced into the reaction chamber and directed toward the substrate, wherein the radicals of the nitriding agent and the radicals of hydrogen react with the silicon-containing precursor and the carbon-containing precursor to form a silicon carbonitride film. 8 . The method according to claim 7 , wherein the silicon carbonitride film has no or substantially no CC bonds and has no or substantially no CN bonds.

9. The method of claim 7, wherein the nitriding agent comprises nitrogen or ammonia.

10. The method according to any one of claims 1 to 6, further comprising: providing an oxidant in the remote plasma source along with the hydrogen source gas, wherein radicals of the oxidant are generated in the remote plasma source; and The radicals of the oxidant are introduced into the reaction chamber together with the radicals of hydrogen and directed toward the substrate, wherein the oxidant and the radicals of hydrogen react with the silicon-containing precursor and the carbon-containing precursor to form a silicon oxycarbide film. 11 . The method according to claim 10 , wherein the silicon oxycarbide film has no or substantially no CC bonds and has no or substantially no CO bonds.

12. The method of claim 10, wherein the oxidant comprises carbon dioxide, carbon monoxide, oxygen, ozone, or nitrous oxide.

13. The method of any one of claims 1-6, wherein the silicon-containing precursor is a silane-based precursor.

14. The method of any one of claims 1-6, wherein the doped or undoped silicon carbide film has a conformality of at least 75%.

15. The method according to any one of claims 1 to 6, wherein the silicon carbide film is undoped silicon carbide.

16. The method of any one of claims 1-6, 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%.

17. The method of any one of claims 1-6, wherein the silicon-containing precursor (i) has no CO bonds and (ii) has no CN bonds.

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